Polymeric binders for the sulfur electrode compatible with ionic liquid containing electrolytes

A novel ionic liquid-containing electrolyte has been demonstrated to improve charging efficiency, lifetime and safety of Li/S cells. However, the high viscosity of the ionic liquid can reduce the kinetics of the electrochemical process and degrade the wettability the S electrode by the electrolyte, which limits electrochemical utilization of the active S. To realize the advantages of the ionic liquid in the electrolyte, while maintaining good cell performances, we have investigated the critical properties of polymeric binders such as polyvinylidene fluoride (PVDF), styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), polyacrylic acid (PAA) and lithium polyacrylate (LiPAA) for the S electrode operated in ionic liquid-containing electrolytes. The PAA binder electrode showed the most promising cell performance which is attributed to its good physical stability and wettability. Moreover, the cell performance of the PAA binder electrode was further improved by combining the PAA binder with the PVDF binder, which enhances the specific capacity up to 1.3 times higher than that of the PAA binder electrode.