A kind of preparation method of high-capacity composite negative electrode material

Abstract

The invention discloses a preparation method of a high-capacity composite negative electrode material. Calcining sucrose and water-soluble phenolic resin in a protective atmosphere at a temperature of 550-850°C for 5-10 hours, and obtaining amorphous carbon after cooling; lithium titanate , Natural graphite and amorphous carbon are placed in a high-speed mixer according to the mass ratio of 1:8-120:0.1-50, and mixed for 1-8h to obtain a mixture A; the mixture A is placed in a protective atmosphere at a temperature of 2200-2900°C Calcination for 3-10 hours, and mixture B is obtained after cooling; the mixture B compressed powder is filled into the mold, high-frequency electromagnetic vibration makes it dense, and after sealing, vacuumize, then put it into a high-pressure container with water or oil, pressurize to 80-250MPa, heated to 120-250°C, kept under pressure for 8-30h, cooled to obtain mixture C, and then placed in a pulverizer for crushing and spheroidizing to obtain a spherical powder with D50=10-80μm. The composite negative electrode material prepared by the invention has a large tap density, can reduce side reactions, is beneficial to increase battery capacity, and improves low-temperature charging performance of the battery.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a preparation method of a high-capacity composite negative electrode material. Background technique [0002] Carbon materials have the advantages of low chemical potential, good cycle performance, low price, and environmental friendliness, and are currently the most ideal and commonly used anode materials for lithium-ion batteries. Among carbon materials, compared with soft carbon and hard carbon, graphite materials have obvious advantages in terms of specific capacity, discharge platform and cost. Among them, natural graphite has the advantages of high specific capacity and low price, but it has a large initial irreversible capacity, poor cycle performance and poor rate performance. In order to overcome the defects of natural graphite, improve the electrochemical performance of carbon anode materials, and reduce the production cost. Among them, carbon / graphite ma...

AI Technical Summary

Problems solved by technology

However, the problem with the carbon / graphite negative electrode is that the first charge will form a solid electrolyte film (SEI) on the surface of the carbon particles, resulting in a loss of battery capacity, and the amount of SEI film formation increases with the increase in the number of charge-discharge cycles, and the internal impedance of the battery increases. , specific energy and power performance decrease