Insights of Zinc\nIon Storage in Chilli-Stem Derived\nPorous Carbon Enabling Ultrastability and High Energy Density of Zinc-Ion\nHybrid Supercapacitors

Aqueous zinc ion hybrid supercapacitors (ZIHSCs) are\npromising\nas low-cost and safe energy storage devices for next-generation applications.\nStill, their energy-power performance and durability are far from\nsatisfactory. Here, we present an energy-dense, and ultrastable ZIHSC\nrealized using activated porous carbons derived from chilli-stems.\nKOH activation resulted in a high specific surface area of 1710 m<sup>2</sup>/g, abundant mesoporous structure, and oxygen functionalities,\nwhich helped the KOH-activated carbon (CSK) to yield an impressive\nspecific capacity and energy density of 192 mA h/g and 172 W h/kg,\nrespectively, and makes it the top-performing ZIHSC in recent times.\nZIHSC’s cycling performance is exceptional, retaining over\n90% capacity even after 50,000 charge–discharge cycles. Molecular\ndynamics simulations reveal easy Zn ion diffusion through interconnected\nchannels and subsequent pore fillings within the carbon electrodes,\nrendering impressive performance. Simulations further reveal important\natomic interactions, demonstrating that higher currents drawn from\nthe device cause partial filling of pores and blockages in the channels\nand result in a decrease in the device’s specific capacity.\nBenefitted by CSK’s impressive performance, the aqueous Zn@pCu//CSK\nfull-cell device has demonstrated good energy-power densities (57.7\nW h/kg and 4.5 k W/kg) and durability over tens of thousands of cycles,\nfurther substantiating ZIHSCs’ application prospects in real\nlife.