Perovskite-based aqueous supercapacitors have important development prospects due to their advantages
of high energy density, low cost, environmental benignity. Here, bimetallic Ni-Mn and trimetallic
Ni-Co-Mn perovskite fluorides are prepared via facile solvothermal method and characterized as positive
electrode materials for supercapacitors. The structure, composition, chemical states and the electrochemical
properties of these samples are investigated in detail. Three electrode measurements indicate that
the electrochemical properties of the perovskite fluorides KNiF3 depend on the nature and amount of
dopants. Partial doping of Ni by Mn increases the rate capability but decreases the specific capacity, while
Co and Mn co-doping improve both the rate capability and specific capacity of perovskite fluoride KNiF3.
The K-Ni-Co-Mn-F (Ni/Co/Mn = 12:2:1) sample exhibits the maximum specific capacity of 211 mAh g 1,
low internal resistance and a high rate capability (82% capacity retention from 1 to 16 A g 1).
Furthermore, the AC//K-Ni-Co-Mn-F (Ni/Co/Mn = 12:2:1) asymmetric supercapacitor delivers a maximum
energy density of 50.2 Wh kg 1. These results prove that Co and Mn co-doped KNiF3 can be a
promising material for supercapacitor.