Preparation method of electrospun composite membrane for lithium ion battery

Abstract

The invention provides a preparation method of an electrospun composite membrane for a lithium ion battery, and relates to lithium ion batteries. The invention provides the preparation method of the electrospun composite membrane which is higher in ionic conductivity, better in electrochemical properties and smaller in thickness for the lithium ion battery. The preparation method comprises: preparing a precursor solution A for compounding polyvinylidene fluoride and another polymer; preparing a precursor solution B for mixing the polyvinylidene fluoride and inorganic nano-material; and adopting an electrospinning technology to obtain the electrospun composite membrane for the lithium ion battery. According to the preparation method provided by the invention, PVDF is adopted as a substrate; a porous mesh-shaped composite fiber membrane is produced by using the electrospinning technology, a polymer blend and the inorganic nano-material; and a crystallinity of a PVDF system is reduced, thus improving ion conductivity, tensile strength and breaking elongation of an amorphous area of the membrane, ensuring ionic conductivity and safety performance of the lithium ion battery with a higher electrolyte, and obtaining fiber membranes different in thickness. Therefore, application needs of the lithium ion battery membrane are met.

Description

technical field [0001] The invention relates to lithium ion batteries, in particular to a method for preparing an electrostatic spinning composite separator for lithium ion batteries. Background technique [0002] Lithium-ion battery is a kind of Li + The rechargeable and dischargeable battery that works by embedding and de-embedding is composed of five parts: positive electrode material, negative electrode material, electrolyte, separator and battery casing packaging material. Among them, the diaphragm is an important part of the lithium-ion battery. It plays a role in preventing the short circuit of the positive and negative electrodes in the battery, and at the same time provides the ion transport channel during the charging and discharging process. Its performance determines the interface structure and internal resistance of the battery. It directly affects the capacity, cycle performance and safety performance of the battery, and the excellent performance of the separa...

AI Technical Summary

Problems solved by technology

Polyolefin microporous separators have the advantages of good electrochemical stability and suitable mechanical strength, but there are also many disadvantages: (1) The electrolyte wetting performance is not good, and the liquid absorption rate is low, which limits the ion conductivity of the battery. (2) Thermal dimensional stability is poor, and significant dimensional shrinkage will occur when the temperature is higher than 120 ° C, resulting in a short circuit inside the battery

Polyvinylidene fluoride (PVDF) has been attracting attention due to its high dielectric constant, good stability, good mechanical properties and good affinity with electrolyte, but its regular structure and high crystallinity have affected the The liquid absorption rate of PVDF fiber membrane, which in turn affects the ion conductivity

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