Fabrication of thin-film lithium batteries with 5-V-class LiCoMnO4 cathodes

All-solid-state thin-film batteries with a 5-V-class cathode material (LiCoMnO4) were fabricated. LiCoMnO4 thin films were grown by pulsed laser deposition. X-ray diffraction and cyclic voltammetry (CV) were used to characterize the thin films. Effects of deposition parameters on the structure, morphology, and electrochemical properties of the thin films were investigated, particularly the influence of oxygen partial pressure, laser fluence, and substrate temperature. The CV curves of the LiCoMnO4 thin films prepared under optimized conditions exhibited reversible 5-V charge/discharge peaks. Thin-film batteries fabricated with LiCoMnO4 cathodes operated at potentials greater than 5 V, which is among the highest voltages reported for a thin-film battery. The thin-film battery also showed good cycling performance at 5 V, with an initial discharge capacity of 107 mAh/g and a capacity retention of 99.4% after 20 cycles.