Adsorption or Repulsion: Exploration of Regionally Confined Solid Polymer Electrolytes for Solid-State Lithium−Sulfur Batteries

Dissolution and shuttle of generated intermediates polysulfides (LiPSs) are intractable challenges for lithium–sulfur (Li–S) batteries equipped with solid polymer electrolytes (SPEs). Herein, several polyimide (PI) derivatives characterized by the introduction of additional functional groups were synthesized and employed as polymer matrices for fabricating regionally confined SPEs. The incorporated amide group in the polymer matrix is found to offer enhanced affinity to both Li + and LiPSs. Despite improved ionic conductivity, the fabricated adsorption-type SPE causes severe accumulation of sulfur species in the SPE and subsequently partial diffusion toward the Li anode. In contrast, inherited sulfonic acid group can strongly bind with Li + through electrostatic adsorption and simultaneously repel S n 2– via electrostatic repulsion. The harmonization of the cation coordination property and the anion repulsion ability not only promotes Li + migration and homogenizes Li deposition but also completely inhibits the entry of LiPSs into the SPE, facilitating their in situ conversion and eliminating the shuttle effect. Consequently, accelerated reaction kinetics, increased sulfur utilization, and extended cycle lifespan are demonstrated in the Li–S cells adopting the repulsion-type SPE coupled with high sulfur loading cathodes.