Imparting high robustness and suppression ability of shuttle effect to sulfur cathode in the Li-S battery via a novel multifunctional binder

To retard the performance degradation of sulfur cathode in lithium-sulfur (Li-S) batteries originating from severe volume variation and intermediate polysulfides shuttle effect during charge and discharge process, commercial polyacrylic acid (PAA) crosslinked by cationic hydroxypropyl polyrotaxane (HPRN+) is used as a water-based multifunctional binder (PAA-HPRN+) of the cathode for the first time. The assembled Li-S battery with the simple sulfur/carbon composite cathode adhered by PAA-HPRN+ displays an outstanding cycling specific capacity retention of 59.9% after 900 cycles at 1.0 C, and the corresponding capacity fading rate per cycle is 0.0446%, which are better than many reported values. Moreover, the cathode also exhibits excellent specific capacity and cycling stability even under high sulfur loading. The superior electrochemical properties are attributed to the slipping of the polyrotaxane that provides the binder with improved mechanical robustness and trapping capability of the soluble polysulfides that suppresses shuttle effect. The proposed design of the multifunctional binder may help to realize practical application of the Li-S battery. (C) 2020 Elsevier Ltd. All rights reserved.