Synergy of a heteroatom (P–F) in nanostructured Sn3O4 as an anode for sodium-ion batteries

Abstract

Na-ion batteries (SIBs) have attracted attention due to their economics and eco-friendly nature compared to lithium-ion batteries. Tin-based compounds are focused for SIBs owing to high theoretical capacities, though they have problems such as lower conductivity and pulverization that hinder their practical applications. Nanoscaling of the tin-based anode material with dual heteroatom doping having different functions might improve the electrochemical performance. Hence, a green approach for the synthesis of dual ion (P–F)-doped nanostructured Sn₃O₄ by a hydrothermal method was demonstrated with excellent Na-storage performance. A strategy of synthesizing dual ion-doped Sn₃O₄ can boost electrochemical performances owing to lattice distortion caused by defects, improved sodium ion conductivity and structural stability of electrodes. Significantly, P and F doping into Sn₃O₄ exhibits high specific capacity with superior rate capability, i.e. 705 mA h g⁻¹ at 50 mA g⁻¹ and 136 mA h g⁻¹ at current density 5 A g⁻¹. The physical insights into the Sn₃O₄ structure due to doping are illustrated, and the relationship with capacity density was investigated. This dual-ion doping strategy may motivate constructing high-performance SIBs.