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, and belongs to the technical field of the technical field of lithium ion battery material preparation. The technical solutions are as follows: (1) weighing 1 to 5 g of sulfur-containing organic compounds and 1 to 5 g of nitrogen-containing organic compounds,adding the compounds to 500 g of organic solvent, stirring evenly, adding 100 g of graphite into the solution, stirring evenly, filtering, then transferring the solution to a tube type furnace, raising the temperature to 200-500 DEG C under an inert atmosphere, then keeping the temperature for 1 to 6 h, and reducing the temperature to the room temperature in an inert atmosphere to obtain a graphite composite material A; (2) implanting the nano-silica in the surface layer of the graphite composite material A through high-speed particle beam bombardment and then carrying out carbonization to obtain the sulfur / nitrogen / silicon co-doped graphite composite anode material. According to the invention, the specific capacity of the graphite material is improved by doping sulfur in the graphite material, and nitrogen doping is carried out to improve the conductivity of the sulfur; 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 lithium ion battery material preparation. Background technique [0002] With the increasing demand for energy density of lithium-ion batteries in the market, the negative electrode materials used in lithium-ion batteries are required to have high specific capacity and cycle life. Currently, the graphite materials on the market have a low reversible capacity (theoretical capacity of 372mAh / g), which limits its use. increase in energy density. The silicon carbon anode material has attracted the attention of researchers due to its high gram capacity and abundant resources, and has been used in high specific energy density lithium-ion batteries and other fields, but its high expansion rate and conductivity deviation restrict its wide application. However, mixing and compounding gra...

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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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