Negative plate as well as preparation method and application thereof

Abstract

The invention relates to the technical field of batteries, in particular to a negative plate and a preparation method and application thereof. The negative electrode plate comprises a negative electrode current collector, a first negative electrode active layer and a second negative electrode active layer, the negative electrode current collector comprises a negative electrode current collector substrate and a carbon material layer arranged on at least one side surface of the negative electrode current collector substrate, a first negative electrode active layer is arranged on the surface, far away from the negative electrode current collector substrate, of the carbon material layer, and a second negative electrode active layer is arranged on the surface, far away from the negative electrode current collector, of the first negative electrode active layer; the first negative electrode active layer comprises a first negative electrode active material, a first binder and a first conductive agent, and the first negative electrode active material comprises a silicon-based negative electrode material doped with hetero atoms; the second negative electrode active layer comprises a second negative electrode active material and a second binder, and the second negative electrode active material comprises a hard carbon material doped with heteroatoms; the atoms comprise at least one of P, N, S, B and O. The negative plate has excellent fast charging performance.

Description

Technical field [0001] The present invention relates to the field of battery technology, in particular, to a negative electrode wafer and a preparation method and application thereof. Background [0002] In recent years, the sales of new energy vehicles have gradually increased, as a power source of lithium-ion batteries in all aspects of the performance is also increasingly demanding, of which, in order to solve the product "endurance and charging anxiety" problem, the new lithium-ion batteries need to have higher energy density and faster charging time. As the most mature negative electrode active material in the current industry, graphite's actual exertion capacity is basically close to the theoretical capacity, and it is difficult to meet the high energy density index. Based on the existing cathode main material and battery formulation system, the graphite mixed silicon-based anode helps to further improve the energy density of lithium-ion batteries, which can effectively so...

AI Technical Summary

Problems solved by technology

However, the inherent semiconductor properties of silicon materials limit the fast charging ability of its batteries. In addition, the difference in electron transfer efficiency between the two materials during charging and discharging will cause uneven current distribution in the negative electrode sheet, resulting in a potential breakthrough in local areas. The lower limit of 0V produces lithium deposition, which reduces the fast charging performance of the power battery and affects safety

[0003] Due to the different surface tension of the two material particles, the silicon-doped graphite negative electrode sheet has different adsorption capabilities for conductive carbon and binder, so it is easy to have uneven distribution of conductive carbon and unstable binder network during mixing and homogenizing coating. , resulting in unsatisfactory battery rate performance; due to the difference in the electrochemical deintercalation potential of graphite material and silicon material, the two different active material materials will have the problem of deintercalating lithium successively, and the current distribution in the negative electrode sheet will be very uneven. , prone to local metal lithium deposition, which in turn affects the safety of the battery; therefore, how to have high-rate characteristics of the pole pieces obtained from two different active materials has become an urgent technical problem to be solved.

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