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Surface-coated/uncoated epitaxial LiCoO2 film electrodes with (104) orientations were fabricated on SrRuO3(100)/Nb:SrTiO3(100) using pulsed laser deposition. Films with thicknesses of ∼18 nm and flat surfaces with roughnesses of less than 1 nm were model systems for clarifying the kinetics of Li-ion transfer at the electrode/electrolyte interface. The Li-ion transfer characteristics at the interface between the LiCoO2 electrode and the electrolyte (LiPF6, ethylene carbonate + diethyl carbonate) were investigated by electrochemical impedance spectrometry. The charge-transfer resistance (Rct) of uncoated LiCoO2 increased from the early cycles when charged/discharged at 3.0-4.2 V. When charged/discharged at 3.0-4.5 V, the Rct of the uncoated LiCoO2 rapidly increased from the first charge. In contrast, the Rct of Li2ZrO3-coated LiCoO2 remained almost constant during the early cycles when charged/discharged either at 3.0-4.2 or at 3.0-4.5 V. The interfacial resistances of the coated and uncoated LiCoO2 electrodes were almost equal (~100 Ω cm2). The activation energy for charge transfer was lower for the coated LiCoO2 electrode compared to that for the uncoated electrode. The current-rate capability was significantly improved by surface coating even at high-voltage charge/discharge at 3.0-4.5 V. The charge transfer process is the rate-determining step of the charge/discharge reaction. [ABSTRACT FROM AUTHOR]