Tunable High-Performance Photo-Assisted Li-O₂ Batteries by the Construction of Ferroelectric Photocathode

Photo-assistance is considered to be an effective approach to reducing the overpotential for lithium-oxygen (Li-O₂) batteries. However, the advancement is greatly hindered by the rapidly recombined photoexcited electrons and holes upon the discharging and charging processes. Herein, a breakthrough in overcoming these challenges is achieved by developing an efficient ferroelectric photocatalyst with spontaneous polarization-induced internal electric fields. Tungsten (W) doped Bi₃TiNbO₉ (Bi₃TiNbO₉-W) as a photocatalyst exhibits enhanced anisotropic migration of photogenerated electrons and holes, which play a key role in reducing the overpotential in the discharge and charge processes, enabling the desirable spatial separation of carriers. Benefiting from the driving force for charge separation, the photocatalytic oxygen reduction and evolution reaction activity is largely improved. As a result, the Bi₃TiNbO₉-W-based Li-O₂ batteries have shown incremental round-trip efficiencies of 95.9% based on the ultra-high discharge voltage (3.25 V) and ultra-low charge voltage (3.39 V). Besides, the constructed photo-assisted Li-O₂ batteries deliver a high rate capability and ultralong durability within 960 h. These findings demonstrate the crucial role of ferroelectric polarization in the improved photocatalytic reaction process, providing significant insight into addressing the overpotential bottleneck in Li-O₂ batteries.