Negative plate, preparation method of negative plate, and lithium ion battery

Abstract

The invention discloses a negative plate, a preparation method of the negative plate, and a lithium ion battery. The negative plate comprises a current collector and a coating structure, the coating structure is at least arranged on one side surface of the current collector, the coating structure comprises a first coating and a second coating, the first coating is located between the current collector and the second coating, the first coating is made of first slurry, the second coating is made of second slurry, and the particle size of the first slurry is smaller than that of the second slurry. According to the negative plate, the first slurry and the second slurry are simultaneously coated to form the coating structure, the coating thickness of the slurries is uniform, the resistance of the negative plate can be remarkably reduced, the peel strength can be improved, the particle size of the inner layer is smaller than that of the outer layer, the porosity of the surface layer of the negative plate can be remarkably improved, and the liquid absorption efficiency of the electrolyte of the negative plate is improved.

Description

technical field [0001] The invention relates to the technical field of batteries, in particular to a negative electrode sheet, a preparation method of the negative electrode sheet and a lithium ion battery. Background technique [0002] Lithium-ion batteries have the advantages of high operating voltage, high energy density, long cycle life and environmental protection, and are widely used in electric vehicles. With the development of electric vehicles, the requirements for the cruising range, charging speed and safety performance of electric vehicle batteries are getting higher and higher. It is imminent to develop a high-energy, high-power and safe lithium-ion battery. [0003] At present, one way to increase the energy density of the battery is to increase the mass percentage of the active material or increase the thickness of the pole piece to increase the mass percentage of the active material, but the design of the thick pole piece increases the gap between the bottom ...

AI Technical Summary

Problems solved by technology

[0003] At present, one way to increase the energy density of batteries is to increase the mass percentage of active materials or increase the thickness of the pole piece to increase the mass percentage of active materials, but the design of the thick pole piece increases the gap between the bottom active material and the electrolyte. The contact distance prolongs the migration path of lithium ions, so that during the charging and discharging process of the battery, lithium ions cannot reach the bottom of the pole piece smoothly and quickly, forming a large concentration polarization, which in turn causes the battery capacity to fail to function normally and the pole piece to peel off A series of problems such as strength decline, poor rate performance, low-temperature lithium precipitation, cycle capacity fading, etc.

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