A conjugated porous triazine-linked polyimide host with dual confinement of polysulfides for high-performance lithium-sulfur batteries.

Abstract

In the quest for next-generation energy storage solutions, lithium-sulfur (Li-S) batteries present exceptional potential due to their high energy density and cost-effectiveness. Nevertheless, significant challenges, such as the shuttle effect of lithium polysulfides (LiPSs) and inadequate sulfur utilization, have impeded their practical application. In this study, we report the design and synthesis of a novel covalent organic polymer that integrates a triazine-linked framework with carbonyl-enriched polyimide moieties, serving as a highly effective sulfur host for Li-S batteries. This engineered polymer not only provides abundant micropores for the physical confinement of LiPSs, but also facilitates robust chemical interaction through synergistic N-Li and O-Li bonding. The hierarchical porous architecture enhances sulfur loading, while the extended π-conjugation promotes rapid electron transport during LiPSs conversion. Consequently, the composite cathode achieves an impressive specific capacity of 1352 mAh g^-1 at 0.1C, along with sustained cyclic stability (453 mAh g^-1 after 400 cycles at 4C). These findings highlight the potential of multifunctional polymeric hosts in addressing critical limitations of Li-S batteries, offering a new blueprint for further developments in the field of high-performance energy storage systems.