CN113707975A - Electrochemical device and electronic device comprising same - Google Patents

Electrochemical device and electronic device comprising same Download PDF

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Publication number
CN113707975A
CN113707975A CN202111021300.4A CN202111021300A CN113707975A CN 113707975 A CN113707975 A CN 113707975A CN 202111021300 A CN202111021300 A CN 202111021300A CN 113707975 A CN113707975 A CN 113707975A
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China
Prior art keywords
electrode assembly
negative
electrochemical device
face
pole piece
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CN202111021300.4A
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Chinese (zh)
Inventor
闫东阳
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Ningde Amperex Technology Ltd
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Ningde Amperex Technology Ltd
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Priority to CN202111021300.4A priority Critical patent/CN113707975A/en
Publication of CN113707975A publication Critical patent/CN113707975A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/14—Primary casings; Jackets or wrappings for protecting against damage caused by external factors
    • H01M50/145—Primary casings; Jackets or wrappings for protecting against damage caused by external factors for protecting against corrosion
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Secondary Cells (AREA)
  • Connection Of Batteries Or Terminals (AREA)

Abstract

The embodiment of the application provides an electrochemical device and an electronic device comprising the same, wherein the electrochemical device is coated on a part which is possibly contacted with a shell and corroded in a negative current collector through a first negative electrode active material, so that the risk of lithium intercalation corrosion reaction caused by contact between the shell and a negative electrode plate can be reduced, the corrosion resistance of the electrochemical device is effectively improved, and the safety performance of the electrochemical device is improved. Due to the existence of the first coating area, the risk of corrosion reaction caused by contact of the shell and the negative pole piece is reduced, on one hand, the use of an insulating part can be omitted, on the other hand, the distance between the shell and the negative pole piece can be reduced, so that the size of the electrochemical device is reduced, the energy density of the electrochemical device is improved, and the production cost of the electrochemical device is reduced.

Description

Electrochemical device and electronic device comprising same
Technical Field
The present disclosure relates to the field of electrochemistry, and more particularly, to an electrochemical device and an electronic device including the same.
Background
The aluminum element (Al) has the advantages of high ductility, easy processing, low cost and the like, and large-size lithium ion batteries generally adopt a composite material containing a large amount of Al as a shell. However, when the case is exposed to the electrolyte environment and simultaneously contacts with the negative electrode plate inside the lithium ion battery, a corrosion reaction occurs, and then the case is in a leakage risk. In addition, Al enters the inside of the electrode assembly and is deposited between the positive and negative pole pieces and the diaphragm, so that the lithium ion battery is easy to have safety risk.
In order to prevent the above problems, in the prior art, generally, at a position where a corrosion risk may occur in a lithium ion battery structure, a distance between a negative electrode plate and a case is designed to be relatively far, and meanwhile, an insulating member is arranged on the case or outside an electrode assembly for protection, which is not beneficial to improving energy density of the lithium ion battery.
Disclosure of Invention
An electrochemical device and an electronic device including the same are provided to improve corrosion resistance and energy density of the electrochemical device.
An embodiment of a first aspect of the present application provides an electrochemical device, which includes an electrode assembly and a housing accommodating the electrode assembly, wherein the electrode assembly includes a pole piece and a separator, the pole piece includes a positive pole piece and a negative pole piece, the separator is disposed between the positive pole piece and the negative pole piece, the electrode assembly is stacked by the positive pole piece, the separator and the negative pole piece, and an outermost pole piece of the electrode assembly is the negative pole piece. The negative pole piece comprises a negative pole current collector and a negative pole coating area, the negative pole coating area is arranged on the surface of the negative pole current collector and comprises a first coating area, a first negative pole active material is arranged in the first coating area, and the first negative pole active material is Li/Li+Is 1V to 3V.
The beneficial effects of the embodiment of the application are as follows: the first negative active material is coated on the part which is possibly contacted with the shell and corroded in the negative current collector, so that the risk of lithium intercalation corrosion reaction between the shell and the negative pole piece due to contact can be reduced, the corrosion resistance of the electrochemical device is effectively improved, and the safety performance of the electrochemical device is improved. Due to the existence of the first coating area, the risk of corrosion reaction caused by contact of the shell and the negative pole piece is reduced, on one hand, the use of an insulating part can be omitted, on the other hand, the distance between the shell and the negative pole piece can be reduced, and the size of the electrochemical device is reduced, so that the energy density of the electrochemical device is improved, and the production cost of the electrochemical device is reduced.
In some embodiments of the present application, the outermost layer of the electrode assembly is a negative electrode tab. The volume occupied by the electrode assembly can be reduced, and the energy density can be improved.
In some embodiments of the present application, the electrode assembly is stacked and wound by the positive electrode tab, the separator, and the negative electrode tab to be disposed in a wound structure, an end surface of the electrode assembly is parallel to an end surface of the case, the end surface of the electrode assembly includes an electrode assembly first end surface and an electrode assembly second end surface, the electrode assembly first end surface is parallel to the electrode assembly second end surface, and the electrode assembly first end surface is connected with the positive electrode terminal and the negative electrode terminal; the first coated region includes at least one of an edge region or a tail region, the edge region being located at the second end face of the electrode assembly; or the first coated region is a negative coated region. According to the embodiment of the application, the risk of corrosion reaction in the area of the shell corresponding to the first coating area in the electrochemical device can be reduced, and the corrosion resistance of the electrochemical device can be improved.
In some embodiments of the present application, the width of the negative electrode tab beyond the positive electrode tab on the second end face of the electrode assembly is a pitch width, and the width of the edge region is greater than or equal to the pitch width and less than the width of the negative electrode tab. By controlling the width of the edge region, the possibility of a decrease in energy density of the electrochemical device is reduced, and the corrosion resistance of the electrochemical device is effectively improved.
In some embodiments of the present application, the electrode assembly second end surface meets the case second end surface; the outermost pole piece of the electrode assembly is connected with the shell at the position closest to the shell. Therefore, the volume of the electrochemical device is reduced, the energy density is improved, the insulating part is saved, and the production cost of the electrochemical device is also reduced.
In some embodiments of the present application, the electrode assembly is stacked and wound by the positive electrode tab, the separator, and the negative electrode tab to be disposed in a wound structure, an end surface of the electrode assembly is perpendicular to an end surface of the case, the end surface of the electrode assembly includes an electrode assembly first end surface and an electrode assembly second end surface, the electrode assembly first end surface is parallel to the electrode assembly second end surface, the end surface of the case includes a case first end surface and a case second end surface, the case first end surface is parallel to the case second end surface; the first end face of the shell is provided with a positive terminal and a negative terminal, the positive terminal is connected to one side of the first end face of the electrode assembly, and the negative terminal is connected to one side of the second end face of the electrode assembly; the first coating region includes at least one of an edge region or a tail region disposed adjacent to a side of the negative terminal; or the first coated region is a negative coated region. Thus, the risk of corrosion reaction between the electrode assembly and the case is reduced, and the corrosion resistance of the electrochemical device is improved.
In some embodiments of the present application, the width of the edge region is equal to the difference between the negative coated region width of the negative electrode tab and the positive coated region width of the positive electrode tab in the first direction. By controlling the width of the edge region, the possibility of reducing the energy density of the electrochemical device is reduced, and the corrosion resistance of the electrochemical device is effectively improved.
In some embodiments of the present application, the electrode assembly first end face and the electrode assembly second end face are both contiguous with the case; the outermost pole piece of the electrode assembly is connected with the shell at the position closest to the shell. Therefore, the volume of the electrochemical device is reduced, the energy density is improved, the insulating part is saved, and the production cost of the electrochemical device is also reduced.
In some embodiments of the present application, the electrode assembly is stacked and wound by a positive electrode plate, a separator and a negative electrode plate to form a wound structure, the end surface of the electrode assembly is parallel to the end surface of the case, the end surface of the electrode assembly comprises an electrode assembly first end surface and an electrode assembly second end surface, the electrode assembly first end surface is parallel to the electrode assembly second end surface, the electrode assembly first end surface is connected with a positive electrode tab, and the electrode assembly second end surface is connected with a negative electrode tab; the first coated region comprises a finishing region; or the first coated region is a negative coated region. Thus, the corrosion resistance of the electrochemical device is improved, and the energy density and the production cost of the electrochemical device are improved.
In some embodiments of the present application, the outermost pole piece of the electrode assembly is joined to the casing proximate the casing. Therefore, the volume of the electrochemical device is reduced, the energy density is improved, the insulating part is saved, and the production cost of the electrochemical device is also reduced.
In some embodiments of the present application, the electrode assembly is stacked in a lamination structure by a positive electrode tab, a separator, and a negative electrode tab, a top surface of the electrode assembly is parallel to an end surface of the case on the first plane, and a positive electrode terminal and a negative electrode terminal are connected to the top surface of the electrode assembly; the first side surface and the second side surface of the electrode assembly on the second plane are respectively a negative pole piece; the first coating region includes at least one of an outer surface of the negative electrode tab at the first and second sides of the electrode assembly, an edge region at the third side of the electrode assembly on the third plane, an edge region at the fourth side of the electrode assembly on the third plane, or an edge region at the bottom of the electrode assembly on the first plane. Thus, the risk of corrosion reactions occurring in the corresponding region of the electrochemical device is reduced, and the corrosion resistance of the electrochemical device can be improved. The provision of the insulating member corresponding to the first coating region in the electrochemical device may also be omitted, and the distance between the electrode assembly and the case may be shortened, thereby reducing the volume of the electrochemical device, reducing the loss of energy density in the electrochemical device, and improving the energy density of the electrochemical device.
In some embodiments of the present application, in the first direction, the width of the edge region of the third side is a width of the negative electrode tab beyond the positive electrode tab on the third side of the electrode assembly; the width of the edge region of the fourth side is the width of the negative electrode tab exceeding the positive electrode tab on the fourth side of the electrode assembly in the first direction; the width of the edge region of the bottom surface in the second direction is a width of the negative electrode tab beyond the positive electrode tab on the bottom surface of the electrode assembly. By limiting the width of the edge region, the electrochemical device can improve the corrosion resistance while maintaining the energy density.
In some embodiments of the present application, the bottom surface, the first side, the second side, the third side, and the fourth side of the electrode assembly each meet the case adjacent thereto. Therefore, the volume of the electrochemical device is reduced, the energy density is improved, the insulating part is saved, and the production cost of the electrochemical device is also reduced.
In some embodiments of the present application, the high potential anode active material includes at least one of titanium lithium oxide, titanium niobium oxide, lithium vanadium oxide, lithium copper oxide, lithium germanium oxide, or a modified material thereof.
In some embodiments of the present application, the high potential negative active material comprises at least one of lithium titanate, titanium niobate, titanium-coated titanium niobate, carbon-coated titanium niobate, or nitrogen-doped titanium niobate. The use of the first negative electrode active material described above can effectively increase the upper and lower potential ranges of the first negative electrode active material for charge and discharge in an electrochemical device.
In some embodiments of the present application, the housing is an aluminum plastic film or a metal shell, and the mass percentage of aluminum in the metal shell is WA＞10wt％。
Embodiments of the present application also provide an electronic device comprising the electrochemical device provided herein. The electronic device also has good energy density and safety performance.
Drawings
In order to more clearly illustrate the embodiments of the present application and the technical solutions of the prior art, the following briefly introduces the drawings required for the embodiments of the present application and the prior art, and obviously, the drawings in the following description are only some embodiments of the present application.
FIG. 1 is a schematic structural view of an electrochemical device according to some embodiments of the present application;
fig. 2 is a left side view of the electrochemical device of fig. 1;
FIG. 3 is a schematic diagram of a negative electrode tab of the electrochemical device of FIG. 1;
FIG. 4 is a schematic view of another negative electrode tab structure of the electrochemical device shown in FIG. 1;
FIG. 5 is a schematic view of another negative electrode tab structure of the electrochemical device shown in FIG. 1;
FIG. 6 is a schematic view of another negative electrode tab structure of the electrochemical device shown in FIG. 1;
FIG. 7 is a schematic structural view of an electrochemical device according to some embodiments of the present application;
FIG. 8 is a top view of the electrochemical device of FIG. 7;
FIG. 9 is a schematic view of a negative electrode tab of the electrochemical device shown in FIG. 7;
FIG. 10 is a schematic view of another negative electrode tab configuration of the electrochemical device shown in FIG. 7;
fig. 11 is a left side view of the electrochemical device in fig. 7;
FIG. 12 is a schematic view of another negative electrode tab of the electrochemical device shown in FIG. 7;
FIG. 13 is a schematic view of another negative electrode tab of the electrochemical device shown in FIG. 7;
fig. 14 is a schematic structural view (front view) of an electrochemical device according to some embodiments of the present application;
fig. 15 is a schematic structural view (front view) of an electrochemical device according to some embodiments of the present application;
fig. 16 is a schematic structural view of an electrochemical device according to some embodiments of the present application;
FIG. 17 is a top view of the electrochemical device of FIG. 16;
fig. 18 is a left side view of the electrochemical device of fig. 16;
FIG. 19 is a schematic view of a negative electrode tab of the electrochemical device shown in FIG. 16;
fig. 20 is a schematic view of another negative electrode tab structure of the electrochemical device shown in fig. 16.
Reference numerals: 001. an electrochemical device; 002. a positive terminal; 003. a negative terminal; 004. an insulating spacer; 005. a welding part; 10. an electrode assembly; 11. a positive electrode plate; 12. a spacer; 13. a negative pole piece; 131. a negative current collector; 100. an end face of the electrode assembly; 101. an electrode assembly first end face; 102. an electrode assembly second end face; 103. a top surface of the electrode assembly; 104. a bottom surface of the electrode assembly; 105. a first side of the electrode assembly; 106. a second side of the electrode assembly; 107. a third side of the electrode assembly; 108. a fourth side of the electrode assembly; 20. a housing; 200. an end face of the housing; 201. a housing first end face; 202. a second end surface of the housing; 30. a first coated region; 31. an edge region; 32. a finalization area; 33. a negative electrode coating region; 40. a second coated region; 50. an anode uncoated region; 60. a positive electrode uncoated region; 71. a positive electrode tab; 72. and a negative pole tab.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It is to be understood that the embodiments described are only a few embodiments of the present application and not all embodiments. All other technical solutions obtained by a person of ordinary skill in the art based on the embodiments in the present application belong to the scope of protection of the present application.
In the embodiments of the present application, the present application is explained by taking a lithium ion battery as an example of an electrochemical device, but the electrochemical device of the present application is not limited to a lithium ion battery. The specific technical scheme is as follows:
embodiments of the present application provide an electrochemical device including an electrode assembly and a case accommodating the electrode assembly. The electrode assembly comprises a pole piece and a separator, wherein the pole piece comprises a positive pole piece and a negative pole piece, the separator is arranged between the positive pole piece and the negative pole piece, the electrode assembly is formed by stacking the positive pole piece, the separator and the negative pole piece, and the outermost pole piece of the electrode assembly is the negative pole piece. The negative pole piece comprises a negative pole current collector and a negative pole coating area, the negative pole coating area is arranged on the surface of the negative pole current collector and comprises a first coating area, a first negative pole active material is arranged in the first coating area, and the first negative pole active material is Li/Li+Is 1V to 3V.
In this application, negative pole piece includes that negative pole mass flow body and negative pole coat the region, and the negative pole coats the regional surface that sets up in the negative pole mass flow body, and the negative pole coats the region including first coating region, and the regional coating of first coating has first negative active material, and first negative active material is to Li/Li+Is 1V to 3V. The negative pole piece is applied to electrochemistryIn the device, during the charge and discharge process of the electrochemical device, the lithium intercalation potential of the first coating region is higher than the lithium precipitation potential, so that the risk of lithium precipitation can be reduced; the lithium ion diffusion coefficient is large, and the lithium ion can be charged and discharged at a high rate in a low-temperature environment; for Li/Li due to upper and lower limits of charge and discharge potential of the first anode active material in an electrochemical device+Is 1V to 3V, thus for Li/Li+The first negative electrode active material has high potential performance, can generate charge-discharge reaction with the positive electrode, does not exert capacity like an insulating piece, and therefore can reduce the energy density loss of the electrochemical device caused by the use of the insulating piece.
Based on this, the first coating region containing the first negative electrode active material is arranged, so that the risk of lithium intercalation corrosion reaction caused by contact between the shell and the negative electrode pole piece in an electrolyte environment can be reduced, the corrosion resistance of the electrochemical device can be improved, and the safety performance of the electrochemical device can be improved. The first coating region of the present application may be disposed on at least one surface of the negative electrode current collector, for example, on a surface of the negative electrode current collector that is outermost in the electrode assembly and is close to the case, or on both surfaces of the negative electrode current collector. In the prior art, in order to avoid contact between the casing and the negative electrode plate in an electrolyte environment, an insulating member is often arranged between the casing and the negative electrode plate. This application has saved the insulating part through setting up first coating region, and then has also saved the inside space of the shared electrochemical device of insulating part, makes electrochemical device's volume reduce, has improved the problem because of the insulating part occupies the loss of energy density that electrochemical device volume caused, can improve electrochemical device's energy density, can also reduce electrochemical device's manufacturing cost.
In some embodiments of the present application, the outermost layer of the electrode assembly is a negative electrode tab. Thus, it is possible to avoid the provision of a separator at the outermost layer of the electrode assembly, whereby the volume occupied by the electrode assembly can be reduced, and the energy density of the electrochemical device can be improved.
In some embodiments of the present application, fig. 1 is a schematic structural view of an electrochemical device, and fig. 2 is a left side view of the electrochemical device. In the present application, the length direction of the electrochemical device is defined as a first direction, i.e., y direction; the thickness direction is a second direction, namely a z direction; the width direction is the third direction, i.e., the x direction. The first plane is a plane perpendicular to the second direction, namely an xoy plane; the second plane is a plane perpendicular to the third direction, namely a yoz plane; the third plane is a plane perpendicular to the first direction, i.e., an xoz plane. It should be understood that the above definitions of the directions are for the purpose of convenience in describing the present invention, and the directions defined in the present application may be understood according to the relative positions of the elements of the drawings and the actual apparatuses.
Referring to fig. 1 and 2, an electrode assembly 10 is stacked and wound by a positive electrode tab 11, a separator 12 and a negative electrode tab 13 to be disposed in a wound structure, an end face 100 of the electrode assembly is parallel to an end face 200 of a case in a first direction, the end face 100 of the electrode assembly includes an electrode assembly first end face 101 and an electrode assembly second end face 102, the end face 200 of the case includes a case first end face 201 and a case second end face 202, and specifically, the electrode assembly first end face 101, the electrode assembly second end face 102, the case first end face 201 and the case second end face 202 are parallel to each other in the first direction, wherein the electrode assembly first end face 101 is close to the case first end face 201, and the electrode assembly second end face 102 is close to the case second end face 202.
The inventors have found that locations in the housing 20 where corrosion risk may occur include: a case second end 202 adjacent to an edge region of the electrode assembly second end 102, and a side surface of the case 20 adjacent to an outermost layer of the electrode assembly 10, the side surface of the case 20 including regions other than the case first end 201 and the case second end 202. This is due to: the second end face 202 of the casing and the side face of the casing 20 may contact with the negative electrode sheet 13 only provided with the second negative active material, and the casing 20 is in an electrolyte environment, so that a corrosion risk is likely to occur; when the case 20 contains Al, the Al enters the inside of the electrode assembly 10, and is deposited between the positive electrode tab 11, the negative electrode tab 13, and the separator 12, further causing a safety risk to the electrochemical device.
Fig. 3 to 6 are schematic diagrams of four different structures of the negative electrode tab in the electrochemical device shown in fig. 1, and as shown in fig. 3 to 6, the negative electrode tab 13 includes a negative electrode collector 131 and a negative electrode coating area 33. An anode tab 72 is provided on the anode current collector 131 not provided with the anode coating region 33. The negative electrode coating region 33 includes a first coating region 30 and a second coating region 40. Specifically, as shown in fig. 3, the first coated region 30 includes an edge region 31, and the edge region 31 is located on the second end face 102 of the electrode assembly. Referring to fig. 3, the edge region 31 may refer to an edge of a side opposite to a direction in which the negative electrode tab 72 protrudes in the second direction; as shown in fig. 4, the first coated region 30 includes a finishing region 32; as shown in fig. 5, the first coating region 30 includes an edge region 31 and a finishing region 32; as shown in fig. 6, the first coating region 30 may be a negative electrode coating region 33 on the negative electrode collector 131, i.e., the first coating region 30 is the negative electrode coating region 33.
By arranging the first coating region 30, the embodiment of the application can reduce the risk of corrosion reaction in the region of the casing 20 corresponding to the first coating region 30 in the electrochemical device, and effectively improve the corrosion resistance of the electrochemical device. Due to the presence of the first coating region 30, the provision of an insulating member is omitted, the distance between the electrode assembly 10 and the case 20 is shortened, and the energy density loss of the electrochemical device is reduced.
In some embodiments of the present application, referring to fig. 2 and 3, the width of the negative electrode tab 13 beyond the positive electrode tab 11 on the second electrode assembly end surface 102 is a pitch width W in the second direction, the width W1 of the edge region 31 is greater than or equal to the pitch width W and less than the width W2 of the negative electrode tab 13, the edge of the separator 12 is between the negative electrode tab 13 and the positive electrode tab 11, and the edge of the negative electrode tab 13 is located on the second electrode assembly end surface 102.
In other embodiments of the present application, the width of the negative electrode tab 13 may be equal to the width of the positive electrode tab 11, the pitch width W is 0, the width W1 of the edge region 31 is greater than 0 and less than the width W2 of the negative electrode tab 13, and the width of the separator 12 is greater than the width of the negative electrode tab 13.
According to the embodiment of the application, the width of the edge region 31 is controlled, so that the energy density reduction of the electrochemical device can be reduced, and the corrosion resistance of the electrochemical device can be improved.
In the present application, the aforementioned "parallel" should be understood as approximately parallel, and those skilled in the art should understand that the end face 100 of the electrode assembly and the end face 200 of the case are ideally parallel, but in actual production application, due to different factors such as the material of the case 20, the machining process of the electrochemical device 001, and the like, the end face 100 of the electrode assembly and the end face 200 of the case are inclined, convex, or concave to different degrees, and thus are not strictly parallel but approximately parallel in some cases.
In the present application, the "run-out region" may refer to a region located at the winding end in the winding direction when the electrode assembly is in a wound structure. In some embodiments, the ending region may be the outermost turn of the winding structure. The "negative electrode coating region 33" refers to the entire region of the negative electrode tab where the negative electrode active material needs to be coated on the negative electrode current collector in the actual production process. The negative electrode active material includes a first negative electrode active material and a second negative electrode active material. The second coated region is provided with a second anode active material.
In some embodiments of the present application, as shown in fig. 3, the negative electrode tab 13 includes the second coating region 40 and the first coating region 30, and the first coating region 30 includes the edge region 31 located at the second end surface 102 of the electrode assembly, so that the risk of corrosion occurring between the second end surface 102 of the electrode assembly and the second end surface 202 of the case can be reduced, and the corrosion protection performance of the electrochemical device 001 can be improved. No insulating member may be disposed between the second electrode assembly end 102 and the second case end 202, and the distance between the second electrode assembly end 102 and the second case end 202 is shortened. Preferably, in some embodiments of the present application, the electrode assembly second end surface 102 meets the case second end surface 202, whereby the volume of the electrochemical device is reduced and accordingly, the volumetric energy density of the electrochemical device is increased while the rated capacity of the electrochemical device is maintained. The saving of the insulating member also reduces the production cost of the electrochemical device.
In some embodiments of the present application, as shown in fig. 4, the negative electrode tab 13 includes the second coating region 40 and the first coating region 30, and the first coating region 30 includes the ending region 32, so that the risk of corrosion occurring between the portion of the outermost electrode tab of the electrode assembly 10 closest to the case 20 and the side of the case 20 can be reduced, and the corrosion resistance of the electrochemical device 001 can be improved. At this time, an insulating member is not required to be disposed between the portion of the outermost pole piece of the electrode assembly 10 closest to the case 20 and the side surface of the case 20, so that the distance between the outermost pole piece of the electrode assembly 10 and the side surface of the case 20 is shortened. Preferably, in some embodiments of the present application, the outermost pole piece of the electrode assembly 10 is connected to the case 20 at a position closest to the case 20, whereby the volume of the electrochemical device is reduced, the energy density is increased, the insulation is saved, and the production cost of the electrochemical device is also reduced.
In some embodiments of the present application, as shown in fig. 5, the negative electrode tab 13 includes a second coated region 40 and a first coated region 30, the first coated region 30 including an edge region 31 and a run-out region 32 at the second end 102 of the electrode assembly.
In other embodiments of the present application, as shown in fig. 6, the first coated region 30 is a negative coated region 33, i.e., the first coated region 30 includes the entire negative coated region 33.
Thus, the risk of occurrence of corrosion reaction between the electrode assembly 10 and the case 20 can be reduced, and the corrosion resistance of the electrochemical device 001 can be improved. No insulating member is required to be arranged between the second electrode assembly end surface 102 and the second case end surface 202, and between the part of the outermost pole piece of the electrode assembly 10 closest to the case 20 and the side surface of the case 20, so that the production cost of the electrochemical device 001 is effectively reduced. Also, since the first negative active material can be charged and discharged at a high rate in an extremely low temperature environment, the increase of the first coating region 30 can effectively improve the charge and discharge performance of the electrochemical device at an extremely low temperature. "contiguous" in the present application may mean that the distance between the electrode assembly 10 and the case 20 is in the range of 0mm to 1mm, preferably 0 mm. Illustratively, referring to fig. 2, the distance P1 between the electrode assembly second end face 102 and the case second end face 202 is ≦ 1mm, preferably P1 ≦ 0 mm; the distance P2 between the outermost pole piece of the electrode assembly 10 and the case is not more than 1mm, P3 is not more than 1mm, and preferably P2 is 0mm and P3 is 0 mm.
In some embodiments of the present application, as shown in fig. 7 and 8, the electrode assembly 10 is disposed in a wound structure by winding the positive electrode tab 11, the separator 12, and the negative electrode tab 13 in a stacked manner, and the end face 100 of the electrode assembly is perpendicular to the end face 200 of the case, specifically, the end face 100 of the electrode assembly includes an electrode assembly first end face 101 and an electrode assembly second end face 102, and the electrode assembly first end face 101 and the electrode assembly second end face 102 are parallel to each other in the second direction and are respectively located at both ends of the electrode assembly 10 in the first direction. The end surface 200 of the housing includes a first end surface 201 and a second end surface 202, and the first end surface 201 and the second end surface 202 are parallel to each other along the first direction and are respectively located at two ends of the housing 20 along the second direction. The first end face 201 of the housing is provided with a positive electrode terminal 002 and a negative electrode terminal 003, the positive electrode terminal 002 is connected to one side of the first end face 101 of the electrode assembly by a welding member 005, and the negative electrode terminal 003 is connected to one side of the second end face 102 of the electrode assembly by a welding member 005, wherein the areas where the welding member 005 is connected to the electrode assembly 10 are the negative uncoated area 50 of the negative electrode plate 13 and the positive uncoated area 60 of the positive electrode plate 11, respectively. The first coating region 30 includes at least one of an edge region 31 or a finishing region 32 provided near the negative electrode terminal 003 side; or the first coated region 30 is a negative coated region 33. Referring to fig. 8 and 9, the edge region 31 in the embodiment of the present application is located at the edge of the negative electrode coating region 33, and thus may also be referred to as an edge region.
In the present application, the "perpendicular" is understood to be approximately perpendicular, and it will be understood by those skilled in the art that the end surface 100 of the electrode assembly and the end surface 200 of the case are ideally perpendicular, but in actual production applications, the end surface 100 of the electrode assembly and the end surface 200 of the case are inclined, protruded or recessed to different degrees due to different factors such as the material of the case 20, the machining process of the electrochemical device 001, and the like, and thus are not strictly perpendicular but approximately perpendicular in some cases.
In some embodiments of the present application, as shown in fig. 8, in the first direction, along the direction in which the second end face 102 of the electrode assembly approaches the case 20, the width W of the edge region 31 is equal to the difference between the width of the negative coating region of the negative electrode tab 13 and the width of the positive coating region of the positive electrode tab 11, the edge of the separator 12 is interposed between the negative electrode tab 13 and the positive electrode tab 11, and the edge of the negative electrode tab 13 is located on the second end face 102 of the electrode assembly. In some embodiments of the present application, the positive electrode coating region may be a positive electrode active material coating region.
In other embodiments of the present application, the negative coating area width of the negative electrode tab 13 is equal to the positive coating area coating width of the positive electrode tab 11, and the edge of the separator 12 exceeds the side of the edge area 31 adjacent to the second end surface 102 of the electrode assembly in the first direction.
According to the embodiment of the application, the width of the edge area 31 is controlled, so that the energy density of the electrochemical device can be prevented from being reduced, and the corrosion resistance of the electrochemical device can be improved.
In some embodiments of the present application, as shown in fig. 9, the negative electrode tab 13 includes a negative uncoated region 50, a second coated region 40, and an edge region 31 along the first direction, and the edge region 31 is located near the negative terminal 003 side and between the negative uncoated region 50 and the second coated region 40, so that the risk of corrosion between the electrode assembly second end surface 102 and the case 20 can be reduced, and the corrosion resistance of the electrochemical device 001 can be improved. No insulating member may be disposed between the second electrode assembly end surface 102 and the case 20, and the distance between the second electrode assembly end surface 102 and the case 20 is shortened. Preferably, the electrode assembly first end surface 101 and the electrode assembly second end surface 102 are both contiguous to the case 20, and referring to fig. 7, the distance P1 between the electrode assembly second end surface 102 and the closest and parallel side surface of the case 20 is not more than 1mm, and preferably, P1 is 0mm, whereby the volume of the electrochemical device is reduced, the energy density is improved, the insulators are saved, and the production cost of the electrochemical device is also reduced.
In some embodiments of the present application, as shown in fig. 10, the negative electrode tab 13 includes a negative uncoated region 50, a second coated region 40, and a final region 32 along the first direction, so that the risk of corrosion occurring between the part of the outermost electrode tab of the electrode assembly 10 closest to the case 20 and the case 20 can be reduced, and the corrosion resistance of the electrochemical device can be improved. At this time, an insulating member may not be disposed between the portion of the outermost pole piece of the electrode assembly 10 closest to the case 20 and the case 20, so that the distance between the outermost pole piece of the electrode assembly 10 and the case 20 is shortened. Preferably, in some embodiments of the present application, the portion of the outermost pole piece of the electrode assembly 10 closest to the case 20 is contiguous with the case 20, and as shown in fig. 11, the distance P2 ≦ 1mm, P3 ≦ 1mm, P4 ≦ 1mm, preferably P2 ≦ 0mm, P3 ≦ 0mm, and P4 ≦ 0mm from the case. Accordingly, the volume of the electrochemical device 001 is reduced, and accordingly, the volumetric energy density thereof is improved while the rated capacity of the electrochemical device remains unchanged, and the production cost of the electrochemical device is reduced by saving the insulating member.
In some embodiments of the present application, as shown in fig. 12, the negative electrode tab 13 includes a negative uncoated region 50, a second coated region 40, and a first coated region 30 along the first direction, and the first coated region 30 includes an edge region 31 and a finishing region 32 disposed near one side of the negative electrode terminal 003.
In other embodiments of the present application, as shown in fig. 13, the negative electrode tab 13 includes a negative uncoated region 50 and a negative coated region 33 on the negative electrode collector along the first direction, i.e., the first coated region 30 is the negative coated region 33.
Thus, the risk of occurrence of corrosion reaction between the electrode assembly 10 and the case 20 can be reduced, and the corrosion resistance of the electrochemical device 001 can be improved. No insulating member may be disposed between the second electrode assembly end 102 and the second case end 202, or between the outermost pole piece of the electrode assembly 10 closest to the case 20 and the other side surfaces of the case 20, so as to effectively reduce the production cost of the electrochemical device. Also, since the first negative active material can be charged and discharged at a high rate in an extremely low temperature environment, the increase of the first coating region 30 can effectively improve the charge and discharge performance of the electrochemical device at an extremely low temperature.
In some embodiments of the present application, as shown in fig. 14 and 15, the electrode assembly 10 is disposed in a wound structure by winding the positive electrode tab 11, the separator 12, and the negative electrode tab 13 in layers, with the end face 100 of the electrode assembly parallel to the end face 200 of the case. Specifically, the end face 100 of the electrode assembly includes an electrode assembly first end face 101 and an electrode assembly second end face 102, and the electrode assembly first end face 101 and the electrode assembly second end face 102 are parallel to each other in the third direction and are respectively located at both ends of the electrode assembly 10 in the second direction. The end surface 200 of the housing includes a first end surface 201 and a second end surface 202, and the first end surface 201 and the second end surface 202 are parallel to each other along the third direction and are respectively located at two ends of the housing 20 along the second direction. The first end surface 101 of the electrode assembly is connected with a positive electrode tab 71, and the second end surface 102 of the electrode assembly is connected with a negative electrode tab 003; the first coated region 30 includes a finishing region 32; or the first coating region 30 is the negative coating region 33, and the specific positions of the ending region 32 and the negative coating region 33 can be respectively referred to fig. 4 and 6, which are not described in detail herein. In this way, the risk of corrosion occurring between the portion of the outermost pole piece of the electrode assembly 10 closest to the case 20 and the case 20 can be reduced, and the corrosion resistance of the electrochemical device 001 can be improved. At this time, an insulating member is not required to be provided between the portion of the outermost pole piece of the electrode assembly 10 closest to the case 20 and the case 20, and the distance between the outermost pole piece of the electrode assembly 10 and the case 20 is shortened.
In some embodiments of the present application, the outermost pole piece of the electrode assembly 10 is connected to the case 20 at a position closest to the case 20, and as shown in fig. 14 and 15, the outermost pole piece of the electrode assembly 10 is located at a distance P2 ≦ 1mm, P3 ≦ 1mm, and preferably, P2 ≦ 0mm, and P3 ≦ 0mm from the case. Thus, the volume of the electrochemical device 001 is reduced, the energy density is improved, the insulating member is saved, and the production cost of the electrochemical device 001 is also reduced.
In some embodiments of the present application, as shown in fig. 16 to 18, the electrode assembly 10 is stacked by the positive electrode tab 11, the separator 12 and the negative electrode tab 13 to form a stacked structure, the top surface 103 of the electrode assembly is parallel to the end surface 200 of the case on the first plane, specifically, the top surface 103 of the electrode assembly, the first end surface 201 of the case and the second end surface 202 of the case are parallel to each other, the first end surface 201 of the case is provided with the positive electrode terminal 002 and the negative electrode terminal 003, the top surface 103 of the electrode assembly is connected with the positive electrode terminal 002 and the negative electrode terminal 003, and the positive electrode terminal 001 and the negative electrode terminal 003 are respectively provided with the insulating spacer 004.
As shown in fig. 18 and 19, the first side 105 and the second side 106 of the electrode assembly 10 on the second plane are the negative electrode tab 13, respectively. Accordingly, locations in the electrode assembly 10 where corrosion risk may occur include areas where the first side 105, the second side 106, the third side 107, the fourth side 108, and the bottom surface 104 correspond to the case 20.
Thus, the first coating region 30 includes at least one of the outer surface of the negative electrode tab 13 located at the first and second sides 105 and 106 of the electrode assembly, the edge region 31 located at the third side 107 of the electrode assembly 10 on the third plane, the edge region 31 located at the fourth side 108 of the electrode assembly on the third plane, or the edge region 31 located at the bottom surface 104 of the electrode assembly 10 on the first plane. The arrangement of the first coating region 30 can reduce the risk of occurrence of corrosion reaction at the corresponding region of the electrochemical device, improve the corrosion resistance of the electrochemical device, omit the arrangement of an insulating member corresponding to the first coating region 30 in the electrochemical device, shorten the distance between the electrode assembly 10 and the case 20, and further reduce the volume of the electrochemical device, and accordingly, the volumetric energy density of the electrochemical device can be improved while the rated capacity of the electrochemical device remains unchanged.
In some embodiments of the present application, as shown in fig. 16 and 17, in the first direction, the width W3 of the edge region 31 of the third side 107 is the width of the negative electrode tab 13 beyond the positive electrode tab 11 on the third side 107 of the electrode assembly 10; the width W4 of the edge region 31 of the fourth side 108 in the first direction is the width of the negative electrode tab 13 beyond the positive electrode tab 11 on the fourth side 108 of the electrode assembly 10; in the second direction, the width W1 of the edge region 31 of the bottom face 104 is the width of the negative electrode tab 13 beyond the positive electrode tab 11 on the bottom face 104 of the electrode assembly 10. By defining the width of the edge region 31, the electrochemical device can improve its corrosion resistance while maintaining energy density.
In some embodiments of the present application, as shown in fig. 19, the first coating region 30 includes the outer surface of the negative electrode tab 13 at the first and second sides 105 and 106 of the electrode assembly, so that the risk of corrosion occurring between the first and second sides 105 and 106 of the electrode assembly 10 and the case 20 can be reduced and the corrosion protection performance of the electrochemical device 001 can be improved. No insulating member is required to be disposed between the first side 105 and the second side 106, so that the distance between the first side 105 and the second side 106 and the housing 20 is shortened. In some embodiments, the first side 105 and the second side 106 of the electrode assembly 10 are respectively connected to the adjacent cases 10, as shown in fig. 20, the distance P5 between the first side 105 and the case 20 is not more than 1mm, preferably, P5 is 0mm, and the distance P4 between the second side 106 and the case 20 is not more than 1mm, preferably, P4 is 0 mm. Therefore, the volume of the electrochemical device is reduced, the energy density of the electrochemical device is improved, the insulating part is saved, and the production cost of the electrochemical device is reduced.
In some embodiments of the present application, the first coating region 30 includes an edge region 31 located at the third side 107 of the electrode assembly 10 on the third plane or an edge region 31 located at the fourth side 108 of the electrode assembly on the third plane or an edge region 31 located at the bottom side 104 of the electrode assembly 10 on the first plane.
In other embodiments, the first coating region 30 includes two of an edge region 31 located at the third side 107 of the electrode assembly 10 on the third plane, an edge region 31 located at the fourth side 108 of the electrode assembly on the third plane, or an edge region 31 located at the bottom side 104 of the electrode assembly 10 on the first plane.
In still other embodiments of the present application, as shown in fig. 20, the first coating region 30 includes an edge region 31 located at the third side 107 of the electrode assembly 10 on the third plane, an edge region 31 located at the fourth side 108 of the electrode assembly on the third plane, and an edge region 31 located at the bottom surface 104 of the electrode assembly 10 on the first plane. The side of the electrode assembly where the first coating region is disposed can effectively prevent corrosion of the case 20 without providing an insulating member, and the distance between the outermost side of the electrode assembly 10 and the case 20 is shortened. In some embodiments, the bottom surface 104, the third side surface 107, and the fourth side surface 108 of the electrode assembly 10 are each contiguous with its adjacent case 10, and referring to fig. 19 and 20, the distance P1 of the bottom surface 104 from the case 20 is no greater than 1mm, preferably P1 is 0mm, the distance P2 of the third side surface 107 from the case 20 is no greater than 1mm, preferably P2 is 0mm, and the distance P3 of the fourth side surface 108 from the case 20 is no greater than 1mm, preferably P3 is 0 mm.
In some embodiments of the present application, the first anode active material includes at least one of lithium titanium oxide, niobium titanium oxide, vanadium lithium oxide, copper lithium oxide, germanium lithium oxide, or a modified material thereof. The method of modification is not particularly limited as long as the object of the present application can be achieved. For example, methods for modifying the above materials include coating, doping, nanocrystallization, or other surface modification. Illustratively, in some embodiments of the present application, the first negative active material comprises at least one of lithium titanate, titanium niobate, titanium-coated titanium niobate, carbon-coated titanium niobate, or nitrogen-doped titanium niobate. The use of the first negative electrode active material described above can effectively raise the upper limit potential and the lower limit potential of the first negative electrode active material for charge and discharge in an electrochemical device.
The second anode active material is not particularly limited in kind in the present application as long as the object of the present application can be achieved. For example, the second negative active material may include natural graphite, artificial graphite, mesophase micro carbon spheres (MCMB), hard carbon, soft carbon, silicon-carbon composite, SiOx(0<x<2) Li-Sn alloy, Li-Sn-O alloy, Sn, SnO2Lithium titanate Li of spinel structure4Ti5O12At least one of Li-Al alloy and metallic lithium.
In some embodiments of the present application, the housing is an aluminum plastic film or a metal shell, the aluminum plastic film comprises a nylon layer, an aluminum foil layer and a polypropylene layer, and the mass percentage of aluminum in the metal shell is WAMore than 10 wt%. The metal shell within the above-mentioned mass percentage content range can have a light weight and high safety.
In the present application, the thickness of the case is not particularly limited as long as the object of the present application can be achieved. For example, the thickness of the shell may be 50 μm to 500 μm, preferably 50 μm to 300 μm, more preferably 50 μm to 200 μm. The case within the above thickness range may effectively protect the internal structure of the electrochemical device.
The type of the insulating member is not particularly limited, and those skilled in the art can select the insulating member according to actual conditions as long as the purpose of the present application can be achieved. For example, the insulating member includes a gummed paper, a separator, a spacer, or the like.
The present application does not particularly limit the material of the tab as long as the object of the present application can be achieved. For example, the positive electrode tab material includes at least one of aluminum (Al) or an aluminum alloy, and the negative electrode tab material includes at least one of nickel (Ni), copper (Cu), or copper-plated nickel (Ni — Cu).
The present application does not particularly limit the connection manner of the tabs as long as the object of the present application can be achieved. For example, at least one of laser welding, ultrasonic welding, resistance welding, conductive adhesive bonding, or the like. The direction that this application is drawn forth different utmost point ear does not have special restriction, as long as can realize the purpose of this application. For example, the direction of the tab lead-out can be the same direction or different directions.
In the present application, there is no particular limitation on the structure of the electrode assembly as long as the object of the present application can be achieved. For example, the structure of the electrode assembly may include at least one of a winding structure or a lamination structure.
In the present application, the separator is used to separate the positive electrode sheet and the negative electrode sheet to prevent internal short circuits of the electrochemical device, which allows electrolyte ions to freely pass through, completing the function of the electrochemical charge and discharge process. The present application does not specifically limit the kind of the separator as long as the object of the present application can be achieved. For example, the separator includes a separator or a solid electrolyte, or the like. The number of the separator, the positive electrode sheet, and the negative electrode sheet in the electrochemical device is not particularly limited as long as the object of the present invention can be achieved.
The electrochemical device of the present application may further include other devices in which electrochemical reactions occur, such as a lithium metal secondary battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery, etc.
The present application does not particularly limit the fabrication process of the electrochemical device as long as the object of the present application can be achieved. For example, the electrochemical device may be prepared by the following process: overlapping the positive pole piece and the negative pole piece through a separator, winding or folding the positive pole piece and the negative pole piece according to needs, putting the positive pole piece and the negative pole piece into a shell, injecting electrolyte into the shell, and sealing the shell; or, overlapping the negative pole piece and the positive pole piece through a separator to form a lamination, fixing four corners of the whole lamination structure by using an adhesive tape, placing the lamination structure into an aluminum shell, injecting electrolyte into the shell, and sealing the shell to obtain the electrochemical device. In addition, an overcurrent prevention element, a guide plate, or the like may be placed in the case as necessary to prevent a pressure rise and overcharge/discharge inside the electrochemical device.
A second aspect of the present application provides an electronic device comprising the electrochemical device provided in the first aspect of the present application. The electronic device has good corrosion resistance.
The electronic device of the present application is not particularly limited, and may include, but is not limited to: notebook computers, pen-input computers, mobile computers, electronic book players, cellular phones, portable facsimile machines, portable copiers, portable printers, headphones, video recorders, liquid crystal televisions, portable cleaners, portable CD players, mini-discs, transceivers, electronic notebooks, calculators, memory cards, portable recorders, radios, backup power supplies, motors, automobiles, motorcycles, mopeds, bicycles, lighting fixtures, toys, game machines, clocks, electric tools, flashlights, cameras, large household batteries, lithium ion capacitors, and the like.
Examples
Hereinafter, embodiments of the present application will be described in more detail with reference to examples and comparative examples. Various tests and evaluations were carried out according to the following methods. Unless otherwise specified, "part" and "%" are based on mass.
The test method and the test equipment are as follows:
testing the capacity of the lithium ion battery:
the lithium ion battery is kept stand for 30 minutes in an environment with the temperature of 25 +/-3 ℃, the voltage is charged to 4.4V by the constant current of 0.5C, then the charging is stopped until the current reaches 0.05C, and the lithium ion battery to be tested is placed for 30 minutes. And then discharging the lithium ion battery to 3.0V by 0.2C current, and placing the lithium ion battery to be tested for 30 minutes. And finally, taking and placing the electric capacity as the battery capacity of the lithium ion battery.
Slight drop test and duration test of high temperature and high humidity:
(1) pretreatment before testing:
standing the lithium ion battery for 5min at 25 ℃, discharging at a rate of 0.2C until the state of charge (SOC) is 0%, standing the battery for 5min, then charging at a rate of 0.5C at a constant current until the SOC is 50%, charging at a constant voltage until the SOC is 0.05C, and standing for 5 min;
(2) checking the appearance of the battery, taking a picture, and testing the voltage;
(3) putting the battery into a clamp, and setting the falling height to be 10 cm;
(4) slightly dropping each surface of the battery for 100 times, sequentially slightly dropping each surface for 500 times, wherein each surface is a cycle, and 3 cycles are tested;
(5) taking the slightly-dropped battery to perform a high-temperature high-humidity test, namely standing the battery for 14 days in an environment with the temperature of (60 +/-3) DEG C and the relative humidity of 90%;
(6) the stored Open Circuit Voltage (OCV) and internal resistance (IMP) of the battery were recorded, and the appearance of the battery was checked and photographed.
Criteria for judging low corrosion risk are: after the high-temperature and high-humidity test is finished, the shell is free of damage and leakage, and the OCV is reduced by less than 0.2V.
Example 1
< preparation of negative electrode sheet >
Mixing the first negative active material, conductive carbon black (Super P) and Styrene Butadiene Rubber (SBR) according to a weight ratio of 96:1.5:2.5, adding deionized water serving as a solvent, blending to obtain first slurry with a solid content of 70%, and uniformly stirring. And mixing the second negative electrode active material, the Super P and the SBR according to a weight ratio of 96:1.5:2.5, adding deionized water as a solvent, blending into a second slurry with a solid content of 70%, and uniformly stirring. And uniformly coating the first slurry on a first coating area of a negative current collector copper foil with the thickness of 8 mu m, uniformly coating the second slurry on a second coating area, and drying at 110 ℃ to obtain the negative pole piece with the coating thickness of 130 mu m and single-side coated with the negative active material. And after the steps are completed, finishing the single-side coating of the negative pole piece. And then, repeating the steps on the other surface of the negative pole piece to obtain the negative pole piece with the negative active material coated on the two surfaces. After coating, the negative pole piece is cut into the specification of 76mm × 851mm for standby.
< preparation of Positive electrode sheet >
The positive electrode active material lithium cobaltate (LiCoO)2) Mixing conductive carbon black (Super P) and polyvinylidene fluoride (PVDF) according to the weight ratio of 97.5:1.0:1.5, adding N-methylpyrrolidone (NMP) as a solvent, preparing into slurry with the solid content of 75%, and uniformly stirring. And uniformly coating the slurry on one surface of an aluminum foil of the positive current collector with the thickness of 10 mu m, and drying at 90 ℃ to obtain a positive pole piece with the coating thickness of 110 mu m. And finishing the single-side coating of the positive pole piece after the steps are finished. And then, repeating the steps on the other surface of the positive pole piece to obtain the positive pole piece with the positive active material coated on the two surfaces. After coating, cutting the positive pole piece into a size of 74mm × 867mm for standby.
< preparation of electrolyte solution >
In a dry argon atmosphere, organic solvents of Ethylene Carbonate (EC), Ethyl Methyl Carbonate (EMC) and diethyl carbonate (DEC) were first mixed in a mass ratio of EC: EMC: DEC: 30:50:20, and then lithium salt lithium hexafluorophosphate (LiPF) was added to the organic solvent6) Dissolving and mixing uniformly to obtain the electrolyte with the concentration of lithium salt of 1.15 mol/L.
< preparation of separator >
A polypropylene (PP) film (available from Celgard) having a thickness of 14 μm was used.
< preparation of lithium ion Battery >
And (3) stacking the prepared positive pole piece, diaphragm and negative pole piece in sequence to enable the diaphragm to be positioned between the positive pole piece and the negative pole piece to play a role in isolation, and winding or folding to obtain the electrode assembly. And (3) placing the electrode assembly into an aluminum-plastic film shell, dehydrating at 80 ℃, injecting the prepared electrolyte, and performing vacuum packaging, standing, formation, shaping and other processes to obtain the lithium ion battery.
Example 16
< preparation of negative electrode sheet >
The same procedure as in example 1 was repeated except that the negative electrode sheet was cut to a size of 41mm × 61 mm.
< preparation of Positive electrode sheet >
The same procedure as in example 1 was repeated, except that the positive electrode sheet was cut into a size of 38 mm. times.58 mm.
< preparation of electrolyte > and < preparation of separator > were the same as in example 1.
< preparation of lithium ion Battery >
And (3) overlapping the prepared positive pole piece, the diaphragm and the prepared negative pole piece to form a lamination, enabling the diaphragm to be positioned between the positive pole piece and the negative pole piece to play a role in isolation, and fixing four corners of the whole lamination structure by using adhesive tapes to obtain the electrode assembly. And (3) placing the electrode assembly into an aluminum-plastic film shell, dehydrating at 80 ℃, injecting the prepared electrolyte, and performing vacuum packaging, standing, formation, shaping and other processes to obtain the lithium ion battery.
Examples 2 to 15, comparative examples 1 to 4, the preparation steps of < preparation of negative electrode sheet >, < preparation of positive electrode sheet >, < preparation of electrolyte >, < preparation of separator > and < preparation of lithium ion battery > were the same as those of example 1; in example 17 and comparative example 5, the preparation steps of < preparation of negative electrode sheet >, < preparation of positive electrode sheet >, < preparation of electrolyte >, < preparation of separator > and < preparation of lithium ion battery > were the same as those in example 16; the variation of the relevant preparation parameters is shown in table 1 and the variation of the relevant effect parameters is shown in table 2:
Figure BDA0003242069050000171
Figure BDA0003242069050000181
Figure BDA0003242069050000191
Figure BDA0003242069050000201
as can be seen from examples 1 to 6 and comparative example 1, in the lithium ion battery with a winding structure shown in fig. 1, when different types of first coating regions are provided in the negative electrode tab, the corrosion risk of the electrochemical device is effectively reduced, the probability that the case leakage amount and the OCV decrease by a value of less than 0.2V are both significantly reduced, and the corrosion resistance of the electrochemical device is effectively improved. The provision of the insulator at the finishing region and/or the insulator between the electrode assembly and the case is also omitted, thereby reducing the production cost of the electrochemical device and the volume of the electrochemical device. As can be seen from example 1, example 4 to example 6, and comparative example 1, the arrangement of the first coating region also significantly improves the energy density of the electrochemical device.
As can be seen from examples 7 to 11 and comparative example 2, with respect to the lithium ion battery of the winding structure shown in fig. 7, when different kinds of first coating regions are provided in the negative electrode tab, the corrosion risk of the electrochemical device is effectively reduced, and thus the corrosion resistance of the electrochemical device is effectively improved. The provision of the insulator at the finishing region and/or the insulator between the electrode assembly and the case is also omitted, thereby reducing the production cost of the electrochemical device and the volume of the electrochemical device. As can be seen from example 7, example 10 and comparative example 2, the provision of the first coating region also significantly improves the energy density of the electrochemical device.
As can be seen from examples 12, 13, and 3, with respect to the lithium ion battery with a winding structure shown in fig. 14, when different kinds of first coating regions are provided in the negative electrode tab, the corrosion risk of the electrochemical device is effectively reduced, and thus the corrosion resistance of the electrochemical device is effectively improved. The provision of the insulator at the finishing region and/or the insulator between the electrode assembly and the case is also omitted, thereby reducing the production cost of the electrochemical device and the volume of the electrochemical device. As can be seen from example 12 and comparative example 3, the provision of the first coating region also significantly improves the energy density of the electrochemical device.
As can be seen from example 14, example 15, and comparative example 4, with respect to the lithium ion battery with a winding structure shown in fig. 15, when different kinds of first coating regions are provided in the negative electrode tab, the corrosion risk of the electrochemical device is effectively reduced, and thus the corrosion resistance of the electrochemical device is effectively improved. The arrangement of the insulating member in the ending region is also omitted, thereby reducing the production cost and the volume of the electrochemical device. As can be seen from example 14 and comparative example 4, the provision of the first coating region also significantly improves the energy density of the electrochemical device.
As can be seen from example 16, example 17, and comparative example 5, with respect to the lithium ion battery having a laminated structure shown in fig. 16, when different kinds of first coating regions are provided in the negative electrode tab, the corrosion risk of the electrochemical device is effectively reduced, and thus the corrosion resistance of the electrochemical device is effectively improved. The provision of an insulating member between the electrode assembly and the case is also omitted, thereby reducing the production cost and volume of the electrochemical device. As can be seen from example 16 and comparative example 5, the provision of the first coating region also significantly improves the energy density of the electrochemical device.
By combining the analysis, the lithium ion battery with the winding structure and the lamination structure can effectively improve the corrosion resistance of the electrochemical device and the safety performance of the electrochemical device by arranging the first coating area on the surface of the negative pole piece. Furthermore, the contact between the shell and the negative pole piece can reduce the risk of occurrence of corrosion reaction, on one hand, the use of an insulating part is omitted, on the other hand, the distance between the shell and the negative pole piece can be reduced, so that the volume of the electrochemical device is reduced, the energy density of the electrochemical device is improved, and the production cost of the electrochemical device is reduced.
It is noted that, herein, relational terms such as "first," "second," "third," "fourth," and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
In addition, in this document, the terms "width", "upper", "left", "top", "bottom", "side", "inner", "outer", "near", "center", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience in describing technical solutions and simplifying the description of the respective embodiments of the present application, and do not indicate or imply that a device or an element must have a specific orientation, be configured and operated in a specific orientation, and thus, cannot be construed as limiting the present application.
All the embodiments in the present specification are described in a related manner, and the same and similar parts among the embodiments may be referred to each other, and each embodiment focuses on the differences from the other embodiments.
The above description is only exemplary of the present application and should not be taken as limiting the present application, as any modification, equivalent replacement, or improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims (16)

1. An electrochemical device comprising an electrode assembly and a case accommodating the electrode assembly, the electrode assembly comprising a pole piece and a separator, the pole piece comprising a positive pole piece and a negative pole piece, the separator being disposed between the positive pole piece and the negative pole piece, the electrode assembly being stacked by the positive pole piece, the separator and the negative pole piece, the outermost pole piece of the electrode assembly being the negative pole piece;
the negative pole piece comprises a negative pole current collector and a negative pole coating area, wherein the negative pole coating area is arranged on the surface of the negative pole current collector, the negative pole coating area comprises a first coating area, the first coating area is provided with a first negative pole active material, and the first negative pole active material is Li/Li+Is 1V to 3V.
2. The electrochemical device according to claim 1, wherein the electrode assembly is arranged in a wound structure by the positive electrode tab, the separator, and the negative electrode tab being stacked and wound, an end face of the electrode assembly being parallel to an end face of the case, the end face of the electrode assembly including an electrode assembly first end face and an electrode assembly second end face, the electrode assembly first end face being parallel to the electrode assembly second end face, the electrode assembly first end face having a positive electrode terminal and a negative electrode terminal connected thereto;
the first coated region includes at least one of an edge region or a tail region, the edge region being located at the electrode assembly second end face; or
The first coated region is the negative coated region.
3. The electrochemical device of claim 2, wherein the width of the negative pole piece beyond the positive pole piece on the electrode assembly second end face is a pitch width, and the width of the edge region is greater than or equal to the pitch width and less than the width of the negative pole piece.
4. The electrochemical device according to claim 3, wherein the electrode assembly second end face meets the case second end face;
the outermost pole piece of the electrode assembly is connected with the shell at the position closest to the shell.
5. The electrochemical device according to claim 1, wherein the electrode assembly is stacked and wound by the positive electrode tab, the separator, and the negative electrode tab in a wound structure, an end face of the electrode assembly is perpendicular to an end face of the case, the end face of the electrode assembly includes an electrode assembly first end face and an electrode assembly second end face, the electrode assembly first end face is parallel to the electrode assembly second end face, the end face of the case includes a case first end face and a case second end face, and the case first end face is parallel to the case second end face;
the first end face of the shell is provided with a positive terminal and a negative terminal, the positive terminal is connected to one side of the first end face of the electrode assembly, and the negative terminal is connected to one side of the second end face of the electrode assembly;
the first coated region includes at least one of an edge region or a tail region disposed proximate to a side of the negative terminal; or
The first coated region is the negative coated region.
6. The electrochemical device of claim 5, wherein the width of the edge region is equal to a difference between a negative coated region width of the negative pole piece and a positive coated region width of the positive pole piece in the first direction.
7. The electrochemical device of claim 5, wherein the electrode assembly first end face and the electrode assembly second end face are each contiguous with the case;
the outermost pole piece of the electrode assembly is connected with the shell at the position closest to the shell.
8. The electrochemical device according to claim 1, wherein the electrode assembly is stacked and wound by the positive electrode tab, the separator, and the negative electrode tab to be disposed in a wound structure, an end surface of the electrode assembly is parallel to an end surface of the case, the end surface of the electrode assembly includes an electrode assembly first end surface and an electrode assembly second end surface, the electrode assembly first end surface is parallel to the electrode assembly second end surface, a positive electrode tab is connected to the electrode assembly first end surface, and a negative electrode tab is connected to the electrode assembly second end surface;
the first coated region comprises a finishing region; or the first coated region is the negative coated region.
9. The electrochemical device of claim 8, wherein a portion of the outermost pole piece of the electrode assembly closest to the casing is contiguous with the casing.
10. The electrochemical device according to claim 1, wherein the electrode assembly is stacked in a lamination structure by the positive electrode tab, the separator, and the negative electrode tab, a top surface of the electrode assembly is parallel to an end surface of the case on the first plane, and a positive electrode terminal and a negative electrode terminal are connected to the top surface of the electrode assembly;
the first side surface and the second side surface of the electrode assembly on the second plane are respectively a negative pole piece;
the first coating region includes at least one of an outer surface of the negative electrode tab at the first and second sides, an edge region at a third side of the electrode assembly on a third plane, an edge region at a fourth side of the electrode assembly on the third plane, or an edge region at a bottom surface of the electrode assembly on the first plane.
11. The electrochemical device according to claim 10,
in the first direction, the width of the edge region of the third side is the width of the negative electrode tab beyond the positive electrode tab on the third side of the electrode assembly;
the width of the edge area of the fourth side is the width of the negative electrode tab exceeding the positive electrode tab on the fourth side of the electrode assembly in the first direction;
in the second direction, a width of an edge region of the bottom surface is a width of the negative electrode tab beyond the positive electrode tab on the bottom surface of the electrode assembly.
12. The electrochemical device according to claim 11, wherein the bottom surface, the first side, the second side, the third side, and the fourth side of the electrode assembly each meet the case adjacent thereto.
13. The electrochemical device according to claim 1, wherein the first negative active material includes at least one of a lithium titanium oxide, a niobium titanium oxide, a vanadium lithium oxide, a copper lithium oxide, a germanium lithium oxide, or a modified material thereof.
14. The electrochemical device of claim 13, wherein the first negative active material comprises at least one of lithium titanate, titanium niobate, titanium-coated titanium niobate, carbon-coated titanium niobate, or nitrogen-doped titanium niobate.
15. The electrochemical device of claim 1, wherein the housing is an aluminum-plastic film or a metal shell, and the mass percentage of aluminum in the metal shell is WA＞10wt％。
16. An electronic device comprising the electrochemical device of any one of claims 1 to 15.
CN202111021300.4A 2021-09-01 2021-09-01 Electrochemical device and electronic device comprising same Pending CN113707975A (en)

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