Nickel sulfide and cobalt-containing carbon nanoparticles formed from ZIF-67@ZIF-8 as advanced electrode materials for high-performance asymmetric supercapacitors.

As a typical pseudocapacitance material, NiS is considered a promising electrode material due to its high theoretical specific capacitance and abundant reserves. However, the electrical conductivity is poor, resulting in a decrease in cycle stability and rate performance. Here, we introduce cobalt-containing porous nanocarbon (Co-NC) derived from zeolite-imidazolate frameworks (ZIFs) as a supporting base to design a hybrid structure. As an electrode material, NiS@Co-NC nanocomposite has a composite effect of double-layer capacitive porous carbon and pseudo-capacitance NiS nanoparticles and excellent electrochemical performance. Specifically, the specific capacitance of NiS@Co-NC nanocomposite is as high as 1116.6 F·g−1 when the current density is 1 A·g−1, and capacity retention is 90.177% at a very high current density of 10 A·g−1 after 5000 cycles. Moreover, the fabricated hybrid supercapacitor delivers an energy density of 21.6 Wh·kg−1 at 799.9 W·kg−1 with coulombic efficiency of 90.177%, and 14.22 Wh·kg−1 at a high power density of 7999.9 W·kg−1, along with excellent cyclic stability of 89.85% at 5 A·g−1 after 5000 cycles. All results indicate that NiS@Co-NC nanocomposites have the potential to be applied as electrodes in hybrid supercapacitors and other energy storage devices. ZIF-67 @ZIF-8 was synthesized through hydrothermal reaction and carbonized as a sacrificial template to generate cobalt-containing nano-carbon and carbon nanotubes. [Display omitted] • CNTs interconnected NiS@Co-containing porous carbon nanocomposite was synthesized. • The composite showed a strong synergistic effect of NiS, CNTs and metallic cobalt modified porous carbon. • NiS@Co-NC nanocomposite has a high specific capacitance of 1116.6 F.g-1 1 A.g-1. [ABSTRACT FROM AUTHOR]