A silicon negative electrode material and a negative electrode sheet coated with carbon nanotubes, a preparation method thereof and a lithium ion battery

Abstract

The invention relates to the field of lithium ion batteries, and discloses a silicon negative electrode material and a negative electrode sheet coated with carbon nanotubes, a preparation method thereof and a lithium ion battery. The preparation method of the silicon negative electrode material comprises the following steps: (1) dissolving polyethylene glycol, citric acid and/or citric acid monohydrate and transition metal salt in a solvent to obtain a precursor solution; (2) mixing the precursor solution with the silicon material, filtering, washing, and then drying under the condition of isolating air to obtain the precursor-coated silicon material; (3) heating the precursor-coated silicon material in an air atmosphere to 200-280 DEG C for sintering for 1.5-3.5 hour, naturally cooling toobtain MOx/Si composite pow; (4) heating the MOx/Si composite powder under the protection of inert gas and/or weak reducing gas to 400-800 DEG C for sintering for 1-5h. The silicon negative electrodematerial obtained by the method has stable electrochemical performance, can avoid damage to the structure of carbon nanotubes, has simple process, does not use flammable and explosive alkane as carbon source, and has high safety.

Description

technical field [0001] The invention belongs to the field of lithium-ion batteries, and in particular relates to a carbon nanotube-coated silicon negative electrode material, a negative electrode sheet, a preparation method thereof, and a lithium-ion battery. Background technique [0002] With the development of the new energy industry, people have put forward higher and higher requirements for lithium-ion batteries. Improving energy density and extending cycle life have become urgent problems for lithium-ion batteries. Traditional graphite anode materials have been difficult to meet the needs of the development of the new situation. Due to its high theoretical specific capacity (4200mAh / g), low potential for lithium intercalation and extraction, and abundant silicon reserves, silicon anode materials have become the most promising anode materials for next-generation lithium-ion batteries. However, silicon anode materials also have the following problems: 1. The huge volume ...

AI Technical Summary

Problems solved by technology

However, silicon anode materials also have the following problems: 1. The huge volume effect produced by silicon during the charge-discharge cycle can easily cause the pulverization of the material, and then separate from the current collector, resulting in a rapid decline in capacity and poor cycle performance; 2. Silicon itself is a semiconductor material, and its conductivity needs to be improved, so it needs to be doped with highly conductive substances; 3. During circulation, silicon will react with lithium hexafluorophosphate in the electrolyte, and it is difficult to form a stable SEI film, making the capacity retention rate and Coulombic inefficiency

Vapor deposition (CVD) has the advantages of low reaction temperature, simple equipment, and easy control of the reaction. However, due to the uneven distribution of carbon transported in the gas phase on the sample, the grown carbon nanotubes will appear unevenly distributed, making the sample The consistency is affected; moreover, this method requires the use of H 2 、CH 4 Inflammable and explosive gases, such as experimental safety hazards are worrying

Images