A novel flexible wire-shaped supercapacitor with enhanced electrochemical performance based on hierarchical Co(OH)2@Ni(OH)2 decorated porous dendritic Ni film/Ni wire

Wire-shaped supercapacitors, a new class of energy storage devices, have recently received enormous attention advantages of miniature size, lightweight and high flexibility. However, most of the reported wire-shaped supercapacitors are still suffered from low specific capacitance and limited energy densities as well as the relatively poor electrochemical performance. In this research, Co(OH)2@Ni(OH)2 nanosheets were successfully synthesized on the 3D-Ni film-coated Ni wire (NW) by electrochemical methods. The electrochemical tests of Co(OH)2@Ni(OH)2/3D-Ni/NW electrode confirmed the outstanding supercapacitive behavior of nanostructures with excellent cycling stability. This behavior could be attributed to 3D network structure of Ni film and the nanosheets which allow facile electrolyte and electrons transportation. Detailed electrochemical characterization shows that the Co(OH)2@Ni(OH)2/3D-Ni/NW exhibits a high specific capacitance of 355.2 C g–1 at current density of 1 Ag–1 and excellent cycle performance (80.0% retention after 3000 CD cycles). Also, the maximum energy density of 27.24 W h kg–1 at the power density of 234.99 W kg–1 was measured. The obtained results reveal that the Co(OH)2@Ni(OH)2 core-shell can be a promising electroactive material for supercapacitors. This unique supercapacitor opens up a new path in the development of fiber-shaped energy storage apparatuses.