Method for producing a film bag single cell and film bag single cell

Abstract

The invention relates to a method for producing a film bag single cell (3) for an electrical energy storage device, wherein an electrochemical active material (2) is encased in a composite film.According to the invention, a composite film tube (1) is coated flatly on its inside with an adhesive (6), the electrochemical active material (2) is inserted into the composite film tube (1), wherein pole contact elements electrically connected to the electrochemical active material (2) are led out in sections at opposite openings of the composite film tube (1), the composite film tube (1) is evacuated after the electrochemical active material (2) has been inserted and the adhesive (6) is activated in a region of the composite film tube (1) surrounding the electrochemical active material (2) for the material-to-material connection of a projection formed by the evacuation and projecting beyond the active material (2), wherein the electrical pole contact elements are sealed and are led out in sections from a composite film sleeve formed by the composite film tube (1).Furthermore, the invention relates to a film bag single cell (3).

Description

The invention relates to a method for producing a single film pouch cell for an electrical energy store, wherein an electrochemical active material is enveloped by a composite film. The invention further relates to a single cell pouch cell.U.S. Pat. No. 8,771,866 B2 discloses a method for producing a secondary battery. The method comprises: positioning an electrode assembly between first and second pouch films; initially sealing outer portions of the first and second pouch films on one side of the first and second pouch films; and additionally sealing outer portions of the first and second pouch films on one side of the first and second pouch films.The invention is based on the object of specifying a method for producing a single cell pouch for an electrical energy store and a single cell pouch.The object is achieved according to the invention by a method which has the features specified in claim 1 and by a single film pouch cell which has the features specified in claim 2.Advantageous embodiments of the invention are the subject matter of the dependent claims.A method for producing a single film pouch cell for an electrical energy store, wherein an electrochemical active material is enveloped by a composite film, provides, according to the invention, that a composite film tube is coated flat on its inner side with an adhesive, the electrochemical active material is inserted into the composite film tube, wherein pole contact elements electrically connected to the electrochemical active material are led out in sections at opposite openings of the composite film tube, the composite film tube is evacuated after the electrochemical active material is inserted, and the adhesive is activated in a region of the composite film tube surrounding the electrochemical active material for the cohesive connection of a protrusion formed by the evacuation and protruding beyond the active material, wherein the electrical pole contact elements are sealed and led out in sections from a composite film shell formed by means of the composite film tube.By using the method, a single film pouch cell is produced which has a pinch seam formed by the protrusion, which is dimensioned smaller than a conventionally known seal seam. Thus, a thermal coupling of the single film pouch cell to a temperature control device can be optimized. Efficient temperature control of the single cell pouch cell is thus promoted.The single film bag cell only has sealing seams formed at the closed openings of the composite film tube, whereby possible weak spots with respect to an opening of such a sealing seam are reduced.A single film bag cell produced by means of the method has optimized temperature control properties and a reduced risk of leaks, since there are only two sealing seams for closing the composite film casing designed as a composite film tube.Exemplary embodiments of the invention are explained in more detail below with reference to drawings.The following are shown: FIG. 1 schematically shows a sectional illustration of an electrochemical active material inserted into a composite film tube, FIG. 2 is a schematic sectional view of the evacuated composite film tube; and FIG. 3 schematically shows a sectional illustration of a number of single film pouch cells thermally coupled to a temperature control device.Corresponding parts are provided with the same reference numerals in all figures.FIG. 1 shows a sectional illustration of an electrochemical active material 2, in particular an electrode foil arrangement, inserted into a composite foil tube 1 for producing a single foil pouch cell 3 shown in more detail in FIG. 3.FIG. 2 shows a sectional illustration of the evacuated composite film tube 1 with the electrochemical active material 2 for producing the single film pouch cell 3.In general, it is known that the electrochemical active material 2 of a single film pouch cell 3, which is also referred to as pouch cell or coffee bag cell, is enveloped by a composite film shell formed by two composite films. The two composite films are connected to one another at a circumferential sealing seam by an adhesive 6, in particular a sealing adhesive, whereby the single film pouch cell 3 is formed. The adhesive 6 is subject to aging phenomena, as a result of which leaks arise in the composite film casing, which can lead to failure of the single film bag cell 3. In particular, a reduction of a sealing width of one millimeter per year caused by aging is assumed here. The single film pouch cells 3 are designed for a service life of ten years, so that a required sealing width is at least ten millimeters, for example 10 mm or 15 mm, in order to compensate for the reduction in the sealing width.Single film pouch cells 3 are installed vertically within a housing, not shown in detail, of an electrical energy store, in particular a traction battery, wherein the single film pouch cell 3 is arranged with one of its long narrow sides vertically on a temperature control device 4, in particular a temperature control plate, shown in detail in FIG. 3 and is thus thermally coupled thereto. In order to optimize a thermal connection of the single film pouch cell 3 to the temperature control device 4, a thermally conductive paste 5 is introduced between the single film pouch cell 3 and the temperature control device 4. The thinner a layer of the thermally conductive paste 5, the more optimized is a thermal coupling between the single film pouch cell 3 and the temperature control device 4.A sealing seam that usually extends around in a comparatively wide manner reduces a thermal coupling between the single cell pouch 3 and the temperature control device 4, in particular if an edge region of the single cell pouch 3 comprising the sealing seam is rolled up. The thermally conductive paste 5 must in any case be applied thicker than is technically necessary. For this reason, the thermal coupling is less good than if the layer of the thermally conductive paste 5 has an optimized thickness. The temperature control device 4 of the electrical energy store consequently operates more inefficiently than would be the case under optimized conditions. In addition, a circumferential adhesive edge, i.e. the circumferential sealing seam, represents a weak point of the composite film shell of the single film pouch cell 3.In order to reduce a risk of leakage of the composite film shell and to optimize thermal coupling of the single film pouch cell 3 to the temperature control device 4, the single film pouch cell 3 is produced as described below.For this purpose, it is provided that the composite film shell of the electrochemical active material 2 is formed by means of a composite film tube 1. An inner side of the composite film tube 1 is coated over its entire surface with adhesive 6, in particular sealing adhesive, in one method step. A tube diameter is selected in such a way that a process-safe introduction of the electrochemical active material 2 into the composite film tube 1 is possible.After the inner side is coated with the adhesive 6, the electrochemical active material 2 is inserted into the composite film tube 1 in a further method step, wherein a length of the composite film tube 1 is selected such that the composite film tube 1 protrudes beyond the electrochemical active material 2. In this case, electrically connected pole contact elements, not shown in more detail, are led out in sections at opposite openings of the composite film tube 1.The composite film tube 1 with the inserted electrochemical active material 2 is then evacuated and the adhesive 6 is activated, in particular in a region surrounding the electrochemical active material 2, in particular in a protrusion formed by the evacuation, so that sections of the composite film tube 1 that abut each other are connected to each other in a surrounding manner.In the region of the opposite openings of the composite film tube 1, wide sealing seams, not shown in more detail, are formed, at which the electrical pole contact elements are led out in a sealed manner.Hermetically sealed pinch seams N are formed on the narrow sides of the single film pouch cell 3, which pinch seams have a shorter length compared to the sealing seams known from the prior art, as is shown in FIG. 3. Since these pinch seams N formed on the long narrow sides are designed to be comparatively small, a thermal coupling of the single film bag cell 3 arranged with the narrow side standing with respect to the temperature control device 4 is optimized.Here too, a thermally conductive paste 5 is applied to the temperature control device 4 for thermal coupling between the single film pouch cell 3 and the temperature control device 4, wherein the thickness of the layer is reduced, so that the thermal coupling is optimized. An efficiency of the temperature control device 4 can thus be increased.By using the composite film tube 1, the composite film sleeve still has only two sealing seams, so that the aging of the adhesive 6 in the closed composite film tube 1 does not play an essential role.List of reference characters1 Composite foil tube 2 Electrochemical active material 3 Single foil pouch cell 4 Temperature control device 5 Thermally conductive paste 6 Adhesive N Pinch seamReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedU.S. Pat. No. 8,771,866 B2

[0002]

Claims

Method for producing a single cell pouch (3) for an electrical energy store, wherein an electrochemical active material (2) is enveloped by a composite foil, characterized in that - a composite foil tube (1) is coated flat on its inner side with an adhesive (6), - the electrochemical active material (2) is inserted into the composite foil tube (1), wherein pole contact elements electrically connected to the electrochemical active material (2) are guided out in sections at opposite openings of the composite foil tube (1), - the composite foil tube (1) is evacuated after the electrochemical active material (2) is inserted, and - the adhesive (6) is activated in a region of the composite foil tube (1) encircling the electrochemical active material (2) for the cohesive connection of a protrusion formed by the evacuation and protruding beyond the active material (2), wherein the electrical pole contact elements are sealed and are brought out in sections from a composite foil sheath formed by means of the composite foil tube (1).Single film pouch cell (3) produced according to the method of claim 1, wherein the composite film shell is formed by a composite film tube (1) which is connected in a materially bonded manner circumferentially to the electrochemical active material (2), and the electrical pole contacts are led out of the composite film shell in a sealed manner on opposite sides of the latter.

Images