Negative electrode sheet and lithium ion battery including negative electrode sheet

Abstract

The embodiment of the application provides a negative electrode sheet and a lithium ion battery including the negative electrode sheet. The negative electrode sheet includes a negative current collector and a negative active material layer disposed on the negative current collector, wherein the negative active material layer includes a negative active material and a dispersant, the mass ratio of the negative active material and the dispersant is greater than or equal to 18.74, and the dispersant includes lithium carboxymethyl cellulose. The negative electrode sheet, while not losing the energydensity of the lithium ion battery, not affecting the cycle life of the lithium ion battery and not causing cyclic expansion, greatly reduces the DC resistance of the lithium ion battery and the charge transfer resistance of an interface, and avoids lithium deposition of the lithium ion battery during cyclic charge / discharge process.

Description

technical field [0001] Embodiments of the present application relate to the battery field, and more specifically, to a negative electrode sheet and a lithium ion battery including the negative electrode sheet. Background technique [0002] When the lithium-ion battery is charged rapidly or at low temperature, if the negative electrode kinetics of the lithium-ion battery is insufficient, it will cause Li + The negative electrode is enriched and electrons are obtained on the surface of the negative electrode active material layer to precipitate on the surface of the negative electrode in the form of lithium dendrites. The formation of lithium dendrites will deteriorate the cycle life of lithium-ion batteries, and there is a risk of piercing the separator, causing safety hazards . [0003] In order to avoid the phenomenon of lithium analysis, the following methods are usually used at present: one is to reduce the compaction density of the pole piece, improve the kinetic perfor...

AI Technical Summary

Problems solved by technology

[0002] When the lithium-ion battery is charged rapidly or at low temperature, if the negative electrode kinetics of the lithium-ion battery is insufficient, it will cause Li + The negative electrode is enriched and electrons are obtained on the surface of the negative electrode active material layer to precipitate on the surface of the negative electrode in the form of lithium dendrites. The formation of lithium dendrites will deteriorate the cycle life of lithium-ion batteries, and there is a risk of piercing the separator, causing safety hazards

[0003] In order to avoid the phenomenon of lithium analysis, the following methods are usually used at present: one is to reduce the compaction density of the pole piece, improve the kinetic performance of the lithium-ion battery, improve the rate performance, and improve the analysis of lithium, but lose the energy density of the lithium-ion battery; The second is to use nitrile or ester-modified negative electrode binders to improve lithium analysis, but it will increase the cycle expansion of lithium-ion batteries; the third is to increase the proportion of low-viscosity solvents in the electrolyte to improve low-temperature lithium analysis, but often It will reduce the conductivity of the electrolyte and worsen the phenomenon of lithium precipitation at room temperature, and the low-viscosity solvent generally has a lower boiling point, which will also deteriorate the high-temperature storage performance of lithium-ion batteries

[0004] Therefore, although the above methods can improve lithium analysis to varying degrees, they will also bring some defects, which are not completely satisfactory.

Images