High-Performance Cellulosic Solid-State Electrolytes: Engineering the Li + Transference Number and Deciphering Conduction Mechanisms

A novel cellulose-based solid polymer electrolyte (Cell-TFSI) was developed through strategic grafting of trifluoromethanesulfonimide (-TFSI) groups onto the cellulose backbone, simultaneously achieving a high Li+ transference number (0.79), room-temperature ionic conductivity (1.12 × 10–4 S cm–1), and mechanical strength (21.65 MPa). Dielectric relaxation spectroscopy and molecular dynamics simulations reveal that weakly coordinated solvation structures between Li+ and sulfonyl/carbonyl oxygens enable a dominant hopping-decoupled ion transport mechanism. Density functional theory calculations demonstrate superior Li+ affinity for -TFSI groups (ΔEAbs. = −7.167 eV) compared to hydroxyl groups (−4.457 eV). The cell-TFSI electrolyte forms an in situ LiF-rich solid electrolyte interphase that enables stable lithium plating/stripping cycling for over 1000 h. This work establishes a universal weak solvation and anion immobilization design principle for sustainable, high-performance solid-state polymer electrolytes.