Research Progress on SiO_x and its Composite Anode Materials for Lithium Ion Battery

To meet the growing demand for electrochemical performance of batteries in electronic devices and electric vehicles, high-performance lithium ion batteries and their electrode materials have attracted recent attention. Silicon oxide (SiO_x, 0<x<2) is considered as a promising anode material for lithium ion battery because of its high theoretical capacity, low voltage platform and abundant natural resources. However, SiO_x has some severe challenges, such as poor cycle performance, low Coulombic efficiency and low rate properties, seriously hindering its commercial development. In this review, the lithium storage mechanism of SiO_x was introduced from its structural characteristics. The research progress of SiO_x and its composite was represented in detail from three aspects, i.e., the selection of silicon source, the design of binder and electrolyte. Furthermore, the effects of organosilicon sources such as esters, silanes and biomass and inorganic silicon sources on the structure and electrochemical properties of SiO_x and its composites were summarized. Finally, some challenges in the process of commercialization of SiO_x and its composites were analyzed. It is indicated that the challenges can be solved by comprehensively adopting modification strategies and approaches such as the design of special structure, element doping, pre-lithiation and the introduction of good conductive carriers, which can effectively promote the commercialization of SiO_x anode materials.