fig4
Figure 4. Characterizations of the cathode in the MnO2/VOSO4-Zn battery in the 20th cycle: (A) XRD patterns at different states, (B) SEM and (C) EDS elemental mapping images after charge, (F) SEM image after discharge, XPS spectra in the region of (D) Mn 3s and (E) O 1s.
