Method for manufacturing a sachet electrochemical cell

Abstract

A method for manufacturing a cell in a pouch comprising the following steps: - forming, in a multilayer film (20), a first cavity (11) and a second cavity (12), the first cavity and the second cavity having a common edge (13) incorporating a fold line (14) allowing the first cavity (11) to be folded over the second cavity (12) so as to form a pouch suitable for receiving a stack of electrodes; - forming a first semi-cylindrical channel (15) in the edge of the first cavity (11) and a second semi-cylindrical channel (16) in the edge of the second cavity (12) such that, when the first cavity (11) is folded over the second cavity (12), the second channel (16) forms with the first channel (15) a conduit (17) suitable for receiving a cable extending within said pouch. Figure for the abbreviation: Fig. 2

Description

Title of the invention: Method for manufacturing an electrochemical cell in a sachet

[0001] The present invention relates to the technical field of pouch electrochemical cells, also known as soft-shell electrochemical cells or "pouch cells" according to Anglo-Saxon terminology. In particular, the present invention relates to a method for manufacturing pouch electrochemical cells and the cells thus obtained.

[0002] In a manner known from the prior art, a Pouch type electrochemical cell comprises an outer envelope or pouch containing an alternating stack of negative and positive electrodes separated from each other by a porous separator film soaked in electrolyte.

[0003] The casing is most often formed by heat-sealing the edges of two multilayer films or strips, each having a thermoplastic layer on its facing inner surfaces. The casing is hermetically sealed so as to leave only a positive terminal and a negative terminal protruding, connected to the corresponding electrodes.

[0004] In order to reduce the edges to be heat-sealed and, consequently, improve the sealing of the casing, it is known that the casing is pre-formed in the form of a double sheet incorporating two identical cavities on either side of a fold line. When folded over each other, the two cavities together form a casing intended to receive the stack of electrodes and the electrolyte.

[0005] Real-time monitoring of the condition of a pouch-type cell in a battery module is crucial for various reasons, such as the safety, performance, and / or longevity of that cell. For this purpose, it is known to install sensors or probes directly on or near the pouch cells, such as temperature sensors, pressure sensors, electrochemical sensors, or gas or leak detectors.

[0006] However, a drawback of existing solutions is that the measurements taken lack relevance and do not accurately reflect the condition of Pouch-type cells. Furthermore, the particular design of these cells presents unique challenges in monitoring their condition and performance.

[0007] There is therefore a need to collect measurements as close as possible to the sachet cells for closer and more precise monitoring.

[0008] An object of the present invention is to propose methods for manufacturing cells in sachets allowing precise and continuous monitoring of the state of these cells, without compromising their integrity.

[0009] To this end, a method for manufacturing a sachet electrochemical cell is proposed firstly, comprising the following steps: - formation, in a multilayer film, of a first cavity and a second cavity substantially identical, the first cavity and the second cavity having a common edge incorporating a fold line allowing the first cavity to be folded over the second cavity so as to form a bag suitable for receiving a stack of electrodes; - formation of a first semi-cylindrical channel in the edge of the first cavity outside of said common edge, this first channel being communicative with the first cavity; - formation of a second semi-cylindrical channel substantially identical to the first channel in the edge of the second cavity outside said common edge so that, when the first cavity is folded over the second cavity along the folding line, the second channel is substantially opposite the first channel and forms with this first channel a conduit suitable for receiving a predefined cable extending into said bag; - arrangement of said stack of electrodes in the second cavity; - folding of the first cavity onto the second cavity; - arrangement of said cable in the conduit formed by the first and second cable trays; - fixing the edge of the first cavity to the edge of the second cavity outside of said common edge.

[0010] Various additional features may be provided, alone or in combination: - the first semi-cylindrical chute has a substantially semi-circular or substantially semi-elliptical cross-section; - the first semi-cylindrical channel is less deep than the first cavity; - the first cavity, the second cavity, the first semi-cylindrical chute and / or the second semi-cylindrical chute are formed by stamping, between a male mold and a female mold, of the multilayer film; - the first cavity, the second cavity, the first chute and the second chute are formed simultaneously; - the edge of the first cavity is fixed, outside of said common edge, to the edge of the second cavity by heat sealing.

[0011] Secondly, a sachet electrochemical cell is proposed that can be obtained by the manufacturing process described above.

[0012] Various additional features may be provided, alone or in combination: - the cable includes a temperature sensor, a pressure sensor, a gas detector, or an electrochemical sensor; - said cable includes a thermocouple cable; - the cable includes a thermoplastic coating at least on its external face intended to be in contact with the first cable tray and with the second cable tray.

[0013] Other features and advantages of the invention will become clearer and more concrete upon reading the following description of embodiments, which is made with reference to the accompanying drawings in which:

[0014] Figure [Fig.1] schematically illustrates steps in a process for manufacturing a sachet electrochemical cell according to various embodiments;

[0015] Figure [Fig.2] schematically illustrates preforming steps of a multilayer film for the manufacture of an electrochemical cell in a sachet according to various embodiments;

[0016] Figure [Fig.3] schematically illustrates the implementation of a manufacturing step of a sachet electrochemical cell according to various embodiments;

[0017] Figure [Fig.4] schematically illustrates a side view of a sachet electrochemical cell according to various embodiments.

[0018] With reference to the attached figures, a method 10 for manufacturing a sachet electrochemical cell includes a step 1 of forming, in a multilayer film 20, a first cavity 11 and a second cavity 12 substantially identical.

[0019] The first cavity 11 and the second cavity 12 have a common edge 13 incorporating a fold line 14 allowing, as illustrated in Figures 2 and 3, the first cavity 11 to be folded over the second cavity 12 so as to form a pouch 21 suitable for receiving a stack of electrodes. When folded over each other along the fold line 14, the two cavities 11, 12 together define or delimit a volume to house the stack of electrodes.

[0020] The first cavity 11 and the second cavity 12 are contiguous along a common edge 13, incorporating a fold line 14 allowing the cavities 11, 12 to be folded over each other. The edges of the two cavities 11, 12 align perfectly when these two cavities 11, 12 are folded over each other. These edges refer to the outer limits of the cavities 11, 12 (where they meet the plane of the multilayer film 20) or to the peripheral area immediately around the opening of the two cavities 11, 12.

[0021] The fold line 14 delimits the two cavities 11, 12, which are substantially symmetrical with respect to this fold line 14. The substantially rectangular profile of the cavities 11, 12 is for illustrative purposes only and is not intended to be limiting.

[0022] In one embodiment, the multilayer film 20 comprises, from the outside to the inside of the bag 21 formed by the two cavities 11, 12, an outer layer electrically insulating protective layer (e.g., plastic), metallic intermediate layer (in particular, aluminum or an aluminum-based alloy) and inner layer of thermoplastic material (e.g., polypropylene).

[0023] The process 10 for manufacturing the electrochemical cell further comprises a step 2 of forming a first semi-cylindrical channel 15 in the edge of the first cavity 11 outside the common edge 13. The first semi-cylindrical channel 15 communicates with the first cavity 11. The first semi-cylindrical channel 15 opens into the interior of the first cavity 11.

[0024] A step 3 is also provided for forming a second semi-cylindrical chute 16 substantially identical to the first semi-cylindrical chute 15 in the edge of the second cavity 12 outside the common edge 13 so that, when the first cavity 11 is folded down onto the second cavity 12 along the folding line 14, the second semi-cylindrical chute 16 is substantially opposite the first semi-cylindrical chute 15 and forms with this first semi-cylindrical chute 15 a conduit 17 suitable for receiving a predefined cable extending into the bag 21.

[0025] Advantageously, the two semi-cylindrical channels 15, 16 formed in the edges of the two cavities 11, 12 symmetrically with respect to the folding line 14 together form a conduit 17 for receiving a cable extending inside the electrochemical cell. The integration of a sensor inside the bagged electrochemical cell is thus possible without compromising its integrity, including its sealing. This conduit 17 allows the sensor to be integrated inside the bagged electrochemical cell without risk of swelling or an increase in its thickness.

[0026] In one embodiment, the first semi-cylindrical conduit 15 has a substantially semi-circular or substantially semi-elliptical cross-section. Advantageously, this results in a conduit 17 capable of tightly fitting a cable with a round or flattened cross-section (in particular, a ribbon cable). This results in a reduction of the risk of voids between the edges of the bag 21 and the outer surface of the cable.

[0027] The first semi-cylindrical chute 15 is preferably less deep than the first cavity 11. It follows advantageously that the two chutes 15,16 form a conduit 17 less wide (or less thick) than the bag electrochemical cell, without impacting the integrity of the latter.

[0028] The first cavity 11, the second cavity 12, the first semi-cylindrical chute 15 and / or the second semi-cylindrical chute 16 are, in one embodiment, formed by stamping, between a male mold and a female mold, of the 20 multilayer film. Such preforming allows for a high production rate.

[0029] For even faster preforming of the multilayer film 20, the first cavity 11, the second cavity 12, the first semi-cylindrical channel 15 and the second semi-cylindrical channel 16 can be formed simultaneously (or concomitantly) by stamping.

[0030] Following the preforming of the first cavity 11, the second cavity 12, the first semi-cylindrical channel 15, and / or the second semi-cylindrical channel 16, a stack of electrodes (not shown) is arranged (step 4 of arrangement in [Fig. 1]) in the second cavity 12. The first cavity 11 is then folded (folding step 5 illustrated by arrow 30 in [Fig. 3]) over the second cavity 12. The two cavities 11 and 12 are folded symmetrically onto each other, that is, folded or brought over each other so that they align symmetrically opposite each other around the folding line 14. This results in a sachet electrochemical cell in the form of a substantially parallelepiped-shaped envelope of low thickness.

[0031] A cable can be placed (step 6 in [Fig. 1]) in the conduit 17 formed by the first semi-cylindrical channel 15 and the second semi-cylindrical channel 16. This cable can, of course, be placed in the first or the second semi-cylindrical channel 15, 16 before the first cavity 11 is folded down onto the second cavity 12. This cable passes through the edge of the electrochemical cell so as to protrude on one side outside the bag 21, and on the other side inside the volume defined by the bag 21 in which the stack of electrodes is placed.

[0032] Various parameters of the bagged electrochemical cell can thus be measured, particularly during each charging or discharging of the bagged electrochemical cell. In one embodiment, the cable includes a temperature sensor, a pressure sensor, a gas detector, or an electrochemical sensor. In another embodiment, the cable includes a thermocouple cable enabling thermal monitoring of the bagged electrochemical cell.

[0033] The edge of the first cavity 11 is fixed (step 7 in [Fig. 1]) to the edge of the second cavity 12 outside the common edge 13. Heat sealing advantageously allows for rapid joining of the two facing edges and a hermetic closure of the bag 21. In one embodiment, the bag 21 is presented under two heated jaws of a heat-sealing device incorporating two recesses (or two channels) substantially identical to the channels 15, 16 forming the conduit 17.

[0034] The electrochemical cell in the bag is resealed, in particular by heat sealing, so that only the cable arranged in the conduit protrudes from the bag 21 17 and, of course, electrical terminations (not shown) connected to the oppositely polarized electrodes of the stack to form the terminals of the bag electrochemical cell. For the introduction of a liquid electrolyte into bag 21, part of the edge of bag 21 can be heat-sealed after filling.

[0035] In one embodiment, the cable comprises a thermoplastic coating (such as polypropylene or polyethylene) at least on its outer face intended to be in contact with the first semi-cylindrical chute 15 and with the second semi-cylindrical chute 16. This coating allows the cable to pass watertight through the edge of the bag 21.

[0036] This advantageously results in a sachet electrochemical cell whose operation can be monitored precisely and continuously, without compromising its integrity.

Claims

Demands

1. A method (10) for manufacturing a sachet electrochemical cell comprising the following steps: - forming (1), in a multilayer film (20), a first cavity (11) and a second cavity (12) substantially identical, the first cavity and the second cavity having a common edge (13) incorporating a fold line (14) allowing the first cavity (11) to be folded over the second cavity (12) so as to form a sachet (21) suitable for receiving a stack of electrodes; - forming (2) a first semi-cylindrical channel (15) in the edge of the first cavity (11) outside of said common edge (13), this first channel (15) being communicative with the first cavity (11);- formation (3) of a second semi-cylindrical channel (16) substantially identical to the first channel (15) in the edge of the second cavity (12) outside said edge (13) in common so that, when the first cavity (11) is folded over the second cavity (12) along the folding line (14), the second channel (16) is substantially opposite the first channel (15) and forms with this first channel (15) a conduit (17) suitable for receiving a predefined cable extending in said bag (21); - arrangement (4) of said stack of electrodes in the second cavity (12); - folding (5) of the first cavity (11) over the second cavity (12); - arrangement (6) of said cable in the conduit (17) formed by the first channel (15) and the second channel (16); - fixing (7) of the edge of the first cavity (11) to the edge of the second cavity (12) outside of said edge (13) in common.;

2. A manufacturing method according to the preceding claim, characterized in that the first semi-cylindrical chute (15) has a substantially semi-circular or substantially semi-elliptical cross-section.

3. A manufacturing method according to claim 1 or 2, characterized in that the first semi-cylindrical chute (15) is less deep than the first cavity (11).

4. A manufacturing method according to any one of the preceding claims, characterized in that the first cavity (11), the second cavity (12), first semi-cylindrical chute (15) and / or second semi-cylindrical chute (16) are formed by stamping, between a male mold and a female mold, of the multilayer film (20).

5. A manufacturing method according to the preceding claim, characterized in that the first cavity (11), the second cavity (12), the first chute (15) and the second chute (16) are formed simultaneously.

6. A manufacturing method according to any one of the preceding claims, characterized in that the edge of the first cavity (11) is fixed, outside of said edge (13) in common, to the edge of the second cavity (12) by heat sealing.

7. Bag electrochemical cell capable of being obtained by the manufacturing process of any one of the preceding claims.

8. Electrochemical cell according to the preceding claim, characterized in that the cable comprises a temperature sensor, a pressure sensor, a gas detector, or an electrochemical sensor.

9. Electrochemical cell according to claim 7 or 8, characterized in that said cable comprises a thermocouple cable.

10. Electrochemical cell according to any one of claims 7 to 9, characterized in that the cable comprises a thermoplastic coating at least on its external face intended to be in contact with the first chute (15) and with the second chute (16).

Images