Improved shunt manifold and equipment block

Abstract

In a first aspect the invention comprises a shunt manifold assembly for a redox flow battery comprising: at least a first shunt sub-unit for electrolyte, the first shunt sub-unit comprising: a first portion of a first distribution channel; a first branch channel providing a fluid connection between the first portion of the first distribution channel and an associated first cell sub-stack; the first branch channel having a serpentine flow path; the first portion of the first distribution channel and the first branch channel providing a first flow path for fluid in the first shunt sub-unit, the first flow path being generally or substantially planar. In a further aspect the invention is a redox flow battery system comprising at least one battery module, one or more or each battery module comprising: (i) a first cell stack; (ii) a first shunt manifold assembly associated with the first cell stack, the first shunt manifold assembly configured to manage electrolyte flow for the first cell stack; further wherein the first cell stack and the first shunt manifold assembly associated with the first cell stack are configured to be removably mounted within the battery module.

Description

[0001] Improved Shunt Manifold and Equipment Block

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to the methods and apparatus for use in battery systems particularly redox flow battery systems. In various aspects the invention relates to redox flow battery system(s) comprising one or more redox flow battery module(s), redox flow battery string(s), redox flow battery array(s), and set(s) of array(s). In particular, in some aspects, the invention relates to a shunt manifold assembly. In particular, in other aspects, the invention relates to an equipment block, which may comprise a shunt manifold assembly. In one or more further aspects the invention relates to methods of operating the above. The invention finds particular application in redox flow battery systems and methods but may be used with other battery systems.

[0004] BACKGROUND OF THE INVENTION

[0005] Redox flow battery systems typically comprise multiple cells connected to one another in a bipolar electrochemical cell arrangement, electrically in series, to increase output voltage. Electrochemical battery modules generate electrical power by passing electrolyte (e.g. catholyte and anolyte) through one or more of the electrochemical cells. These are usually placed in physical proximity next to one another in an arrangement referred to as a stack, or cell stack. Each cell stack is associated with at least one tank, typically at least one tank pair comprising two tanks for anolyte and catholyte, together with pipework and, typically, associated pumps that circulate electrolyte(s) from the tank(s), through the cell stack and back to the tank(s) typically in a closed system. Sometimes more than one cell stack can share a tank or pair of tanks. Together, the cell stack(s), tank(s) and associated electrolyte circulatory system are referred to as a battery module.

[0006] Any number and configuration of cells may be provided. The volume of electrolyte(s) available to the cells generally determines the energy storage capacity of the battery modules.

[0007] Typically, several battery modules are connected together in series to increase the output voltage. This is called a string. Strings of battery modules may be combined, typically in parallel, to form array(s) to provide a useful amount of power at a particular voltage level. Achieving useful voltage levels and / or power levels for grid connected systems, particularly at reasonable cost, still remains challenging. Further, reducing or avoiding losses can improve efficiency in power production.

[0008] Typically, electrochemical cells are hydraulically connected in parallel to common electrolyte(s) in a common tank, more usually in a pair of tanks (known as a tank pair), one for catholyte, one for anolyte. Where the electrolyte(s) is / are conductive, this results in shunt currents between the cells , which result in electrical losses, known as shunt losses. These losses occur because conductive paths exist (via the electrolyte) between series connected cells that are at a different electrical potentials. This difference of potentials induces currents in the electrolyte(s) conductive paths which vary with the resistivity of the conductive, fluid paths. Shunt currents can reduce cell stack lifetime, and / or can result in higher operating and / or maintenance costs.

[0009] There are a variety of strategies to reduce shunt losses, the most used is to provide artificially long channels known as ‘shunts’ between the cells and the tank(s). In cells formed as series of plates within a single cell stack, typically grouped together with one plate next to the other between a pair of end plates, these shunts (long channels) may be formed within the cell plates themselves. However, it is also advantageous to provide shunts between neighbouring cell stacks (or, indeed, between neighbouring cell substacks, which share a tank pair, in other words, to provide long channels between the input(s) and / or output(s) of cells or cell stacks / sub-stacks.

[0010] In ‘NASA Redox Cell Stack Shunt Current, Pumping Power and Cell Performance Trade-offs’ (DoE / NASA / 12726-11 NASATM-82686 February 1982), Hagedorn et al describe calculation of the extent of shunt current through a manifold to a redox flow battery in an introduction to the topic.

[0011] JPH02250269 SHIMIZU describes using long bending passages within the electrode plate frames to reduce shunt current in a flow battery.

[0012] WO0225756 TOMAZIC describes long fluid lines within the stack to reduce shunt currents in a flow battery.

[0013] WC2009025672 and US2009047570 both to HARPER describe serpentine channels in the electrolyte input and output lines as internal manifolds formed as fluid distribution plates apparently in parallel with cell plates within cell stacks.

[0014] In ‘Vanadium Redox Flow Battery Layout for Improved Efficiency’ (EESAT 2007, San Francisco, USA, 2007) SCHREIBER et al describe shunt current calculations for, and physical application of, external manifolds feeding vanadium flow stacks that are electrically connected in series. WO2014145844 and US10074859 both to KELL describe external piping loops as shunt manifolds.

[0015] WO2017006232 FASKIN describes a battery module in a container with complex shunt manifold and pipework arrangements.

[0016] It is of note that, whilst W02009025672 HARPER uses internal manifolds and WO2014145844 KELL uses external manifolds, practical challenges remain. First is cost. The known designs are complex, requiring additional components, external to cell stacks as in KELL, or specifically manufactured components as in HARPER. In either case, components are designed and sized for a predetermined number of cells in a stack, and / or a predetermined number of cell stacks in a system, reducing flexibility to manufacture differently sized systems (increasing manufacturing costs) and / or to repair and / or upgrade such systems in the field.

[0017] Furthermore, where internal manifolds are used, these may be subject to compressive loadingwithin a cell stack which necessitates the provision of a heavy-duty component(s), requiring additional material and / or more complex designs. Furthermore, external piping loops are expensive to manufacture and have many interfaces and connection points so are more prone to leakage. Furthermore, individual piping loops may be required for each fluid circuit, increasing costs.

[0018] Furthermore, challenges remain in draining electrochemical battery systems, e.g. when not in use. Although mentioned by WO2014145844 KELL, which uses external loops with a substantially downward flow pattern, draining remains a challenge. Indeed, such external loops are cumbersome and unwieldy. Thus, several challenges remain in designing a system that addresses one or more problems of the existing art for example which provides a practical and sufficiently self-draining system.

[0019] It is the object of one or more aspects of the invention to alleviate one or more problems presented in the prior art described above or known by those skilled in the art.

[0020] SUMMARY OF THE INVENTION

[0021] In accordance with a first aspect of the invention, there is provided a shunt manifold assembly for a redox flow battery system (such as a redox flow battery module) comprising: at least a first shunt sub-unit for electrolyte (e.g. for one or both positive and / or negative electrolyte), the first shunt sub-unit comprising: - a first portion of a first distribution channel (e.g. forming part of a common first distribution channel e.g. in the form of a tube);

[0022] - a first branch channel (e.g. a first branch tube) providing a fluid connection between the first portion of the first distribution channel and an associated first cell sub-stack;

[0023] - the first branch channel having a serpentine flow path (e.g. along part of its length);

[0024] - the first portion of the first distribution channel and the first branch channel (e.g. preferably substantive portions of each thereof) providing a first flow path for fluid (e.g. a first fluid) in the first shunt sub-unit (e.g. to and / or from a first cell sub-stack), the first flow path being generally or substantially planar (for example associated with (e.g. lying generally or substantially in or about) a first plane).

[0025] In a further aspect there is provided a shunt manifold assembly comprising a first shunt sub-unit configured to provide fluid connection(s) for electrolyte (e.g. one or both positive and negative electrolyte) to and from an associated first cell sub-stack; and at least one further shunt sub-unit configured to provide fluid connection(s) for electrolyte (e.g. one or both positive and negative electrolytes) to and from an associated cell sub-stack.

[0026] In a further aspect there is provided method of manufacturing a manifold assembly comprising: moulding a plurality of (e.g. rotationally) symmetric shunt sub-unit halves and assembling at least one shunt sub-unit from two rotationally symmetric halves.

[0027] In a further aspect of the invention, there is provided a method of manufacturing a shunt manifold assembly as described, comprising: manufacturing a plurality of shunt sub-units and assembling same together to form a shunt manifold assembly.

[0028] In a further aspect, there is provided a redox flow battery system comprising a string of battery modules as described herein.

[0029] In a further aspect, there is provided a redox flow battery system comprising an array of strings of battery modules as described herein.

[0030] In one or more embodiments, the first flow path may be orientated in a particular common direction e.g. along a first draining axis in a first draining direction by orientating the first flow path with respect to that direction.

[0031] In one or more embodiments, the first flow path lies generally in or about a first (preferably a predetermined first) plane. Thus, in one or more embodiments, the level of the first flow path, e.g. the lowest level of the first flow path at any point along its length may vary with respect to the first plane (and in practice with respect to the horizontal) within a predetermined (e.g. small limit). In other words, the first flow path may vary about the first plane by a small amount, typically by no more than the maximum (e.g. vertical) height of the flow path and, more preferably, by no more than half the vertical height of the flow path.

[0032] Preferably, the highest floor level of the first flow path with respect to the first plane (e.g. any point along the first flow path) is less than the lowest ceiling level of the flow path with respect to the first plane. Preferably, in use, the highest floor level of the first flow path is less than the lowest ceiling level of the first flow path with respect to the horizontal plane. In this way, air above a liquid in the flow path can travel along the first flow path e.g. from one end to another of the first flow path, reducing the likelihood of air locks.

[0033] In one or more embodiments, the first shunt sub-unit may further comprise:

[0034] - a first portion of a second distribution channel (e.g. forming part of a common second distribution channel, e.g. in the form of a tube);

[0035] - a second branch channel (e.g. a second branch tube) providing a fluid connection between the first portion of the second distribution channel and an associated (e.g. first) cell sub-stack;

[0036] - the second branch channel having a serpentine path (e.g. along at least part of its length);

[0037] - the first portion of the second distribution channel and the second branch channel (or at least (e.g. preferably) substantive portion(s) each thereof) providing a second flow path for fluid (e.g. a second fluid) in the first shunt sub-unit (e.g. to and / or from a first cell stack), the second flow path being generally or substantially planar (for example associated with (e.g. lying generally or substantially in or about) a second plane.

[0038] In this way, the second flow path may be orientated in a particular direction (e.g. in a second draining direction, close to or, more preferably, the same as the first draining direction e.g. parallel to, or lying in the same plane as, the first flow path.

[0039] In one or more embodiments, a first plane associated with the first flow path may be generally or substantially parallel to a second plane associated with the second flow path. In this way, the first and second flow paths of the first portions of the first and second distribution channels and associated first and second branch channel, of the first shunt sub-unit may be orientated to drain (at least sufficiently) in the same draining direction.

[0040] In one or more embodiments, the first shunt sub-unit may be associated with a first common main plane which comprises the first plane and the second plane. In other words, the first and second flow paths (which may be used for both in-flow and outflow of one electrolyte, or for the in-flows, or the out-flows, of both positive and negative electrolytes), may be associated with (e.g. lie in) the first common main plane e.g. of a first shunt manifold unit. In this way, the first and second flow paths may be orientated to drain in the same direction and at the same level.

[0041] In one or more embodiments, the first shunt sub-unit may further comprise:

[0042] - a first portion of a third distribution channel (e.g. forming part of a common third distribution channel e.g. in the form of a tube);

[0043] - a third branch channel (e.g. a third branch tube) providing a fluid connection between the first portion of the third distribution channel and an associated (e.g. first) cell sub-stack;

[0044] - the third branch channel having a serpentine path (e.g. along at least part of its length);

[0045] - the first portion of the third distribution channel and the third branch channel (or preferably at least substantive portions thereof) providing a third flow path for fluid in the first shunt sub-unit (e.g. to and / or from a first cell sub-stack), the third flow path being generally or substantially planar (for example, associated with (e.g. lying generally or substantially in or about) a third plane).

[0046] Thus, the third flow path may be orientated in a particular direction e.g. in the first or second draining direction, or in a third draining direction.

[0047] In one or more embodiments, the first shunt sub-unit may further comprise;

[0048] - a first portion of a fourth distribution channel (e.g. forming part of a common fourth distribution channel e.g. in the form of a tube);

[0049] - a fourth branch channel (e.g. a fourth branch tube) providing a fluid connection between the first portion of the fourth distribution channel and an associated (e.g. first) cell substack;

[0050] - the fourth branch channel having a serpentine path (e.g. along a part of its length);

[0051] - the first portion of the fourth distribution channel and the fourth branch channel (or preferably at least substantive portions thereof) providing a fourth flow path for fluid in the first shunt sub-unit, the fourth flow path being generally or substantially planar (for example, associated with (e.g. lying generally or substantially in or about) a fourth plane).

[0052] Thus, the fourth flow path may be orientated in a particular direction e.g. in the first or second or third draining direction, or in a fourth draining direction.

[0053] In one or more embodiments, a third plane associated with the third flow path may be generally or substantially parallel to a fourth plane associated with the fourth flow path.

[0054] In this way, the third and fourth flow paths associated with the first portions of the third and fourth distribution channels and the third and fourth branch channels, of the first shunt sub-unit, may be orientated to drain in the same draining direction, preferably in the same draining direction as one or both of the first and second flow paths.

[0055] In one or more embodiments, the first shunt sub-unit may be associated with a second common main plane which comprises the third plane and the fourth plane. In other words, the third and fourth flow paths are associated with the second common main plane e.g. of a second shunt manifold unit. Thus, the third and fourth flow paths can be orientated to drain in the same direction and at the same level.

[0056] In one or more embodiments, at least one of first and second flow paths may lie above or below (e.g. immediately above or below), and / or generally or substantially parallel to, at least one of the third and fourth flow paths.

[0057] Thus, in one or more embodiments, the first common main plane of the first and second flow paths may be above (e.g. directly vertically above) or below (e.g. directly vertically below) the second common main plane of the third and fourth flow paths. Thus, respective portions of first and second distribution channels and associated first and second branch channels, may be vertically above or below, and / or may share the same footprint, as respective portions of the third and fourth distribution channels and associated third and fourth branch channels.

[0058] In one or more alternative embodiments, the first, second, third and fourth flow paths may each lie one above the other e.g. vertically in line.

[0059] In one or more embodiments, at least one of the third and fourth distribution channels and associated third and fourth branch channels of the first and one or more or each further shunt sub-units, may form an out-flow shunt manifold unit for receiving electrolyte (e.g. such as positive and negative electrolyte) from an associated cell substack.

[0060] In one or more embodiments, at least one of the first and second distribution channels and first and second branch channels of the first and one or more or each further shunt sub-units may form (e.g. form part of) an in-flow shunt manifold unit for delivering electrolyte (e.g. such as positive and negative electrolyte) to an associated cell sub-stack.

[0061] In one or more alternative embodiments, one or more portions of each respective first, second, third and fourth distribution channels and associated branch channels of the first and one or more or each further shunt sub-units may form (e.g. form part of) an inlet or outlet shunt manifold unit. In other words, at least four shunt manifold units (both inlet and outlet for both positive and negative electrolytes) may be provided. More preferably just two are provided, more preferably one an inflow and one an outflow shunt manifold unit for both electrolytes.

[0062] In one or more embodiments, within one or more shunt sub-units, or within one or more or each shunt manifold(s) units where provided, one or more or each flow path may share a common level for their respective floors, and / or ceilings and / or central longitudinal axes. Alternatively, or in addition, one or more or each may share a common, vertically overlapping, fluidic path on the same generally planar level from one flow path, or flow path portion, to the next. This is sufficient to allow air to move from one flow path portion to the next to allow drainage.

[0063] In one or more embodiments, at least the first (or one or more or each) shunt sub-unit may be configured to provide a first draining direction (e.g. having a first draining axis, for example in a first common main plane) and the first draining direction (e.g. an axis along it) may be configured to be at an angle a (e.g. a shallow acute angle) to the horizontal (e.g. in use, for example, up to a maximum predetermined angle e.g. a s 2.0°, or s 1 .5°, or s 1.2°, or < 1.0°, or < 0.8°, or < 0.6°, or < 0.5°, or < 0.4°, or < 0.3°, or < 0.2°, or < 0.1°), e.g. at least as great as an expected site grade angle.

[0064] In one or more embodiments, one or more or each further shunt sub-unit may be configured to provide a respective draining direction and / or may be configured to provide a respective draining direction that is the same as the first draining direction of the first shunt sub-unit.

[0065] Preferably, each shunt sub-unit within a shunt manifold unit, and / or each shunt manifold unit, may be generally planar and / or is associated with a common plane of the shunt manifold unit and so may have the same draining direction. Thus, adjusting an inclination and / or level of the shunt manifold assembly, or shunt manifold unit, as a whole, allows adjustment of all the shunt sub-units in that assembly or shunt manifold unit.

[0066] In one or more embodiments, one or more or each shunt sub-unit is mounted on a chassis and may be configured so that its respective draining direction is at an acute internal tilt angle ‘y’ to the chassis (e.g. a small angle such as of y s 2.0°, or s 1 .5°, or < 1.2°, or < 1.0°, or < 0.8°, or < 0.6°, or < 0.5°, or < 0.4°, or < 0.3°, or < 0.2°, or < 0.1°) .g. at least as great as an expected site grade angle.

[0067] Whilst the angle of one or more or each shunt sub-units e.g. an internal tilt angle y with respect to the chassis, may be different; it is preferred these are all the same. Further, whilst the angle of one or more or each shunt sub-units may be variable, or indeed adjustable, within the chassis e.g. on site, it is simpler and so preferable to provide a fixed angle (e.g. internal tilt angle y) for a particular site for all of the generally planar shunt subunits.

[0068] In practice, a battery module chassis may be horizontal within its container but may be offset in use by a small angle (P) due to variation in site grade. Typically, a concrete mounting base on a site for a battery module lies within certain tolerances to the horizontal e.g. ± 1 .0°, or ± 0.6° and so on. Thus, an otherwise horizontally mounted chassis within the battery module may be offset from the horizontal by a slight angle p.

[0069] The overall tilt or inclination angle (say ‘a’) of the first draining direction with respect to the horizontal, for one or more or each shunt sub-unit(s) is typically equal to or greater than the expected tolerance in the grade angle (say P) to the horizontal of the mounting base. Thus when the chassis in which the shunt sub-unit(s) are housed is exactly horizontal, the shunt sub-unit(s) has a draining direction inclined at an internal tilt angle ‘y’ to the chassis and an overall tilt angle of ‘a’, which is equal to ‘y’ when the chassis is itself horizontal.

[0070] Thus, if as |p| , the overall forward tilt (a) of the first draining direction associated with the first shunt sub-unit compensates for any backwards tilt in grade angle (P) of the mounting base. Where the battery module is configured so that a=|p|, the predetermined overall forward tilt (a) of the shunt sub-unit equals the expected rearward tilt (P) of the mounting base due to site grade. This is the worst-case scenario, and the draining direction, preferably the main direction of the shunt manifold assembly as a whole, is horizontal. In other words, the flow path (and so draining direction) of the shunt sub-units within the shunt manifold assembly are generally horizontal where the shunt sub-units all have the same generally planar form and are orientated in the same direction (although internal levels may vary slightly). The shunt manifold assembly will, therefore, self-drain at least to the extent that the shunt current flow path via liquid electrolyte is broken. Typically this is facilitated in a closed system with a small hole for gas in an upper portion of a return pipe in the tank, the small hole being above the free level of electrolyte in the tank. Indeed, depending on the direction of flow of fluid through the flow path and the varying levels of the floor of the flow path, each shunt unit may self-drain entirely (e.g. generally or substantially entirely). Self-draining is able to occur either partially, or entirely, where the internal levels are arranged so that air can flow throughout the entire flow path of the shunt sub-unit. This is because, in one or more preferred embodiments, air locks that might prevent liquid from flowing within the shunt sub-unit are not able to form, and liquid electrolyte can drain via the flow path, at least until the liquid flow path is broken by a slight change in floor level. Indeed, formation of air locks is generally or substantially prevented if overall tilt angle to the horizontal a s a1 (a1 is the air lock angle of the distribution tube) and as a2 (a2 is the air lock angle of the branch channel tube). The air lock angles a1 and a2 typically equal arc tan (height / length) of the respective distribution or branch channel tube. In the distribution channel, the height of the channel (e.g. diameter of tube) may be somewhat larger than that of the branch channels, again reducing the likelihood of air locks.

[0071] Indeed, when the a>p, the forward tilt of the flow path is greater than rearwards tilt of the mounting base and the draining axis now tilts forward in the draining direction. In general terms, the plane associated with shunt sub-unit flow path is now slightly inclined to the horizontal and can drain more easily. There is a limit to the forward tilt, however, set by the tube length tilting direction, so preferably a s a1 and a s a2.

[0072] When the flow path is horizontal, the direction(s) of the serpentine portion of the branch channel has little influence on self-draining. However, when the first draining direction of the first common main plane is tilted, air locks may occur, particularly in branch tubes of lower height (e.g. of smaller diameter and / or of longer length). It is therefore particularly advantageous to avoid longer linear portions, which tend to be narrower, and lower heights (e.g. diameter(s)). Nevertheless, corners introduce flow resistance, so longer lengths and fewer corners are preferred. In some embodiments, a compromise is therefore adopted, utilising corner portion(s) and linear portion(s) in the branch channels, but not too many to provide the requisite length for suitable shunt current protection.

[0073] In a particularly advantageous embodiment, one or more or each branch channel may comprise one or a plurality of linear sections arranged with flow paths crosswise to the draining direction of the draining axis of the first common plane. The linear sections of the branch channel may be connected by one or more corner(s) sections. The corners may be U-shaped between parallel inlet and outlet linear sections. By using a long tube length forthe branch channel but having it span over a short distance (folding / meandering) the air-lock angle is relatively large. Thus, this arrangement reduces the likelihood of air locks in the branch channel.

[0074] Air lock angle a1 , a2 is increased with a larger tube diameter and it is decreased with tube length. Therefore, the preferred arrangement to avoid air-locks is a large tube and a short length. The main purpose of the shunt manifold is to increase the electrical resistance in the fluid path. This is done by reducing the tube diameter and increasing the length. The exact opposite requirement. The branch channel tube meanders over say a 300 mm span equivalent to half the separation of the distribution channel tubes in a preferred embodiment. This is in contract to say 600 mm if it were to meander to-and- fro in the same direction as the distribution channel tubes.

[0075] In one or more embodiments, one or more or each distribution channel may have an axis (generally or substantially) parallel to a first draining direction. In one or more embodiments, a portion (e.g. a first or second portion or one or more or each portion) of the first (or further) distribution channel(s) may define a main longitudinal axis of the shunt manifold assembly e.g. one or more of the portion(s) of the distribution channels may be linear (e.g. generally or substantially linear).

[0076] In one or more embodiments, one or more or each branch channel(s) may comprise a plurality of linear portion(s) and a plurality of corner portion(s).

[0077] In one or more embodiments, at least one or more or all linear portion(s) (e.g. of one or more or each branch channel(s) in one or more or each shunt sub-unit(s)) may be (e.g. generally or substantially) parallel; and / or, one or more or each corner portion(s) (e.g. of one or more or each branch channel(s) in one or more or each shunt subunits)) between one or more respective linear portion(s) may be U-shaped.

[0078] In one or more embodiments, one or more or each linear portion(s) of one or more or each branch channel(s) may define a transverse flow path (e.g. within that linear portion) with respect to at least a first draining direction (e.g. generally or substantially perpendicularto at least a first draining direction e.g. to a main longitudinal axis of a shunt manifold unit (or to the entire shunt manifold assembly) and / or to a longitudinal axis of the flow path in a portion (e.g. a respective portion) of a respective distribution channel).

[0079] In one or more embodiments, the shunt manifold assembly may define a main (e.g. longitudinal) axis and one or more portions of one or more first branch channel(s) may define a second (e.g. longitudinal) axis and the main axis may be at an angle to the second axis of one or more branch channel(s) (e.g. typically the angle is 0° < 6 s 90°. In one or more embodiments, the main axis of the shunt manifold assembly may be generally or substantially perpendicular to the second axis of the one or more branch channel(s). In one or more embodiments, the first distribution channel may define the first longitudinal axis and one or more portions of the one or more branch channel(s) may define the second axis, the first longitudinal axis being at an angle to the second axis (0° < 6 s 90°), and / or being generally perpendicular (e.g. generally substantially perpendicular) to the second axis.

[0080] In one or more embodiments, one or more or each linear portion(s) of one or more branch channel(s) may be (e.g. generally or substantially) perpendicularto a respective portion of a respective distribution tube. In one or more embodiments, one or more or each distribution channel may be linear (e.g. straight, for example generally or substantially straight). In one or more embodiments, one or more portions of a particular distribution channel may be linear, and these may be arranged in a straight line so the entire distribution channel is linear.

[0081] In one or more embodiments, one or more or each respective distribution channel(s) and one or more or each respective branch channel(s) may be fixedly (e.g. rigidly) held with respect to one another and / or may be of rigid construction. In one or more embodiments, these may be made from plastic (e.g. rigid plastic) such as thermoplastic, for example polypropylene or polyethylene.

[0082] In one or more embodiments, one or more or each shunt sub-unit, and / or one or more or each distribution channel(s) and / or one or more or each branch channel(s) together form a rigid (e.g. integrated, unitary) structure, which may be referred to as a shunt manifold unit herein.

[0083] In one or more embodiments, the shunt manifold assembly may comprise one or more further (e.g. second, third, fourth etc.) shunt sub-unit(s). In one or more embodiments, the one or more or each further shunt sub-unit(s) may be identical to the first shunt sub-unit(s). In one or more embodiments the one or more or each further shunt subunits) may have one or more flow paths, generally or substantially, parallel to one another and / or to the flow path of the first shunt sub-unit.

[0084] In one or more embodiments, a corner guide vane may be provided in one or more or each corner section(s) of one or more or each branch channel (e.g. and / or in a distribution channel). The corner guide vane(s) may follow e.g. mirror the shape of the corner, e.g. these may be U-shaped or L-shaped and so on. The corner guide vane(s) may each comprise an upper and a lower guide vane portion extending from (e.g. upwardlyor vertically from) the roof and floor respectively of a branch channel corner section. The upper and lower guide vane portions may meet, and preferably do just meet e.g. to provide a complete corner guide vane across the height of the branch channel tube. The upper and lower sections may be of the same height which may be just recessed below the uppermost surface of each half, so the same or just shorter than half the height of the branch channel. In one or more embodiments, this means that when the two halves of the sub-unit are hot plate welded together, these guide vane upper and lower portions are less likely to be hot welded together but may just meet or nearly meet. Nevertheless, even if hot welded, wholly or partially, at their uppermost opposing surfaces, the now continuous guide vanes formed across the height of the branch channel will function to guide the fluid around the corner section of the branch channel.

[0085] In one or more embodiments, the shunt manifold assembly may comprise: i) an inlet shunt manifold unit, the inlet shunt manifold unit comprising a first layer of one or more shunt sub-units (e.g. associated with a first common main plane); and / or, ii) an outlet shunt manifold unit, the outlet shunt manifold unit comprising a second layer of one or more shunt sub-units (e.g. associated with a second common main plane).

[0086] Preferably, the inlet shunt manifold unit may lie directly vertically above or below, preferably below, the outlet shunt manifold. In one or more embodiments, the inlet shunt manifold unit and outlet shunt manifold unit may be, generally or substantially, identical. In one or more embodiments, the inlet shunt manifold unit and outlet shunt manifold unit may share (e.g. generally or substantially) the same footprint. Preferably, the inlet shunt manifold unit and outlet shunt manifold unit may be located about or generally or substantially parallel to an assembly main plane of the shunt manifold assembly.

[0087] In one or more embodiments, one or more or each shunt sub-unit may be rotationally symmetrical about a rotational axis (such as a central longitudinal axis).

[0088] In one or more embodiments, one half (e.g. an upper half) of one or more or each shunt sub-unit may be identical (e.g. in shape and / or configuration and / or in size) to another half (e.g. a lower half) of the shunt sub-unit. The term half may be used to indicate a first e.g. upper (or lower) portion that co-operates with a corresponding second e.g. lower (or upper) portion.

[0089] In one or more embodiments, a half (e.g. one or both of upper and lower halves) of one or more or each shunt sub-unit(s) may be rotationally symmetrical about a rotational axis) (such as a central longitudinal axis). In other words, the first lower half may be rotationally symmetrical e.g. about a central longitudinal axis) and, once rotated, can be used as a second upper half. Thus, in one or more embodiments, one or more or each shunt sub-unit may be rotationally symmetrical e.g. about at least one rotational axis, such that first portions of the first and second (and / or third and fourth) distribution channels and / or and associated first and second (and / or third and fourth) branch channels are rotationally symmetric. The axis of rotation preferably may lie in the plane of a shunt sub-unit half, but may be perpendicular to the plane of a shunt sub-unit half.

[0090] By providing identical shunt sub-units as repeating sub-assemblies, economies of scale in manufacturing and / or simplification of manufacturing are easier to achieve. Indeed, by providing rotational symmetry in upper and lower halves of one or more or each identical shunt sub-units, and preferably identical upper and lower halves, manufacturing can be simplified. Halves can be molded, preferably identical halves (e.g. upper and / or lower), and these can be arranged about the rotational axis to provide the respective orientation required for serving as upper and / or lower halves of each shunt subunit. These may be referred to as clamshell halves. The halves may match about a sealing surface along their respective peripheries.

[0091] In one or more embodiments, one or more or each shunt sub-unit is constructed from two matching and / or identical halves (e.g. an upper half and a lower half).

[0092] In one or more embodiments, each half may be provided with a first sealing periphery configured to match a first sealing periphery of an opposing half to provide a first seal (e.g. a first peripheral seal) between respective (e.g. upper and lower) halves. The seal may be provided as a weld e.g. from (e.g. hot) welding (e.g. upper and lower) components together.

[0093] In one or more embodiments, a shunt manifold assembly may comprise a second sealing periphery (e.g. supplementary to a first sealing periphery) configured to match a second sealing periphery of an opposing half to provide a second seal (e.g. a second peripheral seal) between respective (e.g. upper and lower) halves.

[0094] In one or more embodiments, a shunt manifold assembly may comprise an end fluid connector (e.g. comprising at least a collar) at the end of a branch channel and / or at the end of a distribution tube, the branch channel and / or distribution tube comprising first and second halves (e.g. upper and lower halves), the sealing surfaces between the two halves terminating before the end fluid connector.

[0095] In one or more embodiments, the method of manufacture may comprise moulding first and second halves (e.g. upper and lower halves) and assembling same together to form a shunt sub-unit. In one or more embodiments, the first and second halves may be identical (e.g. generally or substantially identical or exactly identical).

[0096] In one or more embodiments, the method may comprise: forming an end fluid connector as part of or attached to, to an end of at least one of a branch channel and / or of a distribution channel of a shunt sub-unit (e.g. to form a single element comprising part of one of the halves). The method may comprise forming an end fluid connector which does not comprise a seam joining the two halves.

[0097] In a further aspect there is provided a redox flow battery system comprising at least one battery module, one or more or each battery module comprising: (i) a first cell stack;

[0098] (ii) a first shunt manifold assembly associated with the first cell stack, the first shunt manifold assembly configured to manage electrolyte flow for the first cell stack (e.g. to and / or from the first cell stack, in other words from and / or to a tank assembly e.g. comprising a tank pair (two tanks) for electrolyte(s); further wherein the first cell stack and the first shunt manifold assembly associated with the first cell stack are (e.g. both) configured to be removably mounted (e.g. as a unit) within the battery module.

[0099] In one or more embodiments, there is no requirement to disconnect the first shunt manifold assembly from the first cell stack to remove these from the battery module. Although it is typically necessary to disconnect the shunt manifold assembly from the tank assembly, long and / or extendible and / or flexible tubes may be used to avoid this.

[0100] In one or more embodiments, the battery module may comprise:

[0101] (i) at least one further cell stack (e.g. located next to, e.g. directly next to, for example side by side, with the first cell stack);

[0102] (ii) at least one further shunt manifold assembly, each at least one further shunt manifold assembly associated with a respective at least one further cell stack for managing electrolyte flow for the at least one further cell stack (e.g. to and / or from the at least one further cell stack); further wherein the at least one further cell stack and the shunt manifold assembly associated with the at least one further cell stack may be (e.g. both) configured to be removably mounted (e.g. as a unit) within the battery module.

[0103] In one or more embodiments, at least one cell stack (e.g. the first or the at least one further cell stack) and the shunt manifold associated with the at least one cell stack may be configured to be slidably mounted within the battery module (e.g. so as to be slidable into and / or out of the battery module e.g. as a unit).

[0104] In one or more embodiments, the battery module may comprise at least one expansion slot for removably mounting at least one of the first and further cell stack(s) and associated shunt manifold assembly therein.

[0105] In this way one or more expansion slots may each be provided for each respective cell stack and associated shunt manifold assembly. Indeed, this combination of a cell stack and associated shunt manifold assembly as an integrated equipment block unit facilitates plug-and-play functionality. In one or more embodiments, at least one or more or each cell stack and associated shunt manifold assembly may be each configured to be removable as an integrated equipment block unit (e.g. so the cell stack and associated shunt manifold assembly do not need to be disconnected from one another upon removal).

[0106] In some embodiments, the common chassis is configured to be removable from, and / or insertable, (e.g. slidably) into the battery module and, in particular, from and / or into a housing unit (such as an ISO container) of the battery module.

[0107] Further, in one or more preferred embodiments, the connections and / or pipework for electrolyte between a first (or further) cell stack and its associated shunt manifold assembly may form part of the movable integrated unit e.g. part of the movable equipment block. For example, the equipment block unit (typically comprising at least one of the first cell stack and its associated shunt manifold assembly) can be manufactured and / or shipped and / or repaired and / or replaced and / or supplemented as individual units. Thus, a battery module may be shipped with none or one or more equipment (power) block unit(s), and one or more may be added later e.g. in parallel, and / or existing (power) block unit(s) may be removed individually for repair or replacement.

[0108] In one or more embodiments, one or both of the one or more or each cell stack and associated shunt manifold assembly may be each mounted on rails within the battery module so as to be slidable in and / or out (e.g. as a single unit).

[0109] Rails may be provided on a housing unit (e.g. container) of the battery module or on a chassis of the cell stack and associated shunt manifold assembly, in other words, on the equipment block unit. However, it is preferred that horizontal rails are provided on the housing unit and one or more wheel members, typically one or more opposing pairs of wheel members are provided on a common chassis of the equipment block unit.

[0110] In one or more embodiments, one or more expansion slot(s) may be configured to removably receive a respective cell stack and associated shunt manifold assembly as a slidably removable integrated equipment unit (e.g. as a slidably mounted power block unit).

[0111] By integrated unit is meant a unit, the components of which are fixedly (optionally rigidly) held together, typically within or on a common chassis. Some components may be movable slightly with respect to the chassis, e.g. resilient and / or flexible pipework, or one or more (e.g. rear portions) of a front fixed cell sub-stack and / or front fixed shunt manifold assembly. In one or more embodiments, i) one or more or each cell stack may share a common footprint with its associated shunt manifold assembly; and / or, ii) a footprint of one or more or each cell stack(s) may be of the same order in size, and / or of the same shape, as a footprint of its associated shunt manifold assembly.

[0112] Thus, the footprint of one or more or each cell stack is typically roughly, or more preferably, generally or substantially, the same size and / or shape as a footprint of its associated shunt manifold assembly. Thus, in some embodiments, the footprint of one or more cell stack(s) has a periphery of the same or similar size, and / or of the same or similar shape, as the footprint of its associated shunt manifold assembly.

[0113] In one or more embodiments, one or more or each cell stack is located vertically above or below its associated shunt manifold assembly.

[0114] In one or more embodiments, the cell stack may be located vertically above its associated shunt manifold assembly. In one or more embodiments, the cell stack is directly next to (e.g. immediately adjacent to) its associated shunt manifold assembly (e.g. preferably in a vertical direction).

[0115] In one or more embodiments, one or more of the associated shunt manifold assemblies of one or more or each cell stack, may be mounted in the battery module at an acute angle (e.g. a small acute angle a) to a horizontal direction.

[0116] Whilst the shunt manifold assembly may adopt a variety of shapes, it is preferable if it is generally planar (and one or more or each shunt sub-units within it are generally or substantially parallel to each other) so as to more easily define one or more common draining axes.

[0117] Preferably, the cell stack (or a plane associated with it) is generally vertical and the shunt manifold (or a plane associated with it) is generally horizontal. The cell stack itself may also be mounted at an acute angle (e.g. preferably a small acute angle) to the vertical.

[0118] In one or more embodiments, the cells of a cell stack, or the cells of one or more cell sub-stacks of the cell stack, extend generally or substantially upwardly (e.g. generally or substantially vertically) and an associated shunt manifold assembly, or one or more or each shunt sub-unit of an associated shunt manifold assembly, extends generally or substantially sidewardly (e.g. generally or substantially horizontally).

[0119] Thus, the cell stack (or an associated plane thereof) typically extends upwardly and the shunt manifold assembly (or an associated plane thereof) typically extends in a sideways manner (e.g. laterally) in a generally horizontal manner. Thus, the cell stack and its associated shunt manifold assembly may be transverse (extending in generally vertical and generally horizontal directions) with respect to one another (or at least their respective, associated planes or draining directions).

[0120] In one or more embodiments, the redox flow battery may comp a common chassis and in which the at least one cell stack and its associated shunt manifold assembly are mounted on the common chassis.

[0121] In one or more embodiments, at least one end plate of at least one cell stack, or cell sub-stack, may form a structural cross-member of the chassis.

[0122] In practice, preferably one cell stack (which may comprise multiple cell substacks) and one associated shunt manifold assembly may be mounted on one common (preferably removable) chassis.

[0123] In one or more embodiments, electrolyte pipework to and from the cell stack via its associated shunt manifold is mounted on the common chassis.

[0124] In one or more embodiments, the common chassis may be configured to be mounted generally or substantially horizontally within the battery module (e.g. within a battery module housing such as a container).

[0125] In one or more embodiments, one or both of the at least one cell stack and its associated shunt manifold assembly may be mounted at an acute angle (e.g. ‘y’) to (e.g. to a vertical or horizontal) the common chassis.

[0126] In this way, when the common chassis is horizontally mounted, at least the shunt manifold assembly can be mounted at a slight angle y to the horizontal direction to provide it with a main draining direction. Further, the cell stack can be mounted vertically, or at a slight angle to the vertical, in which case it may be substantially perpendicular to a main draining direction (e.g. a main draining axis) of the shunt manifold assembly.

[0127] In one or more embodiments, one or more or each cell stack may have at least one first draining direction (e.g. generally upwardly) and its associated shunt manifold assembly may have a second draining direction (e.g. generally laterally but with a non-zero vertical component) and, further, in which the first and second draining directions may be generally or substantially mutually perpendicular to one another.

[0128] In one or more embodiments, the shunt manifold assembly comprises shunt flow paths for flow of both anolyte and of catholyte both to and from each cell stack. In some embodiments in which the cell stack comprises a plurality of cell sub-stacks, the associated shunt manifold assembly may comprise an appropriate number of associated shunt sub-units for flow of one or both of anolyte and catholyte both to and from each cell sub-stack.

[0129] In one or more embodiments, an equipment block unit (also known as a power block unit) may be provided comprising a common chassis for one (e.g. the first) cell stack and its associated shunt manifold assembly, and further in which the cell stack and associated shunt manifold assembly may be mounted on the common chassis and one or both may be tilted (e.g. forwardly) at a slight angle to the horizontal (e.g. to a horizontal longitudinal member of the chassis) (e.g. by means of co-operating rails and / or wheel members at different respective heights with respect to the horizontal, e.g. along a length of the removable equipment block unit).

[0130] In this way, one or more rails within a housing unit or a battery module may be horizontal and associated wheel members on a chassis of a removable power block unit may also be distributed in a horizontal plane, however the removable equipment block unit itself is tilted (e.g. forwardly) at a slight angle y with respect to the chassis to facilitate drainage along at least a main draining axis of a shunt manifold assembly (e.g. along the second draining direction of the redox flow battery system).

[0131] In one or more embodiments, the battery module may comprise 1 to 10, or 2 to 8, or 2 to 6, or 2 to 4, or 2 to 3, or 2, or 3, or 4 equipment (e.g. power) block units.

[0132] In one or more embodiments, the battery module may comprise 1 to 10, or 2 to 8, or 2 to 6, or 2 to 4, or 2 to 3, or 2, or 3, or 4 expansion slots, one or more or each expansion slots for receiving a respective cell stack unit and associated shunt manifold assembly (e.g. in the form of removable equipment block unit).

[0133] In one or more embodiments, one or more or each expansion slot may comprise electrical connection(s) for a cell stack (e.g. and any associated cell sub-stacks therein), and / or electrolyte pipework connection(s) for a cell stack(s) (e.g. and indeed any cell sub-stack(s)) and associated shunt manifold assembly and any shunt sub-units therein) for connecting same to and from a tank pair (e.g. a pair of tanks).

[0134] In some embodiments, the electrical connection(s) and electrolyte pipework connection(s) in the expansion slot(s) may be configured for connectingto an equipment block unit comprising the cell stack and associated shunt manifold.

[0135] In one or more embodiments, one or more or each battery module(s) comprises a tank pair (e.g. a single pair of tanks). In one or more embodiments, the cell stacks, and any associated cell sub-stacks therein, within the battery module are hydraulically connected in parallel with the tank pair (e.g. with the single pair of tanks). In one or more embodiments, one or more or each cell stack may comprise two or more cell sub-stacks electrically connected in series (for example, a cell sub-stack may comprise a group of cells stacked together between a pair of end plates and may have separate, parallel hydraulic connections to the pair of tanks).

[0136] In one or more embodiments, in which the battery module comprises at least two cell stacks and associated shunt manifolds (e.g. in individual first and second equipment block units) and the first and second cell stacks are connected electrically in parallel.

[0137] In this way, the power level of the battery module may be adjusted during manufacture and / or later.

[0138] In one or more embodiments, a) within each battery module, one or both of a first cell stack comprising at least one cell sub-stack and a second cell stack comprising at least one cell sub-stack may be provided; and, b) the battery module may be configured to connect at least i) the first and second cell stacks electrically in parallel within the battery module, and ii) the first and second cell stacks and associated cell sub-stacks hydraulically in parallel with the tank pair.

[0139] In one or more embodiments, the battery module may comprise a shunt manifold assembly according to any of claims 1 to 30 or as described herein.

[0140] In a further aspect there is provided an equipment block unit (e.g. power block unit) for a redox flow battery system comprising any of the features of clauses 1 to 24 or as described herein.

[0141] In one or more embodiments, there is provided an equipment block unit (e.g. power block unit) for a redox flow battery system comprising a shunt manifold assembly according to any of claims 1 to 30 or as described herein.

[0142] In one or more embodiments, the first shunt sub-unit, and / or any further shunt sub-unit(s), comprise a one or more or each of; a positive input shunt channel, a positive output shunt channel, a negative input shunt channel, a negative output shunt channel.

[0143] In one or more embodiments, the first and one or more or each further shunt sub-units are generally or substantially identical and may be exactly identical. Indeed, the first and one or more or each further shunt sub-unit(s) may be comprised of a repeating sub-assembly so that the shunt sub-unit(s) are generally or substantially or indeed exactly identical with one another. Use of identical repeating sub-assemblies can facilitate significant cost reduction in both manufacturing and in operation and maintenance.

[0144] In one or more embodiments, the shunt manifold assembly comprises a shunt manifold unit comprising one or both of the positive and negative inlet shunt channels. Preferably both the positive and negative inlet shunt channels are provided within a single integrated shunt manifold unit.

[0145] In one or more embodiments, the shunt manifold assembly comprises an inflow shunt manifold unit and an out-flow shunt manifold unit. Whilst two shunt manifold units, one for inlet shunt channels and one for outlet shunt channels, are preferred, each shunt channel may be provided as a different shunt manifold unit forming a different layer within the manifold assembly. Optionally, the shunt manifold units have coterminous front and back peripheries and, optionally, side peripheries, in other words, preferably each shunt manifold unit providing inlet and / or outlet shunt channels forthe positive and negative electrodes, have coterminous peripheries so that when these are laid one upon the other, these occupy the same footprint within the battery module. Indeed, preferably, these are mounted within the same common chassis.

[0146] In one or more embodiments, one or more or each inlet and / or outlet shunt manifold assembly may comprise co-operating first (e.g. upper) and second (e.g. lower) halves (e.g. clamshell-like halves). One or more or each first (e.g. upper) half and second (e.g. lower) half of the shunt manifold units may be generally or substantially identical (e.g. exactly identical). One or more or each of the first and second halves of the shunt manifold units may be moulded. One or more or each of the first and second halves of the shunt manifold units may comprise, or indeed entirely consist of, thermoplastic.

[0147] In one or more embodiments, one or more branch channels (e.g. forming the inlet and outlet shunt channels) or, more preferably, one or more halves within the shunt manifold unit(s) forming the branch channels, has an end fluid connector at an end thereof for connecting, e.g. via suitable pipework, to an associated cell sub-stack. The halves of the shunt manifold units are preferably provided with at least a first (e.g. peripheral) sealing surface so that opposing sealing surfaces may be sealed together. One or more of the peripheral seals of the halves of the shunt manifold units may terminate before an end of one or more distribution and / or branch channels (in other words at the inlet or outlet shunt channels) so that the peripheral seal has a terminus lying before the end fluid connector (or end cap connector) of the respective distribution or branch channel. Indeed, the peripheral seal in a distribution or branch channel may extend continuously round a height of the channel (e.g. in a smoothly varying seal (e.g. an s-shaped seal) that extends from a floor of the channel around the side walls of the channel and across a ceiling of the channel). In this way, in one or more embodiments, the peripheral seal terminates short of the end fluid connector (or end cap) of the channel which avoids the need to provide a seal between upper and lower halves within an end fluid connector (or end cap connector). An end fluid connector (or end cap connector) moulded as a single element (in particular, a stronger single element, preferably as part of one of the halves, without any joining seals as part of its structure) may be provided.

[0148] Several embodiments of the invention are described and any one or more features of any one or more embodiments may be used in any one or more aspects of the invention as described herein.

[0149] BRIEF DESCRIPTION OF THE DRAWINGS

[0150] The invention will now be described with reference to the following Figures, by way of example only, in which like reference numerals refer to like features.

[0151] Figure 1 is a perspective, partially transparent, view from the front of a battery system comprising a battery module in a container.

[0152] Figures 2A and 2B show front perspective views from above of alternative versions of an equipment block, here a power block unit, typically comprising a cell stack, a shunt manifold assembly and, optionally, a common (shared) chassis; two alternative chassis are shown.

[0153] Figure 3 shows a front elevation-type view of the power block unit of Figures 2A and 2B.

[0154] Figure 4 shows a front perspective view, slightly from below, of the inside of part of a container suitable for receiving one or more, here three, power block units of a battery module.

[0155] Figure 5 shows a front perspective view from above of a container illustrating a power block unit in a partially extracted position mounted on telescopic rails.

[0156] Figure 6 illustrates a front perspective view of a power block unit mounted on a sliding tray for use, for example, in the embodiment of Figure 5. Figure 7 illustrates a plan, partially shaded, view of an in-flow (or out-flow) shunt manifold unit for a shunt manifold assembly, the shunt manifold unit comprising, in this example embodiment, four shunt sub-units.

[0157] Figure 8 shows a plan view of a shunt sub-unit of Figure 7 illustrating the directions of flow of positive and negative electrolyte in this example embodiment when this is used as part of an in-flow shunt manifold unit.

[0158] Figure 9 shows a front perspective view from above of the shunt manifold unit of Figure 8, illustrating (in perspective), optional ribs and an optional peripheral wall on the shunt manifold unit. Here, the directions of flow of positive and negative electrolyte are shown in this example embodiment when this is used as part of an out-flow shunt manifold unit for both anolyte and catholyte.

[0159] Figure 10 shows a plan view of a portion of a shunt manifold assembly, here comprising two (first and second) shunt sub-units which may operate as in-flow (or outflow) shunt sub-units of the shunt manifold assembly.

[0160] Figure 11 shows a perspective view from above of a lower (or upper) half (also referred to as a half clamshell) of a shunt sub-unit.

[0161] Figures 12A, 12B and 12C show perspective close-up views of the front section of a shunt sub-unit or shunt sub-unit half e.g. as seen in Figure 11 .

[0162] Figure 12A shows a corner portion of a lower half of a shunt sub-unit. Figure 12B shows a corner portion of a shunt sub-unit, with lower and upper halves (clamshell halves) joined together. Figure 12C shows two corner portions (one a rear and one a front corner portion) of two neighbouring shunt sub-units, showing upper and lower halves (clamshell halves joined together) illustrating sealing surfaces between the upper and lower halves, and connection(s) for a common fluid distribution tube extending from one shunt sub-unit to another.

[0163] Figure 13 shows a plan view of a half (e.g. an upper or a lower half) of a shunt sub-unit similarto that seen in Figure 11 illustrating inner and optional outer sealing surfaces, and optional (upper and / or lower) guide vane (e.g. guide vane portions) within a branch channel of the shunt sub-unit of the shunt manifold assembly.

[0164] Figure 14 is a close-up perspective view of a portion of a branch channel in a half (e.g. an upper or lower half) of a shunt sub-unit such as that seen in Figure 13, illustrating in perspective curved guide vanes (e.g. guide vane portions) within curved (here U-shaped) end portions of a serpentine branch channel. Figures 15A and 15B show computer models of fluid flow through a serpentine channel similar to those seen in Figures 11 , 13 and 14, in Figure 15A with no guide vane is present, and Figure 15Bwith a guide vane present in curved end portions (here U-shaped portions) of a serpentine branch channel. A consequential reduction in turbulence is seen.

[0165] Figure 16 shows a close-up perspective view of a corner portion of an in-flow (or out-flow) shunt sub-unit at one end, here a front end, of a shunt manifold unit, terminating in a ‘quick connect’ fluid connector.

[0166] Figure 17 shows a corner portion of in-flow (or out-flow) shunt sub-unit at one end, here a rear end, of a shunt manifold unit, the distribution tube of the shunt sub- unit terminating in an end cap.

[0167] Figure 18A shows a side elevation view of a distribution tube; Figure 18B shows a schematic representation of the distribution tube of Figure 18A; Figure 18C shows side elevation cross-sectional close-up views of the ends of the distribution tube of Figure 18A.

[0168] Figure 19 shows a plan cross-sectional view of a branch channel.

[0169] DETAILED DESCRIPTION OF THE INVENTION

[0170] The invention will now be described in more detail, without limitation, with reference to the accompanying Figures.

[0171] It will be understood by those skilled in the art that any dimensions, structures and relative orientations such as height, depth, width, upwardly, laterally, planar, lower and higher, above and below, rigid, fixed, and any directions, such as vertical, horizontal, upper, lower, upward, transverse, axial, radial, longitudinal, tangential, base and roof, lateral, and longitudinal, etc., referred to in this document are within expected use(s) and / or expected tolerances and / or expected limits for the technical field and the apparatus and methods described, e.g. for battery systems and in particular redox flow battery systems, and these terms should be interpreted with this in mind.

[0172] In this document, the use of terms ‘first’, ‘second’, ‘third elements’ or ‘primary’, ‘second’ or ‘tertiary elements’ etc. (e.g. a ‘second element’) does not, where only one is mentioned, require the presence of a ‘first’ such element, unless the context requires otherwise. So, for example a ‘second element’ or ‘secondary element’ does not require the presence of a ‘first element’ or ‘primary element’, although such a ‘first element’ or ‘primary element’ may be present. Further it will be understood that ‘first’ and ‘second’ or ‘primary’ and ‘secondary’ elements, where mentioned, may refer to alternatives, typically of an equivalent or similar nature. For example, in this document first and second cell stacks, or first and second shunt sub-units, referto similar or identical elements, here, typically in the form of equivalent or similar cell stacks, or the same or similar shunt sub-units, used in different locations within the topology of a battery system.

[0173] A cell sub-stack may comprise a group of cells connected in series, which share electrolyte fluid inlets and electrolyte fluid outlets (typically four in total: positive in and out, and negative in and out). It should be noted that by definition “positive” electrolyte is the same as “catholyte” (i.e. the positive electrolyte flowing through the cathode side of the flow battery), and that “negative” electrolyte is the same as “anolyte” (i.e. the negative electrolyte flowing through the anode side of the flow battery).

[0174] A cell sub-stack, e.g. an individual, cell sub-stack may be physically separate from a neighbouring cell sub-stack. A cell sub-stack may comprise a group of bipolar cells with terminal current collectors on each of the positive and negative ends, typically also including other elements such as terminal end plates to form a frame or housing (e.g. optionally with tie-rods between such end plates). Each cell sub-stacks may comprise series connected cells within a pair of end plates.

[0175] In one or more embodiments, multiple cell sub-stacks with terminal connections on each, may be connected in series to form one unitized cell stack, each substack having its own respective positive and negative inlet(s) to and from one or more tanks e.g. the same pair of tanks.

[0176] Referring to Figures 1 to 4, a redox flow battery system 10 is shown here comprising a single battery module 20 in a container 30, typically a rectangular container of ISO standard size (e.g. in compliance with ISO668 (2020)) such as a 20-foot (6.06 m) length container. Other sized containers, e.g. international standard sizes may be used. Other shapes may be used.

[0177] Container 30 is generally rectangular in cross-section when viewed from above, having two opposing short side walls 32, one at the rear and one at the front, and two opposing long side walls 34. One of the short side walls 32 is designated as a front end and one is designated as a rear end. One or more doors 36, typically two doors, are provided at the front end mounted on respective typically vertical axes.

[0178] A series of rails extending rearwardly from the front end are provided on the ceiling underside a roof of the container 30 (see Figure 4). Rails 38 may be, for example, T or I or L-shaped in cross-section, or any suitable shape. Here, l-shaped rails are used, spaced apart in a parallel manner extending between the front end and the rear end of container 30. Thus, opposing portions of each pair of rails 38 provide a hanging mechanism between the rails e.g. which is slidably movable along the rails 38, the purpose of which will be described later.

[0179] Battery module 20 comprises in its lower portion a pair of electrolyte tanks 40 known as a tank pair, here a positive electrolyte tank 40A and a negative electrolyte tank 40B. These occupy the majority of the lower half of container 30. Turning back to Figure 1 , tank pair 40 can be seen extending from a floor of container 30 about two thirds of the way upwards along a height of container 30.

[0180] Battery module 20 further comprises at least one, here three, cell stacks 50. Cell stacks 50 each comprise a stack of cells, typically electrically connected in series and hydraulically connected in parallel to the tank pair 40. Battery module 20 is configured to have one, two or three (or more) cell stacks 50 present at the same time, in any one, two or three (or more) locations with the battery module designed for this purpose. In the example of Figure 1 , three individual cell stacks 50, a first cell stack 50A, a second cell stack 50B, and a third cell stack 50C, are provided. Each cell stack 50 is usually electrically connected in parallel with its neighbouring cell stacks 50 within a single battery module 20. Thus, first cell stack 50A is in parallel with second cell stack 50B and also in parallel with third cell stack 50C, when these present. Only one or two or all three cell stacks 50A, 50B, and 50C may be present. Indeed, with suitable modification four or more cell stacks 50 may be provided within battery module 20.

[0181] The cell stacks 50A, 50B, and 50C are here of the same (e.g. identical) or similar construction. Each of the cell stacks 50 (50A, 50B, 50C) is provided with an associated shunt manifold assembly 80 in the form of a first respective shunt manifold assembly 80A, a second respective shunt manifold assembly 80B, and a third respective shunt manifold assembly 80C. The shunt manifold assemblies 80, are here of the same (e.g. identical) or similar construction. In this way, repeating sub-assemblies may be used for the cell stacks 50 and / or for the shunt manifold assemblies 80 to facilitate repeatable construction components / materials and / or methods, and so cost reduction. Indeed, as will be shown later, repeating sub-assemblies may be used within the cell stacks 50 and / or within shunt manifold assemblies 80 forthe same purpose.

[0182] Each shunt manifold assembly 80 typically comprises one or more shunt manifold units. For example, shunt manifold assembly 80 comprises at least one in-flow shunt manifold unit 180 (for one or both electrolytes) and at least one out-flow shunt manifold unit 280 (for one or both electrolytes). Here, a single in-flow shunt manifold unit 180 for both electrolytes is provided which occupies a common layerwithin shunt manifold assembly 80. Similarly, an out-flow shunt manifold unit 280 is provided which occupies a different common layerwithin assembly 80 (see Figures 3 and 7). Each shunt manifold unit 180, 280 is generally planar. Thus, each shunt manifold unit 180, 280 has associated with it a common main plane, that defines its orientation and position e.g. with respect to the horizontal.

[0183] Each shunt manifold unit 180-280 provides flow path(s) that lie in or about or close to their respective common main plane. Indeed, a central longitudinal axis of the flow path(s) within each respective shunt manifold unit 180, 280 lie in or about or close to their respective common main plane. The common main plane of each shunt manifold unit may be defined as an average height of the shunt manifold unit when it is located on a horizontal surface, or otherwise as would be understood by someone skilled in the art. Each shunt manifold unit 180,280 is constructed so as to be rigid, and rigidly held together, so that it can be handled as a single unit. Thus the flow path(s) within it do not vary, or do not vary to any significant extent. This means that the orientation of the flow path(s) within it can be defined by orientation of the common main plane. In other words, the flow path(s) can be oriented as a whole by orientation of the common main plane. This is the case even though individual flow path portion(s) along each flow path may have a direction of flow that varies slightly with respect to the common main plane, being in line with it, or leading towards it at a slight angle, or leading from it at a slight angle.

[0184] The in-flow shunt manifold unit 180 for both electrolytes and the out-flow shunt manifold unit 280 for both electrolytes are placed directly, here vertically in line, one above the other, the combination forming a respective, associated shunt manifold assembly 80 for a cell stack. Thus, each shunt manifold assembly 80A, 80B, 80C is located immediately below their respective cell stack 50A, 50B, 50C. Thus, each cell stack 50A, 50B, 50C has an associated shunt manifold assembly 80A, 80B, and 80C occupying the same footprint.

[0185] Each cell stack 50A, 50B, 50C and its associated shunt manifold assembly 8080A, 80B, 80C form integrated equipment block units known as power block units 70 (70A, 70B, 70C). Only one or two or all three power block units 70A, 70B, and 70C may be present. Typically, associated electrolyte pipework 42, 44 and connectors also form part of each power block units. These individual power block units 70 typically have a common chassis 90 (e.g. a tray and / or frame) and can be manufactured, handled, and serviced as individual units.

[0186] Each cell stack 50 typically comprises one or more cell sub-stacks 60, each cell sub-stack 60 being formed of a group of cells (e.g. cell plates) electrically in series, physically located together, typically between a pair of end plates 65, 67. In one or more embodiments, one or more of these structural end plates 65, 67 form(s) a structural crossplate of the common chassis of a respective power block unit 70. Here, the front-end plate 65 forms such a structural cross-plate.

[0187] Figure 2A shows a perspective view of a power block unit 70. Each cell stack 60 comprises one or, preferably, two or more cell sub-stacks 60. In the examples shown in Figures 2A and 2B, four cell sub-stacks 60, namely first cell sub-stack 62, second cell substack 64, third cell sub-stack 66, and fourth cell sub-stack 68, are shown. The cell substacks 60 are slightly spaced apart from one another from front to rear, allowing a gap for one or more of electrolyte pipework, electrical connections, expansion, and larger (e.g. longer) cell sub-stacks 60. This together with each respective associated shunt manifold assembly 80 and associated connections on a common chassis 90 provides a neat portable solution to the myriad pipes and connections required.

[0188] In this example embodiment, power block unit 70 comprises a chassis 90, here an elongate chassis 90. Chassis 90 here comprises an opposing pair of parallel upper elongate members 92 and an opposing pair of parallel lower elongate members 94. Each upper elongate member 90 comprises front and rear portions 92A and 92B fastened (e.g. bolted) together directly above a respective lower elongate member 94. End plates 65, 67 are connected (fixedly or slidably) to chassis 90 preferably by angled feet 95, 97 at a lower end to support and locate each cell sub-stack on and within chassis 90.

[0189] Three laterally separated main pillars 98A, 98B, and 98C are rigidly mounted on a respective lower elongate member 94. Between each pair of main pillars, two subsidiary pillars 99A and 99B are provided. The five pillars, three main pillars 98A, 98B, and 98C, and the subsidiary pillars 99A and 99B, are rigidly and fixedly located in an upstanding manner, typically perpendicularly, on respective lower elongate member 94.

[0190] To facilitate draining, it is advantageous if associated shunt manifold assembly 80 is provided with a slight tilt angle ‘y’ in one direction e.g. with respect to the chassis 90, so that it is at a slight angle ‘a’ to the horizontal when in use. When used within an integrated power block unit 70, the power block unit 70 in whole or in part may be inclined at a slight angle. This may be provided for in a number of ways. In this example embodiment, each of the opposing pairs of main pillars 98A, 98B, and 98C is provided with a respective mounting wheel 100A, 100B, 100C which are at slightly differing heights with respect to chassis 90. As can be seen in Figure 2A, the frontmost pair of mounting wheels 100A are located on respective frontmost main pillars 98A, slightly above an uppermost surface of each respective upper elongate member 90. In contrast, opposing pairs of middle mounting wheels 100B are located on respective pillars 98B, slightly lower with respect to the same surface. Further, opposing pairs of rearmost mounting wheels 100C are located in line with an uppermost surface of elongate mounting member 90.

[0191] Where it is described that a first element is in line or above a second element, and a similar first element is in a different relative position with respect to a similar second element, it will be understood that any suitable measuring points for establishing such relative location of one element with respect to another may be used. For example, when considering an uppermost surface of a member and mounting wheels, a central axis of each wheel may be a suitable measuring point. Thus, in Figure 2Athe central axes of front mounting wheels 100A are above the uppermost surface of elongate member 90, the central axes of wheels 100B are just above the same surface, and the central axes of rear mounting wheels 100C are in line it.

[0192] The slightly differing positions of mounting wheels 100A, 100B, and 100C with respect to upper elongate member 92 of chassis 90 means that when the wheels are mounted on respective horizontal rails 38 within a container 30 (see Figure 4), front ends of upper elongate members 92 of chassis 90 are spaced further from rails 38 than the rear ends. This provides a slight incline to power block unit 70 in a forward direction. In other words, power block unit 70 is at a slight angle to mounting rails 38 in container 30, and thus is at a slight angle to the (expected) horizontal, thereby defining a slight downward internal tilt angle ‘y’ (see Figure 2B) towards a front of the power block unit. This will be discussed in more detail below.

[0193] Chassis 90 here comprises four elongate members 92 and 94 that extend from front to rear and are rigidly held together by pillars 98A, 98B, 98C, and 99A and 99B, and, in this example embodiment, structural end plates 96 of each cell sub-stack 60. Alternatively, separate cross-struts between opposing elongate members may be provided. Here, multiple end plates 65 is provided of sufficient strength and sized to form a structural component across chassis 90 between opposing pairs of upper and lower elongate members 92 and 94. As can be seen in Figure 2A, each front end plate 65 of each cell sub-stack 62, 64, 66 and 68 has opposing pairs of angled feet 95 and 97. Front feet 95 are fastened (e.g. bolted) to lower elongate member 94 so that each front structural end plate forms a structural cross-member for chassis 90. Co-operating upper fixing members, e.g. tab and recess and / or bolts, are provided at the top of plate 96 (not shown). The rear end plate of each cell sub-stack 62, 64, 66 and 68 preferably has a sliding foot 97 (e.g. an angled foot) which rests on lower elongate member 94 but is not bolted to it. This means that there is a certain amount of play allowing movement of rear foot 97 of each cell sub-stack 62, 64, 66, 68 on lower elongate members 94. Further, front and rear feet 95, 97 may be angled e.g. at 45°, so that these provide both vertical and horizontal support. The front and rear end plates of the cell sub-stacks are rigidly bound together, compressing the cells between front and rear end plates. Nevertheless, as the temperature changes, a slight amount of expansion and contraction is expected. This can be accommodated by each cell sub-stack having a front pair of bolted feet 95 and a rear pair of sliding feet 97. Indeed, this allows for some variation in both construction of, and / or total number of, cell plates within each cell substack, without needing to vary the mounting to the chassis 90. Thus, the same chassis can be used for differing numbers of cells in cell sub-stacks 60 or even differing numbers of cell sub-stacks.

[0194] As can be seen from Figure 2B, each cell sub-stack 62, 64, 66, 68 is slightly spaced apart from its neighbour(s) facilitating the provision of cell sub-stacks 62, 64, 66, 68 having differing numbers of cells depending on the requirements of the system. Preferably, these all have the same number of cells, but this need not be the case. Further, the number of cells in each cell sub-stack may vary from 10 cells to 200 cells but is more preferably 50, 60, 70 or 80 cells.

[0195] In Figure 2B, a similar power block unit 70 is shown, however here, chassis 90 comprises a pair of continuous upper elongate members 92 and a pair of lower elongate members 94. Each cell sub-stack 62, 64, 66, 68 are each provided with a front structural cross plate 65 mounted on front feet 95 bolted to elongate members 94 and a pair of rear feet 97 slidably mounted on elongate members 94. Upper co-operating members are used to hold the front plate fixedly (e.g. bolts) and the rear plate slidably (e.g. slidable cooperating tab members) to upper elongate members 92. The differing relative vertical positions of front mounting wheels 100A, middle mounting wheels 100B, and rearward mounting wheels 100C with respect to a common surface, here an uppermost surface of upper elongate member 92, can be seen. Frontmost mounting wheels 100A have a central axis located above the uppermost surface of the elongate member 92, whereas the axes of middle mounting wheels 100B are just above that same surface, and rear mounting wheels 100C have a central axis just in line with the uppermost surface of rear elongate members 92.

[0196] Two dashed lines H, L are shown, the upper one (H) between the central axes of mounting wheels 100A, 100B, and 100C is the expected horizontal axis being the axis along which the wheels will sit in rails 38 within container 30. The lower dashed line L is a reference line defined by upper elongate member 92. The distance between the central axis of front mountingwheels 100A and the reference line L is expected to be greaterthan then comparable difference between the central axis of rear mounting wheels 100C and reference line L. A slight tilt angle ‘y’ therefore exists between the expected horizontal H and the reference line L of upper elongate member 92 of chassis 90. This means that the power block unit 70, when in use, located within container 30 will be tilted forward towards its front end at an internal tilt angle of y with respect to the chassis 90 and a slight overall tilt angle a to the horizontal H, (in other words a = internal tilt angle y + site grade angle P). Typically, a is s 2° and preferably s 1°, and more preferably a is s 0.6°. In one or more embodiment, y is s 2° and preferably y s 1°, and more preferably a is s 0.6° tilted towards the front of power block unit 70 on chassis 90.

[0197] Referring to Figure 3, a front view of a front end of a power block unit 70 such as that seen in Figure 2A or 2B is shown. Power block unit 70 here comprises a cell stack 50 of one or more cell sub-stacks 60. The front structural end plate 65 of the first cell sub-stack 62 can be seen. The front pair of mounting wheels 100A can be seen on respective pillars 98A. Because of the slight offset from above view, the top edge of end plates 65, 67 of each cell sub-stack can also be seen.

[0198] Power block unit 70 comprises a cell stack 50 and a shunt manifold 80. The width of the cell stack 50 and, indeed, each individual cell sub-stack 60 is more or less the same as that of the shunt manifold 80 facilitating mounting within a common chassis 90. Indeed, as will be appreciated by consideration of the various figures showing the power block unit 70, at least an outer width, and preferably also the outer periphery of a footprint, of the cell stack 50 is typically more or less the same as the outer width, preferably also the outer periphery of the footprint, of the shunt manifold assembly 80. This means that the cell stack 50 can be located directly in line, e.g. above or below, the shunt manifold assembly 80. Here, shunt manifold assembly 80 is located directly below cell stacks 50. This matching of the size and / or shape of the cross-sectional view of the cell stack 50, at least width ways, when viewed from above, facilitates the mounting of both on the common chassis 90. This also facilitates the handling of the two assemblies (cell stack 50 and shunt manifold assembly 90, and preferably associated pipework and / or connectors etc.) as an integrated power block unit 70.

[0199] Indeed, the shunt manifold assembly 80 and the cell stack 50 are preferably generally rectangular in cross-section when viewed from above. It will be understood, however, that the shunt manifold assembly and the cell stack 50 do not have to have the same length, one may be slightly longer than the other to accommodate e.g. expansion and / or cell sub-stacks of differing length (for example with differing numbers of cells), but it is advantageous if they have at least the same or similar width.

[0200] Each shunt manifold assembly 80 (80A, 80B, 80C) here comprises an in-flow shunt manifold unit 180 for both positive and negative electrolyte and an out-flow shunt manifold unit 280 for both positive and negative electrolyte. Each cell sub-stack 60 is provided with a set of electrolyte connections between it and respective portions (e.g. shunt sub-units 12, 14, 16 and 18 (see Figure 7) of the in-flow and out-flow shunt manifold units 180, 280.

[0201] Here, the in-flow shunt manifold unit 180 is below the out-flow shunt manifold unit, although less preferably it may be above it. The in-flow shunt manifold unit 180 is configured to provide an in-flow to one or more or all respective cell sub-stacks 60 of a cell stack 50. Further, here, each out-flow shunt manifold unit 280 is configured to provide an out-flow shunt for one or more or all cell sub-stacks 60 of a cell stack 50.

[0202] Whilst the positive and negative electrolytes for each cell stack 50 may be handled by four individual shunt manifold units, it is convenient if both positive and negative flow paths leading in are located within the common in-flow shunt manifold unit 180 having flow paths of electrolyte more or less at the same level. Further, it is convenient if the inflow shunt sub-units (12, 14, 16, 18) for each cell sub-stack 60 within one cell stack 50 are located with the same common in-flow shunt manifold unit 180.

[0203] Similarly, it is convenient if both positive and negative electrolyte out-flows are handled within the same out-flow shunt manifold unit 280 having flow paths leading out more or less at the same level within the common out-flow shunt manifold unit 280. Further, it is convenient if the out-flow shunt sub-units (12, 14, 16, 18) for each cell substacks 60 are provided within the same common out-flow shunt manifold unit 280. Each of the in-flow and out-flow shunt manifold units 180, 280 forms a respective layer within the power block unit 70 with an associated main plane defining its overall orientation. Here, the out-flow shunt manifold unit 280 is sandwiched between a base portion of the cell stack 60 and an upper portion of the in-flow shunt manifold unit 180.

[0204] The detail of the shunt manifold assembly 80 and the in-flow and out-flow shunt manifold units 180 and 280 will be described in more detail later, nevertheless, Figure 3 is particularly helpful in illustrating the main distribution channels 81 forthe upper and lower in-flow and out-flow shunt manifold units 180, 280 of shunt manifold assembly 80. An inlet 46A-1 for positive electrolyte and an inlet 46B-1 for negative electrolyte into respective distribution tubes 81 are shown in in-flow shunt manifold unit 180. A positive outlet 46A-2 and a negative outlet 46B-2 from respective distribution tubes 81 in upper out-flow shunt manifold unit 280 are also shown.

[0205] A set of in-flow pipes 42 (42A, 42B) receive positive and negative electrolyte via respective portions of the in-flow shunt manifold unit 180 from the positive and negative electrolyte tanks of a tank pair 40. Fluid end connectors 89 at the exit of the in-flow manifold unit 180 delivering fluid via pipes 42A, 42B into a cell stack 62 via positive inlet 61A-1 to cell sub-stack 62 and negative inlet 61 B-1 . Similarly, respective positive and negative fluid outlets 61 A- 2 and 61 B-2, here at an upper portion of structural end plate 65 of cell substack 63 leads via associated pipework 44 (44A, 44B) to fluid end connectors 89 at respective positive and negative portions of out-flow shunt manifold unit 280.

[0206] Figure 5 shows a perspective view of a container 30 with front doors 36 open, having a power block unit 70 and associated lower elongate member 94 mounted on lower telescopic rails 138 which are mounted above tanks 40. Thus, as will be understood by those skilled in the art there are several ways to arrange the moving (e.g. sliding) in and out of power block unit 70 within container 30. For example, the power block unit may be suspended on rails from above and / or may ride on rails from below or may have wheels on a surface upon which it rolls, and so on. Further, whilst here the motion to remove the power block unit is to-and-fro along a line, it may be rotational, e.g. around a vertical axis.

[0207] Referring now to Figure 6, a power block unit 70 which might be used in the embodiment of Figure 5 is shown. Here, inlet pipes 42 and outlet pipes 44 are formed from single flexible semi-rigid (e.g. resilient) tubes. Upper and lower distribution tubes 81 A provide inlet and outlet flow paths for positive electrolyte. Upper and lower distribution tubes 81 B provide inlet and outlet flow paths for negative electrolyte. Electrical connections 48 are provided for each cell sub-stack 62, 64, 66, and 68 of cell stack 50. L-shaped fluid connectors 89 to and from the in-flow and out-flow shunt manifold units 180, 280 of shunt manifold assembly 80 are provided at a front end. As in Figure 3, electrolyte enters via inlet 46A-1 (positive) and 46B-1 (negative) into respective distribution tubes 81 A, 81 B of in-flow shunt manifold unit 180 to distribute electrolyte to each cell sub-stack 60 within cell stack 50. Similarly, electrolyte exits via outlets 46A-2 and 46B-2 of distribution tubes 81 A, 81 B of, here upper, out-flow shunt manifold unit 280 from each cell sub-stack 60 within cell stack 50. Thus, all four fluid connections to tanks 40 are provided at this front end. Similarly all the electrical connections for each cell-sub-stack are preferably provided at this front end. These arrangements provide simpler one location, here front end, access for fluidic and / or electrical connections (e.g. all external interfaces) for each power block. By providing power blocks 70 that extend longitudinally from front to rear within container 30, the length of the container can be used to a greater extent (e.g. to provide longer cell stacks, and the power blocks 70 can be provided side by side, facilitating a common access location, here at the front end via doors 36. This also allows containers to be placed adjacent to one another with long side walls 34 next to one another, saving on site space.

[0208] Referring now to Figures 7, 8, 9 and 10, various examples of shunt manifold assemblies 80 and portions thereof are shown. Thus, in one or more preferred embodiments, the in-flow shunt manifold unit 180 and out-flow shunt manifold unit 280 are of similar orthe same identical construction as each other e.g. as seen in Figure 7. These 180, 280 may have minor constructional differences, but it is preferred if these are identical.

[0209] Each shunt manifold unit 180, 280 comprises respective shunt sub-units 12, 14, 16, 18, providing one shunt sub-unit per cell sub-stack 62, 64, 66, and 68. Thus, a first shunt sub-unit 12 in one of the in-flow and out-flow shunt manifold units 180, 280 provides flow paths for both positive and negative electrolyte for the in-flow, orthe out-flow, of a first cell sub-stack. Thus, where both in-flow and out-flow shunt manifolds 180, 280 are present, there will be two first shunt sub-units 12, two second shunt sub-units etc. one in the lower layer forming part of the in-flow shunt manifold unit 180 and one in the upper layer forming part of the out-flow shunt manifold unit 280.

[0210] Similarly, the second shunt sub-units 14 in each of the in-flow and out-flow shunt manifold units 180, 280 is associated with a respective cell sub-stack 64. Indeed, each cell sub-stack (62, 64, 66, 68) is provided with two shunt sub-units 14, one in the lower layer forming the in-flow shunt manifold unit and one in the upper layer forming the out-flow shunt manifold unit. Of course, separate shunt sub-units for in-flow and out-flow of positive and negative electrolyte may also be used (so four in total per cell sub-stack). Where the context requires, these upper and lower shunt sub-units may also be referred to together as a shunt sub-unit (e.g. a combined shunt sub-unit) for an associated cell sub-stack.

[0211] The shunt sub-units 12, 14,16,18 and indeed the shunt manifold units 180, 280 derive strength from laterally spaced apart elongate distribution tubes 81 and from transverse (e.g. serpentine) branch tubes 83 rigidly held in place between distribution tubes 81 extending from side to side between the distribution tubes 81 . Each element, each shunt sub-unit 12, 14, 16, 18 and each shunt manifold unit 180, 280 comprising one, two or more individual shunt sub-units rigidly fixed together, can be handled as individual units. Typically, each is manufactured to be sufficiently strong so these will not break under their own weight. Branch channels 83 here in the form of branch tubes 83 provide long shunt channels between respective cell sub-stacks 60, and to between cell stacks 50 in different power blocks 70, increasing resistance between these to reduce and preferably substantially reduce shunt currents therebetween.

[0212] Any further shunt sub-units are similarly associated with respective cell substacks and each cell sub-stack is associated with at least two respective upper and lower shunt sub-units, here only two, and thus share the same or similar footprints. In this example, each cell sub-stack is associated with two shunt sub-units, one in a lower in-flow shunt manifold unit 180 and one in an upper out-flow shunt manifold unit 280.

[0213] In this preferred embodiment, in which two (upper and lower) shunt manifold units 180, 280 are provided, each shunt sub-unit, so each of the first, second, third and any further shunt sub-units 12, 14, 16, and 18 etc. are provided with positive and negative halves (for convenience labelled A, B in Figure 11 ) within which serpentine branch channels 83 form shunt channels for the current flow between electrolyte tanks 40A and 40B and the positive and negative sides of a cell sub-stack 62, 64, 66, 68. Further, each cell sub-stack has, notionally, a respective distribution tube portion of distribution tube 81 allocated to it. For example, positive distribution tube 81 A in Figure 7 comprises four distribution tube portions 81 A-1 , 81 A-2, 81A-3, and 81 A-4 which connect (preferably rigidly) together to form tube 81 A. Negative distribution tube 81 B comprises four distribution tube portions 81 B-1 , 81 B-2, 81 B-3, and 81 B-4 which connect (preferably rigidly) together to form tube 81 B.

[0214] Thus, the branch channels 83 within each shunt sub-unit 12, 14, 16, 18 is, here, in two sides, a positive side 82A, 84A, 86A, and 88A and a negative side 82B, 84B, 86B, and 88B. As described earlier these sides (A, B) may be provided as separate shunt sub- units, ratherthan integrated into a single shunt manifold unit 180, 280 but this is less preferred. Thus, whilst it will be understood that, here, both positive and negative electrolyte are handled within a single sub-unit, these may be handled in separate subunits.

[0215] Figures 8 and 9 show examples of individual shunt sub-units which may be used within an in-flow shunt manifold unit 180 or an out-flow shunt manifold unit 280. The direction of fluid is shown by the arrows. Thus, in Figure 8, positive and negative fluid from respective positive and negative tanks 40A, 40B of a tank pair 40 travel in through portions of distribution tubes 81 A and 81 B respectively before diverting into branch tubes 83 forming branch channels 82A for positive electrolyte and branch channel 82B for negative electrolyte. The branch channels provide a serpentine flow path before exiting the shunt sub-unit at fluid connectors 89 and into electrolyte pipework 42 (see Figure 6) and so into a respective cell sub-stack 60.

[0216] In Figure 9, fluid flows via electrolyte pipework 44 (see Figure 6) from a respective cell sub-stack 60 into fluid connectors 89 and passes, as shown by the arrows, through branch channels 82A and 82B before exiting via respective out-flow portions of distribution tubes 81 A and 81 B in out-flow shunt manifold unit 280.

[0217] Perhaps best seen in Figure 9, a series of spaced apart ribs are provided about branch tubes 83. These ribs may be used as a platform for branch tubes 83 during manufacture and / or as cooling vanes and / or these may provide strength to branch tubes 83. A peripheral wall 87 extends entirely around the shunt sub-unit and this may also be used as a platform member during manufacture and, more usually, provides a drip tray for leak containment in the event of a leak.

[0218] Figure 10 shows a shunt manifold unit 180, 280 for use with cell sub-stacks, comprisingtwo shunt sub-units 12, 14. When combined with a second shunt manifold unit 180, 280, this provides a shunt manifold assembly 80 having two inlets shunts, one for positive and one for negative electrolyte, and two outlet shunts, one for positive and one for negative electrolyte, for each of two cell sub-stacks 62, 64. It is preferred that multiple cell sub-stacks are provided, so two or more cell sub-stacks as shown here, more typically three, four, five, or six or more, however, a cell stack may comprise a single cell sub-stack.

[0219] Referring now to Figure 11 , a cross-sectional cut away perspective view of a lower (or upper) half 200 of one shunt sub-unit 12 is shown in which a first side (to one side of line PQ), labelled portion A, may be used for one electrolyte and a second side (to the other side of line PQ), labelled portion B, may be used for another electrolyte. Typically, portion A is used for positive electrolyte and portion B is used for negative electrolyte.

[0220] Two such halves 200 may be used to provide a single shunt sub-unit 12. Line PQ is a line of symmetry about which half 200 may be rotated to form a second (upper) half and placed upon a first (lower) half. Thus, a first (upper) half 200A and a second (lower) half 200B may be fixedly connected there together as shown in more detail in Figures 12C, 16 and 17. Turning back to Figure 11 , one half 200 of a shunt sub-unit 12 which may form both such upper and lower halves 200A, 200B is shown. In preferred embodiments, upper and lower halves 200A, 200B are identical, the only difference being the rotational arrangement around to axis PQ. Indeed, a shunt manifold unit 180, 280 may comprising multiple shunt sub-units may also be formed as upper and lower halves in a similar manner.

[0221] By providing each sub-unit 12, 14, 16, and 18, as repeatable sub-assemblies from one shunt sub-unit to the next and / or as repeatable, preferably identical, upper and lower halves 200A, 200B, manufacturing of components, assembly of components, and maintenance of components is greatly simplified and cost improvements are seen.

[0222] In more detail now, in Figure 11 , first and second co-operating portions 281 A and 281 B of a distribution tube, one each side of half 200 are shown which provide two spaced distribution channels 81 when two such halves are brought together. Further, first and second co-operating portions 283A, 283B provide branch channel half portions 183 which in turn provide branch channels 83 when brought together.

[0223] When each shunt sub-unit 12, 14, 16, 18 etc. is formed from two respective halves 200, for example a lower half 200B and an upper half 200A, each distribution tube portion 81 and each branch channel 83 is formed with a first inner seam formed from first sealing surfaces 210A, 210B and, preferably, also a second seam formed from second sealing surface 220A, 220B situated around the first seam as secondary protection. Referring to Figure 12B, an example seam formed by sealing surfaces 210, 220, and 230 is shown at 235.

[0224] Inner (e.g. first) sealing surfaces 210A, 210B are formed on respective sides of shunt sub-unit half 200. These define a first continuous seal along the fluid flow path.

[0225] Outer (e.g. second) sealing surfaces 220A, 220B are formed on respective sides of shunt sub-unit half 200. These define a second continuous seal about the fluid flow path in case of leaks from the branch or distribution tubes. An inward second sealing surface 220C may be provided surrounding an internal fixing point 250, again as secondary protection should the first seal fail and / or to facilitate pressure teasting. The co-operating portions of distribution tubes 281 A, 281 B are not quite identical on each side A, B within a single half 200, but may be. Co-operating portions of a fluid connector 89 are shown, one on each side A, B of half 200. These are not quite identical in each side of half 200A, 200B, but may be. By making these slightly different in each side A, B of a single half 200, a number of advantages can be provided. For example, in Figure 12A, an end portion 230 of sealing surface 210, 220 of one half may terminate before a fluid connector portion 89 when co-operating sealing surface end portions 230A, 230B (seen in Figure 11 ) come together. The end portion 230 of sealing surface 210, 220 thus terminates before and is not part of the end connector 89 which is commensurately stronger as it is now an integral element without a seam. In more detail, fluid end connector 89 is located near co-operating upper and lower sealing surfaces 289A and 289B on respective upper and lower halves 200A, 200B, and these terminate at the end portion 230 just short of the fluid connector 89. This means that the sealing surfaces 210, 220 between the two upper and lower halves 200A, 200B do not unnecessarily impact the strength of the fluid connector(s) 89 and result in fluid connector 89 without a weld and / or parting line on the circumference of the sealing surface of 89. Thus, end connector 89 may be formed as part of one half 200 e.g. as a continuous collar component to which a quick fluid connect component may be fixed, e.g. welded.

[0226] Branch tube halves 183 on each side of half 200 are the same or very similar to each other, having a circuitous or serpentine path formed from various corner portions 383, here U-bends, with parallel linear portions 183 in between. Thus, a series of relatively short linear tube portions 183 are placed close to, here next to, one another to provide a lengthy serpentine flow path between an inlet of the branch tube 83 (183) at a junction (typically a slight high point) with a rear end of distribution tube portion e.g. 81 A-1 and an outlet of the branch tube 83 via end connector 89 at the front.

[0227] Another similar end connector 46 is formed at a front end of a distribution tube portion e.g. 81 A-1 and connects (e.g. rigidly) with pipework connections 42 or 44, or with a fluid connector 45 (e.g. in 81 A-2) at a rear end of the distribution tube portion in a neighbouring shunt sub-unit, where provided. A seal 235 between halves 200A, 200B may also terminate short of end connector 46, so that this may also be formed as a single element e.g. a continuous collar component

[0228] Referring now to Figure 12C, a rear fluid connector 45 connects (e.g. by welding, gluing etc. or via a quick connect style arrangement) to a front fluid connector 46. A sealing surface portion 230 of distribution tube 81 terminates just short of the terminal ends of fluid connectors 46 and 89. Further, fluid connector 89 may terminate in a quick connect component 142. Thus, the end portion 230 of the sealing surface between upper and lower halves 200A, 200B terminates before end connector 89 to which a quick connect component 142 may be provided (e.g. welded

[0229] In one or more embodiments, fluid connector 89, and rear and front fluid connectors 45, 46 may terminate in barb for a hose, a quick connect or other fluid interface coupling. In one or more embodiments, quick connect components on the ends of fluid connectors 89, 45 and / or 46 may be molded as part of the shunt manifold sub-unit e.g. as part of one of the shunt manifold sub-unit halves.

[0230] Referringto Figures 11 , 13, and 14, each side A, B of branch channel halves 283A, 283B has respective corner (here U-shaped) portions 383 connecting the ends of the intervening linear portions. The U-shaped corner portions 383 may be provided with guide vanes 240 in one or both sides A, B of one half 200. Thus, upon rotation of to form an upper half, opposing guide vanes 240 are typically provided in opposing upper and lower halves 283A, 283B of branch channels 183. Guide vanes 240 preferably mirror the curved shape of the corner portions 383 but terminate as the corner portions 383 transition into intervening linear portions. The guide vanes in one or both halves 200A, 200B of the shunt sub-unit typically just meet when the two halves 200A, 200B are brought together and welded. Typically, the uppermost surfaces of the guide vanes 240 are recessed below the welding surface(s), and typically just meet following welding. The guide vanes may themselves be welded, but this is less preferred as these are preferably relatively thin structures and so could be damaged or deformed by having these interface with the heated welding pad or plate. Thus, arranging for these to be slightly recessed allows thinner structures to be used for guide vanes which do not unduly reduce flow but which nevertheless may provide a generally or substantially continuous guide vane surface from the floor to the roof of the branch channel tube. Indeed, guide vanes may be provided in only one half 200A, 200B, but this is less preferred.

[0231] The upwardly extending curved nature of guide vanes 240 is seen more in Figure 14. The thickness, or rather thinness, of the guide vanes 240 in one or more or each corner portion half 383 is selected not to unduly reduce fluid flow. Indeed, multiple, preferably concentric, guide vanes od suitable thickness (i.e. relatively thin) may be provided in each corner portion. Preferably, one or more or each guide vane is concentric with a respective corner portion. The curvature and / or shape of the guide vane(s) may be adjusted to correspond to the corresponding shape and / or curvature of a respective corner portion. Guide vanes 240 may be continuously curved or may be formed from tangentially located straight upstandingwalls.

[0232] Figures 15A and 15B show, respectively, models of fluid flow within a branch channel 183 about a curved portion 383 of a branch tube 83. A guide vane 240 has been placed within the branch tube 83 within Figure 15B. The fluid flow is turbulent where it is darker in shade per simulation modelling. The darker portion of turbulent flow around corner portion 383 is less in Figure 15B where guide vane 240 is present, resulting in less pressure drop.

[0233] Figure 16 shows a close-up of a quick end connector 142 and a seam 235 having a terminus 230 which stops short of the fluid end connector 46, here a mounting collar, on shunt sub-unit 12. Thus, the mounting collar 46 can be moulded as part of one half of shunt sub-unit 12 or otherwise formed as a single unit. Indeed, one or more embodiments one or more quick connect components may be moulded as part of the shunt manifold sub unit, e.g. in one of the upper or lower halves thereof. This option may then allow a shunt sub-unit to be “clicked” together with a neighbouring shunt sub-unit t to form a larger shunt manifold unit.

[0234] Figure 17 shows and end cap 145 attached to a rear fluid end connector 45 of a distribution channel, again seam 235 stops short of fluid end connector 45.

[0235] In practice, some sites may have a site grade of up to angle p in any direction. Typically, site grade angle p is si °, and more typically is so.6°. The standard specification is for p to be less than or equal to 0.6°. Specific angles of inclination of the distribution tube with respect to the horizontal can cause an air lock to arise, preventing the power block unit and, in particular, the shunt manifold assembly from draining sufficiently e.g. such that a charged conductive fluid and / or fluid path may remain. Thus variations in site grade can present a problem, as rails 38 in container 30 may not be exactly horizontal.

[0236] Referring now to Figures 18Ato 18C, a distribution tube 81 has a length D1 and a clearance height (fluid port height) at one end of hi .

[0237] An air lock angle a1 can be calculated from the horizontal length (fluid travel distance) of the main distribution leg and the clearance height hi of the distribution port at the rearmost end of the shunt manifold assembly. The horizontal longitudinal distance along the main distribution channel D1 may be, for example, 2500 mm and the height of the distribution port hi may be 22.5mm, giving an air lock angle a1 of arc tan (22.5 / 2500) = 0.51°. Since a1 =0.51° is less than the potential site grade angle p=0.6°, it is possible to install an unmodified power block module and, in particular, shunt manifold assembly in an orientation that may produce an air lock and may not drain. To address this, in one or more embodiments, the supporting chassis 90 suspends the shunt manifold assembly 80 (and typically also the cell stacks 60) at a slight downward internal tilt angle ‘y’ in a (e.g. main) draining direction of the shunt manifold assembly 80. Thus, an internal tilt angle ‘y’, and so overall tilt angle ‘a’, is introduced to the shunt manifold assembly, more accurately to a common main plane of a shunt manifold assembly 80, preferably in a forward direction towards a front.

[0238] Thus, when forward internal tilt angle y is the same or greater than a rear potential angle of p of the site grade, the shunt manifold assembly 80 is always horizontal or tilts forward, in other words overall tilt angle a is zero or positive in a draining direction. In one embodiment, internal tilt angle y=+0.6°, external tilt angle p = -0.6° (rearward), so when |y°| = I P°| the shunt manifold assembly is horizontal (overall tilt angle a=0), and when p=+0.6° (forward), the shunt manifold assembly tilts forward by a= y +p =1 .2°.

[0239] It is of note that the meandering branch channels 83 may have a downward draining direction tilted in an opposite direction to the draining direction of the main distribution tube 81 . In other words, the corner junction between the main distribution channel 81 and a branch channel 83 is a high pointwhen considering the level of the floor of the fluid flow path(s). In this case, an air lock angle a2 for a branch channel may be arc tan (hi / length of branch channel i.e. a2 = arc tan (22.5 / 600) = 2.1°. So, 2.1° is the angle of tilt (here rearwards) above which air lock may occur in the branch channel. The angle of tilt of the branch channel is typically rearward with respect to the horizontal, and so when this is tilted forward in the draining direction by a forward tilt of the shunt manifold assembly, the maximum incline is, say, 1 .2° (i.e. <2.1°) so air lock is not likely to occur.

[0240] By providing common shunt manifold unit(s) 180, 280 associated with respective common main planes for each shunt sub-unit there, it is simpler to orient these as a whole within a battery module 20, to overcome issues of site grade and potential air locks. Thus, draining and in particular self-draining, at least sufficiently to break the current path via liquid electrolyte(s) can be facilitated e.g. for servicing or maintenance.

[0241] Indeed, by providing the shunt manifold unit(s) 180, 280 as part of a shunt manifold assembly 80, the assembly itself can be thought of as a single integrated component oriented in an assembly main plane. Adjustment of this assembly main plane to avoid air locks by inclining it (and so the shunt manifold assembly, at overall tilt angle a to the horizontal, commensurately adjusts the inclination angles of each shunt manifold unit 180, 280. This makes it much simpler to design a power block unit that self-drains (at least sufficiently) as a whole, the cell stacks typically having upstanding cell plates which also self-drain into the shunt manifold assembly.

[0242] The invention has been described with reference to a preferred embodiment. However, it will be appreciated that variations and modifications can be effected by a person of ordinary skill in the art without departing from the scope of the invention.

[0243] Reference Numerals

[0244] 10 Battery System

[0245] 12 first shunt sub-unit

[0246] 14 second shunt sub-unit

[0247] 16 third shunt sub-unit

[0248] 18 fourth shunt sub-unit

[0249] 20 Battery Module (e.g. comprising one or more cell stack(s) and a tank air and associated shunt manifold(s) and other tank and electrical connections).

[0250] 30 container

[0251] 32 short side wall of container (at front and rear ends of container)

[0252] 34 long side wall of container

[0253] 36 door(s), typically two opposing doors, at short front end on vertical axis

[0254] 38 rail(s) (e.g. T- or I- or L-shaped rail(s))

[0255] 40 tank pair, a pair of electrolyte tanks

[0256] 40A positive electrolyte tank

[0257] 40B negative electrolyte tank

[0258] 42 in-flow pipe(s)

[0259] 42A positive in-flow pipe (e.g. to cell sub-stack), optionally flexible

[0260] 42B negative in-flow pipe (e.g. cell sub-stack), optionally flexible

[0261] 44 out-flow pipe(s)

[0262] 44A positive out-flow pipe (e.g. from cell sub-stack), optionally flexible

[0263] 44B negative out-flow pipe (e.g. from cell sub-stack), optionally flexible

[0264] 45 rear end connector portion of a distribution tube

[0265] 46 front end connector portion of a distribution tube

[0266] 46A-1 positive inlet (e.g. to cell sub-stack)

[0267] 46A-2 positive outlet (e.g. from cell sub-stack)

[0268] 46B-1 negative inlet (e.g. to cell sub-stack)

[0269] 46B-2 negative outlet (e.g. from cell sub-stack)

[0270] 48 electrical connector for a cell sub-stack

[0271] 50 cell stack (e.g. stack of cells, typically in series within a cell stack)

[0272] 50A first cell stack (e.g. electrically in parallel with a second and / or third cell stack when present) 50B second cell stack (e.g. electrically in parallel with a first and / or third cell stack when present) 50C third cell stack (e.g. electrically in parallel with a first and / or second cell stack when present) 60 cell sub-stack (e.g. group of cells electrically in series e.g. physically located together, within a cell stack)

[0273] 61 A-1 positive inlet to cell sub-stack

[0274] 61A-2 positive outlet from cell sub-stack

[0275] 61 B-1 negative inlet to cell sub-stack

[0276] 61 B-2 negative outlet from cell sub-stack

[0277] 62 first cell sub-stack

[0278] 64 second cell sub-stack 65 front end plate of cell sub-stack

[0279] 66 third cell sub-stack

[0280] 67 rear end plate of cell sub-stack

[0281] 68 fourth cell sub-stack

[0282] 70 power block unit

[0283] 70A first power block unit

[0284] 70B second power block unit

[0285] 70C third power block unit

[0286] 80 shunt manifold assembly

[0287] 80A first shunt manifold assembly e.g. forfirst power block

[0288] 80B second shunt manifold assembly e.g. for second power block

[0289] 80C third shunt manifold assembly e.g. for third power block

[0290] 180 shunt manifold unit (e.g. in-flow for one or both positive and negative electrolytes)

[0291] 280 shunt manifold unit (e.g. out-flow for one or both positive and negative electrolytes)

[0292] 81 common distribution tube(s) (preferably linear)

[0293] 81A-1, 81A-2, 81A-3, 81A-4 portions of distribution tube in side A of a shunt manifold unit (180,

[0294] 280)

[0295] 81 B-1 , 81 B-2, 81 B-3, 81 B-4 portions of a distribution tube in side B of a shunt manifold unit (180,

[0296] 280)

[0297] 83 branch channel e.g. serpentine branch tube

[0298] 85 ribs

[0299] 87 peripheral wall

[0300] 89 fluid connector (e.g. L-shaped fluid connector between shunt sub-unit and pipework 42 or 44)

[0301] 90 chassis for power block unit

[0302] 92 upper rail, 92A, 92B upper rail portions

[0303] 94 lower rail

[0304] 95 bolted foot

[0305] 96 structural end plate of cell sub-stack

[0306] 97 sliding foot

[0307] 98 pillars

[0308] 98A, 98B, 98C front, middle, and rear main pillars

[0309] 99A, 99B supplementary pillars

[0310] 100 mounting wheel

[0311] 100A, 100B, 100C front, middle, and rear mounting wheels,

[0312] 138 lower (preferably telescoping) rail

[0313] 142 fluid (e.g. quick) connector component

[0314] 143 mounting collar

[0315] 145 end cap

[0316] 183 linear portion(s) of serpentine branch channel

[0317] 283A, 283B sides A, B of branch channel half

[0318] 383 curved portion(s) of serpentine branch channel

[0319] 200 half (e.g. clamshell-like half) of shunt sub-unit

[0320] 200A upper half of shunt sub-unit

[0321] 200B lower half of shunt sub-unit

[0322] 210 inner (e.g. first) sealing surface of shunt sub-unit

[0323] 210A inner sealing surface of first side

[0324] 210B inner sealing surface of second side

[0325] 220 outer (e.g. second) sealing surface

[0326] 220A outer (e.g. second) sealing surface of first side

[0327] 220B outer (e.g. second) sealing surface of second side

[0328] 220C inward (e.g. second) sealing surface 230 terminus of sealing surface

[0329] 235 seam formed by sealing surfaces 210, 220, 230

[0330] 240 curved guide wall

[0331] 250 fixing point (e.g. a land or strong point to which or in which a fixing such as a nut and bolt can be located) a - overall tilt angle (e.g. of a main draining direction)

[0332] P - site grade angle y- internal tilt angle

[0333] PQ axis of symmetry a1 air lock angle of distribution channel (e.g. tube) a2 air lock angle of branch channel (e.g. tube)

[0334] CLAUSES

[0335] The following are clauses suitable for use as claims e.g. in a divisional application.

[0336] 1 . A redox flow battery system comprising at least one battery module, one or more or each battery module comprising:

[0337] (i) a first cell stack;

[0338] (ii) a first shunt manifold assembly associated with the first cell stack, the first shunt manifold assembly configured to manage electrolyte flow for the first cell stack; further wherein the first cell stack and the first shunt manifold assembly associated with the first cell stack are configured to be removably mounted within the battery module.

[0339] 2. A redox flow battery system according to clause 1 in which the battery module comprises:

[0340] (i) at least one further cell stack;

[0341] (ii) at least one further shunt manifold assembly, each at least one further shunt manifold assembly associated with a respective at least one further cell stack for managing electrolyte flow for the at least one further cell stack; further wherein the at least one further cell stack and the shunt manifold assembly associated with the at least one further cell stack are configured to be removably mounted within the battery module.

[0342] 3. A redox flow battery system according to any preceding clause in which at least one cell stack and the shunt manifold associated with the at least one cell stack are configured to be slidably mounted within the battery module.

[0343] 4. A redox flow battery system according to any preceding clause in which the battery module comprises at least one expansion slot for removably mounting at least one of the first and further cell stack(s) and associated shunt manifold assembly therein.

[0344] 5. A redox flow battery system according to any preceding clause in which at least one or more or each cell stack and associated shunt manifold assembly are each configured to be removable as an integrated equipment block unit. 6. A redox flow battery system according to any preceding clause in which one or both of the one or more or each cell stack and associated shunt manifold assembly are each mounted on rails within the battery module so as to be slidable in and / or out.

[0345] 7. A redox flow battery system according to any preceding clause in which: i) one or more or each cell stack shares a common footprint with its associated shunt manifold assembly; and / or ii) a footprint of one or more or each cell stack(s) is of the same order in size, and / or of the same shape, as a footprint of its associated shunt manifold assembly.

[0346] 8. A redox flow battery system according to any preceding clause in which the cell stack is located vertically above its associated shunt manifold assembly.

[0347] 9. A redox flow battery system according to any preceding clause in which one or more of the associated shunt manifold assemblies of one or more or each cell stack, is or are mounted in the battery module at an acute angle to a horizontal direction.

[0348] 10. A redox flow battery system according to any preceding clause comprising a common chassis and in which the at least one cell stack and its associated shunt manifold assembly are mounted on the common chassis.

[0349] 11. A redox flow battery system according to clause 10 in which at least one end plate of at least one cell stack, or cell sub-stack, forms a structural cross-member of the chassis.

[0350] 12. A redox flow battery system according to any preceding clause in which electrolyte pipework to and from the cell stack via its associated shunt manifold is mounted on the common chassis.

[0351] 13. A redox flow battery system according to clause 11 or 12 in which the common chassis is configured to be mounted generally or substantially horizontally within the battery module. 14. A redox flow battery system according to clause 13 in which one or both of the at least one cell stack and its associated shunt manifold assembly are mounted at an acute angle to the common chassis.

[0352] 15. A redox flow battery system according to any preceding clause in which one or more or each cell stack has at least one first draining direction and its associated shunt manifold assembly has a second draining direction and, further, in which the first and second draining directions are generally or substantially mutually perpendicular to one another.

[0353] 16. A redox flow battery system according to clause 15 (e.g. when dependent on clause 5) in which an equipment block unit is provided comprising a common chassis for one cell stack and its associated shunt manifold assembly, and further in which the cell stack and associated shunt manifold assembly are mounted on the common chassis and one or both are tilted at a shallow acute angle to the chassis and / or horizontal.

[0354] 17. A redox flow battery system according to clause 16 in which the battery module comprises 1 to 10, or 2 to 8, or 2 to 6, or 2 to 4, or 2 to 3, or 2, or 3, or 4 equipment (e.g. power) block units.

[0355] 18. A redox flow battery system according to any preceding clause the battery module comprises 1 to 10, or 2 to 8, or 2 to 6, or 2 to 4, or 2 to 3, or 2, or 3, or 4 expansion slots, one or more or each expansion slots for receiving a respective cell stack unit and associated shunt manifold assembly.

[0356] 19. A redox flow battery system according to clause 18 in which one or more or each expansion slot comprises electrical connection(s) for a cell stack, and / or electrolyte pipework connection(s) for a cell stack(s) for connecting same to and from a tank pair.

[0357] 20. A redox flow battery system according to any preceding clause in which the cell stacks, and any associated cell sub-stacks therein, within one or more or each battery module, are hydraulically connected in parallel with the tank pair.

[0358] 21 . A redox flow battery system according to any preceding clause in which one or more or each cell stack comprises two or more cell sub-stacks electrically connected in series. 22. A redox flow battery system according to any preceding clause comprising at least two cell stacks and associated shunt manifolds and the first and second cell stacks are connected electrically in parallel.

[0359] 23. A redox flow battery system according to any preceding clause in which: a) within each battery module, one or both of a first cell stack comprising at least one cell sub-stack and a second cell stack comprising at least one cell sub-stack is provided; and, b) the battery module is configured to connect at least i) the first and second cell stacks electrically in parallel within the battery module, and ii) the first and second cell stacks and associated cell sub-stacks hydraulically in parallel with the tank(s).

[0360] 24. A redox flow battery system comprising a shunt manifold assembly according to any of claims 1 to 30.

[0361] 25. An equipment block unit (e.g. power block unit) for a redox flow battery system comprising any of the features of clauses 1 to 24.

[0362] 26. An equipment block unit (e.g. power block unit) for a redox flow battery system, optionally according to clause 25, comprising a shunt manifold assembly according to any of claims 1 to 30.

Claims

CLAIMS:1 . A shunt manifold assembly for a redox flow battery comprising: at least a first shunt sub-unit for electrolyte, the first shunt sub-unit comprising:- a first portion of a first distribution channel;- a first branch channel providing a fluid connection between the first portion of the first distribution channel and an associated first cell sub-stack;- the first branch channel having a serpentine flow path;- the first portion of the first distribution channel and the first branch channel providing a first flow path for fluid in the first shunt sub-unit, the first flow path being generally or substantially planar.

2. A shunt manifold assembly according to claim 1 in which the first shunt sub-unit further comprises:- a first portion of a second distribution channel;- a second branch channel providing a fluid connection between the first portion of the second distribution channel and an associated cell sub-stack;- the second branch channel having a serpentine path;- the first portion of the second distribution channel and the second branch channel providing a second flow path for fluid in the first shunt sub-unit, the second flow path being generally or substantially planar.

3. A shunt manifold assembly according to claim 2 in which a first plane associated with the first flow path is generally or substantially parallel to a second plane associated with the second flow path.

4. A shunt manifold assembly according to claim 3 in which the first shunt sub-unit is associated with a first common main plane which comprises the first plane and the second plane.

5. A shunt manifold assembly according to any preceding claim in which the first shunt sub-unit further comprises:- a first portion of a third distribution channel;- a third branch channel providing a fluid connection between the first portion of the third distribution channel and an associated cell sub-stack;- the third branch channel having a serpentine path;- the first portion of the third distribution channel and the third branch channel providing a third flow path for fluid in the first shunt sub-unit, the third flow path being generally or substantially planar.

6. A shunt manifold assembly according to claim 5 in which the first shunt sub-unit further comprises;- a first portion of a fourth distribution channel;- a fourth branch channel providing a fluid connection between the first portion of the fourth distribution channel and an associated cell sub-stack;- the fourth branch channel having a serpentine path;- the first portion of the fourth distribution channel and the fourth branch channel providing a fourth flow path for fluid in the first shunt sub-unit, the fourth flow path being generally or substantially planar.

7. A shunt manifold assembly according to claim 6 in which a third plane associated with the third flow path is generally or substantially parallel to a fourth plane associated with the fourth flow path.

8. A shunt manifold assembly according to any of claims 5 to 7 in which at least one of first and second flow paths lie above or below, and / or generally or substantially parallel to, at least one of the third and fourth flow paths.

9. A shunt manifold assembly according to any of claims 6 to 8 in which at least one of the third and fourth distribution channels and associated third and fourth branch channels of the first and one or more or each further shunt sub-units, form an out-flow shunt manifold unit for receiving electrolyte from an associated cell sub-stack.

10. A shunt manifold assembly according to any preceding claim in which at least one of the first and second distribution channels and first and second branch channels of the first and one or more or each further shunt sub-units form an in-flow shunt manifold unit for delivering electrolyte to an associated cell sub-stack.

11. A shunt manifold assembly according to any preceding claim in which at least the first shunt sub-unit is configured to provide a first draining direction and the first draining direction is configured to be at an acute angle a to the horizontal.

12. A shunt manifold assembly according to claim 11 in which one or more or each further shunt sub-unit is configured to provide a respective draining direction and / or is configured to provide a respective draining direction that is the same as the first draining direction of the first shunt sub-unit.

13. A shunt manifold assembly according to claim 11 or 12 in which one or more or each shunt sub-unit is mounted on a chassis and is configured so that its respective draining direction is at an acute angle y to the chassis.

14. A shunt manifold assembly according to any preceding claim in which one or more or each branch channel(s) comprise(s) a plurality of linear portion(s) and a plurality of corner portion(s).

15. A shunt manifold assembly according to claim 14 in which: at least one or more or all linear portion(s) (e.g. of one or more or each branch channel(s) in one or more or each shunt sub-unit(s)) are parallel; and / or, one or more or each corner portion(s) between one or more respective linear portion(s) are U-shaped.

16. A shunt manifold assembly according to claim 14 or 15 in which one or more or each linear portion(s) of one or more or each branch channel(s) define(s) a transverse flow path with respect to at least a first draining direction and / or to a longitudinal axis of the flow path in a portion of a respective distribution channel).

17. A shunt manifold assembly according to claim 16 in which one or more or each linear portion(s) of one or more branch channel(s) is perpendicular to a respective portion of a respective distribution tube.

18. A shunt manifold assembly according to any preceding claim in which one or more or each respective distribution channel(s) and / or one or more or each respective branch channel(s) are rigidly held with respect to one another and / or are of rigid construction.

19. A shunt manifold assembly according to any preceding claim comprising one or more further shunt sub-unit(s).

20. A shunt manifold assembly according to any preceding claim in which a corner guide vane is provided in one or more or each corner section(s) of one or more or each branch channel.21 . A shunt manifold assembly according to any preceding claim comprising: i) an inlet shunt manifold unit, the inlet shunt manifold unit comprising a first layer of one or more shunt sub-units; and / or, ii) an outlet shunt manifold unit, the outlet shunt manifold unit comprising a second layer of one or more shunt sub-units.

22. A shunt manifold assembly according to any preceding claim in which one or more or each shunt sub-unit is rotationally symmetrical about a rotational axis.

23. A shunt manifold assembly according to any preceding claim in which one half of one or more or each shunt sub-unit is identical to another half of the shunt sub-unit.

24. A shunt manifold assembly according to claim 23 in which a half of one or more or each shunt sub-unit(s) is or are rotationally symmetrical about a rotational axis).

25. A shunt manifold assembly according to any preceding claim in which one or more or each shunt sub-unit is constructed from two matching and / or identical halves (e.g. an upper half and a lower half).

26. A shunt manifold assembly according to claim 25 in which each half is provided with a first sealing periphery configured to match a first sealing periphery of an opposing half to provide a first seal between respective halves.

27. A shunt manifold assembly according to claim 26 comprising a second sealing periphery configured to match a second sealing periphery of an opposing half to provide a second seal between respective halves.

28. A shunt manifold assembly according to claim 26 or 27 comprising an end fluid connector at the end of a branch channel and / or at the end of a distribution tube, the branch channel and / or distribution tube comprisingfirst and second halves, the sealing surfaces between the two halves terminating before the end fluid connector.

29. A method of manufacturing a manifold assembly comprising: moulding a plurality of rotationally symmetric shunt sub-unit halves and assembling at least one shunt sub-unit from two rotationally symmetric halves.

30. A method of manufacturing according to claim 28 comprising: forming an end fluid connector as part of or attached to, to an end of at least one of a branch channel and / or of a distribution channel of a shunt sub-unit in which the end connector does not comprise a seam between the two halves.

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