Negative electrode sheet and lithium ion battery comprising same

Abstract

The invention provides a negative electrode sheet and a lithium ion battery comprising the same. According to the negative electrode sheet disclosed by the invention, a first negative electrode activematerial layer and a second negative electrode active material layer are respectively coated on a negative electrode current collector through a double-layer coating technology, wherein the first negative electrode active material layer is positioned between the second negative electrode active material layer and the negative electrode current collector, the first negative electrode active material layer is made of a first negative electrode active material with a relatively large heat conductivity coefficient, the first negative electrode active material with the relatively large heat conductivity coefficient is used so as not to easily accumulate heat and so as to reduce negative electrode polarization and effectively improve the electrode energy density, the surface of the second negative electrode active material layer is in contact with an electrolytic solution, the surface heat dissipation is relatively simple, the migration rate of lithium ions can be improved by proper heat, and the migration rate of the lithium ions can be promoted by using the second negative electrode active material with a smaller heat conductivity coefficient under the condition of ensuring that the heat cannot be locally gathered.

Description

technical field [0001] The invention belongs to the technical field of polymer lithium ion batteries, and in particular relates to a negative electrode sheet and a lithium ion battery including the negative electrode sheet. Background technique [0002] At present, lithium-ion batteries are developing rapidly in the fields of high energy density and fast charging. At the same time, the safety performance of lithium-ion batteries has also attracted much attention. When the lithium-ion battery is rapidly charged or overcharged, if the thermal conductivity of graphite on the negative electrode sheet is insufficient, heat accumulation is likely to occur, and the local lithium ion diffusion rate does not match the intercalation rate, resulting in large local polarization and prone to local lithium precipitation. Safety problems arise; if the thermal conductivity of graphite is large, the corresponding volume density will be large, and fast charging performance cannot be taken int...

AI Technical Summary

Problems solved by technology

When the lithium-ion battery is rapidly charged or overcharged, if the thermal conductivity of graphite on the negative electrode sheet is insufficient, heat accumulation is likely to occur, and the local lithium ion diffusion rate does not match the intercalation rate, resulting in large local polarization and prone to local lithium precipitation. Safety problems arise; if the thermal conductivity of graphite is large, the corresponding volume density will be large, and fast charging performance cannot be taken into account while satisfying high energy density and safety

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