Nanostructured Metal–Organic Framework (MOF)‐Derived Solid Electrolytes Realizing Fast Lithium Ion Transportation Kinetics in Solid‐State Batteries

Solid‐state batteries are hindered from practical applications, largely due to the retardant ionic transportation kinetics in solid electrolytes (SEs) and across electrode/electrolyte interfaces. Taking advantage of nanostructured UIO/Li‐IL SEs, fast lithium ion transportation is achieved in the bulk and across the electrode/electrolyte interfaces; in UIO/Li‐IL SEs, Li‐containing ionic liquid (Li‐IL) is absorbed in Uio‐66 metal–organic frameworks (MOFs). The ionic conductivity of the UIO/Li‐IL (15/16) SE reaches 3.2 × 10−4 S cm−1 at 25 °C. Owing to the high surface tension of nanostructured UIO/Li‐IL SEs, the contact between electrodes and the SE is excellent; consequently, the interfacial resistances of Li/SE and LiFePO4/SE at 60 °C are about 44 and 206 Ω cm2, respectively. Moreover, a stable solid conductive layer is formed at the Li/SE interface, making the Li plating/stripping stable. Solid‐state batteries from the UIO/Li‐IL SEs show high discharge capacities and excellent retentions (≈130 mA h g−1 with a retention of 100% after 100 cycles at 0.2 C; 119 mA h g−1 with a retention of 94% after 380 cycles at 1 C). This new type of nanostructured UIO/Li‐IL SEs is very promising for solid‐state batteries, and will open up an avenue toward safe and long lifespan energy storage systems. After absorbing ionic liquid Li‐IL, nanostructured MOFs of Uio‐66 become a new kind of solid electrolyte (UIO/Li‐IL). The UIO/Li‐IL solid electrolyte shows a high ionic conductivity, good stability against metallic Li electrode, and low solid electrolyte/electrode interfacial resistances. The solid‐state lithium batteries using the UIO/Li‐IL solid electrolyte exhibit a high capacity and excellent retention.