Construction of CoNi2S4@Ni(OH)2 Nanosheet Structures for Asymmetric Supercapacitors with Excellent Performance

It is crucial for energy storage devices to construct electrode materials with excellent performance. However, enhancing energy density and cycling stability for supercapacitors is a significant challenge. We successfully synthesized CoNi2S4@Ni(OH)2 nanosheets on the surface of Ni foam substrate by a two-step hydrothermal approach. The obtained products exhibit a remarkable areal capacitance of 1534 F g−1 at a current density of 1 A g−1. Moreover, even after 10,000 cycles, the specific capacitance remains 90% of its initial value, highlighting the exceptional long-term stability and durability. Furthermore, an asymmetric supercapacitor (ASC) device incorporating the CoNi2S4@Ni(OH)2 material shows remarkable electrochemical performance. It delivers an energy density of 58.5 mW h g−1 at a power density of 2700 W kg−1. The outstanding performance mainly arises from the selection of materials, the design of the structure, and the synergistic interaction between the materials. The result suggests that this material holds great potential as an energy storage material.