Lithiated carboxylated nitrile butadiene rubber with strong polysulfide immobilization ability as a binder for improving lithium-sulfur battery performance

We report the first use of lithiated carboxylated nitrile butadiene rubber (XNBR-Li) as a functional binder for the sulfur cathode of lithium sulfur batteries (LSBs). XNBR-Li has strong adhesion to sulfur and carbon black particles, forming a uniformly dispersed and robust sulfur cathode structure. Furthermore, due to the presence of the -COOLi groups, XNBR-Li has shown a strong ability to trap lithium polysulfides (LPS), which greatly helps to suppress the shuttle effect of LPS in LSBs. The cyclic voltammetry and electrochemical impedance spectroscopy data indicate that the use of XNBR-Li as the binder can accelerate Li+ diffusion kinetics in the sulfur cathode. As a result, the XNBR-Li-based cathode delivers a high capacity of 1140 mAh g(-1) at 0.2 C, high rate performance with a capacity of 729 mAh g(-1) at a high rate of 2 C, and excellent long-term cycling stability with a slow capacity decay rate of 0.04% per cycle at 0.5 C over 500 cycles.