Weak Interaction in Polymer Electrolyte Enables Fast Charging of Solid‐State Lithium Batteries

Abstract

Abstract Constructing solid polymer electrolytes for fast‐charging solid‐state lithium batteries is essential but extremely challenging due to the poor ionic conductivity and large interfacial impedance. Herein, a coordinated Li + transport network solid polymer electrolyte linked by weak bonding is designed and fabricated, featuring a high ionic conductivity of 1.14 × 10 −3 S cm −1 at 30 °C and a broad electrochemical window of 4.82 V. The weak interaction of carboxyl‐functionalized ionic liquid and metal–organic framework with polymers constructs a fast ion migration path and facilitates the dissociation of lithium salt to obtain more free Li + ions, which is beneficial for fast‐charging ability. Thus, remarkable rate capability and cycling performance are obtained with a specific capacity of 96.2 mAh g −1 at 6 C even after more than 500 cycles and capacity retention as high as 98.9% in solid‐state LiFePO 4 ||Li cells. Such a fast‐charging capability outperforms many recent reports and can be attributed to the local inter‐radical interactions of weak bonding in electrolytes and the LiF‐rich solid electrolyte interphase. This work not only confirms the importance of inter‐radical interaction but also provides insights into designing solid‐state electrolytes capable of fast charging.