UNIT FOR ELASTIC CONNECTION OF ELECTROCHEMICAL CELLS AND CORRESPONDING INSTALLATION PROCEDURE

Description

[0001] The present invention relates to an interconnection system for electrochemical cells.

[0002] The invention is particularly applicable to the manufacture of batteries for electric or hybrid vehicles.

[0003] An electrochemical cell comprises an electrolyte contained within a closed outer casing, generally of a roughly parallelepiped shape. The electrochemical cell typically includes terminals in contact with the electrolyte and attached to the outer casing, on the outside of said casing.

[0004] For example, the electrochemical cell comprises a stack of interconnected positive electrodes and a stack of interconnected negative electrodes, separated by a separator. Such an assembly, known as a "stack," is housed in the outer casing.

[0005] It is known to assemble, in series and / or in parallel, a plurality of electrochemical cells in order to make electrical modules, using an interconnection device ensuring electrical contact between the terminals of two neighboring cells.

[0006] It is known from the prior art, for example from documents US 2016 / 126524 A1 and US 2010 / 021810 A1, to connect adjacent battery cells by means of rigid metallic interconnect devices which are permanently fixed, for example by deformation, welding or gluing.

[0007] This method does not allow for the non-destructive dismantling of the assembly by separating the cells.

[0008] Demountable systems are also known but do not offer sufficient results in terms of mechanical strength or electrical power transmission.

[0009] The present invention aims to solve these problems and to provide a simple interconnection system that is easy to install and uninstall, without requiring expensive equipment.

[0010] For this purpose, the invention relates to an interconnection assembly of the aforementioned type, comprising a first and a second electrochemical cell, each of said first and second cells comprising an outer envelope and at least one terminal disposed outside the outer envelope along an axis; said assembly further comprising an interconnection device, comprising a first and a second interconnection element; each of said first and second interconnection elements comprising a fixing surface and a contact surface.The fixing surface of each of the first and second interconnecting elements is suitable for being fixed to the terminal, respectively of the first and second cells, in an installed configuration of the interconnecting assembly; such that, in said installed configuration, the contact surfaces of the first and second interconnecting elements exert a force on each other along an assembly direction of the first and second cells, the assembly direction being substantially perpendicular to the axis of at least one terminal, the interconnecting device thus ensuring an electrical connection between the first and second cells; and the contact surfaces are configured so that, in said installed configuration, said contact surfaces are substantially arranged in a plane forming a constrained angle with said assembly direction, said constrained angle being between 45° and 85°.

[0011] According to other advantageous aspects of the invention, the interconnection assembly comprises one or more of the following characteristics, taken individually or in all technically possible combinations: The connection zone of at least one of the first and second interconnecting elements further comprises a third curved portion, consecutive to the second portion, the second and third portions having concavities opposite to each other; the terminal of at least one of the first and second cells has a terminal surface substantially perpendicular to the axis; and the mounting surface of at least one of the first and second interconnecting elements is configured to conform to said terminal surface in the installed configuration; the terminal of at least one of the first and second cells projects from the outer casing along the axis and comprises a lateral surface parallel to said axis; and the mounting surface of at least one of the first and second interconnecting elements is configured to conform to said lateral surface in the installed configuration;in a dissociated configuration of said assembly, in the absence of force between the first and second interconnecting elements, each contact surface is substantially arranged in a plane forming an unconstrained angle with the corresponding fixing surface, said unconstrained angle being between 45° and 85°, said unconstrained angle being less than or equal to the constrained angle. ;

[0012] The invention further relates to a method of assembling the interconnection assembly described above, comprising the following steps: fixing the fixing surface of each of the first and second interconnection elements of the interconnection device, to the terminal, respectively, of the first and second cells; then bringing the first and second cells together in the direction of assembly, so that the contact surfaces of the first and second interconnection elements come into contact and exert a force on each other in the direction of assembly.

[0013] According to other advantageous aspects of the invention, the process includes one or more of the following characteristics: The force between the contact surfaces induces an elastic deformation of the bonding zone of at least one of the first and second interconnecting elements; the fixing of the fixing surface on the terminal is carried out by welding or brazing.

[0014] The invention further relates to an electrical component, of the module or battery type, comprising: a first and a second electrochemical cell; and an interconnection device; each of said first and second cells comprising an outer envelope and a terminal disposed outside the outer envelope along an axis; the interconnection device, comprising a first and a second interconnection element; each of said first and second interconnection elements comprising a fixing surface and a contact surface, the fixing surface of each of the first and second interconnection elements being fixed to the terminal, respectively, of the first and second cells; the contact surfaces of the first and second interconnection elements exerting a force on each other along an assembly direction of the first and second cells, the assembly direction being substantially perpendicular to the axis of the terminal, the interconnection device thus ensuring an electrical connection between the first and second cells; the contact surfaces being substantially arranged in a plane forming a constrained angle with said assembly direction, said constrained angle being between 45° and 85°;the electrical component being likely to be produced by a process such as that described above.

[0015] The invention further relates to an electric vehicle comprising such an electrical component.

[0016] The invention will be better understood upon reading the following description, given solely by way of non-limiting example and made with reference to the drawings in which: there figure 1 is a partial, perspective view of an interconnection system according to a first embodiment of the invention, in a first configuration; the figure 2 is a side view of elements of the whole of the figure 1 , in a second configuration; the figure 3 is a partial, perspective view of an interconnection assembly according to a second embodiment of the invention, in a first configuration; and the figure 4 is a side view of elements of the whole of the figure 3, in a second configuration.

[0017] THE Figures 1 And 3 represent 10 and 110 interconnection sets, respectively according to a first and a second embodiment of the invention.

[0018] Sets 10 and 110 will be described simultaneously below, with common elements designated by the same reference numbers.

[0019] The interconnection assembly 10, 110 comprises a first 12, 112 and a second 14, 114 electrochemical cells and an interconnection device 16, 116.

[0020] The interconnecting device 16, 116 is designed to electrically connect the first 12, 112 and second 14, 114 cells, as described below. For this purpose, said interconnecting device is made of one or more electrically conductive materials, preferably metallic. The interconnecting device is, for example, made of aluminum.

[0021] As a guide, an element is considered electrically conductive here if its electrical conductivity is greater than σ = 0.7 * 10 6< S·m -1< .

[0022] In general, the invention is capable of electrically connecting a plurality of cells, in particular by a series or parallel arrangement.

[0023] In the following description, the cells in each set 10, 110 are considered identical. Only the first cell, 12, 112, will be described below.

[0024] The cell 12, 112 comprises an outer envelope 20 and at least one first terminal 22, 122 arranged on the outer envelope. Typically, the cell 12, 112 further comprises a second terminal 24, 124, the first and second terminals preferably being of opposite polarities. In this description, the second terminal 24, 124 of each cell is assumed to have a shape similar to the first terminal 22, 122 of said cell. The second terminals 24, 124 of the second cells 14, 114 are visible respectively on the figure 1 and on the figure 3 .

[0025] Each terminal 22, 24, 122, 124 extends along an axis 26 and has a terminal surface 27, 127, substantially perpendicular to said axis 26.

[0026] In the implementation of the figure 1, the terminal surface 27 is flat and is approximately flush with the outer envelope 20. In other words, each terminal 22, 24 forms a small or zero projection relative to the outer envelope 20.

[0027] In the implementation of the figure 3 , each terminal 122, 124 forms a projection relative to the outer envelope 20 along the axis 26. Each of said terminals 122, 124 has a lateral surface 128, parallel to said axis 26.

[0028] In the implementation of the figure 3 The lateral surface 128 is cylindrical with a roughly square or rectangular cross-section. In an alternative not shown, the lateral surface is cylindrical with a non-rectangular polygonal cross-section, or even with a circular or oblong cross-section. More generally, the shape of the marker is not limited to those shown in the figures.

[0029] Each of the Figures 1 And 3shows one of the assemblies 10, 110 in an installed configuration of said assembly, possibly corresponding to an assembly stage of an electrical component of the module or battery type, as described below. An orthonormal basis (X, Y, Z) is considered associated with each assembly 10, 110.

[0030] In the installed configuration, the first 12, 112 and second 14, 114 cells are arranged side by side so that the first terminal 22, 122 of the first cell and the second terminal 24, 124 of the second cell are close and opposite each other, the axes 26 of said terminals being substantially parallel.

[0031] In the embodiments shown, the first and second cells are considered to be aligned along X and the axes 26 are parallel to Z.

[0032] The 16,116 interconnection device will now be described. Each of the figures 2 And 4shows a profile view of one of the 16, 116 interconnecting devices in a dissociated configuration.

[0033] The interconnection device 16, 116 comprises a first 30, 130 and a second 32, 132 interconnection elements. In the embodiment of the Figures 1 And 2 The first 30 and second 32 interconnecting elements are of different shapes. In the embodiment of the figures 3 And 4 , the first 130 and second 132 interconnection elements are of identical shape.

[0034] Each of the first 30, 130 and second 32, 132 interconnecting elements comprises a mounting surface 34, 134 and a contact surface 36, 136 connected to each other. In the embodiments shown, each of the interconnecting elements further comprises a linking area 38, 39, 138 interposed between the mounting surfaces 34, 134 and the contact surfaces 36, 136.

[0035] More specifically, in the embodiments shown, each interconnecting element 30, 32, 130, 132 is formed from a metal strip, for example made of aluminum. The fixing surfaces 34, 134 and contact surfaces 36, 136 of the same interconnecting element are arranged at the ends of said metal strip, on either side of the connecting area 38, 39, 138.

[0036] In the example of Figures 1 And 2 , each fixing surface 34 is flat. In the example of the figures 3 And 4 Each fixing surface 134 comprises a flat central portion 140 and a flat end portion 142. The central portion 140 is located between the end portion 142 and the connection zone 138. In the dissociated configuration of the figure 4 , the central portion 140 and the end portion 142 form an angle of approximately 90°.

[0037] In the embodiments shown, each contact surface 36, 136 is flat and inclined relative to the fixing surface 34, 134. In the example of the figures 3 And 4 , we consider the inclination of the contact surface 136 with the central portion 140 of the fixing surface 134.

[0038] The mounting surfaces 34 and contact surfaces 36 of the first interconnecting element 30 of the assembly 10 are located on the same face of the metal strip forming said first element. Conversely, the mounting surfaces 34 and contact surfaces 36 of the second interconnecting element 32 of the assembly 10 are located on opposite faces of the metal strip forming said second element. Similarly, the mounting surfaces 134 and contact surfaces 136 of each of the first and second interconnecting elements 130, 132 of the assembly 110 are located on opposite faces of the metal strip forming each of said elements. However, for the sake of consistency in the description, the angle of inclination between the mounting and contact surfaces is considered here to be an acute angle, that is, between 0° and 90°.

[0039] In the dissociated configuration of the figure 2Each contact surface 36 is inclined relative to its corresponding mounting surface 34 at an angle known as an unconstrained angle. More precisely, in the dissociated configuration, the first interconnecting element 30 of the assembly 10 has a first angle α between the mounting surfaces 34 and the contact surface 36; and the second interconnecting element 32 has a second angle β between the mounting surfaces 34 and the contact surface 36. Each of the first and second angles α, β is between 45° and 85°. The first and second angles may be the same or different. In the example of the figure 2 The first angle is greater than the second angle.

[0040] Similarly, in the dissociated configuration of the figure 4, each of the first and second interconnection elements 130, 132 of the assembly 110 has an angle γ called unconstrained between the central portion 140 of the fixing surface 134 and the contact surface 136. The angle γ is between 45° and 85°.

[0041] The connection zone 38, 39, 138 comprises at least a first 44, 45, 144 and a second 46, 47, 146 parts, aligned with each other, the first and second parts being arranged respectively near the fixing surface 34, 134 and near the contact surface 36, 136. As visible on the figures 1 to 4 , each of the first and second parts has a curved shape, the concavities of said first and second parts being oriented towards opposite faces of the first 30, 130 or the second 32, 132 corresponding interconnecting element.

[0042] Optionally, the connecting zone includes further variations in concavity between the fixing and contact surfaces. For example, the second interconnecting element 32 of the assembly 10 includes a third curved part 49, disposed between the second part 47 and the contact surface 36, whose concavity is oriented towards the same face as the first part 45.

[0043] The 16 interconnection device of Figures 1 And 2 and set 10 of the figure 1 will now be described in more detail.

[0044] The mounting surface 34 of at least one of the first 30 and second 32 interconnecting elements is configured to fit the terminal surface 27 of a terminal 22, 24 of the first 12 or second 14 cell in the installed configuration of the assembly 10. In the example of the figure 1In the installed configuration, the first interconnecting element 30 is fixed to the first terminal 22 of the first cell 12, the fixing surface 34 of said first interconnecting element fitting the terminal surface 27 of said first terminal 22; and the second interconnecting element 32 is fixed to the second terminal 24 of the second cell 14, the fixing surface 34 of said second interconnecting element fitting the terminal surface 27 of said second terminal 24.

[0045] In the installed configuration of the figure 1 , each of the fixing surfaces 34 of the first and second interconnection element 30, 32 therefore extends substantially along a plane (X, Y).

[0046] Furthermore, in the installed configuration of the figure 1The contact surfaces 36 of the first and second interconnecting elements 30, 32 are in contact with each other, each of said contact surfaces exerting a force oriented along X on the other contact surface. Due to this force, in the installed configuration, each contact surface 36 is inclined at the same angle α', called the constrained angle, relative to the fixing surface. The angle α' is greater than or equal to, and preferably strictly greater than, each of the first angle α and second angle β of the dissociated configuration of the figure 2 By "strictly greater", we mean that the angle α' is closer to 90° than each of the first angle α and second angle β.

[0047] The 116 interconnection device of figures 3 And 4 and set 110 of the figure 3 will now be described in more detail.

[0048] The mounting surface 134 of at least one of the first 130 and second 132 interconnecting elements is configured to fit the lateral surface 128 of a terminal 122, 124 of the first 112 or second 114 cell in the installed configuration of the assembly 110. In the example of the figure 3 In the installed configuration, the first interconnecting element 130 is fixed to the first terminal 122 of the first cell 112, the fixing surface 134 of said first interconnecting element fitting the lateral surface 128 of said first terminal 122; and the second interconnecting element 132 is fixed to the second terminal 124 of the second cell 114, the fixing surface 134 of said second interconnecting element fitting the lateral surface 128 of said second terminal 124.

[0049] More specifically, the central portion 140 and the end portion 142 of each fixing surface 134 respectively fit a face located in a plane (X, Z) and a face located in a plane (Y, Z) of the corresponding lateral surface 128.

[0050] Furthermore, in the installed configuration of the figure 3 The contact surfaces 136 of the first and second interconnecting elements 130, 132 are in contact with each other, each of said contact surfaces exerting a force oriented along X on the other contact surface. Due to this force, in the installed configuration, each contact surface 136 is inclined at the same angle γ', called the constrained angle, relative to the fixing surface. The angle γ' is greater than or equal to, and preferably strictly greater than, the angle γ of the dissociated configuration of the figure 4 By "strictly greater", we mean that the angle γ' is closer to 90° than the angle γ.

[0051] A method for assembling the interconnection set 10, 110 described above will now be described.

[0052] The process relates to the production of an electrical component of the module, pack or battery type. Such an electrical component comprises a plurality of cells 12, 14, 112, 114, connected in pairs in series or in parallel by a plurality of interconnection devices 16, 116.

[0053] A first step in the said process consists of fixing each first 30, 130 and each second 32, 132 interconnection element to a cell terminal 22, 24, 122, 124.

[0054] In particular, the mounting surface 34, 134 of the first interconnecting element 30, 130 described above is fixed to the first terminal 22, 122 of the first cell 12, 112 described above; and the mounting surface 34, 134 of the second interconnecting element 32, 132 described above is fixed to the second terminal 24, 124 of the second cell 14, 114 described above.

[0055] In the case of set 10 of the figure 1 , each fixing surface 34 is fixed to the terminal surface 27 of the corresponding terminal. In the case of assembly 110 of the figure 3 , each fixing surface 134 is fixed to the lateral surface 128 of the corresponding terminal.

[0056] The cells are attached, for example, by welding or brazing, before being assembled together. This allows for the creation of a suitable environment for welding or brazing in the first step of the process.

[0057] Other fixing solutions are possible, for example, fixing by clipping the fixing surface 134 onto the lateral surface 128 of the corresponding terminal.

[0058] Preferably, for cells 12, 14, 112, 114 each comprising two terminals, each terminal of the cells intended to be assembled to make the electrical component is equipped with a first 30, 130 or a second 32, 132 element of an interconnection device 16, 116.

[0059] A second step in the process involves assembling the cells, equipped with interconnecting elements, to create the electrical component. This second step can be carried out at a different site than the first step described above.

[0060] In particular, the first 12, 112 and second 14, 114 cells are placed opposite each other, with the first terminal 22, 122 of the first cell aligned along X with the second terminal 24, 124 of the second cell. The first and second cells are then brought closer together so that the contact surfaces 36, 136 of the first 30, 130 and second 32, 132 interconnecting elements come into contact with each other. The bringing together along X is continued so as to apply a force from one of the contact surfaces 36, 136 on the other. The multi-curvature shape of the connecting zone 38, 39, 138 allows for a spring effect: said connecting zone deforms elastically, changing the inclination between the contact zone 36, 136 and the corresponding fixing zone. Preferably, under mechanical stress, the angle of inclination α', γ' thus approaches 90°.

[0061] The elastic deformation of the bonding zone 38, 39, 138 allows the contact surfaces 36, 136 to be pressed against each other with a force along X, thus ensuring good electrical contact between the first 12, 112 and second 14, 114 cells. The flexibility of the assembly allows for electrical contact under all circumstances.

[0062] The dimensions of the interconnecting elements, particularly their thickness, allow the force to be modulated according to X and the mechanical strength of the assembly, in order to optimize electrical transmission.

[0063] The step of assembling two cells is repeated, so as to assemble in series and / or in parallel a plurality of cells equipped with interconnecting elements.

[0064] The outer envelopes 20 of the cells are then joined together to maintain the applied force between the interconnecting elements.

[0065] This produces an electrical component of the module or battery type.

[0066] Such a cell assembly step is easy to perform; the cells can also be easily dissociated if one of said cells of the electrical organ needs to be replaced. Nomenclature: Reference Corresponding element 10, 110 Interconnection set 12, 112 First cell 14, 114 Second cell 16, 116 Interconnection device 20 Outer envelope 22, 122 First milestone 24, 124 Second marker 26 Terminal axis 27, 127 Terminal surface of the terminal 128 Lateral surface of the terminal 30, 130 First interconnection element of the interconnection device 32, 132 Second interconnection element of the interconnection device 34, 134 Mounting surface of an interconnecting element 36, 136 Contact surface of an interconnecting element 38, 39, 138 Connection zone of an interconnecting element 140 Central portion of connection zone 138 142 End portion of the connection zone 138 44, 45, 144 First part of the connecting zone 46, 47, 146 Second part of the connection zone 49 Third part of the link zone 39

Claims

1. Assembly (10, 110) for interconnecting electrochemical cells for an electric or hybrid vehicle, said assembly comprising a first (12, 112) and a second (14, 114) electrochemical cells, each of said first and second cells comprising an outer casing (20) and at least one terminal (22, 24, 122, 124) arranged outside the outer casing along an axis; said assembly further comprising an interconnection device (16, 116), including a first (30, 130) and a second (32, 132) interconnection element; each of said first and second interconnection elements comprising a mounting surface (34, 134) and a contact surface (36, 136), the mounting surface of each of the first and second interconnection elements being configured to be attached to the terminal (22, 24, 122, 124) of the first and second cells, respectively, in an installed configuration of the interconnection assembly; such that, in said installed configuration, the contact surfaces (36, 136) of the first and second interconnection elements apply a force to each other along an assembly direction (X) of the first and second cells, the assembly direction being substantially perpendicular to the axis of the at least one terminal, the interconnection device thereby providing an electrical connection between the first and second cells, the electrical connection being provided solely by the force between the contact surfaces; the interconnection assembly being characterised in that: the contact surfaces are configured such that, in said installed configuration, said contact surfaces are substantially arranged in a plane forming a constrained angle (α', γ') with said assembly direction, the constrained angle being between 45° and 85°: one of the first and second interconnection elements further comprises a connecting region (38, 39, 138), located between the mounting surface and the contact surface, said connecting region comprising a first (44, 45, 144) and a second (46, 47, 146) consecutive curved portions, the first and second portions having concavities opposite each other.

2. Interconnection assembly (10) according to claim 1, wherein the connecting region (39) of at least one (32) of the first and second interconnection elements further comprises a third curved portion (49), consecutive to the second portion, the second and third portions having concavities opposite each other.

3. Interconnection assembly (10) according to any one of the preceding claims, wherein: the terminal (22, 24) of at least one of the first and second cells has a terminal surface (27) substantially perpendicular to the axis; and the mounting surface (34) of at least one of the first and second interconnection elements is configured to engage said terminal surface in the installed configuration.

4. Interconnection assembly (110) according to any one of the preceding claims, wherein: the terminal of at least one of the first and second cells projects from the outer casing along the axis and comprises a lateral surface (128) parallel to said axis; and the mounting surface (134) of at least one of the first and second interconnection elements is configured to engage said lateral surface in the installed configuration.

5. Interconnection assembly (10, 110) according to any one of the preceding claims, wherein, in a separated configuration of said assembly, in the absence of force between the first and second interconnection elements, each contact surface (36, 136) is substantially arranged in a plane forming an unconstrained angle (α, β, γ) with the corresponding mounting surface (34, 134), said unconstrained angle being between 45° and 85°, the unconstrained angle being less than or equal to the constrained angle (α', γ').

6. Method for assembling the interconnection assembly (10, 110) according to any one of the preceding claims, comprising the following steps: attaching the mounting surface (34, 134) of each of the first (30, 130) and second (32, 132) interconnection elements of the interconnection device to the terminal (22, 24, 122, 124) of the first and second cells, respectively; and then bringing the first and second cells together along the assembly direction (X), such that the contact surfaces (36, 136) of the first and second interconnection elements come into contact and apply a force to each other along the assembly direction (X).

7. Assembly method according to claim 6, wherein the force between the contact surfaces induces elastic deformation of the connecting region (38, 39, 138) of at least one of the first and second interconnection elements.

8. Method according to claim 6 or 7, wherein the attachment of the mounting surface (34, 134) to the terminal is carried out by welding or brazing.

9. Electrical device comprising: a first (12, 112) and a second (14, 114) electrochemical cell; and an interconnection device (16, 116); each of said first and second cells comprising an outer casing (20) and a terminal (22, 24, 122, 124) arranged outside the outer casing along an axis; the interconnection device (16, 116) comprising a first (30, 130) and a second (32, 132) interconnection element; each of said first and second interconnection elements comprising a mounting surface (34, 134) and a contact surface (36, 136), the mounting surface of each of the first and second interconnection elements being attached to the terminal (22, 24, 122, 124) of the first and second cells, respectively; the contact surfaces (36, 136) of the first and second interconnection elements applying a force to each other along an assembly direction (X) of the first and second cells, the assembly direction being substantially perpendicular to the axis of the terminal, the interconnection device thereby providing an electrical connection between the first and second cells; the contact surfaces being substantially arranged in a plane forming a constrained angle (α', γ') with said assembly direction, the constrained angle being between 45° and 85°: the electrical device being capable of being produced by an assembly method according to any one of claims 6 to 8, of an assembly according to any one of claims 1 to 5.