CN113380985B - Method for improving stability of negative plate - Google Patents

Method for improving stability of negative plate Download PDF

Info

Publication number
CN113380985B
CN113380985B CN202110593159.9A CN202110593159A CN113380985B CN 113380985 B CN113380985 B CN 113380985B CN 202110593159 A CN202110593159 A CN 202110593159A CN 113380985 B CN113380985 B CN 113380985B
Authority
CN
China
Prior art keywords
carboxymethyl cellulose
deionized water
slurry
solution
citric acid
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN202110593159.9A
Other languages
Chinese (zh)
Other versions
CN113380985A (en
Inventor
宫娇娇
陈军
黄建根
郑利峰
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Wanxiang A123 Systems Asia Co Ltd
Original Assignee
Wanxiang A123 Systems Asia Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Wanxiang A123 Systems Asia Co Ltd filed Critical Wanxiang A123 Systems Asia Co Ltd
Priority to CN202110593159.9A priority Critical patent/CN113380985B/en
Publication of CN113380985A publication Critical patent/CN113380985A/en
Application granted granted Critical
Publication of CN113380985B publication Critical patent/CN113380985B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • 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
    • H01M4/139—Processes of manufacture
    • 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
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0404—Methods of deposition of the material by coating on electrode collectors
    • 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
    • H01M4/04—Processes of manufacture in general
    • H01M4/043—Processes of manufacture in general involving compressing or compaction
    • H01M4/0435—Rolling or calendering
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

The invention relates to the field of lithium ion batteries, and discloses a method for improving the stability of a negative plate, aiming at solving the problems that in the prior art, carboxymethyl cellulose has insufficient toughness and is easily degraded by bacteria, the prepared negative plate is easy to crack, and the service life is short, wherein the method comprises the following steps: A. adding carboxymethyl cellulose, citric acid and a cross-linking agent into deionized water, strongly stirring at normal temperature until the carboxymethyl cellulose, the citric acid and the cross-linking agent are completely dissolved, adding a bacteriostatic agent and a polystyrene butadiene copolymer, and stirring until the bacteriostatic agent and the polystyrene butadiene copolymer are completely dissolved to obtain a mixed binder solution; B. mixing an active material, a conductive agent, a mixed binder and deionized water; C. adjusting the pH value of the slurry; D. and uniformly coating the negative electrode slurry on a copper foil, and baking, rolling and cutting to obtain the negative electrode sheet. The invention effectively improves the adhesiveness and toughness of the slurry in the negative plate, avoids the slurry from falling off or cracking on the negative plate, obviously prolongs the cycle service life of the negative plate, and has low production cost and simple operation.

Description

Method for improving stability of negative plate
Technical Field
The invention relates to the field of lithium ion batteries, in particular to a method for improving the stability of a negative plate.
Background
In the past two decades, lithium ion batteries have become important power sources for portable devices, and the next generation of lithium ion batteries are widely used in the fields of electric vehicles, power grids, solar energy storage and the like. The manufacturing process of the lithium ion battery has considerable influence on subsequent performance and cost, and the water-based negative plate taking carboxymethyl cellulose (CMC) and Styrene Butadiene Rubber (SBR) as the binder has the advantages of low production cost, small environmental pollution degree and the like, and is widely applied to domestic and foreign lithium ion battery enterprises. However, the flexibility of the carboxymethyl cellulose is limited, the pole piece is easy to crack, and meanwhile, a very small amount of actinomycetes and the like can degrade the carboxymethyl cellulose into polysaccharide or disaccharide, destroy the molecular structure and influence the performance of the subsequent lithium ion battery.
For example, a "carboxymethyl cellulose-based binder and its application in lithium batteries" disclosed in chinese patent literature, which is publication No. CN109638286B, includes the following components in parts by weight: 30-40 parts of sodium carboxymethylcellulose, 10-20 parts of modified SBR, 1-5 parts of tea saponin, 1-5 parts of a thickening agent and 5-10 parts of a diluting auxiliary agent. The modified SBR is used in the invention, so that the stability of the SBR and the flexibility of a slurry system are improved, but the problems of the flexibility and the decomposition of the carboxymethyl cellulose are not solved.
Disclosure of Invention
The invention provides a method for improving the stability of a negative plate, aiming at overcoming the problems that in the prior art, the toughness of carboxymethyl cellulose is insufficient, the prepared negative plate is easy to crack, and the carboxymethyl cellulose is easy to be degraded into polysaccharide or disaccharide by bacteria in the using process of the negative plate, so that the performance of a subsequent lithium ion battery is influenced.
In order to achieve the purpose, the invention adopts the following technical scheme:
a method for improving the stability of a negative plate comprises the following steps:
A. adding carboxymethyl cellulose, citric acid and a cross-linking agent into deionized water, strongly stirring at normal temperature until the carboxymethyl cellulose, the citric acid and the cross-linking agent are completely dissolved, adding a bacteriostatic agent and a polystyrene butadiene copolymer, and stirring until the bacteriostatic agent and the polystyrene butadiene copolymer are completely dissolved to obtain a mixed binder solution;
B. mixing an active material, a conductive agent, a mixed binder and deionized water;
C. adjusting the pH value of the slurry;
D. and uniformly coating the negative electrode slurry on a copper foil, and baking, rolling and cutting to obtain the negative electrode sheet.
The carboxymethyl cellulose is subjected to condensation esterification under the action of citric acid and forms a flexible binder network with a cross-linking agent, so that the toughness and viscosity of the carboxymethyl cellulose are improved; the bacteriostatic agent can inhibit the increase of bacteria in the negative electrode slurry, reduce the degraded amount of the carboxymethyl cellulose, avoid the flexible network structure from being damaged, and prolong the cycle life of the negative electrode plate.
Preferably, in the step A, the mass ratio of the carboxymethyl cellulose to the citric acid to the cross-linking agent to the bacteriostatic agent to the polystyrene-butadiene copolymer is (2-3) to (1-3) to (0.1-0.65) to (8-16), the mass fraction of the carboxymethyl cellulose in the mixed binder solution is 2-3%, and the deionized water is sterilized by ultraviolet rays.
The deionized water after ultraviolet disinfection has less bacteria content, and the degradation amount of the carboxymethyl cellulose is reduced.
Preferably, the cross-linking agent in the step A is one or more of natural guar gum, cationic guar gum or hydroxypropyl guar gum.
Guar gum and modified guar gum are thickeners, have good mechanical strength and cohesiveness, can cushion the graphite particle volume change in the continuous charge-discharge process simultaneously, have inhibited the extra side reaction that the graphite particle breaks and causes to guar gum and modified guar gum are linear structure and can cross-link with carboxymethyl cellulose under the effect of citric acid, still further promote carboxymethyl cellulose's flexibility except increasing the stickness of mixed binder, make the difficult fracture of negative pole piece that makes.
Preferably, the bacteriostatic agent is one or more of amino cellulose, N, O-hydroxymethylated chitosan and chitin.
The nano-sized amino cellulose, N, O-hydroxymethylated chitosan and chitin have the bacteriostatic action.
Preferably, the carboxymethyl cellulose in the step A is prepared from corncobs by the following steps:
a. separating and crushing corncobs from corn straws, sieving the corncobs by a 50-200-mesh sieve, heating the powder in an oven at the temperature of 100 ℃ and 120 ℃ for 1-3 hours, taking out the corncobs, cooling the corncobs to room temperature, dissolving the corncobs into a sodium hydroxide solution with the mass fraction of 8-10% overnight, filtering the corncobs, continuously adding the powder precipitate into a sodium chlorite solution with the mass fraction of 1-2%, keeping the solution at the temperature of 50-70 ℃ for 10-20 hours, filtering the obtained powder, adding the powder into isopropanol, stirring the mixture for 10-30 minutes at normal temperature, slowly adding the sodium hydroxide solution with the mass fraction of 20-40% into the mixed system, and continuously stirring the mixture for 1-2 hours;
b. b, dropwise adding a mixed solution of water and isopropanol containing sodium monochloroacetate into the mixed system obtained in the step a, and keeping the mixed solution at the temperature of 50-70 ℃ for 2-5h, wherein the volume ratio of the water to the isopropanol in the mixed solution of the water and the isopropanol of the sodium monochloroacetate is 1 (1-1.5), and the mass fraction of the sodium monochloroacetate is 5-20%;
c. and c, cooling the solution obtained in the step b to room temperature, filtering, dissolving the slurry with impurities removed in methanol, wherein the volume ratio of the slurry to the methanol is 1 (1-3), adding 96-98% by mass of acetic acid for neutralization, washing the obtained product with industrial ethanol for 2-3 times to remove the impurities, and drying at 70-100 ℃ for 6-10 hours to obtain carboxymethyl cellulose powder.
In the invention, the carboxymethyl cellulose is prepared from corncobs, the cost is low, and the carboxymethyl cellulose prepared by the preparation method has better performance.
Preferably, in the carboxymethyl cellulose preparation step, the mass ratio of corncobs, 8-10% of sodium hydroxide, sodium chlorite solution, 20-40% of sodium hydroxide solution, sodium monochloroacetate solution and acetic acid is (10-30): 20-50): (40-80): (15-35): (10-30):(5-15).
Preferably, in the step B, the active material is one or more of artificial graphite, natural graphite, hard carbon, soft carbon, mesocarbon microbeads, silicon and oxides thereof, tin and oxides thereof, and the conductive agent is one or more of carbon black, ketjen black, conductive graphite, carbon nanotubes, vapor-deposited carbon nanofibers, and graphene.
Preferably, the mass ratio of the active material, the conductive agent, the mixed binder and the water in the step B is (85-90) to (3-6): (2-5): (90-235).
Preferably, phosphoric acid is added in the step C to adjust the pH value to 6-9.
The pH value of the slurry can corrode an oxide layer on the surface of the copper foil within the range of 6-9, the surface roughness is increased, the adhesion of the negative plate is improved, a phosphoric acid-phosphate buffer system can be formed by using phosphoric acid, and the pH value of the negative slurry is stabilized.
Preferably, the coating method in the step D is a doctor blade method, a transfer coating method or a squeeze coating method, and the coating surface density is 70-150g/m2。
The coating amount is too low, the energy density of the lithium ion battery is low, and the manufacturing cost of the battery is high; the coating amount is too high, so that the electronic and lithium ion conduction performance is influenced, and the electrical property is poor.
Therefore, the invention has the following beneficial effects: (1) the adhesiveness and the toughness of the slurry in the negative plate are effectively improved, and the slurry is prevented from falling off or cracking on the negative plate; (2) the cycle service life of the negative plate is obviously prolonged; (3) low production cost and simple operation.
Detailed Description
The invention is further described below with reference to specific embodiments.
The carboxymethyl cellulose used in the following examples was prepared by the following steps:
a. separating and crushing corncobs from corn straws, sieving the corncobs by a 100-mesh sieve, heating the powder in an oven at 120 ℃ for 2 hours, taking out the corncobs, cooling the corncobs to room temperature, dissolving the corncobs into a sodium hydroxide solution with the mass fraction of 10% overnight, filtering the corncobs, continuously adding powder precipitates into a sodium chlorite solution with the mass fraction of 2%, keeping the mixture at 60 ℃ for 20 hours, filtering the obtained powder, adding the powder into isopropanol, stirring the mixture at normal temperature for 20 minutes, slowly adding a sodium hydroxide solution with the mass fraction of 40% into the mixed system, and continuously stirring the mixture for 2 hours, wherein the mass ratio of the corncobs, the 10% sodium hydroxide, the sodium chlorite solution and the 40% sodium hydroxide solution is 20:50:80: 20;
b. dropwise adding a water and isopropanol mixed solution containing sodium monochloroacetate in a volume ratio of 1:1.5 into the mixed system, and keeping the mixed solution at 60 ℃ for 4 hours, wherein the mass fraction of the sodium monochloroacetate is 15%;
c. cooling the solution to room temperature, filtering, dissolving the slurry with impurities removed in methanol at a volume ratio of 1:2, adding 98% by mass of acetic acid for neutralization, washing the obtained product with industrial ethanol for 3 times to remove impurities, and drying at 80 ℃ for 8h to obtain carboxymethyl cellulose powder.
Example 1
A. After deionized water is disinfected by ultraviolet rays, adding carboxymethyl cellulose, hydroxypropyl guar gum and citric acid into the deionized water, strongly stirring at normal temperature until the carboxymethyl cellulose, the hydroxypropyl guar gum and the citric acid are completely dissolved, adding amino cellulose and a polystyrene butadiene copolymer, and mixing to obtain a mixed binder solution, wherein the mass ratio of the carboxymethyl cellulose to the citric acid to the hydroxypropyl guar gum to the amino cellulose to the polystyrene butadiene copolymer to the deionized water is 3:2:2:0.5: 10: 83;
B. adding the artificial graphite, the carbon nano tube and the mixed binder into deionized water which is sterilized by ultraviolet rays, and uniformly stirring, wherein the mass ratio of the artificial graphite to the carbon nano tube to the mixed binder to water is 18: 1:1: 18;
C. adding phosphoric acid to adjust the pH value of the slurry to 6;
D. uniformly coating the negative electrode slurry on a copper foil by using a scraper method, wherein the coating amount is 100g/m2And baking, rolling and cutting to obtain the cathode sheet.
Example 2
A. After deionized water is disinfected by ultraviolet rays, adding carboxymethyl cellulose, natural guar gum and citric acid into the deionized water, strongly stirring at normal temperature until the carboxymethyl cellulose, the natural guar gum and the citric acid are completely dissolved, adding amino cellulose and a polystyrene butadiene copolymer, and mixing to obtain a mixed binder solution, wherein the mass ratio of the carboxymethyl cellulose to the citric acid to the natural guar gum to the amino cellulose to the polystyrene butadiene copolymer to the deionized water is 3:2:2:0.5: 10: 83;
B. adding the artificial graphite, the carbon nano tube and the mixed binder into deionized water which is sterilized by ultraviolet rays, and uniformly stirring, wherein the mass ratio of the artificial graphite to the carbon nano tube to the mixed binder to water is 18: 1:1: 18;
C. adding phosphoric acid to adjust the pH value of the slurry to 6;
D. uniformly coating the negative electrode slurry on a copper foil by using a scraper method, wherein the coating amount is 100g/m2And baking, rolling and cutting to obtain the negative plate.
Example 3
A. After deionized water is disinfected by ultraviolet rays, adding carboxymethyl cellulose, cationic guar gum and citric acid into the deionized water, strongly stirring at normal temperature until the carboxymethyl cellulose, the cationic guar gum and the citric acid are completely dissolved, adding amino cellulose and a polystyrene butadiene copolymer, and mixing to obtain a mixed binder solution, wherein the mass ratio of the carboxymethyl cellulose to the citric acid to the cationic guar gum to the amino cellulose to the polystyrene butadiene copolymer to the deionized water is 3:2:2:0.5: 10: 83;
B. adding the artificial graphite, the carbon nano tube and the mixed binder into deionized water which is sterilized by ultraviolet rays, and uniformly stirring, wherein the mass ratio of the artificial graphite to the carbon nano tube to the mixed binder to water is 18: 1:1: 18;
C. adding phosphoric acid to adjust the pH value of the slurry to 6;
D. uniformly coating the negative electrode slurry on a copper foil by using a scraper method, wherein the coating amount is 100g/m2And baking, rolling and cutting to obtain the cathode sheet.
Example 4
A. After deionized water is disinfected by ultraviolet rays, adding carboxymethyl cellulose, hydroxypropyl guar gum and citric acid into the deionized water, strongly stirring at normal temperature until the carboxymethyl cellulose, the hydroxypropyl guar gum and the hydroxypropyl guar gum are completely dissolved, adding N, O-hydroxymethylated chitosan and a polystyrene butadiene copolymer, and mixing to obtain a mixed binder solution, wherein the mass ratio of the carboxymethyl cellulose to the citric acid to the hydroxypropyl guar gum to the N, O-hydroxymethylated chitosan to the polystyrene butadiene copolymer to the deionized water is 3:2:2:0.5: 10: 83;
B. adding the artificial graphite, the carbon nano tube and the mixed binder into deionized water which is sterilized by ultraviolet rays, and uniformly stirring, wherein the mass ratio of the artificial graphite to the carbon nano tube to the mixed binder to water is 18: 1:1: 18;
C. adding phosphoric acid to adjust the pH value of the slurry to 6;
D. uniformly coating the negative electrode slurry on a copper foil by using a scraper method, wherein the coating amount is 100g/m2And baking, rolling and cutting to obtain the negative plate.
Example 5
A. After deionized water is disinfected by ultraviolet rays, adding carboxymethyl cellulose, hydroxypropyl guar gum and citric acid into the deionized water, strongly stirring at normal temperature until the carboxymethyl cellulose, the hydroxypropyl guar gum and the citric acid are completely dissolved, adding chitin and a polystyrene butadiene copolymer, and mixing to obtain a mixed binder solution, wherein the mass ratio of the carboxymethyl cellulose to the citric acid to the hydroxypropyl guar gum to the chitin to the polystyrene butadiene copolymer to the deionized water is 3:2:2:0.5: 10: 83;
B. adding the artificial graphite, the carbon nano tube and the mixed binder into deionized water which is sterilized by ultraviolet rays, and uniformly stirring, wherein the mass ratio of the artificial graphite to the carbon nano tube to the mixed binder to water is 18: 1:1: 18;
C. adding phosphoric acid to adjust the pH value of the slurry to 6;
D. uniformly coating the negative electrode slurry on a copper foil by using a scraper method, wherein the coating amount is 100g/m2And baking, rolling and cutting to obtain the negative plate.
Example 6
A. After deionized water is disinfected by ultraviolet rays, adding carboxymethyl cellulose, hydroxypropyl guar gum and citric acid into the deionized water, strongly stirring at normal temperature until the carboxymethyl cellulose, the hydroxypropyl guar gum and the citric acid are completely dissolved, adding amino cellulose and a polystyrene butadiene copolymer, and mixing to obtain a mixed binder solution, wherein the mass ratio of the carboxymethyl cellulose to the citric acid to the hydroxypropyl guar gum to the amino cellulose to the polystyrene butadiene copolymer to the deionized water is 3:1:1:0.48: 10: 80;
B. adding the artificial graphite, the carbon nano tube and the mixed binder into deionized water which is sterilized by ultraviolet rays, and uniformly stirring, wherein the mass ratio of the artificial graphite to the carbon nano tube to the mixed binder to water is 18: 1:1: 18;
C. adding phosphoric acid to adjust the pH value of the slurry to 6;
D. uniformly coating the negative electrode slurry on a copper foil by using a scraper method, wherein the coating amount is 100g/m2And baking, rolling and cutting to obtain the negative plate.
Example 7
A. After deionized water is disinfected by ultraviolet rays, adding carboxymethyl cellulose, hydroxypropyl guar gum and citric acid into the deionized water, strongly stirring at normal temperature until the carboxymethyl cellulose, the hydroxypropyl guar gum and the citric acid are completely dissolved, adding amino cellulose and a polystyrene butadiene copolymer, and mixing to obtain a mixed binder solution, wherein the mass ratio of the carboxymethyl cellulose to the citric acid to the hydroxypropyl guar gum to the amino cellulose to the polystyrene butadiene copolymer to the deionized water is 2:3:3:0.4: 10: 81;
B. adding the artificial graphite, the carbon nano tube and the mixed binder into deionized water which is sterilized by ultraviolet rays, and uniformly stirring, wherein the mass ratio of the artificial graphite to the carbon nano tube to the mixed binder to water is 18: 1:1: 18;
C. adding phosphoric acid to adjust the pH value of the slurry to 6;
D. uniformly coating the negative electrode slurry on a copper foil by using a scraper method, wherein the coating amount is 100g/m2And baking, rolling and cutting to obtain the negative plate.
Example 8
A. After deionized water is disinfected by ultraviolet rays, adding carboxymethyl cellulose, hydroxypropyl guar gum and citric acid into the deionized water, strongly stirring at normal temperature until the carboxymethyl cellulose, the hydroxypropyl guar gum and the citric acid are completely dissolved, adding amino cellulose and a polystyrene butadiene copolymer, and mixing to obtain a mixed binder solution, wherein the mass ratio of the carboxymethyl cellulose to the citric acid to the hydroxypropyl guar gum to the amino cellulose to the polystyrene butadiene copolymer to the deionized water is 3:2:2:0.5: 10: 83;
B. adding the artificial graphite, the carbon nano tube and the mixed binder into deionized water which is sterilized by ultraviolet rays, and uniformly stirring, wherein the mass ratio of the artificial graphite to the carbon nano tube to the mixed binder to water is 18: 1:1: 18;
C. adding phosphoric acid to adjust the pH value of the slurry to 9;
D. uniformly coating the negative electrode slurry on a copper foil by using a scraper method, wherein the coating amount is 100g/m2And baking, rolling and cutting to obtain the negative plate.
Example 9
A. After the deionized water is disinfected by ultraviolet rays, adding carboxymethyl cellulose, hydroxypropyl guar gum and citric acid into the deionized water, strongly stirring at normal temperature until all the carboxymethyl cellulose, the hydroxypropyl guar gum and the citric acid are dissolved, adding amino cellulose and a polystyrene butadiene copolymer, and mixing to obtain a mixed binder solution, wherein the mass ratio of the carboxymethyl cellulose, the citric acid, the hydroxypropyl guar gum, the amino cellulose, the polystyrene butadiene copolymer to the deionized water is 3:2:2:0.5: 10: 83;
B. adding the artificial graphite, the carbon nano tube and the mixed binder into deionized water which is sterilized by ultraviolet rays, and uniformly stirring, wherein the mass ratio of the artificial graphite to the carbon nano tube to the mixed binder to water is 18: 1:1: 18;
C. adding phosphoric acid to adjust the pH value of the slurry to 7;
D. uniformly coating the negative electrode slurry on a copper foil by using a scraper method, wherein the coating amount is 70g/m2And baking, rolling and cutting to obtain the negative plate.
Example 10
A. After the deionized water is disinfected by ultraviolet rays, adding carboxymethyl cellulose and hydroxypropyl guar gum into the deionized water, strongly stirring at normal temperature until all the carboxymethyl cellulose and the hydroxypropyl guar gum are dissolved, adding amino cellulose and a polystyrene butadiene copolymer, and mixing to obtain a mixed binder solution, wherein the mass ratio of the carboxymethyl cellulose to the hydroxypropyl guar gum to the amino cellulose to the polystyrene butadiene copolymer to the deionized water is (3: 2:0.5: 10): 85 parts by weight;
B. adding the artificial graphite, the carbon nano tube and the mixed binder into deionized water subjected to ultraviolet disinfection, and uniformly stirring, wherein the mass ratio of the artificial graphite to the carbon nano tube to the mixed binder to water is 20: 2: 1: 37;
C. adding phosphoric acid to adjust the pH value of the slurry to 6;
D. uniformly coating the negative electrode slurry on a copper foil by using a scraper method, wherein the coating amount is 100g/m2And baking, rolling and cutting to obtain the negative plate.
Example 11
A. After deionized water is disinfected by ultraviolet rays, adding carboxymethyl cellulose and citric acid into the deionized water, strongly stirring at normal temperature until the carboxymethyl cellulose and the citric acid are completely dissolved, adding amino cellulose and a polystyrene butadiene copolymer, and mixing to obtain a mixed binder solution, wherein the mass ratio of the carboxymethyl cellulose to the citric acid to the amino cellulose to the polystyrene butadiene copolymer to the deionized water is 3:2:0.5: 10: 85 parts by weight;
B. adding the artificial graphite, the carbon nano tube and the mixed binder into deionized water which is sterilized by ultraviolet rays, and uniformly stirring, wherein the mass ratio of the artificial graphite to the carbon nano tube to the mixed binder to water is 20: 2: 1: 37;
C. adding phosphoric acid to adjust the pH value of the slurry to 6;
D. mixing the above negative electrode slurryUniformly coating the copper foil with a doctor blade method, wherein the coating amount is 100g/m2And baking, rolling and cutting to obtain the negative plate.
Example 12
A. After deionized water is disinfected by ultraviolet rays, adding carboxymethyl cellulose, hydroxypropyl guar gum and citric acid into the deionized water, strongly stirring at normal temperature until the carboxymethyl cellulose, the hydroxypropyl guar gum and the citric acid are completely dissolved, adding amino cellulose and a polystyrene butadiene copolymer, and mixing to obtain a mixed binder solution, wherein the mass ratio of the carboxymethyl cellulose to the citric acid to the hydroxypropyl guar gum to the amino cellulose to the polystyrene butadiene copolymer to the deionized water is 3:2:2:0.5: 10: 83;
B. adding the artificial graphite, the carbon nano tube and the mixed binder into deionized water which is sterilized by ultraviolet rays, and uniformly stirring, wherein the mass ratio of the artificial graphite to the carbon nano tube to the mixed binder to water is 20: 2: 1: 37;
C. adding phosphoric acid to adjust the pH value of the slurry to 6;
D. uniformly coating the negative electrode slurry on a copper foil by using a scraper method, wherein the coating amount is 100g/m2And baking, rolling and cutting to obtain the cathode sheet.
Example 13
A. After deionized water is disinfected by ultraviolet rays, adding carboxymethyl cellulose, hydroxypropyl guar gum and citric acid into the deionized water, strongly stirring at normal temperature until the carboxymethyl cellulose, the hydroxypropyl guar gum and the citric acid are completely dissolved, adding amino cellulose and a polystyrene butadiene copolymer, and mixing to obtain a mixed binder solution, wherein the mass ratio of the carboxymethyl cellulose to the citric acid to the hydroxypropyl guar gum to the amino cellulose to the polystyrene butadiene copolymer to the deionized water is 3:2:2:0.5: 10: 83;
B. adding the artificial graphite, the carbon nano tube and the mixed binder into deionized water subjected to ultraviolet disinfection, and uniformly stirring, wherein the mass ratio of the artificial graphite to the carbon nano tube to the mixed binder to water is 18: 1:1: 18;
C. adding phosphoric acid to adjust the pH value of the slurry to 6;
D. uniformly coating the negative electrode slurry on a copper foil by using a scraper method, wherein the coating amount is 150g/m2Is dried by bakingAnd baking, rolling and cutting to obtain the negative plate.
Example 14
A. After deionized water is disinfected by ultraviolet rays, adding carboxymethyl cellulose with the industrial model number of SHX-5, hydroxypropyl guar gum and citric acid into the deionized water, strongly stirring at normal temperature until all the carboxymethyl cellulose, the citric acid, the hydroxypropyl guar gum, the amino cellulose, the polystyrene butadiene copolymer and the deionized water are dissolved completely, and then adding amino cellulose and the polystyrene butadiene copolymer to mix to obtain a mixed binder solution, wherein the mass ratio of the carboxymethyl cellulose to the citric acid to the hydroxypropyl guar gum to the amino cellulose to the polystyrene butadiene copolymer to the deionized water is 3:2:2:0.5: 10: 83;
B. adding the artificial graphite, the carbon nano tube and the mixed binder into deionized water which is sterilized by ultraviolet rays, and uniformly stirring, wherein the mass ratio of the artificial graphite to the carbon nano tube to the mixed binder to water is 18: 1:1: 18;
C. adding phosphoric acid to adjust the pH value of the slurry to 6;
D. uniformly coating the negative electrode slurry on a copper foil by using a scraper method, wherein the coating amount is 100g/m2And baking, rolling and cutting to obtain the negative plate.
Comparative example 1
A. After the deionized water is disinfected by ultraviolet rays, adding carboxymethyl cellulose, amino cellulose, citric acid, xanthan gum and polystyrene butadiene copolymer into the deionized water, and strongly stirring at normal temperature until the carboxymethyl cellulose, the citric acid, the xanthan gum, the amino cellulose, the polystyrene butadiene copolymer and the deionized water are completely dissolved to obtain a mixed binder solution, wherein the mass ratio of the carboxymethyl cellulose to the citric acid to the xanthan gum to the polystyrene butadiene copolymer to the deionized water is 3:2:2:0.5: 10: 83;
B. adding the artificial graphite, the carbon nano tube and the mixed binder into deionized water which is sterilized by ultraviolet rays, and uniformly stirring, wherein the mass ratio of the artificial graphite to the carbon nano tube to the mixed binder to water is 18: 1:1: 18;
C. adding phosphoric acid to adjust the pH value of the slurry to 6;
D. uniformly coating the negative electrode slurry on a copper foil by using a scraper method, wherein the coating amount is 100g/m2And baking, rolling and cutting to obtain the negative plate.
Comparative example 2
A. After the deionized water is disinfected by ultraviolet rays, adding carboxymethyl cellulose, citric acid, hydroxypropyl guar gum and polystyrene butadiene copolymer into the deionized water, and strongly stirring at normal temperature until the carboxymethyl cellulose, the citric acid, the hydroxypropyl guar gum, the polystyrene butadiene copolymer and the deionized water are completely dissolved to obtain a mixed binder solution, wherein the mass ratio of the carboxymethyl cellulose to the citric acid to the hydroxypropyl guar gum to the polystyrene butadiene copolymer to the deionized water is 3:2:2: 10: 83;
B. adding the artificial graphite, the carbon nano tube and the mixed binder into deionized water, and uniformly stirring, wherein the mass ratio of the artificial graphite to the carbon nano tube to the mixed binder to the water is 18: 1:1: 18;
C. adding phosphoric acid to adjust the pH value of the slurry to 6;
D. uniformly coating the negative electrode slurry on a copper foil by using a scraper method, wherein the coating amount is 100g/m2And baking, rolling and cutting to obtain the negative plate.
Testing the adhesion and cycle life of the negative plates obtained in the examples 1-10 and the comparative examples 1-2 when the negative plates are placed for 0 day and 10 days, wherein the testing method of the adhesion of the negative plates is a pull-off method test described in GB5210, the testing method of the cycle life is to use the negative plates obtained in the examples 1-10 and the comparative examples 1-2 as working electrodes, prepare a half cell by using a pure lithium plate as a counter electrode, and test the cycle life at 0.1-2.0V voltage range and 0.3-1.0C multiplying power at normal temperature; the adhesion and cycle life obtained are shown in the following table: TABLE 1 adhesion and cycle life of negative electrode sheets of examples 1-10 and comparative examples 1-2
Figure GDA0003562480730000091
As can be seen from table 1, when the cross-linking agent is selected from hydroxypropyl guar gum, the effect is better than that of selecting natural guar gum and cationic guar gum, in the negative electrode slurry system of the present invention, the solubility of hydroxypropyl guar gum is higher, and the hydroxypropyl guar gum is easier to form a cross-linked network with carboxymethyl cellulose, xanthan gum is also a commonly used thickener, but in the negative electrode slurry system of the present invention, the hydroxypropyl guar gum is difficult to form a network structure with carboxymethyl cellulose, and the adhesion and stability of the negative electrode sheet of the comparative example 1 are weaker than those of the example 1, it can be verified that the improvement of the performance of the negative electrode slurry by the cross-linking agent is partially from the thickening effect of the cross-linking agent itself, and the other part from the cross-linked network with carboxymethyl cellulose; when citric acid or hydroxypropyl guar gum is absent in the negative electrode slurry, the stability of the negative electrode sheet is lower than that of the negative electrode with both citric acid and hydroxypropyl guar gum, which proves that when citric acid is absent in the system, carboxymethyl cellulose cannot be crosslinked with hydroxypropyl guar gum to form a net, and the ratio of the carboxymethyl cellulose to the citric acid and the crosslinking agent also influences the formation of a crosslinked network, in a 10-day test, the adhesion and the cycle life of example 1 are better than those of example 6 and example 7, so when the ratio of the carboxymethyl cellulose to the citric acid to the crosslinking agent is 3:2:2, the formed crosslinked network is larger, and the quality is better; the negative plate of example 12 has good stability, and when a cross-linked network is generated in the binder, the viscosity and toughness of the binder can be enhanced, and a small amount of binder can ensure that the negative paste does not fall off and crack from the negative plate, so that the proportion of the binder in the negative paste can be reduced, and the content of the conductive agent and the active material can be increased, thereby improving the energy density of the battery.
The amino cellulose, the N, O-hydroxymethylation chitosan and the chitin have certain antibacterial effects, when the antibacterial agent is added into the negative electrode slurry, the adhesive force and the cycle life of the negative electrode plate are reduced by less than those of a comparative example 2 without the antibacterial agent after 10 days, so that the negative electrode slurry prepared by using the ultraviolet sterilized deionized water still has a small amount of mould, the mould can damage the carboxymethyl cellulose after being used for a period of time, and the antibacterial agent can effectively reduce the degradation amount of the carboxymethyl cellulose and improve the stability of the negative electrode plate.
The carboxymethyl cellulose prepared by the corncobs has the advantages of low cost and strong toughness of a cross-linked web, the performance of the carboxymethyl cellulose prepared by the corncobs is better than that of the carboxymethyl cellulose with the model of SHX-5, and when the pH value and the coating amount of the negative pole slurry are within the range of the invention, the negative pole piece has good adhesive force and cycle life.

Claims (7)

1. A method for improving the stability of a negative plate is characterized by comprising the following steps:
A. adding carboxymethyl cellulose, citric acid and a cross-linking agent into deionized water, strongly stirring at normal temperature until the carboxymethyl cellulose, the citric acid and the cross-linking agent are completely dissolved, adding a bacteriostatic agent and a polystyrene butadiene copolymer, and stirring until the bacteriostatic agent and the polystyrene butadiene copolymer are completely dissolved to obtain a mixed binder solution;
B. mixing an active material, a conductive agent, a mixed binder and deionized water;
C. adjusting the pH value of the slurry;
D. uniformly coating the negative electrode slurry on a copper foil, and baking, rolling and cutting to prepare a negative electrode sheet;
the cross-linking agent in the step A is one or more of natural guar gum, cationic guar gum or hydroxypropyl guar gum, and the bacteriostatic agent is one or more of amino cellulose, N, O-hydroxymethylation chitosan and chitin;
and C, adding phosphoric acid to adjust the pH value to 6-9.
2. The method of claim 1, wherein in the step A, the mass ratio of the carboxymethylcellulose to the citric acid to the cross-linking agent to the bacteriostatic agent to the polystyrene-butadiene copolymer is (2-3) to (1-3) to (0.1-0.65) to (8-16), the mass fraction of the carboxymethylcellulose in the mixed binder solution is 2-3%, and the deionized water is sterilized by ultraviolet rays.
3. The method for improving the stability of the negative plate according to claim 1, wherein the carboxymethyl cellulose is prepared from corncobs in the step A, and the preparation steps are as follows:
a. separating and crushing corncobs from corn straws, sieving the corncobs by a 50-200-mesh sieve, heating the powder in an oven at the temperature of 100 ℃ and 120 ℃ for 1-3 hours, taking out the corncobs, cooling the corncobs to room temperature, dissolving the corncobs into a sodium hydroxide solution with the mass fraction of 8-10% overnight, filtering the corncobs, continuously adding the powder precipitate into a sodium chlorite solution with the mass fraction of 1-2%, keeping the solution at the temperature of 50-70 ℃ for 10-20 hours, filtering the obtained powder, adding the powder into isopropanol, stirring the mixture for 10-30 minutes at normal temperature, slowly adding the sodium hydroxide solution with the mass fraction of 20-40% into the mixed system, and continuously stirring the mixture for 1-2 hours;
b. b, dropwise adding a mixed solution of water and isopropanol containing sodium monochloroacetate into the mixed system obtained in the step a, and keeping the mixed solution at the temperature of 50-70 ℃ for 2-5h, wherein the volume ratio of the water to the isopropanol in the mixed solution of the water and the isopropanol of the sodium monochloroacetate is 1 (1-1.5), and the mass fraction of the sodium monochloroacetate is 5-20%;
c. and c, cooling the solution obtained in the step b to room temperature, filtering, dissolving the slurry with impurities removed in methanol, wherein the volume ratio of the slurry to the methanol is 1 (1-3), adding 96-98% by mass of acetic acid for neutralization, washing the obtained product with industrial ethanol for 2-3 times to remove the impurities, and drying at 70-100 ℃ for 6-10 hours to obtain carboxymethyl cellulose powder.
4. The method as claimed in claim 3, wherein in the step of preparing the carboxymethyl cellulose, the mass ratio of the corncob, 8-10% of sodium hydroxide, sodium chlorite solution, 20-40% of sodium hydroxide solution, sodium monochloroacetate solution and acetic acid is (10-30): (20-50): (40-80): (15-35): (10-30):(5-15).
5. The method of claim 1, wherein in the step B, the active material is one or more of artificial graphite, natural graphite, hard carbon, soft carbon, mesocarbon microbeads, silicon and oxides thereof, and tin and oxides thereof, and the conductive agent is one or more of carbon black, Ketjen black, conductive graphite, carbon nanotubes, vapor-deposited carbon nanofibers, and graphene.
6. The method for improving the stability of the negative plate as claimed in claim 1 or 5, wherein the mass ratio of the active material, the conductive agent, the mixed binder and the water in the step B is (85-90) to (3-6): (2-5): (90-235).
7. Root of herbaceous plantThe method for improving the stability of the negative electrode sheet according to claim 1, wherein the coating method in the step D is a doctor blade method, a transfer coating method or a squeeze coating method, and the coating areal density is 70-150g/m2。
CN202110593159.9A 2021-05-28 2021-05-28 Method for improving stability of negative plate Active CN113380985B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202110593159.9A CN113380985B (en) 2021-05-28 2021-05-28 Method for improving stability of negative plate

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202110593159.9A CN113380985B (en) 2021-05-28 2021-05-28 Method for improving stability of negative plate

Publications (2)

Publication Number Publication Date
CN113380985A CN113380985A (en) 2021-09-10
CN113380985B true CN113380985B (en) 2022-06-14

Family

ID=77574782

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202110593159.9A Active CN113380985B (en) 2021-05-28 2021-05-28 Method for improving stability of negative plate

Country Status (1)

Country Link
CN (1) CN113380985B (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115260943A (en) * 2022-07-14 2022-11-01 向能新型材料科技(河北)有限公司 Preparation method of carboxymethyl cellulose ammonium aqueous adhesive
CN117293314B (en) * 2023-09-25 2024-04-12 浙江煌能新能源科技有限公司 Adhesive for improving electrical property of silicon-based negative electrode, battery negative electrode and application

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100537613B1 (en) * 2003-06-20 2005-12-19 삼성에스디아이 주식회사 Anode composition of lithium battery, and anode and lithium battery employing the same
JP2005347197A (en) * 2004-06-07 2005-12-15 Fuji Xerox Co Ltd Battery and power generation method
KR101460774B1 (en) * 2013-01-15 2014-11-17 강원대학교산학협력단 Negative active material for rechargeable lithium battery, method of preparing the same, and negative electrode and rechargeable lithium battery including the same
CN106159271B (en) * 2015-04-22 2019-04-23 北京有色金属研究总院 A kind of lithium ion battery electrode for being cross-linked in situ polymeric binder and its preparation
CN108933245B (en) * 2018-07-19 2021-07-09 西安交通大学苏州研究院 Silicon-based negative electrode material and preparation method thereof

Also Published As

Publication number Publication date
CN113380985A (en) 2021-09-10

Similar Documents

Publication Publication Date Title
CN113380985B (en) Method for improving stability of negative plate
CN106531964B (en) Aqueous binder for sulfur positive electrode and application thereof
CN105702963B (en) A kind of application of carboxymethyl chitosan self-crosslinking polymer in lithium ion battery silicium cathode
CN108630462B (en) Nanofiber-based integrated thin film supercapacitor and preparation method thereof
CN105024044A (en) Preparation method of high-capacity silica-powder-doped lithium battery anode slurry
CN109560254A (en) A kind of lithium battery electrode plate and preparation method thereof
CN109698354B (en) Binder, negative electrode slurry using binder, and preparation method and application of negative electrode slurry
CN108232109B (en) Application of konjac glucomannan in adhesive
CN108649228B (en) Binder for silicon-based negative electrode of lithium ion battery, negative electrode and preparation method
CN104993110B (en) A kind of preparation method of composite negative electrode material of lithium ion battery
CN105206790A (en) Preparation method for lithium battery anode slurry doped with tin powder
CN111785915B (en) Low-crystallization-degree coating material and preparation method thereof, negative electrode material and lithium battery negative electrode
CN113363485B (en) Negative electrode slurry of lithium battery and preparation method thereof
CN113054193B (en) Silicon-based negative electrode self-repairing polymer binder and preparation method and application thereof
CN117038991A (en) Silicon-based negative electrode binder with topological three-dimensional structure, negative electrode sheet, preparation method of negative electrode sheet and battery
CN115064697A (en) Application of modified polyacrylonitrile, binder, negative plate and lithium ion battery
CN111769287B (en) Aqueous adhesive for battery, application of aqueous adhesive, lithium ion battery positive electrode material, lithium ion battery positive electrode sheet and lithium ion battery
CN111029528B (en) Lithium battery slurry and lithium battery pole piece
CN108695508B (en) High-energy lithium battery negative electrode slurry and preparation method thereof
CN113658743A (en) Carbon dot composite conductive agent and preparation method and application thereof
CN113755042A (en) Titanium dioxide coating and preparation method and application thereof
CN112290011A (en) Preparation method of water-based lithium ion battery positive active material slurry and positive plate
CN107749466B (en) Lithium battery with water-based negative electrode and preparation method thereof
CN110931748A (en) Self-repairing hydrogel, silicon-based anode material, preparation method of silicon-based anode material and lithium battery
CN114220973B (en) Adhesive, preparation method and application thereof

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
TA01 Transfer of patent application right
TA01 Transfer of patent application right

Effective date of registration: 20211116

Address after: 311215 No. 855, Jianshe Second Road, economic and Technological Development Zone, Xiaoshan District, Hangzhou City, Zhejiang Province

Applicant after: Wanxiang 123 Co., Ltd

Address before: 311215 No. 855, Jianshe Second Road, Xiaoshan Economic and Technological Development Zone, Xiaoshan District, Hangzhou City, Zhejiang Province

Applicant before: Wanxiang 123 Co., Ltd

Applicant before: Wanxiang Group Co., Ltd

GR01 Patent grant
GR01 Patent grant