WO2017113275A1

WO2017113275A1 - Composite nanofiber membrane for electrochemical element, preparation method and energy storage device

Info

Publication number: WO2017113275A1
Application number: PCT/CN2015/100075
Authority: WO
Inventors: 张宣宣; 解明
Original assignee: 宁波艾特米克锂电科技有限公司
Priority date: 2015-12-31
Filing date: 2015-12-31
Publication date: 2017-07-06
Also published as: CN105655526A

Abstract

Disclosed are a composite nanofiber membrane for an electrochemical element, a preparation method and an energy storage device. The membrane is prepared by self-assembly crosslinking of high-temperature resistant nanofibers, low melting point polymer nanofibers and a flame-retardant material through a wet-process papermaking method. The membrane has a thickness of 10-80 μm, a porosity of 40%-90%, a dimensional shrinkage of 0%-5% when the membrane is at the temperature of 200°C for 30 min, a limit oxygen index (LOI) of 20%-65%, a breathability index Gurley value of 5-300 s/100cc, an electrolyte absorptivity of 150%-500%, and a mechanical stretching strength of 10-100 MPa. The membrane has excellent high-temperature resistance and flame resistance, and the preparation process is simple, and low in cost.

Description

Composite nanofiber separator for electrochemical component, preparation method and energy storage device

Technical field

The invention belongs to the technical field of separators for electrochemical components, and particularly relates to a flame retardant membrane with high temperature resistance and a preparation method thereof. The invention also relates to energy storage devices for the production of such separators, including lithium ion batteries, supercapacitors, lead acid batteries, zinc air batteries, sodium ion batteries.

Background technique

Lithium batteries have many advantages such as high energy density, high power density and long cycle life, and have received great attention in the fields of portable electronic devices, power batteries and energy storage batteries. Over-charging, short-circuit, thermal shock and mechanical shock of lithium-ion batteries may cause lithium-ion batteries to ignite and explode, posing a safety hazard to people's lives and property. In the composition of the lithium battery, the main function of the separator is to isolate the positive and negative electrodes and prevent electrons from passing freely, and at the same time allow ions to pass freely. The performance determines the interface structure and internal resistance of the battery, directly affecting the capacity of the battery. Cyclic performance, etc., and is a key part of the safety performance of lithium-ion batteries. Therefore, whether the performance of the battery separator is excellent is one of the key steps to improve the safety of the battery.

At present, the lithium ion battery separator is mainly a polyolefin separator, which has a sufficiently small pore size to effectively prevent internal short circuit of the battery, and has good uniformity, and can effectively ensure the charge and discharge performance of the battery. However, in the application process, if the battery is thermally out of control due to internal short circuit or overcharge, the internal temperature of the battery rises rapidly, and the polyolefin film cannot guarantee its integrity at high temperature (above 170 ° C), so that the positive and negative materials are A large area of contact occurs, causing the battery to explode, posing a threat to the safety of the battery. Especially in lithium ion power batteries, the design of large capacity and high power charge and discharge requires better high temperature resistance of the diaphragm. Secondly, the polyolefin membrane has poor gas permeability, which can not meet the needs of rapid battery charge and discharge, affecting the cycle life of the battery; in addition, the polyolefin membrane electrolyte has poor wettability and liquid absorption capacity, affecting the lithium battery rate performance and Long cycle performance; synthesize the above content, send It is necessary to have a battery separator having high temperature dimensional stability, good gas permeability, good electrolyte wettability and liquid absorption capability.

In order to further improve the safety of the lithium battery and inhibit the combustion of the electrolyte, a method of adding a flame retardant to the electrolyte has been adopted, and when the flame retardant reaches a certain concentration, the combustion of the electrolyte can be completely suppressed, or the flame retardant itself is incombustible. The nature of the fluoroesters as a solvent for the electrolyte. In the field of separators, the flame retardant modification of the separator also plays an important role in improving the safety of the lithium battery.

Summary of the invention

The technical problem to be solved by the present invention is to improve the thermal stability and flame retardancy of the battery separator, and at the same time improve the electrolyte wetting property, liquid absorbing ability, gas permeability and electrochemical performance of the separator, and provide a high temperature resistance for the electrochemical component. Flame-retardant composite nanofiber membrane and preparation method thereof.

In order to solve the above technical problems, the present invention firstly provides a high temperature flame retardant composite nanofiber separator for electrochemical components, having a thickness of 10-80 μm, a porosity of 40-90%, and a gas permeability index of Gurley of 5-300 s/100 cc. The electrolyte absorption rate is 150-500%, the mechanical tensile strength is 10-100 MPa, and the thermal stability is excellent. At 200 ° C, 30 min, the dimensional shrinkage is 0-5%, the flame retardancy is good, and the LOI (limit oxygen index) ) is 20-65%.

The raw materials of the present invention are based on the mass percentage content: 20-78% of cellulose nanofibers, 20-65% of low melting polymer nanofibers, and 2-35% of flame retardant materials.

The cellulose nanofibers are at least one of cellulose nanofibers separated from nanosized wood materials, seaweed cellulose nanofibers, and bacterial cellulose nanofibers obtained by culturing strains.

The cellulose nanofibers have a diameter of 10 to 1000 nm and a length of 10 to 3000 μm.

The low melting point polymer nanofibers are polymethyl methacrylate, vinylidene fluoride polymer, polyurethane, polyvinyl chloride, polyvinyl alcohol, polyolefin, polyacrylonitrile, polyethylene-vinyl acetate copolymer, One or more combinations of polyethylene succinate.

The low melting point fiber has a diameter of 10 to 1000 nm.

The flame retardant material comprises flame retardant fiber fluorocarbon, phenolic fiber, partial fluorinated fiber, chlorinated fiber, urethane fiber, nitrile chlorinated fiber, PBI, aramid fiber (1414), flame retardant polyester fiber, flame retardant acrylic fiber, flame retardant polypropylene fiber , polyarylsulfone amide, etc.; and flame retardant phosphate, phosphite, tetramethylolphosphonium chloride, organic phosphorus salt, phosphorus oxide, phosphorus-containing polyol, phosphorus-nitrogen compound, melamine, melamine cyanurate, three ( One or more of 2,3-dibromopropyl)isocyanurate, monocyanamide, dicyandiamide, cyanuric acid, thiourea, decabromodiphenyl ether.

In the flame retardant material, the flame retardant fiber has a diameter of 10 to 1000 nm; and the flame retardant has a particle diameter of less than 1 μm.

Another object of the present invention is to provide a preparation method for a low-cost, simple production process, convenient transfer, and suitable for large-scale production of the above-mentioned high-temperature-resistant flame-retardant composite nanofiber separator, characterized in that the specific steps include:

I. Weigh 20-78% of cellulose nanofibers, 20-65% of low melting polymer nanofibers and 2-35% of flame retardant materials into the dispersant by mass percentage content, and rapidly stir to form a whole uniform slurry; The dispersing agent includes one or more of deionized water, ethanol, isopropanol and glycerol;

II. Adding an additive to the slurry of step I; the additive comprises acetic acid, starch acetate, methylol starch, sodium carboxymethylcellulose, hydroxymethylcellulose, gelatin, carrageenan, chitosan, chitin Or one or more of polyethylene oxide, water-soluble polyurethane, polyacrylamide, polyvinylpyrrolidone or water-soluble polyurethane; the mass of the additive is 0.1-10% of the cellulose nanofiber;

III, the slurry after step II is diluted to a mass percentage concentration of 0.01-0.05%;

IV. The diluted slurry is subjected to dehydration molding, pressing, drying and hot rolling forming on the Internet to obtain the high temperature resistant flame-retardant composite nanofiber separator; the press line pressure is 60-120 kg/cm, The drying temperature is 70-100 ° C, the hot rolling forming temperature is 100-300 ° C, and the line pressure is 95-300 kg/cm.

The dispersing agent comprises one or more of deionized water, ethanol, isopropanol and glycerin; the additive comprises acetic acid, starch acetate, methylol starch, sodium carboxymethyl cellulose, hydroxyl group Cellulose, gelatin, carrageenan, chitosan, chitin, polyethylene oxide, water soluble polyurethane, polypropylene One or more of an enamide, a polyvinylpyrrolidone or a water-soluble polyurethane; the mass percentage of the additive is from 0.1 to 10% of the absolute dry weight of the nanocellulose fiber.

In summary, the present invention adopts a wet-laid method to prepare a flame-retardant composite nanofiber membrane with high temperature resistance by self-assembly cross-linking between high-temperature resistant nanofibers, low melting point polymer nanofibers and flame retardant materials. . The cellulose nanofibers are mainly combined by hydrogen bonding and intermolecular force, and the cellulose nanofibers are combined with the low melting point polymer nanofibers and the long diameter of the flame retardant fibers by crosslinking.

Another aspect of the present invention is to provide an energy storage device comprising a closed cell composite using a fibrillated cellulose nanofiber obtained by the above method, such as a lithium ion battery, a supercapacitor, a lead acid battery, a zinc air battery, a sodium ion battery, or the like. Diaphragm.

The invention adopts high-temperature resistant nanofibers, low melting point polymer nanofibers and flame retardant materials to self-assemble and prepare composite nanofiber membranes with high temperature resistance and excellent flame retardant performance. The beneficial effects of the invention are:

1) Once the diaphragm is exposed to a high temperature environment, the diaphragm can prevent leakage and excessive conduction and undesired ion transport blocking current conduction through the closed hole to prevent explosion. 2) The high temperature resistance of the diaphragm can ensure the stability of the diaphragm at high temperature and prevent the positive and negative electrodes from being short-circuited and fired. 3) Flame retardant performance, even if a short circuit emits a large amount of heat to reach the ignition point, the flame retardant performance of the diaphragm can inhibit the ignition. 4) The manufacturing process is simple and low cost.

DRAWINGS

The technical solutions of the present invention are further described in detail below with reference to the accompanying drawings and specific embodiments.

1 is a comparison diagram of combustion properties of (a) a polyolefin separator, (b) a pure nanocellulose separator, and (c) a heat-resistant flame-retardant composite nanofiber separator.

2 is a pre-bake size measurement chart of the heat-resistant flame-retardant composite nanofiber separator in Specific Example 1.

Fig. 3 is a graph showing the dimensional measurement after baking of the heat-resistant flame-retardant composite nanofiber membrane of the specific example 1.

detailed description

The above is a general description of the invention, and the claims of the invention are further explained below by way of specific examples. However, the invention is not limited to the embodiments discussed below, and may be embodied in different forms.

The composite nanofiber membrane for preparing an electrochemical component comprises the following steps:

Step 1. The mass ratio is 20-78% of cellulose nanofibers, 20-65% of low melting polymer nanofibers and 2-35% of flame retardant materials, and the dispersing agent is deionized water, ethanol and isopropyl. One or more of an alcohol and glycerol are rapidly agitated to form an overall uniform slurry.

Wherein the cellulose nanofiber is at least one of fibrillated cellulose nanofibers separated from nanosized wood materials, seaweed cellulose nanofibers, and bacterial cellulose nanofibers obtained by culturing the strain; cellulose nanofibers The diameter is 10-1000 nm and the length is 10-3000 μm.

The low melting point polymer nanofibers are polymethyl methacrylate, vinylidene fluoride polymer, polyurethane, polyvinyl chloride, polyvinyl alcohol, polyolefin, polyacrylonitrile, polyethylene-vinyl acetate copolymer, polybutylene One or more combinations of acid glycol esters, the low melting point polymer nanofibers have a diameter of from 10 to 1000 nm.

Flame retardant materials include flame retardant fiber fluorocarbon, phenolic fiber, vinylidene fluoride, polyvinyl chloride, vinyl chloride, nitrile chloride, PBI, aramid (1414), flame retardant polyester, flame retardant acrylic, flame retardant polypropylene, polyfang Sulfonamide; and flame retardant phosphate, phosphite, tetramethylolphosphonium chloride, organic phosphorus salt, phosphorus oxide, phosphorus-containing polyol, phosphorus-nitrogen compound, melamine, melamine cyanurate, tris(2,3- One or more of dibromopropyl)isocyanate, monocyanamide, dicyandiamide, cyanuric acid, thiourea, decabromodiphenyl ether; flame retardant materials, flame retardant fibers The diameter is 10-1000 nm; the flame retardant particle size is less than 1 μm.

Step 2, adding an additive to the slurry, the additive is acetic acid, starch acetate, methylol starch, One or more of sodium carboxymethyl cellulose, hydroxymethyl cellulose, gelatin, carrageenan, chitosan, chitin, polyethylene oxide, water-soluble polyurethane, polyacrylamide, polyvinylpyrrolidone or water-soluble polyurethane The quality of the additive is 0.1-10% of the dry amount of the cellulose nano-nanose cellulose fiber in the slurry;

Step 3, the slurry water is diluted to a mass percentage concentration of 0.01-0.05%;

Step 4: The diluted slurry is dehydrated by the Internet, and is pressed at a roller line pressure of 60-120 kg/cm. After drying at a temperature of 70-100 ° C, the temperature is 100-300 ° C and the line pressure is 100- The hot-rolling forming composite nanofiber separator of the present invention is obtained by hot-rolling at 300 kg/cm.

The obtained separator has a thickness of 10-80 μm; the porosity is 40-90%, which facilitates the passage of electrolyte ions; the dimensional shrinkage is 0-5% at a temperature of 200 ° C for 30 min; and the limiting oxygen index LOI is 20-65. %; gas permeability index Gurley value is 5-300s/100cc; electrolyte absorption rate is 150%-500%, mechanical tensile strength is 10-100MPa.

Example 1

Cellulose nanofibers, polypropylene fibers (low melting point polymer nanofibers), and aramid fibers (flame retardant materials) separated from nanosized wood materials are put into dispersing agent deionized water at a mass ratio of 75%, 20%, and 5%. Then, the slurry is prepared by high-speed mechanical stirring to achieve uniformity of the whole, and the additive acetic acid is added to the slurry, and the acetic acid mass content accounts for 0.1% of the absolute dry weight of the nanocellulose fiber. The slurry is diluted to a mass concentration of 0.01% by adding water, and the diluted slurry is dehydrated by the Internet; pressed and dried; hot-rolled at a molding temperature of 120 ° C and a line pressure of 120 kg/cm, and then subjected to hot rolling. Rolled paper, rewinding, slitting and packaging to produce a composite nanofiber separator for batteries.

The composite nanofiber membrane has a thickness of 20 μm, a porosity of 45%, an LOI of 30%, a dimensional shrinkage of 0.05% at a temperature of 200 ° C for 30 minutes, an electrolyte absorption rate of 356%, and a gas permeability Gurley value of 15 s/100 cc. The mechanical tensile strength is 80 MPa, showing excellent properties.

Example 2

The seaweed cellulose nanofiber, the polyethylene-vinyl acetate copolymer (low melting point polymer nanofiber), and the phenolic fiber (flame retardant material) are put into the dispersing agent isopropanol at a mass ratio of 20%, 65%, and 15%. Then, the slurry was prepared by high-speed mechanical stirring to achieve uniformity of the solution, and the additive hydroxymethylcellulose was added to the slurry, and the content of hydroxymethylcellulose was 10% of the absolute amount of the nanocellulose fiber. The slurry is diluted to a mass concentration of 0.01% by adding water, and the diluted slurry is dehydrated by the Internet; pressed and dried; hot-rolled at a molding temperature of 110 ° C and a line pressure of 120 kg/cm, and then subjected to hot rolling. Rolled paper, rewinding, slitting and packaging to produce a composite nanofiber separator for batteries.

The composite nanofiber membrane has a thickness of 50 μm, a porosity of 40%, and an LOI of 65%; a dimensional shrinkage of 5% at a temperature of 200 ° C for 30 minutes; an electrolyte absorption rate of 480%; and a gas permeability Gurley value of 260 s/100 cc, The mechanical tensile strength is 10 MPa, showing excellent properties.

Example 3

a mixture of bacterial cellulose nanofibers, polyvinyl alcohol (low melting point polymer nanofibers), tris(2,3-dibromopropyl)isocyanurate and monocyanamide obtained by culturing the strain (flame retardant) Material) The slurry was prepared by adding the dispersant to deionized water at a mass ratio of 75%, 20%, 5%, and then the solution was uniformly homogenized by high-speed mechanical stirring, and the additive chitosan, chitosan was added to the slurry. The mass content accounts for 10% of the absolute dryness of the cellulose nano-nanocellulose fibers. The slurry was diluted to a mass concentration of 0.05% by adding an alcohol-water mixture, and the diluted slurry was dehydrated by the Internet; pressed and dried; and hot-rolled at a molding temperature of 110 ° C and a line pressure of 120 kg/cm. Then, through the roll paper, rewinding, slitting and packaging, a composite nanofiber separator for the battery is obtained.

The composite nanofiber membrane has a thickness of 80 μm, a porosity of 90%, an LOI of 20%, a dimensional shrinkage of 2% at a temperature of 200 ° C for 30 minutes, an electrolyte absorption rate of 150%, and a gas permeability Gurley value of 150 s/100 cc. The mechanical tensile strength is 65 MPa, showing excellent properties.

Example 4

Cellulose nanofibers, polyvinyl chloride (low melting point polymerization) separated from nanosized wood materials Nanofiber), flame retardant polypropylene fiber (flame retardant material) was put into a mixture of dispersant ethanol and isopropanol at a mass ratio of 45%, 53%, 2%, and then the solution was uniformly uniformed by high-speed mechanical stirring. The slurry is prepared, and an additive water-soluble polyurethane is added to the slurry, and the water-soluble polyurethane has a mass content of 0.5% of the absolute dry weight of the nanocellulose fiber. The slurry is diluted to a mass concentration of 0.04% by adding water, and the diluted slurry is dehydrated by the Internet; pressed and dried; hot-rolled at a molding temperature of 120 ° C and a line pressure of 150 kg/cm, and then subjected to hot rolling. Rolled paper, rewinding, slitting and packaging to produce a composite nanofiber separator for batteries.

The composite nanofiber membrane has a thickness of 30 μm, a porosity of 78%, and an LOI of 28%; a dimensional shrinkage of 5% at a temperature of 200 ° C for 30 minutes; an electrolyte absorption rate of 500%; and a gas permeability Gurley value of 150 s/100 cc, The mechanical tensile strength is 100 MPa, showing excellent properties.

Example 5

Cellulose nanofibers, polymethyl methacrylate fibers (low melting point polymer nanofibers), and tetramethylolphosphonium chloride (flame retardant materials) separated from nanosized wood materials by mass ratio of 35%, 30%, 35% is put into the dispersing agent in deionized water, and then the solution is prepared by high-speed mechanical stirring to make the solution uniform. The additive carrageenan is added to the slurry. The carrageenan mass content accounts for 4% of the absolute dry weight of the nanocellulose fiber. . The slurry was diluted to a mass concentration of 0.03% by adding an alcohol-water mixture, and the diluted slurry was dehydrated by the Internet; pressed and dried; and hot-rolled at a molding temperature of 100 ° C and a line pressure of 120 kg/cm. Then, through the roll paper, rewinding, slitting and packaging, a composite nanofiber separator for the battery is obtained.

The composite nanofiber membrane has a thickness of 40 μm, a porosity of 85%, and an LOI of 20%; a dimensional shrinkage of 0.35% at a temperature of 200 ° C for 30 minutes; an electrolyte absorption rate of 328%; and a gas permeability Gurley value of 156 s/100 cc, The mechanical tensile strength is 80 MPa, showing excellent properties.

Example 6

Bacterial cellulose nanofibers, polyolefin fibers (low melting point polymer nanofibers), fluorocarbon (flame retardant materials) are put into dispersing agent deionized water at a mass ratio of 60%, 30%, and 10%, and The slurry is prepared by high-speed mechanical stirring to achieve uniformity of the solution, and the additive acetic acid is added to the slurry, and the acetic acid mass content accounts for 3% of the absolute dry weight of the nanocellulose fiber. The solvent is diluted to a mass concentration of 0.05%, and the diluted slurry is dehydrated by the Internet; pressed and dried; hot-rolled at a molding temperature of 100 ° C and a line pressure of 110 kg/cm, and then subjected to hot rolling. Rolled paper, rewinding, slitting and packaging to produce a composite nanofiber separator for batteries.

The composite nanofiber membrane has a thickness of 60 μm, a porosity of 58%, and an LOI of 47%; a dimensional shrinkage of 0.15% at a temperature of 200 ° C for 30 minutes; an electrolyte absorption rate of 296%; and a gas permeability Gurley value of 165 s/100 cc, The mechanical tensile strength was 58 MPa, showing excellent properties.

Example 7

The seaweed cellulose nanofiber, polyethylene succinate (low melting point polymer nanofiber), flame retardant polyester, flame retardant acrylic, flame retardant polypropylene (flame retardant material) by mass ratio of 45%, 25%, 30 % is put into the dispersant deionized water and glycerol, and then the slurry is prepared by high-speed mechanical stirring to achieve the overall uniformity. The additive is added with starch starch and methylol starch, starch acetate and methylol acetate. The quality and content of starch accounted for 8% of the absolute dry weight of nanocellulose fibers. The slurry is diluted to a mass concentration of 0.02% by adding water, and the diluted slurry is dehydrated by the net; pressed and dried; hot-rolled at a molding temperature of 100 ° C and a line pressure of 105 kg/cm, and then subjected to hot rolling. Rolled paper, rewinding, slitting and packaging to produce a composite nanofiber separator for batteries.

The composite nanofiber membrane has a thickness of 25 μm, a porosity of 85%, an LOI of 50%, a dimensional shrinkage of 4% at a temperature of 200 ° C for 30 minutes, an electrolyte absorption rate of 180%, and a gas permeability Gurley value of 80 s/100 cc. The mechanical tensile strength is 35 MPa, showing excellent properties.

Example 8

Cellulose nanofibers, vinylidene fluoride polymers and polybutylene succinate (low melting point polymer nanofibers), polyarylsulfone amides and perfluoropolyethers, polyvinyl chlorides, oligos, which are separated from nanosized wood materials Chlorinated fiber (flame retardant material) is put into dispersing agent deionized water at a mass ratio of 35%, 50%, 15%, and then the slurry is uniformly homogenized by high-speed mechanical stirring to prepare a slurry, which is added to the slurry. The additive is acetic acid, and the acetic acid content accounts for 2% of the absolute dry weight of the nanocellulose fiber. The slurry was diluted to a mass concentration of 0.04% by adding an alcohol-water mixture, and the diluted slurry was dehydrated by the Internet; pressed and dried; and hot-rolled at a molding temperature of 100 ° C and a line pressure of 150 kg/cm. Then, through the roll paper, rewinding, slitting and packaging, a composite nanofiber separator for the battery is obtained.

The composite nanofiber membrane has a thickness of 50 μm, a porosity of 55%, and an LOI of 46%; a dimensional shrinkage of 0.2% at a temperature of 200 ° C for 30 minutes; an electrolyte absorption rate of 433%; and a gas permeability Gurley value of 230 s/100 cc, The mechanical tensile strength is 68 MPa, showing excellent properties.

Comparative Test:

As shown in the comparative diagram of FIG. 1, a prior art polyolefin separator of the same size, a prior art pure nanocellulose separator, and a heat-resistant flame-retardant composite nanofiber membrane of the present invention are respectively fired by a lighter. It can be seen that the polyolefin membrane of Fig. 1(a) has a large shrinkage deformation and the pure nanocellulose membrane of Fig. 1(b) is spontaneously burned. On the other hand, in Fig. 1(c), the heat-resistant flame-retardant composite nanofiber membrane of the present invention has almost no dimensional shrinkage deformation and is less burned. DESCRIPTION OF THE INVENTION The present invention is a heat-resistant flame-retardant composite nanofiber membrane excellent in performance.

2 and 3 are comparative diagrams of thermal dimensional stability of the heat-resistant flame-retardant composite nanofiber separator prepared in the specific example 1. The initial length of the separator before baking was 12 cm, and it was measured after baking at a temperature of 200 ° C for 30 minutes. The length of the separator was still 12 cm, and there was almost no dimensional shrinkage.

It should be understood that the above specific embodiments are only illustrative of the technical solutions of the present invention, and are not to be construed as limiting. The technical solutions are modified or equivalent, without departing from the spirit and scope of the invention, and are intended to be included within the scope of the appended claims.

Claims

A composite nanofiber separator for electrochemical components, characterized in that the separator has a thickness of 10-80 μm; a porosity of 40-90%, which facilitates the passage of electrolyte ions; at a temperature of 200 ° C for 30 minutes, the size The shrinkage rate is 0-5%; the limiting oxygen index LOI is 20-65%; the gas permeability index Gurley value is 5-300 s/100 cc; the electrolyte absorption rate is 150-500%, and the mechanical tensile strength is 10 MPa-100 MPa.
The composite nanofiber separator for electrochemical components according to claim 1, wherein the raw materials are in mass percentage content: 20-78% of cellulose nanofibers, 20-65% of low melting point polymer nanofibers, and flame retardant. Material 2-35%.
The composite nanofiber separator for electrochemical components according to claim 3, wherein the cellulose nanofibers are cellulose nanofibers separated from nanosized wood materials, seaweed cellulose nanofibers, and cultured strains. At least one of the obtained bacterial cellulose nanofibers.
The composite nanofiber separator for electrochemical devices according to claim 2, wherein the cellulose nanofibers have a diameter of 10 to 1000 nm and a length of 10 to 3000 μm.
The composite nanofiber separator for electrochemical components according to claim 2, wherein the low melting point polymer nanofibers are polymethyl methacrylate, vinylidene fluoride polymer, polyurethane, polyvinyl chloride, One or more combinations of polyvinyl alcohol, polyolefin, polyacrylonitrile, polyethylene-vinyl acetate copolymer, polyethylene succinate.
The method of claim 5 wherein said low melting point polymer nanofibers have a diameter of from 10 to 1000 nm.
The composite nanofiber separator for electrochemical components according to claim 2, wherein the flame retardant material comprises flame retardant fiber fluorocarbon, phenolic fiber, partial fluorocarbon, polyvinyl chloride, vinyl chloride, and nitrile chloride. , PBI, aramid (1414), flame retardant polyester, flame retardant acrylic, flame retardant polypropylene, polyarylsulfone amide, etc.; and flame retardant phosphate, phosphite, tetramethylolphosphonium chloride, organic phosphorus salt, Phosphorus oxide, phosphorus-containing polyol, phosphorus-nitrogen compound, melamine, melamine cyanurate, tris(2,3-dibromopropyl) One or more of cyanuric acid ester, monocyanamide, dicyandiamide, cyanuric acid, thiourea, decabromodiphenyl ether.
The composite nanofiber separator for electrochemical components according to claim 2, wherein the flame retardant material has a diameter of 10 to 1000 nm and a flame retardant particle diameter of less than 1 μm.
A method for preparing a composite nanofiber membrane for an electrochemical component, comprising the following specific steps:

I. Weigh 20-78% of cellulose nanofibers, 20-65% of low melting polymer nanofibers and 2-35% of flame retardant materials into the dispersant by mass percentage content, and rapidly stir to form a whole uniform slurry; The dispersing agent includes one or more of deionized water, ethanol, isopropanol and glycerol;

II. Adding an additive to the slurry of step I; the additive comprises acetic acid, starch acetate, methylol starch, sodium carboxymethylcellulose, hydroxymethylcellulose, gelatin, carrageenan, chitosan, chitin Or one or more of polyethylene oxide, water-soluble polyurethane, polyacrylamide, polyvinylpyrrolidone or water-soluble polyurethane; the mass of the additive is 0.1-10% of the cellulose nanofiber;

III, the slurry after step II is diluted to a mass percentage concentration of 0.01-0.05%;

IV. The diluted slurry is subjected to dehydration molding, pressing, drying and hot rolling forming on the Internet to obtain the high temperature resistant flame-retardant composite nanofiber separator; the press line pressure is 60-120 kg/cm, The drying temperature is 70-100 ° C, the hot rolling forming temperature is 100-300 ° C, and the line pressure is 95-300 kg/cm.
An energy storage device using the composite nanofiber separator for the electrochemical component, including a lithium ion battery, a lithium sulfur battery, an alkaline battery, a super capacitor, a lead acid battery, a zinc air battery, and a sodium ion battery.