Light-assist electrochemical lithiation to silicon semiconductor

•Light-assisted electrochemical lithiation using p-type and n-type silicon single crystals is examined.•Current density is improved significantly during cyclic voltammetry measurement under light irradiation.•Electrochemical impedance spectroscopy measurement shows that the charge-transfer resistance reduces under light irradiation.•Si K-edge X-ray absorption spectroscopy confirms electrochemical lithium-silicon alloying reaction assisted by light irradiation. Charging rate of present lithium-ion batteries is needed to be fast for energy storage of electric vehicles. Light-assisted electrochemical reaction in lithium-ion batteries is one strategy to improve the rate capability. The original concept was reported by making use of the band bending between semiconductor electrodes and ionic conductive electrolytes under light irradiation. However, limited experimental data is provided by comparing light-assist lithiation using n-type and p-type semiconductors in lithium-ion battery system. Here, we report light-assisted electrochemical lithiation using p-type and n-type silicon single-crystals. Improved current density is observed in cyclic voltammetry under light irradiation. Silicon K-edge X-ray absorption spectroscopy confirms the enhanced lithium-silicon alloying reactions by light irradiation especially in p-type silicon. The electrochemical impedance spectroscopy shows that the charge-transfer resistance reduces under light irradiation, which indicates the kinetics acceleration of lithium ions at the electrode/electrolyte interface.