In situ construction of 3D crossing-linked gel polymer electrolyte toward high performance and safety lithium metal batteries

Our study focuses on developing high-performance gel polymer electrolytes (GPEs) tailored for lithium metal batteries (LMBs), harnessing the combined benefits of high conductivity of liquid electrolytes and the enhanced safety of solid electrolytes. To this end, we engineered an in situ polymerized GPE (PMIA- TP) that integrates trifluoroethyl methacrylate (TFMA) and pentaerythritol triacrylate (PETA) monomers within an electrospun poly (m-phthaloyl-m-phenylenediamine) (PMIA) supporting membrane. In addition to high ionic conductivity, high lithium ion transference number, enhanced tensile strength and good thermal stability, the resulting PMIA-TP GPE exhibits satisfactory electrochemical stability against lithium electrodes, enabling long-term and stable lithium plating/stripping in symmetric Li//Li cells, and good rate capability and prolonged cycle life for LiFePO4//Li cells. Further X-ray photoelectron spectroscopy analysis and density functional theory calculations revealed that the electrochemical stability of the PMIA-TP GPE towards lithium metal electrode is due to the formation of a fluorine-rich solid electrolyte interphase (SEI) layer facilitated by reactions involving the –CF3 groups in TFMA, which is beneficial for the effective Li+ transport and lithium dendrite suppression. In summary, our study offers a promising approach to fabricating GPEs that offer high safety and high performance for LMBs.