摘要
Silicon oxide thin films featuring different stoichiometries (SiO x , x = 0.72, 1.23, and 1.58) are prepared using radio frequency sputtering, and the electrochemical behaviors of these films as anode materials for lithium ion batteries are investigated. X-ray photoelectron spectroscopy and glazing incidence X-ray diffraction measurements are conducted at different discharge/charge potentials. The results reveal that the main lithium silicates phases observed during lithiation/delithiation processes are Li 2 Si 2 O 5 , Li 6 Si 2 O 7 , and Li 4 SiO 4 . Films featuring high O stoichiometries tend to form silicate phases exhibiting high O stoichiometries, which present high redox potentials. The Li 2 Si 2 O 5 phase is a kinetically favorable phase and primary reversible product of the lithiation process, while the Li 6 Si 2 O 7 and Li 4 SiO 4 phases appear to be the irreversible products of films presenting high O stoichiometries during the early lithiation/delithiation cycles within the redox potential range of 0.01–1.5 V. However, if the delithiation potential is increased to 3 V, the LiSi 2 O 5 and Li 6 Si 2 O 7 phases appear to be reversible during the early lithiation/delithiation cycles. The Li 4 SiO 4 phase, which is the main silicate phase of SiO 1.58 , remains irreversible. The SiO 1.58 film presents the specific capacities of 1129, 1044, 854, and 828 mAh/g at the charge/discharge rates of 0.1, 0.5, 1, and 5 C, respectively, after 200 cycles.