Curtailing the Overpotential of Lia??CO2 Batteries with Shapea??Controlled Cu2O as Cathode: Effect of Illuminating the Cathode

摘要： Li-air batteries are circumscribed to lab-scale research due to the uninterrupted formation of discharge products. In the case of Li–CO2 batteries, the increase in overpotential due to Li2CO3 formation results in cell death. In this study, we have synthesized Cu2O crystals having three different types of shapes, i.e., cubic, octahedral, and rhombic, to compare the catalytic activity toward CO2 reactions. The full-cycle and long-term stability test reveals that rhombohedral Cu2O facilitates Li2CO3 decomposition more efficiently than that of cubic and octahedral Cu2O. We have extended the cycle to dig into the photocatalytic activeness of the rhombic Cu2O by illuminating the cell. The repeated cycles to 1 h show maximum overpotential of 1.5 V, which is 0.5 V less than that of the cell without illumination. A postmortem analysis of the cell after dividing the cycles into segments demonstrates interesting results on the role of light and Cu2O during the cell cycle.