In the complex system of lithium batteries, the performance of the cathode slurry plays a key role in the overall performance of the battery. As a special additive, polyvinylpyrrolidone (PVP) is gradually emerging and showing unique value in improving the performance of cathode slurry.

PVP is a non-ionic polymer compound, which is polymerized by N-vinylpyrrolidone under specific conditions. Its molecular structure is extremely unique, containing strong polar lactam hydrophilic groups and C-C long-chain lipophilic groups. This special structure gives PVP excellent solvent compatibility, making it miscible with a variety of solvents. At the same time, with the steric hindrance effect, PVP can form an effective coating on the surface of particles, which lays the foundation for its application in lithium battery cathode slurry.

In lithium battery cathode slurry, PVP mainly plays an important role as a dispersant. There are many types of lithium battery cathode materials, such as lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, etc., and conductive agents such as graphene and carbon nanotubes are often added to improve conductivity. However, ultrafine cathode materials such as lithium iron phosphate have small particle size and large specific surface area, which makes it extremely difficult to disperse them evenly during the homogenization process, which can easily cause high viscosity or low solid content of the slurry, seriously affecting the subsequent coating operation. The addition of PVP can effectively improve this situation. Through its special molecular structure, PVP is adsorbed on the surface of cathode material and conductive agent particles, and uses steric hindrance to prevent particle agglomeration, achieve uniform dispersion, and significantly optimize the dispersibility of the slurry.

The application of PVP brings many benefits to the performance improvement of lithium batteries. The appropriate addition of PVP can transform the cathode slurry from a Newtonian fluid to a non-Newtonian fluid, and the viscosity is stably maintained at a low level. This change has a significant effect on reducing the cathode impedance, thereby improving the overall performance of the battery. Taking carbon nanotube conductive agent as an example, PVP can significantly improve its dispersion characteristics in water, organic solvents and other matrices. Studies have shown that medium molecular weight PVP K25 and PVP K30 have the best dispersion effect on multi-walled carbon nanotubes, which can reduce the viscosity of the slurry, reduce the resistivity, disperse the multi-walled carbon nanotubes almost in a single strand, and greatly reduce the entanglement phenomenon. In terms of improving the energy density of lithium-ion batteries, PVP helps carbon nanotube conductive agents to play a greater role, reduce the amount of conductive agents and adhesives, and improve the overall performance of batteries.

With the rapid development of the new energy industry, the performance requirements of lithium batteries continue to rise. As a key additive for lithium battery cathode slurry, PVP is expected to make greater breakthroughs in improving battery energy density, cycle life and safety in the future. At the same time, the development of high-quality and high-performance PVP products and the optimization of their application process in cathode slurry will become an important direction to promote the progress of the lithium battery industry and inject new vitality into the development of new energy technologies.