Biomass-derived porous carbon possesses several advantageous characteristics, such as low cost, inherent properties, and a controllable structure, making it an ideal electrode material for Zn-ion hybrid supercapacitors (ZIHSs). In this investigation, we used cattail leaves (CLs) as the carbon source and employed carbonization and activation techniques to fabricate porous carbon. We aimed to explore the correlation between the morphology, oxygen content, and defects in porous carbon derived from CLs under varying K2CO3 ratios. Remarkably, when the K2CO3/carbon ratio was adjusted to 2:1, the resulting porous carbon from CLs exhibited outstanding electrochemical performance in ZIHSs. These ZIHSs, functioning in an aqueous electrolyte, displayed impressive rate capability, achieving 158.3 mAh g−1 at 0.1 A g−1 and 60.2 mAh g−1 at 20 A g−1, along with a high energy density of 119.5 Wh kg−1. Furthermore, they exhibited exceptional long-term durability with nearly 100 % coulombic efficiency over 10,000 cycles. Additionally, a quasi-solid-state ZIHSs device demonstrated satisfactory specific capacity (148.54 mAh g−1 at 0.1 A g−1) and maintained stability under various orientations. The abundant, renewable, and cost-efficient biomass-derived carbon obtained in this study serves as a valuable guide for the development of portable energy storage devices that are both low in cost and high in performance, thereby contributing to sustainable energy solutions.
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