Dual photoelectrodes activate oxygen evolution and oxygen reduction reactions enabling a high-performance Zn-air battery and an efficient solar energy storage

Traditional Zn-air batteries (ZABs) require a large charge voltage but deliver a small discharge voltage due to their slow kinetics of oxygen evolution and reduction reaction (OER and ORR) on air electrodes. Herein, a novel photorechargeable Zn-air battery (PRZAB) is fabricated by two photoelectrodes to sandwich a Zn electrode, significantly promoting the kinetics of OER and ORR. As a result, the PRZAB achieves an ultra-low charge voltage of 0.63 V and a remarkably high discharge voltage of 1.64 V at a current density of 0.1 mA cm−2, leading to a considerable voltage gap of 1.01 V that the process of discharge exceeds charge to be realized in ZABs. Compared with the ZAB with a state-of-the-art Pt/C catalyst, the charge energy of the PRZAB is saved 184% and its output is enhanced by 18%. Finally, the overall solar-to-output energy conversion efficiency (SOEE) is estimated to be 1.38%. The work provides an innovative way to boost rechargeable battery performance and offers an efficient strategy to store and utilize solar energy.