Redox battery

Abstract

The redox battery includes a plurality of redox battery cells stacked in a stacking direction, each of which includes a first half cell connected to a positive current collector, a second half cell connected to a negative current collector, and an ion exchange membrane separating the first half cell and the second half cell, a positive conductive bus bar extending in the stacking direction and electrically connecting the positive current collectors of the redox battery cells in parallel, and a negative conductive bus bar extending in the stacking direction and electrically connecting the plurality of negative current collectors of the redox battery cells in parallel, and at least one of the positive conductive bus bar and the negative conductive bus bar binds the redox battery cells in the stacking direction.

Description

[Technical field]

[0001] The disclosed technology relates generally to energy storage devices, and more specifically to redox batteries and connections for redox batteries. [Background technology]

[0002] Increasing global warming along with the world's economic growth is driving the need for renewable and sustainable energy systems based on renewable energy, e.g., solar and wind energy. To improve the stability of grid networks against fluctuations due to the intermittent availability of such energy forms, the development of energy storage systems (ESS) is used to store excess electricity, which can be transferred to end customers or the power grid when needed. ESS based on electrochemical energy, e.g., rechargeable or secondary batteries, among others, can provide a cost-effective and clean form of energy storage solution. Examples of electrochemical energy storage systems include lithium-ion, lead-acid, sodium-sulfur, and redox-flow batteries. Different storage times are required for different applications, such as short-term storage, medium-term storage, and long-term storage. Different types of electrochemical energy storage systems have different physical and / or chemical properties. Factors that determine the suitability of an electrochemical energy storage system for a particular application include investment cost, power, energy, lifetime, recyclability, efficiency, scalability, and maintenance costs, to name a few. The selection and design of an appropriate electrochemical storage system is considered a competitive factor. Summary of the Invention [Means for solving the problem]

[0003] According to one embodiment, the redox battery includes a plurality of redox battery cells stacked in a stacking direction, each of the redox battery cells including a first half cell connected to a positive current collector, a second half cell connected to a negative current collector, and an ion exchange membrane separating the first half cell from the second half cell. The redox battery also includes a positive conductive bus bar extending in the stacking direction and electrically connecting the positive current collectors of the redox battery cells in parallel, and a negative conductive bus bar extending in the stacking direction and electrically connecting the negative current collectors in parallel. One or both of the positive bus bar and the negative bus bar are configured as fastening means for mechanically fastening the stacked redox battery cells in the stacking direction.

[0004] According to another embodiment, the redox battery includes a plurality of redox battery cells stacked in a stacking direction, each of the redox battery cells including a first half-cell coupled to a positive current collector, a second half-cell coupled to a negative current collector, and an ion exchange membrane separating the first and second half-cells. The redox battery also includes a positive conductive bus bar extending in the stacking direction and electrically connecting the positive current collectors of the redox battery cells in parallel, and a negative conductive bus bar extending in the stacking direction and electrically connecting the negative current collectors in parallel. The redox battery further includes a positive end plate and a negative end plate disposed at opposite ends of the stacked redox battery cells, the positive end plate coupled to the positive conductive bus bar and the negative end plate coupled to the negative conductive bus bar.

[0005] According to yet another embodiment, the redox battery includes a plurality of redox battery cells stacked in a stacking direction, each of the redox battery cells including a first half cell connected to a positive current collector, a second half cell connected to a negative current collector, and an ion exchange membrane separating the first half cell from the second half cell. The redox battery also includes a positive conductive bus bar extending in the stacking direction and electrically connecting the positive current collectors of the redox battery cells in parallel, and a negative conductive bus bar extending in the stacking direction and electrically connecting the negative current collectors in parallel. The redox battery further includes a positive end plate and a negative end plate disposed at opposite ends of the stacked redox battery cells, the positive end plate and the negative end plate being connected to the positive conductive bus bar. The redox battery further includes a third end plate and a fourth end plate disposed at opposite ends of the stacked redox battery cells, the third end plate and the fourth end plate being connected to the negative conductive bus bar.

[0006] According to yet another embodiment, a redox battery system includes a plurality of redox batteries, each of which is according to any of the above embodiments, each of which includes a pair of conductive positive end plates disposed at opposite ends of the redox battery cells stacked in the cell stacking direction and electrically connected to a positive conductive bus bar, and a pair of conductive negative end plates disposed at opposite ends of the redox battery cells stacked in the cell stacking direction and electrically connected to a negative conductive bus bar, and one or more subsets of the redox batteries are stacked in at least one other direction perpendicular to the cell stacking direction and electrically connected to each other.

[0007] According to yet another embodiment, a redox battery system includes a plurality of redox batteries, each of which includes one or more conductive positive end plates and one or more conductive negative end plates according to any of the embodiments described above, and a conductive shorting structure configured to form an electrical short between structures coupled by a first end and a second end of the conductive shorting structure, the first end configured to be removably secured to and electrically coupled to one of the conductive positive end plates or the conductive negative end plates of the plurality of redox batteries, and the second end configured to be removably secured to and electrically coupled to another of the conductive positive end plates or the conductive negative end plates of the plurality of redox batteries.

[0008] According to yet another embodiment, a redox battery includes a plurality of redox battery cells stacked in a stacking direction, each of the redox battery cells including a first half cell connected to a positive current collector, a second half cell connected to a negative current collector, and an ion exchange membrane separating the first half cell from the second half cell. The redox battery also includes a positive conductive bus bar extending in the stacking direction and electrically connecting the positive current collectors of the redox battery cells in parallel, and a negative conductive bus bar extending in the stacking direction and electrically connecting the negative current collectors in parallel. An end portion of the positive conductive bus bar is bent and disposed at an end of the redox battery cell stack, and an end portion of the negative conductive bus bar is bent and disposed at another end of the redox battery cell stack. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of an exemplary redox flow battery. [Figure 2a] FIG. 2 is a schematic diagram of a sealed redox cell according to an embodiment. [Figure 2b] FIG. 1 is a schematic diagram of a sealed redox battery including multiple sealed redox battery cells in a stacked configuration, according to some embodiments. [Figure 2c]FIG. 1 is a schematic diagram of a sealed redox battery including a plurality of sealed redox battery cells in a stacked configuration, according to certain other embodiments. [Figure 2d] FIG. 2 is a schematic diagram of a sealed redox battery including multiple sealed redox battery cells in a cylindrical stack configuration, according to an embodiment. [Figure 3a] FIG. 2 is a schematic diagram of a redox battery having electrical and mechanical connections to link multiple redox battery cells. [Figure 3b] FIG. 2 is a schematic diagram of a redox battery having electrical and mechanical connections to link multiple redox battery cells. [Figure 3c] FIG. 2 is a schematic diagram of a redox battery having electrical and mechanical connections to link multiple redox battery cells. [Figure 3d] FIG. 2 is a schematic diagram of a redox battery having electrical and mechanical connections to link multiple redox battery cells. [Figure 4a] FIG. 2 is a schematic diagram of a redox battery having bus bars that provide both electrical and mechanical coupling to connect multiple redox battery cells, according to an embodiment. [Figure 4b] FIG. 2 is a schematic diagram of a redox battery having bus bars that provide both electrical and mechanical coupling to connect multiple redox battery cells, according to an embodiment. [Figure 4c] FIG. 2 is a schematic diagram of a redox battery having bus bars that provide both electrical and mechanical coupling to connect multiple redox battery cells, according to an embodiment. [Figure 4d] FIG. 2 is a schematic diagram of a redox battery having bus bars that provide both electrical and mechanical coupling to connect multiple redox battery cells, according to an embodiment. [Figure 5a] FIG. 2 is a schematic diagram of a redox battery, each including a redox battery cell stack between electrically conductive end plates coupled to a bus bar, according to an embodiment. [Figure 5b]FIG. 2 is a schematic diagram of a redox battery, each including a redox battery cell stack between electrically conductive end plates coupled to a bus bar, according to an embodiment. [Figure 5c] FIG. 2 is a schematic diagram of a redox battery, each including a redox battery cell stack between electrically conductive end plates coupled to a bus bar, according to an embodiment. [Figure 5d] FIG. 2 is a schematic diagram of a redox battery, each including a redox battery cell stack between electrically conductive end plates coupled to a bus bar, according to an embodiment. [Figure 5e] FIG. 2 is a schematic diagram of a redox battery, each including a redox battery cell stack between electrically conductive end plates coupled to a bus bar, according to an embodiment. [Figure 5f] FIG. 2 is a schematic diagram of a redox battery, each including a redox battery cell stack between electrically conductive end plates coupled to a bus bar, according to an embodiment. [Figure 5g] FIG. 2 is a schematic diagram of a plurality of redox batteries, each including a redox battery cell stack between conductive end plates, the redox batteries themselves being stacked and electrically coupled via the conductive end plates, according to an embodiment. [Figure 5h] FIG. 2 is a schematic diagram of a plurality of redox batteries, each including a redox battery cell stack between conductive end plates, the redox batteries themselves being stacked and electrically coupled via the conductive end plates, according to an embodiment. [Figure 5i] FIG. 2 is a schematic diagram of a plurality of redox batteries, each including a redox battery cell stack between conductive end plates, the redox batteries themselves being stacked and electrically coupled via the conductive end plates, according to an embodiment. [Figure 6a] 4 is a schematic diagram of a redox cell with electrically conductive end plates coupled to bus bars according to some other embodiments. [Figure 6b] 4 is a schematic diagram of a redox cell with electrically conductive end plates coupled to bus bars according to some other embodiments. [Figure 6c]4 is a schematic diagram of a redox cell with electrically conductive end plates coupled to bus bars according to some other embodiments. [Figure 6d] 4 is a schematic diagram of a redox cell with electrically conductive end plates coupled to bus bars according to some other embodiments. [Figure 6e] 4 is a schematic diagram of a redox cell with electrically conductive end plates coupled to bus bars according to some other embodiments. [Figure 6f] 4 is a schematic diagram of a redox cell with electrically conductive end plates coupled to bus bars according to some other embodiments. [Figure 6g] 4 is a schematic diagram of a redox cell with electrically conductive end plates coupled to bus bars according to some other embodiments. [Figure 6h] 4 is a schematic diagram of a redox cell with electrically conductive end plates coupled to bus bars according to some other embodiments. [Figure 6i] 4 is a schematic diagram of a redox cell with electrically conductive end plates coupled to bus bars according to some other embodiments. [Figure 6j] FIG. 2 is a schematic diagram of a plurality of redox batteries, each including a redox battery cell stack between conductive end plates, the redox batteries themselves being stacked and electrically coupled via the conductive end plates, according to an embodiment. [Figure 6k] FIG. 2 is a schematic diagram of a plurality of redox batteries, each including a redox battery cell stack between conductive end plates, the redox batteries themselves being stacked and electrically coupled via the conductive end plates, according to an embodiment. [Figure 6l] FIG. 2 is a schematic diagram of a plurality of redox batteries, each including a redox battery cell stack between conductive end plates, the redox batteries themselves being stacked and electrically coupled via the conductive end plates, according to an embodiment. [Figure 6m]FIG. 2 is a schematic diagram of a plurality of redox batteries, each including a redox battery cell stack between conductive end plates, the redox batteries themselves being stacked and electrically coupled via the conductive end plates, according to an embodiment. [Figure 6n] FIG. 13 is an illustration of a final redox cell including a pair of external electrodes that can be received by a user, according to an embodiment. [Figure 7a] FIG. 1 is a schematic diagram of a plurality of redox batteries, each including a redox battery cell stack between conductive end plates, the redox batteries themselves being stacked and electrically coupled via the conductive end plates, according to some embodiments. [Figure 7b] FIG. 13 is a schematic diagram of a plurality of redox batteries, each including a redox battery cell stack between conductive end plates, the redox batteries themselves being stacked and electrically coupled via the conductive end plates, in accordance with some other embodiments. [Figure 7c] FIG. 13 is a schematic diagram of a plurality of redox batteries, each including a redox battery cell stack between conductive end plates, the redox batteries themselves being stacked and electrically coupled via the conductive end plates, in accordance with some other embodiments. [Figure 7d] 13 is a schematic diagram of an exemplary coupling mechanism to prevent coupled redox cells from sliding against one another, according to some other embodiments. FIG. [Figure 7e] 13 is a schematic diagram of an exemplary coupling mechanism to prevent coupled redox cells from sliding against one another, according to some other embodiments. FIG. [Figure 8a] FIG. 1 is a schematic diagram of a redox cell having conductive end plates of opposite polarity configured to be electrically shorted using a conductive shorting structure. [Figure 8b] FIG. 1 is a schematic diagram of a vertically stacked redox cell having conductive end plates of opposite polarity configured to be electrically shorted with a conductive shorting structure. [Figure 8c]FIG. 1 is a schematic diagram of horizontally stacked redox cells having conductive end plates of the same polarity configured to be electrically shorted using a conductive shorting structure. [Figure 8d] FIG. 13 is a schematic diagram of a plurality of redox batteries, each including a redox battery cell stack between conductive end plates, the redox batteries themselves being stacked and electrically coupled via the conductive end plates, in accordance with some other embodiments. [Figure 9a] FIG. 1 is an exploded perspective view of a redox battery cell 10 according to some embodiments. [Figure 9b] FIG. 1 is a side view of a redox battery cell 10 according to some embodiments. [Figure 10a] FIG. 2 is a side view of a redox battery including a plurality of stacked redox battery cells, according to some embodiments. [Figure 10b] FIG. 1 is a perspective view of a redox battery including a plurality of stacked redox battery cells, according to some embodiments. [Figure 11a] FIG. 2 is a side view of a redox battery including a plurality of stacked redox battery cells, according to some embodiments. [Figure 11b] FIG. 2 is a plan view of a redox battery including a plurality of stacked redox battery cells, according to some embodiments. [Figure 12a] FIG. 2 is a side view of a redox battery including a plurality of stacked redox battery cells, according to some other embodiments. [Figure 12b] FIG. 2 is a plan view of a redox battery including a plurality of stacked redox battery cells, according to some other embodiments. [Figure 13] FIG. 1 illustrates a top view of an energy storage device including multiple redox cells, according to some embodiments. [Figure 14] FIG. 1 illustrates a top view of an energy storage device including multiple redox cells, according to some embodiments. [Figure 15a] 1 illustrates a side view of a storage device including multiple redox cells, according to some embodiments. [Figure 15b] 15b shows top and bottom views of the storage device illustrated in FIG. 15a. [Figure 16] FIG. 1 illustrates a side view of an energy storage device including multiple redox cells, according to some embodiments. [Figure 17a] 1A-1C are plan views of two different states of an energy storage device including multiple redox cells, according to some embodiments. [Figure 17b] 1A-1C are plan views of two different states of an energy storage device including multiple redox cells, according to some embodiments. [Figure 18a] FIG. 1 illustrates a top view of an energy storage device including multiple redox cells, according to some embodiments. [Figure 18b] FIG. 1 illustrates a top view of an energy storage device including multiple redox cells, according to some embodiments. [Figure 18c] FIG. 1 illustrates a top view of an energy storage device including multiple redox cells, according to some embodiments. [Figure 19a] FIG. 2 is a plan view of an energy storage device including one or more rows of redox cells, according to some embodiments. [Figure 19b] FIG. 2 is a plan view of an energy storage device including one or more rows of redox cells, according to some embodiments. [Figure 20] FIG. 2 is a plan view of an energy storage device including one or more rows of redox cells, according to some embodiments. [Figure 21] FIG. 2 is a plan view of an energy storage device including one or more rows of redox cells, according to some embodiments. [Figure 22] FIG. 2 is a plan view of an energy storage device including one or more rows of redox cells, according to some embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] As mentioned above, the possible competing factors in selecting and designing an electrochemical energy storage system suitable for a particular application include, among others, investment cost, power, energy, lifetime, recyclability, efficiency, scalability, and maintenance cost. Among various electrochemical energy storage systems, Redox Flow Battery (RFB) is considered suitable for stationary energy storage. RFB is an electrochemical energy conversion device that utilizes the oxidation-reduction process of redox species dissolved in a solution. The solution is stored in an external tank and flows into the RFB cell when needed. Some of the advantageous features of RFB technology are independent scalability of power and energy, high depth of discharge (DOD), and reduced environmental impact. Such features allow a wide range of operating power and discharge times, making RFB preferable for the storage of electricity generated from renewable sources.

[0011] Specific disadvantages of some secondary batteries known in the art, such as lithium ion batteries, include the generation of excessive heat and internal pressure during operation of these batteries. To mitigate such effects, some secondary batteries utilize gaps between battery cells and / or separate cooling devices. Advantageously, in batteries according to embodiments disclosed herein, the generation of heat and pressure is much lower, which ultimately reduces the risk of explosion and may not require gaps or cooling devices between battery cells, thereby allowing for compact packing of the battery cells and the battery itself.

[0012] Various batteries use bus bars to electrically connect the battery cells and / or the batteries themselves. For compact bundling, there is a need to reduce the amount of space occupied by the bus bars by efficiently arranging the bus bars. In addition to electrically connecting the battery cells and the batteries, there is another need to physically and mechanically hold either the battery cells or the batteries in an efficient manner. To address these and other needs, various embodiments disclosed herein provide bus bars that enable high-density bundling of battery cells and / or batteries, and energy storage devices including the same. Additionally, embodiments disclosed herein provide batteries and energy storage devices including the same that are easy to maintain after installation.

[0013] FIG. 1 is a schematic diagram of an exemplary redox flow battery (RFB). The RFB 100 includes a battery cell 104. The battery cell 104 has a first half-cell 104A and a second half-cell 104B separated by a separator or ion exchange membrane 112. The first half-cell 104A includes a positive electrolyte reservoir 106A having a first or positive electrolyte and a positive electrode disposed therein, and the second half-cell 104B includes a negative electrolyte reservoir 106B having a second or negative electrolyte and a negative electrode disposed therein. The positive electrode is electrically coupled to a positive current collector 108A, and the negative electrode is electrically coupled to a negative current collector 108B. The positive electrolyte reservoir 106A is physically coupled in fluid communication with a positive electrolyte tank 116A, and the negative electrolyte reservoir 106B is physically coupled in fluid communication with a positive electrolyte tank 116B. In operation, positive electrolyte is circulated between the positive electrolyte tank 116A and the positive electrolyte reservoir 106A via outlet and inlet conduits 120A, 124B using positive electrolyte pump 128A, as represented by the arrows. Similarly, negative electrolyte is circulated between the negative electrolyte tank 116B and the negative electrolyte reservoir 106B via outlet and inlet conduits 120B, 124B.

[0014] In some configurations, a plurality of battery cells 104-1, 104-2, ..., 104-n are stacked to form an RFB cell 150, with each cell configured in a manner similar to battery cell 104. The plurality of battery cells 104-1, 104-2, ..., 104-n includes respective positive electrode electrolyte reservoirs of positive electrode electrolyte reservoirs 106A that can be in fluid communication with each other, and respective negative electrode electrolyte reservoirs of negative electrode electrolyte reservoirs 106B that can be in fluid communication with each other. The linked positive electrode electrolyte reservoirs of positive electrode electrolyte reservoirs 106A are in sequential fluid communication with the positive electrode electrolyte tank 116A, and the linked negative electrode electrolyte reservoirs of negative electrode electrolyte reservoirs 106B are in sequential fluid communication with the negative electrode electrolyte tank 116B.

[0015] Compared to other electrochemical storage technologies, such as lithium-ion, lead-acid, and sodium-sulfur batteries, RFBs offer several advantages, including the decoupling of power conversion from energy storage, allowing independent power and energy scaling. For example, RFBs can be tuned in a flexible and distributed manner depending on the application, and can be scaled to provide power and energy ranging from, for example, a few kW / kWh for home storage to systems with several to tens of MW / MWh for grid storage. Also, unlike fuel cells, the reactions in RFBs are reversible, allowing the same cell to operate as a converter converting electricity into chemical energy and vice versa. RFBs do not consume ionic metals and operate by changing the metal ion valence, allowing for a long period of service life. Cell temperature is relatively easy to control, in part, by regulating electrolyte flow with a relatively high heat capacity electrolyte. Very deep depths of discharge (DOD) can be achieved, while state of charge (SOC) is easy to monitor via cell voltage.

[0016] Despite the various advantages of RFBs, their commercialization has not been widespread compared to other electrochemical storage technologies, despite the relatively large capital, research, and development investments made into the technology over the decades. In particular, widespread commercialization has not yet occurred despite the recent surge in battery demand for ESS applications and the apparent suitability of RFBs for those applications, including greater safety against fire and explosion, suggesting that there are significant obstacles to the commercialization of RFBs, although a long felt need. The present inventors have identified a variety of these obstacles, including relatively low reliability, low efficiency, large system area, and high system complexity.

[0017] The first obstacle to the widespread commercialization of RFBs, similar to the RFB 100 described above with respect to FIG. 1, relates to the relatively high complexity of RFBs and the reliability issues associated therewith. As described above, the RFB includes multiple conduits 120A, 120B, 124A, 124B for transporting electrolyte to and from the battery cells 104, pumps 128A, 128B for circulating the electrolyte, and tanks 116A, 116B for storing the electrolyte. Due to the relatively high complexity, the various connection points for the conduits 120A, 120B, 124A, 124B between the battery cells 104 and the tanks 116A, 116B can lead to reliability issues, e.g., leakage. The probability and frequency of errors increases in proportion to the number of these conduits, which scales with the size of the ESS. When errors occur, they lead to unscheduled repairs as well as safety risks. Additionally, reducing the likelihood of these errors and ensuring uninterrupted operation through preventative maintenance translates into additional operational costs.

[0018] A second obstacle to the widespread commercialization of RFBs relates to the relatively low efficiency of RFBs. One reason for the relatively low efficiency relates to the energy consumed to circulate the electrolyte. For example, for vanadium-based RFBs, the electrolyte includes sulfuric acid, which has a relatively high viscosity. Circulating the electrolyte, especially an electrolyte with a relatively high viscosity, through the fine porous structure of the randomly oriented carbon fiber felt-based electrodes can consume a relatively large amount of positive electrode external energy, lowering the external efficiency of the RFB. The lower external efficiency of RFB systems is one of the main reasons for their lower commercial competitiveness compared to competing secondary battery technologies, such as lithium-ion battery (LIB) technology.

[0019] A third obstacle to the widespread commercialization of RFBs is their relatively lower power and energy densities compared to other electrochemical storage technologies, which hinder their mobile applications. As described herein, power and energy densities refer to the power output and energy storage, respectively, of the storage device relative to the total volume of the energy storage device. Thus, for RFBs, power and energy densities refer to the ratio of power output and energy storage to the total volume, including the cell volume, the tank volume, and the volume of the conduits for transporting the electrolyte. To partially compensate for the lower power and energy densities, RFBs often have relatively large cell active areas and membranes, causing increased cell dimensions, which in turn can cause high transverse gradients of the internal electrolyte of the electrolyte reservoirs 116A, 116B. As a result, the average current density and nominal current of RFBs may be substantially lower than the maximum theoretical values ​​based on a uniform maximum current density. Also, the need for a circulation system, including separate tanks and conduits, further reduces the space efficiency at the overall system level.

[0020] A fourth obstacle to widespread commercialization of RFBs relates to the system complexity, which can be compared to that of a chemical plant. The complexity of designing an RFB system is high, which ultimately increases the development cycle, which ultimately results in a fairly slow technology development. Furthermore, the system complexity is labor and capital intensive, requiring a high level of expertise for installation, maintenance, and removal at the ESS site. The system complexity puts consumers off by the associated increase in overall costs, as well as the potential need for increased manpower deployment and training required to build and maintain the system.

[0021] To address these and other limitations while retaining most of the advantages provided by RFBs, the present disclosure relates to a sealed redox battery that does not need to be connected to separate electrolyte tanks. The present disclosure also relates to a bus bar that allows for efficient bundling of multiple redox battery cells that can be sealed. However, it is recognized that the inventive concepts, including the sealed redox battery and the bus bar, can be implemented individually or in combination.

[0022] Sealed redox battery In one embodiment, various embodiments of the redox battery disclosed herein relate to a redox battery. The redox battery according to the embodiment overcomes or mitigates at least partially some of the commercialization obstacles of RFBs described above while retaining the advantages of RFBs. In particular, unlike some RFBs, while using a redox couple involved in the redox reaction, the redox battery embodiments disclosed herein include a sealed redox battery cell and do not have a separate electrolyte tank connected to the redox battery cell, nor an electrolyte circulation device such as a pump to supply electrolyte from outside the redox battery cell.

[0023] FIG. 2a is a schematic diagram of a sealed redox battery according to an embodiment. The illustrated sealed redox battery 200A includes a first half-cell 204A and a second half-cell 204B. The first half-cell 204A includes a positive electrolyte reservoir 106A having a first or positive electrolyte disposed therein in contact with the positive electrode. The first electrolyte has a first redox couple dissolved therein configured to undergo a first redox half-reaction. The second half-cell 204B includes a negative electrolyte reservoir 106B having a second or negative electrolyte disposed therein in contact with the negative electrode. The second electrolyte has a second redox couple dissolved therein configured to undergo a second redox half-reaction. The positive and negative electrolyte reservoirs 106A, 106B define a reaction space for each half-reaction. The sealed redox battery 200A also includes an ion exchange membrane 112 separating the positive electrolyte reservoir 106A and the negative electrolyte reservoir 106B. The positive electrode is electrically connected to the positive current collector 108A, and the negative electrode is electrically connected to the negative current collector 108B. In some embodiments, a first bipolar plate 208A is interposed between the positive current collector 108A and the positive electrolyte reservoir 106A, and a second bipolar plate 208B is interposed between the negative current collector 108B and the negative electrolyte reservoir 106B.

[0024] Unlike a conventional RFB, in the sealed redox battery 200, the first half-cell 204A, the second half-cell 204B, and the ion exchange membrane 112 define a sealed redox battery cell in a casing or frame 212. The sealed casing 212 renders its internal contents physically inaccessible from the outside under normal operation. That is, the positive and negative electrolytes are not in fluid communication with an external container, such as an electrolyte tank. The casing 212 may hermetically and / or permanently enclose the redox battery 200A. This configuration contrasts with a conventional redox flow battery, in which the redox battery cell is in fluid communication with an external tank. That is, in the sealed redox battery 200A, unlike the RFB 100 described above with respect to FIG. 1, neither the positive electrolyte reservoir 106A nor the negative electrolyte reservoir 106B within the enclosed cell are in fluid communication or physically connected to a separate electrolyte tank that stores the respective electrolyte, either the first electrolyte or the second electrolyte. Thus, substantially the entire volume of positive and negative electrolytes are stored within the redox battery cells and hermetically enclosed by the casing 212. That is, the first electrolyte reservoir 106A stores substantially the entire volume of the first electrolyte for the first half-cell 204A, and the second electrolyte reservoir 106B stores substantially the entire volume of the second electrolyte for the second half-cell 204B. Unlike the RFB 100 illustrated in FIG. 1, since the partially sealed redox battery 200A is not connected to a separate storage tank, the sealed redox battery 200A preferably does not include conduits 120A, 120B, 124A, 124B (FIG. 1) for transporting electrolyte to and from the redox battery cells, nor pumps 128A, 128B (FIG. 1) for circulating the electrolyte.

[0025] As mentioned above, a notable structural difference in the sealed redox battery 200A is the omission of the pumps 128A, 128B (FIG. 1). Instead, in accordance with an embodiment, the sealed redox battery 200A is configured such that the first and second electrolytes circulate spontaneously within the electrolyte reservoirs, the positive electrolyte reservoir 106A of the first half-cell 204A and the negative electrolyte reservoir 106B of the second half-cell 204B. In various configurations, the spontaneous circulation of the first and second electrolytes is caused by one or more of the following: an osmotic pressure difference between the first and second electrolyte reservoirs; density changes of one or both of the first and second electrolytes; diffusion or migration of one or both of the first and second electrolytes; affinity of one or both of the first and second electrolytes for each of the first and second electrodes; first and second redox half-reactions; and thermal expansion or contraction of one or both of the first and second electrolytes. The inventors have found that self-circulation is effective in providing stability in power and energy output when the thickness of the positive and negative electrolyte reservoirs 106A, 106B in the cross-sectional view of FIG. 2a does not exceed a range of values ​​defined by 20 cm, 15 cm, 10 cm, 5 cm, 2 cm, 1 cm, or any of these values.

[0026] 2a, the casing 212 is formed of a corrosion-resistant material suitable for containing the positive and negative electrolytes, which may be quite acidic. In addition to providing corrosion resistance, the casing 212 may be a rigid casing to provide mechanical support for the sealed redox cell 200A. In some embodiments, at least a portion of the casing 212 according to the embodiment may be formed of a flexible material configured to deform to accommodate changes in internal pressure within the positive and negative electrolyte reservoirs 106A, 106B. For example, for a pressure-controlled sealed redox cell, an increase in internal pressure may be caused by various effects described below. In configurations in which only a portion of the casing is formed of a flexible material, the remainder may be formed of a rigid material. The flexible portion may be configured to expand in response to an increase in pressure, for example, to accommodate an increase in the respective volumes of one or both of the positive and negative electrolyte reservoirs 106A, 106B of greater than 0.1%, 0.2%, 0.5%, 1%, 2%, 5%, 10%, 20%, 50%. Suitable materials for the casing 212 may include polyvinyl chloride (PVC), polyethylene (PE), polystyrene (PS), polypropylene (PP), polycarbonate (PC), ABS, reinforced plastics, and the like.

[0027] The sealed redox battery 200A configured in this manner provides various technical and commercial advantages. For example, various unreliability issues with conduits, e.g., pipe joints, between the redox battery cells and the tank, as well as pumps for circulating the electrolyte, are substantially reduced or eliminated, which ultimately reduces unplanned repairs as well as safety risks and operating costs associated with the operation of the sealed redox battery 200A. Also, as described above for the RFB 100 (FIG. 1), by eliminating the need to circulate electrolyte between the redox battery cells and the tank using a pump, external efficiency is substantially improved. The inventors have found that, depending on the size of the system, the sealed redox battery 200A improves power or energy density by up to 2-50 times compared to conventional RFBs by eliminating the need to circulate electrolyte between the cells and the electrolyte tank. As described above, power or energy density refers to the power or energy output, respectively, of a storage device relative to the total volume of the energy storage device. Thus, for a sealed redox battery, power or energy density refers to the ratio of power or energy output, respectively, to the total volume of the sealed redox battery. Also, the elimination of a circulation system including separate tanks, pumps, and conduits greatly improves space efficiency. Furthermore, the greatly reduced system complexity greatly reduces the barriers to commercial implementation of the sealed redox battery 200A. For example, unlike conventional RFBs, the sealed redox battery 200A can be manufactured in packs similar to lithium ion batteries for modular implementation, eliminating the need for the intrusive configuration required to install conventional RFBs, making them more suitable for automation and mass production.

[0028] The operating principles and embodiments of the sealed redox cell 200A will now be described using an example of a sealed vanadium redox cell based on a vanadium (V)-based redox couple, although it is understood that the embodiments are not so limited and that the principles described herein can be applied to redox cells with a variety of other redox couples.

[0029] In a sealed V redox battery according to the embodiment, the first redox couple dissolved in the first or positive electrolyte of the first half-cell 204A is V 4+ / V 5+ a second redox couple dissolved in the second or negative electrolyte of the second half-cell 204B, V 2+ / V 3+ The redox reaction during charging and discharging can be described using the following formula, where → indicates the discharge reaction direction and ← indicates the charge reaction direction. Second half cell / negative electrode: V 2+ ←→V 3+ +e - First half cell / positive electrode: V 5+ +e - ←→V 4+ Overall reaction: V 2+ +V 5+ ←→V 3+ +V 4+

[0030] During charging, tetravalent vanadium ions (V 4+ ) is a pentavalent vanadium ion (V 5+ ) in the second half-cell 204B, while trivalent ions (V 3+ ) is a divalent ion (V 2+ During discharge, in the first half-cell 204A, the pentavalent vanadium ions (V 5+ ) is a tetravalent vanadium ion (V 4+ ) in the second half-cell 204B, while divalent ions (V 2+ ) is a trivalent ion (V 3+ During these redox reactions, electrons are transported through the external circuit and certain ions diffuse across the ion exchange membrane 112 to balance the electroneutrality of the positive and negative half-cells, respectively.

[0031] According to various embodiments, other redox reactions can be implemented in the sealed redox cell 200A. According to various embodiments, the first redox couple and / or the second redox couple include ions of one or more of vanadium (V), zinc (Zn), bromine (Br), chromium (Cr), manganese (Mn), titanium (Ti), iron (Fe), cerium (Ce), and cobalt (Co). In some embodiments, the first redox couple and / or the second redox couple include ions of the same metals as the sealed V redox cell described above. In these embodiments, preferably, mixing of the positive and negative electrolytes does not result in cross-contamination of these electrolytes.

[0032] As described herein, the electrolyte of a redox battery is a solution that conducts electric current by ionization. The electrolyte serves to support the reduced and oxidized forms of the redox couple, and also supports the cations and anions to balance the charge of the ions in the solution during oxidation and reduction of the redox couple. The positive and negative electrolytes according to the embodiment include an acidic aqueous solution. In the case of a sealed V redox battery, the concentration of V ions is related to the energy density of the electrolyte. A higher energy density is preferable and can serve to reduce the volume of the positive and negative electrolyte reservoirs 106A, 106B required for a given amount of energy and power output. However, too high a concentration of V ions can reduce the stability of the V ions. Thus, there is an optimal range of V ions for a given application. For example, the vanadium ions dissolved in one or both of the first and second electrolytes may be greater than 1.0M, 1.5M, 2.0M, 2.5M, or any value within the range defined by these values. On the other hand, V ion concentrations below 1.0 M may result in energy levels that are not suitable for some applications. On the other hand, V ion concentrations above 2.5 M may result in V ion levels that are not suitable for some applications, for example at operating temperatures above 50° C. 5+ This can cause a lower stability of the ions, for example, at operating temperatures below -20°C, the V 2+ and V 3+The solubility limit of the ion can be approached.

[0033] Preferably, according to embodiments, the positive and negative electrolytes may contain the same solvent and / or ions of the same metal. In these embodiments, mixing of the positive and negative electrolytes through the ion exchange membrane 112 does not cause contamination of the respective half-cells. Also, the positive and negative electrolytes may be prepared from the same starting solvent and solutes. For example, for a sealed V redox battery according to some embodiments, the positive and negative electrolytes both contain sulfuric acid. The electrolyte contains tetravalent vanadium ions (V 4+ ) and / or trivalent vanadium ions (V 3+ For example, 0.1M to 2.5M VOSO4 (vanadyl sulfate) is dissolved in 0.1M to 6M H2SO4 in an aqueous solution to form 5-valent vanadium ions (V 5+ ) can be electrochemically reduced to form a positive electrolyte (anode electrolyte) containing a solution of vanadium ions (V 2+ A negative electrode electrolyte (cathode solution) can be formed containing a solution of

[0034] 2a, in various embodiments, the positive and negative electrodes disposed in the positive and negative electrolyte reservoirs 106A, 106B, respectively, include carbon-based materials such as carbon or graphite felt, carbon cloth, carbon black, graphite powder, and graphene, to name a few. Carbon-based materials are preferred and provide a relatively high operating range, excellent stability, and high reversibility. The electrodes are optimized for relatively high electrochemical activity, low bulk resistivity, and large specific area. Improving the electrochemical activity of the electrodes increases the energy efficiency of the sealed redox battery 200A. To improve the performance of the sealed redox battery 200A, the surfaces of the electrodes can be modified, for example, by coating with a metal, increasing the surface roughness, or doping with an additive.

[0035] The positive and negative electrolyte reservoirs 106A, 106B that define the reaction space are filled partially or completely with the respective electrodes between the ion exchange membrane 112 and the first and second bipolar plates 208A, 208B, respectively, or between the ion exchange membrane 112 and the positive and negative current collectors 108A, 108B, respectively, if present. After filling with the respective electrodes, the remaining space of the positive and negative electrolyte reservoirs 106A, 106B is filled partially or completely with the respective electrolyte between the ion exchange membrane 112 and the first and second bipolar plates 208A, 208B, respectively, or between the ion exchange membrane 112 and the positive and negative current collectors 108A, 108B, respectively, if present. In various embodiments, unless purposely punched or porous as described below, the ion exchange membrane 112 serves to substantially separate the two half-cells and substantially prevent intermixing of the two electrolytes and redox couples while providing a H + The ion exchange membrane 112 allows for the transport of ions such as cations, ions, and ions. The ion exchange membrane 112 may be an anion exchange membrane or a cation exchange membrane. The ion exchange membrane 112 may include perfluorinated ionomers, partially fluorinated polymers, and non-fluorinated hydrocarbons, to name several categories of materials. Specific examples of ion exchange membranes 112 include Nafion®, Flemion®, NEOSEPTA-F®, and Gore Select®, which offer excellent chemical stability, high electrical conductivity, and mechanical strength.

[0036] Although various illustrated embodiments include an ion exchange membrane 112 that is selective to a particular type of ion, e.g., cations or anions, embodiments are not limited thereto. For example, in various embodiments, the ion exchange membrane 112 can be a non-selective membrane, e.g., a porous membrane.

[0037] 2a, in some embodiments, the output power can be expanded by connecting multiple single redox battery cells, for example in series, to form a cell stack. In such a configuration, the first bipolar plate 208A and the second bipolar plate 208B can enable the series connection of single cells and eliminate the current collectors 108A, 108B between adjacent bipolar plates. The first bipolar plate 208A and the second bipolar plate 208B can be formed of a suitable material, such as graphite, carbon, carbon plastic, etc., to provide high electrical conductivity and low internal resistance for the cell stack. Additionally, the first bipolar plate 208A and the second bipolar plate 208B support the contact pressure experienced by the electrodes when pressed against them to increase electrical conductivity. Additionally, the first bipolar plate 208A and the second bipolar plate 208B are provided with high acid resistance to prevent corrosion or oxidation of the current collectors 108A, 108B.

[0038] The positive and negative current collectors 108A, 108B comprise a highly electrically conductive metal, such as copper or aluminum, and serve to conduct electrical current during the charging and discharging processes.

[0039] Because the single sealed redox cell 200A described above has an output voltage characteristic of the electrochemical reaction, for example, about 1.65 V or less, additional cells can be electrically connected in series or parallel to achieve higher voltages and currents, respectively, as described herein.

[0040] 2b is a schematic diagram of a sealed redox battery including a plurality of sealed redox battery cells in a stacked configuration, according to some embodiments. The exemplary sealed redox battery 200B includes a plurality of redox battery cells 200B-1, 200B-2, ..., 200B-n that may be stacked, where each cell is configured in a manner similar to the sealed redox battery 200A (FIG. 2a). Each of the plurality of redox battery cells 200B-1, 200B-2, ..., 200B-n includes a positive electrolyte reservoir 106A, a negative electrolyte reservoir 106B, and an ion exchange membrane 112. In the exemplary embodiment, each of the plurality of redox battery cells 200B-1, 200B-2, ..., 200B-n is separately sealed by a casing 212. The multiple redox battery cells 200B-1, 200B-2, . . . , 200B-n are electrically connected in series to increase the output voltage.

[0041] 2c is a schematic diagram of a sealed redox battery including a plurality of sealed redox battery cells in a stacked configuration according to some other embodiments. The exemplary sealed redox battery 200C includes a plurality of redox battery cells 200C-1, 200C-2, ..., 200C-n that may be stacked, where the plurality of redox battery cells 200C-1, 200C-2, ..., 200C-n are configured in a manner similar to the sealed redox battery 200A (FIG. 2a), including a positive electrolyte reservoir 106A, a negative electrolyte reservoir 106B, and an ion exchange membrane 112. However, unlike the sealed redox battery 200B (FIG. 2b), in the exemplary embodiment, the plurality of redox battery cells 200C-1, 200C-2, ..., 200C-n are surrounded by a common casing 222. In a manner similar to the sealed redox battery 200B (FIG. 2b), the multiple redox battery cells 200C-1, 200C-2, ..., 200C-n are electrically connected in series to increase the output voltage. Moreover, in some embodiments, the positive electrode electrolyte reservoirs 106A of the multiple redox battery cells 200C-1, 200C-2, ..., 200C-n can be in fluid communication with each other, and the negative electrode electrolyte reservoirs 106B of the multiple redox battery cells 200C-1, 200C-2, ..., 200C-n can be in fluid communication with each other. The sealed redox battery 200C can be configured as a pouch-type redox battery or a rigid case-type redox battery.

[0042] 2d is a schematic diagram of a sealed redox battery including a plurality of sealed redox battery cells in a cylindrical stacked configuration, according to an embodiment. The exemplary sealed redox battery 200D includes a plurality of redox battery cells 200D-1, 200D-2, ..., 200D-n that may be cylindrically stacked, where the plurality of redox battery cells 200D-1, 200D-2, ..., 200D-n are configured in a manner similar to the sealed redox battery 200A (FIG. 2a) including a positive electrolyte reservoir 106A, a negative electrolyte reservoir 106B, and an ion exchange membrane 112. The plurality of redox battery cells 200D-1, 200D-2, ..., 200C-n may be individually enclosed in a casing in a manner similar to that described above for the sealed redox battery 200B (FIG. 2b). Instead, the multiple redox battery cells 200D-1, 200D-2, ..., 200C-n may be surrounded by a common casing 222 in a manner similar to that described above for the sealed redox battery 200C (FIG. 2c). In a manner similar to the sealed redox battery 200B (FIG. 2b), the multiple redox battery cells 200D-1, 200D-2, ..., 200D-n may be electrically connected in series to increase the output voltage. Furthermore, in some embodiments, the positive electrode electrolyte reservoirs 106A of the multiple redox battery cells 200D-1, 200D-2, ..., 200D-n may be in fluid communication with each other, and the negative electrode electrolyte reservoirs 106B of the multiple redox battery cells 200D-1, 200D-2, ..., 200D-n may be in fluid communication with each other.

[0043] It will be appreciated that some or all of the multiple redox battery cells in each of the stack configurations described above with respect to Figures 2b-2c may be electrically connected in series by appropriately electrically connecting the opposite polarity current collectors of some or all of the cells, or electrically connected in parallel by appropriately electrically connecting the same polarity current collectors of some or all of the cells.

[0044] Differences between sealed redox batteries and conventional secondary batteries The differences and advantages of the sealed redox battery according to the embodiments over conventional RFBs have been described above, including the elimination of the pumping system, the interconnection network of conduits, and the electrolyte tank that contributed to the slow commercial implementation of conventional RFBs. Although the separate electrolyte tank is not required, the sealed redox battery 200A-200D (FIGS. 2a-2d) maintains some of the inherent design flexibility available in conventional RFBs. For example, due to the inherent malleability of the liquid, the design of the cell geometry is much more flexible than in conventional secondary batteries. Furthermore, the power and energy storage capacity can be independently expanded to a limited extent, for example, by adjusting the ratio of electrolyte volume to electrode surface area. The ratio can be adjusted, for example, using the thickness of the positive and negative electrolyte reservoirs 106A, 106B, as described above. On the other hand, the sealed redox battery according to the embodiments also shares the main advantages of conventional batteries, since it is completely sealed to allow for modular implementation. Although a sealed redox battery according to the embodiments, e.g., a LIB, may have components that are referred to using similar terminology, it is recognized that the components of a sealed redox battery according to the embodiments, and their operating principles, are distinguishable from conventional secondary batteries, etc. In the following, a comparison may be made between a sealed redox battery according to the embodiments and a LIB, but it is understood that the comparison is applicable to other conventional secondary batteries.

[0045] First, the structure, functional operation, and operation principle of the electrolyte in the sealed redox battery according to the embodiment are distinguishable from the structure, functional operation, and operation principle of a conventional secondary battery, e.g., a LIB. In operation, in a LIB, the electrolyte does not store energy itself, nor does it participate in the electrochemical reactions in the charge and discharge process. Instead, the electrolyte in a LIB serves primarily to provide a path for lithium ions to be transported between the positive and negative electrodes during the charge and discharge process. Thus, the movement of the electrolyte is not substantially restricted by a separator. In contrast, in the sealed redox battery 200A according to the embodiment, electrochemical energy is stored in the electrolyte in the form of dissolved active materials, e.g., the respective redox couples dissolved in the positive and negative electrolytes that undergo electrochemical reactions during the charge and discharge process. Thus, the electrolyte can be said to be a medium for storing energy in the sealed redox battery according to the embodiment. In the example of a V redox battery, as described above, the oxidation states of the V ionic species dissolved in the positive and negative electrolytes change through the respective half-reactions. Therefore, the chemical composition of the positive and negative electrolytes in a sealed redox battery is different from that of a LIB. Furthermore, unlike a LIB, in a sealed redox battery according to the embodiments, mixing of the positive and negative electrolytes causes a loss of stored energy because the electromotive force due to the difference in the chemical composition of the positive and negative electrolytes leads to energy storage.

[0046] Second, the structure, functional operation, and operating principle of the electrodes in the sealed redox battery according to the embodiments are distinguishable from those of conventional secondary batteries, such as LIBs. In LIBs, the active materials included in the electrodes directly participate in the electrochemical reaction. In operation, in LIBs, lithium ions are transferred between the active materials of the positive electrode and the active materials of the negative electrode to achieve electrochemical equilibrium, and the electrodes themselves act as the main medium for storing energy. In contrast, the electrodes of the sealed redox battery according to the embodiments work very differently from each other. The positive electrode of the sealed redox battery does not participate in the first redox half-reaction, and the negative electrode of the sealed redox battery does not participate in the second redox half-reaction. As described herein, the electrodes that do not participate in the redox half-reaction do not eliminate the function of the electrodes as catalysts and provide physical sites for electrochemical reactions in a similar manner. However, the electrodes themselves do not participate in the electrochemical reaction, and redox ions do not transfer between the positive and negative electrodes during charging and discharging of the redox battery. Depending on the composition, functional groups that act as catalysts may be present on the surface. However, this is distinguishable from electrodes that actively participate in the electrochemical reaction, as in LIBs: instead, electrodes essentially passively transport electrons generated by the electrochemical reaction.

[0047] Third, the structure, functional operation, and working principle of the ion exchange membrane in the sealed redox battery according to the embodiment are distinguishable from those of conventional secondary batteries, such as the separators of LIBs. In LIBs, the active materials of the electrodes where the electrochemical reaction occurs are generally in a solid state, and the separators disposed between the positive and negative electrodes mainly serve to prevent electrical shorts between the electrodes. Thus, although the separators serve to prevent electrical contact between the positive and negative electrodes, the separators in LIBs are not specifically designed to limit the transport of lithium ions therethrough or to limit the electrochemical reaction therebetween. In other words, the separators in LIBs mainly serve to not impede the transport of ions as part of the electrochemical reaction for charging and discharging, and to electrically insulate the positive and negative electrodes from each other. Thus, the separators for LIBs are designed to freely transport lithium ions between the electrodes. In contrast, in a sealed redox battery according to an embodiment, the redox active species dissolve in the electrolyte, and the ion exchange membrane 112 (FIG. 2a) serves to electrically separate the positive and negative electrolytes and prevent them from mixing with each other. Typically, the ion exchange membrane 112 comprises a selectively permeable membrane between which cations or anions are transported to balance the charge between the two half-cells. For example, the ion exchange membrane can be configured to selectively pass cations or anions. Thus, in a sealed redox battery according to an embodiment, the electrolyte that stores energy is liquid, so there is no ion exchange membrane 112, and mixing of the positive and negative electrolytes creates an electrical short circuit, regardless of whether the positive and negative electrodes are in contact with each other. Thus, in a sealed redox battery according to an embodiment, the first and second redox half-reactions occur without substantial transport of ions of the first or second redox pair across the ion exchange membrane 112 that separates the positive and negative electrolyte reservoirs 106A and 106B. As described herein, an ion exchange membrane 112 that does not substantially transport ions of a redox pair refers to an ion exchange membrane 112 that serves to substantially prevent electrolyte crossover between the positive and negative electrode electrolyte reservoirs 106A, 106B (FIG. 2a).Thus, the material for the ion exchange membrane 112 preferably blocks the movement of redox species in the electrolyte, e.g., V ions in a V redox battery, and other ions for charge balancing between the half-cells, e.g., H in a V redox battery. + It may be a membrane that selectively permits the movement of ions, but an ion exchange membrane 112 that does not substantially transport ions of a redox pair may nevertheless permit unintended crossover or limited intended intermixing to alleviate internal pressure buildup.

[0048] Busbars for connecting stacked redox battery cells As discussed above with respect to Figures 2a-c, multiple redox battery cells, e.g., sealed redox battery cells, can be electrically connected in series or parallel to extend one or more of voltage, power, and energy. Figures 3a-d are schematic diagrams of a redox battery having electrical and mechanical connections to connect multiple redox battery cells, according to some example implementations.

[0049] Figure 3a illustrates various components for a single redox battery cell similar in some aspects to those described above for Figure 2a. The single redox battery cell 300A in cross-sectional side view includes a first half-cell 304A and a second half-cell 304B. In addition to the various corresponding components described above, the details of which are not repeated herein for the sake of brevity, the example redox battery cell 300A also includes a mechanical frame or casing 308, bipolar plates 208A, 208B, and a sealant 312 that fills gaps between the mechanical frame 308 and adjacent components, including the ion exchange membrane 112, to prevent leakage of electrolyte from each of the reservoirs 106A, 106B.

[0050] FIG. 3b is a cross-sectional side view of a redox battery 300B including a stack of redox battery cells 300A-1, 300A-2, ..., 300A-n arranged in a stacked configuration and electrically coupled using bus bars 316, 318. Bus bar 316 may be a negative bus bar extending in the stacking direction across the top surface of the stack, and bus bar 318 may be a positive bus bar extending in the stacking direction across the bottom surface of the stack. In a manner similar to the multiple redox battery cells described above with respect to FIGS. 2b-d, the exemplary redox battery cells 300A-1, 300A-2, ..., 300A-n may be electrically coupled in series to increase the output voltage. Additionally, in some embodiments, the positive electrolyte reservoirs 106A of the multiple redox battery cells 300A-1, 300A-2, ..., 300A-n may be in fluid communication with each other, and the negative electrolyte reservoirs 106B of the multiple redox battery cells 300A-1, 300A-2, ..., 300A-n may be in fluid communication with each other. The positive current collector 108A is electrically coupled to a positive bus bar 316, and the negative current collector 108B is electrically coupled to a negative bus bar 318. The example redox battery 300B also includes an insulator 320 and a conductive end plate 324 on each end of the stack. Each of the positive bus bar 316 and the negative bus bar 318 extends in the layer stack direction to electrically couple and overlap multiple cells.

[0051] 3c is a side cross-sectional view of a redox battery 300C including a stack of redox battery cells 300A-1, 300A-2, ..., 300A-n electrically connected using bus bars 316, 318 in a stacked configuration, in a manner similar to the redox battery 300B illustrated in FIG. 3b, the description of similar components is omitted herein for the sake of brevity. Unlike the example illustrated in FIG. 3b, in the example redox battery 300C, in addition to the positive bus bar 316 and the negative bus bar 318 configured to provide electrical connection across the different redox battery cells 300A-1, 300A-2, ..., 300A-n, separate mechanical connection means are provided to substantially hold or fasten the cells together, improving cell reliability. For example, without an additional fastening mechanism to compress the redox battery cell stack, electrolyte may leak and / or the cells may separate. Unlike the example illustrated in FIG. 3b, the redox cell 300C of FIG. 3c is physically held together using fasteners 328, e.g., tie bars. That is, in addition to the positive and negative current collectors 108A, 108B electrically coupled to the positive and negative bus bars 316, 318, respectively, one or more fasteners 328 extend in a stacking direction across the cells on one or more sides of the stack. The fasteners 328 are fastened, anchored, or secured to conductive end plates 324 at both ends of the cell stack using a suitable fastening mechanism, e.g., an adjustable fastening mechanism such as a screw mechanism. The fasteners 328 may be rigid or flexible and may have any suitable shape, e.g., straps, lines, or rods. In the illustrated example, the fasteners 328 extend outside the stack across all four sides of the entire stack and further extend through the conductive end plates 324 to provide compressive pressure therebetween. It will be appreciated that the fastener ports primarily provide a mechanical function of compressing the redox battery cells and therefore may be formed of any suitable material, for example a resilient material that is not electrically conductive.

[0052] 3d is a side cross-sectional view (left) and a top view (right) of a redox battery 300D including a stack of redox battery cells 300A-1, 300A-2, ..., 300A-n in a stacked configuration and electrically coupled using bus bars 316, 318. Except for the arrangement of the bus bars 316, 318, the redox battery 300C is arranged in a similar manner to the redox battery 300C illustrated in FIG. 3c, and a description of similar components is omitted herein for the sake of brevity. Unlike the redox battery 300C (FIG. 3c) in which the negative bus bar 316 and the positive bus bar 318 extend on opposite (top and bottom) faces of the cell stack, the bus bars 316, 318 in the illustrated redox battery cell 300D extend across the same (top) face of the cell stack. The fastening holes 328 extend on the opposing surface that the bus bars 316, 318 do not extend on.

[0053] The inventors have discovered that for a variety of reasons, including reducing the size and complexity of multiple bundled redox battery cells in a stacked configuration, there may be substantial advantages in integrating both the mechanical and electrical functions of a bus bar to simplify integration into a redox battery cell stack. Accordingly, various embodiments are now described in which a bus bar electrically couples multiple cells as well as serving as a mechanical fastener.

[0054] 4a-4d are schematic diagrams of a redox battery including bus bars that provide both electrical and mechanical / structural connections to connect multiple redox battery cells. In each of the figures, in a manner similar to that described above for Figures 3a-3d, an example redox battery 400A-1, 400A-2, 400B, 400C, 400D includes multiple redox battery cells 300A-1, 300A-2, ..., 300A-n stacked in a stacking direction, each of the redox battery cells 300A-1, 300A-2, ..., 300A-n including a first half-cell 304A in contact with the positive current collector 108A, a second half-cell 304B in contact with the negative current collector 108B, and an ion exchange membrane 112 separating the first half-cell 304A and the second half-cell 304B. The redox battery also includes one or more positive conductive bus bars extending lengthwise in the stacking direction to connect, for example, electrically in parallel, the positive current collectors 108A of the redox battery cells 300A-1, 300A-2, ..., 300A-n, and one or more negative conductive bus bars extending lengthwise in the stacking direction to connect, for example, electrically in parallel, the negative current collectors 108B of the redox battery cells 300A-1, 300A-2, ..., 300A-n. Descriptions of components configured similarly to the components of the battery of Figures 3a to 3d are omitted herein for brevity. However, unlike the above-mentioned configurations and conventional configurations, in the redox batteries 400A-1, 400A-2, 400B-400D illustrated in Figures 4a to 4d, in addition to providing electrical connection between the multiple redox battery cells, one or both of the positive bus bar and the negative bus bar are also configured as fastening means for mechanically fastening the stacked redox battery cells 300A-1, 300A-2, ..., 300A-n in the stacking direction.

[0055] The inventors have determined that when the positive and negative bus bars provide a compressive force greater than about 1,000 N, 5,000 N, 10,000 N, 15,000 N, 20,000 N, or within a range defined by any of these values, the bus bars can provide adequate clamping compression pressure to effectively secure the stack together. In such a configuration, individual fasteners such as fasteners 328 described above with respect to Figures 3c and 3d may not be necessary and therefore may be omitted for compact bundling of the redox battery cells.

[0056] The bus bars may be disposed on any of the faces of the redox battery cell stack. FIG. 4a shows side and top views of redox battery cells 400A-1 and 400A-2 having different bus bar configurations. Referring to the top configuration illustrated in FIG. 4a, the redox battery cell 400A-1 includes a positive bus bar 408 and a negative bus bar 412 disposed on opposite faces of the stack. Referring to the bottom configuration illustrated in FIG. 4a, the redox battery cell 400A-2 includes a pair of positive bus bars 408A, 408B with one polarity disposed on adjacent faces sharing an edge, while the other polarity is disposed on adjacent faces sharing an opposite edge. In addition to serving as electrical connections between the redox battery cells and / or batteries, the bus bars according to various embodiments can simultaneously function as fastening means to provide a fastening or compressive force to the redox battery cell stack, as described herein. In the configuration illustrated in Figure 4a, the clamping or compressive force may be provided through a number of contact points 410 where bus bars 408A, 408B are fixedly or removably attached to a number of redox battery cells. The bus bars 408A, 408B may be configured such that they apply a compressive force across the stack in the stacking direction. The compressive force may be provided by a number of other structures as appropriate, as described below.

[0057] Figures 4b-4d are plan views of redox battery cells 400B-400D having bus bars that provide both electrical and mechanical connections to connect multiple redox battery cells together according to another embodiment. In the configuration illustrated in Figures 4b-4d, the bus bars act as fastening means to compress the stack into fastening strips that form loops around the stacked redox battery cells along the stacking direction. The loops are formed around opposing surfaces and outer peripheral surfaces of the first and second conductive end plates.

[0058] In the configuration shown in FIG. 4b illustrating a redox battery 400B, the positive bus bar 416 and the negative bus bar 420 form loops around the redox battery cell stack along the length of the stack. The planes formed by the loops of the positive bus bar 416 and the negative bus bar 420 intersect each other such that the positive bus bar 416 and the negative bus bar 420, respectively, intersect across the outer peripheral surface of the first and / or second conductive end plates 324. Because the bus bars also serve to electrically couple the cells, the positive bus bar 416 and the negative bus bar 420 may be electrically insulated from each other as shown, for example, by an insulator 424 interposed between the positive bus bar 416 and the negative bus bar 420 at the junction therebetween.

[0059] In the configuration shown in FIG. 4c illustrating a redox battery 400C, the positive bus bar 428 and the negative bus bar 432 form loops around the redox battery cell stack along the length of the stack. However, unlike the arrangement illustrated in FIG. 4b, the positive bus bar 428 and the negative bus bar 432 do not cross each other across the outer peripheral surfaces of the first and second conductive end plates 324. Instead, each of the loops is formed around the adjacent side surfaces and adjacent edges thereof as well as the corners of the outer peripheral surfaces of the first and second conductive end plates 324. Preferably, because the positive bus bar 428 and the negative bus bar 432 do not cross each other, insulation as shown in FIG. 4b may not be necessary and may therefore be omitted.

[0060] 4d, illustrating a redox battery 400D, the positive bus bar 408 and the negative bus bar 412 do not need to form loops. Instead, the positive bus bar 408 and the negative bus bar 412 are disposed on opposite sides of the stack in a manner similar to the redox battery 400A described above. Also, in the illustrated configuration, to provide additional fastening strength, individual fastening strips 436 can be looped around the cell stack to provide a compressive force.

[0061] Redox cell having electrically conductive end plates and electrically bonded bus bars In existing stacking configurations of redox batteries, end plates provide a structural function, for example, to provide compressive pressure to a redox battery cell stack. For example, as described above with respect to Figs. 3a-3d, a conductive end plate can be used to secure fasteners to the conductive end plate to provide compressive pressure to the stack. However, embodiments are not limited thereto, and the inventors have found that the conductive end plate can be configured to provide an additional electrical function. The conductive end plate can be formed of an electrically conductive material and can be electrically coupled to a bus bar as part of an overall electrical interconnect network connecting the redox battery cells and / or batteries. For example, the conductive end plate can serve as a positive or negative contact pad, which in turn can serve as a connection point for stacking multiple stacks of redox battery cells. Accordingly, various embodiments of conductive end plates that can be electrically coupled to a bus bar as part of an interconnect network for the redox battery cells will now be described.

[0062] 5a-5f are schematic diagrams of redox batteries 500A-500F having electrically conductive end plates disposed at opposite ends of a redox battery cell stack and electrically coupled to bus bars, according to an embodiment. In each of FIGS. 5a-5f, the redox battery 500A-500F includes a plurality of redox battery cells 300A-1, 300A-2, ..., 300A-n stacked in a stacking direction in a manner similar to that described above with respect to FIGS. 4a-4d, each of the redox battery cells including a first half-cell 304A in contact with the positive current collector 108A, a second half-cell 304B in contact with the negative current collector 108B, and an ion exchange membrane 112 separating the first and second half-cells in a manner similar to that described above with respect to FIGS. 3a-3d, the details of which are omitted herein for brevity. The redox batteries 500A-500F also include a positive conductive bus bar 512 extending in the stacking direction to electrically connect the positive current collectors 108A of the redox battery cells 300A-1, 300A-2, ..., 300A-n, for example, in parallel, and a negative conductive bus bar 516 extending in the stacking direction to electrically connect the negative current collectors 108B of the redox battery cells 300A-1, 300A-2, ..., 300A-n, for example, in parallel. In addition to providing electrical connection in a manner similar to that described above with reference to Figures 4a-4d, the bus bar can also serve as a fastening means for mechanically fastening the redox battery cells stacked in the stacking direction. However, unlike the above-mentioned and conventional configurations, the exemplary redox battery 500A-500F illustrated in Figures 5a-5f further includes a first conductive end plate 504, e.g., a positive conductive end plate, and a second conductive end plate 508, e.g., a negative conductive end plate, disposed at opposite ends of the stacked redox battery cells 300A-1, 300A-2, ..., 300A-n, where the first conductive end plate 504 is electrically conductive and is coupled to a positive conductive bus bar 512, and the second conductive end plate 508 is electrically conductive and is coupled to a negative conductive bus bar 516. The exemplary bus bars are rigidly coupled to the conductive end plates 504, 508 at both ends to provide, among other things, compressive forces and pressure to the cell stack in the stacking direction.

[0063] In a manner similar to the configurations described above with respect to Figures 4a-4d, the positive busbar 512 and the negative busbar 516 can provide fastening means, such as fastening strips. Similarly, the busbars 512, 516 can provide a compressive force in the stacking direction of the redox battery cells of greater than about 1,000N, 5,000N, 10,000N, 15,000N, 20,000N, or within a range defined by any of these values, to provide an adequate fastening compression pressure to effectively secure the stack together and prevent electrolyte leakage. In such a configuration, the busbars 512, 516 can provide sufficient compression pressure that separate fastener ports, as described above with respect to Figure 3c, may not be necessary and can therefore be omitted.

[0064] The bus bars may be disposed on any of the faces of the redox battery cell stack. For example, referring to FIG. 5a illustrating a redox battery 500A, a positive bus bar 512 and a negative bus bar 516 are disposed on opposite faces of the redox battery cell stack. In the illustrated embodiment, a top conductive end plate is electrically coupled to the negative bus bar 516 and serves as a negative conductive end plate 508, and a bottom conductive end plate is electrically coupled to the positive bus bar 512 and serves as a positive conductive end plate 504. Each bus bar is directly coupled to a conductive end plate of the same polarity, while being physically coupled to, but electrically insulated from, a conductive end plate of the opposite polarity. Thus, the positive bus bar 512 is mechanically fixed to both the first (lower) and second (upper) conductive end plates 504, 508, and electrically connected only to the first (lower) conductive end plate that serves as the positive conductive end plate 504, and serves as a fastening means for mechanically fastening the redox battery cells 300A-1, 300A-2, ..., 300A-n stacked in the stacking direction. Similarly, the negative conductive bus bar 516 is mechanically fixed to both the first (lower) and second (upper) conductive end plates 504, 508, and electrically connected only to the second (upper) conductive end plate that serves as the negative conductive end plate 508, and serves as a fastening means for mechanically fastening the redox battery cells 300A-1, 300A-2, ..., 300A-n stacked in the stacking direction.

[0065] To serve as an effective fastening means, the conductive busbars 512, 516 may be fixedly coupled or attached to the conductive end plates using any suitable means. It will be appreciated that one of the ends of the busbars having the same polarity as the conductive end plate may be attached using any suitable technique, such as welding, to provide a high strength connection. However, the other end of the busbars having the opposite polarity to the conductive end plate may not be welded to maintain electrical isolation. FIG. 5b illustrates various exemplary implementations of coupling or fastening means 505A-505G that may provide a high strength connection between the conductive end plates 504, 508 of opposite polarity and the busbars 512, 516. The high strength mechanical fastening means may illustratively include, without limitation, one or more of an L-shaped brace 524, a screw, a pin 532, a bolt 536, an adhesive or weld 540, a jagged or sawtooth anchor 544, or the like. Coupling means are used in conjunction with insulators 520 to maintain electrical isolation between the opposing polarity conductive end plates 504, 508 and the bus bars 512, 516. As illustrated, mechanical coupling means may secure the bus bar 516 to one or both of the side and bottom surfaces of the conductive end plate 504.

[0066] 5c, an example redox battery 500C having electrically conductive end plates 504, 508 coupled to bus bars 512, 216 is similar to that described above for FIGURE 5a, with the positive and negative conductive bus bars 512, 516 disposed on opposite sides of the stack of redox battery cells 300A-1, 300A-2, ..., 300A-n. However, unlike the configuration of FIGURE 5a, the example redox battery 500C further includes an insulating layer 548A, 548B between each conductive end plate 504, 508 and the nearest cell in the stack of redox battery cells 300A-1, 300A-2, ..., 300A-n. Insulating layers 548A, 548B may be inserted to provide additional electrical insulation between cell stacks 300A-1, 300A-2, ..., 300A-n and conductive end plates 504, 508 for improved safety during operation, and may further provide mechanical functions similar to those of the conductive end plates, including providing additional connection points for bus bars 512, 516 to assist in compressive or pressure forces maintained on the cell stacks.

[0067] 5d, an example redox battery 500D is configured similarly to that described above with respect to FIG. 5c, except that in the redox battery 500D, a pair of negative conductive bus bars 516A, 516B are disposed on one pair of opposing sides of the stack of redox battery cells 300A-1, 300A-2, ..., 300A-n, and a pair of positive conductive bus bars 512A, 512B are disposed on the other pair of opposing sides of the stack of redox battery cells 300A-1, 300A-2, ..., 300A-n.

[0068] As discussed above with respect to Figures 4a-4d and 5a-5d, the bus bars electrically coupled to the conductive end plates can be configured to provide suitable compressive force and pressure across the redox battery cell stack, for example, to prevent electrolyte leakage and / or hold the cells together without separation. This allows for the elimination of additional independent fastening means that do not provide electrical coupling in some configurations. However, in some other configurations, additional supporting fastening means can be provided. Figures 5e and 5f illustrate redox batteries 500E, 500F in which the electrically conductive end plates 504, 508 are rigidly coupled to the bus bars in a manner similar to that discussed above with respect to Figures 5c and 5d to provide, among other things, compressive force and pressure to the stack of cells 300A-1, 300A-2, ..., 300A-n in the stacking direction. The example redox cells 500E, 500F also provide additional independent fastening means, such as one or more fastening tie strips or bands 552, that are wrapped around the stack in a stacking direction to provide additional compressive force and pressure to the stack of cells 300A-1, 300A-2, ..., 300A-n. In the configuration illustrated in FIG. 5e, the fastening tie strips 552 form loops in a plane that extends in the stacking or extension direction of the bus bars 512, 516. However, embodiments are not limited thereto, and in other configurations, the fastening tie strips 552 can form loops in different planes, such as a plane that intersects with or is perpendicular to the plane of the example loop formed by the fastening tie strips 552. In the configuration illustrated in FIG. 5f, the fastening tie strips 552 form loops in a plane that is parallel to the extension direction of the bus bars 512A, 512B. As discussed above with respect to the fastener ports of Figures 3c, 3d, and 4d, the fastener tie strips 552 may function substantially to provide sufficient mechanical force and pressure to hold the stack together without functioning to provide an electrical connection between the redox battery cells or batteries, thereby allowing the fastener strips 552 to be formed of an electrically insulating material, such as a polymeric material.

[0069] As described above, the electrically conductive end plates 504, 508 can, among other things, enable the multiple redox battery cells to be bound to the bus bars to provide electrical and mechanical functions. Also, according to various embodiments, the conductive end plates can be configured such that they further enable mechanical and electrical binding of the multiple redox batteries. FIGS. 5g-5i are schematic diagrams of multiple redox batteries each including a redox battery cell stack between a pair of conductive end plates, the redox batteries themselves being stacked and electrically coupled to each other via their respective conductive end plates. Each of the redox batteries includes redox battery cells 300A-1, 300A-2, ..., 300A-n between conductive end plates 556, 560. The individual redox cells of the redox battery can be suitably arranged in any configuration as described above, and a detailed description of these will be omitted for the sake of brevity.

[0070] In the exemplary configuration of stacked redox batteries 500M shown in FIG. 5g, the conductive end plates 556, 560 of nearest adjacent batteries with opposite polarity are coupled together to connect the batteries 500G-1, 500G-2, ..., 500G-n in series. The coupled conductive end plates of the conductive end plates 556, 560 may have any suitable shape to allow for a mechanical coupling therebetween. The mechanical coupling may be such that the coupled conductive end plates 556, 560 are restricted from moving in at least one direction, e.g., in one or both lateral directions perpendicular to the stacking direction of the redox battery cells. For example, with reference to exemplary redox cell 500G, the pair of positive and negative conductive end plates 556, 560 may be coupled via protrusions 564 and recesses 568, which are shaped and sized to provide fixed vertical positioning of vertically adjacent redox cells and / or a snug fit between the protrusions 564 and the recesses 568 to prevent lateral slippage.

[0071] In the exemplary configuration of stacked redox cells 500H shown in FIG. 5h, multiple vertical stacks or columns 510M-1, 510M-2, ..., 510M-m of redox cells are arranged laterally adjacent to each other. Each of the vertical stacks 510M-1, 510M-2, ..., 510M-m of redox cells includes multiple redox cells 500G-1, 500G-2, ..., 500G-n, each of which in turn includes a stack of redox battery cells 300A-1, 300A-2, ..., 300A-n, as described above with respect to FIG. 5g. In the exemplary example, each of the columns 510M-1, 510M-2, ..., 510M-m of redox cells has the same number of redox cells, such that cells of the same vertical height are arranged to form horizontal rows 510L-1, 510L-2, ..., 510L-l of redox cells. When so arranged, the vertical stacks 510M-1, 510M-2, ..., 510M-m of redox cells and the horizontal rows 510L-1, 510L-2, ..., 510L-l of redox cells form an (m x n) array of redox cells. The top conductive end plates 556 of each cell of the cells having a first polarity can be electrically coupled to each other via a top conductive parallel tie plate 572 of the first polarity. The bottom conductive end plates 560 of the cells having a second polarity can be electrically coupled to each other via a bottom conductive parallel tie plate 576 of the second polarity. A pair of side panels 580, which may be electrically insulating, are disposed and connected to the top and bottom conductive parallel connection plates 572, 576 and the ends of the vertical stacks 510M-1, 510M-2, ..., 510M-m to form side panels of a rack structure for holding the (m x n) array of redox cells in place. In this manner, the (m x n) array of redox cells may be bundled into a single rack unit as illustrated. In the example illustrated in Fig. 5h, the redox cells 500G-1, 500G-2, ..., 500G-n in each vertical stack 510M-1, 510M-2, ..., 510M-m are electrically connected in series, but adjacent vertical stacks are electrically connected in parallel by the top and bottom conductive parallel connection plates 572, 576.

[0072] As explained, the top and bottom conductive end plates 556, 560 of the redox cell provide electrical and structural functions such that they enable efficient formation of an array of redox cells, such as stacked redox cell 500H, described above with respect to FIG. 5h. It is recognized that other physical and electrical arrangements are possible for forming an array of redox cells. As one other example, FIG. 5i shows one such other arrangement of stacked redox cells 500I. The stacked redox cells 500I are spatially arranged as an (m×n) array of redox cells, including vertical stacks or columns 510M-1, 510M-2, ..., 510M-m of redox cells, and horizontal rows 510L-1, 510L-2, ..., 510L-l of redox cells, in a manner spatially similar to that described above with respect to FIG. 5h. However, unlike the stacked redox cells 500H (FIG. 5h), in the stacked redox cells 500I, the vertical stacks are not electrically connected in series. In the stacked redox cells 500I, each of the redox cells in the vertically adjacent rows 510L-1, 510L-2, ..., 510L-l are electrically connected in parallel. This is achieved by flipping the redox cells in each of the other rows of every redox cell such that the vertically most adjacent redox cells having conductive end plates with the same polarity that directly face each other among the redox cells are electrically connected to each other by their respective parallel connection plates. By way of example, in the stacked redox cells 500I, the top conductive end plates 556 of the cells in the first row 510L-1 with a first polarity are electrically connected to each other via a first conductive parallel connection plate 572A of a first polarity. Additionally, the top conductive end plates 556 of the cells in the second row 510L-2 and the third row 510L-3 with the first polarity are electrically connected to each other via a second conductive parallel connection plate 572B of the first polarity. In a similar manner, the bottom conductive end plates 560 of the cells in the first row 510L-1 and the second row 510L-2 with the second polarity are electrically connected to each other via a first conductive parallel connection plate 576A of the second polarity.Also, the bottom conductive end plates 560 of the third row 510L-3 having the second polarity are electrically connected to each other via the second conductive parallel connection plate 576B of the second polarity. When configured in this manner, every redox cell of the stacked redox cell 500I is electrically connected in parallel. Although two specific exemplary configurations of an (m×n) array of redox cells having different electrical configurations are demonstrated, it will be recognized that one of ordinary skill in the art can make appropriate modifications to form various other combinations of redox cells that are physically stacked to form an array having cells electrically connected by any suitable combination of series and / or parallel connections.

[0073] As mentioned above, the inventors have found that according to various embodiments described above with respect to Figs. 5a-5i, conductive end plates can be configured to act as electrical connectors formed of electrically conductive material that are coupled to bus bars as part of an overall electrical interconnection network of one or more redox batteries. In the exemplary configurations described above with respect to Figs. 5a-5i, conductive end plates of opposite polarity are disposed on opposite ends of a redox battery cell stack. However, the embodiments are not so limited. In the configurations illustrated in Figs. 5a-5i, the bus bars have one of a polarity such that one end of the bus bar is electrically and physically coupled to one conductive end plate of one polarity, while the other end of the bus bar is physically coupled, but not electrically coupled, to the other conductive end plate of the opposite polarity. For example, a physical-only (i.e., non-electrical) coupling can be achieved by forming an electrical insulator between the coupling points (see, e.g., Figs. 5a, 5b). In some designs, it is preferable to omit the physical dedicated connections between the conductive end plates and the bus bars, by omitting electrical insulation between the conductive end plates and the bus bars of opposite polarity, to allow easier bundling and improve safety and reliability. Next, various embodiments of conductive end plates that can be electrically bonded to the bus bars as part of a connection pathway network for a redox battery cell stack are described, where conductive end plates of the same polarity are formed on opposite sides of the redox battery cell stack. Among other advantages, such configurations can allow for the omission of at least some of the physical dedicated connections between the bus bars and the conductive end plates for simplified bundling of the redox battery cell stack.

[0074] Figures 6a-6i are schematic diagrams of redox batteries 600A-600I with electrically conductive end plates coupled to bus bars according to other embodiments. In each of Figures 6a-6i, in a manner similar to that described above with respect to Figures 5a-5f, each of the redox batteries 600A-600I includes a plurality of redox battery cells 300A-1, 300A-2, ..., 300A-n stacked in a stacking direction, the detailed description of which is omitted herein for the sake of brevity. The redox battery 600A-600I also includes a positive conductive bus bar extending in the stacking direction to electrically connect the positive current collectors 108A of the redox battery cells 300A-1, 300A-2, ..., 300A-n in parallel, and a negative conductive bus bar extending in the stacking direction to electrically connect the negative current collectors 108B of the redox battery cells 300A-1, 300A-2, ..., 300A-n in parallel. In a manner similar to that described above with respect to Figures 5a-5f, the redox battery 600A-600I illustrated in Figures 6a-6i further includes conductive end plates that provide mechanical functions, such as mechanical coupling mechanisms, as well as electrical functions to enable electrical stacking of multiple redox battery cell stacks. However, unlike the redox battery illustrated in Figures 5a-5f, the redox battery 600A-600I illustrated in Figures 6a-6i further includes a conductive end plate having the same polarity formed on one or both ends of each stack of the battery cell stack, or a conductive end plate having an opposite polarity formed on the same end of each stack of the battery cell stack. The exemplary redox battery 600A-600I includes a first conductive end plate and a second conductive end plate, both of which may have the same polarity, e.g., positive polarity, disposed at opposite ends of the stacked redox battery cells, and the first conductive end plate and the second conductive end plate are electrically conductive and connected to a positive conductive bus bar. The redox batteries 600A-600I further include a third conductive end plate and a fourth conductive end plate, both of which may have the same polarity, e.g., negative polarity, disposed at opposite ends of the stacked redox battery cells, the third conductive end plate and the fourth conductive end plate being electrically conductive and coupled to the negative conductive bus bar.In other words, a conductive end plate of opposite polarity is formed at the transmitting end of the stacked redox battery cells, or in the exemplary embodiment, the conductive end plate is split into at least two pieces of opposite polarity, thus providing, among other advantages, electrical connections of opposite polarity to the same top or bottom side of the redox battery.

[0075] Referring to the redox battery 600A shown in FIG. 6a, the first conductive end plate 604A and the third conductive end plate 608A are adjacently disposed on the same end, e.g., the top end, of the stacked redox battery cells 300A-1, 300A-2, ..., 300A-n. Because the first conductive end plate and the third conductive end plate have opposite polarities, the first conductive end plate 604A and the third conductive end plate 608A may be electrically insulated from each other by a gap or an insulating layer (not shown) between them. Similarly, the second conductive end plate 604B and the fourth conductive end plate 608B are electrically insulated from each other and adjacently disposed on the same end, e.g., the bottom end, of the stacked redox battery cells 300A-1, 300A-2, ..., 300A-n. Because the second and fourth conductive end plates have opposite polarities, the second and fourth conductive end plates 604B and 608B may also be electrically isolated from each other by a gap or insulating layer (not shown) between them. The first and third conductive end plates 604A and 608A may be selectively referred to herein as being parts or components of a split conductive end plate. Similarly, the second and fourth conductive end plates 604B and 608B may be selectively referred to herein as being parts or components of a split conductive end plate.

[0076] 6a, the positive conductive bus bars 612A, 612B are mechanically fixed and electrically connected to the first conductive end plate 604A and the second conductive end plate 604B, respectively, so as to function not only as an electrical connector for connecting the positive current collectors but also as a fastening means for mechanically fastening the stacked redox battery cells 300A-1, 300A-2, ..., 300A-n in the stacking direction. Similarly, the negative conductive bus bars 616A, 616B are mechanically fixed and electrically connected to the third conductive end plate 608A and the fourth conductive end plate 608B, respectively, so as to function not only as an electrical connector for connecting the negative current collectors but also as a fastening means for mechanically fastening the stacked redox battery cells 300A-1, 300A-2, ..., 300A-n in the stacking direction.

[0077] In a manner similar to the configurations described above with respect to Figures 4a-4d, the positive conductive bus bars 612A, 612B and the negative bus bars 616A, 616B can be provided with fastening means including fastening strips. For example, the bus bars can provide a compressive force of greater than about 1,000N, 5,000N, 10,000N, 15,000N, 20,000N, or within a range defined by any of these values, to provide adequate fastening compression pressure to effectively secure the stack together and substantially prevent electrolyte leakage. In some configurations, individual fastener ports as described above with respect to Figure 3c may not be necessary and thus may be omitted.

[0078] The bus bars may be disposed on any of the faces of the stack. Referring to FIG. 6a, bus bars of the same polarity may be disposed on opposite faces of the stack. In the illustrated embodiment, a first (top) conductive end plate 604A and a second (bottom) conductive end plate 604B of positive polarity are electrically coupled to positive bus bars 612A, 612B on opposite surfaces of the cell stack. Similarly, a third (top) conductive end plate 608A and a fourth (bottom) conductive end plate 608B of negative polarity are electrically coupled to negative bus bars 616A, 616B on opposite surfaces of the cell stack. Unlike the arrangement illustrated with respect to FIGS. 5a-5f, each bus bar is physically and electrically directly coupled to a conductive end plate of the same polarity at both ends, thereby eliminating the need for electrical insulation between the conductive end plates of the opposite polarity of the bus bars. Thus, each bus bar 612A, 612B, 616A, 616B serves as a fastening means for mechanically fastening the stacked redox battery cells 300A-1, 300A-2, ..., 300A-n in the stacking direction, and serves as an electrical connector coupled to a conductive end plate on either side of the stack with the same polarity as the bus bar. To serve as an effective fastening port, the conductive bus bar can be coupled to the conductive end plate using any suitable means to provide a high strength connection, such as welding, L-shaped braces, screws, pins, bolts, adhesives, sawtooth anchors, etc., in a manner similar to that described above in FIG. 5b. As illustrated in FIG. 5b, insulators can be omitted to maintain electrical isolation between the conductive end plates with opposite polarities and the bus bar, although high strength mechanical coupling means such as L-shaped braces, screws, pins, bolts, adhesives, welding, sawtooth anchors, etc. can be used.

[0079] 6b, an example redox battery 600B may include conductive end plates of the same polarity formed on one or both ends of each of the redox battery cell stacks, conductive end plates of opposite polarity formed on the same end of each of the redox battery cell stacks, or conductive end plates each divided into at least two pieces of opposite polarity, in a manner similar to that shown in FIG 6a. Because the conductive end plates are of opposite polarity, the first conductive end plate 604A and the third conductive end plate 608A may be electrically insulated from each other by an insulating layer 620A disposed therebetween, and the second conductive end plate 604B and the fourth conductive end plate 608B may be electrically insulated from each other by an insulating layer 620B disposed therebetween. Also, unlike the redox battery described above with respect to FIG. 6a, and in a manner similar to that described above with respect to FIG. 5c, the exemplary redox battery 600B also includes an insulating layer 548A, 548B disposed vertically between each conductive end plate and each nearest redox battery cell of the redox battery cell stack. The insulating layers 548A, 548B can be inserted to provide additional electrical insulation between the cell stack and the conductive end plate for improved stability during operation. The insulating layers 548A, 548B can also provide mechanical functions similar to those of the conductive end plates, including providing additional connection points for bus bars to assist in compressive forces or pressures maintained on the redox battery cell stack.

[0080] Referring to FIG. 6c, an exemplary redox battery 600C includes conductive end plates with the same polarity formed on one or both ends of each of the redox battery cell stacks, conductive end plates with opposite polarity formed on the same end of each of the redox battery cell stacks, or conductive end plates split laterally into at least both portions with opposite polarity, in a manner similar to that shown in FIG. 6a. However, unlike FIG. 6a, the conductive end plates with the same polarity are connected by more than one bus bar per side of the redox battery cell stack. In the exemplary configuration, the redox battery includes positive bus bars 624A, 624B and negative bus bars 628A, 628B, respectively, disposed on the side surfaces of the cell stacks, in a manner similar to the redox battery described above with respect to FIGS. 6a and 6b. Additionally, the redox battery 600C further includes positive bus bars 622A, 622B and negative bus bars 626A, 626B, respectively, disposed on the edges of the cell stacks.

[0081] 6d-6g, the exemplary redox battery 600D-600G includes conductive end plates with the same polarity formed on one or both ends of each of the redox battery cell stacks, conductive end plates with opposite polarity formed on the same end of each of the redox battery cell stacks, or conductive end plates divided into at least two parts with opposite polarity, in a manner similar to that shown in FIG 6a. However, unlike FIG 6a, and in a manner similar to that described above with respect to FIG 5e and FIG 5f, the exemplary redox battery includes additional support fastening means, such as one or more fastening tie strips or bands wrapped around the stack in the stacking direction to provide additional compressive force and pressure to the stack of cells 300A-1, 300A-2, ..., 300A-n. In the exemplary configuration, without limitation, the fastening tie strips form loops in a plane parallel to the extension direction of the bus bars. In the configuration illustrated in FIG. 6, the redox cell 600D includes a fastening tie strip 552 that forms a loop in a plane parallel to the extension of the bus bars 612A, 612B, 616A, 616B.

[0082] In the configuration illustrated in Figure 6e, the redox battery 600E also includes insulating layers 548A, 548B disposed vertically between each conductive end plate and the nearest cell of the stack, in a manner similar to that described above for Figure 6b, as well as insulating layers 620A, 620B disposed laterally between the end plates of opposite polarity. Fastening tie strips 552 can be looped around the insulating layers 548A, 548B as well as the cell 300A-1, 300A-2, ..., 300A-n stack.

[0083] In the configurations illustrated in Figures 6f and 6g, further supporting fastening means, e.g. strips or bands, are formed around the entire stack of redox cells including the conductive end plates. The strips or bands can form loops in any direction. In the configuration illustrated in Figure 6f, the redox cell 600F includes conductive end plates with different polarities and a fastening strip 552 that forms a loop around the redox cell stack. In the configuration illustrated in Figure 6g, the redox cell 600G includes conductive end plates with the same polarity and a fastening strip 552 that forms a loop around the redox cell stack.

[0084] Other structural separation arrangements between conductive end plates with opposite polarities formed on the same end of the redox battery cell stack are possible. Referring to FIG. 6h, an example redox battery 600H includes a conductive end plate that is laterally divided into at least two parts with opposite polarities, respectively, according to another embodiment. The example redox battery 600H includes a top conductive end plate that is divided into parts 632A, 636A with opposite polarities, and a bottom conductive end plate that is divided into parts 632B, 636B with opposite polarities. The parts 632A, 632B have the same polarity, e.g., positive polarity, and the parts 636A, 636B have the same polarity, e.g., negative polarity. The conductive end plates of the same polarity are connected by more than one bus bar of the same polarity, including bus bars 612A-612D, which may have, for example, a positive polarity, and bus bars 616A-616D, which may have, for example, a negative polarity, extending in the stacking direction on the surface of the redox battery stack side. Unlike the conductive end plates of opposite polarities formed on the same end of the redox battery cell stack described in Figs. 6a-6g, where the conductive end plates on the same end are split along the length direction, in the embodiment illustrated in Fig. 6h, at least one conductive end plate is split along a direction different from each other in the length direction, for example, diagonally or diagonally, to give two examples. In further contrast to the arrangement illustrated in Figs. 6a-6g, at least one conductive end plate may be split into three or more parts. For example, each of the components 632A, 636A, 632B, 636B are illustrated as being divided into two diagonal end portions connected by a diagonally extending bridge portion.

[0085] Referring to FIG. 6i, an example redox battery 600I includes a conductive end plate that is vertically split into at least two parts with opposite polarity, according to yet another embodiment. The example redox battery 600I includes a top conductive end plate that is vertically split into parts 640A, 644A with opposite polarity, and a bottom conductive end plate that is vertically split into parts 640B, 644B with opposite polarity. In the arrangements illustrated in FIGS. 6a-6h, each conductive end plate is laterally split into at least two parts along the lateral direction. In contrast, in the embodiment illustrated in FIG. 6i, at least one conductive end plate can be split into two or more parts along the vertical direction, e.g., in the stacking direction, such that the two or more parts have a stacked configuration. Further to the arrangement illustrated in Figures 6a-6h, the vertically stacked components 640A, 644A and 640B, 644B of conductive end plates are separated by intervening insulators 648A, 648B therebetween.

[0086] For example, as described above with respect to Figs. 5g-5h, electrically conductive end plates can, among other things, allow multiple stacks to be stacked in an efficient manner with electrical binding. Similarly, efficient stacking arrangements of redox batteries are possible with conductive end plates of opposite polarity formed on the same end of each of the redox battery cell stacks. Figs. 6j-6n are schematic diagrams of multiple redox batteries each including a stack of redox battery cells 300A-1, 300A-2, ..., 300A-n between conductive end plates, according to an embodiment, the redox batteries themselves being stacked and electrically connected via conductive end plates. Exemplary arrangements 600J-600N include conductive end plates that are split into pieces, e.g., pieces with opposite polarity as described above with respect to Figs. 6a-6i, to allow for additional binding flexibility.

[0087] In the exemplary configuration of stacked redox batteries 600J shown in FIG. 6j, each conductive end plate is divided into a conductive portion and an insulating portion. For example, in the individual redox battery 600J-1 shown in FIG. 6j, the top conductive end plate is divided into a conductive portion 652A and an insulating portion 660A, and the bottom conductive end plate is divided into a conductive portion 656B and an insulating portion 660B. The conductive portions 652A, 656B with positive and negative polarities, respectively, are electrically coupled to the current collectors 612A, 616A of the redox battery cells 300A-1, 300A-2, ..., 300A-n with corresponding polarities. The conductive end plate portions 652A, 656B of the nearest adjacent batteries with opposite polarities are physically and electrically coupled to each other to connect the batteries 600J-1, 600J-2, ..., 600J-n in series. The insulated conductive end plate portions 660A, 660B of the nearest adjacent cells do not affect the electrical connectivity between the adjacent cells and are physically coupled to one another. The coupled conductive end plates of the conductive end plates can have any suitable shape to allow for a mechanical coupling therebetween, e.g., a protrusion-recess coupling, in a manner similar to that described above with respect to FIG. 5g. The mechanical coupling is performed such that the coupled conductive end plate portions 652A, 656B of vertically adjacent ones of the cells are restricted from moving in at least one direction, e.g., in one or both lateral directions perpendicular to the stacking direction of the redox battery cells.

[0088] In an exemplary configuration of stacked redox batteries 600K shown in FIG. 6k, multiple rows 610K-1, ..., 610K-n of redox batteries may be arranged to form a rack including an array of redox battery cells in a manner similar to that described above with respect to FIG. 5i and / or FIG. 5j. For example, in the redox battery 600K shown in FIG. 6k, each individual redox battery 610K includes a top conductive end plate divided into conductive end plate portions 652A, 656A with opposite polarity and a bottom conductive end plate divided into conductive portions 652B, 656B with opposite polarity. The portions 652A, 652B with the same polarity, e.g., positive polarity, are electrically coupled to the positive current collectors of the redox battery cells 300A-1, 300A-2, ..., 300A-n and to each other via a positive bus bar 612A. Similarly, the sections 656A, 656B having the same polarity, e.g., negative polarity, are electrically coupled to each other and to the negative current collectors of the redox battery cells 300A-1, 300A-2, ..., 300A-n via the negative bus bar 616A. Unlike the arrangement shown in Figures 5i and / or 5j, the cells of the top row 610K-1 of batteries are laterally offset relative to the cells of the bottom row 610K-n of batteries, such that the segmented bottom conductive end plates 652B, 656B of the cells of the top row 610K-1 of batteries are electrically coupled to the segmented top conductive end plates 652A, 656A of the cells of the bottom row 610K-n of batteries having the opposite polarity. In this manner, an array of redox batteries may be compactly packed into a single rack unit in a manner similar to that described above with respect to Figures 5i and / or 5h.

[0089] For illustrative purposes only, in FIG. 6k, the redox cells are electrically connected in series. However, it is recognized that other arrangements are possible. By way of example, FIG. 6l shows one such other arrangement of stacked redox cells 600L. The redox cells of the stacked redox cells 600L are arranged as an (m×n) array in a manner similar to the array of cells described above with respect to FIG. 5h and FIG. 5i. Each individual redox cell 600A includes a top conductive end plate that is divided into conductive end plate portions 652A, 656A with opposite polarities, and a bottom conductive end plate that is divided into conductive portions 652B, 656B with opposite polarities. The portions 652A, 652B with the same polarity, e.g., positive polarity, are electrically connected to the positive current collectors of the redox battery cells 300A-1, 300A-2, ..., 300A-n and to each other via a positive bus bar 612A. Similarly, the sections 656A, 656B having the same polarity, e.g., negative polarity, are electrically connected to each other and to the negative current collectors of the redox battery cells 300A-1, 300A-2, ..., 300A-n via the negative bus bar 616A. In the stacked redox battery 600L, the redox cells in each row 610L-1, 610L-2, ..., 610L-l are electrically connected in series via adjacent sections 652A, 652B and / or adjacent sections 656A, 656B of laterally adjacent cells of the battery, while the redox cells in each column 610M-1, 610M-2, ..., 610M-m are electrically connected in parallel via adjacent sections 652A, 656A and / or adjacent sections 652B, 656B of vertically adjacent cells of the battery. Although two specific exemplary configurations of an (m×n) array of redox cells having different electrical configurations are demonstrated, it will be recognized that one of ordinary skill in the art can make appropriate modifications to form various other combinations of redox cells that can be physically stacked to form arrays having electrically connected cells, via any suitable combination of series and parallel connections.

[0090] In a manner similar to that described above with respect to Figs. 5h and 5i, in the illustrated array 600M in Fig. 6m, each redox cell in the rows 610L-1, ..., 610L-n can be electrically connected in parallel to each other via the top and bottom conductive parallel connection plates 664. The redox cells of the stacked redox cells 600M are arranged in an (m x n) array in a manner similar to that of the array of cells described above with respect to Fig. 6l. Each individual redox cell 610A is arranged in a manner similar to that described above with respect to Fig. 6l, and a detailed description of these is omitted herein for brevity. The redox cells in each row 610L-1, 610L-2, ..., 610L-l are electrically connected in parallel. The top conductive end plates 652A, 652B of each cell of the cells having a first polarity can be electrically connected to each other via the top conductive parallel connection plate 664 of the first polarity. The bottom conductive end plates 656A, 656B of the cells having a second polarity may be electrically coupled to one another via a bottom conductive parallel tie plate 576 of the second polarity. A pair of side panels 580, which may be electrically insulating, are disposed on and coupled to opposite ends of the top and bottom conductive parallel tie plates 664 to form the side panels of a rack structure for holding in place an (m x n) array of redox cells. In this manner, an (n x m) array of redox cells may be illustratively bundled into a single rack unit in a manner similar to that described above with respect to Figures 5h and 5i.

[0091] Preferably, various bundling schemes for redox battery cell stacks as described herein allow for these compact bundling. FIG. 6n illustrates an energy storage device 600N including multiple packaged redox batteries that can be received by a user. The energy storage device 600N may include a box casing 676, a pair of positive electrodes 668A, 668B external to the casing 676 and connected to positively conductive end plate portions 652A, 652B, and a pair of negative electrodes 672A, 672B external to the casing 676 and connected to negatively conductive end plate portions 656A, 656B. Multiple energy storage devices 600N can themselves be stacked to form, for example, a stack of energy storage devices 600N connected in series.

[0092] 3D stacked redox battery As described above, according to various embodiments, multiple redox battery cells can be stacked with electrical connections between them to form a redox battery. The electrical connections formed by one or both of conductive bus bars and conductive end plates can provide additional mechanical robustness to the electrical connections. Additionally, multiple redox batteries, each having a bus bar and / or conductive end plate, can be stacked or bundled together to form, for example, a one- or two-dimensional stack of redox batteries. The redox batteries can be shaped and arranged as described herein to provide an efficient stacked arrangement of redox battery cells extending in two and three dimensions.

[0093] 7a-7c are schematic diagrams of redox battery systems 700A-C each including a plurality of redox batteries. According to some embodiments, each of the redox batteries includes a stack of redox battery cells 300A-1, 300A-2, ..., 300A-n between conductive end plates 704A, 704B, 708A, 708B, the redox batteries themselves being stacked and electrically connected via the conductive end plates. Each of the redox batteries may be configured according to any of the exemplary configurations described above. In each of the Figs. 7a-7c, each of the redox batteries 700 includes a plurality of redox battery cells 300A-1, 300A-2, ..., 300A-n stacked in a stacking direction in a manner similar to that described above with respect to Figs. 6a-6h, the details of which are not repeated herein for brevity. In particular, each of the redox batteries 700 includes a pair of conductive positive end plates 704A, 704B disposed at opposite ends of the stacked redox battery cells in the cell stacking direction (not shown) and electrically coupled to a positive conductive bus bar. Each of the redox batteries also includes a pair of conductive negative end plates 708A, 708B disposed at opposite ends of the stacked redox battery cells in the cell stacking direction and electrically coupled to a negative conductive bus bar 716. For each of the redox batteries, one of the pair of conductive positive end plates 704A, 704B and one of the pair of conductive negative end plates 708A, 708B form a pair of adjacently disposed conductive end plates of opposite polarity disposed on the same end of the redox battery cell stack according to any of the various embodiments described above with respect to Figures 6a-6l.

[0094] The redox cells according to various embodiments may be stacked in at least one other direction perpendicular to the stacking direction of the cells to form redox cells that are electrically connected to each other. According to various embodiments described herein, the size and shape of the cells may be adapted to form efficient stacking and electrical connections between the cells. For example, the conductive end plates of the exemplary embodiments may have a rectangular shape, adjacently disposed conductive end plate bonded pairs with opposite polarity may have the same dimensions, and the redox cells may be stacked vertically and / or horizontally.

[0095] 7a, an example redox battery system 700A includes multiple columns 710M-1, 710M-2, ..., 710M-m of redox batteries stacked in a lateral or horizontal direction perpendicular to the stacking direction of the redox battery cells 300A-1, 300A-2, ..., 300A-n. Each of the columns 710M-1, 710M-2, ..., 710M-m of redox batteries includes redox batteries arranged in a manner similar to the columns of the array of redox batteries 600L illustrated in FIG. 6l. By way of example, a first column 710M-1 includes multiple redox batteries, where each redox battery 700 is arranged in a manner similar to the redox battery 600A illustrated in FIG. 6l. The redox cells of the first string 710M-1 are arranged and stacked vertically in a manner similar to the string 610M-1 of the array of redox cells 600L described above with reference to FIG. 6l. The redox cells of the first string 710M-1 are stacked vertically with alternating conductive positive end plates 704A, 704B and conductive negative end plates 708A, 708B of the first string 710M-1 of redox cells. The exemplary first string 710M-1 of redox cells can be electrically connected in series. With redox cells having a suitable shape, such as a rectangular shape, adjacent cells in the first string of redox cells can be directly electrically connected by adjacent ones of the conductive positive end plates and conductive negative end plates that are in physical contact with each other. Also, preferably, the conductive end plates of the vertically stacked redox cells can provide a substantially full electrical connection between them by gravity.

[0096] 7a, in the exemplary redox battery system 700A, multiple columns 710M-1, 710M-2, ..., 710M-m of redox batteries are stacked horizontally in a lateral or horizontal direction perpendicular to the stacking direction of the cells, and different columns of redox batteries of the columns 710M-1, 710M-2, ..., 710M-m arranged at corresponding vertical heights are arranged to form multiple rows 710L-1, 710L-2, ..., 710L-l of redox batteries stacked vertically perpendicular to the stacking direction of the cells. The rows 710L-1, 710L-2, ..., 710L-l of redox cells are stacked vertically such that the conductive positive end plates 704A, 704B of a given row are arranged laterally or horizontally adjacent or linearly, and the conductive negative end plates 708A, 708B of a given row are arranged laterally or horizontally adjacent or linearly. By way of example, the redox cells of a given row of redox cells 710L-1, 710L-2, ..., 710L-1 are electrically connected in parallel. With redox cells having a suitable shape, such as a rectangular shape, adjacent redox cells of the second subset of redox cells are electrically connected directly by adjacent conductive positive end plates of the conductive positive end plates in physical contact with each other and / or by adjacent conductive positive end plates of the conductive positive end plates in physical contact with each other.

[0097] 7a, as arranged, the redox cells illustrated in the redox cell system 700A are stacked vertically in a vertical direction and horizontally in a horizontal direction, and when viewed from the stacking direction of the cells (into the page), the multiple redox cells form an array including multiple rows 710L-1, 710L-2, ..., 710L-l of redox cells extending in a horizontal direction and multiple columns 710M-1, 710M-2, ..., 710M-m of redox cells extending in a vertical direction. As arranged, the cells are arranged to form a three-dimensional array. At least some of the redox cells in one or more rows may be electrically connected in parallel and / or at least some of the redox cells in one or more columns may be electrically connected in series.

[0098] Preferably, according to various embodiments described herein, the size and shape of the cells are adapted to form an efficient stack in one or more directions to provide electrical coupling between stacked redox cells substantially by simply physically arranging the redox cells so that they are in contact with each other. Coupling in the vertical direction is further assisted by gravity. The stacked redox cells may also be removably secured to each other by suitable fastening structures such as clips, bands, and the like.

[0099] The stacking arrangement as described herein further provides the advantage that individual redox cells of the redox battery can be removed from the stack (e.g., for replacement or service), for example, by pulling out the stacking direction of the cells. FIG. 7b illustrates another arrangement of the redox battery system 700B that can provide further advantages in this regard. In the example illustrated in FIG. 7b, vertically adjacent cells of the rows 710L-1, 710L-2, ..., 710L-l of redox cells are horizontally offset by a portion of the length of the conductive end plate of the redox cell in the horizontal direction. As configured, different rows of the rows 710L-1, 710L-2, ..., 710L-l of redox cells may not have the same number of cells. A portion of the space formed by the offset portion of the row can be charged by the insulator 720 to provide structural support. The redox battery also includes removable configured openings 724A, 724B of the redox battery, which are further described below. As constructed, removal of one or more of the redox cells does not cause the array to collapse.

[0100] As mentioned above, electrical coupling between vertically adjacent redox cells can be achieved relatively easily according to the embodiment by physically placing one conductive end plate vertically on top of the other conductive end plate. However, unlike the vertical orientation where gravity helps maintain electrical coupling between vertically adjacent conductive end plates, in the horizontal orientation horizontally adjacent conductive end plates can lose electrical contact more easily. FIG. 7c illustrates an exemplary configuration to mitigate such effects. In the arrangement 700C shown in FIG. 7c, further electrical coupling between horizontally adjacent redox cells is provided via a conductive parallel coupling plate 664 that contacts each of the conductive positive end plates or each of the conductive negative end plates. In such a configuration, vertically adjacent rows of redox cells 710L-1, 710L-2, ..., 710L-l are not in direct contact with each other, but are physically separated and interposed by the conductive parallel coupling plate 664. The conductive parallel connecting plates 664 are connected at both ends by side panels in a manner similar to that described above with respect to Figures 5h, 5i and 6m such that the redox cells are bound into a single unit by a rack structure 728.

[0101] As mentioned above, the electrical connection and / or physical stability of vertically stacked redox batteries can be assisted by gravity. However, the inventors have found that horizontal slippage can still occur, for example, due to external vibration. To address these and other effects, Figs. 7d and 7e diagrammatically illustrate an exemplary coupling mechanism for preventing coupled redox batteries from sliding relative to one another and enabling compact packing according to some other embodiments. Referring to Figs. 7d and 7e, vertically adjacent redox batteries of the redox battery can be configured to be vertically stacked and physically coupled by coupling structures to prevent the coupled redox batteries from sliding laterally relative to one another or to limit relative lateral movement therebetween in at least one direction. The redox battery 700 includes a plurality of redox battery cells 300A-1, 300A-2, ..., 300A-n stacked in a stacking direction, configured in a manner similar to that described above with respect to Figs. 6a-6h, the details of which are not repeated herein for brevity. The redox battery 700 includes a pair of conductive positive end plates 704A, 704B (not shown) disposed at opposite ends of the stacked redox battery cells in the cell stacking direction and electrically coupled to a positive conductive bus bar. Each of the redox batteries also includes a pair of conductive negative end plates 708A, 708B disposed at opposite ends of the stacked redox battery cells in the cell stacking direction and electrically coupled to a negative conductive bus bar 716. The exemplary redox battery 700 illustrated in FIG. 7d also includes slots 736 formed in the bottom edges of the conductive positive end plates 704A, 704B and protrusions or rails 732 formed in the top edges of the conductive negative end plates 708A, 708B correspondingly shaped to mate with the slots 736. However, it is understood that embodiments are not so limited and that the slot 736 may be formed on any of the positive and negative conductive end plates 704A / 704B, 708A / 708B of the redox cell, and the protrusion or rail 732 may be formed on the other one of the positive and negative conductive end plates 704A / 704B, 708A / 708B of the redox cell.The protrusions or rails 732 are configured to slide and fit within the slots 736 in the stacking direction of the cells, where the protrusions or rails 732 and slots 736 have vertical and lateral dimensions to substantially prevent vertically adjacent cells of the redox cell 700 from substantially sliding relative to one another in the length direction of the protrusions or rails 732 and slots 736.

[0102] In the exemplary redox battery 700 illustrated in FIG. 7d, the protrusions or rails 732 and slots 736 are formed as part of the corresponding conductive end plates 708A / 708B, 704A / 704B to provide electrical and mechanical coupling between the conductive end plates, although the embodiments are not limited thereto. In the exemplary arrangement of coupled redox batteries 700E illustrated in FIG. 7e, the rails 740 and slots 744 extend through the entire stack of battery cells. Furthermore, although the rails 740 and slots 744 are configured to serve as coupling structures similar to those described above with respect to FIG. 7d, the rails 740 and slots 744 also serve as positive and negative conductive bus bars for the redox battery 710. Thus, in the illustrated arrangement, separate bus bars may be preferably omitted.

[0103] Redox cell having conductive end plates configured to electrically short the cell - Patents.com As described above, according to various embodiments, a plurality of redox battery cells can be stacked with electrical connections therebetween to form a redox battery. A plurality of redox batteries themselves can also be stacked, e.g., to form a stack or array of redox batteries having parallel and / or serial electrical connections therebetween. Among other advantages, the stacked configuration allows for a modular arrangement of redox batteries such that individual ones of the redox batteries can be removed and conveniently replaced, which in turn allows for efficient servicing for replacement and / or repair. For example, when one or more redox batteries require repair or replacement, it may be safer to at least partially discharge the battery before removing it from the stack or array. It may be safer to at least partially discharge the redox battery before removing an individual redox battery from the stack or array. To address these and other needs, in some embodiments, a redox battery according to some embodiments includes conductive end plates configured to electrically short each other, e.g., thereby discharging the redox batteries. Such a configuration may be useful for fast and / or complete discharge or charge balancing of the redox batteries, e.g., to improve battery capacity. Moreover, such a configuration may be useful for reconfiguring the parallel / series chain of redox cells without removing the redox cells from the stack or array.

[0104] 8b-8d are schematic diagrams of redox battery systems each including one or more redox batteries, where at least one of the batteries includes a conductive end plate configured to electrically short with the other conductive end plate. Each of the redox batteries of the redox battery systems 800A-800D includes a plurality of redox battery cells 300A-1, 300A-2, ..., 300A-n stacked in a stacking direction in a manner similar to that described above with respect to Figs. 7a-7c, the details of which are not repeated herein for brevity. In the exemplary redox battery systems 800A-800D, the redox batteries themselves are stacked and electrically coupled via their respective conductive end plates, according to some embodiments. Each of the redox batteries may be configured according to any of the exemplary configurations described above.

[0105] Each of the redox batteries of the redox battery systems 800A-800D illustrated in Figs. 8a-8d includes a conductive end plate with the same polarity formed on one or both ends of each of the redox battery cell stacks, a conductive end plate with opposite polarity formed on the same end of each of the redox battery cell stacks, or a conductive end plate divided into at least two parts with opposite polarity. The redox battery systems 800A-800D also include a conductive short circuit or electrical connection structure configured to form a direct electrical connection or electrical short circuit between the conductive end plates connected by the first and second ends of the conductive structure. The first end of the conductive short circuit structure is configured to be removably fixed and electrically connected to one of the conductive positive and negative end plates of the plurality of redox batteries, and the second end of the conductive short circuit structure is configured to be removably fixed and electrically connected to the other one of the conductive positive and negative end plates. The conductive shorting structures are configured to form an electrical short between conductive positive and / or negative end plates of the same or different redox cells, which may be formed on the same side of the redox cells.

[0106] FIG. 8a is a schematic diagram of a redox battery system 800A including a redox battery having conductive end plates of opposite polarity configured to be electrically shorted using a conductive shorting structure. In the exemplary redox battery 700, one of a pair of conductive positive end plates 704A, 704B and one of a pair of conductive negative end plates 708A, 708B form a pair of adjacently disposed conductive end plates at respective ends of the same redox battery cell stack in a manner similar to that described above with respect to FIGS. 7a-7c. Also, the conductive shorting structure 804 is configured to form an electrical short between the adjacently disposed positive conductive end plate 704A and the negative conductive end plate 708A of opposite polarity. To protect a user, the conductive shorting structure 804 includes a conductive inner structure 808 that is covered by an insulating outer structure 812 except for the exposed ends of the conductive inner structure 808. Apertures 724A, 724B formed on the conductive end plate are configured to receive a conductive shorting structure 804 to provide a conductive path.

[0107] As configured, the redox battery system 800A illustrated in FIG. 8a allows for substantially complete discharge of the redox batteries to approximately 0% state of charge (SoC). The substantially complete discharge improves safety during removal of the redox batteries for service or replacement. Also, the substantially complete discharge of every redox battery in the redox battery stack or array can improve the uniformity of the SoC of the redox batteries in the redox battery stack or array by allowing the redox batteries to be reset so that they can begin charging from approximately 0% SoC. This ultimately improves the overall capacity of the system by reducing or preventing undercharging of some redox batteries that may have higher SoC values ​​compared to others, etc.

[0108] 8b is a schematic diagram of a redox battery system 800B including a plurality of vertically stacked redox batteries 700 each having an electrically conductive end plate of opposite polarity at each end. The electrically conductive end plates of vertically adjacent redox batteries of opposite polarity are configured to be electrically shorted using an electrically conductive shorting structure 804. An example arrangement includes a stacked string of a plurality of redox batteries 700 stacked vertically with electrically conductive positive end plates 704A and negative end plates 708A vertically alternating from a first end of the stacked string of redox batteries 700, and similarly with electrically conductive positive end plates 704B and negative end plates 708B vertically alternating at a second end of the stacked string of redox batteries 700. The electrically conductive shorting structure 804 is configured to form an electrical short between the electrically conductive positive end plates 704A and the electrically conductive negative end plates 708A of vertically adjacent ones of the redox batteries. As configured, vertically adjacent redox cells may be electrically connected in series, linked by a shorting structure 804 that shorts the conductive end plates of adjacent redox cells of opposite polarity.

[0109] 8c is a schematic diagram of a redox cell system 800C including a plurality of horizontally stacked redox cells 700 each having an electrically conductive end plate of opposite polarity at each end. The electrically conductive end plates of horizontally adjacent redox cells with the same polarity are configured to be electrically shorted using an electrically conductive shorting structure 804. An example arrangement includes a plurality of stacked rows of redox cells 700 stacked horizontally such that the electrically conductive positive end plate 704A and the electrically conductive negative end plate 708A at a first end of the stacked row of redox cells 700 are horizontally linearly arranged, and similarly, the electrically conductive positive end plate 704B and the electrically conductive negative end plate 708B at a second end of the stacked row of redox cells 700 are horizontally linearly arranged. The electrically conductive shorting structure 804 is configured to form an electrical short between the electrically conductive positive end plates 704A of horizontally adjacent ones of the redox cells 700. Additionally, the conductive shorting structure 804 is configured to form an electrical short between the conductive negative end plates 708A of horizontally adjacent ones of the redox cells 700. As configured, horizontally adjacent redox cells connected by a shorting structure 804 shorting the conductive end plates of adjacent redox cells of the same polarity can be electrically connected in parallel.

[0110] FIG. 8d is a schematic diagram of a redox cell system 800D including a plurality of horizontally and vertically stacked redox cells 700, each having an opposite polarity conductive end plate at each end. The exemplary redox cells are arranged in a manner similar to that described above for FIG. 7c, and a detailed description thereof is omitted. The redox cell system 800D includes vertically adjacent rows of redox cells 810L-1, 810L-2, ..., 810L-l that are not in direct contact with each other, but are physically separated and interposed by conductive parallel connecting plates 664. The conductive parallel connecting plates 664 are connected at both ends by side panels in a manner similar to that described above for FIG. 5h, FIG. 5i, and FIG. 6m, such that the redox cells are bound in a single unit by a rack structure 728. The redox cells within a given row can be electrically connected in parallel. Additionally, electrical connection between vertically adjacent redox cells is provided via conductive shorting structures 804 arranged in a manner similar to that described above for Figure 8b. Thus, redox cells connected by shorting structures 804 can be electrically connected in series.

[0111] In each of the redox battery system configurations described above with respect to FIGS. 8a-8d, the conductive shorting structure 804 has a U-shape or a handle shape that is easy for a user to grasp. Additionally, the conductive positive end plate 704A and / or the conductive negative end plate 708A electrically shorted by the conductive shorting structure 804 form an opening 724A, 724B thereon configured to receive one of the first end 816A and the second end 816B of the conductive shorting structure. Additionally, the conductive shorting structure 804 can act as a handle for removing the redox battery 700 from the redox battery system. In these embodiments, the conductive shorting structure 804 may be formed by coating the conductive material 808 in a portion configured to contact the hand with an insulating film 812. However, it will be appreciated that embodiments are not limited thereto and the shorting structure 804 can have any suitable shape and the insulating film 812 can be omitted.

[0112] Although not illustrated, various sensors may be coupled to the conductive shorting structure. Examples of sensors include voltage sensors, current sensors, and temperature sensors. The conductive shorting structure may also communicatively couple the redox battery to a battery management system (BMS). The conductive shorting structure may also include other functional components, such as current or voltage regulators or rectifiers, such as diodes, to allow current flow in one direction, but not the other direction, between 0.6V and 1.2V, for example.

[0113] A redox cell including a bus bar extending over a top surface thereof. As described above, the busbars according to the embodiments allow compact bundling of redox battery cells in a redox battery as well as multiple redox batteries in an energy storage system. In various embodiments described above, the redox battery includes a busbar that extends on its side surfaces, for example in the stacking direction of the redox battery cells. However, the embodiments are not limited thereto and will now be described various embodiments of a redox battery including a busbar that extends on its side surfaces and further extends on its top and / or bottom surfaces according to various other embodiments. For example, an end portion of a positive conductive busbar is bent and placed at an end of the redox battery cell stack, and an end portion of a negative conductive busbar is bent and placed at an end or other end of the redox battery cell stack.

[0114] 9a and 9b are exploded perspective and side views, respectively, of a redox battery cell 10 according to some embodiments. The redox battery cell 10 includes a frame or casing 11b, an anode or negative electrode 12, a cathode or positive electrode 13, and a separator or ion exchange membrane 19 separating the anode 12 and the cathode 13. The anode 12, which may be disposed in a negative electrolyte reservoir formed by the volume between the separator 19 and a first bipolar plate 17a, is electrically coupled to an anode current collector 14. The cathode 13, which may be disposed in a positive electrolyte reservoir formed by the volume between the separator 19 and a second bipolar plate 17b, is electrically coupled to a cathode current collector 15. The frame or casing 11, the first bipolar plate 17a and the second bipolar plate 17b define a closed or sealed volume that is separated by a separator 19 into two spaces, a negative electrolyte reservoir housing the anode 12 and a positive electrolyte reservoir housing the cathode 13. The negative electrolyte reservoir contains an electrolyte in which the anode redox couple dissolves and may further include a conductive material, e.g., carbon felt, as part of the anode 12, in a manner similar to that described above for FIG. 2a. For example, the anode redox couple may include one or more of the following elements: vanadium (V), zinc (Zn), bromine (Br), chromium (Cr), manganese (Mn), titanium (Ti), iron (Fe), cerium (Ce), and cobalt (Co). In one embodiment, the anode redox couple is V. 2+ / V 3+The electrolyte may be an acidic aqueous solution, preferably containing sulfuric acid, which is a solution that conducts electric current through ionization. In one embodiment, the electrolyte may be prepared by dissolving VOSO4 (vanadyl sulfate) in H2SO4. The positive electrolyte reservoir contains the electrolyte in which the cathode redox couple is dissolved, and may further contain a conductive material, e.g., carbon felt, as part of the cathode 13, in a manner similar to that described above for FIG. 2a. For example, the cathode redox couple may include one or more of the following elements: vanadium (V), zinc (Zn), bromine (Br), chromium (Cr), manganese (Mn), titanium (Ti), iron (Fe), cerium (Ce), and cobalt (Co). In one embodiment, the cathode redox couple is V 4+ / V 5+ The electrolyte is preferably the same between the positive and negative electrolyte reservoirs. The anode current collector 14 and the cathode current collector 15 can be made of a metal having high electrical conductivity, such as copper or aluminum, and can carry electrical current during the charging and discharging process. The anode current collector 14 and the cathode current collector 15 can protrude from the frame 11 and can be configured to be coupled to a bus bar as described herein. The bipolar plates 17a, 17b can be disposed between the anode current collector 14 and the anode, and between the cathode current collector 15 and the cathode, respectively. The bipolar plates 17a, 17b serve, among other things, to prevent the current collectors 14, 15 from oxidizing. In some implementations, the bipolar plates 17a, 17b can be coatings formed on the current collectors 14, 15, respectively.

[0115] 10a and 10b are side and perspective views of a redox battery including a plurality of stacked redox battery cells according to some embodiments. A redox battery 20 according to one embodiment includes a plurality of redox battery cells 10 stacked in a stacking direction. The anode 12 of any one of the redox battery cells 10 is stacked with the anode 12 of the nearest redox battery cell 10, and the cathode 13 of any one of the redox battery cells 10 is stacked with the cathode 13 of the nearest redox battery cell. As configured, the nearest redox battery cells of the redox battery cells 10 share one anode current collector 14 or cathode current collector 15. That is, the plurality of redox battery cells 10 are stacked such that the anode 12 of a first redox battery cell 10a is stacked adjacent to the anode 12 of a second redox battery cell 10b via the anode current collector 14. Similarly, the cathode 13 of the second redox battery cell 10b is stacked adjacent to the cathode 13 of the third redox battery cell 10c via the cathode current collector 15. The redox battery 20 typically has a six-sided rectangular parallelepiped shape stacked in the stacking direction of the redox battery cells 10. The anode current collector 14 and the cathode current collector 15 protrude from the sides of the frame 11 and are configured to be coupled to positive and negative bus bars, respectively, as described below.

[0116] 11a and 11b are side and top views of a redox battery including a plurality of stacked redox battery cells, according to some embodiments. According to one embodiment, an exemplary redox battery 30 includes a plurality of redox battery cells 10 stacked in a stacking direction and a pair of conductive end plates 130, 140 disposed at both ends of the stacked redox battery cells 10. The redox battery 30 also includes a pair of bus bars 110, 120 that electrically couple the plurality of redox battery cells 10. The pair of conductive end plates 130, 140 serve to protect the ends of the stacked redox battery cells 10 and, together with the pair of bus bars 110, 120, apply pressure to the plurality of redox battery cells 10, as described above, among other functions described herein. As discussed above, the application of pressure provides, among other things, a leak-tight seal between the frame 11 (FIGS. 9a-b) and the bipolar plates 17a, 17b (FIGS. 9a-b) or the current collectors 14, 15 (FIGS. 10a-b). In some implementations, each of the conductive end plates 130, 140 has a chamfer formed on its outer edge. For example, a chamfer may be formed on an edge portion of one or both of the conductive end plates 130, 140 that corresponds to a curved portion of one or both of the bus bars 110, 120. In this case, the chamfer may serve to reduce friction between the conductive end plates 130, 140 and the bus bars 110, 120. The pair of conductive end plates 130, 140 includes a first conductive end plate 130 disposed at one end of the stacked redox battery cells 10 and a second conductive end plate 140 disposed at the other end of the stacked redox battery cells 10. Each of the bus bars 110, 120 electrically and physically connects the multiple redox battery cells 10. Each of the pair of bus bars 110, 120 is formed in a bar shape extending in the stacking direction of the multiple redox battery cells 10. Each of the pair of bus bars 110, 120 is arranged in the length direction in the stacking direction of the stacked redox battery cells 10. One end of each bus of the pair of bus bars 110, 120 is bent and arranged on any one of the pair of conductive end plates 130, 140.The pair of bus bars 110, 120 are coupled to a pair of conductive end plates 130, 140 to apply pressure to the stacked redox battery cells 10. Each bus bar of the pair of bus bars 110, 120 has an appropriate curvature at the curved portion to prevent them from being easily damaged.

[0117] 11a and 11b, the pair of bus bars 110, 120 includes a negative bus bar 110 that electrically connects the anode current collectors 14 of the multiple redox battery cells 10 to each other, and a positive bus bar 120 that electrically connects the cathode current collectors 15 of the multiple redox battery cells 10. An end portion of the negative bus bar 110 is bent to cover a part of the second conductive end plate 140 and is electrically and / or physically connected to the second conductive end plate 140. Similarly, an end portion of the positive bus bar 120 is bent to cover a part of the first conductive end plate 130 and is electrically and / or physically connected to the first conductive end plate 130. In an embodiment in which the pair of conductive end plates 130, 140 are omitted, the pair of bus bars 110, 120 are formed on the frame 11 of the redox battery cell 10 arranged at the end of the stack of the redox battery cells 10. In these implementations, the portions of the bus bars 110, 120 that are coupled to the frames 11 of each of the redox battery cells 10 at the ends of the stack can serve as conductive end plates. Also, in some implementations, a pair of bus bars 110, 120 can be coupled to the anode current collectors 14 and / or cathode current collectors 15 of the redox battery cells 10 upon which the curved portions of the stack of redox battery cells 10 are disposed.

[0118] In the redox battery described above with respect to Figs. 11a and 11b, the conductive end plate 140, e.g., the positive conductive end plate, on one end of the stack of batteries 10, e.g., can have a curved portion over the second conductive end plate 120, if present, and the conductive end plate 130, e.g., the negative conductive end plate, on the other end of the stack of batteries 10, e.g., can have a curved portion over the first conductive end plate 130, if present, the second conductive end plate 120. However, the embodiments are not limited thereto. Figs. 12a and 12b are side and top views of a redox battery including a plurality of stacked redox battery cells according to some other embodiments. The redox battery 40 illustrated according to one embodiment includes a plurality of redox battery cells 10 stacked in a stacking direction in a manner similar to the redox battery 30 described above with respect to Figs. 11a and 11b, and a pair of conductive end plates 130, 140 disposed at both ends of the stacked redox battery cells 10. However, unlike the redox battery 30 (FIGS. 11a and 11b), in the example redox battery 40, each of the pair of bus bars 110, 120 is bent and coupled to the same one of the conductive end plates 130 or 140. In the example embodiment, the negative bus bar 110 and the positive bus bar 120 are both bent and coupled to the first conductive end plate 130. Also, unlike the redox battery 30 (FIGS. 11a and 11b), in which the curved portions of the negative bus bar 110 and the positive bus bar 120 substantially cover (e.g., more than 50%) the surface area of ​​each of the conductive end plates 130, 140, in the example redox battery 40, the curved portions of the negative bus bar 110 and the positive bus bar 120 cover (e.g., less than 50%) the surface area of ​​each of the conductive end plates 130 or 140.

[0119] FIG. 13 is a plan view of an energy storage device including a plurality of redox batteries, according to some embodiments. The energy storage device 400 includes a first redox battery 100 and a second redox battery 200, each of which includes a plurality of redox battery cells 10 stacked in a stacking direction and configured in a manner similar to the redox batteries described above for, for example, without limitation, FIG. 11a and FIG. 11b. The first redox battery 100 and the second redox battery 200 can be stacked in a direction perpendicular to the stacking direction and in contact with each other. The energy storage device 400 also includes a common bus bar 150 that electrically and physically couples the plurality of redox battery cells 10 of the first redox battery 100 and the second redox battery 200. The first redox battery 100 includes a plurality of redox battery cells 10 stacked in a first stacking direction, and a positive bus bar 120 electrically couples the cathode current collectors 15 of the redox battery cells 10 to each other. The second redox battery 200 includes a plurality of redox battery cells 10 stacked in a second stacking direction that is opposite to the first stacking direction, and a negative bus bar 110 electrically connects the anode current collectors 14 of the redox battery cells 10 to each other. Because the redox battery cells 10 of the first redox battery 100 and the second redox battery 200 are arranged in opposite redox battery stacking directions, when viewed from the stacking direction as shown in FIG. 13, a front view of the first redox battery 100 and the second redox battery 200 shows the positive bus bar 120 on the conductive end plate 130 and the negative bus bar 110 on the conductive end plate 140, respectively. A common bus bar 150 physically and electrically connects the first redox battery 100 and the second redox battery 200 in series. The common bus bar 150 is connected to one of the conductive end plates 130, 140 of the first redox cell 100 and is further connected to one of the conductive end plates 130, 140 of the second redox cell 200, thereby physically connecting the first redox cell 100 and the second redox cell 200.

[0120] FIG. 14 is a plan view of an energy storage device including multiple redox batteries, according to some embodiments. The energy storage device 500 includes first to fourth redox batteries 100, 200, 300, 400, each of which includes multiple redox battery cells 10 stacked in a stacking direction and configured in a manner similar to the redox batteries described above for, for example, without limitation, FIG. 11a and FIG. 11b. The first to fourth redox batteries 100, 200, 300, 400 are stacked in a direction perpendicular to the stacking direction. The redox battery cells 10 of the first redox battery 100 and the third redox battery 300 are stacked in the stacking direction of the first battery, while the redox battery cells 10 of the second redox battery 200 and the fourth redox battery 400 are stacked in the stacking direction of the second battery. Since the stacking direction of the battery cells alternates, when viewed from the stacking direction as shown in Fig. 14, the front view of the first to fourth redox batteries 100, 200, 300, 400 alternately shows the positive bus bar 120 and the negative bus bar 110. The energy storage device 500 also includes a common bus bar 150 that electrically and physically connects the multiple redox battery cells 10 of adjacent redox batteries, for example, the first redox battery 100 and the second redox battery 200, and the third redox battery 300 and the fourth redox battery 400. The energy storage device 500 further includes a connecting bus bar 160 that connects the positive bus bar 120 and the negative bus bar 110 of adjacent redox batteries, for example, the second redox battery 200 and the third redox battery 300. In the illustrated arrangement, the connecting bus bar 160 electrically connects the redox cells 200, 300 that are not connected to the common bus bar 150. The first redox cell 100 and the second redox cell 200 are connected by the common bus bar 150, and the third redox cell 300 and the fourth redox cell 400 are connected to the common bus bar 150. The connecting bus bar 160 connects the second redox cell 200 and the third redox cell 300 that are not connected in series by the common bus bar 150. The connecting bus bar 160 is electrically connected to the negative bus bar 110 of the second redox cell 200 and the positive bus bar 120 of the third redox cell 300.The connecting bus bar 160 is connected to a portion of the negative bus bar 110 disposed on the second conductive end plate 140 of the second redox cell 200. Similarly, the connecting bus bar 160 is connected to a portion of the positive bus bar 120 disposed on the first conductive end plate 130 of the third redox cell 300.

[0121] FIG. 15a is a side view of a storage device including a plurality of redox batteries, according to some embodiments. FIG. 15b is a top view and a bottom view of the storage device illustrated in FIG. 15a. Similar to the energy storage device described above with respect to FIG. 13, the energy storage device 600 includes a first redox battery 100 and a second redox battery 200, each of which includes a plurality of redox battery cells 10 stacked in a stacking direction and configured in a manner similar to the redox batteries described above with respect to FIG. 11a and FIG. 11b, for example, without limitation. The first redox battery 100 and the second redox battery 200 can be stacked in a direction perpendicular to the stacking direction and in contact with each other. However, unlike the energy storage device described above with respect to FIG. 13, in which the bus bars 120, 110 extending on the side walls of adjacent redox cells 100, 200 do not face each other, in the storage device 600, the negative bus bar 110 extending on the side wall of the first redox cell 100 is arranged to face the negative bus bar 110 extending on the side wall of the adjacently disposed second redox cell 200. In the illustrated embodiment, the negative bus bar 110 along the side wall of the first redox cell 100 contacts the positive bus bar 120 along the side wall of the second redox cell 200, so that the first redox cell 100 and the second redox cell 200 are electrically connected in series. Furthermore, the negative bus bar 110 and the positive bus bar 120 that contact each other can also be electrically connected by a connecting bus bar 160 at the rear ends of the first redox cell 100 and the second redox cell 200. Additionally, the negative bus bar 110 and the positive bus bar 120 on the opposing non-contact side walls of the first and second redox cells 100 and 200, respectively, may be further configured to be electrically connected to additional redox cells by a connecting bus bar 160 (not shown) that extends away from the first and second redox cells 100 and 200 at the front ends of the first and second redox cells 100 and 200.

[0122] FIG. 16 is a side view of an energy storage device including multiple redox batteries, according to some embodiments. The energy storage device 700 includes a first redox battery 100, a second redox battery 200, and a third redox battery 300, each of which includes multiple redox battery cells 10 stacked in a stacking direction and configured in a manner similar to the redox batteries described above for, for example, without limitation, FIG. 11a and FIG. 11b. The energy storage device 700 also includes a common bus bar 150 configured to electrically and physically connect the redox battery cells 10 of the redox batteries 100, 200 and configured to bend 180 degrees at any portion of the redox battery. The common bus bar 150 is electrically connected to the anode current collector 14 of the battery cells 10 of the first redox battery 100 and further electrically connected to the cathode current collector 15 of the redox battery cells 10 of the second redox battery 200. The common bus bar 150 is configured to bend 180 degrees and fold back on itself, and the common bus bar 150 extending over the side walls of the first and second redox cells 100 and 200 contact each other in a manner similar to that described above with respect to Figures 15a and 15b, thereby electrically connecting the first and second redox cells 100 and 200 in series. As configured, the common bus bar 150 is not connected to the conductive end plates 130, 140 of the first and second redox cells 100 and 200. The energy storage device 700 further includes a connecting bus bar 160 that electrically connects the redox cells 200, 300 that are not connected to the common bus bar 150.

[0123] 17a and 17b are plan views of two different states of an energy storage device including a plurality of redox batteries, according to some embodiments. The energy storage device 800 includes a first redox battery 100, a second redox battery 200, and a third redox battery 300, each of which includes a plurality of redox battery cells 10 stacked in a stacking direction and configured in a manner similar to the redox batteries described above for, for example, without limitation, Figs. 11a and 11b. The energy storage device 800 also includes a common bus bar 150 configured to electrically and physically couple the redox battery cells 10 of the first redox battery 100 and the second redox battery 200. The energy storage device 800 includes a reconfigurable coupling bus bar 160 that can alternately electrically couple the first and second redox cells 100 and 200 that are coupled by a common bus bar 150 (FIG. 17b) or the second and third redox cells 200 and 300 that are not coupled by the common bus bar 150 (FIG. 17b). According to an embodiment, the coupling bus bar 160 is configured to be toggled between the two illustrated positions using a suitable switching or reconfiguration mechanism. In some embodiments, the coupling bus bar 160 is configured to be physically separated from the second and third redox cells 200 and 300 that are not coupled to the common bus bar 150, and then physically attached to the first and second cells 100 and 200 that are coupled to the common bus bar 150. In some other embodiments, the coupling bus bar 160 may be configured to rotate about one of the ends of the coupling bus bar 160 that serves as a pivot. In yet some other embodiments, the coupling bus bar 160 can slide linearly from one position to another. The coupling bus bar 160 is configured to electrically couple the redox cells 100, 200 coupled to the common bus bar 150 to short-circuit and discharge the redox cells 100, 200.Preferably, after the first redox battery 100 and the second redox battery 200 are shorted and discharged by the connecting bus bar 160, a user can safely remove one or both of the first redox battery 100 and the second redox battery 200, for example, for replacement or maintenance of the energy storage device 800. In some embodiments described above, the positive and negative electrolyte reservoirs of the redox battery cell 10 can contain the same electrolyte, and the connecting bus bar 160 can reliably and safely electrically short the anode 12 and the cathode 13. In a manner similar to that described above, the connecting bus bar 160 can act as a handle when removing the first redox battery 100 and the second redox battery 200.

[0124] 18a-18c are plan views of energy storage devices including multiple redox batteries, according to some embodiments. Energy storage devices 900A (FIG. 18a), 900B (FIG. 18b, 18c) include a first redox battery 100 and a second redox battery 200, each of which includes multiple redox battery cells 10 stacked in a stacking direction and configured in a manner similar to the redox batteries described above for, for example, without limitation, FIG. 12a and 12b. The redox battery cells of the first redox battery 100 and the second redox battery 200 are stacked in the same stacking direction such that the front faces of both the first redox battery 100 and the second redox battery 200 have the same alignment. Unlike the redox cells of the energy storage devices described above with respect to Figures 14-17b, each of the first redox cell 100 and the second redox cell 200 of the energy storage devices 900A, 900B includes both a positive bus bar 120 and a negative bus bar 110 across their front faces. Each of the energy storage devices 900A, 900B includes a reconfigurable connecting bus bar 160 disposed on a conductive end plate 130, 140 to which the pair of bus bars 110, 120 are coupled for electrically connecting the adjacent first redox cell 100 and the second redox cell 200. The arrangement direction and switching or reconfiguration mechanism of the connecting bus bar 160 may vary depending on the lateral stacking arrangement of the redox cells 100, 200, as described below.

[0125] 18a, the first redox cell 100 and the second redox cell 200 of the energy storage device 900A are stacked side-to-side such that the negative bus bar 110 and the positive bus bar 120 are linearly arranged in the side-to-side stacking direction of the first redox cell 100 and the second redox cell 200. The negative bus bar 110 and the positive bus bar 120 are both bent and coupled to the first conductive end plate 130, and the connecting bus bar 160 is disposed on the first conductive end plate 130 to electrically connect the negative bus bar 110 of the first redox cell 100 and the positive bus bar 120 of the second redox cell 200. The connecting bus bar 160 extends diagonally because the resulting portion of the negative bus bar 110 of the first redox cell 100 and the portion of the positive bus bar 120 of the second redox cell 200 are disposed diagonally.

[0126] 18b, the first and second redox cells 100 and 200 of the energy storage device 900B are stacked side-to-side such that the negative and positive bus bars 110 and 120 are arranged in alternating stacking directions in the side-to-side direction of the first and second redox cells 100 and 200. As described with respect to FIGS. 12a and 12b, the exemplary energy storage device 900B includes a reconfigurable connecting bus bar 160 similar to that described above with respect to FIGS. 17a and 17b and arranged horizontally. As illustrated, the connecting bus bar 160 is configured to move between a state in which the connecting bus bar 160 electrically connects the negative and positive bus bars 110 and 120 of the same redox cell 100 and a state in which the connecting bus bar 160 electrically connects the negative bus bar 110 of the second redox cell 200 to the positive bus bar 120 of the first redox cell 100. In a manner similar to that described above with respect to Figs. 17a and 17b, the coupling bus bar 160 may be reconfigured or switched, separable, rotatable, or slidable, using an appropriate mechanism. When the coupling bus bar 160 electrically couples the negative bus bar 110 and the positive bus bar 120 of the first redox battery 100, the first redox battery 100 may be short-circuited. As described above with respect to Figs. 17a and 17b, after the first redox battery 100 and the second redox battery 200 are short-circuited and discharged by the coupling bus bar 160, a user may safely remove one or both of the first redox battery 100 and the second redox battery 200, for example, for replacement or maintenance of the energy storage device 900B. Additionally, the coupling bus bar 160 may act as a handle when removing the first redox battery 100 and the second redox battery 200.

[0127] 19a and 19b are plan views of an energy storage device including one or more rows of redox batteries, according to some embodiments. The energy storage device 1000 includes a plurality of redox battery cells 10, including a plurality of first redox batteries 100a and a plurality of second redox batteries 100b, each of which is stacked in a stacking direction and configured in a manner similar to the redox batteries described above for, for example, without limitation, FIG. 11a and FIG. 11b. The plurality of first redox batteries 100a are arranged in a first row extending in the row extension direction, and the plurality of second redox batteries 100b are arranged in the same row extension direction as the first redox batteries 100a. The row direction is perpendicular to the stacking direction of the redox battery cells 10. A plurality of bus bars 160 electrically couple pairs of the first redox batteries 100a and / or the second redox batteries 100b. The connecting bus bars 160 connecting the same redox cells of the first redox cell 100a or the second redox cell 100b are arranged in a direction parallel to the extending direction of the row of the first redox cell 100a or the second redox cell 100b, or in a direction perpendicular to the connecting direction between the first redox cell 100a and the second redox cell 100b. Referring to FIG. 19a, in some arrangements, the first redox cell 100a in the first row and the second redox cell 100b in the second row are positioned at corresponding horizontal positions. In these arrangements, the connecting bus bars 160 at the ends connecting the last first redox cell of the first redox cell 100a and the last second redox cell of the second redox cell 100b extend in a direction perpendicular to the extending direction of the row. 19b, in some other arrangements, the first redox cell 100a in the first row and the second redox cell 100b in the second row are positioned at horizontally offset positions. In these arrangements, the end connection bus bar 160 connecting the last first redox cell of the first redox cells 100a and the last second redox cell of the second redox cells 100b extends in an oblique direction with respect to the direction perpendicular to the extension direction of the rows.

[0128] 19a and 19b, the energy storage device 1000 may further include a support 210 disposed between the plurality of first and second redox cells 100a and 100b. The support 210 may be made of an insulating material to insulate the first and second redox cells 100a and 100b from the second redox cell module 100b. The support 210 guides the arrangement of the first and second redox cells 100a and 100b. The support 210 acts as a guide when a portion of the first and / or second redox cells 100a and 100b are removed or inserted. The connecting bus bar 160 may cross the support 210 as shown.

[0129] FIG. 20 is a plan view of an energy storage device including one or more rows of redox batteries, according to some embodiments. The energy storage device 1200 includes a plurality of redox batteries 100, 200, 300, 400, 500, each of which includes a plurality of redox battery cells 10 stacked in a stacking direction and configured in a manner similar to the redox batteries described above for FIG. 11a and FIG. 11b, for example, without limitation. The redox batteries 100, 200, 300, 400, 500 are arranged in rows extending in a row extension direction. The row direction is perpendicular to the stacking direction of the redox battery cells 10. The energy storage device 1200 includes a plurality of coupling bus bars 160a, 160b. In a manner similar to that described above for FIG. 19, the coupling bus bars 160a, 160b electrically couple pairs of redox batteries 200, 300 and 400, 500. The energy storage device 1200 also includes a shorting bus bar 170 that electrically connects the multiple connecting bus bars 160a, 160b. The shorting bus bar 170 electrically connects the connecting bus bars 160a, 160b connected to the redox batteries 300, 400 connected by the common bus bar 150. The shorting bus bar 170 electrically shorts the redox batteries 200, 300, 400, 500 electrically connected by the connecting bus bars 160a, 160b. In this embodiment, the first connecting bus bar 160a electrically connects the second redox battery 200 and the third redox battery 300 in series, and the second connecting bus bar 160b electrically connects the fourth redox battery 400 and the fifth redox battery 500 in series. The shorting bus bar 170 electrically connects the first connecting bus bar 160a and the second connecting bus bar 160b to short the third redox cell 300 and the fourth redox cell 400. Preferably, when a failure occurs in any of the third cell 300 and the fourth cell 400, they do not interrupt the operation of the energy storage device 1200 and can be shorted using the shorting bus bar 170. Although shorting some of the redox cells using the shorting bus bar 170 can reduce the overall performance of the energy storage device 1200, it may nevertheless be advantageous to continue its operation without interruption.In some implementations, the shorted third cell 300 and fourth cell 400 can function as resistors to generate heat, which can be used for thermal management of the redox battery.

[0130] FIG. 21 is a plan view of an energy storage device including one or more rows of redox batteries, according to some embodiments. The energy storage device 1300 includes a plurality of redox batteries 100, 200, 300, 400, 500, each of which includes a plurality of redox battery cells 10 stacked in a stacking direction and configured in a manner similar to the redox batteries described above for FIG. 11a and FIG. 11b, for example, without limitation. The redox batteries 100, 200, 300, 400, 500 are arranged in rows extending in a row extension direction. The row direction is perpendicular to the stacking direction of the redox battery cells 10. The energy storage device 1300 includes a plurality of coupling bus bars 160a, 160b. In a manner similar to that described above for FIG. 19, the coupling bus bars 160a, 160b electrically couple pairs of redox batteries 200, 300 and 400, 500. The energy storage device 1300 also includes a shorting busbar 170 coupled to the coupling busbars 160a and 160b. The shorting busbar 170 can be controlled by, for example, the battery management system 1100 to electrically couple the coupling busbars 160a and 160b. The shorting busbar 170 includes a busbar body 171 coupled to the multiple coupling busbars 160, a busbar switch 172 for controlling the flow of current through the busbar body 171, and a busbar resistor 173 for adjusting the amount of current flow through the busbar body 171. At least a portion of the busbar body 171 is formed of a conductor for electrically coupling the multiple coupling busbars 160 when the busbar switch 172 is short-circuited (ON). The busbar switch 172 is configured to be controlled by the battery management system 1100 to control the energy storage device 1300 to short-circuit (ON) or open (OFF) the busbar body 171. The busbar resistor 173 is configured to adjust the amount of current flowing through the busbar body 171 to prevent too much current from flowing when the busbar switch 172 is shorted (ON). Heat generated from the busbar resistor 173 can be used for thermal management of at least one of the multiple redox batteries 100, 200, 300, 400, 500.According to one embodiment, shorted bus bar 170 includes multiple bus bar switches 172 and multiple bus bar resistors 173 to allow for incremental adjustment of the amount of current and heat.

[0131] FIG. 22 is a plan view of an energy storage device including one or more rows of redox batteries, according to some embodiments. The energy storage device 1400 includes a plurality of redox batteries 100, 200, 300, 400, 500, each of which includes a plurality of redox battery cells 10 stacked in a stacking direction and configured in a manner similar to the redox batteries described above with respect to, for example, without limitation, FIGS. 12a and 12b. The redox batteries 100, 200, 300, 400, 500 are arranged in rows extending in a row extension direction. The row direction is perpendicular to the stacking direction of the redox battery cells 10. Unlike the redox batteries of the energy storage devices described above with respect to FIGS. 19a-21, each of the redox batteries 100, 200, 300, 400, 500 of the energy storage device 1400 includes both a positive bus bar 120 and a negative bus bar 110 portion across their front faces. The energy storage device 1400 also includes a connecting bus bar 160 that connects the negative bus bar 110 of one of the redox cells, e.g., redox cell 100, to the positive bus bar 120 of an adjacent one of the redox cells, e.g., redox cell 200. The energy storage device 1400 also includes a shorted bus bar 170 that connects to each pair of bus bars 110, 120 of the redox cells. The shorted bus bar 170 includes a bus bar body 171 connected to the pair of bus bars 110, 120, a bus bar switch 172 for controlling the flow of current through the bus bar body 171, and a bus bar resistor 173 for controlling the amount of current flow through the bus bar body 171.

[0132] Unless the context clearly requires otherwise, the words "comprise," "comprising," "include," "including," and the like in the description and claims throughout are to be construed in an inclusive sense; that is, "including, but not limited to," as opposed to an exclusive or all-encompassing sense. The word "coupled," as used generally herein, refers to two or more elements that may be directly connected or connected through one or more intermediate elements. Similarly, the word "connected," as used generally herein, refers to two or more elements that may be directly connected or connected through one or more intermediate elements. Additionally, the words "herein," "upon," "down," and words of similar import, when used in this application, refer to this application as a whole and not to any particular portions of this application. Where the context permits, words in the above detailed description using the singular or plural number may also include the plural or singular number, respectively. When referring to a list of two or more items, the word "or" includes the following interpretations of the word: any one of the items in the list, any one of the items in the list, and any combination of the items in the list.

[0133] Additionally, conditional language used herein, such as "can," "could," "has been," "may," "for example," "for example," "such as," among others, is intended to convey that certain embodiments generally include certain features, elements and / or conditions, but other embodiments do not, unless specifically stated otherwise or understood otherwise within the context in which it is used. Thus, such conditional language is not intended to generally imply that features, elements and / or conditions are required in any way to one or more embodiments, or that these features, elements and / or conditions may or may not be included in or performed in any particular embodiment.

[0134] Although specific embodiments have been described, these embodiments are presented as examples only and are not intended to limit the scope of the present disclosure. Indeed, the novel apparatus, methods, and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions, and changes to the forms of the methods and systems described herein may be made without departing from the spirit of the present disclosure. For example, although blocks are presented in a given arrangement, other embodiments may function similarly with other components and / or circuit topologies, and some blocks may be removed, moved, added, subdivided, combined, and / or modified. Each of these blocks may be embodied in a variety of different ways. Any suitable combination of elements and operations of the various embodiments described above may be combined to provide further embodiments. The various features and processes described above may be embodied independently of one another or may be combined in various ways. It is understood that all possible combinations and subcombinations of features of the present disclosure are within the scope of the present disclosure.

Claims

1. A plurality of redox battery cells stacked in a stacking direction, each of the redox battery cells including a first half cell connected to a positive current collector, a second half cell connected to a negative current collector, and an ion exchange membrane separating the first half cell and the second half cell; A positive conductive bus bar extending in the stacking direction and electrically connecting the positive current collectors of the redox battery cells in parallel; A negative conductive bus bar extending in the stacking direction and electrically connecting the negative current collectors of the redox battery cells in parallel; and A positive end plate and a negative end plate disposed at opposite ends of the stacked redox battery cells, wherein the positive end plate is connected to the positive conductive bus bar, and the negative end plate is connected to the negative conductive bus bar, a redox battery.

2. The positive end plate is electrically conductive with respect to the positive conductive bus bar, and the negative end plate is electrically conductive with respect to the negative conductive bus bar, The redox battery according to Claim 1.

3. One or both of the positive conductive bus bar and the negative conductive bus bar function as fastening ports for compressing the stacked redox battery cells along the stacking direction, The redox battery according to Claim 1.

4. The positive conductive bus bar is mechanically fixed to both the positive end plate and the negative end plate, and is electrically connected to the positive end plate and electrically insulated from the negative end plate, The redox battery according to Claim 1.

5. The negative conductive bus bar is mechanically fixed to both the positive end plate and the negative end plate, and is electrically connected to the negative end plate and electrically insulated from the positive end plate, The redox battery according to Claim 1.

6. The positive conductive bus bar and the negative conductive bus bar are both mechanically fixed to the positive end plate and the negative end plate using one or more mechanical coupling structures, The redox battery according to Claim 1.

7. An insulating layer is interposed between the redox battery cell stack and one or both of the positive end plate and the negative end plate, The redox battery according to Claim 1.

8. The negative electrode conductive bus bar and the positive electrode conductive bus bar are arranged on the opposing surfaces of the redox battery cell stack. The redox battery according to claim 1.

9. A pair of negative electrode conductive bus bars are arranged on a pair of opposing surfaces of the redox battery cell stack. A pair of positive electrode conductive bus bars are arranged on the other pair of opposing surfaces of the redox battery cell stack. The redox battery according to claim 1.

10. The redox battery further includes a tie band that forms a loop around the redox battery cell stack. The redox battery according to claim 1.

11. Including a plurality of redox batteries. Each of the plurality of redox batteries. A plurality of redox battery cells stacked in a stacking direction, each of the redox battery cells includes a positive electrode current collector and a negative electrode current collector. A positive electrode conductive bus bar that extends in the stacking direction and electrically connects the positive electrode current collectors of the redox battery cells in parallel. A negative electrode conductive bus bar that extends in the stacking direction and electrically connects the negative electrode current collectors of the redox battery cells in parallel. A pair of conductive positive electrode end plates arranged at the opposing ends of the stacked redox battery cells and connected to the positive electrode conductive bus bar, and A pair of conductive negative electrode end plates arranged at the opposing ends of the stacked redox battery cells and connected to the negative electrode conductive bus bar. One or more subsets of the redox battery are stacked in at least one other direction orthogonal to the stacking direction of the cells and are electrically connected to each other. Redox battery system.

12. One of the pair of conductive positive electrode end plates and one of the pair of conductive negative electrode end plates form a pair of adjacent end plates with opposite polarities arranged on the same end of the same redox battery cell stack. The redox battery system according to claim 11.

13. The stacking direction of the cells is the first horizontal direction, and the first subset of the redox battery is stacked in a vertical direction orthogonal to the first horizontal direction. The redox battery system according to claim 11.

14. The second subset of the redox battery is stacked in the vertical direction and a second horizontal direction orthogonal to the first horizontal direction. The redox battery system according to claim 13.

15. The plurality of redox batteries are vertically stacked and horizontally stacked in a second horizontal direction. When viewed from the stacking direction of the cells, the plurality of redox batteries form an array including a plurality of rows of redox batteries extending in the second horizontal direction and a plurality of columns of redox batteries extending in the vertical direction. The redox battery system according to claim 11.

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