阅读说明：本技术 薄型氧化还原液流电池电极的制备方法 (Preparation method of thin redox flow battery electrode ) 是由 崔祐喆 尹国献 崔雄晖 于 2018-07-16 设计创作，主要内容包括：本发明的薄型氧化还原液流电池电极的制备方法的特征在于,包括：步骤(1),准备碳纤维束和碳纤维毡；步骤(2),通过针刺对上述碳纤维束进行扩布,来制备由碳纤维向单方向排列而成的支撑层；步骤(3),在上述支撑层上放置上述碳纤维毡；步骤(4),通过对上述碳纤维毡进行针刺,来使上述碳纤维毡内的碳纤维被牵引下来,捆扎上述支撑层内的碳纤维,使得上述支撑层内的碳纤维不向左右散开；步骤(5),针反复穿过上述碳纤维毡并逐渐压接上述碳纤维毡,从而在上述碳纤维毡的上部面向电解液流动的方向形成流路；以及步骤(6),通过反复进行上述步骤(5),来在上述碳纤维毡还形成与上述流路平行的多个其他流路。(The method for producing a thin redox flow battery electrode of the present invention is characterized by comprising: step (1), preparing carbon fiber bundles and a carbon fiber felt; step (2), spreading the carbon fiber bundles by needling to prepare a supporting layer formed by arranging the carbon fibers in a single direction; step (3), placing the carbon fiber felt on the supporting layer; step (4), the carbon fibers in the carbon fiber felt are pulled down by needling the carbon fiber felt, and the carbon fibers in the supporting layer are bound, so that the carbon fibers in the supporting layer are not scattered left and right; step (5), repeatedly penetrating the carbon fiber felt by a needle and gradually pressing the carbon fiber felt, thereby forming a flow path on the upper part of the carbon fiber felt facing to the flowing direction of the electrolyte; and (6) repeating the step (5) to form a plurality of other flow paths parallel to the flow path in the carbon fiber mat.)

1. A method for preparing a thin redox flow battery electrode, comprising:

step (1), preparing carbon fiber bundles and a carbon fiber felt;

step (2), spreading the carbon fiber bundles by needling to prepare a supporting layer formed by arranging the carbon fibers in a single direction;

step (3), placing the carbon fiber felt on the supporting layer;

step (4), the carbon fibers in the carbon fiber felt are pulled down by needling the carbon fiber felt, and the carbon fibers in the supporting layer are bound, so that the carbon fibers in the supporting layer are not scattered left and right;

step (5), repeatedly penetrating the carbon fiber felt by a needle and gradually pressing the carbon fiber felt, thereby forming a flow path on the upper part of the carbon fiber felt facing to the flowing direction of the electrolyte; and

and (6) repeating the step (5) to form a plurality of other flow paths parallel to the flow path in the carbon fiber mat.

2. The method for producing a thin redox flow battery electrode according to claim 1, wherein the carbon fiber mat has an areal density of 10g/m²～300g/m²。

3. The method for producing a thin redox flow battery electrode according to claim 1, wherein the carbon fiber mat has a thickness of 0.1 to 1 mm.

4. The method for producing a thin redox flow battery electrode according to claim 1, wherein the support layer is formed by arranging unit groups in a single direction, the unit groups being formed by stacking several to several tens of carbon fibers.

5. The method for producing a thin redox flow battery electrode according to claim 4, wherein the thickness of the support layer is several times the diameter of the carbon fiber constituting the unit group.

6. The method of manufacturing a thin redox flow battery electrode according to claim 1, wherein the support layer is formed by arranging a single carbon fiber in a single direction.

7. The method of manufacturing a thin redox flow battery electrode according to claim 1, wherein the thickness of the support layer is the same as the diameter of the carbon fiber.

Technical Field

The invention relates to a preparation method of a redox flow battery electrode.

Background

A redox flow battery is a secondary battery that repeats charge and discharge according to an electrochemical reaction of an electrolyte. Examples of the electrolyte used in the redox flow battery include vanadium, Zn — Br, and the like.

Redox flow batteries circulate electrolytes and perform charging and discharging. Charge and discharge occur in the stack where the electrochemical reactions of oxidation and reduction take place, and electricity is stored in the electrolytic solution.

The output of the redox flow battery is determined according to the number and size of the stacks, and the electric capacity is determined according to the amount of electrolyte stored in the tank.

The redox flow battery can semi-permanently use an electrolyte that stores electricity, thereby being environmentally friendly and having no explosive risk.

In such a redox flow battery, it is important that the electrolyte neither escapes from the electrodes, nor has a flow that does not stagnate within the electrodes until the electrolyte sufficiently undergoes an electrochemical reaction, so that the efficiency of the redox flow battery is continuously maintained.

In order to solve such problems, a method of preparing a redox flow battery electrode, in which a plurality of flow paths are formed in a direction in which a carbon fiber felt flows toward an electrolyte by needling so that the electrolyte flows smoothly along the flow paths, is proposed in korean issued patent (10-1865057) of the present applicant. In the method for manufacturing the redox flow battery electrode, a carbon fiber felt with the thickness of 0.1-1 mm is placed on a thermoplastic resin net with the thickness of 0.1-2.0 mm, and needling is carried out to form a flow path, and the net plays a role of supporting the flow path so that the flow path keeps the original shape.

On the other hand, if more unit cells are stacked in the same space by reducing the thickness of the redox flow battery electrode, more electricity can be produced.

However, the mesh used in Korean granted patent (10-1865057) is made of thermoplastic resin, and it is practically difficult to make the thickness less than 1 mm. Therefore, it is difficult to make the thickness of the electrode less than 1mm, which is the sum of the thicknesses of the carbon fiber felt and the mesh.

On the other hand, in korean patent laid-open publication (10-1865057), a flow path is formed on the upper surface of a carbon fiber felt by placing the carbon fiber felt on the upper surface of a mesh and needling the carbon fiber felt, and the carbon fiber felt and the mesh are bonded, so that the needles collide with the hard mesh and are frequently broken, and the broken needles are hidden in the carbon fiber felt, thereby causing a failure of the redox flow battery.

Disclosure of Invention

The present invention provides a method for producing a thin redox flow battery electrode having a novel concept, which can solve the above-mentioned problems.

The method for producing a thin redox flow battery electrode for achieving the above object is characterized. The method comprises the following steps: step (1), preparing carbon fiber bundles and a carbon fiber felt; step (2), spreading the carbon fiber bundles by needling to prepare a supporting layer formed by arranging the carbon fibers in a single direction; step (3), placing the carbon fiber felt on the supporting layer; step (4), the carbon fibers in the carbon fiber felt are pulled down by needling the carbon fiber felt, and the carbon fibers in the supporting layer are bound, so that the carbon fibers in the supporting layer are not scattered left and right; step (5), repeatedly penetrating the carbon fiber felt by a needle and gradually pressing the carbon fiber felt, thereby forming a flow path on the upper part of the carbon fiber felt facing to the flowing direction of the electrolyte; and (6) repeating the step (5) to form a plurality of other flow paths parallel to the flow path in the carbon fiber mat.

In the present invention, since the flow path is formed by needling a carbon fiber mat placed on a support layer in which unit groups of several to several tens of high-strength carbon fibers are laminated and arranged in one direction, the flow path can be supported at a thickness (0.1 to 0.2mm) thinner than that of a conventional thermoplastic web so as not to collapse.

In the present invention, since the flow path is formed by needling a support layer in which one high-strength carbon fiber is arranged in one direction, the flow path can be supported so as not to collapse even if the thickness is much thinner than that of the conventional thermoplastic web. Thus, the thickness of the redox flow battery electrode in which the thickness of the carbon fiber felt and the thickness of the support layer are added can be reduced to 1/5, which is the thickness of the conventional redox flow battery electrode using a thermoplastic mesh, so that more unit cells are stacked in the same space, thereby producing more electricity.

Further, the present invention has a support layer in which carbon fibers, which are not lattice-type thermoplastic nets, are arranged in a row in the direction in which the electrolyte flows, so that the support layer can function to guide the direction in which the electrolyte flows.

ADVANTAGEOUS EFFECTS OF INVENTION

The present invention has a support layer formed of flexible carbon fibers that is not a rigid thermoplastic web, thereby eliminating the problem of needle-breaking even if a carbon fiber felt is placed on the support layer for needling. Therefore, the following problems can be obstructed: the pins, after breaking by collision with the stiff mesh, are hidden within the carbon fiber felt to cause failure of the redox flow battery.

Drawings

Fig. 1 is a flowchart showing a method for producing a thin redox flow battery electrode according to an embodiment of the present invention.

Fig. 2 is a view showing a state in which the carbon fiber bundles are spread in the right and left directions by needle punching.

Fig. 3 is a view showing a state in which a carbon fiber mat is placed on a support layer in which unit groups each formed by stacking several to several tens of carbon fibers are arranged in one direction.

Fig. 4 is a view showing a state in which a carbon fiber mat is placed on a support layer in which individual carbon fibers are aligned in one direction.

Fig. 5 is a view showing a state in which unidirectional carbon fibers in the support layer shown in fig. 3 are bundled by carbon fibers in the carbon fiber mat held by needling so as not to spread out to the left and right.

Fig. 6 is a view showing a state in which unidirectional carbon fibers in the support layer shown in fig. 4 are bundled by carbon fibers in the carbon fiber mat pulled by needling so as not to spread to the left and right.

Fig. 7 is a view showing a state in which a needle repeatedly penetrates the carbon fiber mat shown in fig. 5 and is pressure-bonded to form a flow path at a specific portion of the upper surface of the carbon fiber mat.

Fig. 8 is a view showing a state in which a needle repeatedly penetrates the carbon fiber mat shown in fig. 6 and is pressure-bonded to form a flow path at a specific portion of the upper surface of the carbon fiber mat.

Fig. 9 is a view showing a redox flow battery electrode formed by forming a plurality of flow paths at predetermined intervals on the upper surface of the carbon fiber mat shown in fig. 5.

Fig. 10 is a view showing a redox flow battery electrode in which a plurality of flow paths are formed at predetermined intervals on the upper surface of the carbon fiber mat shown in fig. 6.

Fig. 11 is an exploded perspective view of a unit cell provided with the redox flow battery electrode shown in fig. 9.

Fig. 12 is an exploded perspective view of a unit cell provided with the redox flow battery electrode shown in fig. 10.

Description of the reference numerals

1. 2: the unit cell 11: ion exchange membrane

12: spacer 13: bipolar plate

10. 20: redox flow battery electrode F: carbon fiber felt

S1, S2: support layers CF1, CF 2: carbon fiber

Detailed Description

Hereinafter, a method for producing a thin redox flow battery electrode according to an embodiment of the present invention will be described in detail.

As shown in fig. 1, a method for manufacturing a thin redox flow battery electrode according to an embodiment of the present invention includes: step (1) S11, preparing carbon fiber bundles and a carbon fiber felt; step (2) S12, preparing a support layer in which carbon fibers are arranged in a single direction by spreading the carbon fiber bundles by needling; step (3) S13, placing the carbon fiber mat on the support layer; step (4) S14, by needling the carbon fiber felt, the carbon fibers in the carbon fiber felt are pulled down to bind the carbon fibers in the support layer, so that the carbon fibers in the support layer are not scattered left and right; step (5) S15, repeatedly passing a needle through the carbon fiber mat and gradually pressing the carbon fiber mat to form a flow path facing the direction of the electrolyte on the upper part of the carbon fiber mat; and (6) S16, repeating the step (5), thereby forming a plurality of other flow paths parallel to the flow path in the carbon fiber mat.

Step (1) S11 will be explained.

A carbon fiber bundle T as shown in fig. 2 is prepared. The carbon fiber bundle T has a form of a bundle (tow) in which long carbon fibers CF1 are aligned in one direction. The carbon fiber CF1 is formed of several to several hundred carbon fiber filaments so as to have a diameter of 0.1 to 0.2 mm. To avoid the drawings becoming overly complicated, the carbon fiber filaments are omitted from illustration in fig. 2 to 12.

A carbon fiber mat F shown in fig. 3 was prepared. The carbon fiber mat F is made by randomly agglomerating short carbon fibers CF 2. The thickness of the carbon fiber felt F is 0.1-1 mm.

Preferably, the areal density of the carbon fiber felt F is 10g/m²～300g/m²More preferably, the areal density of the carbon fiber felt F is 50g/m²～200g/m²。

The reason for this is that if the areal density of the carbon fiber mat F is less than 10g/m²The carbon fiber felt F directly absorbs the electrolyte, so that the flow path does not normally function, the durability of the carbon fiber felt F is greatly reduced, and if the areal density of the carbon fiber felt F is more than 300g/m²It is difficult to produce the thin carbon fiber mat F, and the material cost increases.

Step (2) S12 will be explained.

As shown in fig. 2, when the needle N repeatedly punches the carbon fiber bundle T, the intervals between the carbon fibers CF1 constituting the carbon fiber bundle T gradually increase, and the carbon fiber bundle T is spread.

As the carbon fiber bundles T pass through the needle-punched spread cloth, the support layers S1, S2 shown in fig. 3 or fig. 4 are prepared. Although needling can be performed without being bound to both ends of the carbon fiber bundle T, in order to prevent the carbon fibers CF1 from coming apart during needling, needling can be performed on the middle portion of the carbon fiber bundle T while the both ends of the carbon fiber bundle T are held by a jig (jig).

As shown in fig. 3, the support layer S1 in which unit groups of several to several tens of carbon fibers CF1 are stacked and arranged in one direction can be formed depending on the number of times of needling. In this case, the thickness of the support layer S1 is several times the diameter of the carbon fiber CF 1.

As an example, the unit group shown in fig. 3 is composed of 3 carbon fibers CF1 stacked vertically.

Since the diameter of one carbon fiber CF1 is

Therefore, the thickness of the support layer S1 formed by vertically stacking 3 carbon fibers CF1 is 3 times the diameter (0.1 to 0.2mm) of the carbon fibers CF1

For another example, if the unit group is composed of 4 carbon fibers CF1 stacked vertically, the thickness of the support layer S1 is 0.4 to 0.8mm that is 4 times the diameter (0.1 to 0.2mm) of the carbon fibers CF 1.

As such, the present invention can easily adjust the thickness of the support layer S1 by adjusting the number of vertically stacked carbon fibers CF 1.

On the other hand, as shown in fig. 4, as the number of needle punching increases, the spread amount of the carbon fiber bundle T gradually increases, and finally, the support layer S2 in which one carbon fiber CF2 is aligned in one direction can be formed. In the above case, the thickness of the support layer S2 is 0.1 to 0.2mm, which is the same as the diameter (0.1 to 0.2mm) of the carbon fiber CF 2. Therefore, the thickness of the support layer S2 can be reduced to the diameter of one carbon fiber CF 2.

Hereinafter, in the description of steps 3S13 to 6S16, a method of forming the flow path P1 on the upper surface of the carbon fiber felt F supported by the support layer S1 in which the unit groups are arranged in one direction shown in fig. 3 and a method of forming the flow path P2 on the upper surface of the carbon fiber felt F supported by the support layer S2 in which one carbon fiber CF2 is arranged in one direction shown in fig. 4 will be alternately described.

Step (3) S13 will be explained.

As shown in fig. 3, a carbon fiber felt F is placed on the support layer S1. The support layer S1 is formed by stacking several to several tens of high-strength carbon fibers, and the unit groups are aligned in one direction, and therefore, it is also possible to support the flow path P1 with a thickness thinner than that of the conventional thermoplastic net, so that the flow path P1 (see fig. 9) does not collapse. Also, the carbon fibers CF1 of the support layer S1 are arranged in a line in the direction of current flow, so that the direction of electrolyte flow can be guided.

On the other hand, as shown in fig. 4, a carbon fiber felt F is placed on the support layer S2. The support layer S2 is formed by stacking one high-strength carbon fiber in one direction, and therefore can support the flow path P2 with a small thickness so that the flow path P2 (see fig. 10) does not collapse. Also, the carbon fibers CF1 of the support layer S2 are arranged in a line in the direction of current flow, so that the direction of electrolyte flow can be guided.

Step (4) S14 will be explained.

In the process of forming the flow path P1 shown in fig. 7 by needling the carbon fiber felt F shown in fig. 3, in order to prevent the carbon fibers CF1 of the support layer S1 arranged in one direction from scattering to the left and right, the carbon fibers CF1 in the support layer S1 are bundled by the carbon fibers CF2 in the carbon fiber felt F. For this reason, in a state where the carbon fiber felt F is placed on the support layer S1, a plurality of portions of the carbon fiber felt F are needled.

Then, as shown in fig. 5, the carbon fibers CF2 in the carbon fiber felt F are held down, and the carbon fibers CF1 in the support layer S1 are bundled so that the carbon fibers CF1 in the support layer S1 do not spread to the left and right.

On the other hand, in the process of forming the flow path P2 shown in fig. 8 by needling the carbon fiber felt F shown in fig. 4, in order to prevent the carbon fibers CF1 of the support layer S2 arranged in one direction from scattering to the left and right, the carbon fibers CF1 in the support layer S2 are bundled by the carbon fibers CF2 in the carbon fiber felt F. For this reason, in a state where the carbon fiber felt F is placed on the support layer S2, a plurality of portions of the carbon fiber felt F are needled.

Then, as shown in fig. 6, the carbon fibers CF2 in the carbon fiber felt F are held down, and the carbon fibers CF1 in the support layer S1 are bundled so that the carbon fibers CF1 in the support layer S1 do not spread to the left and right.

Step (5) S15 will be explained.

As shown in fig. 7, the carbon fiber mat F shown in fig. 3 is needled to form a flow path P1 facing the direction in which the electrolyte flows (the direction of the linear arrow shown in fig. 11) on the upper portion of the carbon fiber mat F. For this purpose, as shown in fig. 7, the needle N repeatedly passes through the carbon fiber mat F and gradually pressure-bonds the portion where the flow path P1 is to be formed. In this manner, the pressure-bonded portion forms the flow path P1. The flow path P1 thus formed allows the electrolyte to flow smoothly along the flow path P1.

On the other hand, as shown in fig. 8, the carbon fiber mat F shown in fig. 4 is needled to form a flow path P2 facing the direction in which the electrolyte solution flows (the direction of the linear arrow shown in fig. 12) on the upper portion of the carbon fiber mat F. For this purpose, as shown in fig. 8, the needle N repeatedly passes through the carbon fiber mat F, and gradually pressure-bonds the portion where the flow path P2 is to be formed. In this manner, the pressure-bonded portion forms the flow path P2. The flow path P2 thus formed allows the electrolyte to flow smoothly along the flow path P2.

On the other hand, by adjusting the number of times of needling and the depth of needling, the degree of pressure contact of the carbon fiber mat F can be adjusted, and the depths of the flow paths P1 and P2 can be adjusted according to the degree of pressure contact of the carbon fiber mat F. In order to adjust the depth of the flow paths P1 and P2 in steps, the number of needle pricks is preferably 10 beats/cm²About 300 beats/cm². More preferably, the number of needle punching is 30 beats/cm²150 dozen/cm²。

On the other hand, if the depth of the flow paths P1 and P2 is too deep, the electrolyte rapidly escapes along the flow path P1 before the electrochemical reaction sufficiently occurs, and if the depth of the flow paths P1 and P2 is too shallow, the electrolyte cannot escape satisfactorily. In view of these problems, the depth of the flow paths P1 and P2 is preferably 1/2 to 1/3 the thickness of the carbon fiber felt F.

As described above, the flow paths P1 and P2 are formed not by cutting the carbon fiber mat F but by pressure-bonding the carbon fiber flow paths (P) by needle punching, and the flow path P1 can be easily formed even in a thin carbon fiber mat F having a thickness of 1mm or less.

On the other hand, the widths w1 and w2 of the flow paths P1 and P2 can be set to be at least 1mm by needle punching, and the maximum width can be arbitrarily set. However, if the widths w1 and w2 of the flow paths P1 and P2 are too short, the electrolyte rapidly escapes along the flow paths before the electrochemical reaction sufficiently occurs, and if the widths w1 and w2 of the flow paths P1 and P2 are too narrow, the electrolyte does not escape well. In view of these problems, it is preferable to set the maximum width of the widths w1 and w2 of the flow paths P1 and P2.

Step (6) S16 will be explained.

As shown in fig. 7, a plurality of other flow paths P1 parallel to the flow path P1 were also formed in the carbon fiber felt F by needling the carbon fiber felt F, and finally the redox flow battery electrode 10 shown in fig. 9 was prepared. The intervals between the flow paths P1 are constant, but may be different. The interval between the flow paths P1 is constant in the present embodiment.

Reference symbol T1 shown in fig. 9 denotes the thickness of the redox flow battery electrode 10, reference symbol T11 denotes the thickness of the carbon fiber felt F, and reference symbol T12 denotes the thickness of the support layer S1. Therefore, T1 is T11+ T12, T11 is in the range of 0.1 to 1mm, and T12 is from 0.3 to 0.6mm (the stacking height of 3 carbon fibers), so that redox flow battery electrode 10 can be made thin with a thickness of 0.4 mm.

As shown in fig. 11, redox flow battery electrode 10 is cut in a set size and provided to unit cell 1.

The unit cell 1 includes an ion exchange membrane 11, a separator 12, a bipolar plate 13, and a redox flow battery electrode 10. The straight arrows shown in fig. 11 indicate the direction of the electrolyte flow. A plurality of unit cells 1 are arranged and connected to prepare a redox flow battery stack, and the stack is connected to an electrolyte tank to prepare a redox flow battery.

Since the redox flow battery electrode 10 is thin, more electricity can be produced by stacking more unit cells in the same space.

On the other hand, as shown in fig. 8, a plurality of other flow paths P2 parallel to the flow path P2 are formed in the carbon fiber felt F by needling the carbon fiber felt F, and finally the redox flow battery electrode 20 shown in fig. 10 is prepared. The intervals between the flow paths P2 are constant, but may be different. The interval between the flow paths P2 is constant in the present embodiment.

Reference symbol T1 shown in fig. 10 denotes the thickness of the redox flow battery electrode 20, reference symbol T11 denotes the thickness of the carbon fiber felt F, and reference symbol T12 denotes the thickness of the support layer S2. Therefore, T1 is T11+ T12, T11 is in the range of 0.1 to 1mm, and T12 is from 0.1 to 0.2mm (the diameter of 1 carbon fiber), so that the redox flow battery electrode 10 can be manufactured to be ultra-thin with a thickness of at least 0.2 mm.

As shown in fig. 12, the redox flow battery electrode 20 is cut in a set size and provided to the unit cell 2.

The unit cell 2 includes an ion exchange membrane 11, a separator 12, a bipolar plate 13, and a redox flow battery electrode 20. The straight arrows shown in fig. 12 indicate the direction of the electrolyte flow. A plurality of unit cells 2 are arranged and connected to prepare a redox flow battery stack, and the redox flow battery is prepared by connecting the stack to an electrolyte tank.

Since redox flow battery electrode 20 is ultra-thin, more electricity can be produced by stacking more cells in the same space.