Corona-shaped two-dimensional polyaramid derivatives for poly(ethylene oxide)-based all-solid-state lithium batteries†

Abstract

Solid polymer electrolytes (SPEs), especially those based on poly(ethylene oxide) (PEO), have garnered significant attention in the field of all-solid-state lithium batteries due to their high processability and low cost, advantages that are typically hard to achieve with their inorganic counterparts. However, their poor ionic conductivities have retarded their further application in all-solid-state lithium batteries. Herein, we report a series of corona-shaped two-dimensional polyaramid (2DPA) derivatives that improve the overall performance of PEO-based SPEs, including ionic conductivity, ion transference number, and electrochemical stability. We demonstrate that the unique corona topology, consisting of a rigid two-dimensional polyaramid core and flexible poly(ethylene glycol) (PEG) chains grafted at its periphery, effectively inhibits the crystallization of the PEO matrix through chain entanglement, thus enhancing ionic conductivity. Furthermore, the 2D polyaramid core provides enriched Lewis acidic binding sites for counter anions, suppressing the anion motion and resulting in selective lithium-ion transport. Therefore, a blend of 30% 2DPA-PEGs and PEO exhibits an enhanced room temperature ionic conductivity up to 4.39 × 10⁻⁵ S cm⁻¹ (an order of magnitude higher than that of the original SPE), an elevated lithium-ion transference number of 0.78, and a high oxidation voltage of 4.7 V (vs. Li/Li⁺). Meanwhile, the assembled all-solid-state batteries exhibit improved cycling performance and higher stability. Such a heterostructural polymer design strategy showcases the promising potential of novel 2D polymer derivatives for ion transport optimization in SPEs.