Hard carbon-silicon carbon composite material, preparation method thereof and lithium ion battery

Abstract

The invention provides a hard carbon-silicon carbon composite material, a preparation method thereof and a lithium ion battery, and relates to the technical field of lithium batteries. The hard carbon-silicon carbon composite material is structurally characterized in that graphite is used as a framework, hard carbon coats nano silicon, soft carbon coats graphite and hard carbon, and graphite and hard carbon are connected through soft carbon. The preparation method comprises the steps of forming a suspension from a soluble polymer material, a dispersing agent and nano silicon, and removing a solvent to obtain mixture powder; heating and carbonizing the mixture powder; and uniformly mixing the carbonized powder with graphite and asphalt, adding the powder into a high-temperature coating reaction kettle, heating, carbonizing, and screening to obtain the hard carbon-silicon carbon composite material. According to the hard carbon-silicon carbon composite material, the preparation method ofthe hard carbon-silicon carbon composite material and the lithium ion battery, the graphite framework, the multi-structure material taking the graphite framework, hard carbon-coated nano silicon and soft carbon as a binder and a coating layer is low in expansion rate, and the cycle life is prolonged.

Description

technical field [0001] The invention relates to the technical field of lithium batteries, in particular to a hard carbon-silicon-carbon composite material, a preparation method thereof, and a lithium ion battery. Background technique [0002] With the development of battery technology, lithium-ion batteries are widely used in the fields of 3C products, power devices and energy storage equipment because of their advantages such as high specific capacity, high working voltage, good safety, long life, and no memory effect. In recent years, with the continuous improvement of electronic products, vehicle-mounted and energy storage equipment for miniaturization, light weight, multi-function, and long-term driving, the requirements for high energy density, high rate performance, and long cycle life of lithium-ion batteries constantly improving. [0003] As one of the four core components of the battery, the negative electrode material plays a key role in the overall performance of...

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Problems solved by technology

[0006] The problem solved by the present invention is that when nano-silicon is used as the negative electrode material, the charging process leads to a large degree of expansion, and the silicon-carbon composite material combined with graphite cannot eliminate the charging expansion, and there are a large number of exposed nano-silicon particles on the surface of the composite material. The continuous reaction of the liquid forms an SEI film, which leads to the problem of insufficient electrolyte at the end of the battery cycle.

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