Lithium ion battery gel electrolyte with multi-stage structure and preparation method thereof

Abstract

The invention discloses lithium ion battery gel electrolyte with a multi-stage structure and a preparation method thereof. The lithium ion battery gel electrolyte with the multi-stage structure comprises a polymer network cross-linking framework and a liquid electrolyte in the network framework, wherein the polymer network physical cross-linking framework is composed of nano fibers of PVDF (Polyvinylidene Fluoride) electrostatic spinning, and the cross-linking framework is adsorbed to two sides of a base PE (Poly Ethylene) film. The preparation method comprises the following steps: 1) preparing an electrostatic spinning solution; 2) preparing a first-level framework structure by electrostatic spinning; 3) coating a polymer so as to prepare a second-level framework structure; and 4) carrying out high-temperature in-situ polymerization so as to prepare a PMMA (Polymethyl Methacrylate) gel polymer three-level framework structure. The gel frameworks are distributed in a level-by-level structure, and compared with a conventional gel system, the macromolecule cross-linking system of the multi-level structure has the advantages of high mechanical intensity, high fluid protection capability, high porosity of the network structure, high conductivity and the like, and paves the way for the research of a new generation of gel electrolytes.

Description

technical field [0001] The present invention relates to a polymer gel electrolyte system (including gel electrolyte and diaphragm support framework) for lithium-ion batteries with a multi-level structure, in particular to a PVDF electrospun nanofiber, a PVDF-HFP polymer cross-linked secondary network and gel electrolyte systems with polymer crosslinked networks polymerized in situ. Background technique [0002] Lithium-ion batteries have gained market dominance due to the advantages of high voltage, small size, light weight, high energy density, and long cycle life. [0003] At present, the electrolyte of lithium-ion batteries is divided into liquid electrolyte and gel electrolyte. Among them, the liquid electrolyte is characterized by stable and reliable electrochemical performance, but it generally has problems such as poor safety, insufficient hardness of the battery and easy deformation. In contrast, the gel electrolyte system fixes the fluid solvent molecules in the p...

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Problems solved by technology

Since the concentration of the polymerizable monomer in the gel electrolyte precursor is low, it will not be enough to convert the liquid electrolyte into a gel electrolyte, so it is often necessary to add more polymerizable monomers; but the concentration of the polymerizable monomer When the concentration is high, the polymer concentration in the generated gel electrolyte is also high, which will cause difficulties in lithium ion conduction, resulting in a series of electrochemical performance problems such as low lithium ion conductivity and easy lithium precipitation.

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