Preparation method of polymer gel electrolyte cell

Abstract

The invention discloses a preparation method of a polymer gel electrolyte cell, which comprises the following steps: 1) polymer powder pretreatment: the polymer powder is passed through a high-speed ball milling method to obtain a powder with a particle size of less than 1 μm; 2 ) Polymer powder dispersion: mix the polymer powder after ball milling in step 1) with non-aqueous solvent, lithium salt, and additives to prepare a submicron polymer suspension dispersion; 3) Electrolyte gelation: mix step 2 ) The prepared polymer suspension dispersion liquid is poured into the lithium-ion cell to fully infiltrate it, then gelled at a high temperature for 1-12 hours, and then cooled to obtain a polymer gel electrolyte cell. Compared with the prior art, the polymer gel electrolyte cell prepared by the present invention has higher ionic conductivity, lower battery internal resistance, excellent cycle life, good high temperature performance, excellent safety performance and There is no risk of liquid leakage, and the comprehensive performance is obviously better than that of the electrolyte cell prepared by the existing preparation method.

Description

technical field [0001] The invention belongs to the field of polymer lithium ion batteries, and more specifically, the invention relates to a preparation method of a polymer gel electrolyte cell. Background technique [0002] Compared with lead-acid, Ni-Cd, and MH-Ni batteries, lithium-ion batteries have higher specific volume energy density, specific gravimetric energy density, and better environmental friendliness, so they have been widely used in mobile phones, portable audio and video players , laptops, handheld touch screen tablets and other electronic products. In recent years, as the concept of energy crisis has been deeply rooted in the hearts of the people, people have gradually realized that excessive reliance on fossil energy is extremely dangerous, thus setting off a worldwide EV-HEV (electric vehicle, hybrid electric vehicle), as well as intermittent power generation such as wind power and photovoltaic power generation. The energy storage station (ESS) boom of ...

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Problems solved by technology

However, the production process of this method is quite complicated, which not only requires high equipment and processes, but also makes it difficult to recover and reuse solvents, and low-boiling flammable solvents will also bring potential safety hazards.

In addition, this film-making method is only suitable for the lamination process, and the production efficiency is low, and the porosity of the finished film is also low, and the electrical conductivity is less than 1.0×10 -3 S / cm, the battery produced by this method has poor low temperature performance and rate performance, and the application area is also narrow

The phase inversion method (reversed phase method, also called solvent / non-solvent method) developed later was improved on the basis of the Bellcore film formation method, which improved the porosity and electrical conductivity of the porous membrane to a certain extent. However, the comprehensive performance is still poor, and the amount of solvent is large, and the cost is high

[0006] 2. In-situ gel method: This method is generally to mix polymerizable small molecule monomers, initiators, crosslinking agents, coupling agents, etc. with liquid electrolyte, and then generate (free radicals, cations, etc.) Polymerization reaction forms gel in situ, which has the advantages of simple process, low cost, and high conductivity when the polymer skeleton content is low. However, the system formed by this method has a dense and non-porous structure, so that the rate performance and The cycle performance is poor, and the monomer is not easy to polymerize completely, and the residual monomer and initiator fragments will have a negative impact on the electrochemical stability of the cell.

However, the viscosity of the pre-gel solution of this invention is 300-2500CP, which is hundreds to thousands of times that of conventional liquid electrolytes, thus bringing about the problem of difficulty in wetting pole pieces and separators, although the inventor also realized that the viscosity The molecular weight is limited to less than 10,000 due to the problem of poor wetting, but even if a low molecular weight polymer is used, or the method of reducing the amount of polymer added is used, the battery cells prepared by the invention still have low initial capacity / efficiency and low cycle time. Disadvantages of rapid capacity decay

The Chinese invention patent application 201210128618.7 provides a large-area electrospinning gel realization process. The gel electrolyte membrane prepared by this method has the advantages of large porosity, high conductivity, and good comprehensive performance. However, the electrostatic Spinning is easy to catch fire in a high-pressure drying environment, and a relatively sealed environment is required to control dust, and it is difficult to recover the solvent after volatilization, which is easy to cause air pollution. In addition, the cost of electrospinning is high, so the production efficiency of gel electrolyte is low. large scale industrial production

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