Biomass-derived wearable energy storage systems based on poplar tree-cotton fibers coupled with binary nickel–cobalt nanostructures

We demonstrated symmetric and asymmetric supercapacitors (SSCs and ASCs) based on core/shell-like Ni–Co oxide@cotton//Fe ₂ O ₃ –carbon nanotubes@cotton that are capable of storing a remarkable amount of energy, while retaining a high power density and long cycle life.