In-situ polymerized cross-linked binder for cathode in lithium-sulfur batteries

Volume expansion and polysulfide shuttle effect are the main barriers for the commercialization of lithium-sulfur (Li-S) battery. In this work, we in-situ polymerized a cross-linked binder in sulfur cathode to solve the aforementioned problems using a facile method under mild conditions. Polycarbonate diol (PCDL), triethanolamine (TEA) and hexamethylene diisocyanate (HDI) were chosen as precursors to prepare the cross-linked binder. The in-situ polymerized binder (PTH) builds a strong network in sulfur cathode, which could restrain the volume expansion of sulfur. Moreover, by adopting functional groups of oxygen atoms and nitrogen atoms, the binder could effectively facilitate transportation of Li-ion and adsorb polysulfide chemically. The Li-S battery with bare sulfur and carbon/sulfur composite cathodes and cross-linked PTH binder displays much better electrochemical performance than that of the battery with PVDF. The PTH-bare S cathode with a mass loading of 5.97 mg/cm2 could deliver a capacity of 733.3 mAh/g at 0.2 C, and remained 585.5 mAh/g after 100 cycles. This in-situ polymerized binder is proved to be quite effective on restraining the volume expansion and suppressing polysulfide shuttle effect, then improving the electrochemical performance of Li-S battery.