A Photo‐Assisted Chargeable Aqueous Zinc‐Iodine Battery

Abstract Solar energy is an abundant and renewable energy resource, but it must be captured and stored for practical application in view of the intermittency and low‐energy density. The search for an effective solar energy storage system is highly required, yet remains a challenge. In this paper, we design a novel solar energy storage device by integrating a TiO 2 photo‐electrode into an aqueous zinc‐iodine battery (ZIB). During charging process under illumination, I − in catholyte is oxidized to I 3 − by photo‐excited holes from TiO 2 photo‐electrode. Meanwhile, the photo‐excited electrons transfer to the anode through the external circuit and reduce the Zn 2+ into Zn. Due to the compensation of photo‐voltage, an ultralow charging voltage of 0.56 V is achieved, much lower than the discharging voltage (1.2 V), resulting in 54 % input electric energy savings.