Integrated vanadium battery large stack

Abstract

The application discloses an integrated vanadium battery large electric pile and belongs to the technical field of novel energy storage, comprising 2N parallelly connected and identically structured series-connected battery groups, wherein the series-connected battery group comprises a first end plate, a first insulating plate, a first current collector plate, a plurality of series-connected vanadium single cells, a second current collector plate, a second insulating plate and a second end plate which are stacked in sequence; two series-connected battery groups form a group of electric pile parallel structures; in each electric pile parallel structure, the first end plates of the two series-connected battery groups share one, the first insulating plates share one, the second end plates share one, and other structures are independent; the electric pile parallel structure further comprises structure-symmetrical positive and negative electrolyte distribution structures; the positive electrolyte of the two series-connected battery groups shares one outlet or inlet, and the negative electrolyte shares one outlet or inlet, so that the positive and negative electrolytes are evenly distributed. The application can improve the power of a single pile, avoid the problems of increasing the number of battery groups and bypass current, increasing the size of sealing rings, bipolar plates and liquid flow frames, increasing the processing difficulty, processing cost and liquid leakage risk.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of new energy storage technology, and particularly relates to an integrated vanadium battery large stack. BACKGROUND

[0002] With the rapid expansion of renewable energy and smart grid, vanadium redox flow battery technology has great potential in large-scale energy storage fields such as intermittent energy generation, grid peak shaving, and distributed power supply. In recent years, the power of newly built vanadium battery energy storage projects has reached megawatt, ten megawatts or even hundred megawatts, and vanadium battery systems are developing towards high power and large capacity. At present, the single stack power of vanadium battery stack is mostly concentrated in 50-100 kW, and a 10 MW vanadium battery energy storage system usually needs hundreds of vanadium battery stacks, which has high integration difficulty and complexity. Preparing a vanadium battery stack with higher single stack power is conducive to reducing the integration difficulty of high-power vanadium battery energy storage systems.

[0003] At present, the methods for increasing the single stack power include increasing the number of cell layers and increasing the reaction area of single cell.

[0004] Increasing the number of cell layers will increase the bypass current of the stack and reduce the efficiency of the stack, so various measures are mainly taken to reduce the bypass current, such as adding a partition plate in the middle of the stack. Patent CN 104852075 B “Liquid flow structure of vanadium battery stack” discloses a vanadium battery stack, which comprises a first series of single cell groups and a second series of single cell groups, and the two series of single cell groups are separated by a partition plate in the middle of the stack. The partition plate has electrolyte channels leading to the first series of single cell groups and the second series of single cell groups, respectively. The essence of this structure is a combination of two small vanadium battery stacks, but there will be a problem of uneven distribution of electrolyte between the first series of single cell groups and the second series of single cell groups, which will cause the decline of battery performance and voltage consistency.

[0005] Increasing the reaction area of single cell also has some problems, which will put higher requirements on the processing precision of sealing rings, polar plates, and liquid flow frames, and large-area stacks are more likely to have liquid leakage problems. In addition, the stack is fastened by bolts, and a large single cell reaction area will cause uneven pressure distribution in the reaction plane, which will easily cause deformation of the end plate after long-term use of the stack, the pressure in the middle part of the reaction zone will become smaller, the contact resistance will become larger, and the performance of the stack will be reduced. SUMMARY

[0006] In view of the high integration difficulty and complexity of the existing high-power vanadium battery energy storage system, the present application provides an integrated vanadium battery large stack, which can improve the single stack power while avoiding the problems of increasing the number of cell layers and bypass current, increasing the size of the sealing ring, bipolar plate, and liquid flow frame, and increasing the processing difficulty, processing cost, and risk of liquid leakage by connecting the partial components of 2N series of cell groups in parallel.

[0007] The technical scheme adopted by the present application is as follows:

[0008] An integrated vanadium battery large stack includes 2N parallelly connected and structurally identical series battery groups, N is a positive integer, and the series battery group includes a first end plate, a first insulation plate, a first current collector plate, a plurality of series-connected vanadium single cells, a second current collector plate, a second insulation plate, and a second end plate stacked in sequence;

[0009] Two series battery groups constitute a group of stack parallel structures, and there are N groups of stack parallel structures in total.

[0010] In each stack parallel structure, the first end plates of the two series battery groups share one, the first insulation plates share one, and the second end plates share one, and the other structures are all independent.

[0011] The stack parallel structure further includes a positive electrolyte distribution structure and a negative electrolyte distribution structure, both of which are symmetrical structures; the positive electrolyte of the two series battery groups shares one outlet or inlet, and the negative electrolyte shares one outlet or inlet; and the positive electrolyte and the negative electrolyte are then evenly distributed to the two series battery groups.

[0012] Further, a spring is arranged between the second insulation plate and the second end plate of the series battery group, for compensating for the internal stress changes of the stack caused by part processing size errors, material creep, stress relaxation, and material thermal expansion and contraction in high and low temperature environments, and for improving the contact at the middle part of the stack reaction area and reducing the stack contact resistance.

[0013] Further, the pressure distribution in the reaction plane of the stack is controlled by planning the spring distribution and adjusting the spring stiffness coefficient.

[0014] Further, an inner end plate is arranged between the second insulation plate and the spring of the series battery group, for increasing the strength of the second insulation plate.

[0015] Further, the material of the inner end plate is stainless steel, aluminum alloy, or other materials with relatively high strength.

[0016] Further, the flow directions of the positive electrolyte and the negative electrolyte are co-flow or counter-flow.

[0017] Further, the positive electrolyte distribution structure and the negative electrolyte distribution structure are respectively located on the two sides of the first insulation plate.

[0018] Further, the outlets / inlets of the positive electrolyte and the negative electrolyte are located on the first end plate or the first insulation plate, and the second insulation plate does not contain electrolyte flow-through holes, at this time, the positive electrolyte and the negative electrolyte flow in a U-shaped manner inside the series battery group.

[0019] Further, the outlet of the positive electrolyte and the negative electrolyte is located on the first end plate or the first insulating plate, and the inlet is located on the second insulating plate, or the inlet is located on the first end plate or the first insulating plate, and the outlet is located on the second insulating plate, at this time, the positive electrolyte and the negative electrolyte flow in a Z shape inside the series battery pack.

[0020] Further, the middle of the first insulating plate is a sunken structure for embedding the first current collecting plate, and the lug extends outside the series battery pack.

[0021] Further, the first insulating plate is a flat structure, and a cover plate is arranged at the common port area of the outlet or inlet of the positive electrolyte and the negative electrolyte to prevent the positive electrolyte and the negative electrolyte from contacting the first end plate and the first current collecting plate, thereby preventing corrosion and electrification of the first end plate and the first current collecting plate.

[0022] Further, the vanadium single cell comprises, in sequence, a graphite plate, a first sealing ring, a positive electrolyte flow frame, a positive electrode, a second sealing ring, an ion conductive film, a third sealing ring, a negative electrode, a negative electrolyte flow frame, and a fourth sealing ring.

[0023] The beneficial effects of the present application are:

[0024] 1. The present application proposes an integrated vanadium battery large electric pile, since the structures of the plurality of series battery pack parts are the same and are in parallel connection, the current of each series battery pack can be automatically distributed according to its performance under the condition that the total voltage of the integrated vanadium battery large electric pile is the same, thereby avoiding the problem of voltage uniformity caused by performance decay due to long-term operation of the electric pile; at the same time, the structure of the series battery pack and the distribution structure of the positive and negative electrolytes are optimized, so that the flow resistance of each series battery pack is the same, the electrolyte flow into each series battery pack is the same, and the consistency of the performance of each series battery pack is ensured; thus, the present application can improve the power of a single pile while avoiding the problems of large bypass current and low efficiency caused by increasing the number of battery piles, and the problems of increasing the size of the sealing ring, bipolar plate, and liquid flow frame due to the excessive reaction area of a single cell, thereby increasing the processing difficulty, processing cost, and the risk of liquid leakage.

[0025] 2. Preferably, by arranging springs between the second insulating plate and the second end plate and reasonably planning the spring distribution and adjusting the spring stiffness coefficient, the pressure distribution in the reaction plane of the electric pile is more uniform, the contact resistance of the middle reaction zone is reduced, and the service life of the electric pile is prolonged. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 FIG. 1 is a schematic diagram of a parallel structure of one electric pile in Embodiment 1 of the present application;

[0027] Figure 2Structure diagram of the vanadium single cell in embodiment 1 of the present application;

[0028] Figure 3 Structure diagram of the vanadium single cell in embodiment 1 of the present application;

[0029] Figure 4 Structure diagram of the vanadium single cell in embodiment 1 of the present application;

[0030] Figure 5 Structure diagram of the vanadium single cell in embodiment 1 of the present application;

[0031] Figure 6 Structure diagram of the vanadium single cell in embodiment 1 of the present application;

[0032] Figure 7 Structure diagram of the vanadium single cell in embodiment 1 of the present application;

[0033] Figure 8 Structure diagram of the vanadium single cell in embodiment 1 of the present application;

[0034] Figure 9 Structure diagram of the vanadium single cell in embodiment 1 of the present application;

[0035] Figure 10 Structure diagram of the vanadium single cell in embodiment 1 of the present application;

[0036] The explanation of each mark in the drawing is as follows:

[0037] 11: first end plate; 21: first insulation plate; 31: first current collecting plate; 12: second end plate; 22: second insulation plate; 32: second current collecting plate; 4: spring; 2111: total inlet of positive electrolyte; 2112: inlet manifold of positive electrolyte; 2113: outlet manifold of positive electrolyte; 2121: inlet manifold of negative electrolyte; 2122: outlet manifold of negative electrolyte; 2123: total outlet of negative electrolyte. DETAILED DESCRIPTION

[0038] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0039] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative labor are within the scope of protection of the present application.

[0040] Embodiment 1

[0041] The present embodiment provides an integrated vanadium battery large stack, which comprises 2N series-connected battery groups with the same structure, and N is a positive integer. Two series-connected battery groups form a group of stack parallel structures, and there are N groups of stack parallel structures in total.

[0042] As shown in Figure 1 In the stack parallel structure (composed of series-connected battery group S1 and series-connected battery group S2), both series-connected battery groups comprise a first end plate 11, a first insulation plate 21, a first current collector plate 31, a plurality of series-connected vanadium single cells, a second current collector plate 32, a second insulation plate 22 and a second end plate 12 stacked in sequence, and are fixedly connected together through penetrating threaded rods; and the first end plates 11 of the two series-connected battery groups share one, the first insulation plates 21 share one, and the second end plates 12 share one, and the other structures are independent.

[0043] A spring 4 is further arranged between the second insulation plate 22 and the second end plate 12 of the series-connected battery group. By planning the distribution of the spring 4 and adjusting the stiffness coefficient of the spring 4, the pressure distribution in the stack reaction plane is controlled to compensate for the changes in internal stress of the stack caused by part processing size tolerance, material creep, stress relaxation and material thermal expansion and contraction in high and low temperature environments, and to improve the contact at the middle part of the stack reaction area and reduce the stack contact resistance.

[0044] An inner end plate is further arranged between the second insulation plate 22 and the spring 4 of the series-connected battery group, which is made of stainless steel, aluminum alloy or other materials with high strength, and is used to increase the strength of the second insulation plate 22.

[0045] The structure of the plurality of series-connected vanadium single cells is as shown in Figure 2As shown, each van single cell comprises, in sequence, a graphite plate, a first sealing ring, a positive flow frame, a positive electrode, a second sealing ring, an ion conductive film, a third sealing ring, a negative electrode, a negative flow frame, and a fourth sealing ring.

[0046] The middle of the first insulation plate 21 can be a flat plate structure or a sunken structure; when it is a flat plate structure, the corresponding first current collecting plate 31 structure is as shown in Figure 3 As shown, at this time, the two series battery groups share one first current collecting plate 31, the size of the first current collecting plate 31 is the same as that of the first insulation plate 21, the holes in the four corners are electrolyte flow holes, and a plastic cover plate is embedded in the middle T-shaped hollow area, which, in combination with the T-shaped distribution structure on the first insulation plate 21, forms an electrolyte flow cavity to prevent the positive electrolyte and the negative electrolyte from contacting the first end plate 11 and the first current collecting plate 31, causing corrosion and electrification of the first end plate 11 and the first current collecting plate 31; when it is a sunken structure as shown in Figure 4 As shown, the first current collecting plate 31 is embedded in the sunken structure of the first insulation plate 21. Figure 5 As shown, the lugs protrude outside the series battery group.

[0047] The series-parallel structure of the stack further comprises positive electrolyte distribution structures and negative electrolyte distribution structures respectively located on the two sides of the first insulation plate 21, both of which are symmetrical structures.

[0048] By designing the outlets / inlets of the positive electrolyte and the negative electrolyte at different positions of the series-parallel structure of the stack, the flow direction of the electrolyte inside the series battery group can be designed as U-shaped or Z-shaped.

[0049] Specifically, when the outlets / inlets of the positive electrolyte and the negative electrolyte are both located on the first end plate 11 or the first insulation plate 21, and the second insulation plate 22 does not contain electrolyte flow holes, the positive electrolyte and the negative electrolyte flow in a U-shaped manner inside the series battery group; when the outlet of the positive electrolyte and the negative electrolyte is located on the first end plate 11 or the first insulation plate 21, and the inlet is located on the second insulation plate 22, or the inlet is located on the first end plate 11 or the first insulation plate 21, and the outlet is located on the second insulation plate 22, the positive electrolyte and the negative electrolyte flow in a Z-shaped manner inside the series battery group.

[0050] Taking the structure in which the positive electrolyte and the negative electrolyte flow in a U-shaped manner inside the series battery group as an example, the positive electrolyte distribution structure and the negative electrolyte distribution structure, as well as the flow direction of the positive electrolyte and the negative electrolyte inside the series battery group, are described in detail.

[0051] Specifically, the positive electrolyte distribution structure includes one positive electrolyte total inlet 2111, one flow channel, two positive electrolyte manifold inlets 2112, and two positive electrolyte manifold outlets 2113; the negative electrolyte distribution structure includes two negative electrolyte manifold inlets 2121, two negative electrolyte manifold outlets 2122, one flow channel, and one negative electrolyte total outlet 2123.

[0052] As shown in Figure 4 and Figure 5 , the positive electrolyte flows into the parallel structure of the stack from the positive electrolyte total inlet 2111, is divided into two through the flow channel, flows into two positive electrolyte manifold inlets 2112, and then flows into two independent series-connected battery groups (specifically, multiple series-connected vanadium single cells), and finally flows out of the parallel structure of the stack through two positive electrolyte manifold outlets 2113. The flow direction of the positive electrolyte inside the two series-connected battery groups is shown in Figure 6 .

[0053] Similarly, the negative electrolyte flows into the parallel structure of the stack from two negative electrolyte manifold inlets 2121, flows into two independent series-connected battery groups (specifically, multiple series-connected vanadium single cells) respectively, flows out through two negative electrolyte manifold outlets 2122, and is collected through the flow channel to the negative electrolyte total outlet 2123, and finally flows out of the parallel structure of the stack. The flow direction of the negative electrolyte inside the two series-connected battery groups is shown in Figure 7 , and the flow directions of the positive electrolyte and the negative electrolyte are the same.

[0054] Figure 8 The positive electrolyte and the negative electrolyte are shown in Figure 9 , the positive electrolyte and the negative electrolyte are shown in .

[0055] Figure 10 The positive electrolyte and the negative electrolyte are shown in , the positive electrolyte and the negative electrolyte are shown in

[0056] The opening sizes of the positive electrolyte total inlet 2111 and the negative electrolyte total outlet 2123 are larger than those of the positive electrolyte manifold outlet 2113 and the negative electrolyte manifold inlet 2121.

[0057] In the embodiment, each series battery is the same, the positive electrolyte distribution structure and the negative electrolyte distribution structure between the series batteries are symmetrical structures, thus the flow resistance of each series battery is the same, the electrolyte flow into each series battery is the same, and the consistency of the performance of each series battery can be ensured.

[0058] In addition, the performance of the stack is attenuated during long-term operation, and since the multiple series batteries are in parallel structure, the total voltage is the same, and the current of each series battery is automatically distributed according to the performance of each series battery, thereby avoiding the problem of voltage uniformity.

[0059] The above embodiments only illustrate the principles and advantages of the present application, and are not used to limit the present application, and are only used to help understand the principles of the present application, and the protection scope of the present application is not limited to the above configurations and embodiments, and those skilled in the art can make other various specific modifications and combinations without departing from the essence of the present application according to the disclosed technology, but still within the protection scope of the present application.

Claims

1. An integrated vanadium battery stack, characterized in that, It includes 2N parallel connected series battery packs with the same structure, where N is a positive integer. Each series battery pack includes a first end plate, a first insulating plate, a first current collector, multiple vanadium single cells connected in series, a second current collector, a second insulating plate, and a second end plate stacked in sequence. Two battery packs connected in series together form a parallel stack structure, for a total of N parallel stack structures; In each parallel structure of the battery stacks, the first end plate of the two series battery packs is shared, the first insulation plate is shared, and the second end plate is shared, while the other structures are owned independently. The parallel structure of the battery stack also includes a positive electrolyte distribution structure and a negative electrolyte distribution structure located on the first insulating plate, both of which are symmetrical structures. The positive electrolyte distribution structure includes one positive electrolyte inlet, one flow channel, two positive electrolyte manifolds, and two positive electrolyte outlets. The negative electrolyte distribution structure includes two negative electrolyte manifolds, two negative electrolyte outlets, one flow channel, and one negative electrolyte outlet. The positive electrolytes of the two series-connected battery packs share a common inlet, and the negative electrolytes share a common outlet, thereby evenly distributing the positive and negative electrolytes to the two series-connected battery packs.

2. The integrated vanadium battery stack according to claim 1, characterized in that, A spring is also provided between the second insulating plate and the second end plate of the series-connected battery pack.

3. The integrated vanadium battery stack according to claim 2, characterized in that, The pressure distribution within the reactor reactor plane is controlled by planning the spring distribution and adjusting the spring stiffness coefficient.

4. The integrated vanadium battery stack according to any one of claims 1 to 3, characterized in that, An inner end plate is also provided between the second insulating plate of the series battery pack and the spring.

5. The integrated vanadium battery stack according to any one of claims 1 to 3, characterized in that, The positive electrode electrolyte separation structure and the negative electrode electrolyte separation structure are located on opposite sides of the first insulating plate.

6. The integrated vanadium battery stack according to claim 5, characterized in that, The inlet and outlet of the positive electrolyte and the negative electrolyte are both located on the first insulating plate, and the second insulating plate does not have electrolyte flow holes. At this time, the positive electrolyte and the negative electrolyte flow in a U-shape inside the series battery pack.

7. The integrated vanadium battery stack according to any one of claims 1 to 3, characterized in that, The first insulating plate has a recessed structure in the middle for embedding the first current collector, and the collector ear extends out of the series battery pack.

8. The integrated vanadium battery stack according to any one of claims 1 to 3, characterized in that, The first insulating plate has a planar structure, and a cover plate is placed in the common port area of ​​the positive and negative electrolyte outlets to prevent the positive and negative electrolytes from contacting the first end plate and the first current collector.

9. The integrated vanadium battery stack according to any one of claims 1 to 3, characterized in that, The vanadium single cell comprises a graphite plate, a first sealing ring, a positive electrode flow frame, a positive electrode, a second sealing ring, an ion-conducting film, a third sealing ring, a negative electrode, a negative electrode flow frame, and a fourth sealing ring stacked in sequence.

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