A three-dimensional crosslinked chitosan sulfate network binder for high-performance Li–S batteries

Poor cycling performance caused by the shuttle effect of polysulfides is the main obstacle in the development of advanced lithium–sulfur (Li–S) batteries. Functional polymer binders with polar groups can effectively adsorb polysulfides chemically, thereby suppressing the shuttle effect. Herein, a robust three-dimensional crosslinked polymer network, which demonstrates excellent mechanical property and strong affinity for polysulfides, is prepared by the aldimine condensation and coordination reactions. The crosslinked chitosan sulfate network (CCSN) significantly enhances the cycling performance and rate capability of the sulfur cathode. The CCSN-based sulfur cathode exhibits a high initial discharge capacity of 824 mAh g−1 with only 0.082% average capacity loss per cycle at 1 C. At a high rate of 4 C, the cathode exhibits a high capacity retention of 84.8% after 300 cycles. Moreover, the CCSN-based sulfur cathode exhibits an excellent cycling performance at a high sulfur loading of 2.5 mg cm−2, which indicates the excellent mechanical strength and binding performance of the CCSN binder for high-energy density Li–S batteries. This study demonstrates a viable approach for developing high-performance Li–S batteries for practical application.