Mn–Fe-based oxide electrocatalysts for air electrodes of lithium–air batteries

• The electrochemical properties of lithium–air batteries with MnOx were examined.
• We attempted to improve battery performance by substituting the Mn with Fe, Ni, or Co.
• The batteries using Mn2−xFexO3 showed large 1st discharge capacity of 230 mAh g−1.
• Mn1.8Fe0.2O3 had stable cycle characteristics with a capacity loss of 25% after 10 cycles.

The electrochemical properties of lithium–air batteries incorporating air electrodes loaded with MnOx, which had different Mn valences as the electrocatalysts were examined in an organic electrolyte solution consisting of 1 mol l−1 lithium bis(trifluoromethanesulfonyl)imide (LiTFSI)/propylene carbonate (PC). Furthermore, we attempted to improve the battery performance by substituting the Mn site in MnOx with Fe, Ni, or Co. The batteries using Mn2−xFexO3 showed rather large 1st discharge capacities of 230 mAh g−1 at a current density of 0.25 mA cm−2 in a dry air atmosphere. The discharge and charge overpotentials were both greatly reduced by loading Mn2−xFexO3 catalysts. However, almost all of these oxides exhibited poor cycle performance. Of the oxides that we examined, Mn1.8Fe0.2O3 had comparatively stable cycle characteristics with a capacity loss of only 25% after 10 cycles.