Descriptor-Guided Dynamic Solvation-Shell Reconstruction Enables PEO-Based Polymer Electrolytes With 10.9 mS cm-1 Ionic Conductivity.

High-voltage polymer electrolyte lithium metal batteries have long been constrained by the intrinsically low ionic conductivity of polymer electrolytes and unstable high-voltage cathode interfaces, especially at low temperatures where ion transport and interfacial kinetics become sluggish. Here, we propose a descriptor-guided dynamic solvation-shell reconstruction strategy for poly(ethylene oxide) (PEO)-based quasi-solid electrolytes by introducing nitrile plasticizers with competitive Li+ affinity and fast local Li+ diffusivity. These nitrile ligands competitively enter the first Li+ solvation shell, weaken persistent Li+-ether oxygen coordination, and shift Li+ migration from polymer-cage-confined hopping to ligand-exchange-assisted transport. The optimized electrolyte achieves a room-temperature ionic conductivity of 10.9 mS cm-1, nearly three orders of magnitude higher than that of the pristine PEO electrolyte. Meanwhile, the nitrile-containing solvation shell regulates interfacial decomposition pathways, suppresses oxidative PEO degradation in high-voltage Li‖NCM811 cells, and promotes the formation of compact cathode electrolyte interphases. Benefiting from simultaneously enhanced bulk Li+ transport and high-voltage interfacial stability, the optimized electrolyte enables stable fast-charging cycling and low-temperature operation in Li‖NCM811 cells. This work establishes descriptor-guided dynamic first-solvation-shell reconstruction as a molecular design principle for high-conductivity, high-voltage-stable PEO-based quasi-solid electrolytes.