Multifunctional binder designs for lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries are promising next-generation high energy density batteries but their practical application is hindered by several key problems, such as the intermediate polysulfide shuttling and the electrode degradation caused by the sulfur volume changes. Binder acts as one of the most essential components to build the electrodes of Li-S batteries, playing vital roles in improving the performance and maintaining the integrity of the cathode structure during cycling, especially those with high sulfur loadings. To date, tremendous efforts have been devoted to improving the properties of binders, in terms of the viscosity, elasticity, stability, toughness and conductivity, by optimizing the composition and structure of polymer binders. Moreover, the binder modification endows them strong polysulfide trapping ability to suppress the shuttling and decreases the swelling to maintain the porous structure of cathode. In this review, we summarize the recent progress on the binders for Li-S batteries and discuss the various routes, including the binder combination use, functionalization, in-situ polymerization and ion cross-linking, etc., to enhance their performance in stabilizing the cathode, building the high sulfur loading electrode and improving the cyclic stability. At last, the design principles and the problems in further applications are also highlighted.