PET non-woven cloth-based composite lithium ion battery diaphragm with nano aperture and preparation method of PET non-woven cloth-based composite lithium ion battery diaphragm

Abstract

The invention discloses a PET non-woven cloth-based composite lithium ion battery diaphragm with a nano aperture and a preparation method of the PET non-woven cloth-based composite lithium ion battery diaphragm. The lithium ion battery diaphragm is prepared from the following raw materials: a hydrophilic PET non-woven cloth base material and a macromolecular polymer, wherein small holes of 1 to 500 nm are uniformly distributed in the hydrophilic PET non-woven cloth base material, and the porosity is 50 to 70 percent; the small holes of the hydrophilic PET non-woven cloth base material are filled with the macromolecular polymer; the macromolecular polymer is polyvinyl alcohol or carboxymethyl cellulose sodium. By the adoption of a method for ultrasonic treatment, vacuum infiltration, low-temperature drying and thermal rolling, the small holes of PET hydrophilic non-woven cloth are filled with the macromolecular polymer, so that the PET non-woven cloth-based composite lithium ion battery diaphragm with the nano aperture has the advantages of higher porosity, lower thermal shrinkage, small lithium ion mass transfer impedance and good electrochemical performance. The preparation method disclosed by the invention is less in steps and easy to operate; use of a toxic reagent is not involved in the preparation process, so that the safety is high; the preparation method is applicable to preparation of a matrix material from the PET hydrophilic non-woven cloth with various surface densities and high breathability, and industrial production can be realized.

Description

technical field [0001] The invention relates to the technical field of electrochemical power sources, in particular to a PET non-woven fabric-based composite lithium-ion battery diaphragm with a nanometer aperture and a preparation method thereof. Background technique [0002] With the market's rapid demand for new energy electric vehicles and power energy storage devices, lithium-ion batteries are being developed in the direction of high-rate rapid charge and discharge. However, the existing lithium-ion battery separators are mostly made of polyethylene and polypropylene materials, which are only suitable for It is suitable for small mobile electrical equipment such as mobile phones and tablet computers, but not suitable for large electrical equipment such as electric vehicles, unmanned aerial vehicles, and spacecraft, because the porosity of polyolefin separators is low, generally less than 40%, and cannot be used for lithium A large number of fast transitions of ions prov...

AI Technical Summary

Problems solved by technology

[0002] With the market's rapid demand for new energy electric vehicles and power energy storage devices, lithium-ion batteries are being developed in the direction of high-rate rapid charge and discharge. However, the existing lithium-ion battery separators are mostly made of polyethylene and polypropylene materials, which are only suitable for It is suitable for small mobile electrical equipment such as mobile phones and tablet computers, but not suitable for large electrical equipment such as electric vehicles, unmanned aerial vehicles, and spacecraft, because the porosity of polyolefin separators is low, generally less than 40%, and cannot be used for lithium A large number of fast transitions of ions provide channels. In addition, lithium-ion batteries will generate a lot of heat during fast charging under high-rate conditions, while polyolefin separators have poor thermal stability, and the melting temperature is lower than 170 ° C. Excessive temperature It will cause the melting deformation of the diaphragm and cause danger due to the internal short circuit of the lithium-ion battery. Therefore, it is urgent to develop a large-scale power lithium-ion battery with good thermal stability and excellent mechanical stability;

[0003] PET non-woven fabric-based lithium-ion battery separators take advantage of the advantages of PET non-woven fabrics in thermal stability, large pore size and wide distribution, but the existing PET non-woven fabric-based lithium-ion battery separators make the polymer very difficult due to capillary force and other reasons. It is difficult to completely fill the pores of the non-woven fabric, and the polymer is mostly covered on the surface of the non-woven fabric, and cannot be completely filled in the pores of the non-woven fabric. Therefore, the prepared composite materials are mostly layered structures, and the filling effect on the pores of the non-woven fabric Limited, and the larger pores are easy to make the positive and negative electrodes of the lithium-ion battery contact and short-circuit, which is also the biggest problem facing the non-woven fabric-based lithium-ion battery separator materials at present.

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