KR102564499B1 - Carbon fiber composite nonwoven fabric, electrode current collector comprising same, and method of manufaturing same - Google Patents

Abstract

A carbon fiber composite nonwoven fabric, an electrode current collector including the same, and a manufacturing method thereof are disclosed. The carbon fiber composite nonwoven fabric is carbon fiber; and a binder including micro short fibers and nano long fibers, wherein the micro short fibers include a hydrophilic polymer, and the nano long fibers include cellulose nanofibers (CNF) and have low sheet resistance and excellent It has the effect of having tensile strength and has excellent hydrophilicity, so it can be used as an electrode current collector for aqueous zinc batteries.

Description

Carbon fiber composite non-woven fabric, electrode current collector including the same, and manufacturing method thereof

The present invention relates to a carbon fiber composite nonwoven fabric, an electrode current collector including the same, and a method for manufacturing the same, wherein micro short fibers and nano long fibers are cross-linked and combined to form a strong bond, resulting in a three-dimensional three-dimensional structure having improved mechanical properties and electrical conductivity. It relates to a carbon fiber composite nonwoven fabric having a network structure, an electrode current collector including the same, and a manufacturing method thereof.

Currently, the most widely used secondary battery technology is a lithium ion-based battery (Li-ion battery), which is applied to various portable electronic devices and electric vehicles due to its high driving voltage and output stability. With the recent expansion of the wearable market, demand for high-capacity, high-stability, and eco-friendly batteries has increased. However, lithium ion batteries use an organic electrolyte, which is easily exposed to the risk of fire due to high flammability when an electrical short circuit occurs. As an alternative to this, water-based secondary batteries are attracting attention, and zinc (Zn) metal, in particular, is considered a very suitable material as an anode material for water-based batteries due to its very high theoretical capacity (820 mAh/g), eco-friendliness, and low price. .

Generally, metal foil is used as a current collector of a secondary battery, but it is not suitable as a current collector of a flexible battery because it has a limited capacity, is heavy, and has a characteristic of being crumpled when implementing a battery. In particular, although a zinc thin film is used as the anode of an aqueous zinc battery, repeated plating and peeling of zinc ions occur during charging and discharging of the battery, and at this time, zinc forms dendrites, which leads to low Coulombic efficiency. and low lifespan, there is a problem of causing an electrical short circuit, and controlling it is an important task for the commercialization of an aqueous zinc battery. In order to control the formation of these dendrites, various types of additives are added to the electrolyte or zinc metal in the form of an alloy is used. However, these additives have a problem of causing another side reaction in the battery or shortening the life and capacity of the battery.

Therefore, research on an electrode current collector for an aqueous zinc battery capable of controlling the formation of zinc dendrites and having electrochemical stability and excellent lifespan characteristics is required.

An object of the present invention is to solve the above problems, and to provide a carbon fiber nonwoven fabric that can be used as an electrode current collector and a manufacturing method thereof by having low sheet resistance and excellent tensile strength.

In addition, an electrode current collector for an aqueous zinc battery having electrochemical stability and excellent lifespan characteristics and a manufacturing method thereof are provided.

According to one aspect of the present invention, carbon fiber; and a binder including micro short fibers and nano long fibers, wherein the micro short fibers include a hydrophilic polymer, and the nano long fibers include cellulose nanofibers (CNF). A composite nonwoven fabric is provided.

In addition, the nano-long fiber is positioned on the carbon fiber and the carbon fiber to crosslink the carbon fiber and the carbon fiber, or the nano-long fiber is positioned on the micro short fiber and the micro short fiber to cross-link the micro short fiber. and micro short fibers can be cross-linked, or the nano-long fibers are positioned on the carbon fibers and micro short fibers to cross-link the carbon fibers and micro short fibers with each other to form a carbon fiber composite nonwoven fabric having a three-dimensional network structure. there is.

In addition, the nano-long fibers may form a film-like fiber bundle.

In addition, the hydrophilic polymer is polyvinyl alcohol (PVA), hydrophilic polyurethane, polyethylene oxide (PEO), polypropylene oxide (PPO), polydopamine, poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT) : PSS) and combinations thereof.

In addition, the carbon fiber composite nonwoven fabric may include 10 to 50 parts by weight of the binder based on 100 parts by weight of the carbon fibers.

In addition, the weight (wt) ratio (MF:NF) of the micro short fibers (MF) and the nano long fibers (NF) may be 5:5 to 9:1.

In addition, the basis weight of the carbon fiber composite nonwoven fabric may be 50 to 300 gsm.

In addition, the length of the micro short fibers may be 0.5 to 3 mm, and the width of the micro short fibers may be 5 to 30 μm.

According to another aspect of the present invention, an electrode current collector including the carbon fiber composite nonwoven fabric is provided.

In addition, the electrode current collector is the carbon fiber composite non-woven fabric; and a metal coated on the carbon fiber composite nonwoven fabric.

In addition, the metal is zinc (Zn), gold (Au), silver (Ag), aluminum (Al), beryllium (Be), bismuth (Bi), cobalt (Co), copper (Cu), chromium (Cr), Cadmium (Cd), Iron (Fe), Gallium (Ga), Hafnium (Hf), Indium (In), Iridium (Ir), Manganese (Mn), Molybdenum (Mo), Magnesium (Mg), Nickel (Ni) ), niobium (Nb), lead (Pb), palladium (Pd), platinum (Pt), rhodium (Rh), rhenium (Re), rubidium (Ru), antimony (Sb), tin (Sn), tantalum It may include at least one selected from the group consisting of rum (Ta), tellurium (Te), titanium (Ti), vanadium (V), tungsten (W), and zirconium (Zr).

According to another aspect of the present invention, (a) preparing a mixed solution containing carbon fibers; (b) preparing a binder solution containing micro short fibers and nano long fibers; and (c) preparing the carbon fiber composite nonwoven fabric according to claim 1 by mixing the mixed solution and the binder solution.

In addition, by mixing in step (c), the nano-long fibers cross-link at least one selected from the group consisting of the carbon fibers and the micro-short fibers to form a three-dimensional network structure.

In addition, the nano-long fiber may be in the form of a fiber bundle.

In addition, the weight (wt) ratio (MF:NF) of the micro short fibers (MF) and the nano long fibers (NF) in the binder solution may be 5:5 to 9:1.

The carbon fiber composite nonwoven fabric of the present invention has the effect of having low sheet resistance and excellent tensile strength, and can be used as an electrode current collector for an aqueous zinc battery due to its excellent hydrophilicity.

In addition, the carbon fiber composite nonwoven fabric of the present invention can be manufactured in an environmentally friendly manner using a wet method, and has advantages of a simple processing method and a short processing time compared to conventional carbon-based two-dimensional structures.

In addition, the electrode current collector of the present invention has excellent electrochemical stability and lifespan characteristics by including the carbon fiber composite nonwoven fabric.

In addition, the electrode current collector of the present invention effectively controls the dendrites of zinc through the three-dimensional network structure of the carbon fiber composite nonwoven fabric, thereby providing an aqueous zinc battery with high coulombic efficiency and improved lifespan characteristics when the electrode current collector is used. can do.

Since these drawings are for reference in explaining exemplary embodiments of the present invention, the technical spirit of the present invention should not be construed as being limited to the accompanying drawings.
1 is a schematic diagram showing a carbon fiber composite nonwoven fabric and a manufacturing method thereof according to one embodiment of the present invention.
Figure 2 is a schematic diagram showing a method for manufacturing a carbon fiber composite nonwoven fabric according to one embodiment of the present invention.
3 shows actual images and SEM images of carbon fiber nonwoven fabrics for each CNF content of Examples 1 to 5 and Comparative Example 1.
4 shows an actual image of the carbon fiber composite nonwoven fabric prepared according to Example 5.
Figure 5a shows a SEM image (scare bar = 500 μm) of the surface of the carbon fiber composite nonwoven fabric prepared according to Example 5.
Figure 5b shows a SEM image (scare bar = 50 μm) of the surface of the carbon fiber composite nonwoven fabric prepared according to Example 5.
6 shows contact angle analysis data of the carbon fiber composite nonwoven fabric of Example 1.
Figure 7a shows resistance analysis data for each CNF content of Examples 1 to 5 and Comparative Example 1.
7B shows resistance analysis data for each basis weight of Example 1 and Examples 6 to 10.
7C shows resistance analysis data for each binder content in Example 1 and Examples 11 to 14.
Figure 8a shows the tensile strength analysis data for each CNF content of Examples 1 to 5 and Comparative Example 1.
Figure 8b shows the tensile strength analysis data for each basis weight of Example 1 and Examples 6 to 10.
Figure 8c shows the tensile strength analysis data for each binder content of Example 1 and Examples 11 to 14.
9A shows a digital photograph of an electrode current collector manufactured according to Example 15.
FIG. 9B shows SEM pictures at different magnifications of the electrode current collector manufactured according to Example 15. FIG.
10 shows energy dispersive X-ray spectroscopy (EDS) mapping and spectrum results of an electrode current collector prepared according to Example 15.
11 is a graph of charging and discharging overvoltage according to rate change of Device Example 1 (zinc-carbon fiber composite nonwoven fabric) and Device Comparative Example 1 (zinc thin film).
12 shows cycle test results of Device Example 1 (zinc-carbon fiber composite nonwoven fabric) and Device Comparative Example 1 (zinc thin film).

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention.

However, the following description is not intended to limit the present invention to specific embodiments, and in describing the present invention, if it is determined that the detailed description of related known technologies may obscure the gist of the present invention, the detailed description will be omitted. .

Terms used herein are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, the terms "comprise" or "having" are intended to indicate that there is a feature, number, step, operation, component, or combination thereof described in the specification, but one or more other features or It should be understood that the presence or addition of numbers, steps, operations, components, or combinations thereof is not precluded.

Also, terms including ordinal numbers such as first and second to be used below may be used to describe various components, but the components are not limited by the terms. These terms are only used for the purpose of distinguishing one component from another. For example, a first element may be termed a second element, and similarly, a second element may be termed a first element, without departing from the scope of the present invention.

In addition, when a component is referred to as being “formed” or “layered” on another component, it may be formed or laminated directly on the front or one side of the surface of the other component, but intermediate It should be understood that other components may be further present.

Hereinafter, a carbon fiber composite nonwoven fabric, an electrode current collector including the same, and a manufacturing method thereof will be described in detail. However, this is presented as an example, and the present invention is not limited thereby, and the present invention is only defined by the scope of the claims to be described later.

1 is a schematic diagram showing a carbon fiber composite nonwoven fabric and a manufacturing method thereof according to one embodiment of the present invention.

Referring to Figure 1, the present invention is a carbon fiber; and a binder including micro short fibers and nano long fibers, wherein the micro short fibers include a hydrophilic polymer, and the nano long fibers include cellulose nanofibers (CNF). A composite nonwoven fabric is provided.

In addition, the nano-long fiber is positioned on the carbon fiber and the carbon fiber to crosslink the carbon fiber and the carbon fiber, or the nano-long fiber is positioned on the micro short fiber and the micro short fiber to cross-link the micro short fiber. Crosslinking and micro short fibers with each other, or the nano long fibers are located on the carbon fibers and micro short fibers to cross-link the carbon fibers and micro short fibers with each other to form a carbon fiber composite nonwoven fabric with a three-dimensional network structure. can

In addition, the nano-long fibers may form a film-like fiber bundle.

In addition, the hydrophilic polymer is polyvinyl alcohol (PVA), hydrophilic polyurethane, polyethylene oxide (PEO), polypropylene oxide (PPO), polydopamine, poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT) :PSS) and at least one selected from the group consisting of combinations thereof, preferably polyvinyl alcohol.

In addition, the carbon fiber composite nonwoven fabric may include 10 to 50 parts by weight of the binder based on 100 parts by weight of the carbon fibers, and preferably 30 to 50 parts by weight. When the amount of the binder is less than 10 parts by weight, it is difficult to form a nonwoven fabric due to the low content of the binder, and when it exceeds 50 parts by weight, the content of carbon fibers is low, and sheet resistance of the carbon fiber composite nonwoven fabric is increased, which is not preferable.

In addition, the weight (wt) ratio (MF:NF) of the micro short fibers (MF) and the nano long fibers (NF) may be 5:5 to 9:1, preferably 5:5 to 7:3 can be When the ratio of the micro short fibers (MF) is increased at the weight (wt) ratio (MF:NF) of 5:5, the pores through which the solvent escapes are blocked during the process of manufacturing the carbon fiber composite nonwoven fabric by the wet manufacturing method, thereby reducing the process time This is undesirable because this drastically increases, and when the ratio of the nano long fibers (NF) is reduced at a weight (wt) ratio (MF:NF) of 9:1, sufficient crosslinking occurs between micro short fibers and carbon fibers and nanofibers. If not, the tensile strength is significantly lowered, which is undesirable.

In addition, the basis weight of the carbon fiber composite nonwoven fabric may be 50 to 300 gsm, preferably 100 to 200 gsm. If the basis weight of the carbon fiber composite nonwoven fabric is less than 50 gsm, it is highly likely to be damaged in the process of peeling off the sample after drying when manufacturing the carbon fiber composite nonwoven fabric, and if it exceeds 300 gsm, to prepare a carbon fiber composite nonwoven fabric It takes a long time for the solvent to escape during the process, which is undesirable because the process time is greatly increased.

In addition, the length of the micro short fibers may be 0.5 to 3 mm, and the width of the micro short fibers may be 5 to 30 μm.

The present invention provides an electrode current collector including the carbon fiber composite nonwoven fabric.

In addition, the electrode current collector is the carbon fiber composite non-woven fabric; and a metal coated on the carbon fiber composite nonwoven fabric.

In addition, the metal is zinc (Zn), gold (Au), silver (Ag), aluminum (Al), beryllium (Be), bismuth (Bi), cobalt (Co), copper (Cu), chromium (Cr), Cadmium (Cd), Iron (Fe), Gallium (Ga), Hafnium (Hf), Indium (In), Iridium (Ir), Manganese (Mn), Molybdenum (Mo), Magnesium (Mg), Nickel (Ni) ), niobium (Nb), lead (Pb), palladium (Pd), platinum (Pt), rhodium (Rh), rhenium (Re), rubidium (Ru), antimony (Sb), tin (Sn), tantalum It may contain at least one selected from the group consisting of rum (Ta), tellurium (Te), titanium (Ti), vanadium (V), tungsten (W) and zirconium (Zr), preferably containing zinc can do.

Figure 2 is a schematic diagram showing a method for manufacturing a carbon fiber composite nonwoven fabric according to one embodiment of the present invention.

Referring to Figure 2, the present invention comprises the steps of (a) preparing a mixed solution containing carbon fibers; (b) preparing a binder solution containing micro short fibers and nano long fibers; and (c) preparing the carbon fiber composite nonwoven fabric according to claim 1 by mixing the mixed solution and the binder solution.

In addition, by mixing in step (c), the nano-long fibers cross-link at least one selected from the group consisting of the carbon fibers and the micro-short fibers to form a three-dimensional network structure.

In addition, the nano-long fiber may be in the form of a fiber bundle.

In addition, the weight (wt) ratio (MF:NF) of the micro short fibers (MF) and the nano long fibers (NF) in the binder solution may be 5:5 to 9:1, preferably 5:5 to 7:3. When the ratio of the micro short fibers (MF) is increased at the weight (wt) ratio (MF:NF) of 5:5, the pores through which the solvent escapes are blocked during the process of manufacturing the carbon fiber composite nonwoven fabric by the wet manufacturing method, thereby reducing the process time This is undesirable because this drastically increases, and when the ratio of the nano long fibers (NF) is reduced at a weight (wt) ratio (MF:NF) of 9:1, sufficient crosslinking occurs between micro short fibers and carbon fibers and nanofibers. If not, the tensile strength is significantly lowered, which is undesirable.

[Example]

Hereinafter, a preferred embodiment of the present invention will be described. However, this is for illustrative purposes and the scope of the present invention is not limited thereby.

Manufacture of carbon fiber composite nonwoven fabric

Example 1

1 is a schematic diagram showing a carbon fiber composite nonwoven fabric and a manufacturing method thereof according to one embodiment of the present invention, and FIG. 2 is a schematic diagram showing a manufacturing method of a carbon fiber composite nonwoven fabric according to one embodiment of the present invention. A carbon fiber composite nonwoven fabric of Example 1 was prepared with reference to FIGS. 1 and 2.

First, carbon fibers (Catech H, T300) were cut into short fibers of less than 3 mm, and a mixed solution was prepared based on 1 L of distilled water per 1 g of the carbon fibers.

Micro short fibers, polyvinyl alcohol (PVA) (Kuraray, KURALON K-II ^TM ) and nano long fibers, cellulose nanofibers (CNF) (Moorim P&P, fibers with a length of 3 to 300 μm and a width of less than 50 nm are 2 The gel dispersed in water by wt%) was dispersed in 500 mL of distilled water using a stirrer for about 10 minutes to prepare a white suspension (binder solution). At this time, the PVA and the CNF were prepared at a ratio of 9:1.

Thereafter, the mixed solution and the binder solution were mixed and a carbon fiber composite nonwoven fabric having a basis weight of 200 gsm was prepared using a wet nonwoven fabric manufacturing apparatus. The ratio of carbon fiber and binder (PVA + CNF) in the carbon fiber composite nonwoven fabric was 7 :3.

Examples 2 to 5, Comparative Example 1

A carbon fiber composite nonwoven fabric was prepared under the same conditions as in Example 1, but with a different ratio of PVA and CNF, and the manufacturing conditions are shown in Table 1 below.

division Carbon Fiber (%) PVA (%) CNFs (%) Example 1 70 27 3 Example 2 70 24 6 Example 3 70 21 9 Example 4 70 18 12 Example 5 70 15 15 Comparative Example 1 70 30 0

Examples 6 to 10

A carbon fiber composite nonwoven fabric was manufactured under the same conditions as in Example 1, but the basis weight of the carbon fiber composite nonwoven fabric was changed, and the manufacturing conditions are shown in Table 2 below.

division Basis weight (gsm) Example 1 200 Example 6 50 Example 7 100 Example 8 150 Example 9 250 Example 10 300

Examples 11 to 14

A carbon fiber composite nonwoven fabric was prepared under the same conditions as in Example 1, but was prepared by varying the ratio of carbon fiber and binder (PVA + CNF), and the manufacturing conditions are shown in Table 3 below.

division Carbon Fiber (%) PVA (%) CNFs (%) Example 1 70 27 3 Example 11 90 9 One Example 12 80 18 2 Example 13 60 36 4 Example 14 50 45 5

Manufacture of electrode current collector

Example 15

An electrode current collector was manufactured by coating zinc on the surface of the carbon fiber composite nonwoven fabric prepared according to Example 1 through sputtering. The sputtering was conducted for 2 hours.

Manufacture of electrochemical symmetric cell

Device Example 1

The electrode current collector prepared according to Example 15 was cut into a size of 8 pie in diameter. Thereafter, the electrode current collector cut into a 2032 coin cell was used as an anode and a cathode, respectively, and a symmetrical cell injected with 3 M ZnSO ₄ was manufactured.

Device comparison example 1

Zn foil was cut into a size of 8 pie in diameter. Thereafter, the zinc thin film cut into a 2032 coin cell was used as an anode and a cathode, respectively, and a symmetrical cell injected with 3 M ZnSO ₄ was manufactured.

[Test Example]

Electron microscopic analysis (FE-SEM) was analyzed using SU8020 (HITACHI).

The tensile strength was analyzed using Instron-3343 (INSTRON), and the tensile strength of the carbon fiber composite nonwoven fabric was measured by pulling at 20 mm per minute at a measuring distance of 20 mm with a sample size of 10 mm in length and 50 mm in width.

Test Example 1: Confirmation of carbon fiber composite nonwoven fabric shape according to composition change of binder

3 shows actual images and SEM images of carbon fiber composite nonwoven fabrics for each CNF content of Examples 1 to 5 and Comparative Example 1. In detail, Figure 3a shows actual images of carbon fiber composite nonwoven fabrics for each CNF content in Examples 1 to 5 and Comparative Example 1, Figure 3b is a cross-sectional SEM image of Example 1, and Figure 3c is a cross-section of Example 5 SEM image, Figure 3d is a surface SEM image of Comparative Example 1, Figure 3e is a surface SEM image of Example 1, Figure 3f is a surface SEM image of Example 2, Figure 3g is a surface SEM image of Example 3, Figure 3h is a surface SEM image Surface SEM image of Example 4, Figure 3i shows the surface SEM image of Example 5.

According to Figure 3a, it can be seen that there is a big difference in the shape of the carbon fiber nonwoven fabric with no CNF added (CNF 0%, Comparative Example 1) and the added carbon fiber nonwoven fabric (Examples 1 to 5). It can be seen that the carbon fiber nonwoven fabric without CNF is formed with a thickness of 2.3 mm because the bond between the carbon fiber and the PVA short fiber is not formed, and the fibers sometimes come off. On the other hand, it can be seen that the carbon fiber nonwoven fabric to which CNF is added has a relatively thin thickness and has a rigid structure, and as the content of CNF increases, the number of fibers falling off decreases.

According to FIGS. 3b and 3c, in Example 1 (FIG. 3b) in which the CNF content is 10%, carbon fibers and PVA are indiscriminately laminated, and the layer separation phenomenon is observed due to the low content of CNF to connect the fibers. can do. On the other hand, in the case of Example 5 (FIG. 3c) in which the CNF content is 50%, since the CNF serves as a bridge between the carbon fibers and the PVA-laminated microfibers, the mechanical strength of the nonwoven fabric increases as the CNF content increases. Improvements in physical properties can be expected.

According to FIG. 3D, carbon fiber is relatively thin and straight with a cylindrical structure, and PVA short fiber is relatively thick and has a wide surface. It can be seen that the bonding strength is very weak because the carbon fiber and the PVA single fiber form a structure in which the fibers are stacked without bonding with each other.

According to FIG. 3e, in Example 1, microstructured fibers form a network on the surface of the carbon fiber and PVA single fiber, and it can be seen that the bonding force is somewhat stronger than that of Comparative Example 1 (FIG. 3d) in which the CNF content is 0%. . As the CNF content in the binder of the carbon fiber nonwoven fabric increases, the fiber bundle forms a surface and connects the carbon fiber and the PVA short fiber. Due to this structure, it helps to maintain the shape of the nonwoven fabric, and in samples with 0% and 10% relatively low CNF content, carbon fiber fragments may come off.

According to FIGS. 3f and 3g, Example 2 in which the content of CNF is 20% and Example 3 in which the content of CNF is 30% are well maintained, and it can be seen that the phenomenon of carbon fiber fragments falling off is significantly reduced. .

According to FIGS. 3h and 3i, in Example 4 in which the CNF content is 40% and in Example 5 in which the CNF content is 50%, it can be seen that the carbon fiber and the PVA short fiber are covered with films. The film appears because CNF, which is a nano-long fiber, forms numerous bundles and connects micro fibers (carbon fiber and PVA short fiber), and it can be seen that more film shapes appear as the content of CNF increases.

Test Example 2: Confirmation of formation and structure of carbon fiber composite nonwoven fabric

4 shows an actual image of a carbon fiber composite nonwoven fabric prepared according to Example 5 of the present invention.

According to FIG. 4, it can be confirmed that the carbon fiber composite nonwoven fabric is well manufactured according to the manufacturing method of the present invention.

Figure 5a shows a SEM image (scare bar = 500 μm) of the surface of the carbon fiber composite nonwoven fabric prepared according to Example 5, Figure 5b is a SEM image (scare bar = 500 μm) of the surface of the carbon fiber composite nonwoven fabric prepared according to Example 5 = 50 μm).

According to FIG. 5a, it can be seen that the carbon fiber has a straight line shape and the PVA has a fiber shape. In addition, CNF is located on the carbon fibers and carbon fibers to cross-link the carbon fibers and carbon fibers, or is located on the PVA short fibers and PVA short fibers to cross-link the PVA short fibers and PVA short fibers to each other. Alternatively, it can be confirmed that the carbon fiber and the PVA short fiber are cross-linked with each other to form a carbon fiber composite nonwoven fabric having a three-dimensional network structure.

According to Figure 5b, it can be seen that the CNF has a fiber bundle form. In addition, it can be confirmed that the CNF surrounds the surface of the carbon fiber or the PVA short fiber and serves to connect fibers to fibers.

Test Example 3: Hydrophilic property analysis of carbon fiber composite nonwoven fabric

6 shows contact angle analysis data of the carbon fiber composite nonwoven fabric of Example 1.

In detail, while fixing the carbon fiber composite nonwoven fabric of Example 5 to a contact angle measuring device and dropping a certain amount (0.03 mL) of distilled water, a video was continuously taken using a digital camera for a predetermined time, and a part of the video was assisted. is indicated by 4.

According to FIG. 6, it can be confirmed that water droplets dropped on the surface of the carbon fiber composite nonwoven fabric are immediately absorbed into the nonwoven fabric. This is a phenomenon caused by the hydrophilic material in the three-dimensional network structure of the carbon fiber composite nonwoven fabric with many pores and the binder, PVA micro short fibers and CNF nano long fibers.

Hydrophilic property is an important factor for use as an electrode for an aqueous secondary battery, and since the carbon fiber composite nonwoven fabric of the present invention has excellent hydrophilic properties, the carbon fiber composite nonwoven fabric of the present invention can be used as an electrode for an aqueous secondary battery.

Test Example 4: Sheet resistance measurement and tensile strength analysis of carbon fiber composite nonwoven fabric

Test Example 4-1: Analysis of Sheet Resistance and Tensile Strength by CNF Content

Figure 7a shows resistance analysis data by CNF content of Examples 1 to 5 and Comparative Example 1, and Figure 8a shows tensile strength analysis data by CNF content of Examples 1 to 5 and Comparative Example 1. In addition, in Table 4 below, the resistance and tensile strength according to the CNF content of Examples 1 to 5 and Comparative Example 1 are summarized and shown.

division Carbon Fiber (%) PVA (%) CNFs (%) Resistance (Ω) Tensile strength (gf) Example 1 70 27 3 4.3 1,971 Example 2 70 24 6 3.8 2,457 Example 3 70 21 9 3.3 3,444 Example 4 70 18 12 3.2 5,326 Example 5 70 15 15 2.5 6,662 Comparative Example 1 70 30 0 6.0 92

According to Figures 7a, 8a and Table 4, it can be seen that the resistance decreases as the content of CNF in the carbon fiber composite nonwoven fabric increases. Therefore, it can be seen that a low sheet resistance value can be obtained only when CNF is secured above a certain level.

In addition, it can be seen that the tensile strength increases as the content of CNF increases, and the increase does not decrease.

However, when the CNF content is added above a certain level, the time required to remove water in the wet-laid nonwoven fabric manufacturing process increases rapidly (process time increase), so it is preferable to include 10 to 50 parts by weight relative to 100 parts by weight of the binder (PVA + CNF) .

Test Example 4-2: Sheet resistance and tensile strength analysis by basis weight

7B shows resistance analysis data by basis weight of Example 1 and Examples 6 to 10, and FIG. 8B shows tensile strength analysis data by basis weight of Example 1 and Examples 6 to 10. In addition, in Table 5 below, resistance and tensile strength by basis weight of Example 1 and Examples 6 to 10 are summarized and shown.

division Basis weight (gsm) Resistance (Ω) Tensile strength (gf) Example 1 200 4.3 1,971 Example 6 50 13.5 430 Example 7 100 6.9 746 Example 8 150 3.3 1,531 Example 9 250 3.1 2,161 Example 10 300 3.2 2,197

According to FIGS. 7b and 8b and Table 5, it can be confirmed that the resistance decreases as the basis weight increases in the carbon fiber composite nonwoven fabric, and the tensile strength increases as the basis weight increases, but the increase gradually decreases.

Accordingly, it can be confirmed that the preferred basis weight value of the carbon fiber composite nonwoven fabric is 100 to 200 gsm.

Test Example 4-3: Analysis of Sheet Resistance and Tensile Strength by Binder Content

7C shows resistance analysis data for each binder content of Example 1 and Examples 11 to 14, and FIG. 8C shows tensile strength analysis data for each binder content of Example 1 and Examples 11 to 14. In addition, in Table 6 below, resistance and tensile strength for each binder content of Example 1 and Examples 11 to 14 are summarized and shown.

division Carbon Fiber (%) PVA (%) CNFs (%) Resistance (Ω) Tensile strength (gf) Example 1 70 27 3 4.3 1,971 Example 11 90 9 One 2.6 194 Example 12 80 18 2 2.4 734 Example 13 60 36 4 5.1 2,390 Example 14 50 45 5 4.5 2,794

7c and 8c and Table 6, it can be seen that the higher the sheet resistance value, the lower the carbon fiber content. Therefore, it can be seen that a low sheet resistance value can be obtained only when the content of carbon fiber is high.

In addition, it can be seen that the tensile strength increases as the carbon fiber content increases, but the increase gradually decreases.

Therefore, it can be confirmed that the preferred content of the binder is 30 to 50 parts by weight based on 100 parts by weight of the carbon fiber composite nonwoven fabric.

Test Example 5: Confirmation of Formation of Electrode Current Collector

FIG. 9A shows a digital photograph of an electrode current collector manufactured according to Example 15, and FIG. 9B shows an SEM photograph of the electrode current collector manufactured according to Example 15 at different magnifications.

9a and 9b, it can be seen that the surface color of the carbon fiber composite nonwoven fabric has changed slightly to brown, there is no significant change in the microstructure of the carbon fiber composite nonwoven fabric, and it can be confirmed that zinc is thinly coated on the surface of the nonwoven fabric. can

10 shows energy dispersive X-ray spectroscopy (EDS) mapping and spectrum results of an electrode current collector prepared according to Example 15.

According to FIG. 10, it can be seen that in the electrode current collector of Example 15, a thin layer composed only of zinc is formed on the surface of the carbon fiber composite nonwoven fabric.

Test Example 6: Symmetric cell evaluation

11 is a graph of charging and discharging overvoltage according to rate change of Device Example 1 (zinc-carbon fiber composite nonwoven fabric) and Device Comparative Example 1 (zinc thin film). In detail, in order to confirm the rate characteristic, charging and discharging were performed for 10 minutes each under conditions of 0.1, 0.2, 0.5, 1, 2, 5, and 10 mA/cm ² , and the results are shown in FIG. 11 .

According to FIG. 11, in the case of Device Comparative Example 1 using a zinc foil, a very unstable charge/discharge overvoltage behavior was shown from the time the rate limit reached 0.5 mA/cm ² , and the instability continued as the rate rate increased. You can see that you are seeing an improvement.

On the other hand, in the case of Device Example 1 using the zinc-carbon fiber nonwoven fabric (electrode current collector of Example 15), it can be seen that stable charge/discharge overvoltage behavior is exhibited at each rate.

12 shows cycle test results of Device Example 1 (zinc-carbon fiber composite nonwoven fabric) and Device Comparative Example 1 (zinc thin film). In detail, FIG. 12 shows the results of the repeated charge/discharge test at a rate of 3 mA/cm ² and a capacity of 0.5 mAh/cm ² .

According to FIG. 12, in the case of Device Comparative Example 1 using a zinc foil, the charge/discharge overvoltage fluctuated severely before 10 hours passed, whereas the zinc-carbon fiber nonwoven fabric (electrode current collector of Example 15) was used. In the case of Device Example 1, it can be confirmed that stable overvoltage behavior is exhibited for more than 300 hours.

Therefore, it can be confirmed that the carbon fiber composite nonwoven fabric prepared according to the present invention serves to help stable charge and discharge reactions as a negative electrode current collector of a zinc ion battery.

The scope of the present invention is indicated by the following claims rather than the detailed description above, and all changes or modifications derived from the meaning and scope of the claims and equivalent concepts should be construed as being included in the scope of the present invention. do.

Claims (15)

carbon fiber; and
A binder including micro short fibers and nano long fibers;
The micro short fibers include a hydrophilic polymer,
The nano-long fibers include cellulose nanofibers (CNF),
The nano-long fiber is positioned on the carbon fiber and the carbon fiber to crosslink the carbon fiber and the carbon fiber with each other,
The nano-long fibers are positioned on the micro-short fibers and the micro-short fibers to cross-link the micro-short fibers with each other;
The nano-long fibers are positioned on the carbon fibers and micro short fibers to crosslink the carbon fibers and micro short fibers with each other to form a carbon fiber composite nonwoven fabric having a three-dimensional network structure,
A carbon fiber composite nonwoven fabric for use in electrode current collectors of water-based batteries. delete According to claim 1,
Carbon fiber composite nonwoven fabric, characterized in that the nano-long fibers form a film-like fiber bundle form. According to claim 1,
The hydrophilic polymer is polyvinyl alcohol (PVA), hydrophilic polyurethane, polyethylene oxide (PEO), polypropylene oxide (PPO), polydopamine, poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS ) And a carbon fiber composite nonwoven fabric comprising at least one selected from the group consisting of combinations thereof. According to claim 1,
The carbon fiber composite nonwoven fabric comprises 10 to 50 parts by weight of the binder based on 100 parts by weight of the carbon fiber. According to claim 1,
The carbon fiber composite nonwoven fabric, characterized in that the weight (wt) ratio (MF: NF) of the micro short fibers (MF) and the nano long fibers (NF) is 5: 5 to 9: 1. According to claim 1,
Carbon fiber composite nonwoven fabric, characterized in that the basis weight of the carbon fiber composite nonwoven fabric is 50 to 300 gsm. According to claim 1,
The length of the micro short fibers is 0.5 to 3 mm,
Carbon fiber composite nonwoven fabric, characterized in that the width of the micro short fibers is 5 to 30 μm. An electrode current collector for use in an aqueous battery, comprising the carbon fiber composite nonwoven fabric according to claim 1 . According to claim 9,
the electrode current collector
The carbon fiber composite nonwoven fabric; and
An electrode current collector comprising a; metal coated on the carbon fiber composite nonwoven fabric. According to claim 10,
The metal is zinc (Zn), gold (Au), silver (Ag), aluminum (Al), beryllium (Be), bismuth (Bi), cobalt (Co), copper (Cu), chromium (Cr), cadmium ( Cd), iron (Fe), gallium (Ga), hafnium (Hf), indium (In), iridium (Ir), manganese (Mn), molybdenum (Mo), magnesium (Mg), nickel (Ni), Niobium (Nb), Lead (Pb), Palladium (Pd), Platinum (Pt), Rhodium (Rh), Rhenium (Re), Rubidium (Ru), Antimony (Sb), Tin (Sn), Tantalum ( An electrode current collector characterized in that it comprises at least one selected from the group consisting of Ta), tellurium (Te), titanium (Ti), vanadium (V), tungsten (W), and zirconium (Zr). (a) preparing a mixed solution containing carbon fibers;
(b) preparing a binder solution containing micro short fibers and nano long fibers; and
(c) preparing a carbon fiber composite nonwoven fabric according to claim 1 by mixing the mixed solution and the binder solution;
A method for producing a carbon fiber composite nonwoven fabric comprising: According to claim 12,
Preparation of a carbon fiber composite nonwoven fabric, characterized in that by mixing in step (c), the nano-long fibers cross-link at least one selected from the group consisting of the carbon fibers and the micro short fibers to form a three-dimensional network structure. method. According to claim 13,
Method for producing a carbon fiber composite nonwoven fabric, characterized in that the nano-long fiber is in the form of a fiber bundle. According to claim 12,
Method for producing a carbon fiber composite nonwoven fabric, characterized in that the weight (wt) ratio (MF: NF) of the micro short fibers (MF) and the nano long fibers (NF) in the binder solution is 5: 5 to 9: 1 .