TiO2-coated LiCoO2 electrodes fabricated by a sputtering deposition method for lithium-ion batteries with enhanced electrochemical performance

We fabricated lithium cobalt oxide (LiCoO2, LCO) electrodes in the absence and presence of TiO2 layers as cathodes for lithium-ion batteries (LIBs) using a sputtering deposition method under an Ar atmosphere. In particular, TiO2 coating layers on sputtered LCO electrodes were directly deposited in a layer-by-layer form with varying TiO2 sputtering times from 60 to 120 s. These sputtered electrodes were heated at 600 °C in an air atmosphere for 3 h. The thicknesses of TiO2 layers in TiO2-coated LCO electrodes were controlled from ∼2 to ∼10 nm. These TiO2-coated LCO electrodes exhibited superior electrochemical performance, i.e. high capacities (93–107 mA h g−1@0.5C), improved retention of >60% after 100 cycles, and high-rate cycling properties (64 mA h g−1@1C after 100 cycles). Such an improved performance of TiO2-coated LCO electrodes was found to be attributed to relieved volumetric expansion of LCO and protection of LCO electrodes against HF generated during cycling.