Electric battery module including an optimized heating device

Abstract

The invention relates to an electric battery module comprising at least two electrochemical cells (2), each comprising a flexible pouch (3) surrounding a stack of electrodes (12), said pouch (3) being made in two parts. According to the invention, the module comprises a heating device including an electric current source and a heating wire (15) disposed inside each pouch between the two parts, each heating wire (15) being connected to the current source, which can be activated at any time by a control element to supply electric current to each heating wire (15) placed inside a pouch and thus raise the temperature of the thermochemical cells (2) of said module (1). Figure for the abstract: Figure 4

Description

Title of the invention: Electric battery module comprising an optimized heating device

[0001] The present invention relates to an electric battery module comprising an optimized heating device.

[0002] Lithium-ion technology cells, in certain use cases, particularly for hybrid and plug-in hybrid vehicles, require heating to optimize their operating performance. This heating can be required during the battery charging or discharging phase.

[0003] Currently, heating mats are used to achieve this temperature increase. These heating mats are positioned against the module containing the cells. However, in practice, it has been observed that these heating mats, positioned in this way, do not distribute heat evenly across the cells. Furthermore, these heating mats constitute a thermal resistance during the cooling phase.

[0004] An electric battery module according to the invention has a heating device arranged judiciously within said module to overcome the disadvantages noted in the prior art.

[0005] The invention relates to an electric battery module comprising at least two electrochemical cells, each having a flexible pouch surrounding a stack of electrodes, said pouch being made in two parts.

[0006] According to the invention, said module comprises a heating device including an electrical current source and a heating wire disposed inside each pouch between the two parts. Each heating wire is connected to the current source, which can be activated at any time by a control element to supply electrical current to the heating wire located inside a pouch and thus raise the temperature of the thermochemical cells of said module. The cells involved in an electric battery module according to the invention are also called "pouch" cells because of their particular pouch or sachet shape. The distinctive feature of a heating device for an electric battery module according to the invention is that it ensures heating of each electrochemical cell from within each of the electrochemical cells composing it.Indeed, a heating wire is placed inside each electrochemical cell to allow for thorough heating of each cell. As a result, the cells are heated in an optimized manner, minimizing heat loss. Depending on... Depending on the path taken by the heating wire inside each cell, the cell can be heated homogeneously, while still allowing for the possibility of preferentially heating certain areas of the cell. The heating wire is positioned between the two halves of each cell's pouch before the two halves are assembled to form the pouch. Preferably, the two pouch halves are joined together by heat sealing. The heating wire is very compact and therefore does not alter the dimensions of the electrochemical cell or encroach on the space reserved for the electrodes. Advantageously, the electrochemical cells used in the battery module are lithium-ion cells.The heating wire placed inside each cell allows for rapid heating of the cell, thereby improving the performance of the electric battery module during certain phases of vehicle operation. Each heating wire within the electrochemical cell's casing can, for example, form an open or closed loop inside that casing. The control element could be, for example, an onboard computer in the vehicle with an algorithm designed to manage the different heating phases of the electric battery module.

[0007] According to one possible feature of the invention, the heating wire of each cell is placed around the electrodes located inside said cell. In this way, the heating wire will never be in direct contact with the electrodes and therefore does not risk damaging said electrodes through direct heating. Moreover, if this heating wire were in direct contact with these electrodes, it would inevitably create a temperature gradient at the electrodes, which would not promote homogeneous operation of the electric battery module.

[0008] According to one possible feature of the invention, the two parts of a pouch each comprise a recess surrounded by a flat edge, said two parts being arranged relative to each other such that the two flat edges are in contact with each other and the two recesses complement each other to delimit an internal space in which the electrodes are placed, the heating wire being inserted between the two flat edges of said parts. With such a configuration, the heating wire will be held in position between the two flat edges of the two parts forming the pouch, since said two flat edges will be heat-sealed to each other. The heating wire will thus have no chance of moving within the pouch to come into the internal space delimited by the two recesses.

[0009] According to one possible feature of the invention, the recess in each part of a pouch has a rectangular outline, the flat edge surrounding said recess having the shape of a closed rectangular frame, the heating wire running along the two rectangular frames in contact with each other. In other words, the heating wire is trapped between the two flat frames in contact with each other, and will extend at least partially along these two flat frames.

[0010] According to one possible feature of the invention, the heating wire forms a rectangular wire inside a pouch, having straight segments. In this configuration, the heating wire extends over almost the entire length of the flat frames in contact with each other. The longer the heating wire is within the pouch, the more efficient and homogeneous the heating of said pouch will be.

[0011] According to one possible feature of the invention, two ends of the heating wire of each electrochemical cell emerge from the pouch, an electrical connector base linking the two ends of the heating wire being attached to said pouch, the electrical source being electrically connected to the two emerging ends of the heating wire of each electrochemical cell. The term "ends" is used to represent the incoming and outgoing portions of the heating wire in the pouch, these two ends being able to extend outside said pouch to form an electrical circuit.

[0012] According to one possible feature of the invention, the electrical connector base and the two ends of the heating wire are folded against an external surface of one of the two parts of the pouch. In this way, such a configuration eliminates protruding parts of the electrical battery module that could be bent and possibly break during handling or upon contact with an external element. Likewise, these protruding parts must be eliminated because they could injure a person.

[0013] According to one possible feature of the invention, the electrical connector base is attached to the pouch by welding using a polymer strip. In this way, the electrical connector base is securely fixed to the pouch without risk of movement along it. Similarly, such welding eliminates the need for other fastening methods such as screws or rivets, which could significantly increase the weight of an electric battery module according to the invention.

[0014] According to one possible feature of the invention, the electric battery module comprises an upper casing forming a cover and a lower casing forming a receptacle housing the electrochemical cells, the power source being a power supply unit that is attached to an external surface of the upper casing. By closing the upper casing onto the lower casing containing the electrochemical cells, the power supply unit is located outside the casing housing the electrochemical cells, and closes the electrical circuit that powers the heating wires of the electrochemical cell pouches.

[0015] According to a possible feature of the invention, the electric battery module comprises two terminal blocks in the form of two parallel rods, said two terminal blocks passing through two openings in the upper casing as they emerge from said upper casing when the casing has been formed.

[0016] An electric battery module according to the invention has several advantages: - The heating device is easy to implement because it does not require modification of the electrochemical cells, -The implementation of the heating system is of low cost, -The implementation of the heating system is a natural part of the usual cell manufacturing process, -Heating is carried out as close as possible to the cell chemistry, -Avoids the implementation of all thermal resistances related to the construction of the module.

[0017] A detailed description of a preferred embodiment of an electric battery module according to the invention is given below, with reference to the following figures:

[0018] [Fig. 1] [Fig. 1] is a perspective view of part of a pouch of an electrochemical cell of an electric battery module according to the invention

[0019] [Fig.2] Fig.2 is a perspective view of part of the sleeve of Fig.1 equipped with a heating wire and a connector,

[0020] [Fig.3] The [Fig.3] is a perspective view of an area of ​​the part of the pouch of the [Fig.2],

[0021] [Fig.4] [Fig.4] is a perspective view of part of the sleeve of [Fig.2] in which a block of electrodes was placed,

[0022] [Fig.5] Fig.5 is a perspective view of an electrochemical cell of an electric battery module according to the invention,

[0023] [Fig.6] [Fig.6] is a perspective view of the area of ​​[Fig.3], with the ends of the heating wire and the connector folded against an external surface of part of the pouch,

[0024] [Fig.7] Fig.7 is a perspective view of an electric battery module according to the invention comprising several parallel electrochemical cells,

[0025] [Fig.8] [Fig.8] is a view of the electric battery module of [Fig.7], in which two terminal blocks have been mounted,

[0026] [Fig.9] Fig.9 is a perspective view of a housing containing a module of electric battery according to the invention, from which two boniers emerge,

[0027] [Fig. 10] The [Fig. 10] is an exploded perspective view of the housing of the [Fig. 9],

[0028] [Fig. 11] The [Fig. 11] is a partial front view of part of a device of heating of an electric battery module according to the invention, showing an electrical circuit out of the electrochemical cells.

[0029] With reference to Figures 7, 8, 9, and 10, an electric battery module 1 according to the invention comprises a plurality of electrochemical cells 2 arranged parallel to one another, said cells 2 being, for example, of the Lithium-ion type. Within this module 1, the cells 2 can be mounted either in series or in parallel, or in a combination of these two types of arrangement. The electrochemical cells 2 of an electric battery module 1 according to the invention are of the "pouch" type, that is to say, each is delimited by a pouch 3.

[0030] With reference to Figures 1, 2, 4, 5, and 11, the pouch 3 of each electrochemical cell 2 of an electric battery module 1 according to the invention is made of two sections 4, 5 which are heat-welded to each other. Each of the sections 4, 5 of the pouch 3 has a rectangular outline and a central rectangular recess 6 surrounded by a rectangular flat frame 7. This flat frame 7 comprises four segments 8, 9, 10, 11, two of which 8, 9 are short and parallel, and two others 10, 11 are elongated and parallel. The two short segments 8, 9 have the same width, and the two long segments have the same width. These four segments 8, 9, 10, 11 are in the same plane and completely surround the central recess 6. The rectangular recess 6 is placed in the corresponding section 4, 5 so that a longitudinal axis of said recess 6 is parallel to a longitudinal axis of said section 4, 5.When pocket 3 of the electrochemical cell is mounted: -the two flat frames 7 of the two sections 4, 5 establish a surface contact between them, at the level of which the heat weld is carried out, -the central recesses 6 of the two sections 4, 5 complement each other to delimit an internal space in pocket 3. .

[0031] Referring to [Fig. 4], this internal space is used to house a stack of electrodes 12 having a general rectangular parallelepiped shape, said stack occupying the entirety of this internal space. At the two ends of this stack of electrodes 12, two collectors 13, 14 emerge, to which two conductive tabs 30, 31 are welded, said two ends being considered along a longitudinal axis of the stack 12.

[0032] With reference to Figures 2, 3, and 4, an electric battery module 1 according to the invention has a heating device comprising, in each electrochemical cell 2 of the component, a heating wire 15. Within each electrochemical cell 2, the heating wire 15 comprises an inlet end 16 and an outlet end 17 emerging from the pouch 3, said wire 15 forming a rectangular loop inside the pouch 3, between these two inlet and outlet ends 16, 17. This rectangular loop has dimensions that are analogous to those of the planar frames 7 of the two sections 4, 5 of the pouch 3, such that it extends along said planar frame 7. Initially, the stack of electrodes 12 is placed in the hollow 6 of a first section 4, 5 of the pouch 3 and the heating wire 15 is placed against the flat frame 7 of this same first section 4, 5, before a second section 4, 5 is heat-welded to said first section 4, 5 to form the pouch 3. The electrical wire 15 is thus trapped between the two flat frames 7 of the two sections 4, 5 which are in contact with each other.

[0033] Referring to [Fig. 5], once pocket 3 has been formed: -the two conductive tabs 30, 31 emerge from the two short sides of the pouch 3, -the two ends 16, 17 of the heating wire 15 emerge from one of the two large sides 10, 1 of said pouch 3.

[0034] The two sections 4, 5 of the pouch 3 containing the stack of electrodes 12 and the heating wire 15 are heat-welded at the conductive tabs 30, 31 which emerge from the two short sides of the pouch 3, by means of a polymer strip 18 placed against said conductive tabs 30, 31, this polymer strip 18 also ensuring a good seal of the pouch 3.

[0035] With reference to figures 2, 3, 4 and 5, a connector base 19 is fixed to the pouch 3 by passing through the two ends 16, 17 of the heating wire 15.

[0036] With reference to [Fig.6], in order to eliminate any unnecessary protrusion of the pouch 3, the connector base 15 and the two ends 16, 17 of the heating wire 15 are folded against an external surface of one of the two sections 4, 5 forming said pouch 3.

[0037] Referring to [Fig. 1 1], when the electrochemical cells 2 are arranged parallel to each other to form the electric battery module 2, a single heating wire 15 passes through all the thermochemical cells 2. Indeed, the arrangement of the heating device in the electric battery module 1 is such that: -the output end 17 of the heating wire 15 of the first electrochemical cell 2 is extended until it forms the input end 16 of the heating wire 15 of the second electrochemical cell 2 placed right next to it, -the output end of the heating wire 15 of the second electrochemical cell 2 is extended until it forms the input end 16 of the heating wire 15 of the third electrochemical cell 2 placed right next to it, and so on.

[0038] In this way, the heating wire 15 has overall an input end placed at the input of the first electrochemical cell 2, and an output end placed at the output of the last electrochemical cell 2, said cells 2 composing the module 1 of the electric battery according to the invention.

[0039] Referring to [Fig. 8], two bomies 19, 20 in the form of two parallel cylindrical rods are placed at the level of the first electrochemical cell 2 and the last electrochemical cell 2 of the module 1 of the electric battery according to the invention.

[0040] Referring to Figures 9 and 10, the stack of electrochemical cells 2 is placed in a housing 21 comprising an upper casing 22 forming a lid, and a lower casing 23 forming a receptacle for housing said electrochemical cells 2. The upper casing 22 is a flat rectangular plate having three openings 24, 25, 26, and the lower casing 23 is delimited by four walls 32, 33, 34, 35 forming a rectangle and by a base 36 on which said four walls 32, 33, 34, 35 rest. The four walls 32, 33, 34, 35 of the lower casing 23 extend onto the base 36, each being perpendicular to said base 36. The stack of electrochemical cells 2, equipped with their heating wire 15, is placed in the lower casing 23, then the upper casing 22 is closed on the lower casing 23 to form the housing 21 containing the electrochemical cells 2.The two housings 19, 20 pass through two openings 24, 25 of the upper casing 22, emerging from it towards the outside of the housing 21, an insulator 37 being inserted in the third opening 26 of said upper casing 22. A power supply intended to power the heating wire 15 to heat all the electrochemical cells 2 housed in the casing 21, is in the form of a power supply unit 38 which is attached to an external surface of the upper casing 22. This power supply 21 can be triggered at any time by an on-board computer in a vehicle, as soon as there is a need to heat the electrochemical cells 2 of the electric battery module 1.

Claims

Claims

1. Electric battery module (1) comprising at least two electrochemical cells (2) each comprising a flexible pouch (3) surrounding a stack of electrodes (12), said pouch (3) being made in two parts (4, 5), said module (1) comprising a heating device comprising an electric current source (21) and a heating wire (15) arranged inside each pouch (3) between the two parts (4, 5), each heating wire (15) being connected to the current source (21), which can be activated at any time by a control element to supply electric current to the heating wire (15) placed inside a pouch (3) and thus raise the temperature of the electrochemical cells (2) of said module (1), the heating wire (15) of each cell (2) being placed around the electrodes (12) placed inside said cell (2)., the two parts (4, 5) of a pouch (3) each comprising a recess (6) surrounded by a flat edge (7), and being arranged relative to each other so that the two flat edges (7) are in contact with each other and the two recesses (6) complement each other to delimit an internal space in which the electrodes (12) are placed, the heating wire (15) being inserted between the two flat edges (7) of said parts (4, 5), characterized in that two ends (16, 17) of the heating wire (15) of each electrochemical cell (2) emerge from the pouch (3), and in that an electrical connector base (19) connects the two ends (16, 17) of the heating wire (15) by being fixed to said pouch (3), the electrical source (21) being electrically connected to the two emerging ends (16, 17) of the heating wire (15) of each cell electrochemical (2).

2. Electric battery module according to claim 1, characterized in that the recess (6) of each of the parts (4, 5) of a pocket (3) has a rectangular outline, and in that the flat edge (7) surrounding said recess has the shape of a closed rectangular frame (8, 9, 10, 11), the heating wire (15) running along the two rectangular frames (8, 9, 10, 11) in contact with each other.

3. Electric battery module according to claim 2, characterized in that the heating wire (15) forms a wire rectangle inside the pocket (3), having rectilinear segments.

4. Electric battery module according to any one of claims 1 to 3, characterized in that the electrical connector base (19) and the two ends (16, 17) of the heating wire (15) are folded against an external surface of one of the two parts (4, 5) of the pocket (3).

5. Electric battery module according to any one of claims 1 to 4, characterized in that the electrical connector base (19) is fixed to the pocket (3) by welding using a polymer strip.

6. Electric battery module according to any one of claims 1 to 5, characterized in that it comprises an upper casing (22) forming a cover and a lower casing (23) forming a receptacle housing the electrochemical cells (2), and in that the electrical source (21) is an electrical power supply box which is secured to an external surface of the upper casing (22).

7. Electric battery module according to claim 6, characterized in that it comprises two terminals (19, 20) in the form of two parallel rods, and in that said two terminals (19, 20) pass through two openings (25, 26) of the upper casing (22) emerging from said upper casing (22), when the box has been formed.

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