The Role of Self-Catalysis Induced by Co Doping in Nonaqueous Li-O 2 Batteries.

This work systematically studies the product self-catalysis of in situ electrochemical cobalt doping of Li 2 O 2 and reveals its potential mechanism for improving the performance of lithium-oxygen (Li-O 2 ) batteries. Theoretical calculations demonstrate that the discharge products contain substituted and interstitial Co impurities, which serve as active sites to promote the formation of Li 3 O 4 crystallization, thus switching the nucleation mechanism from the main discharge product Li 2 O 2 to Li 3 O 4 . This Co-doping behavior leads to the thermodynamically favorable and dynamically stable formation of Li 3 O 4 crystals during the discharge process. Through systematic investigation of the structural, energetic, electronic, diffusive, and catalytic properties of the Co-doped Li 2 O 2 and Li 3 O 4 compounds, we found that Li 3 O 4 has better charge/mass transport and a lower overpotential for the Li 3 O 4 formation/decomposition reaction. Consequently, this work elucidates that Co doping provides a simple and effective approach for increasing the proportion of Li 3 O 4 , which can significantly improve the Li-O 2 battery performance.