Layered Tin Phosphide Composites as Promising Anodes for Lithium-Ion Batteries

Tin phosphides have garnered considerable attention as promising anode materials for lithium-ion batteries (LIBs) due to their high theoretical capacities and earth abundance of constituent elements. Particularly, the rhombohedral Sn3P4 compound, a long-proven phase of tin phosphides, remains unexplored for LIBs. In this study, a solid-state reaction was employed to prepare Sn3P4-based composites as anodes for LIBs. The layered Sn3P4/Sn4P3 composite with the highest Sn3P4 percentage of 80.5% shows an impressive electrochemical performance when carboxymethylcellulose sodium and super P were adopted as the binder and conductive agent, respectively. The higher theoretical capacity of the dominated Sn3P4 in the composites compared to Sn4P3 and the enhanced charge transfer with carbon coating contribute to the improved rate capability and cycle life of Sn3P4/Sn4P3@C composites. Specifically, the resultant Sn3P4/Sn4P3@C anode shows a highly reversible capacity (1140 mAh g–1 at 0.1 A g–1 after the initial five cycles), a considerable rate capability (750 mAh g–1 at 2.0 A g–1), and a good durability (513 mAh g–1 after 100 cycles at 1.0 A g–1). The intrinsic composition of Sn and P coupled with the layered structure accounts for such a superior Li-storage performance. Our findings indicate that layered Sn3P4-based materials are promising candidate anodes for next-generation LIBs.