Silicon-carbon composite materials

Comparative analysis of silicon-carbon composite materials and silicon-oxygen anode Silicon-carbon composite materials:...

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Comparative analysis of silicon-carbon composite materials and silicon-oxygen anode

Silicon-carbon composite materials:

Silicon-carbon composite materials are usually composed of a mixture of nano-silicon and graphite materials. By reducing the particle size of silicon-based materials to the nanometer level, smaller particle sizes and more voids can be obtained, making it easier to buffer the stress and deformation generated by silicon during the process of lithium ion insertion and extraction. In addition, nanoparticles can shorten the diffusion distance of lithium ions and increase the lithium storage capacity of silicon materials. The core difficulty of the production process of silicon-carbon anodes lies in the preparation of nano-silicon powder, and common nano-silicon production processes include magnesium thermal reduction, silane thermal decomposition, discharge plasma and mechanical grinding.

Silicon-oxygen anode:

Silicon-oxygen anodes are made of a mixture of silicon oxide (SiOx) and graphite materials. Compared with silicon materials, the volume expansion of silicon oxide during lithium insertion is greatly reduced, so the cycle performance is greatly improved. The core of silicon-oxygen anodes is the preparation of SiOx. Most companies synthesize SiOx from pure silicon and SiO2 to form a silicon-oxygen anode precursor, which is then prepared through a series of processes. SiOx can also be purchased directly from outside, but it still needs to be processed before it can be compounded with artificial graphite to prepare silicon-oxygen negative electrode.

The carbon negative electrode technology route mostly uses nano-silicon. The small particle size can improve the volume change of silicon-based materials during charging and discharging, and nano-scale silicon materials have smaller particle sizes and more gaps, which can more easily buffer the stress and deformation generated by silicon during the process of lithium ion insertion and extraction. In addition, nanoparticles can shorten the diffusion distance of lithium ions and increase the lithium storage capacity of silicon materials. The silicon-oxygen negative electrode technology route mostly uses silicon oxide. Compared with single silicon particles, silicon oxide (SiOx) has a smaller volume expansion during lithium insertion, so its cycle stability is significantly improved compared to pure silicon negative electrode.

At present, silicon-oxygen is the main power in applications. In the field of power batteries, the third-generation pre-lithium silicon-oxygen, Tesla (doped 5%), Kirin battery (doped 8-12%), NIO ET7 (doped 20-30%, semi-solid, but poor cycle); in the field of consumer batteries, silicon carbon is more advanced, doped 5-10%.

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