An assembly comprising a battery cell and a method for recovering one or more gases emitted during battery formation.

Abstract

This assembly (2) comprises a battery cell (4) equipped with electrodes (10), an electrolyte, and a pouch (6) housing the electrodes (10) and the electrolyte, the assembly (2) further comprising an additional pouch (8) and a conduit (30) connecting the pouch (6) to the additional pouch (8). Figure for the abbreviation: Fig 1

Description

Title of the invention: Assembly comprising a battery cell and method for recovering one or more gases emitted during battery formation technical field

[0001] The present invention relates to battery cells and in particular to the degassing of battery cells during their formation.

[0002] In particular, the present invention relates to an assembly comprising a battery cell and a method for recovering one or more gases emitted during the formation of a battery, in particular emitted during the battery formation cycle during which the battery undergoes several charge and discharge cycles. Previous techniques

[0003] A battery cell may undergo, during its formation, at least one charge and discharge cycle during which gases are emitted. These gases can cause unwanted reactions with cell materials and degrade the battery's performance, particularly its durability.

[0004] In order to remove the emitted gases, a degassing step is generally carried out on the cell in an inert environment, for example in a glove box under inert gas, in order to ensure the safety of the operator carrying out the degassing. Description of the invention

[0005] The present invention therefore aims to overcome all or part of the aforementioned disadvantages, to improve the performance of a battery cell, and to simplify the operation of degassing the battery cell.

[0006] The present invention relates to an assembly comprising a battery cell equipped with electrodes, an electrolyte, and a pocket housing the electrodes and the electrolyte.

[0007] The assembly further includes an additional pouch and a conduit connecting the pouch to the additional pouch.

[0008] The pocket and the additional pocket communicate only via the conduit. Thus, the gases emitted by the battery cell during its formation can flow through the conduit to the additional pocket, thereby reducing the amount of gas emitted in contact with the electrodes and the electrolyte and therefore the parasitic reactions degrading the performance and durability of the battery cell.

[0009] The assembly may include a fluid check device configured to allow the flow of fluid from the pouch to the additional pouch and to prevent the flow of fluid from the additional pouch to the pouch.

[0010] Thus, the gases emitted into the pocket and flowing from the pocket to the additional pocket through the conduit are trapped in the additional pocket and cannot degrade the performance of the battery cell.

[0011] The fluid return-stop device can be arranged in the additional pocket.

[0012] The pouch and the additional pouch can be linked together by a flat portion inside which the conduit extends.

[0013] Said flat portion may extend outward from an edge of the pocket. Said flat portion may extend outward from an edge of the additional pocket.

[0014] The pocket and the additional pocket can be formed from a pre-formed upper sheet and a pre-formed lower sheet joined together.

[0015] The preformed upper and lower sheets can each comprise aluminum covered with a film of a polymer material.

[0016] Aluminium constitutes a protective layer for the battery cell.

[0017] The pre-formed upper and lower sheets are heat-sealed together.

[0018] In particular, the polymer material film of the preformed upper sheet is heat-sealed to the polymer material film of the preformed lower sheet.

[0019] The conduit can be made of a polymer material.

[0020] The conduit made of a polymer material can be obstructed, particularly by By subjecting the pipe to a high temperature, for example during a heat-sealing operation, it is possible to cut the pipe so that the inner and outer liners are sealed. In particular, this operation does not require an inert environment and can be carried out in an anhydrous room.

[0021] The present invention also relates to a method for recovering a gas emitted during the formation of a battery comprising at least the following steps:

[0022] - a step in the realization of an assembly comprising a battery cell equipped electrodes, an electrolyte, and a pouch housing the electrodes and the electrolyte, the assembly further comprising an additional pouch and a conduit connecting the pouch to the additional pouch;

[0023] - a battery cell cycling step; and

[0024] - a step of cutting the conduit so that the pocket is separated from the pocket additional and is waterproof.

[0025] Thus, the gases emitted during the formation of the battery and contained in the additional pocket are recovered without risk to the operator.

[0026] The assembly realization stage may include the following steps:

[0027] - a pocket formation step during which part of a sheet A preformed upper sheet is welded, in particular heat-welded, to a portion of a preformed lower sheet, the electrodes being housed between said portion of the preformed upper sheet and said portion of the preformed lower sheet, a first end of the conduit opening between said part of the preformed upper sheet and said part of the preformed lower sheet, a second end of the conduit extending towards another part of the preformed upper sheet and another part of the preformed lower sheet;

[0028] - a step of injecting the electrolyte into the bag through the conduit;

[0029] - a step of positioning a fluid check valve configured for to allow the flow of a fluid from the first end of the pipe to the second end of the pipe and to prevent the flow of a fluid from the second end of the pipe to the first end of the pipe; and

[0030] - an additional pocket formation step during which said another part of the preformed upper sheet is welded, in particular heat-welded, to said other part of the preformed lower sheet, the second end of the conduit opening into the additional pocket.

[0031] Said preformed upper sheet portion and said other preformed upper sheet portion are complementary to each other and form the preformed upper sheet. Said preformed lower sheet portion and said other preformed lower sheet portion are complementary to each other and form the preformed lower sheet.

[0032] The pocket formation step may include the insertion of a metal rod into the conduit.

[0033] Thus, the conduit is protected during the formation of the pocket. The metal rod is advantageously removed before the additional pocket formation step.

[0034] The gases emitted contained by the additional pocket can then be analyzed to verify the proper progress of the battery formation, and thus verify that the battery meets the quality and performance standards required for its marketing. Brief description of the drawings

[0035] The present invention will be better understood upon study of the detailed description of embodiments, taken by way of non-limiting examples and illustrated by the accompanying drawings in which:

[0036] [Fig-1] is a schematic view of an assembly according to an example embodiment of the invention;

[0037] [Fig.2] is a cross-sectional view of [Fig.1];

[0038] [Fig.3] is a detail view of [Fig.2];

[0039] [Fig.4] schematically illustrates a process for recovering a gas emitted during the battery formation;

[0040] [Fig.5] and [Fig.6] illustrate a step in the formation of a pocket according to an example of an embodiment of the invention;

[0041] [Fig.7] and [Fig.8] illustrate a heat-sealing step of the pocket according to a example of an implementation of the invention; and

[0042] [Fig.9] illustrates a cutting step of the assembly according to an example of embodiment of the invention. Detailed description

[0043] Figures 1 to 3 show an assembly 2 comprising a battery cell 4 with a pouch 6, and an additional pouch 8. The pouch 6 is intended for storing electrical energy. The additional pouch 8 is intended for recovering gases generated in the pouch 6, particularly during the formation cycling of the battery cell 4. The battery is, for example, intended to power an electric motor vehicle.

[0044] The battery cell 4 comprises electrodes 10 and an electrolyte (not shown) housed in the pocket 6, as well as two current collectors 12 each extending through a wall of the pocket 6.

[0045] The electrodes 10 of the cell 4 comprise at least one anode, for example made of graphite, and at least one cathode, for example made of a lithium- or sodium-based material. The electrolyte is, for example, a liquid electrolyte or a solid polymer.

[0046] The pocket 6 comprises an upper wall 14 and a lower wall 16 opposite the upper wall 14, as well as peripheral edges 18 connecting the upper and lower walls 14, 16 of the pocket 6 so as to form an internal space.

[0047] The additional pocket 8 also includes an upper wall 20 and a lower wall 22 opposite the upper wall 20, as well as peripheral edges 24 connecting the upper and lower walls 20, 22 of the additional pocket 8 so as to form an internal space.

[0048] Assembly 2 comprises a flat portion 26 extending from the peripheral edges 18 of the pocket 6 and an additional flat portion 28 extending from the peripheral edges 24 of the additional pocket 8. The flat portion 26 and the additional flat portion 28 form a single unit. In other words, the flat portion 26 is formed from the same material as the additional flat portion 28.

[0049] The assembly 2 further includes a conduit 30 connecting the pocket 6 to the additional pocket 8.

[0050] The interior space of pocket 6 and the interior space of the additional pocket 8 communicate fluidly only through the conduit 30.

[0051] A first end 32 of the conduit 30 extends through a peripheral edge 18 of the pocket 6 and opens into the interior space of the pocket 6. A second end 34 of the conduit 30 opposite to the first end 32 of the conduit 30 extends through a peripheral edge 24 of the additional pocket 8 and opens into the interior space of the additional pocket 8. The conduit 30 extends through the flat wall 26 and the additional flat wall 28.

[0052] The conduit 30 includes, for example, a needle.

[0053] The conduit 30 is, for example, made of a polymer material.

[0054] Assembly 2 includes a fluid check valve 36 allowing the circulation of fluid from the pocket 6 to the additional pocket 8 and preventing the circulation of fluid from the additional pocket 8 to the pocket 6.

[0055] The fluid check valve 36 here comprises a fluid check valve disposed in the interior space of the additional pocket 8.

[0056] The second end 34 of the pipe 30 has a shape adapted to fix the fluid check valve.

[0057] The fluid check valve includes a ball and a spring pushing the ball into a position of closing the pipe 30.

[0058] As detailed below, the pocket 6 and the additional pocket 8 are formed from a pre-formed upper sheet 38 and a pre-formed lower sheet 40 joined together ([Fig. 6]). For example, the pre-formed inner and upper sheets 38, 40 are heat-sealed together to form the pocket 6, the flat portion 26, the additional pocket 8, and the additional flat portion 28.

[0059] The upper and lower sheets 38, 40 are pre-formed so as to give the shape of the assembly 2 when the pre-formed upper sheet 38 and the pre-formed lower sheet 40 are assembled.

[0060] The upper and lower preformed leaves 38, 40 are advantageously identical to each other.

[0061] The upper preformed sheet 38 comprises ([Fig.7]), for example, an aluminum sheet 42 covered, at least on its face oriented towards the lower preformed sheet 40, by a film 44 of a polymer material.

[0062] The preformed upper sheet 38 includes a part having a recess (not referenced) intended to form part of the pocket 6, in particular to form the upper wall 14 of the pocket 6, and another part having an additional recess (not referenced) intended to form part of the additional pocket 8, in particular to form the upper wall 20 of the additional pocket 8.

[0063] The lower preformed sheet 40 comprises ([Fig.7]), for example, an aluminum sheet 42 covered, at least on its face oriented towards the upper preformed sheet 38, by a film 44 of a polymer material.

[0064] The preformed lower sheet 40 includes a part having a recess (not referenced) intended to form in part the pocket 6, in particular to form the lower wall 16 of the pocket 6, and another part having an additional recess (not referenced) intended to form in part the additional pocket 8, in particular to form the lower wall 22 of the additional pocket 8.

[0065] The recess in the pre-formed lower sheet 40 is intended to form the pocket 6 of the assembly 2 together with the recess in the pre-formed upper sheet 38. The additional recess in the pre-formed lower sheet 40 is intended to form the additional pocket 8 of the assembly 2 together with the additional recess in the pre-formed upper sheet 38.

[0066] Figure 4 schematically represents a method for recovering a gas emitted during the formation of battery cell 4. In particular, this gas is emitted when, following the formation of battery cell 4, it undergoes at least one charge and discharge cycle to stabilize its active materials and thus minimize undesirable chemical reactions during subsequent charge and discharge cycles.

[0067] We begin with a step 46 of realization of the assembly 2 comprising a sub-step 48 of formation of the pocket 6 illustrated in figures 5 to 9.

[0068] During substep 48 of pocket formation 6, the electrodes 10 are positioned in the recess of the preformed lower sheet part 40, the current collectors 12 are connected to the electrodes 10, the current collectors 12 are positioned in contact with a flat periphery of the preformed lower sheet part 40 extending the recess of the preformed lower sheet 40, the current collectors 12 being arranged on either side of the electrodes 10.

[0069] Then, the pipe 30 is positioned so that the first end 32 of the pipe 30 is opposite the electrodes 10 and so that the second end 34 of the pipe 30 is opposite the electrodes 10 with respect to the first end 32 of the pipe 30.

[0070] Advantageously, a metal rod 50 is inserted into the conduit 30.

[0071] Then, a flat perimeter is brought to the preformed upper part of the sheet 38 extending the indentation of the preformed upper sheet part 38 to the perimeter of the preformed lower sheet part 40 so that the electrodes 10 are housed in the pocket 6 formed by the indentations of the preformed upper and lower sheets 38, 40, so that the first end 32 of the conduit 30 opens into the pocket 6 and so that the current collectors 12 are clamped between the preformed upper and lower sheets 38, 40.

[0072] Finally, the preformed upper and lower sheet portions 38, 40 are welded together, thus forming the flat portion 26. In particular, the preformed upper sheet portion 38 is heat-welded to the preformed lower sheet portion 40 by heating The edges of the recesses in the pre-formed upper and lower sheets 38, 40 are joined. For example, the polymer films 44 covering the aluminum sheets 42 of the pre-formed upper and lower sheets 38, 40 are heated to a temperature above 160°C and melt ([Fig. 8]). The metal rod 50, which protected the pipe 30 during the heat-sealing process, is then removed.

[0073] We continue with a sub-step 52 of injecting the electrolyte into the pocket 6 through the conduit 30.

[0074] Then, a substep 54 of positioning the fluid check valve 36 is carried out. For example, the fluid check valve is inserted into the second end 34 of the pipe 30 of suitable shape.

[0075] Finally, a sub-step 56 of forming the additional pocket 8 is carried out. A flat perimeter of the other part of the pre-formed upper sheet 38 extending the additional recess of the other part of the pre-formed upper sheet 38 is brought into contact with a flat perimeter of the other part of the pre-formed lower sheet 40 extending the additional recess of the other part of the pre-formed lower sheet 40. Then, the other parts of the pre-formed upper and lower sheets 38, 40 are welded, in particular heat-welded, thus forming the additional flat portion 28.

[0076] The gas recovery process is continued by a step 58 of cycling the battery cell 4, comprising several charge and discharge cycles of the battery cell 4. The gases are then generated in the pocket 6 and subsequently vented to the additional pocket 8 through the conduit 30.

[0077] Finally, a cutting step 60 is carried out on the conduit 30 so that the pocket 6 is separated from the additional pocket 8 and is sealed. For example, the flat portion 26 and the additional flat portion 28 in which the conduit 30 extends are heat-sealed so as to seal the conduit 30. Then a cutting device is used to separate the parts of the pre-formed upper and lower sheets 38, 40 from the other parts of the pre-formed upper and lower sheets 38, 40, the flat portion 26 then being separated from the flat portion 28, as illustrated in [Fig. 9].

[0078] The additional pocket 8 can now be analyzed to verify the proper progress of the formation of the battery cell 4.

Claims

Demands

1. Assembly (2) comprising a battery cell (4) having electrodes (10), an electrolyte, and a pouch (6) housing the electrodes (10) and the electrolyte, characterized in that it further comprises an additional pouch (8) and a conduit (30) connecting the pouch (6) to the additional pouch (8) and a fluid check device (36) configured to permit the flow of fluid from the pouch (6) to the additional pouch (8) and to prevent the flow of fluid from the additional pouch (8) to the pouch (6).

2. Assembly (2) according to claim 1, in which the pocket (6) and the additional pocket (8) are linked together by a flat portion (26, 28) inside which the conduit (30) extends.

3. Assembly (2) according to any one of claims 1 and 2, wherein the pocket (6) and the additional pocket (8) are formed of a preformed upper sheet (38) and a preformed lower sheet (40) joined together.

4. Assembly (2) according to claim 3, wherein the preformed upper and lower sheets (38, 40) each comprise aluminum (42) covered with a film (44) of a polymer material.

5. Assembly (2) according to any one of claims 3 and 4, wherein the preformed upper and lower sheets (38, 40) are heat-welded together.

6. Assembly (2) according to any one of the preceding claims, wherein the conduit (30) is formed of a polymer material.

7. A method for recovering a gas emitted during battery formation, characterized in that it comprises the following steps: - a step (46) of constructing an assembly (2) comprising a battery cell (4) equipped with electrodes (10), an electrolyte, and a pouch (6) housing the electrodes (10) and the electrolyte, the assembly (2) further comprising an additional pouch (8) and a conduit (30) connecting the pouch (6) to the additional pouch (8) and comprising a substep (54) of positioning a fluid check valve (36); - a step (58) of cycling the battery cell (4); and - a step (60) of cutting the conduit (30) so that the pouch (6) is separated from the additional pouch (8) and is watertight.

8. A method according to claim 7, wherein the step of making the assembly (2) comprises the following steps: - a step (48) of forming the pocket (6) during which a portion of a preformed upper sheet (38) is welded to a portion of a preformed lower sheet (40), the electrodes (10) being housed between said portion of the preformed upper sheet (38) and said portion of the preformed lower sheet (40), a first end (32) of the conduit (30) opening between said portion of the preformed upper sheet (38) and said portion of the preformed lower sheet (40), a second end (34) of the conduit (30) extending towards another portion of the preformed upper sheet (38) and another portion of the preformed lower sheet (40); - a step (52) of injecting the electrolyte into the bag (6) through the conduit (30);- a step (54) of positioning a fluid check valve (36) configured to permit the flow of fluid from the first end (32) of the pipe (30) to the second end (34) of the pipe (30) and to prevent the flow of fluid from the second end (34) of the pipe (30) to the first end (32) of the pipe (30); and - a step (56) of forming the additional pocket (8) during which said other part of the preformed upper sheet (38) is welded to said other part of the preformed lower sheet (40), the second end (34) of the pipe (30) opening into the additional pocket (8).

9. Method according to claim 8, wherein the step (48) of forming the pocket (6) comprises the insertion into the conduit (30) of a metal rod (50).

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