Lithium ion battery silicon carbide composite anode material and preparation method thereof

Abstract

The invention discloses a lithium ion battery silicon carbide composite anode material and a preparation method thereof and aims to solve the technical problem of improving the cycling stability of a silicon carbide cathode. The lithium ion battery silicon carbide composite anode material consists of the following components in percentage by mass: 85 to 75 percent of graphite and 15 to 25 percent of silica particles, wherein the nano silica particles are dispersed on a graphite carrier to form a nuclear shell structure and are 5 to 16 mum in granularity. The preparation method comprises the following steps of: preparing a graphite dispersing agent and a silicon grinding dispersing agent; adding the silicon grinding dispersing agent into the graphite dispersing agent; and performing thermal treatment. When the method is compared with the prior art, silicon atoms are dispersed on a graphite atomic nucleus by a cation-anion charge absorption method, so that the silicon atoms can uniformly wrap the surface of the graphite, the dispersity of silicon is effectively improved in a silicon carbide composite material preparing process, the initial efficiency and the cycling stability of the silicon carbide composite anode material are improved, and a battery using the material as an anode material has relatively high safety, multiplying power performance and cycle performance.

Description

technical field [0001] The invention relates to a lithium ion battery negative electrode material and a preparation method thereof, in particular to a silicon-carbon composite material and a preparation method thereof. Background technique [0002] Due to the rapid development and wide application of various portable electronic devices and electric vehicles, there is an urgent need for lithium-ion batteries with high energy and long cycle life. At present, graphite, the main negative electrode material of commercial lithium-ion batteries, has low theoretical capacity (372mAh / g) and poor high-rate charge and discharge performance, which limits the further improvement of lithium-ion battery energy. So far, silicon has the highest theoretical capacity among anode materials. Li and Si form an alloy Li x Si (0<x≤4.4), it is generally believed that at room temperature, the lithium-rich product produced by the alloying of silicon anode and lithium is mainly Li 3.75 Si phase, ...

AI Technical Summary

Problems solved by technology

However, the number of surface atoms, specific surface area and surface energy of nano-silicon will increase rapidly during charging and discharging. There are no adjacent atoms around the surface atoms, and there are many dangling bonds. It has unsaturated properties and is easy to combine with other atoms, so it has great Chemically active, prone to agglomeration during placement and use

From the existing research results, researchers basically prepare silicon-carbon composites according to the embedding model, coating model, and molecular contact model; but the existing methods are difficult to distribute silicon in carbon or evenly coat the carrier. However, it is still not possible to completely avoid the slow destruction of the silicon structure during the reversible charge-discharge process.

Images