A review of phosphorus and phosphides as anode materials for advanced sodium-ion batteries
Sodium-ion batteries (SIBs) are promising low-cost alternatives to lithium-ion batteries (LIBs) in energy storage applications because of the natural abundance of sodium as compared with lithium. However, the radius of Na+ ions is ∼50% larger than that of Li+ ions, leading to challenging sodiation/desodiation at the anodes of SIBs and reduced performances. Therefore, the exploration of novel SIB anode materials to facilitate sodiation/desodiation has become a leading area of research. Here, cost-effective phosphorus and metal/nonmetal phosphides, possessing high theoretical gravimetric capacities and volumetric specific capacities, have emerged as new and promising anode materials for SIBs. Based on this, this review will provide a comprehensive summary of the recent progress in the development of phosphorus and metal/nonmetal phosphide materials and corresponding composite SIB anodes in terms of material synthesis, characterization, sodium storage mechanism and performance validation in SIB apparatuses. In addition, challenges associated with the development of such advanced materials are summarized and analyzed. Finally, to facilitate the research and development of these emerging SIB anode materials, future research directions are proposed to overcome challenges toward the practical commercialization of sodium-ion batteries.