| Gel polymer lithium ion battery not only has the advantages of lithium ion battery,but also has the unique advantages of high safety,controllable shape and light weight.As an important part of polymer lithium-ion batteries,gel polymer electrolytes have attracted the attention of many researchers in order to prepare polymer electrolytes with excellent comprehensive performance.In this paper,PVDF-HFP was used as the matrix of polymer electrolyte,and the electrolyte was prepared by spin coating method.The effects of the content of ionic liquid plasticizer and the amount of inorganic filler on the structure and properties of electrolytes were studied by adding ionic liquids,inorganic fillers,and so on,in order to prepare high content of ionic liquid plasticizers and inorganic fillers.Performance of polymer electrolytes.The research contents of this paper are divided into the following two parts:（1）Preparation and Properties of Gel Polymer electrolyte based on PVDF-HFP,EMIMTFSI（IL）and LiTFSI.Gel polymer electrolytes were prepared by PVDF-HFP,IL and LiTFSI.The effects of the ratio of IL and PVDF-HFP on the structure and properties of electrolytes were studied systematically.The results show that with the increase of IL content,the crystallinity of the system decreases significantly and the thermaldecompositiontemperatureincreases.Inaddition,electrochemical measurements showed that the addition of IL could significantly improve the ionic conductivity and lithium ion mobility of GPEs,especially the conductivity of 3P/5E/2LI electrolyte at 30℃ is 2.0×10-3S cm-1,the lithium ion transfer number is 0.5,and the electrochemical window is 5 V.The Coulomb efficiency of LiFePO4/GPE/Li battery has more than 99%,the capacity retention rate is about 86%after 50 cycles at 0.1C.At the same time,he electrolyte showed excellent rate performance.（2）Preparation and Properties of Gel Polymer electrolyte based on PVDF-HFP,EMIMTFSI（IL）,LiTFSI and rGO-NH2.Gel polymer electrolytes were prepared from PVDF-HFP,IL,LiTFSI and rGO-NH2.The effects of the amount of rGO-NH2 on the electrolyte properties were analyzed by XRD,TGA and electrochemical workstation.The results showed that the crystallinity of electrolyte was decreased and the thermal decomposition temperature was increased with the addition of rGO-NH2.At the same time,the addition of IL and rGO-NH2 improved the conductivity of GPE.At 30℃,the ionic conductivity of the sample 3P/5E/2LG-10 is 2.1×10-3S cm-1,the electrochemical stability window is 4.9 V,and the lithium ion migration number is0.45.The cell test results show that the electrolyte has excellent cycle performance and rate performance. |
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