Preparation method of carbon-coated nitrogen-magnesium-doped porous silicon-based composite material and lithium ion battery

Abstract

The invention relates to the field of battery material preparation methods, and discloses a preparation method of carbon-coated nitrogen-magnesium-doped porous silicon-based composite material and a lithium ion battery. The method comprises the steps of dropwise adding a carbon source solution into nano silicon dioxide powder, and carrying out high-temperature carbonization operation in a nitrogenatmosphere so as to obtain a carbon-coated nitrogen-doped silicon dioxide material; performing high-temperature reduction operation on the carbon-coated nitrogen-doped silicon dioxide material in a reducing atmosphere to obtain a carbon-coated nitrogen-doped silicon-based composite material; etching the carbon-coated nitrogen-doped silicon-based composite material to obtain a carbon-coated nitrogen-doped porous silicon-based composite material; carrying out ultrasonic dispersion operation on the carbon-coated nitrogen-doped porous silicon-based composite material to obtain a dispersed mixed turbid solution; and adding the dispersed mixed turbid solution into a magnesium source mixed solution, and carrying out separation, washing and drying operations to obtain the carbon-coated nitrogen-magnesium-doped porous silicon-based composite material. According to the method, volume expansion of silicon can be effectively inhibited, and the conductivity and the initial efficiency of the silicon-carbon material are effectively improved.

Description

technical field [0001] The invention relates to the field of battery material preparation methods, in particular to a preparation method of a carbon-coated nitrogen-magnesium-doped porous silicon-based composite material and a lithium-ion battery. Background technique [0002] In recent years, lithium-ion batteries have been widely used in vehicles, portable electronic devices, hybrid vehicles and electric vehicles due to their advantages of green energy, high energy density, good cycle performance, and environmental friendliness. At present, the anode material of lithium-ion batteries used in the commercial field is generally graphite. However, the theoretical specific capacity of graphite is only 372mAh / g, which restricts the practical application of lithium-ion batteries as power batteries in fields such as transportation and energy storage. Silicon, silicon-based alloys and silicon oxides have high theoretical specific capacity and good safety, and are ideal substitute ...

AI Technical Summary

Problems solved by technology

Among them, silicon particles are often pulverized by high-energy ball milling of large silicon blocks. The particle size of silicon particles obtained by this method is relatively large, and the silicon particles are solid. This structure cannot effectively alleviate the volume expansion of silicon, and silicon-carbon negative electrode materials are widely used. There is a problem of weak conductivity and low first effect caused by excessive polarization

At present, the main method for enterprises to improve the first efficiency is through lithium supplementation. However, lithium powder is a flammable and corrosive substance, and the conditions for lithium supplementation are relatively harsh. Strict protection measures need to be taken to inject silicon-carbon anode materials in a strict oxygen-free environment. If lithium powder is added inside, if oxygen leakage occurs during lithium supplementation, combustion or even explosion accidents will easily occur, and the cost of lithium supplementation is high and the safety is low, so it is not suitable for large-scale promotion and use.

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