Search

CN-121975454-A - Preparation method and application of SBR-free full-cellulose-based negative electrode binder

CN121975454ACN 121975454 ACN121975454 ACN 121975454ACN-121975454-A

Abstract

The invention discloses a preparation method and application of an SBR-free full-cellulose-based negative electrode binder, and belongs to the technical field of lithium ion battery binders. The invention is used for solving the technical problems that the CMC/SBR emulsion used as the negative electrode binder of the lithium ion battery in the prior art has poor adhesion, poor mechanical strength and chemical stability, expensive raw materials and environmental protection. A preparation method of the SBR-free all-cellulose-based negative electrode binder comprises the following steps of adding cellulose subjected to TEMPO oxidation into deionized water, homogenizing under high pressure to obtain TOCNF suspension, and mixing CMC powder with TOCNF suspension to obtain the SBR-free all-cellulose-based negative electrode binder with strong adhesiveness and mechanical properties. The prepared SBR-free all-cellulose-based negative electrode binder is applied to preparation of lithium ion battery negative electrode plate materials. The finally prepared lithium ion battery has the advantages of good electrochemical performance and long cycle life.

Inventors

  • WANG HUIQING
  • LI XIANG
  • DING GUODONG

Assignees

  • 合肥工业大学

Dates

Publication Date
20260505
Application Date
20260202

Claims (10)

  1. 1. The preparation method of the SBR-free full-cellulose-based negative electrode binder is characterized by comprising the following steps of: s1, adding cellulose oxidized by TEMPO into deionized water, uniformly mixing to obtain slurry, homogenizing the slurry at high pressure, and adding deionized water to obtain TOCNF suspension; s2, mixing CMC powder with TOCNF suspension, dissolving at 15-25 ℃ and uniformly mixing for 4-8 hours to obtain the SBR-free all-cellulose-based negative electrode binder.
  2. 2. The method for preparing the SBR-free full-cellulose-based negative electrode binder according to claim 1, wherein in step S1, the method for preparing the TEMPO oxidized cellulose comprises the steps of: Adding TEMPO and NaBr into deionized water in turn, stirring at 15-25 ℃ until TEMPO and NaBr are completely dissolved to obtain a mixture, adding dry purified cellulose fiber raw materials into the mixture, mixing and dispersing, adding NaClO solution to form a reaction system, adjusting the pH value of the reaction system to 10.5-11, reacting for 3-7h to obtain a product, centrifuging the product, and washing the product with deionized water for 4-8 times to obtain the cellulose oxidized by TEMPO.
  3. 3. The preparation method of the SBR-free full-cellulose-based negative electrode binder, which is characterized in that the effective chlorine content in NaClO solution is 6-14wt%, and the dosage ratio of TEMPO, naBr, deionized water, dried purified cellulose fiber raw material and NaClO solution is 0.8g:5g:4000mL-4500mL:45-50g:370-375g.
  4. 4. The preparation method of the SBR-free full-cellulose-based negative electrode binder according to claim 1, wherein in the step S1, the solid content of the slurry is 0.8-1.6wt%, the high-pressure homogenizing pressure is 150-200Mpa, and the number of times of high-pressure homogenizing is 6-10.
  5. 5. The method for preparing a SBR-free all-cellulose-based negative electrode binder according to claim 1, wherein in step S2, the CMC powder has a viscosity of 1200 to 4500 mPa ·s, a weight average molecular weight of 300000 to 700000, a substitution degree of 0.8 to 1.4, a purity of 99.5% or more, an aspect ratio of TOCNF of 200 to 2000, a diameter of 1 to 20nm, and a carboxyl content of 1.3 to 2.5mmol/g in a 1wt% aqueous solution at 25 ℃.
  6. 6. The preparation method of the SBR-free full-cellulose-based negative electrode binder, according to claim 1, wherein the mass ratio of CMC powder to TOCNF in TOCNF suspension is 10:a, wherein a is equal to or less than 1 and equal to or less than 8, and a is an integer.
  7. 7. The method for preparing a non-SBR full-cellulose-based negative electrode binder according to claim 6, wherein the mass ratio of CMC powder to TOCNF in TOCNF suspension is 10:a, wherein a is 2≤6 and a is an integer.
  8. 8. Use of a SBR-free full cellulose based negative electrode binder prepared by the method for preparing a SBR-free full cellulose based negative electrode binder according to claim 7 in a negative electrode material of a lithium ion battery.
  9. 9. The use according to claim 8, wherein the preparation method of the lithium ion battery negative electrode sheet material comprises the following steps: And (3) adding the SBR-free all-cellulose-based negative electrode binder, the conductive agent and the graphite material into a stirring kettle for mixing and dispersing to obtain negative electrode slurry, coating the negative electrode slurry on a current collector, carrying out vacuum preheating and vacuum drying to obtain a lithium ion battery negative electrode plate material, and assembling the battery.
  10. 10. The application of the SBR-free full-cellulose-based negative electrode binder in the lithium ion battery negative electrode plate material, according to claim 9, is characterized in that the mass ratio of the graphite material to the SBR-free full-cellulose-based negative electrode binder to the conductive agent is 90-95:2.5-5:2.5-5, the mixing and dispersing rotating speed is 700-900r/min, the mixing and dispersing time period is 5-8h, the vacuum preheating temperature is 60-90 ℃, the vacuum preheating time period is 2-3h, the vacuum drying temperature is 60-90 ℃, the vacuum drying pressure is-0.1 MPa, and the vacuum drying time period is 12-14h.

Description

Preparation method and application of SBR-free full-cellulose-based negative electrode binder Technical Field The invention belongs to the technical field of lithium ion battery binders, relates to a lithium ion battery binder, and in particular relates to a preparation method and application of an SBR-free all-cellulose-based negative electrode binder. Background The performance of lithium ion batteries as efficient energy storage devices is highly dependent on the stability of the electrode structure. The graphite negative electrode material is the negative electrode material which is most widely applied and mature in the current lithium ion battery, wherein the binder system is a key auxiliary material for ensuring firm combination among the graphite negative electrode active material, the conductive agent and the current collector. At present, the industry commonly adds an equal proportion of SBR emulsion (styrene butadiene rubber emulsion) into a CMC (sodium carboxymethyl cellulose) adhesive to improve the brittleness of a graphite pole piece and increase the adhesion between the pole piece and a copper foil current collector. However, the compatibility between SBR and CMC mainly depends on physical mixing, lacks strong chemical bonding, and may cause peeling of electrode material due to unstable interface during charge and discharge. Patent application CN104600318A discloses a modified CMC and a gel battery thereof, wherein the used binder is a combination of the modified CMC and SBR, the solvent is deionized water, and fluorine-containing chains are introduced into the modified CMC to enhance the affinity and cohesiveness with SBR emulsion and coating materials. However, the imported SBR emulsion has the advantages of high price, short shelf life and limited mechanical strength, is difficult to effectively inhibit the volume change of graphite particles in the electrode circulation process, and is easy to cause the structural degradation of the electrode after long-term circulation. In addition, the SBR emulsion needs to be added after the CMC/graphite slurry is stirred, and the emulsion is easy to break under long-time high-speed shearing, so that the cohesiveness is reduced, and the process control difficulty is increased. In order to solve the technical limitations of CMC/SBR composite binders for negative electrodes, development of advanced binders replacing CMC/SBR is needed. In view of the technical drawbacks of this aspect, a solution is now proposed. Disclosure of Invention The invention aims to provide a preparation method and application of an SBR-free all-cellulose-based negative electrode binder, which are used for solving the technical problems that the mixture of CMC powder and SBR emulsion in the prior art is used as the negative electrode binder of a lithium ion battery, and has poor adhesion, poor mechanical strength and chemical stability, expensive raw materials and environmental protection. The aim of the invention can be achieved by the following technical scheme: the preparation method of the SBR-free full-cellulose-based negative electrode binder comprises the following steps of: s1, adding cellulose oxidized by TEMPO into deionized water, uniformly mixing to obtain slurry, homogenizing the slurry at high pressure, and adding deionized water to obtain TOCNF suspension; s2, mixing CMC powder with TOCNF suspension, dissolving at 15-25 ℃ and uniformly mixing for 4-8 hours to obtain the SBR-free all-cellulose-based negative electrode binder. Further, in step S1, the preparation method of the TEMPO oxidized cellulose includes the following steps: Adding TEMPO (2, 6-tetramethyl piperidine-1-oxygen free radical) and NaBr into deionized water in turn, stirring at 15-25 ℃ until TEMPO and NaBr are completely dissolved to obtain a mixture, adding dry purified cellulose fiber raw materials into the mixture, mixing and dispersing, adding NaClO solution to form a reaction system, regulating the pH value of the reaction system to 10.5-11, reacting for 3-7 hours to obtain a product, centrifuging the product, and washing the product with deionized water for 4-8 times to obtain cellulose oxidized by TEMPO. Further, the purified cellulose raw material includes, but is not limited to, at least one of cotton source (refined linters, long linters, combed cotton), wood source (softwood pulp board, hardwood pulp board, bamboo pulp board), wheat straw/straw stalk cellulose purified cellulose raw material, sea squirt cellulose and fermentation bacterial cellulose source cellulose raw material. Further, the effective chlorine content in the NaClO solution is 6-14wt%, and the dosage ratio of TEMPO, naBr, deionized water, dried purified cellulose fiber raw material and NaClO solution is 0.8g:5g:4000mL-4500mL:45-50g:370-375g. Further, in the step S1, the solid content of the slurry is 0.8-1.6wt%, the high-pressure homogenizing pressure is 150-200Mpa, and the times of high-pressure homogenizing are 6-10 time