A flow battery flow frame assembly and flow battery stack

Abstract

The application provides a flow battery flow frame assembly and a flow battery stack. The flow frame assembly comprises a flow frame body and cover plates arranged on both sides of the surface of the flow frame body. The flow frame body has a liquid inlet, a liquid outlet, an electrode area, an inlet flow channel groove and an outlet flow channel groove. The electrode area has a flow uniforming cavity first flared mouth area and a flow uniforming cavity second flared mouth area. The cover plates are respectively surrounded with the inlet flow channel groove, the outlet flow channel groove, the first flared mouth area and the second flared mouth area of the flow frame body to form an inlet long and narrow flow channel, an outlet long and narrow flow channel, a first flared mouth flow channel and a second flared mouth flow channel. The flow battery stack comprises a plurality of single cells connected in series. Each single cell comprises an electrode, an ion exchange diaphragm, a bipolar plate and a flow frame assembly.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of battery, and particularly relates to a flow battery flow frame assembly and a flow battery stack. BACKGROUND

[0002] The flow battery is a new type of storage battery, which is a high-performance storage battery with positive and negative electrolyte separated and circulated. The flow battery has the characteristics of high capacity, wide use field (environment) and long cycle service life. The redox flow battery is a new type of large-capacity electrochemical energy storage device which is being actively developed. It is different from the battery using solid material electrode or gas electrode. The active material of the redox flow battery is a flowing electrolyte solution. The most significant feature of the redox flow battery is large-scale storage. Under the situation of high demand for the use of renewable energy, it can be predicted that the flow battery will usher in a period of rapid development. The iron-chromium redox flow battery is a kind of redox flow battery, which has the advantages of long service life, high energy conversion efficiency, good safety, environmental friendliness and the like, and can be used for large-scale energy storage system matched with wind power generation and photovoltaic power generation. It is one of the main choices for peak shaving and load balancing of power grid.

[0003] The flow channel design of the flow frame is a difficulty in the design of the iron-chromium battery. When designing the flow channel, the following points should be considered: (1) uniform distribution of fluid, which enables the electrolyte to flow uniformly through the graphite felt electrode; (2) small current loss to avoid low energy conversion efficiency caused by large current loss; (3) small fluid resistance to reduce the energy loss of the pump; (4) high cost and great technical difficulty in the preparation of large-area flow frame by molding technology.

[0004] In the prior art, patent CN200910015370.1 "A kind of flow device of all-vanadium ion redox flow battery" uses flow channel with bending and multiple detours, which reduces the current loss caused by electrolyte conduction when the battery is self-discharged;Patent CN201120035036.5 "A kind of flow frame device for all-vanadium flow battery" uses S-shaped flow channel, which prolongs the distance of electrolyte in the flow frame, increases the effective resistance of the battery during self-discharge and reduces the fluid resistance;Patent CN201220689925.8 "A kind of flow frame device and vanadium battery containing the device" relates to a kind of central symmetric rotary flow channel;In patent CN201310656248.9 "Flow frame assembly and flow battery", the flow channel is located in the internal flow channel between the two sides of the flow frame assembly, and the electrolyte only flows in the internal flow channel of the flow frame, so that the electrolyte is isolated from the ion exchange membrane, avoiding the problem of positive and negative electrolyte liquid mixing. The flow channels in these patents cannot achieve uniform flow of electrolyte in the electrode, which often causes incomplete utilization of carbon felt area, large pressure difference in single cell in the stack and other problems. Patent CN201220672976.X "A kind of flow frame device and the stack composed of the same" uses primary flow distribution channel and multi-stage flow distribution channel, which plays a certain role in standardizing electrolyte, but the flow uniformity is limited and there is a problem of large current loss during self-discharge. At the same time, the existing technology cannot solve the problem of high cost and high technical difficulty of large-area flow frame prepared by molding technology. SUMMARY

[0005] The purpose of the present application is to solve the problems existing in the prior art, and to provide a flow battery flow frame assembly and a flow battery stack.

[0006] The technical solution for achieving the purpose of the present application is as follows:

[0007] A flow battery flow frame assembly, comprising: a flow frame body and a cover plate arranged on the two side surfaces of the flow frame body, wherein:

[0008] The flow frame body has a liquid inlet, a liquid outlet, an electrode area, an inlet flow channel groove and an outlet flow channel groove; the inlet flow channel groove and the outlet flow channel groove are centrally symmetrically arranged on the opposite sides of the flow frame body; the electrode area is an open hole having a flow uniforming cavity first horn mouth area and a flow uniforming cavity second horn mouth area; the first horn mouth area and the second horn mouth area are axially symmetric structures; the liquid inlet is communicated with the first horn mouth area through the inlet flow channel groove, and the liquid outlet is communicated with the second horn mouth area through the outlet flow channel groove;

[0009] The cover plate and the inlet flow channel groove, the outlet flow channel groove, the first horn mouth area and the second horn mouth area are enclosed to form an inlet long and narrow flow channel, an outlet long and narrow flow channel, a first horn mouth flow channel and a second horn mouth flow channel, and the inlet long and narrow flow channel and the outlet long and narrow flow channel are centrally symmetrically arranged, and the first horn mouth flow channel and the second horn mouth flow channel are axially symmetrically arranged.

[0010] The electrode area is used for accommodating the electrode. Through the above structure, the electrolyte enters the inlet narrow flow channel through the liquid inlet, and then flows through the first trumpet-shaped flow channel, the electrode area, the second trumpet-shaped flow channel and the outlet narrow flow channel in sequence, and then flows out from the liquid outlet.

[0011] The two sides of the liquid flow frame assembly are respectively provided with ion exchange diaphragms and bipolar plates.

[0012] Preferably, the material of the liquid flow frame body has flexibility and self-sealing performance. Preferably, the material of the liquid flow frame body is selected from anisotropic materials with ABA structure and has a surface hardness of 65-110A. As an example, the anisotropic material with ABA structure is an elastic material such as TPE, TPO or silicone resin. Further preferably, the anisotropic material with ABA structure is a TPO elastic material and has a surface hardness of 75-95A.

[0013] As an example, the material of the cover plate is selected from one of polypropylene, chlorinated polyvinyl chloride, hard polyvinyl chloride, polytetrafluoroethylene, epoxy resin or glass fiber plate.

[0014] The application also provides a liquid flow battery stack comprising a plurality of single cells connected in series, each single cell comprising an electrode, an ion exchange diaphragm, a bipolar plate and the liquid flow frame assembly described above; wherein:

[0015] The ion exchange diaphragm and the bipolar plate are respectively arranged on opposite sides of the liquid flow frame assembly;

[0016] The electrode is arranged in the electrode area, and one side of the electrode in the vertical direction of the thickness of the electrode is tightly attached to one plane of the bipolar plate, and the other side of the electrode is in contact with the ion exchange diaphragm.

[0017] Preferably, the bipolar plate is a rectangular bipolar plate, which is wrapped with a wrapping type sealing structure to avoid hard contact with the cover plate.

[0018] The wrapping type sealing structure is preferably a sealing ring made of ethylene-propylene-diene rubber (EPDM) material.

[0019] Further, the liquid flow battery stack further comprises a battery stack interface, end plates at both ends and current collecting plates adjacent to the end plates, wherein: the battery stack interface comprises a positive electrolyte inlet, a negative electrolyte inlet, a positive electrolyte outlet and a negative electrolyte outlet.

[0020] Further, the single cell further comprises a sealing gasket, which is arranged on both sides of the liquid flow frame assembly, the ion exchange diaphragm and the bipolar plate.

[0021] The material of the sealing gasket is preferably a rubber elastomer.

[0022] Preferably, the flow battery stack adopts CrCl3 solution and FeCl2 solution as electrolyte, and the ion exchange diaphragm is selected from one of the following: perfluorosulfonic acid proton exchange membrane, PSSS (poly sulfostyrene acid sodium) modified polypropylene membrane (for example, Daramic LLC, USA), styrene-divinyl benzene copolymer anion exchange membrane, and styrene-divinyl benzene copolymer cation exchange membrane (for example, domestic JAM type anion exchange membrane and JCM type cation exchange membrane).

[0023] The end plate serves to fix the plurality of single cells. As an example, the end plate is made of polypropylene, epoxy resin or glass fiber plate, and has a thickness of 1-10 cm.

[0024] The flow battery stack is externally provided with a liquid storage tank and a circulating pump, and the circulating pump preferably has a flow rate of 1-108 L / min and a head of 1-10 m.

[0025] The present application has the following beneficial effects:

[0026] Through the combined design of the flow frame, the integrated molding process is avoided, and the production of the stack is simplified.

[0027] The wide flow equalization cavity is provided, so that the electrolyte is uniformly distributed in the reaction carbon felt. The overall liquid passing condition of the carbon felt is consistent, and the dead angle and polarization phenomenon are avoided, so that the electrolyte is fully utilized, and the consistency of the stack is ensured.

[0028] The energy storage system formed by the battery stack has the following advantages: the rated discharge power of the system reaches 20 kW, the charge-discharge energy conversion efficiency reaches 75%, the actual measured current loss is less than 2.5%, the actual measured charge-discharge cycle is more than 100 times without attenuation, the theoretical service life is more than 10,000 times, the operating temperature range can reach-20℃-70℃, and the stack pressure drop is about 50 kPa. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 : The structure of the flow battery stack of one embodiment of the present application is shown in the figure.

[0030] Figure 2 : Figure 1 : The front view of the flow battery stack.

[0031] Figure 3 : The exploded view of the flow battery stack of one embodiment of the present application.

[0032] Figure 4 : The structure of the flow frame body of one embodiment of the present application is shown in the figure.

[0033] Figure 5 : The structure of the sealing gasket of one embodiment of the present application is shown in the figure.

[0034] Figure 6The charge-discharge curve of the flow battery stack of embodiment 1.

[0035] In the figure, 1 is a battery stack interface, 2 is an end plate, 3 is a current collector plate, 4 is an ion exchange diaphragm, 5 is a cover plate, 6 is a flow frame body, 7 is an electrode, 8 is a bipolar plate, 61 is an inlet flow channel groove, 62 is an outlet flow channel groove, 63 is an electrode area, 64 is a liquid inlet, 65 is a liquid outlet, 611 is a first horn area, and 621 is a second horn area. DETAILED DESCRIPTION

[0036] The technical solutions of the present application are further described below with preferred embodiments.

[0037] Those skilled in the art should know that the following embodiments are only used to illustrate the present application, but not to limit the scope of the present application.

[0038] Embodiment 1

[0039] A Fe / Cr system liquid flow battery stack is composed of a plurality of single cells connected in series (100 single cells connected in series in this embodiment), each single cell is a Fe / Cr redox flow battery, and Fe 2+ / Fe 3+ , Cr 2 + / Cr 3+ are used as the positive and negative electrodes of the battery. The liquid flow battery stack has an external liquid storage tank and a circulating pump, the positive / negative electrolyte is stored in two liquid storage tanks respectively, the electrolyte is driven by an acid-resistant liquid circulating pump to the reaction site (battery stack) and then returned to the liquid storage tank to form a circulating liquid flow circuit, so as to realize the charging and discharging process. The electrolyte used is FeCl2 and CrCl3, and the theoretical calculation is according to the initial Fe 2+ concentration of 1.0 mol / L.

[0040] Referring to Figures 1-2 , the battery stack includes a plurality of single cells connected in series, a battery stack interface 1, end plates 2 at both ends, and current collector plates 3 adjacent to the end plates 2. Four battery stack interfaces 1 are opened on the end plates 2, which are used as the positive electrolyte inlet, the negative electrolyte inlet, the positive electrolyte outlet, and the negative electrolyte outlet respectively.

[0041] As shown in Figures 3-4 , each single cell includes an electrode 7, an ion exchange diaphragm 4, a bipolar plate 8, and a flow frame assembly; wherein the flow frame assembly includes a flow frame body 6 and a cover plate 5 arranged on both sides of the surface of the flow frame body 6.

[0042] Ion exchange membrane 4 and bipolar plate 8 are arranged on opposite sides of the flow frame assembly respectively; electrode 7 is arranged in electrode area 63 of flow frame body 6, and one side of electrode 7 in the vertical direction of its thickness is tightly attached to one plane of bipolar plate 8, and the other side of electrode 7 is in contact with ion exchange membrane 4. Bipolar plate 8 is a rectangular bipolar plate, which is wrapped with a wrapping type sealing structure to avoid hard contact with cover plate 5. The wrapping type sealing structure is a sealing ring of ethylene propylene diene rubber (EPDM) material. Flow frame body 6 has liquid inlet 64, liquid outlet 65, electrode area 63, first horn mouth area 611, second horn mouth area 621, inlet flow channel groove 61 and outlet flow channel groove 62; inlet flow channel groove 61 and outlet flow channel groove 62 are symmetrically arranged on opposite sides of flow frame body 6; electrode area 63 is an open hole with flow equalizing cavity first horn mouth area 611 and flow equalizing cavity second horn mouth area 621; first horn mouth area 611 and second horn mouth area 621 are axially symmetric structures; liquid inlet 64 is in communication with first horn mouth area 611 through inlet flow channel groove 61, and liquid outlet is in communication with second horn mouth area 621 through outlet flow channel groove 62;

[0043] Cover plate 5 and inlet flow channel groove 61, outlet flow channel groove 62, first horn mouth area 611 and second horn mouth area 621 form inlet long flow channel, outlet long flow channel, first horn mouth flow channel and second horn mouth flow channel respectively, and inlet long flow channel and outlet long flow channel are centrally symmetrically arranged, and first horn mouth flow channel and second horn mouth flow channel are axially symmetrically arranged.

[0044] In each single cell, electrodes 7 on the left and right sides of ion exchange membrane 4 are respectively used as the positive and negative electrodes of the cell, and the flow frame assemblies containing electrodes 7 are respectively filled with the corresponding positive and negative electrolyte.

[0045] When assembling the cell stack, it is required that ion exchange membrane 4 and electrode 7, and electrode 7 and bipolar plate 8 are in full contact.

[0046] The single cell further comprises a sealing gasket (the structure of which is shown in Figure 5 The sealing gasket is arranged on the two sides of the flow frame assembly, ion exchange membrane 4 and bipolar plate 8.

[0047] The size of flow frame body 6 is: length 1120 mm, width 520 mm, and thickness 2.5 mm.

[0048] The size of ion exchange membrane 4 is: length 1120 mm, and width 450 mm.

[0049] The size of electrode 7 (carbon felt) is: length 1050 mm, width 250 mm, and thickness 4 mm.

[0050] In the battery stack, the ion exchange membrane 4 is a perfluorosulfonic acid resin membrane (Nafion 212), the end plate 2 of the battery stack is made of epoxy resin, the thickness is 4 cm, and the cover plate 5 is PP material. The liquid flow frame body 6 is made of anisotropic material with ABA structure, the A layer is TPO (thermoplastic polyolefin) with a surface hardness of 90A, and the B layer is PP material.

[0051] The battery stack is externally connected to a liquid storage tank and a circulating pump, and the circulating pump is model MX100 (manufacturer: Yeweiqi Company). The liquid storage tank is connected to the battery stack interface 1, and the positive and negative electrolytes are transported to the battery stack through the circulating pump.

[0052] The positive and negative electrolytes of the battery stack structure independently operate through their respective flow channels to form a loop. The electrolyte flows into the inlet narrow flow channel through the liquid inlet 64, enters the first horn inlet flow channel, and then enters the electrode area 63 through the first horn inlet flow channel. The electrolyte uniformly flows to the electrode 7, and then flows through the second horn inlet flow channel and the outlet narrow flow channel in turn and flows out from the liquid outlet 65. During the charging process, an external voltage is applied to the current collector plate 3, causing the ions in the electrolyte to change in valence, thereby achieving the purpose of storing energy, i.e., the charging process. During discharging, the potential difference between the positive and negative electrolyte tanks causes the ions inside the electrolyte to change in valence, and the charge moves directionally to generate an electric current that is output through the current collector plate 3, i.e., the discharging process.

[0053] The battery stack of this embodiment has a rated discharge power of 20 kW, a charge-discharge energy conversion efficiency of 80%, and no attenuation after 100 charge-discharge cycles, with a theoretical service life of more than 10,000 times. The operating temperature range can reach -20°C to 70°C, and the operating pressure is about 45 kPa. The charge-discharge curve of one cycle is shown in Figure 6 .

[0054] Example 2:

[0055] The battery stack structure is the same as that of Example 1, except that the battery stack contains 100 single cells connected in series. The electrolyte used is FeCl2 and CrCl3, and the theoretical calculation is based on the initial Fe 2+ concentration of 1.2 mol / L.

[0056] The size of the liquid flow frame body 6 is: length 1120 mm, width 520 mm, and thickness 2.5 mm.

[0057] The size of the ion exchange membrane 4 is: length 1120 mm, width 450 mm.

[0058] The size of the electrode 7 (carbon felt) is: length 1050 mm, width 250 mm, and thickness 4 mm.

[0059] The ion exchange membrane 4 in the battery stack is a sulfonated styrene modified PP porous membrane, the end plate 2 of the battery stack is made of epoxy resin, the thickness is 4 cm, and the cover plate 5 is a glass fiber epoxy material. The liquid flow frame body 6 is made of anisotropic material with an ABA structure, the A layer is TPO with a surface hardness of 75A, and the B layer is PP material.

[0060] The battery stack is externally connected to a liquid storage tank and a circulating pump. The circulating pump is model MX100 (manufacturer: Yeweiqi Company). The liquid storage tank is connected to the battery stack through the interface 1, and the positive and negative electrolytes are transported to the battery stack through the circulating pump.

[0061] The battery stack of the embodiment has a rated discharge power of 20 kW, a charge-discharge energy conversion efficiency of 77%, and no attenuation is found in the actual measurement of charge-discharge cycles for more than 100 times.

[0062] Embodiment 3:

[0063] The battery stack structure is the same as that in Embodiment 1, except that the battery stack contains 100 single cells connected in series.

[0064] The size of the liquid flow frame body 6 is: length 1120 mm, width 520 mm, and thickness 2.5 mm.

[0065] The size of the ion exchange membrane 4 is: length 1120 mm, width 450 mm.

[0066] The size of the electrode 7 (carbon felt) is: length 1050 mm, width 250 mm, and thickness 4 mm.

[0067] The ion exchange membrane 4 in the battery stack is a sulfonated styrene modified PP porous membrane, the end plate 2 of the battery stack is made of epoxy resin, the thickness is 4 cm, and the cover plate 5 is a glass fiber epoxy material. The liquid flow frame body 6 is made of anisotropic material with an ABA structure, the A layer is TPO with a surface hardness of 75A, and the B layer is PP material.

[0068] The electrolyte used is FeCl2 and CrCl3. The theoretical calculation is based on the initial Fe 2+ The concentration is 1.2 mol / L.

[0069] The battery stack is externally connected to a liquid storage tank and a circulating pump. The circulating pump is model MX100 (manufacturer: Yeweiqi Company). The liquid storage tank is connected to the battery stack through the interface 1, and the positive and negative electrolytes are transported to the battery stack through the circulating pump.

[0070] The battery stack of the embodiment has a rated discharge power of 20 kW, a charge-discharge energy conversion efficiency of 77%, and no attenuation is found in the actual measurement of charge-discharge cycles for more than 100 times.

[0071] The above embodiments are only used for illustrating the present application, and are not intended to limit the present application. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present application. Therefore, all equivalent technical solutions belong to the scope of the present application, and the patent protection scope of the present application should be defined by the claims.

Claims

1. A flow battery flow frame assembly, characterized by, The application relates to a liquid flow frame assembly for a flow battery, which comprises: a liquid flow frame body (6) and a cover plate (5) arranged on the surface of the liquid flow frame body (6), wherein: the liquid flow frame body (6) is provided with a liquid inlet (64), a liquid outlet (65), an electrode area (63), an inlet flow channel groove (61) and an outlet flow channel groove (62); the inlet flow channel groove (61) and the outlet flow channel groove (62) are symmetrically arranged on opposite sides of the liquid flow frame body (6); the electrode area (63) is an opening and is provided with a flow uniformizing cavity first horn mouth area (611) and a flow uniformizing cavity second horn mouth area (621); the first horn mouth area (611) and the second horn mouth area (621) are axially symmetrical; the liquid inlet (64) is communicated with the first horn mouth area (611) through the inlet flow channel groove (61), and the liquid outlet (65) is communicated with the second horn mouth area (621) through the outlet flow channel groove (62); the cover plate (5) is surrounded by the inlet flow channel groove (61), the outlet flow channel groove (62), the first horn mouth area (611) and the second horn mouth area (621) to form an inlet long and narrow flow channel, an outlet long and narrow flow channel, a first horn mouth flow channel and a second horn mouth flow channel, and the inlet long and narrow flow channel and the outlet long and narrow flow channel are centrally symmetrically arranged, and the first horn mouth flow channel and the second horn mouth flow channel are axially symmetrically arranged; the material of the liquid flow frame body (6) is flexible and self-sealing; the material of the cover plate (5) is selected from one of polypropylene, chlorinated polyvinyl chloride, hard polyvinyl chloride, polytetrafluoroethylene, epoxy resin and glass fiber plate.

2. The liquid flow frame assembly of claim 1, wherein, The material of the liquid flow frame body (6) is selected from an ABA structure anisotropic material and has a surface hardness of 65-110A.

3. The liquid flow frame assembly of claim 2, wherein, The A layer of the ABA structure anisotropic material is a TPE, TPO or silicon resin elastic material.

4. The liquid flow frame assembly of claim 3, wherein, The A layer of the ABA structure anisotropic material is a TPO elastic material and has a surface hardness of 75-95A.

5. A flow battery stack comprising a plurality of single cells connected in series, characterized in that, Each single cell comprises an electrode (7), an ion exchange diaphragm (4), a bipolar plate (8) and the liquid flow frame assembly according to any one of claims 1-4; wherein: the ion exchange diaphragm (4) and the bipolar plate (8) are arranged on opposite sides of the liquid flow frame assembly respectively; the electrode (7) is arranged in the electrode area (63), and one side of the electrode (7) in the vertical direction of the thickness of the electrode (7) is closely attached to one plane of the bipolar plate (8), and the other side of the electrode (7) is in contact with the ion exchange diaphragm (4); the bipolar plate (8) is a rectangular bipolar plate, and a wrapping type sealing structure is wrapped around the four sides of the bipolar plate (8) to avoid hard contact with the cover plate (5).

6. The flow battery stack of claim 5, wherein, The flow battery stack further comprises a stack interface (1), end plates (2) located at two ends and current collecting plates (3) close to the end plates (2), wherein: the stack interface (1) comprises a positive electrolyte inlet, a negative electrolyte inlet, a positive electrolyte outlet and a negative electrolyte outlet.

7. The flow battery stack of claim 5, wherein, The single cell further comprises a sealing gasket, and the sealing gasket is arranged on the two sides of the liquid flow frame assembly, the ion exchange diaphragm (4) and the bipolar plate (8).

8. The flow battery stack of claim 5, wherein, The CrCl3 solution and the FeCl2 solution are used as electrolyte, and the ion exchange diaphragm (4) is selected from one of the following: a perfluorosulfonic acid proton exchange membrane, a PSSS modified polypropylene membrane, a styrene-divinylbenzene copolymer anion exchange membrane, and a styrene-divinylbenzene copolymer cation exchange membrane.

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