Porous trimetallic fluoride Ni–Co–M (M = Mn, Fe, Cu, Zn) nanoprisms as electrodes for asymmetric supercapacitors

Electroactive materials, with high electrochemical activity, are urgently needed for supercapacitors. While it remains a great challenge to integrate high rate capability and outstanding cycling stability simultaneously. Mixed transition metal fluorides with porous structures are regarded as helpful active electrode materials for supercapacitors. Herein, three dimensional porous tri metallic (Ni–Co–M, M = Mn, Fe, Cu, Zn) fluorides were synthesized by reflux condensation and calcination methods. Among them, Ni–Co–Zn fluorides (NCZF) exhibited stronger synergetic electrochemical property compared with other transition metals, contributing a high specific capacitance of 914.4 F/g at 1 A/g and 81.3% capacity retention at 20 A/g and the specific capacitance could maintain 45.6% after 30,000 cycles. The hybrid supercapacitor based on NCZF and activated carbon (AC) electrodes also displayed a specific capacity of 222 F/g at 1 A/g and 90.2 F/g at 20 A/g with ultralong cycling stability (61.9% capacity retention after 10,000 cycles).