Construction of NiCoSe₂ nanosheets supported on CuNi₂S₄ nanospheres for advanced hybrid supercapacitors

The interface engineering strategy of hybridizing transition metal sulfides (TMSs) with other electroactive materials has proven to be a powerful strategy to exploit advanced electrode materials for supercapacitors (SCs). Herein, CuNi₂S₄ nanospheres were grown directly onto carbon cloth (CC) by a single-step electrodeposition procedure, and the bimetallic selenide NiCoSe₂ then was deposited over the CuNi₂S₄ nanospheres to create a flexible CuNi₂S₄@NiCoSe₂ hybrid electrode material with special core-shell architecture. The nanoflower-like hybrid structure not only increases the redox active sites but also provides short paths for electron/ion transport and improves redox reaction kinetics. The CuNi₂S₄@NiCoSe₂ electrode achieves a capacity value of 979.2 C g^-1/3.43 C cm^-2 at 1 A g^-1 along with good rate performance, outperforming pristine CuNi₂S₄ and NiCoSe₂. This wonderful supercapacitive behavior is related to the synergy of CuNi₂S₄'s high conductivity and NiCoSe₂'s high electroactivity. Furthermore, the hybrid supercapacitor using the CuNi₂S₄@NiCoSe₂cathode along with the porous carbon from pine pollen anode achieves an energy density (78.9 Wh kg^-1 at 720.2 W kg^-1) and maintains 91.4 % of original capacity after 50,000 cycles. These findings affirm that the CuNi₂S₄@NiCoSe₂ heterostructure is structurally superior as an electrode material in advanced energy storage systems.