Lithium ion battery cathode material and preparation method thereof, and lithium ion battery

Abstract

The invention discloses a lithium ion battery cathode material and a preparation method thereof, and a lithium ion battery. The preparation method of the material comprises the following steps: 1)mixing metal and SiOx to obtain a mixture, wherein, metal is one or more from lithium, sodium, potassium, calcium, magnesium and titanium, and x is greater than 0 and less than 2.0; and 2)under inert atmosphere or vacuum condition, roasting the mixture for 0.5-24 hours at 300-1000 DEG C to obtain the cathode material. By reacting the metal and SiOx, active oxygen content in the cathode material is reduced, and the obtained cathode material also comprises the above metal oxide. According to the invention, active oxygen content in the cathode material is reduced, primary efficiency for charge and discharge can be greatly increased, the above metal oxide in the cathode material can alleviate volume expansion of silicon in the cathode material at certain degree, and thereby the volume effect of the whole cathode material is reduced.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a lithium ion battery negative electrode material, a preparation method thereof, and a lithium ion battery. Background technique [0002] At present, the lithium-ion batteries used in production mainly use graphite-based negative electrode materials, but the theoretical lithium intercalation capacity of graphite is 372mAh / g, but it has actually reached 370mAh / g. Therefore, there is almost no room for improvement in the capacity of graphite-based negative electrode materials. [0003] In the past ten years, a variety of new high-capacity and high-rate negative electrode materials have been developed, among which silicon-based materials have become a research hotspot due to their high mass specific capacity (the theoretical specific capacity of silicon is 4200mAh / g). The material is accompanied by serious volume expansion and contraction during the lithium...

AI Technical Summary

Problems solved by technology

[0003] In the past ten years, a variety of new high-capacity and high-rate negative electrode materials have been developed, among which silicon-based materials have become a research hotspot due to their high mass specific capacity (the theoretical specific capacity of silicon is 4200mAh / g). The material is accompanied by serious volume expansion and contraction during the process of intercalation and delithiation, which leads to the powdering and falling off of the electroactive material on the electrode, and finally leads to capacity fading

In order to overcome the specific capacity fading of silicon-based negative electrode materials, a common method is to uniformly disperse nano-silicon particles into other active or inactive material matrices (such as Si-C, Si-TiN, Si-SiO 2 etc.), such as using SiO as the lithium intercalation active material, using pitch as the carbon precursor, ball-milling SiO and pitch and sintering at 500-1000°C, on the one hand, transforming the pitch into amorphous carbon and covering the surface of SiO particles, To enhance its conductivity, on the other hand, SiO disproportionates into a composite structure in which silicon dioxide wraps nano-silicon particles at high temperature. The transition layer of silicon oxide is thicker, and the main component of the transition layer is SiO x (0﹤x﹤2.0), because it is not a stable crystal structure, SiO x The oxygen in (0﹤x﹤2.0) will combine with lithium ions to form electrochemically inert Li 2 O, the above-mentioned silicon-based negative electrode materials are temporarily difficult to be applied to lithium-ion batteries due to their low efficiency for the first time