Binder free approach for fabrication of lithium cobalt oxide for thin film based lithium-ion µ-batteries

Abstract

The increasing demand for microelectronics has significantly driven the advancement of thin film energy storage devices, specifically lithium-ion batteries. In this current work, binder-free lithium cobalt oxide (LCO) has been synthesized by Radio Frequency (RF) magnetron sputtering on aluminium foil substrate in an argon atmosphere. The investigation focused on optimizing the cathode on aluminium foil by varying parameters, such as RF source power, working pressure, and temperature of the substrate. The deposited layers were analyzed for their structural and surface properties to confirm the formation of LCO. The surface of LCO obtained from this binder-free approach helps us create an excellent interface between cathode-electrolyte with a low contact angle (18.1°). An electrochemical analysis of the optimized sample (480 nm thick) was carried out by using 1 M lithium hexa-fluoro-phosphate. The initial charge capacity in the 2 − 4.2 V voltage range was obtained to be 624 mAh/cm³ at the C-rate of 0.05C, which is closer to the theoretical capacity (690 mAh/cm³). Signifying, over 90 % of total lithium is contributed during the charge storage mechanism. As a result, it can be interpreted that the binder-free sputtering technology can be implemented to fabricate efficient electrodes for lithium-ion batteries.