Effects of surface modification by MgO on interfacial reactions of lithium cobalt oxide thin film electrode

Magnesium oxide (MgO)-modified lithium cobalt oxide (LiCoO 2) thin film electrodes were prepared by pulsed laser deposition (PLD) and effects of surface modification by MgO on interfacial reactions of LiCoO 2 were studied. The modification by MgO was carried out by PLD on LiCoO 2 thin film electrode successively after the deposition of LiCoO 2 thin film by PLD. Auger electron spectroscopy suggested that Mg dispersed uniformly in nano-scale on the film electrode. Cyclic voltammetry measurements clearly showed that MgO modification suppresses the increase of resistances caused by repetition of lithium-ion insertion–extraction reaction charged up to 4.2 V versus Li/Li +. Moreover, MgO modification decreased the activation energy of lithium-ion transfer reaction at LiCoO 2 thin film electrode–electrolyte interface, indicating that the modification by MgO affects the kinetics of lithium-ion transfer reaction at LiCoO 2–electrolyte interface.