JP2009104849A - Negative electrode collector, secondary battery, battery pack, and vehicle mounting them - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a negative electrode current collector capable of cutting off current by devising a current path of the negative electrode current collector, and by partly fusing a short circuit point of the negative electrode current collector. <P>SOLUTION: The negative electrode current collector 13 is composed of an insulating layer 13a having electric insulating characteristics, and a conductive part 13b formed on a surface of the insulating layer 13a.A plurality of metal parts extended in a battery terminal direction are independent from each other and arranged in a comb-shaped state in the conductive part 13b. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a negative electrode current collector, a secondary battery using the same, a battery pack using the same, and a vehicle equipped with these.

  A secondary battery is a chemical battery that can be repeatedly used as a battery by storing electricity by charging. The demand for secondary batteries is increasing in the fields of small devices such as digital cameras and mobile phones, and vehicle devices such as electric cars and electric bicycles. In particular, as a secondary battery for driving a motor used in vehicle equipment such as an electric vehicle, a non-aqueous electrolyte battery (also referred to as a non-aqueous solvent-type secondary battery), among them, the highest theoretical energy among all batteries. Lithium-ion secondary batteries having a high profile are attracting attention and are currently being developed rapidly.

  Taking a lithium ion secondary battery as an example, a lithium ion secondary battery generally includes a positive electrode in which a positive electrode active material or the like is applied to both surfaces of a positive electrode current collector using an adhesive (binder), and a lithium ion secondary battery. An electrolyte layer that allows movement, and a laminate (battery element) in which negative electrodes obtained by applying a negative electrode active material or the like to both surfaces of a negative electrode current collector using a binder are laminated.

  Lithium ion secondary batteries using metal foil for the positive electrode current collector and / or the negative electrode current collector are discharged due to an internal short circuit of the battery, and the voltage cannot be maintained even when charged, and there is a possibility that it cannot be used. . For this reason, in a current collector, preventing discharge due to an internal short circuit is an important issue in operating a lithium ion secondary battery with long-term reliability.

Therefore, as a technique for preventing discharge due to an internal short circuit, for example, as described in Patent Document 1 below, by forming through holes in a grid in the current collector, the contact resistance of the short circuit part is increased and short circuited. A lithium secondary battery that can reduce the current and suppress the current has been proposed (see Patent Document 1 below).
Japanese Patent No. 3696790

  However, this conventional technology uses a small-capacity battery for mobile phones as an example, and it is premised on that a small amount of current flows in the event of an abnormality, and utilizes the fact that a large current flows like a large-capacity battery for automobiles etc. However, there was no idea of melting the short-circuit portion of the current collector and blocking the short-circuit portion.

  Furthermore, assuming a large-capacity battery, even when the short-circuited portion of the current collector is melted, generally, a metal having a low melting point such as aluminum used for the material of the positive electrode current collector is in the shape of the positive electrode current collector or It is relatively easy to melt regardless of the thickness, but there is a problem that it is difficult to melt a metal having a high melting point such as copper used for the material of the negative electrode current collector.

  Therefore, the present invention solves the above-mentioned problems, devise the current path of the negative electrode current collector in a large capacity battery such as an electric vehicle, and partially melts the short-circuit portion of the negative electrode current collector to cut off the current It is an object of the present invention to provide a negative electrode current collector that can be reduced and that can suppress the influence on the voltage balance of the entire secondary battery, and a secondary battery including the same.

  The above object of the present invention is achieved by the following means.

  The negative electrode current collector of the present invention is a negative electrode current collector comprising an insulating layer having electrical insulation and a conductive part formed on the surface of the insulating layer, wherein the conductive part is a plurality extending in the battery terminal direction. The metal parts are arranged in a comb shape independently of each other.

  The secondary battery of the present invention is a secondary battery in which a negative electrode having a negative electrode active material layer on the negative electrode current collector and a positive electrode having a positive electrode active material layer are laminated via an electrolyte layer, The predetermined interval between adjacent metal parts arranged in a comb shape on the negative electrode current collector is an interval of 100 times or less the thickness of the stacked negative electrode active material layer, the electrolyte layer, and the positive electrode active material layer. It is characterized by being.

  The assembled battery of the present invention is configured by connecting the secondary batteries in series and parallel.

  The vehicle according to the present invention includes the assembled battery.

  According to the present invention, by devising the current path of the negative electrode current collector, at the time of a short circuit, the short circuit part of the negative electrode current collector is partially melted to interrupt the current, and the short circuit part is electrically separated, The influence which it has on the voltage balance of the whole secondary battery by a short circuit can be suppressed.

  Embodiments of the present invention will be described below with reference to the drawings. In the following drawings, each component is exaggerated for clarity of explanation. Moreover, the same code | symbol was used for the same member in the figure. Furthermore, in each embodiment of the present invention, a lithium ion secondary battery will be described as an example.

(First embodiment)
FIG. 1 is an external view of a lithium ion secondary battery according to the present embodiment. FIG. 2 is a cross-sectional view of the lithium ion secondary battery 100 shown in FIG. 1 cut in the battery terminal (tab) direction.

  In summary, lithium ion secondary battery 100 of the present embodiment includes a negative electrode current collector composed of an insulating layer and a conductive portion formed on the surface of the insulating layer, and the conductive portion extends in the direction of the battery terminal. The plurality of metal parts are arranged in a comb shape independently of each other.

  The lithium ion secondary battery 100 has, for example, a rectangular flat shape as shown in FIG. 1, and a positive electrode tab 30 </ b> A and a negative electrode tab 30 </ b> B for taking out electric power are drawn out from both sides thereof. . The battery element 10 is wrapped with an exterior material (for example, a laminate film) 20 of the lithium ion secondary battery 100, the periphery thereof is heat-sealed, and the battery element 10 is sealed with the positive electrode tab 30A and the negative electrode tab 30B pulled out. Yes.

  The battery element 10 is for generating electricity using a chemical reaction of a substance. As shown in FIG. 2, the battery element 10 includes a positive electrode made of a positive electrode current collector 11 and a positive electrode active material layer 12 formed on both surfaces of the positive electrode current collector 11, a negative electrode current collector 13, and a negative electrode current collector 13. And a negative electrode composed of the negative electrode active material layer 14 formed on both surfaces of the negative electrode. The battery element 10 is formed by stacking a plurality of positive electrodes and negative electrodes with an electrolyte layer 15 interposed therebetween. The positive electrode current collecting tab portion 40A is formed by extending and connecting the ends of the plurality of positive electrode current collectors 11 of the battery element 10, and is connected to the positive electrode tab 30A for taking out electricity. Moreover, the negative electrode current collection tab part 40B is extended from the edge part of the some negative electrode collector 13 of the battery element 10, and is connected with the negative electrode tab 30B for taking out electricity. In the present embodiment, positive electrode active material layer 12 and negative electrode active material layer 14 are formed only on one side of positive electrode current collector 11 and negative electrode current collector 13 located in the outermost layer of battery element 10. Yes. In the present embodiment, the positive electrode tab 30A and the negative electrode current collector 13 are prevented in order to prevent the positive electrode tab 30A from coming into contact with the negative electrode current collector 13 of the lower positive electrode current collector tab portion 40A. An insulating layer 35 is provided between the two. Similarly, in order to prevent the negative electrode tab 30B from coming into contact with the positive electrode current collector 11 of the upper negative electrode current collection tab portion 40B and short-circuiting, an insulating layer is provided between the negative electrode 30B and the positive electrode current collector 11. 35 is provided. The insulating layer 35 is made of, for example, an electric insulating tape such as Kapton tape or insulating paper. Furthermore, the number of stacked positive electrodes, negative electrodes, and electrolyte layers is not limited to the form shown in FIG.

  Hereinafter, the positive electrode current collector, the positive electrode active material layer, the electrolyte layer, the negative electrode active material layer, and the negative electrode current collector that constitute the battery element 10 will be described in detail.

[Positive electrode current collector]
The positive electrode current collector 11 includes a conductive portion 11b formed on both surfaces of the insulating layer 11a and the insulating layer 11a. The insulating layer 11a is formed from polyimide, which is a resin material having high insulating properties. Unlike the present embodiment, the insulating layer 11a is made of a thermosetting resin such as polyethylene terephthalate (PET), phenol resin, and epoxy, or rubber, vinyl chloride resin, polystyrene, ABS resin, polyethylene, polypropylene, and the like. It can be made of an extensible resin. Alternatively, the insulating layer 11a can be formed in a multilayer structure in which two or more thin films made of the above materials are combined, for example. Aluminum is preferably used for the conductive part 11b. The conductive portion 11b is not limited to aluminum, and a metal such as nickel or copper can also be used.

[Positive electrode active material layer]
The positive electrode active material layer 12 is a layer containing a positive electrode active material that plays a central role in the charge / discharge reaction of the lithium ion secondary battery 100. As the positive electrode active material, a lithium-transition metal oxide is preferably used. In addition to the lithium-transition metal oxide, a lithium-transition metal phosphate compound or a lithium-transition metal oxide compound can also be used as the positive electrode active material.

  In addition to the positive electrode active material, the positive electrode active material layer 12 includes additives such as a binder (binder) and a conductive additive. An example of the binder is polyvinylidene fluoride (PVdF). The conductive assistant is an additive blended to improve the conductivity of the active material layer, and is preferably carbon fiber.

[Electrolyte layer]
The electrolyte layer 15 is composed of, for example, a separator impregnated with an electrolytic solution. Examples of the electrolyte that can be impregnated with the separator include lithium salts such as LiPF ₆ and LiBF ₄ . As the separator, for example, a porous sheet made of a polymer that absorbs and holds an electrolyte can be used.

[Negative electrode active material layer]
The negative electrode active material layer 14 is a layer containing a negative electrode active material that plays a central role in the charge / discharge reaction of the lithium ion secondary battery 100. A carbon material is preferably used as the negative electrode active material. In addition, it is desirable to use carbon materials having different sizes in order to ensure negative electrode filling efficiency and conductivity. Examples of the carbon material include graphite-based carbon materials such as natural graphite and artificial graphite, carbon black, and activated carbon. The negative electrode active material is not limited to a carbon material, and for example, a material such as a Si-based material or a Sn-based material may be used.

  The negative electrode active material layer 14 includes additives such as a binder and a conductive additive in addition to the negative electrode active material. As the binder, a fluorine resin into which a functional group is introduced is used, for example, polyvinylidene fluoride. As the conductive assistant, carbon fiber is preferably used as in the positive electrode active material layer 12.

  Here, the weight ratio of the adhesive to the negative electrode active material, the adhesive, and the conductive additive contained in the negative electrode active material layer 14 is preferably 6% or less. The binder in the negative electrode active material layer 14 can be bound even if the amount of the binder added is reduced by using a resin having good adhesiveness to the insulator (insulating layer 13a) serving as the base material of the negative electrode current collector 13. Can keep sex. Therefore, by covering the negative electrode current collector 13 and setting the binder that inhibits the reaction to 6% or less, the output of the negative electrode can be improved and the content of the negative electrode active material can be increased, so that the energy density is also increased. be able to.

[Negative electrode current collector]
The negative electrode current collector 13 includes a conductive portion 13b formed on both surfaces of the insulating layer 13a and the insulating layer 13a. Specifically, the negative electrode current collector 13 has a plurality of metal parts in which the conductive parts 13b extend in the battery terminal direction (in the tab 30B direction) on both surfaces of the insulating layer 13a independently of each other in a comb shape. To be arranged. Therefore, the negative electrode current collector 13 has a higher conductivity in the battery terminal direction than in the direction perpendicular to the battery terminal direction. The predetermined interval between adjacent metal parts arranged in a comb shape is an interval of 100 times or less the thickness of the stacked negative electrode active material layer 14, electrolyte layer 15, and positive electrode active material layer 12. A detailed description of the conductive portion 13b will be described later.

  The insulating layer 13a is formed from polyimide, which is a resin material having high insulating properties. Unlike this embodiment, the insulating layer 13a is made of a thermosetting resin such as polyethylene terephthalate (PET), phenol resin, and epoxy, or rubber, vinyl chloride resin, polystyrene, ABS resin, polyethylene, polypropylene, and the like. It can be made of an extensible resin. Alternatively, the insulating layer 13a can be formed in a multilayer structure in which two or more thin films made of the above materials are combined, for example. The thickness of the insulating layer 13a is desirably 3 to 30 μm. If the thickness of the insulating layer 13a is 3 μm or less, it is not possible to ensure a sufficient thickness to withstand the tension applied by the coating device in the coating step of coating the current collector foil on the surface of the insulating layer 13a. Further, if the thickness of the insulating layer 13b is 30 μm or more, it is not preferable from the viewpoint of minimizing the weight increase of the negative electrode current collector 13.

  The conductor portion 13b is made of copper that is not alloyed with lithium, and is formed integrally with the insulating layer 13a by vapor deposition or the like. The conductive portion 13b is not limited to copper, and for example, a metal that does not alloy with lithium, such as nickel, can be used. It is desirable that the average thickness of copper on the entire surface area of the insulating layer 13a (the thickness where the copper is not formed on the surface area is 0) is 0.1 to 5 μm. That is, the average thickness of copper as the current collector foil needs to ensure a thickness that allows a rated current to flow sufficiently. The closer to the battery terminal that is the external terminal, the larger the current flowing through the current collector foil, and the thickness to be secured differs depending on the dimension of the external terminal in the vertical direction and the shape of the external terminal. When the aspect ratio of the current collector foil is between 1: 5 and 10: 1, a thickness of 0.1 μm to 5 μm is required.

  Here, the conventional negative electrode current collector is generally formed of only a metal and has a thickness of 10 μm. However, the negative electrode current collector has a thickness that is sufficient to satisfy the purpose of flowing current. However, this thickness is determined by the rolling accuracy of the copper foil as the current collector foil, the tensile strength at which the foil is pulled during application, and the like. Therefore, in the lithium ion secondary battery 100 of the present embodiment, sufficient electrical conductivity is secured and copper is maintained by attaching a metal thin film that does not alloy with lithium, such as copper, to the insulating layer (resin) 13a. The weight can be reduced by giving the insulating layer (resin) the tensile strength that has been achieved. That is, when copper is used as the material of the conductive portion 13b and polyimide is used as the material of the insulating layer 13a, the respective densities are approximately 9 g / cc for copper and 0.8 to 1.5 g / cc for polyimide. Therefore, it is desirable that the thickness of the insulating layer 13a be 6 times or less that of the reduced copper.

  Hereinafter, the structure of the insulating layer 13a and the conductive portion 13b of the negative electrode current collector 13 which is a feature of the lithium ion secondary battery 100 of the present embodiment will be described in detail.

  FIG. 3 is a diagram illustrating the shape of the conductive portion 13b of the negative electrode current collector 13 of the lithium ion secondary battery 100 of the present embodiment.

  As shown in FIG. 3A, a plurality of conductive portions 13b of the negative electrode current collector 13 are formed in a comb-like pattern with copper extending in the battery terminal direction (in the tab 120B direction) at a predetermined interval. The That is, the conductive portion 13b is composed of a metal portion 50a made of a plurality of linear coppers located on the surface of the insulating layer 13a. Moreover, the lithium ion secondary battery 100 of this Embodiment has the metal part 50b which joins the some metal part 50a and connects with the negative electrode tab 30B. The metal part 50b also becomes the negative electrode current collecting tab part 40B, and a plurality of metal parts 50a are joined to the negative electrode tab 30B.

  By forming the conductive portion 13b in such a comb-shaped pattern, the purpose of flowing the current of the negative electrode current collector 13 along the current path as shown in FIG. it can. Further, even if a short-circuit current occurs in the lithium ion secondary battery 100, as shown in FIG. 3B, a part of the conductive portion 13b is evaporated due to the current concentration around the short portion, and only the short portion is not allowed. Can be activated. For reference, taking the case where the conductive portion of a conventional lithium ion secondary battery is flat as an example, the current flows along the current path as shown in FIG. At time, as shown in FIG. 4B, the influence on the output of the entire secondary battery was large.

  Next, an interval L1 (hereinafter referred to as “pattern interval”) between adjacent metal portions 50a arranged in a comb shape of the conductive portion 13b will be described.

  FIG. 5 is a schematic view illustrating a cross section of a part of the battery element 10 for explaining the pattern interval. On the negative electrode current collector 13, the negative electrode active material layer 14, the electrolyte layer 15, and the positive electrode active material are illustrated. A state in which the layer 12 is laminated is shown. FIG. 6 is a diagram showing the relationship between the pattern interval L1 and the internal resistance. The internal resistance represents the sum of the resistance when lithium ions transmit the electrolyte and the resistance when electrons transmit the negative electrode active material.

  As shown in FIG. 5, the thickness of each layer is, for example, 15 μm for the positive electrode current collector 11, 80 μm for the positive electrode active material layer 12, 20 μm for the electrolyte layer (separator) 15, and 80 μm for the negative electrode active material layer 14 (electrolyte layer). 15 to the insulating layer 13a), the metal portion 50a (conductive portion 13b) is 25 μm, and the insulating layer 13a is 25 μm. Further, the resistivity R1 of the electron movement path (hereinafter referred to as “conductive network”) through the negative electrode active material of the negative electrode is generally about 1/1000 of the resistivity R2 of the electrolyte. Further, since the pattern interval L1 is provided, electrons located within the pattern interval move to the adjacent conductive portion 13b via the conductive network.

  Here, when the maximum value of the internal resistance is considered, the internal resistance is maximized because the lithium in the electrolyte is located above the positive electrode active material layer 12 (the positive electrode current collector 11 as shown in FIG. 5). This is a case in which electrons move from the portion approaching to the lower part of the negative electrode active material layer 14 (part approaching the negative electrode current collector 13) and electrons are generated at the center of the pattern interval L1. That is, the maximum movement distance of lithium in the electrolyte includes the positive electrode active material layer 12, the electrolyte layer 15, and the negative electrode active material layer 14 including the electrolyte in the positive electrode active material layer 12 and the negative electrode active material layer 14. The distance is L2 (180 μm). Therefore, the maximum resistance when lithium moves from the upper part of the positive electrode active material layer 12 to the insulating layer 13a can be expressed by L2 × R2. Further, when electrons are generated at the center of the pattern interval L1, the distance that the electrons move through the conductive network to the adjacent conductive portion 13b is L1 / 2. Therefore, the resistance is expressed by L1 / 2 × R1. Can do. From the above, the maximum value of the internal resistance can be represented approximately by (L2 × R2) + (L1 / 2 × R1).

  Therefore, for example, when the pattern interval L1 is 100 times the distance L2 (L1 = L2 × 100), the relationship between the resistivity R1 and R2 is R1 × 1000 = R2, and thus the maximum internal resistance is It can be expressed as 1.05 × L2 × R2. Therefore, when there is no pattern interval L1, that is, when the conductor 13b is uniformly formed on the entire surface of the insulating layer 13a, the maximum internal resistance is L2 × R2, so the pattern interval L1 is 100 times L2. If it is set below, the increase in internal resistance can be suppressed to 10% or less. If the pattern interval L1 is increased, the internal resistance rapidly increases as shown in FIG. 6, and the performance of the battery is significantly deteriorated. Therefore, the pattern interval L1 is set to the negative electrode active material layer 14, the electrolyte layer 15, and the positive electrode. It is desirable that the distance is 100 times or less the thickness of the laminated active material layer 12.

  Further, as shown in FIG. 7, the minimum interval of the pattern interval L1 is preferably about the same as that of the negative electrode active material in order to ensure a sufficient binding force.

  As described above, the lithium ion secondary battery 100 of the present embodiment has the following effects.

  (A) When a current flows through the metal extending in the direction of the battery terminal near the short-circuited location, only the metal around the short-circuited location is melted and cut off, the short-circuited location is electrically separated, Performance degradation can be suppressed.

  (B) The interval between adjacent metal parts extending in the direction of adjacent battery terminals is set to an interval of 100 times or less the thickness obtained by laminating the negative electrode active material layer, the electrolyte layer, and the positive electrode active material layer. Sufficient output current can be flowed by suppressing the resistance increase to 1/10 or less of the resistance, and deterioration of the battery performance can be suppressed even if a certain interval is provided.

  (C) By setting the thickness of the insulating layer of the negative electrode current collector to 3 to 30 μm, it is possible to withstand the tension applied in the application step of applying a current collector foil such as copper, and to ensure the yield. . Furthermore, by giving the insulating layer the tensile strength that copper has maintained, the amount of copper can be reduced, the overall weight of the lithium ion secondary battery can be reduced, and a battery with a high weight energy density can be supplied. it can.

  (D) By setting the average thickness of the metal to 0.1 to 5 μm, the output current (rated current) can flow sufficiently, and the heat generation by the current collector foil when the rated current is passed for a short time is suppressed. In the case of initial failure, the short part can be evaporated.

  (E) By making the conductivity in the battery terminal direction higher than the conductivity in the direction perpendicular to the battery terminal direction, it is possible to ensure a uniform current distribution and good conductivity in the energization direction of the rated current while maintaining a short current. It is possible to suppress heat generation by the current collector foil when a rated current is passed for a time and to evaporate a short portion at the time of initial failure.

  (F) By reducing the weight ratio of the adhesive to the negative electrode active material, the adhesive, and the conductive additive contained in the negative electrode active material layer to 6% or less, the ratio of the binder covering the carbon surface is reduced, and the electrolyte and Since the reaction surface in contact with carbon can be increased, the energy density of the battery can be increased. In addition, the proportion of the electrolyte in the space between the carbon material, which is the negative electrode active material, increases, and the obstacle of ion conduction decreases, so the ionic resistance decreases and the power density of the battery increases. Can do.

(Second Embodiment)
Next, the lithium ion secondary battery according to the second embodiment of the present invention will be described in detail.

  In the lithium ion secondary battery of the second embodiment, the shape of the metal part 50a constituting the conductive part 13b of the negative electrode current collector 13 is different from that of the first embodiment.

  As shown in FIG. 8, the conductive part 13b of the negative electrode current collector in the lithium ion secondary battery of the second embodiment has a first metal part 501 having a resistance value different from that of the metal part 50a extending in the battery terminal direction. And the second metal portion 502 are repeatedly connected. In addition, about the structure similar to 1st Embodiment, the description of the said 1st Embodiment shall be referred and description is abbreviate | omitted below.

  The conductive portion 13b of the negative electrode current collector 13 has a linear conductive path in the direction in which the rated current is applied, and has a pattern in which the current detours to the short portion in the event of a short circuit or the like, and the current concentrates on a thin conductive path. Therefore, in the conductive part 13b having a shape as shown in FIG. 8, a current flows through the first metal part 501 and the second metal part 502 in the battery terminal direction, and in the case of a short circuit, the conductive part 13b is more resistant than the first metal part 501. The current concentrates on the second metal part 502 having a large current, and the second metal part 502 is melted and the current is easily interrupted.

  Note that the conductive portion 13b is not limited to the shape of FIG. 8A, but has various shapes such as the shape of FIG. 8B in order to increase the adhesive strength with the insulating layer 13a or the negative electrode active material layer. Can be.

  As described above, the described embodiment has the following effects in addition to the effects (a) to (f) of the first embodiment.

  (G) In the energizing direction of the rated current, a uniform current distribution and good conductivity are ensured, and when a defect such as a short circuit occurs, a pattern is formed so that the current density around the short circuit part increases. It is possible to obtain characteristics that are easy to evaporate in a shorter time.

(Third embodiment)
Next, a lithium ion secondary battery according to a third embodiment of the present invention will be described in detail. In the lithium ion secondary battery of the third embodiment, the shape of the metal part 50a constituting the conductive part 13b of the negative electrode current collector is different from those of the first and second embodiments. That is, as shown in FIG. 9, the arrangement | sequence of the metal part 50a extended in a battery terminal direction arranges the some 3rd metal part 503 in a pattern form. At this time, by reducing the portion where the third metal portions 503 come into contact with each other, the resistance at the contact portion becomes larger than the resistance of the metal portion 503 itself. For the same configuration as the first embodiment, the description of the first embodiment is referred to, and the description is omitted below.

  In the conductive portion 13b having the shape as shown in FIG. 9, current flows through the plurality of third metal portions 503 in the battery terminal direction, and current is concentrated at a portion where the third metal portions 503 are in contact with each other at the time of short circuit. However, the contact portion melts and the current is easily interrupted.

  In addition, as shown to Fig.9 (a), as for the electroconductive part 13b, the shape which a contact part may contact the 2nd 3rd metal part 503 which adjoins may be sufficient, as shown in FIG.9 (b). Further, the contact portion may be in contact with one adjacent third metal portion 503.

  As described above, the present embodiment described has the following effects in addition to the effects (a) to (g) of the first and second embodiments.

  (H) By forming each of the plurality of metal portions extending in the battery terminal direction with a plurality of the same third metal portions, the first metal portion and the second metal portion having different resistance values are formed. In addition, the manufacturing process can be simplified.

(Fourth embodiment)
Next, a lithium ion secondary battery according to a fourth embodiment of the present invention will be described in detail. In the lithium ion secondary battery of the third embodiment, the shape of the metal part 50a constituting the conductive part 13b of the negative electrode current collector is different from that of the first to third embodiments.

  As shown in FIG. 10, the conductive part 13b of the negative electrode current collector in the lithium ion secondary battery of the fourth embodiment is a fourth metal part having a resistance value different from that of the metal part 50a extending in the battery terminal direction. 504 and the fifth metal portion 505 are repeatedly connected. A plurality of adjacent fourth metal parts 504 are connected by a fifth metal part 505 having a resistance higher than that of the fourth metal part 504. For the same configuration as the first embodiment, the description of the first embodiment is referred to, and the description is omitted below.

  In the conductive part 13b having a shape as shown in FIG. 10, a current flows through the fourth metal part 504 and the fifth metal part 505 in the battery terminal direction, and the resistance is larger than that of the fourth metal part 504 at the time of a short circuit. The current concentrates on the fifth metal part 505, the fifth metal part 505 is melted, and the current is easily interrupted.

  The conductive portion 13b is not limited to the shape shown in FIGS. 10A and 10B, and can have various shapes.

  As described above, the present embodiment described has the following effects in addition to the effects (a) to (g) of the first and second embodiments.

  (I) A current collector foil and an active material layer made of metal by constituting a plurality of metal parts extending in the battery terminal direction with a metal part having a large surface area covering the insulating layer and a metal part connecting them. Thus, it is possible to supply a battery having a long service life.

(Fifth embodiment)
The assembled battery of the present embodiment is configured by connecting the lithium ion secondary batteries described in the first to fourth embodiments in series and parallel. By connecting lithium ion secondary batteries in series or in parallel, the capacity and voltage of the assembled battery can be freely adjusted.

  FIG. 11 is an external view showing an example of the assembled battery according to the present embodiment. FIG. 11A is a plan view of the assembled battery, FIG. 11B is a plan view of the assembled battery, and FIG. 11C is an assembled battery. It is a side view of a battery.

  For example, as shown in FIG. 11, the assembled battery 300 of the present embodiment is configured by connecting a plurality of small battery modules 250 that can be attached and detached using a connecting jig 310. The battery module 250 can be formed by connecting a plurality of the lithium ion secondary batteries of the above embodiments, in series or in parallel. The connection jig 310 is an electrical connection means and connects the plurality of battery modules 250 to each other.

  As described above, the described embodiment has the following effects in addition to the effects of the first to third embodiments.

  (J) The assembled battery of this embodiment is configured by connecting the lithium ion secondary batteries shown in the first to fourth embodiments in series or in parallel. Therefore, since a secondary battery with excellent durability is used, long-term reliability due to battery voltage imbalance can be improved. In addition, a lighter assembled battery can be provided by reducing the amount of copper used for the negative electrode current collector and using a secondary battery using an insulating layer having a low density.

(Sixth embodiment)
The vehicle according to the present embodiment is mounted with the lithium ion secondary battery described in the first to fourth embodiments or the assembled battery described in the fifth embodiment. Such lithium ion secondary batteries, battery modules, and / or assembled batteries can be mounted on vehicles such as automobiles and trains, and used as power sources for driving electric devices such as motors.

  FIG. 12 is a schematic configuration diagram showing an automobile as a vehicle according to the sixth embodiment of the present invention.

  In order to mount the assembled battery 300 on the electric vehicle 400, the battery pack 300 is mounted under the seat in the center of the vehicle body of the electric vehicle 400 as shown in FIG. If it is installed under the seat, the interior space and the trunk room can be widened. In addition, the place where the assembled battery 300 is mounted is not limited to under the seat, and may be a lower part of the rear trunk room or an engine room in front of the vehicle. The electric vehicle 400 using the assembled battery 300 as described above has high durability and can provide sufficient output even when used for a long period of time. Furthermore, it is possible to provide an electric vehicle and a plug-in hybrid vehicle (PHEV) excellent in fuel consumption and driving performance. Moreover, in order to use as such a power supply for vehicles, it is preferable that the internal resistance of a lithium ion secondary battery is about 1-5 m (ohm).

  In the present invention, not only the assembled battery 300 but also only the battery module 250 may be mounted depending on the intended use, or the assembled battery 300 and the battery module 250 may be mounted in combination. .

  As described above, the described embodiment has the following effects in addition to the effects of the first to fifth embodiments.

  (K) The electric vehicle of the present embodiment is mounted with the lithium ion secondary battery or the assembled battery shown in the first to fifth embodiments as a driving power source. Therefore, since the secondary battery excellent in durability is used, the reliability of the electric vehicle can be improved. In addition, by reducing the amount of copper used for the negative electrode current collector and using a secondary battery using an insulating layer with a low density, vehicles such as hybrid cars, electric cars, and fuel cell cars that are low in weight and good in fuel efficiency can be used. Can be provided.

  The preferred embodiments of the present invention have been described above. However, the present invention should not be limited to the above embodiments, and does not depart from the spirit and scope expressed in the claims. Various modifications, additions, and omissions are possible by those skilled in the art.

  For example, in the present embodiment, the negative electrode current collector has been described as an example, but it is needless to say that the positive electrode current collector can have the same configuration with the same idea.

1 is an external view of a lithium ion secondary battery according to a first embodiment of the present invention. It is sectional drawing which cut | disconnected the lithium ion secondary battery shown in FIG. 1 in the battery terminal (tab) direction. It is a figure showing the shape of the electroconductive part of the negative electrode collector of the lithium ion secondary battery of the 1st Embodiment of this invention. It is a figure showing the shape of the electroconductive part of the negative electrode collector of the conventional lithium ion secondary battery. It is the schematic which illustrated the cross section of a part of battery element in order to demonstrate the pattern space | interval of the lithium ion secondary battery which concerns on the 1st Embodiment of this invention. It is a figure which shows the relationship between the pattern space | interval and internal resistance of the lithium ion secondary battery which concerns on the 1st Embodiment of this invention. It is the schematic which illustrated the cross section of a part of battery element in order to demonstrate the pattern space | interval of the lithium ion secondary battery which concerns on the 1st Embodiment of this invention. It is a figure showing the shape of the electroconductive part of the negative electrode collector of the lithium ion secondary battery of the 2nd Embodiment of this invention. It is a figure showing the shape of the electroconductive part of the negative electrode collector of the lithium ion secondary battery of the 3rd Embodiment of this invention. It is a figure showing the shape of the electroconductive part of the negative electrode collector of the lithium ion secondary battery of the 4th Embodiment of this invention. It is a figure which shows the assembled battery which is the 5th Embodiment of this invention. It is a figure which shows the vehicle which is the 6th Embodiment of this invention.

Explanation of symbols

11 positive electrode current collector,
12 positive electrode active material layer,
13 negative electrode current collector,
13a insulating layer,
13b conductive part,
14 negative electrode active material layer,
15 Electrolyte layer.

Claims (9)

A negative electrode current collector comprising an insulating layer having electrical insulation and a conductive portion formed on the surface of the insulating layer,
The negative electrode current collector, wherein the conductive portion includes a plurality of metal portions extending in a battery terminal direction and arranged in a comb shape independently of each other. A secondary battery in which a negative electrode having a negative electrode active material layer on a negative electrode current collector according to claim 1 and a positive electrode having a positive electrode active material layer are laminated via an electrolyte layer,
The predetermined interval between adjacent metal parts arranged in a comb shape on the negative electrode current collector is an interval of 100 times or less the thickness of the stacked negative electrode active material layer, the electrolyte layer, and the positive electrode active material layer. A secondary battery characterized by the above.   The secondary battery according to claim 2, wherein the insulating layer has a thickness of 3 to 30 μm.   3. The secondary battery according to claim 2, wherein an average thickness of the metal portion over the entire surface area of the insulating layer is 0.1 to 5 μm.   The secondary battery according to any one of claims 2 to 4, wherein conductivity in a battery terminal direction is higher than conductivity in a direction perpendicular to the battery terminal direction.   6. The secondary battery according to claim 5, wherein each metal portion extending in the battery terminal direction is arranged by repeatedly connecting a first metal portion and a second metal portion having different resistance values. .   3. A negative electrode active material, an adhesive, and a conductive assistant, wherein the weight ratio of the adhesive to the negative active material, the adhesive, and the conductive assistant is 6% or less. The secondary battery according to any one of 6.   An assembled battery comprising the secondary batteries according to claim 7 connected in series and parallel.   A vehicle to which the assembled battery according to claim 8 is applied.

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