Integrated vanadium battery large electric pile

Abstract

The invention discloses an integrated vanadium battery large electric pile, and belongs to the technical field of novel energy storage, the integrated vanadium battery large electric pile comprises 2N series battery packs which are connected in parallel and have the same structure, and each series battery pack comprises a first end plate, a first insulating plate, a first collector plate, a plurality of vanadium single batteries which are connected in series, a second collector plate, a second insulating plate and a second end plate which are stacked in sequence; the battery packs connected in series in pairs form a group of galvanic pile parallel structure; in each galvanic pile parallel structure, the first end plates, the first insulating plates and the second end plates of the two series battery packs share one structure, and other structures are independent; the galvanic pile parallel connection structure also comprises a positive electrode electrolyte separation structure and a negative electrode electrolyte separation structure which are symmetrical; the positive electrolyte of the two series battery packs share one outlet or inlet, and the negative electrolyte of the two series battery packs share one outlet or inlet, so that uniform distribution of the positive electrolyte and the negative electrolyte is realized. According to the invention, the problems that the number of cells and bypass current are increased, the sizes of the sealing ring, the bipolar plate and the liquid flow frame are increased, and the processing difficulty, the processing cost and the liquid leakage risk are increased can be avoided while the single-stack power is improved.

Description

Technical Field

[0001] The present invention belongs to the field of novel energy storage technology, and in particular relates to an integrated vanadium battery large stack. Background Art

[0002] With the rapid expansion of renewable energy and smart grids, all-vanadium flow battery technology has great potential in large-scale energy storage fields such as intermittent energy generation and storage, grid peak regulation, and distributed power supply. In recent years, the power of newly built vanadium battery energy storage project systems has reached megawatts, tens of megawatts, and even hundreds of megawatts, and vanadium battery systems are developing in the direction of high power and large capacity. At present, the power of a single vanadium battery stack is mostly concentrated in the range of 50 to 100kW. A 10MW-class vanadium battery energy storage system usually requires hundreds of vanadium battery stacks, which are difficult and complex to integrate. The preparation of vanadium battery stacks with higher single-stack power will help reduce the difficulty of integrating high-power vanadium battery energy storage systems.

[0003] Current methods to increase the power of a single stack include increasing the number of battery cells in the stack and increasing the reaction area of ​​a single cell.

[0004] Increasing the number of battery cells in the stack will increase the bypass current of the stack and reduce the efficiency of the stack. Therefore, various measures are mainly taken to reduce the bypass current for this method, such as adding a partition in the middle of the stack. Patent CN 104852075 B "Liquid Flow Structure of a Vanadium Battery Stack" discloses a vanadium battery stack, including a first series-connected single battery group and a second series-connected single battery group. The two series-connected single battery groups are separated by a partition in the middle of the stack. There are electrolyte channels in the partition, which lead to the first series-connected single battery group and the second series-connected single battery group respectively. The essence of this structure is a combination of two small vanadium battery stacks, but there will be a problem of uneven electrolyte distribution between the first series-connected single battery group and the second series-connected single battery group, which will cause a decrease in battery performance and voltage consistency.

[0005] However, increasing the reaction area of ​​a single cell also has some problems. It will put higher requirements on the processing accuracy of components such as sealing rings, plates, and liquid flow frames. Large-area fuel cells are more likely to have leakage problems. In addition, the fuel cell stack is fastened with bolts. A single cell with a large reaction area will lead to uneven pressure distribution in the reaction plane. Long-term use of the fuel cell stack can easily cause deformation of the end plates, reduce the pressure in the middle part of the reaction zone, and increase the contact resistance, thereby reducing the performance of the fuel cell stack. Summary of the invention

[0006] In view of the high integration difficulty and complexity of existing high-power vanadium battery energy storage systems, the present invention provides an integrated vanadium battery large stack, which is obtained by connecting partial components of 2N series-connected battery groups in parallel. It can improve the power of a single stack while avoiding the problems of increasing the number of battery cells and bypass current, increasing the size of sealing rings, bipolar plates, and liquid flow frames, and increasing processing difficulty, processing costs, and leakage risks.

[0007] The technical solution adopted by the present invention is as follows:

[0008] An integrated vanadium battery large stack, comprising 2N series-connected battery groups of the same structure connected in parallel, N being a positive integer, the series-connected battery group comprising a first end plate, a first insulating plate, a first current collecting plate, a plurality of vanadium single batteries connected in series, a second current collecting plate, a second insulating plate and a second end plate stacked in sequence;

[0009] Two battery packs connected in series form a battery stack parallel structure, with a total of N battery stack parallel structures;

[0010] In each parallel structure of the battery stack, two series-connected battery groups share one first end plate, one first insulating plate, and one second end plate, and the other structures are independent;

[0011] The battery stack parallel structure also includes a positive electrode electrolyte separation structure and a negative electrode electrolyte separation structure, both of which are symmetrical structures; the positive electrode electrolytes of the two series-connected battery groups share a common outlet or inlet, and the negative electrode electrolytes share a common outlet or inlet; and then the positive electrode electrolyte and the negative electrode electrolyte are evenly distributed to the two series-connected battery groups.

[0012] Furthermore, a spring is arranged between the second insulating plate and the second end plate of the series-connected battery pack to compensate for the changes in internal stress of the battery stack caused by dimensional errors in parts processing, material creep, stress relaxation, and thermal expansion and contraction of materials in high and low temperature environments, and to improve the contact in the middle part of the reaction zone of the battery stack and reduce the contact resistance of the battery stack.

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

[0014] Furthermore, an inner end plate is provided between the second insulating plate of the series-connected battery pack and the spring to increase the strength of the second insulating plate.

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

[0016] Furthermore, the positive electrode electrolyte and the negative electrode electrolyte flow in the same direction or in a countercurrent direction.

[0017] Furthermore, the positive electrode electrolyte separation structure and the negative electrode electrolyte separation structure are respectively located on two sides of the first insulating plate.

[0018] Furthermore, the inlets / outlets of the positive electrolyte and the negative electrolyte are both located on the first end plate or the first insulating plate, and the second insulating plate does not contain electrolyte flow holes. At this time, the positive electrolyte and the negative electrolyte flow in a U shape inside the series battery pack.

[0019] Furthermore, the outlet of the positive electrode electrolyte and the negative electrode 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 electrode electrolyte and the negative electrode electrolyte flow in a Z shape inside the series battery group.

[0020] Furthermore, the middle of the first insulating plate is a sinking structure for embedding the first current collecting plate, and the collecting ears extend out of the series-connected battery pack.

[0021] Furthermore, the first insulating plate is a planar structure, and a cover plate is placed in the common port area of ​​the outlet or inlet of the positive electrode electrolyte and the negative electrode electrolyte to prevent the positive electrode electrolyte and the negative electrode electrolyte from contacting the first end plate and the first current collecting plate, causing corrosion and charging of the first end plate and the first current collecting plate.

[0022] Furthermore, the vanadium single cell comprises a graphite plate, a first sealing ring, a cathode liquid flow frame, a positive electrode, a second sealing ring, an ion conductive membrane, a third sealing ring, a negative electrode, a cathode liquid flow frame and a fourth sealing ring stacked in sequence.

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

[0024] 1. The present invention proposes an integrated vanadium battery stack. Since the partial structures of multiple series-connected battery groups with the same structure are in parallel, the current of each series-connected battery group can be automatically distributed according to its performance while ensuring the same total voltage of the integrated vanadium battery stack, thereby avoiding the voltage uniformity problem caused by the long-term operation of the battery stack and the performance degradation; at the same time, the structure of the series-connected battery group and the distribution structure of the positive and negative electrolytes are optimized and designed, so that the flow resistance of each series-connected battery group is the same, and the electrolyte flow rate flowing into each series-connected battery group is the same, thereby ensuring the consistency of the performance of each series-connected battery group; therefore, the present invention can improve the power of a single stack while avoiding the problems of large bypass current and low efficiency caused by increasing the number of battery cells, as well as the problems of increasing the size of the sealing ring, bipolar plate, and liquid flow frame due to the excessively large reaction area of ​​the single-chip battery, thereby increasing the processing difficulty, processing cost, and leakage risk;

[0025] 2. Preferably, by arranging a spring between the second insulating plate and the second end plate, and rationally planning the spring distribution and adjusting the spring stiffness coefficient, the pressure distribution in the reaction plane of the fuel cell stack is controlled to be more uniform, the contact resistance of the middle reaction zone is reduced, and the service life of the fuel cell stack is extended. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of a parallel structure of a battery stack in Example 1 of the present invention;

[0027] Figure 2This is a schematic diagram of the structure of multiple vanadium cells connected in series in Example 1 of the present invention;

[0028] Figure 3 This is a schematic diagram of the structure in which the first current collecting plate is not embedded in the first insulating plate in Embodiment 1 of the present invention;

[0029] Figure 4 This is a schematic structural diagram of a first insulating plate with a sunken structure in Embodiment 1 of the present invention;

[0030] Figure 5 This is a structural schematic diagram of the first current collecting plate embedded in the first insulating plate in Embodiment 1 of the present invention;

[0031] Figure 6 A schematic diagram of the flow direction of the positive electrode electrolyte inside the vanadium single battery of the battery stack parallel structure in Example 1 of the present invention;

[0032] Figure 7 A schematic diagram of the flow direction of the negative electrode electrolyte inside the vanadium single battery of the battery stack parallel structure in Example 1 of the present invention;

[0033] Figure 8 This is a schematic diagram of a parallel structure of a stack in which the inlet / outlet of the positive electrode electrolyte and the negative electrode electrolyte are both located on the first end plate in Example 1 of the present invention;

[0034] Fig. 9 Schematic diagram of the first end plate in which the inlet / outlet of the positive electrode electrolyte and the negative electrode electrolyte are both located on the first end plate in Example 1 of the present invention;

[0035] Fig.10 This is a schematic diagram of a parallel structure of a battery stack in which the inlet / outlet of the positive electrode electrolyte and the negative electrode electrolyte are both located on the first insulating plate in Example 1 of the present invention;

[0036] The descriptions of the symbols in the accompanying drawings are as follows:

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

[0038] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0039] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] Example 1

[0041] This embodiment provides an integrated vanadium battery large stack, including 2N series-connected battery groups with the same structure connected in parallel, where N is a positive integer. Two series-connected battery groups form a stack parallel structure, with a total of N stack parallel structures.

[0042] like Figure 1 As shown, in the battery stack parallel structure (composed of a series-connected battery group S1 and a series-connected battery group S2), the two series-connected battery groups each include a first end plate 11, a first insulating plate 21, a first current collecting plate 31, a plurality of vanadium cells connected in series, a second current collecting plate 32, a second insulating plate 22, and a second end plate 12, which are stacked in sequence and fixed together by a penetrating screw; and the two series-connected battery groups share one first end plate 11, one first insulating plate 21, and one second end plate 12, and the other structures are independent.

[0043] A spring 4 is also arranged between the second insulating plate 22 and the second end plate 12 of the series battery pack. By planning the distribution of the spring 4 and adjusting the spring 4 stiffness coefficient, the pressure distribution in the reaction plane of the stack is controlled to compensate for the internal stress changes of the stack caused by part processing dimensional tolerances, material creep, stress relaxation, and thermal expansion and contraction of materials in high and low temperature environments, improve the contact in the middle part of the stack reaction zone, and reduce the contact resistance of the stack.

[0044] An inner end plate is also provided between the second insulating plate 22 of the series-connected battery pack and the spring 4 . The inner end plate is made of stainless steel, aluminum alloy or other high-strength materials to increase the strength of the second insulating plate 22 .

[0045] The structure of multiple vanadium cells connected in series is as follows Figure 2As shown, each vanadium single cell includes a graphite plate, a first sealing ring, a positive electrode liquid flow frame, a positive electrode, a second sealing ring, an ion conductive membrane, a third sealing ring, a negative electrode, a negative electrode liquid flow frame and a fourth sealing ring stacked in sequence.

[0046] The middle of the first insulating plate 21 may be a flat plate structure or a sunken structure. When it is a flat plate structure, the structure of the first current collecting plate 31 used is as follows: Figure 3 As shown, at this time, the two series battery groups share a first current collecting plate 31, the size of the first current collecting plate 31 is the same as the size of the first insulating plate 21, the holes at the four corners are holes for electrolyte flow, and a plastic cover is embedded in the middle T-shaped hollow area. The plastic cover is combined with the T-shaped liquid separation structure on the first insulating plate 21 to form an electrolyte flow cavity to prevent the positive electrode electrolyte and the negative electrode electrolyte from contacting the first end plate 11 and the first current collecting plate 31, causing corrosion and charging of the first end plate 11 and the first current collecting plate 31; when it is as follows Figure 4 When the sinking structure shown in FIG. 1 is shown (the shaded portion is the thickness of the sinking current collecting plate), the first current collecting plate 31 is embedded in the sinking structure of the first insulating plate 21, as shown in FIG. Figure 5 As shown, the collecting ears extend out of the series-connected battery pack.

[0047] The battery stack parallel structure further includes a positive electrode electrolyte separation structure and a negative electrode electrolyte separation structure respectively located on two sides of the first insulating plate 21, both of which are symmetrical structures.

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

[0049] Specifically, when the inlet / outlet of the positive electrode electrolyte and the negative electrode electrolyte are both located on the first end plate 11 or the first insulating plate 21, and the second insulating plate 22 does not contain an electrolyte flow hole, the positive electrode electrolyte and the negative electrode electrolyte flow in a U-shape inside the series battery pack; when the outlet of the positive electrode electrolyte and the negative electrode electrolyte is located on the first end plate 11 or the first insulating plate 21, and the inlet is located on the second insulating plate 22, or the inlet is located on the first end plate 11 or the first insulating plate 21, and the outlet is located on the second insulating plate 22, the positive electrode electrolyte and the negative electrode electrolyte flow in a Z-shape inside the series battery pack.

[0050] Taking the structure in which the positive electrode electrolyte and the negative electrode electrolyte flow in a U shape inside the series battery pack as an example, the positive electrode electrolyte separation structure and the negative electrode electrolyte separation structure, as well as the flow direction of the positive electrode electrolyte and the negative electrode electrolyte inside the series battery pack are specifically described.

[0051] Specifically, the positive electrolyte separation structure includes one positive electrolyte main inlet 2111, one liquid flow trough, two positive electrolyte inlet manifold ports 2112 and two positive electrolyte outlet manifold ports 2113; the negative electrolyte separation structure includes two negative electrolyte inlet manifold ports 2121, two negative electrolyte outlet manifold ports 2122, one liquid flow trough and one negative electrolyte main outlet 2123.

[0052] like Figure 4 and Figure 5 As shown, after the positive electrode electrolyte flows into the parallel structure of the battery stack from the positive electrode electrolyte main inlet 2111, it flows into two positive electrode electrolyte inlet manifolds 2112 through the liquid flow trough, and then flows into two independent series battery groups (specifically, multiple vanadium single batteries connected in series), and finally flows out of the parallel structure of the battery stack through two positive electrode electrolyte outlet manifolds 2113. The flow direction of the positive electrode electrolyte inside the two series battery groups is as follows: Figure 6 shown.

[0053] Similarly, after the negative electrode electrolyte flows into the parallel structure of the battery stack from the two negative electrode electrolyte inlet manifolds 2121, it flows into two independent series battery groups (specifically, multiple vanadium single cells connected in series), flows out through the two negative electrode electrolyte outlet manifolds 2122, and is collected to the negative electrode electrolyte total outlet 2123 through the two-in-one liquid flow trough, and finally flows out of the parallel structure of the battery stack. The flow direction of the negative electrode electrolyte inside the two series battery groups is as follows: Figure 7 As shown, the flow direction of the positive electrode electrolyte and the negative electrode electrolyte is the same direction.

[0054] Figure 8 Schematic diagram of a parallel structure of a stack in which the inlet / outlet of the positive electrode electrolyte and the negative electrode electrolyte are both located on the first end plate 11, as shown in FIG. Fig. 9 As shown, the first end plate 11 is provided with a positive electrode electrolyte total inlet 2111 , two positive electrode electrolyte outlet manifold ports 2113 , two negative electrode electrolyte inlet manifold ports 2121 and a negative electrode electrolyte total outlet 2123 .

[0055] Fig.10 This is a schematic diagram of a battery stack parallel structure in which the inlets / outlets of the positive electrode electrolyte and the negative electrode electrolyte are both located on the first insulating plate 21. Since the first insulating plate 21 is located inside the battery stack parallel structure and the first end plate 11 has no opening, a hole is opened on the side of the first insulating plate 21. Specifically, one positive electrode electrolyte total inlet 2111, two positive electrode electrolyte manifold outlets 2113, two negative electrode electrolyte manifold inlets 2121 and one negative electrode electrolyte total outlet 2123 are provided.

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

[0057] In this embodiment, each battery group connected in series is identical, and the positive electrode electrolyte separation structure and the negative electrode electrolyte separation structure between the battery groups connected in series are symmetrical structures. Therefore, the flow resistance of each battery group connected in series is the same, and the electrolyte flow rate flowing into each battery group connected in series is the same, which can ensure the consistency of the performance of each battery group connected in series.

[0058] In addition, the performance of the battery stack will decay after long-term operation. Since multiple series-connected battery groups are connected in parallel with the same total voltage, the current of each series-connected battery group will be automatically distributed according to the performance of each series-connected battery group, avoiding the problem of voltage uniformity.

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

Claims

1. An integrated vanadium battery large stack, characterized in that: The invention comprises 2N series battery packs connected in parallel and having the same structure, wherein N is a positive integer, and the series battery pack comprises a first end plate, a first insulating plate, a first current collecting plate, a plurality of vanadium single batteries connected in series, a second current collecting plate, a second insulating plate, and a second end plate, which are stacked in sequence; Two battery packs connected in series form a battery stack parallel structure, with a total of N battery stack parallel structures; In each parallel structure of the battery stack, two series-connected battery groups share one first end plate, one first insulating plate, and one second end plate, and the other structures are independent; The battery stack parallel structure also includes a positive electrode electrolyte separation structure and a negative electrode electrolyte separation structure, both of which are symmetrical structures; the positive electrode electrolytes of the two series-connected battery groups share a common outlet or inlet, and the negative electrode electrolytes share a common outlet or inlet; and then the positive electrode electrolyte and the negative electrode electrolyte are evenly distributed to the two series-connected battery groups.

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

3. The integrated vanadium battery large stack according to claim 2 is characterized in that: The pressure distribution in the reaction plane of the fuel cell stack can be controlled by planning the spring distribution and adjusting the spring stiffness coefficient.

4. The integrated vanadium battery large 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 and the spring of the series-connected battery pack.

5. The integrated vanadium battery large 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 respectively located on two sides of the first insulating plate.

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

7. The integrated vanadium battery large stack according to claim 5 is characterized in that: The outlet of the positive electrode electrolyte and the negative electrode 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 electrode electrolyte and the negative electrode electrolyte flow in a Z shape inside the series battery group.

8. The integrated vanadium battery large stack according to any one of claims 1 to 3, characterized in that: The middle of the first insulating plate is a sinking structure for embedding the first current collecting plate, and the collecting ears extend out of the series-connected battery pack.

9. The integrated vanadium battery large stack according to any one of claims 1 to 3, characterized in that: The first insulating plate is a planar structure, and a cover plate is placed in the common port area of ​​the outlet or inlet of the positive electrode electrolyte and the negative electrode electrolyte.

10. The integrated vanadium battery large 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 cathode liquid flow frame, a positive electrode, a second sealing ring, an ion conductive membrane, a third sealing ring, a negative electrode, a cathode liquid flow frame and a fourth sealing ring which are stacked in sequence.

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