Improved Cycling Performance Using a Poly-2-Acrylamido-2-Methylpropanesulfonic Acid (AMPS)-Based Crosslinked Gel Polymer on a Sulfur Cathode for Inhibiting the Dissolution of Polysulfide in a Li–S Battery

Abstract

In lithium–sulfur (Li–S) batteries, the impregnation of sulfur into electrically conductive materials of porous carbon plays a significant role in preventing the dissolution of lithium polysulfide (LiPS) into an electrolyte solution and improving cycling performance. However, this strategy does not render high-energy density to Li–S cells because of the limited amount of sulfur in porous carbon. Once the sulfur overflows out of porous carbon because of the significant volume change occurring during charge–discharge cycling, the LiPS formed outside porous carbon probably diffuses toward the anode, leading to poor cycling performance. In this study, the poly-2-acrylamido-2-methylpropanesulfonic acid (AMPS)-based polymer incorporated into the sulfur/porous carbon composite cathode in a Li–S cell effectively suppresses LiPS dissolution even when sulfur is present outside porous carbon, achieving good cycling performance with a capacity retention of 72% at the 100th cycle. Herein, the polymer used is poly-AMPS with a crosslinker of N-[tris(3-acrylamidopropoxymethyl)methyl]acrylamide, which is synthesized using 2-hydroxy-2-methylpropiophenone as the photoinitiator. The characteristics of the as-synthesized AMPS-based polymer and sulfur–carbon composite cathode are meticulously investigated by scanning electron microscopy–energy-dispersive X-ray spectrometry, transmission electron microscopy, dynamic light-scattering analysis, thermogravimetric analysis, and X-ray diffraction.

Recent interlayer and separator design approaches for high‐performance Li–S batteries

“…9,10 For example, there is a solution that encapsulates sulfur in carbon, but as the number of charge and discharge cycles increases, elution of sulfur occurs and the impedance increases. 19 Among them, the strategy of using separators and interlayers is a very attractive approach for LSBs. This is because their physical and chemical properties can be easily changed by direct modification, which can be used to directly influence the LiPS and effectively suppress the "shuttle effect," which is the biggest problem in LSBs.…”

“…There are several strategies to address this challenge, including cathode design and the use of host materials 9,10 . For example, there is a solution that encapsulates sulfur in carbon, but as the number of charge and discharge cycles increases, elution of sulfur occurs and the impedance increases 19 . Among them, the strategy of using separators and interlayers is a very attractive approach for LSBs.…”