Battery pack for electric road vehicle and electric road vehicle equipped therewith

Abstract

A battery pack for an electric road vehicle includes: a plurality of planar electrochemical cells arranged in a battery pack pattern; wherein each cell includes a terminal electrode at a first edge; a support facing a terminal electrode of the battery; a plurality of elastically deformable spring conductive elements having a first end coupled to the support, where the spring conductive elements are arranged in rows such that when the battery pack is in use, each row of spring conductive elements presses against a terminal electrode of a respective cell to form a conductive bridge between each cell and the support; wherein the terminal electrodes of each cell are connected to each other by a longitudinal weld line parallel to the first edge of the respective cell; wherein, for each cell, a conductive plane is provided between the terminal electrode and a corresponding row of spring conductive elements; wherein each conductive plane is constrained to a respective end electrode by a point or a lateral weld line at a space between two adjacent spring conductive elements of the same row.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent application claims the priority of Italian patent application No. 102023000014934, filed on July 17, 2023, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] The technical field of the invention relates to the field of electric road vehicles. This indication includes road vehicles driven purely by electricity and road vehicles driven by a combination of electricity and an internal combustion engine. More specifically, the invention relates to a battery pack, i.e. a battery pack installed in the aforementioned road vehicle and configured to store electrical energy supplied during electric driving. In this context, the invention will solve 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 comprising the aforementioned battery pack. Background Art

[0004] In the automotive industry, and in particular with regard to electric road vehicles, it is known to utilize lithium batteries to store the electrical energy supplied during electric driving. In fact, such lithium batteries offer a high energy density and are very suitable for the realization of electrical energy in the automotive industry. In fact, from a chemical point of view, lithium polymers currently represent the state of the art in the production of high-capacity batteries. In such batteries, a series and parallel interconnection of a plurality of cells (usually 3.7 V each) is provided to achieve the total voltage and energy density required for the battery pack. Commercially available battery modules (not only automotive battery modules, but also battery modules for consumer electronics) generally include planar pouch cells, which have a very limited thickness relative to the other dimensions. It can be seen that they have two very wide opposite faces (through which the heat is almost completely dissipated) and four thin and elongated side faces, wherein the positive and negative terminals of the battery are arranged on one side or on two opposite sides. In particular, a known electrical energy storage system for electric road vehicles comprises a battery pack consisting of a plurality of battery modules electrically connected to each other. Each battery module in turn comprises: a support structure, which carries a plurality of electrochemical cells electrically connected to each other in a series and parallel manner. In a known manner, electrical connectors are also provided for connecting the battery pack to the vehicle's propulsion system and to a control unit (commonly referred to as BMS, Battery Management System) which interacts with all the battery modules in order to control and manage each cell or electrochemical battery pack of each battery module.

[0005] As is well known, in this structure, each electrochemical cell has a positive electrode at one end and a negative electrode at the opposite end (or the same end), and has a control unit (i.e., BMS) connected to each electrode of the electrochemical cell to control the voltage value of each electrochemical cell. Typically, the connection between the electrodes of a single electrochemical cell and the control unit is achieved through a plurality of cables extending inside the storage system. The presence of these multiple cables complicates the structure and assembly of the electric energy storage system, including: an increase in the capacity, volume, and weight of the electric energy storage system, and the risk of endangering the safety of the electric energy storage system, especially because there may be a significant voltage difference of the order of several hundred volts between the cable connecting the starting electrochemical cell of the battery pack and the cable connecting the last electrochemical cell of the battery pack.

[0006] EP4092795, proposed by the same applicant as the present invention, describes an alternative solution to the aforementioned cables for monitoring the voltage of an electrochemical cell of a battery. In short, the solution described in EP4092795 provides: a solution for equipping the battery with a control unit, which directly faces the battery and is protected on the other side by a specially provided housing, inside which a sensor element for sensing the battery voltage comprises a plurality of elastically deformable conductors, in fact a type of spring element, which is directly fixed to the control unit on one side and elastically compressed against the electrodes of the battery on the other side in use. For further details, reference is obviously made to EP4092795, since the structure of the battery described therein represents a starting point that can be improved thanks to the present invention. In particular, as will become clear, this improvement concerns the contact point between the spring element and the electrode of the battery, since it can be inferred that the measurement of the battery voltage and the operation of the battery thus controlled by the control unit are strictly linked to the "contact" between the lug and the end of the spring. At present, the free end of the spring contacts the battery at the welding point, which serves to connect the electrodes to each other and through which the electrical energy of the battery is transmitted. In this sense, these welds cannot be removed nor reduced at will, since the performance of the entire battery module depends on them. This known contact between the spring and the battery has some disadvantages. In fact, the welds can be poor conductors of current and can also generate impurities and roughness in the contact area, which can lead to poor contact or can destroy the covering of the spring, thus initiating undesirable corrosion mechanisms.

[0007] Therefore, based on this prior art, there is a need to improve the contact area between the spring for measuring voltage and the battery electrode to overcome the above disadvantages. Summary of the invention

[0008] It is therefore an object of the present invention to provide a battery pack for an electric road vehicle which overcomes the above-mentioned disadvantages. In addition to the battery pack itself, the present invention also comprises an electric road vehicle equipped with the battery pack.

[0009] The starting point of the present invention is a battery pack comprising:

[0010] - a plurality of electrochemical cells, preferably in lithium-ion technology, wherein the cells are planar and arranged side by side in the mode of a battery pack, forming at least one module; each cell comprises two terminal electrodes which, according to the invention, are brought back 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 (obviously, the weld line preferably has some interruptions, forming a kind of dotted weld line). As is known, the length of the longitudinal weld cannot be reduced at will, since it must meet the design specifications (the power of the cell passes through the weld), so the above-mentioned interruptions are only a few small sections of the length of the edge of the cell;

[0011] a support (preferably made of a non-conductive material, in the form of a planar substrate) mounted in the cell so as to have a single face facing the terminal electrodes of the cell;

[0012] - a plurality of spring conductive elements, i.e. elastically deformable conductive elements, whose first end is connected to the support and whose second end is intended to make contact (more precisely, indirectly) with the electrode, making it possible to measure the voltage of the battery or to power some external device. In particular, the spring conductive elements are arranged in rows positioned parallel to each other so that, when the battery pack is in use, the spring conductive elements of each row are pressed against the terminal electrode along the edge of the corresponding battery. In this way, a conductive bridge for measuring the voltage is formed between each battery and the support.

[0013] Such structures are known, for example as described in EP4092795 by the same applicant, so that a person skilled in the art does not need further details to understand the elements listed above.

[0014] Starting from this known structure, the invention proposes to provide each battery with another element, namely a conductive plane, which covers the terminal electrode (between the electrode and the respective row of spring-conducting elements), wherein each conductive plane is constrained to the respective terminal electrode only at certain locations by points or transverse welding lines. Such welding points are in particular at the separation spaces between two adjacent spring-conducting elements of the same row, so that when the battery is in use and the spring-conducting elements are pressed against the conductive plane, the free ends of the springs are in contact with the conductive plane in areas where no welding points or lines are provided.

[0015] The length of these welds is limited, since the design feature (transmission of the battery's power) is entrusted to the longitudinal weld line located below the conductive plane (i.e. on the opposite side relative to the spring). The fact that the spring is in contact with the non-welded surface area allows the drawbacks mentioned in the prior art to be overcome. In addition, the conductive plane is thin and therefore does not occupy much volume.

[0016] Preferably, as already mentioned above, each longitudinal welding line connecting the respective terminal electrodes is a non-continuous line along the entire edge of the battery, but it is of the "dotted line" type, i.e. with discontinuous points or welding gaps. The interruption points of the longitudinal welding lines are not random, but exactly at the connection points or transverse connecting welding lines formed on the new conductive plane. In this way, the points or transverse welding lines do not overlap with the longitudinal welding lines.

[0017] Preferably, the terminal electrodes are in the form of conducting plates overlapping along substantially the entire first edge of each cell.

[0018] Preferably, the battery pack further comprises:

[0019] - a box-like supporting structure having a rear wall and two side walls and an opening opposite the rear wall, from which the terminal electrodes of the battery are accessible;

[0020] a cover connected to the support structure at the opening; in this case, the support supporting the spring element is formed as a base coupled to the cover and facing the battery;

[0021] - At least one voltage sensing device of the battery, supported by the support and connected to the spring element, for monitoring the voltage of each battery.

[0022] Obviously, the innovative elements provided by the present invention are the conductive planes covering the electrodes and the longitudinal welding lines connecting the electrodes. In order to achieve safe operability and installation in the battery, each conductive plane is coupled to an operating body made of non-conductive material. Preferably, each operating body made of non-conductive material comprises a bridging portion parallel to the corresponding conductive plane and two side portions, which are configured to couple to the corresponding elements of the battery pack and ensure the correct positioning of the new conductive plane.

[0023] Preferably, the new conductive plane, the spring conductive element, and the terminal electrode are made of the same conductive material.

[0024] Finally, the invention also extends to every electric road vehicle fitted with a battery pack which is the subject of the appended claims.Preferably, the battery pack is arranged transversely to the longitudinal direction of the vehicle and is mounted on a frame at the rear of the passenger compartment. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The invention will now be described with reference to the accompanying drawings, which show some non-limiting example embodiments of the invention, in which:

[0026] Figure 1 is a schematic perspective view of an electric vehicle that may be equipped with a battery pack according to the present invention;

[0027] Figure 2 is a schematic perspective view of a battery pack for an electric vehicle, which battery pack may be improved according to the present invention;

[0028] Figure 3 yes Figure 2 An exploded view of the battery pack;

[0029] Figure 4 yes Figure 3 A magnified view of the module details of the battery pack;

[0030] Figure 5 Shows Figure 3 An enlarged view of a detail of a battery pack in which there is a spring element for measuring the voltage of the battery, which spring element connects the electrodes of the battery to the control unit; in this figure, the connection between the spring and the electrodes of the battery pack according to the prior art is schematically shown;

[0031] Figure 6 Shows Figure 3 1. an enlarged view of a detail of a battery pack in which a spring element for measuring the voltage of the battery is present, which spring element connects the electrodes of the battery to the control unit; in this figure, a first step of making a connection between the spring and the electrodes of the battery pack according to the invention is schematically shown;

[0032] Figure 7 Shows Figure 3 an enlarged view of a detail of a battery pack in which there is a spring element for measuring the voltage of the battery, which connects the electrodes of the battery to the control unit; in this figure, a second step of making a connection between the spring and the electrodes of the battery pack according to the invention is schematically shown;

[0033] Figure 8 An enlarged view of an additional component is shown which has been introduced into a battery for making a connection according to the invention between a spring and an electrode of a cell of the battery. DETAILED DESCRIPTION

[0034] Reference Figure 1, reference numeral 1, as a whole, indicates a road vehicle provided with two front wheels W and two rear wheels W. The road vehicle 1 is a vehicle driven at least partially by electricity and provided with a frame 2. The road vehicle 1 comprises a battery pack 3, which in this example is supported by the frame 2 in an engine compartment 4. As shown, the battery pack is preferably arranged in the rear part of a passenger compartment 5, for example on the vehicle floor, behind the seats contained in the passenger compartment 5.

[0035] Figure 2 An example of a battery pack 3 is shown, which can be modified according to the invention. In this example, the battery pack 3 has a substantially elongated parallelepiped shape and can be arranged transversely to the longitudinal axis of the vehicle. In particular, the battery pack 3 is suitable for connection to an electric propulsion system (not shown) of the vehicle 1 and is suitable for storing electrical energy generated by an electric motor (not shown) or released by other sources. Figure 2 and Figure 3 As shown, the battery pack 3 includes at least one portion 6, which is configured to accommodate a battery control and monitoring system 8 (commonly referred to as BMS, i.e., "battery management system"), which is suitable for controlling the operating parameters of the battery. As is known, the battery pack includes a plurality of batteries, and the ends of these batteries C are connected to terminals T at portion 6. Two connectors CN extend from the control and monitoring system 8, and the connectors CN are configured to conduct current from and to the control system 8. The battery pack 3 also includes a portion 7, which is configured to accommodate electrochemical cells C, i.e., the active material of the battery pack 3. For example, as Figure 3 As shown, the vehicle battery pack 3 includes a support structure 15, which in turn includes at least two elongated peripheral elements 16 and 18 facing each other, defining a box-like portion BP (BP) therebetween. The battery pack 3 also includes one or more partitions 17, which are arranged to separate the box-like portion BP defining at least two accommodating compartments, wherein the partition 17 is arranged transversely to the two peripheral elements 16 and 18 facing each other. In other words, the peripheral elements 16 and 18 define two parallel planes, and the partition 17 extends transversely (vertically) between the two planes. Figure 3 In a non-limiting embodiment, the separator 17 defines three different accommodation compartments within the box-shaped portion BP. The electrochemical cells C are planar, electrically connected and parallel to each other and to the separator 17, and are divided into three modules 12 in this example. Figure 4As shown, in this example, each of the modules 12 includes at least two insertion plates 32, which are arranged at the end of each module 12, parallel to the partitions 17, and are configured to facilitate the insertion of each module 12 into the relevant accommodation room in a compressed state, so as to maintain the compressed state even after insertion. In this way, the module 12 of the battery C is compressed outside the accommodation room and inserted, maintaining the compressed state. By doing so, the battery C is kept compressed between the two partitions 17 that define each accommodation room. In this example, each insertion plate 32 includes a guide element 34, which is configured to guide the module 12 during the insertion of the module 12 into the corresponding accommodation room. Figure 4 As can be seen from the example, the battery pack 3 includes a plurality of heat dissipation elements 20. Figure 4 As can be seen in the example of , each battery C includes a pair of terminal electrodes TT' and TT" (positive and negative electrodes, i.e., cathode and anode) extending from the same side of the battery C. The electrodes TT' and TT" are supported by a support 27 made of a plastic material. In order to prevent contact between two adjacent batteries, the support 27 has a partition 29. In particular, the connection of the terminal electrodes TT', TT" is made at one or more connection planes 31.

[0036] Back to Figure 2 The battery pack 3 comprises at least one cooling panel 11 which is arranged at at least one side surface and is configured to be fixed to the support structure 15 by means of fixing elements 10, 10' so as to dissipate the heat transferred by the heat dissipation element 20. The battery pack 3 comprises a top opening which is sealed closed by a cover element 9.

[0037] Figure 5 Shows Figure 3 1 is an enlarged cross-sectional view of a detail of a battery pack. This view shows a control unit 13, which includes a base 37 constrained to the cover 9, which faces the connection plane 31 of the terminal electrodes TT', TT" of the battery. The base 37 supports a plurality of elements 14, which are configured to control the operating parameters (voltage, temperature, etc.) of the electrochemical cells C of the module 12. Figure 5 In the figure, reference numeral 39 denotes a spring-type elastically deformable conductive contact element for sensing the voltage of the battery. This spring conductive element 39 is configured to be elastically compressed between the planar supporting substrate 37 and the connection plane 31 of the terminal electrodes TT', TT" during use. To this end, a plurality of spring conductive elements 39 are arranged in a single row, so that more than one spring conductive element 39 is located on the connection plane 31 of the terminal electrodes TT', TT" of each electrochemical cell C. Figure 5Schematically shows the coupling between the spring conductive element 39 and the connection plane 31 of the electrodes of the cells of the battery pack according to the prior art. In particular, the coupling between the overlapping terminal electrodes TT', TT" is achieved by a continuous welding line 40, which extends substantially along the entire length of the connection plane 31 and the edge of the cell below. Therefore, the contact of the spring conductive element 39 with the connection plane 31 occurs at the welding line 40, which involves a series of disadvantages (as mentioned above).

[0038] Figure 6 Shows Figure 3 , wherein the aforementioned spring conductive element 39 for measuring the battery voltage is present, and in this figure schematically shows the first step of coupling between the electrodes of the battery cells of the battery pack and the springs to optimize the contact area of ​​the spring conductive element 39 according to the invention. Figure 6 As shown, in this case, too, welding is performed along the edge of the battery so as to form a coupling between the overlapping terminal electrodes TT', TT". However, in an innovative manner, in this case, the longitudinal welding line 41 is not continuous, but is made in the form of a series of welding portions alternating with non-welding portions. In particular, the non-welding portion is located at the space between two adjacent spring conductive elements 39 arranged in the same row. Reference numeral 42 denotes a portion without the longitudinal welding line 41.

[0039] Figure 7 Shows Figure 6 , in which the second step of coupling between the spring and the electrodes of the cells of the battery pack according to the invention is schematically shown. As can be seen from this figure, the invention provides a conductive plane 43 which covers the longitudinal welding lines 41 and forms an intermediate layer between the spring conductive elements 39 and the connection plane 31 of the underlying bonding electrode. The connection between this conductive plane 43 and the connection plane 31 is achieved by welding points or transverse welding lines 44 at the portion 42 where there were previously no longitudinal welding lines 41. The transverse welding lines 44 are therefore located at the space between two adjacent spring conductive elements 39 of the row, and in this way, when the spring conductive elements 39 are pressed against the cells C, they come into contact with the surface area without welding, i.e. with the portion of the conductive plane 43 between the transverse welding lines 44. This solution achieves the desired result, since in this way there are no impurities and roughnesses in the contact area caused by welding, thus reducing the possibility of poor contact or damage to the spring covering.

[0040] at last, Figure 8 It is shown how the conductive plane 43 is supported by a handling structure 45 made of a non-conductive material, in this case in the form of a bridge, to allow an operator to position the plane 43 safely and precisely on an electrode of a battery.

Claims

1. A battery pack (3) for an electric road vehicle (1), wherein: The battery pack (3) comprises: - a plurality of planar electrochemical cells (C) arranged side by side in the mode of a battery pack; wherein each cell (C) comprises a terminal electrode (TT', TT") at a first edge; - 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 member (37); wherein the spring conductive elements (39) are arranged in a row so 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 the corresponding battery (C) to form a conductive bridge between each battery (C) and the support member (37); wherein the terminal electrodes (TT', TT") of each battery (C) are connected to each other via a longitudinal welding line (41) parallel to the first edge of the corresponding battery (C); Features: For each battery (C), a conductive plane (43) is arranged between the terminal electrode (TT', TT") and a corresponding row of the spring conductive elements (39); wherein each conductive plane (43) is constrained to the corresponding terminal electrode (TT', TT") by a point or a transverse welding line (44) at a space provided between two adjacent spring conductive elements (39) in the same row, so that when the battery pack (3) is used, the spring conductive element (39) is pressed against a portion of the conductive plane (43) without a welding point or welding line.

2. The battery pack according to claim 1, wherein: For each battery (C), a connection plane (31) is provided for connecting the terminal electrodes (TT', TT"), wherein the longitudinal welding line (41) connecting the terminal electrodes (TT', TT") of each battery (C) is formed on the corresponding connection plane (31) below the conductive plane (43).

3. The battery pack according to claim 1 or 2, wherein: Each longitudinal welding line (41) connecting the corresponding terminal electrode (TT', TT") is a dotted line, and the point or transverse welding line (44) connecting the conductive plane (43) to the terminal electrode (TT', TT") is located at a gap in the dotted longitudinal welding line (41), so that the point or transverse welding line (44) does not overlap with the longitudinal welding line (41).

4. A battery pack according to any one of the preceding claims, wherein: The terminal electrodes (TT', TT") are made in the form of conductive plates substantially along the entire first edge of each cell.

5. The battery pack according to any one of the preceding claims, wherein the battery pack further comprises: - a box-like supporting structure (15) having a rear wall and two side walls and an opening opposite the rear wall, from which the terminal electrodes (TT', TT") of the battery (C) are accessible; - a cover (9) coupled to the support structure (15) at the opening; the support (37) supporting the spring conductive element (39) is formed to be coupled to the cover (9) and facing the base of the battery (C); - at least one voltage sensing device (14) of the battery (C), supported by the support (37) and connected to the spring conductive element (39) to monitor the voltage of each battery (C).

6. The battery pack according to any of the preceding claims, wherein each conductive plane (43) is coupled to an operating body (45) made of a non-conductive material.

7. The battery pack according to claim 6, wherein: The operating body (45) made of non-conductive material includes a bridge portion parallel to the corresponding conductive plane (43) and two side portions configured to be coupled to corresponding elements of the battery pack (3).

8. A battery pack according to any one of the preceding claims, wherein: The conductive plane (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) wherein: The vehicle (1) comprises a battery pack (3) according to any one of the preceding claims.

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 a passenger compartment (5).

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