KR20240006931A - Zinc-bromine battery cell and zinc-bromine battery module comprising the same - Google Patents

Abstract

The present invention relates to a zinc-bromine battery cell and a zinc-bromine battery module containing the same. Specifically, it has a new structure that can suppress the crossover phenomenon of bromine ions, thereby achieving high coulombic efficiency, voltage efficiency, and energy efficiency. It relates to a high-performance zinc-bromine battery cell capable of implementing and a zinc-bromine battery module including the same.

Description

Zinc-bromine battery cell and zinc-bromine battery module comprising the same {Zinc-bromine battery cell and zinc-bromine battery module comprising the same}

The present invention relates to a zinc-bromine battery cell and a zinc-bromine battery module containing the same.

As existing power generation systems, such as thermal power generation that uses fossil fuels and causes large amounts of greenhouse gases and environmental pollution problems, and nuclear power generation that has problems with the stability of the facility itself and waste disposal, are revealing various limitations, renewable energy along with renewable energy Research and development on energy storage systems (ESS) are actively underway to respond to the volatility of

Zinc-bromine batteries, one of these batteries for energy storage systems, are attracting attention due to their advantages such as price competitiveness, non-ignition characteristics based on aqueous electrolyte, and excellent lifespan characteristics. In order to secure the capacity of a zinc-bromine battery, it is important to secure the reversibility of zinc metal and bromine-based ions, which are electrode active materials. However, due to the crossover phenomenon between electrodes due to diffusion of bromine ions and precipitation of zinc metal, bromine ions react with zinc metal deposits, causing self-discharge, thereby deteriorating battery performance.

In detail, in the case of a conventional vertical cell structure in which a porous ion exchange membrane is installed between both electrodes, there is a disadvantage in that the diffusion of bromine ions and the detachment of zinc metal precipitates occur through the porous ion exchange membrane, thereby deteriorating battery performance. .

Therefore, there is a need to develop a high-performance zinc-bromine battery that suppresses the above-mentioned crossover phenomenon and exhibits high coulombic efficiency, voltage efficiency, and energy efficiency.

Korean Patent Publication No. 10-2019-0005393

One object of the present invention is to provide a zinc-bromine battery cell with a new structure that can suppress the crossover phenomenon of bromine-based ions that causes a decrease in the performance of zinc-bromine batteries and a zinc-bromine battery module including the same. .

Another object of the present invention is to provide a high-performance zinc-bromine battery cell that suppresses crossover phenomenon and exhibits high coulombic efficiency, voltage efficiency, and energy efficiency, and a zinc-bromine battery module including the same.

Another object of the present invention is to provide a zinc-bromine battery cell that can be easily manufactured in a large area and realize high capacity and high energy density, and a zinc-bromine battery module including the same.

In order to solve the problem described above, one embodiment includes a cathode, an anode, an electrolyte, and a barrier film disposed between the cathode and the anode, and the cathode and the anode are arranged side by side in a horizontal direction. A bromine battery cell is provided.

The thickness directions of one surface of the cathode and anode facing the electrolyte may not oppose each other.

The thickness directions of one surface of the cathode and anode facing the electrolyte may be parallel to each other.

One side of the cathode and anode facing the electrolyte may be located on the same plane.

One surface of the cathode and anode may be positioned below the electrolyte in the direction of gravity.

The zinc-bromine battery cell further includes a bipolar plate, and the bipolar plate may include a first region in contact with a side of the cathode or anode and a second region in contact with the electrolyte.

The zinc-bromine battery may be a non-flow type zinc-bromine battery.

It may be that bromine-based ions contained in the electrolyte do not crossover to the cathode.

The cathode and anode may include a porous carbon body.

The barrier film may be a non-porous film.

The height of the blocking film may be higher than the thickness of the anode and cathode.

The height of the blocking film may be higher than the width of the anode and cathode.

A conductive adhesive may be applied to the surfaces of the anode and cathode.

Another embodiment provides a zinc-bromine battery module that includes a plurality of the above-described zinc-bromine battery cells as unit cells, and the plurality of zinc-bromine battery cells are arranged side by side in the horizontal direction.

It may further include a bipolar plate interposed between the adjacent unit cells.

The zinc-bromine battery cell according to the present invention can achieve high coulombic efficiency, voltage efficiency, and energy efficiency by having a new structure that can suppress the crossover phenomenon of bromine-based ions.

In addition, the present invention can provide a zinc-bromine battery module with high capacity and high energy density because it is easy to manufacture in a large area by extending the length of the electrode and stacking the cells due to the nature of the cell structure.

Figure 1 is a schematic diagram of the structure and operating mechanism of a zinc-bromine battery cell according to an embodiment.
Figure 2 is a schematic diagram of a battery module including a zinc-bromine battery cell according to an embodiment.
Figure 3 is a diagram showing the stacked structure of a zinc-bromine battery cell according to an embodiment, and Figure 4 is a schematic diagram showing the assembly process of a zinc-bromine battery cell according to an embodiment.
Figure 5 is a photograph of a zinc-bromine battery cell according to one embodiment.
Figure 6 is a graph showing coulombic efficiency and energy efficiency according to the number of cycles of Examples 1 to 3 and Comparative Example 1, and Figures 7 (a) and (b) are the charge-discharge of the first and tenth cycles, respectively. It shows a curve.
Figure 8 is a diagram showing a method of reducing the width of the electrode to lower resistance.
Figure 9 is a graph showing coulombic efficiency and energy efficiency according to the number of cycles of Example 1, Example 4, and Comparative Example 1, and Figure 10 shows the charge-discharge curves of the first and tenth cycles.

The embodiments described in this specification may be modified into various other forms, and the technology according to one embodiment is not limited to the embodiments described below. Additionally, the embodiment of one embodiment is provided to more completely explain the present disclosure to those skilled in the art.

Additionally, as used in the specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to also include the plural forms, unless the context clearly dictates otherwise.

In addition, the numerical range used in this specification includes the lower limit and upper limit and all values within the range, increments logically derived from the shape and width of the defined range, all double-defined values, and the upper limit of the numerical range defined in different forms. and all possible combinations of the lower bounds. Unless otherwise specified in the specification of the present invention, values outside the numerical range that may occur due to experimental error or rounding of values are also included in the defined numerical range.

Furthermore, “including” a certain element throughout the specification means that other elements may be further included, rather than excluding other elements, unless specifically stated to the contrary.

The present inventor believes that although the conventional vertical cell structure, in which the anode is placed at the bottom in the direction of gravity and the cathode is placed at the top, is advantageous in terms of the movement distance of ions contained in the electrolyte, a crossover phenomenon between electrodes is bound to occur, thereby improving battery performance. It was recognized that this was the cause of the decline. Accordingly, as a result of repeated research to suppress the crossover phenomenon, the diffusion of bromine ions can be blocked through a new structure in which a blocking film is placed between the cathode and anode arranged side by side in the horizontal direction, and thus zinc-bromine battery cells. The present invention was completed by confirming that the performance of the zinc-bromine battery module to which this was applied was improved.

The zinc-bromine battery cell according to the present invention includes a cathode, an anode, an electrolyte, and a blocking film disposed between the cathode and the anode, and the cathode and the anode are arranged side by side in the horizontal direction.

The zinc-bromine battery cell according to one embodiment includes a blocking film between the anode and the cathode arranged side by side in the horizontal direction, thereby suppressing the crossover phenomenon of bromine-based ions, which occurs when bromine-based ions react with zinc metal precipitates. Self-discharge problems can be prevented. Accordingly, battery performance can be improved by ensuring the reversibility of zinc metal and bromine-based ions, which are electrode active materials. In particular, coulombic efficiency, which is an important indicator of battery performance, can be improved.

The bromine-based ion may be one or more selected from bromine ions (Br ^- ) and polybromine ions. Specifically, the polybromide ion may be one or more selected from Br ^2- , Br ^3- , Br ^5- , Br ^7- , and Br ^9- , but is not limited thereto.

In one embodiment, the thickness directions of one surface of the cathode and the anode facing the electrolyte may not face each other.

Figure 1 is a schematic diagram of the structure and operating mechanism of a zinc-bromine battery cell according to an embodiment.

Hereinafter, a zinc-bromine battery cell according to an embodiment of the present invention will be described in detail with reference to the attached drawings. The attached drawings are provided as examples in order to sufficiently convey the technical idea of the present invention to technicians, and the present invention is not limited to the drawings presented below and may be embodied in many other forms.

Referring to FIG. 1, the zinc-bromine battery cell according to one embodiment is different from a conventional cell having a structure in which the thickness directions of one side of the cathode and anode facing the electrolyte are opposed to each other in order to shorten the moving distance of the electrolyte. By having a structure that does not cause bromine ions to suppress the crossover phenomenon and prevent contact between bromine ions and zinc metal precipitates, battery performance can be improved by securing the reversibility of zinc metal and bromine ions, which are electrode active materials. You can.

In one embodiment, the thickness direction of one surface of the cathode and anode facing the electrolyte may be parallel to each other, thereby more effectively suppressing the crossover phenomenon of bromine ions and separating bromine ions from zinc metal precipitates. Contact can be blocked.

In one embodiment, one side of the cathode facing the electrolyte may be located higher or lower than one side of the anode facing the electrolyte, or one side of the cathode and the anode facing the electrolyte may be located on the same plane. there is. As one side of the cathode and anode facing the electrolyte are located on the same plane, the crossover phenomenon of bromine-based ions can be further suppressed, thereby realizing high coulombic efficiency, voltage efficiency, and energy efficiency.

In one embodiment, one side of the cathode and the anode may be positioned below the electrolyte in the direction of gravity. Referring to FIG. 1, bromine-based ions and zinc generated from the anode and cathode, respectively, after operation of the cell. Metal precipitates can sink in the direction of gravity, suppressing the crossover phenomenon of bromine ions.

The zinc-bromine battery cell according to one embodiment may further include a bipolar plate, and the bipolar plate may include a first region in contact with a side of the cathode or anode and a second region in contact with the electrolyte. .

Specifically, as one surface of the cathode and the anode is located below the electrolyte in the direction of gravity, the first area may be located below the second area.

In the zinc-bromine battery cell according to one embodiment, the cathode, anode, electrolyte, and barrier film have the structures described above, so that bromine-based ions contained in the electrolyte do not crossover to the cathode.

In one embodiment, the zinc-bromine battery may be a non-flow type zinc-bromine battery. At this time, the non-flow type battery refers to a battery that does not use an electrolyte storage tank and a pumping system. Unlike the flow type zinc-bromine battery, the non-flow type battery does not have energy loss during the electrolyte pumping process. No problem. When the above-described zinc-bromine battery cell is introduced into such a non-flow type zinc-bromine battery, the crossover of bromine ions can be more alleviated than that of a flow-type zinc-bromine battery, thereby further improving battery performance.

In one embodiment, the cathode and anode may include a porous carbon body. The porous carbon body may include macropores, mesopores, micropores, or a combination thereof, and preferably includes macropores. Additionally, the porous carbon body may have a specific surface area of 10 m ² /g to 1000 m ² /g, but is not limited thereto.

Specifically, the porous carbon body is at least one of carbon felt, carbon paper, carbon cloth, natural graphite, artificial graphite, expanded graphite, carbon fiber, non-graphitizable carbon, carbon black, carbon nanotubes, fullerene, and activated carbon. It may include one, preferably at least one of carbon felt, carbon paper, and carbon cloth, and more preferably may include carbon felt.

The porous carbon body may be a heat-treated porous carbon body, and the heat-treated porous carbon body can be effectively impregnated with electrolyte, thereby improving battery performance. The heat treatment may be performed at 400°C to 600°C, and more specifically, may be performed at 450°C to 600°C or 450°C to 550°C, but is not particularly limited thereto.

In one embodiment, the barrier film is not limited as long as bromine ions and zinc metal precipitates do not pass through the film, and in particular, it may be a non-porous film. More specifically, it may be a non-porous film formed by extrusion using a blown film technique or a cast film method. The barrier film may be a non-porous polyethylene film or a non-porous polypropylene film, and a specific example of the non-porous film may be a non-stretched polypropylene (cast polypylene, CPP) film, but is not limited thereto.

The thickness of the blocking film is not particularly limited, but may be 10 ㎛ to 100 ㎛ or 10 ㎛ to 50 ㎛, and if the above range is satisfied, the movement distance of ions during battery operation can be minimized.

In one embodiment, the height of the blocking film may be higher than the thickness of the anode and cathode, and as a result, bromine-based ions and zinc metal precipitates do not move between the electrodes, thereby preventing self-discharge that is fatal to the performance of the battery. .

The thickness of the anode and cathode and the height of the blocking film may be appropriately changed depending on the purpose of use of the battery cell, operating conditions, etc., and are not particularly limited thereto, but for example, the thickness of the anode (or cathode) and the The ratio of the height of the blocking film may be 1:2 to 3, 1:2 to 2.8, or 1:2 to 2.5, and if the above range is satisfied, the crossover phenomenon can be suppressed and the movement distance of ions can be minimized, thereby improving battery performance. It can be improved more than this.

In one embodiment, the height of the blocking film may be higher than the width of the anode and the cathode, which is preferable because the crossover phenomenon can be effectively suppressed while minimizing the moving distance of the electrolyte.

Of course, the width of the anode and cathode and the height of the blocking film may be appropriately changed depending on the purpose of use of the battery cell, operating conditions, etc., and for example, the ratio of the width of the anode (or cathode) and the height of the blocking film is 1: It may be 1 to 3, 1:1.3 to 3 or 1:1.3 to 2, but is not particularly limited thereto.

In one embodiment, a conductive adhesive may be applied to the surfaces of the anode and the cathode, which improves the contact force between the electrode and the bipolar plate to prevent peeling at the electrode interface and also reduces electrical resistance, thereby providing higher performance zinc. -You can obtain bromine battery cells. The conductive adhesive may be carbon paste, solder paste, conductive polymer, silver-epoxy adhesive, etc., but is not limited thereto.

The zinc-bromine battery module according to the present invention includes a plurality of the above-described zinc-bromine battery cells as unit cells, and the plurality of zinc-bromine battery cells are arranged side by side in the horizontal direction.

Referring to FIG. 2, in the zinc-bromine battery module according to the present invention, the cathode of one unit cell may be disposed adjacent to the anode of an adjacent unit cell, and a bipolar plate interposed between the adjacent unit cells may be used. More may be included.

The zinc-bromine battery module includes the above-described zinc-bromine battery cells arranged side by side in the horizontal direction, thereby suppressing the crossover phenomenon and having high coulombic efficiency, voltage efficiency, and energy efficiency.

In addition, as can be seen in Figure 2, by stacking the cells in the horizontal direction and extending the length of the electrodes, it is easy to manufacture a large-area module, thereby providing a zinc-bromine battery module with high capacity and high energy density.

In one embodiment, the thickness direction of one surface of the negative electrode facing the electrolyte contained in one unit cell may not be opposite to the thickness direction of one surface of the negative electrode facing the electrolyte contained in an adjacent unit cell, More specifically, it may be parallel. Additionally, one side of the cathode facing the electrolyte included in one unit cell and one side of the cathode facing the electrolyte included in an adjacent unit cell may be located on the same plane. By arranging a plurality of unit cells in this way, it is possible to provide a high-performance zinc-bromine battery module by suppressing the crossover phenomenon of bromine-based ions.

Hereinafter, examples and experimental examples will be described in detail below. However, the examples and experimental examples described below are only illustrative of some, and the technology described in this specification is not limited thereto.

<Example 1>

After heat-treating the carbon felt at 520°C for 9 hours using a box furnace, the heat-treated carbon felt was cut to a size of 19 mm prepared. A barrier film was prepared by cutting a non-stretched polypropylene (cast polypylene, CPP) film about 40 ㎛ thick enough to cover the electrode chamber.

Figure 3 is a diagram showing the stacked structure of a zinc-bromine battery cell according to an embodiment, and Figure 4 is a schematic diagram showing the assembly process of a zinc-bromine battery cell according to an embodiment, as shown in Figures 3 and 4. The cathode and anode are placed in the chamber so that each 19 mm x 10 mm side faces upward and downward. Thereafter, the blocking film is placed on the chamber so that the height of the blocking film from the bottom of the carbon felt electrode in one chamber is 11 mm, and then fixed using tape. Then, a zinc-bromine battery cell was manufactured by assembling the bipolar plate, copper current collector, and end plate as shown in Figure 3.

<Example 2>

A zinc-bromine battery cell was manufactured in the same manner as Example 1, except that the height of the blocking film was placed at 10 mm instead of 11 mm in Example 1.

<Example 3>

A zinc-bromine battery cell was manufactured in the same manner as Example 1, except that the height of the barrier film was placed at 12 mm instead of 11 mm in Example 1.

<Example 4>

In Example 1, the width of the carbon felt used for the anode and cathode was 7 mm instead of the 10 mm width, and the step of applying carbon paste to the anode and cathode before assembling the anode and cathode in the chamber. A zinc-bromine battery cell was manufactured in the same manner as Example 1, except that it further included.

<Comparative Example 1>

A zinc-bromine battery cell was manufactured in the same manner as Example 1, except that the cPP film was not used.

<Experimental Example 1> Performance evaluation according to the height of cPP film

In order to confirm the effect of the height of the cPP film on the performance of the battery, the performance of the cells of Examples 1 to 3 and Comparative Example 1 were evaluated, and the results are shown in Figures 6 and 7.

In the case of the example, an aqueous electrolyte of 2.5M ZnBr ₂ was injected into the manufactured cell through the electrolyte injection port, aged for 12 hours, and bubbles were removed using a vacuum chamber, and then the anode and cathode were aligned in the horizontal direction as shown in FIG. 1. The performance was evaluated by operating in a side-by-side state. In the case of the comparative example, after electrolyte injection, aging, and bubble removal in the same manner, the performance was evaluated by operating with the anode placed at the bottom in the direction of gravity and the cathode placed at the top. was evaluated.

Figure 5 is a photograph of a zinc-bromine battery cell according to one embodiment, and the red dotted line shown in Figure 5 indicates the area where the carbon felt electrode is located, and the green dotted line indicates the area where the cPP film is located.

Figure 6 is a graph showing coulombic efficiency and energy efficiency according to the number of cycles of Examples 1 to 3 and Comparative Example 1, and Figures 7 (a) and (b) are the charge-discharge of the first and tenth cycles, respectively. It represents a curve.

The blocking film (cPP film) placed between both electrodes is related to the movement distance of zinc ions and whether or not the crossover phenomenon of bromine ions is suppressed. In detail, the higher the height of the blocking film from the bottom of the carbon felt electrode, the more effectively the crossover phenomenon of bromine ions can be suppressed. However, at the same time, the resistance due to the increased movement distance of zinc ions increases, which may actually reduce energy efficiency. there is.

Referring to Figures 6 and 7, in the case of Example 1, the coulombic efficiency was 96.7%, which was an improvement of 4.1% compared to Comparative Example 1, and through this, the zinc-bromine battery cells according to one embodiment were arranged side by side in the horizontal direction. It was confirmed that by placing a blocking film between electrodes, the crossover phenomenon can be blocked, and the coulombic efficiency of the zinc-bromine battery cell, which is an important indicator of battery performance, can be improved.

<Experimental Example 2> Performance evaluation according to electrode width and adhesive

As seen in Experimental Example 1, improved coulombic efficiency was shown, but low energy efficiency became a problem. This was due to the effect of overvoltage (resistance) caused by an increase in the movement distance of ions. To reduce this, the width of the electrode was changed as shown in Figure 8. In order to reduce and at the same time increase the contact force between the carbon felt and the bipolar plate, the performance of the cell of Example 4 using the anode and cathode coated with carbon paste was further evaluated. The performance evaluation results according to Example 1, Example 4, and Comparative Example 1 are shown in Figures 9 and 10.

Figure 9 is a graph showing coulombic efficiency and energy efficiency according to the number of cycles of Example 1, Example 4, and Comparative Example 1, and Figure 10 shows the charge-discharge curves of the first and tenth cycles.

Referring to Figures 9 and 10, in the case of Example 4, the coulombic efficiency was 95.4%, which was improved by about 2.7% compared to Comparative Example 1, and the voltage efficiency and energy efficiency were 78.3% and 74.7%, respectively, which were improved compared to Example 1. The energy efficiency of Example 5 is similar to Comparative Example 1, and through this, the zinc-bromine battery cell according to one embodiment can not only improve coulombic efficiency, which is an important indicator of battery performance, but also improves coulombic efficiency, which is an important indicator of battery performance. It was confirmed that equivalent energy efficiency could be achieved.

As described above, the present disclosure has been described in the present specification using specific details and limited examples, but these are provided only to facilitate a more general understanding of the present disclosure, and the present disclosure is not limited to the above embodiments. Anyone skilled in the art can make various modifications and variations from this description.

Therefore, the idea described in this specification should not be limited to the described embodiments, and all claims that are equivalent or equivalent to this claim as well as the later-described claims fall within the scope of the idea described in this specification. They will say they do it.

Claims (15)

It includes a cathode, an anode, an electrolyte, and a barrier film disposed between the cathode and the anode,
A zinc-bromine battery cell, wherein the cathode and the anode are arranged side by side in a horizontal direction. According to paragraph 1,
A zinc-bromine battery cell in which the thickness directions of one surface of the cathode and anode facing the electrolyte do not oppose each other. According to paragraph 1,
A zinc-bromine battery cell in which the thickness directions of one surface of the cathode and anode facing the electrolyte are parallel to each other. According to paragraph 1,
A zinc-bromine battery cell in which one side of the cathode and anode facing the electrolyte are located on the same plane. According to paragraph 1,
A zinc-bromine battery cell, wherein one side of the cathode and anode is located below the electrolyte in the direction of gravity. According to paragraph 1,
Further comprising a bipolar plate,
The bipolar plate includes a first region in contact with a side of the cathode or anode and a second region in contact with an electrolyte. According to paragraph 1,
The zinc-bromine battery is a zinc-bromine battery cell, which is a non-flow type zinc-bromine battery. According to paragraph 1,
A zinc-bromine battery cell in which bromine-based ions contained in the electrolyte do not crossover to the cathode. According to paragraph 1,
A zinc-bromine battery cell, wherein the cathode and the anode include a porous carbon body. According to paragraph 1,
A zinc-bromine battery cell wherein the barrier film is a non-porous film. According to paragraph 1,
A zinc-bromine battery cell in which the height of the barrier film is higher than the thickness of the anode and cathode. According to paragraph 1,
A zinc-bromine battery cell, wherein the height of the barrier film is higher than the width of the anode and cathode. According to paragraph 1,
A zinc-bromine battery cell in which a conductive adhesive is applied to the surfaces of the anode and the cathode. Comprising a plurality of zinc-bromine battery cells according to any one of claims 1 to 13 as unit cells,
A zinc-bromine battery module in which the plurality of zinc-bromine battery cells are arranged side by side in a horizontal direction. According to clause 14,
A zinc-bromine battery module further comprising a bipolar plate interposed between the adjacent unit cells.