Anode sizing agent, anode pole piece and lithium ion battery

Abstract

The invention provides an anode sizing agent, an anode pole piece and a lithium ion battery. The anode sizing agent comprises an anode active material, a conductive agent and a binding agent; the anode active material comprises a first anode active material grain of which pH value is not less than 11.5. The binding agent comprises fluorine-containing polymer. The anode sizing agent further comprises additive. The anode sizing agent has good mobility and stability, and can effectively solve the gel, jelly, and agglomeration problems during the processing of the anode pole piece, improving the production efficiency, ensuring the consistence of the lithium ion battery while improving the storage life and high-temperature circulatory stability of the lithium ion battery under the high voltage.

Description

technical field [0001] The invention relates to the technical field of batteries, in particular to a positive electrode slurry, a positive electrode sheet and a lithium ion battery. Background technique [0002] Compared with other traditional secondary batteries, lithium-ion batteries have many advantages such as small size, high voltage, and high energy density, and have made a series of great progress in the fields of consumer electronics such as mobile phones and notebooks. With the vigorous development of the new energy industry, more and more researchers are actively developing lithium-ion batteries with high power density, high cycle stability, and high safety, hoping to use them as power batteries for electric vehicles. Among the many positive electrode active materials used in lithium-ion batteries, layered lithium nickel cobalt manganese (NCM) and lithium nickel cobalt aluminum (NCA) are considered to be the future driving forces due to their high discharge capacit...

AI Technical Summary

Problems solved by technology

Such as increasing the sintering temperature or increasing the atmosphere purge, but this will lead to particle size increase or too much Li volatilization, resulting in insufficient lithium content in the positive electrode active material, and ultimately fail to achieve the designed performance

[0005] In addition, for NCM and NCA materials with high alkalinity (that is, high pH value), water washing or pickling is often used to reduce the pH of the surface, but water or acid is a strong polar substance, on the one hand, it will cause the positive active material The dissolution of certain ions on the surface, such as Li, Ni, Co, Mn, etc., will destroy the surface structure of the positive electrode active material. On the other hand, a small amount of residual water molecules will diffuse into the interior of the particle, which is not easy to remove. To completely eliminate it, it is necessary to Sintering at high temperature again will lead to the precipitation of a part of Li, forming a small amount of Li on the surface. 2 CO 3 and other substances, leading to lithium depletion in the bulk phase and changes in the surface structure

The second method is to strictly control the water content of each auxiliary material to the ppm level during stirring, and place the slurry at a lower ambient humidity, but this method is costly, and will greatly increase lithium in the absence of large-scale production capacity. The cost of ion batteries

The third method is to add cyclic ketones to improve the gel degree of the slurry during the stirring process. Adding cyclic ketones has the least impact on the performance of lithium-ion batteries, but cyclic ketones are highly carcinogenic and relatively Strong volatility will affect the safety of operators, so it has been gradually abandoned

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