Edge-Dislocated WO3 Photocathode Toward Efficient Photo-Assisted Li-O2 Batteries.

Abstract

The operation of rechargeable Li-O2 batteries critically depends on the highly reversible formation and decomposition of Li2O2 at the cathode. However, the intrinsic insulating nature of Li2O2 fundamentally restricts reaction kinetics, posing a core challenge to practical applications. Here, it is demonstrate that the insulating properties of Li2O2 can be effectively improved by photoexcitation, attributed to the generation of photo-induced charge carriers. It is inspired to develop photo-assisted Li-O2 batteries featuring Z-type photocathode@Li2O2 heterojunction, which serves as a charge modulation channel to regulate carrier dynamics through photocathode modifications. By employing edge-dislocated WO3 as the photocathode, sustained growth of Li2O2 films is observed with a thickness >18 µm, which is 2-3 orders of magnitude higher than typically reported values. Benefiting from the enhanced exciton dissociation of Li2O2 and improved oxidative capability of photocathode, the battery delivers an ultra-high discharge capacity of 31 800 mAh g-1 under a current density of 100 mA g-1 and a light-induced temperature of ≈60 °C. In addition, a low polarization overpotential of 0.04 V is achieved with high reversibility over 1 000 h. The grasp of photoexcited Li2O2 within Li-O2 batteries can drive solutions beyond state-of-the-art metal-air batteries.