Electrochemical properties of Si film electrodes deposited on electrochemically etched Cu substrate

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In order to investigate the electrochemical properties of Si electrodes deposited on a roughened current collector (substrate), the electrochemical etching method was applied to a Cu current collector. The surface roughness of a Cu current collector could be controlled with an electrochemical etching time and the roughest surface was obtained at 20 min etched Cu foil. After the etching, a thin Cu2O film was formed on the surface due to high reactivity with air. Amorphous Si films were deposited on flat and rough substrates and their morphologies were considerably affected by those of substrates. A Si electrode with a rough current collector exhibited remarkably improved cycle performance and maintained a discharge capacity over 1200 mA h g−1 even after the 50th cycle. The formation of large cracked Si tiles was caused by the improved adhesion between Si film and Cu substrate.