Boron-phosphorus co-doped porous silicon negative electrode material and preparation method thereof

Abstract

The invention discloses a boron-phosphorus co-doped porous silicon negative electrode material and a preparation method thereof. The boron-phosphorus co-doped porous silicon negative electrode material is characterized in that the material takes elemental silicon as a matrix and is doped with boron atoms and phosphorus atoms, the mass doping amount of the boron atoms is 0.001-0.17 wt%, the mass doping amount of the phosphorus atoms is 0.01-2wt%, and the balance is elemental silicon; and the structure of the silicon material is a hollow porous structure. The silicon source and the doping sourceare both soluble liquid precursors, the uniform doping characteristic of the product silicon material can be guaranteed, and the doping content can be adjusted in a large range by changing the proportion of the added raw materials. Silicon reduction and element doping processes are synchronously completed by adopting a magnesiothermic reduction method, an additional compounding or coating step isnot needed, the energy consumption is low, the process is simple, and the method is suitable for industrial production. Two important problems of volume expansion and poor conductivity of the siliconmaterial in industrial production are solved at the same time, and the obtained product has excellent comprehensive performance and good practical prospect.

Description

technical field [0001] The invention belongs to the field of inorganic nano-energy storage materials, and in particular relates to a boron-phosphorus co-doped porous silicon negative electrode material and a preparation method thereof. Background technique [0002] With the continuous development of society, people's demand for energy continues to increase, traditional fossil fuels are gradually exhausted, and the timeliness of new energy sources such as wind energy and solar energy is greatly limited, so the demand for energy storage devices is increasing; At the same time, the rapid development of electric vehicles and smart grids puts higher demands on high energy density energy storage devices. In this context, lithium-ion batteries, as an electrochemical energy storage device with obvious advantages, have attracted extensive attention. Traditional graphite anode materials due to their low lithium storage capacity (372mAh g -1 ) is difficult to meet the current needs, ...

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Problems solved by technology

However, although the initial reaction temperature of magnesia thermal reduction is low, the magnesia thermal reduction process is a violent exothermic reaction process. The local temperature in the reaction system is too high, which leads to partial melting and agglomeration of silicon. The accumulation will lead to the collapse and agglomeration of the porous structure formed by the magnesia thermal reaction, thereby reducing the electrochemical performance of porous silicon; in addition, in order to improve the conductivity of porous silicon and enhance the lithium storage performance of porous silicon, it is often used before or after the magnesia thermal reduction process. Additional compounding or cladding processes are required to mix high-conductivity or high-stability materials such as carbon materials, ceramic materials, metal materials, etc., with silicon. These additional compounding or cladding processes greatly increase the difficulty of preparation and are difficult Guarantees uniform dispersion of the different components in the composite

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