硅化镁还原CO2一步原位合成Si/C复合负极

硅碳(Si/C)负极被认为是高能量密度锂离子电池的首选负极材料，本文提出了一种利用Mg₂Si一步还原CO₂原位制备硅碳复合材料的新方法，研究了Ar∶CO₂混合气体积比和反应温度等关键工艺对Si/C负极材料微结构和电化学性能的影响。研究发现，该方法原位合成的Si/C颗粒尺寸为几百纳米，晶态硅和无定形碳相互交织、分布均匀。当反应温度为700℃、Ar∶CO₂=7∶1时合成的Si/C复合材料作为锂离子电池负极材料时，在0.2 A/g的电流密度下，500个循环后仍有1134 mA·h/g可逆容量。本文利用温室气体CO₂来制备储能用Si/C复合负极材料，既能实现变废为宝，同时该方法合成工艺简便，容易工业化实施，具有商业化开发的潜力。 

In-situ synthesis of Si/C composites anode by one-step reduction of CO2 with magnesium silicide

Silicon/carbon (Si/C) anode is considered as a promising anode material for high-density lithium ion batteries. In the present work, a novel strategy to in-situ synthesize Si/C composites by one-step reduction of CO₂ with Mg₂Si was proposed. The effects of volume ratio of Ar∶CO₂ mix gas and the reaction temperature on the microstructure and electrochemical properties of the synthesized Si/C were investigated. It is found that crystalline Si and amorphous C are interwoved each other in the Si/C particles with the size of about several nanometers. As anode materials for lithium ion batteries, the Si/C composites synthesized at 700℃ under the Ar∶CO₂ gas ratio of 7∶1 exhibit a high capacity of 1134 mA·h/g over 500 cycles at a current density of 0.2 A/g. This study provides an avenue to synthesize Si/C energy storage materials from greenhouse CO₂ gas with the merits of facile operation procedure, easy large-scale production and potential commercial applications.