An Efficient MnO Photocathode with an Excellent SnO 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@MnO heterojunction. The design ingeniously combines the excellent electronic conductivity of SnO with the high energy storage and light absorption capacities of MnO. The capacity of the SnO@MnO-based PAZIB is ≈598 mAh g with a high photo-conversion efficiency of 1.2% under illumination at 0.1 A g, which is superior to that of most reported MnO-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@MnO 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.