Reduction of irreversibility in the first charge of tin oxide thin film negative electrodes

Sputter deposited 3000 Angstrom tin oxide thin films into which metallic lithium (6000 Angstrom) was reacted were studied to develop a new negative electrode for thin firm rechargeable lithium batteries. The crystal structure and chemical composition of the lithium reacted tin oxide alms were characterized by X-ray diffraction (XRD) analysis and Auger electron spectroscopy, respectively. The charge/discharge performances of these films exhibited capacities >400 mAh/g for >75 cycles. There was no irreversible plateau near 0.8 V vs. Li/Li+ due to reduction of SnO2 to Sn and Li2O during the first charge half-cycle. XRD and scanning transmission electron microscopy results suggest that the Lithium-reacted tin oxide thin film consists of metallic tin, lithium oxide, and reduced tin oxide, and the reacted thin films show reduced microcracks created by density fluctuations. (C) 2001 The Electrochemical Society. All rights reserved.