Carbon nanotube‐supported mixed‐valence Mn3O4 electrodes for high‐performance lithium‐oxygen batteries

Abstract

Lithium–oxygen batteries (LOBs) have extensive applications because of their ultra-high energy densities. However, the practical application of LOBs is limited by several factors, such as a high overpotential, poor cycle stability, and limited rate capacity. In this paper, we describe the successful uniform loading of Mn₃O₄ nanoparticles onto multi-walled carbon nanotubes (Mn₃O₄@CNT). CNTs form a conductive network and expose numerous catalytically active sites, and the one-dimensional porous structure provides a convenient channel for the transmission of Li⁺ and O₂ in LOBs. The electronic conductivity and electrocatalytic activity of Mn₃O₄@CNT are significantly better than those of MnO@CNT because of the inherent driving force facilitating charge transfer between different valence metal ions. Therefore, the Mn₃O₄@CNT cathode obtains a low overpotential (0.76 V at a limited capacity of 1000 mAh g⁻¹), high initial discharge capacity (16895 mAh g⁻¹ at 200 mA g⁻¹), and long cycle life (97 cycles at 200 mA g⁻¹). This study provides evidence that transition metal oxides with mixed-valence states are suitable for application as efficient cathodes for LOBs.