Converting bulk MoSi2 alloy to a SiOx based anode material through controlled oxidation induced sublimation

Abstract

SiO_x-based anode materials have attracted increasing attention for lithium storage because of their natural abundance, low cost, and high capacity. However, the practical application of bulk SiO_x remains challenging due to its unsatisfactory cyclability originated from the serious structural degradation and poor electrical conductivity. Herein, a micron-sized SiO_x-based anode material (SiO_x/MoSi₂, designated as SiMoO-800), where conductive MoSi₂ nanocrystals are dispersed in a SiO_x matrix, is constructed by the controllable oxidation of bulk MoSi₂ alloy. During the controlled oxidation process, most of the Mo sublimates in the form of MoO₃. The unique SiO_x/MoSi₂ composite demonstrates a high capacity, good cyclability, and ideal rate performance. The full cell based on a SiO_x/MoSi₂ anode and LiFePO₄ cathode delivers a high capacity (131.5 mA h g⁻¹ after 100 cycles at 0.5 C) and long-term durability (500 cycles).