Electrochemical properties of asymmetric supercapacitor based on optimized carbon-based nickel-cobalt-manganese ternary hydroxide and sulphur-doped carbonized iron-polyaniline electrodes

This study describes a modified low temperature gel-method for production of low cost mixed-metal hydroxides/carbon composites electrode materials via a simple and cost-effective stirring technique. A ternary metal hydroxide of nickel, cobalt, and manganese (NiCoMn-TH) combined with activated expanded graphite (AEG) as composite electrode material (NiCoMn-TH/AEG) provided a maximum specific capacity of 116.81 mAh g−1 at a specific current of 0.5 A g−1, measured in a three-electrode configuration in 1 M KOH aqueous electrolyte. Electrochemical measurements of the NiCoMn-TH/AEG composite material and a sulphur-doped carbonized iron PANI (CFP–S) negative electrode assembled as an asymmetric supercapacitor (SC), delivered a high energy density of 23.5 Wh kg−1 corresponding to a power density of 427 W kg−1 at 0.5 A g−1. Interestingly, the assembled asymmetric SC, NiCoMn-TH/AEG//CFP-S gained about 68.4% of its initial specific capacitance corresponding to an energy density of ∼31.8 Wh kg−1 resulting in a power density of 530.1 W kg−1 over a floating test of 120 h at a specific current of 1 A g−1. These excellent results suggest that this composite material possesses satisfactory potential for high efficient electrode for supercapacitor applications.