Dual‐Mechanism Anchoring of Iodine Species by Pitch‐Derived Porous Carbon for Enhanced Zinc–Iodine Battery Performance
Siqi Zeng, Shuang Chen, Zhuoran Ao, Xiaolong Lin, Lijing Yan, Chenyu Liu, Zhan Lin
Abstract
Abstract Aqueous Zn‐I 2 battery is an overwhelming candidate for sustainable energy storage systems due to its high safety, low cost, and environmental friendliness. However, the serious self‐discharge and the shuttle effect initiated by soluble polyiodides significantly hinder further development. Herein, a pitch‐derived carbon (PPC MK ) with a unique micro‐/mesopores structure and abundant oxygen‐containing functional groups is prepared, with dual‐mechanism anchoring of iodine species to effectively confine the polyiodides for alleviating the above problems. The rich micropores of PPC MK (0.62 nm) function to inhibit the formation of I 3 − , and the large specific surface ar ea enables a high I 2 uptake of 64.51%. Moreover, oxygen‐containing functional groups of PPC MK further enhance the interaction with I 3 − to strengthen the polyiodide confinement. Therefore, the Zn‐I 2 batteries exhibit a high specific capacity of 236.76 mAh g −1 (4 mg iodine cm −2 ) with an average Coulombic efficiency of 99.73% at 1 C, low self‐discharge rate of 18.18% capacity loss after one‐week resting, and superior durability of 20 000 cycles at 20 C with 95.08% retentive capacity. Especially, the pouch cell exhibits a superior area capacitance of 5.51 mAh cm −2 at a high‐loading (30 mg iodine cm −2 ). This study provides an economically effective solution for the large‐scale production of high‐performance Zn‐I 2 batteries.