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

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 R (3) over barm phase and on its electrochemical behavior in lithium cells was investigated. X-ray diffraction (XRD) shows the formation of well-crystallized R (3) over barm 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 500 nm min (1). (C) 2015 Elsevier Ltd. All rights reserved.