Magnetic field and photon co-enhanced S-scheme MXene/In2S3/CoFe2O4 heterojunction for high-performance lithium-oxygen batteries.

Under the spotlight for their potential to reduce over-potential, photo-assisted Li-O2 batteries still face a key challenge: the rapid recombination of photo-generated electron-hole pairs, which limits their efficiency. In this study, we address this limitation by designing a Li-O2 battery that integrates both photo and magnetic field assistance, using an S-scheme MXene/In2S3/CoFe2O4 heterojunction photocathode. This unique combination enhances visible light absorption and generates a strong built-in electric field, facilitating effective charge separation and boosting photocatalytic activity. During discharge, photo-generated electrons participate in the oxygen reduction reaction, while photo-induced holes contribute to the decomposition of discharge products during charging. Furthermore, the introduction of a magnetic field, confirmed through vibrating sample magnetometer, Mössbauer spectroscopy, X-ray absorption near edge structure, and cyclic voltammetry analyses, enhances electron-hole separation via Lorentz forces and spin-orbit coupling, accelerating the formation and decomposition of Li2O2. With this synergistic approach, the battery achieves a high specific capacity of 26,500 mAh g-1, ultra-low oxygen reduction/evolution reaction over-potentials of 0.08 V/0.17 V, and a long cycle life of 2000 cycles with energy efficiency of 98.11 %. This work demonstrates the promising potential of combining photo and magnetic field effects to improve the electrochemical performance of Li-O2 batteries, opening new avenues for high-performance energy storage systems.