High-performance supercapacitors based on NiMn layered double hydroxides/Ni₃S₂ nanocomposite

Layered double hydroxide (LDH), an emerging electroactive material, receives significant attention in storage and energy conversion area due to its excellent ion insertion and exchange capacity. Transition metal sulfides with multiple oxidation states and redox reactions maintain high-power density. In this research, NiMn-LDH on transition metal sulfides M − S (M = Ni, Co, Mn, Fe) are synthesized. Of these, NiMn-LDH/Ni₃S₂ demonstrates excellent electrochemical efficiency. In the three-electrode system, NiMn-LDH/Ni₃S₂ electrode achieves high specific capacitance of 2028.38 mF cm⁻² at 1 mA cm⁻² and excellent cycling stability of 69.53 % retention after 5000 cycles at 10 mA cm⁻². The device consisting of activated carbon and NiMn-LDH/Ni₃S₂ exhibits a remarkable energy density of 63.06 Wh kg⁻¹ at a power density of 1599.94 W kg⁻¹. The NiMn-LDH/Ni₃S₂ electrode demonstrates an effective pseudo-capacitance performance and holds a great promise for electrodes in capacitive energy storage devices.