An Efficient MnO 2 Photocathode with an Excellent SnO 2 Electron Transport Layer for Photo-Accelerated Zinc Ion Batteries.

Photo-accelerated rechargeable batteries play a crucial role in fully utilizing solar energy, but it is still a challenge to fabricate dual-functional photoelectrodes with simultaneous high solar energy harvesting and storage. This work reports an innovative photo-accelerated zinc-ion battery (PAZIB) featuring a photocathode with a SnO 2 @MnO 2 heterojunction. The design ingeniously combines the excellent electronic conductivity of SnO 2 with the high energy storage and light absorption capacities of MnO 2 . The capacity of the SnO 2 @MnO 2 -based PAZIB is ≈598 mAh g -1 with a high photo-conversion efficiency of 1.2% under illumination at 0.1 A g -1 , which is superior to that of most reported MnO 2 -based ZIB. The boosting performance is attributed to the synergistic effect of enhanced photogenerated carrier separation efficiency, improved conductivity, and promoted charge transfer by the SnO 2 @MnO 2 heterojunction, which is confirmed by systematic experiments and theoretical simulations. This work provides valuable insights into the development of dual-function photocathodes for effective solar energy utilization.