Facile synthesis of mesoporous hierarchical ZnS@β-Ni(OH)2 microspheres for flexible solid state hybrid supercapacitors

Abstract

Mesoporous hierarchical ZnS@β-Ni(OH)₂ microspheres have been successfully synthesized via a facile route. In the synthesis process, ZnS spheres are used as the templates for the direct growth of β-Ni(OH)₂ nanosheets on their surface. Owing to their unique structure and composition, when the mesoporous hierarchical ZnS@β-Ni(OH)₂ microspheres were utilized as electrode materials for supercapacitors, which exhibited substantially enhanced specific capacitance (1361.7 F g⁻¹ at 4.0 A g⁻¹) compared with ZnS and β-Ni(OH)₂. Furthermore, a flexible solid state hybrid supercapacitor was assembled by using mesoporous hierarchical ZnS@β-Ni(OH)₂ microspheres as a positive electrode and activated carbon as a negative electrode. The resulting flexible solid state device showed a specific capacitance of 170.97 mF cm⁻² at 2.0 mA cm⁻², and offered a volumetric energy density of 0.783 mW h cm⁻³ and a power density of 45.7 mW cm⁻³. Impressively, the device displayed good mechanical flexibility under various bending angles from 0° to 180°. This study presents a novel and promising electrochemically active material for supercapacitors.