Emulsion Binders with Multiple Crosslinked Structures for High-Performance Lithium-Sulfur Batteries

Lithium-sulfur batteries suffer a lot from the huge volume change and the shuttle effect. However, conventional poly(vinylidene fluoride) binder has intrinsic drawbacks, such as low ion conductivity, weak polysulfide-trapping ability, poor mechanical properties, and requirement of organic solvents. Herein, we designed a functional emulsion binder with multi crosslinked structure. Such a structure was formed by the covalent crosslinking within and between the emulsion particles, which facilitates the adapting of the volume expansion of sulfur cathode, thereby ensuring the integrity of electrodes. Besides, the polar functional groups endow the binder with strong chemisorption of lithium polysulfide and fast lithium-ion migration ability. Thus, the assembled lithium-sulfur battery displayed a high initial discharge capacity of 1246 mAh center dot g(-1) at 0.1 C, and a capacity fading rate of 0.04% per cycle after 500 cycles at 0.5 C. Even at a high sulfur mass loading of 4.8 mg center dot cm(-2), a high capacity of 956 mAh center dot g(-1) was still obtained at 0.2 C.

Automated summary

A functional emulsion binder with multi crosslinked structure was designed to solve the volume change and shuttle effect issues in lithium-sulfur batteries. The covalent crosslinking within and between the emulsion particles enabled the sulfur cathode to adapt to volume expansion, ensuring electrode integrity. The polar functional groups of the binder facilitated strong chemisorption of lithium polysulfide and fast lithium-ion migration. The assembled lithium-sulfur battery exhibited a high initial discharge capacity of 1246 mAh/g at 0.1 C, and a capacity fading rate of 0.04% per cycle after 500 cycles at 0.5 C. Even at a high sulfur mass loading of 4.8 mg/cm2, a high capacity of 956 mAh/g was still obtained at 0.2 C.