Confined templated-synthesized graphene/polyaniline hydrogel cathode integrated with aramid nanofiber hydrogel electrolyte toward high-performance Zn-ion hybrid supercapacitors

Zn-ion hybrid supercapacitors (ZIHCs) have attracted significant attention because of their affordability, battery-like capability and environment friendliness. However, their low specific capacity and irreversible dendrite growth have hindered the practical applications. Herein, graphene/polyaniline hydrogel (GPH5) cathode and aramid nanofiber/ZnSO₄ (ANF/ZnSO₄) hydrogel electrolyte are respectively fabricated via confined template polymerization in graphene/MnO₂ hydrogel and solvent exchange/immersing process in 2 M ZnSO₄ solution. The confined template strategy using MnO₂ as sacrificial template effectively avoids uneven aniline adsorption in graphene networks. The resulting GPH5 cathode presents rich electrochemical active sites and strong 3D crosslinked network with polyaniline nanofibers and nanofelts tightly anchoring on graphene sheets, achieving favorable specific capacity achieving 456.7 F g⁻¹ and high rate performance reaching even 84.5 % (1–20 A g⁻¹). As-prepared ANF/ZnSO₄ hydrogel electrolyte exhibits high ionic conductivity (3.02 S m⁻¹) and mechanical strength, enhancing the ion transport efficiency. Consequently, assembled ZHSCs efficiently suppress Zn dendrite growth and deliver outstanding specific capacity (311.3 F g⁻¹ or 147.0 mAh g⁻¹ at 1 A g⁻¹), high energy density (125.0 Wh kg⁻¹) and excellent power density (reaching 17000 W kg⁻¹). The results reveal ZHSCs consisting of GPH5 cathode and ANF/ZnSO₄ hydrogel electrolyte are promising in new electrochemical storage systems.