Group IVA Alloy Anodes for Sodium-Ion Rechargeable Batteries: Electrochemistry, Mechanics, and Kinetics

Sodium-ion batteries (SIBs) are perhaps the most promising technology currently to fulfill the requirements of large-scale energy storage. Unlike lithium, sodium (Na) source is cost-effective, abundant, and geographically evenly distributed. While hard carbon remains the benchmark anode material in SIBs, its specific capacity is limited by adsorption-intercalation chemistry, necessitating the exploration of new alternatives to meet the increasing energy demands. Group IVA alloy elements exhibit interesting sodium storage capabilities with significantly higher specific capacities. This work systematically reviews the electrochemistry, mechanics, and kinetics of silicon (Si), germanium (Ge), tin (Sn), and lead (Pb) in various SIB systems, highlighting the key points of each element: (1) Si is electrochemically inactive to Na though theoretical calculations suggest the existence of Na−Si intermetallic compounds; (2) the formation of Na−Ge phases beyond 1 : 1 atomic stoichiometry is kinetically limited; (3) the high impedance of Na−Sn phases lead to a series of charge transfer issues; (4) Pb-based anodes should not be fully eliminated from the future roadmap due to the promising cycling performances and mature recycling efforts. Collectively, this review sets a comprehensive foundation for researchers investigating alloy-type anodes for SIBs.