<p>Poly(ethylene oxide) (PEO)-based all-solid-state polymer electrolytes (SPEs) hold significant promise for developing high-specific-energy and high-safety Li batteries, while still suffering from poor mechanical robustness and low Li⁺-conducting efficiency. Aramid nanofibers (ANFs), endowed with exceptional mechanical strength and abundant intramolecular/intermolecular interactions, are regarded as effective additives to improve SPE performance. However, the strictly symmetric interchain interactions within ANFs generate a highly ordered hydrogen-bond network, producing inert aggregates within the matrix and severely compromising electrolyte stability. To address these issues, a poly(ethylene glycol) (PEG)-mediated asymmetric interaction was constructed between ANF chains. By introducing PEG chains with weaker H-bonding acceptor sites, higher steric hindrance, and abundant lithiophillic groups, the simultaneous construction of rapid Li-ion channels and disruption of strong, symmetric interactions between ANF chains markedly improve interfacial compatibility and Li⁺ transport efficiency. The as-prepared electrolyte maintains excellent mechanical properties (yield stress of 3.25 MPa) while enabling stable cycling of Li∥Li symmetric cells for over 1600 h with low polarization voltage. The lithium cobaltate (LCO)∥Li cell with as-prepared electrolyte exhibits a capacity retention rate of 82.7% after 300 cycles at 1 C, which is remarkably higher than the unmodified counterpart (only 35.5%), achieving synergistic optimization of interfacial compatibility and mechanical performance.</p>