CN110400955B

CN110400955B - Redox flow battery

Info

Publication number: CN110400955B
Application number: CN201810383325.0A
Authority: CN
Inventors: 金富基; 金箕贤; 赵范熙; 崔淡潭
Original assignee: Standard Energy Co ltd
Current assignee: Standard Energy Co ltd
Priority date: 2018-04-25
Filing date: 2018-04-25
Publication date: 2022-07-12
Anticipated expiration: 2038-04-25
Also published as: CN110400955A

Abstract

The redox flow battery according to the present invention includes a battery cell or a stack and an electrolyte tank in a battery module, and a device instead of a pump for transporting an electrolyte to the battery cell or the stack is applied to each battery module, thereby enabling the generation of shunt current to be dramatically reduced. Further, since the electrolyte tank is provided for each battery module, the transfer path of the electrolyte can be drastically reduced, and a fluid control unit using pressure is provided for each module instead of the pump in order to transfer the electrolyte, so that the power required for driving the pump can be saved and the efficiency of the battery can be improved.

Description

Redox flow battery

Technical Field

The present invention relates to a redox flow battery, and more particularly, to a redox flow battery characterized by a combination of a plurality of battery modules each including an electrolyte tank for storing an anolyte and a catholyte and a fluid control unit for transferring an electrolyte from the electrolyte tank to a battery cell, thereby reducing a reaction time, improving efficiency, and suppressing generation of a shunt current (shunt current).

Background

In recent years, renewable energy sources such as solar energy and wind energy have been favored as a method for suppressing greenhouse gas emissions, which are major causes of global warming, and various studies have been made for the practical popularization thereof. However, renewable energy is greatly affected by the site selection environment and natural conditions. Further, since the output of the renewable energy varies greatly, there is a disadvantage that the energy cannot be supplied continuously and uniformly. Therefore, in order to use renewable energy for domestic use or commercial use, a system has been introduced in which energy is stored when the output is high and the stored energy is used when the output is low.

As such an energy storage system, a large-capacity secondary battery is used, and as an example, a large-capacity secondary battery storage system is introduced into a large-scale solar power generation and wind power generation community. As secondary batteries used for the large-capacity power storage, there are lead storage batteries, sodium sulfur (NaS) batteries, Redox Flow Batteries (RFB), and the like.

The lead storage battery is widely commercially used compared to other batteries, but has disadvantages such as low efficiency and maintenance costs due to periodic replacement and a problem of disposal of industrial waste generated when the battery is replaced. In the case of NaS batteries, there is an advantage in that energy efficiency is high, but there is a disadvantage in that operation at a high temperature of 300 ℃ or higher is performed. Since a redox flow battery has a feature that it can operate at normal temperature and can independently design a capacity and an output, a large amount of research has been conducted in recent years as a large-capacity secondary battery.

Similar to a fuel cell, a redox flow battery has a function of a Secondary battery (Secondary battery) capable of charging and discharging electric energy by configuring a Stack (Stack) by arranging a separation membrane (membrane), an electrode, and a separator (Bipolar plate) in Series (Series). In a redox flow battery, an anolyte (Electrolyte) and a catholyte supplied from an anode and a catholyte storage tank are ion-exchanged while circulating on both sides of a separation membrane, and electrons are transferred in the process, thereby performing charge and discharge. It is known that such a redox flow battery has a longer life than a conventional secondary battery and can be produced in a large-medium-sized system of kW to MW, and therefore is most suitable for ESS (Energy storage system).

However, the redox flow battery is a configuration in which tanks storing an anolyte and a catholyte are independently arranged with a certain space therebetween (for example, a configuration in which an electrolyte tank is arranged with a certain space therebetween on both sides or the lower side of a stack), and has a disadvantage in that the electrolyte circulation pipe connecting the stack and the electrolyte tank is relatively large in comparison with other lead storage batteries, lithium ion batteries, and lithium-sulfur batteries as power storage devices, on the basis of an approximate power storage capacity in terms of the volume of the entire system.

Further, since it is necessary to provide a plurality of electrolyte circulation pipes connected to the stack, the pump, and the electrolyte tank, a pump capacity equal to or higher than a certain reference is required to constantly supply the electrolyte to each stack, and the longer the length of the electrolyte circulation pipe is, the larger the required capacity of the pump becomes, and there is a problem that the size of the pump and the manufacturing cost of the battery increase, and the power consumption increases in accordance with the increase in the pump capacity, and the overall battery efficiency decreases.

In addition, a general battery is required to have a high operation responsiveness in performing a charge/discharge operation. However, in the case of a redox flow battery, when the battery is started up for charging and discharging in a stationary state, it takes time until the electrolyte is circulated into the stack by a pump, and the responsiveness is degraded according to the time required, and a plurality of chemical-resistant pipes for connecting the battery cells, the stack, and the pump are required, which causes a problem of an increase in cost.

Here, a general redox flow battery supplies an electrolyte to each battery cell through a manifold. However, the electrolyte filled in the manifold functions as an electrical path connecting the battery cells, and thus can serve as a path through which electrons move, and a shunt current (shunt current) is generated through such a path, so that a part of energy is lost by the shunt current during charge and discharge, which causes a reduction in efficiency, damage to components, and non-uniformity in performance of the battery cells. Conventionally, in order to reduce such a shunt current, a method of reducing the cross-sectional area by increasing the length of the manifold has been mainly adopted, but this increases the flow resistance of the fluid and causes a pumping loss, and therefore, it is required to establish a countermeasure against this.

Prior art documents

Patent document

Patent document 1: korean laid-open patent No. 10-2011-0119775 (2011 11 months 02 days)

Patent document 2: korean registered patent No. 10-1176126 (2011 year, 10 months, 26 days)

Disclosure of Invention

Problems to be solved by the invention

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a redox flow battery in which an electrolyte tank for storing an electrolyte is provided for each battery cell or each stack (stack) unit in which a plurality of battery cells are stacked, or an alternative pump for transporting an electrolyte to a battery cell or a stack is applied to a system in which an electrolyte tank is shared by a plurality of battery cells, whereby a drop in battery efficiency due to the provision of a plurality of pumps can be overcome, and generation of a shunt current can be suppressed.

Means for solving the problems

The present invention relates to a redox flow battery.

One embodiment of the present invention relates to a redox flow battery including one or more electrically connected battery modules each including a battery cell, an electrolyte tank, an electrolyte flow path, and a fluid control unit for transmitting externally generated pressure to the electrolyte flow path, the battery modules each independently circulating an electrolyte internally and performing charge and discharge.

The present invention is characterized in that the battery module includes:

one or more than two battery units, including a separation film arranged between the anode and the cathode and a separator laminated on the outer side surfaces of the anode and the cathode;

a pair of electrolyte tanks disposed inside the battery module and supplying an anolyte or a catholyte to the anode or the cathode;

an electrolyte flow path which connects the battery cell and the electrolyte tank and transfers the electrolyte; and

and one or more fluid control units provided in the electrolyte flow path, and configured to control the flow of the electrolyte by transmitting pressure transmitted from outside the battery module to the electrolyte flow path.

In the present invention, the fluid control portion may include:

one or more check valves disposed at a portion of the electrolyte flow path to guide the flow of the electrolyte in one direction; and

a fluid transport pipe communicating with the electrolyte flow path adjacent to the check valve and directly transmitting pressure transmitted from outside of the battery module to the electrolyte flow path, or,

the fluid control unit may be provided at one end of the electrolyte flow path, and include:

a control section case located in the electrolyte tank;

a fluid transport pipe for directly transmitting pressure transmitted from the outside of the battery module to the control unit case; and

and one or more check valves provided on a side surface of the control unit case, for guiding the electrolyte from the electrolyte tank to the control unit case and guiding the electrolyte from the control unit case to the electrolyte flow path.

In the present invention, the battery module may include two or more fluid control units, and when the battery module includes two fluid control units, a positive pressure cycle of one of the fluid control units may partially overlap a positive pressure cycle of the other of the fluid control units with respect to a pressure supply cycle of the fluid control unit. For this purpose, the fluid control unit may further include one or more pressure control valves.

In the present invention, the fluid transport pipe may further include one or more fluid filters, or may further include one or more electrolyte inflow prevention devices selected from a valve, an isolation valve, a check valve, and a float valve inside the fluid transport pipe.

Effects of the invention

The redox flow battery according to the present invention is provided with a cell or a stack and an electrolyte tank in a battery module, and is applied to each battery module by providing a fluid control unit using pressure instead of a pump for each module in order to feed an electrolyte, thereby being capable of dramatically reducing or eliminating the occurrence of shunt current.

In addition, when the electrolyte tank is provided for each battery module, the path for transferring the electrolyte can be dramatically shortened, power required for driving the pump can be saved, and the efficiency of the battery can be improved.

Drawings

Fig. 1 illustrates a redox flow battery incorporating a plurality of battery modules according to an embodiment of the present invention.

Fig. 2 illustrates the internal configuration of a battery module according to an embodiment of the present invention.

Fig. 3 illustrates the internal construction of a battery module according to another embodiment of the present invention.

Fig. 4 illustrates an example of the check valve in the present invention.

Fig. 5A to 5C illustrate other examples of the check valve in the present invention.

Fig. 6 and 7 illustrate a redox flow battery provided with two fluid control portions.

Fig. 8A to 8C illustrate pressure cycles of the respective fluid control portions in the case where two fluid control portions are provided.

Fig. 9A and 9B illustrate a fluid control portion further provided with a pressure control valve.

Fig. 10A and 10B illustrate an example of a pressure control valve.

Fig. 11 and 12 show a fluid control unit further including an electrolyte inflow prevention device and a fluid filter.

Fig. 13 illustrates a redox flow battery incorporating a plurality of battery modules according to an embodiment of the present invention.

Description of the reference numerals

1: stack, 10: battery module, 100: battery cell, 110: anode, 120: cathode, 130: separation membrane, 140: partition plate, 150: a housing, 200: electrolyte tank, 210: anolyte tank, 220: catholyte tank, 300: fluid control portion, 310: check valve, 311: first check valve, 312: second check valve, 320: control section housing, 330: fluid transport pipe, 340: pressure control valve, 350: electrolyte inflow preventer, 360: fluid filter, 400: electrolyte flow path, 500: pressure generator, 600: and a module connecting portion.

Detailed Description

The redox flow battery according to the present invention will be described in detail below with reference to specific examples. The following specific examples are provided as examples to fully convey the concept of the present invention to those skilled in the art.

Therefore, the present invention is not limited to the specific examples described below, but can be embodied in other forms.

In this case, the technical terms and scientific terms used have meanings that are generally understood by those skilled in the art unless otherwise defined, and descriptions of well-known functions and structures that may unnecessarily obscure the gist of the present invention are omitted in the following description.

In addition, the drawings described below are provided as examples in order to fully convey the concept of the present invention to those skilled in the art. Therefore, the present invention is not limited to the drawings shown below, and may be embodied in other forms. Note that, throughout the specification, the same reference numerals denote the same constituent elements.

Furthermore, as used in the specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as long as they are not specifically referred to in the context of the article.

In the description of the components of the present invention, it is possible to use the terms first, second, A, B, (a), (b), and the like. Such terms are only used to distinguish one component from another component, and the nature, order, sequence, or the like of the respective components are not limited by the terms. When a certain component is described as being "connected", "coupled" or "connected" to another component, it is to be understood that the component may be directly connected or connected to the other component, but other components may also be "connected", "coupled" or "connected" between the components.

In the present invention, the term "battery cell" is the smallest unit for performing charge and discharge by an electrolyte, and is composed of a separation membrane, a separator, and the like, which perform ion exchange.

In the present invention, the term "stack" means that a plurality of battery cells are stacked or constituted.

The inventors of the present invention have made intensive studies to solve the following problems as disadvantages of a redox flow battery, the problems being: physical problems such as an increase in the length of the electrolyte circulation tube and a resulting increase in the volume of the battery itself, the need for high-performance pumps, or an increase in the number of pumps itself; and problems of increased pump size and unit cost of battery manufacturing corresponding to electrolyte transport, decreased responsiveness, and suction loss, as a result, the distance of electrolyte movement is significantly reduced by combining a plurality of battery modules including battery cells or stacked bodies and a fluid control unit, and problems of decreased responsiveness, suction loss, and the like are solved by providing a fluid controller for each battery module instead of a pump, thereby completing the present invention.

As shown in fig. 1 or 13, the redox flow battery according to the present invention includes one or more battery modules 10 electrically connected to each other, and each battery module 10 includes a battery cell 100, an electrolyte tank 200, an electrolyte flow path 400, and a fluid control unit 300 that transmits pressure generated externally to the electrolyte flow path, and is configured to independently circulate and charge and discharge the electrolyte.

As described in more detail with reference to fig. 2, the present invention may include: one or more than two battery units 100, which include a pair of electrodes divided into an anode 110 and a cathode 120, a separator 130 disposed between the electrodes, and a separator 140 laminated on the outer surface of the electrodes; a pair of electrolyte tanks 200 disposed inside the battery module and supplying an anolyte or a catholyte to the anode or the cathode; an electrolyte flow path 400 connecting the battery cell and the electrolyte tank and transferring the electrolyte; and one or more fluid control units 300 disposed in the electrolyte flow path, and configured to control the flow of the electrolyte by transmitting pressure transmitted from the outside of the battery module to the electrolyte flow path.

In the present invention, the battery cell is described and illustrated with reference to a general redox flow battery, and electrodes, separators, and the like may be omitted in some cases.

On the other hand, in the present specification, since the structure and function of the end plate, the electrolyte tank 200, the pump, and the like are well known to those skilled in the art, they will not be described in detail in the present specification.

Hereinafter, each constituent element will be described in more detail with reference to the drawings.

Fig. 1 schematically illustrates the form of the redox flow battery according to the present invention, in which a plurality of battery modules 10 connected to a pressure generator 500 through a fluid transport pipe 330 for transporting an electrolyte are electrically connected through a module connection portion 600. However, in some cases, the battery modules may be independently driven without electrical connection therebetween.

The redox flow battery according to the present invention is characterized in that the electrolytes are independently circulated without interference or exchange of the electrolytes between the battery modules, or the electrolyte tank is shared by several battery modules, thereby minimizing the generation of shunt current. In some cases, a passage through which the electrolyte can flow may be formed between the battery modules to mix the electrolyte between the battery modules. In the present invention, it is not limited.

Fig. 2 schematically illustrates the form of the battery module 10, and includes a battery cell 100, an anolyte tank 210, and a catholyte tank 220, which are connected to the battery cell via an electrolyte flow path 400. On the other hand, the electrolyte solution flow path may be provided with a fluid control unit 300 so that the electrolyte solution can be transferred by pressure transmitted from the outside.

In the present invention, as shown in the lower end of fig. 2, the battery cell 100 may include: a pair of electrodes divided into an anode 110 and a cathode 120; a separation film 130 between the electrodes; and a separator 140 separating the outsides of the anode and cathode. The anode, the cathode, the separation film, and the separator are located in the case 150, and electrochemical reactions such as movement, charge, and discharge of the electrolyte are generated inside the case.

The anolyte and the catholyte supplied to the battery cell are transferred from the electrolyte tank and flow into the case through the electrolyte flow path to react, and the reacted electrolyte enters the electrolyte tank through the electrolyte flow path again to circulate.

In the present invention, the fluid control unit 300 may be provided in an electrolyte flow path through which the electrolyte flows into the battery cell, instead of a conventional pump, for circulation of the electrolyte. The structure and type of the fluid control unit are not limited as long as the fluid control unit is provided to allow the electrolyte to flow in a predetermined direction by a change in pressure, and the fluid control unit can prevent backflow and can transfer the electrolyte by a change in pressure.

As another example of the fluid control portion, a check valve may be mentioned. As described in more detail with reference to the left upper end of fig. 2, the check valves include a pair of

check valves

311 and 312 capable of transferring fluid in one direction in the electrolyte flow path, and a fluid transfer pipe 330 for directly transferring pressure to the electrolyte flow path is provided between the check valves and communicates with the electrolyte flow path.

That is, when pressure is transmitted from the outside through the fluid transport pipe, pressure change occurs naturally in the space between the first check valve and the second check valve, and the electrolyte flows in one direction.

For example, when the operation is performed such that the pressure in the space between the first check valve and the second check valve in the fluid transfer pipe is reduced (negative pressure), the pressure in the space between the check valves is naturally also reduced. Therefore, in order to maintain the pressure balance, the electrolyte on the side of the first check valve flows into the space between the check valves, and the second check valve is closed, thereby preventing the backflow of the electrolyte. When the pressure supplied from the outside is increased (positive pressure), the electrolyte solution present between the check valves naturally flows into the battery cell through the second check valve, and the first check valve closes. By repeating this process, the electrolyte flows into the battery cell or the stack and circulates.

Although fig. 2 and the like show a mode in which the fluid control unit includes a pair of check valves, the fluid control unit may have only one check valve, or may have two or more check valves, because the fluid control unit generally has a high fluid flow resistance inside the battery cell and has an effect of preventing a part of the backflow even without the second check valve, if necessary. The configuration of the fluid control unit can be freely changed within a range that can achieve the object of the present invention, and it is needless to say that the configuration also falls within the scope of the present invention.

In the embodiment of the present invention, the fluid control unit applies positive pressure to the battery cell to supply the electrolyte, but the present invention is not limited to this, and the fluid control unit may be connected to an electrolyte flow path through which the electrolyte is discharged from the battery cell, and apply negative pressure to the battery cell to circulate the electrolyte from the battery cell. In this case, the operation direction of the check valve may be reversed, and in this case, the positive pressure and the negative pressure preferably operate in a reverse manner in the pressure supply cycle of the fluid control portion described in fig. 8A to 8C.

The present invention has the above-described structure, and therefore, it is not necessary to drive the motor for each battery module, energy efficiency can be improved, the circulation distance of the electrolyte can be shortened, the responsiveness of the battery can be improved, and the use of acid-resistant piping can be minimized.

In the present invention, the fluid control unit is required to form a positive pressure and a negative pressure at a certain level or higher, because the flow of the electrolyte is guided. In the present invention, the range of the positive pressure and the negative pressure is not limited, and the pressure may be higher than the atmospheric pressure or lower than the atmospheric pressure as long as the pressure is a pressure that can guide the flow of the electrolyte. As an example, the range of the pressure may be based on the atmospheric pressure, and the difference may be appropriately adjusted regardless of the upper limit and the lower limit of the pressure, such as positive pressure to negative pressure, positive pressure to atmospheric pressure, atmospheric pressure to negative pressure, and the like.

In order to guide the smooth flow of the electrolyte and increase the amount of the electrolyte supplied to the battery cell, a control unit case 320 may be provided, as shown in the upper end of fig. 2, which can form a constant separation chamber between the check valves.

In the present invention, the type of the device and the fluid for transmitting the pressure in the fluid control unit is not limited. As an example, a compressor or a pump for compressing a fluid for transmitting pressure may be provided as the pressure generator 500 in order to form the positive pressure, and the pressure generator may be a vacuum device, an intake device, or an ejector (ejector) having a venturi tube in order to form the negative pressure. As the fluid, any of gas and liquid can be used, and can be freely selected according to the type of the pressure generator to be operated. Further, only either one of the devices that form positive pressure or negative pressure may be used.

The pressure generator according to the present invention may be configured to be supplemented by a separate supply device (not shown) in order to compensate for fluid lost during operation, and may further include a pressure measuring device (not shown) configured to inject fluid into the pressure generator through the supply device to be supplemented or discharged to the outside when a positive pressure and a negative pressure below a certain level are measured in order to maintain a constant magnitude of pressure applied to the fluid control unit.

Fig. 4 shows a general form of the fluid control unit including the check valve, and the control unit case 320 includes a pair of

check valves

311 and 312 directly connected to the electrolyte flow path 400 on both side surfaces thereof, and a fluid transport pipe 330 for supplying pressure to the electrolyte flow path is directly connected to an upper surface thereof. At this time, in order to prevent the fluid from flowing into the control unit case through the fluid transport pipe, one or more electrolyte inflow preventers 350 may be further provided.

The electrolyte inflow preventer may be made of any material and in any form as long as it can smoothly transmit pressure and prevent fluid from flowing into the control unit case. As an example, as shown in fig. 4, it is preferable that the valve be located in the electrolyte case, be able to physically separate the electrolyte case from the fluid transport tube, and be provided in a flexible valve form.

The fluid control unit 300 according to the present invention may be located between the electrolytic solution tank and the battery cell as shown in fig. 2, or may be located inside the electrolytic solution tank 200 as shown in fig. 3. To explain this in more detail, the fluid control unit is provided at one end of the electrolyte flow path 400 in the electrolyte tank, and the mixing of the fluid and the electrolyte is cut off by the control unit case 320. The control unit case has a pair of

check valves

311 and 312 on the side surface, and each of the check valves includes a check valve that operates from the outside to the inside of the control unit case and a check valve that operates from the inside to the outside of the control unit case. In this case, the check valve, which operates from the inside to the outside of the control unit case, may be directly connected to one end of the electrolyte flow path. The check valve that operates from the outside to the inside of the control unit case is preferably located in the electrolyte solution by directly contacting the electrolyte solution in the electrolyte solution tank or extending the line.

When a positive pressure is transmitted to the fluid control unit in the electrolyte tank by the pressure generator, the electrolyte in the fluid control unit is pushed out to the electrolyte flow path by the check valve, and the liquid level of the electrolyte in the fluid control unit naturally decreases, thereby causing a difference in liquid level between the electrolyte in the fluid control unit and the electrolyte outside. When the liquid level of the electrolyte is lowered by a predetermined amount or more and the supply of the positive pressure is interrupted, the electrolyte can be caused to flow into the fluid control portion by the difference in the liquid level of the electrolyte. Therefore, the amount of negative pressure supplied to the pressure generator to flow the electrolyte can be reduced, or the electrolyte can naturally flow into the fluid control unit even if the negative pressure is not supplied, and the efficiency of the entire redox flow battery can be improved.

In the present invention, the check valve 310, which is also referred to as a backflow prevention valve, operates such that the flow of the electrolyte is directed in one direction. In the present invention, as shown in fig. 2 and the like, the check valve may have any configuration such as a ball (ball) shape and a valve shape as long as the flow direction of the fluid can be controlled.

For example, a disk-shaped check valve as shown in fig. 5A or a valve-shaped check valve as shown in fig. 5B may be provided, and various types of check valves such as a lift check valve, a swing wafer check valve, and a wedge disk check valve may be used.

In addition to the check valve, a valve that operates by pressure as shown in fig. 5C may be provided. The operation of the valve is similar to that of a general check valve, and the flow of the electrolyte may be a mode in which the fluid flows in the forward direction as a whole because the flow resistance in the reverse direction is higher than that in the forward direction. That is, regardless of the form of the check valve, the flow of the electrolyte may be such that the fluid flows in the forward direction as a whole due to a higher flow resistance in the reverse direction than in the forward direction, and this also falls within the category of the check valve.

As shown in fig. 6 and 7, the battery module may include two or more fluid control units 300. Generally, when there is one fluid transport pipe in the fluid control unit, the electrolyte is supplied to the battery cell only at a positive pressure, and it is difficult to form a continuous flow of the electrolyte. In addition, at this time, the electrolyte may stay in the battery cell for a certain time or more, and the performance of the battery cell itself may be degraded.

To eliminate this, the present invention may connect two or more fluid control portions to direct a continuous flow. As will be described in more detail with reference to fig. 7, when a positive pressure is supplied to the first fluid control unit 300a, a negative pressure is supplied to the second fluid control unit 300 b. That is, since the positive pressure is supplied to the first fluid control portion, the electrolyte between the check valves flows into the battery cell side, and since the negative pressure is supplied to the second fluid control portion at the same time, the electrolyte in the electrolyte tank flows into the space between the check valves. After the electrolyte in the first fluid control unit is supplied to the battery cell, negative pressure is supplied to the first fluid control unit, and positive pressure is supplied to the second fluid control unit at the same time, whereby the electrolyte is supplied to the battery cell. By repeating such an operation, the continuous flow of the electrolyte can be guided to stably drive the battery cell.

When the battery module includes a plurality of fluid control units as described above, it is preferable to adjust the supply cycle of the pressure supplied to the fluid control units. In this case, it is preferable to change the pressure in a different phase than to set the supply cycles to the same phase (phase).

As will be described in more detail with reference to fig. 8A, when the pressure supply cycle of the first fluid control unit and the pressure supply cycle of the second fluid control unit are made completely opposite (minor image phase) and the positive pressure section and the negative pressure section of each control unit are made to have the same length as each other as shown in fig. 8A, a constant flow rate of the electrolyte solution should be supplied to the battery cell, but in each fluid control unit, at the point where the pressure cycle changes, the electrolyte solution is generally supplied to the battery cell in an amount smaller than the electrolyte solution to be supplied due to the disturbance of each section. That is, in this interval, the flow rate may decrease instantaneously.

Therefore, in order to prevent the supply of the electrolyte from being blocked due to the above-described disturbance, it is preferable that the positive pressure cycle sections or the negative pressure cycle sections of the fluid control units overlap each other.

To explain this in more detail with reference to the drawings, as shown in fig. 8B, the periods of the fluid control units are made the same, the lengths of the positive pressure section and the negative pressure section of one fluid control unit are maintained the same, and the positive pressure section of the other fluid control unit is maintained longer than the negative pressure section, or as shown in fig. 8C, the operation phases of the two fluid control units are made different, and the positive pressure period of one fluid control unit and the positive pressure period of the other fluid control unit are made to overlap each other for a certain time, that is, the interval D adjusted to be the positive pressure period in one fluid control unit is made to be the positive pressure period in the other fluid control unit₁Interval D of negative pressure cycle in the other fluid control part₂The length is preferably long.

This is because, when the positive pressure cycle and the negative pressure cycle of the two fluid control portions have exactly the same length, the electrolyte is generally supplied to the battery cell in an amount smaller than the amount of the electrolyte to be supplied, and therefore, in order to compensate for the shortage, the length of the positive pressure cycle of one or both of the fluid control portions is made longer than the length of the negative pressure cycle, and the electrolyte supplied to the battery cell is maintained constant.

Although the two fluid control units are illustrated in the drawings as having the same cycle, the two fluid control units may have the same or different cycles, and may be changed to any mode as long as the purpose of the operation of the fluid control units described above can be achieved.

In addition, when the flow rate of the electrolyte flowing into the fluid control unit is smaller than the flow rate discharged to the battery cell (in addition, when the electrolyte inflow preventer is not provided or the electrolyte inflow preventer is broken), the fluid to be subjected to positive pressure flowing into the fluid control unit may flow into the battery cell instead of the electrolyte, and the performance of the battery cell may be degraded.

In order to adjust the cycle of the pressure supplied to each fluid control unit 300 as described above, it is preferable to further provide a pressure control valve 340 between the pressure generator and the fluid control unit as shown in fig. 9A and 9B. The pressure control valve is used for alternately supplying positive pressure and negative pressure to the fluid control portion, and includes a structure for freely adjusting the opening and closing of the port in accordance with a specific pressure supply cycle as described above, and devices of all forms corresponding thereto.

As described in more detail with reference to fig. 10A and 10B, the pressure control valve 340 may be provided in each of the fluid transfer pipes from the two different pressure generators as shown in fig. 10A. The pressure control valve may include a pressure control valve housing 341, and a switching pipe 342 inside the housing. In this case, the pressure control valve housing includes a pipe (inlet pipe) through which the fluid flows toward the inside of the housing (input) and a pipe (outlet pipe) through which the fluid flows toward the outside of the housing (output), and the number of the pipes can be adjusted to freely adjust the switching mode of the switching pipe.

Further, as shown in fig. 10B, positive pressure and negative pressure may be simultaneously connected to the respective pressure control valves 340, and the pressure supplied to the fluid control unit 300 may be selectively supplied from the positive pressure and the negative pressure in a desired cycle. Alternatively, another port or an external valve may be provided to connect the two pressure supply pipes so that an intermediate pressure between the positive pressure and the negative pressure can be formed.

As an example, in the case where one pressure control valve includes one inflow pipe and two discharge pipes, the pressure control valve has a structure in which one pressure generator and two fluid control portions are connected to each other. Therefore, when the pressure needs to be changed when the positive pressure is supplied to any one of the fluid control units, the connection mode between the switching pipe and the discharge pipe may be changed so as to supply the positive pressure to the other fluid control unit.

Although only one casing inflow pipe and two casing discharge pipes may be provided as shown in the drawings, the present invention is not limited to this, and two casing inflow pipes and one casing discharge pipe may be provided, and the number of inflow pipes and discharge pipes may be freely adjusted according to the number of pressure supply units and fluid control units.

In addition, in the section D adjusted to the positive pressure period as described above₁Interval D of more negative pressure period₂In the case of a long period, the interval of the positive pressure cycle is longer than the interval of the negative pressure cycle, and therefore, the positive pressure is supplied to all the fluid control units at the moment. In this case, if the switching pipe is provided as described above, it is difficult to supply positive pressure to all the fluid control units, and therefore, it is preferable to provide a regulator valve (not shown) such as an electromagnetic valve outside the casing instead of the switching pipe.

For example, the solenoid valves are connected to the discharge pipes connected to the respective fluid control units, and when a positive pressure is supplied to any one of the fluid control units, the solenoid valves of the discharge pipes connected to the corresponding fluid control unit are opened, and when a positive pressure is supplied to both the first fluid control unit and the second fluid control unit, the solenoid valves of all the discharge pipes are opened, thereby adjusting the positive pressure cycle as described above. Alternatively, as shown in fig. 10B, the positive pressure and the negative pressure may be controlled independently for each battery cell.

The redox flow battery according to the present invention may include a plurality of pressure generators 500 as shown in fig. 9A and the like, but may use space to the maximum extent while reducing energy consumption by simultaneously generating positive pressure and negative pressure in one pressure generator and configuring discharge ports for the generated positive pressure and negative pressure to be different from each other as shown in fig. 9B.

The redox flow battery according to the present invention may further include an electrolyte inflow preventer 350 inside the fluid transport pipe 330.

In general, since vanadium oxide, hydrazine, a halogen compound, other acids, and the like are added to a redox flow battery, a transport pipe having acid resistance needs to be used in order to transport the redox flow battery. However, since the special transport pipe as described above is more expensive than a general pipe, it is preferable to use a general metal pipe, a pneumatic pipe, or a pneumatic guide pipe in addition to the pipe for transporting the electrolyte.

The problem is that in order to apply pressure to the electrolyte flow path by the fluid as described above, it is necessary to form the fluid transfer pipe for supplying the fluid so as to communicate with the electrolyte flow path, but the electrolyte may flow back to the fluid transfer pipe side during the positive pressure supply or the negative pressure supply.

Therefore, in order to solve such a problem, the fluid transfer pipe may further include an electrolyte inflow prevention device selected from one or more than two of a valve, an isolation valve, a check valve, and a float valve, so as to prevent the electrolyte from flowing back.

In more detail, an example of the electrolyte inflow preventer 350 is described with reference to fig. 11, in which the electrolyte inflow preventer is provided at a position adjacent to the fluid transport pipe and the fluid control unit casing, is a substance having pores therein, such as a mesh structure, which can float by the electrolyte, and is a sheet-like surface in contact with the fluid transport pipe so that the fluid transport pipe can be closed.

As shown in the upper end of fig. 11, the electrolyte inflow preventer preferably has a diameter of a predetermined size or more, and is preferably smaller than the diameter of the fluid transport pipe, in order to float in the fluid transport pipe. On the other hand, the fluid transport pipe may be configured such that a diameter of a portion directly connected to the control unit case is smaller than a diameter of the electrolyte inflow preventer so that the electrolyte inflow preventer is not detached.

As shown in the lower end of fig. 11, when the negative pressure is applied to the fluid transport pipe to raise the liquid level of the electrolyte in the control unit case, the electrolyte inflow prevention device blocks the fluid transport pipe, and functions as a kind of valve, thereby preventing the inflow of the electrolyte.

However, in the case of the float valve shown in fig. 11, it may be difficult to completely block the inflow of the fluid into the control unit case by the operation of the pump that supplies the negative pressure and the positive pressure. Therefore, as shown in fig. 12, the electrolyte inflow preventer introduced in the form of a valve may be provided so as to completely cover the end face of the fluid transport tube.

As described in more detail with reference to fig. 12, the valve is made of an elastic material to completely close the connection between the fluid transport tube and the control unit case, so that the pressure transmitted through the fluid transport tube can be efficiently transmitted into the control unit case. That is, as shown in the upper end of fig. 12, when the positive pressure is transmitted to the control unit case, the valve is also expanded in the direction from the fluid transport tube to the control unit case in accordance with the positive pressure. Therefore, the pressure in the control unit case rises, and therefore the internal check valve naturally operates, and the electrolyte moves to the battery cell side.

As shown in the lower end of fig. 12, when negative pressure is transmitted to the control unit case, the valve is also expanded in the direction of the fluid transport tube from the control unit case in accordance with the negative pressure. In this case, the pressure in the control unit case is reduced, and the check valve inside is operated, so that the electrolyte solution moves from the electrolyte tank toward the control unit case.

However, the present invention is not limited to this, and any structure may be employed as long as it can transmit pressure to the fluid control unit while blocking the inflow of the electrolyte, as long as it can completely block the fluid transport pipe by the float or the valve that can be deformed by pressure as shown in fig. 11 or 12.

In addition, the electrolyte inflow preventer may be used by mixing one or more than two different configurations. That is, it does not matter if one or more floating bodies or the valve-shaped electrolyte inflow prevention devices are mixed and used.

The electrolyte inflow preventer is preferably constructed of a material having fluidity so as to maintain acid resistance because of its structure in direct contact with the electrolyte. For example, polymers such as polypropylene, polyethylene, and polystyrene, rubbers such as acrylic rubber and fluororubber, and metals such as aluminum can be used without limitation as long as they have the above-described physical properties.

In addition, the redox flow battery according to the present invention may further include a fluid filter 360 in the fluid transport pipe 330 in order to remove impurities that may be mixed in the electrolyte.

When the fluid for transmitting pressure to the fluid control unit is air or a gas containing oxygen, the electrolyte may be oxidized to lower the charge/discharge efficiency of the battery cell. In order to eliminate this, it is preferable that the fluid transport pipe further includes a fluid filter as shown in fig. 11 and 12 so that impurities such as oxygen are not mixed in the electrolyte solution. In this case, the fluid filter may be provided in each fluid control unit, or may be provided in one fluid transport pipe by connecting all the fluid control units, or may be replaced for repair.

In the present invention, the fluid filter is used to remove components such as oxygen and moisture that deteriorate the performance of the electrolytic solution in advance, and preferably includes a corresponding component removal filter or the like that can uniformly remove the components other than the above components as long as the components affect the performance of the electrolytic solution. As an example, an oxygen scavenger or oxygen removal device may be installed in a portion of the fluid transport pipe.

In addition to the above-described configuration, the redox flow battery according to the present invention may further include an electric terminal for external electrical connection, a control unit and a monitor unit capable of controlling the fluid control unit and the like, and a terminal or a connector for connecting them.

Further, the fluid filter may be applied to a rotary body using pressure supplied from the outside, and a structure in place of the pump may be configured by rotation of the rotary body.

Fig. 13 is a diagram of an embodiment in which a large-capacity system is configured by connecting a plurality of battery modules described above. The battery modules 100 may be electrically connected in series or in parallel, or may be electrically independent, and may be connected to a pressure generator so that pressure can be transmitted from the outside in order to drive the fluid control units of the respective battery modules, and the number of the pressure generators may be one or more according to the size and the number of the battery modules.

As described above, the redox flow battery according to the present invention can smoothly circulate an electrolyte to a battery cell or a stacked body without using an expensive chemical pump. Further, since the electrolyte tank can be provided for each of the battery modules or shared by a certain number of battery modules, the circulation distance of the electrolyte is considerably shorter than that of a conventional redox flow battery, and the specific gravity of the expensive acid-resistant transport pipe can be significantly reduced.

Further, since the circulation distance of the electrolyte is short, the response can be greatly improved as compared with the conventional redox flow battery, and the electrolyte tank can be separated, and at this time, the electrolyte circulates only in each battery module, and thus a shunt current is not generated.

The redox flow battery according to the present invention can effectively realize a high-voltage large-capacity Energy storage system (Energy storage system) called an Energy storage box by the above-described characteristics. Further, since it is not necessary to use a plurality of expensive chemical pumps, it is possible to save costs, and since each battery module can be independently installed and replaced, it is possible to improve the operation efficiency. Furthermore, since the large-capacity energy storage system can be realized by differentiating the battery modules having similar performance in consideration of the performance variation of the battery modules, the efficiency of the system can be improved.

The redox flow battery according to the present invention will be described in more detail below with reference to examples and comparative examples. The following examples and comparative examples are merely described to aid understanding of the present invention, and therefore the present invention is not limited to the following examples and comparative examples.

As shown in fig. 7, the battery cells were connected to the electrolyte tank and the fluid control unit, and a flow rate measuring instrument was connected to the electrolyte inlet and outlet and the outlet of each battery cell to measure the flow rate of the electrolyte.

At this time, the battery cell used in each example was composed of two carbon electrodes, two current collectors, four gaskets, and one separator film, the active area of which was about 49cm². The separator is made of a carbon material, and a fluorine-based separator is used as the separator. The electrolyte is a vanadium electrolyte, and the vanadium concentration is 1.6mol to 2.0 mol. At this time, the specific gravity of the vanadium electrolyte was about 1.4.

Further, the battery module used in each of the embodiments is provided with two fluid control portions having a valve configuration, and the flow rate of the electrolyte is about 100 ml/min.

In the battery module configured as described above, the pressure supplied to the fluid control unit was adjusted to circulate the electrolyte, the pressure supply period of the fluid control unit was set to two seconds, the positive pressure supply time was adjusted as shown in table 1 below, and the battery module was repeatedly operated for one minute. At this time, the flow rate of the electrolyte discharged from the battery cell was measured in units of one minute, and then an average value was calculated.

[ Table 1]

As shown in table 1 above, when the two fluid control units are controlled in the same cycle and different phases (example 1), although a flow rate lower than the average flow rate is instantaneously caused to flow, if the phases of the pressure supply cycles of the fluid control units are adjusted to be different and the positive pressure supply time of the fluid control units is made longer than the negative pressure supply time as shown in examples 2 to 4, a flow rate higher than the average flow rate is instantaneously caused to flow, and therefore, a flow rate higher than the minimum flow rate required to maintain the cell performance can be ensured, and stable cell driving can be performed with more improved performance.

As described above, the general connection structure of the redox flow battery according to the present invention and the like have been described with reference to the preferred embodiments and comparative examples of the present invention, but it will be understood by those skilled in the art that various modifications and changes can be made to the present invention without departing from the spirit and scope of the present invention described in the following claims.

Claims

1. A redox flow battery in which,

the battery module includes one or more battery modules each including a battery cell, an electrolyte tank, an electrolyte flow path, and a fluid control unit for transmitting pressure generated externally to the electrolyte flow path, and is configured to independently circulate the electrolyte for each or a predetermined number of the battery modules to perform charging and discharging,

the battery module includes a plurality of fluid control units, at least two of the plurality of fluid control units being arranged in parallel in at least one of a section from the electrolyte tank to the battery cell and a section from the battery cell to the electrolyte tank in the electrolyte flow path,

a fluid transport pipe connected to each of the at least two fluid control portions, the fluid transport pipe being connected to a pressure generator provided independently of the electrolyte flow path so that a first pressure at which the electrolyte flows from the electrolyte tank to the battery cell and a second pressure at which the electrolyte flows from the battery cell to the electrolyte tank can be supplied to the at least two fluid control portions via the fluid transport pipe by the pressure generator,

wherein a first pressure providing time interval of any one of the at least two fluid control portions overlaps with a second pressure providing time interval of another one of the at least two fluid control portions.

2. A redox flow battery as claimed in claim 1 wherein,

the battery module includes:

one or more than two battery units, which are divided into an anode and a cathode in the internal region, and comprise a separation film and a separator laminated on the outer side surface of the electrode;

an electrolyte flow path connecting the battery cell and the electrolyte tank and transferring the electrolyte; and

3. A redox flow battery as claimed in claim 1 wherein,

the fluid control portion includes:

and one or more check valves disposed inside the electrolyte flow path to guide the flow of the electrolyte in one direction.

4. A redox flow battery as claimed in claim 1 wherein,

the fluid control portion is provided at one side end of the electrolyte flow path, and includes:

a control section case located in the electrolyte tank; and

5. A redox flow battery as claimed in claim 1 wherein,

the fluid control unit further includes one or more pressure control valves.

6. A redox flow battery as claimed in claim 1 wherein,

the fluid transport pipe further includes an electrolyte inflow preventer inside, the electrolyte inflow preventer being one or more than two selected from a valve, an isolation valve, a check valve, and a float valve.

7. A redox flow battery as claimed in claim 1 wherein,

the fluid transport pipe is provided with a fluid filter.