Bimetallic Co-Mn Perovskite Fluorides as Highly-Stable Electrode Materials for Supercapacitors.

Bimetallic Co-Mn perovskite fluorides (KCox Mn1-x F3 , denoted as K-Co-Mn-F) with various Co/Mn ratios (1:0, 12:1, 6:1, 3:1, 1:1, 1:3, 0:1) were prepared through a one-pot solvothermal strategy and further used as electrode materials for supercapacitors. The optimal K-Co-Mn-F candidate (Co/Mn=6:1) showed a size range of 0.1-1 μm and uniform elemental distribution; exhibiting small changes in XRD peaks and XPS binding energy in comparison to the bare K-Co-F and K-Mn-F, due to the structural/electronic effects. Owing to the stronger synergistic effect of Co/Mn redox species, the K-Co-Mn-F (Co/Mn=6:1) electrode exhibited superior specific capacity and rate behavior (113-100 C g-1 at 1-16 Ag-1 ) together with excellent cycling stability (118 % for 5000 cycles at 8 Ag-1 ), and the activated carbon (AC)//K-Co-Mn-F (Co/Mn=6:1) asymmetric capacitor showed superior energy and power densities (8.0-2.4 Wh kg-1 at 0.14-8.7 kW kg-1 ) along with high cycling stability (90 % for 10 000 cycles at 5 Ag-1 ).