Patent Publication Number: US-2022216496-A1

Title: Segmented frames for redox flow batteries

Description:
This application is being filed on 31 Aug. 2018, as a PCT International patent application, and claims priority to U.S. Provisional Patent Application No. 62/553,631, filed Sep. 1, 2017, the disclosure of which is hereby incorporated by reference herein in its entirety. 
    
    
     INTRODUCTION 
     The rechargeable flow battery (i.e. a redox flow battery) stores chemical energy in electrolyte solutions that contain electro-active elements. Conversion of this chemical energy to electrical energy may be captured and used for the purposes of powering a variety of devices and/or delivered to a power grid. 
     A typical rechargeable flow battery will have one or more cells. The cell will have an anolyte solution portion and a catholyte solution portion. These portions are separated by a membrane. Reservoirs containing additional anolyte and catholyte solutions are fluidically coupled to the anolyte portion and catholyte portion of the cell, respectively. As each electrolyte solution is circulated through its respective portion of the cell, the membrane allows for proton exchange between the anolyte solution and the catholyte solution. A current collector (e.g., an electrode) transfers the energy associated with the electron exchange between the anolyte and the catholyte to or from a power source depending on whether the redox-flow battery is being charged or discharged. 
     Current redox flow technology is limited by several issues. For example, membrane fouling, cross contamination of electrolyte solutions, electrical shunt paths, and increased fluid resistance. Additionally, preventing cross contamination of electrolyte solutions between cells and between the portions of a cell while reducing manufacturing costs continues to be challenging with current redox flow technology. 
     It is with respect to these and other considerations that aspects of the technology have been disclosed. Also, although relatively specific problems have been discussed, it should be understood that the technology disclosed herein should not be limited to solving the specific problems identified in the background or the disclosure. 
     Redox Flow Battery 
     Aspects of the technology relate to a redox flow battery with a cell plate and a frame, together which form a frame plate assembly. In embodiments, multiple frame plate assemblies are stacked together to form a cell stack. The cell plates are fluidically coupled to the frame of the frame plate assembly. In aspects of the technology, the frame may be segmented with two or more component so as to increase the flatness and decrease the manufacturing tolerances for each frame component. As such, the number of frame plate assemblies that may be stacked together is increased while reducing uneven and/or bulging cell stacks. This, in aspects, increasing cell stack and redox-flow battery system efficiencies. Additionally, the technology described herein may increase the cell stack density, which may increase the cell stack heat exchange coefficient and thermal management characteristics in embodiments. 
     The cell stack is fluidically coupled to a reservoir, in aspects, using manifold inserts (e.g., piping) to provide electrolyte solutions from a cell reservoir to the cell stack. In aspects of the technology, the frame may house an electrolyte pathway which feeds and/or returns electrolytes from a frame channel to a cell plate. Frame channels across frame plates in a cell stack may align to form a combined channel, which channel may feed multiple cell plates of the cell stack. 
     These and various other features as well as advantages that characterize the systems and methods described herein will be apparent from a reading of the following detailed description and a review of the associated drawings. Additional features are set forth in the description which follows. Also, additional features t will be apparent from the description or may be learned by practice of the technology. The benefits and features of the technology will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Non-limiting and non-exclusive embodiments are described with reference to the following figures. 
         FIG. 1  illustrates an example redox flow battery environment in which aspects of the technology may be implemented. 
         FIG. 2  illustrates a schematic perspective view of an example cell stack system. 
         FIGS. 3A and 3B  illustrate example electrolyte pathways between multiple frame plate assemblies of a redox cell stack. 
         FIG. 4  illustrates a schematic view of an example frame plate assembly. 
         FIG. 5  illustrates a perspective view of another example frame plate assembly. 
         FIG. 6  illustrates an exploded view of the frame plate assembly shown in  FIG. 5 . 
         FIG. 7  illustrates a perspective view of an example frame segment of the frame plate assembly shown in  FIG. 5 . 
         FIG. 8A-8D  illustrate enlarged detail views of the frame segment shown in  FIG. 7 . 
         FIG. 9  illustrates a perspective view of another example frame segment that may be used with the frame plate assembly shown in  FIG. 5 . 
         FIGS. 10A-10D  illustrate various views of an example radial connector insert that may be used with the frame segment shown in  FIG. 9 . 
         FIGS. 11A-11D  illustrate various views of an example radial spacer insert that may be used with the frame segment shown in  FIG. 9 . 
         FIG. 12  illustrates a flowchart of an example method of assembling a frame plate assembly. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates an example of a redox-flow battery system  100  having a cell stack  102 . As illustrated, the redox-flow battery system  100  also includes a catholyte reservoir  104  holding a catholyte solution  106  and an anolyte reservoir  108  holding an anolyte solution  110 . A first pumping mechanism  112  is used to circulate the catholyte solution  106  from the catholyte reservoir  104  to the cell stack  102  and back via a catholyte pathway  114  and a second pumping mechanism  116  is used to circulate the anolyte solution  110  from the anolyte reservoir  108  to the cell stack  102  and back via a anolyte pathway  118 . Additionally, a catholyte current collector  120  and an anolyte current collector  122  are present. 
     In an embodiment, the redox-flow battery system  100  may be one of a vanadium-vanadium redox flow battery, a polysulfide bromide battery, an iron-chromium battery, or a manganese-vanadium redox flow battery. In an embodiment where the redox-flow battery system  100  is a vanadium redox flow battery, the catholyte solution  106  is substantially V 5+  in the charged state. Additionally, where the battery is in the charged state, the anolyte solution  110  is substantially V 2+ . In an embodiment where the system is a polysulfide bromide battery, the catholyte solution  106  is substantially sodium tribromide, and the anolyte solution  110  is substantially sodium disulfide in a charged state. In an embodiment where the system is an iron-chromium battery, the catholyte solution  106  is substantially Fe 3+ , and the anolyte solution  110  is substantially Cr 2+  in a charged state. In an embodiment where the system is a manganese-vanadium battery, the catholyte solution  106  is substantially Mn 3+ , and the anolyte solution  110  is substantially Vn 2+  in a charged state. It will be appreciated that the technologies described herein may be used with other redox-flow battery chemistries. 
     The cell stack  102  may include a plurality of cell plates as described in further detail below. Each cell plate of the cell stack  102  facilitates the exchange of electrical energy between the catholyte and the electrolyte during a charge/discharge cycle. Each cell plate, which includes a proton exchange membrane positioned between the two electrodes, allows the transfer of a proton from the catholyte to the anolyte during the discharge cycle, and a current collector facilitates the exchange of an electron from the anolyte to the catholyte during the discharge cycle. The cells stack may have cells that are in series or are in parallel. While only one cell stack  102  is illustrated, it will be appreciated that multiple cell stacks may be electrically coupled together in either series or parallel. 
     In an embodiment, one or more mechanical pumps are used as the first pumping mechanism  112  and the second pumping mechanism  116  to circulate the catholyte solution  106  and the anolyte solution  110 , respectively. Other methods and/or equipment may be used to provide circulation of the catholyte solution  106  between the catholyte reservoir  104  and the cell stack  102 , as well as to circulate the anolyte solution  110  between the anolyte reservoir  108  and the cell stack  102  as required or desired. 
     As illustrated, the catholyte reservoir  104  is fluidically coupled to the cell stack  102  by the catholyte pathway  114  (which may be a tube, a pipe, or the like), and the anolyte reservoir  108  is fluidically coupled to the cell stack  102  by the anolyte pathway  118  (which may be a tube, a pipe, or the like). It will be appreciated that one or more cell stacks  102  may be configured to be fluidically coupled together in series and/or parallel as required or desired and as described further below. 
       FIG. 2  illustrates a schematic-perspective view of an example cell stack system  200 . In aspects of the technology, the cell stack system  200  includes a plurality of frame plate assemblies  201 . The plurality of frame plate assemblies  201  includes a first frame plate assembly  202 , a second frame plate assembly  204 , and a third frame plate assembly  206 , up to an n th  or last frame plate assembly  208 . The plurality of frame plate assemblies  201  may have any number of frame plate assemblies as required or desired. As illustrated, each frame plate assembly, such as the first frame plate assembly  202 , the second frame plate assembly  204 , the third frame plate assembly  206 , and the last frame plate assembly  208  are shaped as similar sized rectangular prisms. In alternative examples, each frame plate assembly  204 ,  206 ,  206 ,  208  may have any other shape, or size, or differing shapes/sizes that enables the cell stack system  200  to function as described herein. 
     It will be appreciated that each frame plate assembly has a front face and a back face as described further below. For example, the first frame plate assembly  202  has a front face  210  and an opposite back face  212 . In aspects of the technology, the front face  210  and the back face  212  are substantially perpendicularly planar. In aspects of the technology, the back face  212  of the first frame plate assembly  202  is disposed proximate to a front face of the second frame plate assembly  204 , a back face of the second frame plate assembly  204  is disposed proximate to a front face of the third frame plate assembly  206 , and so on. Each frame plate assembly includes, in embodiments, a frame and a cell plate (e.g., a monopolar or bipolar plate comprising carbon paper electrodes and a membrane), which the cell plate is used to facilitate the charging/discharging of a redox flow battery. Various embodiments of the frame plate assembly are discussed in further detail below with references to  FIGS. 4-11 . 
     The plurality of frame plate assemblies  201  may be coupled together using one or more framing members  216 . For example, the back face  212  of the first frame plate assembly  202  may be coupled to the front face of the second frame plate assembly  204  using one or more framing members  214  that also couples the back face of the second frame plate assembly  204  to the front face of the third frame plate assembly  206 , and so on. 
     Coupling may occur through a variety of means. As illustrated, the plurality of frame plate assemblies  201  are coupled together using framing rods  216 . The framing rods  216  orthogonally penetrate the front face  210  and the back face  212  of the first frame plate assembly  202 . The framing rod  216  is a type of framing member  216 . In aspects of the technology, the framing members  216  may be rods, plates, walls, shafts, and/or any item capable of coupling each of the plurality of frame plate assemblies  201  to adjacent frame plate assemblies. In aspects of the technology, the first frame plate assembly  202  has a plurality of bores operable to receive the plurality of framing rods  216 . Additionally, fasteners  218  couple the framing rods  216  to the first frame plate assembly  202 . Though the illustrated fasteners  218  are bolts that couple to a threaded end of the framing rods  216 , it will be appreciated that other fastening technology is contemplated. Thus, the fasteners  218  are tightened to form a robust coupling, via pressure, with adjacent framing members in the cell stack. 
     Similarly, the second frame plate assembly  204  has a plurality of bores, which bores may be aligned with the bores of the first frame plate assembly  202  such that the plurality of framing rods  216  may be received. In alternative embodiments, other framing members may be used. The other frame plate assemblies in the plurality of frame plate assemblies  201  may have similarly aligned bores to receive the framing rods  216 . As such, each frame plate assembly of the plurality of frame plate assemblies  201  may couple to the adjacent frames by sliding over the framing rods  216 . 
     As illustrated, the plurality of framing rods  216  may be secured to a first mounting plate  220 . The first mounting plate  220  may cap the top of the plurality of frame plate assemblies  201 . That is, the first mounting plate  220  may be disposed on the front face  210  of the first frame plate assembly  202 . Similarly, a second mounting plate  222  may cap the bottom of the plurality of frame plate assemblies  201 . That is, the second mounting plate  222  may be disposed on the back face of the last frame plate assembly  208  and opposite the first mounting plate  220 . 
     Additionally illustrated in  FIG. 2  is electrolyte piping  224  and  226 . The electrolyte piping fluidically couples an electrolyte reservoir, such as an anolyte reservoir or catholyte reservoir, to the plurality of frame plate assemblies  201 . As illustrated, the electrolyte piping  224  and the electrolyte piping  226  penetrate through the first frame plate assembly  202  through an angle orthogonal to the front face  210  and the back face  212 . The electrolyte piping  224  may deliver and/or return the electrolyte solution to each frame plate assembly in the plurality of frame plate assemblies  201 . The electrolyte piping  224 ,  226  may be a separate component, as illustrated, or may be formed piecewise through the stacking and aligning channels (e.g., bores) of the plurality of frame plate assemblies  201  and as described further below. 
     The reservoirs may be the same as or similar to the electrolyte reservoirs described with references to  FIG. 1 . In aspects of the technology, each frame plate assembly is designed with a pathway such that an electrolyte solution may pass from the frame of a frame plate assembly to a cell plate of the frame plate assembly, and then to another frame plate assembly, and then ultimately to an electrolyte reservoir. 
       FIG. 3A  illustrates an example catholyte pathway between multiple frame plate assemblies of a redox cell stack  300 . In aspects of the technology, a catholyte solution  302  enters a first frame plate assembly  304 . The first frame plate assembly  304  may have a frame with a variety of channels, vias, membranes, porous material, and/or pathways to direct the flow of the catholyte solution  302  across a portion of the backside of the first frame plate assembly  304 . In aspects, flow may be directed through a frame of the first frame plate assembly  304  into a cell portion of the first frame plate assembly  304 . In aspects of the technology, flow into the cell portion of the first frame plate assembly  304  is directed across a backside of the membrane of the cell portion of the first frame plate assembly  304 . Flow of the catholyte solution may be directed such that a laminar sheet-flow occurs across the backside of a membrane of a cell portion of the first frame plate assembly  304 . 
     The catholyte solution  302  then proceeds to enter a second frame plate assembly  306 . In aspects of the technology, the frame of the second frame plate assembly includes channels, vias, membranes, porous materials, and or/pathways to direct the flow of the catholyte solution  302  across a portion of a backside of the second frame plate assembly. Flow of  302  may enter and exit the second frame plate assembly  306  in a similar manner as the first frame plate assembly  304 . In aspects, flow may be directed through a frame of the second frame plate assembly  306  into a cell portion of the second frame plate assembly. In aspects of the technology, flow into the cell portion of the second frame plate assembly  306  is directed across a backside of the membrane of the cell portion of the second frame plate assembly  306 . Flow of the catholyte solution  302  may be directed such that a laminar sheet-flow occurs across the backside of a membrane of the cell portion of the second frame plate assembly  306 . 
     This pattern of flow of the catholyte solution  302  may proceed to a plurality of other frame plate assemblies, including a third frame plate assembly  308 , and/or to a reservoir. Flow of  302  may enter and exit the third frame plate assembly  308  in a similar manner as the first and second frame plate assembles  304 ,  306 . In aspects of the technology, the catholyte solution  302  enters a frame plate assembly and flow may be directed such that the catholyte solution flows down a backside portion of the membrane of a cell portion of a plate assembly. 
     Illustrated in  FIG. 3B  is a flow of an anolyte solution  310 . An anolyte solution may travel from the first frame plate assembly  304  to the second frame plate assembly  306 . The first frame plate assembly  304  may have a frame with a variety of channels, vias, membranes, porous material, and/or pathways to direct the flow of the anolyte solution  310  across a portion of the front side of the first frame plate assembly  304 . In aspects, flow may be directed through a frame of the first frame plate assembly  304  into a cell portion of the first frame plate assembly  304 . In aspects of the technology, flow into the cell portion of the first frame plate assembly  304  is directed across a front side of the membrane of the cell portion of the first frame plate assembly  304 . Flow of the anolyte solution  310  may be directed such that a laminar sheet flow occurs across the front side of the membrane of the cell portion of the first frame plate assembly  304 . 
     The anolyte solution  310  then proceeds to enter the second frame plate assembly  306 . Flow of the anolyte solution  310  may enter and exit the second frame plate assembly  306  in a similar manner as the first frame plate assembly  304 . In aspects of the technology, the frame of the second frame plate assembly  306  includes channels, vias, membranes, porous materials, and or/pathways to direct the flow of the anolyte solution  310  across a front side of the second frame plate assembly  306 . In aspects, flow may be directed through a frame of the second frame plate assembly  306  in a cell portion of the second frame plate assembly  306 . In aspects of the technology, flow into the cell portion of the second frame plate assembly  306  is directed across a front side of the membrane of the cell portion of the second frame plate assembly  306 . Flow of the anolyte solution  310  may be directed such that a laminar sheet flow occurs across the front side of a membrane of the cell portion of the second frame plate assembly  306 . 
     This pattern of flow of the anolyte solution  310  may proceed to a plurality of other frame plate assemblies, including a third frame plate assembly  308 , and/or to a reservoir. Flow of  310  may enter and exit the third frame plate assembly  308  in a similar manner as the first and second frame plate assembles  304 ,  306 . In aspects of the technology, the anolyte solution  310  enters a frame plate assembly and flow may be directed such that the anolyte solution flows down a frontside portion of the membrane of a cell portion of a plate assembly. 
     In aspects of the technology, the catholyte solution  302  flows through a shared manifold (not shown). That is, in an example, each cell includes a flow path that enables an electrolyte to flow from an inlet to an outlet, and each frame plate assembly has an internal manifold insert, such as the electrolyte piping (shown in  FIG. 2 ). Thus, stacking multiple frame plate assemblies may create a common supply and return manifolds via the electrolyte piping. This internal manifold supplies and returns electrolyte to the individual cells in a parallel flow configuration, in example embodiments. Other configurations are contemplated. 
       FIG. 4  illustrates a schematic view of an example frame plate assembly  400 . The frame plate assembly  400  includes a frame  402  coupled in fluidic communication to a cell plate  404 . In this example, the frame  402  is substantially square and has a length  406  that is approximately between 15 inches and 20 inches. While the cell plate  404  is also substantially square and has a length  408  that is approximately between 8 inches and 12 inches. As such, the frame  402  has a relatively large cross sectional length compared to the cell plate  404 . In aspects of the technology, increasing flatness (defined as change in height over change in length) for a cell plate  404  is desirable to ensure a robust seal among cell plates in a cell stack. The frame  402  flatness is desirable, in aspects, to the extent the flatness of the frame  402  affects the sealing between cell plates. Thus, by reducing the frame plate assembly  402  flatness  412  effect on the sealing ability of the cell plate  402 , the frame  402  flatness  412  manufacturing tolerance may be reduced. (It will be appreciated that some level of flatness is desirable to allow the frame  402  to be coupled to framing members to form a cell stack). 
     The frame plate assembly  400  may include a floating frame plate assembly as described in U.S. Patent Application No. 62/518,953 filed Jun. 13, 2017 and entitled “FLOATING FRAME PLATE ASSEMBLY,” the disclosure of which is hereby incorporated by reference herein in its entirety. For example, the cell plate  404  may be manufactured with a relatively low tolerance and high flatness  410  of at least 0.0005 inches per linear 1 inch. In additional or alternative examples, the flatness  410  may be at least 0.0005 millimeters (mm) per 1 mm. While, the frame  402  may be manufactured with a relatively higher tolerance and lower flatness  412  of greater than 0.005 inches per linear 1 inch. In additional or alternative examples, the flatness  412  may be greater than 0.005 mm per linear 1 mm. By utilizing the floating frame plate assembly, the number of frame plate assemblies  400  stacked together in the cell stack may be increased because the frame  402  may move relative to the cell plate  404 . As such, the undesirable results from higher manufacturing tolerances and lower flatness of the frame  402  are reduced within the system. 
       FIG. 5  illustrates a perspective view of another example frame plate assembly  500 .  FIG. 6  illustrates an exploded view of the frame plate assembly  500 . Referring concurrently to  FIGS. 5 and 6 , the frame plate assembly  500  includes a frame assembly  502  coupled in fluidic communication to a cell plate  504 . For the example, the cell plate  504  is a substantially rectangular prism with a front face  506  and an opposite back face  508 . The cell plate  504  also includes four side walls  510  defining a perimeter  512  of the cell plate  504 . Each side wall  510  includes a center flange  514  extending along the length of the side wall and an orifice  516  defined therein which may channel a flow of electrolytes therethrough. 
     The frame assembly  502  includes two or more interlocking frame segments  518  that surrounds the cell plate perimeter  512 . The frame segments  518  may be manufactured out of a variety of materials, such as a rigid or semi-rigid plastic. In some examples, the frame segments  518  may be manufactured out of electrical isolating and heat conducting material. In this example, the frame assembly  502  includes four frame segments  518 A,  518 B,  518 C, and  518 D. However, in alternative examples, the frame assembly  502  may include any number of frame segments that enable the frame plate assembly  500  to function as described herein. For example, the frame assembly  502  may include two, three, five, or more segments. By modulating the frame assembly  502 , each frame segment  518  has a lower surface area such that manufacturing tolerances may be decreased and flatness may be increased. This may be so because, for some manufacturing processes, maintaining flatness across a larger distance is more costly and/or time consuming. Accordingly, having a smaller distance upon which to maintain a flatness may allow for a lower overall manufacturing tolerance of the frame plate assembly  500  while still achieving the same or better flatness levels. This may in turn enable a greater number of frame plate assemblies to be stacked within the cell stack. Additionally, the cell stack increases in density so as to increase its heat exchange coefficient and thermal management characteristics. 
       FIG. 7  illustrates a perspective view of the frame segment  518 .  FIG. 8A-8D  illustrate enlarged detail views of the frame segment  518 . Referring concurrently to  FIGS. 7-8D  and continued reference to  FIGS. 5 and 6 , each frame segment  518  includes a body  520  having a first end  522  and a second end  524 . The first end  522  includes an extension connection element  526  (shown in detail in  FIG. 8A ) and the second end  524  includes a receiver connection element  528  such that two adjacent frame segments  518  may interlock with each other. For example, the extension connection element  526  may include two circular extensions  530  defined on a planar extension  531  having a reduced thickness. The receiver connection element  528  may include two corresponding circular apertures  532  defined on a planar extension  533  having a reduced thickness. For example, the first end  522  of one frame segment  518 A may be received within the second end  524  of an adjacent frame segment  518 B. The connection between frame segments may be a snap-fit connection, friction-resistance connection, or any other connection type that interlocks the frame segments  518  together. 
     Each frame segment  518  also includes a frame channel  534  (shown in detail in  FIG. 8D ) defined in the body  520  and a plug  536  (shown in detail in  FIG. 8C ) extending from the body  520 . An electrolyte pathway  537  extends between the frame channel  534  and the plug  536  such that a flow of electrolytes may be channeled between the cell plate  504  and the frame channel  534 . The frame channel  534  may be further defined within a sealing element  538  that extends outward from the body  520 . The sealing element  538  is configured to mate with an adjacent sealing element  538  such that an elongate frame channel is formed through the cell stack for channeling the electrolyte flow to and from the reservoirs as described above. For example, a recess  540  may be defined on one end of the sealing element  538  while a corresponding extension (not shown) is defined on the opposite end of the sealing element  538  such that adjacent sealing elements  538  may be mated and sealed together. Along an annular surface  542  of the frame channel  534 , a circumferential opening  544  may be defined therein. A first end  546  of the electrolyte pathway  537  is coupled in fluidic communication with the opening  544  such that the electrolyte flow may be channeled into the electrolyte pathway  537 . 
     The plug  536  is disposed at a second end  548  of the electrolyte pathway  537  and extends from the body  520 . In the example, the plug  536  includes an opening  550  extending therethrough and the plug  536  is sized and shaped to be received by a corresponding orifice  516  of the cell plate  504 . For example, the plug  536  is substantially cylindrical and includes one or more annular ribs  552  such that a sealed fluidic connection is made between the frame segment  518  and the cell plate  504 . In some examples, the plug  536  and/or the second end  548  may be flexible so as to enable the cell plate to float and move relative to the frame assembly  502  and further reduce the impact of the frame segment manufacturing tolerances. In one example, the cell plate  504  may float approximately 0.6 inches with respect to the frame assembly  502 . 
     In the example, the electrolyte pathways  537  facilitate channeling an electrolyte flow from an electrolyte reservoir to the cell plate  504  for operation of the system as described above. For example, one or more of the electrolyte pathways  537  may be a catholyte supply pathway that delivers a catholyte solution to the cell plate  504 , a catholyte return pathway that returns a catholyte solution to a catholyte reservoir and/or other frame plate assemblies, an anolyte supply pathway that delivers an anolyte solution to the cell plate  504 , and/or an anolyte return pathway that returns an anolyte solution to an anolyte reservoir and/or other frame plate assemblies. 
     The electrolyte pathways  537  may be formed by a variety of methods. In the example, the electrolyte pathways  537  are integral and defined within the body  520 . As such the plug  536 , the pathways  537 , and the body  520  are unitary. The integral pathways may be formed by gas assist or thermal injection molding, through additive manufacturing processes, or any other manufacturing process. In alternative examples, the electrolyte pathways  537  may be a separate component and include a substantially inert tubing that is disposed within an electrolyte cutaway defined within the body  520 . The tubing may be polyurethane, polypropylene, or any other inert material. 
     In further alternative examples, the electrolyte pathways  537  may include electrolyte shunt pathways  554 . The shunt pathways  554  extend for a predetermined length so as to control the electrical resistance and the fluid resistance of the electrolyte flow therein. For example, in certain applications, it may be desirable to increase electrical resistance to prevent shunt currents within the frame segment  518  and/or across frame segments within a cell stack. Additionally, for certain applications, it may be desirable to decrease fluid resistance within the frame segment  518  and/or across frame segments within a cell stack. In aspects of the technology, electrical resistance is controlled by changing various elements of the frame assembly  502 . For example, the material of the electrolyte shunt pathways  554 , the length of the electrolyte shunt pathways  554 , the size and shape of the electrolyte shunt pathways  554  (e.g., diameter of the electrolyte shunt pathway openings) and the material, the size, and the shape of the plug  536  may alter the electrical resistance in the frame assembly  502 . 
     Adjacent to the plug  536 , each frame segment  518  may also include a plate connector  556  (shown in detail in  FIG. 8B ) extending from the body  520 . The plate connector  556  is configured to receive at least a portion of the side wall  510  of the cell plate  504  so as to couple the frame assembly  502  to the cell plate  504  and restrict movement and flexing of sealing surfaces (e.g., between the plug  536  and the orifice  516 ) to reduce electrolyte leakage. As such, when the frame assembly  502  moves relative to the cell plate  504  the plate connector  556  directs the flex stresses into the body  520  of the frame segment  518  and/or the electrolyte pathway tubing. 
     For example, the plate connector  556  includes two or more alternating flanges  558  that define a recess  560  therebetween, which receives the corresponding cell plate flange  514 . In alternative examples, any other connection element may be used that enables the cell plate  504  to be coupled to the frame segment  518  as described herein. In additional examples, the cell plate  504  may be segmented into two or more members and each frame segment  518  may be bonded to the corresponding cell plate member in order to facilitate forming the frame plate assembly  500 . 
     Additionally illustrated are one or more bores  562  defined within each frame segment  518 . The bores  562  are circular cut-outs adapted to receive framing members, such as rods, and as described above. 
       FIG. 9  illustrates a perspective view of another example frame segment  600  that may be used with the frame plate assembly  500  (shown in  FIG. 5 ). Similar to the example described above, the frame segment  600  includes a body  602  having an extension connection element  604 , a receiver connection element  606 , a plug  608 , and an electrolyte pathway  610  or shunt pathway  612 . However, in this example, a frame channel area  614  is defined in the body  602 . The frame channel area  614  is sized and shaped to receive a removable corner member (shown in  FIGS. 10 and 11 ) so as to form all or part of the frame channel within the frame segment. One advantage of having a removable corner member form all or a part of a frame channel is it may allow for easier manufacturing. In use, frame channels of one frame plate assembly may couple to frame channels of another, adjacent frame plate assembly. As such, it is desirable, in aspects, to have the frame channels form a robust seal with the other frame channels. One reason is that a robust seal will aid in reducing leakage of the electrolyte solution as the electrolyte solution flows from frame plate assembly to frame plate assembly. To achieve a robust seal, it is beneficial, in aspects, to manufacture each frame channel to couple robustly with its adjacent frame channel. In some aspects, this means manufacturing complementary geometries between two adjacent frame channels. For example, where two frame channels couple together via a substantially planar face having a sealing element, such as an o-ring, the degree to which both frame channel&#39;s coupling surfaces are flat may aid in maintaining a robust seal. Having the removable corner members form all or a part of the frame channel may allow for the removable corner members to be manufactured at high precision levels without necessarily needing to have the rest of the frame segment body  602  be at such a high precision level. For some manufacturing processes, this may decrease the overall manufacturing cost and complexity. Examples of the removable corner members are discussed further below. 
       FIGS. 10A-10D  illustrate various views of an example radial connector insert  700  that may be used with the frame segment  600  (shown in  FIG. 9 ). In particular,  FIG. 10A ,  FIG. 10B ,  FIG. 10C , and  FIG. 10D  illustrate front, side, perspective, and back views, respectively, of the removable corner member that is the radial connector insert  700 . The radial connector insert  700  may be used to allow an electrolyte solution to flow from one frame channel of a first frame plate assembly to a second frame channel of an adjacent, second frame plate assembly. The radial connector insert  700  includes a rectangular prism insert body  702 . In other aspects, the body  702  may be any other shape as required or desired. A connection element  704  extends from the body  702  which, in operation, fluidically couples the insert  700  to an electrolyte pathway. 
     The connection element  704  extends orthogonally from a first wall  706  of the body  702 . In aspects of the technology, the connection element  704  may be a tube with a press-fit, snap-fit, threaded connection, or any other connection such that the connection element resiliently engages with a frame end of an electrolyte pathway, such as an anolyte or catholyte pathway described with more detail above. 
     In aspects, this allows a frame channel  708  defined in the body  702  to be in fluidic communication with one or more cell plates. For example, in aspects, the connection element  704  has a pathway  710  defined therein that fluidically couples the frame channel  708  to the electrolyte pathway of a frame plate assembly when in operation. Specifically, the frame channel  708  may be defined by an annular wall  712  to which the pathway  710  extends to. 
     The radial connector insert  700  includes the frame channel  708  that allows, in aspects, an electrolyte to flow from one frame plate assembly to another frame plate assembly and/or to an electrolyte reservoir. Indeed, each radial connector insert  700  may have a sealing element  714  that protrudes from a front face  716  of the body  702  and may be adapted to couple to a back face  718  of an adjacent removable corner member. As illustrated, the sealing element  714  protrusion has a face  720  that may be substantially planar. In some aspects, the face  720  may couple to an o-ring or other material to aid in forming a robust seal with an adjacent frame channel (the adjacent frame channel may be another removable corner member). 
     An attachment element  722  may correspond to a receiving element (not shown) of a frame segment, such as the frame segment described with reference to  FIG. 9 . For example, the attachment element  722  may be a tongue that protrudes from a side wall of the radial connector insert  700  and inserts into a corresponding slot of the frame segment. In other aspects, other attachment elements may be used, such as snap fittings. This may allow the radial connector insert  700  to be removably inserted into the body of the frame segment. 
       FIGS. 11A-11D  illustrate various views of an example radial spacer insert that may be used with the frame segment shown in  FIG. 9 . In particular,  FIG. 11A ,  FIG. 11B ,  FIG. 11C , and  FIG. 11D  illustrate front, side, perspective, and back views, respectfully, of a removable corner member that is a radial spacer insert  800 . The radial spacer insert  800  may be used to allow an electrolyte solution to flow from one frame channel of a first frame plate assembly to a second frame channel of a second frame plate assembly without being channeled into an electrolyte pathway. As illustrated, the radial spacer insert  800  includes a rectangular prism insert body  802 . In other aspects, the body  802  may be any other shape as required or desired. 
     As illustrated, the radial spacer insert  800  has a frame channel  804  defined in the body  802  that allows, in aspects, an electrolyte to flow from one frame plate assembly to another, adjacent frame plate assembly. Indeed, the radial spacer insert  800  may have a sealing element  806  that protrudes from a front face  808  of the body  802  and may be adapted to couple to a back face  810  of an adjacent removable corner member. As illustrated, the sealing element  806  is a protrusion that has a face  812  that may be substantially planar. In some aspects, the face  812  of the sealing element  806  may couple to an o-ring or other material to aid in forming a robust seal with an adjacent frame channel (part or all of the adjacent frame channel may be another removable corner member). 
     An attachment element  814  may correspond to a receiving element (not shown) of a frame segment, such as the frame segment described with reference to  FIG. 9 . For example, the attachment element  814  may be a tongue that protrudes from a side wall and inserts into a corresponding slot of the frame segment. In this example, the attachment element  814  may extend substantially around the perimeter of the body  802  because electrolyte flow does not need to be channeled between the frame channel  804  and the electrolyte pathways. In other aspects, other attachment elements may be used, such as snap fittings. This may allow the radial spacer insert  800  to be removably inserted into the body of the frame segment. 
       FIG. 12  illustrates a flowchart of an example method  900  of assembling a frame plate assembly that includes a cell plate and a frame assembly. The method includes forming at least two frame segments of the frame assembly (operation  902 ), coupling each frame segment of the at least two frame segments in fluidic communication to the cell plate (operation  904 ); and interlocking adjacent frame segments such that the frame assembly at least partially surrounds a perimeter of the cell plate (operation  906 ). 
     In this example, utilizing frame segments improves manufacture of the frame assembly components to desired predetermined tolerances and also reduces material use. By reducing the size of the frame segments, rapid cycling injection molding (operation  908 ) may be used with or without post machining (operation  910 ). In other examples, compression molding (operation  912 ) may be used for component manufacturing. In additional examples, component manufacturing may include molding, gas assist, additive manufacturing (operation  914 ), or any other process. 
     In some examples, the method  900  further includes stacking two or more frame plate assemblies (operation  916 ), and coupling each frame plate assembly of the two or more frame plate assemblies in fluidic communication, wherein the stack of two or more frame plate assemblies form at least a portion of the redox cell stack (operation  918 ). In other examples, the method further  900  includes forming at least one removable corner member (operation  920 ) and coupling the at least one removable corner member to each frame segment (operation  922 ). 
     The description and illustration of one or more embodiments provided in this application are not intended to limit or restrict the scope of the invention as claimed in any way. The embodiments, examples, and details provided in this application are considered sufficient to convey possession and enable others to make and use the best mode of claimed invention. The claimed invention should not be construed as being limited to any embodiment, example, or detail provided in this application. Regardless of whether shown and described in combination or separately, the various features (both structural and methodological) are intended to be selectively included or omitted to produce an embodiment with a particular set of features. Having been provided with the description and illustration of the present application, one skilled in the art may envision variations, modifications, and alternate embodiments falling within the spirit of the broader aspects of the general inventive concept embodied in this application that do not depart from the broader scope of the claimed invention 
     EXAMPLE EMBODIMENTS 
     For reasons of completeness, various aspects of the disclosure are set out in the following numbered clauses: 
     Clause 1. A frame plate assembly for a redox cell stack, the frame plate assembly comprising: a cell plate; and a frame assembly coupled in fluidic communication to the cell plate, wherein the frame assembly is configured to at least partially surround a perimeter of the cell plate and to channel at least one flow of electrolytes to the cell plate, the frame assembly comprising at least two frame segments, wherein each frame segment of the at least two frame segments comprises: a body having a first end and a second end; an extension connection element disposed at the first end; and a receiver connection element disposed at the second end, wherein two adjacent frame segments are configured to interlock via the extension connection element being received in the receiver connection element. 
     Clause 2. The frame plate assembly of Clause 1, wherein the frame assembly comprises three frame segments. 
     Clause 3. The frame plate assembly of Clause 1, wherein the frame assembly comprises four frame segments. 
     Clause 4. The frame plate assembly of Clause 1, wherein each frame segment further comprises: at least one frame channel defined in the body and configured to channel the at least one flow of electrolytes therethrough; at least one plug extending from the body and configured to be at least partially received in the cell plate; and at least one electrolyte pathway defined in the body and extending between the at least one frame channel and the at least one plug such that the at least one flow of electrolytes is channeled between the cell plate and the at least one frame channel. 
     Clause 5. The frame plate assembly of Clause 4, wherein the at least one electrolyte pathway comprises an electrolyte shunt pathway. 
     Clause 6. The frame plate assembly of Clause 4, wherein the at least one plug is unitary with the body. 
     Clause 7. The frame plate assembly of Clause 4, wherein the at least one frame channel is defined by a sealing element extending from the body. 
     Clause 8. The frame plate assembly of Clause 4, wherein the at least one frame channel is defined in a removable corner member configured to removably attach to the body. 
     Clause 9. The frame plate assembly of Clause 1, wherein each frame segment of the at least two frame segments further comprises at least one plate connector configured to couple the frame segment to the cell plate. 
     Clause 10. The frame plate assembly of Clause 1, wherein the cell plate comprises at least two plate members, and wherein each frame segment of the at least two frame segments is bonded to the corresponding plate member. 
     Clause 11. The frame plate assembly of Clause 1, wherein the cell plate is configured to float about 0.6 inches with respect to the frame assembly. 
     Clause 12. A method of assembling a frame plate assembly for a redox cell stack, the frame plate assembly including a cell plate and a frame assembly, the method comprising: forming at least two frame segments of the frame assembly; coupling each frame segment of the at least two frame segments in fluidic communication to the cell plate; and interlocking adjacent frame segments such that the frame assembly at least partially surrounds a perimeter of the cell plate. 
     Clause 13. The method of Clause 12, wherein forming the at least two frame segments further includes injection molding each frame segment. 
     Clause 14. The method of Clause 13 further comprising post machining each frame segment. 
     Clause 15. The method of Clause 12, wherein forming the at least two frame segments further includes compression molding each frame segment. 
     Clause 16. The method of Clause 12, wherein forming the at least two frame segments further includes additively manufacturing each frame segment. 
     Clause 17. The method of Clause 12 further comprising: stacking two or more frame plate assemblies; and coupling each frame plate assembly of the two or more frame plate assemblies in fluidic communication, wherein the stack of two or more frame plate assemblies form at least a portion of the redox cell stack. 
     Clause 18. The method of Clause 12 further comprising: forming at least one removable corner member; and coupling the at least one removable corner member to each frame segment.