Review of silicon-based alloys for lithium-ion battery anodes

Silicon (Si) is widely considered to be the most attractive candidate anode material for use in next-generation high-energy-density lithium (Li)-ion batteries (LIBs) because it has a high theoretical gravimetric Li storage capacity, relatively low lithiation voltage, and abundant resources. Consequently, massive efforts have been exerted to improve its electrochemical performance. While some progress in this field has been achieved, a number of severe challenges, such as the element's large volume change during cycling, low intrinsic electronic conductivity, and poor rate capacity, have yet to be solved. Methods to solve these problems have been attempted via the development of nanosized Si materials. Unfortunately, reviews summarizing the work on Si-based alloys are scarce. Herein, the recent progress related to Si-based alloy anode materials is reviewed. The problems associated with Si anodes and the corresponding strategies used to address these problems are first described. Then, the available Si-based alloys are divided into Si/Li-active and inactive systems, and the characteristics of these systems are discussed. Other special systems are also introduced. Finally, perspectives and future outlooks are provided to enable the wider application of Si-alloy anodes to commercial LIBs.