Directional Modification‐Functionalized Metal–Organic Framework Solid‐State Electrolytes for Highly Stable Li–O2 Batteries

Abstract Metal–organic frameworks (MOFs) with accurately directional and well‐ordered channels are considered ideal solid‐state Li‐ion conductors and are expected to be utilized in solid‐state lithium–oxygen (Li–O 2 ) batteries to achieve rechargeable batteries with high energy density. However, the instability of MOFs toward air and lithium metal has become a crucial problem to overcome. Herein, a breakthrough is first realized in overcoming these challenges by utilizing cationic MOF (CMOF) as an advanced Li‐ion conductor. Benefiting from the positively charged sites in the CMOF, an outstanding Li + conductivity of 6.45 × 10 −4 S cm −1 at room temperature, a low activation energy of 0.15 eV, and a high transference number of 0.59 are achieved. In particular, the CMOF shows high flame retardancy, H 2 O, and O 2 − stability, which are key factors that affect the battery performance of Li–O 2 batteries. Such extraordinary Li + transport makes the assembled solid‐state Li–O 2 battery cycle up to 790 h with a low overpotential of 1.09 V. The proposed novel directional modification strategy is of great significance to developing high‐performance SSEs for solid‐state Li–O 2 batteries and other lithium batteries.