Ni-Co nanosheets supported on conductive “core” for integrated supercapacitor with high performance

Abstract

Developing supercapacitors with high energy density, fast charging rates, and superior cycle life is crucial to the ever-increasing electric energy storage. However, how to construct a new type of supercapacitors involving pseudocapacitive performance and electric double-layer capacitive performance and exhibiting enhanced electronic conductivity is still challenging. Here, hierarchical NixCo2x(OH)y@Ni@ZnO/ITO architecture is successfully fabricated by growing NixCo2x(OH)y nanosheets on surface of well-aligned Ni@ZnO nanorod using co-electrodeposition method. NixCo2x(OH)y with layered structure is wrapped like rippled silk and increases the specific surface area, which is crucial and benefit for fast ion adsorption/de-adsorption and fast surface redox reactions. Importantly, interlayer Ni serves as a nanostructured current collector and electronic conductor, playing an important role in rate capability. By virtue of structure features, the self-support NixCo2x(OH)y@Ni@ZnO/ITO as binder-free electrode for supercapacitors manifests higher specific capacitance (124mFcm−2 at 0.1mAcm−2, the mass of active material per square centimeter is typically in 100s micrograms). Furthermore, the NixCo2x(OH)y@Ni@ZnO/ITO exhibits remarkable cycling stability with about 95% specific capacitance retention after 5000 cycles. The results show that Ni-Co nanostructure constructed on surface of embedded conductive “core” materials is promising for high-energy supercapacitors.