WO2016132280A1

WO2016132280A1 - Battery modules and methods for their manufacture

Info

Publication number: WO2016132280A1
Application number: PCT/IB2016/050808
Authority: WO
Inventors: John Lewis; Mark Brown
Original assignee: Tata Motors European Technical Centre Plc; Tata Motors Limited
Priority date: 2015-02-18
Filing date: 2016-02-16
Publication date: 2016-08-25
Also published as: GB2535546B; GB2535546A; GB201506303D0

Abstract

A method of making a battery module (100) comprising a plurality of interconnected cells (118) (e.g. pouch cells), each cell (1 18) having a plurality of terminals (118T1, 118T2), the method comprising: (i) arranging a plurality of cell groups (120), each group comprising 1, 2, 3 or more individual cells (118), e.g. in the form of a face-to-face cell stack or a side-by-side cell sub-array, into a side-by-side array, wherein pairs of cell terminals (118T1, 118T2) in adjacent respective cell groups (120) are adjacent one another, and preferably of opposite polarity; (ii) interconnecting the adjacent cell terminals (118T1, 118T2) within each respective pair via a or a respective busbar element (130B), e.g. of a flexible, braided, monometallic material, preferably by ultrasonic welding, so as to interconnect adjacent cell groups (120); and then, subsequent to step (ii), (iii) configuring the interconnected cell groups (120), e.g. by folding, into a face- to-face array to form the said battery module (100).

Description

BATTERY MODULES AND METHODS FOR THEIR MANUFACTURE

FIELD OF THE INVENTION

The present disclosure relates to battery modules and methods for their manufacture. More particularly, though not exclusively, the disclosure relates to battery modules, especially battery modules for use as or in batteries for electric vehicles, comprising arrangements of interconnected cells, and to methods for making such battery modules.

BACKGROUND OF THE INVENTION

Large battery packs such as are commonly used in electric vehicle traction applications are typically made up of an array of battery modules. Each module consists of a plurality of electrochemical battery cells connected together in such a way as to provide the module voltage and capacity required, and modules are then connected together within the battery pack to provide the overall pack voltage and energy required.

Traction battery applications generally use lithium ion cells. These are commercially available in a variety of configurations, such as cylindrical, rectangular and pouch cells. Pouch cells are often preferred because their geometry allows more cells to be accommodated within a given volume and they can thus provide a greater energy density. Pouch cells also have a higher surface area to volume ratio, which facilitates cooling. Lithium ion pouch cells typically have the terminals arranged on one side of the pouch. The cell chemistry and internal electrode construction results in the positive cell terminal normally being aluminium and the negative terminal normally being nickel- coated copper. These terminals generally comprise thin (typically 0.2 mm) flexible foils.

In order to provide mechanical support, individual pouch cells may be packaged within frames or cassettes, typically of plastics material. The cassette may also include provision for cooling the cell, such as a heatsink device, and means of applying controlled compression to the cell, such as a foam pad, when the cell is in an assembled state. Battery modules are generally formed by stacking and mechanically securing together the requisite number of cells in a face-to-face manner. The individual cells within the assembled module are then electrically interconnected using busbars, which usually comprise a formed component made of copper or aluminium or a combination of both. The cell terminals are generally joined to the busbar by a welding process.

Many conventional welding processes, such as laser or resistance welding, are generally well suited to forming the interconnections between cell terminals and busbars, because the process tooling can be suitably scaled to permit access to weld locations within the battery module once assembled. However, because the commonly favoured use of pouch cells means that dissimilar metals are used for the positive and negative terminals, it is not possible to use busbars comprising solely copper or aluminium in these cases. This is because when copper and aluminium are joined using conventional weld processes that rely on interfacial fusion, brittle copper-aluminium intermetallic compounds are formed, which result in welds of poor integrity, strength and durability.

One possible solution to this problem is to employ busbars which are composite structures of aluminium and copper, such that welds between the aluminium positive cell terminals are made to that portion of the busbar which comprises aluminium, and likewise welds between the copper negative cell terminals are made to that portion of the busbar that comprises copper. In this way fusion welds are always made between like metals and problems of intermetallic compound formation are avoided. However such composite busbar components are relatively expensive, so it would be advantageous to be able to use a simple mono-metallic component if that were possible.

In terms of other known welding techniques, ultrasonic welding has long been recognised as a means for forming reliable joints between dissimilar metals. Unlike resistance or laser welding, there is no fusion at the weld interface. Instead the process relies on the formation of a solid state diffusion bond, and hence the formation of intermetallic compound is generally able to be avoided. However, in terms of practical implementation, ultrasonic welding presents a problem in the field of interconnecting cells of battery modules as manufactured by known methods, because the size and configuration of the weld tools result in their being unable to access the restricted space between adjacent cell terminals in order to form a weld.

It is therefore an object of the present invention to circumvent or at least partially solve or ameliorate the above problems and limitations or shortcomings of interconnecting cells in the production of battery modules according to known techniques, and to provide a new way of making battery modules comprising arrays of interconnected cells which is simpler, more versatile and results in battery modules having improved properties. SUMMARY OF THE INVENTION

Accordingly, aspects of the present invention provide a method of making a battery module, a battery module per se, a battery for an electric vehicle, and an electric vehicle including a battery comprising one or more of the battery modules.

As used herein the terms "side-by-side" and "face-to-face" are defined relative to the general shape and configuration of many common designs of cell which are typically in the form of a generally relatively flat, polygonal (usually generally rectangular) body having opposite major faces (i.e. front and rear faces) which have relatively large height and width dimensions in comparison with the body's thickness, and opposite minor side faces (i.e. left and right sides, which join the major faces) which have a relatively small width dimension in comparison with their height and correspond to the relatively small thickness of the cell body. The minor top face of the cell body is generally where the cell connection tabs are located. Thus, "side-by-side" means respective cells are arranged with their narrow minor sides juxtaposed (i.e. with the right side of one cell positioned adjacent or substantially abutting the left side of the neighbouring cell, or vice versa), and "face-to-face" means the respective cells are arranged with their respective major front and rear faces juxtaposed (i.e. in a front-to-rear stacked or overlapping arrangement).

In one aspect of the invention for which protection is sought there is provided a method of making a battery module comprising a plurality of interconnected cells, each cell having a plurality of terminals, the method comprising:

(i) arranging a plurality of cell groups into a side-by-side array, wherein cell terminals of adjacent respective cell groups are adjacent one another;

(ii) interconnecting the adjacent cell terminals via a or a respective busbar element so as to interconnect adjacent cell groups; and then

(iii) configuring the interconnected cell groups into a face-to-face array to form the said battery module.

In the present method, the order in which the interconnecting step (ii) and the subsequent configuring step (iii) are performed is advantageous in that it allows relatively unrestricted access to the cell terminals in order to form the interconnection between them via the or the respective busbar element, e.g. by welding.

In some embodiments the side-by-side arranging step (i) may be such that adjacent cell terminals in adjacent respective cell groups are of opposite polarity. This may thus serve to interconnect adjacent cells in a series electrical arrangement, which may be preferred in many practical embodiments. However, in alternative embodiments it may be possible for adjacent cell terminals in adjacent respective cell groups to be of the same polarity, in which case the resulting electrical arrangement of the interconnected cells may be parallel.

Thus in another aspect of the invention for which protection is sought there is provided a method of making a battery module comprising a plurality of interconnected cells, each cell having a plurality of terminals, the method comprising:

(i) arranging a plurality of cell groups into a side-by-side array, wherein adjacent pairs of cell terminals in adjacent respective cell groups are of opposite polarity;

(ii) interconnecting the cell terminals within each respective pair via a or a respective busbar element so as to interconnect adjacent cell groups; and then

In embodiments of the invention each cell group may comprise one or more discrete electrochemical cells.

The or each cell may be of any desired or appropriate type of electrochemical battery cell, e.g. depending on the end use of the battery module and the its overall desired voltage, current and other characteristics. However, in many preferred embodiments of the invention the or each cell is a pouch cell, e.g. a lithium ion pouch cell, especially with a pair of respective terminals which comprise different metals, e.g. aluminium and nickel- coated copper. However the invention may be applied just as usefully to cells of other types or configurations.

In some embodiments, especially those embodiments in which the or each cell is a pouch cell, the or each cell may be housed or contained within a frame or cassette, e.g. of plastics material. Such a frame or cassette may at least partially surround or enclose the cell, especially a pouch cell, therewithin. Such a frame or cassette may preferably be constructed and/or sized and/or configured to provide mechanical support to the cell, especially a pouch cell, therewithin, and especially to facilitate their stacking and/or configuring into the final battery module.

In such embodiments comprising a pouch cell housed or contained within a frame or cassette, the or each frame or cassette may comprise a hinge element or device, so that adjacent frames or cassettes, or pairs of frames or cassettes, are attachable to each other in a hingeing manner. A wide variety of known types of hinge may be suitable for this purpose. The use of such hinges may serve to facilitate the frames or cassettes being configured in step (iii) into the battery module once the cells have had their respective terminals interconnected by the respective busbar element(s). In the case of such mutually hinged frames or cassettes, each frame or cassette may optionally further comprise one or more retaining and/or locking means, e.g. one or more clips, detents or brackets, for securing neighbouring frames or cassettes together within the or each cell group and/or for securing neighbouring cell groups together once they have been configured into the battery module in step (iii).

In other embodiments, instead of the or each cell being housed or contained within a frame or cassette which is hingeably attachable to an adjacent cell, adjacent cells or adjacent cell groups may be configured into their required relative configurations, either in a stage of forming the respective cell groups (in cases where each cell group comprises a plurality of cells) or in a stage of configuring the cell groups into the array in step (iii) of the method, or even in both said stages, using a jig or other manipulation apparatus. Such use of a jig or other apparatus may preferably be such as to configure the respective cells or cell groups (as the case may be), by appropriate positioning and face-to-face arranging, e.g. by folding, relative to each other into the required array, with the jig or other apparatus being subsequently removed, especially once the final battery module has been formed. In certain embodiments, especially those in which the or each cell group comprises a plurality of cells, in particular in the form of a side-to-side cell sub-array (as will be defined and discussed further hereinbelow), it may be provided that the or each such cell group is itself housed or contained within a frame or cassette, such as any of those forms of frame or cassette defined above. In particular, such a frame or cassette which may at least partially surround or enclose the or each cell group may serve to support the cells of the group, optionally in combination with one or more heatsink elements or devices (again, as will be defined and discussed further hereinbelow) in order to facilitate their correct or optimum relative positioning during the steps of interconnecting the relevant cell terminals and the subsequent configuring of the cell groups into the battery module.

In some embodiments the or each cell, whether or not housed within a frame or cassette, may, in the finally configured or assembled battery module, be provided in combination with, especially in thermal contact with, e.g. faced or interfaced with, at least one heatsink element or device. For example, when undergoing charging and discharging during normal operation, lithium ion cells generate heat in proportion to the rate of charge or discharge. In the case of their use in electric vehicles, the rate of charge and particularly the rate of discharge will depend on the type of electric vehicle application. Vehicles with wholly electric propulsion (namely BEV's) generally have relatively low discharge rates, whereas vehicles with hybrid propulsion (namely PHEV's or REEV's) require higher discharge rates. This is because although the latter have similar peak power and voltage requirements to BEV's, vehicle space and weight constraints often limit the size of the battery modules which can be accommodated. Furthermore, cells which may be exposed to temperatures outside the specified upper operating temperature limit can over time suffer degradation in performance, such as loss of energy storage capacity and in extreme cases safety may be compromised. These problems may be exacerbated in geographical territories with high ambient temperatures. Therefore, provision of efficient cooling of cells within battery modules can often be an important consideration in battery design.

Accordingly, in some embodiments of the various aspects of the invention the or each cell may, in the finally configured or assembled battery module, be arranged in thermal contact with, e.g. with a cell face or surface thereof in thermal contact with, at least one face or surface of at least one heatsink element or device. However, in other embodiments the or each cell may, in the finally configured or assembled battery module, be arranged with each of a plurality of cell faces or surfaces thereof in thermal contact with a respective face or surface of a respective one of a plurality of heatsink elements or devices. The or each such heatsink element or device may for example comprise a cooling plate, such as a cooling plate comprising a network or arrangement of internal passageways or channels through which is passed or pumped a coolant fluid, e.g. a coolant liquid or gas. In some embodiments comprising one or more cooling plate(s) or other heatsink element(s) or device(s), the heatsink element(s) or device(s) may for example be provided within a frame or cassette which is used to contain a given individual cell. Furthermore it/they may also usefully be integral with such a frame or cassette, where present. In other embodiments comprising one or more cooling plate(s) or other heatsink element(s) or device(s), the heatsink element(s) or device(s) may instead be provided as component(s) of a or a respective frame or cassette arrangement, or even may itself/themselves form or constitute a framing or supporting or facing or interfacing arrangement, which is used to contain or support a plurality of cells, e.g. in the form of a face-to-face cell stack or a side-by-side cell sub-array, which make up a cell group.

In some embodiments, the or each of a plurality of heatsink elements or devices may, in the finally configured or assembled battery module, advantageously be positioned in thermal contact with at least one face or surface of the or each of the cells making up a cell group. Preferably a single given heatsink device or element may, in the finally configured or assembled battery module, be positioned in thermal contact with, e.g. in face-to-face thermal contact with, a plurality of, or surfaces of different ones of a plurality of, cells making up the cell group. This arrangement may be particularly useful and efficient in the case of cell groups each comprising a side-by-side plural-cell sub-array, whereby plural such cells may be cooled by a single given cooling plate.

In general, in practising embodiments of the method of the invention the requisite number of heatsink elements or devices may initially be located, distributed or arranged in combination with the various ones of the plurality of cell groups in such a way that when the step (iii) of configuring the interconnected cell groups takes place, e.g. by folding of the overall arrangement, the relative distribution or arrangement of the one or more heatsink elements or devices and the various cell groups is such that the desired final face-to-face arrangement of cell groups forming the battery module includes the one or more heatsink elements or devices interposed between appropriate ones of the cell groups to achieve a desired optimum cell group and heatsink distribution. Various interposed arrangements or sequences are possible, depending for example on the total number of heatsink elements or devices used, the total number of cell groups present in the overall arrangement, and the manner in which the overall arrangement is designed to be folded into the finally configured battery module.

For example: in certain initial arrangements of cell groups in combination with one or more heatsink elements or devices, one or more selected ones of, but not all of, the cell groups may each have a cooling plate or other heatsink element or device attached thereto or faced thereon. In some such arrangements the one or more selected cell groups having a respective cooling plate or other heatsink element or device attached thereto or faced thereon may be non-adjacent or non-neighbouring with respect to each other in the overall initial side-by-side array of the cell groups. In other initial arrangements, at least one cooling plate or other heatsink element or device may even be interposed in sequence between any given pair of adjacent cell groups. Combinations of any of the aforementioned arrangements may also be possible. However, generally it may be preferred that a given heatsink element or device, especially that in the form of an internally cooled cooling plate as mentioned above, is - in the finally configured arrangement of cell groups forming the battery module - in thermal contact with as many cells as conveniently possible, subject to overall space and configurational constraints, in order to maximise the cooling efficiency of a given flow of cooling fluid through the cooling plate(s) whilst simplifying and minimising as far as possible the provision of and connections to and from an external cooling fluid source and/or flow control and/or pumping arrangement.

Where one or more heatsink devices or elements are provided, they may in practice be arranged in combination with the respective cell groups as part of, or prior to, the step (i) of arranging the plurality of cell groups into the initial side-by-side array, or at least prior to the step (iii) of configuring the interconnected cell groups into the said face-to-face array to form the battery module.

In embodiments of the invention the or each cell or cell group, whether or not housed within a frame or cassette, may be provided in combination with one or more compression element(s) or device(s), e.g. one or more foam pad(s), which may be provided within the said frame or cassette, where such is used to contain the cell or cell group. The compression element(s) may be configured to ensure that pouch cells of a given battery module remain under a compressive stress, e.g. in accordance with many cell manufacturers' recommendations. In some embodiments the or each cell may preferably comprise a pair of terminal tabs (one positive and one negative) for connection thereto of a or a respective busbar element. Each tab may protrude or extend from, e.g. from a top face or edge of, the body of the or the respective cell (or, in the case of pouch cells, from the preferred frame or cassette used to contain the cell). The tabs may preferably protrude or extend generally upwardly when the cell groups are in their arranged condition ready for interconnection, in order to allow or facilitate ready access to the tabs of a relevant welding tool or item of equipment, which in preferred embodiments is an ultrasonic welding tool or item of ultrasonic welding equipment. In certain embodiments the pair of terminal tabs (one positive and one negative) for connection thereto of a or a respective busbar element may, instead of protruding or extending from the same face or edge of the body of the or the respective cell, protrude or extend outwardly from different, especially, opposite faces or edges of the body of the or the respective cell. For example, one of the terminal tabs may extend from a top face or edge thereof and the other of the terminal tabs may extend from an opposite bottom face or edge thereof. As another example, one of the terminal tabs may extend from a left side face or edge thereof and the other of the terminal tabs may extend from an opposite right side face or edge thereof. In all such embodiments the polarities of the respective terminal tabs of the various cells, as well as the shape and configuration of the respective busbar element(s) which connect them, may be selected appropriately, e.g. depending on the overall relative configurational arrangement of the cells forming the resulting battery module.

In some embodiments of the invention each cell group may comprise a single cell, so that the method involves arranging, interconnecting and configuring a plurality of individual, i.e. discrete, cells.

Thus, in one species of embodiments the method may comprise:

(i) arranging a plurality of individual, i.e. discrete, cells into a side-by-side array, wherein pairs of cell terminals in adjacent respective cells are adjacent one another;

(ii) interconnecting the cell terminals within each respective pair via a or a respective busbar element so as to interconnect adjacent cells; and then

(iii) configuring the interconnected cells into a face-to-face array to form the said battery module.

However, in other embodiments each cell group may comprise a plurality of, e.g. 2, 3, 4 or even more, discrete cells, optionally pre-interconnected and, pre-configured into the said cell group.

Such cell groups which each comprise a plurality of cells may take various physical configurational forms: In one such configurational form the or each cell group may comprise a plurality of cells arranged in a mutually face-to-face manner, whereby said plurality of cells form a cell stack which constitutes the said cell group. In another such configurational form the or each cell group may comprise a plurality of cells arranged in a mutually side-by-side manner, whereby said plurality of cells form a cell sub-array which constitutes the said cell group. In such a cell sub-array, the cells may preferably be arranged or juxtaposed in a generally substantially linear or planar sub-array.

In one embodiment of either of the above configurational forms, the plurality of discrete cells may be pre-interconnected prior to being configured into the respective cell stack or sub-array. However, in an alternative embodiment of either of the above configurational forms, the plurality of discrete cells may be interconnected subsequently to their being configured into the respective cell stack or sub-array. Such interconnecting may be a discrete step prior to, or possibly may be substantially simultaneously with, the step (ii) of interconnecting adjacent cell terminals by the respective busbar element(s).

In some preferred embodiments each cell group may comprise 2 or 3 discrete cells, optionally pre-interconnected and, pre-configured into a cell stack or sub-array which constitutes the said cell group. Preferably the or each such cell stack or sub-array, whether formed from 2, 3 or more than 3 discrete cells, may correspond to, or may be or may be comprised by, a battery module made according to the above-defined method of the first aspect of the invention. Thus, in another species of embodiments the method may comprise:

(i) arranging a plurality of cell pairs into a side-by-side array, each cell pair comprising 2, optionally pre-interconnected and, pre-configured cells in face-to-face or side-by-side relative spatial relationship within that pair, wherein pairs of cell terminals in adjacent respective cell pairs are adjacent one another;

(ii) interconnecting the cell terminals within each respective pair via a or a respective busbar element so as to interconnect adjacent cell pairs; and then

(iii) configuring the interconnected cell pairs into a face-to-face array to form the said battery module. Accordingly, in embodiments of the preceding species, each cell pair may thus comprise a pair of cells arranged either face-to-face relative to each other, i.e. as a 2-cell cell stack, or side-by-side relative to each other, i.e. as a 2-cell cell sub-array.

Thus, in yet another species of embodiments the method may comprise:

(i) arranging a plurality of cell stacks or cell sub-arrays into a side-by-side array, each cell stack or sub-array comprising 3 or more, optionally pre-interconnected and, pre-configured cells in face-to-face or side-by-side, as the case may be, relative spatial relationship within that cell stack or sub-array, wherein pairs of cell terminals in adjacent respective cell stacks or sub-arrays are adjacent one another;

(ii) interconnecting the cell terminals within each respective pair via a or a respective busbar element so as to interconnect adjacent cell stacks or sub-arrays; and then (iii) configuring the interconnected cell stacks or sub-arrays into a face-to-face array to form the said battery module.

Accordingly, in embodiments of the preceding species, each cell stack or sub-array, as the case may be, may thus comprise 3 or more cells arranged either face-to-face relative to each other, i.e. as a 3-cell cell stack, or side-by-side relative to each other, i.e. as a 3- cell cell sub-array.

In some forms of each of the above preceding two species embodiments, it may be preferred that each of the defined, optionally pre-interconnected and, pre-configured cell pairs or cell stacks or cell sub-arrays is, or is comprised by, a battery module formed by the method according to the above-defined first-mentioned species embodiment. However, in other forms of the above preceding two species embodiments, it may be possible for each of the pre-interconnected and pre-configured cell pairs or cell stacks or cell sub-arrays to be, or be comprised by, any other known design of battery module assembled or formed by any known method.

In the assembly of any pre-interconnected and pre-configured cell pairs or cell stacks or cell sub-arrays, whether according to a method of the present invention or any known method, if desired or if necessary one or more locating and/or anchoring means, e.g. including one or more guide posts, may be employed to facilitate the correct positioning of a busbar element during assembly. The one or more guide posts may facilitate the correct positioning of a busbar element during configuring of the cell groups into a face- to-face array to form the said battery module.

In some embodiments the step (i) of arranging a plurality of cell groups into a side-by- side array, wherein pairs of cell terminals in adjacent respective cell groups are adjacent one another, may comprise arranging or juxtaposing the cell groups into a generally linear or planar array. This may serve to facilitate or optimise the second step of interconnecting the cell groups via the respective busbar element(s).

It is an important and distinguishing feature of the present invention that the step (ii) of interconnecting the adjacent cell terminals via a or a respective busbar element so as to interconnect adjacent cell groups is carried out prior to the step (iii) of configuring the interconnected cell groups into a battery module.

In certain embodiments, in particular those in which each cell group comprises a plurality of cells, whether in the form of a face-to-face cell pair or stack or side-by-side cell sub- array, the step (ii) of interconnecting the adjacent cell terminals via a or a respective busbar element so as to interconnect adjacent cell groups may, in addition to effecting interconnection between adjacent cell groups, also effect interconnection of the relevant terminals of individual cells within each group.

In the step (ii) of interconnecting the adjacent cell terminals via a or a respective busbar element so as to interconnect adjacent cell groups, the resulting arrangement may preferably be such that all the cells of the battery module are interconnected into a series electrical arrangement. Alternatively the resulting arrangement may be such that all the cells of the battery module are interconnected into a parallel electrical arrangement. In some embodiments, where a cell group comprises a plurality of cells, the cells of (i.e. within) the cell group may be connected in a parallel arrangement, or alternatively in a series arrangement. The cell groups may themselves be connected in series. Alternatively the cell groups may be connected in parallel.

In some embodiments the step (ii), of interconnecting the adjacent cell terminals via a or a respective busbar element so as to interconnect adjacent cell groups, may preferably be carried out by ultrasonic welding.

Suitable ultrasonic welding techniques and equipment will be readily available and well known to persons skilled in the art. One useful ultrasonic welding system which may be used is a sonotrode system. Ultrasonic welding may be especially preferred in embodiments of the invention as it permits the formation of reliable joints in cases where adjacent cell terminals to be interconnected are of different metals, as is the case with the preferred pouch cells to which preferred embodiments of the invention are especially applicable. The present method is particularly, but not exclusively, beneficial to embodiments of the invention comprising ultrasonic welding because it facilitates access to the cell terminals for the ultrasonic weld tools. As described above, this has been precluded hitherto in conventionally assembled battery modules because of the restricted space between adjacent cell terminals and the size and configuration of the weld tools.

In embodiments the or each busbar element may be substantially or predominantly of a monometallic material, e.g. substantially or predominantly of copper (or copper-rich alloy) or aluminium (or aluminium-rich alloy).

In some embodiments the or each busbar element may be of a flexible or bendable material. This is in order to facilitate the bending or flexing of the or each busbar element as the cells which they interconnect are configured in step (iii) into the battery module. A preferred such material is a braided, foil, or ribbon material, e.g. a copper (or copper-rich) braid, foil or ribbon, or an aluminium (or aluminium-rich) braid, foil or ribbon.

In some embodiments the step (iii) of configuring the interconnected cell groups face-to- face into a battery module may comprise overlaying or overlapping or stacking (e.g. in a generally horizontal or vertical, or some other oriented, plane) the respective cell groups relative to each other in a face-to-face manner, so as to form a cell stack, which may itself constitute the battery module. In some embodiments this preferred configuring of the interconnected cell groups in step (iii) may comprise configuring the cell groups, e.g. by bending or folding of the respective busbar elements which interconnect them, into one or more cell group pairs, with the cell groups in each pair being oriented oppositely (i.e. back-to-front) from each other. In this manner the resulting configured array may thus be of the nature of a "concertina" arrangement.

In some embodiments of the invention the method may further comprise:

(iv) securing the configured interconnected cell groups together to form the battery module.

Such securing together of the configured interconnected cell groups together may be by any suitable means, for example one or more retaining and/or locking means, e.g. one or more straps, plates, clips, detents, brackets or any combination thereof. In some embodiments such a securing together of the configured cell groups may conveniently be by use of a pair of end-plates, optionally in combination with at least one securing strap or band. Such end-plates may advantageously provide or carry external connection terminals (one positive, one negative) for connection of the finished battery into or to the electrical system into which it is destined for use. To this end, appropriate internal connections may be made between the connection terminals of the respective end-plates and respective terminal busbar elements of the cell array, typically busbar elements at opposite ends of the cell array. In another aspect of the invention for which protection is sought there is provided a battery module or a battery stack as or when made by a method according to any other aspect or any embodiment thereof.

Thus, in accordance with yet another aspect of the invention for which protection is sought there is provided a battery module per se (whether or not made by the method of any other aspect of the invention), comprising:

a plurality of electrochemical cells forming one or more cell groups and configured in a face-to-face array,

wherein pairs of cell terminals in adjacent respective cell groups are adjacent one another (and preferably of opposite polarity), the cell terminals within each respective pair being interconnected via a or a respective busbar element so as to interconnect adjacent cell groups of the array,

wherein the or each busbar element is connected to a respective cell terminal by ultrasonic welding,

and wherein the or each busbar element is of a flexible or bendable material.

In embodiments of the preceding aspect the or each busbar element may be substantially or predominantly of a monometallic material, e.g. substantially or predominantly of copper (or copper-rich alloy) or aluminium (or aluminium-rich alloy), and optionally additionally the or each cell may comprise a pouch cell, e.g. a lithium ion pouch cell, especially with a pair of respective terminals which comprise different metals, e.g. aluminium and nickel-coated copper.

In another aspect of the invention for which protection is sought there is provided a battery for an electric vehicle, comprising one or more battery modules according to any other aspect or any embodiment thereof, or made according to a method of any other aspect or any embodiment thereof.

In another aspect of the invention for which protection is sought there is provided an electric vehicle including a battery according to the preceding aspect or any embodiment thereof. Thus, in practical implementation of embodiments of the invention, a plurality of battery modules according to any one or more aspect(s) of the invention or any embodiment(s) thereof, or made according to any method according to any one or more aspect(s) of the invention or any embodiment(s) thereof, may be assembled or configured together and their terminals interconnected as appropriate to form a complete battery, especially a battery for an electric vehicle. Practical details of such implementations may be in accordance with existing knowledge in the art, so will be readily understood and readily available to persons skilled in the art.

Embodiments of the invention may be applied to the production of batteries for a wide variety of electric vehicles, such as cars, vans, goods or freight vehicles, motorcycles, road vehicles for public transportation such as buses, trains, trams, cable-carried vehicles, water-borne vehicles or craft, aircraft and even spacecraft. Such vehicles may include wholly electrically driven vehicles, or alternatively may include any type of hybrid vehicle.

In another aspect of the invention for which protection is sought there is provided a method of making a battery module comprising a plurality of interconnected cells (e.g. pouch cells), each cell having a plurality of terminals, the method comprising:

(i) arranging a plurality of cell groups, each group comprising 1 , 2, 3 or more individual cells, into a side-by-side array, wherein pairs of cell terminals in adjacent respective cell groups are adjacent one another, and preferably of opposite polarity;

(ii) interconnecting the adjacent cell terminals within each respective pair via a or a respective busbar element, e.g. of a flexible, braided, monometallic material, preferably by ultrasonic welding, so as to interconnect adjacent cell groups; and then, subsequent to step (ii),

(iii) configuring the interconnected cell groups, e.g. by folding, into a face-to-face array to form the said battery module.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS Some embodiments of the present invention will now be described in detail, by way of example only, with reference to the accompanying drawings, in which:

FIGURE 1 is a schematic illustration showing three cell stacks or groups for forming part of a battery module according to embodiments of the invention, each stack being of two cells and the stacks being arranged into a side-by side array and interconnected to one another in a hinged manner;

FIGURE 2(a) is an exploded perspective view of one of the cell pairs of the array of FIG. 1 , which is a group of 2 cells in the form of a stack of 2 cell cassettes, showing its various structural components;

FIGURE 2(b) is a perspective view of the cell group of FIG. 2(a) shown in its assembled state but prior to installation of a bridge member;

FIGURE 3(a) is an exploded perspective view of the cell array used to form the battery module, showing the cell pairs arranged and ready for having their respective terminals interconnected by respective busbar elements;

FIGURE 3(b) is a perspective view corresponding to FIG. 3(a), showing the respective terminals having been interconnected by the respective busbar elements, and before the configuring of the array into the battery module;

FIGURE 4 is a close-up perspective view of part of the arranged cell array of FIGS. 3(a) and (b), showing more clearly the connections of the busbar elements to adjacent cell terminals;

FIGURES 5(a) and 5(b) are perspective views of the array of FIG. 3(b), showing the cell pairs in sequential stages of being configured by folding and face-to-face overlaying into the battery module;

FIGURE 6 is a perspective view of a complete battery module according to a first embodiment of the invention, which comprises 12 interconnected groups of two cells or cell pairs, i.e. 12 cell stacks each comprising 2 pre-assembled (i.e. pre-interconnected and pre-configured) cells;

FIGURE 7(a) is an enlarged perspective view of an upper portion of the complete battery module of FIG. 6, showing in detail an example of the upper hinged connections between the individual cell cassettes;

FIGURE 7(b) is similar to FIG. 7(a) but is an enlarged perspective view of a lower portion of the complete battery module of FIG. 6, showing in detail an example of the lower hinged connections between the individual cell cassettes;

FIGURE 8 is a perspective view of a complete battery module according to a second embodiment of the invention, which comprises 8 interconnected cell stacks each comprising 3 preassembled (i.e. pre-interconnected and pre-configured) cells; FIGURE 9(a) is a perspective view of an alternative form of cell suitable for use in certain embodiments of the invention, which cell has a different arrangement of terminal tabs;

FIGURE 9(b) is a perspective view, corresponding to that of FIG. 5(b), showing an example of such an embodiment utilising a plurality of the alternative cells of FIG. 9(a) in the process of being configured into the final array of an alternative battery module;

FIGURE 10 is a schematic perspective view of an arrangement of end-plates and strap for finally securing together the cell groups of the array forming the battery module of any of the preceding embodiments of the invention;

FIGURES 1 1 (a), 1 1 (b) and 1 1 (c) are schematic illustrations of various manners in which cell groups may be electrically connected;

FIGURE 12 is a perspective view of a complete battery module according to a third embodiment of the invention, which comprises 24 series-interconnected cells arranged in 8 cell groups, each cell group being a cell sub-array formed by 3 side-by-side pre-interconnected cells and thermally contacting, in the finally configured array forming the battery module, one side of a respective one of a total of 4 liquid-cooled heatsinks;

FIGURE 13 is an exploded perspective view of the battery module of FIG. 12, showing its various structural components and in particular the two battery sub-modules each formed by foldingly configuring a particular array of cell groups and associated heatsinks as shown in FIGS. 15 & 16;

FIGURE 14(a) is a perspective view of an example form of heatsink element used in conjunction with the various cells to form the battery module of FIGS. 12 & 13;

FIGURE 14(b) is a perspective view of an alternative form of heatsink element, which has a different arrangement of input and output nozzles or nipples;

FIGURES 15(a) - 15(f) are simplified illustrative perspective views of one array of already interconnected cell groups and their associated heatsinks, each cell group being a 3-cell sub-array, as used to form one of the sub-modules (i.e. half) of the battery module of FIGS. 12 & 13, showing in sequential stages one manner in which the interconnected cell sub-arrays and heatsinks are configured into the said sub-module by folding and face-to-face overlaying; and

FIGURES 16(a) - 16(h) are simplified illustrative perspective views of the same array of already interconnected 3-cell sub-arrays and their associated heatsinks as in FIG. 13, but showing in sequential stages another manner in which the interconnected cell sub-arrays and heatsinks are configured into the said sub-module by folding and face-to-face overlaying.

DETAILED DESCRIPTION OF EMBODIMENTS FIG. 1 is a schematic illustration showing a portion of an arrangement of components of an electrochemical battery module during a process of assembly to form such a module. The portion of the arrangement shown in FIG. 1 has three cell groups or cell stacks 120, each cell group 120 having two cell cassettes 1 10 (FIG. 2) provided in a stacked arrangement. Each cell cassette has a single electrochemical cell 1 18. In the present embodiment the cells 1 18 are rechargeable, although in some embodiments the cells 1 18 may not be configured to be rechargeable.

The cell groups 120 are shown in FIG. 1 in a side-by side array and interconnected to one another in a hinged manner. Each group 120 has a front face 120F and a rear face 120R, the groups 120 being arranged in FIG. 1 such that the front faces 120F (and therefore also the rear faces 120R) of adjacent groups 120 face in opposite directions. Each group 120 has first and second terminal portions 120T1 , 120T2 respectively. The first terminal portion 120T1 provides an electrical connection to a positive electrode of the cells 1 18 of the group 120 whilst the second terminal portion 120T2 provides an electrical connection to negative electrodes of the cells 1 18 of the group 120. As noted above, each group 120 is formed by a stack of two cell cassettes 1 10 as shown in FIG. 2. FIG. 2(a) is an exploded view of a single group 120 of two cell cassettes 1 10, whilst FIG. 2(b) shows the group 120 with the cassettes assembled and coupled to each other prior to installation of a bridge member 162 that forms part of the cell group 120. With reference to FIG. 2(a), each cell cassette 1 10 has an electrochemical pouch cell 1 18 formed in a known manner and which is provided within a cassette housing. The cassette housing has a back plate 1 12, a cassette frame 1 14 and a spacer member 1 16. The back plate 1 12 functions as a heatsink for the pouch cell 1 18. The back plate 1 12 is in the form of a pressed aluminium structure having a substantially flat, rectangular base portion 1 12B and side tabs 1 12T projecting from three sides of the base portion 1 12B in a direction normal to the base portion 1 12B to define a tray having one open edge. The cassette frame 1 14 is in the form of an open rectangular frame having a size and shape corresponding to that of the back plate 1 12 such that the frame 1 14 may be fitted snugly within the tray defined by the back plate 1 12. A depth 1 14d of the frame corresponds to a depth 1 12d of the tray defined by the back plate 1 12.

The spacer member 1 16 is in the form of a sheet of resiliently compressible material sized to fit within an aperture 1 14A defined by the frame 1 14. In the present embodiment the spacer member 1 16 is formed from a foamed material.

The electrochemical pouch cell 1 18 is of a known type and has a pair of electrical terminals 1 18T1 , 1 18T2 projecting from a free edge 1 18e of the cell 1 18, the terminals being of first and second type 1 18T1 , 1 18T2 respectively. In the present embodiment terminals of the first type 1 18T1 are of positive polarity, whilst terminals of the second type 118T2 are of negative polarity. The cell cassette 1 10 is arranged such that in assembled form the frame 1 14 fits within the tray defined by the back plate 1 12 as described above, with the pouch cell 1 18 provided within the frame 114. The spacer member 1 16 is sandwiched between the plate portion 1 12B of back plate 1 12 and the pouch cell 1 18. A pair of elongated fixing elements 1 19 are employed to secure the cell 1 18 to the frame 1 14. In the present embodiment the fixing elements 1 19 are in the form of elongate bars having pin elements projecting from one side of the bar at opposite ends of the bar. In the assembled configuration the pin elements pass through the cell 1 18 and are secured to one side of the frame 1 14. During manufacture, assembled cell cassettes 1 10 are stacked one on top of the other in pairs and a bridge member 162 is placed over one end of each stack of two cassettes 1 10. The bridge member 162 is shown in perspective view in FIG. 2(a). The bridge member is in the form of a cap arranged to fit over one end of the stack. A pair of apertures 162AT1 , 162AT2 are provided in the bridge member 162 at locations corresponding to that of the terminals 1 18T1 , 1 18T2 of the cells 1 18 of each cell group 120. During assembly the terminals 1 18T1 , 1 18T2 are passed through the respective apertures 162AT1 , 162AT2 as the bridge member 162 is placed over one end of a pair of cassettes 1 10. At the same time, two pairs of locator posts 1 14P protruding upwardly from the upper periphery of the assembled frame 1 14 pass through respective locator apertures 162L provided in the bridge member 162 adjacent each end thereof, in order to facilitate the location of the apertures 162AT1 , 162AT2 over the respective terminals 1 18T1 , 1 18T2. In this condition, each aperture 162AT1 , 162AT2 has two terminals protruding therethrough. In the present embodiment, the cells 1 18 of each cell group are connected in parallel, such that the first terminals 1 18T1 of the cells 1 18 of one group 120 pass through one aperture 162AT1 , whilst the second terminals 1 18T2 of the cells 1 18 of the group 120 pass through the other aperture 162AT2. The bridge member 162 also has four pairs of guide posts 162P, one at each end of each of the apertures 162AT1 , 162AT2, the posts 162P of each pair being on opposite sides of the associated aperture 162AT1 , 162AT2. The guide posts 162P are positioned so as to assist management of movement of busbar members 130B (not shown in FIG. 2) described below. The busbar members 130B are employed to electrically connect adjacent cell groups 120.

Importantly, in the present embodiment cell groups 120 are formed of two different configurations, namely configuration I and configuration II. In configuration I, for each cassette 1 10 of a given group 120 having configuration I, the terminals of first type 1 18T1 are positioned on the left of the group 120 as viewed in the direction of front face 120F (at which the cell 1 18 of one cassette 1 10 is exposed) and the terminals of the second type 118T2 are positioned on the right. Conversely, in configuration II, for each cassette 1 10 of a given group 120 having configuration II, the terminals of first type 1 18T1 are positioned on the right of the group 120 as viewed in the direction of front face 120F and the terminals of the second type 1 18T2 are positioned on the left. FIG. 3(a) is a schematic illustration showing the cell groups 120 in exploded view prior to joining in a hinged manner as shown in FIG. 1 . FIG. 3(a) also shows the busbar members 130B prior to connection to the cell groups 120. As can be seen from FIG. 3(a), the cell groups 120 are arranged such that adjacent cell groups 120 are of alternate configuration. In the arrangement of FIG. 3 the left-most cell group (labelled 1201) is of configuration I, the next cell group in the series (labelled 12011) being of configuration II. The next cell group is of configuration I , and so forth in an alternating manner along the series of groups 120.

FIG. 3(b) shows the cell groups 120 of FIG. 3(a) after adjacent groups 120 have been connected together by means of the busbar members 130B.

FIG. 4 is an enlarged view showing the manner in which the busbar members 130B are attached to the groups 120. It is to be understood that, because the cell groups 120 are arranged alternately in configurations I and II, the first terminals 1 18T1 of the two pouches 1 18 of one group 120 are connected to the second terminals 1 18T2 of the pouches 1 18 of the next, adjacent group 120, such that the cell groups 120 are connected electrically in series. The busbar members 130B are joined to the terminals 1 18T1 , 1 18T2 by ultrasonic welding in the present embodiment, e.g. using a sonotrode ultrasonic welding apparatus/system, examples of which are readily available in the art, e.g. the 20kHz ultrasonic spot welding system supplied by Sonics & Materials, Inc. of Connecticut, USA. The welding process causes each end of the busbar member 130B to be electrically connected to the respective terminal 1 18T1 , 1 18T2 presented to it, the pair of terminals protruding through a given aperture also being joined to one another by the welding operation.

Following joining of the busbar members 130B to the terminals 1 18T1 , 1 18T2 such that the cell groups 120 are connected electrically in series, the assembly of groups 120ASS shown in FIG. 3(b) is folded as shown in FIGS. 5(a) and 5(b) to form an electrochemical battery module 100 as shown in FIG. 6. Straps (not shown) may be wrapped around the module 100 to retain the module 100 in the folded configuration of FIG. 6. In some embodiments the cell groups 120 may be arranged to couple to one another when folded into the face-to-face configuration in which they are provided in the arrangement of FIG. 6. For example, in some arrangements the cell groups 120 may be arranged to snap-lock together. This may be achieved in some embodiments by providing complementary inter-engaging formations that allow coupling, for example by means of a detent arrangement or the like.

Alternatively or in addition, in some embodiments the cell groups 120 may be arranged to couple to one another when folded into the back-to-back configuration in which they are also provided in the arrangement of FIG. 6.

As one example of the manner in which the individual cell cassettes 1 10 of the battery module 100 of FIG. 6 may be connected and secured together, FIGS. 7(a) and 7(b) show in enlarged detail the construction of the upper and lower (respectively) hinge connections between the individual cell cassettes 1 10 of the complete battery module 100 of FIG. 6.

Each hinge connection comprises two halves formed from a respective pair of hinge lugs 174a, 184a (or 174b, 184b in the case of the lower hinge connections), protruding outwardly from respective side walls of the respective frames 1 14 of the respective cassettes 1 10. Each hinge lug 174a, 184a, 174b, 184b may conveniently be formed integrally, e.g. by moulding, with the respective section of its respective frame 1 14. The hinge lugs of each respective pair 174a, 184a; 174b, 184b are mutually interconnectable or interlockable by a snap-fit or click-together arrangement (not shown), for example a vertically oriented (with respect to the drawing) pin-in-hole arrangement or alternatively by means of a clip element on one of the lugs 174a (or 174b) engaging horizontally (with respect to the drawing) with a corresponding anchoring toe formed on the other of the lugs 184a (or 184b).

The orientation and arrangement of the respective pairs of hinge lugs 174a, 184a; 174b, 184b on each cassette frame 1 14 are preferably such that any given two-part hinge on any cassette frame 1 14 can be used either (i) to connect together individual discrete cassette frames 1 14 of adjacent cassettes 1 10 in the forming of a given cell group 120 (such as that shown in FIG. 2), before the group 120 is interconnected to another by a respective busbar member 130B, or alternatively (ii) to unite and secure together neighbouring cell groups 120, after their individual assembly and interconnection by the respective busbar members 130B, once they have been configured (e.g. folded) into the final array to form the battery module as shown in FIG. 6.

As shown in FIGS. 7(a) and 7(b), the upper and lower hinge sections may essentially be the same in construction and operation, so that each cell cassette 110 is hingedly connected to each of its immediately neighbouring cassettes 1 10 at or near the top and bottom of each of its lateral sides in a like manner. It is however possible in other embodiments to provide more than two, e.g. three or even more, such hinge connections on any given lateral side of each cassette 1 10.

Although embodiments incorporating hinge connections between respective cell cassettes 1 10, as shown by way of example in FIGS. 7(a) and 7(b), may in many instances be preferred, it is to be understood that in other embodiments such hinge connections may be dispensed with altogether, thereby leading to cassette frames with somewhat simpler constructions, e.g. leading to simpler mouldings. For example, in such embodiments without integral moulded hinges to interconnect neighbouring cassettes, either during the assembly of individual cell groups and/or the groups' overall configuring (e.g. by folding) into the final battery module, the necessary configuring of the respective cassettes may be done manually (with appropriate care) or, possibly preferably, using an external hinged assembly, frame, former or like fixture to bring the cassettes together and unite them in the required relative configuration.

FIG. 8 shows a battery module 200 made according to a further embodiment of the invention. Like features of the module 200 of FIG. 8 to those of the module of FIGS. 1 to 7 are shown with like reference signs incremented by 100. In the module of FIG. 8 each cell group 220 has three cell cassettes 210 coupled together in series. The three cell cassettes 210 of each cell group 220 are arranged such that the pouch cells 218 of the group 220 are coupled to one another in parallel, as in the embodiment of FIG. 1 .

Turning to FIG. 9(a), here there is shown an alternative form of cell 1 18' suitable for use in certain embodiments of the invention. This alternative cell 1 18' has its terminal tabs 1 18T1 ', 1 18T2' (one positive and one negative) located at opposite ends of the cell body, e.g. protruding outwardly from each of its top and bottom ends, instead of both extending from the same (top) end as in the embodiment of FIG. 2. FIG. 9(b), which corresponds to FIG. 5(b), shows the corresponding arrangement of a plurality of such alternative cells 1 18', showing the various terminal tabs 1 18T1 ', 1 18T2' of the cell pairs 120' having been interconnected by the respective busbar elements 130B', some above and some below the configured array, in the process of being configured by folding and face-to-face overlaying into the final array of an alternative battery module.

Any of the embodiment battery modules within the scope of the invention, including any of those specifically described above, may have their finally configured cell groups secured together by any suitable means, e.g. any combination of one or more straps, plates, clips, detents or brackets. By way of a schematic example, FIG. 10 shows one such arrangement for securing together an array of cell groups constituting a battery module 100, 200 into its final configuration. In this schematic example a pair of tray- shaped end-plates or pressure-plates 350a, 350b, e.g. of cast aluminium or aluminium alloy or a moulded plastics material or composite material, each with a planar end face 352 and a perimeter flange 354 protruding perpendicularly therefrom, encloses a respective side portion of the configured array. The whole arrangement is secured together by a strap or band 360, e.g. of stainless steel, which is passed therearound and whose ends are secured by any suitable means, e.g. a clasp or like device. The respective end-plates 350a, 350b further provide the necessary external connection terminals 370a, 370b (one positive, one negative) for connection of the finished battery into or to the electrical system into which it is destined for use, e.g. that of a vehicle, by appropriate internal connections to the respective terminals 370a, 370b of the respective terminal ones of the respective busbar elements 130B of the cell array of the finally assembled battery module 100, 200.

FIG. 1 1 illustrates various ways in which cell groups 120 according to the various embodiments of the present invention may be electrically connected: FIG. 1 1 (a) is a circuit diagram showing two cell groups, each having only a single cell cassette 1 10, connected in series;

FIG. 1 1 (b) is a circuit diagram showing two cell groups, each having two cell cassettes 1 10 connected in parallel, connected in series;

FIG. 1 1 (c) is a circuit diagram showing two cell groups, each having three cell cassettes 1 10 connected in parallel, connected in series.

Turning to FIGS. 12 to 16 collectively, these Figures show another embodiment of battery module 400 made according to the invention, which is based on a different relative spatial arrangement of the twenty-four cells 418 arranged into respective cell groups 420 which together make up the final battery module 400. In this embodiment the twenty-four cells 418 are arranged in first and second arrays or sub-modules 410a, 410b each of which comprises four cell sub-arrays 420. Each cell sub-array 420 comprises three side-by-side linearly juxtaposed cells 418 which thus constitutes a cell group. The individual cells 418, e.g. lithium ion cells, within each sub-array 420 are pre- interconnected via their adjacent terminals (not marked, for clarity) by respective busbar elements 430, e.g. by ultrasonic welding or another known technique. Preferably the terminals of immediately adjacent cells 418 within each sub-array 420 may be of opposite polarity so that within each cell sub-array 420 the cells 418 are interconnected in a series electrical arrangement. Likewise the terminals of immediately adjacent cells 418 in respective adjacent sub-arrays 420 may also preferably be of opposite polarity so that the adjacent sub-arrays may likewise be interconnected in an overall series electrical arrangement. As in the other embodiments illustrated in the preceding drawings and described above, each cell 418 may if desired or necessary be housed or supported within a supporting frame or cassette, e.g. of injection moulded plastics material, whose overall construction may be as before, including its hinged connection to adjacent cell frames/cassettes in order to allow adjacent cell sub-arrays 420 to be readily hingeable with respect to its neighbouring sub-arrays 420. This degree of freedom is particularly useful in the folding up of the sub-arrays 420 of each of the first and second arrays or sub-modules 410a, 410b during the step of configuring the interconnected cell sub-arrays 420 into the final battery module 400. Optionally each cell sub-array 420 itself may if desired be supported by or mounted within some form of frame arrangement, e.g. of a similar type to that used to support and contain individual cells. Such sub-array frames may, if present, serve to not only maintain an optimum separation between the respective cooling plates 412, but they may also serve as a means of maintaining optimum lateral support and separation of the individual cells 418 themselves. Such sub-array frames may furthermore, if present, also provide a convenient means of accommodating foam compression pads which apply controlled pressure to the surface of the individual cells 418 in accordance with cell manufacturer recommendations. Such pressure may in practice be tailored for optimum efficacy, e.g. by the depth of the frame which controls the extent of foam compression and by selection of foam with appropriate compression force deflection characteristics. As shown in FIGS. 15(a) and 16(a), which actually both show the same side-by-side array or sub-module 410a or 410b in its state once the cell sub-arrays 420 have been arranged in that side-by-side array in step (i) and interconnected in step (ii) via their adjacent terminals by respective busbar elements 430, certain ones of the sub-arrays 420 have associated therewith a respective heatsink element in the form of a cooling plate 412. In the example as illustrated, the two outermost cell sub-arrays 420 each have a respective cooling plate 412 faced thereon, e.g. by virtue of the cooling plate 412 being affixed to or supported by the cells' collective frame or cassette supporting arrangements, so that one major face of each respective cooling plate is in thermal contact with the respective faces of the cells 418 in the relevant sub-array 420. However the two innermost cell sub-arrays 420 do not have a cooling plate faced thereon, since each of those two sub-arrays will effectively share the same respective cooling plate as their immediately neighbouring respective sub-array 420, by virtue of coming into thermal contact with an opposite major face of that respective cooling plate as the whole array is folded up as shown in either of FIGS. 15 or 16.

One example of such a cooling plate is shown in FIG. 14(a). It is made of a heat- conductive material, e.g. a suitable metal or metal alloy, and has planar surfaces on both its major faces in order to maximise thermal contact area with the relevant cell faces. The interior of the cooling plate 412 has formed therein a series, array or network of internal channels or passages for passage therethrough of a cooling fluid, e.g. a cooling liquid or gas, which may be pumped therethrough by any suitable external supply and flow control apparatus (not shown). Any suitable pattern or arrangement of internal channels or passages may be used, preferably such as to achieve an optimum degree of temperature uniformity across the various cells with which the cooling plate is to be in thermal contact. Practical examples of suitable such cooling fluid supply and flow control systems are well known in the art. Input and output nozzles or nipples 412|_N, 412ουτ are provided for connection of the cooling plate 412 to the relevant cooling fluid supply and flow control apparatus. As shown, the input and output nozzles or nipples 412|_N, 412ουτ may be located both at the same end of the cooling pate 412. Optionally neighbouring or adjacent cooling plates 412 may be oriented oppositely with respect to one another, so that the respective input and output nozzles or nipples 412IN, 412OUT of neighbouring or adjacent cooling plates 412 are located at opposite ends of the resulting folded cell group arrangement. Alternatively neighbouring or adjacent cooling plates 412 may be oriented the same way round with respect to one another, so that the respective input nozzles or nipples 412_!N of neighbouring or adjacent cooling plates 412 are located at one common end of the resulting folded cell group arrangement, and the respective output nozzles or nipples 412ουτ of neighbouring or adjacent cooling plates 412 are located at the opposite common end of the resulting folded cell group arrangement. This arrangement may lead to better use of space and less crowding in the vicinity of the input and output nozzles or nipples 412|_N, 412ουτ, particularly where connections to the external cooling fluid supply and flow control apparatus is needed. Once the final folded cell group arrangement has been effected, if desired or necessary one or more respective manifold arrangements (not shown) may optionally be provided at one or both ends thereof (as appropriate, depending on the locations of the various input and output nozzles or nipples 412|_N, 412ουτ), for use in connecting up the respective input and output nozzles or nipples 412|_N, 412ουτ of the respective cooling plates 412 to the relevant cooling fluid supply and flow control apparatus.

In an alternative form of cooling plate 412', as shown in FIG. 14(b), the input and output nozzles or nipples 412'|_N, 412'ουτ may instead be located at opposite ends of the cooling plate 412', as shown. The input and output nozzles or nipples 412'IN, 412'OUT may if desired be reversed in their relative locations at the opposite ends of the cooling plate 412' from that shown in this drawing. As with the form of cooling plate 412 shown in FIG. 14(a), and again for the purpose of better use of space, in the use of the alternative form of cooling plate 412' shown in FIG. 14(b), optionally neighbouring or adjacent cooling plates 412' may be oriented oppositely, or alternatively the same way round, with respect to one another, so that either the respective input and output nozzles or nipples 412'|_N, 412 OUT of neighbouring or adjacent cooling plates 412' are located at opposite ends of the resulting folded cell group arrangement, or alternatively the respective input nozzles or nipples 412'|_N of neighbouring or adjacent cooling plates 412' are located at one common end of the resulting folded cell group arrangement and the respective output nozzles or nipples 412'OUT of neighbouring or adjacent cooling plates 412' are located at the opposite common end of the resulting folded cell group arrangement. Again, one or more appropriately located manifold arrangements may be provided for connecting up the respective input and output nozzles or nipples 412'|_N, 412'₀υτ to the relevant cooling fluid supply and flow control apparatus.

FIGS. 15(a) to 15(f) show in sequence one manner in which the various cell sub-arrays 420, in combination with their respective cooling plates 412, may be folded up and configured into a final face-to-face array or sub-module 410, as shown in its final form in FIG. 15(f). The relative movements of the various elements of the arrangements are illustrated schematically by the large arrows as shown, as will be self-explanatory. FIGS. 16(a) to 16(h) show in sequence an alternative manner in which the same cell sub-arrays 420, in combination with their same respective cooling plates 412, may be folded up and configured into the same final face-to-face array or sub-module 410, as shown in its final form in FIG. 16(h). Again, the relative movements of the various elements of the arrangements are illustrated schematically by the large arrows as shown, as will be self- explanatory. It will be noted that the two starting arrangements in FIGS. 15(a) and 16(a) are the same, as are the two final arrangements in FIGS. 15(f) and 16(h).

For ease of illustration and practicality, especially as regards availability and use of space and particularly in the case where a jig or other apparatus is used to support the various components of the arrangement during its assembly and folding up, it may be preferred, or at least convenient - as illustrated in these Figures - for each "half" of the complete battery module 400 to be assembled and configured separately as a discrete sub-module 410a, 410b. Each such sub-module 410a, 410b may thus itself constitute a "cell group" as defined in the broadest context of the present invention, so that the final steps of arranging the sub-modules 410a, 410b side-by-side, interconnecting the sub- modules' adjacent terminals via respective busbars, and the final configuring, e.g. by folding, of the sub-modules into their final configuration (as shown in FIG. 12) constituting the complete battery module 400, may constitute yet another embodiment of the present invention.

As shown in FIG. 13, various additional components of the overall arrangement may be provided for inclusion in or employed to effect the various configuring and assembly of the sub-modules 410a, 410b into the final, complete battery module 400. These may include final interconnection terminal tabs (or pairs thereof) 418T on each sub-module 410a, 410b, for final electrical interconnection of the sub-modules 410a, 410b to each other and of the completed battery module into a vehicle, or other, power supply system. Such final interconnections may be facilitated by the provision of an electrical connection manifold assembly 460 which, by way of example as shown, may include a bank of respective terminals 462 each for connection to a respective one of the interconnection terminal tabs 418T. The aforementioned additional components may further include respective front and rear supporting or compression frame panels 414a, 414b (e.g. of injection moulded plastics or a metal or metal alloy, e.g. aluminium), optional respective front and rear intermediate spacer sheet members 416a, 416b, e.g. of a relatively stiff plastics or metal material, sized to fit within the respective front and rear frame panels 414a, 414b, and securing straps or bands 450a, 450b, 450c (e.g. of stainless steel). It is to be understood that the above-mentioned intermediate spacer sheet members 416a, 416b may serve to provide thermal insulation from any cooling effect of the respective front and rear frame panels 414a, 414b, as well as evening out the distribution of loads arising from the outer frame panels 414a, 414b, especially when the latter are pocketed on the inside. The aforementioned additional components may further include one or more compression sheets or pads, such as those shown in FIG. 13 as 415a, 415b, 415c, 415d, 415e and 415f, e.g. of a foam or other resiliently deformable material, which are applied to at least one face of each of the cells 418 within each sub-module 410a, 410b in order to maintain, in the finished assembly, each cell 418 under a suitable desired compressive stress, e.g. in accordance with the relevant cell manufacturers' recommendations. Any suitable number and/or shape and size of such compression sheets or pads may be employed, for example tailored to match the major facial dimensions of individual cells 418 (as shown as 415a, 415b, ... etc in the drawing), or alternatively larger such compression sheets or pads may be used which for example span plural cells, such as all three cells 418 within a given cell sub-array 420. Any such compression sheets or pads may for example be self-adhesive, in order to assist their placement and retention during the overall assembly procedure. If desired or necessary, one or more additional such compression sheets or pads may be provided within each sub-module 410a, 410b, that is to say respective such additional such compression sheets or pads may be located between adjacent folded cell sub-arrays 420, in order to provide equivalent compressive cushioning to the cells 418 in the relevant sub-arrays 420 once they have been folded into each sub-module 410a, 410b. In this case, and in the context of the illustrated embodiment as shown in FIG. 13, the finished battery module may therefore include a total of 5, e.g. planar, banks of such compression sheets or pads, each of which is located between a respective pair of cell sub-arrays 420 in the finally assembly battery module 400. The outer frame panels 414a, 414b may further provide a means of securing or anchoring the battery module 400 within a vehicle or other end-use environment, e.g. by virtue of securing or anchoring apertures or lugs 490. Such outer frame panels 414a, 414b, or alternatively a pair of additional dedicated end plates (not shown in this group of Figures), may if desired usefully additionally accommodate the necessary positive and negative HV terminals for final connection of the complete battery module into a vehicle, or other, power supply system.

It is to be understood that the above description of some embodiments and aspects of the invention has been by way of non-limiting examples only, and various modifications may be made from what has been specifically described and illustrated whilst remaining within the scope of the invention as defined in the appended claims.

Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of those words, for example "comprising" and "comprises", mean "including but not limited to", and are not intended to (and do not) exclude other moieties, additives, components, integers or steps.

Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith.

Claims

1 . A method of making a battery module comprising a plurality of interconnected cells, each cell having a plurality of terminals, the method comprising:

2. A method according to Claim 1 , wherein the side-by-side arranging step (i) is such that adjacent cell terminals in adjacent respective cell groups are of opposite polarity.

3. A method according to Claim 1 or Claim 2, wherein each cell group comprises one or more discrete electrochemical cells.

4. A method according to any one of Claims 1 to 3, wherein the or each cell is a pouch cell, especially a pouch cell with a pair of respective terminals which comprise different metals.

5. A method according to Claim 4, wherein the or each cell, or the or each cell group in the case of a plurality of cells making up a respective cell group, is housed or contained within a frame or cassette.

6. A method according to Claim 5, wherein the or each frame or cassette comprises a hinge element or device, so that adjacent frames or cassettes, or pairs of frames or cassettes, are attachable to each other in a hingeing manner.

7. A method according to Claim 6, wherein each frame or cassette further comprises one or more retaining and/or locking means for securing neighbouring frames or cassettes together within the or each cell group, and/or between adjacent cell groups, as the case may be, and/or for securing neighbouring cell groups together once they have been configured into the battery module in step (iii).

8. A method according to any preceding Claim, wherein the or each cell is provided with at least one heatsink element or device in thermal contact therewith.

9. A method according to Claim 8, as depending through Claim 5, wherein the heatsink element or device is provided within the said frame or cassette.

10. A method according to any preceding Claim, wherein the or each cell is provided with a compression element or device.

1 1 . A method according to Claim 10, as depending through Claim 5, wherein the compression element or device is provided within the said frame or cassette.

12. A method according to any preceding Claim, wherein the or each cell comprises a pair of terminal tabs (one positive and one negative) for connection thereto of a or a respective busbar element.

13. A method according to any one of Claims 1 to 12, wherein each cell group comprises just a single cell, whereby the method involves arranging, interconnecting and configuring a plurality of individual, discrete cells.

14. A method according to any one of Claims 1 to 12, wherein each cell group comprise a plurality of discrete cells, optionally pre-interconnected and, pre-configured mutually face-to-face into a cell stack which constitutes the said cell group.

15. A method according to any one of Claims 1 to 12, wherein each cell group comprise a plurality of discrete cells, optionally pre-interconnected and, pre-configured mutually side-by-side into a cell sub-array which constitutes the said cell group.

16. A method according to Claim 14 or Claim 15, wherein each cell group comprises 2 or 3 discrete cells, optionally pre-interconnected and, pre-configured into the said cell stack or cell sub-array, as the case may be, which constitutes the said cell group.

17. A method according to any one of Claims 14 to 16, wherein each cell group comprising the plurality of discrete, optionally pre-interconnected and, pre-configured cells is, or is comprised by, a battery module made according to the method of any one of Claims 1 to 12.

18. A method according to any one of Claims 14 to 17, wherein in the assembly of any of the said, optionally pre-interconnected and, pre-configured cell pairs or cell stacks or cell sub-arrays, as the case may be, one or more locating and/or anchoring means is/are employed to facilitate the correct relative positioning of adjacent cells prior to or during their assembly into the respective cell pair or cell stack or cell sub-array, as the case may be.

19. A method according to any preceding Claim, wherein the step (i) of arranging a plurality of cell groups into a side-by-side array, wherein pairs of cell terminals in adjacent respective cell groups are adjacent one another, comprises arranging or juxtaposing the cell groups into a generally linear or planar array.

20. A method according to any one of Claims 14 to 19, wherein:

(i) the plurality of discrete cells are pre-interconnected prior to being configured into the respective cell stack or sub-array; or

(ii) the plurality of discrete cells are interconnected subsequently to their being configured into the respective cell stack or sub-array, and the interconnecting is either a discrete step prior to, or substantially simultaneously with, the step (ii) of interconnecting adjacent cell terminals by the respective busbar element(s).

21 . A method according to any preceding Claim, wherein in the step (ii) of interconnecting the adjacent cell terminals via a or a respective busbar element so as to interconnect adjacent cell groups, the resulting arrangement is such that all the cells of the battery module are interconnected into a series electrical arrangement.

22. A method according to any preceding Claim, wherein the step (ii) of interconnecting the cell terminals via a or a respective busbar element so as to interconnect adjacent cell groups, is carried out by ultrasonic welding.

23. A method according to any preceding Claim, wherein the or each busbar element is substantially or predominantly of a monometallic material.

24. A method according to any preceding Claim, wherein the or each busbar element is of a flexible or bendable material.

25. A method according to Claim 24, wherein the material of the or each busbar element is a braided, foil, or ribbon material.

26. A method according to any preceding Claim, wherein the step (iii) of configuring the interconnected cell groups face-to-face into a battery module comprises overlaying or overlapping or stacking the respective cell groups relative to each other in a face-to-face manner so as to form a cell stack.

27. A method according to Claim 26, wherein the configuring of the interconnected cell groups in step (iii) comprises configuring the cell groups by bending or folding of the respective busbar elements which interconnect them, into one or more cell group pairs, with the cell groups in each pair being oriented oppositely from each other so as to form a concertina-type arrangement.

28. A method according to any preceding Claim, wherein the method further comprises:

29. A battery module as or when made by a method according to any one of Claims 1 to 28.

30. A battery cell stack for use as the cell group in a method according to any one of Claims 1 to 28, the battery cell stack itself being a battery module formed by a method according to any one of Claims 1 to 28.

31 . A battery cell sub-array for use as the cell group in a method according to any one of Claims 1 to 28, the battery cell sub-array itself being a battery module formed by a method according to any one of Claims 1 to 28.

32. A battery module comprising:

and wherein the or each busbar element is of a flexible or bendable material.

33. A battery for an electric vehicle, the battery comprising one or more battery modules according to Claim 29 or Claim 32.

34. An electric vehicle including a battery according to Claim 32.