Silicon oxides for Li-ion battery anode applications: Toward long-term cycling stability

The emergence of developing new anode materials for Li-ion batteries has motivated experts to screen several materials to replace conventional carbonaceous anodes. Silicon oxides with different silicon and oxygen contents are a promising family of anode materials without the severe volume change of silicon-based anodes. The formation of lithium oxide and lithium silicates in the first cycle helps to buffer the volume change, while the generated amorphous silicon can secure the high specific capacity in long-term cycling. Silicon monoxide (SiO) and silicon dioxide (SiO2) are commercially available, while silicon sub-oxides (SiOx) are usually formed during the heating process. However, the low conductivity and poor initial Coulombic efficiency problems still exist. This review paper is focused on the strategies proposed to overcome the mentioned problems faced by silicon oxides. Based on the latest advancements, future research directions and promising methods to overcome the remaining challenges are discussed to stimulate further discussion and ideas in the rational design of silicon oxide anodes with high specific capacity and long cycle stability in the near future.