Preparation method of high-specific energy porous silicon-carbon composite negative electrode material

Abstract

The invention discloses a preparation method of a high-specific energy porous silicon-carbon composite negative electrode material. The preparation method concretely comprises the following steps: dispersing micro-nano silicon powder in an aqueous carbonate solution, slowly adding the obtained solution to an aqueous solution of a calcium salt under rapid stirring, and continuing stirring for 0.5-10 h; purifying the obtained solid, dispersing the purified solid in a polymer solution, and stirring the solid and the polymer solution for 0.5-5 h; and drying the obtained solid, pre-reacting the dried solid in air at 200-350 DEG C for 0-5 h, carbonizing the obtained pre-reaction product in an inert atmosphere at 600-1500 DEG C for 1-10 h, and purifying and drying the obtained product to obtain the porous silicon-carbon composite negative electrode material.

Description

technical field [0001] The invention relates to the technical field of inorganic non-metallic materials, in particular to a preparation method of a high-specific-energy porous silicon-carbon composite negative electrode material. Background technique [0002] In recent years, new energy vehicles have become the key investment areas of countries all over the world, and a series of domestic preferential policies have also greatly promoted the development of new energy vehicles. However, most commercial lithium-ion batteries for power batteries use graphite as the negative electrode, but the theoretical discharge specific capacity of graphite is only 372mAh / g, which has defects such as low energy density, low power density, or poor cycle life. At the same time, it is easy to form a stable solid electrolyte interface film and the volume expansion and contraction of graphite flakes during the charge-discharge cycle can easily lead to serious safety problems (Journal of Power Sour...

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Problems solved by technology

However, most commercial lithium-ion batteries for power batteries use graphite as the negative electrode, but the theoretical discharge specific capacity of graphite is only 372mAh / g, which has defects such as low energy density, low power density, or poor cycle life.

At the same time, it is easy to form a stable solid electrolyte interface film and the volume expansion and contraction of graphite flakes during the charge-discharge cycle can easily lead to serious safety problems (Journal of Power Sources, 2013, 236: 118-125)

[0003] As the anode material of lithium-ion batteries, silicon has a theoretical capacity as high as 4200mAh / g, so it has received extensive attention in the research and development of long-life power batteries. However, silicon will undergo serious volume shrinkage and expansion during charging and discharging, and the volume change can be Up to 300%, the large internal stress generated inside the material causes the material structure to break and fall off, reducing the conductivity and cycle stability of the electrode

Therefore, most studies use nano-silica powder (less than 100 nanometers) and porous silicon, or compound silicon powder and carbon materials to prepare nano-structured silicon-carbon composite materials. The process is generally complicated and difficult to achieve industrialization, resulting in high costs.

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