Toward Practical Photo-Assisted Li-O2 Batteries: a Four-Electron Pathway Enabled by Ru-Doped β-MnO2

Photo-assisted Li-O₂ batteries, which utilize solar energy to reduce overpotentials, have attracted significant interest. However, challenges such as sluggish redox kinetics, limited photogenerated carrier availability, excessive byproduct formation, and oxygen evolution constraints persist. This study integrates computational and experimental approaches to demonstrate that Ru doping at interstitial sites in β-MnO₂ induces lattice expansion, introduces additional reactive sites, enhances light absorption, and accelerates redox reaction kinetics. Under simulated conditions (57% relative humidity), the battery achieves an impressive 98.4% round-trip efficiency, excellent high-rate performance, and exceptional cycling stability over 720 h with reversible four-electron conversion to LiOH. Furthermore, stable operation under real atmospheric conditions marks the first demonstration of a photo-assisted Li-O₂ battery based on a four-electron process. These findings provide new insights into advancing the practical implementation of Li-O₂ batteries for efficient energy storage applications.