Enhancement of thin film tin oxide negative electrodes for lithium batteries

Thin films of pure SnO2, of the Sn/Li2O layered structure, and of Sn/Li2O were fabricated by sputtering method, while a `lithium-reacted tin oxide thin filmʹ was assembled by the evaporation of lithium metal onto a SnO2 thin film. Film structure and charge/discharge characteristics were compared. The lithium-reacted tin oxide thin film, the Sn/Li2O layered structure, and the Sn/Li2O co-sputtered thin films did not show any irreversible side reactions of forming Li2O and metallic Sn near 0.8 V vs Li/Li+. The initial charge retention of the Sn/Li2O layered structure and Sn/Li2O cosputtered thin films was about 50% and a similar value was found for the lithiumreacted tin oxide thin film (more than 60%). Sn/Li2O layered structure and Sn/Li2O cosputtered thin films showed better cycling behavior over 500 cycles than the pure SnO2 and lithium-reacted tin oxide thin film in the cut-off range from 1.2 to 0 V vs Li/Li+.