Vertically Aligned Supramolecular Host–Guest Complexes of Sulfobutyl Ether β-Cyclodextrin Enable Multi-Pathway Ion Transport in Composite Polymer Electrolytes

Composite polymer electrolytes (CPEs) are promising for lithium-metal batteries, but randomly dispersed fillers often create discontinuous and tortuous Li+ transport pathways. Here, a supramolecular host–guest complex (SBE-β-CD-DEC) was constructed by encapsulating diethyl carbonate (DEC) within sulfobutyl ether β-cyclodextrin (SBE-β-CD) and aligned in a PUA/PEGDA matrix under an alternating electric field. The resulting architecture spatially connected DEC-rich confined regions with filler/polymer interfaces, establishing multiple continuous, low-tortuosity Li+ transport pathways. The aligned electrolyte exhibited an ionic conductivity of 5.09 × 10−4 S cm−1, a Li+ transference number of 0.58, and an apparent activation energy of 0.11 eV. Multiphysics simulations indicated the highest local current density in DEC-rich confined regions, followed by filler/polymer interfaces, supporting their cooperative contribution to Li+ transport. Li||Li cells cycled stably for over 1200 h at 0.1 mA cm−2, while Li||LiFePO₄ cells retained 97.5% capacity after 400 cycles at 0.5 C. This work demonstrates an effective supramolecular confinement–alignment strategy for constructing continuous multipathway ion-transport networks in CPEs.