SILICON-BASED ALLOYS BY CHEMICAL DELITHIATION FOR LITHIUM-ION BATTERIES

Abstract

Li-ion battery research is of great technical and industrial importance. Currently, researchers are seeking negative electrode materials that will lead to higher energy density cells. Si-based alloys are promising candidates. However, the commercialization of Si-based alloys as Li-ion battery negative electrodes is hindered by the volume expansion problem of Si during lithiation. In this work, a chemical delithiation method was studied to prepare amorphous silicon (a-Si) from lithium silicide compounds with alcohol. This method was also utilized to synthesize carbon-silicon (C-Si) and iron-silicon (Fe-Si) alloys as negative electrodes for Li-ion batteries. Using powder X-ray diffraction, Mӧssbauer spectroscopy, scanning electron microscopy and electrochemical measurements, the structure and electrochemistry of a-Si, C-Si and Fe-Si alloys were investigated. The as-prepared a-Si, C-Si and Fe-Si electrodes displayed improved electrochemical performance and lower volume expansion compared to that of crystalline Si.