A facile electrosynthesis approach of amorphous Mn-Co-Fe ternary hydroxides as binder-free active electrode materials for high-performance supercapacitors

Electrochemical energy storage technologies such as batteries and supercapacitors have a great potential for use in many applications. However, to meet the increasing demand in both the energy and power densities of these devices, further research and development are essential to overcome major obstacles such as cost and durability, which are hindering their commercialization. Herein, we report on the successful deposition of amorphous Mn-Co-Fe ternary hydroxide nanoplatelets directly on Ni foam without the need for any binders. The material was fully characterized using EDS, XRD, FTIR, Raman spectroscopy, XPS and FE-SEM techniques. Upon their use as supercapacitor electrodes, the deposited amorphous mixed hydroxide nanoplatelets demonstrated a maximum specific capacitance of 1200 F/g at a scan rate of 5 mV/s. The asymmetric supercapacitor device showed an energy density of 11.4 Wh/kg with a corresponding power density of 1125 W/kg at a charging current density of 1.5 A/g as calculated from the galvanostatic charging/discharging (GCD) measurements. The cyclic stability of the assembled device was scrutinized via GCD test for 4000 cycles while measuring its electrochemical impedance spectra before and after cycling. The decay in the supercapacitive performance was found to be as low as ∼4% after 4000 GCD cycles, indicating an excellent long-term stability, with the equivalent series resistance (ESR) remained almost constant during those cycles. [Display omitted] •Binder-free Mn-Co-Fe ternary hydroxide nanoflakes were successfully deposited on Ni foam.•A specific capacitance of 1200 F/g at a scan rate of 5 mV/s was achieved.•Cyclic stability of the assembled device was scrutinized via GCD test for 4000 cycles.•The equivalent series resistance (ESR) remained almost constant after 4000 cycles.•The device maintains excellent capacitance retention at ∼96% after 4000 GCD cycles.