Double Crosslinked Polymer Electrolyte by C-S-C Group and Metal-Organic Framework for Solid-State Lithium Batteries

Poly(ethylene oxide) (PEO) is among the most promising candidates for solid-state electrolytes in lithium metal batteries. However, the low ionic conductivity caused by strong coordination between Li ions and the EO chains limits the practical application of PEO-based electrolytes. Herein, a double crosslinked PEO-based electrolyte with alternate C-S-C groups and functionalized metal-organic frameworks (MOFs) is proposed. The incorporation of C-S-C groups not only accelerates Li ions transport by weakening the coordination between Li ions and polymer backbone, but also facilitates segmental relaxation of the polymer backbone. The PEO-based electrolyte with C-S-C groups shows a remarkable 13-fold increase in ionic conductivity. Furthermore, when functionalized MOFs are used as crosslinked centers, the double-crosslinked PEO-based electrolyte with a robust network structure possesses enhanced mechanical/electrochemical/thermal stability and limited anion transmission. As a result, the symmetrical Li||Li cell enables over 2400 h cycling at room temperature. The LiFePO4||Li cells show long cycle life over a wide temperature range from 25 to 100 degrees C, and a high areal capacity of 1.43 mAh cm(-2) is achieved with a cathode loading of 10.0 mg cm(-2). This study demonstrates a promising strategy to develop advanced electrolytes for potential solid-state lithium-metal batteries.