Prismatic battery cells, battery packs, and road vehicles

Abstract

To provide a prismatic battery cell, a corresponding battery pack, and a road vehicle that are at least partially free from the shortcomings of prior art, while also being easy and economical to manufacture. [Solution] The prismatic battery cell (6) includes a box-shaped metal case (9) including a first base wall (11) and a second base wall (12) facing each other along the longitudinal axis (L) of the cell; a stack (10) including a plurality of electrode plates (19) alternately spaced apart by foil of separator material; and an exhaust system (24) configured to allow gas to escape from the inside to the outside of the box-shaped metal case (9) when the pressure inside the box-shaped metal case (9) exceeds a predetermined threshold, wherein the exhaust system (24) is located in the region of the first base wall (11) and / or the second base wall (12) and is configured to use the first base wall (11) and / or the second base wall as valves.

Description

Technical Field

[0001] Cross - reference to related applications This patent application claims priority from Italian Patent Application No. 102024000029331, filed on December 20, 2024, the entire disclosure of which is incorporated herein by reference.

[0002] The present invention relates to prismatic battery cells commonly used to form battery modules containing a plurality of prismatic cells arranged in a row, for the transport industry, for example for combustion / electrically driven electric motor vehicles and hybrid motor vehicles.

[0003] In particular, the present invention can advantageously be applied to high - performance electric (or hybrid) road vehicles, although not exclusively, and this will be explicitly referred to hereinafter for the sake of generality without loss of generality.

Background Art

[0004] As is known, electric or hybrid vehicles include a battery pack, which in turn consists of a plurality of electrical energy storage modules, generally called "battery modules", arranged in positions close to / adjacent to each other within a support structure. Next, each battery module includes a case and a plurality of battery cells arranged in the case in positions arranged in a row or block.

[0005] In the case of prismatic battery cells, each battery cell is provided with a parallelepiped - shaped (usually called a can) metal shell generally made of aluminum, having an upper side where two electrical connectors protrude, which respectively define the two electrodes of the battery, namely the anode and the cathode. The two electrical connectors are electrically insulated from each other and from the battery cell shell, and are electrically connected in series to adjacent battery cells within the same battery module by connection elements (sometimes called "current collectors").

[0006] In particular, each cell contains electrode plates, which are formed by a notching process, usually laser or mechanical notching, exposing small terminal tabs that are aligned with each other. These are typically welded to each other, followed by a (greater thickness) connecting element, which is then welded to the exposed electrical connector of the battery cell. The latter is then connected to the outside of the battery module case to supply the expected voltage.

[0007] This type of cell has several drawbacks. First, the presence of tabs necessitates precision in stacking the electrode plates. Furthermore, the tabs themselves increase the electrical resistance of the cell, resulting in an increase in temperature.

[0008] Each battery cell also has a safety valve (or, in any case, a preferential failure zone with an opening defined in case of the need for exhaust) configured to limit pressure in case of possible gas release into its respective shell, for example, to prepare for thermal instability. The safety valve is usually located on the upper side of the shell, midway between the two electrical connectors. Gas released through the safety valve occupies the upper volume of the battery module and can then flow out into the empty upper zone of the battery pack.

[0009] As is well known, battery packs are mounted in the vehicle in the area of ​​the floorboard, with precautions to ensure safety in the event of collisions and possible intrusions from below. For this purpose, space is generally provided below the battery module, separating the latter perpendicularly from the wall defining the bottom of the vehicle towards the road surface.

[0010] In particular, the aforementioned space separates the vehicle's bottom wall from the cooling system, which is typically provided to cool the battery modules from below. This cooling system is actually represented by a horizontal plate, which has multiple channels through which heat exchange fluid flows and is located in the area of ​​the base of each battery module.

[0011] When dealing with these known solutions, it is necessary to reduce the vertical dimensions while continuing to meet the safety requirements outlined above regarding collisions and potential intrusions from below.

[0012] In fact, the vertical dimension of the known solution mentioned above is a sum of several additive factors, namely, A space provided above the underside of the vehicle for safety against collisions and intrusions from below. The height required for the horizontal cooling plate, Typical height of a battery module, and The empty upper area of ​​the battery pack, from which any gases released by the battery cells can be vented. It is relatively large because it is made up of [something].

[0013] In addition to reducing vertical dimensions, there is a further need to improve the efficiency of the cooling system of known solutions. In this regard, known solutions with horizontal cooling plates are quite simple, but they may not be able to remove heat optimally from components positioned higher up in the battery module, and the use of a suitable thermal conductor to transfer heat to the cooling plate may be required.

[0014] An example of a prismatic battery cell is described in Italian Patent Application No. 102024000016132 filed by the present applicant. [Prior art documents] [Patent Documents]

[0015] [Patent Document 1] European Patent No. 3,475,996 [Overview of the Initiative] [Problems that the invention aims to solve]

[0016] The object of the present invention is to provide a prismatic battery cell, a corresponding battery pack, and a road vehicle that are at least partially liberated from the above-mentioned drawbacks and at the same time are simple and economical to manufacture.

Means for Solving the Problems

[0017] According to the present invention, there is provided a prismatic battery cell, a corresponding battery pack, and a road vehicle as claimed in any one of the independent claims appended hereto and, preferably, in any one of the dependent claims directly or indirectly dependent on the independent claims.

[0018] The appended claims illustrate preferred embodiments of the present invention and form an essential part of this description.

[0019] The present invention will now be described with reference to the accompanying drawings, which show some non-limiting embodiments thereof.

Brief Description of the Drawings

[0020] [Figure 1] It is a schematic plan view of a road vehicle including a battery pack according to an embodiment of the present invention, with details omitted for clarity. [Figure 2] Schematically shows the anode and cathode of a battery cell according to the present invention. [Figure 3] Shows a plan view and a side cross-sectional view of a cell portion formed starting from the anode and cathode of FIG. 2, with details omitted for clarity. [Figure 4] It is a schematic plan and side cross-sectional view of a cell including the portion of FIG. 3. [Figure 5] It is a schematic front view of the cell of FIG. 4. [Figure 6] It is a schematic perspective view of the cells of FIGS. 4 and 5.

Modes for Carrying Out the Invention

[0021] In Figure 1, reference numeral 1 generally indicates a road vehicle, which, as a whole, has two front wheels 2 and two rear wheels 3, and at least one pair (or all) of these receive torque from an electric or hybrid powertrain system 4. The powertrain system 4 may be solely electric (i.e., including only one or more electric motors) or hybrid (i.e., including an internal combustion engine and at least one electric motor).

[0022] In these diagrams, the same symbols and reference letters indicate the same element or component with the same function.

[0023] For the purposes of this invention, the term "second part" does not imply the existence of a "first part." In fact, these terms are used solely for clarity and should not be interpreted restrictively.

[0024] Elements and features included in different preferred embodiments, including those depicted in the drawings, can be combined with each other without exceeding the scope of protection of this patent application for that reason, as described below.

[0025] Hereafter, expressions such as "at the top," "at the bottom," "at the front," "at the back," and others similar thereto will be used to refer to the normal movement state of vehicle 1 along its normal direction of movement D.

[0026] As shown in the non-limiting embodiment of Figure 1, An essential longitudinal axis X of vehicle 1, which is horizontal and parallel to the normal direction of movement D of vehicle 1 when in use. Essential to vehicle 1, when in use, the horizontal axis Y is horizontal and perpendicular to axis X, and An essential element of vehicle 1 is the vertical axis Z, which is perpendicular to the axes X and Y during use. It is possible to define it further.

[0027] The powertrain system 4 preferably includes at least one electromechanical device, which is controlled by an AC / DC electronic power converter (i.e., an "inverter") (of a known kind, not shown herein), which is connected to a vehicle battery pack 5.

[0028] The battery pack includes a plurality of prismatic battery cells 6 as described herein.

[0029] The battery pack also includes a support structure 7 configured to support and house the battery cells 6 (see Figure 1). In detail, the support structure 7 is located beneath the vehicle occupant compartment 8.

[0030] Cell 6 is a prismatic cell as described above, and therefore includes a box-shaped metal case 9, inside which a stack of electrodes 10 is housed, preferably immersed in their respective electrolytes.

[0031] The box-shaped metal case 9, which is made of aluminum in particular, then includes a first foundation wall 11 and a second foundation wall 12 that face each other along the longitudinal axis L of the cell 6.

[0032] More specifically, the box-shaped metal case 9 also includes side walls 13 with four faces, which join the first base wall 11 to the second base wall 12, and together with these, define an internal space 14 inside the box-shaped metal case 9. In other words, the combination of walls 11, 12 and 13 defines the box-like / prismatic or parallelepiped shape of the box-shaped case 9.

[0033] Cell 6 further includes a first electrode 15, which includes a first metal connector 16 electrically connected to a first base wall 11.

[0034] In addition, cell 6 includes a second electrode 17, which includes a second metal connector 18 electrically connected to the second base wall 12.

[0035] Advantageously, though not limited, the first electrode 15 is the cathode of cell 6, while the second electrode 17 is the anode of cell 6.

[0036] Cell 6 further includes a stack 10, which is housed in the internal space 14 of a box-shaped metal case 9 and includes a number of electrode plates 19 (commonly called blanks, shown individually in Figure 2) that are spaced apart by foils 20 of separator material S (of known types, and therefore not further detailed below) to form a repeating electrode-separator-electrode-separator structure, as shown in Figures 3 and 4.

[0037] In detail, the electrode plates 19 alternately consist of anode plates 20 and cathode plates 21, which extend in the longitudinal direction along the longitudinal axis L and in the width direction along the transverse axis T perpendicular to the longitudinal axis L.

[0038] The electrode plate 19 includes a metal core (also known as a current collector) partially coated with an active material, typically in the form of a compacted powder, which is, for example, graphite in the case of the cathode, and lithium and cobalt in the case of the anode (at least as far as lithium-ion batteries are concerned). The electrode plate is typically entirely coated with the active material on both sides, except for a side band conventionally called the bare foil.

[0039] The anode plate 20 has a first metal terminal element 22 (a so-called tab) protruding along its longitudinal axis L toward the first base wall 11, and the first metal terminal element is electrically connected to the first base wall to form the first electrode 15.

[0040] Furthermore, the cathode plate 21 has a second metal terminal element 23 protruding from the second base wall 12 along its longitudinal L-axis in the opposite direction to the first metal terminal element 22. The second metal terminal element is electrically connected to the second base wall, forming a second electrode 17 having the opposite polarity to the first electrode 15.

[0041] The first metal terminal element 22 and the second metal terminal element 23 correspond to the aforementioned side band, i.e., the bare foil, or tabs obtained therefrom using laser or mechanical forming.

[0042] Advantageously, the second metal terminal element 23 extends across the entire width of the cathode plate 21. In this way, the need to form terminal tabs is avoided. In addition, by increasing the width through which the current exiting the cell 6 can flow, the electrical resistance of the battery cell 6 is reduced, resulting in improved, or reduced, relative heat generation. As a result, the complexity of the cell cooling system can also be reduced.

[0043] In particular, the first metal terminal element 22 has a width W1 that is smaller than the width W2 of the second metal terminal element 23 and the anode plate 20 from which they protrude.

[0044] Preferably, but not limited to, the length L1 of the first metal terminal element 22 is smaller than the length L2 of the second metal terminal element 23 in order to facilitate the respective electrical connections, i.e., (laser or ultrasonic) welding, to the second base wall 12. In fact, this increased length facilitates contact with the second base wall 12 and effectively eliminates the large intermediate connecting elements present in prior art cells.

[0045] According to the preferred but non-limiting embodiment shown in Figure 4, the second base wall 12 is electrically connected to the side wall 13, thus forming a second, positive, cup-shaped electrode 17. In contrast, at least a portion of the first base wall 11 is electrically insulated from the side wall 13. Thus, the first base wall 11, or at least a portion electrically insulated from the side wall 13, essentially acts as the first cathode 15 of the cell 6, while the combination of the side wall 13 and the second base wall 12 defines the second anode 17 of the prismatic cell 6.

[0046] In summary, the second electrode 17 defines the positive terminal of cell 6 (and therefore the second metal connector 18) and includes at least the second base wall 12 and side wall 13, and in particular, or part of the first base wall 11. On the other hand, the first electrode 15 defines the negative terminal (and therefore the first metal connector 16) and includes part of the first base wall 11 that is electrically insulated from the side wall 13.

[0047] Thus, despite the fact that poles 15 and 17 are on opposite sides of stack 10, it is possible to place both the first 16 and the second connector 18 on the same side of case 9. This structure is particularly advantageous when connecting cell 6 to the rest of the electrical system of road vehicle 1.

[0048] Preferably, but not limited to, the first base wall 11 and / or (particularly) the second base wall 12 are directly connected (i.e., without the interposition of intermediate connector elements) to the first metal terminal element 22 and / or the second metal terminal element 23, respectively. In this way, the dimensions, the amount of active material, and the weight of the cell 6 are optimized.

[0049] As shown in the non-limiting embodiment of Figure 5, the electrical connection between the first foundation wall 11 or, in particular, the second foundation wall 12 and the first metal terminal element 22 or the second metal terminal element 23, respectively, is made in the center of the first foundation wall 11 or the second foundation wall 12 and within the welding area WA, particularly rectangular in shape.

[0050] In some preferred non-limiting cases, the second foundation wall 12 and the second metal terminal element 23 are made of aluminum.

[0051] On the other hand, the first foundation wall 11 is preferably made of aluminum, while the first metal terminal element 22 is made of copper.

[0052] In some preferred cases, the battery cell 6 includes an exhaust system 24 configured to allow gas to escape from the inside to the outside of the box-shaped metal case 9 when the pressure inside the box-shaped metal case 9 exceeds a predetermined threshold.

[0053] In particular, as shown in the embodiment of Figure 5, the exhaust system 24 is located in the area of ​​the first foundation wall 11 and / or (preferably) the second foundation wall 12, and is configured to use the first foundation wall 11 and / or the second foundation wall 12 as valves.

[0054] To the advantage of this arrangement, though not limited, the exhaust system 24 is located in the area of ​​the positive terminal of cell 6, particularly surrounding the second foundation wall 12.

[0055] According to some non-limiting embodiments, the exhaust system 24, in particular the second foundation wall 12, External conductor element, Insulating element, A conductive plate in which an external conductive element, an insulating element, and the conductive plate are crimped together, Conductive rupture disc electrically connected and welded to a conductive plate, Includes.

[0056] In particular, the second electrical terminal element 23 is electrically connected to the conductive rupture disc.

[0057] In other words, the exhaust system can be designed similarly to that described in Patent Document 1, or to a known type of cell 4680, although cylindrical in shape.

[0058] In other non-limiting cases, the exhaust system 24 includes a specific weld on the second foundation wall 12, which is particularly provided to have a rectangular or concentric shape (especially on the outer surface).

[0059] Preferably, the welded joint is configured to define a preferred failure point of the second foundation wall 12, and to enable so-called exhaust operations in the area surrounding the second foundation wall 12.

[0060] In this way, the entire second base wall 12, i.e., the entire cover, is used as an exhaust valve. Furthermore, in this manner, the energy density of cell 6 can be maximized, and as much space as possible inside the box-shaped metal case 9 can be allocated to the active material.

[0061] In some preferred non-limiting cases, the system 24 includes at least one weak point of the second foundation wall 12, in particular a weld defining a line. In particular, the weld extends (inward) around the foundation wall 12.

[0062] Preferably, but not limited to, a predetermined pressure value for removing gas from inside case 9 is 6 bar or more, particularly 9 bar, preferably 12 bar, and more specifically 15 bar.

[0063] For example, the electrode plate 20 can be a rectangle with dimensions of 160 x 100 mm, while lengths L1 and L2 can be 12 mm and 18 mm, respectively.

[0064] Although the invention described above relates to a specific embodiment, its scope of protection should not be considered limited to that embodiment, as it also includes all variations, modifications, or abbreviations of these covered by the appended claims, such as different types of storage systems for materials, etc.

[0065] The embodiments described herein can be combined with one another without exceeding the scope of protection of the present invention for this reason.

[0066] The vehicles and methods described above offer many advantages.

[0067] First, cell resistance and, therefore, relative heat generation are reduced.

[0068] In addition, the cooling system can be simplified, and the management of the heat buildup inside the battery pack can be improved.

[0069] Finally, the energy and power intensity of the prismatic cell can be increased. [Explanation of symbols]

[0070] 1 vehicle 2 Front wheels 3 Rear wheels 4 Powertrain System 5 Battery Packs 6 battery cells 7 Support structure 8. Crew compartment 9 Box-shaped metal cases 10 stacks 11. First foundation wall 12. Second foundation wall 13 Side wall 14 Interior space 15 First electrode 16. First metal connector 17. Second electrode 18. Second metal connector 19 Electrode plate 20 anode plates 21 Cathode Plate 22 First terminal element 23 Second terminal element 24 Exhaust System X-axis Y-axis Z-axis L Long axis T horizontal axis L1 Length L2 Length W1 width W2 width WA welding area

Claims

1. A rectangular prism-shaped battery cell (6), A box-shaped metal case (9) including a first base wall (11) and a second base wall (12) facing each other along the longitudinal axis (L) of the cell, the box-shaped metal case (9) also includes a side wall (13) with four surfaces that connects the first base wall (11) to the second base wall (12) and together with these, defines an internal space (14) inside the box-shaped metal case (9), A first electrode (15) including a first metal connector (16) electrically connected to the first base wall (11), A second electrode (17) including a second metal connector (18) electrically connected to the second base wall (12), A stack (10) is arranged in the internal space (14) of the box-shaped metal case (9) and includes a plurality of electrode plates (19) that are alternately separated from one another by foil of separator material so as to form a repeating electrode-separator-electrode-separator structure, Includes, The electrode plates (19) alternately consist of anode plates (20) and cathode plates (21), each extending in the length direction along the longitudinal axis (L) and in the width direction along the transverse axis (T) perpendicular to the longitudinal axis (L). The anode plate (20) has first metal terminal elements (22) protruding along the longitudinal axis (L) toward the first base wall (11), and these are electrically connected to form the first electrode (15). The cathode plate (21) has a second metal terminal element (23) protruding toward the second base wall (12) along the longitudinal axis (L) in the direction opposite to the first metal terminal element (22), and these are electrically connected to each other, forming the second electrode (17) opposite to the first electrode (15). The battery cell (6) includes an exhaust system (24) configured to allow gas to escape from the inside to the outside of the box-shaped metal case (9) when the pressure inside the box-shaped metal case (9) exceeds a predetermined threshold, The exhaust system (24) is located on the first foundation wall (11) and / or the second foundation wall (12), and is configured to use the first foundation wall (11) and / or the second foundation wall (12) as valves. Rectangular prism-shaped battery cell (6).

2. The battery cell (6) according to claim 1, wherein the second electrode (17) defines the positive terminal of the cell, and the exhaust system (24) is located at the positive terminal of the cell and in particular surrounds the second base wall (12).

3. The battery cell (6) according to claim 1, wherein the second metal terminal element (23) extends across the entire width of the cathode plate (21).

4. The battery cell (6) according to claim 1, wherein the first metal terminal element (22) has a width (W1) less than the width (W2) of the second metal terminal element (23) and the anode plate (20) from which they protrude.

5. The battery cell (6) according to claim 1, wherein the length (L1) of the first metal terminal element (22) is less than the length (L2) of the second metal terminal element (23).

6. The battery cell (6) according to any one of claims 1 to 5, wherein the second base wall (12) is electrically connected to the side wall (13), while at least a portion of the first base wall (11) is electrically insulated from the side wall (13).

7. The battery cell (6) according to claim 6, wherein the second electrode (17) defines the positive terminal of the cell and includes at least the second base wall (12) and the side wall (13), and in particular a portion of the first base wall (11).

8. The battery cell (6) according to claim 7, wherein the first electrode (15) defines a negative terminal and includes a portion of the first base wall (11) that is electrically insulated from the side wall (13).

9. The battery cell (6) according to any one of claims 1 to 8, wherein the first base wall (11) and / or the second base wall (12) are directly connected to the first metal terminal element (22) and / or the second metal terminal element (23), respectively.

10. The battery cell (6) according to any one of claims 1 to 9, wherein the electrical connection between the first base wall (11) or the second base wall (12) and the first metal terminal element (22) or the second metal terminal element (23), respectively, is made in a particularly rectangular welding area located in the center and inside of the first base wall (11) or the second base wall (12).

11. The battery cell (6) according to any one of claims 1 to 8, wherein the second base wall (12) and the second metal terminal element (23) are made of aluminum.

12. Four wheels (2, 3) in which at least one pair of wheels (2, 3) are driven, Electric or hybrid powertrain system (4) A battery pack (5) comprising a plurality of battery cells (6) as described in claim 1, Includes, The battery pack (5) includes a support structure (7) that supports and houses the battery cells located below the vehicle occupant compartment (8). Road vehicles (1).

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