Electrochemical cells, battery modules and batteries incorporating such cells

Abstract

The invention relates to an electrochemical cell incorporating a stack of electrodes separated from one another by a porous separator film, comprising a first electrical connection terminal, a second electrical connection terminal of opposite polarity to the first electrical connection terminal, wherein the first electrical connection terminal comprises a first tab projecting in the plane of the electrochemical cell between a first joining edge at which it adjoins a first face of the electrochemical cell and a first free-end edge; - and wherein the second electrical connection terminal comprises a second tab projecting in the plane of the electrochemical cell between a second joining edge at which it adjoins a second face of the electrochemical cell opposite the first face and a second free-end edge; the first tab has a first surface, and the second tab has a second surface smaller than the first surface.

Description

Electrochemical cells and battery modules and batteries incorporating such cells

[0001] The present invention relates to electrochemical cells, and more particularly to the electrical connection of such cells in a battery module or in a battery intended to equip a motor vehicle at least partially supplied with propulsion energy by electric battery. The invention also relates to electrical modules, battery packs and batteries comprising such cells.

[0002] An electric battery intended to equip a hybrid or electric vehicle comprises an accumulator comprising several modules or battery packs integrating a plurality of electrochemical cells mechanically assembled together in one or more rows and electrically connected to each other in series or in parallel. An electric battery is understood to mean a set of electrochemical cells assembled in a support structure, either by intermediate grouping in the form of modules, or according to an architecture called, in English, "Cell-To-Pack" (CTP) or "Cell-To-Chassis" (CTC), in which the cells are arranged adjacently without intermediate grouping in the form of modules. This method of direct integration of the cells makes it possible to produce a battery having increased compactness, a reduction in mass, as well as an improved energy density compared to traditional architectures comprising intermediate modules.Thus, unless otherwise indicated, the expression "electric battery" (whether a PTC battery, a CTC battery or a module battery, depending on the mode of integration of the cells) designates a plurality of electrochemical cells arranged, with or without intermediate modules, within a single structure. A battery module, or a battery pack integrating a plurality of battery modules, generally provides additional functions such as encapsulation, mechanical protection, thermal or electrical monitoring, functions which are absent or redistributed differently in PTC or CTC architectures.

[0003] The electrical connection between two adjacent electrochemical cells in the same row, whether within a battery module or, more generally, an electric battery, is provided by an electrical connection plate or bar, usually called a "busbar" in English terminology. This electrical connection bar, made of a conductive material, connects the electrical connection terminals (or poles) of two adjacent electrochemical cells.

[0004] Each of the electrical connection terminals is in the form of a flexible metal strip or, more generally, a tab, commonly called a "tab" in English, intended to be folded against the electrical connection bar and welded thereto. Indeed, a common method for electrically connecting two adjacent electrochemical cells in a battery module or in an electric battery consists of arranging an electrical connection bar so that it extends between the two electrical connection tabs opposite two adjacent electrochemical cells, folding these electrical connection tabs onto the electrical connection bar, and laser welding each electrical connection tab onto the electrical connection bar.

[0005] The electrical connection bar is provided to be wide enough (in a connection direction between the two electrochemical cells perpendicular to the planes of the two adjacent cells) to receive the two electrical connection terminals each separately and without overlapping one on the other. Most often, the electrical connection bar comprises two parts and each of the two parts is soldered to one of the two connection tabs, so as to electrically connect the two adjacent electrochemical cells, without overlapping of the two tabs on the electrical connection bar.

[0006] However, such an electrical connection bar is not entirely satisfactory, particularly due to its dimensions. An inherent disadvantage of the electrical connection bar is that it increases the size and weight of battery modules or electric batteries, in addition to its manufacturing cost due to the quantity of material used.

[0007] Document EP1770801A1 describes electrode tabs of various shapes and lengths. Document EP2804239A1 discloses an electrode assembly having different shapes of anode weld portion and cathode.

[0008] An object of the present invention is to ensure reliable electrical connections between the connection terminals of the electrochemical cells of a battery module or an electric battery, while reducing the size of the battery modules or electric batteries.

[0009] Another object of the present invention is to provide an electrochemical cell allowing the use of a narrow electrical connection bar for space-saving series or parallel mounting of electrochemical cells.

[0010] Another object of the present invention is to improve the energy density of electric batteries or battery packs.

[0011] Another object of the present invention is to improve the overall performance of hybrid or electric vehicles.

[0012] For this purpose, it is proposed, firstly, an electrochemical cell integrating a stack of electrodes separated from each other by a porous separator film, this electrochemical cell comprising a first electrical connection terminal, a second electrical connection terminal of polarity opposite to the first electrical connection terminal, - the first electrical connection terminal integrating a first tab extending in projection between a first junction edge with a first face of the electrochemical cell and a first free end edge opposite the first junction edge; - the second electrical connection terminal integrating a second tab extending in projection between a second junction edge with a second face of the electrochemical cell opposite the first face and a second free end edge opposite the second junction edge;the first tab has a first surface and the second tab has a second surface less than the first surface.;

[0013] Various additional features may be provided, alone or in combination:- the second tab comprises, relative to the first tab, at least a first notch;- the first notch is made on a first edge connecting the second free end edge to the second joining edge of the second tab;- the second tab comprises a second notch substantially symmetrical to the first notch relative to a plane substantially perpendicular to the second joining edge.- the stack of electrodes is arranged in a flexible bag, the cell further comprising an electrolyte in the bag.

[0014] Secondly, a battery module is proposed comprising at least: - a first electrochemical cell and a second electrochemical cell each integrating a stack of electrodes separated from each other by a porous separator film, a first electrical connection terminal, a second electrical connection terminal of polarity opposite to the first electrical connection terminal, the first electrical connection terminal integrating a first tab extending in projection between a first junction edge with a first face of the electrochemical cell and a first free end edge opposite the first junction edge; the second electrical connection terminal integrating a second tab extending in projection between a second junction edge with a second face of the electrochemical cell opposite the first face and a second free end edge opposite the second junction edge;the first tab having a first surface and the second tab having a second surface lower than the first surface, the second tab comprising, relative to the first tab, at least a first notch;- an electrical connecting bar electrically connecting the first electrochemical cell and the second electrochemical cell, the first tab of the first electrochemical cell being folded onto the electrical connecting bar, the second tab of the second electrochemical cell being folded onto the first tab of the first electrochemical cell;the battery module further comprising: - a first laser welding bead in an area of ​​said first tab of the first electrochemical cell not covered by said second tab of the second electrochemical cell corresponding to the first notch of this second tab of the second electrochemical cell, for welding said first tab of the first electrochemical cell to the electrical connection bar.;

[0015] Various additional features may be provided, alone or in combination:- the first tab of the first electrochemical cell is made of a first material comprising a first metal, the electrical connecting bar being made of a second material comprising the first metal;- the first metal is predominant in the first material and in the second material;- the battery module further comprises a second laser weld bead in an overlapping area between said first tab of the first electrochemical cell and said second tab of the second electrochemical cell for welding the second tab of the second electrochemical cell to the first tab of the first electrochemical cell;- the first notch is made on a first edge connecting the second free end edge to the second joining edge of the second tab;- the second tab of the second electrochemical cell comprises, with respect to the first tab of the second electrochemical cell, at least one second notch substantially symmetrical to the first notch with respect to a plane substantially perpendicular to the second junction edge of the second tab of the second electrochemical cell with said second face of the second electrochemical cell; - the stack of electrodes is arranged in a flexible bag, the cell further comprising an electrolyte in the bag.;

[0016] Thirdly, there is provided a battery pack incorporating a plurality of the battery modules described above.

[0017] Fourthly, an electric battery is proposed comprising at least:- a first electrochemical cell and a second electrochemical cell each integrating a stack of electrodes separated from each other by a porous separator film, a first electrical connection terminal, a second electrical connection terminal of polarity opposite to the first electrical connection terminal, the first electrical connection terminal integrating a first tab extending in projection between a first junction edge with a first face of the electrochemical cell and a first free end edge opposite the first junction edge; the second electrical connection terminal integrating a second tab extending in projection between a second junction edge with a second face of the electrochemical cell opposite the first face and a second free end edge opposite the second junction edge;the first tab having a first surface and the second tab having a second surface lower than the first surface, the second tab comprising, relative to the first tab, at least a first notch;- an electrical connecting bar electrically connecting the first electrochemical cell and the second electrochemical cell, the first tab of the first electrochemical cell being folded onto the electrical connecting bar, the second tab of the second electrochemical cell being folded onto the first tab of the first electrochemical cell;the electric battery further comprising: - a first laser welding bead in an area of ​​said first tab of the first electrochemical cell not covered by said second tab of the second electrochemical cell corresponding to the first notch of this second tab of the second electrochemical cell, for welding said first tab of the first electrochemical cell to the electrical connecting bar.;

[0018] Various additional features may be provided, alone or in combination:- the first tab of the first electrochemical cell is made of a first material comprising a first metal, the electrical connecting bar being made of a second material comprising the first metal;- the first metal is predominant in the first material and in the second material;- the electric battery further comprises a second laser welding bead in an overlapping area between said first tab of the first electrochemical cell and said second tab of the second electrochemical cell for welding the second tab of the second electrochemical cell to the first tab of the first electrochemical cell;- the first notch is made on a first edge connecting the second free end edge to the second joining edge of the second tab;- the second tab of the second electrochemical cell comprises, with respect to the first tab of the second electrochemical cell, at least one second notch substantially symmetrical to the first notch with respect to a plane substantially perpendicular to the second junction edge of the second tab of the second electrochemical cell with said second face of the second electrochemical cell; - the stack of electrodes is arranged in a flexible bag, the cell further comprising an electrolyte in the bag.;

[0019] Fifthly, there is provided a method of electrical connection between a first electrochemical cell and a second electrochemical cell in a battery module, in a battery pack or in an electric battery presented above, comprising the following steps:- folding the first tab of the first electrochemical cell onto an electrical connecting bar and the second tab of the second electrochemical cell onto the first tab of the first electrochemical cell;- applying a first laser welding bead in an area of ​​said first tab of the first electrochemical cell not covered by said second tab of the second electrochemical cell corresponding to the first notch of this second tab of the second electrochemical cell, to weld said first tab of the first electrochemical cell to the electrical connecting bar;- applying a second laser weld bead in an overlapping area between said first tab of the first electrochemical cell and said second tab of the second electrochemical cell to weld the second tab of the second electrochemical cell to the first tab of the first electrochemical cell.;

[0020] Other characteristics and advantages of the invention will appear more clearly and concretely on reading the following description of embodiments, which is given with reference to the appended drawings in which:

[0021] the figure schematically illustrates an electrochemical cell according to various embodiments;

[0022] the figure schematically illustrates a portion of a battery module, battery pack or electric battery according to various embodiments;

[0023] the figure schematically illustrates an electrical connection between two adjacent electrochemical cells of a battery module, battery pack or electric battery according to various embodiments;

[0024] the figure schematically illustrates steps of a method of electrical connection between two adjacent electrochemical cells of a battery module, a battery pack or an electric battery according to various embodiments.

[0025] Referring to the, there is shown an electrochemical cell10 intended to be integrated into a device30, in particular a battery module30, a battery pack30, or an electric battery30. This electrochemical cell10 comprises a stack of electrodes separated from each other by a porous separator film. The stack of electrodes is arranged (or wrapped) in a flexible pouch comprising an electrolyte. The electrochemical cell10 may, in fact, be a pouch cell or a flexible packaging cell, commonly called a "Pouch".

[0026] As shown in the, the electrochemical cell10 comprises a first electrical connection terminal1 (or pole) and a second electrical connection terminal2 of opposite polarity to the first electrical connection terminal1.

[0027] The first electrical connection terminal1 comprises a first tab11 extending protruding between a first edge12 for joining with a first face14 of the electrochemical cell10 and a first free end edge13 opposite the first joining edge12. The first tab11 forms, for example, the positive electrical connection terminal of the electrochemical cell10. The first tab11 is, in one embodiment, made of aluminum.

[0028] The second electrical connection terminal2 comprises a second tab21 extending protruding between a second edge22 for joining with a second face24 of the electrochemical cell10 opposite the first face14 and a second free end edge23 opposite the second joining edge22. The second tab21 forms, for example, the negative electrical connection terminal of the electrochemical cell10. The second tab21 is, in one embodiment, made of copper, nickel or nickel-plated copper.

[0029] More generally, the first electrical connection terminal1 and the second electrical connection terminal2 are in the form of flexible tabs11,21 protruding from two opposite faces14,24 of the parallelepiped shape of the electrochemical cell10. The first tab11 and the second tab21 extend projecting into the plane of the electrochemical cell10.

[0030] The first tab11has a first surface and the second tab21has a second surface smaller than the first surface. In other words, the electrochemical cell10 comprises a first tab11and a second tab21forming two electrical connection terminals1,2of opposite polarity, the two tabs11,21having different surfaces. It follows that, when they are superimposed, the second tab21partially covers the first tab11. In other words, when the first tab11and the second tab21are superimposed, they partially, but not completely, overlap each other, so that there is at least one area of ​​the first tab11that is not covered by the second tab21.

[0031] In a non-limiting embodiment, the second tab 21 comprises, relative to the first tab 11, at least one first notch 25 (a cutout or indentation) such that the surface area of ​​the second tab 21 is smaller than the surface area of ​​the first tab 11. In other words, when comparing the second tab 21 to the first tab 11, the second tab 21 differs at least in that it comprises the first notch 25.

[0032] A non-overlapping (or non-overlapping) area of ​​the first tab 11 and the second tab 21 when they are superimposed comprises at least the first notch 25. Thus, when they are superimposed, the first tab 11 and the second tab 21 do not overlap at least at the level of the first notch 25 provided in the second tab 21.

[0033] The first notch25 is, in one embodiment, made on a first edge connecting the second free end edge23 to the second joining edge22 of the second tab21. This first notch25 extends at least partially over this first edge. Starting from the elongated shape of the tabs11,21, such a first notch25 reduces the length, measured in a direction parallel to the second joining edge22, of the second tab21 compared to that of the first tab11. The notch25 may be of any suitable shape such as rectangular, square, circular, triangular, oval or polygonal.

[0034] In a non-limiting embodiment illustrated by Figures 1-3, the second tab 21 comprises a first notch 25 and a second notch 26 substantially symmetrical with respect to a plane substantially perpendicular to the second junction edge 22. A symmetry of the second tab 21 with respect to said plane makes it easier to arrange the electrochemical cell 10 in either direction for its electrical connection with the neighboring electrochemical cell 10.

[0035] Referring to the, there is shown a part of a device 30, in particular a battery module 30, a battery pack 30 incorporating a plurality of battery modules, or an electric battery 30 comprising a plurality of electrochemical cells 10 arranged in a row (one next to the other in a connection direction) and whose tabs 11, 21 are electrically connected to each other by means of electrical connection bars 31. The electrochemical cells 10 of the battery module 30 or of the battery 30 can be connected to each other in series when the second tabs 21 of these cells 10 are of the same polarity or in parallel when the second tabs 21 of two successive cells 10 are of opposite polarity. In a series (respectively, parallel) connection of cells10, the polarities of the connection terminals1,2 arranged on the displayed side of the battery module30 or the electric battery30 are alternated (respectively, identical).In other words, the electrochemical cells are juxtaposed head to tail (respectively, parallel in the same direction or oriented identically), each pair of tabs11,21 contiguous on the same side of the battery module30 or electric battery30 belonging to two adjacent electrochemical cells having opposite polarities (respectively, identical polarities). In a battery module30 or in an electric battery30, several stacked or juxtaposed rows of electrochemical cells can, of course, be envisaged.

[0036] In one embodiment, the battery module 30 comprises housings or, more generally, mechanical assembly means intended to receive the electrochemical cells 10, these means being arranged to assemble the electrochemical cells 10 so that their electrical connection terminals 1, 2 can be electrically connected to each other in a series or parallel assembly using the electrical connection bars 31 by laser welding. In an electric battery 30, the cells 10 can, furthermore, be directly arranged in a support structure (a housing in the case of a PTC battery or the chassis of the vehicle in the case of a CTC battery arranged to house the electrochemical cells 10).

[0037] The electrical connection bar 31 comprises an elongated body made of an electrically conductive material (in particular, copper, aluminum or an alloy thereof) which extends between two adjacent electrochemical cells 10. The electrical connection bar 31 is, in one embodiment, flat in shape. Each electrical connection bar 31 makes it possible to bring the tabs 11, 21 of two successive cells of the battery module 30 or the electric battery 30 into electrical contact. For this, as illustrated by the , a first tab 11 of a first electrochemical cell 10 is folded onto the electrical connection bar 32 and a second tab 21 of a second neighboring electrochemical cell 10 is folded onto the first tab 11 of the first electrochemical cell 10 (step 51 on the ).Due to the difference between the surface area of ​​the first tab11 and the second tab21, there is a non-overlapping area between the two folded tabs11,21 (i.e., an area where the two surfaces do not overlap) corresponding to the first notch25 and / or the second notch26. More generally, the second tab21 partially covers the first tab11. More generally, since the surface area of ​​a first tab11 of a first electrochemical cell10 is greater than the surface area of ​​a second tab21 of a neighboring second electrochemical cell10, there is an area of ​​the first tab11 of the first electrochemical cell10 not covered by the second tab21 or which does not overlap the second tab21 of the neighboring second electrochemical cell.

[0038] A first bead32 (a point or a line) of laser welding is applied (step52 on the) in said non-overlapping zone of the first tab11 to weld this first tab11 to the electrical connection bar31.

[0039] The first tab11 of the first electrochemical cell10 is made of a first material comprising a first metal. The electrical connection bar31 is made of a second material comprising the first metal. In other words, the first tab11 and the electrical connection bar31 have a metal in common or both contain the same metal in their composition. This common metal advantageously ensures better compatibility between the material of the first tab11 and the material of the electrical connection bar31, leading to better structural integrity of the weld. This advantageously results in a reduction in the risks of cracking or weld defects and, consequently, a more robust and reliable first weld bead32.

[0040] In one embodiment, the common metal is predominant in the material of the first tab11 and in the material of the electrical connection bar31. The term "predominant metal in a material" means a compound that represents the largest amount by weight among the compounds of the material, in other words the compound constituting the main or most abundant component of the material in question. For example, the first tab11 and the electrical connection bar31 are based on aluminum or copper with, respectively, a first purity level and a second purity level that are different.In this case, the tab11 and the electrical connection bar31 have similar melting and thermal expansion properties, promoting the creation of a first laser weld bead32 that is robust, reliable and without the risk of welding defects and / or cracking that may occur when welding elements with different melting and / or thermal expansion properties.

[0041] Advantageously, a predominant common metal in the material of the tab11 and in the material of the electrical connection bar31 makes it possible to produce a homogeneous and solid weld capable of withstanding the vibrations of the motor vehicle. This advantageously results in a stable and solid mechanical connection between the first tab11 and the electrical connection bar31. The application of the first welding bead32 with a suitable laser power for welding the first tab11 to the electrical connection bar31 makes it possible, compared to welding both the first tab11, the second tab21 and the electrical connection bar31, to assemble them efficiently without the risk of creating a possible mixture of different materials.

[0042] More generally, the application of a first weld bead 32 in the non-overlapping zone of the first tab 11 to fix it to the electrical connection bar 31 provides mechanical stability to the connection between the electrochemical cells and the electrical connection bars 31, in particular in the face of vehicle vibrations. Since these are two metal elements, such welding, of course, also allows an electrical connection between the first tab 11 and the electrical connection bar 31.

[0043] A second laser weld bead33 is applied (step53on) to the second tab21 to weld it to the first tab11 in an overlapping area between the two tabs11,21.

[0044] It should be noted that a weld of the first tab 11 to the electrical bonding bar 31 and of the second tab 21 to the first tab 11 does not require as much depth or, equivalently, weld energy as for welding both the second tab 21, the first tab 11 and the electrical bonding bar 31. An input of too much energy to the weld can, therefore, be avoided.

[0045] Advantageously, the embodiments presented above make it possible to avoid an intermetallic mixture likely to occur during welding of both the second tab 21, the first tab 11 and the electrical connection bar 31 and which may compromise the quality of the electrical and mechanical connection between the electrochemical cells 10.

[0046] A first weld bead32 from the first tab11 to the electrical connection bar31 and a second weld bead33 from the second tab21 to the first tab11 allow the electrochemical cells10 to be securely fixed to the electrical connection bar31 and to be electrically connected. Furthermore, such a connection involving an overlap of the tabs11,21 allows the use of an electrical connection bar31 of smaller width, this width being measured in a direction perpendicular to the two adjacent cells10. The need for an electrical connection bar31 wide enough to receive on each side and without overlapping the tabs11,21 is, advantageously, no longer required. This results in a smaller footprint in the battery modules30 or in the electric batteries30 so that an increase in the number of electrochemical cells10 per battery module can be considered to improve the overall power of the vehicle.

[0047] In view of the above, an electrical connection between two adjacent electrochemical cells10 in a battery module30 or in an electric battery30 comprises a step of bending51 the first tab11 of the first electrochemical cell10 onto the electrical connection bar31 and the second tab21 of the second electrochemical cell10 onto the first tab11 of the first electrochemical cell. A first laser welding bead32 is then applied (step52) in a non-overlapping area of ​​the first tab11 between the two tabs11,21 (corresponding to the first notch25 and / or the second notch26) so as to weld the first tab11 to the electrical connection bar31. The first tab11 and the electrical connection bar31 both comprise the same metal, preferably predominant, in their composition.A second weld bead 33 is also applied (step 53) in an overlapping area between the two tabs 11, 21 so as to weld the second tab 21 to the first tab 11.

Claims

Battery module (30) comprising at least:- a first electrochemical cell (10) and a second electrochemical cell (10) each integrating a stack of electrodes separated from each other by a porous separator film, a first electrical connection terminal (1), a second electrical connection terminal (2) of polarity opposite to the first electrical connection terminal (1), the first electrical connection terminal (1) integrating a first tab (11) extending in projection between a first edge (12) joining with a first face (14) of the electrochemical cell (10) and a first free end edge (13) opposite the first joining edge (12);the second electrical connection terminal (2) incorporating a second tab (21) extending projecting between a second edge (22) joining with a second face (24) of the electrochemical cell (10) opposite the first face (14) and a second free end edge (23) opposite the second joining edge (22); the first tab (11) having a first surface and the second tab (21) having a second surface smaller than the first surface, the second tab (21) comprising, relative to the first tab (11), at least a first notch (25);- an electrical connection bar (31) electrically connecting the first electrochemical cell and the second electrochemical cell (10), the first tab (11) of the first electrochemical cell (10) being folded onto the electrical connection bar (31), the second tab (21) of the second electrochemical cell (10) being folded onto the first tab (11) of the first electrochemical cell; the battery module (30) being characterized in that it further comprises - a first laser welding bead (32) in an area of ​​said first tab (11) of the first electrochemical cell (10) not covered by said second tab (21) of the second electrochemical cell (10) corresponding to the first notch (25) of this second tab (21) of the second electrochemical cell (10), for welding said first tab (11) of the first electrochemical cell (10) to the electrical connection bar (31).; Battery module (30) according to the preceding claim, characterized in that the first tab (11) of the first electrochemical cell (10) is made of a first material comprising a first metal, the electrical connection bar (31) being made of a second material comprising the first metal. Battery module (30) according to the preceding claim, characterized in that the first metal is predominant in the first material and in the second material. Battery module (30) according to any one of the preceding claims, characterized in that it further comprises a second laser welding bead (33) in an overlapping area between said first tab (11) of the first electrochemical cell (10) and said second tab (21) of the second electrochemical cell (10) for welding the second tab (21) of the second electrochemical cell (10) to the first tab (11) of the first electrochemical cell (10). Battery module (30) according to any one of the preceding claims, characterized in that the first notch (25) is made on a first edge connecting the second free end edge (23) to the second joining edge (22) of the second tab (21). Battery module (30) according to any one of the preceding claims, characterized in that the second tab (21) of the second electrochemical cell (10) comprises, with respect to the first tab (11) of the second electrochemical cell (10), at least one second notch (26) substantially symmetrical to the first notch (25) with respect to a plane substantially perpendicular to the second edge (22) of junction of the second tab (21) of the second electrochemical cell (10) with said second face (24) of the second electrochemical cell (10). Battery module (30) according to any one of the preceding claims, characterized in that the stack of electrodes is arranged in a flexible bag, the cell further comprising an electrolyte in the bag. A battery pack incorporating a plurality of battery modules (30) according to any preceding claim. Electric battery (30) comprising at least:- a first electrochemical cell (10) and a second electrochemical cell (10) each integrating a stack of electrodes separated from each other by a porous separator film, a first electrical connection terminal (1), a second electrical connection terminal (2) of polarity opposite to the first electrical connection terminal (1), the first electrical connection terminal (1) integrating a first tab (11) extending in projection between a first edge (12) joining with a first face (14) of the electrochemical cell (10) and a first free end edge (13) opposite the first joining edge (12);the second electrical connection terminal (2) incorporating a second tab (21) extending projecting between a second edge (22) joining with a second face (24) of the electrochemical cell (10) opposite the first face (14) and a second free end edge (23) opposite the second joining edge (22); the first tab (11) having a first surface and the second tab (21) having a second surface smaller than the first surface, the second tab (21) comprising, relative to the first tab (11), at least a first notch (25);- an electrical connection bar (31) electrically connecting the first electrochemical cell and the second electrochemical cell (10), the first tab (11) of the first electrochemical cell (10) being folded onto the electrical connection bar (31), the second tab (21) of the second electrochemical cell (10) being folded onto the first tab (11) of the first electrochemical cell; the electric battery (30) being characterized in that it further comprises - a first laser welding bead (32) in an area of ​​said first tab (11) of the first electrochemical cell (10) not covered by said second tab (21) of the second electrochemical cell (10) corresponding to the first notch (25) of this second tab (21) of the second electrochemical cell (10), for welding said first tab (11) of the first electrochemical cell (10) to the electrical connection bar (31).; Electric battery (30) according to the preceding claim, characterized in that the first tab (11) of the first electrochemical cell (10) is made of a first material comprising a first metal, the electrical connection bar (31) being made of a second material comprising the first metal. Electric battery (30) according to the preceding claim, characterized in that the first metal is predominant in the first material and in the second material. Electric battery (30) according to any one of claims 9 to 11, characterized in that it further comprises a second laser welding bead (33) in an overlapping zone between said first tab (11) of the first electrochemical cell (10) and said second tab (21) of the second electrochemical cell (10) for welding the second tab (21) of the second electrochemical cell (10) to the first tab (11) of the first electrochemical cell (10). Electric battery (30) according to any one of claims 9 to 12, characterized in that the first notch (25) is made on a first edge connecting the second edge (23) of the free end to the second edge (22) of the second tab (21). Electric battery (30) according to any one of claims 9 to 13, characterized in that the second tab (21) of the second electrochemical cell (10) comprises, with respect to the first tab (11) of the second electrochemical cell (10), at least one second notch (26) substantially symmetrical to the first notch (25) with respect to a plane substantially perpendicular to the second edge (22) of junction of the second tab (21) of the second electrochemical cell (10) with said second face (24) of the second electrochemical cell (10). Electric battery (30) according to any one of claims 9 to 14, characterized in that the stack of electrodes is arranged in a flexible bag, the cell further comprising an electrolyte in the bag. A method of electrical connection between a first electrochemical cell (10) and a second electrochemical cell (10) in a battery module (30) according to any one of claims 1 to 7, in a battery pack according to claim 8, or in an electric battery (30) according to any one of claims 9 to 15, comprising the following steps:- folding (51) the first tab (11) of the first electrochemical cell (10) onto an electrical connection bar (31) and the second tab (21) of the second electrochemical cell (10) onto the first tab (11) of the first electrochemical cell (10);- applying (52) a first laser welding bead (32) in an area of ​​said first tab (11) of the first electrochemical cell (10) not covered by said second tab (21) of the second electrochemical cell (10) corresponding to the first notch (25) of this second tab (21) of the second electrochemical cell (10), to weld said first tab (11) of the first electrochemical cell (10) to the electrical connection bar (31);- applying (53) a second laser welding bead (33) in an overlapping area between said first tab (11) of the first electrochemical cell (10) and said second tab (21) of the second electrochemical cell (10) to weld the second tab (21) of the second electrochemical cell (10) to the first tab (11) of the first electrochemical cell (10).;

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