CN115295802A - Adhesive, preparation method thereof and application thereof in lithium ion battery - Google Patents

Adhesive, preparation method thereof and application thereof in lithium ion battery Download PDF

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Publication number
CN115295802A
CN115295802A CN202210791711.XA CN202210791711A CN115295802A CN 115295802 A CN115295802 A CN 115295802A CN 202210791711 A CN202210791711 A CN 202210791711A CN 115295802 A CN115295802 A CN 115295802A
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adhesive
inorganic particles
electrode material
thickeners
conductive inorganic
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罗震
许莹
龚翠然
郑杨清
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Fujian Institute of Research on the Structure of Matter of CAS
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Fujian Institute of Research on the Structure of Matter of CAS
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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
    • 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
    • H01M4/622—Binders being polymers
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • 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
    • H01M4/624—Electric conductive fillers
    • 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)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

The invention provides an adhesive, a preparation method thereof and application thereof in a lithium ion battery. The adhesive comprises a polymer with a side chain containing functional groups, inorganic particles and a solvent; the mass ratio of the polymer containing functional groups on the side chains to the inorganic particles is 10: 2-2: 10; the inorganic particles include conductive inorganic particles and ion conductive inorganic particles; the mass ratio of the conductive inorganic particles to the ion-conductive inorganic particles is 10:1 to 1:10. the invention has the advantages that: the problem of volume expansion of the silicon-based negative electrode is inhibited by utilizing the thermal crosslinking effect among the adhesive components, and the cycling stability of the silicon and tin negative electrodes is improved; and secondly, the ion conducting component of the adhesive has the function of transmitting ions, which is beneficial to improving the rate capability of the lithium battery.

Description

Adhesive, preparation method thereof and application thereof in lithium ion battery
Technical Field
The application relates to an adhesive, a preparation method thereof and application thereof in a lithium ion battery, belonging to the technical field of new polymer materials.
Background
The lithium ion battery has excellent performances of high working voltage, large specific energy, long cycle life and the like, and is widely applied to the fields of mobile equipment, electric automobiles, aerospace, aviation and the like. The lithium ion battery mainly comprises a current collector, an active material, an adhesive, a conductive agent, a diaphragm and the like. The nature of the active material determines the type and nature of the adhesive used. Currently, polyvinylidene fluoride (PVDF) is used as an adhesive between a positive electrode material and a current collector in most lithium battery manufacturing processes, and a styrene butadiene rubber emulsion/carboxymethyl cellulose composite (SBR/CMC) is mainly used for bonding between a negative electrode material and the current collector.
The positive electrode binder is mainly PVDF, and PVDF has an inherent reaction which can form defluorination reaction with hydrogen under strong alkalinity, so that PVDF jelly gel is produced in the positive electrode slurry mixing process. Therefore, the electrode material slurry mixing process needs to strictly control the environmental humidity. And fluorine contamination and fluorine recovery are a great problem to be faced in the subsequent battery material recovery process.
SBR/CMC and acrylonitrile-acrylate copolymer adhesives are commonly used for the adhesion of graphite cathode materials. The volume change of the graphite cathode in the charging and discharging process is small, and the bonding strength of SBR and acrylic ester is enough to inhibit the graphite powder from falling off or the powder from separating from the current collector. However, for silicon, tin and other negative electrode materials with high specific capacity, due to the huge volume change of the negative electrode materials in the charging and discharging processes, the pulverization of the silicon and tin electrode materials is difficult to control by the common SBR and acrylate adhesives, and finally the cycle performance is linearly reduced.
PVDF and acrylonitrile-acrylate copolymer are the preferred binders for electrode materials of ion batteries, mainly because the C-F bond and the-CN bond in the polymer structure have good ion transport effect and electrochemical stability. Most of the common polymers have strong adhesive property, but the low ionic conductivity of the polymers limits the application of the polymers in the adhesion of lithium ion battery materials.
Research shows that Lewis acid centers on the surfaces of the nanoparticles can interact with anions of lithium salt, so that polar atoms in the polymer and Li are weakened + Promotes dissociation of lithium salt, thereby releasing free Li + To improve the ion conduction efficiency of lithium ions. Therefore, the nanoparticles are mainly used for preparing a composite polymer electrolyte of a lithium ion battery. There has also been a small number of studies using nanoparticles in the manufacture of lithium ion Chi Nianjie agentsBut all require the addition of a coupling component to assist crosslinking. Samsung SDI corporation (chinese patent CN 103242595B) reported that a composition consisting of inorganic particles, a binder prepolymer and an organic-inorganic coupling agent was used for bonding silicon, tin negative electrodes. The silicon and tin negative electrodes are anchored on the inorganic particles and the adhesive through the coupling agent, so that the volume expansion of the silicon and tin negative electrodes can be well inhibited.
Disclosure of Invention
Aiming at the problems of volume expansion of the negative electrode, low ionic conductivity of common polymers and the like, the invention provides an adhesive composition applicable to the positive electrode and the negative electrode of a lithium ion battery. The adhesive composition can effectively limit the volume expansion of the tin cathode through simple heat treatment without adding a coupling agent; secondly, the adhesive composition makes up the problem of low ionic conductivity of the conventional polymer by utilizing the ion transmission function of the nano particles, widens the selection range of the polymer of the adhesive and provides a technical scheme for non-fluorination of the lithium ion battery adhesive; more recently, the adhesive composition is beneficial to the transmission of lithium ions, and can effectively improve the rate capability of the lithium ion battery.
According to one aspect of the present application, there is provided an adhesive comprising a polymer, conductive inorganic particles, and ion-conductive inorganic particles;
the polymer is obtained by polymerizing a monomer containing a functional group on a side chain;
the functional group is selected from at least one of hydroxyl, carboxyl, amino, isocyanate group, epoxy group or ester group;
optionally, the polymer is selected from at least one of polyurethane, polyvinyl alcohol, polyacrylic acid, polyvinyl acetate, polyacrylamide, carboxymethyl cellulose, hydroxypropyl methyl cellulose, hydroxypropyl cellulose, hydroxyethyl cellulose, or hydroxyethyl cellulose salts;
in the present application, the inorganic particles are collectively referred to as conductive inorganic particles and ion conductive inorganic particles, unless otherwise specified. It has been found that alkali metal ions or alkaline earth metal ions are believed to diffuse along the nanoparticle interface region, i.e. some nanoparticles may haveThe transmission function of lithium ions or sodium ions can improve the ion conduction efficiency. The transmission and conduction mechanism of lithium ions at the interface of the nanoparticles is not consistent, and one of the ideas is the Lewis acid-base theory: the Lewis acid center on the surface of the nanoparticle can interact with the anion of the lithium salt, so that the polar atom and Li in the polymer are weakened + Promotes dissociation of lithium salt, thereby releasing free Li + To improve the ion conduction efficiency of lithium ions. And the higher the high specific surface area of the nanoparticles, the better the ion conductivity. In the present specification, these particles having a lithium ion transport function are collectively referred to as "ion-conductive inorganic particles".
The ratio of the mass of the polymer to the sum of the masses of the conductive inorganic particles and the ion-conductive inorganic particles is 10: 2-2: 10;
preferably, the ratio of the mass of the polymer to the sum of the masses of the conductive inorganic particles and the ion-conductive inorganic particles is 10:3 to 3:10;
the mass ratio of the conductive inorganic particles to the ion-conductive inorganic particles is 10:1 to 1:10.
the conductive inorganic particles are at least one selected from metal particles, graphite, acetylene black or carbon nanotubes;
the metal particles are selected from at least one of Be, al, ti, V, fe, co, zn, ge, zr, ag, sn, au or Mn;
the ion-conducting inorganic particles are selected from at least one of metal oxide, non-metal oxide or metal fluoride;
the metal oxide is selected from at least one of Be, al, ti, V, fe, co, zn, ge, zr, ag, sn, au or Mn oxides;
the non-metal oxide is selected from silicon dioxide;
the metal fluoride is at least one of Be, al, ti, V, fe, co, zn, ge, zr, ag, sn, au or Mn fluoride.
According to another aspect of the present application, a method for preparing the above adhesive is provided, which at least comprises the following steps:
mixing raw materials containing a polymer, conductive inorganic particles, ion-conducting inorganic particles and a solvent to obtain the adhesive.
The mixing comprises the following steps:
dissolving conductive inorganic particles and ion-conductive inorganic particles in a solvent to obtain a mixture I;
dissolving the polymer in a solvent to obtain a mixture II;
mixing the mixture I and the mixture II;
the mixing temperature is 25-100 ℃.
The solvent is at least one of water, N-methyl pyrrolidone, dimethylformamide, tetrahydrofuran, acetone, butanone, ethanol, isopropanol or acetonitrile;
the mass of the solvent is as follows: the sum of the masses of the polymer, the conductive inorganic particles and the ion-conducting inorganic particles is = 20;
optionally, the raw materials also contain a wetting agent;
the wetting agent is selected from at least one of alkyl sulfate, sulfonate, fatty acid ester sulfate, carboxylic acid soap, phosphate ester, polyoxyethylene alkylphenol ether, polyoxyethylene fatty alcohol ether, polyoxyethylene polyoxypropylene block copolymer or silanol nonionic surfactant;
the content of the wetting agent is 0 to 5.0 weight percent of the adhesive;
optionally, the raw materials also contain a thickening agent;
the thickening agent is selected from a low-molecular thickening agent and/or a high-molecular thickening agent;
the low molecular weight thickener is at least one of inorganic salt thickeners, fatty alcohol, fatty acid thickeners, alkanolamide thickeners, ether thickeners, ester thickeners or amine oxide thickeners;
the macromolecular thickener is at least one of cellulose thickener, polyacrylic acid thickener, polyurethane thickener, natural gum thickener or polyoxyethylene thickener.
The content of the thickening agent is 0-5.0 wt% of the adhesive.
According to another aspect of the present application, a positive electrode material for a lithium ion battery is provided, wherein the positive electrode material contains the above-mentioned binder or the binder obtained by the above-mentioned preparation method.
According to another aspect of the present application, there is provided a negative electrode material for a lithium ion battery, the negative electrode material containing the above binder or the binder obtained by the above preparation method.
According to another aspect of the present application, a lithium ion battery is provided, and the positive electrode of the lithium ion battery adopts the positive electrode material described above;
or/and;
the cathode of the lithium ion battery adopts the cathode material.
The adhesive provided by the invention can effectively neutralize alkaline substances generated by the action of the anode material and water, and is also suitable for silicon and tin cathodes.
In order to achieve the above object, the adhesive of the present invention mainly comprises: a polymer having a functional group in a side chain (i.e., "polymer in claims"), a conductive inorganic particle (i.e., "conductive inorganic particle in claims"), and an ion conductive inorganic particle (i.e., "ion conductive inorganic particle in claims"). The ion-conducting particles have an ion-conducting function by an interface, and the conductive inorganic particles have an electron-conducting function. When the content of the inorganic particles in the adhesive reaches the level of forming a conductive network and an ion interface transmission network, the transmission efficiency of ions and electrons of the electrode can be improved to the maximum extent, so that the rate capability of the lithium ion battery is improved.
When the adhesive is used as an adhesive of silicon and tin negative electrodes, hydroxyl on the surface of ion-conducting inorganic particles reacts with functional groups on a polymer side chain at high temperature to form a cross-linked structure, so that the volume change of the silicon and tin negative electrodes is controlled.
When the adhesive is used, the adhesive needs to be heated and crosslinked, and the thermal crosslinking temperature is 80-200 ℃, preferably 100-150 ℃. The purpose is that when the adhesive is used for bonding electrode materials of lithium ion batteries, a polymer containing functional groups on side chains in the adhesive and ion-conducting inorganic particles generate a crosslinking reaction.
In the adhesive, the conductive inorganic particles have a particle size of 1nm to 2000nm, optionally 1nm to 200nm.
In the adhesive, the particle size of the ion-conducting inorganic particles is 10 nm-20 μm, and optionally, the particle size is 10 nm-2 μm.
The viscosity of the adhesive is more than or equal to 1000 mPa.s at 25 ℃, and the inorganic particles are not easy to settle.
The preparation process of the adhesive comprises the following steps:
A. wetting of inorganic particles (including conductive inorganic particles and ion-conductive inorganic particles)
Soaking conductive inorganic particles and ion conductive inorganic particles in a certain amount of solvent, stirring for 30min, standing for 24h, and adding wetting agent if necessary;
B. dissolution of polymers containing functional groups in the side chains
And (3) dissolving the polymer by using the solvent in the step A, if the solvent is heated to promote dissolution, cooling the solvent to perform the next operation.
C. Preparation of polymer/inorganic particle adhesive containing functional group on side chain
And dispersing the dissolved polymer and the wetted particles at a high speed, and optionally adding a thixotropic agent to adjust the viscosity to obtain the adhesive.
The adhesive can be used for preparing electrodes of lithium ion batteries and button batteries thereof, and the preparation method comprises the following steps:
1) Preparing electrode slurry: mixing an electrode material, an adhesive and a conductive agent, and performing ball milling for 2 hours;
2) Coating: uniformly coating the electrode slurry on an aluminum foil (copper foil), and carrying out vacuum drying for 12 hours at the temperature of 80-200 ℃;
3) Punching the pole piece: rolling the pole piece after vacuum drying, and punching to obtain a circular electrode piece with the diameter of 16 mm;
4) Preparing a button half cell: after vacuum drying at 80 ℃ for 12h, transferring the circular electrode slice to a dry argon glove box, matching with lithium metal to form a button half cell, wherein the electrolyte is 1mol/L lithium hexafluorophosphate (the solvent is Ethylene Carbonate (EC): dimethyl carbonate (DMC): methyl ethyl carbonate (EMC) =1 (V)); adding 3wt% of functional additive tris (trimethylsilyl) phosphate or fluoroethylene carbonate (FEC) into the electrolyte; the diaphragm is a polypropylene diaphragm.
The electrode material can be a positive electrode material or a negative electrode material. The positive electrode material comprises positive electrode materials such as lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, manganese nickel cobalt composite oxide and the like. Specific examples of such a positive electrode material include LiCoO 2 ，LiNiO 2 ，LiMnO 2 And LiMn 2 O 4 ， LiMn x Ni y Co 1-x-y O 2 ，LiVO 2 、Li x V 2 O 4 、Li x V 3 O 8 ，LiFeO 2 ，LiFePO 4 . Wherein x ranges from 0.1 to 2; y ranges from 0.1 to 2;
the negative electrode material can be artificial graphite, natural graphite, active carbon, silicon-based negative electrode material and tin-based negative electrode material.
In the coating operation in the preparation process of the lithium ion battery electrode, as is known, an aluminum foil is used as a current collector for the positive electrode, and a copper foil is used as a current collector for the negative electrode.
In the preparation process of the lithium ion battery electrode, the coating operation is carried out, and the electrode needs to be subjected to vacuum heating treatment at the temperature of 80-200 ℃. The electrode is heated at 80 to 200 ℃ in order to promote the thermal crosslinking reaction between the polymer having a functional group on a side chain and the inorganic particles in the composition.
The conductive agent is selected from conductive carbon black, carbon nano tubes or graphene;
the dosage ratio of the electrode material to the conductive agent is 65-99;
preferably, the ball milling time is 1-5 h;
preferably, the drying temperature is 80-200 ℃;
preferably, the drying time is 4-24 h;
preferably, the drying is performed under vacuum conditions;
preferably, the vacuum degree of the drying is-0.02 to-0.1 MPa.
The invention has the advantages that the problem of volume expansion of the silicon-based negative electrode is inhibited by utilizing the thermal crosslinking effect among the adhesive components, and the cycling stability of the silicon and tin negative electrodes is improved; furthermore, the problem of low ionic conductivity of the conventional polymer is solved by utilizing the ion transmission function of the nanoparticles, and a feasible technical scheme is provided for the non-fluorination of the lithium ion adhesive.
Drawings
FIG. 1: adhesive D-Differential Scanning Calorimetry (DSC) spectrum.
FIG. 2: the adhesive is applied to a positive electrode material (NMC 622), and the prepared cycle rate curve of the lithium ion battery is obtained.
FIG. 3: the adhesive is applied to a positive electrode material (LFP), and the prepared cycle rate curve of the lithium ion battery is obtained.
FIG. 4: the adhesive is applied to the negative electrode material (S600), and the prepared cycle curve of the lithium ion battery is obtained.
Detailed Description
The present application will be described in detail with reference to examples, but the present application is not limited to these examples. The starting materials and reagents in the examples of the present application were all purchased commercially.
Nano silicon oxide: hydrophilic, specific surface area 420m 2 (ii)/g, shanghai Michelin Biochemical technology, inc.
Nano alumina: hydrophilic, particle size 30nm, shanghai Michelin Biochemical technology Ltd.
Conductive carbon black: super-P conductive agent, shenzhen Wei Di Fei New energy science and technology Limited.
Polyvinyl alcohol, alcoholysis degree 80-99%, shanghai Mielin Biochemical technology Co., ltd.
NMC622：LiNi 0.6 Mn 0.2 Co 0.2 O 2 Hu nan fir new materials Co., ltd.
LFP: lithium iron phosphate, a new material from Hu nan fir, inc.
Silicon carbon negative electrode: s600, shenzhen, beibei New energy materials GmbH.
The analysis method in the examples of the present application is as follows:
the adhesive was tested for thermal crosslinking temperature using differential scanning calorimetry (TA Instruments DSC Q200).
Electrochemical performance of battery
The first measurement of the specific charge capacity, charge capacity and discharge capacity was carried out using a blue cell test system (model: LAND-CT2001A, available from Wuhan blue electronics Co., ltd.).
And (3) evaluating the circulation and rate performance of the button half cell:
standing the assembled button half cell for 8h at 25 ℃, firstly charging to 4.2V at a multiplying power of 0.1C), standing for 3min, then discharging to 2.8V at a multiplying power of 0.1C, standing for 3min, and then charging to 4.2V at a multiplying power of 0.1C, wherein the charge and discharge once again count for 1 cycle period; according to the above rule, completing the multiplying factor test by cycling for 5 times at 0.2C, 0.5C and 1.0C respectively, finally charging to 4.2V at 0.2C multiplying factor, standing for 3min, discharging to 2.8V at 0.5C multiplying factor, standing for 3min, and cycling to 50 times.
The following electrochemical properties of the lithium battery were obtained, respectively:
0.1C, 0.2C, 0.5C and 1.0C.
100-cycle retention rate = first-charge specific capacity/100-th-cycle specific charge capacity × 100%;
200 cycle retention rate = first charge specific capacity/200 th cycle charge specific capacity × 100%;
n hundred cycles retention = first charge specific capacity/nth hundred cycles charge specific capacity × 100%.
Preparation example 1
1. Wetting of inorganic particles
7.5g of ion conductive particles (nano silicon oxide) and 0.75g of conductive inorganic particles (acetylene black) were immersed in 10g N-methylpyrrolidone (NMP), stirred for 30min and then allowed to stand for 24h.
2. Dissolution of polymers with functional groups in the side chains
10.0g of polyvinyl alcohol was added to 50g N-methylpyrrolidone, dissolved at 65 ℃ and then cooled to 25 ℃.
3. Preparation of Adhesives
The mixtures prepared in step 1 and step 2 were dispersed at 3000rpm at high speed and 50g of NMP were added to adjust the viscosity to 50000mPas. Adhesive a (polymer of functional groups on the side chains: sum of masses of ion-conductive particles and conductive inorganic particles = 10.
Preparation example 2
Similarly to preparation example 1, the amount of ion-conducting particles (nano-silica) in preparation example 1 was reduced to 5.0g, and the amount of conductive inorganic particles (acetylene black) was reduced to 0.5g. The viscosity was adjusted to 50000mPas by adding 50g of NMP. Adhesive B (polymer of functional group on side chain: sum of mass of ion-conductive particle and conductive inorganic particle = 10.
Preparation example 3
Similarly to preparation example 1, the amount of ion-conducting particles (nano-silica) in preparation example 1 was reduced to 2.5g, and the amount of conductive inorganic particles (acetylene black) was reduced to 0.25g. The viscosity was adjusted to 50000mPas by adding 50 g. Adhesive C (polymer of functional group on side chain: sum of mass of ion-conductive particle and conductive inorganic particle = 10.
Preparation example 4
Similar to the procedure of production example 1 except that NMP was replaced with water as a solvent, an adhesive D (mass of the polymer having a functional group on the side chain: the sum of the masses of the ion-conductive particles and the conductive inorganic particles = 10. The viscosity of the adhesive was 60000 mPas.
Preparation example 5
Similar to the procedure of preparation example 2 except that the ion-conducting particles (nano-silica) were replaced with nano-alumina, an adhesive E (mass of polymer having functional groups on the side chain: the sum of the mass of ion-conducting particles and conductive inorganic particles = 10.25) was obtained. The viscosity of the adhesive was 60000 mPas.
Example 1 adhesive a preparation of lithium ion button cell (NMC 622 electrode)
1) Preparing electrode slurry: 3.8072g NMC622, 0.7065g adhesive A
0.1071g of conductive carbon black (Super-P) and 2.6g of NMP, ball milling for 2 hours;
2) Coating: uniformly coating the electrode slurry on an aluminum foil, and performing vacuum drying at 100 ℃ for 12 hours;
3) Punching a pole piece: rolling the vacuum-dried pole piece, and punching to obtain a circular electrode piece with the diameter of 16 mm;
4) Preparing a button half cell: after vacuum drying at 80 ℃ for 12h, transferring the circular electrode slice to a dry argon glove box, matching with lithium metal to form a button half cell, wherein the electrolyte is 1mol/L lithium hexafluorophosphate (the solvent is Ethylene Carbonate (EC): dimethyl carbonate (DMC): methyl ethyl carbonate (EMC) =1 (V)); adding 3wt% of functional additive tri (trimethylsilyl) phosphate into the electrolyte; the diaphragm is a polypropylene diaphragm.
And the lithium ion battery prepared in example 1 was tested for cycle and rate performance as shown in table 1 and fig. 2.
Example 2 preparation of adhesive B lithium ion button cell (NMC 622 electrode)
A lithium ion rechargeable battery was fabricated using the composition B of preparation example 2 as an adhesive, and the lithium battery fabricated in example 2 was tested for cycle and rate performance as shown in table 1 and fig. 2, similarly to example 1.
Example 3 preparation of adhesive C lithium ion button cell (NMC 622 electrode)
A lithium ion rechargeable battery was fabricated using the composition C of preparation example 3 as an adhesive, and the lithium battery fabricated in example 3 was tested for cycle and rate performance as shown in table 1 and fig. 2, similarly to example 1.
EXAMPLE 4 preparation of lithium ion button cell (LFP electrode) with adhesive D
Similar to example 1, except that: lithium iron phosphate (LFP) is used as an electrode material, water is used as a solvent, the composition D in preparation example 4 is used as an adhesive to prepare a lithium ion rechargeable battery, and the cycle and rate performance of the lithium battery prepared in example 4 are tested as shown in table 1 and fig. 3.
Example 5 preparation of lithium ion button cell (silicon carbon electrode) with adhesive D
1) Preparing electrode slurry: mixing 1.6040 silicon-carbon cathode, 1.3436 adhesive D and 0.2021g of conductive agent, and ball-milling for 2 hours;
2) Coating: uniformly coating the electrode slurry on a copper foil, and carrying out vacuum treatment for 12 hours at 130 ℃;
3) Punching a pole piece: rolling the vacuum-dried pole piece, and punching to obtain a circular electrode piece with the diameter of 16 mm;
4) Preparing a button half cell: after vacuum drying at 80 ℃ for 12h, transferring the circular electrode slice to a dry argon glove box, matching with lithium metal to form a button half cell, wherein the electrolyte is 1mol/L lithium hexafluorophosphate (the solvent is Ethylene Carbonate (EC): dimethyl carbonate (DMC): methyl ethyl carbonate (EMC) =1 (V)); adding 3wt% of fluoroethylene carbonate (FEC) serving as a functional additive into the electrolyte; the diaphragm is a polypropylene diaphragm.
And the lithium ion battery prepared in example 5 was tested for cycle performance as shown in fig. 4.
EXAMPLE 6 preparation of lithium ion Battery (silicon carbon electrode) with adhesive E
A lithium ion battery was prepared using composition E of preparation example 5 as an adhesive, and the lithium battery prepared in example 6 was tested for cycle performance as shown in fig. 4, except that composition E of preparation example 5 was used as an adhesive. COMPARATIVE EXAMPLE 1 preparation of lithium ion Battery from polyvinyl alcohol (NMC 622 electrode)
The lithium battery prepared in comparative example 1 was tested for cycle and rate performance similar to example 1, except that polyvinyl alcohol was used as the adhesive, as shown in table 1 and fig. 2.
COMPARATIVE EXAMPLE 2 preparation of lithium ion Battery (LFP electrode) from polyvinyl alcohol
The lithium battery prepared in comparative example 2 was tested for cycle and rate performance similar to example 4, except that polyvinyl alcohol was used as the adhesive, as shown in table 1 and fig. 3.
COMPARATIVE EXAMPLE 3 preparation of lithium ion Battery (silicon carbon electrode) from polyvinyl alcohol
The lithium battery prepared in comparative example 3 was tested for cycle performance similar to example 5, except that polyvinyl alcohol was used as an adhesive, as shown in fig. 4.
Table 1 electrochemical performance table of adhesive used for preparing lithium ion battery with different anode materials
Figure BDA0003734099840000121
FIG. 1 illustrates:
as seen from the Differential Scanning Calorimetry (DSC) spectrum (FIG. 1) of adhesive D, adhesive-D (PVA + SiO) of preparation example 4 is different from PVA 2 ) Significant endothermic peaks occur in a large temperature interval between 80 ℃ and 200 ℃. The reason for this may be the hydroxyl group on the side chain of PVA and SiO 2 The hydroxyl groups on the surface are subjected to dehydration crosslinking reaction.
Table 1, accompanying fig. 2, accompanying fig. 3 illustrate:
from the rate data of the lithium particle batteries in examples 1-4 and comparative examples 1-2, it can be seen that when pure PVA is used as the adhesive (comparative examples 1 and 2), the specific capacity of the prepared electrode with high rate is significantly lower than that of the adhesive containing inorganic particles (examples 1-4) due to the poor conductivity and ion conductivity of PVA. The reason why the rate performance of the rechargeable battery is remarkably improved along with the increase of the sum of the mass of the ionic particles and the conductive inorganic particles in the adhesive is that the interface of the ion-conducting particles has the function of transmitting lithium ions, and a more perfect ion-conducting network is formed along with the increase of the content of the ion-conducting particles (in examples 1 to 3, adhesives A, B and C are respectively used, and the mass ratio of the sum of the mass of the ion-conducting particles and the mass of the conductive inorganic particles to the mass of the polymer is 8.25,5.5 and 2.75 respectively). The lithium ion battery prepared by the adhesive with higher ion conducting particle content shows more excellent rate capability.
FIG. 4 illustrates:
as seen from the cycle data of the lithium ion batteries of examples 5 and 6 and comparative example 3, the cycle retention rate of the silicon-carbon anode in example 5 is greater than 95% after 100 cycles; after 500 cycles, the lithium ion batteries prepared in examples 5 and 6 still maintain higher specific capacity (about 400 mAh/g, which is higher than the theoretical specific capacity 372mAh/g of graphite). The adhesive after thermal crosslinking can effectively inhibit the volume expansion of the silicon-based material. At the same time, the specific capacity without the ion-conducting particles (comparative example 3, 206 mAh/g) was also smaller than the specific capacity with the ion-conducting particles (example 5, 734 mAh/g) at the same rate (0.2C). Further proves the interface ion transmission function of the ion-conducting particles.
Although the present application has been described with reference to a few embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the application as defined by the appended claims.

Claims (10)

1. An adhesive is characterized in that the adhesive is prepared by mixing a mixture of a rubber and a resin,
the adhesive comprises a polymer with a side chain containing functional groups, inorganic particles and a solvent;
the mass ratio of the polymer containing the functional group on the side chain to the inorganic particles is 10: 2-2: 10;
the inorganic particles include conductive inorganic particles and ion conductive inorganic particles;
the mass ratio of the conductive inorganic particles to the ion-conductive inorganic particles is 10:1 to 1:10.
2. the adhesive of claim 1,
the functional group is selected from at least one of hydroxyl, carboxyl, amino, isocyanate group, epoxy group or ester group;
preferably, the polymer is selected from at least one of polyurethane, polyvinyl alcohol, polyacrylic acid, polyvinyl acetate, polyacrylamide, carboxymethyl cellulose, hydroxypropyl methyl cellulose, hydroxypropyl cellulose, hydroxyethyl cellulose, or hydroxyethyl cellulose salt;
preferably, the conductive inorganic particles are selected from at least one of metal particles, graphite, acetylene black, or carbon nanotubes;
preferably, the metal particles are selected from at least one of Be, al, ti, V, fe, co, zn, ge, zr, ag, sn, au or Mn;
preferably, the ion-conducting inorganic particles are selected from at least one of metal oxides, non-metal oxides or metal fluorides;
preferably, the metal oxide is selected from at least one of oxides of Be, al, ti, V, fe, co, zn, ge, zr, ag, sn, au or Mn;
preferably, the non-metal oxide is selected from silica;
preferably, the metal fluoride is selected from at least one of fluorides of Be, al, ti, V, fe, co, zn, ge, zr, ag, sn, au or Mn.
3. The adhesive of claim 1,
the adhesive also contains a wetting agent;
preferably, the wetting agent is selected from at least one of alkyl sulfate, sulfonate, fatty acid ester sulfate, carboxylic acid soap, phosphate ester, polyoxyethylene alkylphenol ether, polyoxyethylene fatty alcohol ether, polyoxyethylene polyoxypropylene block copolymer or silanol nonionic surfactant;
preferably, the content of the wetting agent is 0 to 5.0wt% of the adhesive;
preferably, the adhesive also contains a thickening agent;
preferably, the thickener is selected from a low molecular thickener and/or a high molecular thickener;
preferably, the low molecular weight thickener is at least one selected from inorganic salt thickeners, fatty alcohol thickeners, fatty acid thickeners, alkanolamide thickeners, ether thickeners, ester thickeners or amine oxide thickeners;
preferably, the polymer thickener is at least one selected from cellulose thickeners, polyacrylic acid thickeners, polyurethane thickeners, natural gum thickeners and polyoxyethylene thickeners;
the content of the thickening agent is 0-5.0 wt% of the adhesive.
4. A method for preparing the adhesive according to any one of claims 1 to 3,
at least comprises the following steps:
mixing raw materials containing a polymer, conductive inorganic particles, ion-conducting inorganic particles and a solvent to obtain the adhesive.
5. The production method according to claim 4,
the mixing comprises the following steps:
dissolving conductive inorganic particles and ion-conductive inorganic particles in a solvent to obtain a mixture I;
dissolving a polymer in a solvent to obtain a mixture II;
mixing the mixture I and the mixture II;
the mixing temperature is 25-100 ℃.
6. The production method according to claim 4,
the solvent is at least one of water, N-methyl pyrrolidone, dimethylformamide, tetrahydrofuran, acetone, butanone, ethanol, isopropanol or acetonitrile;
the mass of the solvent is as follows: the sum of the masses of the polymer, the conductive inorganic particles and the ion-conductive inorganic particles is from 1 to 1:1;
optionally, the raw materials also contain a wetting agent;
optionally, the raw material further comprises a thickening agent.
7. An electrode material for a lithium ion battery, characterized in that,
the electrode material for the lithium ion battery comprises a positive electrode material and a negative electrode material;
the positive electrode material is selected from LiCoO 2 、LiNiO 2 、LiMnO 2 、LiMn 2 O 4 、LiMn x Ni y Co 1-x-y O 2 、LiVO 2 、Li x V 2 O 4 、Li x V 3 O 8 、LiFeO 2 Or LiFePO 4 At least one of;
wherein, x ranges from 0.1 to 2; y ranges from 0.1 to 2;
the negative electrode material is selected from at least one of artificial graphite, natural graphite, activated carbon, a silicon-based negative electrode material or a tin-based negative electrode material;
the positive electrode material and/or the negative electrode material contains the adhesive according to any one of claims 1 to 3 or the adhesive obtained by the production method according to any one of claims 4 to 6;
preferably, the adhesive needs to be subjected to heat crosslinking treatment when in use;
preferably, the temperature of the thermal crosslinking is 80-200 ℃;
preferably, the temperature of the thermal crosslinking is 100 ℃ to 150 ℃.
8. A preparation method of a lithium ion battery electrode is characterized in that,
at least comprises the following steps:
mixing materials containing electrode materials and conductive agents, and performing ball milling to obtain slurry;
coating the slurry on the surface of a substrate, and drying to obtain the lithium ion battery electrode;
wherein, when preparing the positive electrode, the electrode material is selected from the positive electrode material in claim 7;
when preparing a negative electrode, the electrode material is selected from the negative electrode materials described in claim 7.
9. The method of claim 8,
the conductive agent is selected from conductive carbon black, carbon nano tubes or graphene;
the dosage ratio of the electrode material to the conductive agent is 65-99;
preferably, the ball milling time is 1-5 h;
preferably, the drying temperature is 80-200 ℃;
preferably, the drying time is 4-24 h;
preferably, the drying is performed under vacuum conditions;
preferably, the vacuum degree of the drying is-0.02 to-0.1 MPa.
10. A lithium ion battery is characterized in that,
the lithium ion battery employs the positive electrode and/or the negative electrode prepared according to claim 9.
CN202210791711.XA 2022-07-07 2022-07-07 Adhesive, preparation method thereof and application thereof in lithium ion battery Pending CN115295802A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116525771A (en) * 2023-05-05 2023-08-01 湖南山锂新能源科技有限公司 Modified lithium ion battery anode material and preparation method and application thereof
CN116836653A (en) * 2023-06-13 2023-10-03 南平市延平鑫东来科技有限公司 Conductive adhesive, preparation method thereof and application thereof in lithium ion battery

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116525771A (en) * 2023-05-05 2023-08-01 湖南山锂新能源科技有限公司 Modified lithium ion battery anode material and preparation method and application thereof
CN116525771B (en) * 2023-05-05 2024-02-09 湖南山锂新能源科技有限公司 Modified lithium ion battery anode material and preparation method and application thereof
CN116836653A (en) * 2023-06-13 2023-10-03 南平市延平鑫东来科技有限公司 Conductive adhesive, preparation method thereof and application thereof in lithium ion battery

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