Highly ordered, polypyrrole-coated Co(OH)2 architectures for high-performance asymmetric supercapacitors

Abstract

Metal oxide structures consisting of uniformly close-packed components are attractive in energy storage systems due to advantages from their unique structures, such as high loading amount of active materials and relatively large surface area. Here, we report the fabrication of highly ordered metal oxide nanosheet-based architectures composed of Co(OH)₂ nanosheets on carbon cloth for application in a supercapacitor electrode. In addition, polypyrrole (PPy) is coated on the Co(OH)₂ surface by vapour deposition polymerization (VDP) to obtain high rate performance and low resistance of the active material. Then, the PPy-coated Co(OH)₂-based nanosheets are assembled within a PVA–KOH polymer electrolyte as the positive electrode of solid-state asymmetric supercapacitors (ASCs). The energy storage device based on this architecture exhibits high electrochemical performance (27.4 F cm⁻³ capacitance and 10.53 mW h cm⁻³ energy density) with superb cycle stability.