Sn4P3–C nanospheres as high capacitive and ultra-stable anodes for sodium ion and lithium ion batteries

Abstract

Tin phosphide (Sn₄P₃) has emerged as an anode for sodium ion batteries (SIBs) due to its high reversible capacity and low redox potential. Sn₄P₃ shows a synergistic Na-storage reaction to form Na₁₅Sn₄ and Na₃P, but suffers from large volume expansion and Sn aggregation during the Na⁺ insertion–extraction resulting in poor cycle stability. Sn₄P₃ has also been considered a promising anode material for lithium ion batteries (LIBs), but very limited studies have been performed. Herein, core–shell Sn₄P₃–C (carbon) composite nanospheres are fabricated by carbonization/reduction and phosphorization of SnO₂–GCP (glucose-derived, carbon-rich polysaccharide) nanospheres. The size of Sn₄P₃–C nanospheres is controlled to optimize their electrochemical performance as long-term stable anodes for SIBs and LIBs. Among them, the 140 nm-sized Sn₄P₃–C nanosphere electrode exhibits high reversible capacity, high rate capability, and ultra-long cycle stability as an anode for both SIBs and LIBs, delivering a high capacity of 420 mA h g⁻¹ after 2000 cycles (SIBs) and 440 mA h g⁻¹ after 500 cycles (LIBs) at a high current density of 2000 mA g⁻¹. Hence, the Sn₄P₃–C nanospheres can be considered as a promising anode material for next generation SIBs and LIBs.