Safety diaphragm for secondary battery and preparation method thereof

Abstract

The invention provides a safety separator for a secondary battery that has heat sealing properties and excellent gas permeability without using an adhesive and a preparation method thereof. The method for preparing a safety separator for a secondary battery according to the present invention is characterized in that it includes the following steps: a spinning solution configuration step: at room temperature, a certain amount of heat-sensitive material is dissolved in a spinning solvent as a spinning solute In the process, stir evenly to obtain an electrospinning solution; the electrospinning process: use a high-temperature resistant non-woven fabric diaphragm as a base film, and electrospin the electrospinning solution on the base film, and the spinning conditions are: room temperature, positive high pressure It is +5 KV~+20 KV, the negative high voltage is ‑1KV~‑10KV, and the left and right translation speed of the syringe is 10~60 mm min ‑1 , the rolling speed of the collector is 10~60mm·min ‑1 , the exit speed of electrospinning solution is 0.02~0.5mm min ‑1 , the collection time is 10-1200min, and the safety separator for secondary batteries is obtained after drying, wherein the safety separator for secondary batteries includes a base film and a spinning layer directly attached to the base film.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a safety separator for secondary batteries and a preparation method thereof. [0002] technical background [0003] Due to the advantages of high specific energy, long cycle life and environmental friendliness, lithium-ion batteries are widely used in portable electronic products, electric vehicles and other fields. The development of a new generation of portable electronic products and electric vehicles has put forward higher requirements for the safety and energy density of lithium-ion batteries. The separator is one of the important components of the lithium-ion battery. Its function is to prevent the physical contact between the positive and negative electrodes and provide ion conductivity by absorbing the electrolyte. Although the separator does not directly participate in the battery reaction, its structure and properties determine the performance ...

AI Technical Summary

Problems solved by technology

For example, the patent CN106299219A uses polyethylene microspheres as a safety diaphragm prepared as a thermal protection layer, but due to the close packing of microspheres and the use of adhesives, it will affect the air permeability of the diaphragm, thereby affecting the ion conductivity of the diaphragm

Moreover, the use of the adhesive will also cause adverse effects such as equipment blockage during the preparation process.

[0005] In addition, due to the high thermal closure temperature of polyethylene (130°C), due to the existence of thermal inertia, the internal temperature of the battery will greatly exceed 130°C when the diaphragm is closed, causing side reactions between the positive and negative electrodes and the electrolyte.

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