Sulfur and Nitrogen Dual Heteroatom Synergistic Enhanced Organic Cathodes toward High-Performance Aqueous Zn-Organic Batteries

Aqueous zinc-ion batteries (AZIBs) stand out among various battery technologies, although high-performance cathode materials are still urgently needed. Sulfur-containing organic materials have been proven to be excellent electrode materials for AZIBs. A thiazine-naphthoquinone (DDT, 6,13-dihydrodibenzo[b,i]thiazines-5,7,12,14-tetrone) has been synthesized as organic cathode material based on a dual heteroatom regulation strategy. To further investigate the regulatory role of nitrogen atom, a nitrogen-methylated DDT, DMT (6,13-dihydro-13-methyldibenz[b,i]thiazines-5,7,12,14-tetrone), has been synthesized afterward. The sulfur atom of thiazine not only decreases solubility but also imparts good flexibility to the molecules. Moreover, the nitrogen atom improves the dynamic performance in aqueous electrolytes. The dual heteroatom doping gives these cathode materials an excellent electrochemical performance. Therefore, DDT//Zn and DMT//Zn batteries exhibit good rate performance, cycle life, and stability in 2.0 M Zn(ClO4)2 electrolytes. DDT//Zn and DMT//Zn batteries have high capacities of 225.6 and 186.3 mAh g–1 at 0.05 A g–1, respectively, and can maintain discharge capacities of 91.8 and 90.1 mAh g–1 at 20.0 A g–1. Due to regulation of the methyl group on nitrogen, DMT//Zn batteries exhibit a higher capacity retention rate, with 88.9% following 5000 cycles at 10.0 A g–1. The dual heteroatom regulation strategy would provide more choices and materials for the AZIBs.