Elucidation of Li+ Conduction Behavior in MOF Glass Electrolyte Toward Long‐Cycling and High C‐Rate Lithium Metal Batteries

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Abstract Vitrified metal–organic frameworks (MOFs) are promising solid‐state electrolytes for lithium metal batteries due to their unique structures. Nevertheless, the effect of distorted molecular structures in glassy MOFs on Li+ migration behavior at the molecular level remains largely unexplored, posing a huge obstacle to further boosting their electrochemical performances. Herein, Li+ conduction behavior in glassy ZIF‐62 quasi‐solid‐state electrolyte (GZ‐62‐QSSE) is molecularly elucidated, in which Li+ migration is accomplished by the continuous delivery of N sites in imidazole and benzimidazole ligands like the process of relay race. Such fast Li+ migration in GZ‐62‐QSSE demonstrates more than 1.5‐time increase in transference number and helps to generate inorganic‐dominated cathode/anode interphases for unblocked ion transport compared with crystalline ZIF‐62 electrolyte. Consequently, the long‐term stability with remarkable high‐rate capability is realized in the proof‐of‐the‐concept full cells, which represents one of best values among all reported MOF‐based solid‐state batteries. For example, LiFePO4 ||Li full cells employing GZ‐62‐QSSE brilliantly undergo 3000 cycles with high initial capacity of 132.1 mAh g−1 and ultralow decay rate of 0.009% at 1 C. Full cells still display high discharge capacity of 83.6 mAh g−1 at 5 C. The elaborated high‐performance glassy ZIF‐62 electrolyte offers new insights for exploiting advanced solid‐state electrolytes and propels the development of solid‐state lithium metal batteries.

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