Introduction of photo electrochemical water-oxidation mechanism into hybrid lithium-oxygen batteries

The hybrid lithium oxygen batteries (LOBs) have been limited by the sluggish electrochemical catalytic performance towards both oxygen reduction (ORR) and oxygen evolution reaction (OER). Previous research has utilizing the light illumination to promote the charge process in non-aqueous electrolyte. However, the organic electrolyte has been blamed for the poor electrochemical stability and volatilization during illumination. For the first time, photo-enhanced aqueous LOBs have been promoted, where the reaction mechanism of OER is familiar with photo electrochemical (PEC) water-oxidation. The alpha-Fe2O3 nanorods and BiVO4 nanoplates are synthesized by the hydrothermal method combined with heat treatment, showing good photo-electrocatalytic property. Herein, the alpha-Fe2O3 electrode exhibits a superior longtime stability than the BiVO4 nanoplates, which suffer from the severe photo-corrosion. The photo-assisted hybrid Li-O-2 battery based on alpha-Fe2O3 electrode is realized with a discharge potential of 2.56 V. Compared with the traditional hybrid LOBs, the charge potential is reduced from 3.96 V to 3.15 V. This work indicates that most n-type semiconductors used in PEC water-oxidation can have positive effect on the charge process in hybrid LOBs.