Chemical and spatial dual-confinement engineering for stable Na-S batteries with approximately 100% capacity retention
Yong Zhang, Xinyi Guo, Qi Yang, Yuan Shao, Yadong Du, Jun Qi, Ming Zhao, Zhengjie Shang, Yuhan Hao, Yongchao Tang, Ying Li, Riguang Zhang, Baojun Wang, Jieshan Qiu
Abstract
Sodium-sulfur (Na-S) batteries are attracting intensive attention due to the merits like high energy and low cost, while the poor stability of sulfur cathode limits the further development. Here, we report a chemical and spatial dual-confinement approach to improve the stability of Na-S batteries. It refers to covalently bond sulfur to carbon at forms of C-S/N-C=S bonds with high strength for locking sulfur. Meanwhile, sulfur is examined to be S 1 -S 2 small species produced by thermally cutting S 8 large molecules followed by sealing in the confined pores of carbon materials. Hence, the sulfur cathode achieves a good stability of maintaining a high-capacity retention of 97.64% after 1000 cycles. Experimental and theoretical results show that Na + is hosted via a coordination structure (N···Na···S) without breaking the C-S bond, thus impeding the formation and dissolution of sodium polysulfide to ensure a good cycling stability. This work provides a promising method for addressing the S-triggered stability problem of Na-S batteries and other S-based batteries.