Hierarchical manganese valence gradient MnO2via phosphorus doping for cathode materials with improved stability

The search for a method for enhancing the electrochemical performance of manganese dioxide is still a challenge. Herein, we report a rod-like P-MnOx cathode material with a hierarchical manganese gradient valence through the phosphatization process. For the incorporation of P, Mn3O4 was formed on the surface of MnO2 and exhibited a gradient valence structure, while the oxygen defect concentration in P-MnOx increased. The unique structure was verified via XRD, TEM and XPS. As the cathode material for a supercapacitor, the specific capacitance of P-MnOx was 126.3 F g-1, which was four times that of MnO2. The assembling of the coin cells of aqueous ZIBs with P-MnOx also showed good rate performance. The electrochemical performance of the synthesised P-MnOx cathode was enhanced for the synergistic effect of improved conductivity and structural stability.