Direct fabrication of LiCoO2 thin-films in water–ethanol solutions by electrochemical–hydrothermal method

Abstract

LiCoO2 thin films were synthesized via an easy one-step electrochemical-hydrothermal route using ethanol–water blends as solvent. The influence of the synthesis parameters - i.e. ethanol/water ratio, temperature, pressure, reaction time and current density - on the formation of layered R3¯m phase and on its electrochemical behavior in lithium cells was investigated. X-ray diffraction (XRD) shows the formation of well-crystallized R3¯m LiCoO2 thin films with preferred (101) orientation, without any trace of spinel-like (LT-LiCoO2) phase or cobalt oxide Co3O4 impurities. LiCoO2 films with controlled orientation exhibit a specific capacity close to the theoretical value, and excellent capacity retention even at high current density. Experimental results reveal that electrodeposition under hydrothermal conditions allows high deposition rates reaching 500nmmin−1.