Cationic Imidazolium Sites: An Efficiency Strategy for Stabilizing High-Capacity Cathodes in Zinc-Iodine and Lithium-Sulfur Batteries.

Abstract

Aqueous zinc-iodine batteries (ZIBs) and lithium-sulfur batteries (LSBs) are promising energy-storage systems because of their high theoretical energy density and relatively abundant active materials. However, both systems suffer from severe shuttle effects and sluggish redox kinetics, which considerably hinder their practical applications. Here, an imidazolium-containing cationic covalent triazine framework (iCTF-BCIM) is rationally designed as a bifunctional host and catalyst to address common challenges of both ZIBs and LSBs. Specifically, the resulting iodine-loaded iCTF-BCIM cathode (I2@iCTF-BCIM) delivers an ultra-long cycling life of more than 100 000 cycles at 5 A g-1, with a capacity retention of 97.2% and a Coulombic efficiency approaching 100%. In situ and ex situ spectroscopic analyses demonstrate that the I2@iCTF-BCIM electrode undergoes a highly reversible iodine redox process. Furthermore, LSBs assembled with sulfur-loaded iCTF-BCIM cathode, denoted as S@iCTF-BCIM, deliver a high specific capacity of 1275 mAh g-1 at 0.2 C (1 C = 1675 mA g-1), along with remarkable cycling stability. More importantly, theoretical calculations combined with experimental results reveal that imidazolium-derived cationic environments contribute to regulating the adsorption and conversion behavior of electrochemical intermediates in both ZIBs and LSBs. This work demonstrates the applicability of iCTF-BCIM as a common host catalyst for both ZIBs and LSBs.