In situ grown NiFeP@NiCo2S4 nanosheet arrays on carbon cloth for asymmetric supercapacitors

Construction of pseudocapacitive electrode materials with well-defined nanostructures is highly desirable for exploring supercapacitors with both high energy density and power density. Herein, we propose a novel strategy to design three-dimensional [email protected]2S4 nanosheet arrays directly grown on carbon cloth via successively hydrothermal reaction, phosphorization treatment, and electrodeposition technique. The integrated hybrid electrode inherits the characteristics of high electrical conductivity and multiple oxidation states from single component, and also forms well-developed nanosheet-like heterostructure with good structural stability and generates strong synergistic effect of ion, nickel, and cobalt ions. Thus, the prepared binder-free [email protected]2S4 electrode shows a high specific capacity of 874.4C g−1 at a current density of 1 A g−1, outstanding rate capability (76.1% capacitance retention at 20 A g−1) and good long-term cycling stability (85.6% retention after 5000 cycles), which is superior to pure NiFeP and NiCo2S4 nanosheets. Furthermore, the constructed asymmetric supercapacitor device displays a high energy density of 87.9 Wh kg−1 at a power density of 433.6 W kg−1 and good cycling stability (85.2% retention after 10,000 cycles). This work offers a feasible and effective approach to design positive electrode materials with smart heterostructure for high-performance asymmetric supercapacitors.