WO2023180428A1

WO2023180428A1 - Modular battery pack for electric vehicles

Info

Publication number: WO2023180428A1
Application number: PCT/EP2023/057423
Authority: WO
Inventors: Rodyn GILHARRY; Csaba Dobi
Original assignee: Northvolt Ab
Priority date: 2022-03-24
Filing date: 2023-03-23
Publication date: 2023-09-28

Abstract

A battery module comprising a frame having a pair of side walls and a pair of end walls is provided. The module further comprises a beam extending parallel to the pair of side walls to define a first internal space between a first side of the beam and a side wall of the pair of side walls and a second internal space between a second side of the beam and the other side wall of the pair of side walls. A first plurality of secondary cells are arranged in the first internal space and a second plurality of second cells are arranged in the second internal space. The first plurality of secondary cells are fixed to the first side of the beam and the second plurality of secondary cells are fixed to the second side of the beam.

Description

MODULAR BATTERY PACK FOR ELECTRIC VEHICLES

Technical field

The present disclosure generally relates to batteries for electric vehicles. More particularly, the present disclosure relates to a modular battery pack for installation in electric vehicles.

Background

Rechargeable or secondary batteries find widespread use as electrical power supplies and energy storage systems. For example, in automobiles, battery packs formed of a plurality of battery modules, wherein each battery module includes a plurality of electrochemical cells, are provided as a means of effective storage and utilization of electric power.

Several different form factors exist for the electrochemical cells applied in secondary batteries depending on their intended application field. In automotive applications, the most common cell types are cylindrical, prismatic and pouch cells. A further concept for automotive applications is large format flat, thin cells, which in general include a single positive electrode and a single negative electrode and in which the upper and lower surfaces are formed by the electrodes, which serve as cell housing and also act as the terminals for the cell.

However, there is still a need for alternative and improved cell designs and battery packs, in particular in view of balancing the weight and strength of a battery pack, challenges relating to mechanical movement during cell swelling, or handling of cell failure.

Summary

Aspects of the present disclosure relate to a modular battery pack for electric vehicle having adaptations and improvements directed to solving one or more of the aforementioned problems. According to an aspect of the present disclosure, there is provided a battery module comprising a plurality of aligned secondary cells, each secondary cell of the plurality of secondary cells having a casing and a failure vent in the casing for venting gases upon thermal failure of the secondary cell, and a thermal sheath arranged on the casing of each secondary cell, in a fluid path between vented gases from other secondary cells in the plurality of secondary cells and the casing of said each secondary cell.

According to an aspect, there is provided a base plate of a battery pack for an electric vehicle comprising a first layer forming a top side of the base plate, configured to provide an internal bottom wall of the battery pack, a second layer having recesses formed thereon for routing a coolant, and a third layer forming an underside of the base plate. The second layer is interposed between the first layer and the third layer such that the recesses are enclosed by the first layer and/or the third layer so as to form coolant channels for routing coolant and thereby cooling the battery pack.

The first layer may be formed of a thermally conductive layer of aluminum, steel or the like, or a thermally conductive plastic or composite material. The second layer may be formed of a thermally and electrically insulating layer of a low-density foam, plastic or a composite material. Preferably, the material is waterproof and configured to operate on a hot coolant environment for an extended period of time. The coolant channels may be milled, machined, molded, etched or the like. The third layer may be formed of a composite or plastic material, or a metal layer, having a relatively high impact resistance and mechanical strength to protect the battery pack from the external environment.

According to an aspect, there is provided a battery module comprising a plurality of aligned secondary cells, and a partitioning device interposed between each of the plurality of aligned secondary cells and bonded thereto. The partitioning device comprises a compressible sheet having a peripherally attached rigid support structure, is bonded to the secondary cells via the rigid support structure.

According to an aspect, there is provided a battery module comprising a plurality of aligned secondary cells, each secondary cell having a casing and a failure vent in the casing for venting gases upon thermal failure of the secondary cell, and a heat shield layer arranged between the plurality of secondary cells and a top wall of the battery module, thereby creating a module venting channel between the heat shield layer and the top wall. The heat shield layer is configured to thermally insulate the plurality of secondary cells from the module venting channel. Further, for each secondary cell, a cell venting channel is configured to direct vented gases from the failure vent of said each secondary cell to the module venting channel.

According to an aspect, a frame for a battery module is provided, comprising one or more walls arranged to enclose a space for containing internal components of the battery module. At least one wall of the one or more walls is formed of a non-metallic material and comprises a rigid reinforcement structure.

According to an aspect there is provided a battery module comprising a frame comprising a pair of side walls and a pair of end walls. Further, the module comprises at least one beam extending parallel to the pair of side walls between the pair of end walls, thereby defining a first internal space between a first side of the beam and a side wall of the pair of side walls, and a second internal space between a second side of the beam and the other side wall of the pair of side walls. The module also comprises a first plurality of secondary cells arranged in the first internal space aligned in a first column between the pair of end walls, and a second plurality of second cells arranged in the second internal space aligned in a second column between the pair of end walls. The first plurality of secondary cells are fixed to the first side of the beam and the second plurality of secondary cells are fixed to the second side of the beam.

According to an aspect, a battery module is provided, comprising a plurality of aligned secondary cells, and a busbar configured to electrically interconnect at first and a second one of the plurality of secondary cells. The busbar comprises a first connection plate adapted to be attached to a first terminal plate of the first secondary cell and a second connection plate adapted to be attached to a second terminal plate of the second secondary cell. Further, the first and second connection plates comprise interlocking structures configured to engage corresponding interlocking structures of the first and second terminal plates.

The interlocking structures of the first and second connection plates may comprise through holes and the corresponding interlocking structures of the first and second terminal plates may comprise pins arranged to be fitted in the through holes.

The through holes may have a circular cross section and the pins a quadrangular cross section, such that the pins and/or holes are deformed when pushed together, thereby producing a tight mechanical joint.

Brief description of drawings

The above and other aspects of the present invention will now be described in more detail, with reference to the appended figures.

Figure 1 is a perspective view of a battery pack with a cover assembly, according to aspects of the present disclosure.

Figure 2 is a perspective view of a battery pack without a cover assembly, according to aspects of the present disclosure.

Figure 3 is an exploded view of a battery pack, according to aspects of the present disclosure.

Figure 4 is an exploded view of a cover assembly for a battery pack, according to aspects of the present disclosure.

Figure 5 is a perspective view of a battery module for a battery pack, according to aspects of the present disclosure.

Figure 6 is a perspective view of a battery module for a battery pack having a heat shield layer and non-metallic side walls, according to aspects of the present disclosure.

Figure 7 is an exploded view of a battery module for a battery pack, according to aspects of the present disclosure.

Figure 8 is an exploded view of an electrical management layer for a module, according to aspects of the present disclosure. Figure 9 is a perspective exploded view of a (secondary) cell, a thermal sheath for the cell, and a partitioning device, according to aspects of the present disclosure.

Figure 10 is a top view of a battery module for a battery back, having an enlarged view of a subset of secondary cells, with a perspective view of a secondary cell having a partitioning device bonded thereto, according to aspects of the present disclosure.

Figure 11 is a cross-sectional view of a portion of a battery module for a battery pack, showing a wall and a plurality of aligned secondary cells, according to aspects of the present disclosure.

Figure 12 is a perspective view of a frame for a battery module, according to aspects of the present disclosure.

Figure 13 is an isolated perspective view of a beam comprised in the frame shown in figure 12, according to aspects of the present disclosure.

Figure 14a is a top view of the module frame shown in figure 12, having example operational forces illustrated thereon, according to aspects of the present disclosure.

Figures 14b and 14c show enlarged views of the interface regions of 14a, having alternatively configured interfaces.

Figure 15 is a top view of a battery module for a battery back having a failed secondary cell, according to aspects of the present disclosure.

Figure 16 is a perspective partial view of a battery module for a battery pack having a heat shield layer and an enlarged portion showing a mating of a venting valve between a cell venting channel and an aperture in the heat shield layer, according to aspects of the present disclosure.

Figure 17 shows an exploded partial view of the battery module showing the arrangement of the heat shield layer over the cell layer and the electrical management layer in the module, according to aspects of the present disclosure.

Figure 18 is a partial cross-sectional view of the battery module showing the relative arrangements of the apertures in the heat shield layer, the venting valves of the electrical management layer, and the failure vents of cells in a module, according to aspects of the present disclosure. Figure 19 is a cross-sectional view of a portion of a battery module for a battery pack, showing a wall and a plurality of aligned secondary cells, wherein a secondary cell has failed, and flow paths of vented gases, according to aspects of the present disclosure.

Figure 20 shows an exploded partial view of a battery module having venting channels directing vented gases from a failed cell to the side of the modules.

Figure 21 is a top view of a venting channel of figure 20, illustrating the gas flow to the side of the module.

Figures 22 and 23 are partial perspective views of a press fit busbar for electrically interconnecting two modules.

Detailed description

Aspects of the present disclosure will now be described hereinafter with reference to the accompanying drawings, in which currently preferred, exemplary implementations of the disclosed aspects are illustrated.

Figure 1 is a perspective view of a battery pack 1 (also referred to herein as simply ‘pack T) with a top cover 2, according to aspects of the present disclosure. The battery pack 1 further comprises a pack frame 3, having openings therein to allow for connections to high voltage connectors 4, a coolant inlet 5 and/or similar such inputs/outputs.

Figure 2 is a perspective of the battery pack 1 without the top cover 2 shown in figure 1 . As continued throughout, repeated elements having like- numbered references are not discussed again in detail.

As shown in figure 2, the battery pack 1 contains a plurality of battery modules 6 (also referred to herein as simply ‘modules 6’). Whilst there are only three modules 6 shown, it will be appreciated that a greater or fewer number of modules 6 may be included in the pack 1 .

The modules 6 may be electrically connected together and to main terminals 7 for collective charging/discharging of the modules 6, e.g. via the high voltage connectors 4. The electrical interconnection may for instance be achieved by means of an interference fit, or press fit, busbar shown in figures 22 and 23. The pack 1 may further comprise auxiliary electronics 8 for pack- level control and/or monitoring functions. It will be appreciated that the term ‘module’ may refer both to structural and electrical entities. Thus, a battery pack 1 of the present disclosure may form a single module structurally, and a plurality of modules electrically. Put differently, the structural module may be defined by the common pack frame 3 illustrated in, e.g., figures 1-3, whereas the electrical modules 6 may be defined by a stack of cells 26 arranged in a module frame 20. By the term ‘pack’ may be understood a structure comprising one or several structural modules 6 and an electrical management system (BMS). A difference between a ‘pack’ and a ‘module’ could therefore be that the latter do not comprise a (complete) BMS or master BMS. It may however comprise a monitoring sub-system.

The various parts of the battery pack 1 are discussed in more detail in relation to figure 3, which shows a battery pack 1 in exploded view. Figure 3 is generally discussed hereon from top to bottom.

The pack 1 may comprise a cover assembly 2 for protecting from shocks/damage and/or from liquid incursion. As shown in figure 4, the cover assembly 2 may comprise a top cover 14 and a sealant layer 15.

Illustrated below the top cover 2 is a plurality of battery modules 6, which may be fixed into the battery pack 1 assembly by fixing means 9, which may be bolts, screws, rivets, or the like. The modules 6 may be electrically interconnected by at least one module connector 10, configured to electrically interconnect a plurality of modules via, e.g. module busbars (not shown in this figure but shown and discussed in relation to figures 8 and 9) or similar electrical connection points.

The modules 6 may be arranged in a pack frame 3, as discussed above. Whilst the geometry of the pack frame 3 (thus defining the geometry of the battery pack 1 as a whole) is shown as being rectangular, it will be appreciated that the battery pack 1 may take any shape, as desired, considering also a need to provide appropriately shaped and preferably tessellating modules 6.

The internal bottom wall of the battery pack 1 may be provided by a base plate 11 . The base plate 11 may then be mounted on an external cooling assembly (not shown) or, in some examples, the base plate 11 may comprise an integrate cooling system, such that coolant can be passed in and out of inlets/outlets 12.

The base plate 11 may be attached to the battery pack 1 via mounting points 13, which may have corresponding apertures 13a in the base plate 11 to allow passage therethrough. In some examples, the mounting points 13 may interface (e.g. engage, attach) with the fixing means 9 such that the modules 6 may form an integral structure of the battery pack 1 . In further options, the base plate 11 may be connected to the battery pack frame 3 by means of an adhesive and bolts arranged around the perimeter (not shown in the present figure).

Figure 5 shows a perspective view of a module 6 according to an aspect of the present disclosure.

The module 6 may have a peripherally arranged module frame 20, which may be formed of one or more pieces. In the illustrated example, the module frame 20 comprises a pair of side walls 27 and end walls 28.

The module frame 20 may comprise end walls 28 at either end of the columns/stacks of cells, as well as one or more walls 28 interposed between the columns of cells. The module frame 20 may further comprise a beam 29 extending between the end walls 28 (i.e. parallel to the side walls 27) so as to separate neighboring columns of cells. The module frame 20 and the beam 29 are discussed in more detail in relation to figures 12 to 14.

Figure 6 shows a perspective view of a module 6 according to an aspect of the present disclosure. The illustrated module 6 further comprises a heat shield layer 24 arranged over the cells, having apertures 25, discussed in more detail below in relation to figures 16 to 19. The heat shield layer 24 may further serve as a top cover of the module.

The example module frame 20 illustrated in figure 6 differs from that shown in figure 5 at least in that the module frame 20 in figure 6 is formed of a non-metallic material, with a rigid reinforcement structure, in this example an externally visible structure of vertically and horizontally extending ridges.

It will be appreciated that not all side walls 27 and/or end walls 28 need be formed of said non-metallic material(s), and only one or another subset of the walls 27, 28 may be formed of said non-metallic material(s). Further advantageous properties of the non-metallic material may comprise a density lower than that of metallic materials (such as aluminum or steel), thermal and/or electrical insulation, and/or made of recycled or recyclable materials. Examples of such materials may be plastic, foam, such as a syntactic foam, or composite materials. Such materials are also easily formed from molding, extruding, milling, machining or additive manufacturing (AM) techniques, such that precise structures (e.g. reinforcement structure) can be formed with ease.

Although the reinforcement structure is shown as being an open cellular structure of rectangles, extending in the thickness direction of the walls 27, 28, other configurations are possible. For example, the reinforcement structure may be an open cellular structure comprising a zigzag structure forming a plurality of triangular prisms extending along a height of the one or more walls (such as that shown in figures 7, 10, 12, and 14a).

Such a non-metallic module frame 20 may beneficially provide increased thermal and/or electrical insulation between the module 6 and the pack 1. Furthermore, the cost and/or weight of the module 6 may be beneficially reduced, thereby increasing the overall energy density of the battery pack 1 . If recycled or recyclable materials are used to form the module frame 20, the overall carbon footprint of the battery pack 1 may also be reduced.

Figure 7 shows an exploded view of a battery module 6. The module 6 has been exploded to show a number of layers 20, 21 , 22, 23, which are discussed from bottom up.

The module 6 comprises a frame 20 as discussed above. The intermediate end walls 28 and the beam 29 can be more clearly seen in this view, but are not discussed in more detail here.

The next illustrate layer is a cell layer 23 comprising a plurality of cells 26 arranged into two columns, these columns being separated in the frame 20 by the beam 29. Each column is further subdivided into two stacks of cells 26, separated in the frame 20 by the intermediate end walls 28. The cells 26 are discussed in more detail in relation to figures 9 to 11. The module 6 may further comprise an electrical management layer 21 overlaid onto the cell layer 23, which is discussed in more detail below, in relation to figure 8. The electrical management layer 23 may comprise components for monitoring, interconnecting and/or protecting the cells 26.

As briefly mentioned above, the module 6 may further comprise a protective layer 22 for overlaying on the electrical management layer 21 , which may comprise a heat shield layer 24 having apertures which align with valves in the electrical management layer 21 , which are provided above failure vents of the cells so as to create a cell venting channel. This arrangement is discussed in more detail in relation to figures 18 to 21.

Figure 8 shows an exploded view of an electrical management layer 21 . The main body of the electrical management layer 21 may be formed of a carrier plate 32, which may preferably be made from plastic or another non- conductive material for providing rigidity or structure to the electrical management layer 21 .

The carrier plate 32 may have provided therein (e.g. as a result of etching, laser cutting, drilling, etc.) a plurality of venting apertures 33 for allowing formation of the cell venting channel (discussed in more detail below) and a plurality of electrode apertures 34 for allowing electrically connective access to electrodes of the cells 26 in the cell layer 23 below the electrical management layer 21 .

The electrical management layer 21 may further comprise a venting layer 30 comprising a plurality of venting valves 31 for arrangement over failure vents of the cells 26 (as discussed further below). The venting layer 30 may be bonded to the cells 26 and/or to the carrier plate 32, depending on the particular implementation.

For overlaying onto the cells 26, the electrical management layer 21 may further comprise one or more cell monitoring units 35, which may be configured to monitor a thermal and/or electrical status of the cells 26. The cell monitoring units 35 may comprise apertures 36 corresponding to the venting apertures 33 in the carrier plate.

Moreover, the electrical management layer 21 may comprise a plurality of busbars 37 for abutting the electrodes of the cells 26 and thereby electrically (inter)connecting the cells 26 in the module 6. The busbars 37 may be formed of metal or any other electrically conductive material.

Figure 9 shows an exploded view of a cell 26, a thermal sheath 41 for a cell 26, and a partitioning device 45 for interposing between cells 26 in a module 6.

The cell 26 may be substantially cuboidal as illustrated, or may have some other shape depending on the implementation. It will be appreciated that, if the cell 26 were to have a different shape, elements shaped in a complementary manner may also have a different shape so as to complement the shape of the cell 26.

The cell 26 may comprise means for storing energy, such electrode sheets, an electrolyte, etc. or similar such means, which are contained in a casing 38 of the cell 26, preferably in a fluid-tight manner. The casing 38 may be formed of metal with a coating, such as a plastic film coating, or in some examples the casing may be entirely formed of plastic or some other appropriate material.

As illustrated, the cell 26 may be provided with electrodes 39 (e.g. two electrodes: an anode and a cathode) for providing electrical energy to (i.e. charging) the cell 26 and sourcing electrical energy from (i.e. discharging) the cell 26, the electrical energy being stored in said means for storing energy.

During charging or discharging, or as a result of thermal or mechanical shocks, or for other reasons, a cell 26 may experience a failure. The failure may comprise a chemical event causing a so-called ‘thermal runaway’ (TR) event leading to the production of hot gases which may cause the casing 38 of the cell 26 to swell in response to the TR event. It will be appreciated that cells 26 may also swell (i.e. enlarge) and shrink during the course of normal operations.

For a TR events or otherwise, the cell 26 may be provided with a failure vent 40, configured to open (e.g. in a controlled or uncontrolled manner such as rupturing) to allow the ejection of gases and other ejecta from the failed cell 26, thereby preventing an explosion of the cell 26. An example construction of a failure vent may be a thinned portion of the casing 38 (e.g. made from aluminum) having predetermined weakened points such that a predetermined amount of internal pressure may rupture the thinned portion of the casing 38 at the weakened points.

Various techniques may be employed in preventing the swelling of and/or ejections from cells 26 from detrimentally affecting the rest of the cells 26 in the module 6 or the module 6 itself. For example, mechanical stresses may be considered, and it may be desired to limit or control the forces places upon other cells 26 and/or the module frame 20 as a result of one or a plurality of the cells 26 swelling in size. Thermal stresses may also be considered, and it may be desired to limit or control the damage caused by hot gases and ejecta emanating from failure vents 40 of failed cells 26 on other cells 26 in the module 6. These and other problems are addressed by aspects of the present disclosure, as detailed below.

The thermal sheath 41 may be configured to thermally insulate and protect the cell 26. The thermal sheath 26 may be made from mica or other such thermally insulative, compact, and lightweight materials, depending on the implementation.

The illustrated thermal sheath 41 has a body formed of a folded sheet 42, having a first side 42a and second side 42b for placement on the faces of the cell 26 which are to be proximate to neighboring cells 26 and a third side 42c for placement on the top face of the cell 26, which may have openings 43 corresponding to the positions of the electrodes 39 on the cell and an aperture 44 corresponding to the position of the failure vent 40.

In an example arrangement of cells 26 whereby cells are aligned in stacks or columns in the module 6 (e.g. as shown in figure 10), the thermal sheath 41 - in particular, the third side 42c thereof - may be arranged in a fluid path between vented gases from other cells 26 in the module 6 and the casing 38 of the cell 26 having the thermal sheath 41 arranged thereon.

Thus, whilst the first side 42a and the second side 42b arranged between faces of cells 26 may mitigate conductive heat transfer between cells 26, the third side 42c may beneficially mitigate conductive heat transfer between cells 26, carried in the flow of vented gases after e.g. a TR event of a cell 26 causing an opening of a failure vent 40 of said cell 26 to release said vented gases. Further, the sheath 41 may be electrically insulating to allow the third side 42c to help protecting the cells 26 from electrically charged particles in the vented gases or ejecta.

In some examples, the thermal sheath 41 may be formed from a sheet 42 of, e.g., mica, or some similar sheet-like thermal insulator, that may have opening(s) 43 and aperture(s) 44 cut whilst the sheet 42 is in an unfolded state, and may further be connected to other to-be-separated sheets 42, for separating by similar cutting means, for example.

The sheet 42 may then be folded before or during arrangement of the thermal sheath 41 onto the cell 26. For example, adhesive may be applied to the sheet 42 and/or the cell 26, to thereby fix the thermal sheath 41 to the cell 26.

According to said example arrangement of cells 26 in a stack or column (e.g. as shown in figure 10), the module 6 may further comprise partitioning devices 45 for interposing between cells 26 in the module 6. The partitioning device 45 may comprise a compressible sheet 46 having a peripherally attached rigid support structure 47, which may also be referred to as a frame 47. The partitioning device(s) 45 in a module 6 may beneficially be configured to compress and uniformly transmit compressive forces amongst cells 26 and to the module frame 20.

It will be appreciated that a first amount of swelling of a cell 26 may be entirely accommodated for by compression of its abutting partitioning device(s) 45, in particular the compressible sheet(s) 46 thereof, as a result of the compressible sheet 46 compressing. Thus, it may the case that no compression forces are transmitted to neighboring cells 26.

However, in some cases, the swelling/expansion of one or more cells 26 in a module 6 may be such that the compressible sheet(s) 46 in the partitioning device(s) 45 cannot accommodate all of the swelling. Indeed, in some examples, the frame 47 may be configured to limit the compression of the partitioning device 45, thereby beneficially controlling a minimum inter-cell spacing. Thus, a beneficially more even force distribution may be achieved throughout the cells 26 in a module 6. Further, the frame 47 may be arranged to limit the amount of precompression of the compressible sheet 46 during module assembly by acting as a compression limiter.

It will be appreciated that the distinction between the above two cases (i.e. whether compressive forces can be localized or distributed amongst a plurality of cells 26 and partitioning devices 45) may depend on, for example, the percentage increase of the cell’s 26 dimensions during swelling, the thickness and/or compressibility of the compressible sheet 46, etc.

Figure 10 more clearly shows a module 6 having two columns of cells 26 separated by a beam 29, as well as a perspective view of a cell 26 having the thermal sheath 41 arranged thereupon, and the partitioning device 45 engaged with the cell 26.

The support structure/frame 47 of the partitioning device 45 may preferably only surround two or three sides of the compressible sheet 46. Hence, the compression limiting function of the partitioning device 45 may be achieved without excess weight contributed from the support structure 47. The support structure 47 may further avoid convective heat transfer from vented gases of failed cells 26 by not having a side substantially in the fluid path of such gases (e.g. a top side).

Furthermore, the support structure 47 may comprise an engagement structure 48 on a first side 47a and a second side 47b of the support structure, wherein the engagement structure 48 is configured to engage with the cell 26 and thereby properly align the partitioning device 45 with the cell 26.

In some examples, the partitioning device 45 may be bonded to the cell via the support structure 47. By bonding via the support structure 47 as opposed to the compressible sheet 46, shear forces may beneficially be primarily resisted by the support structure 47 instead of the compressible sheet 46, the material of which may be selected for superior compressibility and/or thermal properties but not for resisting such shear forces.

Hence, by bonding the cells 26 together via the support structure(s) 47 of the partitioning devices 45, the cells 26 may further resist crush load forces and serve as a structural part of the module 6 themselves. As shown in figure 11 , a partitioning device 45 may be placed between each cell 26 as well as between an end cell 26 and an end wall 28, thereby evenly distributing compressive forces to the module frame 20 from the cells 26.

As mentioned above, arranged over the cell layer 23, there may be an electrical management layer 21 comprising a venting layer 30 with venting valves 31 , aligned with the failure vents 40 of the cells 40, having corresponding apertures 25 in the heat shield layer 24 arranged thereover. The heat shield layer 24 may be bonded (e.g. in a fluid-tight manner) to the venting layer 30 via a bonding agent 52 such as heat-resistant glue or the like.

As can also be seen from the cross-sectional perspective of figure 11 , the electrodes 39 of the cells 26 may have busbars 37 aligned thereover to electrically connect the cells 26 in the cell layer 23 to the electrical management layer 21 .

In order to accommodate more cells 26 into a module 6, they may beneficially be integrated into the structure thereof. Thus, more of the volume and weight of the module 6 (which may have some prescribed maximum) can be afforded to the cells 26 themselves rather than other structural components. Thus, the overall energy density of a battery pack 1 can be improved.

One technique mentioned above for integrating cells 26 into the structure of the module 6 may involve bonding cells 26 together and to the module frame 20, in some examples, e.g. via the support structure(s) 47 of the partitioning device(s) 45.

Further techniques may involve adaptations and improvements of the module frame 20, for example as shown in figures 12 to 14. Figure 12 shows an isolated perspective view of a module frame 20 and figure 13 further isolates the beam 29 from the module frame 20, in perspective view.

Although not shown in figure 13, the beam 29 may further comprise a plurality of through holes, slots, or openings. Hence, the weight of the beam 29 may advantageously be reduced. The through holes may be spaced apart and configured to enhance airflow between the different sections 54a, 54b, 54c, 54d of the frame 20.

Figure 14a shows a top view of the module frame 20 with forces arrows added. Figures 14b and 14c show enlarged views of alternative configurations for the interfaces 51 b and 51c (collectively ‘interfaces 51’) between the beam 29 and the end walls 28. It will be appreciated that interface 51a in this example may be a mirror image of interface 51 b. As can be seen in figures 14a to 14c, the interface 51c between the end of the beam 29 and the walls 28e and 28f is configured to distribute a tension force T from along the beam 29 so as to impart a compressive force C in the end walls 28e and 28f. In this way, a swelling of cells bonded to the beam 29 can be safely absorbed by the structure of the module 20. In particular, it can be seen in figures 14a and 14c that the interface 51c is arranged between the two subwalls 28e and 28f that make up the end wall 28 of the module 20. It can be seen that the walls 28e and 28f respectively mate with opposite sides of the interface 51c.

Specifically, it can be seen that the inner connecting sides of the walls 28e, 28f are configured to interlock with the interface 51c such that the walls 28e, 28f form a substantially uninterrupted structural unit. Accordingly, the introduction of the interface 51c effectively couples the beam 29 to the walls 28e, 28f for a distribution of ferees therebetween, and without a substantial structural impact on the walls 28e, 28f.

In the alternative configuration of the interface 51c shown in figure 14c, the interface 51c comprises a first section extending at a first angle from the longitudinal axis of the beam 29, and a second section extending at a second angle from the first section, the first angle and the second angle summing to substantially 90 degrees. Hence, the second section is arranged substantially perpendicular to the longitudinal axis of the beam 29, thereby allowing the tension forces T to be effectively imparted onto the frame 20. The first section being angled at an intermediate angle between perpendicular and parallel (i.e. , in the range between 0 and 90 degrees, preferably between 30 and 60 degrees) allows for a translation of the tensional forces T along the longitudinal axis of the beam 29 to be transferred into compressive forces C along the length of the walls 28e and 28f.

In a further alternative example to that illustrated in figure 14c, the interface 51c comprises a first section extending at a substantially 90 degree angle from the longitudinal axis of the beam 29 to as to locally form an L- shape at the end of the beam 29. According to such an example, a simplified construction of the interface 51c is realized that is more straight-forward to manufacture.

Viewed from one perspective, it can be said that the module frame 20 serves the function of multiple modules and thus the number of modules 6 in a battery pack 1 can be reduced, and the size thereof can be increased, thereby simplifying the construction of such a battery pack 1 .

The module frame 20 is divided into four internal spaces 54a, 54b, 54c, and 54d (collectively ‘internal spaces 54’) by the intermediate end walls 28c and 28d as well as the beam 29. The beam 29 comprises bonding surfaces 53 for bonding cells 26 to and interfaces 51 for interfacing and structurally engaging with the module frame 20.

Cells 26 may thus be bonded (or otherwise fixed) to the bonding surfaces 53 and thereby be structurally integrated into the module 6. The cells 26 may be bonded using an adhesive (e.g. a structural glue or the like) such that mechanical stresses, e.g. arising from swelling/compression shear forces can be directly communicated into the beam 29. The beam 29 may then distribute these forces into the module frame 20 itself via interfaces 51 with the end walls 28.

As discussed above, the conversion of the swelling (S) forces from the cells 26 into tension (T) forces in the side walls 27 via interfaces 51 can be seen in figure 14a. The interface 51c, for example, can be seen redirecting the forces from cell 26 swelling into a compression (C) or bending force in the end walls 28e and 28f, which transfer this force (e.g. via a rigid connection) to the side walls 27a and 27b.

The beam 29 interfaces with the intermediate side wall (formed as a pair of sub-walls 28c and 28d) arranged between and parallel to the pair of end walls 27a and 27b. The pair of sub-walls 28c, 28d of the intermediate wall respectively abut either side of the beam 29 at the interface 51 b. Similarly to the interfaces 51a and 51c, the interface 51 b is configured to distribute forces from the beam 29 to the intermediate walls 28c, 28d.

As with the interface 51c interlocking with the walls 28e, 28f, the interface 51 b is configured with a profile to engage corresponding profiles on the pair of sub-walls 28c, 28d abutting said interface 51 b. A first example of such a profile is shown in figure 14a, and an alternative configuration is shown in figure 14b. Focusing on figure 14b, it can be seen that the profile of the interface 51 b is one that curves in a first direction, and then back on itself, thereby forming a serpentine profile. In alternative examples, the profile may comprise a zig-zag profile, an S-shaped profile, or a similar profile that allows for an ease of manufacture and an effective interlocking between the interface 51 b and the walls 28c and 28d that abut either side.

Thus, it can be seen that through configuration of the profiles of the interfaces 51 a, 51 b, 51 c, the geometry of the beam 29 itself can be used to facilitate and enhance the transfer of ferees, reducing a reliance on other joining means such as adhesive or fixings.

The interfaces 51 b and 51c shown in figures 14b and 14c are asymmetrical. Thus, the profile of the interfaces 51 b, 51c can advantageously serve as ‘poke-yoke’ features that ensure the end walls 28e, 28f and intermediate walls 28c, 28d are assembled in the correct manner.

The beam 29 is preferably formed from a material with a high strength to weight ratio, such as steel. In a preferred example, the beam 29 is formed from sheet steel of thickness 1 millimeter. In another preferred example, the beam 29 is formed from a thermally insulating composite configured to heat transfer between cells on either side of the beam 29. The material selection for such a thermally insulating composite may depend on the structural properties thereof.

Figure 15 shows an example part of a module 6 (e.g. corresponding to the lower half of the module frame 20 shown in figure 14) having a plurality of aligned cells 26 in two columns, the columns being separated by a beam 29. The illustrated module 6 has a failed cell 26F therein. For example, the cell 26F may have undergone a TR event or a similar failure, which may cause an expulsion of gases and/or other ejecta from the failure vent 40 of the failed cell 26. Next to the failed cell 26F is a neighboring cell 26N, discussion of which may also apply to a nearby cell 26 or any other cell in fluid communication with the failure vent 40 of the failed cell 26F.

If the beam 29 is configured with through holes, as discussed above, such through holes can advantageously create an air gap between cells 26 in different sections 54a, 54b, 54c, 54d, which can reduce heat transfer, e.g., in the event of a thermal runaway event.

As mentioned above, cells 26 in the module 6 may have arranged thereon a thermal sheath 41 which, in particular, may protect the upper-facing exposed surfaces of the cells 26 from heating up excessively (which may propagate failure throughout the module 6) as a result of convective heat transfer.

However, the gases from the failed cell 26F may preferably be vented from the module 6, such out of a module vent (not shown). A module vent may be provided in, e.g. end wall 28f, such that, when venting the module 6, the vented gases may pass over the other cells 26 including the neighboring cell 26N.

In some cases, the vented gases may comprise charged particles or the like which, if incident upon electrodes 39 of e.g. cell 26N, could cause short circuiting and thus damage to said cell 26N. Therefore, it may be desirable to implement a fluid isolation between the failure vents 40 of cells 26 in a module 6 such that vented gases and other ejected are at least primarily directed through a separate and isolated venting channel rather than directly over other cells 26.

To this effect, and according to aspects of the present disclosure, the module 6 may further comprise a heat shield layer 24 arranged between the cells 26 and a top wall (e.g. sealant layer 15) of the battery module 6 (or of the battery pack 1), thereby creating a module venting channel 59 between the heat shield layer 24 and the top wall.

The heat shield layer 24 may be configured to thermally insulate the cells 26 from the module venting channel 59. In some examples, the heat shield layer may comprise a layer of mica or another material with preferably low weight and high thermally insulative properties. For at least one cell (e.g. failed cell 26F), there may be provided a cell venting channel 60 configured to direct vented gases from the failure vent 40 of said cell 26F to the module venting channel 59. An example fluid flow upon failure of the cell 26F is illustrated in figure 19.

In the illustrated example shown in figures 16 to 19, the cell venting channel 60 may be connected to the module venting channel 59 via apertures 25 in the heat shield layer 24. The apertures 25 may align with venting valves 31 discussed above in the electrical management layer 21 . The venting layer 30 comprising the venting valves 31 may be sealed onto the cells 26 so as to form a chamber or ‘pocket’ around each failure vent 40.

The venting valves 31 in the venting layer 30 and/or the apertures 25 in the heat shield layer 24 may be formed by AM techniques, pressing, punching, laser cutting, or other such methods to create the three- dimensional forms of said components. The apertures 25 may taper into a slope 58 leading to the venting valves 31 to beneficially further guide vented gases from the cell venting channel 60 to the module venting channel 59.

The venting valve 31 may take any form and may be made out of the same or a different material as that used for the heat shield later 24. The venting valve 31 may, for example, have a plurality of flaps/teeth 56 and/or weakened points 57. In some examples, the flaps 56 and/or weakened points 57 may be cut using laser cutting or a similar precision cutting technique, before or after the protruding shape of the venting valves 31 (i.e. protruding from the venting layer 30) is formed.

The flaps 56 may advantageously retard fluid flow between the cell venting channel 60 and the module venting channel 59, such that vented gases flowing directly from a failure vent 40 of a failed cell 26F (e.g. undergoing a TR event) may have sufficient fluid velocity to push past and through the flaps 56 of the venting valve 31 and into the module venting channel 59, but once the vented gases are in the module venting channel 59, their fluid velocity may been retarded by passing through the flaps 56 (e.g. causing them to ‘flutter’) such that the hot vented gases do not have sufficiently high fluid velocity to substantially enter the cell venting channels 60 of other cells 26, e.g. neighboring cells 26N.

Additionally or alternatively, weakened points 57 may be provided in the configuration of the venting valves 31 . The weakened points 57 may be configured to cause a venting valve 31 to rupture in response to an excess of fluid pressure incident upon the venting valve 31 . For example, the weakened points 57 may be provided on (e.g. at an attachment point of) the flaps 56 such that the flaps 56 may flutter/flap in response to an incident fluid flow and break off if the fluid velocity exceeds a particular amount. Thus, the weakened points 57 may beneficially prevent vented gases with a high fluid velocity from, e.g., rupturing the bonding agent 52 and encroaching into another (e.g. a neighboring) cell venting channel 60.

Accordingly, cells 26 may beneficially be substantially fluidly isolated from each other, at least in respect of vented gases caused by TR events or similar such events. Thus, damage to other cells 26 in the module 6, and potential propagation of a failure, can be significantly mitigated as a result of the above described configuration of the module venting channel 59 and the cell venting channel(s) 60.

Another design of the venting channels 59, 60 is shown in figures 20 and 21. Similarly to the examples in figures 16-19, the heat shield layer 24 may comprise apertures 25 that align with the venting valves 31 of a module 6. Further, the top cover 14 may comprise a guiding structure forming the ceiling of a module venting channel 59 directing the vented gases from the failure vent 40 of a failed cell 26F to a vent gas channel 62 arranged at the side of the module 6, that is, in the frame 3. The top cover 14 may for instance be attached to the heat shield layer 24 by means of a venting channel sealing 61 defining the outline of the guiding structure defining the module venting channel 59 and its opening at the side of the module 6. The venting channel sealing 61 may for instance comprise an adhesive arranged at the heat shield layer 24 and/or the top cover 14. In further options the guiding structure comprises an elongated projection or rib 63 defining a boundary of wall of the module venting channel 59. The projection may for instance be formed by punching, stamping, milling or machining the top cover, and may be configured to form a seal with the venting channel sealing 61 shown in figure 21.

In some examples, the apertures 25 may be arranged in an elongated recess or groove formed in the heat shield layer 24 and extending to the edge of the module 6. The elongated recess may hence form part of a floor of the module venting channel 59 and act to further increase an open cross- sectional area of the module venting channel 59.

As mentioned in connection with figure 3 the battery modules 6 may be electrically interconnected by a module connector 10, or module busbar 10. An example of such a busbar 10 is illustrated in figure 22. Several different techniques for joining the busbar 10 and the modules 6 are conceivable, including welding and riveting. In the following, an example based on an interference fit principle will be discussed.

Figure 22 shows a busbar 10 configured to electrically interconnect a first and a second module 6’, 6”. The busbar 10 comprises a first connection plate 110’ and a second connection plate 110”, each of which being configured to be fitted with mating parts of a respective module terminal plate 120’, 120” of the first and second module 6’, 6”. The connection plates 110’, 110” may for instance comprise a plurality of through holes 111 adapted to receive a corresponding pin 121 of the module terminal plates 120’, 120”. The through holes 111 may beneficially be rounded, or circular, and the pins 121 provided with a quadrangular cross section, or vice versa. In alternative designs the pins 121 are arranged at the busbar 10 and the holes at the modules 6’, 6”. As the pins 121 are pressed into the holes 111 the material of at least one of the pins 121 and the holes 111 may deform to provide a reliable electrical and mechanical press-fit connection between the busbar 10 the modules 6’, 6”.

To further facilitate the fastening between the mating parts, the parts may be formed of different materials. The module terminal plates 120’, 120” may for example be formed of copper and the busbar 10 of aluminum. Since aluminum is known to deform more easily that copper, the (copper) pins 121 of the module terminal plates 120’, 120” may cause the holes in the (aluminum) connection plates 110’, 110” to plastically deform, thereby ensuring a reliable electrical and electrical interconnection between the modules 6’, 6”.

In some examples, the module terminal plates 120’, 120” and the connection plates 110’, 110” of the busbar may comprise the same material at the interface forming the joint between the modules 6’, 6” and the busbar 10 to reduce the risk of galvanic corrosion. The connection plates 110’, 110” may for instance comprise two different materials, with a cladding matching the material of the module terminal plates 120’, 120”. In one example, the module terminal plates 120’, 120” may be formed of aluminum (which is known to facilitate laser welding of the terminal plates 120’, 120”) to the module terminals, whereas the connection plates 110’, 110” may comprise a copper core covered by a layer of aluminum matching the material of the module terminal plates 120’, 120”.

Further, the portion of the busbar 10 interconnecting the connection plates 110’, 110”, also referred to as an interconnecting portion 112, may comprise a flexible portion allowing a relative movement between the two modules 6’, 6” to reduce the mechanical forces at the joint area. The flexible portion may for instance be formed of a braided conductor.

The press fit fastening of the busbar 10 advantageously saves space, as there is no need for additional structures such as bolts or rivets protruding in the z-direction, that is, orthogonally to the module terminal plates 120’, 120”. Further, alternative joining methods involving heating (such as welding) and/or addition of material (such as solder or rivets) generally require access by welding or riveting tools during the assembly process, which may add time, cost and complexity to the assembly line. The press fit busbar 10 provides a solution to this problem, as it can produce a joint by simply being pushed onto the module terminal plates 120’, 120”.

The press fit busbar 10 may also be relatively easily detached to facilitate replacement or repair of a faulty module, as well as recycling of the battery pack.

A further merit of the busbar 10 illustrated in figures 22 and 23 would be the arrangement of the interconnecting portion 112 of the busbar 10, which joins the connection plates 110’, 110”. The interconnecting portion 112 may be arranged in a plane intersecting the plane in which the module terminal plates 120’, 120”, thereby allowing the interconnecting portion 112 to be arranged at the side of the modules 6’, 6”. In the example illustrated in figures 22 and 23 the module terminal plates 120’, 120”, and hence the connection plates 110’, 110” of the busbar 10, may extend in an xy-plane and the interconnecting portion 112 in an orthogonal, xz-plane. This allows the interconnecting portion 112 to be arranged at the side of the modules 6’, 6”, between the modules and the pack frame 3 to save space in the z-direction.

Particular aspects

Aspects of the present disclosure are summarized below in numbered paragraphs, to assist with understanding of the present disclosure.

Aspect 1

A1 . A battery module comprising: a plurality of aligned secondary cells, each secondary cell of the plurality of secondary cells having a casing and a failure vent in the casing for venting gases upon thermal failure of the secondary cell; and a thermal sheath arranged on the casing of each secondary cell, in a fluid path between vented gases from other secondary cells in the plurality of secondary cells and the casing of said each secondary cell.

A2. The battery module according to paragraph A1 , wherein the thermal sheath is formed of mica.

A3. The battery module according to paragraph A1 or A2, wherein the thermal sheath has a body formed of a folded sheet, having a first side and second side for placement on faces of the cell which are to be proximate to neighboring cells, and a third side for placement on a top face of the cell.

A4. The battery module according to paragraph A3, wherein the thermal sheath further comprises one or more openings corresponding to the positions of the electrodes on the cell and/or an aperture corresponding to the position of a failure vent on the cell.

A5. The battery module according to paragraph A4, wherein the one or more openings corresponding to the positions of the electrodes on the cell comprise open slots extending from an edge of the folded sheet.

A6. The battery module according to any of paragraphs A1 to A4, wherein the thermal sheath is electrically insulating.

A7. The battery module according to any of paragraphs A1 to A5, wherein the thermal sheath is fixed to the cell, for example by adhesive.

A8. A method of manufacturing the thermal sheath according to any of paragraphs A2 to A7, comprising: folding a thermally insulating sheet to thereby form the thermal sheath.

A9. The method according to paragraph A8, further comprising: cutting, before said folding, an opening or aperture in the sheet.

A10. The method according to paragraph A8 or A9, wherein a plurality of thermal sheaths is cut from the same thermally insulating sheet.

Aspect 2

B1 . A base plate of a battery pack for an electric vehicle comprising: a first layer forming a top-side of the base plate, configured to provide an internal bottom wall of the battery pack; a second layer having recesses formed thereon for routing a coolant; and a third layer forming an underside of the base plate; wherein the second layer is interposed between the first layer and the third layer such that the recesses are enclosed by the first layer and/or the third layer so as to form coolant channels for routing coolant and thereby cooling the battery pack.

B2. The first layer may be formed of a thermally conductive layer of aluminum, steel or the like, or a thermally conductive plastic or composite material.

B3. The second layer may be formed of a thermally and electrically insulating layer of a low-density foam, plastic or a composite material.

B4. Preferably, the material is waterproof and configured to operate on a hot coolant environment for an extended period of time.

B5. The coolant channels may be milled, machined, molded, etched or the like.

B6. The third layer may be formed of a composite or plastic material, or a metal layer, having a relatively high impact resistance and mechanical strength to protect the battery pack from the external environment.

Aspect 3

C1 . A battery module comprising: a plurality of aligned secondary cells; and a partitioning device interposed between each of the plurality of aligned secondary cells and bonded thereto; wherein the partitioning device comprises a compressible sheet having a peripherally attached rigid support structure; and the partitioning device is bonded to the secondary cells via the rigid support structure.

C2. The battery module according to paragraph C1 , wherein the rigid support structure comprises a frame having a rectangular profile. C3. The battery module according to paragraph C2, wherein the frame is formed of two or three adjacent sides.

C4. The battery module according to any of paragraphs C1 to C3, wherein the rigid support structure is bonded to the compressible sheet and/or at least one of the secondary cells.

C5. The battery module according to paragraph C4, wherein adjacent secondary cells are bonded together via the rigid support structure arranged therebetween.

C6. The battery module according to any of paragraphs C1 to C5, wherein the rigid support structure further comprises an engagement structure on a first side and/or a second side of the support structure, configured to engage with a secondary cell and thereby align the partitioning device with the secondary cells.

Aspect 4

D1 . A battery module comprising: a plurality of aligned secondary cells, each secondary cell having a casing and a failure vent in the casing for venting gases upon thermal failure of the secondary cell; a heat shield layer arranged between the plurality of secondary cells and a top wall of the battery module, thereby creating a module venting channel between the heat shield layer and the top wall; wherein the heat shield layer is configured to thermally insulate the plurality of secondary cells from the module venting channel; and for each secondary cell, a cell venting channel configured to direct vented gases from the failure vent of said each secondary cell to the module venting channel. D2. The battery module according to paragraph D1 , wherein the heat shield layer comprises a plurality of apertures aligning with respective failure vents of the plurality of secondary cells.

D3. The battery module according to paragraph D2, wherein the heat shield layer is fixed to the plurality of secondary cells such that the cell venting channels are formed through the plurality of apertures.

D4. The battery module according to any of paragraphs D1 to D3, further comprising a venting layer arranged between the plurality of secondary cells and the heat shield layer, wherein the venting layer comprises a plurality of shaped valves configured to be arranged above respective venting valves of the plurality of secondary cells, and wherein the heat shield is bonded around a periphery of each of the shaped valves of the venting layer.

D5. The battery module according to paragraph D4, wherein the shaped valves are shaped so as to form the cell venting channel.

D6. The battery module according to paragraph D4 or D5, wherein the shaped valves comprise flaps configured to retard fluid flow between the cell venting channel and the module venting channel.

D7. The battery module according to any of paragraphs D4 to D6, wherein the shaped valves further comprise weakened points configured to cause a shaped valve to rupture in response to an excess of fluid pressure incident upon said shaped valve.

Aspect 5

E1 . A frame for a battery module, comprising: one or more walls arranged to enclose a space for containing internal components of the battery module; wherein at least one wall of the one or more walls is formed of a non- metallic material; and said at least one wall comprises a rigid reinforcement structure.

E2. The frame according to paragraph E1 , wherein all of the one or more walls is formed of the non-metallic material.

E3. The frame according to paragraph E1 or E2, wherein the non-metallic material is a composite material.

E4. The frame according to any of paragraphs E1 to E3, wherein the rigid reinforcement structure comprises an open cellular structure.

E5. The frame according to paragraph E4, wherein the open cellular structure comprises a zig-zag structure forming a plurality of triangular prisms extending along a height of the one or more walls.

E6. The frame according to paragraph E4 or E5. further comprising a sensor arrangement arranged within the open cellular structure.

E7. The frame according to paragraph E6, wherein the sensor arrangement forms part of a battery management system.

Aspect 6

F1. A battery module comprising: a frame comprising a pair of side walls and a pair of end walls; at least one beam extending parallel to the pair of side walls between the pair of end walls, thereby defining a first internal space between a first side of the beam and a side wall of the pair of side walls, and a second internal space between a second side of the beam and the other side wall of the pair of side walls; a first plurality of secondary cells arranged in the first internal space aligned in a first column between the pair of end walls; a second plurality of second cells arranged in the second internal space aligned in a second column between the pair of end walls; wherein the first plurality of secondary cells are fixed to the first side of the beam and the second plurality of secondary cells are fixed to the second side of the beam.

F2. The battery module according to paragraph F1 , further comprising a first interface between an end of the at least one beam and one of the end walls, the first interface being configured to distribute a force from along the beam to said one of the end walls.

F3. The battery module according to paragraph F2, wherein said one of the end walls comprises two sub-walls, and the first interface is arranged between the two sub-walls.

F4. The battery module according to paragraph F3, wherein the two-walls are configured to respectively mate with opposite sides of the first interface.

F5. The battery module according to any of paragraphs F2 to F4, wherein the first interface comprises a first section extending at a first angle from the longitudinal axis of the beam, and a second section extending at a second angle from the first section, the first angle and the second angle summing to substantially 90 degrees.

F6. The battery module according to any of paragraphs F2 to F4, wherein the first interface comprises a first section extending at a substantially 90 degrees from the longitudinal axis of the beam.

F7. The battery module according to any of paragraph F1 to F6, further comprising an intermediate wall arranged between and parallel to the pair of end walls, wherein the intermediate wall is formed as a pair of sub-walls either side of the beam.

F8. The battery module according to paragraph F7, wherein the pair of sub-walls of the intermediate wall respectively abut either side of the beam at a second interface, the second interface being preferably configured to distribute forces from the beam to the intermediate wall.

F9. The battery module according to paragraph F8, wherein the second interface is configured with a profile to engage corresponding profiles on the pair of sub-walls abutting the second interface.

F10. The battery module according to paragraph F9, wherein the profile comprises a zig-zag profile, a serpentine profile, or an S-shaped profile.

F11 . The battery module according to any of paragraphs F1 to F10, wherein the at least one beam is formed from steel, preferably from sheet steel of thickness 1 millimeter.

F12. The battery module according to any of paragraphs F1 to F11 , wherein the at least one beam comprises one or more through holes, the through holes being preferably configured to enable airflow between the first internal space and the second internal space.

Aspect 7

G1 . A battery module comprising: a plurality of aligned secondary cells; and a busbar configured to electrically interconnect at first and a second one of the plurality of secondary cells; wherein the busbar comprises a first connection plate adapted to be attached to a first terminal plate of the first secondary cell and a second connection plate adapted to be attached to a second terminal plate of the second secondary cell; and wherein the first and second connection plates comprises interlocking structures configured to engage corresponding interlocking structures of the first and second terminal plates. G2. The interlocking structures of the first and second connection plates may comprise through holes and the corresponding interlocking structures of the first and second terminal plates may comprise pins arranged to be fitted in the through holes.

G3. The through holes may have a circular cross section and the pins a quadrangular cross section, such that the pins and/or holes are deformed when pushed together, thereby producing a tight mechanical joint. It will be appreciated that, although the above aspects are presented separately, they may be combined in any suitable manner such that a battery pack may benefit from all of the advantages provided by respective aspects of the present disclosure. Furthermore, while the foregoing description and the appended drawings are provided as exemplary or preferred realizations of the disclosed aspects, it will be appreciated that the disclosed aspects need not be limited to the exact form shown and/or described.

Claims

1 . A battery module comprising: a frame comprising a pair of side walls and a pair of end walls; at least one beam extending parallel to the pair of side walls between the pair of end walls, thereby defining a first internal space between a first side of the beam and a side wall of the pair of side walls, and a second internal space between a second side of the beam and the other side wall of the pair of side walls; a first plurality of secondary cells arranged in the first internal space aligned in a first column between the pair of end walls; and a second plurality of second cells arranged in the second internal space aligned in a second column between the pair of end walls; wherein the first plurality of secondary cells are fixed to the first side of the beam and the second plurality of secondary cells are fixed to the second side of the beam.