Interface engineering of MnO2 for high-performance photo-rechargeable Zn ion batteries

Abstract

Photo-rechargeable zinc-ion batteries (ZIBs) are emerging as a promising energy storage technology, offering advantages in safety and cost over conventional integrated systems. Their widespread application, however, is hindered by the limited photoelectric conversion efficiency of typical photocathodes. To address this, we present an interface engineering strategy by constructing MnO2/TiO2 photocathode. In this design, an amorphous TiO2 layer functions as an interfacial electron transport channel, which not only facilitates the efficient separation of photogenerated electron-hole pairs but also enhances the subsequent Zn2+ storage kinetics. The photo-rechargeable ZIB based on the MnO2/TiO2 photocathode demonstrates a high specific capacity of 374 mAh g-1 under illumination, significantly surpassing the 230 mAh g-1 obtained in the dark, alongside a high photo-conversion efficiency of 1.5%. Furthermore, a proof-of-concept integrated power unit comprising three photo-rechargeable ZIBs connected in series is demonstrated to effectively drive various electronic devices, including the drone, model car, and light bulbs. This work provides a viable interfacial design principle for high-performance photo-rechargeable ZIBs and highlights their potential for future renewable energy applications.