Low‐cost porous carbon materials prepared from peanut red peels for novel zinc‐ion hybrid capacitors

Abstract Zinc‐ion hybrid capacitors combine the advantages of supercapacitors and batteries and are a promising electrochemical energy storage device. In order to meet the demand for materials with higher energy density and longer cycle time, there is an urgent need to find a zinc‐ion supercapacitor cathode material with lower cost and better electrochemical performance. In this experiment, low‐cost agricultural peanut red skin waste was converted into biomass‐derived carbon material (PSR‐X) with high specific surface area, larger pore volume, and more homogeneous pore size distribution through carbonisation and KOH activation. Due to the interaction of these properties, PSR‐X as the cathode material has higher specific capacity and better multiplicity performance than the zinc‐ion capacitor prepared from the initial carbonised PSR as the cathode material. In addition, the PSR‐4‐based zinc‐ion capacitor has an excellent specific capacity of 86 mAh g −1 at a current density of 0.1 A g −1 , a high capacity retention of 55 % even at a high current density of 30 A g −1 , and a high energy density of 66.16 Wh kg −1 at a power density of 218.1 W kg −1 . What is more gratifying is that the capacitor exhibits an ultra‐long cycle life, with a high capacity retention rate of 85 % after 8,000 charge/discharge cycles at a current density of 1 A g −1 .