Electrode stack / separator stack for battery cell, and method for manufacturing such electrode stack / separator stack

Abstract

To provide an electrode stack / separator stack and a method for manufacturing such electrode stack / separator stack, in which a stacking process is easier than the prior art in terms of manufacturing technology, and which may be carried out with greater accuracy of placement.SOLUTION: An electrode stack / separator stack for a battery cell comprises at least an electrode, in particular a cathode (K), and a counter electrode, in particular an anode (A). The electrode (K) is a constituent of a laminated composite (V), in which one separator (S) is laminated to each of the two sides of the electrode (K), and the two separators (S) protrude beyond the electrode (K) each with an overhang (a) on the edge side. An edge-side gap (9) between the two separator overhangs (a) is in particular completely filled with an edge protection film (11).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an electrode stack / separator stack for a battery cell according to the preamble of claim 1 as well as to a method for manufacturing such an electrode stack / separator stack according to the preamble of claim 10.

[0002] Such an electrode / separator stack can be manufactured by lamination of individual sheets. In the lamination of individual sheets, the placement accuracy of the electrode sheets and separator sheets in the electrode / separator stack is crucial for the safety and performance of the battery cell. For example, the electrochemical performance of a battery cell with a relatively small overlap of the electrodes degrades relatively quickly during operation. Furthermore, incorrect placement of the sheets can lead to direct contact connection of the anode and cathode, which may trigger a short circuit and failure of the battery cell. To achieve perfect overlap of the anode and cathode despite the inaccurate placement, for example, the anode in the electrode / separator stack can be larger in the circumferential direction than the cathode by an oversized portion (e.g., 1.5 mm), and the separator can be larger than the anode by an oversized portion.

[0003] The above-mentioned stacking of the individual sheets is carried out, in a production-technologically costly manner, by means of control devices which receive their coordinates on the basis of image processing in which, after each sheet laying, the position of each laid electrode / separator sheet is optically detected and evaluated, thus determining the laying accuracy.

[0004] Such optical detection of the placement accuracy does not provide for position correction of the already placed electrode / separator sheets after the stacking process, so that placement errors are identified but cannot be subsequently removed. Furthermore, additive manufacturing carried out using image processing is costly in terms of measurement technology and can lead to system-induced position deviations of the individual sheets stacked in the electrode / separator stack.

[0005] From US 2022 / 0148821 A1, a battery cell is known having an inner element with a first main surface, a second main surface, a first side surface, a second side surface, a first end surface and a second end surface. Further, a first inner electrode extending to the first end surface, a second electrode extending to the second end surface, a separator layer arranged between the first electrode and the second electrode and an electrolyte solution are provided. Furthermore, the first electrode is arranged on the first end surface and the second electrode is arranged on the second end surface. The first electrode, the second electrode and the separator layer form an integrally joined composite.

[0006] From DE 10 2016 217 397 A1 an electrode stack is known in which at least one sheet edge lateral surface is provided with an electrically insulating coating, which is applied from the liquid phase and extends over the entire height of the electrode stack.

[0007] From JP 5375263 a manufacturing method and a manufacturing device for batteries with high battery performance are known, in which a number of laminates of one electrode and one separator are formed.

[0008] The object of the present invention is to provide an electrode stack / separator stack in which the lamination process can be carried out more easily in terms of manufacturing technology and with higher placement accuracy than in the prior art, as well as a method for manufacturing such an electrode stack / separator stack.

[0009] The above mentioned problem is solved by the features of claim 1 or claim 10. Preferred developments of the invention are disclosed in the dependent claims.

[0010] The invention is based on an electrode / separator stack for a battery cell, which consists at least of an electrode, in particular a cathode, and a counter-electrode, in particular an anode. The electrode is a component of a laminated composite, in which one separator is laminated on each of the two sides of the electrode. The two separators project from the electrode at the edge side with protrusions. According to the characterizing part of claim 1, the edge side gap between the two separator protrusions is preferably completely filled by an edge protection film. The edge protection film may have the same material thickness as the electrode, observed in the thickness direction of the laminated composite. In this way, the corners and edges of the electrode are protected from external mechanical loads by means of the edge protection film. The edge protection film can provide a form-stable abutment surface during the alignment process carried out on the finished electrode / separator stack, which abutment surface allows a damage-free lateral movement of the electrodes in the electrode / separator stack. Furthermore, the edge protection film acts as an electrical insulator, which increases the electrical safety of the battery cell.

[0011] The electrode stack / separator stack according to the invention can be produced in the form of a stack of individual sheets, in which the laminated composite and the counterelectrode are laminated to one another as individual sheets.

[0012] In a technical embodiment, each separator may have an adhesive layer, by means of which the separator can be laminated onto the electrode in a lamination process, in particular forming a laminated composite. In this way, the two separators and the electrode arranged therebetween already form a structural unit that is joined together before the lamination process is carried out, which results in a higher lamination accuracy in the electrode stack / separator stack, in particular compared to electrode stacks / separator stacks in which the electrodes are laminated as individual sheets.

[0013] The electrodes and / or counterelectrodes are formed from a substrate film. One or both sides of the substrate film are coated with an electrode active material. The active material has a binder, in particular a polymeric binder, preferably PVDF. In order to avoid unfavorable material combinations between the active material and the edge protection film and, if necessary, the adhesive layer, both the active material binder and the edge protection film and, if necessary, the adhesive layer are formed from the same material. That is, both the adhesive layer and the edge protection film have the same material composition as the active material binder. This ensures that the edge protection film is durable against the electrolyte. Furthermore, it is ensured that the material combination between the edge protection film and the active material binder is electrochemically stable or durable.

[0014] The laminated composite consisting of two separators and an electrode arranged between them may be provided as a rectangular planar cutout. On one cutout side of the cutout (hereinafter referred to as the "conductor strip side"), the substrate film of the electrode may be extended laterally outwardly by the conductor strip beyond the separator edge. The edge side gap, which is filled by the edge protection film, may extend continuously at least along the cutout side opposite the conductor strip side and along the two cutout sides of the laminated composite perpendicular to the conductor strip side. The conductor strip side itself is not provided with an edge protection film, which makes it possible to remove the conductor strip from the composite. In this way, thickenings (caused by the edge protection film) at the height of the conductor strip, which would become noticeable later, are avoided. It is therefore advantageous if the edge protection film is provided on only three of the total four cutout sides, so that no thickenings can occur.

[0015] To achieve perfect overlap of the electrode (i.e. cathode) and counter-electrode (i.e. anode) despite imprecision in placement, the counter-electrode may preferably be dimensioned to be circumferentially larger than the electrode by an oversized portion, e.g. 1-3 mm. The counter-electrode and separator may preferably be manufactured as a joint sheet cutout, i.e. the counter-electrode is dimensioned to have the same area and the same contour as the separator, except for its conductor piece, so that the corners and edges of the counter-electrode may be aligned in line with the corners and edges of the separator in the stacking direction.

[0016] The method for producing the electrode / separator stack can be divided into a lamination process and a subsequent alignment process. In the lamination process, the laminated composite of separator and electrode and the counterelectrode are laminated to one another in the form of a stack of individual sheets. In the subsequent alignment process, the laminated composite and the counterelectrode can be aligned to one another in the lamination direction. Due to the provision of the edge protection film according to the invention, the laminated composite is designed to be form-stable, so that a damage-free position correction of the laminated composite can be carried out transversely to the lamination direction. The laminated composite, which is thus form-stable, also provides a stable counterhold or a stable support base for the adjacent counterelectrode, so that a damage-free position correction of the counterelectrode can be carried out. Preferably, at least one lateral stop, in particular a slider, can be used in the alignment process. The lateral stops allow stack components, i.e., laminated composites or counter electrodes, that are misaligned laterally relative to the stacking direction to be corrected, i.e., aligned with other stack components.

[0017] The edge protection film can be applied to the laminated composite in any suitable manner. For example, the edge protection film can be applied to the laminated composite in a coating process, in which the viscous base component of the edge protection film is applied directly to the edge side gap of the laminated composite. In contrast, in an advantageous alternative variant, it is also possible to introduce the edge protection film as a separate component, i.e., as a solid-phase material (e.g., film, adhesive film, etc.).

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. [Brief description of the drawings]

[0019] [Figure 1] 1A-1D are diagrams illustrating the construction and manufacture of an electrode stack / separator stack according to the present invention. [Figure 2a] 1A-1D are diagrams illustrating the construction and manufacture of an electrode stack / separator stack according to the present invention. [Figure 2b] 1A-1D are diagrams illustrating the construction and manufacture of an electrode stack / separator stack according to the present invention. [Figure 2c] 1A-1D are diagrams illustrating the construction and manufacture of an electrode stack / separator stack according to the present invention. [Figure 3a] 1A-1D are diagrams illustrating the construction and manufacture of an electrode stack / separator stack according to the present invention. [Figure 3b] 1A-1D are diagrams illustrating the construction and manufacture of an electrode stack / separator stack according to the present invention. [Figure 3c] 1A-1D are diagrams illustrating the construction and manufacture of an electrode stack / separator stack according to the present invention. [Figure 4] 1A-1D are diagrams illustrating the construction and manufacture of an electrode stack / separator stack according to the present invention. [Diagram 5]1A-1D are diagrams illustrating the construction and manufacture of an electrode stack / separator stack according to the present invention.

[0020] In FIG. 1, a completed electrode stack / separator stack for a battery cell is shown. It has, in stacking order from bottom to top, an anode A, a cathode K, and another anode A and cathode K, each with a separator S disposed therebetween. The anode A is shown alone in each of FIGS. 2a-c. The anode A is thus a rectangular sheet cut consisting of a substrate film 1. Both sides of the substrate film 1 are coated with active material 3. On one rectangular side, the substrate film 1 is extended outwards by an anode conductor strip 5.

[0021] The cathode K, according to Figs. 3a-3c, is likewise a rectangular sheet cut, which is formed from a substrate film 1 coated on both sides with active material 3. The substrate film 1 of the cathode K is extended on one rectangular side by a cathode conductor strip 7. Unlike the anode A, the cathode K shown in Figs. 3a-3c is not provided as an individual sheet before the lamination process is carried out. Rather, the cathode K together with the separator S is a constituent part of a laminated composite V, in which the separator S is laminated on the cathode K under pressure and heat on both sides, respectively.

[0022] In the completed electrode / separator stack (FIG. 1), all of the anode conductor strips 5 protrude from the left stack side, while all of the cathode conductor strips 7 protrude from the right stack side.

[0023] As can further be seen from Fig. 1, the anode A is dimensioned larger than the cathode K by a circumferential oversize a, for example 1-3 mm, which ensures the overlap of the anode A and the cathode K despite imprecise placement. Furthermore, the separator S and the anode A are realised as a joint sheet cut, i.e. they have the same area and the same contour, except for the anode conductor strip 5, so that in the electrode stack / separator stack (Fig. 1) the corners and edges of the anode A are aligned in the stacking direction with the corners and edges of the separator S.

[0024] In the laminated composite V, the two separators S protrude from the cathode K with the same protrusion as the oversized portion a. In this way, an edge side gap 9 is formed, which is defined by the separator protrusion a and the cathode K. The edge side gap 9 is completely filled with an edge protection film 11, which has the same material thickness as the cathode K when observed in the thickness direction of the laminated composite V. Each of the two separators S is formed with an adhesive layer 13, which allows the separator S to be laminated onto the cathode K under pressure and heat in a lamination process, thereby obtaining the laminated composite V.

[0025] The edge protection film 11 forms mechanical protection for the corners and edges of the laminated composite V. In addition, the edge protection film 11 acts as an electrical insulator preventing a direct contact connection between the anode A and the cathode K. In addition, the edge protection film 11 improves the shape stability of the laminated composite V at its corners and edges.

[0026] The edge protection film 11 is made of a polymer material. In order to avoid an unfavorable material combination between the active material binder, i.e., PVDF, and the edge protection film 11, the edge protection film 11 is also made of PVDF. This further ensures chemical durability against the electrolyte in the battery cell. It is emphasized that the present invention is not limited to the edge protection film 11 made of PVDF, but rather it is also possible to manufacture the edge protection film 11 from other suitable materials instead of PVDF.

[0027] The electrode / separator stack (FIG. 1) is manufactured in a lamination process and a subsequent alignment process (FIGS. 4 and 5). In the lamination process, the laminated composites V and the anodes A are stacked one on top of the other. Then, in the alignment process (FIGS. 4 and 5), a position correction is performed, in which the stack components, i.e., the laminated composites V and the anodes A, can be aligned in line with the other stack components by means of a slider 15. It is emphasized that the invention is not limited to the use of the slider 15 shown in the figures. Rather, the alignment can be performed via gravity, whereby the alignment can be performed in a self-centering manner. Alternatively, the alignment function can be realized by means of a vibrating plate with fixed stops.

[0028] An alignment force F is applied to the electrode / separator stack transversely to the stacking direction by means of a slider 15, possibly under the effect of gravity.

[0029] By the present invention, a satisfactory stacking accuracy can be achieved without relying on image processing and manipulation devices. Using inexpensive technology (i.e., slider 15), the stacking accuracy is brought to a high level. Moreover, the stacking accuracy can be adjusted after the stacking process, i.e., during the alignment process. [Explanation of symbols]

[0030] 1. Substrate film 3 Active materials 5 Anode conductor strip 7 Cathode conductor strip 9 Edge side gap 11 Edge protection film 13 Adhesive layer 15 Lateral stopper A Anode K cathode V Laminated Composite F Alignment Force a Oversized part, separator protrusion

Claims

1. An electrode stack / separator stack for a battery cell comprising at least an electrode, in particular a cathode (K), and a counter electrode, in particular an anode (A), The electrode (K) is a component of a laminated composite (V) in which one separator (S) is laminated on each side of the electrode (K), In an electrode stack / separator stack, the two separators (S) protrude from the electrodes (K) at their edge sides with protrusions (a), the edge side gap (9) between two of said separator projections (a) is in particular completely filled by an edge protection film (11), The edge protection film (11) and the electrode (K) have the same material thickness, in particular when observed in the thickness direction of the laminated composite (V); An electrode stack / separator stack comprising:

2. 2. The electrode stack / separator stack of claim 1, wherein each separator (S) has an adhesive layer (13) by means of which the separator (S) can be laminated onto the electrode (K) in a lamination process, in particular during which the laminated composite (V) is formed.

3. The electrode (K) and / or the counter electrode (A) are formed from a substrate film (1) having one or both sides coated with an active material (3), In particular, said active material (3) comprises a binder, in particular a polymeric binder, preferably PVDF, 3. An electrode stack / separator stack according to claim 1 or 2, in particular wherein the active material binder, the edge protection film (11) and / or the adhesive layer (13) are formed from the same material.

4. The laminated composite (V) is a rectangular planar cut portion, At one cut side of the cut, i.e. the conductor strip side, the substrate film (1) of the electrode (K) is extended laterally outwardly beyond the separator edge by conductor strips (5, 7), 4. The electrode stack / separator stack according to claim 1, wherein the edge side gap (9), in particular filled by the edge protection film (11), extends continuously at least along the cut side opposite the conductor strip (7), and in particular along two sides of the laminated composite (V) perpendicular to the conductor strip side.

5. 5. The electrode stack / separator stack of claim 4, wherein the edge side gap (9) filled by the edge protection film (11) extends circumferentially along all cut side surfaces of the laminated composite (V) except for the conductor piece side surface.

6. 6. The electrode stack / separator stack of claim 1, wherein the separator (S) and the counter electrode (A) are a congruent sheet cutout, i.e. have the same area and the same contour, except for the conductor piece (5) of the counter electrode (A), so that corners and edges of the counter electrode (A) can be aligned in line with the corners and edges of the separator (S) in the stacking direction.

7. The method of making the electrode stack / separator stack comprises: A lamination process is provided, in which the laminated composite (V) and the counter electrode (A) are not fixed and can be stacked on each other in a lamination direction, 7. The electrode stack / separator stack of claim 1, further comprising an alignment process, in which the laminated composite (V) and the counter electrode (A) can be aligned in line with each other in a stacking direction.

8. 8. The electrode stack / separator stack of claim 7, wherein the alignment process uses at least one lateral stop (15), in particular a slider, by means of which a stack component that is misaligned laterally with respect to the stacking direction, i.e. the laminated composite (V) or the counter electrode (A), can be aligned with another stack component.

9. 9. The electrode stack / separator stack according to claim 1, wherein the edge protection film (11) can be applied onto the laminated composite (V) in a coating process, in which a viscous base component of the edge protection film (11) can be applied directly to the edge side gap (9) of the laminated composite (V).

10. A method for producing an electrode stack / separator stack, in particular according to any one of claims 1 to 9, for a battery cell comprising at least an electrode, in particular a cathode (K), and a counter-electrode, in particular an anode (A), comprising: The electrode (K) is a component of a laminated composite (V) in which one separator (S) is laminated on each side of the electrode (K), A method for producing an electrode stack / separator stack, in which the two separators (S) protrude from the electrodes (K) at their edge sides with protrusions (a), the edge side gap (9) between two of said separator projections (a) is in particular completely filled by an edge protection film (11), The edge protection film (11) and the electrode (K) have the same material thickness, in particular when observed in the thickness direction of the laminated composite (V); 13. A method for producing an electrode stack / separator stack comprising:

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