Unwrapping the potential of CoS and MoS₂ via heterostructure engineering for high-energy symmetric solid-state supercapacitor applications

The development of heterostructured multimetal sulfides offers a promising route to enhance supercapacitor performance by increasing redox-active sites and facilitating rapid ion/electron transport. Herein, we demonstrate the fabrication of a hybrid CoS/MoS₂ (CS/MS) nanosphered heterostructure grown on nickel foam via a facile hydrothermal method. This design maximizes electrochemically active surface area, promotes efficient interfacial charge transfer, and shortens ion diffusion pathways. As a binder-free electrode, the CS/MS heterostructure electrode exhibits a specific capacitance of 2013 F g^–1 at a current density of 1 A g^–1, which is approximately 2- to 4-fold higher than that of the individual unitary electrodes. Furthermore, the hybrid electrode achieves a maximum energy density and power density of ∼ 161 Wh kg⁻¹ and 7.2 kW kg⁻¹, respectively, while maintaining excellent capacitance retention of ∼ 96 % after 10,000 CD cycles. Interestingly, the fabricated solid-state CS/MS||CS/MS device delivers an admirable rate performance of ∼ 71 % at 10 A g^–1, a capacitance restoration capability of ∼ 93 %, and an improved energy density of ∼ 29.82 Wh kg⁻¹. In addition, the device demonstrates excellent endurance under continuous CV and CD cycling (85 % at 10 A g^–1), along with excellent coulombic efficiency (∼ 97 %), indicating strong potential as a high-performance supercapacitor material.