Busbar connector

Abstract

A busbar connector (60) for making one or more electrical connections within or to a battery module (M) of a battery pack, the battery module (M) comprising one or more battery cells, wherein the busbar connector (60) comprises: a base portion (160) for forming an electrical connection to one or more of the battery cells within the module; and at least one connector portion (180, 190) for forming an electrical connection from the base portion (160) to one or more other components of the module or the battery pack; wherein at least one or more of the following (i) to (iv) is satisfied: (i) the at least one connector portion (180, 190) has a non-uniform transverse cross-sectional area passing therealong, or (ii) the at least one connector portion (180, 190) has a lateral width which varies passing therealong, or (iii) the base portion (160) has a longitudinal length, the base portion (160) and the at least one connector portion (180, 190) are united or joined via an attachment portion, and the attachment portion has a length dimension, in the same direction as the longitudinal length of the base portion (160), which is greater than the lateral width of the at least one connector portion (180, 190) at locations therealong spaced or distal from the attachment portion, or (iv) the base portion (160) has a longitudinal length, and the at least one connector portion (180, 190) extends transversely from a lateral side of the base portion (160), and further extends in a general length direction (L) thereof which lies at an angle relative to the longitudinal length direction of the base portion (160), wherein the said angle lies in the range of from greater than 0 or 2 or 5 or 10 or 15 or 20 or 25° up to 30 or 40 or 50 or 60 or 70 or 80 or 90° relative to the longitudinal length direction of the base portion (160).

Claims

1. A busbar connector for making one or more electrical connections within or to a battery module of a battery pack, the battery module comprising one or more battery cells, wherein the busbar connector comprises: a base portion for forming an electrical connection to one or more of the battery cells within the battery module; and a pair of connector portions for forming an electrical connection from the base portion to one or more other components of the battery module of the battery pack, each one of said pair of connector portions extending away from a respective side of the base portion, whereby the pair of connector portions are arranged or configured to bear against or abut respective ones of a pair of opposite side faces of a cell housing, wherein the base portion is arranged to lie against or in abutment or adjacent an upper or a lower face of the cell housing such that the base portion makes electrical connections to the one or more of the battery cells accommodated within the housing; wherein at least one of the following (i) to (iv) is satisfied: (i) the pair of connector portions has a non-uniform transverse cross-sectional area passing therealong, (ii) the pair of connector portions has a lateral width which varies passing therealong, (iii) the base portion has a longitudinal length, the base portion and the pair of connector portions are united or joined via an attachment portion, and the attachment portion has a longitudinal length dimension, in the same direction as the longitudinal length of the base portion, which is greater than the lateral width of the pair of connector portions at locations therealong spaced or distal from the attachment portion, and (iv) the base portion has a longitudinal length, and the pair of connector portions extends transversely from a lateral side of the base portion, and further extends in a general length direction thereof which lies at an angle relative to the longitudinal length direction of the base portion, wherein the angle lies in the range of from greater than 0° up to 90° relative to the longitudinal length direction of the base portion.

2. A busbar connector according to claim 1, wherein (iii) is satisfied and the longitudinal length dimension of the attachment portion corresponds to at least a majority portion of the longitudinal length of the base portion, such that the longitudinal length dimension of the attachment portion is greater than 50% of the longitudinal length of the base portion.

3. A busbar connector according to claim 2, wherein the attachment portion is or comprises a fold or an angled portion, wherein the angle of the fold or angled portion is approximately a right angle.

4. A busbar connector according to claim 1, wherein the base portion and the pair of connector portions are configured relative to each other such that they are placeable against different but adjacent sides or faces of the cell housing.

5. A busbar connector according to claim 1, wherein the pair of connector portions are oriented substantially parallel to each other.

6. A busbar connector according to claim 1, wherein the pair of connector portions are configured so as to be generally geometrically substantially identical to one another and a mirror image of one another.

7. A busbar connector according to claim 1, wherein either or both of the connector portions is joined or united to or with the base portion at an angle relative thereto, wherein the angle is approximately 90°.

8. A busbar connector according to claim 1, wherein either or both of the connector portions is generally tapered when viewed side-on, and narrowing in its lateral width dimension passing from its site or line of connection or attachment or joining to the base portion towards an end thereof distal from the base portion, optionally wherein that site or line of connection or attachment or joining is an integral connection or uniting of the material of the respective connector and base portions.

9. A busbar connector according to claim 1, wherein the base portion is apertured or foraminate, whereby it comprises or contain a plurality of apertures therein, optionally wherein the apertures are arranged in an array, wherein each aperture corresponds to and is positioned or located in the vicinity or locality of or adjacent to a corresponding location of a respective pole or terminal of a cell to be accommodated in a respective compartment in a cell housing when the busbar connector is fitted to or mounted on a respective cell array of a respective battery module.

10. A busbar connector according to claim 1, wherein (iv) is satisfied, and either or both of the respective connector portions is configured with a swept-back or swept-forward configuration, depending on whether the general length direction in which the connector portion is considered, or is defined, as extending towards a rear end or a forward end of the base portion of the busbar connector.

11. A busbar connector according to claim 10, wherein the general length direction towards the rear end or the general length direction towards the forward end, in which the respective connector portions are considered, or are defined, as extending, each independently are or correspond to a longitudinal direction of the base portion in which, when in use, a voltage gradient or a current density increases passing longitudinally along the base portion of the busbar connector, or wherein the respective general length directions towards the rear end or the forward end, in which the respective connector portions are considered, or are defined, as extending, each independently are or correspond to a longitudinal direction of the base portion in which, when in use, a voltage gradient or a current density decreases passing longitudinally along the base portion of the busbar connector.

12. A busbar connector according to claim 1, wherein either or both of the connector portions terminates in an electrical interconnection end portion distal from the base portion.

13. A busbar connector according to claim 12, wherein either or both of the terminal interconnection end portions extends a distance of up to 20% of the longitudinal length of the base portion beyond the longitudinal limit of the base portion, whereby either or both of the respective terminal interconnection end portions is configured to be electrically interconnectable to another, like terminal interconnection end portion of another, like connector portion of another, like busbar connector provided on an adjacent or sequentially next battery module in a series of battery modules in an overall battery pack or assembly.

14. A busbar connector according to claim 12, wherein the respective interconnection end portions are each connected to their respective connector portions by a step or ramp, whereby a stepped or ramped interconnection end portion on one busbar connector's connector portion can be placed into side-by-side electrically conductive abutment with a correspondingly but oppositely stepped or ramped interconnection end portion on the other busbar connector's connector portion.

15. A method of making a busbar connector, comprising: providing a blank of electrically conductive material having a first portion corresponding to and for forming the base portion as defined in claim 1, and two second portions corresponding to and for forming the pair of connector portions as defined in claim 1; and forming the blank, optionally by folding or bending or shaping, into said busbar connector according to claim 1.

16. A battery module comprising at least one busbar connector according to claim 1.

17. A battery module comprising a pair of busbar connectors each according to claim 1, wherein the pair of busbar connectors are mounted or fitted thereon or thereto.

18. A battery comprising a battery module according to claim 16.

19. A vehicle including a battery according to claim 18.

20. A battery module according to claim 17, wherein each one of said pair of connector portions of the respective busbar connectors of the pair in each module are configured such that the respective connector portions on each respective lateral side of the cell housing bear against or abut different respective regions of the same lateral side of the cell housing, wherein said regions are separated from each other by a distance sufficient to electrically insulate said respective connector portions from each other on that lateral side of the cell housing or module.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the various aspects of the present invention will now be described, by way of example only, with reference to the accompanying drawings, which are to be considered as schematic drawings only, in which:

(2) FIG. 1 is an exploded perspective view of a vehicle battery pack or assembly, comprising a series of a plurality of battery modules, showing at least some of its main components, including an embodiment of a heat exchanger, an embodiment of a cell housing, and an embodiment of a busbar connector, all being example embodiments of their own respective invention aspects;

(3) FIG. 2 is a top perspective view of the embodiment heat exchanger shown in the assembly of FIG. 1;

(4) FIG. 3(a) is an enlarged top perspective view of a portion of the heat exchanger of FIG. 2;

(5) FIG. 3(b) is an enlarged bottom perspective view of a portion of the heat exchanger of FIG. 2;

(6) FIG. 4 is a top perspective view of an alternative embodiment heat exchanger usable in the assembly of FIG. 1, showing an alternative example arrangement of its thermal fluid flow channels;

(7) FIG. 5 is a top perspective view of the embodiment cell housing as shown in the assembly of FIG. 1;

(8) FIG. 6 is a top plan view of the cell housing of FIG. 5, showing more clearly the configuration and arrangement of its tri-lobed cell housing compartments;

(9) FIG. 7 is a top perspective view of the embodiment busbar connector as shown in the assembly of FIG. 1;

(10) FIG. 8 is a bottom plan view of the busbar connector if FIG. 7;

(11) FIG. 9 is an explanatory cross-sectional view of the manner in which electrical connection is made between the busbar connector of FIG. 7 and cells in the battery module array.

DETAILED DESCRIPTION OF EMBODIMENTS

(12) Referring firstly to FIG. 1, this shows in exploded form the main components of a vehicle battery pack or assembly, showing at least some of its main components. The battery pack or assembly 10 comprises, generally, a linear series or array of physically and electrically interconnected but discrete battery modules Ma, Mb, Mc collectively contained within an elongate generally rectangular-sectioned outer casing, tray or trough 110, e.g. of an electrical insulating material such as a suitably rigid and strong plastics material. Each of the battery modules Ma, Mb, Mc comprises a respective moulded cell housing 40a, 40b, 40c, as will be described further below, each cell housing 40a, 40b, 40c being bounded on its various faces and sides by a respective pair of busbar connectors 60aA, 60aB; 60bA, 60bB; 60cA, 60cB; as will also be described further below. The upper side of the arrangement of cell housings and busbar connectors—and also the lower side thereof, if desired or necessary (although FIG. 1 does not show this option for clarity reasons)—is bounded by an elongate strip-like or panel-like heat exchanger device 20, e.g. supported by end-mounts 27, to facilitate heat transfer out of or away from the cells of each battery module during use, which heat exchanger device 20 will also be described further below.

(13) The series or array of battery modules Ma, Mb, Mc are bounded on each end by a respective end-cap 90, e.g. of electrical insulating material, which also serve as respective anchoring sites for electrical end connection means 82, 84, 86 via which overall electrical connections are made to each respective end of the battery module array. If desired or necessary any given joint between immediately adjacent battery modules may be strengthened or stabilised, especially against being bent, by virtue of a support element, such as that shown as 88.

(14) FIGS. 2 and 3(a) and 3(b) show the heat exchanger device 20 in greater detail, which is a heat exchanger device 20 according to an embodiment of one or more of the heat exchanger aspects of the present invention.

(15) The heat exchange device 20 comprises a generally somewhat flat or planar body of thermally conductive material, e.g. aluminium or an aluminium alloy, which has been coated on at least its underside surface 23 (as shown in FIG. 3(b)) with an electrically insulating coating. The body forming the basic structure of the heat exchanger device 20 comprises a network or array or system of conduits or channels 22 formed internally therewithin for flow therethrough of an appropriate thermal transfer fluid, e.g. a cooling or heating liquid. The conduits or channels 22 may be of any suitable cross-sectional size and shape, as for example the flow characteristics of the thermal transfer fluid in a particular embodiment device 20 may dictate. The thermal transfer fluid flows into the network, array or system of internal conduits or channels 22 via a fluid inlet 261N, and out thereof via a fluid outlet 26OUT. Flow of the thermal fluid through the network, array or system of conduits or channels 22 may be effected and/or controlled by an appropriate pumping apparatus or system (not shown).

(16) The internal conduits or channels 22 may conveniently be formed in the body of the heat exchanger device 20 by a process already in common use in the art of heat exchangers destined for refrigerators, for example. Such a method may, by way of example, involve selective or patterned bonding together of a pair of aluminium (or aluminium alloy) sheets, followed by expansion of non-bonded spaces inbetween the sheets to form the one or more conduits or channels. Such a method may be carried out using a modified roll-bonding or cold-welding technique and apparatus, wherein, in general terms:

(17) (1) a pattern corresponding to the desired shape and configuration of conduits or channels 22 to be formed is applied to a surface of at least one of the pair of aluminium sheets, e.g. by a serigraphy or other printing technique, in the form of a resist or anti-bonding material applied only in selected regions or portions of the sheet surface corresponding to the pattern;

(18) (2) the combined face-to-face sheets are then pre-heated, e.g. typically at a temperature of up to around 400° C.;

(19) (3) rolling of the combined sheets is then carried out in a press, e.g. under typical pressures of up to around 600 tonnes; (4) annealing (for hardening purposes) is then carried out, e.g. by heat treatment at a temperature of up to around 450° C.;

(20) (5) the roll-bonded sheets are then cooled (e.g. using water) and dried;

(21) (6) the separation and expansion of the non-bonded regions or portions of the bonded sheets corresponding to the initially applied pattern is then accomplished by pumping into the exposed opening(s) thereof an expansion fluid, e.g. a gas such as compressed air, at a suitable elevated pressure, e.g. in the range of from about 90 to about 130 bar.

(22) Suitable apparatus and precise processing parameters and conditions for carrying out practical examples of the above process will be readily apparent to the skilled person and within their general skill and knowledge.

(23) In order to produce a heat exchanger device 20 of optimum heat transfer characteristics when placed into contact or abutment with the respective busbar connectors 60aA, 60bA, 60cA atop the respective upper faces of the respective cell housings 40a, 40b, 40c of the respective modules Ma, Mb, Mc, the underside 23 of the heat exchanger device may be designed, as shown in FIG. 3(b), to be substantially flat or planar, with only the upper side of the device 20 being contoured or rippled or shaped to display or accommodated the various conduits or channels 2 formed with the body of the device 20. The provision of such structural variations is within the general knowledge and skill of the person skilled in the art and versed in the art of heat exchanger manufacture.

(24) Once the basic body—or “substrate”, as it may alternatively be termed in the description that follows—of the heat exchanger device 20 has been formed, it is then subjected to a further processing stage in which there is applied or fabricated directly onto at least one surface thereof—which in many practical forms may be at least its underside 23—a coating of an electrically insulating material. Such an electrically insulating coating may be applied or fabricated as follows:

(25) The electrically insulating coating layer is formed on the aluminium substrate (i.e. the pre-formed body of the heat exchanger device 20) from a polysiloxane material.

(26) The aluminium substrate (i.e. the pre-formed body of the heat exchanger device 20) is initially provided as an anodised substrate, having been subjected to an anodic oxidation process to form a porous layer of aluminium oxide (Al.sub.2O.sub.3) over the surface thereof. The porous layer has a plurality of pores provided therein and provides an anodised surface layer over the substrate surface. By way of example, the anodic layer may be around 20 micrometres in thickness, although other thicknesses may be useful, such as thicknesses in the range from about 10 micrometres to about 50 micrometres. The electrically insulating layer that is ultimately formed penetrates the pores of the porous surface layer, enabling good adhesion to be established between the applied electrically insulating layer and the porous surface layer on the substrate.

(27) As noted above, the layer of porous oxide is pre-formed by an anodic oxidation process to a thickness of around 3-200 microns. The porous oxide layer is then coated with a first layer in the form of a layer of a polysiloxane sol-gel material by spraying.

(28) Following spraying the formulation is allowed to dry in air at 20° C. for 1 hour to form a gel, before being fired at 150° C. in air for 1 hour to form a second layer, being a final layer.

(29) It is believed that when the polysiloxane sol-gel material is applied to the substrate, polysiloxane particles migrate into the pores formed in the porous oxide layer. It is believed that this enables the formed electrically insulating layer to better adhere to the substrate, since it is able to better “key” into the pores provided over the substrate surface. The polysiloxane material as-fired is in many cases formed as a substantially continuous layer of electrically insulating material.

(30) In more detail: a flow-chart of the overall process of fabricating a heat sink according to an embodiment of the present invention may be represented as follows.

(31) START.fwdarw.S101: prepare sheet of aluminium for anodising.fwdarw.S103: anodise aluminium sheet.fwdarw.S105: dip-coat anodised sheet with polysiloxane solution to form a first layer.fwdarw.S107: dry and fire first layer to convert the first layer to a second layer.fwdarw.STOP

(32) In step S101, a substrate of aluminium in the form of a sheet is prepared for anodising. Preparation may include degreasing of the substrate. Light abrasion of the surface thereof may be performed in some embodiments. In step S103 the sheet is subjected to an anodic oxidation process to form a layer of porous native oxide thereover. In step S105 the sheet is spray-coated with a polysiloxane sol-gel solution to form a first layer of solution thereover. It is to be understood that other coating methods may also be employed in other embodiments, such as dip-coating or any other suitable technique. In step S107 the sheet is dried to convert the first layer into a polysiloxane gel layer. The gel layer is subsequently fired to convert the gel layer into a second layer in the form of a layer of electrically insulating material of relatively high scratch resistance that is highly thermally conducting and suitable for use as an electrically isolated heat exchange device according to embodiments of the present invention. During firing to convert the first layer into the second layer, the first layer is densified, and it is believed that chemical bonds are thus formed between particles of polysiloxane. Other process steps may occur in some example embodiments in addition to or instead of any one or more of the above steps, if appropriate or required.

(33) In some embodiments, more than one layer of gel material may be formed before curing. Thus in some embodiments a layer of sol-gel material may be formed and dried to form a gel layer. A second layer of sol-gel material may then be formed over the gel layer, and again dried to form a second gel layer over the first layer. This process may be repeated as many times as required in order to form a gel coating of the required total thickness, although we have found that often a single coating may be sufficient for applications in which an electrical potential across the coating is expected to be up to 500V. Single coatings may also be suitable for higher potential differences, such as 1000V or more, in some embodiments. The gel coating may then be fired to form a layer of electrically insulating material of relatively high scratch resistance and which is highly thermally conducting, as described above.

(34) In some embodiments, one or more regions of the substrate (i.e. the pre-formed body of the heat exchanger device 20) may be masked with a mask material such as a polymer material before the initial anodic oxidation process or before coating with the sol-gel material. The mask material may be removed before or after curing of the sol-gel material in order to prevent the formation of a tightly bonded, electrically insulating polysiloxane layer in the one or more regions. This process step may be useful where it is ultimately required to make an electrical connection directly to the substrate (i.e. the pre-formed body of the heat exchanger device 20), for example an earth connection.

(35) As one specific practical Example of the above generally described process and its practical implementation, there may be mentioned the following sequence of processing and testing steps:

Example

(36) (1) A substrate—i.e. a pre-formed body of the heat exchanger device 20, displaying a generally flat or planar lower major face, whose lowermost sheet used to form it has a thickness of approximately 1 mm—was degreased and subjected to an anodic oxidation process. The anodic oxidation process was carried out according to BS EN ISO 7599—“Anodizing of aluminium and its alloys”. This process resulted in the formation of a layer of aluminium oxide on the exposed lower surface of the body of approximately 30 microns in thickness.

(37) (2) The substrate was then coated in a solution of a polysiloxane sol-gel material by a dip-coating process: The substrate was allowed to stand with its major face in a substantially vertical plane to “dry” the sol-gel material and convert the sol-gel layer into a gel layer. The substrate was then fired in order to cure the gel by heating to a temperature in the range from around 150° C. to around 300° C., optionally in the range from around 200° C. to around 250° C. in air. The substrate may be fired for any suitable period of time, for example a period of from about 10 minutes to about 100 minutes or more. Other temperatures and time periods may be useful in some other example processes. The firing process resulted in the formation of an electrically insulating layer on the lower surface of the body having a thickness of approximately 50 microns.

(38) (3) Following fabrication of the electrical insulating layer on the body surface, electrical testing of the layer structure was performed to test the integrity of the insulating layer thus formed. An electrical contact was made to the underlying heat exchange body Al substrate by removal of a portion of the insulating layer, to form a first electrode. A second electrode was applied to the insulating layer spaced away from the first electrode and a potential difference established across the insulating layer between the Al substrate and the second electrode. A potential of 2 kV was applied and it was found that current flow through the insulating layer was negligible.

(39) Whilst in many examples the material of the heat exchanger device body may comprise aluminium or an aluminium alloy, in other examples other suitable thermally conductive metals or metal alloys may be employed instead, if appropriate or desired, such as one or more metals or metal alloys selected from or containing any of the following: zinc, iron, a carbon steel, magnesium, titanium, niobium, zirconium, hafnium, tantalum, or an alloy of any of the foregoing metals, or possibly an alloy containing aluminium and any of lithium, beryllium or magnesium. Such alternative metals may also allow a native oxide to be readily formed thereover by anodic oxidation (e.g. in the case of a ferrous metal, a ferric oxide layer may be formed by exposure to red fuming nitric acid before depositing the sol-gel layer thereover), thereby usefully lending them well to a coating application/fabrication process as described above. Of course, however, other methods of forming an oxide on the substrate layer may be employed instead, if appropriate or desired.

(40) Thus, by use of the above-described processing steps for applying or fabricating an electrically insulating coating layer on the relevant face or surface of the pre-formed heat exchanger body in accordance with embodiments of this invention, there may be produced a heat exchanger device 20 having a higher thermal conductivity than known heat sinks or heat exchangers, especially those already in use in battery applications, whilst providing excellent electrical insulation between the metallic substrate of the heat exchanger device body and electrically conductive components that it may be in contact with in a respective battery module 40a, 40b, 40c or overall battery pack or assembly 10 itself.

(41) Furthermore, by use of this manufacturing technique it is possible to apply or fabricate a relatively highly scratch resistant, electrically insulating coating of relatively low thermal resistance on the substrate of the pre-formed heat exchanger device body, this being possible in a reliable, convenient, industrially applicable and cost effective manner. The relatively low thermal resistance of the coating may be made possible at least in part because a relatively thin, substantially continuous coating may be provided having good electrical insulation properties.

(42) FIG. 4 shows an alternative heat exchanger device 20′ very similar to that of FIGS. 2 and 3(a) and 3(b), except that here the arrangement or pattern of the internal conduits or channels 22′ is modified in shape, e.g. in order to provide a better tailored distribution and positional presence of heat transfer fluid as it travels through the device 20′, e.g. as dictated by particular heat distributional requirements of a given battery module cell arrangement.

(43) Turning now to FIGS. 5 and 6, these show an embodiment of a cell housing 40 according to an embodiment of one or more of the cell housing aspects of the present invention. The illustrated cell housing 40 may corresponding to any of the individual cell housings 40a, 40b, 40c shown in FIG. 1.

(44) The cell housing 40 is formed as a unitary moulded body comprising an array of the nature of a “honeycomb”-like structure comprising a collection of interconnected side-by-side compartments 44B, 44T, etc each for accommodating a single electrochemical battery cell (not shown, for clarity). The cells are collectively arranged for connection together in a parallel electrical arrangement, whereas the individual battery modules Ma, Mb, Mc are interconnected in a series arrangement. In the example embodiment shown each compartment 44B, 44T, etc is configured for accommodating a generally substantially cylindrical-walled electrochemical battery cell therewithin. For this purpose each compartment 44B, 44T, etc is of a sufficient height to fully accommodate the respective cell therein whilst allowing electrical connections to be made to its lower and upper poles or terminals (as described further below).

(45) In some embodiment configurations, in particular in the case of battery cells which are slightly conical in the outer shape of their casings, each compartment 44B, 44T, etc may be formed with side walls whose configurations mirror or substantially geometrically match that conical shape, so that each cell is able to be accommodated stably and snugly within its respective compartment, especially for example so as to be retained therein under gravity or without any discrete retention element needed to hold each respective cell in place within its respective compartment.

(46) The cell housing 40 is formed as a unitary discrete entity by any suitable conventional moulding technique, with its various curved or arcuate side walls 50 being interconnected in various configurations to form the various compartments 44B, 44T, etc therein. In addition to the compartments themselves, the cell housing 40 is formed with integral end-features 54, 56 for enabling adjacent housings, e.g. 40a and 40b, or 40b and 40c, to be physically interlocked or interconnected together in a longitudinal direction, as shown in FIG. 1. There may be further provided on the integral cell housing moulding 40 any suitable number of appropriately located or positioned locating pins, stakes, spigots, bosses or detents 49, which may be used to locate, mount and/or retain one or more other components of a given battery module, or battery pack or assembly, such as one or more heat exchanger devices 20 or one or more busbar connectors (such as retention features thereof labelled as 249 in FIG. 8) or even other components of the overall arrangement.

(47) Once the battery module or battery pack has been fully assembled, such pins, stakes, spigots, bosses or detents 49 may if desired be deformed, e.g. using heat or ultrasonics, to form respective retention heads thereon which effectively secure the relevant heat exchanger 20 or other component(s) in its/their final mounted position(s) in the assembly.

(48) The material from which the cell housing is formed by moulding is a thermally conductive, electrically insulating material and may be formed by any suitable known moulding method, examples of which are widely available and used in the art. The material comprises a matrix of an electrically insulating material, having dispersed or distributed therewithin particles of a thermally conductive material. The particles may be uniformly dispersed throughout the matrix material. They may be incorporated into the matrix material in any suitable mixing-in stage of the overall moulding process and the preparation of the component materials therefor.

(49) By way of example the matrix may be a plastics material, such as a natural or synthetic polymeric material or resin, having a suitably high electrical resistivity. One suitable example of such electrical insulating plastics material is a GRP (glass-reinforced plastics), or the corresponding matrix plastics material from which known GRP materials are made. Suitable examples of electrically insulating GRP materials are widely available in the art of industrial plastics for various applications, and may comprise a matrix or binder of a variety of resins or polymers (e.g. epoxy, thermoplastic or thermosetting), for instance an isophthalic polyester resin, and may have distributed therein an array or network of glass fibres. As alternative materials to GRPs, there may instead be employed as the matric material various ceramic-reinforced plastics, examples of which are also well-known per se in the art.

(50) The particles of thermally conductive material dispersed or distributed in the matrix may comprise particles of any suitable material having a suitably high thermal conductivity. Examples include various predominantly non-metallic materials, e.g. certain ceramic materials, or thermally conductive polymers. Some practical examples of suitable such materials include: bauxite, alumina (aluminium oxide), polyphenylene sulfide (PPS, such as that from Celanese Corporation).

(51) The particles of the dispersed material within the matrix may be of any suitable size and shape, such as may be dictated by the thermal conductivity properties required of the resulting housing material. In some example forms the particles may for instance have an average (mean) particle width or diameter (as the case may be) in the approximate range of up to about 1 or 2 or 3 or 5 or 8 or 10 or 20 or 30 or 40 or 50 or 75 or 100 or 200 or 400 or 600 or 800 or 1000 microns (1 mm), or possibly even up to 1 or 2 or 3 or 5 mm. In some example forms the particles may for instance be irregularly or asymmetrically shaped particles, e.g. flakes, which is to say they comprise flattened bodies of the material, e.g. having one or more, optionally a pair of opposed, faces with at least one lateral dimension or a surface area which is significantly greater or significantly smaller than the corresponding dimension or surface area of one or more of its other faces. In other example forms, however, the particles may be substantially regularly or symmetrically shaped particles, e.g. generally approximately spherical or polyhedral.

(52) The relative proportions of the electrically insulating matrix material and the material forming the dispersed thermally conductive particles may vary depending on the individual thermal properties required of the cell housing material once moulded into its final shape and spatial arrangement of compartments.

(53) By way of example, however, the electrically insulating matrix material may for instance make up from about 50 or 60 or 70 or 80 or 89 or 90% by weight up to about 90 or 91 or 92 or 95 or 97 or 98 or 99% by weight of the housing material. Conversely, the thermally conductive material dispersed or distributed as particles in the matrix may for instance make up from about 1 or 2 or 3 or 5 or 8 or 9 or 10% by weight up to about 10 or 11 or 20 or 30 or 40 or 50% by weight of the housing material. However, precise relative proportions of the two principal components may be selected in any given practical scenario in accordance with principles and techniques well-known to the skilled person versed in the art of industrial moulding materials, in order to arrive at a housing material having optimum thermal conductivity properties to suit any specific battery module demands.

(54) Generally the composition of the material of the cell housing may be selected so as to provide an optimum balance between its thermal conductivity and a required level of heat transfer through the material, also taking into account its electrical strength against a required level of electrical isolation between the cells and/or busbars within or surrounding the housing.

(55) The individual compartments 44B, 44T, etc in the cell housing 40 are defined by respective arcuate side-walls thereof, which join or attach or connect any one compartment to any one other compartment by virtue of those side walls—such as those labelled 50 in FIGS. 5 and 6—being at least partially united together or fused or even in common, in particular as integrally formed portions of the overall unitary moulding which forms the complete housing 40.

(56) The compartments 44B, 44T, etc are configured and arranged in discrete groups 42B, 42T, etc, with each group having the appearance (when viewed in plan, as seen in the FIGS.) of a plural-lobed moulding, each lobe of the moulding corresponding to a single compartment in which a battery cell is to be accommodated. Within each group the compartments 44B, 44T, etc may be arranged substantially symmetrically about a central axis, especially rotationally symmetrically about that central axis, when viewed in plan.

(57) In this illustrated example the groups of compartments comprise three linear rows (spaced apart in the longitudinal direction of the housing 40) of equi-spaced three-lobed moulded compartments 44T, in the style of a “trefoil” or “cloverleaf” shape, and a single row (again spaced apart in the longitudinal direction of the housing 40) of equi-spaced two-lobed moulded compartments 44B, in the style of a “bifoil” shape.

(58) Other numbers of rows of other configurations of groups of compartments, or any combination of discrete species of groups each comprising different numbers of compartment “lobes” per group may be employed in other example forms. In particular, specific patterns and arrangements of various species of lobed groups of compartments may be employed in various alternative example forms of cell housings still within the scope of the invention, especially in order to optimise space-filling or packing and in order to optimise the degree to which such arrangements may optimise the thicknesses, shapes and layouts of compartment side walls in such a way as to beneficially effect their overall heat transfer and distribution characteristics.

(59) It will be noted that in the illustrated embodiment example, the groups 42T of tri-lobed compartments 44T in any one given longitudinal row are equi-spaced within but oriented in a rotationally different orientation—specifically a 120°—rotationally-shifted rotational orientation—relative to each other (when viewed in plan). Furthermore, the tri-lobed groups 42T of compartments 44T in the one given row protrude, e.g. a short distance (such as about 0.5 or 1 or 2 or 3 or 4 or 5 up to about 7 or 8 or 10 or 12 or 15 or 20 or 25 or 30 or 35 or 40 or 45 or 50% of the diameter or width of a single compartment 44T), into the gap or space between individual groups 42T in the immediately adjacent row. This close-packing arrangement may thus serve to reduce large variations in the wall thicknesses that divide and define individual compartments 44B, 44T, etc, thereby potentially reducing large variations in thermal conductivity—and thus overall thermal transfer properties—as between different locations or sites within the overall cell housing moulded structure.

(60) Of course, in other example embodiment forms, other shapes of individual compartments, the shapes of the groups into which they are grouped, and relative spatial arrangements and distributions of those groups relative to each other, may be employed, as appropriate or desired.

(61) In general, however, the cell compartments 44B, 44T, etc formed in the housing 40 may be shaped and grouped so as to provide optimisation between being able to provide sufficient energy density within a given material volume, e.g. dependent on the planar space restrictions within an overall battery module Ma, Mb, Mc, and being able to provide sufficient transfer of heat from, or to, or between cells whilst minimising the effects of any cell and housing moulding dimensional variations.

(62) Turning now to FIGS. 7, 8 and 9, these show an embodiment of a busbar connector 60 according to an embodiment of one or more of the busbar connector aspects of the present invention. The illustrated busbar connector 60 may be any of the individual busbar connectors 60aA, 60aB; 60bA, 60bB; 60cA, 60cB; shown in FIG. 1.

(63) The busbar connector 60 comprises a base portion 160, and, extending at an approximate right-angle)(−90° from opposite lateral sides of the base portion 160, a pair of opposed parallel connector portions 180, 190. Each of the base portion 160 and connector portions 180, 190 is formed from an electrically conductive material, e.g. copper, a copper alloy or any other suitable material having an appropriately high electrical conductivity. The base portion 160 is generally approximately flat or planar in shape, and each connector portion 180, 190 is also substantially flat or planar. Conveniently the busbar connector 160 may be formed, e.g. by bending, folding or otherwise shaping by any suitable means, from a unitary blank, e.g. in sheet form, of the material pre-formed, e.g. by pre-moulding, pre-cutting, pre-stamping or otherwise pre-machining, into the required shape and configuration to form the respective base portion 160 and connector portions 180, 190 of the finished busbar connector 60.

(64) The base portion 160 is configured so as to be placeable against or in abutment with or adjacent an upper or a lower face of a respective cell housing 40, where connections are made to the respective cells accommodated within the housing 40. The pair of connector portions 180, 190 are configured so as to be placeable so as to bear against or abut respective ones of a pair of opposite lateral side faces of the respective cell housing 40. This relative arrangement can be seen more clearly in FIG. 1.

(65) Each of the respective connector portions 180, 190 of the busbar connector 60 is specially shaped, when viewed side-on, so as to have a non-uniform transverse cross-sectional area passing therealong. Alternatively this feature may be defined as the respective connector position 180, 190 having a lateral width which varies passing along it. Thus, it may be considered that the side-on shape of each respective connector portion 180, 190 is generally substantially triangular or tapered passing towards its end distal from the base portion. Thus, a major side of the triangle opposite its hypotenuse may form a site or line of connection or attachment or joining, especially an integral such connection/attachment/joining, of the respective connector portion 180, 190 to the base portion 160.

(66) According to an alternative definition of the respective connector portions 180, 190, the base portion 160 and each respective connector portion 180, 190 are united or joined via a respective attachment portion, and each respective attachment portion may be defined as having a length dimension, in the same direction as the longitudinal length of the base portion 160, which is greater than the lateral width of the respective connector portion 180, 190 at locations therealong spaced or distal from the respective attachment portion.

(67) According to yet another alternative definition of the respective connector portions 180, 190, each said connector portion 180, 190 may alternatively be defined as extending transversely from a lateral side of the base portion 160, and further extending in a general length direction L thereof (as shown in FIG. 7) which lies at an angle relative to the longitudinal length direction of the base portion 160, wherein the said angle lies in the approximate range of from greater than about 0 or 2 or 5 or 10 or 15 or 20 or 25° up to about 30 or 40 or 50 or 60 or 70 or 80 or 90° relative to the longitudinal length direction of the base portion 160.

(68) Any of the above defined shapes and/or configurations of the respective connector portions 180, 190 of the busbar connector 60 may further be such that the respective connector portions 180, 190 of different, discrete, busbar connectors 60 on the respective lateral sides of a given cell housing 40 bear against or abut different respective regions of the same lateral side, wherein said regions are separated from each other by a distance sufficient to electrically insulate the two connector portions 180, 190 from each other on that lateral side of the cell housing.

(69) As shown by way of example in FIGS. 8 and 9, the base portion 160 of the or each busbar connector 60 (of which the positive polarity busbar connector is designated “60pos”, and the negative polarity busbar connector is designated “60neg”) is apertured or foraminate, such that it comprises an array of a plurality of apertures 166 therein. The apertures 166 are generally part-rectangular in shape (when viewed in plan), although they may alternatively be arcuate or even part-circular. The apertures 166 are arranged in an array, wherein each aperture corresponds to and is positioned or located in the locality of a corresponding location of a respective pole or terminal 204, 206 of a battery cell 200 to be accommodated in a respective compartment 44B, 44t, etc in a cell housing 40 when the busbar connector 60 is fitted to or mounted on a respective cell array of a respective battery module M.

(70) Within each respective aperture 166 the material of the base portion 160 is formed into a tongue or protrusion or extension 168 which protrudes or extends into the respective aperture 166 from a peripheral side thereof, e.g. a side proximal a rear end 160R of the base portion 160. Each respective tongue or protrusion or extension 168 is configured so as to lie out of, especially below, a general plane of the base portion 160.

(71) Furthermore, the electrically conductive material forming the or each tongue or protrusion or extension 168 has a reduced thickness, e.g. of the order of 0.3 mm, which is less than the thickness of the material of the base portion 160 which surrounds the respective aperture 166, which may typically be around 1.5 mm. This reduced thickness of −0.3 mm of the or each tongue or protrusion or extension 168 may typically be approximately equal to a thickness of a material forming a cell pole or terminal 204 (FIG. 9) itself, or a material forming a casing wall of a cell, which is to be electrically connected to the respective tongue or protrusion or extension 168 by a process involving welding. This feature may serve to assist in making an efficient and secure welded connection between the respective tongue or protrusion or extension 168 and a respective cell pole or terminal.

(72) FIG. 9 also shows by way of example the manner in which a heat exchanger device 300 is mounted in the overall arrangement of the battery module, with its electrical insulating coating 230 applied thereto and a thermal paste optionally included in any gaps between the heat exchanger device 300 and the relevant poles or terminals 206 of the battery cells 200.

(73) As mentioned above, and as illustrated in the embodiment busbar connector 60 shown in FIG. 7, each connector portion 180, 190 may be thought of as extending transversely from a lateral side of the base portion 160, and further extending in a general length direction L thereof which lies at an angle relative to the longitudinal length direction of the base portion 160, wherein the said angle lies in the approximate range of from greater than about 0 or 2 or 5 or 10 or 15 or 20 or 25° up to about 30 or 40 or 50 or 60 or 70 or 80 or 90° relative to the longitudinal length direction of the base portion 160. In this manner each connector portion 180, 190 may thus be configured with a “swept-back” or “swept-forward” configuration (depending on whether the general length direction in which the respective connector portion is considered, or is defined, as extending is towards a rear end 160R or a forward end 160F of the respective base portion 160 of the respective busbar connector 60).

(74) In some embodiment forms the above-mentioned respective directions towards the aforementioned rear end 160R or forward end 160F, as the case may be, in which the connector portions 180, 190 are considered, or are defined, as extending, may each independently be or correspond to a longitudinal direction of the base portion 160 in which, when in use, a voltage gradient or a current density increases—or, in alternative embodiments, decreases—passing longitudinally along the base portion 160 of the busbar connector 60. This “swept-back” or “swept-forward” configuration of the or the respective connector portion may in such instances assist in the “equilibration” or “evening out” of variations in current densities and distributions across or through specific portions of the busbar connector 60, thereby leading to improved or at least more reliable contributions of the busbar connector 60 to overall heat distributions—especially equilibrated heat distributions—within a given battery module M, especially across the cells thereof, and/or between modules Ma, Mb, Mc in an assembled battery pack 10.

(75) However, in other embodiment forms other spatial or configurational relationships between the direction, and/or angle relative to the general plane of the base portion, and/or shape of the or each connector portion, relative to a voltage gradient and/or current density increase or decrease passing along the base portion of the busbar connector in the said longitudinal direction thereof, may be possible.

(76) The pair of connector portions 180, 190 of the busbar connector 60 are configured so as to be generally geometrically substantially identical to one another, but a mirror image of one another.

(77) Each connector portion 180, 190 terminates in a respective electrical interconnection end portion 182, 192 distal from the base portion 160, wherein each terminal interconnection end portion 182, 192 extends in a direction parallel to the longitudinal direction of the base portion 160. Each terminal interconnection end portion 182, 192 extends a distance, e.g. typically a short distance, such as up to about 1 or 2 or 5 or 8 or 10 or 12 or 15 or 20% of the longitudinal length of the base portion 160, beyond the longitudinal limit of the base portion 160, whereby the or each respective terminal interconnection end portion 182, 192 is configured to be electrically interconnectable to another, like terminal interconnection end portion 182, 192 of another, like connector portion 180, 190 of another, like busbar connector 60 provided on an adjacent or sequentially next battery module M in a series of battery modules Ma, Mb, Mc in an overall battery pack or assembly 10. In this manner adjacent or sequentially next battery modules Ma, Mb, Mc in a battery pack or assembly 10 can be conveniently electrically connected together via the respective busbar connectors 180, 190 in each module Ma, Mb, Mc, in order to fulfil the overall electrical supply parameters of the battery pack or assembly 10.

(78) In order to facilitate the making of such electrical interconnections between adjacent or sequentially next interconnection end portions 182, 192 of respective connector portions 180, 190 of respective busbar connectors 60 in adjacent or sequentially next modules Ma, Mb, Mc, the respective interconnection end portions 182, 192 may each be connected to its respective connector portion 180, 190 by a respective step or ramp 186, 196, whereby a stepped or ramped interconnection end portion 182, 192 on one busbar connector's connector portion 180, 190 may be more readily placed into side-by-side electrically conductive abutment with, e.g. by virtue of being welded or adhered to, a correspondingly, but oppositely, stepped or ramped interconnection end portion 182, 192 on the other busbar connector's connector portion 180, 190.

(79) As shown in the illustrated embodiment arrangement of FIGS. 1 and 7, each battery module Ma, Mb, Mc is fitted with a pair of busbar connectors 60aA, 60aB; 60bA, 60bB; 60cA, 60c, respectively. In each module the two busbar connectors form a pair, which are geometrically identical or similar to each other but are configured as mirror images of each other. Thus, a base portion 160 of a first one of the busbar connectors 60 is mounted on, e.g. in abutment against, an upper major face of the module M, and a base portion 160 of a second one of the busbar connectors 60 is mounted on, e.g. in abutment against, a lower, opposite major face of that module M. The upper major face of the module M is an upper major face of a cell housing 40 of the module M that accommodates the battery cells of that module, and the lower major face of the module M is a lower major face of the cell housing 40, whereby each of the respective base portions 160 of the two busbar connectors 60 is in abutting electrical contact with the poles or terminals of the cells accommodated in the housing 40 of the module M on the respective upper and lower major faces thereof.

(80) Also as shown in the illustrated embodiment arrangement, the configurations of the respective connector portions 180, 190 of the respective busbar connectors 60 of the pair in each module M are such that the respective connector portions 180, 190 on each respective lateral side of the cell housing 40 bear against or abut different respective regions of the same lateral side of the cell housing 40, wherein said regions are separated from each other by a distance sufficient to electrically insulate the two connector portions 180, 190 from each other on that lateral side of the cell housing 40 or module M. In some embodiment forms this relative configuration may be conveniently achieved and exploited, especially in terms of the ease with which adjacent modules Ma, Mb, Mc may be electrically interconnected via their respective busbar connectors 60, by virtue of the two geometrically similar or identical (albeit mirror image) busbar connectors 60 being oriented in a reversed longitudinal orientation relative to each other on the two opposite major faces of the cell housing 40 or module M.

(81) As a result of our investigations, we have found that by designing a busbar connector to have certain novel features of shape and configuration as defined and described above, it is possible to control or adjust or tailor current densities and current distributions at particular points and/or positions and/or regions therewithin, which may be exploited to good effect in further optimising heat transfers and heat distributions within a battery module, and in particular between individual cells and across cell arrays in such a module.

(82) In some cases such improved control of current densities and current distributions may lead to advantageous effects of “equilibration” or “evening out” of variations in current densities and distributions, i.e. the reduction of “hot-spots”, across or through specific portions of the busbar, thereby leading to improved or at least more reliable contributions of the busbar to overall heat distributions—especially equilibrated heat distributions—within a given battery module, especially across the cells thereof, and/or between modules in an assembled battery pack.

(83) It is to be understood that the above description of one or more specific embodiments 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 by the appended claims.

(84) Throughout the description and claims of this specification, the words “comprise” and “contain” and linguistic 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.

(85) 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.

(86) 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.