Molecularly Designed Coordination Polymer Networks Enable Dynamic Interfacial Protection for High-Voltage Quasi-Solid-State Li Metal Batteries

Although quasi–solid–state lithium–metal batteries (QSSLMBs) coupled with high–Ni cathodes promise high energy density, their unstable electrode interfaces limit lifespan and safety. Here, we report a soluble coordination polymer network bearing Ni 2+ ion–imprinted polymer (IIP) functionality for dynamic interfacial protection of Ni–rich cathodes. Through rational macromolecular design, an imidazole–rich Ni 2+ IIP was engineered to preferentially adsorb on Ni–rich cathode surfaces. Further tailoring of the copolymer composition enables a stable and soluble IIP network that provides dynamic interfacial protection, which enhances the oxidative stability of conventional polyether electrolytes while unexpectedly accelerating interfacial kinetics. The design rationale was confirmed by in situ Fourier–transform infrared spectroscopy, in situ X–ray diffraction, 2D nuclear magnetic resonance spectroscopy, and other complementary characterizations. Thus, the synthesized IIP electrolyte enables durable Li||NCM811 operation at 4.5 V, with discharge capacities above 150 mAh g −1 at 3C and reliable cycling at −20°C. This polymer–network–mediated interfacial chemistry offers an effective route toward practical high-voltage QSSLMBs.