Insights of Zinc Ion Storage in Chilli-stem Derived Porous Carbon Enabling Ultra-stability and High Energy Density of Zinc-Ion Hybrid Supercapacitors: Nature inspired supercapacitors

Aqueous zinc ion hybrid supercapacitors (ZIHSCs) with carbon cathodes show significant potential as next-generation high-performance energy storage devices due to their excellent energy-power densities and ultralong cycle stability traits. Here, an energy-dense and ultra-stable ZIHSC is realized using ultrathin mesoporous carbons derived from chilli-stems. Results suggest that the activation process via Zn(NO3)2 and KOH boosts the surface area and pore structures of the resultant carbons. Notably, the KOH-activated carbon (CSK) with the highest specific surface area of 1710 m2/g, abundant mesoporous structure, and suitable oxygen content generates an impressive specific capacity of 192 mAh/g at 0.5 A/g and an outstanding energy density of 172 Wh/kg, which is the top-performing ZIHSC in recent times. The ZIHSC also retained over 90% capacity even after 50,000 charge-discharge cycles. Molecular dynamics simulations to analyze the charge storage mechanism of Zn ions in porous carbon electrode. The simulations revealed important atomic interactions, demonstrating that higher current drawn from the device causes partial filling of pores and blockages within the porous carbon electrode channels. This results in a decrease in the ZIHSC device’s specific capacity. The cathode’s performance is further validated in an aqueous Zn@pCu//CSK full-cell device, which demonstrates a remarkable energy density (57.7 Wh/kg with 180 W/kg) and stability over tens of thousands of cycles. The full ZIHSC devices are effective in powering light-emitting diodes, further substantiating their application prospects in real-life