Battery pack, usually cylindrical in shape, and fuel cell system using such a pack

Abstract

The invention relates to a battery pack (1) comprising a plurality of electrochemical cells (4), the battery pack having an outer casing (10) of predetermined shape, with a main body (14) generally cylindrical of revolution about a body axis. The invention also relates to a fuel cell-based electrical power supply system, the system comprising a fuel cell, an electrical battery arrangement downstream of the fuel cell, a hydrogen gas supply arrangement, and a plurality of locations, each location being configured to receive a hydrogen tank in the form of a generally cylindrical cylinder, at least one of the locations being configured to receive, instead of a hydrogen tank, a battery pack having a shape substantially similar to a hydrogen tank. Abstract figure: Fig. 2

Description

Title of the invention: Battery pack in generally cylindrical form and fuel cell system using such a pack

[0001] The present invention relates to a battery pack generally in the form of a hydrogen bottle and to a fuel cell system using such a battery pack.

[0002] Such a battery pack can be placed in place of a hydrogen cylinder when it is desired to increase the energy storage capacity in electrical form. The present invention also relates to a fuel cell system using such a battery pack.

[0003] We are particularly interested here in fuel cell-based electrical power supply systems, such systems comprising one or more high-pressure hydrogen (H2) gas cylinders to supply the fuel cell with hydrogen, and a downstream electrical battery arrangement functional to the fuel cell, to store the energy produced in electrical form for downstream consumers.

[0004] Such an electrical power supply system can be installed on board a motor vehicle, without limitation as to type or size, including commercial vehicles, e.g., vans or trucks. In other embodiments, such an electrical power supply system can be installed on board any type of land vehicle, e.g., agricultural machinery, a railway vehicle, or a marine vehicle, including aircraft. In other embodiments, such an electrical power supply system can be installed on board stationary equipment such as an electric generator, or any other equipment.

[0005] Depending on the electrical energy consumption needs of the vehicle or generally of the equipment on board which the system is installed, a greater range in quantity of hydrogen or a greater electrical storage capacity may be required.

[0006] The inventors sought to optimize the possibility of meeting divergent objectives in terms of power and / or energy autonomy.

[0007] For this purpose, a battery pack is proposed comprising a plurality of electrochemical cells, the battery pack having an outer casing of predetermined shape, with a main body generally cylindrical of revolution around a body axis.

[0008] In practice, this shape allows the battery pack to be housed in place of a hydrogen bottle, as will be seen in detail later.

[0009] More specifically, the battery pack can replace a hydrogen bottle in a fuel cell-based electrical power supply system.

[0010] It is noted that the cylindrical shape is completely contrary to the battery pack shapes known in current electric or hybrid vehicles, for which prismatic or parallelepiped shapes are preferred, which are suitable for being integrated efficiently into the chassis, floors or underbody areas of the vehicles.

[0011] The term "battery pack" should be interpreted here as "electric battery pack" suitable for storing energy in electrical form. In practice, the voltage across the terminals of the battery pack can range from 48 volts to several hundred volts.

[0012] Here we understand by “main body” the part of the outer envelope interposed between the two ends of the outer envelope.

[0013] Advantageously, the current section of the main body is annular and circular.

[0014] An electrical connection is provided at one end of the outer casing to connect the battery pack to an electrical network of a vehicle or other installation using the system promoted here.

[0015] According to one embodiment, the outer casing comprises domed, cap-shaped ends. The caps connect continuously with the main cylindrical body.

[0016] Accordingly, the battery pack replicates the external shape of the hydrogen cylinder, including its ends. This allows for the installation, on one of the curved end sections, of a connector bracket that can accommodate the hydrogen line connector even if the connector itself is not in use. The volume of the battery pack is similar or identical to the volume of the hydrogen cylinder it replaces.

[0017] According to an alternative embodiment, the end faces can be flat. This can allow for a more economical manufacturing of the battery pack casing. For example, each of the two ends can be made in the form of a flat disc and assembled by screwing them onto the cylindrical main body. It is of course possible to have one end flat and the other end domed.

[0018] According to one embodiment, the predetermined shape has a length greater than at least twice the diameter of the main body. In a particular example, the predetermined shape has a length greater than at least 2.5 times the diameter. Preferably, the predetermined shape has a length greater than at least 3 times the diameter.

[0019] The more or less elongated form factor of the battery pack is thus characterized. The form factor and external shape of the battery pack can therefore conform to local standards for hydrogen cylinders.

[0020] According to one embodiment, the battery pack comprises a stack of modules, each module comprising a plurality of electrochemical cells arranged next to each other.

[0021] According to one embodiment, advantageously, the negative and positive terminals of an electrochemical cell are located on the same side, e.g., axial end. The other side contains no terminals.

[0022] At the collective level, the terminals of all the electrochemical cells of a module are located substantially in the same plane. This facilitates electrical connections between the different electrochemical cells of a module, using relatively simple connecting elements.

[0023] According to one embodiment, in a given module, the electrochemical cells are electrically connected in series. The electrochemical cells thus form a chain; this principle proves simpler to implement than a parallel connection.

[0024] According to one embodiment, the electrochemical cells have a cylindrical shape. This type of electrochemical cell is readily available on the market.

[0025] This may include, in particular, lithium-ion type electrochemistry, without this being limiting with regard to the present invention.

[0026] According to one embodiment, in a given module, the electrochemical cells are arranged in a hexagonal pattern in the transverse plane. The inventors have found that this hexagonal pattern is an optimum for compactness within a circular envelope.

[0027] According to one embodiment, in a given module, the number of electrochemical cells can be 19, with two concentric hexagonal levels. According to another embodiment, in a given module, the number of electrochemical cells can be 37, with three concentric hexagonal levels.

[0028] The main body has an outer diameter denoted D2 and an inner diameter denoted Dl; the wall thickness can be limited to a few millimeters. Indeed, unlike the case of a hydrogen tank, to house electrochemical cells, there is no significant internal pressure to withstand. Furthermore, a relief valve can be provided on the outer casing to prevent excessive overpressure inside the battery pack's outer casing.

[0029] According to one embodiment, each module takes the form of a thick disk. The term "pancake" can also be used. This shape is thus optimum because its shape corresponds to the available volume inside the outer casing.

[0030] The module has a diameter D5 slightly smaller than the internal diameter DI of the main body. The module has a height H2 slightly greater than the axial length of the electrochemical cells.

[0031] According to one embodiment, each module is angularly indexed around the axis A. For example, a protruding stud on the module may be provided which cooperates with a groove arranged in the inner wall of the outer casing of the battery pack.

[0032] The nipple is received in the groove so as to lock the module inside the battery pack in rotation around axis A. This allows the desired angular position of the modules and also of the electrical connection terminals to be ensured in particular to make connections by mutual contact with neighboring modules.

[0033] According to one option, the operation of installing a module inside the battery pack may be such that it requires a translational movement along the axis and then a rotational movement around the axis.

[0034] According to one embodiment, at least one connection element is provided between neighboring modules. The connection element, e.g., a busbar connection system or other, may have elastic properties so that the contact between two adjacent modules is compressed to ensure good electrical contact quality. This allows for the absorption of small dispersions and minor misalignments between neighboring modules.

[0035] According to one embodiment, a residual axial pre-stress is provided to ensure the quality of the connections between modules.

[0036] According to one embodiment, the battery pack includes an electronic control unit 6. The electronic control unit is responsible for monitoring at least one temperature prevailing inside the battery pack and for monitoring the battery pack voltage and the current delivered and / or received by the battery pack. An isolation switch (relay or other) is also provided to disconnect the battery pack from the rest of the vehicle.

[0037] By way of example, it should be noted that the electrical connector for the external connection of the battery pack is located on the same side as the electronic control unit. In other words, the electronic control unit is located near the connection connector.

[0038] According to one embodiment, a thermal insulating separator is provided between two adjacent modules. This prevents a thermal incident occurring inside one module from propagating to neighboring modules. At the very least, it significantly slows the progression of any potential thermal incident towards neighboring modules.

[0039] According to one embodiment, a dummy hydrogen hose fitting is provided on the battery pack in order to allow a hydrogen connection connector to be retained. According In this design, the false hydrogen pipe fitting is located axially opposite the electrical connection.

[0040] The present invention also relates to a fuel cell-based electrical power supply system, the system comprising a fuel cell, an electrical battery arrangement downstream of the fuel cell, a dihydrogen gas supply arrangement, a plurality of locations each location being configured to receive a hydrogen tank in the form of a generally cylindrical bottle, characterized in that at least one of the locations is configured to receive, instead of a hydrogen tank, a battery pack having a shape substantially similar to a hydrogen tank, as previously described.

[0041] In other words, at least one of the locations can accommodate either a hydrogen bottle or a battery pack.

[0042] According to one embodiment, it can be provided that all available locations are equipped to receive either a hydrogen bottle or a battery pack.

[0043] According to one embodiment of the system, a dummy hydrogen pipe fitting is provided on the battery pack in order to be able to maintain a hydrogen connection connector.

[0044] The present invention also relates to an electric vehicle comprising an electrical power supply system as described above.

[0045] The invention will be further detailed by describing non-limiting embodiments, and based on the accompanying figures illustrating variants of the invention, in which: - [Fig.1] schematically illustrates an electrical power supply system in a motor vehicle, with hydrogen bottles to power a fuel cell, and, in place of one of the hydrogen bottles, the presence of a battery pack designed according to the present invention; - [Fig.2] schematically illustrates in perspective view an example of a battery pack, the outer casing not being shown; - [Fig.3] shows a cross-sectional view of the example battery pack from [Fig.2]; - [Fig.4] shows an axial cross-sectional view of the example battery pack from [Fig.2]; - [Fig.5] illustrates in perspective view an example of a module included in the battery pack; - [Fig. 6] shows another perspective view of the example module included in the battery pack; - [Fig. 7] shows a detailed cross-sectional view illustrating the angular indexing of a module inside the battery pack casing; - [Fig.8] schematically illustrates the connection of several modules in serial mode; - [Fig.9] schematically illustrates the connection of several modules in parallel mode; - [Fig. 10] schematically illustrates two examples of connecting the terminals of electrochemical cells inside a module; - [Fig. 11] illustrates in cross-section, another example of a battery pack with 37 electrochemical cells per stage, i.e. in a module; - [Fig. 12] illustrates a connecting element linking two terminals of adjacent electrochemical cells.

[0046] In the various figures, the same reference numerals designate identical or similar elements. For the sake of clarity, some elements are not necessarily shown to scale.

[0047] Figure 1 shows a functional schematic diagram of a fuel cell-based electrical power supply system installed in a vehicle in the illustrated example. As already mentioned, the vehicle can be of any type.

[0048] In the illustrated example, the vehicle is equipped with at least one wheel 89 driven by an electric motor 88 controlled by an inverter 87, these elements being known per se and therefore not described in detail here. The inverter is supplied with electrical energy from a main battery denoted Batt. The main battery Batt is recharged by the output of a fuel cell 80, possibly with the interposition of a voltage adapter device denoted 81.

[0049] The proposed system is a zero carbon emission system, that is to say it emits only water.

[0050] The voltage across the terminals of the main battery Batt will typically be a few hundred volts, for example between 200 volts and 800 volts. Lower voltages may be used.

[0051] To operate, the fuel cell 80 must be supplied with dihydrogen gas H2. In the illustrated example, removable tanks labeled 3 are shown which can be exchanged; in practice, once a tank is empty, it can be replaced by a full tank.

[0052] According to an alternative solution, it may be provided to recharge the tanks by means of a recharging port 32.

[0053] According to other configurations, the hydrogen supply may include a main permanent tank and additional removable tanks.

[0054] In the illustrated example, six locations are provided for removable hydrogen tanks 3. These locations are marked C1, C2, C3, C4, C5 and C6.

[0055] The main battery is monitored by a battery monitoring unit, designated 85, also known in the trade as BMS (Battery Monitoring System).

[0056] The operation of the fuel cell and the operation of the electric motor are ensured in the illustrated example by a central supervisor identified as 8.

[0057] Following an ingenious arrangement, at location C5, an additional battery pack, with the acronym PBS and generally identified as 1, was placed in place of a hydrogen bottle.

[0058] This additional battery pack has an external shape identical to or close to the external shape of the hydrogen cylinder. Thus, it can be placed in the mechanical receptacle suitable for the hydrogen cylinder.

[0059] The battery pack in a form equivalent to a hydrogen bottle will be described in later paragraphs, but [Fig.1] already illustrates that the electrical connector 13 of the battery pack can be coupled to an electrical connector 83 belonging to a harness 84 of the power supply system, this harness being connected to the harness carrying electrical energy from the main battery.

[0060] It is noted that a voltage adapter marked 82 may be provided if the voltage of the additional battery pack PBS is substantially different from the voltage of the main battery.

[0061] It should be noted that in [Fig.1], the additional battery pack has been represented twice: firstly geographically in place of a hydrogen bottle, and secondly functionally in parallel with the main battery.

[0062] The additional battery pack is managed by a local electronic control unit identified as 6.

[0063] Figure 2 shows the interior of an example battery pack, without showing the outer casing. Conversely, section 3 of Figure 3 shows the outer casing, labeled 10.

[0064] The battery pack 1 comprises a plurality of electrochemical cells 4. In the illustrated example, there are 19 electrochemical cells arranged side by side in a plane transverse to the axis.

[0065] In practice, there is a central cell (centered on axis A), then 6 cells on a first hexagonal ring, and then 12 cells on a second hexagonal ring.

[0066] It is noted that along the axis, several cells follow one another, six in the example illustrated in [Fig.2]. Thus, there are 114 electrochemical cells in the illustrated battery pack.

[0067] In the illustrated example, the electrochemical cells are grouped into subsets called modules here and identified as 5. A module groups the electrochemical cells 4 located at the same axial position.

[0068] In the various illustrated examples, the electrochemical cells have a cylindrical shape. However, it is not excluded to use cells that have other shapes, for example prismatic cells or pouch-shaped cells (in the language of the trade).

[0069] Referring to [Fig. 4], it can be seen that the outer casing of the battery pack comprises a main body, denoted 14, having a cylindrical shape of revolution about axis A and an outer diameter, denoted D2. The outer diameter D2 can be between 10 cm and 50 cm, for example. The inner diameter is denoted D1.

[0070] The thickness of the outer casing wall can be between 3 mm and 10 mm depending on the material used to make it.

[0071] The outer casing 10 may be made of metallic material, plastic material, or composite material. The outer casing 10 has an outer wall 12 and an inner wall 11.

[0072] In one embodiment, a decommissioned hydrogen (or even oxygen) tank is reused. In other words, starting with an empty and purged hydrogen (or even oxygen) tank, it is reworked by means of internal machining.

[0073] The first end El has a domed shape; the second end E2 also has a domed shape.

[0074] The electrical connector 13 allows the battery pack to be connected to the user system's electrical network.

[0075] A hydrogen connector support marked 62 is disposed at the opposite end with respect to the electrical connector 13.

[0076] The local electronic control unit 6 is disposed in the area of ​​the first end El where the electrical connector 13 is also disposed.

[0077] Referring to figures 5 and 6, module 5 has a diameter D5 and a height H2. The different modules are stacked one on top of the other along axis A.

[0078] Each module includes a plate 50 with recesses 51 forming individual holding housing for an electrochemical cell 4. The plate 50 is typically made of molded plastic.

[0079] In addition to the aforementioned plate 50, a cylindrical annular ferrule, designated 57, may be provided which radially borders the module on the outside and protects electrochemical cells. The module packaging can be completed by a top face 58 on which are arranged bus bars for electrical connection which are discussed below.

[0080] Each module 5 has two electrical connection terminals Bl, B2. The two electrical connection terminals are located on the same axial end of the module, or alternatively be arranged on either side as will be seen later.

[0081] Generally, the modules are electrically connected to each other by means of connection elements 18.

[0082] Each electrochemical cell is connected to its neighbor by means of a first bar bus, denoted 17, and another similar bar bus.

[0083] As illustrated in [Fig. 12], the bus bar 17 electrically connects the positive terminal of one electrochemical cell to the negative terminal of one of the neighboring electrochemical cells. The bus bar may be covered with insulation, at least in its intermediate section.

[0084] Since the central positive terminal of the cell is slightly higher than the peripheral annular negative terminal, the busbar has a step to compensate for the height difference.

[0085] Furthermore, an internal vertical busbar 52 is provided which allows the positive terminal or the negative terminal to be exited either on the upper or lower face of the module, depending on the usage configuration.

[0086] As illustrated in [Fig.7], angular indexing is provided.

[0087] Each module is equipped with a stud 56. The inner wall 11 of the outer casing 10 has a groove 16. The stud 56 is received in the groove 16 by complementary shape with sufficient clearance to allow the studs to slide axially in the groove. Two diametrically opposed studs of different shapes may be provided to serve as a keying device during assembly.

[0088] A person skilled in the art understands that the shapes could be reversed, namely a recessed shape on the module side and a protruding shape on the inner wall side of the envelope.

[0089] As illustrated in [Fig. 8], the modules can be connected in series. According to this diagram, the positive terminal of the lower module is connected to the negative terminal of the module above it. The positive terminal of that adjacent module is connected to the negative terminal of the module above it, and so on. A negative conductor 70 is provided to run from the main negative terminal to the top, i.e., to the end equipped with the connection connector 13.

[0090] The mechanical assembly of the end of the casing generates an axial stress that presses the modules against each other and puts stress on the connecting elements 18, which may have elasticity designed for this purpose.

[0091] As illustrated in [Fig. 9], the modules can be connected in parallel. In this case, two diametrically opposed electrical collectors are provided: the negative collector 71 and the positive collector 72. Each module has its negative terminal connected to the negative collector 71 and its positive terminal connected to the positive collector 72.

[0092] Figure 9 also shows a variant concerning one end of the outer casing. A cover 10B is provided which closes, for example by a screw system, the end of the casing, relative to the main body 10A.

[0093] Figure 10 illustrates two variants of serial connection within a module. It can be seen that the two terminals of a module are not necessarily diametrically opposed. There may be one terminal in the center and the other on the periphery, or the two peripheral terminals may be close to each other.

[0094] Fig. 11 shows a variant with 39 cells. There is a central cell (centered on axis A), then 6 cells on a first hexagonal ring, then 12 cells on a second hexagonal ring, and then 18 cells on a third hexagonal ring.

[0095] In addition, the modules 5 are separated by a thermal insulating separator marked 7. Thus a thermal incident occurring inside one module will not easily propagate to neighboring modules.

[0096] According to one embodiment, the weight of a battery pack as proposed can be less than 35 kg or 30 kg, which allows handling without special lifting tools, by one or two people.

[0097] According to one embodiment, the voltage across the terminals of the battery pack as proposed can be between 24 volts and 48 volts, in which case we remain in the field of very low voltage which does not require any special insulation precautions or protection of persons.

[0098] Of course, according to another embodiment the voltage across the terminals of the battery pack can be greater than 48 volts and go up to a few hundred volts.

[0099] The number of locations for hydrogen cylinders or additional battery packs can be arbitrary. In [Fig. 1], we have illustrated three locations C4, C5, C6 which can accept either a hydrogen cylinder or an additional battery pack, but of course there could be more, or two, or only one.

[0100] Advantageously, the same technical platform can serve several vehicle variants, some variants being range-oriented with a maximum of locations occupied by hydrogen bottles and conversely some power-oriented variants with a certain number of locations occupied by additional battery packs.

[0101] Furthermore, it is noted that the same vehicle can be reconfigured during its life.

[0102] A system installed on board a vehicle has been illustrated; however, as already As mentioned, the system can be installed on a machine or equipment other than a vehicle.

Claims

Demands

1. Battery pack (1) comprising a plurality of electrochemical cells (4), the battery pack having an outer casing (10) of predetermined shape, with a main body (14) generally cylindrical of revolution about a body axis (A).

2. Battery pack according to claim 1, wherein the outer casing comprises domed, cap-shaped ends.

3. Battery pack according to any one of claims 1 to 2, wherein the predetermined shape has a length (L2) greater than at least twice the diameter (D2) of the main body.

4. Battery pack according to any one of claims 1 to 3, wherein the battery pack comprises a stack of modules (5), each module comprising a plurality of electrochemical cells (4) arranged next to each other.

5. Battery pack according to claim 4, wherein each module takes the form of a thick disc.

6. Battery pack according to any one of claims 4 to 5, wherein there is provided a system of at least one connection element (18) between the modules (5).

7. Battery pack according to any one of claims 1 to 6, wherein the battery pack includes an electronic control unit (6).

8. Battery pack according to any one of claims 4 to 5, wherein a thermal insulating separator (7) is provided between two adjacent modules.

9. Fuel cell-based electrical power supply system, the system comprising a fuel cell (FC), an electrical battery arrangement downstream of the fuel cell, a dihydrogen gas supply arrangement, a plurality of locations, each location being configured to receive a hydrogen tank in the form of a generally cylindrical bottle, characterized in that at least one of the locations is configured to receive, instead of a hydrogen tank, a battery pack having a shape substantially similar to a hydrogen tank, as defined in any one of claims 1 to 8.

10. Electric vehicle comprising an electrical power supply system according to claim 9.

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