Hierarchical Co–Ni hydroxides integrated with carbon nanotubes via ZIF-67 templates for high-performance supercapacitors

Supercapacitors but suffer from low specific capacity and poor rate capability due to limited electrical conductivity. Herein, a zeolitic imidazolate framework (ZIF-67) was employed simultaneously as a cobalt source and a sacrificial template to direct the room-temperature hydrolysis of Ni²⁺ ions, leading to the formation of interwoven Co–Ni LDH nanosheets with enhanced electrolyte-electrode interaction and accelerated ion transport. Incorporation of carbon nanotubes (CNTs) markedly improved conductivity and charge-transfer kinetics, with the optimized CNC30 electrode delivering 870 F g⁻¹ at 1 A g⁻¹ and retaining 85% capacitance at 10 A g⁻¹. Electrochemical impedance spectroscopy confirmed a significant reduction in charge-transfer resistance from 1.37 Ω to 0.49 Ω upon CNT integration. Further enhancement was achieved by introducing ZIF-67, as CNCZ30 exhibited 902.7 F g⁻¹ at 1 A g⁻¹, with 72% retention at 10 A g⁻¹. Notably, CNCZ30 demonstrated excellent durability, maintaining 96.6% of its initial capacitance after 7000 cycles. These results highlight the synergistic effects of CNTs, LDHs, and ZIF-67 in boosting conductivity, active surface area, and redox activity, positioning Co–Ni LDH/CNT/ZIF-67 composites as promising electrodes for next-generation supercapacitors.