Molecular Bridging Creates an Interconnected Coordination Network for Continuous Li + Hopping in Polymer Electrolytes

Abstract

Fast and selective lithium ion (Li + ) transport in polymer electrolytes requires continuous, low‐barrier hopping pathways at room temperature. Here, we construct a multifunctional three‐dimensional polymer network in which solid succinonitrile (SN) dynamically couples adjacent ether and ester coordination sites, creating a bridge‐mediated, nanoscopically continuous Li + pathway. High‐field (up to 18.8 T) multinuclear multidimensional solid‐state nuclear magnetic resonance directly reveals that SN cooperates with polymer chains to form an interconnected coordination network. Acting as a dynamic molecular bridge, this network shortens Li─O transport distances to below 7 Å and accelerates Li + hopping. Meanwhile, boron‐containing moieties associate with bis(fluorosulfonyl)imide anions (FSI) and restrict their local mobility, enhancing Li + selectivity. Variable‐temperature measurements confirm accelerated local Li + dynamics with a correlation activation energy of 0.07 eV and suppressed anion motion. Consequently, the electrolyte delivers an ionic conductivity of 1.31 mS cm −1 and a Li + transference number of 0.61 at 30°C. It also enables stable cycling with high‐loading cathodes, retaining 89.8% capacity after 200 cycles with LiFePO 4 (12.9 mg cm −2 ) and robustly operating with LiNi 0.8 Co 0.1 Mn 0.1 O 2 (10.0 mg cm −2 ). This work establishes a molecular structure‐dynamics framework for regulating Li + hopping and provides a practical strategy for advanced polymer electrolytes through rational engineering of dynamic local coordination environments.