Preparation and performance of long-life PEO-based solid-state batteries based on the complexation of 15 Crown ether 5 with lithium salt

Poly (ethylene oxide) (PEO)-based solid-state electrolytes are the most researched and widely used polymer solid-state electrolytes, but their ionic conductivity, electrochemical stability window, and cycling stability all need further improvement. In this work, 15 Crown ether 5 and the high concentration of lithium salts are added into PEO solid-state electrolytes using a solution-casting approach. The resulting solid-state electrolyte exhibits an ionic conductivity of 3.14 × 10 −3  S cm −1 at 60 °C and an electrochemical stability window exceeding 5.2 V. The assembled Li//Li symmetric battery can be stably cycled for over 850 h at a current of 0.1 mA cm −2 , and the LiFePO 4 //Li battery has an initial discharge capacity of 144 mA h g −1 at 2C rate, retaining 85 % of its capacity after 800 cycles. By optimizing the solid-state electrolyte components, Li//Li symmetric batteries can achieve cycling stability for up to 2200 h, and LiFePO 4 //Li batteries can endure up to 2000 cycles at a 2C rate and 4800 cycles at a 5C rate. Moreover, the prepared solid-state electrolyte can be matched with a high-voltage cathode electrode, offering a wide range of potential applications and promising commercialization prospects.