Tubular redox flow battery stack and all-vanadium redox flow battery system

Abstract

The utility model discloses a tubular redox flow battery stack and an all-vanadium redox flow battery system, and the tubular redox flow battery stack comprises a graphite rod, a first carbon felt electrode, a proton membrane, a second carbon felt electrode, a graphite tube and a packaging tube shell which are sequentially sleeved from inside to outside, a negative electrode reaction side for circulation of a negative electrode electrolyte is formed on the inner side of the proton membrane, a negative electrode liquid inlet and a negative electrode liquid outlet are formed in the positions, corresponding to the negative electrode reaction side, of the packaging tube shell, and a positive electrode reaction side for circulation of a positive electrode electrolyte is formed on the outer side of the proton membrane; a positive electrode liquid inlet and a positive electrode liquid outlet are formed in the positions, corresponding to the positive electrode reaction side, of the packaging tube shell; the diameter of the proton membrane is matched with the inner diameter of the second carbon felt electrode, and the proton membrane can form deformation adjustment along with the change of the flow and the pressure of the electrolyte. By adopting the tubular structure, the complexity of the cell structure is reduced, particularly, the fluid resistance and mass transfer influence in a galvanic pile are reduced, and the running reliability of the proton membrane is effectively improved.

Description

Technical Field

[0001] This utility model relates to the field of flow battery technology, and in particular to a tubular flow battery stack and an all-vanadium flow battery system. Background Technology

[0002] Current flow batteries typically employ a stacked assembly method, which requires high sealing standards. Over long-term use, leakage is prone to occur, causing corrosion to other components in the stack structure. Furthermore, leaked electrolyte pollutes the environment and contaminates the outer surface of the stack, affecting its aesthetic appearance. Additionally, the stacked assembly method uses a tie-rod fixing structure, requiring metal end plates to meet the pressure requirements for stack sealing. This results in lower mass power density and volumetric power density of the flow battery stack, hindering cost reduction and industrial applications.

[0003] Currently, a Chinese utility model patent with publication number CN 221727180 U discloses a tubular flow battery. By setting the tube body, electrodes, current collector rings, and ion-conducting membrane in a stacked annular structure, it achieves a larger contact area for ion exchange and lower losses in its liquid mass transfer pump function. While the annular electrodes ensure sufficient internal liquid channels, it neglects the implementation method of the annular ion membrane and the difference in flow rates between the two electrodes due to uneven pressure, and the resulting shear force can damage the proton exchange membrane. Furthermore, in this tubular flow battery, the first electrode is sleeved outside the second electrode, with an annular ion-conducting membrane spaced between them. The cross-section of the single cell, from the inside out radially, shows the second electrode, inner current collector ring, ion-conducting membrane, outer current collector ring, first electrode, and tube body. The overall internal outline of the single cell is U-shaped or L-shaped. This arrangement results in a small contact area between the current collector ring and the electrode, leading to severe heat generation under high current conditions. The non-linear internal outline also causes concentration polarization, reducing energy efficiency. Utility Model Content

[0004] In order to overcome the shortcomings of the prior art, the purpose of this utility model is to provide a tubular flow battery stack and an all-vanadium redox flow battery system, which has the advantages of reducing the complexity of the battery structure and the risk of electrolyte leakage, and improving the reliability of the proton exchange membrane.

[0005] The objective of this utility model is achieved through the following technical solution:

[0006] According to a first aspect of the present disclosure, a tubular flow battery stack is provided, comprising a graphite rod, a first carbon felt electrode, a proton exchange membrane, a second carbon felt electrode, a graphite tube, and a packaging shell arranged sequentially from the inside out. The inner side of the proton exchange membrane forms a negative electrode reaction side for the flow of negative electrode electrolyte. The packaging shell is provided with a negative electrode inlet and a negative electrode outlet corresponding to the negative electrode reaction side. The outer side of the proton exchange membrane forms a positive electrode reaction side for the flow of positive electrode electrolyte. The packaging shell is provided with a positive electrode inlet and a positive electrode outlet corresponding to the positive electrode reaction side.

[0007] The diameter of the proton exchange membrane is adapted to the inner diameter of the second carbon felt electrode, and the proton exchange membrane can deform and adjust according to changes in the flow rate and pressure of the electrolyte.

[0008] To achieve the above technical solution, the battery stack is divided into a negative electrode reaction side and a positive electrode reaction side using a proton exchange membrane. The electrolyte enters from the positive electrode inlet and exits from the positive electrode outlet, while the negative electrode electrolyte enters from the negative electrode inlet and exits from the negative electrode outlet, ensuring that the positive and negative electrolytes do not cross-contaminate. On the positive electrode reaction side, a graphite tube serves as the current collector, and the second carbon felt electrode serves as the reaction electrode. The positive electrode electrolyte penetrates the graphite tube through the positive electrode inlet into the reaction zone, and then flows out through the graphite tube and the encapsulation shell. The positive electrode electrolyte completes the reaction on the second carbon felt electrode. On the negative electrode reaction side, a graphite rod serves as the current collector... The first carbon felt electrode is the reaction electrode, and the negative electrolyte reacts on the first carbon felt electrode. The battery stack is installed in a sequential manner so that the current collectors form surface contact, which can reduce the thermal effect. Since flow batteries usually operate under high current, the thermal effect is effectively reduced while also improving energy efficiency. Since the proton exchange membrane can deform and adjust with the flow rate and pressure of the electrolyte, it can overcome the effect of uneven flow and pressure distribution on the shear force of the proton exchange membrane in the large cavity, and can cope with uneven pressure and flow in different directions, thus improving the reliability of the proton exchange membrane operation.

[0009] This application adopts a tubular structure, which, compared with existing battery stacks, eliminates the need for heavy metal end plates, thereby increasing mass power density. It also eliminates the need for a tie rod-type fixing structure, reducing the complexity of the battery structure and the risk of electrolyte leakage. Furthermore, the tubular structure can form a DC layer channel internally, overcoming the problem of excessive internal resistance in existing battery stacks. This results in advantages such as low range resistance, reduced energy consumption, improved mass transfer, avoidance of polarization, and increased single-cycle conversion efficiency. Moreover, the large electrolyte flow rate, low flow resistance, and fast mass transfer make electrolyte flow rate no longer the main limiting factor, reducing additional pump power consumption.

[0010] In some exemplary embodiments, the proton exchange membrane is formed into a cylindrical structure using a laser welding process.

[0011] To achieve the above technical solution, a laser welding process is used to form the proton exchange membrane. This process has a concentrated welding temperature, a short action time, and causes minimal damage to the proton exchange membrane.

[0012] In some exemplary embodiments, the proton exchange membrane is also welded to both ends to form a sealed structure.

[0013] The above technical solution improves the overall sealing performance by setting a frame membrane, thereby increasing the reliability of the proton exchange membrane and improving its effective utilization rate.

[0014] In some exemplary embodiments, the first carbon felt is bonded to the graphite rod with conductive adhesive.

[0015] In some exemplary embodiments, the second carbon felt electrode is bonded to the inner wall of the graphite tube by conductive adhesive.

[0016] The above technical solution is achieved by using conductive adhesive bonding, which can solve the contact problem between the carbon felt electrode and the current collector in a large-channel flow battery, reduce contact resistance, and reduce ineffective heat effects.

[0017] According to a second aspect of the present disclosure, an all-vanadium redox flow battery system is provided, comprising:

[0018] As described in the first aspect, the tubular flow battery stack;

[0019] A positive electrode storage tank and a negative electrode storage tank, wherein the outlet of the positive electrode storage tank is connected to the positive electrode inlet, and the return end of the positive electrode storage tank is connected to the positive electrode outlet; the outlet of the negative electrode storage tank is connected to the negative electrode inlet, and the return end of the negative electrode storage tank is connected to the negative electrode outlet; and,

[0020] A delivery unit used to realize electrolyte circulation.

[0021] In some exemplary embodiments, the positive electrode storage tank is connected to the positive electrode inlet via a first inlet pipe and to the positive electrode outlet via a first return pipe, and the negative electrode storage tank is connected to the negative electrode inlet via a second inlet pipe and to the negative electrode outlet via a second return pipe.

[0022] In some exemplary embodiments, the delivery unit includes: a first delivery unit connected to the positive electrode storage tank and a second delivery unit connected to the negative electrode storage tank, wherein the first delivery unit is connected to the first infusion pipe and / or the first return pipe, and the second delivery unit is connected to the second infusion pipe and / or the second return pipe.

[0023] To achieve the above technical solution, the positive electrode electrolyte in the positive electrode storage tank is transported from the positive electrode inlet to the battery stack through the first transport unit, and the negative electrode electrolyte in the negative electrode storage tank is transported from the negative electrode inlet to the battery stack through the second transport unit. The positive electrode electrolyte and the negative electrode electrolyte are separated by a proton exchange membrane in the battery stack. The positive electrode electrolyte completes the reaction on the second carbon felt electrode, and the negative electrode electrolyte completes the reaction on the first carbon felt electrode. Since the proton exchange membrane can deform and adjust with the changes in the flow rate and pressure of the electrolyte, it can overcome the effect of uneven flow and pressure distribution on the shear force of the proton exchange membrane in the large cavity, and can cope with uneven pressure and flow in different directions, thus improving the reliability of the proton exchange membrane operation.

[0024] In summary, compared with the prior art, this utility model has the following beneficial effects:

[0025] This utility model provides a tubular flow battery stack and a vanadium redox flow battery system. The battery stack is divided into a negative electrode reaction side and a positive electrode reaction side by a proton exchange membrane. The electrolyte enters from the positive electrode inlet and exits from the positive electrode outlet, while the negative electrode electrolyte enters from the negative electrode inlet and exits from the negative electrode outlet, preventing cross-contamination between the positive and negative electrolytes. On the positive electrode reaction side, a graphite tube serves as the current collector, and a second carbon felt electrode serves as the reaction electrode. The positive electrode electrolyte enters the reaction zone through the graphite tube via the positive electrode inlet, and then flows out through the graphite tube and the encapsulation shell, completing the reaction on the second carbon felt electrode. On the negative electrode reaction side, a graphite rod serves as the current collector, and a first carbon felt electrode serves as the reaction electrode, completing the reaction on the first carbon felt electrode. The battery stack is installed in a sequential nested manner, allowing the current collectors to form surface contact, which reduces the thermal effect. Since flow batteries typically operate under high current, this effectively reduces... While improving thermal efficiency, the proton exchange membrane (PEM) also adapts to changes in electrolyte flow and pressure, thus overcoming the shear force on the PEM within the large cavity caused by uneven flow and pressure distribution. This allows it to cope with pressure and flow unevenness in different directions, improving the reliability of PEM operation. The tubular structure, compared to existing battery stacks, eliminates the need for heavy metal end plates, increasing mass power density. It also eliminates the need for a tie-rod fixing structure, reducing battery structure complexity and the risk of electrolyte leakage. Furthermore, the tubular structure creates a DC layer channel internally, overcoming the problem of excessive internal resistance in existing battery stacks. This results in advantages such as low range resistance, reduced energy consumption, improved mass transfer, avoidance of polarization, and increased single-cycle conversion efficiency. The large electrolyte flow rate, low flow resistance, and fast mass transfer mean that electrolyte flow rate is no longer the primary limiting factor, reducing additional pump power consumption. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of the tubular flow battery stack in an embodiment of the present invention.

[0027] Figure 2 This is a cross-sectional view of the tubular flow battery stack in an embodiment of this utility model.

[0028] Figure 3 This is a schematic diagram of the structure of the graphite rod and the first carbon felt electrode combined in an embodiment of the present invention.

[0029] Figure 4 This is a schematic diagram of the structure of the graphite rod, the first carbon felt electrode, and the proton membrane combined in an embodiment of the present invention.

[0030] Figure 5 This is a schematic diagram of the structure of the second carbon felt electrode, graphite tube, and encapsulation shell combined in an embodiment of this utility model.

[0031] Figure 6 This is a schematic diagram of the structure of the all-vanadium redox flow battery system in an embodiment of this utility model.

[0032] The numbers and letters in the diagram represent the names of the corresponding components:

[0033] 10. Graphite rod; 20. First carbon felt electrode; 30. Proton exchange membrane; 31. Frame membrane; 40. Second carbon felt electrode; 50. Graphite tube; 60. Encapsulation shell; 61. Negative electrode inlet; 62. Negative electrode outlet; 63. Positive electrode inlet; 64. Positive electrode outlet; 70. Positive electrode storage tank; 71. First delivery pipe; 72. First return pipe; 80. Negative electrode storage tank; 81. Second delivery pipe; 82. Second return pipe; 91. First delivery unit; 92. Second delivery unit. Detailed Implementation

[0034] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0035] like Figures 1 to 5As shown, the first aspect of this utility model provides a tubular flow battery stack, including a graphite rod 10, a first carbon felt electrode 20, a proton exchange membrane 30, a second carbon felt electrode 40, a graphite tube 50, and a casing 60 arranged sequentially from the inside out. The inner side of the proton exchange membrane 30 forms a negative electrode reaction side for the flow of negative electrolyte. The casing 60 is provided with a negative electrode inlet 61 and a negative electrode outlet 62 corresponding to the negative electrode reaction side. The outer side of the proton exchange membrane 30 forms a positive electrode reaction side for the flow of positive electrolyte. The casing 60 is provided with a positive electrode inlet 63 and a positive electrode outlet 64 corresponding to the positive electrode reaction side. The diameter of the proton exchange membrane 30 is adapted to the inner diameter of the second carbon felt electrode 40, and the proton exchange membrane 30 can deform and adjust according to the flow rate and pressure of the electrolyte.

[0036] Specifically, the proton exchange membrane 30 is formed into a cylindrical structure using laser welding. The laser welding process for forming the proton exchange membrane 30 results in concentrated welding temperature and short action time, minimizing damage to the proton exchange membrane 30. Furthermore, frame membranes 31 are welded and fixed to both ends of the proton exchange membrane 30 to form a sealed structure. The frame membranes 31 and the proton exchange membrane 30 can also be connected and fixed using laser welding. By setting the frame membranes 31, the overall sealing performance is improved, thereby enhancing the reliability of the proton exchange membrane 30 and increasing its effective utilization rate.

[0037] The first carbon felt is bonded to the graphite rod 10 with conductive adhesive, and the second carbon felt electrode 40 is bonded to the inner wall of the graphite tube 50 with conductive adhesive. The use of conductive adhesive bonding can solve the contact problem between the carbon felt electrode and the current collector in the large-channel flow battery, reduce the contact resistance, and reduce the ineffective heat effect.

[0038] The battery stack is divided into a negative electrode reaction side and a positive electrode reaction side by a proton exchange membrane 30. Electrolyte enters from the positive electrode inlet 63 and exits from the positive electrode outlet 64, while negative electrode electrolyte enters from the negative electrode inlet 61 and exits from the negative electrode outlet 62, ensuring no cross-contamination between the positive and negative electrolytes. On the positive electrode reaction side, a graphite tube 50 serves as the current collector, and the second carbon felt electrode 40 serves as the reaction electrode. The positive electrode electrolyte enters the reaction zone through the graphite tube 50 via the positive electrode inlet 63, and exits through the graphite tube 50 and the encapsulation shell 60. The positive electrode electrolyte completes the reaction on the second carbon felt electrode 40. On the negative electrode reaction side, a graphite rod 10 serves as the current collector. The fluid and the first carbon felt electrode 20 serve as the reaction electrode, and the negative electrolyte completes the reaction on the first carbon felt electrode 20. The battery stack is installed in a sequential manner so that the current collector forms a surface contact, which can reduce the thermal effect. Since flow batteries usually operate under high current, the thermal effect is effectively reduced while also improving energy efficiency. Since the proton exchange membrane 30 can deform and adjust with the flow rate and pressure of the electrolyte, it can overcome the shear force of the proton exchange membrane 30 in the large cavity caused by uneven flow and pressure distribution, and can cope with pressure and flow unevenness in different directions, thus improving the reliability of the proton exchange membrane 30 operation.

[0039] This application adopts a tubular structure, which, compared with existing battery stacks, eliminates the need for heavy metal end plates, thereby increasing mass power density. It also eliminates the need for a tie rod-type fixing structure, reducing the complexity of the battery structure and the risk of electrolyte leakage. Furthermore, the tubular structure can form a DC layer channel internally, overcoming the problem of excessive internal resistance in existing battery stacks. This results in advantages such as low range resistance, reduced energy consumption, improved mass transfer, avoidance of polarization, and increased single-cycle conversion efficiency. Moreover, the large electrolyte flow rate, low flow resistance, and fast mass transfer make electrolyte flow rate no longer the main limiting factor, reducing additional pump power consumption.

[0040] The assembly process of the tubular flow battery stack in this application includes:

[0041] S100, such as Figure 3 As shown, the first carbon felt electrode 20 is attached and fixed to the graphite rod 10 with conductive adhesive to form a first processed body. The first carbon felt electrode 20 serves as a reaction electrode, the graphite rod 10 serves as a current collector electrode, and is connected to an external wire.

[0042] S200, such as Figure 4 As shown, the proton exchange membrane 30 is formed into a column shape using laser welding technology, and a frame membrane 31 is welded at both ends of the tube opening for sealing. The proton exchange membrane 30 is fitted onto the first processing body to form the second processing body. The negative electrode electrolyte reacts inside the proton exchange membrane 30, enters from one end opening and flows out from the other end opening.

[0043] S300, such as Figure 5 As shown, the second carbon felt electrode 40 is bonded to the inner wall of the graphite tube 50 with conductive adhesive, and then the graphite tube 50 is encapsulated in the encapsulation shell 60 to form a third processed body. The encapsulation shell plays a protective and support role. The encapsulation can preferably be made of PP with glass fiber to meet the requirements of insulation, pressure resistance, and corrosion resistance. The diameter of the proton exchange membrane 30 is similar to the inner diameter of the second carbon felt electrode 40. The negative and positive electrolytes flow through the inner and outer channels of the proton exchange membrane 30, allowing the proton exchange membrane 30 to swing with the imbalance of liquid flow and pressure, thereby reducing the effect of liquid shear force due to uneven pressure and improving the reliability of the battery stack. The graphite tube 50 serves as the current collector electrode, with an external wire. The positive electrolyte penetrates the encapsulation shell 60 and the inlet of the graphite tube 50 to enter the reaction zone, and flows out from the other end through the outlet of the graphite tube 50 and the encapsulation shell 60.

[0044] S400, The second processing body is encapsulated into the third processing body to form a tubular flow battery stack. The positive and negative electrodes of the tubular flow battery stack are separated by a proton exchange membrane 30 to ensure that the electrolytes of the positive and negative electrodes do not penetrate each other. The active substances in the electrolyte complete the reaction on the first carbon felt electrode 20 and the second carbon felt electrode 40, respectively.

[0045] Of course, in some embodiments, the positive electrode reaction side and the negative electrode reaction side can also be interchanged.

[0046] like Figure 6 As shown, the second aspect of this utility model provides an all-vanadium redox flow battery system, including: a tubular flow battery stack as in the first aspect; a positive electrode storage tank 70 and a negative electrode storage tank 80, wherein the outlet end of the positive electrode storage tank 70 is connected to the positive electrode inlet 63, the return end of the positive electrode storage tank 70 is connected to the positive electrode outlet 64, the outlet end of the negative electrode storage tank 80 is connected to the negative electrode inlet 61, and the return end of the negative electrode storage tank 80 is connected to the negative electrode outlet 62; and a conveying unit for realizing electrolyte circulation.

[0047] The positive electrode storage tank 70 is connected to the positive electrode inlet 63 via a first inlet pipe 71 and to the positive electrode outlet 64 via a first return pipe 72. The negative electrode storage tank 80 is connected to the negative electrode inlet 61 via a second inlet pipe 81 and to the negative electrode outlet 62 via a second return pipe 82. The conveying unit includes a first conveying unit 91 connected to the positive electrode storage tank 70 and a second conveying unit 92 connected to the negative electrode storage tank 80. The first conveying unit 91 is connected to the first inlet pipe 71 and / or the first return pipe 72, and the second conveying unit 92 is connected to the second inlet pipe 81 and / or the second return pipe 82. In this embodiment, both the first conveying unit 91 and the second conveying unit 92 are inlet pumps. The first conveying unit 91 is connected to the first inlet pipe 71, and the second conveying unit 92 is connected to the second inlet pipe 8125.

[0048] The positive electrode electrolyte in the positive electrode storage tank 70 is transported to the battery stack from the positive electrode inlet 63 through the first transport unit 91, and the negative electrode electrolyte in the negative electrode storage tank 80 is transported to the battery stack from the negative electrode inlet 61 through the second transport unit 92. The positive and negative electrode electrolytes are separated by the proton exchange membrane 30 in the battery stack. The positive electrode electrolyte reacts on the second carbon felt electrode 40, and the negative electrode electrolyte reacts on the first carbon felt electrode 20. Since the proton exchange membrane 30 can deform and adjust with the flow rate and pressure of the electrolyte, it can overcome the shear force of the proton exchange membrane 30 in the large cavity caused by uneven flow and pressure distribution, and can cope with uneven pressure and flow in different directions, thus improving the reliability of the proton exchange membrane 30 operation.

[0049] The above embodiments only illustrate several implementation methods of this utility model, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the utility model patent. It should be noted that for those skilled in the art, several modifications and improvements can be made without departing from the concept of this utility model. These are all equivalent modifications and improvements made to the above embodiments based on the essential technology of this utility model, and all of these fall within the protection scope of this utility model.

Claims

1. A tubular flow battery stack, characterized by, The device includes, from the inside out, a graphite rod, a first carbon felt electrode, a proton exchange membrane, a second carbon felt electrode, a graphite tube, and a packaging shell. The inner side of the proton exchange membrane forms a negative electrode reaction side for the flow of negative electrolyte. The packaging shell has a negative electrode inlet and a negative electrode outlet corresponding to the negative electrode reaction side. The outer side of the proton exchange membrane forms a positive electrode reaction side for the flow of positive electrolyte. The packaging shell has a positive electrode inlet and a positive electrode outlet corresponding to the positive electrode reaction side. The diameter of the proton exchange membrane is adapted to the inner diameter of the second carbon felt electrode, and the proton exchange membrane can deform and adjust according to changes in the flow rate and pressure of the electrolyte.

2. The tubular flow battery stack of claim 1, wherein, The proton exchange membrane is formed into a cylindrical structure using a laser welding process.

3. The tubular flow cell battery stack of claim 1 or 2, wherein, The proton exchange membrane is also welded and fixed to both ends to form a sealed structure.

4. The tubular flow battery stack of claim 1, wherein, The first carbon felt is bonded and fixed to the graphite rod with conductive adhesive.

5. The tubular flow battery stack of claim 1, wherein, The second carbon felt electrode is bonded and fixed to the inner wall of the graphite tube with conductive adhesive.

6. A vanadium redox flow battery system characterized by, include: The tubular flow battery stack as described in any one of claims 1-5; A positive electrode storage tank and a negative electrode storage tank, wherein the outlet of the positive electrode storage tank is connected to the positive electrode inlet, and the return end of the positive electrode storage tank is connected to the positive electrode outlet; the outlet of the negative electrode storage tank is connected to the negative electrode inlet, and the return end of the negative electrode storage tank is connected to the negative electrode outlet; and, A delivery unit used to realize electrolyte circulation.

7. The vanadium redox flow battery system of claim 6, wherein, The positive electrode storage tank is connected to the positive electrode inlet via a first inlet pipe and to the positive electrode outlet via a first return pipe. The negative electrode storage tank is connected to the negative electrode inlet via a second inlet pipe and to the negative electrode outlet via a second return pipe.

8. The vanadium redox flow battery system of claim 7, wherein, The delivery unit includes: a first delivery unit connected to the positive electrode storage tank and a second delivery unit connected to the negative electrode storage tank, wherein the first delivery unit is connected to the first delivery pipe and / or the first return pipe, and the second delivery unit is connected to the second delivery pipe and / or the second return pipe.

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