Research on tin-copper bimetallic phosphide nanoparticles as anode for sodium-ion batteries

Abstract

Although Sn₄P₃ exhibits potential as a material employed as the anode the practical use in SIBs is impeded by issues such as significant volume changes, poor cycling stability, and rapid capacity degradation. To tackle these obstacles, we employed a one-step solvothermal approach to disperse copper-doped Sn₄P₃ nanoparticles within a porous carbon (PC) network. The resulting SnCuP/PC composites serve as a promising electrode material for use in sodium ion storage. The porous carbon structure enhances the rate at which Na⁺ ions interact with the electrode, thereby reducing expansion of volume during charging and discharging processes. Additionally, copper doping enhances the conductivity of Sn₄P₃ and promotes Na⁺ ion migration. As a result, SnCuP/PC-2, as the material utilized in sodium ion battery anodes, exhibits reversible capacities at 443.8 mA h g⁻¹, 365.4 mA h g⁻¹, and 268.9 mA h g⁻¹ at current intensities of 0.2 A g⁻¹, 1.0 A g⁻¹, and 2.0 A g⁻¹, respectively. These impressive charge storage capacities may be credited to the porous configuration and elevated surface area per unit mass and abundance of electrochemically reactive sites within the composites. These features reduce electrical resistance at the interface of facilitate charge transfer and enhance ion diffusion. Furthermore, the presence of a carbon skeleton ensures consistent porous structure maintenance throughout charge and discharge cycles, thereby the performance under different charging rates and long-term stability over multiple cycles are also improved.