Bioinspired Binders Actively Controlling Ion Migration and Accommodating Volume Change in High Sulfur Loading Lithium–Sulfur Batteries

摘要

High-loading lithium-sulfur batteries have gained considerable fame for possessing high area capacity, but face a stern challenge from capacity fading because of serious issues, including "polysulfides shuttling," insulating S/Li2S, large volume changes, and the shedding of S/C particles during drying or the cell encapsulation process. Herein, a bioinspired water-soluble binder framework is constructed via intermolecular physical cross-linking of functional side chains hanging on the terpolymer binder. Experimental results and density-functional theory (DFT) calculations reveal that this network binder featuring superior volume change accommodation can also capture lithium polysulfides (LiPSs) through strong anchoring of O, N+ actives to LiPSs by forming Li center dot center dot center dot O and N+center dot center dot center dot S-x(2-) bonds. In addition, the abundant negative charged sulfonate coordination sites and good electrolyte uptake of the designed binder endow the assembled cells with high lithium ion conductivity and fast lithium ion diffusion. Consequently, a remarkable capacity retention of 98% after 350 cycles at 1 C and a high areal capacity of 12.8 mA h cm(-2) with high sulfur loading of 12.0 mg cm(-2) are achieved by applying the environmentally friendly binder.