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 the formation of a battery 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 formation cycle of the battery 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 parasitic reactions with materials of the cell and degrade the performance of the battery, in particular its durability.

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

[0005] The present invention therefore aims to overcome all or part of the aforementioned drawbacks, 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 provided with electrodes, an electrolyte, and a pocket housing the electrodes and the electrolyte.

[0007] The assembly further comprises an additional pocket and a conduit connecting the pocket to the additional pocket.

[0008] The pocket and the additional pocket communicate only through 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 gases 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 anti-return device configured to allow circulation of fluid from the bag to the additional bag and to prevent circulation of fluid from the additional bag to the bag.

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

[0011] The fluid anti-return device may be arranged in the additional pocket.

[0012] The pocket and the additional pocket may be connected to each other by a flat portion inside which the pipe extends.

[0013] Said planar portion may extend projecting from an edge of the pocket. Said planar portion may extend projecting from an edge of the additional pocket.

[0014] The pocket and the additional pocket may be formed from a preformed upper sheet and a preformed lower sheet joined together.

[0015] The preformed upper and lower sheets may each comprise aluminum coated with a film of a polymeric material.

[0016] Aluminum provides a protective layer for the battery cell.

[0017] The preformed 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 may be formed from a polymeric material.

[0020] The pipe formed from a polymer material may be obstructed, in particular by subjecting the pipe to a high temperature, for example during a heat-sealing operation. It is then possible to cut the pipe so that the bag and the additional bag are watertight. In particular, this operation does not require the use of 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 of producing an assembly comprising a battery cell provided electrodes, an electrolyte, and a bag housing the electrodes and the electrolyte, the assembly further comprising an additional bag and a conduit connecting the bag to the additional bag;

[0023] - a step of cycling the battery cell; and

[0024] - a step of cutting the pipe so that the pocket is separated from the pocket extra 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 step of producing the assembly may comprise the following steps:

[0027] - a pocket-forming step in which a portion of a sheet su preformed upper sheet is welded, in particular heat-welded, to a part of a preformed lower sheet, the electrodes being housed between said part of the preformed upper sheet and said part 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 pocket through the pipe;

[0029] - a step of positioning a fluid non-return device configured to 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] - a step of forming the additional pocket during which said other 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 pipe opening into the additional pocket.

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

[0032] The step of forming the pocket may comprise inserting a metal rod into the conduit.

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

[0034] The emitted gases contained by the additional pocket can then be analyzed to verify the proper progress of the formation of the battery, 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 studying the detailed description of embodiments, taken as non-limiting examples and illustrated by the appended drawings in which:

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

[0037] [Fig.2] is a sectional view of [Fig.l];

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

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

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

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

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

[0043] Figures 1 to 3 represent an assembly 2 comprising a battery cell 4 provided with a pocket 6, and an additional pocket 8. The pocket 6 is intended to store electrical energy. The additional pocket 8 is intended to allow the recovery of gases generated in the pocket 6, in particular during the formation cycle 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 composed of graphite, and at least one cathode, for example composed of a lithium or sodium-based material. The electrolyte is, for example, a liquid or solid polymer electrolyte.

[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 a space internally.

[0047] The additional pocket 8 also comprises 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 a space internally.

[0048] The 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-piece assembly. In other words, the flat portion 26 is integral with the additional flat portion 28.

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

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

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

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

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

[0054] The assembly 2 comprises a fluid non-return device 36 allowing the circulation of a fluid from the pocket 6 to the additional pocket 8 and preventing the circulation of a fluid from the additional pocket 8 to the pocket 6.

[0055] The fluid non-return device 36 here comprises a fluid non-return valve arranged in the interior space of the additional pocket 8.

[0056] The second end 34 of the pipe 30 has a shape suitable for fixing the fluid non-return valve there.

[0057] The fluid check valve comprises a ball and a spring urging the ball into a position for closing the pipe 30.

[0058] As detailed below, the pocket 6 and the additional pocket 8 are formed from a preformed upper sheet 38 and a preformed lower sheet 40 joined together ([Fig. 6]). For example, the preformed 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 preformed so as to give the shape of the assembly 2 during the assembly of the preformed upper sheet 38 and the preformed lower sheet 40.

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

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

[0062] The preformed upper sheet 38 comprises a portion provided with a recess (not referenced) intended to partly form the pocket 6, in particular to form the upper wall 14 of the pocket 6, as well as another portion provided with an additional recess (not referenced) intended to partly form the additional pocket 8, in particular to form the upper wall 20 of the additional pocket 8.

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

[0064] The preformed lower sheet 40 comprises a part provided with a recess (not referenced) intended to partly form the pocket 6, in particular to form the wall lower part 16 of the pocket 6, as well as another part provided with an additional recess (not referenced) intended to partly form the additional pocket 8, in particular to form the lower wall 22 of the additional pocket 8.

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

[0066] [Fig. 4] schematically represents a method for recovering a gas emitted during the formation of the battery cell 4. In particular, this gas is emitted when, following the formation of the battery cell 4, the latter 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 producing the assembly 2 comprising a sub-step 48 of forming the pocket 6 illustrated in FIGS. 5 to 9.

[0068] During the sub-step 48 of forming the pocket 6, the electrodes 10 are positioned in the recess of the part of the preformed lower sheet 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 part of the preformed lower sheet 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 relative to the first end 32 of the pipe 30.

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

[0071] Then, a flat outline of the part of the preformed upper sheet 38 is brought extending the recess of the part of the preformed upper sheet 38 in contact with the periphery of the part of the preformed lower sheet 40 so that the electrodes 10 are housed in the pocket 6 formed by the recesses 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 sandwiched between the preformed upper and lower sheets 38, 40.

[0072] Finally, the parts of the preformed upper and lower sheets 38, 40 are welded, thus forming the flat portion 26. In particular, the part of the preformed upper sheet 38 is heat-sealed to the part of the preformed lower sheet 40 by heating the edges of the recesses of the preformed upper and lower sheets 38, 40 so as to join them. For example, the films 44 of polymer material covering the aluminum sheets 42 of the preformed upper and lower sheets 38, 40 are heated to a temperature above 160°C and melt ([Fig.8]). The metal rod 50, having protected the pipe 30 during heat welding, is then removed.

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

[0074] Then, a sub-step 54 of positioning the fluid non-return device 36 is carried out. For example, the fluid non-return 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 periphery of the other part of the preformed upper sheet 38 extending the additional recess of the other part of the preformed upper sheet 38 is brought into contact with a flat periphery of the other part of the preformed lower sheet 40 extending the additional recess of the other part of the preformed lower sheet 40. Then, the other parts of the preformed upper and lower sheets 38, 40 are welded, in particular heat-sealed, thus forming the additional flat portion 28.

[0076] The process for recovering the emitted gas is continued by a step 58 of cycling the battery cell 4 comprising several charging and discharging cycles of the battery cell 4. The gases are then generated in the pocket 6 and then evacuated to the additional pocket 8 through the pipe 30.

[0077] Finally, a step 60 of cutting the pipe 30 is carried out 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 pipe 30 extends are heat-sealed so as to seal the pipe 30. Then a cutting device is used to separate the parts of the preformed upper and lower sheets 38, 40 from the other parts of the preformed 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 formation of the battery cell 4.

Claims

Claims

1. Assembly (2) comprising a battery cell (4) provided with electrodes (10), an electrolyte, and a pocket (6) housing the electrodes (10) and the electrolyte, characterized in that it further comprises an additional pocket (8) and a conduit (30) connecting the pocket (6) to the additional pocket (8).

2. An assembly (2) according to claim 1, comprising a fluid non-return device (36) configured to allow the circulation of a fluid from the bag (6) to the additional bag (8) and to prevent the circulation of a fluid from the additional bag (8) to the bag (6).

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

4. An assembly (2) according to any preceding claim, wherein the pocket (6) and the additional pocket (8) are formed from a preformed upper sheet (38) and a preformed lower sheet (40) joined together.

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

6. Assembly (2) according to one of claims 4 and 5, in which the preformed upper and lower sheets (38, 40) are heat-sealed together.

7. An assembly (2) according to any preceding claim, wherein the conduit (30) is formed from a polymeric material.

8. A method for recovering a gas emitted during the formation of a battery, characterized in that it comprises the following steps: - a step (46) of producing an assembly (2) comprising a battery cell (4) provided with electrodes (10), an electrolyte, and a pocket (6) housing the electrodes (10) and the electrolyte, the assembly (2) further comprising an additional pocket (8) and a conduit (30) connecting the pocket (6) to the additional pocket (8); - a step (58) of cycling the battery cell (4); and - a step (60) of cutting the conduit (30) so that the pocket (6) is separated from the additional pocket (8) and is waterproof.

9. Method according to claim 8, in which the step of producing the assembly (2) comprises the following steps: - a step (48) of forming the pocket (6) during which a part of a preformed upper sheet (38) is welded to a part of a preformed lower sheet (40), the electrodes (10) being housed between said part of the preformed upper sheet (38) and said part of the preformed lower sheet (40), a first end (32) of the conduit (30) opening between said part of the preformed upper sheet (38) and said part of the preformed lower sheet (40), a second end (34) of the conduit (30) extending towards another part of the preformed upper sheet (38) and another part of the preformed lower sheet (40); - a step (52) of injecting the electrolyte into the pocket (6) through the pipe (30);- a step (54) of positioning a fluid non-return device (36) configured to allow the circulation of a fluid from the first end (32) of the pipe (30) to the second end (34) of the pipe (30) and to prevent the circulation of a 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).;

10. A method according to claim 9, wherein the step (48) of forming the pocket (6) comprises inserting a metal rod (50) into the conduit (30).

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