The electrochemical insertion-deinsertion of lithium into CuO electrode was examined by Cu K-edge X-ray absorption near edge structure (XANES) during the first electrochemical cycle. The XANES spectra in the LixCuO (x: lithium content) system reveal that the initial insertion of lithium leads to the reduction of the Cu2+ in the pristine CuO to form the reduced nanosized Cu metal. In the successive deinsertion of lithium, the reduced Cu particles changed partially to the phase of Cu2O.

Keywords: XANES; nanoparticles; CuO