“…For MnO/Mn 3 O 4 , Mn2p 3/2 and Mn2p 1/2 peaks are fitted into four peaks 642.22 eV and 640.18 eV, 652.44 eV and 655.70 eV, which is consistent with Mn 3+ and Mn 2+ . After the electrochemical oxidation, Mn2p narrow spectrum for Na 0.91 MnO 2 shows four peaks with the binding energy at 642.90 eV and 641.86 eV, 654.57 eV and 653.10 eV, corresponding to Mn 4+ and Mn 3+ . For the core‐level O1s spectra (Figure d), both MnO/Mn 3 O 4 and Na 0.91 MnO 2 show three peaks at the binding energy of 530.11 eV, 531.49 eV and 532.79 eV, which is consistent with Mn−O, Mn−OH and −OH from adsorbed water .…”