Realizing Reversible Photo‐Charging via Stacked 1T/2H MoS 2 Bifunctional Cathodes for Photo‐Rechargeable Batteries

ABSTRACT Photo‐rechargeable batteries that integrate solar energy harvesting, conversion, and storage in a single device are able to efficiently utilize sustainable energy. However, current photo‐batteries based on bifunctional (photovoltaic conversion and energy storage) cathodes could only achieve photo‐assisted charging, whereas light‐only photo‐charging remains incomplete and irreversible. Particularly, in absence of a photo‐charging circuit, the observed charging phenomena are pseudo photo‐charging due to side reactions. To realize genuine photo‐charging, we design a bifunctional cathode of MoS 2 by integrating photo active (2H) and energy storage (1T) phases. Nickel oxide is introduced to improve the interface conductivity and stabilize the 2H/1T phases of MoS 2 . Additionally, we employed an external resistance to balance the self‐discharge current and the photo‐charging current under illumination. For the first time, we demonstrate Zn 2+ photo‐batteries that can be reversibly photo‐charged for over ten times, and the deposition of zinc at the anode is visualized. The photo‐rechargeable batteries could realize a photo‐charging capacity ratio of 100% by2 h illumination, with a specific capacity of 110.55 mAh g −1 . Furthermore, we assemble a sustainable energy harvest‐conversion‐storage mini‐system that could practically provide energy to portable electronics.