A circular flow battery and a stack thereof

Abstract

The present invention belongs to the field of liquid flow batteries and discloses a circular liquid flow battery and a battery stack. The circular liquid flow battery includes a liquid conducting end plate A, a current collecting plate A, a bipolar plate A, a positive electrode frame, a positive electrode frame cover, a positive porous electrode, an ion exchange membrane, a negative porous electrode, a negative electrode frame cover, a negative electrode frame, a bipolar plate B, a current collecting plate B, and a liquid conducting end plate B, which are stacked in sequence. Bolt holes are respectively provided at the center positions of the liquid conducting end plate A, the current collecting plate A, the bipolar plate A, the positive electrode frame, the ion exchange membrane, the negative electrode frame, the bipolar plate B, the current collecting plate B and the liquid conducting end plate B. The liquid conducting end plate A and the liquid conducting end plate B are respectively provided with a side external connection positive electrode liquid inlet hole and a side external connection negative electrode liquid inlet hole. The present invention reduces structural parts and reduces the thickness and volume of the battery stack, can improve the energy density of the battery stack, and uses the end plate with only a half-opening on the inside, which reduces the difficulty of end plate processing; makes the battery stack more evenly fastened, and reduces the risk of leakage.

Description

Technical Field

[0001] The present invention relates to the field of liquid flow batteries, in particular to a circular liquid flow battery and a battery stack. Background Art

[0002] Circular liquid flow batteries have solved the problems of uneven electrolyte reaction, concentration polarization and reduced battery efficiency in rectangular battery stacks to a certain extent, but the existing circular liquid flow batteries still have the following problems, for example: Patent CN105514467 B discloses a design method for a circular liquid flow battery, a circular liquid flow battery, including end plates, flow channel plates A, flow channel plate A cover, flow channel plate B, flow channel plate B cover, current collecting plates, (bipolar) plates, positive porous electrodes, positive liquid flow frames, positive liquid flow frame cover, ion exchange membranes, negative liquid flow frame cover, negative liquid flow frames, negative porous electrodes, (bipolar) plates, current collecting plates, flow channel plate B cover, flow channel plate B, flow channel plate A cover, flow channel plate A, and end plates stacked in sequence. The circular liquid flow battery stack is composed of two or more circular liquid flow batteries connected in series; it includes end plates, flow channel plate A, flow channel plate A cover, flow channel plate B, flow channel plate B cover, current collecting plate, (bipolar) plate, positive porous electrode, positive liquid flow frame, positive liquid flow frame cover, ion exchange membrane, negative liquid flow frame cover, negative liquid flow frame, negative porous electrode, ..., (bipolar) plate, positive porous electrode, positive liquid flow frame, positive liquid flow frame cover, ion exchange membrane, negative liquid flow frame cover, negative liquid flow frame, negative porous electrode, (bipolar) plate, current collecting plate, flow channel plate B cover, flow channel plate B, flow channel plate A cover, flow channel plate A, and end plates stacked in sequence. The "..." indicates that the (bi)polar plate, positive porous electrode, positive flow frame, positive flow frame cover, ion exchange membrane, negative flow frame cover, negative flow frame, and negative porous electrode are repeated units. CN105514467 B uses end plates and flow plates for electrolyte inlet and outlet, increasing the thickness and volume of the stack and reducing its energy density. The use of flow plates requires a separate flow plate cover, making it more difficult to seal the stack and prone to leakage.

[0003] Patent CN 105742665 B discloses a liquid guide plate structure for a circular flow battery stack: the liquid guide plate is cylindrical, with a negative electrolyte guide channel and a positive electrolyte guide channel provided within it. The positive and negative electrolyte guide channels are designed into the same liquid guide plate, wherein the positive electrode inlet flow channel and positive electrode dispersion flow channel, and the negative electrode inlet flow channel and negative electrode dispersion flow channel are located in two different planes parallel to the two end surfaces of the liquid guide plate and do not intersect with each other. The positive electrode guide port connecting channel, the positive electrode guide port, the negative electrode guide port connecting channel, and the negative electrode guide port are staggered by a certain phase angle. Although the liquid guide plate structure used in CN 105742665 B reduces the difficulty of sealing, the multiple layers of openings within the liquid guide plate inevitably increase the thickness of the liquid guide plate, thereby affecting the thickness of the battery stack. Moreover, the staggered openings within the liquid guide plate make production and processing difficult.

[0004] Patent CN102903946 B discloses a circular liquid flow battery and a circular liquid flow battery stack including the same. The end plate is designed as follows: the electrolyte enters the end plate through the central liquid inlet hole and is distributed through the liquid inlet side groove. This design has two shortcomings: first, the sealing of the liquid inlet side groove is difficult to control, which can easily cause internal leakage; second, the distribution from the center hole to both sides is prone to imbalance. Summary of the Invention

[0005] To address the above issues, the present invention provides a design method for a circular flow battery and a circular flow battery stack, involving improvements to components such as the liquid inlet plate and electrode frame. This design can reduce manufacturing complexity, improve production efficiency, and minimize sealing area, thereby reducing the risk of leakage.

[0006] The above-mentioned object of the present invention is achieved by the following technical solutions:

[0007] A circular liquid flow battery includes a liquid conducting end plate A, a current collecting plate A, a bipolar plate A, a positive electrode frame, a positive electrode frame cover, a positive porous electrode, an ion exchange membrane, a negative porous electrode, a negative electrode frame cover, a negative electrode frame, a bipolar plate B, a current collecting plate B, and a liquid conducting end plate B, which are stacked in sequence. Bolt holes are respectively provided at the center of the liquid conducting end plate A, the current collecting plate A, the bipolar plate A, the positive electrode frame, the ion exchange membrane, the negative electrode frame, the bipolar plate B, the current collecting plate B, and the liquid conducting end plate B. The liquid conducting end plate A and the liquid conducting end plate B are respectively provided with a side externally connected positive electrode liquid inlet hole and a side externally connected negative electrode liquid inlet hole.

[0008] Furthermore, the liquid-conducting end plate A is a circular flat plate, and 2n holes are evenly opened on one side close to the liquid-conducting end plate A and at a certain distance from the center of the liquid-conducting end plate A, n of which are positive electrode liquid inlet holes, and n of which are negative electrode liquid inlet holes, n ≥ 2, and the setting of n is the same as the number of electrode partitions of the circular liquid flow battery. The depth of the hole only needs to not pass through the liquid-conducting end plate A. After reaching the required depth, the hole is bent 90 degrees in the radial direction toward the outside of the circle, and is connected to the side of the circular flat plate and the external liquid inlet device; the structure of the liquid-conducting end plate B is the same as that of the liquid-conducting end plate A.

[0009] Furthermore, the current collecting plate A and the bipolar plate A are circular flat plates, and 2n through holes are opened at positions corresponding to the positive electrode liquid inlet hole of the liquid guiding end plate A and the negative electrode liquid inlet hole of the liquid guiding end plate A, where n≥2; the structure of the current collecting plate B is the same as that of the current collecting plate A, and the structure of the bipolar plate B is the same as that of the bipolar plate A.

[0010] Furthermore, the positive electrode frame and the negative electrode frame are circular flat plates, and 4n through holes are opened in the circular flat plate area, n of which are positive electrode liquid inlet holes, n of which are negative electrode liquid inlet holes, n of which are positive electrode liquid outlet holes, and n of which are negative electrode liquid outlet holes, n≥2, and the setting of n is the same as the number of circular liquid flow battery electrode partitions. N brackets are set to connect the central liquid collection area and the outer annular area. The bracket and the outer annular area form an area for placing semicircular or fan-shaped porous electrodes. A groove is set in the outer annular area as a liquid inlet channel, one end of which is connected to the positive electrode liquid inlet hole and the negative electrode liquid inlet hole, and the other end is connected to the porous electrode placement area; a groove is set on the bracket as a liquid outlet channel, one end of which is connected to the central liquid collection area, and the other end is connected to the positive electrode liquid outlet hole and the negative electrode liquid outlet hole.

[0011] Furthermore, the positive porous electrode and the negative porous electrode are n semicircular or fan-shaped electrodes, n≥2, the electrolyte flows into the electrode from the long arc side of the semicircle or fan to participate in the reaction, and the electrolyte flows out of the electrode from the short arc side of the semicircle or fan.

[0012] Furthermore, the positive electrode frame cover and the negative electrode frame cover serve as sealing covers and are buckled onto the liquid inlet flow channel, liquid outlet flow channel and liquid collection area on the positive electrode frame and the negative electrode frame, respectively, to ensure that the electrolyte flows through the designed flow channel.

[0013] Furthermore, the ion exchange membrane is circular, and 4n through holes are opened corresponding to the positive or negative electrode frame, n≥2, n are the positive electrode liquid inlet holes of the ion exchange membrane, n are the negative electrode liquid inlet holes of the ion exchange membrane, n are the positive electrode liquid outlet holes of the ion exchange membrane, and n are the negative electrode liquid outlet holes of the ion exchange membrane. The setting of n is the same as the number of circular liquid flow battery electrode partitions.

[0014] A circular liquid flow battery stack is formed by connecting two or more circular liquid flow batteries in series.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. The end plate and the liquid guide plate (flow channel plate) are combined to reduce structural parts and reduce the thickness and volume of the fuel cell stack, which can improve the energy density of the fuel cell stack. In addition, the end plate of the present invention is only half-opened on the inside, which reduces the difficulty of end plate processing. It should be noted here that in the prior art, the liquid guide plate needs to open a large number of holes in the thickness direction of the plate, and its internal electrolyte channels converge from the hole position to the center of the circle, which is very difficult to process. However, the internal electrolyte channels of the present invention are from the hole position to the outside of the end plate, and when opening the hole, it is only necessary to drill a certain depth on the side, so it is described as a semi-open hole.

[0017] 2. Eliminate the flow channel plate and flow channel plate cover, eliminating the need for additional sealing, thereby reducing the risk of stack leakage.

[0018] 3. The electrode frame was redesigned, and bolt holes were added in the center of the electrode frame, liquid inlet plate, current collecting plate, and bipolar plate. This makes the center area of the stack solid and allows for additional bolts in the center area, making the stack more evenly tightened and reducing the risk of leakage. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the circular liquid flow battery and its stack structure of the present invention;

[0020] Figure 2 This is a schematic diagram of the assembly of a single battery;

[0021] Figure 3 Schematic diagram of the structure of the liquid-conducting end plate A;

[0022] Figure 4 Schematic diagram of the structure of the current collecting plate A;

[0023] Figure 5 Schematic diagram of the structure of bipolar plate A;

[0024] Figure 6 Schematic diagram of the structure of the positive electrode frame. The structure of the negative electrode frame is the same as that of the positive electrode frame.

[0025] Figure 7 Schematic diagram of the structure of the positive electrode frame cover plate. The negative electrode frame cover plate has the same structure as the positive electrode frame cover plate.

[0026] Figure 8 Schematic diagram of the structure of the positive porous electrode. The negative porous electrode has the same structure as the positive porous electrode.

[0027] Figure 9 Schematic diagram of the structure of the ion exchange membrane;

[0028] Figure 10 Schematic diagram of the structure of bipolar plate B;

[0029] Figure 11 Schematic diagram of the structure of the current collecting plate B;

[0030] Figure 12 Schematic diagram of the structure of the liquid-conducting end plate B;

[0031] Figure 13 Schematic diagram of the structure of a common bipolar plate.

[0032] Wherein: 1- liquid conducting end plate A, 2- current collecting plate A, 3- bipolar plate A, 4- positive electrode frame, 5- positive electrode frame cover, 6- positive porous electrode, 7- ion exchange membrane, 8- bipolar plate B, 9- current collecting plate B, 10- liquid conducting end plate B, 11- bolt hole of liquid conducting end plate A, 12- side external connection positive electrode liquid inlet hole, 13- liquid conducting end plate A positive electrode liquid inlet hole, 14- side external connection negative electrode liquid inlet hole, 15- liquid conducting end plate A negative electrode liquid inlet hole, 16- negative electrode Bipolar plate A bolt hole, 32-bipolar plate A positive electrode inlet hole, 33-bipolar plate A negative electrode inlet hole, 41-positive electrode frame bolt hole, 42-positive electrode inlet hole, 43-negative electrode inlet hole, 44-positive electrode outlet hole, 45-negative electrode outlet hole, 51-positive electrode frame Cover plate positive electrode liquid inlet hole, 52-positive electrode frame cover plate positive electrode liquid outlet hole, 71-ion exchange membrane bolt hole, 72-ion exchange membrane positive electrode liquid inlet hole, 73-ion exchange membrane negative electrode liquid inlet hole, 74-ion exchange membrane positive electrode liquid outlet hole, 75-ion exchange membrane negative electrode liquid outlet hole, 81-bipolar plate B bolt hole, 82-bipolar plate B positive electrode liquid outlet hole, 83-bipolar plate B negative electrode liquid outlet hole, 91-current collector B bolt hole, 92-current collector B positive electrode liquid outlet hole, 93 Collector plate B negative electrode liquid outlet hole, 101-liquid conducting end plate B bolt hole, 102-side external connection positive electrode liquid outlet hole, 103-liquid conducting end plate B positive electrode liquid outlet hole, 104-side external connection negative electrode liquid outlet hole, 105-liquid conducting end plate B negative electrode liquid outlet hole, 111-ordinary bipolar plate bolt hole, 112-ordinary bipolar plate positive electrode liquid inlet hole, 113-ordinary bipolar plate negative electrode liquid inlet hole, 114-ordinary bipolar plate positive electrode liquid outlet hole, 115-ordinary bipolar plate negative electrode liquid outlet hole. DETAILED DESCRIPTION

[0033] For a better understanding of the present invention, the following examples are provided to further illustrate the present invention, but the present invention is not limited to the following examples. Unless otherwise specified, the experimental methods used in the present invention are conventional methods, and the experimental equipment, materials, reagents, etc. used can be purchased from chemical companies.

[0034] A circular liquid flow battery, which is composed of a liquid conducting end plate A1, a current collecting plate A2, a bipolar plate A3, a positive electrode frame 4, a positive electrode frame cover 5, a positive porous electrode 6, an ion exchange membrane 7, a negative porous electrode 18, a negative electrode frame cover 17, a negative electrode frame 16, a bipolar plate B8, a current collecting plate B9, and a liquid conducting end plate B10. Seals are provided between the components to prevent leakage inside and outside the battery.

[0035] A circular liquid flow battery stack, comprising a liquid conducting end plate A1, a current collecting plate A2, a bipolar plate A3, a positive electrode frame 4, a positive electrode frame cover 5, a positive porous electrode 6, an ion exchange membrane 7, a plurality of repeated single sections, a negative porous electrode 18, a negative electrode frame cover 17, a negative electrode frame 16, a bipolar plate B8, a current collecting plate B9, and a liquid conducting end plate B10;

[0036] The above-mentioned repeating single section is composed of a negative porous electrode 18, a negative electrode frame cover 17, a negative electrode frame 16, a common bipolar plate, a positive electrode frame 4, a positive electrode frame cover 5, a positive porous electrode 6, and an ion exchange membrane 7; the common bipolar plate is a bipolar plate A with a positive electrode liquid outlet hole and a negative electrode liquid outlet hole added thereto, and the position of the liquid outlet hole is the same as that of the bipolar plate B, that is, the common bipolar plate has a positive electrode liquid inlet hole, a positive electrode liquid outlet hole, a negative electrode liquid inlet hole, and a negative electrode liquid outlet hole at the same time.

[0037] The components of the circular liquid flow battery or circular liquid flow battery stack are circular structures, and the projections of the centers of the circles of the components coincide with each other on the horizontal plane. Bolts are used to connect and fasten the components through bolt holes such as the liquid guide end plate A bolt hole 11, the current collecting plate A bolt hole 21, the bipolar plate A bolt hole 31, the positive electrode frame bolt hole 41, the ion exchange membrane bolt hole 71, the bipolar plate B bolt hole 81, the current collecting plate B bolt hole 91, the liquid guide end plate B bolt hole 101, and the ordinary bipolar plate bolt hole 111;

[0038] The positive electrode electrolyte of the circular liquid flow battery is introduced from an external container, and enters the positive electrode frame 4 from the positive electrode liquid inlet hole 12 connected to the side, the positive electrode liquid inlet hole 13 of the liquid guide end plate A, the positive electrode liquid inlet hole 22 of the current collecting plate A, the positive electrode liquid inlet hole 32 of the bipolar plate A, and the positive electrode liquid inlet hole 42. It flows through the liquid inlet channel of the positive electrode frame into the long arc side of the semicircular or fan-shaped positive porous electrode 6 to participate in the reaction, and then the electrolyte flows from the semicircular or fan-shaped positive porous electrode 6 to the long arc side of the semicircular or fan-shaped positive porous electrode 6. The liquid flows out along the short arc edge and enters the central liquid collecting area of the positive electrode frame 4. Then, it flows from the liquid outlet channel of the positive electrode frame 4 into the positive electrode liquid outlet hole 44, the positive electrode liquid outlet hole 52 of the positive electrode frame cover, the positive electrode liquid outlet hole 74 of the ion exchange membrane, the positive electrode liquid outlet hole of the negative electrode frame 16, the positive electrode liquid outlet hole 82 of the bipolar plate B, the positive electrode liquid outlet hole 92 of the current collecting plate B, the positive electrode liquid outlet hole 103 of the liquid guide end plate B, and returns to the external container through the positive electrode liquid outlet hole 102 connected to the side.

[0039] The negative electrode electrolyte of the circular liquid flow battery is introduced from an external container and enters the negative electrode frame 16 from the negative electrode liquid inlet hole 14 connected to the side, the negative electrode liquid inlet hole 15 of the liquid guide end plate A, the negative electrode liquid inlet hole 23 of the current collecting plate A, the negative electrode liquid inlet hole 33 of the bipolar plate A, the negative electrode liquid inlet hole 43 of the positive electrode frame 4, the negative electrode liquid inlet hole 73 of the ion exchange membrane, etc., and flows into the long arc side of the semicircular or fan-shaped negative electrode porous electrode 18 through the liquid inlet channel of the negative electrode frame 16 to participate in the reaction. Then the electrolyte flows out from the short arc side of the semicircular or fan-shaped negative electrode porous electrode 18 and enters the central liquid collection area of the negative electrode frame 16, and then enters the negative electrode liquid outlet hole 83 of the bipolar plate B, the negative electrode liquid outlet hole 93 of the current collecting plate B, the negative electrode liquid outlet hole 105 of the liquid guide end plate B, the negative electrode liquid outlet hole 104 connected to the side, etc. and returns to the external container;

[0040] The flow direction of the positive and negative electrolytes in the circular liquid flow battery stack is roughly the same as that of the circular liquid flow battery, and it needs to pass through several repeated single-cell structures;

[0041] Assemble the circular flow battery stack as described above; electrode area: 900 cm 2 , Number of sections: 15 The stack adopts face sealing, the sealing material is fluororubber, and the membrane material is Nafion115.

[0042] The assembled stack is 310mm thick, leak-free, and boasts a charge-discharge coulombic efficiency of 96.6%, a voltage efficiency of 84.3%, and an energy efficiency of 81.4%. Compared to test data from a Chinese patent (CN105742665 B), the circular stack of the present invention demonstrates significant advantages in coulombic efficiency, voltage efficiency, and energy efficiency.

[0043] The above description is only a preferred specific implementation method of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, can make equivalent replacements or changes based on the technical solutions and inventive concepts of the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A circular liquid flow battery, comprising a liquid conducting end plate A (1), a current collecting plate A (2), a bipolar plate A (3), a positive electrode frame (4), a positive electrode frame cover (5), a positive porous electrode (6), an ion exchange membrane (7), a negative porous electrode (18), a negative electrode frame cover (17), a negative electrode frame (16), a bipolar plate B (8), a current collecting plate B (9), and a liquid conducting end plate B (10) stacked in sequence, characterized in that: Bolt holes are respectively provided at the center positions of the liquid conducting end plate A (1), the current collecting plate A (2), the bipolar plate A (3), the positive electrode frame (4), the ion exchange membrane (7), the negative electrode frame (16), the bipolar plate B (8), the current collecting plate B (9) and the liquid conducting end plate B (10). The liquid conducting end plate A (1) is provided with a side externally connected positive electrode liquid inlet hole (12) and a side externally connected negative electrode liquid inlet hole (14). The liquid conducting end plate B (10) is provided with a side externally connected positive electrode liquid inlet hole (12) and a side externally connected negative electrode liquid inlet hole (14).

2. A circular liquid flow battery according to claim 1, characterized in that: The liquid-conducting end plate A (1) is a circular flat plate, and 2n holes are evenly opened at a certain distance from the center of the liquid-conducting end plate A (1) and close to one side of the liquid-conducting end plate A (1), n holes are positive electrode liquid inlet holes, n holes are negative electrode liquid inlet holes, n ≥ 2, and the setting of n is the same as the number of electrode partitions of the circular liquid flow battery.

3. A circular liquid flow battery as claimed in claim 1, characterized in that: The current collecting plate A (2) and the bipolar plate A (3) are circular flat plates, and 2n through holes are provided at positions corresponding to the positive electrode liquid inlet hole (13) and the negative electrode liquid inlet hole (15) of the liquid conducting end plate A, where n≥2.

4. A circular liquid flow battery according to claim 1, characterized in that: The positive electrode frame (4) and the negative electrode frame (16) are circular flat plates. 4n through holes are provided in the circular flat plate area, n of which are positive electrode liquid inlet holes (42), n of which are negative electrode liquid inlet holes (43), n of which are positive electrode liquid outlet holes (44), and n of which are negative electrode liquid outlet holes (45). n≥2, and the setting of n is the same as the number of electrode partitions of a circular liquid flow battery. N brackets are provided to connect the central liquid collection area and the outer annular area. The brackets and the outer annular area enclose an area where a semicircular or fan-shaped porous electrode is placed. A groove is provided in the outer annular area as a liquid inlet channel, one end of which is connected to the positive electrode liquid inlet hole (42) and the negative electrode liquid inlet hole (43), and the other end is connected to the porous electrode placement area. A groove is provided on the bracket as a liquid outlet channel, one end of which is connected to the central liquid collection area, and the other end is connected to the positive electrode liquid outlet hole (44) and the negative electrode liquid outlet hole (45).

5. A circular liquid flow battery as claimed in claim 1, characterized in that: The positive porous electrode (6) and the negative porous electrode (18) are n semicircular or fan-shaped electrodes, n≥2, and the electrolyte flows into the electrodes from the long arc side of the semicircle or fan to participate in the reaction, and the electrolyte flows out of the electrodes from the short arc side of the semicircle or fan.

6. A circular liquid flow battery as claimed in claim 1, characterized in that: The positive electrode frame cover plate (5) and the negative electrode frame cover plate (17) are respectively used as sealing covers to buckle onto the liquid inlet flow channel, liquid outlet flow channel and liquid collection area on the positive electrode frame (4) and the negative electrode frame (16).

7. A circular liquid flow battery as claimed in claim 1, characterized in that: The ion exchange membrane is circular and has 4n through holes corresponding to the positive or negative electrode frame, where n≥2, n being the positive electrode liquid inlet holes (72) of the ion exchange membrane, n being the negative electrode liquid inlet holes (73) of the ion exchange membrane, n being the positive electrode liquid outlet holes (74) of the ion exchange membrane, and n being the negative electrode liquid outlet holes (75) of the ion exchange membrane, wherein the setting of n is the same as the number of electrode partitions of the circular liquid flow battery.

8. A circular liquid flow stack, characterized in that: It is composed of two or more circular liquid flow batteries according to any one of claims 1 to 7 connected in series.

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