Preparation and performance of a flame-retardant gel polymer electrolyte
In this work,a flame-retardant gel polymer electrolyte was prepared using an in situ polymerization process.We introduced 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether(HFE)into an electrolyte system to improve the flame retardancy of the electrolyte.HFE can also inhibit the shuttle effect in lithium-sulfur batteries by adjusting the solubility of polysulfides.By comparing the flame retardancy and electrochemical performance tests of electrolytes without HFE(HFE-0)and electrolytes with different HFE contents,it was found that when the volume ratio of DOL,DME,and HFE was 1∶0.5∶0.5(HFE-0.5),respectively,the gel polymer electrolyte demonstrated the best flame retardancy and electrochemical performance.Scanning electron microscopy(SEM)and electrochemical tests were performed to analyze and compare the electrochemical properties and lithium anode surface morphologies of lithium-sulfur and lithium-iron-phosphate batteries using HFE-0 and HFE-0.5 electrolytes after cycling.The results show that the lithium-sulfur battery with the HFE-0.5 electrolyte can maintain a specific discharge capacity of 706 mAh/g after 100 cycles with an 84.5%capacity retention rate at 0.1 C,and the cycling performance is significantly better than that of the electrolyte without HFE.In addition,the specific discharge capacity of the lithium-iron-phosphate battery with the HFE-0.5 electrolyte reached 117.2 mAh/g after 110 cycles at 0.2 C,indicating that the prepared gel polymer electrolyte can also be applied in these batteries.The designed flame-retardant gel polymer electrolytes with good electrochemical performances are useful for promoting the development and application of lithium-sulfur batteries.
lithium-sulfur batteryflame retardant gel polymer electrolytesHFEelectrochemical properties
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