Metal−Organic Framework Ion Conductor‐Based Polymer Solid Electrolytes for Long‐Cycle Lithium Batteries

Embedding MOFs in polymer matrices is a significant strategy for constructing high‐performance solid‐state electrolytes (SSEs). However, the uniformity and interfacial compatibility between MOFs particles and polymer affect their full function due to the physical blending method. Therefore, the development of uniform and stable MOFs/polymer SSEs is an inevitable challenge. Here, an in situ crosslinking strategy designed to build ion transport expressway network is introduced for highly stable hybrid electrolytes. Ion‐conductive MOFs are closely linked to the polyethylene glycol (PEG) chains via chemical bonds, which promotes the interface compatibility and Li+ transport capability. The resulting SSEs are endowed with high Li+ conductivity (2.12 × 10−4 S cm−1 at 25 °C), high potential window (5.23 V), and high Li‐ion transference number (0.75). Consequently, the above properties endow the Li|Li cells with stable stripping/plating under 0.1 mA cm−2 for 5600 h. The as‐built LiFePO4|Li cells using the as‐prepared SSEs deliver a satisfying capacity retention of 93.1% over 860 cycles under 2 C and 50 °C. Additionally, when cycled under 1 C and room temperature (RT), the LiFePO4|Li batteries produce a capacity of 134.9 mAh g−1 over 300 cycles. This study opens up a novel avenue for designing and developing advanced SSEs in solid batteries.