The Role of Self-Catalysis Induced by Co Doping in Nonaqueous Li-O₂ Batteries

This work systematically studies the product self-catalysis of in situ electrochemical cobalt doping of Li₂O₂ and reveals its potential mechanism for improving the performance of lithium-oxygen (Li-O₂) batteries. Theoretical calculations demonstrate that the discharge products contain substituted and interstitial Co impurities, which serve as active sites to promote the formation of Li₃O₄ crystallization, thus switching the nucleation mechanism from the main discharge product Li₂O₂ to Li₃O₄. This Co-doping behavior leads to the thermodynamically favorable and dynamically stable formation of Li₃O₄ crystals during the discharge process. Through systematic investigation of the structural, energetic, electronic, diffusive, and catalytic properties of the Co-doped Li₂O₂ and Li₃O₄ compounds, we found that Li₃O₄ has better charge/mass transport and a lower overpotential for the Li₃O₄ formation/decomposition reaction. Consequently, this work elucidates that Co doping provides a simple and effective approach for increasing the proportion of Li₃O₄, which can significantly improve the Li-O₂ battery performance.