In Situ Polymer-Integrated Metal–Organic Framework for Solid-State Electrolyte Membrane

Solid-state lithium metal batteries hold great promise for energy storage by addressing the limited cycle life and safety issues inherent in liquid electrolyte systems. Nevertheless, the development of efficient solid-state electrolytes remains a significant challenge. In this work, we present an electrolyte membrane fabricated through the integration of metal-organic frameworks (MOFs) by in situ-formed polymer chains. Specifically, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) is employed to initiate the in situ polymerization of <i>N</i>,<i>N</i>-dimethylacrylamide within MOFs. The resulting polymer chains not only interconnect MOF particles to form a composite electrolyte membrane but also provide continuous ion-conductive paths for Li⁺ transport. Meanwhile, the confinement within the MOF channels restricts the mobility of bulky TFSI^- anions. As a result, the composite electrolyte membrane achieves a high room-temperature ionic conductivity exceeding 10^-4 S·cm^-1, a remarkable Li⁺ transference number of 0.77, and a broad electrochemical stability window up to 5.67 V. Furthermore, the electrolyte membrane demonstrates excellent interfacial compatibility with the lithium metal, effectively inhibiting dendrite growth. When applied in lithium metal batteries, it enables a specific capacity of 124.2 mAh·g^-1 at 1.0 C, a high Coulombic efficiency of 99.5%, and outstanding rate performance.