Hierarchical poly(2-aminothiophenol)/Co–Ni heterostructures with nanoflake–nanoneedle architecture for high-performance supercapacitors

The present study reports a hierarchical supercapacitor electrode that integrates poly(2-aminothiophenol) (P2-ATH) with a cobalt–nickel heterostructure comprising cobalt carbonate hydroxide hydrate (CCHH) and cobalt-nickel oxide (CNO). The hybrid is synthesized by hydrothermal growth of CCHH/CNO nanoneedles, followed by in situ oxidative polymerization of P2-ATH to yield conformal nanoflakes. This interpenetrating architecture furnishes a porous, electrically percolated network that shortens ion-diffusion paths and accelerates electron transport, thereby coupling the redox activity of P2-ATH with the multiple Faradaic sites of the Co–Ni phase. Electrochemical tests in different electrolytes (NaOH, NaCl, and HCl) demonstrate a strong electrolyte dependence, with 0.5 M HCl yielding the best performance. At 0.4 A g$^{−1}$, the specific capacitance reaches 113.87 F g$^{−1}$ in HCl, compared with 27.89 F g$^{−1}$ in NaOH and 7.73 F g$^{−1}$ in NaCl. In 0.5 M HCl, the electrode delivers an energy density of 5.69 Wh kg$^{−1}$ at a specific power of 479.7 W kg$^{−1}$. The results highlight the synergistic interplay between the conductive P2-ATH and the Co–Ni nanoneedle, establishing P2-ATH/CNO-CCHH as a promising platform for high-rate, durable supercapacitors and broader electrochemical energy-storage applications.