A non-flammable, flexible and UV-cured gel polymer electrolyte with crosslinked polymer network for dendrite-suppressing lithium metal batteries

A flexible, non-flammable gel polymer electrolyte (GPE) was synthesized by combining UV-cured polymerization of ethoxylated trimethylolpropane triacrylate (ETPTA) within the framework of glass fiber (GF) membrane. Non-flammable hydrofluoroether (1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether, FEPE) and high flash point solvent (fluoroethylene carbonate, FEC) were employed as plasticizers for GPE-FEC/FEPE (60:40) to promote the safety of electrolyte and improve the compatibility with lithium metal anode. Non-flammable GPE-FEC/FEPE (60:40) possessed high safety level, high ionic conductivity (1.57 mS cm(-1) at 30 degrees C), excellent oxidation stability (4.6 V vs. Li/Li+), high lithium-ion transference number (0.71) and good thermal stability (120 degrees C). After 1000 h test, Li/GPE-FEC/FEPE (60:40)/Li displayed better compatibility with lithium metal electrode compared with commercial liquid electrolyte. The test of Li/LFP cells showed that the safe GPE-FEC/FEPE (60:40) had excellent cycling performance at room temperature and elevated temperature. After 1000 cycles at 2 C and room temperature, the capacity retention was as high as 88.4%. XPS spectra proved that GPE-FEC/FEPE (60:40) was beneficial to promote the formation of LiF-rich SEI film on the surface of lithium metal anode, which could effectively inhibit the growth of lithium dendrites.

Automated summary

A flexible, non-flammable gel polymer electrolyte with high ionic conductivity, excellent oxidation stability, and good thermal stability was synthesized. It exhibited better compatibility with the lithium metal anode compared to commercial liquid electrolyte, and showed excellent cycling performance even after 1000 cycles at room temperature and elevated temperature.