Lithium ion battery positive electrode slurry, preparation method thereof and lithium ion battery

Abstract

The invention relates to lithium ion battery positive electrode slurry, a preparation method thereof and a lithium ion battery. The positive electrode slurry comprises a positive electrode active substance, a solvent, a composite binder, a composite conductive agent and a dispersing agent, wherein the composite conductive agent is a mixture composed of a conductive agent A and a conductive agent B; the conductive agent A is a conductive agent capable of forming a point-to-point conductive network; the conductive agent B is a conductive agent capable of forming a point-to-line or surface-contact conductive network; and the conductive agent A and the conductive agent B respectively account for 80-90% and 10-20% of the total weight of the conductive agent. According to the method disclosed bythe invention, the positive electrode slurry is processed and modified by changing the adding sequence of different substances in the positive electrode slurry, adjusting the stirring time, the stirring speed and the proportioning ratio and using the dispersing agent, the positive electrode slurry which enables all the components to be uniformly mixed and is relatively good in dispersion, moderate in viscosity and relatively small in fineness can be prepared, and the positive electrode slurry can improve the processing performance of the lithium battery and also can keep the battery to have excellent electrochemical performance.

Description

technical field [0001] The invention relates to the field of lithium ion batteries, in particular to a lithium ion battery positive electrode slurry, a preparation method thereof, and a lithium ion battery. [0002] technical background [0003] The positive electrode is the most important part of the lithium-ion battery, which determines the core electrochemical performance of the battery. Therefore, a reasonable positive electrode slurry formulation and its preparation method are the primary conditions for the performance of the lithium-ion battery. [0004] Lithium-ion batteries generally include the main parts such as positive electrode sheet, negative electrode sheet, separator, electrolyte, etc. Among them, the preparation process of the existing positive electrode sheet is to mix the binder and the solvent to glue, and then add the conductive agent and the active agent to the glue. The materials are uniformly mixed to obtain a positive electrode slurry, and then the sl...

AI Technical Summary

Problems solved by technology

The dispersion of the positive electrode slurry is uneven, and it is easy to settle in the coating process after the stirring is completed, resulting in a significant drop in the viscosity of the positive electrode slurry, which affects the uniform coating of the positive electrode slurry on the positive electrode current collector, directly leading to the capacity of the lithium battery. problems such as poor capacity decay, fast capacity decay, and poor cycle performance; the fineness of the slurry is large, which is prone to the phenomenon of large particle agglomeration, and the large particle agglomeration will cause the positive electrode slurry to easily settle, resulting in easy viscosity of the positive electrode slurry Substantial changes occur, affecting the uniform coating of positive electrode slurry and the performance of lithium-ion batteries

[0005] After research, it is found that the dispersion of positive electrode slurry has a certain relationship with the selection of conductive agent and binder. In the prior art, a single conductive agent and / or a single binder is often used, and the use of a single conductive agent often cannot effectively collect Micro-current between active materials, active materials and current collectors, which ultimately affects the conductivity of lithium-ion batteries

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