Bifunctional polymer binders featured with both strong binding and superior polysulfide trapping properties are highly desired for the fabrication of sulfur cathodes with suppressed polysulfide shuttling in Li-S batteries. In this paper, we have explored the potential of a quaternary ammonium cationic polymer, polydiallyldimethylammonium (PDADMA-X; X = T, B, P, and Cl) with different counter anions (TFSI-, BF4-, PF6-, and Cl-, respectively) as the bifunctional binder. We have also revealed the dramatic effects of the counter anion on the performance of the cationic polymer binder. PDADMA-X's containing the former three weakly associating anions have been demonstrated to show polysulfide adsorption capability. In particular, PDADMA-T having the largest, least interacting TFSI- anion shows the optimum performance, with strong binding strength and the best polysulfide adsorption capability. Relative to commercial PVDF and PDADMA-X's of other counter anions, it offers sulfur cathodes with lowered polarization, higher discharge capacity, significantly better capacity retention, and improved cycling stability. With its convenient synthesis from commercially available PDADMA-Cl, cationic PDADMA-T having the TFSI- anion is a promising bifunctioal binder for sulfur cathodes in practical Li-sulfur batteries. (c) 2017 Elsevier Ltd. All rights reserved.