Function of Ammonium Polyacrylate Binders for Long-Life Lithium/Sulfur Cells

The long cycle life of lithium-sulfur cells is strongly desired to leverage the sulfur's high specific capacity. In this study, we investigated the effects of the countercations of polyacrylate binders used in sulfur composite electrodes on the cycling performance of the lithium-sulfur cells. Lithium, sodium, and ammonium were compared as countercations. Sulfur electrodes were evaluated in terms of their mechanical strength, porous structure, and interaction with the polysulfide. The electrodes with an ammonium polyacrylate binder, which has high mechanical strength, could maintain a porous structure throughout cycling, resulting in the highest cycling performance. Moreover, the affinity of the ammonium polyacrylate with the polysulfide contributed to recovering some capacity by recapturing the polysulfide during the charge step.