Silicon-carbon negative electrode, preparation method thereof, lithium ion battery and electric vehicle

Abstract

The invention discloses a silicon-carbon negative electrode, a preparation method thereof, a lithium ion battery and an electric vehicle, which relate to the technical field of the silicon-carbon negative electrode of the lithium ion battery. The silicon-carbon negative electrode comprises a negative electrode current collector, a coating and a silicon-carbon negative electrode material layer sequentially arranged on the surface of the negative electrode current collector; Coatings include: mesophase pitch, graphene and coating binder, mesophase pitch, graphene and binder mass ratio of 20-50:40-65: 1.5-10. The silicon-carbon negative electrode current collector of the present invention is coated with a mesophase pitch, The coating of graphene and binder can improve the conductivity and heat dissipation of silicon-carbon negative electrode, improve the cycle performance, safety and high current charging and discharging ability of lithium ion battery. The binder is PVDF of water system,and the adhesive between coating and negative electrode material PVDF of water system is synergistic to enhance the adhesion between coating and negative electrode material and further improve the cycle performance.

Description

technical field [0001] The invention relates to the technical field of silicon-carbon negative poles of lithium-ion batteries, in particular to a silicon-carbon negative pole, a preparation method thereof, a lithium-ion battery and an electric vehicle. Background technique [0002] The increase in the energy density of lithium-ion batteries puts forward higher requirements for the negative electrode material. At present, the theoretical capacity of the graphite negative electrode has reached more than 95%, and the application is close to its theoretical limit. Compared with graphite anode materials, silicon-based anode materials have obvious advantages in energy density, and their theoretical specific capacity can be as high as 4200mAh / g. Due to their abundant reserves and low lithium intercalation potential, silicon-based anode materials have become a hotspot in the research and application of anode materials. [0003] However, there are many problems to be solved urgently ...

AI Technical Summary

Problems solved by technology

[0004] 1. Silicon has a large volume effect in the process of intercalation and delithiation, and the high volume expansion rate makes the silicon particles pulverized severely during the cycle, and the capacity decays rapidly;

[0005] 2. Silicon is a semiconductor, and its conductivity is much worse than that of graphite anode, which greatly affects the first Coulombic efficiency and high-current charge-discharge capability of silicon-based lithium batteries.

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