A kind of sandwich structure multilayer gel polymer electrolyte for lithium ion battery and preparation method thereof

Abstract

The invention provides a sandwich structural multi-layer gel polymer electrolyte for a lithium ion battery. The gel polymer electrolyte is a sandwich multi-layer structure; the number of layers is an odd number; furthermore, the sandwich multi-layer structure includes at least three layers; the gel polymer electrolyte is prepared by a film A and a film B in an alternative compounding manner, wherein the film A is a polymethyl methacrylate film; the film B is a polyethylene glycol terephthalate film or a polycaprolactone film; the upper and lower surface layers of the sandwich multi-layer structure are the film A; and the film B is put in the inner layer of the sandwich multi-layer structure, and is alternatively compounded with the film A. The preparation method of the invention is simple; industrial production is easily realized; the disadvantages of complex operation, difficult control, non-uniform film property and the like due to the fact that the multi-layer film is prepared through the methods, such as a non-woven solution intrusion method, a multi-layer film hot-press forming method and a spin-coating method, can be overcome; and the application range of the existing electrostatic spinning technology can be expanded.

Description

technical field [0001] The invention belongs to the field of lithium-ion battery preparation, and relates to a polymethyl methacrylate (PMMA) sandwich-structured multilayer gel polymer electrolyte for lithium-ion batteries and an electrospinning preparation method thereof. Background technique [0002] Traditional lithium-ion batteries use liquid electrolytes, which are prone to leakage and other unsafe factors. Gel polymer electrolyte (GPE) is a gel system composed of polymers, lithium salts, organic solvents, etc. It has both the high conductivity of liquid electrolytes and the safety of solid electrolytes. GPE membranes are considered to have the most potential for development. Electrolyte materials for high-performance lithium-ion batteries are also an important way to solve the safety of lithium-ion batteries. [0003] At present, the structure and properties of GPE have been reported. The polymers usually used to prepare GPE include polyethylene oxide (PEO), polyacryl...

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Problems solved by technology

Chinese patent CN105932204A discloses a composite lithium-ion battery diaphragm and its preparation method. The non-woven fabric is invaded into the PMMA polymer mixed solution, and then the non-woven fabric is taken out from the solution to remove the solvent to prepare a composite lithium-ion battery diaphragm. , this method requires the preparation of a PMMA polymer mixed solution with complex components. It is difficult to maintain precise control of the content of each component in the process, and it is difficult to ensure the uniformity of the performance of the prepared composite membrane.

Chinese patent CN105619991A discloses a composite lithium-ion battery diaphragm material and its preparation method. The battery diaphragm material mentioned has a three-layer structure, wherein the first and third layers are polymer porous films, and the two layers of polymer Inorganic particles are attached to the opposite sides of the porous film, and the middle layer is a non-woven fabric impregnated with a polymer binder. The structure is easy to occur physically or chemically, and the film-forming performance is difficult to control

The multi-layer film is made of sol prepared by soluble inorganic salts through alternate spin coating, and has certain dielectric properties, but it cannot be used to prepare GPE, and the method is cumbersome in the process of alternate spin coating when preparing the film, and the preparation efficiency is low. Too low for mass production

Raghavan et al. (Journal of Power Sources, 2010, 195(18): 6088-6094) on polyvinylidene fluoride-hexafluoropropylene / polyacrylonitrile (P(VDF- co -HFP) / PAN) composite gel polymer electrolyte was studied, P(VDF- co -HFP) and PAN were prepared by continuous electrospinning method to obtain a multi-layer superimposed mixed film, the structure is similar to a sandwich structure, and there is a good interfacial interaction between layers. The method is to continuously add Two polymer solutions are continuously spun to form a film. This process may cause the two polymer solutions to partially mix and cause phase separation, forming stress concentration points inside the film, which is not conducive to the improvement of mechanical properties. In this document The relevant mechanical properties have not been reported, which may be the reason for the lack of mechanical properties. This method is not conducive to industrialized actual production

[0006] At present, there is no relevant literature at home and abroad about the research on the preparation of multilayer films from PMMA and PET or PCL, and the method of preparing multilayer films to form a composite structure between PET or PCL and PMMA will be able to overcome the lack of mechanical properties of PMMA. , providing a way to prepare PMMA-based GPE with high ionic conductivity and high mechanical strength

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