Sn-based alloy materials have gained popularity to replace commercial graphite anodes due to their higher gravimetric and volumetric capacity for next generation rechargeable lithium-ion batteries. Here a series of SnxFe alloys with nanosized derived from chemical transformation of pre-formed Sn nanoparticles as templates were successfully prepared. The morphology, crystal structure and composition of SnxFe intermetallic are greatly influenced by temperature, surface stabilizer and reagent molar ratio. The optimized Sn-Fe anode with core-shell structure could deliver 541 mAh/g after 200 cycles at the C/2 rate, corresponding to nearly 100 % initial capacity and 90.2% of the maximum charging capacity. The calculated volumetric capacity was about two times than that of commercial carbon. It also has excellent rate performance, delivering 94.8%, 84.3%, 72.1%, and 58.2% of the 0.1C capacity (679.8 mAh/g) at 0.2C, 0.5C, 1C and 2C, respectively. When it went back from 1 C to 0.1 C, the charge capacity recovered to 513.3, 603.2, 662 and 692.8 mAh g−1. The exploring of Fe-Sn alloy from this work also provides insight for the designing other Sn-M (Co, Ni, Cu, Mn etc.) system.
Acknowledgement: This work is supported by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) program under Award No. DE-EE0006852.