METHOD FOR PRODUCING A BATTERY CELL

Abstract

A method for producing a battery cell involves producing a battery cell with a housing having a first volume containing a multiplicity of electrodes are stacked one on top of another and an electrolyte, wherein the electrolyte can be introduced into the first volume via an opening in the housing.

Claims

1. A method for producing a battery cell, comprising: a) providing a housing having a first volume, and, in the first volume, a multiplicity of electrodes stacked one on top of another and an electrolyte, wherein the electrolyte is introduced into the first volume via an unsealed opening; b) degassing the first volume via the opening and closing the opening with a closing element, wherein the closing element and the opening form a non-material connection; c) arranging a chamber on the housing so that the opening and the closing element are arranged inside the chamber and so that at least one part of the housing is arranged outside the chamber; d) creating a negative pressure in the chamber; and e) providing a laser welding device and materially connecting the closing element to the housing using a laser beam, so that the opening is sealed gas-tight by the material connection thus created.

2. The method according to claim 1, in which the laser beam is coupled into the chamber via a transparent wall of the chamber.

3. The method according to claim 1, wherein the chamber has a bearing surface for contacting the housing, and wherein the bearing surface is designed to seal the chamber gas-tight from an environment.

4. The method according to claim 1, wherein the chamber has a second volume which is smaller than the first volume.

5. The method according to claim 4, wherein the second volume is at most 5 percent of the first volume.

6. The method according to claim 1, wherein the closing element comprises a sealing material by which the opening is closed in a liquid-tight manner before step c).

7. The method according to claim 1, wherein the closing element is connected to the housing in a form-fitting manner before step c).

8. The method according to claim 1, wherein the negative pressure in the chamber is less than 30 mbar.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0060] The invention and the technical environment are explained in more detail below with reference to the accompanying figures. It should be pointed out that the invention is not intended to be limited by the embodiments mentioned. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the facts explained in the figures and to combine them with other components and findings from the present description. In particular, it should be pointed out that the figures and in particular the proportions shown are only schematic. In the figures:

[0061] FIG. 1: a battery cell in an exploded view, in a perspective view;

[0062] FIG. 2: the battery cell according to FIG. 1 according to step a), in a perspective view;

[0063] FIG. 3: the battery cell according to FIGS. 1 and 2 according to step b), in a perspective view;

[0064] FIG. 4: the battery cell according to FIG. 3 with an alternative closing element, in a perspective view;

[0065] FIG. 5: the battery cell according to FIGS. 1 to 4 according to step c), in a perspective view;

[0066] FIG. 6: the battery cell according to FIGS. 1 to 5 according to step d), in a perspective view;

[0067] FIG. 7: the battery cell according to FIGS. 1 to 6 according to step e), in a perspective view; and

[0068] FIG. 8: the battery cell according to FIGS. 1 to 7 according to step f), in a perspective view.

DETAILED DESCRIPTION OF THE INVENTION

[0069] FIG. 1 shows a battery cell 1 in an exploded view, in a perspective view. FIG. 2 shows the battery cell 1 according to FIG. 1 according to step a), in a perspective view. FIGS. 1 to 2 are described together below.

[0070] The battery cell 1 has a housing 2 having a first volume 3 and in the first volume 3 a multiplicity of electrodes 4 stacked on top of one another and an electrolyte 5. The electrolyte 5 may be introduced into the first volume 3 via an opening 6 in the housing 2. The housing 2 is a dimensionally stable (i.e. only a plastically deformable) housing 2. The electrodes 4 are in particular stacked in a known manner and are acted upon by an electrolyte 5 or an electrolytic liquid.

[0071] The electrodes 4 are foil-like, i.e. they have a large side surface and a small thickness. The separators are each arranged between the side surfaces of the adjacently arranged different electrode foils. The anodes and the cathodes within the stack of electrodes 4 are connected in parallel with one another, so that the conductors of a plurality of anodes are electrically conductively connected to one another and the conductors of a plurality of cathodes are electrically conductively connected to one another. The conductors of the anodes are electrically conductively connected to a first connection 17 and the conductors of the cathodes are electrically conductively connected to a second connection 18.

[0072] The rigid housing 2 has a cover 19 on which the first connection 17 and the second connection 18 for the electrical connection of the electrodes 4 arranged inside the housing 2 to a circuit arranged outside the housing 2, as well as the closable opening 6 for filling the first volume 3 are provided with the electrolyte 5. Furthermore, a pressure relief valve 20 is arranged in the cover 19, via which pressure relief to an environment 13 can take place when the pressure in the first volume 3 increases.

[0073] According to step a), the battery cell 1 is provided with the housing 2 and electrodes 4 arranged therein and the electrolyte 5 as well as the unsealed opening 6. The opening 6 is arranged in a dimensionally stable part of the housing 2, the cover 19.

[0074] FIG. 3 shows the battery cell 1 according to FIGS. 1 and 2 according to step b), in a perspective view. FIG. 4 shows the battery cell 1 according to FIG. 3 with an alternative closing element 7 in a perspective view. FIGS. 3 to 4 are described together below. Reference is made to the statements about FIGS. 1 to 2.

[0075] According to step b), the first volume 3 is degassed via the opening 6 in a known manner and the opening 6 is sealed with a closing element 7, wherein the closing element 7 and the opening 6 have a non-material connection, i.e. a non-positive and/or positive connection.

[0076] In both cases of FIGS. 3 and 4, the closing element 7 is designed in two parts. In doing so, for example, the one element, for example a sealing material 15, are deformed by the other element of the multi-part closing element 7 so that a good seal of the opening 6 can be achieved. In FIG. 3 the closing element 7 comprises two discs. In FIG. 4, the locking element 7 comprises a bolt and a ball which can be deformed by the bolt.

[0077] FIG. 5 shows the battery cell 1 according to FIGS. 1 to 4 according to step c), in a perspective view. FIG. 6 shows the battery cell 1 according to FIGS. 1 to 5 according to step d), in a perspective view. FIGS. 5 to 6 are described together below. Reference is made to the statements relating to FIGS. 1 to 4.

[0078] According to step c), a chamber 8 is arranged on the housing 2 so that the opening 6 and the closing element 7 are arranged inside the chamber 8 (see also FIG. 6) and at least a part of the housing 2 is arranged outside the chamber 8. The chamber 8 has the function of sealing the closing element 7 and a part of the housing 2 from an environment 13 of the battery cell 1 and the chamber 8, so that a special atmosphere can be set within the chamber 8, preferably a vacuum or partial vacuum that has a vacuum device 16 connected to the chamber 8 can be realized. The chamber 8 has a second volume 14 that is significantly smaller than the first volume 3.

[0079] The chamber 8 has an open side which is placed on the housing 2. The chamber 8 thus surrounds a surface of the housing 2 which comprises the opening 6 or the closing element 7, a heat-affected zone of the weld seam 21 produced in step e) and an additional zone surrounding the weld seam 21 and the heat-affected zone. The additional zone prevents the chamber 8 from being damaged by contacting the heat-affected zone.

[0080] The fixation between the chamber 8 and the surface of the housing 2 is effected by a suction system or by a vacuum device 16 connected to the chamber 8. The chamber 8 contacts the housing 2 via a bearing surface 12. The material of this bearing surface 12 can be a rubber or a soft metal in order to avoid damaging the housing 2 by arranging the chamber 2 due to the negative pressure conditions in the chamber 8.

[0081] Step d) comprises creating a negative pressure, i.e. a partial vacuum or a vacuum, in the chamber 8. For this purpose, the vacuum device 16 is connected to the chamber 8 via which air can be sucked out of the chamber 8.

[0082] FIG. 7 shows the battery cell 1 according to FIGS. 1 to 6 according to step e), in a perspective view. Reference is made to the statements on FIGS. 1 to 6.

[0083] Step e) comprises the provision of a laser welding device 9 and the material connection of the closing element 7 to the housing 2 by a laser beam 10, so that the opening 6 is gas-tightly sealed by the material connection or weld seam 21 thus produced.

[0084] The laser beam 10 is coupled into the chamber 8 via a transparent wall 11 of the chamber 8. The transparent wall 11 of the chamber 8 faces the open side surface of the chamber 8 and the housing 2.

[0085] The chamber 8 is arranged immovably on or in relation to the housing 2 during step e). The housing 2 is moved with the chamber 8 relative to the laser beam 10 and the environment 13.

[0086] In FIG. 7 it can be seen that the closing element 7 is designed as a rivet that is introduced undeformed into the opening 6 and then deformed at least within the first volume 3 so that the closing element 7 is arranged captively in the opening 6.

[0087] FIG. 8 shows the battery cell 1 according to FIGS. 1 to 7 according to step f), in a perspective view. Reference is made to the statements about FIGS. 1 to 7.

[0088] The battery cell 1 is now ready for operation. The opening 6 is sealed by the closing element 7 and the closing element 7 is materially connected to the housing via the weld seam 21.

LIST OF REFERENCE SIGNS

[0089] 1 Battery cell [0090] 2 Housing [0091] 3 First volume [0092] 4 Electrode [0093] 5 Electrolyte [0094] 6 Opening [0095] 7 Closing element [0096] 8 Chamber [0097] 9 Laser welding device [0098] 10 Laser beam [0099] 11 Wall [0100] 12 Bearing surface [0101] 13 Environment [0102] 14 Second volume [0103] 15 Sealing material [0104] 16 Vacuum device [0105] 17 First connector [0106] 18 Second connector [0107] 19 Cover [0108] 20 Pressure relief valve [0109] 21 Weld seam