阅读说明：本技术 一种锂电池隔膜材料及其制备方法 (Lithium battery diaphragm material and preparation method thereof ) 是由 崔永哲 林文丹 曹畅 于 2021-09-07 设计创作，主要内容包括：本发明公开了一种锂电池隔膜材料及其制备方法,所述锂电池隔膜材料是使用改性剂对聚乙烯进行改性后制备得到；其中,改性剂为果胶钪复合炭化物,果胶钪复合炭化物的制备方法为：步骤1,使用果胶与氯化钪通过反应制备得到果胶钪胶体分散系；步骤2,使用三聚氰胺与二碲化锆纳米片通过升温处理,制备得到三聚氰胺不完全炭化物；步骤3,将三聚氰胺不完全炭化物置于果胶钪胶体分散系中反应后,经过干燥处理,得到果胶钪复合炭化物。本发明公开了一种锂电池隔膜材料,其中锂电池隔膜材料是采用改性后的聚乙烯,相比较于常规的聚乙烯材料,具有更好的耐高温性和浸润性,此外还使锂离子的通透性得到增强,从而提升了锂电池的耐久使用性和充放电性能。(The invention discloses a lithium battery diaphragm material and a preparation method thereof, wherein the lithium battery diaphragm material is prepared by modifying polyethylene by using a modifier; wherein the modifier is pectin scandium composite carbide, and the preparation method of the pectin scandium composite carbide comprises the following steps: step 1, pectin and scandium chloride are used for preparing a pectin scandium colloid dispersion system through reaction; step 2, heating melamine and zirconium ditelluride nanosheets to prepare incomplete melamine carbide; and 3, placing the incompletely carbonized melamine in a pectin scandium colloid dispersion system for reaction, and drying to obtain the pectin scandium composite carbonized substance. The invention discloses a lithium battery diaphragm material, wherein the lithium battery diaphragm material is prepared from modified polyethylene, has better high temperature resistance and wettability compared with the conventional polyethylene material, and enhances the permeability of lithium ions, thereby improving the durability and the charge-discharge performance of a lithium battery.)

1. The lithium battery diaphragm material is characterized in that the lithium battery diaphragm material is prepared by modifying polyethylene by using a modifier; wherein the modifier is pectin scandium composite carbide, and the preparation method of the pectin scandium composite carbide comprises the following steps:

step 1, pectin and scandium chloride are used for preparing a pectin scandium colloid dispersion system through reaction;

step 2, heating melamine and zirconium ditelluride nanosheets to prepare incomplete melamine carbide;

and 3, placing the incompletely carbonized melamine in a pectin scandium colloid dispersion system for reaction, and drying to obtain the pectin scandium composite carbonized substance.

2. The lithium battery separator material as claimed in claim 1, wherein the mass ratio of the pectin scandium composite carbide to the polyethylene is 10-18: 100.

3. The lithium battery separator material as claimed in claim 1, wherein in step 1, the pectin and the scandium chloride are subjected to a cross-linking reaction in an aqueous solution system.

4. The lithium battery separator material as claimed in claim 1, wherein in the step 2, the particle size of the zirconium ditelluride nanosheets is 20-50 nm.

5. The lithium battery separator material as claimed in claim 1, wherein in the step 2, the temperature of the temperature raising treatment is 350 to 400 ℃, and the temperature raising rate is 1 to 3 ℃.

6. The lithium battery separator material as claimed in claim 1, wherein in the step 3, the drying treatment is carried out by a spray drying method, and the temperature of the spray drying is 140-180 ℃.

7. The lithium battery separator material as claimed in claim 1, wherein the step 1 is specifically:

s1, weighing pectin, mixing with deionized water, heating to 50-60 ℃, and fully stirring until the pectin is completely dissolved to obtain a pectin solution; weighing scandium chloride, mixing with deionized water, and stirring for dissolving to obtain a scandium chloride solution; wherein the mass ratio of pectin to deionized water in the pectin solution is 1: 15-20; in the scandium chloride solution, the mass ratio of scandium chloride to deionized water is 1: 10-25;

s2, dropwise adding a scandium chloride solution into the pectin solution, stirring for 8-12 hours at 50-60 ℃, stopping heating, continuously stirring until the reaction system is cooled to room temperature, and concentrating until the volume is reduced by half to obtain a pectin scandium colloid dispersion system; wherein the mass ratio of the scandium chloride solution to the pectin solution is 1.1-1.3: 1.

8. The lithium battery separator material as claimed in claim 1, wherein the step 2 is specifically:

p1, weighing melamine, mixing the melamine with ethanol, fully stirring the mixture to be completely dissolved, adding zirconium ditelluride nanosheets, fully stirring the mixture again, and removing the ethanol under reduced pressure to obtain a melamine mixture; wherein the mass ratio of the melamine to the zirconium ditelluride nanosheets to the ethanol is 1: 0.12-0.24: 5-8;

and P2, placing the melamine mixture in a tubular furnace, introducing nitrogen as protective gas, heating to 350-400 ℃, carrying out heat preservation treatment for 2-4 hours, cooling to room temperature along with the furnace, and grinding into powder to obtain the incomplete melamine carbide.

9. The lithium battery separator material as claimed in claim 1, wherein the step 3 is specifically:

weighing incomplete melamine carbide, adding the incomplete melamine carbide into a pectin scandium colloid dispersion system, performing ultrasonic dispersion uniformly, continuously stirring at the temperature of 60-80 ℃ for 6-8 hours, and drying to obtain a pectin scandium composite carbide; wherein the mass ratio of the melamine incomplete carbide to the pectin scandium colloid dispersion system is 1: 5-10.

10. The method for preparing a lithium battery separator material as claimed in claim 1, comprising the steps of:

weighing polyethylene particles, placing the polyethylene particles in a mixing roll, heating to a molten state, adding pectin and scandium composite carbide, continuously stirring and uniformly mixing, performing extrusion molding through an extruder, casting onto the roll surface of a cooling roller rotating stably, and performing cooling shaping and rolling to obtain the lithium battery diaphragm material.

Technical Field

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

Background

The battery diaphragm is one of the key materials of the lithium battery, and mainly plays a role in preventing the contact of the positive electrode and the negative electrode, so that the short circuit caused by the contact of the positive electrode and the negative electrode is prevented, and electrolyte ions can freely migrate and pass through the battery diaphragm. Therefore, the separator has a decisive influence on the battery capacity, cycle performance, charge/discharge current density, safety and other characteristic parameters. At present, the lithium battery diaphragm used in the market is mainly a polyolefin diaphragm with a microporous structure, and comprises a single-layer polyethylene, a single-layer polypropylene and a polyolefin three-layer composite film. Although the traditional polyolefin microporous diaphragm has good chemical stability, thin thickness and higher mechanical property, the traditional polyolefin microporous diaphragm has poor high temperature resistance and can generate a hot melting phenomenon at a certain temperature, so that the anode and the cathode are in direct contact to generate a short circuit phenomenon; in addition, the nonpolar polyolefin microporous membrane has a hydrophobic surface and lower surface energy, has poor wettability to polar organic electrolyte, has poor electrolyte absorption and retention capacity, is not favorable for lithium ion transmission, and reduces the ionic conductivity of the membrane, so that the electrochemical performance and the service life of the battery are reduced.

Disclosure of Invention

The invention aims to provide a lithium battery diaphragm material and a preparation method thereof, aiming at the problems of poor high temperature resistance and poor wettability with electrolyte existing in the traditional polyolefin microporous diaphragm in the prior art.

The purpose of the invention is realized by adopting the following technical scheme:

in a first aspect, the invention provides a lithium battery diaphragm material, which is prepared by modifying polyethylene with a modifier; wherein the modifier is pectin scandium composite carbide, and the preparation method of the pectin scandium composite carbide comprises the following steps:

step 1, pectin and scandium chloride are used for preparing a pectin scandium colloid dispersion system through reaction;

step 2, heating melamine and zirconium ditelluride nanosheets to prepare incomplete melamine carbide;

and 3, placing the incompletely carbonized melamine in a pectin scandium colloid dispersion system for reaction, and drying to obtain the pectin scandium composite carbonized substance.

Preferably, the polyethylene has a molecular weight of 20 to 50 ten thousand.

Preferably, the mass ratio of the pectin scandium composite carbide to the polyethylene is 10-18: 100.

Preferably, in the step 1, the pectin and the scandium chloride are subjected to a cross-linking reaction in an aqueous solution system.

Preferably, in the step 2, the particle size of the zirconium ditelluride nanosheet is 20-50 nm.

Preferably, in the step 2, the temperature of the temperature rise treatment is 350-400 ℃, and the temperature rise rate is 1-3 ℃.

Preferably, in the step 3, the drying treatment is carried out by using a spray drying method, and the temperature of the spray drying is 140-180 ℃.

Preferably, the step 1 specifically comprises:

s1, weighing pectin, mixing with deionized water, heating to 50-60 ℃, and fully stirring until the pectin is completely dissolved to obtain a pectin solution; weighing scandium chloride, mixing with deionized water, and stirring for dissolving to obtain a scandium chloride solution; wherein the mass ratio of pectin to deionized water in the pectin solution is 1: 15-20; in the scandium chloride solution, the mass ratio of scandium chloride to deionized water is 1: 10-25;

s2, dropwise adding a scandium chloride solution into the pectin solution, stirring for 8-12 hours at 50-60 ℃, stopping heating, continuously stirring until the reaction system is cooled to room temperature, and concentrating until the volume is reduced by half to obtain a pectin scandium colloid dispersion system; wherein the mass ratio of the scandium chloride solution to the pectin solution is 1.1-1.3: 1.

Preferably, the step 2 specifically comprises:

p1, weighing melamine, mixing the melamine with ethanol, fully stirring the mixture to be completely dissolved, adding zirconium ditelluride nanosheets, fully stirring the mixture again, and removing the ethanol under reduced pressure to obtain a melamine mixture; wherein the mass ratio of the melamine to the zirconium ditelluride nanosheets to the ethanol is 1: 0.12-0.24: 5-8;

and P2, placing the melamine mixture in a tubular furnace, introducing nitrogen as protective gas, heating to 350-400 ℃, carrying out heat preservation treatment for 2-4 hours, cooling to room temperature along with the furnace, and grinding into powder to obtain the incomplete melamine carbide.

Preferably, the step 3 specifically comprises:

weighing incomplete melamine carbide, adding the incomplete melamine carbide into a pectin scandium colloid dispersion system, performing ultrasonic dispersion uniformly, continuously stirring at the temperature of 60-80 ℃ for 6-8 hours, and drying to obtain a pectin scandium composite carbide; wherein the mass ratio of the melamine incomplete carbide to the pectin scandium colloid dispersion system is 1: 5-10.

In a second aspect, the invention provides a preparation method of a lithium battery diaphragm material, which comprises the following steps:

weighing polyethylene particles, placing the polyethylene particles in a mixing roll, heating to a molten state, adding pectin and scandium composite carbide, continuously stirring and uniformly mixing, performing extrusion molding through an extruder, casting onto the roll surface of a cooling roller rotating stably, stretching, cooling, shaping and rolling to obtain the lithium battery diaphragm material.

Preferably, white oil is also added in the extrusion molding process; wherein the mass ratio of the white oil to the polyethylene particles is 0.2-0.5: 1, and the extrusion temperature is 170-200 ℃.

Preferably, the stretching is biaxial stretching, the stretching sequence being: longitudinal stretching is carried out before transverse stretching.

Preferably, the transverse stretching is performed in two passes with elution using dichloromethane between the two passes.

The invention has the beneficial effects that:

1. the invention discloses a lithium battery diaphragm material, wherein the lithium battery diaphragm material is prepared from modified polyethylene, has better high temperature resistance and wettability compared with the conventional polyethylene material, and enhances the conductivity of lithium ion, thereby improving the durability and the charge and discharge performance of a lithium battery.

2. The invention also discloses a preparation method of the lithium battery diaphragm material, which is to fuse the polyethylene material and the modified material and then press the fused polyethylene material and the modified material to form the required battery diaphragm material. The method can modify the polyethylene material, and has better performance in the aspects of high temperature resistance and service life compared with the conventional method of coating the high temperature resistant layer on the surface of the polyethylene material.

3. The invention uses pectin scandium compound carbide for modifying polyethylene, wherein the preparation process of the pectin scandium compound carbide is approximately as follows: firstly, preparing pectin scandium by forming a stable pectin scandium colloidal dispersion system by pectin and scandium ions in water; secondly, the incomplete melamine carbide is prepared by combining melamine with abundant nitrogen with orthorhombic zirconium ditelluride of a two-dimensional structure, and then performing incomplete carbonization and sintering on the zirconium ditelluride coated by the melamine; and then, reacting and combining the melamine incomplete carbide with the pectin scandium colloidal dispersion, and adsorbing the pectin scandium on the surface of the melamine incomplete carbide to form the pectin scandium composite carbide. The lithium battery diaphragm material prepared by the preparation method has the advantages of high temperature resistance, low thermal shrinkage, longer service life and better charge and discharge performance.

Detailed Description

For the purpose of more clearly illustrating the present invention and more clearly understanding the technical features, objects and advantages of the present invention, the technical solutions of the present invention will now be described in detail below, but are not to be construed as limiting the implementable scope of the present invention.

In the preparation process of the invention, the addition of pectin enhances the hydrophilicity and wettability of the material, and the reaction of pectin and scandium chloride to generate the pectin scandium enhances the high temperature resistance and hardness of the pectin, weakens the solubility of the pectin part, and improves the stability of the pectin while having better wettability. In addition, the prepared pectin scandium and the carbonized product (melamine incomplete carbonized product) are wrapped, so that the binding property of the carbonized product and polyethylene is enhanced, and according to the subsequent detection of the invention, the prepared diaphragm not only has better high temperature resistance and lower heat shrinkage compared with a common polyethylene diaphragm, but also has enhanced permeability to lithium ions in battery liquid, so that the charge and discharge performance of the battery is improved.

The incomplete melamine carbide is prepared by mixing melamine and zirconium ditelluride nanosheets to form a coating, then sintering at a certain temperature for a certain time, and coating the surface of the zirconium ditelluride nanosheets with a carbon-nitrogen compound generated by the melamine. In the process, the obtained incomplete carbonized melamine has the property of carbonized melamine and simultaneously retains the characteristics of partial organic matters, so that the incomplete carbonized melamine is more tightly combined with the zirconium diselenide nanosheets and is more easily and tightly crosslinked with the subsequent pectin bismuth through chemical bonds. In general, the treatment of incomplete carbonization sacrifices partial hardness to obtain stronger fusibility, and the diaphragm does not need very strong hardness, so the treatment mode of the invention has more practical significance.

The invention is further described below with reference to the following examples.

Example 1

A lithium battery diaphragm material is prepared by modifying polyethylene with the molecular weight of 20-50 ten thousand with a modifier; wherein the modifier is pectin scandium composite carbide, and the mass ratio of the pectin scandium composite carbide to the polyethylene is 15: 100.

The preparation method of the pectin scandium composite carbide comprises the following steps:

step 1:

s1, weighing pectin, mixing with deionized water, heating to 50-60 ℃, and fully stirring until the pectin is completely dissolved to obtain a pectin solution; weighing scandium chloride, mixing with deionized water, and stirring for dissolving to obtain a scandium chloride solution; wherein in the pectin solution, the mass ratio of pectin to deionized water is 1: 18; in the scandium chloride solution, the mass ratio of scandium chloride to deionized water is 1: 18;

s2, dropwise adding a scandium chloride solution into the pectin solution, stirring for 8-12 hours at 50-60 ℃, stopping heating, continuously stirring until the reaction system is cooled to room temperature, and concentrating until the volume is reduced by half to obtain a pectin scandium colloid dispersion system; wherein the mass ratio of the scandium chloride solution to the pectin solution is 1.2: 1.

Step 2:

p1, weighing melamine, mixing with ethanol, fully stirring, completely dissolving, adding zirconium ditelluride nanosheets with the particle size of 20-50 nm, fully stirring again, and removing ethanol under reduced pressure to obtain a melamine mixture; wherein the mass ratio of the melamine to the zirconium ditelluride nanosheets to the ethanol is 1:0.19: 7;

and P2, placing the melamine mixture in a tubular furnace, introducing nitrogen as protective gas, heating to 380 ℃ at the heating rate of 2 ℃, carrying out heat preservation treatment for 3 hours, cooling to room temperature along with the furnace, and grinding into powder to obtain the incomplete melamine carbide.

And step 3:

weighing incomplete melamine carbide, adding the incomplete melamine carbide into a pectin scandium colloid dispersion system, performing ultrasonic dispersion uniformly, continuously stirring at the temperature of 60-80 ℃ for 6-8 hours, and performing spray drying to obtain a pectin scandium composite carbide; wherein the mass ratio of the melamine incomplete carbide to the pectin scandium colloidal dispersion is 1:7, and the temperature of spray drying is 160 ℃.

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

weighing polyethylene particles, placing the polyethylene particles in a mixing roll, heating the polyethylene particles to a molten state, adding pectin and scandium composite carbide, continuously stirring and uniformly mixing the mixture, performing extrusion molding through an extruder, casting the mixture onto the roll surface of a cooling roller rotating stably, stretching the mixture, cooling and shaping the mixture, and rolling the stretched mixture to obtain a lithium battery diaphragm material;

wherein, white oil is also added in the extrusion molding process, the mass of the white oil and the polyethylene particles is 0.4:1, and the extrusion temperature is 185 ℃; the stretching is bidirectional stretching, and the stretching sequence is as follows: and performing longitudinal stretching and transverse stretching, wherein the transverse stretching is performed twice, and dichloromethane is used for elution between the two transverse stretching.

Example 2

A lithium battery diaphragm material is prepared by modifying polyethylene with the molecular weight of 20-50 ten thousand with a modifier; wherein the modifier is pectin scandium composite carbide, and the mass ratio of the pectin scandium composite carbide to the polyethylene is 10: 100.

The preparation method of the pectin scandium composite carbide comprises the following steps:

step 1:

s1, weighing pectin, mixing with deionized water, heating to 50-60 ℃, and fully stirring until the pectin is completely dissolved to obtain a pectin solution; weighing scandium chloride, mixing with deionized water, and stirring for dissolving to obtain a scandium chloride solution; wherein the mass ratio of pectin to deionized water in the pectin solution is 1: 15; in the scandium chloride solution, the mass ratio of scandium chloride to deionized water is 1: 10;

s2, dropwise adding a scandium chloride solution into the pectin solution, stirring for 8-12 hours at 50-60 ℃, stopping heating, continuously stirring until the reaction system is cooled to room temperature, and concentrating until the volume is reduced by half to obtain a pectin scandium colloid dispersion system; wherein the mass ratio of the scandium chloride solution to the pectin solution is 1.1: 1.

Step 2:

p1, weighing melamine, mixing with ethanol, fully stirring, completely dissolving, adding zirconium ditelluride nanosheets with the particle size of 20-50 nm, fully stirring again, and removing ethanol under reduced pressure to obtain a melamine mixture; wherein the mass ratio of the melamine to the zirconium ditelluride nanosheets to the ethanol is 1:0.12: 5;

and P2, placing the melamine mixture in a tubular furnace, introducing nitrogen as protective gas, heating to 350 ℃ at the heating rate of 1 ℃, carrying out heat preservation treatment for 2 hours, cooling to room temperature along with the furnace, and grinding into powder to obtain the incomplete melamine carbide.

And step 3:

weighing incomplete melamine carbide, adding the incomplete melamine carbide into a pectin scandium colloid dispersion system, performing ultrasonic dispersion uniformly, continuously stirring at the temperature of 60-80 ℃ for 6-8 hours, and performing spray drying to obtain a pectin scandium composite carbide; wherein the mass ratio of the melamine incomplete carbide to the pectin scandium colloidal dispersion is 1:5, and the temperature of spray drying is 140 ℃.

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

weighing polyethylene particles, placing the polyethylene particles in a mixing roll, heating the polyethylene particles to a molten state, adding pectin and scandium composite carbide, continuously stirring and uniformly mixing the mixture, performing extrusion molding through an extruder, casting the mixture onto the roll surface of a cooling roller rotating stably, stretching the mixture, cooling and shaping the mixture, and rolling the stretched mixture to obtain a lithium battery diaphragm material;

wherein, white oil is also added in the extrusion molding process, the mass of the white oil and the polyethylene particles is 0.2:1, and the extrusion temperature is 170 ℃; the stretching is bidirectional stretching, and the stretching sequence is as follows: and performing longitudinal stretching and transverse stretching, wherein the transverse stretching is performed twice, and dichloromethane is used for elution between the two transverse stretching.

Example 3

A lithium battery diaphragm material is prepared by modifying polyethylene with the molecular weight of 20-50 ten thousand with a modifier; wherein the modifier is pectin scandium composite carbide, and the mass ratio of the pectin scandium composite carbide to the polyethylene is 18: 100.

The preparation method of the pectin scandium composite carbide comprises the following steps:

step 1:

s1, weighing pectin, mixing with deionized water, heating to 50-60 ℃, and fully stirring until the pectin is completely dissolved to obtain a pectin solution; weighing scandium chloride, mixing with deionized water, and stirring for dissolving to obtain a scandium chloride solution; wherein in the pectin solution, the mass ratio of pectin to deionized water is 1: 20; in the scandium chloride solution, the mass ratio of scandium chloride to deionized water is 1: 25;

s2, dropwise adding a scandium chloride solution into the pectin solution, stirring for 8-12 hours at 50-60 ℃, stopping heating, continuously stirring until the reaction system is cooled to room temperature, and concentrating until the volume is reduced by half to obtain a pectin scandium colloid dispersion system; wherein the mass ratio of the scandium chloride solution to the pectin solution is 1.3: 1.

Step 2:

p1, weighing melamine, mixing with ethanol, fully stirring, completely dissolving, adding zirconium ditelluride nanosheets with the particle size of 20-50 nm, fully stirring again, and removing ethanol under reduced pressure to obtain a melamine mixture; wherein the mass ratio of the melamine to the zirconium ditelluride nanosheets to the ethanol is 1:0.24: 8;

and P2, placing the melamine mixture in a tubular furnace, introducing nitrogen as protective gas, heating to 400 ℃ at the heating rate of 3 ℃, carrying out heat preservation treatment for 4 hours, cooling to room temperature along with the furnace, and grinding into powder to obtain the incomplete melamine carbide.

And step 3:

weighing incomplete melamine carbide, adding the incomplete melamine carbide into a pectin scandium colloid dispersion system, performing ultrasonic dispersion uniformly, continuously stirring at the temperature of 60-80 ℃ for 6-8 hours, and performing spray drying to obtain a pectin scandium composite carbide; wherein the mass ratio of the melamine incomplete carbide to the pectin scandium colloidal dispersion is 1:10, and the temperature of spray drying is 180 ℃.

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

weighing polyethylene particles, placing the polyethylene particles in a mixing roll, heating the polyethylene particles to a molten state, adding pectin and scandium composite carbide, continuously stirring and uniformly mixing the mixture, performing extrusion molding through an extruder, casting the mixture onto the roll surface of a cooling roller rotating stably, stretching the mixture, cooling and shaping the mixture, and rolling the stretched mixture to obtain a lithium battery diaphragm material;

wherein, white oil is also added in the extrusion molding process, the mass of the white oil and the polyethylene particles is 0.5:1, and the extrusion temperature is 200 ℃; the stretching is bidirectional stretching, and the stretching sequence is as follows: and performing longitudinal stretching and transverse stretching, wherein the transverse stretching is performed twice, and dichloromethane is used for elution between the two transverse stretching.

Comparative example 1

A lithium battery diaphragm material is prepared by modifying polyethylene with the molecular weight of 20-50 ten thousand with a modifier; wherein the modifier is pectin carbide, and the mass ratio of the pectin carbide to the polyethylene is 15: 100.

The preparation method of the pectin carbide comprises the following steps:

step 1:

weighing pectin, mixing with deionized water, heating to 50-60 ℃, and fully stirring until the pectin is completely dissolved to obtain a pectin solution; wherein in the pectin solution, the mass ratio of pectin to deionized water is 1: 18;

step 2:

p1, weighing melamine, mixing with ethanol, fully stirring, completely dissolving, adding zirconium ditelluride nanosheets with the particle size of 20-50 nm, fully stirring again, and removing ethanol under reduced pressure to obtain a melamine mixture; wherein the mass ratio of the melamine to the zirconium ditelluride nanosheets to the ethanol is 1:0.19: 7;

and P2, placing the melamine mixture in a tubular furnace, introducing nitrogen as protective gas, heating to 380 ℃ at the heating rate of 2 ℃, carrying out heat preservation treatment for 3 hours, cooling to room temperature along with the furnace, and grinding into powder to obtain the incomplete melamine carbide.

And step 3:

weighing incomplete melamine carbide, adding the incomplete melamine carbide into a pectin scandium colloid dispersion system, performing ultrasonic dispersion uniformly, continuously stirring at the temperature of 60-80 ℃ for 6-8 hours, and performing spray drying to obtain a pectin scandium composite carbide; wherein the mass ratio of the melamine incomplete carbide to the pectin scandium colloidal dispersion is 1:7, and the temperature of spray drying is 160 ℃.

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

weighing polyethylene particles, placing the polyethylene particles in a mixing roll, heating the polyethylene particles to a molten state, adding pectin carbide, continuously stirring and uniformly mixing the mixture, performing extrusion molding through an extruder, casting the mixture onto the roll surface of a cooling roller rotating stably, stretching the mixture, cooling and shaping the mixture, and rolling the stretched mixture to obtain a lithium battery diaphragm material;

wherein, white oil is also added in the extrusion molding process, the mass of the white oil and the polyethylene particles is 0.4:1, and the extrusion temperature is 185 ℃; the stretching is bidirectional stretching, and the stretching sequence is as follows: and performing longitudinal stretching and transverse stretching, wherein the transverse stretching is performed twice, and dichloromethane is used for elution between the two transverse stretching.

Comparative example 2

A lithium battery diaphragm material is prepared by modifying polyethylene with the molecular weight of 20-50 ten thousand with a modifier; wherein the modifier is pectin scandium carbide, and the mass ratio of the pectin scandium carbide to the polyethylene is 15: 100.

The preparation method of the pectin scandium carbide comprises the following steps:

step 1:

s1, weighing pectin, mixing with deionized water, heating to 50-60 ℃, and fully stirring until the pectin is completely dissolved to obtain a pectin solution; weighing scandium chloride, mixing with deionized water, and stirring for dissolving to obtain a scandium chloride solution; wherein in the pectin solution, the mass ratio of pectin to deionized water is 1: 18; in the scandium chloride solution, the mass ratio of scandium chloride to deionized water is 1: 18;

s2, dropwise adding a scandium chloride solution into the pectin solution, stirring for 8-12 hours at 50-60 ℃, stopping heating, continuously stirring until the reaction system is cooled to room temperature, and concentrating until the volume is reduced by half to obtain a pectin scandium colloid dispersion system; wherein the mass ratio of the scandium chloride solution to the pectin solution is 1.2: 1.

Step 2:

p1, weighing melamine, mixing with ethanol, fully stirring, completely dissolving, adding zirconium ditelluride nanosheets with the particle size of 20-50 nm, fully stirring again, and removing ethanol under reduced pressure to obtain a melamine mixture; wherein the mass ratio of the melamine to the zirconium ditelluride nanosheets to the ethanol is 1:0.19: 7;

and P2, placing the melamine mixture in a tubular furnace, introducing nitrogen as protective gas, heating to 800 ℃ at the heating rate of 2 ℃, carrying out heat preservation treatment for 3 hours, cooling to room temperature along with the furnace, and grinding into powder to obtain the melamine complete carbide.

And step 3:

weighing melamine complete carbide, adding the melamine complete carbide into a pectin scandium colloid dispersion system, carrying out ultrasonic dispersion uniformly, carrying out continuous stirring treatment at the temperature of 60-80 ℃ for 6-8 h, and carrying out spray drying treatment to obtain a pectin scandium composite carbide; wherein the mass ratio of the melamine complete carbide to the pectin scandium colloidal dispersion is 1:7, and the temperature of spray drying is 160 ℃.

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

weighing polyethylene particles, placing the polyethylene particles in a mixing roll, heating the polyethylene particles to a molten state, adding pectin and scandium carbide, continuously stirring and uniformly mixing the mixture, performing extrusion molding through an extruder, casting the mixture onto the roll surface of a cooling roller rotating stably, stretching, cooling, shaping and rolling to obtain a lithium battery diaphragm material;

wherein, white oil is also added in the extrusion molding process, the mass of the white oil and the polyethylene particles is 0.4:1, and the extrusion temperature is 185 ℃; the stretching is bidirectional stretching, and the stretching sequence is as follows: and performing longitudinal stretching and transverse stretching, wherein the transverse stretching is performed twice, and dichloromethane is used for elution between the two transverse stretching.

For more clearly explaining the invention, the battery separator materials prepared in examples 1 to 3 and comparative examples 1 to 2 were prepared to have a thickness of (15 ± 0.1) μm and were tested in performance, wherein the tensile strength was tested according to the standard GB/T1040.3-2006, the air permeability, the thermal shrinkage and the ionic conductivity were tested according to the standard GB/T36363-2018, and the thermal shrinkage was the shrinkage after treatment at 130 ℃ for 1 hour.

The results are shown in table 1:

table 1 comparison of the properties of different battery separators

As can be clearly obtained from table 1, examples 1 to 3 of the present invention have better mechanical strength, air permeability, and ionic conductivity, lower thermal shrinkage, higher film breaking temperature, and smaller contact angle with water, indicating better high temperature resistance, wettability, and high ion permeability.

Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the protection scope of the present invention, although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.