Bifunctional WO3/TiO2 heterojunction photocathode for high-performance photo-assisted Li–O2 battery

Photo-assisted charging is a useful method for mitigating high overpotential in Lithium–oxygen (Li–O2) batteries. Herein, WO3/TiO2 heterostructures were carefully designed on carbon-fiber fabrics and used as photocathodes in photo-assisted Li-O2 batteries. The transfer mechanism of photoexcited carriers with a strong redox ability in WO3/TiO2 heterostructures reduces the compounding of electrons (e-) and holes (h+). Accordingly, the battery's energy can be tuned by illumination, giving an ultra-low overpotential of 0.11 V at a current density of 0.05 mA·cm-2 with excellent cycling stability (retaining a round-trip efficiency of 96.21% after 150 cycles). The cycle life can reach 1000 h due to increased photo-generated carrier separation efficiency and decreased electrochemical reaction impedance.