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

摘要

Sb-doped SnO_2 (ATO) nanostructured thin films were prepared by using radio frequency magnetron sputtering at the substrate temperatures of 25 ℃, 100 ℃ and 200 ℃, respectively. All the ATO thin films have the similar redox characteristics in the cyclic voltammetry measurements. The ATO thin film sputtered at 200 ℃ shows the lowest charge transfer resistance and best electrochemical performance, and has a high reversible capacity of 679 mA h g~(-1) at 100mA g~(-1) after 200 charge-discharge cycles and high rate performance of 483 mAh g~(-1) at 800mA 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 SnO_2 reacted with Li~+ to produce metallic Sn and followed by the formation of the Li_xSn alloys during discharge process, and then Li_xSn alloys de-alloyed, Sn reacted with Li_2O, and even partially formed SnO_2 during charge process.