The rational design of solid fillers is an effective route to improve the electrochemical performance of solid polymer electrolytes (SPEs). Here we demonstrate that an Fe‐based metal organic framework, MIL‐88B‐NH 2 (Fe), with a fibrous structure, enhances both interfacial stability and ion transport when incorporated into SPEs. MIL‐88B‐NH 2 (Fe) is rich in open metal sites, which increase the ionic conductivity and the Li + transference number. In addition, a stable Fe 3+ /Fe 2+ interfacial layer derived from the MOF metal nodes provides electrostatic shielding, helping to suppress Li dendrite growth and maintain uniform Li deposition. As a result, the designed SPEs achieve an ionic conductivity of 1.1 × 10 −3 S cm −1 at 60°C and a Li + transference number of 0.33, enabling uniform Li + flux and stable cycling. Pouch‐type cells retain 153.7 mAh g −1 after 1500 cycles at 0.5 C and 60°C, highlighting the practical robustness of this electrolyte design.
Xu et al. (Wed,) studied this question.