Hybrid supercapacitors using metal-organic framework derived nickel-sulfur compounds

Metal-organic frameworks (MOFs) are highly suitable precursors for supercapacitor electrode materials owing to their high porosity and stable backbone structures that offer several advantages for redox reactions and rapid ion transport.

In this study, a carbon-coated Ni₉S₈ composite (Ni₉S₈@C-5) was prepared via sulfuration at 500 ℃ using a spherical Ni-MOF as the sacrificial template.

The stable carbon skeleton derived from Ni-MOF and positive structure-activity relationship due to the multinuclear Ni₉S₈ components resulted in a specific capacity of 278.06 mAh·g^-1 at 1 A·g^-1. Additionally, the hybrid supercapacitor (HSC) constructed using Ni₉S₈@C-5 as the positive electrode and the laboratory-prepared coal pitch-based activated carbon (CTP-AC) as the negative electrode achieved an energy density of 69.32 Wh·kg^-1 at a power density of 800.06 W·kg^-1, and capacity retention of 83.06 % after 5000 cycles of charging and discharging at 5 A·g^-1. The Ni-MOF sacrificial template method proposed in this study effectively addresses the challenges associated with structural collapse and agglomeration of Ni₉S₈ during electrochemical reactions, thus improving its electrochemical performance. Hence, a simple preparation method is demonstrated, with broad application prospects in supercapacitor electrodes.