A review of anode materials for sodium ion batteries

Lithium-ion batteries (LIBs) are used in electric vehicles and portable smart devices, but lithium resources are dwindling and there is an increasing demand which has to be catered for. Sodium ion batteries (SIBs), which are less costly, are a promising replacement for LIBs because of the abundant natural reserves of sodium. The anode of a SIB is a necessary component of the battery but is less understood than the cathode. This review outlines the development of various types of anodes, including carbon-based, metallic and organic, which operate using different reaction mechanisms such as intercalation, alloying and conversion, and considers their challenges and prospects. Strategies for modifying their structures by doping and coating, and also modifying the solid electrolyte interface are discussed. In addition, this review also discusses the challenges encountered by the anode of SIBs and the solutions.