Battery pack for electric-powered road vehicle and electric-powered road vehicle equipped with such battery pack

Abstract

To provide a battery pack in which corrosion caused by poor connection between a spring element and a battery cell is suppressed.SOLUTION: A battery pack for an electric-powered road vehicle includes a plurality of planar electrochemical cells arranged in a pack pattern. Each cell includes terminal electrodes at a first edge, a support facing the terminal electrodes of the cells and a plurality of elastically deformable spring-conducting elements having first ends coupled to the support. The spring-conducting elements are arranged in rows so that, when the battery pack is in use, each row of the spring-conducting elements is pressed against the terminal electrodes of a corresponding cell to form a conductive bridge between each cell and the support. The terminal electrodes of each cell are connected to one another by a longitudinal welding line parallel to the first edge of the corresponding cell, and, for each cell, a conductive plane is provided between the terminal electrodes and the corresponding row of spring-conducting elements. Each conductive plane is constrained to the corresponding terminal electrodes by means of points or transverse welding lines at a space provided between two adjacent spring-conducting elements in the same row.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] <CROSS REFERENCE TO RELATED APPLICATIONS> This patent application claims priority to Italian Patent Application No. 102023000014934, filed on July 17, 2023, the entire disclosure of which is incorporated herein by reference.

[0002] The technical field of the invention is that of electric road vehicles. Such indications include both road vehicles powered exclusively electrically and road vehicles powered both electrically and endothermically. More specifically, the invention relates to a battery pack, i.e. a battery pack installed on board the road vehicles mentioned above and configured to store the electrical energy supplied during electric propulsion. Against this background, the invention addresses the problem of how to improve the voltage monitoring of the individual cells constituting the battery pack. Finally, the invention also relates to a road vehicle equipped with the aforementioned battery pack. [Background technology]

[0003] In the automotive industry, and in particular for electric road vehicles, it is known to utilize lithium batteries to store the electrical energy supplied during electric propulsion. In fact, such lithium batteries offer a high energy density that is ideal for incorporating electrical power in the automotive industry. At present, in fact, lithium polymers are, from a chemical point of view, the state of the art in the manufacture of high-capacity batteries. In such batteries, a series and parallel interconnection of various cells (typically 3.7 V each) is provided in order to reach the desired total voltage and energy density of the battery pack. Battery modules that are usually available commercially (for automobiles, but also for household appliances) often include flat, pouch-type batteries with a very limited thickness relative to the other dimensions. Two very wide opposing faces (through which the heat is dissipated almost integrally) and four thin, elongated sides are distinguished, with the positive and negative terminals of the cells being located on one side or on two opposing sides. In particular, an energy storage system for electric road vehicles is known, which comprises a battery pack in which several battery modules are electrically connected to each other. Each battery module further comprises a support structure holding a number of electrochemical cells electrically connected together in series and parallel. In known manner, electrical connectors for connecting the battery pack to the vehicle's propulsion system are also provided, as well as a control unit (commonly referred to as a Battery Management System (BMS)) that interacts with all the battery modules to control and manage each cell or set of electrochemical cells in each battery module.

[0004] As is known, in such a structure, each electrochemical cell has an anode at one end and a cathode at the opposite end (or the same end), and a control unit (i.e., BMS) is connected to each electrode of the electrochemical cell in order to control the voltage value of each electrochemical cell. Generally, the connection of the electrodes of a single electrochemical cell to the control unit is performed by multiple electric cables extending inside the storage system. The presence of the multiple electric cables complicates the structure and assembly of the electric energy storage system, which is accompanied by an increase in the volume, volume, and weight of the electric energy storage system. In addition, there is a risk of compromising the safety of the electric energy storage system, especially since there may be a large voltage difference of several hundred volts between the cable connecting the first electrochemical cell of the battery pack and the cable connecting the last electrochemical cell of the battery pack.

[0005] EP 4092795, by the same applicant of the present invention, describes an alternative solution to the above-mentioned electric cables for monitoring the voltage of the electrochemical cells of a battery pack. Briefly, in the solution described in EP 4092795, it is realized to equip the battery with a control unit, which directly faces the cell and is protected on the other side by a specially provided casing, in which the sensor elements for sensing the cell voltage comprise a number of elastically deformable conductors, in fact a kind of spring elements, which are fixed on one side directly to the control unit and on the other side are elastically compressed against the electrodes of the cell in use. The structure of the battery pack described in EP 4092795 is obviously the starting point for what can be improved by the present invention, so that reference is made for further details. In particular, such an improvement concerns the contact points between the described spring elements and the electrodes of the cells, as will become evident, since, as assumed, the measurement of the cell voltage and therefore the operation of the battery pack controlled by the control unit is strictly related to the "contact" between the tabs and the ends of the springs. Currently, the free ends of the springs contact the cells at welds, which are provided to connect the electrodes to each other and through which the battery power flows. In this sense, such welds cannot be eliminated or reduced at will, since the performance of the entire battery module depends on them. Such known contacts between the springs and the cells have several drawbacks. In fact, the welds can be poor current conductors and can also cause the presence of impurities and roughness in the contact area, which can lead to a loss of contact or can damage the coating of the springs, which can cause undesirable corrosion mechanisms.

[0006] Starting from such prior art, there is therefore an ongoing need to improve the contact area between the above-mentioned springs measuring the voltage and the electrodes of the cell in order to overcome the above-mentioned drawbacks. Summary of the Invention

[0007] It is therefore an object of the present invention to provide a battery pack for an electric road vehicle that can solve the above-mentioned problems. The present invention extends to the battery pack itself as well as to an electric road vehicle equipped with such a battery pack.

[0008] The starting point of the invention is a battery pack, which includes: - a plurality of electrochemical cells, preferably in lithium-ion technology, each cell being planar and arranged side by side in a pack to form at least one module. As is known, each cell comprises two terminal electrodes, which according to the invention are returned to a first edge of the cell, so that they can be easily connected to each other by a longitudinal weld line along the edge (preferably a weld line with some interruptions, as is clear, to form a kind of discontinuous weld line). As is known, the length of the longitudinal weld must meet the design specifications (the power of the battery flowing through the weld), and therefore the aforementioned interruptions cannot be shortened at will, since they are only a small part of the length of the cell edge. a support (preferably in the form of a planar substrate, made of a non-conductive material) placed within the battery so as to have a separate face facing the terminal electrode of the cell. - a plurality of spring conductive elements, i.e. elastically deformable conductive elements, with a first end coupled to the support and a second end intended to come into contact with an electrode (with an mediated contact, as will become clear) so as to be able to measure the voltage of the cell or to supply a current to some external device. In particular, the spring conductive elements are arranged in parallel rows in such a position that, during use of the battery pack, each row of spring conductive elements is pressed against a terminal electrode along the edge of the corresponding cell. In this way, a conductive bridge is formed between each cell and the support in order to measure the voltage.

[0009] Such structures are known and are described, for example, in EP 4092795 by the same applicant, so that a person skilled in the art does not need further details to understand the above elements.

[0010] Starting from such known structures, the invention proposes to provide each cell with a further element, i.e. a conductive surface, covering the terminal electrode (interposed between the electrode and the corresponding row of spring conductive elements). Each conductive surface is bound to the corresponding terminal electrode by a spot or a transverse weld line only at a specific position. Such a weld point is in particular in a separation space provided between two adjacent spring conductive elements of the same row, so that during use of the battery, when the spring conductive element is pressed against the conductive surface, the free ends of the springs come into contact with the conductive surface in areas where no weld point or weld line is provided.

[0011] Since the design feature (passing the battery power) is dependent on the longitudinal welds located under the conductive surface, i.e. on the opposite side to the spring, the length of these welds must be limited. The fact that the spring is in contact with the surface areas where no welds are provided makes it possible to overcome the drawbacks mentioned with reference to the prior art. Moreover, this conductive surface is thin and therefore does not take up an unnecessarily large volume.

[0012] Preferably, as mentioned above, each longitudinal weld line connecting the corresponding terminal electrodes is a discontinuous line along the entire edge of the cell, but of the "broken line" type, i.e. with interruptions or weld gaps. The interruptions of the longitudinal weld lines are not irregular, but are precisely at the connection points or transverse connecting weld lines made on the new conductive surface. In this way, these points or transverse weld lines do not overlap the longitudinal weld lines.

[0013] Preferably, the terminal electrodes are made in the form of conductive plates overlapping substantially along the entire first edge of each cell.

[0014] Preferably, the battery pack further comprises: - A box-shaped support structure having a back wall, two side walls, and an opening opposite the back wall through which the terminal electrodes of the cells can be accessed. a cover connected to the support structure at the opening, in which case the support supporting the spring element takes the form of a substrate connected to the cover and facing the cell. - at least one voltage sensing device of the cells, supported by the support and connected to the spring element, for monitoring the voltage of each cell.

[0015] As is evident, the innovative element provided by the invention is a conductive surface covering the electrodes and the longitudinal welds joining them. To allow safe handling and installation in the battery, each conductive surface is coupled to a control body made of non-conductive material. Each control body, preferably made of non-conductive material, comprises a bridge part parallel to the corresponding conductive surface as well as two sides configured to couple with corresponding elements of the battery pack and ensure the correct positioning of the new conductive surface.

[0016] Preferably, the new conductive surface, the spring conductive element and the terminal electrode are made of the same conductive material.

[0017] Finally, the invention also extends to any electric road vehicle equipped with a battery pack as claimed, preferably arranged transversely to the longitudinal direction of the vehicle and mounted on a frame at the rear of the passenger compartment. [Brief description of the drawings]

[0018] The present invention will now be described with reference to the accompanying drawings, which show some non-limiting exemplary embodiments thereof. [Figure 1] 1 is a schematic perspective view of an electric vehicle that can be equipped with a battery pack according to the present invention. [Diagram 2] 1 is a schematic perspective view of a battery pack for an electric vehicle that can be improved in accordance with the present invention; [Diagram 3]FIG. 3 is an exploded view of the battery pack of FIG. 2. [Figure 4] FIG. 4 is an enlarged view of a detail of a module of the battery pack of FIG. 3. [Diagram 5] Fig. 5 shows an enlarged view of a detail of the battery pack of Fig. 3, in which there is a spring element for measuring the cell voltage, connecting the electrodes of the cells to a control unit. In such a view, the prior art coupling between the spring and the electrodes of the cells of the battery pack is diagrammed. [Figure 6] Fig. 6 shows an enlarged view of a detail of the battery pack of Fig. 3, in which there is a spring element for measuring the voltage of the cell, connecting the electrodes of the cell to a control unit. In such a view, the first step of forming a bond according to the invention between the spring and the electrodes of the cells of the battery pack is diagrammed. [Figure 7] Figure 7 shows an enlarged view of a detail of the battery pack of Figure 3, in which there is a spring element for measuring the voltage of the cell, connecting the electrodes of the cell to the control unit. In such a view, the second step of forming the bond according to the invention between the spring and the electrodes of the cells of the battery pack is diagrammed. [Figure 8] FIG. 8 shows an enlarged view of further components introduced into the battery pack to form bonds according to the present invention between the springs and the electrodes of the cells of the battery pack. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Preferred Embodiments of the Invention With reference to Figure 1, the number 1 generally indicates a road vehicle comprising two front wheels W and two rear wheels W. The road vehicle 1 is an at least partly electrically driven vehicle and comprises a frame 2. The road vehicle 1 comprises a battery pack 3, which in this embodiment is supported by the frame 2 in an engine compartment 4. As can be seen, preferably the battery pack is located at the rear of the passenger compartment 5, for example in the floor of the vehicle, behind the seats accommodated inside the passenger compartment 5.

[0020] FIG. 2 shows an embodiment of a battery pack 3 that can be improved according to the present invention. In this embodiment, the battery pack 3 has a substantially elongated rectangular parallelepiped shape and can be arranged transversely with respect to the longitudinal axis of the vehicle. In particular, the battery pack 3 is suitable for being connected to an electric propulsion system (not shown) of the vehicle 1 and is adapted to store electric energy generated by an electric machine (not shown) or discharged by another source. As shown in FIGS. 2 and 3, the battery pack 3 comprises at least one part 6 configured to accommodate a battery control and monitoring system 8 (usually called Battery Management System (BMS)) adapted to control the operating parameters of the battery. As is known, the battery comprises a number of cells, the ends of such cells C being connected to terminals T in the part 6. Two connectors CN protrude from the control system 8 and are configured to conduct electric current from and towards the control system 8. The battery pack 3 further comprises a part 7 configured to accommodate electrochemical cells C (i.e. the active material of the battery pack 3). For example, as shown in FIG. 3, the vehicle battery pack 3 comprises a support structure 15, which further comprises at least two elongated peripheral elements 16 and 18 facing each other. The peripheral elements define a box-like portion BP between them. The battery pack 3 further comprises one or more partitions 17 arranged to divide the box-like portion BP, which defines at least two housings. The partitions 17 are arranged transversely with respect to the two peripheral elements 16 and 18 facing each other. In other words, the peripheral elements 16 and 18 define two parallel planes in which the partitions 17 extend transversely (perpendicularly). In the non-limiting embodiment of FIG. 3, the partitions 17 define three different housings inside the box-like portion BP. The electrochemical cells C are planar, electrically connected to each other and to both the partitions 17, parallel and divided into three modules 12 in this example. As can be seen in FIG. 4, in this embodiment, each module 12 includes at least two insert plates 32 .They are arranged at the end of each module 12, parallel to the partitions 17, and are arranged to facilitate the insertion of each module 12 by being compressed in the corresponding housing, so that it remains compressed after insertion. In this way, the module 12 of the cell C is compressed outside the housing and inserted in a compressed state. By doing so, the cell C remains compressed between the two partitions 17 that define the corresponding housing. In this embodiment, each insertion plate 32 comprises a guide element 34, which is arranged to guide the module 12 during insertion into the corresponding housing. As can be seen in the embodiment of FIG. 4, the battery pack 3 comprises a number of heat dissipation elements 20. As is known and as can be seen in the embodiment of FIG. 4, each cell C comprises a pair of terminal electrodes TT', TT" (positive and negative electrodes, i.e. cathode and anode) extending from the same side of the cell C. The electrodes TT', TT" are supported by a support 27, made of a plastic material. To prevent two adjacent cells from coming into contact, the support 27 comprises a separator 29. In particular, the connection of the terminal electrodes TT′, TT″ is effected at one or more connection planes 31.

[0021] Returning to Fig. 2, the battery pack 3 includes at least one cooling panel 11. The cooling panel 11 is arranged on at least one side and configured to be fixed to the support structure 15 by fixing elements 10, 10' to dissipate heat transferred by the heat dissipation element 20. The battery pack 3 includes an upper opening that is sealed by a cover element 9.

[0022] FIG. 5 shows an enlarged cross-sectional view of a detail of the battery pack of FIG. 3. Such a view shows the presence of a control unit 13 comprising a substrate 37 restrained on the cover 9, facing the connection plane 31 of the terminal electrodes TT', TT" of the cells. The substrate 37 supports a number of elements 14 configured to control the operating parameters (voltage, temperature, etc.) of the electrochemical cells C of the module 12. In FIG. 5, reference number 39 denotes a spring-type, elastically deformable conductive contact element for sensing the cell voltage. Such a spring element 39 is configured to be elastically compressed, in use, between the planar support substrate 37 and the plane 31 of the terminal electrodes TT', TT". For this purpose, a number of springs 39 are provided, arranged in a single row, such that there is one or more springs 39 in the plane 31 of the terminal electrode TT', TT" of each electrochemical cell C. The prior art connection between the springs 39 and the plane 31 of the electrodes of the cells of the battery pack is diagrammed in FIG. 5. In particular, the connection between the overlapping terminal electrodes TT', TT" is made by a continuous weld line 40 that extends substantially along the entire length of the plane 31 and the edge of the underlying cell. At the weld line 40, therefore, contact between the springs 39 and the plane 31 occurs, which entails a series of disadvantages (mentioned above).

[0023] FIG. 6 shows an enlarged view of a detail of the battery pack of FIG. 3, in which the aforementioned spring element 39 is present for measuring the cell voltage. In such a view, a first step of the inventive connection between the spring 39 and the electrode of the cell of the battery pack is diagrammed in order to optimize the contact area of ​​the spring 39. As can be seen in FIG. 6, a weld is also made along the edge of the cell to form a connection between the overlapping terminal electrodes TT', TT". However, in this case, in an innovative manner, the longitudinal weld line 41 is not continuous, but is made in the form of a series of welds alternating with non-welded sections. In particular, these non-welded sections are located in the spaces provided between two adjacent springs 39 of the same row. The reference number 42 indicates the section where the longitudinal weld line 41 is not provided.

[0024] FIG. 7 shows an enlarged view of a detail of the battery pack of FIG. 6, in which the second step of the bonding according to the invention between the spring and the electrode of the cell of the battery pack is diagrammed. As can be seen in such a figure, the invention provides for the presence of a conductive surface 43, which covers the longitudinal weld line 41 and forms an intermediate layer between the spring 39 and the underlying joining surface 31, which joins the electrode. The connection between such conductive surface 43 and the plane 31 is obtained by a weld or transverse weld line 44, which is made in the part 42 where the longitudinal weld line 41 was not previously provided. The transverse weld line 44 is thus located in the space between two adjacent springs 39 of the row, in this way, when the springs 39 are pressed towards the cell C, they come into contact with the surface area without welding, i.e. the part of the conductive surface 43 between the transverse weld lines 44. With this solution, the desired result is achieved, since impurities and roughness resulting from welding are thus not present in the contact area, thus reducing the risk of losing contact or of damaging the coating of the spring.

[0025] Finally, FIG. 8 shows how the conductive surface 43 is supported by a handling structure 45 made of a non-conductive material, in this case in the form of a bridge, to enable the operator to safely and accurately position the conductive surface 43 on the electrode of the cell.

Claims

1. A battery pack (3) for an electric road vehicle (1), comprising: - a plurality of planar electrochemical cells (C) arranged side by side in a pack, each cell (C) being provided with a terminal electrode (TT', TT") at a first edge thereof; a support (37) facing the terminal electrodes (TT', TT") of the cell (C); a plurality of elastically deformable spring conductive elements (39) having a first end coupled to the support (37), the plurality of elastically deformable spring conductive elements (39) being arranged in rows such that, when the battery pack (3) is in use, each row of the spring conductive elements (39) presses against the terminal electrodes (TT', TT") of a corresponding cell (C) to form a conductive bridge between each cell (C) and the support (37); the terminal electrodes (TT', TT") of the respective cells (C) are connected to each other by longitudinal weld lines (41) parallel to the first edges of the corresponding cells (C); a battery pack (3) characterized in that for each of the cells (C), a conductive surface (43) is provided between the terminal electrode (TT', TT") and a corresponding row of the spring conductive elements (39), each of the conductive surfaces (43) being constrained to the corresponding terminal electrode (TT', TT") by a point or a transverse weld line (44) in a space provided between two adjacent spring conductive elements (39) of the same row, whereby, during use of the battery, the spring conductive elements (39) are pressed against a portion of the conductive surface (43) where no weld point or weld line is provided.

2. 2. The battery pack according to claim 1, wherein for each of the cells (C), a joining surface (31) for joining the terminal electrodes (TT', TT") is provided, and the longitudinal welds (41) connecting the terminal electrodes (TT', TT") of each of the cells (C) are made on the corresponding joining surface (31) below the conductive surface (43).

3. 3. The battery pack according to claim 1, wherein each of the longitudinal weld lines (41) connecting the corresponding terminal electrodes (TT', TT") is a discontinuous line, and the points or the transverse weld lines (44) connecting the conductive surfaces (43) to the terminal electrodes (TT', TT") are located in the gaps of the discontinuous longitudinal weld lines (41) so as not to overlap the longitudinal weld lines (41).

4. 4. The battery pack according to claim 1, wherein the terminal electrodes (TT', TT") are made in the form of conductive plates along substantially the entire first edge of each of the cells.

5. The battery pack, a box-shaped support structure (15) having a rear wall and two side walls, and an opening opposite said rear wall through which the terminal electrodes (TT', TT") of said cells (C) can be accessed; a cover (9) connected to the support structure (15) at the opening, to which is connected a support (37) supporting the spring element (39), the support (37) being in the form of a substrate facing the cell (C); The battery pack according to any one of claims 1 to 4, further comprising at least one voltage sensing device (14) of said cell (C) supported by said support (37) and connected to said spring element (39) for monitoring the voltage of each of said cells (C).

6. 6. The battery pack according to claim 1, wherein each of the conductive surfaces (43) is coupled to an operating body (45) made of a non-conductive material.

7. 7. The battery pack of claim 6, wherein the operating body (45) of a non-conductive material has a bridge portion parallel to the corresponding conductive surface (43) as well as two sides configured to couple to corresponding elements of the battery pack (3).

8. 8. The battery pack according to claim 1, wherein the conductive surface (43), the spring conductive element (39) and the terminal electrodes (TT', TT") are made of the same conductive material.

9. An electric road vehicle (1) comprising a battery pack (3) according to any one of claims 1 to 8.

10. 10. The vehicle according to claim 9, wherein the battery pack (3) is arranged transversely to the longitudinal direction of the vehicle (1) and is mounted on a frame (2) at the rear of the passenger compartment (5).

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