CN-122011974-A - Polyacrylic acid-cellulose nanocrystalline composite binder and preparation method and application thereof

Abstract

The invention discloses a polyacrylic acid-cellulose nanocrystalline composite binder, and a preparation method and application thereof. The polyacrylic acid-cellulose nanocrystalline composite binder comprises polyacrylic acid, polar group modified cellulose nanocrystalline and water, wherein the polar group modified cellulose nanocrystalline is at least one of carboxylated cellulose nanocrystalline and sulfoacid-carboxylated cellulose nanocrystalline. The polyacrylic acid-cellulose nanocrystalline composite binder has the advantages of large binding force, good chemical stability, strong ion/electron transmission capability and the like, can effectively improve the cycle life and the first coulomb efficiency of a lithium ion battery when being used as a negative electrode material binder, has the advantages of simple preparation method, mild reaction condition, low production cost, safety and environmental protection, and is suitable for large-scale industrial production and application.

Inventors

• WANG CHAOYANG
• JIAO AO
• Cheng Dejian

Assignees

• 华南理工大学

Dates

Publication Date

20260512

Application Date

20260121

Claims (10)

1. 1. The polyacrylic acid-cellulose nanocrystalline composite adhesive is characterized by comprising polyacrylic acid, polar group modified cellulose nanocrystalline and water, wherein the polar group modified cellulose nanocrystalline is at least one of carboxylated cellulose nanocrystalline and sulfoacid-carboxylated cellulose nanocrystalline.
2. 2. The polyacrylic acid-cellulose nanocrystalline composite binder according to claim 1, wherein the mass ratio of polyacrylic acid to polar group modified cellulose nanocrystalline is 4-9:1.
3. 3. The polyacrylic acid-cellulose nanocrystalline composite binder according to claim 1 or 2, wherein the mass fraction of solute in the polyacrylic acid-cellulose nanocrystalline composite binder is 5% -10%.
4. 4. A method for preparing the polyacrylic acid-cellulose nanocrystalline composite binder according to any one of claims 1 to 3, characterized by comprising the following steps: 1) Preparing a polyacrylic acid solution and polar group modified cellulose nanocrystalline dispersion liquid: The preparation of polyacrylic acid solution, namely, dissolving acrylic acid and an initiator in water to carry out polymerization reaction to obtain polyacrylic acid solution; preparing polar group modified cellulose nanocrystalline dispersion liquid: dispersing the polar group modified cellulose nanocrystalline in water to obtain polar group modified cellulose nanocrystalline dispersion liquid; 2) And uniformly mixing the polyacrylic acid solution and the polar group modified cellulose nanocrystalline dispersion liquid to obtain the polyacrylic acid-cellulose nanocrystalline composite adhesive.
5. 5. The method of claim 4, wherein the polymerization reaction in step 1) is carried out at a temperature of 5-100 ℃ for 0.5-24 hours.
6. 6. The negative electrode plate is characterized by comprising a current collector and a negative electrode coating, wherein the preparation raw materials of the negative electrode coating comprise a negative electrode active material, a conductive agent and the polyacrylic acid-cellulose nanocrystalline composite binder according to any one of claims 1-3.
7. 7. The negative electrode sheet of claim 6, wherein the negative electrode coating is prepared from the following raw materials in percentage by mass: 85% -93% of negative electrode active material; 2% -10% of a conductive agent; 3-5% of polyacrylic acid-cellulose nanocrystalline composite binder.
8. 8. The negative electrode sheet according to claim 6 or 7, wherein the negative electrode active material is at least one of a silicon oxygen active material and a silicon carbon active material.
9. 9. The negative electrode sheet according to claim 6 or 7, wherein the conductive agent is at least one of carbon black, carbon nanotubes, graphene, and carbon fibers.
10. 10. A lithium ion battery comprising the negative electrode sheet according to any one of claims 6 to 9.

Description

Polyacrylic acid-cellulose nanocrystalline composite binder and preparation method and application thereof Technical Field The invention relates to the technical field of lithium ion batteries, in particular to a polyacrylic acid-cellulose nanocrystalline composite binder, and a preparation method and application thereof. Background Lithium Ion Batteries (LIBs) have the advantages of high energy density, longer cycle life, better environmental protection and the like, and are widely applied to the fields of portable electronic equipment, new energy automobiles, energy storage systems and the like. At present, most of lithium ion batteries adopt graphite as a negative electrode material, and the theoretical specific capacity (372 mAh/g) of the graphite is low, so that the specific capacity of the existing lithium ion batteries cannot meet the increasing practical application demands at all. The silicon-based negative electrode material is an emerging negative electrode material of a lithium ion battery, has theoretical specific capacity (which can reach about 4200 mAh/g) far higher than that of graphite, and has very wide application prospect. However, the silicon-based negative electrode material has huge volume change along with repeated intercalation/deintercalation of lithium ions in the charge and discharge process, so that the capacity and the cycle life of a lithium ion battery can be directly influenced, and the contact area between the silicon-based negative electrode material and electrolyte can be increased due to silicon particle breakage caused by the volume change of the silicon-based negative electrode material, so that more irreversible side reactions can occur, so that an uneven SEI layer is formed on the surface of the negative electrode material, and the service life of the lithium ion battery can be further shortened. At present, in order to ensure that the silicon-based negative electrode material can fully exert the characteristic of high theoretical specific capacity, researchers develop various negative electrode material binders for lithium ion batteries, for example, CN 101103475A discloses a negative electrode material binder for lithium ion batteries based on ethylene-acrylic acid copolymer and/or ethylene-methacrylic acid copolymer, but the molecular chains of the two copolymers contain a large amount of carboxyl groups, the compatibility with electrolyte is poor, the long-term cycling stability of the prepared lithium ion battery is poor, CN 113024898A discloses a negative electrode material binder for lithium ion batteries formed by compounding carrageenan and konjak gum, the binder has the advantages of simple preparation, safe raw materials, low price and the like, but the swelling rate of the two natural biomass polymers of the carrageenan and the konjak gum is higher, the problems of loose bonding network and reduced bonding force are easy to occur in the using process, the electrode structure deformation and the electrochemical performance are easy to occur finally, and CN 120349742A discloses a photocrosslinked polyacrylic acid-based water-based binder (AA)MEACMCS/DES), which not only can optimize the ion conduction path and dissipate mechanical stress, but also has intermolecular multiple forces, and can realize dynamic repair of electrode interface damage, but requires uv-initiated crosslinking, which has great limitation in practical application. In summary, the existing silicon-based negative electrode material binder also has the problems of poor mechanical property, low ion transmission rate, easy generation of unstable SEI film by irreversible side reaction with electrolyte, poor chemical stability, complicated curing operation and the like, and is difficult to completely meet the actual application demands. Therefore, the development of the lithium ion battery anode material adhesive with good mechanical property, good chemical stability and strong ion/electron transmission capability has very important significance. Disclosure of Invention The invention aims to provide a polyacrylic acid-cellulose nanocrystalline composite binder, and a preparation method and application thereof. The technical scheme adopted by the invention is as follows: The polyacrylic acid-cellulose nanocrystalline composite binder comprises polyacrylic acid (PAA), polar group modified cellulose nanocrystalline and water, wherein the polar group modified cellulose nanocrystalline is at least one of carboxylated cellulose nanocrystalline (CNC-MY) and sulfoacid-carboxylated cellulose nanocrystalline (CNC-ML). Preferably, the mass ratio of the polyacrylic acid to the polar group modified cellulose nanocrystals is 4-9:1. Preferably, the mass fraction of the solute in the polyacrylic acid-cellulose nanocrystalline composite binder is 5% -10%. The preparation method of the polyacrylic acid-cellulose nanocrystalline composite binder comprises the following steps: 1) Preparing a polyacrylic acid solu