Defect-induced deposition of manganese oxides on hierarchical carbon nanocages for high-performance lithium-oxygen batteries

The cathode of lithium-oxygen (Li-O₂) batteries should have large space for high Li₂O₂ uptake and superior electrocatalytic activity to oxygen evolution/reduction for long lifespan. Herein, a high-performance MnO_x/hCNC cathode was constructed by the defect-induced deposition of manganese oxide (MnO_x) nanoparticles on hierarchical carbon nanocages (hCNC). The corresponding Li-O₂ battery (MnO_x/hCNC@Li-O₂) exhibited excellent electrocatalytic activity with the low overpotential of 0.73‒0.99 V in the current density range of 0.1‒1.0 A·g^–1. The full discharge capacity and cycling life of MnO_x/hCNC@Li-O₂ were increased by ~86.7% and ~91%, respectively, compared with the hCNC@Li-O₂ counterpart. The superior performance of MnO_x/hCNC cathode was ascribed to (i) the highly dispersed MnO_x nanoparticles for boosting the reversibility of oxygen evolution/reduction reactions, (ii) the interconnecting pore structure for increasing Li₂O₂ accommodation and facilitating charge/mass transfer, and (iii) the concealed surface defects of hCNC for suppressing side reactions. This study demonstrated an effective strategy to improve the performance of Li-O₂ batteries by constructing cathodes with highly dispersed catalytic sites and hierarchical porous structure.