Biomass-Assisted Construction of Carbon-Supported Fe–Co–Cu Trimetallic Oxides/Sulfides for Supercapacitors with Excellent Performance

Transition-metal compounds are considered as a promising class of electrode materials due to their unique features, combining with good electrical conductivity, enhanced ion-diffusion rate, abundant active sites for redox reaction, available multiple oxidation states, high electrochemical activity, and low activation energy for electron transfer among metal centers. Compared with monometallic and bimetallic compounds, the construction of trimetallic compounds can further boost the electrochemical performance. Here, a biomass-assisted approach is presented to construct CoFe2O4–Cu5FeS4–CoS2 trimetallic composites loaded on porous carbon via a cross-linking process followed by high-temperature sulfidation. Due to the formation of interconnected ion-diffusion channels, rich redox reaction sites, and synergistic effect among trimetallic composites, the optimized sample exhibits impressive electrochemical performance with a specific capacitance of 3899.7 F g–1 at 0.5 A g–1, which is obviously superior to the corresponding bimetallic composite-based electrodes. Furthermore, the assembled CoFe2O4–Cu5FeS4–CoS2@PC-700//PC-700 asymmetric supercapacitor maintains an excellent cycling stability of 92.23% after 10,000 cycles. The device reveals an energy density of up to 80.5 W h kg–1 at a rate of 0.45 kW kg–1. This work provides an idea for the preparation of pseudocapacitive electrode materials with high-energy storage capacity.