Constructing asymmetrical dual catalytic sites in manganese oxides enables fast and stable lithium–oxygen catalysis

Abstract

Manganese oxides as cathode catalysts for lithium–oxygen batteries exhibit unsatisfactory oxygen catalytic activity and cycling stability, due to the weak adsorption of oxygen-containing intermediates and inevitable structural degradation caused by unstable high electron-density Mn sites. Herein, we rationally construct asymmetrical Mn–Ru dual sites on MnO₂ nanowires to improve the catalytic activity and stability for Li–O₂ batteries. Refined structural characterization proves that the Mn–Ru dual sites lead to an increase in electron density around the Mn site. Moreover, theoretical calculations reveal that the Ru single atom incorporation effectively decreases electron density in Mn–O antibonding states, thus stabilizing the high electron-density Mn sites while enhancing the adsorption of oxygen-containing intermediates. The obtained MnO₂ nanowires with Mn–Ru dual sites display an overall discharge/charge overpotential (0.50 V) and an unprecedented cycling life (180 cycles or 1800 h), which is significantly superior to bare MnO₂ and outperforms most of the ever-reported noble-metal-based cathodes. More importantly, the asymmetrical dual sites construction strategy can be readily expanded to Mn–Ir dual sites for enhancing the catalytic activity and stability of Mn-based catalysts.