Surface acidity regulation for boosting Li2O2 decomposition towards lower charge overpotential Li–O2 batteries

Abstract

The discharge product Li₂O₂ with a wide band gap requires a high potential to decompose, hindering the practical application of Li–O₂ batteries (LOBs). Herein, a surface acidity regulation strategy is proposed to boost Li₂O₂ decomposition through doping Mn atoms into Co₃O₄ catalyst. Experimental results and theoretical calculations demonstrate that the doped Mn atoms increase empty orbitals near the Fermi level to enhance the surface acidity of Co₃O₄. Among the doped catalysts, the 15%Mn-doped Co₃O₄ with a suitable surface acidity of 347.5 μmol g⁻¹ promotes the electronic transfer from Li₂O₂ to Co₃O₄ and coordinates the reduction of the desorption barriers of Li⁺ and O₂, which effectively boosts the decomposition of Li₂O₂ to reduce the charge overpotential of LOBs, thus achieving a low charge overpotential (1.18 V at 1000 mA g⁻¹) and great cyclic stability (350 cycles at 4000 mA g⁻¹) in LOBs. Even under the limited specific capacity of 2000 mAh g⁻¹, the 15%Mn-doped Co₃O₄-based LOBs exhibit a great cycle stability of 250 cycles. This work elucidates the critical role of catalyst surface acidity regulation in boosting Li₂O₂ decomposition, thus reducing the charge overpotential of LOBs.