Hierarchical NiCoS@Nickel-Cobalt Layered Double Hydroxide Nanotube Arrays on Metallic Cotton Yarns for Flexible Supercapacitors.

Constructing high capacitance active materials and three-dimensional (3D) conductive networks inside textile yarn frames is a promising strategy to synthesize yarn supercapacitor electrodes. In this study, growing NiCoS@Ni-Co layered double hydroxide (LDH) nanotube arrays on Au-metalized cotton yarns yields a novel yarn supercapacitor electrode material. The resulting yarn electrode possesses numerous merits, including high electrical conductivity from NiCoS and Au-metalized cotton yarns, high capacitance of Ni-Co LDH nanosheets, and the 3D hierarchical electrode structure. The unique electrode structure leads to excellent electrochemical properties including high capacitance (5680 mF cm), excellent rate performance, and stable cycling performance. A two-ply symmetric yarn supercapacitor assembled from the NiCoS/Ni-Co LDH/Au/cotton yarn electrode reaches an areal energy density of 3.5 μW h cm.