Synthesis, Lithium Insertion and Thermal Stability of Si–Mo Alloys

Abstract

Li insertion was investigated in SixMo100−x (90 ≥ x ≥ 70, Δx = 10) alloys prepared by mechanical ball milling. X-ray diffraction (XRD) and quantitative phase analysis were used to analyze phase compositions of these Si–Mo alloys, and how these phase compositions changed with milling times. The results of quantitative phase analysis showed that cr-Si converted into a-Si within 1 h during milling, and the Si–Mo reactions were nearly complete after only 4-h milling. During electrochemical cycling, the Si–Mo samples with high initial Mo contents and long milling times displayed good crystalline Li15Si4 suppression and stable cycling performance. In addition, thermal stability of some selected Si–Mo alloys was studied. The Si80Mo20 16 h alloy combines good thermal stability and a high volumetric capacity of about 1300–1400 Ah L−1 after heat treatment at 600 °C or 800 °C, which may allow the alloy to be further improved by carbon coating at high temperature.