CN112029452A - Preparation method and application of adhesive capable of improving battery rate performance - Google Patents

Preparation method and application of adhesive capable of improving battery rate performance Download PDF

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CN112029452A
CN112029452A CN202010946511.8A CN202010946511A CN112029452A CN 112029452 A CN112029452 A CN 112029452A CN 202010946511 A CN202010946511 A CN 202010946511A CN 112029452 A CN112029452 A CN 112029452A
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reactant
binder
mass
battery
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CN112029452B (en
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李娟�
马艳
唐姚
庄卫东
孙延先
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Huading Guolian Sichuan Battery Material Co ltd
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Huading Guolian Sichuan Battery Material Co ltd
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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J151/00—Adhesives based on graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Adhesives based on derivatives of such polymers
    • C09J151/003—Adhesives based on graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Adhesives based on derivatives of such polymers grafted on to macromolecular compounds obtained by reactions only involving unsaturated carbon-to-carbon bonds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F259/00—Macromolecular compounds obtained by polymerising monomers on to polymers of halogen containing monomers as defined in group C08F14/00
    • C08F259/08—Macromolecular compounds obtained by polymerising monomers on to polymers of halogen containing monomers as defined in group C08F14/00 on to polymers containing fluorine
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F265/00—Macromolecular compounds obtained by polymerising monomers on to polymers of unsaturated monocarboxylic acids or derivatives thereof as defined in group C08F20/00
    • C08F265/02—Macromolecular compounds obtained by polymerising monomers on to polymers of unsaturated monocarboxylic acids or derivatives thereof as defined in group C08F20/00 on to polymers of acids, salts or anhydrides
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
    • C09J11/02—Non-macromolecular additives
    • C09J11/06—Non-macromolecular additives organic
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • 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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Abstract

The invention belongs to the technical field of battery materials, and particularly relates to a preparation method and application of a binder capable of improving the rate capability of a battery. The binder of the lithium ion battery is mainly obtained by taking a substance containing an electron conducting group, a substance containing an ion conducting group, a substance containing a doping group and the like as main raw materials through a polymerization reaction, can reduce the migration energy barrier of electrons and ions, reduce polarization and internal resistance and improve the multiplying power performance of the battery; the electron delocalized group can form a strong double-electric-layer structure with a current collector, in addition, the macromolecular polymer in the main group of the adhesive can improve the adhesive force among molecules, between molecules and active materials and between conductive agents, and the small molecular polymer has low Tg and can be effectively infiltrated and adhered to the current collector to improve the cycle performance of the battery; the improvement of the intrinsic conductivity and the binding power of the binding agent can reduce the using amount of the conductive agent and the binding agent and improve the overall capacity of the lithium battery.

Description

Preparation method and application of adhesive capable of improving battery rate performance
Technical Field
The invention belongs to the technical field of battery materials, and particularly relates to a preparation method and application of a binder capable of improving the rate capability of a battery.
Background
Lithium ion batteries have played an increasingly important role in new energy sources due to their high energy density, which exceeds 150WhKg-1Almost all known secondary batteries have the highest energy density. In order to further improve the performance of lithium ion batteries, researchers have tried to find new electrode materials, electrolytes and additives, however, the efficiency of lithium ion batteries depends largely on the optimization of the electrode preparation conditions, and one of the important aspects is to find the most suitable binder for the electrode. The binder is an important component in the positive and negative electrode materials of the lithium battery, can tightly bind the active material, the conductive agent and the current collector in the electrode materials, enhances the electronic contact between the active material and the conductive agent as well as between the active material and the current collector, and better stabilizes the structure of the pole piece.
Currently, polyvinylidene fluoride (PVDF) is widely used as a positive electrode binder of a lithium ion battery in a commercial lithium ion battery because PVDF has good electrochemical stability and high binding power to an electrode material and a current collector. However, with the market demand for high energy density, high rate performance, and the like of lithium batteries, development of a novel binder is urgently needed.
Regarding the improvement of the binder to improve the rate of battery performance, the following patent documents are disclosed:
CN107230772A provides a high-nickel ternary material composite binder, which comprises 20-35 wt% of suspension polymerized polyvinylidene fluoride (PVDF) and 65-80 wt% of emulsion polymerized PVDF. Meanwhile, the invention also discloses a positive electrode slurry containing the composite binder for the high-nickel ternary material and a corresponding preparation method, which can effectively overcome the defects of wider particle size distribution, easy water absorption and the like of NCA (nickel-cobalt-aluminum) particles, furthest reduce the adverse effect caused by the easy water absorption of the nickel oxide-cobalt-aluminum NCA material, obviously improve the overall performance of the finally prepared positive electrode plate, facilitate the improvement of the market application prospect of battery manufacturer products, promote the wide production and application and have great production practice significance.
The binder disclosed in the above patent documents contains a large amount of F element, and the prepared high-alkaline ternary positive electrode slurry is prone to chemical gelation, which further affects slurry processability and battery electrochemical performance.
The CN104752729B patent discloses a preparation method of an aqueous composite binder with electronic and ionic conductivity commonalities for lithium ion batteries, which is formed by blending a flexibilizer, an ionic binder and a water-soluble polymer to form a polymer matrix, wherein the ionic binder provides a lithium source, and the polymer matrix can conduct lithium ions; the conductive agent is dispersed in the polymer matrix to form a composite conductive polymer, and the filler forms a conductive network in a polymerization system. The aqueous composite binder prepared by the invention is an electronic conductor and an ionic conductor, can effectively increase the content of lithium ions in the positive plate, and improves the cycling stability of the battery. The preparation method comprises the following steps: (1) dissolving a flexibilizer in water; secondly, adding a water-soluble polymer into the solution, and stirring until the water-soluble polymer is dissolved; thirdly, adding the ionic binder into the solution obtained in the second step, and stirring until the ionic binder is completely dissolved to obtain a polymer matrix; fourthly, adding a conductive agent into the polymer matrix, and uniformly dispersing; wherein the flexibilizer is partially hydrolyzed polyacrylamide with the weight percentage of
Figure BDA0002675468130000021
Said water-soluble polymerThe substance is polyvinyl alcohol with the weight percentage of
Figure BDA0002675468130000022
The ionic adhesive is carboxymethyl cellulose lithium, and the weight percentage of the ionic adhesive is
Figure BDA0002675468130000023
The conductive agent is any one or more selected from acetylene black, graphite, graphene and carbon nano tubes, and the weight percentage of the conductive agent is
Figure BDA0002675468130000024
The electrodes in the above method mainly use various conductive agents to provide electron moving channels. The conductive agent has a large proportion, and the content of the active main material can be reduced to a certain extent, so that the capacity of the whole battery is influenced.
Therefore, there is a need to improve the deficiencies of the methods provided in the above-mentioned patent documents, and to invent a binder that can significantly increase the battery rate without affecting the battery capacity and the electrochemical performance of the battery.
Disclosure of Invention
In order to solve the technical problems, the invention provides a preparation method of a binder of a lithium ion battery, which can obviously improve the rate capability and the cycle performance of the battery and improve the capacity of the lithium battery;
the adhesive is mainly obtained by taking a substance containing an electron conducting group, a substance containing an ion conducting group, a substance containing a doping group and the like as main raw materials through polymerization reaction;
the substance containing the doping group improves the electron delocalization of the main chain of the binder, thereby achieving the purpose of modifying the conductivity of the binder; the electron-conducting group-containing substance and the ion-conducting group-containing substance improve the electron-conducting and ionic properties of the binder by grafting.
The preparation method of the binder of the lithium ion battery provided by the invention comprises the following steps:
(1) mixing a binder monomer, a medium and a first free radical initiator, heating to 40-45 ℃, adding a substance containing a doping group and a crosslinking auxiliary agent, and slowly introducing acetylene gas to obtain a reactant B;
(2) mixing the reactant B, the substance containing the electronic conducting group, the substance containing the ionic conducting group and a second free radical initiator, and heating to 60-100 ℃ to obtain a polymer C1, wherein the molecular weight of C1 is 1-10 w;
(3) repeating the steps (1) to (2), and increasing the heating reaction temperature in the step (1) to 60-85 ℃ to obtain a second polymer C2, wherein the molecular weight of C2 is 30-80 w;
(4) and mixing the reactant C1, the reactant C2, the cross-linking agent, the third radical initiator and the additive alkali, and heating to 60-100 ℃ to obtain the binder.
Preferably, (1) the binder monomer is selected from any one of acrylic acid monomers and vinylidene fluoride monomers; the medium is water; the first free radical initiator is selected from any one of persulfate, azobisisobutyronitrile and acyl peroxide; the substance containing the doping group is selected from any one of diisocyanate and pyrrole monomers;
the mass ratio of the binder monomer to the medium is 1: 2-1: 5; the first free radical initiator accounts for 0.05-0.1% of the mass of the binder monomer;
the crosslinking auxiliary agent is acrylic acid; the crosslinking auxiliary agent accounts for 0-0.3% of the mass of the binder monomer;
acetylene accounts for 10-30% of the mass of the binder monomer.
Preferably, in (2), the substance containing an electron-conducting group is any one of styrene and aniline monomers;
the substance containing the ion conducting group is any one of lithium styrene sulfonate and lithium acrylate;
the substance containing the electron conductor group accounts for 5-15% of the reactant B; the substance containing the ion conductor group accounts for 10-20% of the reactant B;
the second free radical initiator is selected from any one of persulfate, azobisisobutyronitrile and acyl peroxide; the second radical initiator accounts for 0.05-0.1% of the mass of the reactant B.
Preferably, in (4), theThe coupling agent is selected from alcohols and CH2I2Any one of (a); the cross-linking agent accounts for 0.1-0.3% of the sum of the mass of the reactant C1 and the mass of the reactant C2; the additive is sodium hydroxide; the additive accounts for 0-0.1% of the sum of the mass of the reactant C1 and the mass of the reactant C2; the mass ratio of the reactant C1 to the reactant C2 is 1: 4-12;
the third free radical initiator is selected from any one of persulfate, azobisisobutyronitrile and acyl peroxide; the third free radical initiator accounts for 0.05-0.1% of the sum of the mass of the reactant C1 and the mass of the reactant C2.
As a preferred mode, the method for preparing the binder capable of improving the rate capability of the battery comprises the following steps:
(1) adding a doping auxiliary agent into a reaction kettle, heating to 40-45 ℃, and then slowly adding a substance containing a doping group to perform nucleophilic reaction to obtain a reactant A;
(2) mixing a binder monomer, a medium and a first free radical initiator, and heating to 40-50 ℃; then adding the reactant A and the crosslinking assistant, and slowly introducing acetylene gas to obtain a reactant B;
(3) mixing the reactant B, the substance containing the electronic conducting group, the substance containing the ionic conducting group and a second free radical initiator, and heating to 60-100 ℃ to obtain a polymer C1, wherein the molecular weight of C1 is 1-10 w;
(4) repeating the steps (1) - (3), and increasing the reaction temperature in the step (2) to 60-85 ℃;
(5) and mixing the reactant C1, the reactant C2, the cross-linking agent, the third radical initiator and the additive, and heating to 60-100 ℃ to obtain the binder.
Preferably, in the step (1), the doping auxiliary agent is an enol substance; the mol ratio of the doping auxiliary agent to the doping group-containing substance is 2: 1-2.1: 1;
the substance containing the doping group is selected from any one of diisocyanate and pyrrole monomers.
Preferably, (2) the binder monomer is selected from any one of acrylic acid monomers and vinylidene fluoride monomers; the medium is water; the first free radical initiator is selected from any one of persulfate, azobisisobutyronitrile and acyl peroxide;
the mass ratio of the binder monomer to the medium is 1: 2-1: 3; the first free radical initiator accounts for 0.05-0.1% of the mass of the binder monomer;
the crosslinking auxiliary agent is acrylic acid; the crosslinking auxiliary agent accounts for 0-0.3% of the mass of the binder monomer;
the reactant A accounts for 5-10% of the mass of the binder monomer;
acetylene accounts for 10-30% of the mass of the binder monomer.
Preferably, in (5), the crosslinking agent is selected from alcohols and CH2I2Any one of (a); the cross-linking agent accounts for 0.1-0.3% of the sum of the mass of the reactant C1 and the mass of the reactant C2; the mass ratio of the reactant C1 to the reactant C2 is 1: 4-12;
the third free radical initiator is selected from any one of persulfate, azobisisobutyronitrile and acyl peroxide; the third free radical initiator accounts for 0.05-0.1% of the sum of the mass of the reactant C1 and the mass of the reactant C2;
the additive is alkali; the additive accounts for 0-0.1% of the sum of the mass of the reactant C1 and the mass of the reactant C2.
Preferably, the method further comprises washing and drying the obtained binder to obtain a finished binder.
The binder of the lithium ion battery is applied to the coating field of the anode, the cathode and the diaphragm of the battery; and the binder is mixed with the conventional binder and then applied to the coating field of the anode, the cathode and the diaphragm of the battery, which are both the protection scope of the invention.
The binder prepared by the method can reduce the electron and ion migration energy barrier, reduce polarization and internal resistance and improve the rate capability of the battery; the electron delocalized group can form a strong double-electric-layer structure with the current collector, in addition, the macromolecular polymer in the adhesive can improve the adhesive force among molecules, between molecules and active materials and between conductive agents, and the micromolecular polymer has low Tg, can be effectively infiltrated and adhered to the current collector, and improves the cycle performance of the battery; the improvement of the intrinsic conductivity and the binding power of the binding agent can reduce the using amount of the conductive agent and the binding agent and improve the overall capacity of the lithium battery.
The improvement of the conductivity and the binding power of the binding agent can reduce the using amount of the conductive agent and the binding agent, improve the overall capacity of the lithium battery and avoid the defect that the battery capacity is influenced in the CN104752729B proposal mentioned in the background technology.
The ionic conductivity of the product reaches 5 multiplied by 10 at room temperature-4～3×10-3S/cm, electron conductivity 2X 10-3～8×10-3S/cm；
The capacity retention rate of the battery (using PAA1) at 25 ℃ of 1.5C, 2C and 2.5C/0.5C reaches 86.3-90.6%, 82.5-87.5% and 78.6-82.9%;
the capacity retention rate of the battery at 25 ℃ and 1C/1C cycle of 200T is 91.8-93.5%.
Detailed Description
The present invention will be further described with reference to specific examples so that those skilled in the art may better understand the present invention, but the present invention is not limited thereto.
Example 1A
(1) Adding doping auxiliary agent allyl alcohol into a reaction kettle, heating to 45 ℃, reacting for 3 hours, slowly adding doping group substance diisocyanate (allyl alcohol: diisocyanate is 2.1:1, mol ratio) for nucleophilic reaction to obtain a reactant A1；
(2) Mixing a binder acrylic monomer, an aqueous medium and an initiator persulfate, heating to 45 ℃, and adding the reactant A obtained in the step (1)1Then acetylene gas is slowly introduced to obtain an acrylic polymer B with smaller molecular weight1；
Wherein the acrylic monomer: 1: 2.5 (mass ratio), wherein the persulfate accounts for 0.06 percent of the mass of the acrylic monomer; reactant A16 percent of the mass of the acrylic monomer; acetylene accounts for 20 percent of the mass of the acrylic monomer;
(3) reacting the reactant B1Mixing styrene containing an electronic conducting group, lithium styrene sulfonate containing an ionic conducting group and an initiator persulfate, and heating to 90 ℃ to obtain the acrylic polymer C1 with improved grafting1A molecular weight of about 1 ten thousand;
wherein persulfate is present as reactant B10.06% of the mass of (1); styrene in reactant B110% of; lithium p-styrene sulfonate as reactant B110% of;
(4) repeating the steps (1) to (3) (increasing the reaction temperature in the step (2) to 75 ℃ C.) to obtain a high molecular weight (about 50 ten thousand) acrylic polymer C21；
(5) Reacting the reactant C11、C21Mixing the cross-linking agent ethylene glycol, the initiator persulfate and the additive sodium hydroxide, and heating to 85 ℃ to obtain the final polyacrylic acid binder D11；
Mass ratio of reactants C1: c2 ═ 1: 10; ethylene glycol accounts for 0.1% of the total mass of the reactants; persulfate as a total reactant (reactant C1)1、C21Sum) 0.06% of the mass; sodium hydroxide accounts for 0.06% of the total reaction mass; the molecular weight of the binder is about 120 ten thousand;
(6) and washing and drying the polymer slurry to obtain a finished adhesive PAA 1.
Example 1B
The adhesive finished product PAA1 in example 1A is taken, the polyacrylic acid adhesive PAA1 and the negative polyacrylic acid adhesive PAA0 commonly used in the industry are used for negative graphite materials on lithium ion batteries, and new material test experiments are performed by matching lithium simple substances, and the test items are as follows.
TABLE 1 method and apparatus for testing adhesive products
Figure BDA0002675468130000071
Figure BDA0002675468130000081
Remarking: the testing voltage range of the anode material is 3.0V-4.3V; the testing voltage range of the cathode material is 5 mV-2.0V.
PAA1 Ionic conductivity 5X 10 at Room temperature-4S/cm, electron conductivity 8X 10-3S/cm；
The capacity retention rates of the batteries (using PAA1) at 25 ℃ of 1.5C, 2C and 2.5C/0.5C are respectively 89.2%, 85.2% and 81.6%. The capacity retention rate of the battery at 25 ℃ and 1C/1C cycling 200T is 92.5 percent.
The capacity retention rates of the battery (using PAA0) at 25 ℃ and 1.5C and 2C/0.5C are respectively 83.2 percent and 79.8 percent, and the capacity retention rate of the battery at 25 ℃ and 1C/1C cycling 200T is 88.5 percent. PAA0 Ionic conductivity 2X 10 at room temperature-9S/cm, electron conductivity 8X 10-10S/cm。
From the comparison between PAA1 and PAA0, the binder of the present invention has an electronic conductivity that is 7 orders of magnitude higher after application in a battery; similarly, the conductivity is also 5 orders of magnitude higher; the capacity retention rate is obviously higher than that of the battery manufactured by adopting PAA 0; compared with the common adhesive, the adhesive product disclosed by the invention has the advantages that the conductivity, the electronic conductivity, the battery capacity retention rate and the cycle performance are far ahead, and the advantages are obvious.
Example 2
(1) Mixing a binder vinylidene fluoride monomer, an aqueous medium and an initiator AIBN (azodiisobutyronitrile), heating to 45 ℃, adding a group-doped pyrrole monomer and a crosslinking assistant acrylic acid, and slowly introducing acetylene gas to obtain an acrylic polymer B with a small molecular weight2；
Vinylidene fluoride monomer: 1: 4, AIBN accounts for 0.08 percent of the mass of the vinylidene fluoride monomer; the pyrrole monomer accounts for 5% of the mass of the vinylidene fluoride monomer; the mass of the acrylic acid accounts for 0.2 percent of that of the vinylidene fluoride monomer; acetylene accounts for 20 percent of the mass of the vinylidene fluoride monomer;
(2) reacting the reactant B2Mixing aniline monomer containing an electronic conducting group, lithium styrene sulfonate containing an ionic conducting group and an initiator AIBN, and heating to 90 ℃ to obtain the vinylidene fluoride polymer C1 with improved grafting2(molecular weight about 3.0 ten thousand);
wherein AIBN comprises reactant B20.08% of; aniline as reactant B210% of; lithium p-styrene sulfonate as reactant B210% of;
(3) repeating the steps (1) to (2), raising the reaction temperature in the step (1) to 60 DEG CTo obtain vinylidene fluoride polymer C2 with large molecular weight (about 30 ten thousand)2；
(4) Reacting the reactant C12、C22Mixing the cross-linking agent propylene glycol, the initiator persulfate and the additive sodium hydroxide, heating to 85 ℃ to obtain the final polyvinylidene fluoride binder D12；
Mass ratio of reactants C12：C221: 5; propylene glycol as the total reactant (C1)2And C22Sum of mass) 0.3% of the mass; the persulfate accounts for 0.05 percent of the total reaction mass; sodium hydroxide accounts for 0.06% of the total reaction mass; the binder has a molecular weight of about 90 million;
(5) washing and drying the polymer slurry to obtain a finished adhesive product PVDF 2;
(6) the polyvinylidene fluoride binder PVDF2 and the industry common positive polyvinylidene fluoride binder PVDF0 are used for positive NCM (523) materials on lithium ion batteries, and are matched with lithium simple substances to carry out new material test experiments, and the test items are the same as those in example 1;
PVDF2 Ionic conductivity 9X 10 at Room temperature-4S/cm, electronic conductivity 6X 10-3S/cm；
The capacity retention rate of the battery (using PVDF2) at 25 ℃ of 1.5C, 2C and 2.5C/0.5C is 86.3%, 82.5% and 78.6%. The capacity retention rate of the battery is 93.5 percent at 25 ℃ and 200T through 1C/1C circulation.
The capacity retention rates of the batteries (using PVDF0) at 25 ℃ and 1.5C and 2C/0.5C are respectively 83.8 percent and 79.2 percent. The capacity retention rate of the battery at 25 ℃ and 1C/1C cycle of 200T is 90.2%. PVDF0 Ionic conductivity 3X 10 at room temperature-10S/cm, electronic conductivity 6X 10-10S/cm。
Example 3
(1) Adding doping auxiliary agent allyl alcohol into a reaction kettle, heating to 40 ℃, reacting for 4 hours, slowly adding doping group substance diisocyanate (allyl alcohol: diisocyanate is 2.1:1 by mass ratio) for nucleophilic reaction to obtain a reactant A3；
(2) Mixing a binder acrylic acid monomer, an aqueous medium and an initiator persulfate, heating to 50 ℃, adding a crosslinking assistant acrylic acid, and slowly introducing acetylene gas to obtain the acrylic acid-containing aqueous solutionAcrylic Polymer B having a smaller molecular weight3；
Acrylic acid monomer: the aqueous medium is 1:3.3, and the persulfate accounts for 0.05 percent of the mass of the acrylic monomer; reactant A3Accounting for 8 percent of the mass of the acrylic monomer; pyrrole accounts for 0.02 percent of the mass of the acrylic monomer; acetylene accounts for 25 percent of the mass of the acrylic monomer;
(3) reacting the reactant B3Mixing styrene containing electron-conducting groups, lithium acrylate containing ion-conducting groups and persulfate serving as an initiator, and heating to 90 ℃ to obtain the acrylic polymer C1 with improved grafting3(molecular weight about 2 ten thousand);
wherein persulfate is present as reactant B30.05% of the mass of (a); styrene in reactant B310% of; lithium acrylate as reactant B315% of;
(4) repeating the steps (1) to (2) (the reaction temperature in the step (2) is 85 DEG C]To obtain a high molecular weight (about 60 ten thousand) acrylic polymer C23；
(5) Reacting the reactant C13、C23Crosslinking agent C2H2I2Mixing with initiator persulfate, heating to 90 deg.C to obtain final polyacrylic binder D13；
Mass ratio of reactants C13:C23＝1:6；C2H2I2Accounting for 0.2 percent of the total mass of the reactants; the persulfate accounts for 0.06 percent of the total reaction mass; the molecular weight of the binder is about 150 ten thousand;
(6) washing and drying the polymer slurry to obtain a finished product PAA3 of the adhesive;
(7) the polyacrylic acid binder PAA3 and the negative polyacrylic acid binder PAA0 commonly used in the industry are used for negative graphite materials on lithium ion batteries, and new material test experiments are carried out by matching lithium simple substances, and the test items are the same as those in example 1.
PAA3 Ionic conductivity 3X 10 at room temperature-3S/cm, electron conductivity 2X 10-3S/cm。
The capacity retention rate of the battery (using PAA3) at 25 ℃ of 1.5C, 2C and 2.5C/0.5C is 90.6%, 87.5% and 82.9%. The capacity retention rate of the battery at 25 ℃ and 1C/1C cycling 200T is 91.8 percent.
The capacity retention rates of the battery (using PAA0) at 25 ℃ and 1.5C and 2C/0.5C are 83.2 percent and 79.8 percent respectively. The capacity retention rate of the battery with 200T cycles at 25 ℃ and 1C/1C is 88.5 percent. PAA0 Ionic conductivity 2X 10 at room temperature-9S/cm, electron conductivity 8X 10-10S/cm。
As seen from the comparison between the binder products in the above 3 examples and the conventional binder products, the binder of the present invention has high conductivity and high electronic conductivity after being applied to a battery, and maintains the capacity retention rate of the battery at a high level.

Claims (10)

1. The preparation method of the binder capable of improving the rate capability of the battery comprises the following steps:
(1) mixing a binder monomer, a medium and a first free radical initiator, heating to 40-45 ℃, adding a substance containing a doping group and a crosslinking auxiliary agent, and slowly introducing acetylene gas to obtain a reactant B;
(2) mixing the reactant B, the substance containing the electronic conducting group, the substance containing the ionic conducting group and a second free radical initiator, and heating to 60-100 ℃ to obtain a polymer C1, wherein the molecular weight of C1 is 1-10 w;
(3) repeating the steps (1) to (2), and increasing the heating reaction temperature in the step (1) to 60-85 ℃ to obtain a second polymer C2, wherein the molecular weight of C2 is 30-80 w;
(4) and mixing the reactant C1, the reactant C2, the cross-linking agent, the third radical initiator and the additive alkali, and heating to 60-100 ℃ to obtain the binder.
2. The method for preparing the binder capable of improving the rate capability of the battery as claimed in claim 1, wherein: (1) the binder monomer is selected from any one of acrylic acid monomers and vinylidene fluoride monomers; the medium is water; the first free radical initiator is selected from any one of persulfate, azobisisobutyronitrile and acyl peroxide; the substance containing the doping group is selected from any one of diisocyanate and pyrrole monomers;
the mass ratio of the binder monomer to the medium is 1: 2-1: 5; the first free radical initiator accounts for 0.05-0.1% of the mass of the binder monomer;
the crosslinking auxiliary agent is acrylic acid; the crosslinking auxiliary agent accounts for 0-0.3% of the mass of the binder monomer;
acetylene accounts for 10-30% of the mass of the binder monomer.
3. The method for preparing the binder capable of improving the rate capability of the battery as claimed in claim 1, wherein: (2) in the method, the substance containing the electronic conducting group is any one of styrene and aniline monomers;
the substance containing the ion conducting group is any one of lithium styrene sulfonate and lithium acrylate;
the substance containing the electron conductor group accounts for 5-15% of the reactant B; the substance containing the ion conductor group accounts for 10-20% of the reactant B;
the second free radical initiator is selected from any one of persulfate, azobisisobutyronitrile and acyl peroxide; the second radical initiator accounts for 0.05-0.1% of the mass of the reactant B.
4. The method for preparing the binder capable of improving the rate capability of the battery as claimed in claim 1, wherein: (4) wherein the crosslinking agent is selected from alcohols and CH2I2Any one of (a); the cross-linking agent accounts for 0.1-0.3% of the sum of the mass of the reactant C1 and the mass of the reactant C2; the additive is sodium hydroxide; the additive accounts for 0-0.1% of the sum of the mass of the reactant C1 and the mass of the reactant C2; the mass ratio of the reactant C1 to the reactant C2 is 1: 4-12;
the third free radical initiator is selected from any one of persulfate, azobisisobutyronitrile and acyl peroxide; the third free radical initiator accounts for 0.05-0.1% of the sum of the mass of the reactant C1 and the mass of the reactant C2.
5. The preparation method of the binder capable of improving the rate capability of the battery comprises the following steps:
(1) adding a doping auxiliary agent into a reaction kettle, heating to 40-45 ℃, and then slowly adding a substance containing a doping group to perform nucleophilic reaction to obtain a reactant A;
(2) mixing a binder monomer, a medium and a first free radical initiator, and heating to 40-50 ℃; then adding the reactant A and the crosslinking assistant, and slowly introducing acetylene gas to obtain a reactant B;
(3) mixing the reactant B, the substance containing the electronic conducting group, the substance containing the ionic conducting group and a second free radical initiator, and heating to 60-100 ℃ to obtain a polymer C1, wherein the molecular weight of C1 is 1-10 w;
(4) repeating the steps (1) - (3), and increasing the reaction temperature in the step (2) to 60-85 ℃;
(5) and mixing the reactant C1, the reactant C2, the cross-linking agent, the third radical initiator and the additive, and heating to 60-100 ℃ to obtain the binder.
6. The method for preparing the binder capable of improving the rate capability of a battery according to claim 5, wherein in the step (1), the doping auxiliary agent is an enol substance; the mol ratio of the doping auxiliary agent to the doping group-containing substance is 2: 1-2.1: 1;
the substance containing the doping group is selected from any one of diisocyanate and pyrrole monomers.
7. The method for preparing the binder capable of improving the rate capability of the battery according to claim 5, wherein in the step (2), the binder monomer is selected from any one of acrylic acid monomers and vinylidene fluoride monomers; the medium is water; the first free radical initiator is selected from any one of persulfate, azobisisobutyronitrile and acyl peroxide;
the mass ratio of the binder monomer to the medium is 1: 2-1: 3; the first free radical initiator accounts for 0.05-0.1% of the mass of the binder monomer;
the crosslinking auxiliary agent is acrylic acid; the crosslinking auxiliary agent accounts for 0-0.3% of the mass of the binder monomer;
the reactant A accounts for 5-10% of the mass of the binder monomer;
acetylene accounts for 10-30% of the mass of the binder monomer.
8. The battery of claim 5 capable of increasing the battery powerThe preparation method of the adhesive with rate performance is characterized in that in the step (5), the cross-linking agent is selected from alcohols and CH2I2Any one of (a); the cross-linking agent accounts for 0.1-0.3% of the sum of the mass of the reactant C1 and the mass of the reactant C2;
the mass ratio of the reactant C1 to the reactant C2 is 1: 4-12;
the third free radical initiator is selected from any one of persulfate, azobisisobutyronitrile and acyl peroxide; the third free radical initiator accounts for 0.05-0.1% of the sum of the mass of the reactant C1 and the mass of the reactant C2;
the additive is alkali; the additive accounts for 0-0.1% of the sum of the mass of the reactant C1 and the mass of the reactant C2.
9. The method for preparing the binder capable of improving the rate performance of the battery as claimed in any one of claims 1 and 5, further comprising washing and drying the obtained binder to obtain a finished binder.
10. The application of the binder of the lithium ion battery of any one of claims 1 to 8 in the fields of coating of a positive electrode, a negative electrode and a separator of the battery; and mixing the binder with the conventional binder and applying the mixture to the field of coating of the positive electrode, the negative electrode and the diaphragm of the battery.
CN202010946511.8A 2020-09-10 2020-09-10 Preparation method and application of adhesive capable of improving battery rate performance Active CN112029452B (en)

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CN101210158A (en) * 2006-12-26 2008-07-02 中南大学 Electric bonding for battery or capacitor and composition containing the same used for electrode
CN104356979A (en) * 2014-10-28 2015-02-18 深圳市贝特瑞新能源材料股份有限公司 Polyacrylate water-based adhesive for electrode materials of lithium ion battery, preparation method of adhesive and electrode plates of lithium ion battery
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