Utilizing solar energy to improve the oxygen evolution reaction kinetics in zinc-air battery.

Liu, Xiaorui; Yuan, Yifei; Liu, Jie; Liu, Bin; Chen, Xu; Ding, Jia; Han, Xiaopeng; Deng, Yida et al. · Nat Commun · 2019

basic_science · Level V

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Abstract

Directly harvesting solar energy for battery charging represents an ultimate solution toward low-cost, green, efficient and sustainable electrochemical energy storage. Here, we design a sunlight promotion strategy into rechargeable zinc-air battery with significantly reduced charging potential below the theoretical cell voltage of zinc-air batteries. The sunlight-promoted zinc-air battery using BiVO<sub>4</sub> or α-Fe<sub>2</sub>O<sub>3</sub> air photoelectrode achieves a record-low charge potential of ~1.20 and ~1.43 V, respectively, under illumination, which is lowered by ~0.5-0.8 V compared to the typical charge voltage of ~2 V in conventional zinc-air battery. The band structure and photoelectrochemical stability of photoelectrodes are found to be key factors determining the charging performance of sunlight-promoted zinc-air batteries. The introduction of photoelectrode as an air electrode opens a facile way for developing integrated single-unit zinc-air batteries that can efficiently use solar energy to overcome the high charging overpotential of conventional zinc-air batteries.