A kind of sulfur/nitrogen/silicon co-doped graphite composite negative electrode material and preparation method thereof

Abstract

The invention relates to a sulfur / nitrogen / silicon co-doped graphite composite negative electrode material and a preparation method thereof, belonging to the technical field of preparation of lithium ion battery materials. The technical solution is: (1) Weigh 1~5g of sulfur-containing organic compound and 1~5g of nitrogen-containing organic compound into 500g of organic solvent, stir evenly, add 100g of graphite into it and stir evenly, after filtering, transfer to the tube type In the furnace, under an inert atmosphere, heat up to 200-500°C and keep it warm for 1-6 hours, then cool down to room temperature in an inert atmosphere to obtain graphite composite material A; into the surface layer of the graphite composite material A, and then carbonized to obtain a sulfur / nitrogen / silicon co-doped graphite composite negative electrode material. The invention improves the specific capacity of the graphite material by doping sulfur in the graphite material, and improves the electrical conductivity of the sulfur through nitrogen doping; the expansion of the material can be reduced and the liquid absorption capacity of the material can be improved.

Description

technical field [0001] The invention relates to a sulfur / nitrogen / silicon co-doped graphite composite negative electrode material and a preparation method thereof, belonging to the technical field of preparation of lithium ion battery materials. Background technique [0002] As the market's requirements for the energy density of lithium-ion batteries increase, the anode materials used in lithium-ion batteries are required to have high specific capacity and cycle life. The graphite materials currently on the market have a low reversible capacity (theoretical capacity 372mAh / g), which limits its Increased energy density. Silicon-carbon anode materials have attracted the attention of researchers due to their high gram capacity and abundant resources, and have been used in high specific energy density lithium-ion batteries and other fields. However, their high expansion rate and conductivity deviation restrict their wide application. However, mixing and compounding graphite and...

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Problems solved by technology

For example, the patent (CN105576203A) discloses the graphene / silicon / carbon nanotube composite material and its preparation method and application. The preparation process is: add graphene powder and carbon nanotubes to the NMP solution, and disperse them evenly with ultrasonic vibration. , then add nano-silica powder, and disperse evenly through ultrasonic oscillation; dry, dry, and grind the obtained mixed solution to obtain a graphene / silicon / carbon nanotube composite material, but it has poor lithium ion conductivity and poor electronic conductivity. And its high expansion rate and other defects, and its method is single, while reducing the expansion rate, the electronic and ionic conductivity properties of the material have not been improved, which affects the comprehensive performance of the material; patent (application number: 201410515321.5) published A silicon-carbon-nitrogen composite negative electrode material and its preparation method are disclosed. The preparation method is to heat the mixture of silicon source and nitrogen source to 600-1000 °C at a heating rate of 0.5-10 °C / min under an argon atmosphere. ℃, keep warm for 3-15h, cool down to room temperature, and obtain nitrogen-doped silicon-based materials

The above preparation method is mainly prepared from silicon source, nitrogen source and carbon source. However, although the silicon material has a high capacity, its high expansion rate affects its cycle performance, and at the same time, the large specific surface area of ​​the silicon material itself is easy to agglomerate. It causes poor consistency; for example, by particle implantation, the doping amount and doping depth of the silicon material can be controlled to improve the consistency of the material

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