A method for preparing a coaxial skin-core structure fiber battery

Abstract

The present invention relates to the technical field of fiber battery preparation, and discloses a method for preparing a coaxial skin-core fiber battery, comprising the following steps: (1) preparing a base slurry; the raw materials of the base slurry include carbon nanotubes, graphene and carbon black; (2) adding lithium manganate and lithium titanium phosphate to the base slurry to prepare a negative electrode slurry and a positive electrode slurry; (3) preparing a gel electrolyte slurry; the raw materials of the gel electrolyte slurry include chitosan, polyvinyl alcohol and lithium sulfate; (4) filling the positive electrode slurry, the gel electrolyte slurry and the negative electrode slurry into three syringes respectively and preparing a fiber battery by coaxial spinning; the fiber battery is radially divided into a positive electrode layer, an electrolyte layer and a negative electrode layer. The present invention constructs an isotropic three-dimensional carbon structure through carbon nanotubes, graphene and carbon black, and uses coaxial spinning to prepare a fiber battery, so that it has better mechanical strength, flexibility and conductivity.

Description

Technical Field

[0001] The present invention belongs to the technical field of fiber battery preparation, and more specifically relates to a method for preparing a coaxial skin-core structure fiber battery. Background Art

[0002] With the rapid progress of modern science and technology, portable and wearable electronic products are gradually developing towards flexibility, lightness and miniaturization. However, current power sources are generally rigid and too large to meet the requirements of flexible energy storage. Therefore, modern electronic technology requires flexible energy storage power sources with high energy density and flexibility.

[0003] With the urgent demand for high energy density in various wearable electronic products, mobile terminals and electric vehicles, metallic lithium has re-emerged in recent years. Lithium metal anode is considered the "holy grail" of future lithium-based batteries due to its highest theoretical specific capacity (3860mAhg -1 ) and the lowest reduction potential (-3.040V compared to standard hydrogen electrode), it has gradually become a hot spot in current energy storage technology.

[0004] In addition, fiber batteries are of great significance because they can be woven into flexible textiles, which can become compact, wearable and lightweight power solutions. However, most of the various types of fiber batteries currently available have borrowed the preparation methods and processes of planar batteries, mainly including coating conductive materials, active materials and electrolytes on the fiber substrate layer by layer. This method can only produce fiber batteries with low productivity and cannot meet the requirements of practical applications. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a method for preparing a coaxial skin-core structure fiber battery. The fiber battery is prepared by coaxial solution spinning, which not only has good electrochemical properties, mechanical strength and flexibility, can provide energy for other electronic devices, but also has high production efficiency and can meet practical application needs.

[0006] To achieve the above object, the present invention provides a method for preparing a coaxial skin-core structure fiber battery, comprising the following steps:

[0007] (1) preparing a base slurry; the raw materials of the base slurry include carbon nanotubes, graphene and carbon black;

[0008] (2) adding lithium manganese oxide and lithium titanium phosphate to the base slurry to prepare negative electrode slurry and positive electrode slurry;

[0009] (3) Preparation of gel electrolyte slurry; the raw materials of the gel electrolyte slurry include chitosan, polyvinyl alcohol and lithium sulfate;

[0010] (4) The positive electrode slurry, the gel electrolyte slurry and the negative electrode slurry are respectively filled into three syringes and a fiber battery is prepared by coaxial spinning; the fiber battery is radially divided into a positive electrode layer, an electrolyte layer and a negative electrode layer.

[0011] Adding graphene, carbon nanotubes and carbon black to the battery slurry, these three have excellent conductivity at the surface line points, they complement each other's vacancies, build an isotropic three-dimensional carbon structure, greatly enhance the conductivity of the battery slurry, and use it as the main structure of the fiber, it can also make the fiber have strong mechanical properties. Then, add lithium ion active materials of different valences to the base slurry to form positive electrode slurry and negative electrode slurry.

[0012] Acetic acid solution is used as the base to provide an acidic environment for the electrolyte slurry, and chitosan and polyvinyl alcohol are added to make the electrolyte slurry have better viscosity and a certain degree of formability. Finally, in order to make the electrolyte slurry have the corresponding battery ion elements, a certain amount of lithium sulfate is added to enable the positive and negative electrodes to better exchange electrons.

[0013] The fiber battery is prepared by wet spinning, and the spinneret used contains three channels, the inner one is a small channel, the middle one is a medium channel, and the outer one is a large channel. By introducing different proportions of positive electrode slurry, electrolyte slurry, and negative electrode slurry, a coaxial skin-core structure is formed, and then introduced into a coagulation bath to form fibers. By using coaxial spinning, a fiber battery with a three-layer concentric circle structure is prepared, which is the positive electrode, electrolyte, and negative electrode from the inside to the outside. The structure is consistent in all radial directions and has better mechanical strength. At the same time, it increases the effective contact area of ​​the positive and negative electrodes and improves the charge and discharge rate.

[0014] Further preferably, in step (1), the method for preparing the base slurry comprises: dispersing carbon nanotubes, graphene and carbon black in water to obtain a polycarbon aqueous solution; and adding an acrylonitrile aqueous solution to the polycarbon aqueous solution to obtain a base slurry.

[0015] The carbon nanotubes, graphene and carbon black are uniformly dispersed in deionized water by mechanical stirring and ultrasonic dispersion to form a multi-carbon aqueous solution. The acrylonitrile polymer aqueous solution is added to the aqueous solution of carbon nanotubes, graphene and carbon black as the main body, which provides a certain conductivity on the one hand, and on the other hand, the adhesive makes the various components tightly combined, improves the formability of the fiber, and enhances the mechanical strength of the fiber.

[0016] Further preferably, in step (1), the added amounts of the carbon nanotubes, graphene and carbon black are 10-50% of the total mass of the carbon nanotubes, graphene and carbon black respectively; the total mass concentration of the carbon nanotubes, graphene and carbon black in the polycarbon aqueous solution is 15-25%; the mass ratio of the acrylonitrile aqueous solution to the polycarbon aqueous solution is 2-10:100; and the mass concentration of the acrylonitrile aqueous solution is 10-12%.

[0017] Further preferably, in step (2), the mass fraction of lithium manganate in the positive electrode slurry is 10-20%; the mass fraction of lithium titanium phosphate in the negative electrode slurry is 10-20%.

[0018] Further preferably, in step (2), polyvinylidene fluoride emulsion is added to the negative electrode slurry and the positive electrode slurry respectively.

[0019] The addition of vinylidene fluoride emulsion improves the mechanical strength of the slurry, and the addition of carbon nanotubes, graphene and carbon black further improves the conductivity of the slurry and at the same time improves the strength of the fibers after spinning.

[0020] Further preferably, in step (3), the method for preparing the gel electrolyte slurry comprises: adding chitosan to an acetic acid solution, then adding a polyvinyl alcohol solution and mixing, and then adding lithium sulfate to obtain a gel electrolyte slurry.

[0021] Sodium hydroxide is added to the coagulation bath to provide an alkaline environment, and lithium sulfate is added to provide lithium ions.

[0022] Further preferably, the ratio of the chitosan, acetic acid solution, polyvinyl alcohol solution and lithium sulfate is 1-20g:50-500mL:20-50mL:5-10g; the mass concentration of the acetic acid solution is 5-10%; the mass concentration of the polyvinyl alcohol solution is 20-30%.

[0023] Further preferably, in step (4), the mass ratio of the positive electrode slurry, the gel electrolyte slurry and the negative electrode slurry is 2:3:4.

[0024] Further preferably, in step (4), the injection speeds of the syringes loaded with the positive electrode slurry, the gel electrolyte slurry and the negative electrode slurry are 2 mL / min, 3 mL / min and 4 mL / min respectively.

[0025] By varying the extrusion speed and extrusion volume, the thickness of the positive electrode, negative electrode and electrolyte layers in the final spun fiber tends to be consistent, preventing the weakness of individual layers from causing battery failure. At the same time, the increase in the thickness of the negative electrode layer ensures the smooth formation of the fiber in the coagulation bath.

[0026] Further preferably, in step (4), the negative electrode layer of the fiber battery is also coated with a protective layer; the protective layer is formed by taking out the coaxially spun fiber after it is shaped in a coagulation bath and then immersing it in a polyurethane stock solution to form a protective layer.

[0027] Finally, the polyurethane stock solution will solidify on the fiber surface to form a flexible polyurethane protective layer.

[0028] Further preferably, the preparation method of the polyurethane is: adding diisocyanate and dimethyl tin to polyether polyol, and mechanically mixing to prepare a polyurethane stock solution; the mass ratio of the diisocyanate, dimethyl tin and polyether polyol is 0.5-2:0.01-0.1:50-200; the molecular weight of the polyether polyol is 20000-25000.

[0029] Polyurethane is synthesized with polyether polyol and diisocyanate as raw materials, and the reaction is catalyzed by adding dimethyl tin, and the polyether polyol and diisocyanate components are reacted by mechanical stirring. By using high molecular weight polyether polyol as the main raw material to synthesize polyurethane, the prepared polyurethane protective layer has good flexibility.

[0030] Further preferably, in step (4), the coagulation bath for coaxial spinning is an aqueous solution containing sodium hydroxide and lithium sulfate.

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] (1) The three conductive agents - carbon nanotubes, graphene and carbon black - are uniformly mixed through mechanical stirring and ultrasonic dispersion. These three agents construct an isotropic three-dimensional carbon structure, which greatly improves the conductive properties of the slurry.

[0033] (2) The thickness of the positive electrode, negative electrode and electrolyte layers in the final spun fiber are made consistent by different extrusion speeds and extrusion volumes, preventing the failure of the battery due to the weakness of individual layers. At the same time, the increase in the thickness of the negative electrode layer ensures the smooth formation of the fiber in the coagulation bath.

[0034] (3) By using coaxial spinning, a fiber battery with a three-layer concentric circle structure is prepared, which is the positive electrode, electrolyte and negative electrode from the inside to the outside. The structure is consistent in all radial directions, has better mechanical strength, and at the same time increases the effective contact area of ​​the positive and negative electrodes, thereby improving the charge and discharge rate;

[0035] (4) By using high molecular weight polyether polyol as the main raw material to synthesize polyurethane, the prepared polyurethane protective layer has good flexibility;

[0036] (5) Take a fiber battery with a length of 20 cm, and use copper wire to connect the positive and negative electrodes of the battery to the LED light. The LED light can work normally and stably. DETAILED DESCRIPTION

[0037] The technical content and effects of the present invention are further described in detail below in conjunction with the embodiments, but the present invention is not limited thereto.

[0038] Example 1

[0039] A method for preparing a coaxial skin-core structure fiber battery comprises the following preparation steps:

[0040] (1) Preparation of polycarbonate aqueous solution: 10 g of carbon nanotubes were added to 80 ml of deionized water and dispersed uniformly by ultrasonication. Then, 5 g of graphene and 5 g of carbon black were added in sequence and stirred (speed of 800 rpm, dispersion time of 1 h), and further ultrasonicated (power of 100 W, temperature of 20° C., dispersion time of 30 min) to obtain a polycarbonate aqueous solution.

[0041] (2) Preparation of base slurry: 5 g of 10 wt % acrylonitrile aqueous solution was mixed with 100 g of 20 wt % polycarbonate aqueous solution, and stirred (rotation speed of 800 rpm, dispersion time of 2 h) to obtain a base slurry.

[0042] (3) Preparation of electrode slurry: 50 g of lithium manganate was added to 100 g of the base slurry. After the lithium manganate was completely dissolved, 100 g of a 20 wt % polycarbonate aqueous solution and 100 g of a polyvinylidene fluoride emulsion were added and stirred (mechanical stirring speed was 800 rpm, dispersion time was 2 h) to obtain a negative electrode slurry.

[0043] 50 g of lithium titanium phosphate was added to 100 g of the base slurry, and then 100 g of a 20 wt % polycarbonate aqueous solution and 100 g of a polyvinylidene fluoride emulsion were added, and stirred (mechanical stirring speed was 800 rpm, dispersion time was 2 h) to obtain a positive electrode slurry.

[0044] (4) Preparation of gel electrolyte slurry: 10 g of chitosan was added to 100 mL of 5 wt % acetic acid solution and stirred; then 20 mL of 10 wt % polyvinyl alcohol solution was added and stirred (speed was 800 rpm, dispersion time was 2 h), and finally 5 g of lithium sulfate was added to obtain a gel electrolyte slurry.

[0045] (5) Preparation of polyurethane stock solution: 100 g of polyether polyol with a molecular weight of 20,000 to 25,000 was added to a beaker, and 1.2 g of diisocyanate and 0.05 g of dimethyl tin were added, and mechanically mixed (rotation speed of 200 rpm, dispersion time of 10 min) to obtain a polyurethane stock solution.

[0046] (6) Preparation of fiber battery: The prepared positive electrode slurry, gel electrolyte slurry and negative electrode slurry are filled into three syringes respectively, the masses of the positive electrode slurry, gel electrolyte slurry and negative electrode slurry are 40g, 60g and 80g respectively, and are extruded into the spinneret holes by injection pumps, and the injection speeds of the injection pumps connected to the positive electrode slurry, gel electrolyte slurry and negative electrode slurry are 2mL / min, 3mL / min and 4mL / min respectively. The slurry is extruded into a coagulation bath (aqueous solution of 1mol / L sodium hydroxide and 1mol / L lithium sulfate) to form fibers, which are radially divided into a positive electrode layer, an electrolyte layer and a negative electrode layer. After the fibers are shaped, they are passed into a polyurethane stock solution to form a protective layer to obtain a fiber battery.

[0047] Example 2

[0048] A method for preparing a coaxial skin-core structure fiber battery comprises the following preparation steps:

[0049] (1) Preparation of polycarbonate aqueous solution: 10 g of carbon nanotubes were added to 80 ml of deionized water and dispersed uniformly by ultrasonication. Then, 8 g of graphene and 2 g of carbon black were added in sequence and stirred (speed of 800 rpm, dispersion time of 1 h), and further ultrasonicated (power of 100 W, temperature of 20° C., dispersion time of 30 min) to obtain polycarbonate aqueous solution.

[0050] (2) Preparation of base slurry: 10 g of 10 wt % acrylonitrile aqueous solution was mixed with 100 g of 20 wt % polycarbonate aqueous solution, and stirred (rotation speed of 800 rpm, dispersion time of 2 h) to obtain a base slurry.

[0051] (3) Preparation of electrode slurry: 50 g of lithium manganate was added to 100 g of the base slurry. When the lithium manganate was completely dissolved, 50 g of a 20 wt% polycarbonate aqueous solution and 150 g of a polyvinylidene fluoride emulsion were added and stirred (mechanical stirring speed was 800 rpm, dispersion time was 2 h) to obtain a negative electrode slurry.

[0052] 50 g of lithium titanium phosphate was added to 100 g of the base slurry, and then 50 g of a 20 wt % polycarbonate aqueous solution and 150 g of a polyvinylidene fluoride emulsion were added, and stirred (mechanical stirring speed was 800 rpm, dispersion time was 2 h) to obtain a positive electrode slurry.

[0053] (4) Preparation of gel electrolyte slurry: 10 g of chitosan was added to 100 mL of 5 wt % acetic acid solution and stirred; then 40 mL of 10 wt % polyvinyl alcohol solution was added and stirred (speed was 800 rpm, dispersion time was 2 h), and finally 5 g of lithium sulfate was added to obtain a gel electrolyte slurry.

[0054] (5) Preparation of polyurethane stock solution: 100 g of polyether polyol with a molecular weight of 20,000 to 25,000 was added to a beaker, and 1.2 g of diisocyanate and 0.05 g of dimethyl tin were added, and mechanically mixed (rotation speed of 200 rpm, dispersion time of 10 min) to obtain a polyurethane stock solution.

[0055] (6) Preparation of fiber battery: The prepared positive electrode slurry, gel electrolyte slurry and negative electrode slurry are filled into three syringes respectively, the masses of the positive electrode slurry, gel electrolyte slurry and negative electrode slurry are 40g, 60g and 80g respectively, and are extruded into the spinneret holes by injection pumps, and the injection speeds of the injection pumps connected to the positive electrode slurry, gel electrolyte slurry and negative electrode slurry are 2mL / min, 3mL / min and 4mL / min respectively. The slurry is extruded into a coagulation bath (aqueous solution of 1mol / L sodium hydroxide and 1mol / L lithium sulfate) to form fibers, which are radially divided into a positive electrode layer, an electrolyte layer and a negative electrode layer. After the fibers are shaped, they are passed into a polyurethane stock solution to form a protective layer to obtain a fiber battery.

[0056] Example 3

[0057] A method for preparing a coaxial skin-core structure fiber battery comprises the following preparation steps:

[0058] (1) Preparation of polycarbonate aqueous solution: 10 g of carbon nanotubes were added to 80 ml of deionized water and dispersed uniformly by ultrasonication. Then, 5 g of graphene and 5 g of carbon black were added in sequence and stirred (speed of 800 rpm, dispersion time of 1 h), and further ultrasonicated (power of 100 W, temperature of 20° C., dispersion time of 30 min) to obtain a polycarbonate aqueous solution.

[0059] (2) Preparation of base slurry: 2 g of 10 wt % acrylonitrile aqueous solution was mixed with 100 g of 20 wt % polycarbonate aqueous solution, and stirred (rotation speed of 800 rpm, dispersion time of 2 h) to obtain a base slurry.

[0060] (3) Preparation of electrode slurry: 50 g of lithium manganate was added to 100 g of the base slurry. After the lithium manganate was completely dissolved, 100 g of a 20 wt % polycarbonate aqueous solution and 50 g of a polyvinylidene fluoride emulsion were added and stirred (mechanical stirring speed was 800 rpm, dispersion time was 2 h) to obtain a negative electrode slurry.

[0061] 50 g of lithium titanium phosphate was added to 100 g of the base slurry, and then 100 g of a 20 wt % polycarbonate aqueous solution and 50 g of a polyvinylidene fluoride emulsion were added, and stirred (mechanical stirring speed was 800 rpm, dispersion time was 2 h) to obtain a positive electrode slurry.

[0062] (4) Preparation of gel electrolyte slurry: 15 g of chitosan was added to 150 mL of 5 wt % acetic acid solution and stirred; then 20 mL of 10 wt % polyvinyl alcohol solution was added and stirred (speed was 800 rpm, dispersion time was 2 h), and finally 5 g of lithium sulfate was added to obtain a gel electrolyte slurry.

[0063] (5) Preparation of polyurethane stock solution: 100 g of polyether polyol with a molecular weight of 20,000 to 25,000 was added to a beaker, and 1.2 g of diisocyanate and 0.05 g of dimethyl tin were added, and mechanically mixed (rotation speed of 200 rpm, dispersion time of 10 min) to obtain a polyurethane stock solution.

[0064] (6) Preparation of fiber battery: The prepared positive electrode slurry, gel electrolyte slurry and negative electrode slurry are filled into three syringes respectively, the masses of the positive electrode slurry, gel electrolyte slurry and negative electrode slurry are 40g, 60g and 80g respectively, and are extruded into the spinneret holes by injection pumps, and the injection speeds of the injection pumps connected to the positive electrode slurry, gel electrolyte slurry and negative electrode slurry are 2mL / min, 3mL / min and 4mL / min respectively. The slurry is extruded into a coagulation bath (aqueous solution of 1mol / L sodium hydroxide and 1mol / L lithium sulfate) to form fibers, which are radially divided into a positive electrode layer, an electrolyte layer and a negative electrode layer. After the fibers are shaped, they are passed into a polyurethane stock solution to form a protective layer to obtain a fiber battery.

[0065] Table 1

[0066] Elongation at break (%) Breaking strength(MPa) Elastic modulus (MPa) Example 1 30 50 1.2 Example 2 38 63 1.8 Example 3 19 41 1.1

[0067] The fiber battery prepared in Examples 1-3 was cut into 20 cm lengths, and the positive and negative electrodes of the battery were connected to the LED lamp with copper wires, and the LED lamp could work normally and stably. As shown in Table 1, the fiber battery in the present invention also has good mechanical strength and flexibility.

[0068] The above embodiments of the present invention are merely examples for illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes and modifications can be made based on the above description. It is impossible to list all the embodiments here. Any obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for preparing a coaxial skin-core fiber battery, It is characterized in that The steps include: (1) Preparation of a base slurry; the raw materials of the base slurry include carbon nanotubes, graphene and carbon black; the carbon nanotubes, graphene and carbon black are dispersed in water to obtain a multi-carbon aqueous solution; an acrylonitrile aqueous solution is added to the multi-carbon aqueous solution to obtain a base slurry; the amount of the carbon nanotubes, graphene and carbon black added is 10-50% of the total mass of the carbon nanotubes, graphene and carbon black respectively; the total mass concentration of the carbon nanotubes, graphene and carbon black in the multi-carbon aqueous solution is 15-25%; the mass ratio of the acrylonitrile aqueous solution to the multi-carbon aqueous solution is 2-10:100; the mass concentration of the acrylonitrile aqueous solution is 10-12%; (2) adding lithium manganese oxide and lithium titanium phosphate to the base slurry to prepare negative electrode slurry and positive electrode slurry respectively; (3) Preparation of gel electrolyte slurry; the raw materials of the gel electrolyte slurry include chitosan, polyvinyl alcohol and lithium sulfate; chitosan is added to acetic acid solution, polyvinyl alcohol solution is added and mixed, and lithium sulfate is added to obtain gel electrolyte slurry; the ratio of the amount of chitosan, acetic acid solution, polyvinyl alcohol solution and lithium sulfate is 1-20g:50-500mL:20-50mL:5-10g; the mass concentration of the acetic acid solution is 5-10%; the mass concentration of the polyvinyl alcohol solution is 10-20%; (4) The positive electrode slurry, gel electrolyte slurry and negative electrode slurry are filled into three syringes respectively and prepared by coaxial spinning to form a fiber battery with a three-layer concentric circle structure, which includes the positive electrode, electrolyte and negative electrode from the inside to the outside, and the structure is consistent in all radial directions.

2. The method for preparing the coaxial skin-core fiber battery according to claim 1, It is characterized in that In step (2), the mass fraction of lithium manganese oxide in the positive electrode slurry is 10-20%; the mass fraction of lithium titanium phosphate in the negative electrode slurry is 10-20%.

3. The method for preparing the coaxial skin-core structure fiber battery according to claim 1, It is characterized in that In step (4), the mass ratio of the positive electrode slurry, the gel electrolyte slurry and the negative electrode slurry is 2:3:

4.

4. The method for preparing the coaxial skin-core fiber battery according to claim 1, It is characterized in that In step (4), the injection speeds of the syringes loaded with the positive electrode slurry, the gel electrolyte slurry, and the negative electrode slurry are 2 mL / min, 3 mL / min, and 4 mL / min, respectively.

5. The method for preparing the coaxial skin-core fiber battery according to claim 1, It is characterized in that In step (4), the negative electrode layer of the fiber battery is also coated with a protective layer; the protective layer is formed by taking out the coaxially spun fiber after it is shaped in a coagulation bath and then immersing it in polyurethane to form a protective layer.

6. A method for preparing a coaxial skin-core fiber battery as claimed in claim 1 or 5, It is characterized in that In step (4), the coagulation bath for coaxial spinning is an aqueous solution containing sodium hydroxide and lithium sulfate.