Method for manufacturing a battery monocell, and method for manufacturing a battery.

Abstract

To provide a method for producing a monocell for a planar battery with sufficient stiffness for easy handling, without requiring lamination.SOLUTION: From a first foil, the shape of a coated portion of a first electrode is partially cut out along a cut-out lane. The first foil is inserted between separator sheets, where at least one pair of alignment openings in the separator sheets are mutually aligned to each other and aligned to an alignment opening in the first foil. A second foil is then placed on or under a first assembly, and an alignment opening in the second foil is aligned to the alignment openings in the first assembly. From a second assembly 28, a monocell is cut out according to a predefined shape.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present invention relates to a battery, and more particularly to a battery including a plurality of stacked battery cells.

Background Art

[0002] A battery cell includes two or more electrodes separated by a separator sheet. The cell can be manufactured by various manufacturing techniques including winding, folding, and stacking. According to the stacking technique, a plurality of monocells are stacked together, and each monocell includes a first electrode (usually a cathode) inserted between two separator sheets. The separator sheets are joined by heat or an adhesive along the periphery of the cathode, and then cut to form pockets having the same shape and dimensions as the anode. These pockets containing the cathode are then stacked alternately with the anode and placed in a metal container, and tabs extending from these electrodes are welded together for connection to the contacts of the battery. The container is filled with a liquid electrolyte before final sealing. Alternatively, the stacked cells may be integrated into an aluminum laminate pouch. A general advantage of a stacked cell battery is that such a battery can be manufactured in various shapes since the shape of the cell is not limited to a specific form.

[0003] Each pair of the cathode-containing pocket and the anode forms a monocell, and thus the battery includes a plurality of stacked monocells. However, as the size of the battery decreases, it becomes more difficult to control the position of the cathode between the separator layers. As a result, the accuracy and efficiency decrease as the cell size decreases. Furthermore, handling and alignment of individual monocells become more difficult as the size decreases.

[0004] An improved assembly method has been developed. In this method, the monocell is manufactured by placing a cathode sheet cut to the desired cell shape between continuous rolls of separator sheets, placing an anode sheet above or below it, bonding the sheets together while applying heat and pressure, and then cutting the monocell according to the desired shape. This increases the rigidity of the monocell and enables faster processing speeds.

[0005] However, not all types of separator sheets can be easily bonded together. Furthermore, the pressure and heat used in bonding can damage the separators and electrodes, potentially leading to undesirable results such as short circuits or insufficient electrolyte adsorption when the monocell is assembled into a battery. [Overview of the project]

[0006] The present invention relates to a method for manufacturing a monocell for a battery according to the appended claims. According to the method of the present invention, a cut pattern is manufactured on a first coated metal foil, a second coated metal foil, and a pair of separator sheets. The first foil is used to manufacture a first electrode, and the second foil is used to manufacture a second electrode of the monocell. The first electrode may be the cathode and the second electrode the anode, or vice versa. The present invention is summarized below in the first case (first electrode is the cathode, second electrode is the anode), but the terms cathode and anode may be reversed.

[0007] From the cathode foil, the shape of the cathode covering portion is partially cut along the cutting lane. This cut is partial in the sense that the covering portion remains attached to the foil at a predetermined position on the cathode tab. The cutting pattern of the first foil additionally includes alignment openings, while the cutting patterns of the anode foil and the pair of separator sheets also include their respective alignment openings. The cathode foil is inserted between the separator sheets, where at least one pair of alignment openings in the separator sheets are aligned with each other and with respect to the alignment openings in the cathode foil. The pair of separator sheets are then joined along the cutting lane to form a first assembly including a pocket that encloses the covered cathode portion. The anode foil is then placed above or below the first assembly, and the alignment openings in the anode foil are aligned with the alignment openings in the first assembly. The anode foil is attached to the first assembly to obtain a second assembly. From the second assembly, a monocell is cut according to a predetermined shape.

[0008] By leaving the covered cathode portion initially attached to the foil and by providing alignment openings for each, the correct positioning of the cathode foil between the pair of separator sheets becomes possible. By attaching the anode foil to the first assembly, it becomes possible to form a monocell with sufficient rigidity that is easy to handle without the need for lamination. [Brief explanation of the drawing]

[0009] [Figure 1] This shows a monocell suitable for manufacturing batteries using lamination techniques. [Figure 2a-2d] Figures 2a to 2d show the four components of the monocell shown in Figure 1. [Figure 3a-3b] The cutting patterns of the cathode foil, anode foil, and two separator sheets according to the first embodiment of the present invention are shown. [Figure 4a-4b]The cutting patterns of the cathode foil, anode foil, and two separator sheets according to the first embodiment of the present invention are shown. [Figures 5a-5b] The cutting patterns of the cathode foil, anode foil, and two separator sheets according to the first embodiment of the present invention are shown. [Figure 6] According to the first embodiment, Figures 3 to 5 show how the cut foils and sheets are assembled to form a monocell. [Figure 7] According to the first embodiment, Figures 3 to 5 show how the cut foils and sheets are assembled to form a monocell. [Figure 8] Figure 7 shows how the monocell is cut from the assembly obtained by the assembly steps shown. [Figure 9] Figures 3 to 8 show some modifications of the embodiments. [Figures 10a-10c] This shows cutting patterns applicable to continuous foil and separator sheets for applying the method of the present invention in a continuous production line. [Figures 11a-11b] The cutting patterns of the cathode foil and anode foil according to a second embodiment of the present invention are shown. [Figures 12a-12b] The cutting patterns of the cathode foil and anode foil according to a second embodiment of the present invention are shown. [Figures 13a-13b] The assembly of the monocell according to the second embodiment is shown. [Figures 14a-14c] This shows an alternative set of cutting patterns applicable to the method of the present invention, which is provided with additional alignment openings. [Modes for carrying out the invention]

[0010] Figure 1 shows a monocell 1 suitable for manufacturing a battery using the lamination method described above. The battery contains a certain number of stacked components, separately shown in Figures 2a to 2d. One of several electrodes is located at the bottom of the monocell. In this exemplary case, the anode 2 is shown in Figure 2a, but it may also be the cathode. The anode is formed from a coated metal foil including a coated electrode portion 3 and an uncoated tab 4. The anode coating may be a graphite coating in the case of a rechargeable lithium-ion battery. The tab 4 is integral with the anode foil; that is, the tab is the uncoated portion of the foil extending out from the coated portion 3. The anode is cut in a "D" shape, but this is merely one exemplary monocell shape. Other shapes are possible.

[0011] A pocket 11 is located at the top of anode 2. The pocket 11 includes first and second separator sheets, between which the cathode is inserted. The cathode 5 is shown in Figure 2c. The cathode 5 is formed from a metal foil having a coated portion 6 and an uncoated tab 7. In the case of a rechargeable lithium-ion battery, the cathode coating may contain lithium cobalt oxide or other lithium-based active ingredients. Separator sheets 8 and 9, shown separately in Figures 2b and 2d, are attached to each other along the periphery of the coated cathode portion 6 in an adhesion lane 10, indicated by a dotted line in Figure 1. The cathode tab 7 includes a portion 7a that is placed between separator sheets 8 and 9 and a portion 7b that extends out of the pocket 11 and is placed adjacent to the anode tab 4 in the assembled monocell. The outer periphery of the coated portion 3 of anode 2 corresponds to the outer periphery of the cathode-containing pocket 11.

[0012] According to the present invention, the monocell 1 shown in Figure 1 is assembled from sheets of material that have been pre-cut according to a specific pattern, then aligned and assembled. The present invention is described in the case of a D-shaped monocell, but is applicable to any monocell shape.

[0013] A first embodiment is shown in Figures 3 to 5. Figure 3a shows a rectangular cathode foil 14. This foil is a metal foil whose entire surface is covered with a cathode coating, except for a strip 16 along one side of the foil. That is, the strip 16 is formed from bare metal foil. The cathode foil 14 therefore includes a covered portion 15 and an uncovered portion 16. From this foil, as shown in Figure 3b, the covered portion 6 of the cathode is partially cut off by removing the covering foil material in a cutting lane 17 surrounding the shape of the covered portion 6. In addition, an alignment opening 18 is cut off from the uncovered strip 16 of the foil material, resulting in a cut portion including the cutting lane 17 and the alignment opening 18. The alignment opening completely covers a predetermined surface area of ​​the anode tab 4 at its predetermined position and extends to the left of the anode tab position. The covered cathode portion 6 remains attached to the foil at a predetermined position 19, which is a designated position of the cathode tab.

[0014] Figure 4a shows a rectangular anode foil 20 that equally includes the coated portion 21 and the uncoated strip 22. From this foil, a positioning opening 23a is cut to align with the uncoated strip 22, as shown in Figure 3b.

[0015] The left edges of both alignment openings 18 and 23a are positioned at the same distance from a predetermined anode tab position, thereby enabling final alignment, as will be further described in the text.

[0016] In addition to the alignment opening 23a, a tab opening 23b is cut from the anode foil 20 on the opposite side of the intended anode tab position. The width of the tab opening 23b is equal to the combined width of the cathode tab 7 and the gap between tabs 4 and 7 of the monocell. More generally, the tab opening 23b is sized to cover at least a predetermined surface area of ​​a portion 7b of the cathode tab 7 extending out of the pocket 11 at that predetermined location on the portion 7b.

[0017] Figure 5a shows a rectangular separator sheet 25. As shown in Figure 5b, an alignment aperture 26 is cut in the separator sheet 25. The height of the aperture 26 is equal to the height of the anode tab 4, and the width of the aperture 26 is equal to the combined width of the adjacent tabs 4 and 7, including the gap between the tabs, and the width of the alignment aperture 23a in the anode foil. Two separator sheets 25 are thus cut so as to have alignment apertures 26 of equal size. These sheets 25 are formed from materials that can adhere to each other under the influence of heat and / or light. For example, a polyethylene sheet and a polypropylene sheet can be heated and joined to each other in this way. All cutting steps for creating the cutout lanes and apertures may be performed, for example, by laser cutting.

[0018] Following these cutting steps, the separator sheet 25 and the cathode foil 14 are overlapped in the manner shown in Figure 6. In the overlapping image, the separator sheet 25 is shown in a perspective view. The cathode foil 14 is disposed between two separator sheets 25, and the alignment apertures 26 of equal size in the separator sheets 25 are aligned with each other. The left edge of the alignment aperture 18 is aligned with the left edge of the alignment aperture 26. When the cathode foil 14 and these separator sheets 25 are thus aligned, these separator sheets contact each other along the cutout lane 17. These separator sheets are joined in the area corresponding to the cutout lane 17 when pressed and heated, for example, by a physical heater or a laser, thus forming an assembly 27. The cutout lane 17 here becomes the adhesion lane 10 shown in Figure 1. The assembly 27 includes a pocket 11 that contains the covered cathode portion 6. The covered cathode portion 6 is fixed at the adhesion lane 10 by the joining between the pair of separator sheets 25 and is sandwiched between the separator sheets 25, while remaining attached to the cathode foil 14 at a predetermined position 19 of the cathode tab.

[0019] Referring to FIG. 7, the cut anode foil 20 is then placed under the assembly 27 of the separator sheet and the cathode foil. The left edge of the alignment opening 23a is aligned with the left edges of the alignment openings 18 and 26 in the assembly 27. The overlay image in FIG. 7 shows the separator sheet in a perspective view, similar to the cathode and anode foils, to visualize the alignment of the openings 18, 23a, and 26. The anode foil 20 is then attached by a suitable adhesive to a pocket including the cut coating portion 6 of the cathode, thereby forming a further assembly 28. Thereafter, the single cell 1 is cut from the assembly 28 along the cutting line 29 shown in FIG. 8, for example by laser cutting.

[0020] By partially cutting the cathode, that is, by leaving the cathode attached to the foil 14 at the tab position 19 before joining these separator layers 25, and by providing alignment openings 18, 26 that enable correct alignment between the cathode foil 14 and the separator sheet 25, correct positioning of the cathode between the separator sheets is ensured regardless of the dimensions of the cathode. The alignment opening 23a in the anode foil further enables correct alignment of the electrodes with each other. By arranging the openings 18, 23a, 26 relative to the predetermined positions of the tabs, it is further allowed to cut the single cell along a single cutting line 29 after assembling the various foils and sheets. Since all the components of the single cell are attached, a highly rigid single cell that is easy to handle can be obtained without the need to laminate multiple constituent layers.

[0021] Some modifications of the embodiments described above will be explained with reference to Figure 9, which shows an alternative cutting pattern for the cathode foil 14. Here, the cathode foil includes an alignment opening 18a and a tab opening 18b. The tab opening 18b is integrated with the cutting lane 17 and covers a predetermined surface area of ​​the anode tab 4 at its predetermined position. The cutting patterns for the anode foil 20 and the separator sheet 25 are the same as in the previous embodiment. The only difference from the previous embodiment is that the alignment opening 18a of the cathode foil 14 is physically separated from the tab opening 18b. This indicates the more general principle of this embodiment, namely, that both foils 14, 20 and both separator sheets 25 are provided with matching alignment openings, and these alignment openings allow the foils and sheets to be superimposed and aligned by aligning each alignment opening along at least one edge of the opening (the left edge in the illustrated embodiment).

[0022] The tab openings 18b and 23b are provided not for alignment purposes, but to allow the final assembly to be cut out in a single cutting step that yields the required monocell shown in Figure 1. For this purpose, the tab opening 18b in the cathode foil 14 must cover at least a predetermined surface area of ​​the anode tab 4 at its predetermined location, and the tab opening 23b in the anode foil 20 must cover at least a predetermined surface area of ​​the cathode tab portion 7b that extends out of the pocket 11 at its predetermined location.

[0023] Therefore, the embodiments shown in Figures 3 to 7 are special cases in which the alignment opening 18a and the tab opening 18b in the cathode foil 14 form a single continuous opening 18. This opening 18 may be referred to as an "alignment opening" even though it serves two functions: alignment and enabling the monocell to be cut in a single cutting step.

[0024] According to one embodiment, alignment openings 18a, 23a, and 26 are provided in the cathode foil and anode foil, as well as in the separator sheet, but tab openings may not be provided. In that case, in order to obtain the required monocell, it is necessary to cut the assembly 28 along the cutting line 29, and then cut off the tab-shaped portions of the cathode foil and anode foil.

[0025] Similarly, the alignment openings 26 in the separator sheet 25 may have the same shape and size as the alignment openings 18a and 23a in these foils, and the shape and position of the tabs may not be considered. In that case, in order to obtain the required monocell, it is necessary to cut the assembly 28 along the cutting line 29 and then cut off the portion of the separator sheet remaining between the tabs.

[0026] The method of the present invention is suitable for manufacturing multiple monocells and batteries in a continuous process. Figures 10a to 10c show repeated cutting patterns in a continuous roll of cathode foil 14 (Figure 10a), anode foil 20 (Figure 10b), and two separator sheets 25 (Figure 10c). Since each of the above-described cutting patterns is repeated at regular distances from each other, it becomes possible to continuously position and assemble various components in the manner described above.

[0027] Further embodiments are shown in Figures 11 and 12. These figures show the cutting patterns of the cathode foil 14 and anode foil 20. The cutting pattern of the separator sheet 25 is the same as in the previous embodiment, namely the cut-out openings 26. The rectangular cathode foil 14 and anode foil 20 shown in Figures 11a and 12a are here completely coated; that is, there are no uncoated metal strips along both sides of the foil. Therefore, in the areas corresponding to the tabs, the coating is locally removed. This is shown in Figures 11b and 12b. These figures show the cathode tab area 40 and anode tab area 41, respectively. Local removal of the coating can be performed by laser ablation. The cutting patterns of the cathode foil 14 and anode foil 20 are the same as in the first embodiment, namely the cut-out lines 17 and alignment openings 18 (a combination of alignment openings and tab openings) of the cathode foil 14, and the alignment openings 23a and tab openings 23b of the anode foil 20. The coating in the tab area may be removed before or after the cutting operation. Figure 13a shows how the cathode foil is inserted between two separator sheets and aligned with the two separator sheets to obtain the first assembly 27. Figure 13B shows how the first assembly is aligned with the anode foil to obtain the second assembly 28 before cutting the monocell along the same cutting line 29 shown in Figure 8.

[0028] Figures 14A and 14B show embodiments in which additional openings are provided on the opposite side of the electrodes. In the illustration, this is a mirror copy 18' of the first alignment opening 18, and mirror copies 23a' and 26' of the alignment openings 23a and 26. These additional openings are included purely for alignment purposes and do not form part of the ultimately cut monocell. The presence of these openings improves alignment before bonding the separator sheets and before bonding the anode foil to the first assembly.

[0029] The present invention is applicable to rechargeable and non-rechargeable planar batteries of any shape and size that are realistically feasible. A planar battery according to the present invention can be obtained by stacking monocells manufactured by a method according to any embodiment of the present invention in a container, connecting the tabs of the first and second electrodes of the monocells to their respective battery contacts, and closing and sealing the container.

Claims

1. A method for manufacturing a monocell (1) for a planar battery, The monocell includes first and second electrodes (5, 2), each electrode including a covered metal foil portion (6, 3) and an uncovered metal tab (7, 4), the covered metal foil portion and the metal tab having predetermined positions relative to each other and having predetermined shapes and predetermined surface areas, the first electrode (5) being sandwiched between two separator sheets (8, 9) attached to each other along an adhesion lane (10) extending along the periphery of the covered metal foil portion (6) of the first electrode, except for the position (19) of the metal tab (7) of the first electrode, the separator sheets (8, 9) forming a pocket (11) into which the covered metal foil portion (6) of the first electrode is inserted, a portion (7b) of the first metal tab (7) of the first electrode extending out of the pocket (11), and the second electrode (2) being attached to the pocket (11), The aforementioned method, - A step of providing first and second metal foils (14, 20), wherein each foil includes a coating containing the respective chemical components of the first and second electrodes, - A step of partially cutting off the covered metal foil portion (6) of the first electrode in the first metal foil (14) by removing the foil material in a cutting lane (17) extending along the periphery of the predetermined shape, wherein the covered metal foil portion (6) of the first electrode remains attached to the first metal foil (14) at the predetermined position (19) of the metal tab (7) of the first electrode (5), - A step of cutting out the first alignment opening (18, 18a) in the first metal foil (14), - A step of cutting out a second alignment opening (23a) in the second metal foil (20), - A step of providing first and second separator sheets (25) and cutting at least one pair of alignment openings (26) in each of the first and second separator sheets, - The steps of inserting the cut first metal foil (14) between the first and second separator sheets (25) such that the separator sheets (25) face each other along the cutting lane (17), aligning the pair of alignment openings (26) of the separator sheets with each other, and aligning it with the first alignment openings (18, 18a) in the first metal foil (14), - Subsequently, the separator sheets (25) are attached to each other along the cutting lane (17) to obtain a first assembly (27) including the pocket (11) that encloses the partially cut-out covered metal foil portion (6) of the first electrode (5), - The step of aligning the second metal foil (20) with the first assembly (27) such that the second alignment opening (23a) in the second metal foil (20) aligns with the pair of alignment openings (26) in the separator sheet (25) and with the first alignment openings (18, 18a) in the first metal foil (14), - Subsequently, the second metal foil (20) is attached to the first assembly (27) to obtain the second assembly (28), - A step of cutting the second assembly (28) along a cutting line (29) that conforms to the outer shape of the adhesion lane (10) and the metal tabs (7, 4) Methods that include...

2. - A step of cutting out a first tab opening (18b) in the first metal foil before inserting the first metal foil (14) between the separator sheets (25), wherein the first tab opening covers at least a predetermined surface area of ​​the metal tab (4) of the second electrode (2) at the predetermined position, - A step of cutting out a second tab opening (23b) in the second metal foil before aligning the second metal foil (20) with the first assembly (27), wherein the second tab opening covers at least the predetermined surface area of ​​the portion (7b) of the first metal tab (7) that extends out of the pocket (11) at the predetermined position of the portion (7b) of the first metal tab (7) and The method according to claim 1, including the method described in claim 1.

3. The method according to claim 2, wherein the alignment opening and the first tab opening (18b) in the first metal foil form a single continuous opening (18).

4. The method according to claim 1, wherein one of the pair of alignment openings (26) in the separator sheet (25) covers the predetermined surface area of ​​the metal tab (4) of the second electrode (2) and the portion (7b) of the metal tab of the first electrode (5) that extends out of the pocket (11).

5. The method according to claim 1, wherein the first and second metal foils (14, 20) are rectangular foils having a covered portion (15, 21) and an uncovered strip (16, 22) along one side of the foil, and the cutting lane (17) and the first and second alignment openings (18, 18a, 23a) are formed such that the metal tabs (7, 4) of the monocell are formed from the material of the uncovered strip (16, 22), and the covered metal foil portion (6, 3) of the monocell is formed from the covered portion (15, 21) of the foil.

6. The method according to claim 1, wherein the first and second metal foils (14, 20) are completely coated foils, and the method includes an additional step of removing the coating of each foil in areas (40, 41) corresponding to at least the predetermined surface area of ​​the metal tab (7, 4) at the predetermined location on the metal tab (7, 4).

7. The method according to claim 1, wherein the alignment openings (18, 18a, 23a, 26) in the first and second metal foils (14, 20) and the separator sheet (25) are rectangular in shape.

8. A plurality of monocells (1) are manufactured according to the method of claim 1, The aforementioned monocells are stacked inside a container, Connecting the metal tabs (7, 4) of the first and second electrodes (5, 2) of the monocell to their respective battery contacts, To close and seal the aforementioned container A method of manufacturing batteries.

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