CN102496464A - Super capacitance battery diaphragm, preparing method thereof and application thereof - Google Patents

Abstract

The invention relates to a separator for a supercapacitor battery. The surface of the fiber forming the separator has a permanent hydrophilic group sulfonic acid group and an acrylic monomer. The fiber forming the separator is composed of polyolefin sheath-core fiber or polypropylene It is composed of fiber or polyolefin sheath-core fiber and polypropylene fiber, which are formed by wet papermaking or dry carding process to make a laminated diaphragm matrix. It has the characteristics of excellent liquid retention ability, high strength, strong ion migration ability, high charge retention rate, and low internal resistance, which can meet the high-current charging and discharging requirements of supercapacitor batteries, and has excellent low-temperature performance.

Description

Supercapacitor battery separator, its preparation method and application

technical field

The invention relates to a separator for batteries; in particular, it relates to a separator for a supercapacitor battery and a preparation method and application thereof.

Background technique

History has entered the 21st century. With the deepening of the global energy crisis, the depletion of oil resources and the increasing harm of air pollution and global temperature rise, governments and automobile companies generally recognize that energy saving and emission reduction are the main focus of future automobile technology development. Direction, the development of electric vehicles has become the best way to solve these two technical difficulties. Electric vehicles have also become the choice of countries around the world and a focus of technology competition. From the perspective of energy and environment, the development of new energy vehicles is an inevitable choice for our country.

The supercapacitor battery (that is, a kind of supercapacitor) adopts the comprehensive performance balance design idea, and cleverly introduces the activated carbon material into the negative electrode of the nickel-metal hydride battery, that is, one electrode uses the electrode activated carbon electrode, while the other electrode uses the capacitive electrode material or The battery electrode realizes the combination of ordinary supercapacitor and battery, so as to have the excellent performance of ordinary supercapacitor and storage battery. Supercapacitor battery is a new type of power source for both military and civilian use. It has many characteristics such as high energy density, high power density, high charge and discharge efficiency, good high and low temperature performance, long cycle life, safety and environmental protection, and high cost performance. The bottleneck problem of automobile power supply technology can also be applied in surface ships, submarines, new aircraft, missiles and aerospace fields.

The three key materials of supercapacitor batteries include positive and negative electrode materials and diaphragm materials. Since a supercapacitor battery is a combination of an ordinary supercapacitor and a battery, the separator material must meet its corresponding technical requirements, and must have excellent liquid retention capacity, high strength, strong ion migration ability, high charge retention rate, and low internal resistance. It meets the high-current charging and discharging requirements of supercapacitor batteries, and has excellent low-temperature performance and other characteristics.

The battery separator materials currently on the market are mainly for nickel-metal hydride batteries, lithium-ion batteries, ordinary supercapacitors, etc., which cannot meet or give full play to the excellent characteristics of supercapacitor batteries. Therefore, it is necessary to research and develop a new separator material to meet the needs of supercapacitors. Battery usage requirements.

Contents of the invention

The technical problem solved by the present invention is to provide a supercapacitor battery diaphragm, which has the characteristics of excellent liquid retention capacity, high strength, strong ion migration ability, high charge retention rate, low internal resistance, etc., and can meet the high-current charge and discharge of supercapacitor batteries Requirements, and has excellent low temperature performance.

A further object of the present invention is to provide a preparation method of the supercapacitor battery diaphragm.

In order to achieve the above object, the technical scheme adopted in the present invention is:

A diaphragm for a supercapacitor battery, the surface of fibers forming the diaphragm has both sulfonic acid groups and acrylic monomers, and the fibers constituting the diaphragm are composed of polyolefin sheath-core fibers and/or polypropylene fibers.

The supercapacitor battery diaphragm provided by the present invention has a permanent hydrophilic group sulfonic acid group and an acrylic monomer on the fiber surface of the diaphragm, and the fiber constituting the diaphragm is composed of polyolefin sheath-core fiber or polypropylene fiber or is composed of Composed of polyolefin sheath-core fiber and polypropylene fiber, it is formed by wet papermaking or dry carding process to make a laminated diaphragm matrix. Such a supercapacitor battery separator has excellent liquid retention capacity, high strength, strong ion migration ability, high charge retention rate, and low internal resistance, which meets the high-current charging and discharging requirements of supercapacitor batteries, and has excellent low-temperature performance.

In the supercapacitor battery separator of the present invention, the sulfonic acid groups can be evenly grafted on the surface of the fibers forming the separator through sulfonation treatment, and the degree of sulfonation is preferably 0.7% to 1.0%; other known sulfonic acids can also be used base grafting means.

In the supercapacitor battery separator of the present invention, the acrylic monomer can be uniformly grafted on the surface of the fibers forming the separator after sulfonation treatment through physicochemical emulsification and diffusion technology, and the monomer grafting rate is preferably 0.1% to 2.0%. ; Other known acrylic monomer grafting means can also be used. The acrylic monomer is one or more of acrylic acid monomer, methacrylic acid, methyl acrylate, ethyl acrylate, itaconic acid, unsaturated carvone acid, sulfamic acid, alkenyl sulfonic acid mixture.

In the supercapacitor battery separator of the present invention, the preferred composition of fibers constituting the separator is: the weight ratio of polyolefin sheath-core fibers is 80% to 100%, and the weight ratio of polypropylene fibers is 20% to 100%. The denier of the polyolefin sheath-core fiber is 0.6D-1.0D, and the fiber length is 3mm-38mm; the denier of the polypropylene fiber is 0.6D-0.8D, and the fiber length is 5mm-38mm.

Further, the present invention provides a method for preparing the diaphragm of the supercapacitor battery. First, polyolefin sheath-core fibers and/or polypropylene fibers are made into a laminated diaphragm matrix, and then the diaphragm matrix is subjected to sulfonation treatment. After sulfonation, the diaphragm Then emulsification diffusion grafting treatment is carried out, so that the acrylic monomer is evenly grafted on the surface of the sulfonated fiber.

In the above preparation method, the polyolefin sheath-core fiber and/or the polypropylene fiber can be formed by wet papermaking or dry carding process to make a laminated diaphragm matrix.

The above preparation method, wherein the sulfonation treatment can adopt known technical means, a preferred implementation process is: use gaseous sulfur trioxide with a concentration of more than 90%, and carry out sulfonation treatment on the diaphragm substrate in the sulfonation reactor , the temperature in the sulfonation reactor is 60°C to 100°C, the concentration of sulfur trioxide is 90%, and the sulfonation speed is 20 m/min. The alkali is neutralized, wherein the concentration of lye potassium hydroxide or sodium hydroxide is 1%, and then washed with deionized water until neutral, and then dried.

The above-mentioned preparation method, wherein said emulsification diffusion grafting treatment can adopt known technical means, a kind of preferred implementation process is: acrylic monomer, emulsification diffusion agent and deionized water are formulated into graft modification liquid, wherein The weight concentration of the acrylic monomer is 10% to 30%; the weight concentration of the emulsifying and diffusing agent is 0.1% to 0.6%; after the continuous operation of the sulfonated diaphragm is etched at normal temperature and pressure, it enters the grafted In the modified solution, and maintain the inert gas continuously fed into the modified solution, fully carry out the polymerization and grafting reaction at 75°C. The emulsifying diffusing agent is preferably alkyl ether sulfate and alkylphenol ether disulfonate.

According to a preferred embodiment of the present invention, the preparation method of the supercapacitor battery diaphragm provided by the present invention specifically includes the following steps:

(1) Preparation of diaphragm matrix: cut polyolefin sheath-core fiber or polypropylene fiber or polyolefin sheath-core fiber and polypropylene fiber into short fibers of 25mm to 38mm, and use dry carding process to form them into low-gram Heavy single-layer separator matrix; or cut polyolefin sheath-core fibers or polyolefin sheath-core fibers and polypropylene fibers with various fibers into ultra-short fibers of 3mm to 10mm, using wet papermaking technology, after beating, forming, Dehydration and drying to make a low-weight single-layer diaphragm substrate; the multi-layer low-gram weight single-layer diaphragm substrate is laminated using a laminator, and the surface density is controlled according to the technical requirements of product design, and adjusted to the required density through a rolling mill. thickness of the diaphragm substrate.

(2) Sulfonation treatment: use gaseous sulfur trioxide with a concentration of more than 90% to perform sulfonation treatment on the diaphragm substrate in a sulfonation reactor, and the temperature in the sulfonation reactor is 60°C to 100°C, preferably 70°C, The concentration of sulfur trioxide is 90%, and the sulfonation speed is 20 m/min. After sulfonation treatment, the sulfonic acid group is uniformly grafted on the surface of the fiber forming the diaphragm, and neutralized by alkali, in which the lye potassium hydroxide or hydroxide The concentration of sodium is 1%, and then washed with deionized water until neutral, and then dried. Control the degree of sulfonation in the range of 0.7% to 1.0%, and the O/C in the range of 0.01 to 0.05.

(3) Grafting treatment of physical and chemical emulsification diffusion technology: acrylic monomer, emulsification diffusion agent and deionized water are made into graft modification liquid, and the concentration of acrylic monomer (weight) is 10% to 30%; emulsification diffusion The concentration of the agent (weight) is 0.1% to 0.6%; after the continuous operation of the sulfonated diaphragm is etched under the condition of normal temperature and pressure, it enters the acrylic monomer solution containing the emulsified diffusing agent, and keeps the modified liquid The inert gas is continuously fed into the medium, and the polymerization and grafting reaction is fully carried out under the condition of 75 ° C, and the grafting rate of the monomer is controlled within the range of 0.1% to 2.0%.

(4) Suppressing, coiling, and packaging the diaphragm base that has been grafted with sulfonation and physicochemical emulsification and diffusion technology to produce a supercapacitor cell diaphragm.

The beneficial effects of the supercapacitor battery diaphragm of the present invention are:

(1) The surface of the fibers that make up the diaphragm has both permanent hydrophilic groups, sulfonic acid groups and acrylic monomers. The fibers that make up the diaphragm are composed of polyolefin sheath-core fibers or polypropylene fibers or polyolefin sheath-core fibers. Composed of fiber and polypropylene fiber, it is formed by wet papermaking or dry carding process to make a laminated diaphragm matrix. In this way, the supercapacitor battery separator has excellent liquid retention capacity, high strength, strong ion migration ability, high charge retention rate, and low internal resistance, which meets the high-current charging and discharging requirements of supercapacitor batteries, and has excellent low-temperature performance.

(2) The present invention preferably adopts two hydrophilic treatment methods of sulfonation treatment and grafting of physical and chemical emulsification diffusion technology to treat the fibers forming the diaphragm, and both sulfonic acid groups and acrylic monomers are effectively grafted to the fibers On the carbon atoms on the surface, this can ensure that the separator has permanent hydrophilic ability and liquid retention ability, improves ion migration ability and exchange ability, effectively reduces internal resistance, improves high current charge and discharge ability, and has excellent charge power retention. At the same time, the physical and chemical emulsification and diffusion technology grafting treatment effectively compensates for the damage to the strength of the separator by sulfonation treatment, homogenizes the pore size, reduces the short circuit rate, and makes the supercapacitor battery separator better meet the use of supercapacitor batteries. By adopting the physical and chemical emulsification and diffusion technology, the hydrophilic group sulfonic acid group and the acrylic monomer are combined with the carbon (C) atoms on the surface of the fiber, which is permanent.

Detailed ways

For further illustrating the present invention, specifically illustrate in conjunction with following examples:

The degree of sulfonation is related to the ratio between the number of sulfur atoms (S) and the number of oxygen atoms (O) of the sulfonic acid group (-SO ₃ H) treated on the fiber surface, and the number of carbon atoms (C) on the fiber surface , wherein the nominal O/C ratio is within 0.005-0.05 based on the O/C ratio, and O and C do not include O and C in acrylic monomers; the molar ratio of sulfur and carbon elements ranges from 0.2 to 1.5mass %; the ion exchange capacity of the membrane satisfies 0.001-0.15 (equivalent/m ² ).

Example 1

The fiber material is compounded according to the weight ratio, that is, polyolefin sheath-core fiber, fiber fineness 0.8D, length 38mm, content 80%; polypropylene fiber, fineness 0.8D, length 38mm, content 20%, the above-mentioned fiber is dry-processed Formed by carding process, dried in hot air at 120°C to make a separator substrate with a single-layer density of 18g/ ^m2 , and three layers of single-layer separator substrates with a density of 18g/ ^m2 were laminated using a laminator and adjusted with a rolling mill To a certain thickness, a diaphragm substrate is made, and the surface density of the diaphragm substrate is 54g/m ² .

The diaphragm matrix is transported to the sulfonation reactor, and sulfonated with 90% concentration of gaseous sulfur trioxide, and the sulfonated matrix is transported to the alkali cleaning tank for neutralization reaction. The concentration of potassium hydroxide is 1%, and the alkali washing The speed is controlled at 20 m/min, and then rinsed with deionized water, rolled, and dried at a temperature of 100°C to obtain a diaphragm base cloth with a sulfonation degree of 0.8% and an O/C of 0.04.

Then, after the sulfonated diaphragm in continuous operation is etched under the condition of normal temperature and pressure, it enters the acrylic monomer solution containing emulsified diffusing agent, and carries out emulsified diffusion grafting treatment, so that the acrylic monomer is evenly grafted on the surface of the sulfonated fiber.

Acrylic acid monomer, alkyl ether sulfate and deionized water are made into graft modification liquid, and the concentration of acrylic acid monomer (weight) is 10%; The concentration of alkyl ether sulfate (weight) is 0.2%; After the sulfonated diaphragm is etched under normal temperature and pressure conditions, it enters the grafting modification solution, and keeps inert gas continuously flowing into the modification solution, and performs sufficient polymerization and grafting reaction at 75°C to control The monomer grafting rate is 0.2%.

Separator matrix grafted by sulfonation and physicochemical emulsification and diffusion technology is pressed, coiled and packaged to produce a supercapacitor battery separator with an areal density of 55g/m ² and a thickness of 0.12mm.

Example 2

100% polyolefin sheath-core fiber is used to make the diaphragm matrix. The fiber fineness is 0.8D and the fiber length is 3mm to 10mm. Using wet papermaking technology, it is made into a single layer with a density of 18g after beating, molding, dehydration and drying. /m ² of the diaphragm substrate, the three-layer single-layer diaphragm substrate with a density of 18g/m ² is laminated with a laminator, and adjusted to a certain thickness with a rolling mill to make a diaphragm substrate. The surface density of the diaphragm substrate is 54g/m ² .

Then carry out treatment according to the sulfonation treatment of Example 1 and the graft treatment method and sequence of physical and chemical emulsification and diffusion technology, and make a supercapacitor battery diaphragm with an area density of 55g/m ² and a thickness of 0.12mm, and a sulfonation degree of 0.8%. , O/C is 0.041, monomer grafting rate is 0.2%.

Example 3

Firstly, 100% polypropylene fiber is used, of which the fineness is 0.8D and the length is 38mm. It is formed by dry carding process, and dried in hot air at 130°C to make a separator substrate with a single layer density of 24g/ ^m2 .

Then use 100% polyolefin sheath-core fiber, the fiber fineness is 0.8D, and the fiber length is 3mm to 10mm. Using wet papermaking technology, it is made into a single layer with a density of 23g/ ^m2 after beating, molding, dehydration, and drying. the diaphragm base.

Laminate the 3-layer single-layer diaphragm matrix using a laminator, wherein the middle layer is a single-layer diaphragm matrix of 100% polypropylene fiber, and the other two single layers are a single-layer diaphragm matrix of 100% polyolefin sheath-core fiber. Adjust to a certain thickness to make a diaphragm base, and the surface density of the diaphragm base is 70g/m ² .

The diaphragm matrix is transported to the sulfonation reactor, and sulfonated with 90% concentration of gaseous sulfur trioxide, and the sulfonated matrix is transported to the alkali cleaning tank for neutralization reaction. The concentration of potassium hydroxide is 1%, and the alkali washing The speed is controlled at 20 m/min, and then rinsed with deionized water, rolled, and dried at a temperature of 105°C to obtain a diaphragm base cloth with a sulfonation degree of 0.9% and an O/C of 0.043.

Then, after the sulfonated diaphragm in continuous operation is etched under the condition of normal temperature and pressure, it enters the acrylic monomer solution containing emulsified diffusing agent, and carries out emulsified diffusion grafting treatment, so that the acrylic monomer is evenly grafted on the surface of the sulfonated fiber.

Methyl acrylate, alkylphenol ether disulfonate and deionized water are made into graft modification liquid, methyl acrylate (weight) concentration is 20%; Alkylphenol ether disulfonate (weight) concentration is 0.4 %; After the sulfonated diaphragm in continuous operation was etched under normal temperature and pressure conditions, it was put into the graft modification solution, and the inert gas was kept continuously flowing into the modification solution, and fully carried out under the condition of 75°C. In the polymerization grafting reaction, the monomer grafting rate is controlled at 0.5%.

Separator matrix grafted by sulfonation and physicochemical emulsification and diffusion technology is pressed, coiled and packaged to produce a supercapacitor battery separator with an areal density of 72g/m ² and a thickness of 0.22mm.

Example 4

Using 100% polyolefin sheath-core fiber to make the diaphragm matrix, the fiber fineness is 0.8D, and the fiber length is 3mm to 10mm. Using wet papermaking technology, it is made into a single layer with a density of 20g after beating, molding, dehydration, and drying. /m2 of the diaphragm substrate, three layers of single-layer diaphragm substrates with a density of 20g/ ^m2 are laminated using a laminator, and adjusted to a certain thickness with a rolling mill to make a diaphragm substrate. The surface density of the diaphragm substrate is 60g/ ^m2 .

Then carry out treatment according to the sulfonation treatment of embodiment 3 and the grafting treatment method and order of physical and chemical emulsification and diffusion technology, and make a supercapacitor battery diaphragm with an area density of 62g/m ² and a thickness of 0.18mm, and a sulfonation degree of 0.85%. , O/C is 0.042, monomer grafting rate is 0.4%.

Using the above batching conditions and processing methods, the performance indicators of the supercapacitor battery separator are shown in Table 1.

Table 1

The supercapacitor battery diaphragm of the present invention has permanent hydrophilic group sulfonic acid groups and acrylic monomers on the surface of the fibers forming the diaphragm, and the sulfonic acid groups are evenly grafted on the surface of the fibers forming the diaphragm through sulfonation treatment. The monomers are evenly grafted on the surface of the sulfonated fibers that make up the diaphragm through physical and chemical emulsification and diffusion technology. The fibers that make up the diaphragm are composed of polyolefin sheath-core fibers or polypropylene fibers or polyolefin sheath-core fibers. Composed with polypropylene fiber, it is formed by wet papermaking or dry carding process to make a laminated diaphragm matrix. In this way, the supercapacitor battery separator has excellent liquid retention capacity, high strength, strong ion migration ability, high charge retention rate, and low internal resistance, which meets the high-current charging and discharging requirements of supercapacitor batteries, and has excellent low-temperature performance. Due to the simultaneous use of sulfonation treatment and physical and chemical emulsification diffusion technology grafting two hydrophilic treatment methods to treat the fibers that make up the diaphragm, and both sulfonic acid groups and acrylic monomers are effectively grafted to the carbon atoms on the fiber surface , which ensures that the separator has permanent hydrophilic ability and liquid retention ability, improves ion migration ability and exchange ability, effectively reduces internal resistance, improves high current charge and discharge ability, and has excellent charge retention ability. Physicochemical emulsification diffusion technology grafting treatment effectively compensates for the damage to the strength of the separator by sulfonation treatment, homogenizes the pore size, reduces the short circuit rate, and makes the supercapacitor battery separator better meet the use of supercapacitor batteries.

Comparative example:

The battery separator materials currently on the market are mainly for nickel-metal hydride batteries, lithium-ion batteries, ordinary supercapacitors, etc., which cannot meet or give full play to the excellent characteristics of supercapacitor batteries.

In order to further illustrate the excellent performance and wide application range of the product of the present invention, the product and other separators were tested on nickel-metal hydride batteries. Carry out routine index test and be used for the part battery of model AAA700 battery with the supercapacitor battery separator of the gained supercapacitor battery membrane of the embodiment of the present invention 2, and Japan's FV4365 and the 700/71 of these two kinds of foreign nickel metal hydride batteries of Britain (Simart). Performance test, as shown in Table 2.

Table 2

From the comparison of the data in Table 2, it can be seen that the diaphragm obtained in Example 2 of the present invention has the best comprehensive performance in all aspects, especially in terms of internal resistance.

The supercapacitor battery separator made by the embodiment of the present invention 2 and Japan's FV4365 and the 700/71 of the United Kingdom (Simart) are used on the automotive nickel-hydrogen battery to perform electrical performance tests. Test, as shown in Table 3.

table 3

From the data in the above table, it can be seen that the diaphragm obtained in Example 2 of the present invention has excellent performance in terms of large current discharge and internal resistance.

The above-mentioned embodiments are only descriptions of the preferred implementation modes of the present invention, and are not intended to limit the scope of the present invention. All such modifications and improvements should fall within the scope of protection defined by the claims of the present invention.

Claims (10)

1. super capacitance cell barrier film is characterized in that: the fiber surface of forming barrier film has sulfonic group and acrylic monomer simultaneously, and the fiber of said composition barrier film is made up of polyolefin sheath core fiber and/or polypropylene fibre.

2. super capacitance cell barrier film according to claim 1 is characterized in that: said sulfonic group is handled through sulfonation and is grafted on the fiber surface of forming barrier film equably, and sulfonation degree is 0.7%～1.0%.

3. super capacitance cell barrier film according to claim 2 is characterized in that: said acrylic monomer is grafted on the fiber surface of the composition barrier film that sulfonation handled equably through physical chemistry emulsification diffusion technique, and monomer-grafted rate is 0.1%～2.0%.

4. according to claim 1 or 3 described super capacitance cell barrier films, it is characterized in that: said acrylic monomer is the mixture of one or more compositions in acrylic monomers, methacrylic acid, methyl acrylate, ethyl acrylate, itaconic acid, unsaturated Sheep's-parsley ketone acid, sulfamic acid, the olefin sulfonic acid.

5. super capacitance cell barrier film according to claim 1 is characterized in that: said polyolefin sheath core fiber part by weight is 80%～100%, and the polypropylene fibre part by weight is 20%～100%.

6. super capacitance cell barrier film according to claim 5 is characterized in that: the fiber number of said polyolefin sheath core fiber is 0.6D～1.0D, and fibre length is 3mm～38mm; The fiber number of polypropylene fibre is 0.6D～0.8D, and fibre length is 5mm～38mm.

7. the preparation method of the described super capacitance cell barrier film of claim 1; It is characterized in that: at first polyolefin sheath core fiber and/or polypropylene fibre are processed lamination type barrier film matrix; Again the barrier film matrix being carried out sulfonation handles; The sulfonation metacneme carries out emulsification diffusion grafting again to be handled, and makes the fiber surface after acrylic monomer is grafted on sulfonation equably.

8. preparation method according to claim 7 is characterized in that: said sulfonation processing procedure is: use the gaseous sulfur trioxide of 90% above concentration, in sulfonation reactor, the barrier film matrix is carried out sulfonation and handle; Temperature in the sulfonation reactor is 60 ℃～100 ℃, sulfur trioxide concentration 90%, 20 meters/minute of sulfonation speed; Handle through oversulfonate; Sulfonic group is grafted on the fiber surface of forming barrier film uniformly, carries out neutralisation treatment through alkali, and wherein alkali lye potassium hydroxide or concentration sodium hydroxide are 1%; And then be washed till neutrality with deionized water, oven dry.

9. preparation method according to claim 7; It is characterized in that: said emulsification diffusion grafting processing procedure is: acrylic monomer, emulsification diffusant and deionized water are made into graft modification liquid, and wherein the weight concentration of acrylic monomer is 10%～30%; The weight concentration of emulsification diffusant is 0.1%～0.6%; The sulfonation metacneme that moves continuously after the processing that is etched under the normal temperature and pressure conditions, is got in the graft modification liquid, and keep successive feeding inert gas in the modification liquid, under 75 ℃ of conditions, carry out abundant graft polymerization and react.

10. the super capacitance cell that contains the described super capacitance cell barrier film of claim 1.