Cross-linked polymer gel electrolyte membrane supported by hydrophilic polytetrafluoroethylene microporous membrane

Abstract

The invention discloses a cross-linked polymer gel electrolyte membrane supported by a hydrophilic polytetrafluoroethylene microporous membrane. When the cross-linked polymer gel electrolyte membrane is prepared, firstly, methoxypolythylene glycol with double bonds and methyl acrylic glycidyl ester segmented copolymer are combined, ethylene glycol dimethacrylate, a thermal initiator and organic electrolyte containing lithium salt are added, stirring is conducted to form an even polymeric precursor solution; the hydrophilic polytetrafluoroethylene microporous membrane is immersed in the polymeric precursor solution and fully absorbs the polymeric precursor solution and is taken out, and the cross-linked polymer gel electrolyte membrane is obtained after cross-linked gelatinization is conducted. According to the cross-linked polymer gel electrolyte membrane, the preparation technology is simple, the electrolyte membrane is suitable for industrial production, a prepared cross-linked polymer gel electrolyte membrane system not only has a good mechanical property, but also has a good electrochemical property, an ionic conductivity at room temperature reaches up to 1.30*10-3 S cm-1, and an electrochemical stability window value can reach 4.5V. Lithium iron phosphate / lithium metal batteries assembled by the cross-linked polymer gel electrolyte membrane have good cycle performance under 25 DEG C and 70 DGE C.

Description

technical field [0001] The invention relates to the field of gel polymer electrolytes, in particular to a cross-linked gel polymer electrolyte membrane supported by a hydrophilic polytetrafluoroethylene microporous membrane. Background technique [0002] The gel polymer electrolyte used in lithium batteries has a dual function: it can conduct lithium ions, and at the same time, it can act as a separator to separate the positive and negative electrodes of the battery. The room temperature conductivity of gel polymer electrolytes generally reaches 10 -4 ~10 -3 S cm -1 Level, electrochemical stability window ≥ 4.5V, to meet the actual use requirements. General gel polymer electrolyte matrix materials include: polyethylene oxide (PEO), polymethyl methacrylate (PMMA), polyacrylonitrile (PAN), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP )Wait. The traditional preparation method of gel polymer electrolyte is carried out in a glove box filled with argon: liq...

AI Technical Summary

Problems solved by technology

Such a preparation method and the materials used must be carried out in a glove box filled with argon, which is not suitable for large-scale industrial production; in addition, the polymer matrix swells after absorbing the liquid electrolyte, which will lead to a decrease in the mechanical properties of the gel polymer electrolyte

[0003] At present, mature liquid electrolyte lithium batteries mainly use commercial polyolefin microporous membranes such as PE and PP. Their electrochemical stability is good. Although the performance meets certain requirements, there are still certain defects. The crystallinity of PE, PP and other materials High, low polarity, low porosity, poor affinity for liquid electrolyte, less liquid electrolyte adsorbed, and liquid electrolyte is easy to leak out, which will not only lead to battery performance degradation but also may bring a series of safety hazards sexual problems

At the same time, the gel polymer electrolyte prepared by using polyolefin microporous membranes such as PE and PP as a support has low porosity and the hydrophobicity of the membrane surface makes it difficult for the polymer to adhere to the surface, resulting in low conductivity and composite Membrane structure stability is poor

In addition, the high temperature resistance of the polyolefin microporous membrane is not ideal, and it is prone to problems such as wrinkling, which makes the high temperature performance of the battery worse.

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