Decoupling‐Induced Competition and Re‐Equilibration in Li ⁺ ‐Coordination: Mechanistic Insights into Interfacial Stabilization of Microphase‐Separated Polymer Electrolytes

ABSTRACT Achieving high ionic conductivity and stable interfacial layers remains a significant challenge in designing polymer electrolytes for lithium metal batteries. This study proposes a strategy that addresses these limitations by decoupling competitive interactions and reconstructing a balanced Li ⁺ coordination environment. Specifically, succinonitrile (SN) and lithium difluorophosphate (LiDFP) were incorporated into an ether‐rich polymer matrix. SN promotes lithium salt dissociation while it simultaneously engages in competitive coordination with oxygen‐containing groups on the polymer chains, decoupling and releasing more Li ⁺ from the polymer chain to enhance ionic conductivity. Meanwhile, PO ₂ F ₂ ⁻ weakens the strong SN‐Li ⁺ coordination in the solvated sheath layer, partially replacing SN molecules to reconstitute a stable weakly solvated structure. This dual‐regulation mechanism of Li ⁺ decoupling competition and coordination reconstruction establishes a more balanced Li ⁺ coordination environment, which enables fast Li ⁺ transport within the electrolyte and uniform interfacial deposition. The resulting electrolyte, S _0.5 TPE‐P, exhibits an impressive ionic conductivity of 1 mS cm ⁻¹ . An NCM811‖lithium cell utilizing this electrolyte retains 86% of its initial capacity after 500 cycles at 3C. Furthermore, even when paired with the high‐nickel‐content LiNi _0.9 Co _0.05 Mn _0.05 O ₂ (NCM90) cathode material, or operated at 0°C, the electrolyte also maintains robust cycling stability, highlighting its broad applicability and operational resilience.