阅读说明：本技术 一种纳米纤维锂电池隔膜及其制备方法 (Nanofiber lithium battery diaphragm and preparation method thereof ) 是由 李汪洋 胡伟 吴磊 张德顺 徐凤锦 孙小华 郭浩 王爱华 于 2020-12-07 设计创作，主要内容包括：本发明公开了一种纳米纤维锂电池隔膜及其制备方法,涉及锂电池隔膜技术领域,阻燃型纳米纤维锂电池隔膜,由聚N-丙烯氧基邻苯二甲酰亚胺和纳米氧化铝经静电纺丝制成。本发明以N-丙烯氧基邻苯二甲酰亚胺作为单体,经聚合反应制备聚N-丙烯氧基邻苯二甲酰亚胺并将其作为隔膜的主要加工原料,辅以纳米氧化铝制得阻燃型纳米纤维锂电池隔膜；其中聚N-丙烯氧基邻苯二甲酰亚胺不仅能够使所制隔膜满足锂电池的性能使用要求,并且还能赋予隔膜优良的阻燃性能,避免了外加阻燃剂导致的影响隔膜应用性能的问题。(The invention discloses a nanofiber lithium battery diaphragm and a preparation method thereof, and relates to the technical field of lithium battery diaphragms. According to the invention, N-propylene oxy phthalimide is used as a monomer, poly-N-propylene oxy phthalimide is prepared through polymerization reaction and is used as a main processing raw material of a diaphragm, and nano-alumina is used as an auxiliary material to obtain the flame-retardant nano-fiber lithium battery diaphragm; the poly-N-propylene oxy phthalimide can not only enable the prepared diaphragm to meet the performance and use requirements of a lithium battery, but also endow the diaphragm with excellent flame retardant performance, and avoid the problem that the application performance of the diaphragm is affected due to an additional flame retardant.)

1. A nanofiber lithium battery diaphragm is characterized in that: is prepared from poly N-propylene oxy phthalimide and nano alumina through electrostatic spinning.

2. The nanofiber lithium battery separator as claimed in claim 1, wherein: the mass ratio of the poly-N-propylene oxy phthalimide to the nano aluminum oxide is 50-100: 1-20.

3. The nanofiber lithium battery separator as claimed in claim 1, wherein: the poly N-propylene oxy phthalimide is prepared by polymerizing N-propylene oxy phthalimide monomers.

4. The nanofiber lithium battery separator as claimed in claim 1, wherein: the particle size of the nano alumina is 40-80nm, and the purity is more than or equal to 99.99%.

5. The method of preparing a nanofiber lithium battery separator as claimed in any one of claims 1 to 4, wherein: the method comprises the following steps:

(1) adding N-propylene oxy phthalimide and an initiator into an organic solvent, heating for polymerization reaction, adding water after the reaction is finished, stirring until the precipitate is not increased any more, stopping adding water, standing, filtering, and drying to obtain poly-N-propylene oxy phthalimide;

(2) adding poly N-propylene oxy phthalimide and nano aluminum oxide into a screw extruder, melting and blending, and performing electrostatic spinning on the obtained melt to obtain the nano fiber lithium battery diaphragm.

6. The method of preparing a nanofiber lithium battery separator as claimed in claim 5, wherein: the organic solvent is at least one of N, N-dimethylformamide, N-dimethylacetamide and dimethyl sulfoxide.

7. The method for preparing a nanofiber lithium battery separator as claimed in claim 5, wherein the initiator is an organic peroxide initiator or an azo initiator.

8. The method for preparing the nanofiber lithium battery diaphragm as claimed in claim 5, wherein the amount of the initiator is 0.1% -0.5% of the mass of the N-acryloxy phthalimide.

9. The method for preparing a nanofiber lithium battery separator as claimed in claim 5, wherein the melt blending temperature is 210-220 ℃.

10. The method for preparing the nanofiber lithium battery diaphragm as claimed in claim 5, wherein the temperature of the electrostatic spinning is 20-30 ℃, the relative humidity is 20-70%, the spinning speed is 0.01-0.5mL/h, the distance between the spinning nozzle and the receiving device is 5-30cm, and the spinning voltage is 10-30 kV.

The technical field is as follows:

the invention relates to the technical field of lithium battery diaphragms, in particular to a nanofiber lithium battery diaphragm and a preparation method thereof.

Background art:

in the construction of lithium batteries, the separator is one of the key internal layer components. The performance of the diaphragm determines the interface structure, internal resistance and the like of the battery, directly influences the capacity, circulation, safety performance and other characteristics of the battery, and the diaphragm with excellent performance plays an important role in improving the comprehensive performance of the battery. The separator has a main function of separating the positive electrode and the negative electrode of the battery to prevent short circuit due to contact between the two electrodes, and also has a function of allowing electrolyte ions to pass therethrough. The separator material is non-conductive, and the physical and chemical properties of the separator have a great influence on the performance of the battery.

At present, polyolefin diaphragm materials are widely applied to lithium batteries, but the polyolefin diaphragm has the problem of poor flame retardance. Although the flame retardant property of the polyolefin diaphragm can be improved by adding the flame retardant, the permeation property and the wettability of the diaphragm to the electrolyte and the mechanical property of the diaphragm can be influenced by adding the flame retardant.

The invention content is as follows:

the invention aims to provide a nano-fiber lithium battery diaphragm and a preparation method thereof, wherein newly synthesized poly-N-propylene-oxy-phthalimide is used as a preparation raw material to endow the diaphragm with excellent flame retardant property, and the mechanical property of the diaphragm can be improved.

The technical problem to be solved by the invention is realized by adopting the following technical scheme:

a nano-fiber lithium battery diaphragm is prepared from poly (N-propylene oxy-phthalimide) and nano-alumina through electrostatic spinning.

The mass ratio of the poly-N-propylene oxy phthalimide to the nano aluminum oxide is 50-100: 1-20.

The poly N-propylene oxy phthalimide is prepared by polymerizing N-propylene oxy phthalimide monomers.

The particle size of the nano alumina is 40-80nm, and the purity is more than or equal to 99.99%.

The preparation method of the nanofiber lithium battery diaphragm comprises the following steps:

(1) adding N-propylene oxy phthalimide and an initiator into an organic solvent, heating for polymerization reaction, adding water after the reaction is finished, stirring until the precipitate is not increased any more, stopping adding water, standing, filtering, and drying to obtain poly-N-propylene oxy phthalimide;

(2) adding poly N-propylene oxy phthalimide and nano aluminum oxide into a screw extruder, melting and blending, and performing electrostatic spinning on the obtained melt to obtain the nano fiber lithium battery diaphragm.

The organic solvent is at least one of N, N-dimethylformamide, N-dimethylacetamide and dimethyl sulfoxide.

The initiator is an organic peroxide initiator or an azo initiator.

The dosage of the initiator is 0.1-0.5% of the mass of the N-propylene oxy phthalimide.

The melt blending temperature is 210-220 ℃.

The temperature of the electrostatic spinning is 20-30 ℃, the relative humidity is 20-70%, the spinning speed is 0.01-0.5mL/h, the distance between a spinning nozzle and a receiving device is 5-30cm, and the spinning voltage is 10-30 kV.

In the invention, the pore diameter of the diaphragm is controlled by an electrostatic spinning method, the diaphragm with narrow pore diameter range and average pore diameter of 100-200nm is prepared, and the problems of wide pore diameter distribution range and poor uniformity of the diaphragm in the prior art are solved.

In the invention, N-propylene oxy phthalimide is used as a starting material for preparing a nano-fiber lithium battery diaphragm, and the conventional use of the N-propylene oxy phthalimide does not give technical suggestion of using the N-propylene oxy phthalimide as a raw material for preparing the nano-fiber lithium battery diaphragm and further gives technical suggestion of endowing the diaphragm with flame retardant property.

The addition of the nano alumina in the invention can reduce the aperture of the diaphragm, and the nano alumina is resistant to the corrosion of electrolyte, thus not causing the blockage of the diaphragm and influencing the normal operation of the lithium battery.

The invention has the beneficial effects that: according to the invention, N-propylene oxy phthalimide is used as a monomer, poly-N-propylene oxy phthalimide is prepared through polymerization reaction and is used as a main processing raw material of a diaphragm, and nano-alumina is used as an auxiliary material to obtain the flame-retardant nano-fiber lithium battery diaphragm; the poly-N-propylene oxy phthalimide can not only enable the prepared diaphragm to meet the performance and use requirements of a lithium battery, but also endow the diaphragm with excellent flame retardant performance, and avoid the problem that the application performance of the diaphragm is affected due to an additional flame retardant.

The specific implementation mode is as follows:

in order to make the technical means, the creation characteristics, the achievement purposes and the effects of the invention easy to understand, the invention is further described with the specific embodiments.

Nano alumina was purchased from Nanjing Tiancheng New materials Co., Ltd, model TAP-A26.

Polyethylene was purchased from medium petroleum compliant PP-FC 709M.

Example 1

(1) Adding 20g N-propyleneoxy phthalimide and 0.1g of azobisisobutyronitrile into 500mL of N, N-dimethylformamide, heating to 70 ℃ for polymerization reaction for 5h, adding water after the reaction is finished, stirring until the precipitate is not increased any more, stopping adding water, standing, filtering, and drying to obtain poly-N-propyleneoxy phthalimide.

(2) Adding 100g of poly N-propylene oxy phthalimide and 5g of nano aluminum oxide into a screw extruder, heating to 210 ℃, melting and blending, carrying out electrostatic spinning on the obtained melt at the temperature of 25 ℃, the relative humidity of 45%, the spinning speed of 0.1mL/h, the distance between a spinning nozzle and a receiving device of 15cm and the spinning voltage of 15kV, and obtaining the nano fiber lithium battery diaphragm with the thickness of 20 microns.

Example 2

Example 2 the same preparation method of the separator as in example 1 was used, except that the amounts of poly-N-propyleneoxyphthalimide and nano-alumina were adjusted.

(1) Adding 20g N-propyleneoxy phthalimide and 0.1g of azobisisobutyronitrile into 500mL of N, N-dimethylformamide, heating to 70 ℃ for polymerization reaction for 5h, adding water after the reaction is finished, stirring until the precipitate is not increased any more, stopping adding water, standing, filtering, and drying to obtain poly-N-propyleneoxy phthalimide.

(2) Adding 90g of poly N-propylene oxy phthalimide and 5g of nano aluminum oxide into a screw extruder, heating to 210 ℃, melting and blending, carrying out electrostatic spinning on the obtained melt at the temperature of 25 ℃, the relative humidity of 45%, the spinning speed of 0.1mL/h, the distance between a spinning nozzle and a receiving device of 15cm and the spinning voltage of 15kV, and obtaining the nano fiber lithium battery diaphragm with the thickness of 20 microns.

Comparative example

Comparative example the same separator preparation method as in example 1 was used, except that poly-N-propyleneoxyphthalimide was replaced with polypropylene.

Adding 100g of polypropylene and 5g of nano-alumina into a screw extruder, heating to 210 ℃, melting and blending, and carrying out electrostatic spinning on the obtained melt at the temperature of 25 ℃, the relative humidity of 45%, the spinning speed of 0.1mL/h, the distance between a spinning nozzle and a receiving device of 15cm and the spinning voltage of 15kV to obtain the nano-fiber lithium battery diaphragm with the thickness of 20 microns.

Tensile strength: the standard GB/T1040.3-2006 is adopted;

puncture strength: the standard GB/T21302-2007 is adopted;

limiting oxygen index: standard JIS-K7201-3-2008 was used.

The test was performed in triplicate and the average was taken.

TABLE 1

Item	Tensile strength/MPa	Puncture Strength/N	Oxygen index/%
				Example 1	63.4	51.5	38
Example 2	64.2	52.8	36
				Comparative example	56.7	43.3	25

As can be seen from Table 1, the preparation of poly-N-propyleneoxy-phthalimide of the present invention not only can improve the mechanical strength of the diaphragm, but also can endow the diaphragm with excellent flame retardant performance, and no additional flame retardant is required.

The foregoing shows and describes the general principles and broad features of the present invention and advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.