The application of PVP in lithium battery!

PVP can be used as dispersing agent for lithium battery cathode material

PVP can be used as dispersing agent of lithium battery electrode and conductive material processing agent. According to the announcement of Xinxingyuan Company, the amount of PVP in the field of new energy battery is 1GWh, about 15 tons, mainly using industrial grade PVP K30.

Slurry is crucial in the production of lithium batteries. Seventy percent of the quality of the battery is related to the quality of the electrode, and seventy percent of the quality of the electrode is related to the quality of the slurry. Good slurry is equal to done 50% of the battery, which is the core work of battery manufacturing. Lithium ion battery slurry is basically composed of active substance, conductive agent, binder and solvent. In the electrode preparation section, material drying, sol and slurry directly determine the quality of the slurry.

Lithium cathode material is difficult to disperse uniformly in the homogenizing process, so dispersant needs to be added. The cathode materials of lithium battery mainly include lithium cobaltate, lithium manganate, lithium iron phosphate, etc. Due to their low conductivity, appropriate amount of conductive agents, such as graphene and carbon nanotubes, are often added in the preparation process of the battery to improve the conductivity of the cathode materials. However, ultra-fine lithium cathode materials, such as lithium iron phosphate, are difficult to disperse evenly in the homogenizing process due to their small particle size and large specific surface area, resulting in high viscosity or low solid content of the slurry, which leads to coating difficulties or even impossible. Therefore, the selection of dispersant is particularly important for the dispersion of lithium cathode slurry.

PVP is an ideal dispersing agent for lithium cathode slurry. PVP molecular structure contains strong polar lactam hydrophilic group and C-C long chain oil hydrophilic group, which can be well compatible with a variety of solvents, and can be coated on the surface of particles, forming a good dispersion through steric hindrance effect. Adding the appropriate amount of PVP into the lithium battery positive slurry can significantly improve the dispersion of the slurry, make the slurry from Newtonian fluid to non-Newtonian fluid, and stabilize the slurry viscosity to a lower level, which is conducive to reducing the impedance of the positive electrode and improving the performance of the battery.

PVP can be used as a processing aid for carbon nanotubes conductive agents

Carbon nanotubes (CNTS) can improve the energy density of lithium-ion batteries. Conductive paste is the paste formed by evenly dispersing the conductive agent in the solvent, while the carbon nanotube conductive agent is the paste formed by dispersing the carbon nanotube in the dispersing solvent. As a new type of lithium-ion battery conductive agent, carbon nanotube conductive agent can improve the conductivity of the battery, and the addition amount is 60%-70% less than the conventional carbon black conductive agent. At the same time, it can reduce the amount of adhesive, which has a significant effect on the energy density of lithium-ion battery.

PVP can significantly improve the dispersion properties of carbon nanotubes in water, organic solvents and other substrates. CNTs are light in weight, perfectly connected in hexagonal structure, and have many abnormal mechanical, electrical and chemical properties. Carbon nanotubes (CNTS) form bundles or become entangled with each other due to strong van der Waals forces between the tubes, resulting in agglomeration, which severely limits their mechanical, thermal and electrical applications. PVP is a kind of amphiphilic polymer with special structure. The pyrrolidone group is a hydrophilic group, and the main chain is a hydrophobic chain segment of C-C bond. It is oilophilic, so it can dissolve in water or alcohol, carboxylic acid, amine alkane and other organic solvents. The introduction of PVP, a polymer with amphiphilic structure, onto the surface of CNTs significantly improved the dispersion of CNTs in water, organic solvents and other substrates. The medium molecular weight PVP K25 and PVP K30 showed the best dispersion effect on the multi-walled carbon nanotubes. The slurry viscosity was low, showing the characteristics of nearly Newtonian fluid. The dispersed multi-walled carbon nanotubes particles were uniform, the average particle size was relatively small, and had good stability. The adsorption capacity is higher than that of low molecular weight PVP K17 and high molecular weight PVP K90, and has better steric hindrance modification effect on the surface of multi-walled carbon nanotubes, so that the multi-walled carbon nanotubes are almost single-root dispersion, and the entanglement phenomenon is significantly reduced.


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