Designing intimately interconnected neuron-shaped nickel-copper(I) sulfide nanocomposites as cathode material for supercapacitors

Abstract

Nanostructured transition metal sulfides have attracted significant attention as pseudocapacitance materials owing to their high specific capacitance and improved conductivity compared to oxides. Bimetallic nickel‑copper(I) (NiCu) sulfides are promising candidates for use in asymmetric supercapacitors because of their high specific capacitance, wide voltage range, and high conductivity. In this study, we synthesize neuron-shaped Ni-Cu(I) sulfide nanocomposites with intimate interconnectivity via the sulfidation and ion exchange of Ni-Cu(I) carbonate hydroxide, prepared by a straightforward hydrothermal process. The product's unique structure, featuring a neuronal network, exhibits a high specific capacitance of 1226.5 F g−1 at 1 A g−1 and an excellent cycling stability (88.97 % capacitance retention after 5000 cycles), which is attributed to the coexistence of bimetallic components and an inherently interconnected neuron-shaped configuration that prevents structural collapse and self-aggregation, while providing easy electrolyte accessibility. Furthermore, an asymmetric supercapacitor with a Ni-Cu(I) sulfide cathode material demonstrates a maximum power and energy densities of 9000 W kg−1 and 23.99 Wh kg−1, respectively, with an initial capacity retention rate of 83.69 % after 5000 cycles. The distinctive structural features of Ni-Cu(I) sulfides enhance the energy storage capabilities of the nanomaterials, enabling the development of portable electronic devices.