Metal–Organic Framework-Supported Poly(ethylene oxide) Composite Gel Polymer Electrolytes for High-Performance Lithium/Sodium Metal Batteries

Thanks to their high energy density, lithium/sodium metal batteries (LMBs/SMBs) are considered to be the most promising next-generation energy storage system. However, the instability of the electrode/electrolyte interface and dendrite growth seriously hinders commercial application of LMBs/SMBs. In addition, traditional liquid electrolytes are inflammable and explosive. As a key part of the battery, the electrolyte plays an important role in solving the abovementioned problems. Although solid electrolytes can alleviate dendrite growth and liquid electrolyte leakage, their low ionic conductivity and poor interfacial contact are not conducive to improvement of overall LMBs/SMB performances. Therefore, it is necessary to find a balance between liquid and solid electrolytes. Gel polymer electrolytes (GPEs) are one means for achieving high-performance LMBs/SMBs because they combine the advantages of liquid and solid electrolytes. Metal–organic frameworks (MOFs) benefit from high specific surface areas, ordered internal porous structures, organic–inorganic hybrid properties, and show great potential in modified electrolytes. Here, Cu-based MOF-supported poly(ethylene oxide) composite gel polymer electrolytes (CGPEs) were prepared by ultraviolet curing. This CGPE exhibited high ionic conductivity, a wide electrochemical window, and a high ion transference number. In addition, it also exhibited excellent cycle stability in symmetric batteries and LMBs/SMBs. This study showed that CGPE had great practical application potential in the next-generation LMBs/SMBs.