Tuning the Swelling and Dispersion of SPAN Enables High-Performance Li-S Batteries

Lithium-sulfur (Li-S) batteries have attracted significant attention due to their high energy density and low cost of raw materials. Although the SPAN cathode has better electrochemical performance than the traditional S₈/C composite, it is far from meeting the needs of commercialization, and its energy density, cycle stability, and rate performance need to be further improved. In this study, the swelling and dispersion of SPAN in different solvents are investigated for the first time by using different binders to optimize the electrode structure. The selection of water as a solvent can reduce the swelling of SPAN and inhibit cracking in the electrode preparation process, which effectively improves the structural stability of the electrode during the long-time charging and discharging process. The combination of CMC&SBR binder can reduce the agglomeration of active material and conductive carbon and contribute to the capacity of SPAN at a high current rate. As a result, the non-swelling SPAN with CMC&SBR binder exhibits a stable long cycling performance (83% capacity retention for 200 cycles at 1 C) and high rate performance (1192 mAh g^-1 at 5 C). In particular, the Li-S pouch cell is able to cycle stably for more than 50 cycles at 0.2 C under high loading (SPAN loading level of 7.2 mg cm^-2 and area capacity over 4 mAh cm^-2) with the specific capacity maintained at 1306 mAh g^-1. This work has the potential to promote the commercialization of Li-SPAN batteries.