Laminar Composite Solid Electrolyte with Poly(Ethylene Oxide)‐Threaded Metal‐Organic Framework Nanosheets for High‐Performance All‐Solid‐State Lithium Battery

Abstract

Developing laminar composite solid electrolyte with ultrathin thickness and continuous conduction channels in vertical direction holds great promise for all‐solid‐state lithium batteries. Herein, a thin, laminar solid electrolyte is synthesized by filtrating –NH2 functionalized metal‐organic framework nanosheets and then being threaded with poly(ethylene oxide) chains induced by the hydrogen‐bonding interaction from –NH2 groups. It is demonstrated that the threaded poly(ethylene oxide) chains lock the adjacent metal‐organic framework nanosheets, giving highly enhanced structural stability (Young’s modulus, 1.3 GPa) to 7.5‐μm‐thick laminar composite solid electrolyte. Importantly, these poly(ethylene oxide) chains with stretching structure serve as continuous conduction pathways along the chains in pores. It makes the non‐conduction laminar metal‐organic framework electrolyte highly conductive: 3.97 × 10−5 S cm−1 at 25 °C, which is even over 25 times higher than that of pure poly(ethylene oxide) electrolyte. The assembled lithium cell, thus, acquires superior cycling stability, initial discharge capacity (148 mAh g−1 at 0.5 C and 60 °C), and retention (94% after 150 cycles). Besides, the pore size of nanosheet is tailored (24.5–40.9 Å) to evaluate the mechanisms of chain conformation and ion transport in confined space. It shows that the confined pore only with proper size could facilitate the stretching of poly(ethylene oxide) chains, and meanwhile inhibit their disorder degree. Specifically, the pore size of 33.8 Å shows optimized confinement effect with trans‐poly(ethylene oxide) and cis‐poly(ethylene oxide) conformation, which offers great significance in ion conduction. Our design of poly(ethylene oxide)‐threaded architecture provides a platform and paves a way to the rational design of next‐generation high‐performance porous electrolytes.