Sustainable and mass-producible epoxy vitrimer-based gel polymer electrolytes

Abstract With the growing demand for high-energy-density energy storage devices, lithium metal batteries (LMBs) using lithium metal as anodes have emerged as promising candidates. However, the issues of lithium anodes, such as dendrite growth, poor compatibility with liquid electrolytes, and safety concerns, pose challenges for their practical use. Therefore, gel polymer electrolytes (GPEs) become popular due to their good compatibility with lithium anodes. However, traditional GPEs suffer from poor mechanical strength, complex fabrication processes, lack of self-healing ability and recyclability, which hinder their large-scale and sustainable application. Here we present an epoxy vitrimer (cross-linked network with dynamic covalent bonds) as GPE for LMBs, synthesized from commercially available raw materials of epoxy resins by a simple technology of hot-pressing. The epoxy vitrimer-based GPE shows good electrochemical performance, with over 1000 h of stable cycling in Li symmetric cells and impressive cycling retention of 92.4% after 200 cycles in LiFePO4||Li cells. Moreover, dynamic covalent bonds endow vitrimer with remarkable self-healing ability and recyclability, which would further improve the cycling and safety aspects of the battery. Therefore, due to its low material costs and simple manufacturing process, epoxy vitrimer-based GPE has a great potential for sustainable mass production in practical application in LMBs.