3D Hierarchical Sunflower‐Shaped MoS2/SnO2 Photocathodes for Photo‐Rechargeable Zinc Ion Batteries

Photo-rechargeable zinc-ion batteries (PRZIBs) have attracted much attention in the field of energy storage due to their high safety and dexterity compared with currently integrated lithium-ion batteries and solar cells. However, challenges remain toward their practical applications, originating from the unsatisfactory structural design of photocathodes, which results in low photoelectric conversion efficiency (PCE). Herein, a flexible MoS₂/SnO₂-based photocathode is developed via constructing a sunflower-shaped light-trapping nanostructure with 3D hierarchical and self-supporting properties, enabled by the hierarchical embellishment of MoS₂ nanosheets and SnO₂ quantum dots on carbon cloth (MoS₂/SnO₂ QDs@CC). This structural design provides a favorable pathway for the effective separation of photogenerated electron-hole pairs and the efficient storage of Zn²⁺ on photocathodes. Consequently, the PRZIB assembled with MoS₂/SnO₂ QDs@CC delivers a desirable capacity of 366 mAh g^-1 under a light intensity of 100 mW cm^-2, and achieves an ultra-high PCE of 2.7% at a current density of 0.125 mA cm^-2. In practice, an integrated battery system consisting of four series-connected quasi-solid-state PRZIBs is successfully applied as a wearable wristband of smartwatches, which opens a new door for the application of PRZIBs in next-generation flexible energy storage devices.