Ultrafast long-life zinc-ion hybrid supercapacitors constructed from mesoporous structured activated carbon

Zinc-ion hybrid supercapacitors (ZICs) with high capacity and long life provide an intelligent solution that will expand the scope of energy storage applications in the future. Nevertheless, activated carbon (AC) as a cathode material still encounters serious challenges because of the low ionic diffusion and transport ability due to its microporous structure and poor wettability during cycling, which leads to rapid capacity and life fading at high current densities. In this paper, we present an engineered surface of AC with a mesoporous structure and an improved wettability using a dehydrogenation process of polyvinylpyrrolidone for ultrafast long-life ZICs. The developed ZIC exhibits an excellent energy storage performance with a high specific capacity of 176 mAh g⁻¹ at a current density of 0.5 A g⁻¹ and an outstanding high-rate performance of 72 mAh g⁻¹ at 10 A g⁻¹, in addition to a robust ultrafast long life of over 40,000 cycles and a 78% capacity retention. The superior energy storage characteristics are strongly attributed to unique mesopores on the surface and an improved wettability that provide enlarged surface areas and facile ionic diffusion/transport capability of the AC cathode, demonstrating the promising potential of ZICs as next-generation supercapacitors.