Binder and carbon-free SbSn-P nanocomposite thin films as anode materials for sodium-ion batteries

Tin-antimony/phosphorus nanocomposite thin films have been successfully prepared by pulsed laser deposition and are studied as anode materials for sodium ion batteries. The thin films exhibit a specific capacity of about 252 mAh g−1 over 100 cycles at a rate of 250 mA g−1, which is much higher than those for tin-antimony alloy, antimony or tin thin films. The improved electrochemical performance is attributed to the introduced phosphorus, which plays a key role in forming a stable solid electrolyte interface layer, thus enhances the reversibility. Phase separation is revealed after the initial cycle by forming the metallic tin and antimony nanoparticles. In addition, introducing phosphorus into tin-antimony alloy film can reduce the interfacial resistance between the electrode and electrolyte, as well as facilitate sodium-ion diffusion in the electrode.