Molecular Engineering of Polymer Brushes Enables Lithium-Sulfur Battery Stable Operation under Ultra-Wide Temperature Range.

Abstract

Achieving stable operation under a wide temperature range is a critical target for the practical applications of lithium-sulfur batteries. However, intense lithium polysulfides (LiPSs) shuttling at high-temperature, sluggish sulfur species conversion, and inhomogeneous Li+ deposition at low-temperature severely impair the cycle lifespan of batteries. Herein, the multifunctional polymer brushes are fabricated by grafting anthraquinone-functionalized poly(glycidyl methacrylate) brushes on graphene surfaces (G-pGMAAQ) to simultaneously regulate the evolution of sulfur and lithium species. Combining theoretical calculations and experiments, it is revealed that G-pGMAAQ serves as a redox mediator that reduces the LiPSs conversion energy barrier, and its unique polar brush-like structure effectively inhibits LiPSs shuttling and homogenizes Li+ flow. Hence, G-pGMAAQ facilitates lithium-sulfur batteries stable operation in an ultra-wide temperature range (-40-70 °C). Furthermore, the Ah-level pouch cell achieves an energy density of 417 Wh kg-1, demonstrating the commercial potential of polymer brushes for lithium-sulfur batteries.