Recently, the team of Wen Zhaoyin, a researcher at the Shanghai Institute of Ceramics, Chinese Academy of Sciences, achieved the in-situ preparation of gel polymer electrolytes using ion-conducting initiators. The gel polymer electrolytes have excellent fire resistance and are based on solid lithium assembled from the electrolyte The battery can still supply power to the LED array under the conditions of simultaneous shear and fire (flame temperature 528 ℃), which greatly improves the safety of the lithium battery. Relevant work applied for a Chinese invention patent. The main research results were published in the international journal "Advanced Energy Materials" with the title of In Situ Generated Fireproof Gel Polymer Electrolyte with Li6.4Ga0.2La3Zr2O12As Initiator and Ion-Conductive Filler. The first author is Xu Dong, a doctoral student at Shanghai Silicate, and the tutor is Wen Zhaoyin.
To a certain extent, gel polymer electrolyte (GPE) has the advantages of high safety of solid polymer electrolyte (SPE) and high ion conductivity of liquid electrolyte, and is considered to be the most suitable electrolyte system for practical application. At present, most researches are on gel polymer electrolyte systems based on polyvinylidene fluoride (PVDF) and its derivatives. However, the gel electrolyte still contains a certain amount of flammable liquid electrolyte, which poses safety risks. In order to further improve its safety performance and electrochemical performance, researchers have done a lot of research work, mainly including organic-organic blend modification, organic-inorganic composite modification, physical / chemical cross-linking modification, etc. However, most literatures do not report the safety performance of gel polymer electrolytes in detail. On the other hand, in the preparation process of gel polymer electrolytes such as the currently commonly used phase inversion method, a large amount of volatile organic solvents are used, which not only pollutes the environment but also increases costs, and the preparation process is cumbersome. The above-mentioned problems can be avoided or alleviated by the method of in-situ crosslinking polymerization.
Wen Zhaoyin's team used garnet-type solid electrolyte (Li6.4Ga0.2La3Zr2O12) as an initiator and ion-conducting filler in triethyl phosphate / fluoroethylene carbonate of polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP) The ester (TEP / FEC) mixed solution initiates the defluorination and cross-linking process of PVDF-HFP, so as to realize the in-situ preparation of gel polymer electrolyte, and the mechanism of gel transformation process is studied in depth. The optimized gel polymer electrolyte has an ion conductivity of 1.83 × 10-3 S cm-1 at 20 ° C and an electrochemical stability window of 4.75V at room temperature. The gel polymer electrolyte has excellent fire resistance, and the solid-state lithium battery assembled from it has high safety. The ternary lithium battery based on the gel polymer electrolyte shows good cycle stability. This work provides a new way of thinking about the use of fire-resistant gel electrolytes to obtain excellent ionic conductivity and to ensure the high safety of gel polymer electrolytes and corresponding lithium batteries.
Related work was supported by the National Key Research and Development Program and the National Natural Science Foundation of China.
Schematic diagram of composition and structure of fire-proof gel polymer electrolyte and shear and combustion experiment of soft-packed lithium battery based on the gel polymer electrolyte
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