Electric battery module comprising an optimised 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 an electrode stack (12), the pouch (3) being made in two portions. According to the invention, the module comprises a heating device including an electric current source and a heating wire (15) arranged inside each pouch between the two portions, each heating wire (15) being connected to the current source, which can be activated at any time by a control element in order to supply electric current to each heating wire (15) placed inside a pouch and thus to raise the temperature of the thermochemical cells (2) of the module (1).

Description

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 need to be heated up in certain use cases, particularly for hybrid and plug-in hybrid vehicles, to optimize their operating performance. The temperature increase may 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 said heating mats positioned in this way do not diffuse uniform heating of the cells. In addition, these heating mats constitute a thermal resistance during the cooling phase.

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

[0005] The subject of the invention is an electric battery module comprising at least two electrochemical cells each comprising 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 comprising an electric current source and a heating wire arranged inside each pouch between the two parts, each heating wire being connected to the current source, which can be activated at any time by a control element to supply electric current to the heating wire placed 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 format in sachet or pouch. The particularity of a heating device of an electric battery module according to the invention is that it allows heating of each electrochemical cell from the inside of each of the electrochemical cells composing it. Indeed, a heating wire is placed inside each of the electrochemical cells to allow heating in depth of each of these cells. As a result, the heating of the cells is carried out in an optimized way by limiting heat losses. Depending on the path taken by the heating wire inside each cell, the heating of said cell can be carried out in a homogeneous way, while not excluding the possibility of being able to heat in a preferential way certain zones of said cell.The heating wire is positioned between the two parts of the pouch of each cell before assembling said two parts to obtain the pouch. Preferably, the two parts of the pouch are fixed to each other by heat welding. The heating wire is very compact and will therefore not modify the dimensions of the electrochemical cell and will not encroach on the space reserved for the electrodes. Advantageously, the electrochemical cells involved in the electric battery module are lithium ion type cells. The heating wire placed inside each cell will allow said cell to be heated quickly in order to improve the performance of the electric battery module, during certain phases of use of a vehicle comprising such an electric battery module. Each heating wire placed in the pouch of the electrochemical cell can for example form an open or closed loop inside said pouch.The control element may, for example, be a computer embedded in the vehicle and having an algorithm designed to manage the different heating phases of the electric battery module.

[0007] According to a possible feature of the invention, the heating wire of each cell is placed around the electrodes placed 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 with direct heating. In addition, if this heating wire were in direct contact with these electrodes, it would inevitably create a temperature gradient at the level of these electrodes which would not promote homogeneous operation of the electric battery module.

[0008] According to a possible characteristic 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, so 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 and be placed in the internal space delimited by the two recesses.

[0009] According to a possible characteristic of the invention, the recess of each of the parts of a pocket 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 a possible characteristic of the invention, the heating wire forms a wire rectangle inside a pocket, having rectilinear segments. For 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 pocket, the more it will ensure efficient and uniform heating of said pocket.

[0011] According to a possible characteristic of the invention, two ends of the heating wire of each electrochemical cell emerge from the pouch, an electrical connector base connecting the two ends of the heating wire by being fixed 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 materialize the incoming and outgoing parts of the heating wire in the pouch, these two ends being able by elsewhere be extended outside said pocket to form an electrical circuit.

[0012] According to a 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 emerging parts of the electric battery module which would be likely to twist and possibly break during handling, or upon contact with an external element. Similarly, these emerging parts must be eliminated, as they could injure an individual.

[0013] According to a possible characteristic of the invention, the electrical connector base is fixed to the pouch by welding using a polymer strip. In this way, the electrical connector base is securely fixed to the pouch without the risk of moving along it. Similarly, such welding makes it possible to dispense with other fixing means such as, for example, screws or rivets, which would be likely to significantly increase the weight of an electric battery module according to the invention.

[0014] According to a possible characteristic 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 electrical source being an electrical power supply box which is secured to an external surface of the upper casing. By closing the upper casing on the lower casing containing the electrochemical cells, the electrical power supply box is outside the box housing the electrochemical cells, and closes the electrical circuit making it possible to power the heating wires of the pouches of the electrochemical cells.

[0015] According to a possible characteristic 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 and emerging from said upper casing when the housing 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 device is of reduced cost, -The implementation of the heating device naturally enters into the usual manufacturing process of the cells, -Heating is carried out as close as possible to the chemistry of the cell, -Avoids the implementation of all thermal resistances linked 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] Figure 1 is a perspective view of a portion of a pouch of an electrochemical cell of an electric battery module according to the invention

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

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

[0021] [Fig. 4] Figure 4 is a perspective view of the portion of the pouch of Figure 2 in which an electrode block has been placed,

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

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

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

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

[0026] [Fig. 9] Figure 9 is a perspective view of a case containing an electric battery module according to the invention, and from which two terminal blocks emerge,

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

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

[0029] Referring 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 each other, said cells 2 being able, for example, to be 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 that they are each delimited by a pocket 3.

[0030] Referring 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-sealed to each other. Each of the sections 4, 5 of the pouch 3 has a rectangular outline, and has a central recess 6 of rectangular shape and surrounded by a flat frame 7 of rectangular shape. This flat frame 7 comprises four segments 8, 9, 10, 11 of which two 8, 9 are short and parallel, and of which 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 inscribed 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 the electrochemical cell pocket 3 is mounted:. - the two flat frames 7 of the two sections 4, 5 establish a surface contact between them, at which the heat welding is carried out, - the central recesses 6 of the two sections 4, 5 complement each other to delimit an internal space in the pocket 3.

[0031] Referring to Figure 4, this internal space is used to house a stack of electrodes 12 having the general shape of a rectangular parallelepiped, 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] Referring 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 comprising it, a heating wire 15. Within each electrochemical cell 2, the heating wire 15 comprises an input end 16 and an output end 17 emerging from the pouch 3, said wire 15 forming a rectangular loop inside the pouch 3, between these two input and output ends 16, 17. This rectangular loop has dimensions which are similar to those of the flat frames 7 of the two sections 4, 5 of the pouch 3, so that it extends along said flat frame 7. Initially, the stack of electrodes 12 is placed in the recess 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 that a second section 4, 5 is heat-sealed to said first section 4, 5 to form the pocket 3.The electric 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 Figure 5, once the pouch 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 long sides 10, 11 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-sealed at the level of the conductive tabs 30, 31 which emerge from the two small sides of the pouch 3, by means of a polymer strip 18 placed against said tabs. conductive 30, 31, this polymer strip 18 also ensuring good sealing of the pocket 3.

[0035] Referring to Figures 2, 3, 4 and 5, a connector base 19 is fixed to the pocket 3 with the two ends 16, 17 of the heating wire 15 passing therethrough.

[0036] Referring to Figure 6, in order to remove any unnecessary protrusion from the pocket 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 pocket 3.

[0037] Referring to Figure 11, 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 to form 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 to form 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 generally has 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 making up the electric battery module 1 according to the invention.

[0039] Referring to Figure 8, two terminal blocks 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 electric battery module 1 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 cover, and a lower casing 23 forming a receptacle for housing said electrochemical cells 2. The upper casing 22 is a plate rectangular plane 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 bottom 36 on which rest said four walls 32, 33, 34, 35. The four walls 32, 33, 34, 35 of the lower casing 23 extend over the bottom 36 while each being perpendicular to said bottom 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 case 21 containing the electrochemical cells 2. The two terminal blocks 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 into the third opening 26 of said upper casing 22.An electrical power source intended to power the heating wire 15 to cause the heating of all the electrochemical cells 2 housed in the housing 21, is in the form of an electrical power supply box 38 which is secured to an external surface of the upper casing 22. This electrical power source 21 can be triggered at any time by an on-board computer in a vehicle, as soon as a need arises 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), characterized in that said module (1) comprises a heating device comprising an electric current source (21) and a heating wire (5) arranged inside each pouch (3) between the two parts (4, 5), and in that each heating wire (15) is 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 thermochemical cells (2) of said module (1).

2. Electric battery module according to claim 1, characterized in that the heating wire (15) of each cell (2) is placed around the electrodes (12) placed inside said cell (2).

3. Electric battery module according to claim 2, characterized in that the two parts (4, 5) of a pocket (3) each comprise a recess (6) surrounded by a flat edge (7), said two parts (4, 5) 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, and in that the heating wire (15) is inserted between the two flat edges (7) of said parts (4, 5).

4. Electric battery module according to claim 3, 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.

5. Electric battery module according to claim 4, characterized in that the heating wire (15) forms a wire rectangle inside the pocket (3), having rectilinear segments.

6. Electric battery module according to any one of claims 3 to 5, characterized in that two ends (16, 17) of the heating wire (15) of each electrochemical cell (2) emerge from the pocket (3), and in that that an electrical connector base (19) connects the two ends (16, 17) of the heating wire (15) by being fixed to said pocket (3), the electrical source (21) being electrically connected to the two emerging ends (16, 17) of the heating wire (15) of each electrochemical cell (2).

7. Electric battery module according to claim 6, 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).

8. Electric battery module according to any one of claims 5 or 6, characterized in that the electrical connector base (19) is fixed to the pocket (3) by welding using a polymer strip.

9. Electric battery module according to any one of claims 1 to 8, 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).

10. Electric battery module according to claim 9, characterized in that it comprises two terminal blocks (19, 20) in the form of two parallel rods, and in that said two terminal blocks (19, 20) pass through two openings (25, 26) of the upper casing (22) emerging from said upper casing (22), when the housing has been formed.

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