RuO₂ sputtered thin film supercapacitor's performance as function of oxygen incorporation

The relation of oxygen incorporation of RuO₂ film and Li+ ions is not clear as yet. To find a correlation between the capacitance and oxygen contents can provide the insight of mechanism and the improvement of performance. We sputtered the bottom electrode, RuO₂ film on Pt/TiO₂/Si substrate in different oxygen partial pressure. Lipon (lithium phosphorous oxynitride) film as an electrolyte was r.f. sputtered on it, and RuO₂ film as a top electrode was deposited on Lipon with the same procedure of the first layer. In this work, we studied the effect of oxygen excess on the performance of TFSC. All solid-state TFSC was tested with charge-discharge cyclic measurement. It ran for 200 cycles. As the cycles go on, the capacitance decreases gradually. When oxygen partial pressure increased during RuO₂ film deposition, the fade of capacitance rised.