Elastic rubber-containing multifunctional binder for advanced Li-S batteries

Abstract Li-S batteries (LSBs) are considered as next-generation energy-storage devices because of their high energy density. However, long-term use of LSBs is limited by the volume changes of sulfur and the shuttle effect. To address these issues, a multifunctional polymer binder is developed by combining a commercial binder and elastic rubber. Poly(vinyl pyrrolidone) (PVP) is used as the main binder, and carboxylated nitrile butadiene rubber (XNBR) is added to enhance its mechanical toughness and adsorb soluble lithium polysulfides. The XNBR is vulcanized with S to enhance its mechanical properties and chemical polarity. The combination of PVP and crosslinked-XNBR allows control of the volume change of sulfur, regulates soluble polysulfides, and ensures the good dispersion of the electrode material. LSBs with the proposed binder exhibit a remarkable battery-performance improvement of 300% after 500 cycles at 1C compared with an LSB using a PVP binder, as well as cycle stability, with a small capacity decay of 0.02% per cycle at 1C for 1000 cycles.