CN115966412A - Non-woven fabric composite diaphragm for supercapacitor and preparation method and application thereof - Google Patents

Abstract

The invention relates to the field of composite diaphragms, in particular to a non-woven composite diaphragm for supercapacitors and a preparation method and application thereof. The non-woven composite diaphragm structure at least includes: a base film, a ceramic particle layer and a bonding layer; wherein, the pore diameter of the base film is 0.1-10 μm; the thickness of the base film is 10-40 μm; The porosity is 50-80%. The invention provides a non-woven composite diaphragm for supercapacitors, which has excellent air permeability and acupuncture strength, and can also have good bonding performance with capacitors and other pole pieces, and is suitable for promotion in the field of battery composite diaphragms, and has broad application potential. Prospects.

Description

A kind of non-woven composite diaphragm for supercapacitor and its preparation method and application

technical field

The invention relates to the field of composite diaphragms, in particular to a non-woven composite diaphragm for supercapacitors and a preparation method and application thereof.

Background technique

With the rapid development of new energy vehicles, rail transit, new energy ships, and smart grids, there is an urgent need for energy storage devices with high energy density, high power density, and good cycle life. Among them, lithium-ion batteries and supercapacitors play an extremely important role in the field of energy storage due to their advantages in energy density and power density, respectively. With the further expansion of the application market demand, there is an urgent need for higher-energy fast-charging energy storage devices. Therefore, energy storage systems with higher volumetric energy will be a major demand in the future market.

From the perspective of the system, a new direction is also proposed for the size requirements of the monomer. However, for the system, the proportion of small-sized single shells, connectors and other accessories will increase, so the proportion of active materials will decrease, which is not conducive to the volume specific energy and mass specific energy of the system. If the size of the thickened monomer is further increased, the compactness of the system can be further improved. However, the increase in the size of the monomer will also bring many problems. How to ensure the dynamic and thermodynamic stability of the pole piece/diaphragm/electrolyte interface, and reduce the damage and displacement of the diaphragm and pole piece during the cell transfer process The problem needs to be solved urgently.

Prior art CN103199209A and CN112259911A also disclose the method for preparing ceramic/non-woven composite diaphragm, but these methods only solve the problem of large aperture of non-woven diaphragm, large self-discharge and high short-circuit rate, and do not improve diaphragm/pole piece The interface and adhesion force, and no solution has been proposed for the displacement of large-scale cell diaphragm and pole piece.

Therefore, the application provides a non-woven composite separator for supercapacitors that can solve the above technical problems.

Contents of the invention

In order to solve the above problems, the first aspect of the present invention provides a non-woven composite diaphragm for supercapacitors, the non-woven composite diaphragm structure at least includes: a base film, a ceramic particle layer and a bonding layer; wherein the base The pore diameter of the membrane is 0.1-10 μm; the thickness of the base membrane is 10-40 μm; the porosity of the base membrane is 50-80%.

As a preferred solution, the pore diameter of the base film is 1-5 μm; the thickness of the base film is 20-30 μm; the porosity of the base film is 60-70%.

As a preferred solution, the base film is a non-woven base film; the material of the non-woven base film is cellulose, polyethylene terephthalate, aramid fiber, polyimide, spandex , carboxymethyl cellulose, hydroxymethyl cellulose, polyacrylonitrile, polybutylene terephthalate, polyamide at least one.

As a preferred solution, the material of the non-woven fabric base film is any one of cellulose, polyethylene terephthalate, aramid, and polyimide.

As a preferred solution, the material of the non-woven fabric base film is polyethylene terephthalate.

As a preferred solution, the components in the ceramic particle layer at least include ceramic particles, and the ceramic particles are aluminum oxide, titanium dioxide, silicon dioxide, boehmite, zirconium dioxide, zinc oxide, tin dioxide, magnesium oxide 1. At least one of calcium oxide; the average particle size of the ceramic particles is 0.1-1 μm.

As a preferred solution, the ceramic particles are alumina and/or silicon dioxide; the average particle size of the ceramic particles is 0.3-0.6 μm.

As a preferred solution, the composition of the bonding layer at least includes polymer particles, and the polymer particles are polyvinylidene fluoride-hexafluoropropylene copolymer, polymethyl methacrylate, AFL, polyethylene At least one of alcohols; the average particle diameter of the polymer particles is 1-10 μm.

As a preferred solution, the polymer particles are polyvinylidene fluoride-hexafluoropropylene copolymer particles and/or polymethyl methacrylate particles; the average particle diameter of the polymer particles is 2-6 μm.

As a preferred solution, the composition of the ceramic particle layer includes, by mass percentage: 20-40% ceramic particles, 0-5% dispersant, 0-5% thickener, 0-5% wetting agent , 0.1 ~ 4% binder, deionized water to make up the balance.

As a preferred solution, the mass ratio of the ceramic particles to the binder is 25-35:2-5.

As a preferred solution, the mass ratio of the ceramic particles to the binder is 32:2.5.

As a preferred solution, the composition of the adhesive layer includes, in mass percent: 5-20% polymer particles, 0-5% dispersant, 0-5% thickener, 0-5% wetting agent, 0.2-2% binder, and deionized water to make up the balance.

As a preferred solution, the mass ratio of the polymer particles to the binder is 6-12:1-1.5.

As a preferred solution, the mass ratio of the polymer particles to the binder is 8.5:1.1.

As a preferred solution, the binder is polyacrylate; the moisture content of the polyacrylate is 0.05-0.1%.

As a preferred solution, the dispersant is at least one of polyvinylpyrrolidone, polyethylene glycol, polyethylene oxide and polyacrylate.

As a preferred solution, the dispersant is polyvinylpyrrolidone.

As a preferred scheme, the thickener is sodium carboxymethyl cellulose, methyl cellulose, hydroxypropyl methyl cellulose, polyacrylamide, polyvinylpyrrolidone, polyvinyl alcohol, polyethylene oxide, poly At least one of acrylic acid and polyacrylate.

As a preferred solution, the wetting agent is at least one of polysiloxane quaternary ammonium salt, polyoxyethylene ether, and thiol acetal.

As a preferred solution, the wetting agent is polysiloxane quaternary ammonium salt.

As a preferred solution, the thickness of the ceramic particle layer is 1-3 μm; the thickness of the bonding layer is 1-3 μm.

The second aspect of the present invention provides a method for preparing the above-mentioned non-woven composite separator for supercapacitors, the steps include the following steps: (1) mixing and stirring the required components of the ceramic particle layer to obtain the first slurry; (2) mixing The first slurry is coated on both sides of the base film to obtain a ceramic/base film composite diaphragm; (3) the ceramic/base film composite diaphragm is cold-pressed at room temperature at 25°C for 10 seconds to 5 minutes at a pressure of 1 to 5 MPa; (4) the adhesive Mix and stir the required components of the layer to obtain the second slurry; (5) coat the second slurry on both sides of the ceramic/base membrane composite diaphragm to obtain.

The third aspect of the present invention provides an application of the above-mentioned non-woven composite diaphragm for supercapacitors, including the application of the non-woven composite diaphragm in supercapacitors and fast-charging electric energy storage periods.

Beneficial effect:

1. In this application, by selecting polymer bonding particles and ceramic particles with a specific particle size to coat the non-woven fabric, the ceramic particles can be effectively filled into the gaps of the non-woven fabric base film during the preparation process, and the In addition to the problems of large self-discharge and high short-circuit rate of the non-woven base film, it can also cooperate with the further coated large-size adhesive polymer particles to realize the adhesion of the non-woven composite separator and the pole piece by hot pressing. The interface between the diaphragm and the pole piece is improved, the adhesion between the diaphragm and the pole piece is improved, and the displacement of the diaphragm and the pole piece of the large-sized cell is reduced, thereby improving the capacity, life and safety of the high-power energy storage device.

2. A composite diaphragm provided in this application, through the process sequence of first coating ceramic particles and then coating cohesive polymer particles, in addition to effectively reducing the amount of polymer particles, improving the surface of the non-woven diaphragm At the same time of adhesion, the non-woven composite separator also has good liquid absorption capacity, thermal stability, puncture strength and low air permeability, making it more suitable for high-power fast-charging energy storage devices and supercapacitors. Excellent applicability, interface consistency and service life.

Description of drawings

Fig. 1 is a schematic structural diagram of the composite diaphragm provided by the present application.

In the figure: 1-base film, 2-ceramic particle layer, 3-bonding layer.

Detailed ways

Example 1

Embodiment 1 The first aspect provides a non-woven composite membrane for supercapacitors, the non-woven composite membrane structure at least includes: a base film, a ceramic particle layer and a bonding layer; wherein the pore diameter of the base film The thickness of the base film is 2.5 μm; the thickness of the base film is 25 μm; the porosity of the base film is 65%.

The base film is a non-woven base film made of polyethylene terephthalate.

The composition of the ceramic particle layer includes, by mass percentage: 32% ceramic particles, 0.2% dispersant, 0.2% thickener, 0.1% wetting agent, 2.5% binder, and deionized water to make up the balance.

The composition of the bonding layer includes, by mass percentage: 8.5% polymer particles, 0.15% dispersant, 0.15% thickener, 0.1% wetting agent, 1.1% binder, and deionized water to make up the balance.

The ceramic particles are alumina particles with an average particle size of 0.5 μm; the polymer particles are polyvinylidene fluoride-hexafluoropropylene copolymer particles with a diameter of 2 μm.

The dispersant is polyvinylpyrrolidone; the thickener is sodium carboxymethyl cellulose; the wetting agent is polysiloxane quaternary ammonium salt. The binder is polyacrylate, and the moisture content is less than 0.1%.

The thickness of the ceramic particle layer is 2.5 μm; the thickness of the bonding layer is 1.5 μm.

The second aspect of embodiment 1 provides a kind of preparation method of non-woven composite separator for supercapacitor, and the steps include the following steps: (1) mixing and stirring the required components of the ceramic particle layer to obtain the first slurry; (2) mixing The first slurry is coated on both sides of the base film to obtain a ceramic/base film composite diaphragm; (3) the ceramic/base film composite diaphragm is cold-pressed at room temperature 25°C for 2min at a pressure of 4.5MPa; (4) the bonding layer is The components need to be mixed and stirred to obtain the second slurry; (5) Coating the second slurry on both sides of the ceramic/base membrane composite diaphragm, to obtain.

Example 2

The specific implementation of this example is consistent with Example 1, the difference is: 26.5% ceramic particles, 0.25% dispersant, 0.25% thickener, 0.1% wetting agent, 2.9% binder, deionized water to supplement the balance ; Among them, the ceramic particles are silicon dioxide with an average particle size of 0.3 μm.

The composition of the bonding layer includes, in mass percentage: 10% polymer particles, 0.15% dispersant, 0.15% thickener, 0.1% wetting agent, 1.1% binder, and deionized water to supplement the balance; The particles are polymethyl methacrylate particles with an average particle size of 3 μm.

Example 3

The specific implementation of this example is consistent with Example 1, the difference is: 35% ceramic particles, 0.25% dispersant, 0.2% thickener, 0.15% wetting agent, 3.4% binder, deionized water to supplement the balance ; Among them, the ceramic particles are silicon dioxide with an average particle size of 0.6 μm.

The composition of the bonding layer includes, by mass percentage: 6% polymer particles, 0.15% dispersant, 0.15% thickener, 0.1% wetting agent, 1.1% binder, and deionized water to supplement the balance; The particles are polymethyl methacrylate particles with an average particle size of 6 μm

Comparative example 1

The specific implementation of this comparative example is the same as that of Example 1, except that step (3) is not included in the preparation process of the composite diaphragm.

Comparative example 2

The specific implementation of this comparative example is the same as that of Example 1, except that the polymer particles are 0.2 μm polyvinylidene fluoride-hexafluoropropylene copolymer particles.

Comparative example 3

The specific implementation of this comparative example is the same as that of Example 1, except that the ceramic particles are 5 μm alumina particles.

Comparative example 4

The specific implementation of this comparative example is the same as that of Example 1, except that the polymer particles are 0.2 μm polyvinylidene fluoride-hexafluoropropylene copolymer particles, and the ceramic particles are 5 μm alumina particles.

performance evaluation

Air permeability: Tested according to the GB/T36363-2018 test method, 5 samples were tested in each embodiment, and the average value of the measured values was recorded in Table 1.

Acupuncture strength: Tested according to the GB/T36363-2018 test method, 5 samples were tested in each embodiment, and the average value of the measured values was recorded in Table 1.

The bond strength between the separator and the negative electrode sheet: the test was carried out according to the GB/T2792-2014 test method, and 5 samples were tested for each example and comparative example, and the average value of the measured values was recorded in Table 1.

Table 1

It can be known from Examples 1 to 3, Comparative Examples 1 to 4 and Table 1 that a nonwoven composite separator for a supercapacitor provided by the present invention has excellent air permeability and acupuncture strength, and can also be used with capacitors, etc. The pole piece has good bonding performance, is suitable for promotion in the field of battery composite separators, and has broad development prospects.

Claims (10)

1. A non-woven composite diaphragm for supercapacitor, characterized in that: the non-woven composite diaphragm structure at least includes: base film, ceramic particle layer and bonding layer; wherein, the pore diameter of the base film is 0.1 ~10 μm; the thickness of the base film is 10-40 μm; the porosity of the base film is 50-80%. 2. The non-woven composite diaphragm for supercapacitor according to claim 1, wherein: the base film is a non-woven base film; the material of the non-woven base film is cellulose, polyethylene terephthalate At least one of ethylene glycol formate, aramid, polyimide, spandex, carboxymethyl cellulose, hydroxymethyl cellulose, polyacrylonitrile, polybutylene terephthalate, and polyamide. 3. The non-woven composite membrane for supercapacitor according to claim 2, characterized in that: the composition at least includes ceramic particles in the ceramic particle layer, and the ceramic particles are aluminum oxide, titanium dioxide, silicon dioxide, Boehm At least one of stone, zirconium dioxide, zinc oxide, tin dioxide, magnesium oxide, and calcium oxide; the average particle size of the ceramic particles is 0.1-1 μm. 4. The non-woven composite diaphragm for supercapacitor according to claim 3, characterized in that: the composition of the bonding layer at least includes polymer particles, and the polymer particles are polyvinylidene fluoride-hexafluoro At least one of propylene copolymer, polymethyl methacrylate, AFL, and polyvinyl alcohol; the average particle diameter of the polymer particles is 1-10 μm. 5. The non-woven composite diaphragm for supercapacitor according to claim 4, characterized in that: the composition of the ceramic particle layer comprises, in mass percentage: 20-40% ceramic particles, 0-5% dispersant , 0-5% thickener, 0-5% wetting agent, 0.1-4% binder, deionized water to make up the balance. 6. The non-woven composite diaphragm for supercapacitor according to claim 5, characterized in that: the composition of the bonding layer comprises, in mass percentage: 5-20% polymer particles, 0-5% dispersed Agent, 0-5% thickener, 0-5% wetting agent, 0.2-2% binder, and deionized water to make up the balance. 7 . The non-woven fabric composite diaphragm for supercapacitor according to claim 6 , characterized in that: the binder is polyacrylate; the moisture content of the polyacrylate is 0.05-0.1%. 8. The non-woven composite diaphragm for supercapacitor according to claim 7, characterized in that: the dispersant is at least one of polyvinylpyrrolidone, polyethylene glycol, polyethylene oxide, and polyacrylate. 9. A method for preparing a non-woven composite diaphragm for supercapacitor according to any one of claims 1 to 8, characterized in that: the step comprises the following steps: (1) mixing and stirring the required components of the ceramic particle layer Obtain the first slurry; (2) coat the first slurry on both sides of the base film to obtain a ceramic/base film composite diaphragm; (3) cool the ceramic/base film composite diaphragm with a pressure of 1 to 5 MPa at room temperature at 25°C Press for 10 seconds to 5 minutes; (4) Mix and stir the ingredients required for the bonding layer to obtain the second slurry; (5) Coat the second slurry on both sides of the ceramic/base membrane composite diaphragm to obtain the product. 10. An application of the non-woven composite diaphragm for supercapacitor according to any one of claims 1 to 8, characterized in that: the non-woven composite diaphragm is included in the period of supercapacitor and fast charging type electric energy storage Applications.

Images