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.