EP4463911A1

EP4463911A1 - Battery pack, and assembling process for manufacturing a battery pack

Info

Publication number: EP4463911A1
Application number: EP23700359.5A
Authority: EP
Inventors: Claudio Mingazzini; Daniele Pullini; Matteo Basso
Original assignee: Centro Ricerche Fiat SCpA; Agenzia Nazionale per le Nuove Tecnologie lEnergia e lo Sviluppo Economico Sostenibile ENEA
Current assignee: Centro Ricerche Fiat SCpA; Agenzia Nazionale per le Nuove Tecnologie lEnergia e lo Sviluppo Economico Sostenibile ENEA
Priority date: 2022-01-12
Filing date: 2023-01-12
Publication date: 2024-11-20
Also published as: WO2023135546A1

Abstract

A battery pack (4), in particular for vehicles (1), has a plurality of storage modules (10a, 10b), which are arranged along at least one row (11a) inside an external housing structure (13) and are separated from one another by an internal structure provided with at least one corrugated wall (16a).

Description

BATTERY PACK, AND ASSEMBLING PROCESS FOR MANUFACTURING

A BATTERY PACK

Cross-Reference to Related Applications

This Patent Application claims priority from Italian Patent Application No. 102022000000386 filed on January 12, 2022 the entire disclosure of which is incorporated herein by reference.

Technical Field of the Invention

The present invention relates to a battery pack, with a configuration which is considered of high interest, in particular, for the transportation sector, for example for motor vehicles.

State of the Art

As is known, in the sector of the electric power supply by means of batteries, especially in the vehicle field, the need is felt to ensure high levels of safety with regard to the risks of fires. Generally, in vehicles that adopt battery packs, the latter are each formed by a plurality of storage modules accommodated in a housing structure: such structure has to have suitable expedients for physically separating each module from the adjacent ones, so as to ensure that the possible fire on one of such modules does not entail either a chain degeneration, or the fact of compromising the integrity of the external walls of the housing structure.

Simultaneously, within the scope of fireproof components (e.g. in the aeronautical sector), the possibility is known to manufacture flat plates made of “metal composite laminates”, or FML (acronym for the term “Fibre-Metal laminates”), manufactured by coupling at least one layer of polymer reinforced by fibres (e.g. in the form of prepreg), and at least one metal sheet (typically made of aluminium, but also of titanium or steel). Alternating metal sheets and layers of fibre- reinforced polymer ensures lightening the metal parts, since the fibres allow a high resistance to traction, which improves the overall mechanical performances, whereas the presence of the metal sheets, even if having a low thickness, carry out a barrier function for containing the fire and preventing the air from entering into contact with the polymeric matrix where the fibres are embedded (considering that such matrix is combustible, even if generally chosen so as to be a flame-retardant).

In the light of their effectiveness, there is extreme interest in using these materials for manufacturing structures that house the modules of the battery packs. For example, document EP2617080 shows an external casing for a battery, formed by walls made of FML. However, such solution is not sufficient for being applied to a battery pack formed by more modules, which should be separated and insulated from one another. To such regard, in fact, the desire is to devise a solution which optimally protects each module, with respect to the adjacent ones (besides providing a protection along the external lateral walls of the battery pack).

Within this scope, the need is felt to provide a battery pack which requires relatively simple and cost-effective production and assembling processes, also in the light of the known technological difficulties associated with the cutting and joining of the semifinished products made of FML, operations which would be necessary for containing each single battery module starting from such semifinished products. More specifically, it is suitable for such production and assembling processes to be automated, so as to be utilised on a large scale and/or be adapted in a relatively simple manner to different production lines.

Furthermore, the need is felt to reduce to the minimum the discontinuities and/or the openings present in the elements made of FML to be mounted in the battery packs, so as to limit the number and/or the extension of the edges with parts of polymeric matrix exposed to air and thus to oxygen.

Simultaneously, preferably, it is suitable for the features of the battery pack to allow an easy disassembly of the components, both for a possible maintenance, removal, replacement and recycling of the storage modules, and for the recycling of the materials used for said elements made of FML, for an end-of-life reuse thereof.

Object and Summary of the Invention

The object of the present invention is thus to provide a battery pack, which allows satisfying the above-mentioned needs in a simple and cost-effective manner and, in particular, has a housing structure which can be easily manufactured starting from semifinished products made of FML, so as to obtain the desired features of fire resistance, lightness and resistance.

According to the present invention, a battery pack is provided, in particular for vehicles, as defined in claim 1. The present invention further relates to an assembling process for manufacturing a battery pack, as defined in claim 11.

Brief Description of the Drawings

The invention will now be described with reference to tire accompanying drawings, which illustrate a non-limiting example embodiment thereof, wherein: - Figure 1 illustrates, in perspective and in a simplified manner, a bottom part of a vehicle, provided with a preferred embodiment of the battery pack according to the present invention;

Figure 2 shows an exploded view of the battery pack of Figure 1;

Figure 3 shows, on an enlarged scale, a detail of Figure 2; and

Figures 4 to 11 show a series of subsequent steps for assembling the battery pack according to the principles of the present invention.

Description of Preferred Embodiments of the Invention

In Figure 1, reference numeral 1 indicates, as a whole, a vehicle (partly illustrated), which comprises a body 2 (schematically illustrated) defining a seat 3 which accommodates a battery pack 4 defining a preferred embodiment of the battery pack according to the teachings of the present invention.

Such teachings apply, in general, not only to the automotive field and to the transportation sector, but to any application which has the need to store electric energy, even if Figure 1 refers to the specific vehicle example.

In such specific example, in particular, the seat 3 is obtained at a floor 5 of the body 2, hence the battery pack 4 is arranged under a passenger compartment and/or a loading compartment (not illustrated) of the vehicle 1.

In particular, the seat 3 and the battery pack 4 extend in length along a rectilinear axis 6 which corresponds to the forward longitudinal direction of the vehicle 1. As is shown in Figure 2, the seat 3 is closed at the bottom, preferably tight, by a base 7 having an upper surface on which the battery pack 4 rests. More in particular, the seat 3 also accommodates a control and interface unit 9 which is electrically connected to the battery pack 4, by means of wirings not illustrated. The battery pack 4 comprises a plurality of rechargeable storage modules 10, and the unit 9 is configured to transfer the electric current between the storage modules 10 and the electrical system of the vehicle 1, to monitor the state of charge and the efficiency of the modules 10, etc..

The storage modules 10 are arranged in positions aligned and adjacent to one another. In the particular illustrated example, the storage modules 10 are aligned along a series of rows parallel to one another, and along a series of lines, which are orthogonal to such rows (in Figure 4, and in the following figures, the rows are indicated by 1 la and 1 lb, and the lines by 12a and 12b). In other words, the storage modules 10 are arranged at the intersections between the above-mentioned rows and the above-mentioned lines, so as to form a sort of grid.

In simpler embodiments, not illustrated, the battery pack 4 could also theoretically include one single row of modules 10. Still with reference to the exploded view of Figure 2, the battery pack 4 comprises an external housing structure 13 which accommodates the storage modules 10 and can be manufactured according to the prior art, in the form of simple box.

In the particular illustrated example, the housing structure 13 comprises a frame 14, for example made of steel, arranged in the seal 3 and defining an internal compartment 15 which houses the modules 10.

According to a variation not illustrated, the frame 14 can be absent, hence the compartment 15 is directly defined by the walls of the seat 3.

The storage modules 10 can be divided into four sets, indicated by reference numerals 10a, 10b, 10c, 10d respectively: the modules 10a and 10b are arranged, in alternate positions between one another, along rows 1 la (Figures 4-6), whereas the modules 10c and 10d are arranged, in alternate positions between one another, along rows lib (Figures 8-10); the rows lib, in turn, are alternate to the rows 11a (in the particular illustrated example, the rows are in all five, three identified by 1 la and two identified by lib).

It is thus clear that the modules 10a are aligned and alternate to the modules 10c along lines 12a (Figure 8), whereas the modules 10b are aligned and alternate to the modules 10d along lines 12b (Figure 10); the lines 12b, in turn, are alternate to the lines 12a.

According to the present invention, the battery pack 4 comprises an internal structure, in the compartment 15, composed of corrugated walls defining a compartmentalisation which keeps the single modules 10 separated from one another. Specifically, the arrangement of such internal structure provides, for each of the rows 11a and 11b, a respective corrugated wall 16a and 16b (Figure 5 and 9). Each wall 16a houses the modules 10a and 10b, and separates them from one another along the corresponding row 11a (Figure 6), whereas each wall 16b houses the modules 10c and 10d, and separates them from one another along the corresponding row lib (Figure 10).

As is evident in Figures 6 and 7, the walls 16a are parallel and spaced apart so as to be separated from one another by channels 24, which are respectively engaged by the rows 1 lb (and thus by the walls 16b and by the modules 10c and 10d).

Figure 3 shows a detail of the battery pack 4, for one of the walls 16a and the modules 10a and 10b, but the configuration is also similar for the walls 16b and the modules 10c and 10d. As is visible in such figure, the wall 16a is composed of a succession of waves, each of which defines two seats 18 and 19, which are facing in opposite directions to one another and house respective modules 10a and 10b, which as above-mentioned are adjacent to one another along the corresponding row 11a. Each wave comprises a septum 20, which is orthogonal to the corresponding row 11a and separates the seats 18 and 19 from one another. In other words, the septum 20 is interposed between a rear face of the module 10a and a front face of the module 10b. Simultaneously, each wave of the wall 16a comprises a crest portion 21, which covers the upper face of the module 10a, and a downstream portion 22 which covers the lower face of the module 10b.

In a direction orthogonal to the rows 11a, 11b and parallel to the lines 12a,12b, each of the walls 16a,16b has a constant width equal to that of the modules 10a and 10b, so as to entirely cover them, but without having laterally protruding portions.

The profile of the waves, preferably, corresponds to the shape and to the external dimensions of the modules 10, so as not to leave clearances with respect to the faces of the storage modules 10 and thus reduce to the minimum the content and the flow of air, i.e. of oxygen, inside the battery pack 4. Possible spaces or clearances can anyway be provided during the design phase (for example along the comers of the corrugated walls), to be used for passing the electrical wirings.

Each seat 17,18 accommodates a single storage module, in a direction parallel to the rows 11a, 11b: in other words, the semi-period of the waves of the walls 16a and 16b is equal to the dimension of the modules 10, measured in a direction parallel to the rows 11a, 11b (disregarding the thickness of the walls 16a and 16b, by approximation).

In the illustrated example, the storage modules 10 are parallelepipeds, hence the waves of the walls 16a,16b are square waves. However, the external shape of the storage modules 10 and, consequently, the profile of the waves of the walls 16a,16b could be different: for example, the parallelepiped shape could be obtained by assembling smaller cells or units having another shape, comprising the cylindrical shape and consequently the profile of the waves of the walls 16a, 16b could have a curved part so as to better adapt thereto.

With reference to Figures 2 and 7, according to a preferred aspect of the present invention, the battery pack 4 comprises a corrugated wall 16c, in addition to the walls 16a and 16b, with waves oriented orthogonally with respect to the orientation provided in the walls 16a and 16b. The wall 16c is advantageously utilised when the battery pack 4 includes at least two rows of modules, as in the preferred illustrated solution, so as to separate such rows: therefore, in the illustrated example, the wall 16c comprises septums 25 which are orthogonal to the lines 12a and 12b for separating the lateral faces of the modules 10a from those of the modules 10c, along the lines 12a (Figure 8), and the lateral faces of the modules 10b from those of the modules 10d, along the lines 12b.

More specifically, with reference to Figure 7, each wave of the wall 16c defines two parallel channels 26 and 27 (Figure 7), facing in opposite directions to one another and separated from one another by a corresponding septum 25. Each channel 26 accommodates a corresponding wall 16a (with the respective modules 10a and 10b), whereas each channel 27 accommodates a corresponding wall 16b (with the respective modules 10c and 10d). Furthermore, the waves of the wall 16c comprise respective crest portions 28, which cover the upper faces of the modules 10b, and respective downstream portions 29 defining a cover and a support for the lower faces of the modules 10c.

In a direction parallel to the rows 11a, 11b and orthogonal to the lines 12a, 12b, the wall 16c has a width equal to the extension of the set of the modules 10a and 10b and of the set of the modules 10c and 10d.

In a direction parallel to the lines 12a, 12b, each channel 25,26 accommodates one single row of storage modules: in other words, the semi-period of the waves of the wall 16c is equal to the dimension of the modules 10, measured in a direction parallel to the lines 12a, 12b (disregarding the thickness of the wall 16c, by approximation).

Finally, as is shown in Figures 2 and 11, the housing structure 13 comprises a cover 30 which closes at the top the compartment 15 and is thus arranged on the crest portions 28 of the wall 16c, on the crest portions of the walls 16b and on the upper faces of the modules 10d.

Going back to what is shown in Figures 4 to 11 , the battery pack 4 is preferably assembled by means of the following steps:

- the modules 10a are arranged on a support surface (defined by the wall 7 or by a different holding base), in alternate positions along the rows 11a and along the lines 12a (Figure 4);

- the walls 16a are arranged on the modules 10a, in positions spaced apart so as to leave the channels 24 free, and so as to house the modules 10a in the seats 18, which are facing downwards (Figure 5);

- the modules 10b are arranged on the downstream portions of the walls 16a and thus housed in the seats 19, which are facing upwards (Figure 6); the wall 16c is arranged so as to house the walls 16a and the rows 11a in the channels 26 (which are facing upwards), whereas the channels 27 (which are facing upwards) overlap the channels 24 (Figure 7); the modules 10c are arranged in the channels 27, on the downstream portions of the wall 16c, in alternate positions between one another along the rows 1 lb and along the lines 12a (Figure 8); the walls 16b are arranged on the modules 10c, so as to house the latter (Figure 9); the modules 10d are arranged on the downstream portions of the walls 16b and thus housed in the walls 16b (Figure 10); the battery pack 4 is sealed at the top by the cover 30.

It is thus clear that: each module 10a is completely enclosed between the base 7, the corresponding wall 16a and the wall 16c; each module 10b is completely enclosed between the corresponding wall 16a and the wall 16c; each module 10c is completely enclosed between the corresponding wall 16b and the wall 16c; each module 10d is completely enclosed between the corresponding wall 16b, the wall 16c and the cover 30.

Consequently, it is evident that each storage module 10 is completely separated with respect to the others.

In order to pass the wirings, it is possible to make holes through the above- mentioned corrugated walls, according to techniques known per se. Obviously, the diameter of such holes has to be the smallest possible, so as not to compromise the fire-barrier function.

With respect to the preferred solution illustrated in the accompanying figures, simplified variations (not illustrated) can be adopted, which anyway use at least one corrugated wall for accommodating the storage modules, according to the principles of the present invention. For example, the wall 16c can be replaced by one or more U-sections or by one or more flat walls (orthogonal to the lines 12a, 12b) for defining the septums 25 which separate the rows 11a, 11b from one another; and/or each of the seats 18,19 of the walls 16a, 16b can be dimensioned by design so as to accommodate more than one storage module (especially if they are relatively small).

In the battery pack 4 shown by way of example, one single layer of storage modules 10 on top of the base 7 is provided, hence the height of the housing structure 13 and, thus, of the battery pack 4, substantially corresponds to the height of said storage modules 10 (disregarding the thickness of the walls, by approximation). Variations (not illustrated) having more layers of storage modules, stacked vertically, can anyway be adopted.

Furthermore, according to variations not illustrated, the battery pack 4 could be oriented differently with respect to what illustrated by way of example in Figures 1 and 2, for example by vertically arranging the base 7, the cover 30 and the bendings forming the waves of the walls 16a, 16b.

The utilisation of one or more corrugated walls according to the present invention is particularly advantageous when such corrugated walls are manufactured starting from flat semifinished products having at least two layers coupled to one another, one defined by a metal sheet and the other one by a fibre-reinforced polymeric material. Falling within this type of semifinished products there are the products commonly known as FMLs (“fibre-metal laminates”), as well as similar products obtained by means of techniques different from the lamination.

In particular, Figure 3 shows, on an enlarged scale, the corrugated walls of the battery pack 4 having external surfaces defined by respective layers made of metal 32,33 (for example, of an aluminium alloy) arranged on opposite sides of an intermediate layer 34, composed of a resin or polymer reinforced by fibres. In general, with respect to what illustrated, the number of layers can be different, and/or at least one of the external surfaces of the walls 16a,16b,16c can be defined by the fibre reinforced polymer instead of being metallic (for example, in the cases when it is pre-eminent to ensure an electrical insulation along such external surface).

In the present case, the layers 32 and 33 have the sole fireproof function, and not a structural holding function. Consequently, the thickness of each metal layer present in the walls 16a, 16b, 16c is relatively low, i.e. less than 0.2 mm (typically around 0.1 mm).

The available technologies and the specific materials usable for producing these flat semifinished products are many and are not described herein, since they are generally known and/or in phase of experimental research and development, and do not fall within the scope of the present invention.

By using corrugated walls with this type of semifinished products, the advantages are essentially the following.

First of all, the corrugated walls are relatively wide, such to cover the entire extension of the battery pack 4, from one side to the other of the external housing structure 13, and do not have discontinuities (with the exception of the small holes made for passing the electrical wirings). Therefore, there is a reduction to the minimum of:

- the passing of air (i.e. oxygen) towards each storage module 10 inside the battery pack 4, and

- the number and/or the extension of the edges with parts of polymeric matrix exposed to air/oxygen, hence, the fire-barrier performances are optimal.

Furthermore, in order to obtain the corrugated walls, only bending operations are necessary, hence cutting and/or moulding operations of complex shapes are avoided. In particular, in order to obtain each of the walls 16a, 16b, 16c, the deformations are exclusively defined by bending lines (or curvatures), which all extend parallel to one another. In this manner, a high precision in the shapes and dimensions of the walls 16a, 16b, 16c is obtained, in a relatively contained time and without compromising the structural features of the materials present in the starting flat semifinished products. For example, it is possible to use a mould configured to simultaneously form the bending lines or, preferably, a hot press configured to form one step at a time (and simultaneously polymerise the matrix of the composite material).

In particular, the hot presses that mould one step at a time, on the one hand, allow automating at least part of the bending process and are suitable for large-scale productions (in comparison with pressings in autoclave) and, on the other hand, are configurable to adapt the production to specific dimensions and shapes of the storage modules to be housed in the battery pack. In fact, in the known equipment already available for forming the corrugated walls starting from flat semifinished products, it is possible to set and adjust the step (or semi-period) and/or the shape of the waves in a relatively simple and quick manner, based on the needs of the production line. Therefore, this type of equipment production can be applied to the vehicle applications in an extremely advantageous manner.

Furthermore, the battery pack 4 can be disassembled in a relatively simple manner, for carrying out maintenance operations on the storage modules 10 and/or for the end-of-life recovery of the walls 16a, 16b, 16c. In particular, the walls 16a, 16b, 16c are easily demounted, since they simply rest on the other components, without any fixings which require particular equipment and/or a long operation time for the removal. Once removed at end-of-life, the walls 16a, 16b, 16c can be subject to a flattening to then be reused, for example newly hot pressed, for a similar application or also different from the one provided according to the present invention.

It is then evident that the materials composed of alternate layers made of metal and composite are particularly advantageous with regard to the lightness and the resistance to the impacts of the internal structure (for example: with respect to a structure entirely made of steel, a reduction in weight is obtained of approximately 40%). In order to increase these advantages, also the frame 14 and/or the cover 30 and/or the base 7 can be made of FML materials. However, generally, the concept of using corrugated walls in battery packs can also be applied for different materials (for example, simple metal sheets or composite materials, possibly intumescent, fire- retardant or with fireproof coatings).

Based on the foregoing, it is then evident that the number of components of the internal structure is relatively low and the corrugated walls 16a, 16b, 16c, as above- mentioned, can simply be resting, without the strict need for fixings for being blocked with respect to the external housing structure 13. In particular, the dimensions of the walls 16a,16b,16c are established by design depending on the shape and dimensions of the storage modules 10 and preferably dtpending on the space available in the compartment 15, so as not to leave clearances with respect to the frame 14 and/or the cover 30.

Based on the foregoing, it is finally evident that modifications and variations can be made to the battery pack 4 and to the relative assembling procedure above-described with reference to the accompanying figures, which do not depart from the scope of protection of the presort invention, as defined in the appended claims.

In particular, as already above-mentioned, the number, the positioning and the shape of the corrugated profile of the walls 16a, 16b, 16c can be different from what described and illustrated, depending of the type, number, external shape and arrangement of the storage modules in the compartment 15.

Claims

CLAIMS 1. A battery pack (4), comprising: first storage modules (10a,10b), arranged along at least one first row (11a); an internal structure for compartmentalising said first storage modules (10a,10b); an external housing structure (13), that accommodates the storage modules and the internal structure; characterised in that said internal structure comprises at least one first corrugated wall (16a).

2. The battery pack according to claim 1, wherein said first corrugated wall (16a) defines at least two seats (18,19), which are facing in opposite directions to one another, are separated from one another by a first transverse septum (22), forming part of said first corrugated wall (16a), and house respective first storage modules (10a, 10b).

3. The battery pack according to claim 1 or 2, wherein said first corrugated wall (16a) has a constant width, measured in a direction orthogonal to said row (11a); said width being substantially equal to that of said first storage modules (10a, 10b).

4. The battery pack according to any one of the preceding claims, wherein said first corrugated wall has at least one wave with a semi-period substantially equal to a dimension of said first storage modules (10a,10b), measured in a direction parallel to said first row (11a).

The battery pack according to claim 2, wherein each of said seats (18,19) accommodates only one of said first storage modules (10a, 10b).

6. The battery pack according to claim 4 or 5, wherein said corrugated wall (16a) has a corrugated profile complementary to the external shape of said first storage modules (10a, 10b), e.g. a square wave profile.

7. The battery pack according to any one of the preceding claims, comprising second storage modules (10c,10d), which are arranged along at least one second row (11b), parallel to said first row (11a), and are separated from said first storage modules (10a, 10b) by a second transverse septum (25); and wherein said internal structure comprises a second corrugated wall (16b) configured to house said second storage modules.

8. The battery pack according to claim 7, wherein said internal structure further comprises a third corrugated wall (16c) defining al least two channels (26,27), facing in directions opposite to each other, one of the channels housing said first corrugated wall (16a) and said first storage modules (10a,10b), and the other of the channels housing said second corrugated wall (16b) and said second storage modules (10c, 10d); said second transverse septum (25) forming part of said third corrugated wall (16c).

9. The battery pack according to any one of the preceding claims, wherein said first corrugated wall (16a) comprises at least two layers coupled to one another; one of said layers being defined by a metal malerial and the other of said layers being defined by a fibre-reinforced polymeric material.

10. The battery pack according to claim 9, wherein said first corrugated wall (16a) has two external surfaces defined by respective layers made of metal material.

11. An assembling process for manufacturing a battery pack according to claim 8, the process comprising the steps of: arranging a first set (10a) of said first storage modules (10a, 10b) on a support surface (7), in positions spaced apart along said first row (11a); arranging said first corrugated wall (16a) on the storage modules of said first set (10a), so as to house them in respective seats (18) of said first corrugated wall (16a); arranging a second set (10b) of said first storage modules (10a, 10b) in further seats (19) of said first corrugated wall (16a), in alternate positions to the storage modules of said first set (10a) along said first row (11a); arranging said third corrugated wall (16c) so as to house said first corrugated wall (16a) and said first storage modules (10a,10b) in a channel (25) of said third corrugated wall (16c); arranging a third set (10c) forming part of said second storage modules (10c, 10d) in a further channel (27) of said third corrugated wall (16c) in positions spaced apart along said second row (11b); arranging said second corrugated wall (16b) in said further channel (27) on the storage modules of said third set (10c), so as to house them in respective seats of said second corrugated wall (16b); arranging a fourth set (10d) forming part of said second storage modules (10c, 10d) in further seats of said second corrugated wall (16b), in alternate positions to the storage modules of said third set (10c) along said second row (10b); arranging a cover (30) to cover the storage modules of said fourth set (10d).