Electrochemical and microstructural characterization of magnetron-sputtered ATO thin films as Li–ion storage materials

• Nano-structured ATO thin films prepared by RF magnetron sputtering at 25 °C, 100 °C and 200 °C, respectively.
• ATO thin films show a high reversible capacity and high rate performance.
• Electrochemical reaction mechanism of the ATO thin film was revealed by transmission electron microscopy.

Sb-doped SnO2 (ATO) nanostructured thin films were prepared by using radio frequency magnetron sputtering at the substrate temperatures of 25 °C, 100 °C and 200 °C, respectively. All the ATO thin films have the similar redox characteristics in the cyclic voltammetry measurements. The ATO thin film sputtered at 200 °C shows the lowest charge transfer resistance and best electrochemical performance, and has a high reversible capacity of 679 mA h g−1 at 100 mA g−1 after 200 charge–discharge cycles and high rate performance of 483 mA h g−1 at 800 mA g−1. The electrochemical mechanisms were investigated by analyzing the phase evolution of the ATO electrodes that had been electrochemically induced at various stages. The results reveal that the ATO underwent reversible lithiation/delithiation processes during the electrochemical cycles, i.e., the SnO2 reacted with Li+ to produce metallic Sn and followed by the formation of the LixSn alloys during discharge process, and then LixSn alloys de-alloyed, Sn reacted with Li2O, and even partially formed SnO2 during charge process.

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