Negative electrode of lithium ion battery and preparation method thereof

Abstract

The invention belongs to the field of materials of lithium ion batteries, and particularly relates to a negative electrode of the lithium ion battery and a preparation method thereof. The negative electrode of the lithium ion battery comprises a current collector and negative electrode paste for coating the current collector, wherein the negative electrode paste comprises the following dry ingredients by weight percent: 92-99% of active material and 1-8% of an adhesive; the active material is graphite or graphite alloy; the adhesive is waterborne multi-component copolymerization emulsion. The waterborne multi-component copolymerization emulsion is used for replacing conventional butadiene styrene rubber and serves as the adhesive for the lithium ion battery, so that the more excellent adhesive performance is realized in comparison with the adhesive performance of a conventional adhesive, and meanwhile, the prepared battery has prominently excellent performances such as good low temperature characteristics, low circulation expansion rate, good long cycling performance and relatively excellent processing characteristics; the negative electrode prepared by using the method has relatively small impedance and relatively good dynamic performance and is capable of effectively solving the problem of risk of separation of lithium in the lithium ion battery at low temperature; the prepared battery has the characteristics of safety, reliability and long cycle life.

Description

technical field [0001] The invention belongs to the field of lithium ion battery materials, and more specifically relates to a lithium ion battery negative electrode and a preparation method thereof. Background technique [0002] Since its commercialization, lithium-ion batteries have been widely used as power sources for various mobile devices due to their high energy density, high working voltage, no memory effect, long cycle life, and no pollution to the environment. The practical phase of the scale. [0003] The characteristics of lithium-ion batteries can be developed by improving the components of the battery. The performance of the battery depends on the electrodes, electrolyte and battery materials contained therein, while the characteristics of the electrodes depend on the active materials, current collectors and binders of the battery. The agent provides the adhesion between the battery active material and the current collector. When the binder provides a strong a...

AI Technical Summary

Problems solved by technology

[0004] At present, water-based negative electrode sheets of lithium-ion batteries generally use styrene-butadiene rubber (SBR) as a binder, and the solubility parameters of such substances are in the range of 16-18 (J / cm 3 ) 1 / 2 , and the solubility parameter of the current electrolyte system is 20-26 (J / cm 3 ) 1 / 2 The gap is large, and the conductivity of lithium ions in this type of material is poor

When the coating weight increases, the kinetic performance of batteries prepared using such substances as binders will further deteriorate at low temperatures, which has severely restricted the application of lithium-ion batteries at low temperatures.

In addition, the brittleness of the pole piece is generally too strong in the current production process of the lithium-ion battery negative pole piece, which affects the compaction density of the negative pole piece.