Zinc-nickel single-flow battery monomer and galvanic pile structure of zinc-nickel single-flow battery

Abstract

The invention relates to the technical field of flow batteries, and discloses a zinc-nickel single flow battery monomer and a galvanic pile structure of the zinc-nickel single flow battery, the single flow battery monomer comprises an integrated electrode frame, a nickel electrode, a zinc electrode and a diaphragm for separating the zinc electrode from the nickel electrode are arranged in an electrode cavity of the integrated electrode frame, and the two sides of the integrated electrode frame are respectively connected with the polar plates in a sealing manner through sealing rings. The method has the advantages that the production cost is reduced, and the stack assembly efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of flow batteries, and particularly to a zinc-nickel single-flow battery cell and a stack structure of a zinc-nickel single-flow battery. Background Art

[0002] The power generation from renewable energy sources such as wind energy and solar energy will surely become the main force of future energy. However, the intermittent and unstable characteristics of renewable energy have brought major challenges to the stable operation of the power system. Energy storage technology is an effective means to help achieve the efficient utilization of renewable energy and the stable operation of the power system. Compared with physical energy storage technologies such as pumped-storage energy storage, the more flexible electrochemical battery energy storage technology has gradually attracted people's attention. Among various battery energy storage technologies, flow batteries have become large-scale battery energy storage technologies with great development potential due to their long life, high safety, and high energy efficiency.

[0003] The zinc-nickel flow energy storage battery mainly consists of a stack unit, an electrolyte unit, an electrolyte storage and supply unit, a battery management system, a thermal management system, etc. Among them, the stack is the core place for the conversion of electrical energy and chemical energy, and is generally composed of several or dozens of single cells stacked together. The single cell of the zinc-nickel flow battery is the most basic unit for assembling the stack. As disclosed in CN 102867978 A, the positive and negative electrode materials of the single cell are separated by a diaphragm. The diaphragm allows the electrolyte to pass through to form a current loop and separates the zinc electrode and the nickel electrode to prevent short circuit. On both sides of this diaphragm, there are configured electrode materials, gaskets, bipolar plates, current collector plates, insulating plates, end plates, nuts, etc. To ensure sealing and avoid electrolyte leakage, as Figure 1 shown, gaskets need to be configured on both sides of the electrode frame, both sides of the bipolar plate, and both sides of the diaphragm, which results in a complex structure, low sealing reliability, and high sealing cost. Summary of the Invention

[0004] The purpose of the present invention is to overcome the problem that gaskets need to be configured on both sides of the electrode frame, both sides of the bipolar plate, and both sides of the diaphragm in the prior art, which leads to a complex structure and high sealing cost. A zinc-nickel single-flow battery cell and a stack structure of a zinc-nickel single-flow battery are provided, which have the advantages of reducing production costs and improving the stack assembly efficiency.

[0005] To achieve the above purpose, on the one hand, the present invention provides a zinc-nickel single-flow battery cell. The single-flow battery cell includes an integrated electrode frame. In the electrode cavity of the integrated electrode frame, there are installed a nickel electrode, a zinc electrode, and a diaphragm that separates the zinc electrode from the nickel electrode. Both sides of the integrated electrode frame are hermetically connected to the plates through sealing rings respectively.

[0006] In some embodiments, a liquid inlet, a liquid inlet flow channel, and a liquid inlet buffer tank are sequentially communicated in the liquid inlet side of the integrated electrode frame. The liquid inlet buffer tank is provided with a plurality of liquid inlet guiding bodies arranged at intervals in the X direction. A gap between two adjacent liquid inlet guiding bodies forms a liquid inlet channel. The liquid inlet buffer tank is communicated with the electrode cavity through the liquid inlet channel. Among them, the sizes of two adjacent liquid inlet guiding bodies in the X direction are not equal.

[0007] In some embodiments, a plurality of the liquid inlet guiding bodies are arranged in at least one group. The liquid inlet flow channel is provided with at least one liquid inlet flow channel outlet communicated with the liquid inlet buffer tank, and each liquid inlet flow channel outlet is correspondingly provided with a group of liquid inlet guiding bodies.

[0008] In some embodiments, in each group of liquid inlet guiding bodies, the size of the liquid inlet guiding body in the X direction decreases as the distance from the liquid inlet flow channel outlet increases.

[0009] In some embodiments, in each group of the liquid inlet guiding bodies, the size of the liquid inlet channel in the X direction increases as the distance from the liquid inlet flow channel outlet increases.

[0010] In some embodiments, the liquid inlet guiding body is set as a cuboid.

[0011] In some embodiments, the liquid inlet side and the liquid outlet side of the integrated electrode frame are asymmetrically arranged.

[0012] In some embodiments, the liquid outlet side is provided with a liquid outlet, a liquid outlet flow channel, and a liquid outlet buffer tank. Among them, the liquid outlet is communicated with the liquid outlet buffer tank through the liquid outlet flow channel. Between the liquid outlet buffer tank and the electrode cavity, liquid outlet guiding bodies are arranged at equal intervals in the X direction. A gap between two adjacent liquid outlet guiding bodies forms a liquid outlet channel. The liquid outlet buffer tank is communicated with the electrode cavity through the liquid outlet channel.

[0013] In some embodiments, the liquid outlet buffer tank is provided with a tapered outlet, and the tapered outlet is communicated with the liquid outlet flow channel.

[0014] In some embodiments, the liquid outlet buffer tank is provided with two symmetric tapered outlets, and two ends of the liquid outlet flow channel are respectively communicated with one of the tapered outlets.

[0015] In some embodiments, two surfaces of the frame body of the integrated electrode frame on the nickel electrode side and the zinc electrode side are respectively provided with a liquid inlet side and a liquid outlet side.

[0016] In some embodiments, the zinc-nickel single liquid flow battery monomer includes a cover plate covering the liquid inlet side and the liquid outlet side. Welding ribs surrounding the electrolyte circulation channel are arranged on the frame body of the integrated electrode frame. The cover plate and the integrated electrode frame are friction welded through the welding ribs.

[0017] In some embodiments, the separator is selected from a cation exchange membrane, an anion exchange membrane, or a porous membrane.

[0018] In some embodiments, the material of the sealing ring is selected from fluororubber, silicone rubber, or expanded elastic tape.

[0019] The second aspect of the present invention provides a stack structure of a zinc-nickel single-flow battery, and the stack structure includes at least two zinc-nickel single-flow battery monomers of the present invention.

[0020] In some embodiments, the electrode compression ratio of the stack structure is 0.1 to 0.5. When the working current density of the battery is higher than 35 mA / cm2, the Coulomb efficiency > 97%, the voltage efficiency > 87.5%, and the energy efficiency > 85%.

[0021] Through the above technical solutions, in the present invention, the electrode frame for installing the positive electrode and the electrode frame for installing the negative electrode are combined into one electrode frame. The separator is attached to the middle position in the thickness direction of the integrated electrode frame. The electrode plate and the electrode frame share the same set of sealing strips, reducing the number of sealing strips used, lowering the production cost, and improving the assembly convenience. Description of the Drawings

[0022] Figure 1 is a schematic diagram of the sealing structure of the (N - 3)th to (N - 2)th sections in an N-section series stack in the prior art (N > 4), where: 1 nickel electrode frame; 2 sealing strip; 3 bipolar plate; 4 zinc electrode frame; 5 separator;

[0023] Figure 2 is the sealing structure of the (N - 3)th to (N - 2)th sections in an N-section series stack of an embodiment of the present invention (N > 4), where: 13 integrated electrode frame; 8 separator; 9 sealing ring; 12 electrode plate;

[0024] Figure 3 is a schematic diagram of the structure of a zinc-nickel single-flow battery monomer of another embodiment of the present invention;

[0025] Figure 4 is Figure 3 a schematic diagram of the structure of an embodiment of the integrated electrode frame in

[0026] Description of the Reference Numerals in the Drawings of the Present Invention

[0027] 8 separator; 9 sealing ring; 10 cover plate; 11 current collector; 12 electrode plate; 13 integrated electrode frame; 131 liquid inlet side; 132 liquid outlet side; 133 electrode cavity; 1311 liquid inlet; 1312 liquid inlet flow channel; 1313 liquid inlet buffer tank; 1314 liquid inlet guiding fluid; 1321 liquid outlet; 1322 liquid outlet flow channel; 1323 liquid outlet buffer tank; 1324 liquid outlet guiding fluid. Detailed implementation mode

[0028] The endpoints and any values within the ranges disclosed herein are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the values between the endpoints of each range, between the endpoints of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0029] In the present invention, unless otherwise stated, the orientation terms such as "upper, lower, left, and right" generally refer to the upper, lower, left, and right shown in the reference drawings; "inner and outer" refer to the inner and outer of the contour of each component itself.

[0030] The present invention discloses a zinc-nickel single-flow battery cell. The single-flow battery cell includes end plates, plate electrodes 12, current collectors 11, an integrated electrode frame 13, current collectors 11, plate electrodes 12, and end plates that are stacked in sequence. Among them, a nickel electrode, a zinc electrode, and a separator 8 that separates the nickel electrode and the zinc electrode are installed in the electrode cavity 133 of the integrated electrode frame 13. Both sides of the integrated electrode frame 13 are hermetically connected to the plate electrode 12 through sealing rings 9 respectively.

[0031] Refer to Figure 1 As shown, to avoid electrolyte leakage by ensuring sealing, sealing gaskets need to be configured on both sides of the electrode frame. In this way, an average of 3 sealing rings are required for one single battery; as Figure 2 As shown, in the present invention, the positive electrode and the negative electrode share one electrode frame, and no sealing material is required between the electrode frame and the separator. The integrated electrode frame and the plate electrode share the same set of sealing strips. In this way, the average number of sealing rings for one single battery is reduced from 3 to 1.5, reducing the sealing cost of the flow energy storage battery and improving the assembly convenience.

[0032] To make the current collector 11 fit more closely to the plate electrode 12, thereby reducing the internal resistance, an inner concave mounting position with the contour shape of the current collector 11 is formed on the plate electrode 12.

[0033] On the frame body of the integrated electrode frame 13, a liquid inlet side 131 and a liquid outlet side 132 are arranged across the electrode cavity 133, and the liquid inlet side 131 and the liquid outlet side 132 are arranged asymmetrically.

[0034] On the two surfaces of the frame body of the integrated electrode frame 13 on the nickel electrode side and the zinc electrode side, a liquid inlet side 131 and a liquid outlet side 132 are respectively arranged.

[0035] Such as Figure 4As shown, the integrated electrode frame 13 includes a substrate and a through hole formed in the middle of the substrate. This through hole serves as the electrode cavity 133 for installing the nickel electrode, zinc electrode, and separator 8. The remaining parts on both sides of the electrode cavity 133 in the Y direction are respectively formed as the liquid inlet side 131 and the liquid outlet side 132. Among them, on the bottom surface of the groove located on the liquid inlet side 131, a plurality of liquid inlet guiding fluids 1314 are arranged at intervals in the X direction. The area between the plurality of liquid inlet guiding fluids 1314 and the groove wall of the groove located on the liquid inlet side 131 is formed as the liquid inlet buffer groove 1313. The substrate is also provided with a liquid inlet 1311 and a liquid inlet flow channel 1312. The liquid inlet 1311 is communicated with the liquid inlet buffer groove 1313 through the liquid inlet flow channel 1312. The gap between two adjacent liquid inlet guiding fluids 1314 is formed as a liquid inlet channel. The liquid inlet buffer groove 1313 is communicated with the electrode cavity 133 through the liquid inlet channel. Among them, the sizes of two adjacent liquid inlet guiding fluids 1314 in the X direction are not equal, so that the spacing between the liquid inlet channels is not equal.

[0036] It should be noted that in the absence of the liquid inlet guiding fluid 1314, the electrolyte cannot flow evenly through the electrode surface. The concentration of the active substance in some areas of the electrode cavity 133 may be too high or too low, resulting in poor transfer of the active substance in the electrolyte, thereby affecting the performance of the flow battery. The electrolyte entering from the liquid inlet 1311 enters the liquid inlet buffer groove 1313 through the liquid inlet flow channel 1312, flows freely therein, and enters the electrode cavity 133 through a plurality of liquid inlet channels formed by a plurality of liquid inlet guiding fluids 1314 arranged at intervals in the X direction. This can guide the flow of the electrolyte, ensure that the electrolyte flows evenly through the electrode surface, reduce concentration polarization, and improve the charge and discharge efficiency and stability of the battery; compared with the equally spaced liquid inlet channels in the prior art, the non-equidistant liquid inlet channels of the present invention can optimize the fluid flow process and improve the flow velocity uniformity in the electrode.

[0037] The liquid inlet flow channel 1312 is provided with N (N≥1) liquid inlet flow channel outlets communicating with the liquid inlet buffer tank 1313. A plurality of liquid inlet guiding bodies 1314 arranged at intervals in the X direction are divided into N groups, and each liquid inlet flow channel outlet is correspondingly provided with a group of liquid inlet guiding bodies 1314. Since the flow velocity at the position of the liquid inlet flow channel outlet is relatively large after the electrolyte flows out of the liquid inlet flow channel outlet, while the flow velocity at the position far from the liquid inlet flow channel outlet in the liquid inlet buffer tank 1313 is relatively small, in order to reduce the velocity gradient in the liquid inlet buffer tank 1313 and ensure that the electrode regions far from the liquid inlet flow channel outlet can all be supplied with sufficient electrolyte, in each group of liquid inlet guiding bodies 1314 in the present invention, the dimension of the liquid inlet guiding body 1314 in the X direction decreases as the distance from the liquid inlet flow channel outlet increases, that is, the spacing between the liquid inlet channels decreases as the distance from the liquid inlet flow channel outlet increases. The liquid flow channel outlet is oppositely provided with the liquid inlet guiding body 1314 having the largest dimension in the X direction, guiding the electrolyte at the liquid inlet flow channel outlet to flow in the X direction so as to be distributed as evenly as possible in the electrode cavity 133, ensuring the uniformity of the active material supply, further reducing the mass transfer loss, and improving the battery voltage efficiency and the system efficiency. It should be noted that the present invention has no special requirements for the gradient of the dimension of the liquid inlet guiding body 1314 in the X direction decreasing as the distance from the liquid inlet flow channel outlet increases. For example, in the direction of increasing distance from the liquid inlet flow channel outlet, the next liquid inlet guiding body 1314 can be reduced by 1%-50% compared with the previous one. Only the next liquid inlet guiding body 1314 being reduced by 10% compared with the previous one is taken as an example in Embodiment 1 of the present invention to illustrate the advantages of the present invention, but the present invention is not limited thereto.

[0038] In the present invention, the dimension of the liquid inlet channels in each group of liquid inlet guiding bodies 1314 in the X direction increases as the distance from the liquid inlet flow channel outlet increases. The liquid inlet channel between the liquid inlet guiding body 1314 farthest from the liquid inlet flow channel outlet and the liquid inlet guiding body 1314 has the largest dimension in the X direction. By adjusting the dimension and spacing of the liquid inlet guiding bodies 1314 according to the distance from the liquid inlet flow channel outlet, the dimension of the liquid inlet guiding bodies 1314 at the position far from the liquid inlet flow channel outlet is smaller and the spacing is larger, providing more flow channel space for the electrode regions far from the liquid inlet flow channel outlet, reducing the flow resistance, which helps to ensure that the electrode regions far from the liquid inlet flow channel outlet can all be supplied with sufficient electrolyte, promoting the exchange of the active material and the electrolyte, ensuring the uniformity of the active material supply, further reducing the mass transfer loss, and improving the battery voltage efficiency. It should be noted that the present invention has no special requirements for the gradient of the dimension of the liquid inlet channels in the X direction increasing as the distance from the liquid inlet flow channel outlet increases. For example, in the direction of increasing distance from the liquid inlet flow channel outlet, the next liquid inlet channel can be increased by 1%-50% compared with the previous one. Only the next liquid inlet channel being increased by 10% compared with the previous one is taken as an example in Embodiment 1 of the present invention to illustrate the advantages of the present invention, but the present invention is not limited thereto.

[0039] The liquid inlet guiding fluid body 1314 is arranged as a cuboid extending along the Y direction, which can effectively reduce the processing difficulty, save the processing cost and play a role in positioning the electrode.

[0040] In the present invention, the liquid inlet flow channel 1312 is arranged as a multi-stage distribution flow channel. Along the material flow direction, the outlet of the last-stage distribution flow channel is formed as a liquid inlet flow channel outlet communicating with the liquid inlet buffer tank 1313, and these liquid inlet flow channel outlets are evenly distributed along the X direction. The liquid inlet 1311 communicates with the main flow channel of the multi-stage distribution flow channel.

[0041] In the present invention, the multi-stage distribution flow channel is as Figure 4 shown, and includes a primary main flow channel extending from the corner of the substrate along the X direction to the middle of the substrate. The end of the primary main flow channel communicates with the middle of the secondary main flow channel. The secondary main flow channel symmetrically extends from the middle of the substrate to both ends along the X direction. Both ends of the secondary main flow channel respectively communicate with two baffle channels extending along the Y direction. The baffle channels communicate with the liquid inlet buffer tank 1313. Among them, a fluid dividing body is arranged in each baffle channel. Thus, after passing through the primary main flow channel, the electrolyte is divided into two left and right strands and respectively enters the baffle channels, and is divided into multiple strands through the fluid dividing body and enters the liquid inlet buffer tank. The fluid dividing body structure for dividing the liquid in the baffle channel into at least two strands is well known to those skilled in the art and does not belong to the core improvement part of this application, so it will not be elaborated here.

[0042] On the bottom surface of the groove on the liquid outlet side 132, a plurality of liquid outlet guiding fluid bodies 1324 are arranged at equal intervals along the X direction. The area between the plurality of liquid outlet guiding fluid bodies 1324 and the groove wall of the groove on the liquid outlet side 132 is formed as a liquid outlet buffer tank 1323. A liquid outlet 1321 and a liquid outlet flow channel 1322 are provided on the substrate. The liquid outlet 1321 is connected to the liquid outlet buffer tank 1323 through the liquid outlet flow channel 1322. The gap between two adjacent liquid outlet guiding fluid bodies 1324 is formed as a liquid outlet channel. The liquid outlet buffer tank 1323 is connected to the electrode cavity 133 through the liquid outlet channel.

[0043] The liquid outlet buffer tank 1323 is provided with a tapered outlet communicating with the liquid outlet flow channel 1322, and the tapered structure is used to accelerate the flow rate of the electrolyte and reduce the battery polarization.

[0044] The liquid outlet 1321 is arranged at the corner of the substrate and is diagonally arranged with the liquid inlet 1311. The liquid outlet buffer tank 1323 is provided with two tapered outlets symmetrical about the Y-direction center axis of the substrate. Both ends of the liquid outlet flow channel 1322 respectively communicate with one tapered outlet. In this way, a uniform distribution of the fluid flow rate on the liquid outlet side can be ensured.

[0045] The liquid outlet guiding fluid body 1324 is arranged as a long strip extending along the Y direction. One end of the liquid outlet guiding fluid body 1324 close to the liquid outlet buffer tank 1323 is arranged as a semi-cylindrical body, and the end face close to the electrode is arranged as a rectangle, which is convenient for positioning the electrode.

[0046] The single cell of the zinc-nickel single flow battery includes a cover plate 10 covering the liquid inlet side 131 and the liquid outlet side. Welding ribs surrounding the electrolyte flow channel are provided on the frame body of the integrated electrode frame 13. The cover plate 10 and the integrated electrode frame 13 are welded by friction welding using the welding ribs. In the present invention, there are no special requirements for the distribution of the welding ribs. For example, dot-shaped, discontinuous strip-shaped or continuous strip-shaped welding ribs can be formed on each protrusion, each current collector and other surfaces of the frame body that contact the cover plate.

[0047] The size of the cover plate 10 in the X direction and / or Y direction can be 3-10 mm, and the thickness can be 0.1-1 mm.

[0048] In the present invention, the separator 8 can be selected from ion exchange membranes commonly used in the field of zinc-nickel flow batteries, such as cation exchange membranes, anion exchange membranes or porous membranes. There are no special requirements for this in the present invention and will not be elaborated further. The thickness of the separator 8 can be 25-200 μm.

[0049] There are no special requirements for the sealing ring in the present invention, and the sealing rings commonly used in the field of flow batteries can be used, such as fluororubber sealing rings, silicone rubber sealing rings or expanded elastic band sealing rings.

[0050] The thickness of the sealing ring 9 before compression is 0.2-3 mm, and the compression ratio is 0.6-0.8.

[0051] The inventors found that the current plate materials are mostly carbon-plastic composite materials, which only serve to connect single cells, isolate the electrolyte solution between adjacent single cells, and collect the current generated by the electrode reactions on both sides of the bipolar plate. They have no self-sealing function, and the low conductivity and thermal conductivity of the carbon-plastic composite materials result in poor battery stability and energy efficiency. The plate 12 is selected from flexible graphite plates. The flexible graphite plates have high conductivity and thermal conductivity, which can improve the battery stability and energy conversion efficiency to a certain extent. There are no special requirements for the flexible graphite plates in the present invention. As long as the flexible graphite plates can meet the conductivity of 10-100 mS / m, they can be used in the present invention, and this will not be elaborated further in the present invention.

[0052] The nickel electrode is coated on graphite felt, carbon felt, carbon paper or carbon cloth. Zinc is in solution and will undergo a chemical reaction on the surface of carbon felt or graphite felt. There are no special requirements for the zinc electrode and nickel electrode in the present invention. Commercially available zinc electrodes including one of graphite felt, carbon felt, carbon paper or carbon cloth and commercially available nickel hydroxide electrodes can be used, and this will not be elaborated further in the present invention.

[0053] In the present invention, the thickness of the electrode before compression can be 0.2-4 mm.

[0054] In the present invention, the compression ratio of the electrode is 0.1-0.5.

[0055] Based on the foregoing disclosure, the present invention discloses a stack structure of a zinc-nickel single-flow battery. The stack structure includes at least two zinc-nickel single-flow battery monomers of the present invention. Thus, for example, a stack structure including two zinc-nickel single-flow battery monomers of the present invention includes a positive end plate, a positive electrode plate, a positive current collector, a sealing ring, a positive cover plate, a nickel electrode, a separator, an integrated electrode frame, a zinc electrode, a negative cover plate, a sealing ring, a bipolar plate, a sealing ring, a positive cover plate, a nickel electrode, a separator, an integrated electrode frame, a zinc electrode, a negative cover plate, a sealing ring, a negative current collector, a negative electrode plate, and a negative end plate that are stacked in sequence. Among them, each part is connected by bolts. The inventor's research found that in order to reduce the number of gaskets, in the stack structure, in addition to forming the positive and negative electrode frames of the battery monomer into an integrated form in the present invention, a bipolar plate can also be welded at the position where the separator was originally pasted in the integrated electrode frame (exchanging the positions of the bipolar plate and the separator). In this way, the sealing material between the electrode frame and the bipolar plate can be removed. However, in actual use, there will be a situation of internal leakage in the stack, resulting in liquid cross-flow between adjacent single cells in the stack structure. In the flow battery structure of the present invention, the negative electrode frame and the positive electrode frame in the battery monomer are combined into one, reducing the production cost of the stack while ensuring sealing; the integrated electrode frame and the electrode plate share the same set of sealing strips, which reduces the number of seals used, increases the reliability of the seal, and reduces the risk of electrolyte leakage.

[0056] In the present invention, the electrode compression ratio of the stack structure is 0.1 to 0.5, and when the battery operating current density is 35 mA / cm 2 , the Coulomb efficiency > 97%, the voltage efficiency > 87.5%, and the energy efficiency > 85%.

[0057] The present invention will be described in detail below through embodiments. In the following embodiments, the zinc electrode, nickel electrode, gasket, electrode plate, and separator are all commercially available products.

[0058] In the embodiments of the present invention, the calculation methods for each result are as follows:

[0059] (1) Coulomb efficiency CE: It is the ratio of the energy storage capacity to the charging capacity.

[0060]

[0061] In the formula, Q dis is the energy storage capacity, A·h; Q ch is the charging capacity, A·h; I dis is the discharge current density, mA / cm 2 ; I ch is the charging current density, mA / cm 2 ; t is the charge and discharge time, s.

[0062] (2) Voltage efficiency VE: The voltage efficiency is the ratio of the average discharge voltage to the average charge voltage.

[0063]

[0064] Wherein, is the average discharge voltage, V; is the average charge voltage, V; V dis is the discharge voltage at any time, V; V ch is the charge voltage at any time, V; t dis is the discharge time, s; t ch is the charge time, s.

[0065] (3) Energy efficiency EE: The ratio of the discharge energy to the charge energy.

[0066]

[0067] Wherein, W dis is the discharge energy, W·h; W ch is the charge energy, W·h.

[0068] Example 1

[0069] The stack structure of the zinc-nickel single-flow battery includes Figure 3 15 series-connected zinc-nickel single-flow battery monomers as shown. The stack structure includes a positive end plate, a positive electrode plate, a positive current collector, a sealing ring (3-mm-thick expanded body with a compression ratio of 0.8), a positive cover plate, a commercially available nickel electrode (2.9-mm-thick carbon felt and 0.65-mm-thick nickel hydroxide electrode), a separator (using an 80-μm-thick PP porous membrane), Figure 4 the integral electrode frame as shown, a commercially available zinc electrode (4-mm-thick carbon felt), a negative cover plate, a sealing ring, a bipolar plate, a sealing ring, a positive cover plate, a commercially available nickel electrode (2.9-mm-thick carbon felt and 0.65-mm-thick nickel hydroxide electrode), a separator, the integral electrode frame, a zinc electrode, a negative cover plate, a sealing ring, a negative current collector, a commercially available zinc electrode (4-mm-thick carbon felt), a negative end plate. Among them, each part is connected by bolts; among them, the positive electrode plate, the negative electrode plate, and the bipolar plate adopt commercially available flexible graphite plates with a conductivity of 20 S / cm, a thickness of 0.8 mm, the thickness of the integral electrode frame is 5.8 mm, the thicknesses of the positive and negative cover plates are 0.5 mm, and the compression ratio of the electrode material is 0.25.

[0070] Connect the assembled stack structure to the Lanbo battery test system model BT2018F. After turning on the circulation pump to circulate the electrolyte (the electrolyte is a mixture of 7 mol / L potassium hydroxide and 0.2 mol / L zinc acetate, and the electrolyte flow rate is 0.4 m / s), let it stand for half an hour. Connect the positive and negative electrode tabs to the positive and negative circuit lines of the test system. First, activate the positive electrode material with a small current density of 10 mA / cm 2 and 20 mA / cm 2 , and then perform a constant current charge-discharge cycle test with a current density of 35 mA / cm 2 . Set the discharge cut-off voltage to 0.4 V.

[0071] The test results are shown in Table 1.

[0072] Example 2

[0073] Differing from Example 1, the positive electrode plate, negative electrode plate, and bipolar plate are made of commercially available conductive plastic plates with a conductivity of 20 S / cm.

[0074] The test results are shown in Table 1.

[0075] Comparative Example 1

[0076] Differing from Example 1, the positive and negative electrodes on both sides of the bipolar plate are installed in the integrated electrode frame of the present invention, and the bipolar plate is welded to the integrated electrode frame by laser welding. The positive and negative electrodes of the single cell are separated by a diaphragm, and the positive and negative electrodes at the ends adopt an electrode frame with the structure as shown in Figure 4 . Among them, the negative electrode frame is 3 mm thick, and the positive electrode frame is 2.8 mm thick.

[0077] The test results are shown in Table 1.

[0078] Table 1

[0079]

[0080] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A zinc-nickel single-flow battery cell, characterized in that: The single-flow battery cell comprises an integrated electrode frame (13), wherein an electrode cavity (133) of the integrated electrode frame (13) contains a nickel electrode, a zinc electrode and a diaphragm (8) separating the zinc electrode from the nickel electrode, and both sides of the integrated electrode frame (13) are sealed and connected to an electrode plate (12) via a sealing ring (9).

2. The zinc-nickel single-flow battery cell according to claim 1, characterized in that: The liquid inlet side (131) of the integrated electrode frame (13) is provided with a liquid inlet port (1311), a liquid inlet channel (1312) and a liquid inlet buffer groove (1313) which are connected in sequence, the liquid inlet buffer groove (1313) is provided with a plurality of liquid inlet guide bodies (1314) arranged at intervals along the X direction, the gap between two adjacent liquid inlet guide bodies (1314) forms a liquid inlet channel, the liquid inlet buffer groove (1313) is connected to the electrode cavity (133) through the liquid inlet channel, wherein the sizes of two adjacent liquid inlet guide bodies (1314) in the X direction are unequal.

3. The zinc-nickel single-flow battery cell according to claim 2, characterized in that: The plurality of liquid inlet guide bodies (1314) are arranged into at least one group, the liquid inlet channel (1312) is provided with at least one liquid inlet channel outlet connected to the liquid inlet buffer tank (1313), and each of the liquid inlet channel outlets is correspondingly provided with a group of liquid inlet guide bodies (1314).

4. The zinc-nickel single-flow battery cell according to claim 3, characterized in that: In each group of liquid inlet guide bodies (1314), the size of the liquid inlet guide bodies (1314) in the X direction decreases as the distance from the outlet of the liquid inlet channel increases; and / or In each group of the liquid inlet guide bodies (1314), the size of the liquid inlet channel in the X direction increases as the distance from the outlet of the liquid inlet channel (1312) increases.

5. The zinc-nickel single-flow battery cell according to claim 4, characterized in that: The liquid inlet guide body (1314) is configured as a rectangular parallelepiped.

6. The zinc-nickel single-flow battery cell according to claim 2, characterized in that: The liquid inlet side (131) and the liquid outlet side (132) of the integrated electrode frame (13) are arranged asymmetrically.

7. The zinc-nickel single-flow battery cell according to claim 6, characterized in that: The liquid outlet side (132) is provided with a liquid outlet (1321), a liquid outlet flow channel (1322) and a liquid outlet buffer groove (1323), wherein the liquid outlet (1321) is connected to the liquid outlet buffer groove (1323) through the liquid outlet flow channel (1322), and liquid outlet guide bodies (1324) arranged at equal intervals along the X direction are provided between the liquid outlet buffer groove (1323) and the electrode cavity (133), and the gap between two adjacent liquid outlet guide bodies (1324) forms a liquid outlet channel, and the liquid outlet buffer groove (1323) is connected to the electrode cavity (133) through the liquid outlet channel.

8. The zinc-nickel single-flow battery cell according to claim 7, characterized in that: The liquid outlet buffer tank (1323) is provided with a tapered outlet, and the tapered outlet is communicated with the liquid outlet channel; Preferably, the liquid outlet buffer tank (1323) is provided with two symmetrical tapered outlets, and the two ends of the liquid outlet channel (1322) are respectively connected to one of the tapered outlets.

9. The zinc-nickel single-flow battery cell according to any one of claims 1 to 8, characterized in that: The zinc-nickel single-flow battery cell comprises a cover plate (10) provided on a liquid inlet side (131) and a liquid outlet side, a frame of an integrated electrode frame (13) is provided with welding ribs surrounding an electrolyte flow channel, and the cover plate (10) and the integrated electrode frame (13) are friction welded via the welding ribs; and / or The membrane (8) is selected from a cation exchange membrane, an anion exchange membrane or a porous membrane.

10. A battery stack structure of a zinc-nickel single-liquid flow battery, characterized in that: The battery stack structure comprises at least two zinc-nickel single-flow battery cells according to any one of claims 1 to 9; Preferably, the electrode compression rate of the battery stack structure is 0.1-0.5, and the battery operating current density is higher than 35 mA / cm 2 When the Coulomb efficiency is >97%, the voltage efficiency is >87.5%, and the energy efficiency is >85%.

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