Apparatus for coupling electrode tabs of a semi-finished electrochemical cell and method thereof

Abstract

An apparatus (10) for coupling electrode tabs (7) of an electrochemical cell semi-finished product (1) comprises a pressing mechanism (20) movable in a transverse direction between a resting configuration and a pressing configuration, wherein in said pressing configuration said pressing mechanism (20) is configured to press together in the transverse direction said tabs (7) and wherein said pressing mechanism (20), when in the pressing configuration, defines a gap (40), extended in a longitudinal direction, comprising an end opening (41) and configured to contain said pressed tabs (7); a punch (50) movable in the longitudinal direction in at least one compacting position in which the punch (50) is inserted in said gap (40) through said end opening (41), wherein in the compacting position the punch (50) is configured to press at least some tabs (7) of said plurality of tabs (7) in the longitudinal direction.

Description

[0001] "Apparatus for coupling electrode tabs of a semi-finished electrochemical cell and method thereof"

[0002] The present invention relates to an apparatus for coupling electrode tabs of an electrochemical cell semi-finished product and a method for coupling electrode tabs of an electrochemical cell semi-finished product.

[0003] In the production of certain types of electric accumulators, such as lithium batteries made up of prismatic or pouch-type cells, flat electrode portions, alternately positive and negative, are superimposed on each other along a transverse direction with separating layers of dielectric material, generally referred to in the industry's technical jargon as "separators", also in the form of flat portions.

[0004] The flat portions of the electrodes and separators can be formed from single stacked sheets or portions of a folded or wound web defining multiple flat portions.

[0005] In the first type of electrolytic cells, both electrodes and separators are formed from a plurality of individual flat sheets, stacked one on top of the other by alternating positive and negative electrode sheets and interposing a separator sheet between each successive positive and negative electrode sheet.

[0006] In a second type of electrolytic cells, the electrodes are formed by a plurality of single flat sheets, superimposed on one another by alternating positive and negative electrode sheets, the separators are formed by a single web folded between the electrode sheets to interpose a flat portion of the separator web between each successive positive and negative electrode sheet.

[0007] In a third type of electrolytic cells, the positive electrode is in the form of a positive electrode web, the negative electrode is in the form of a negative electrode web and the separators are in the form of two separator webs. The webs are superimposed by alternating the separator webs with the electrode webs and wound onto a flat winding support so that flat portions of the positive electrode, negative electrode and separator are superimposed on one other in an alternating manner and curved connecting portions between the flat portions.

[0008] The electrodes are substantially made by depositing a layer of electrode active material on one surface or both surfaces of a current collector metal foil. By choosing a suitable combination of active material for electrodes and of material of the current-collecting metal sheet, it is possible to obtain electrode precursors intended for making positive electrodes and electrode precursors intended for making negative electrodes.

[0009] The electrode precursors are then cut into individual square or rectangular sheets or webs of a predetermined size, depending on the type of electrolytic cell to be made. Similarly, the separator sheets are cut in the form of square or rectangular sheets or webs of a predetermined size depending on the type of electrolytic cell to be made.

[0010] Electrochemical cells are produced in a known way. For example, for the first type of electrolytic cell described above, the positive and negative electrode sheets are stacked, arranging them on top of each other alternately and separated from each other by separator sheets. For the second type of electrolytic cell described above, the positive and negative electrode sheets are stacked, arranging them on top of each other alternately, and the separator web is folded so that flat portions of the separator sheet are interposed between each positive and negative electrode pair. For the second type of electrolytic cell described above, two separator webs and a positive electrode web and a negative electrode web are superimposed, alternating the separator webs with the electrode webs, and wound onto a flat winding support.

[0011] To connect the flat portions of the electrodes made as described above to the respective battery terminals, each flat portion is provided with a tab. Tabs are usually portions of the metal foil of the electrodes on which no active material is deposited. The metal foil is cut to define both the electrode and the tab.

[0012] This produces an electrolytic cell semi-finished product comprising flat electrode portions superimposed on each other along a transverse direction, with flat separator portions in between, from which electrode tabs protrude in electrical continuity with the respective flat electrode portions. The tabs of the positive electrode flat portions are superimposed with each other, e.g. at one longitudinal end of the semi-finished product, and the tabs of the negative electrode flat portions are superimposed with each other and offset from the tabs of the positive electrode flat portions, e.g. at an opposite longitudinal end of the semi-finished product.

[0013] When the electrolytic cell semi-finished product is manufactured, the tabs are placed on top of each other, separated from each other by an empty space having a thickness essentially equal to the sum of the thicknesses of two separator sheets and one electrode sheet.

[0014] Conventionally, to make the terminals of the electrolytic cell, to which the battery's electrical contacts are to be connected, the tabs are placed next to each other in a coupling plane, parallel to, or coinciding with, a centreline plane of the electrolytic cell semi-finished product. Tabs offset from the coupling plane are folded so that a proximal portion of the tab converges towards the coupling plane, and folded so that a distal portion of the tab is oriented parallel to the coupling plane. In this way, the distal portions of the tabs are in contact with each other at the coupling plane. Due to the different distance of each tab from the coupling plane, the lengths of the proximal and distal portions vary with the distance of each tab from the coupling plane. More specifically, the length of the proximal portion increases in proportion to the distance of each tab from the coupling plane, and consequently the length of the distal portion decreases with the distance of each tab from the coupling plane. Therefore, the longitudinal ends of the tabs thus coupled are offset longitudinally.

[0015] To temporarily fasten the tabs next to each other, an initial welding, known as "prewelding", is carried out to join them together. Subsequently, the tabs are cut at the distal portion to equalise their respective ends longitudinally, in an operation known as "trimming". Next, the electrical terminals intended to form the poles of the electrolytic cell are soldered to the soldered and equalised tabs. These operations are carried out for the positive electrode tabs and for the negative electrode tabs.

[0016] The Applicant has found that cutting the tabs to even out their longitudinal ends produces scraps and dust in conductive materials, which if not properly handled risk penetrating between the electrodes and creating quality problems.

[0017] The Applicant also found that the blades used to cut the tabs are subject to wear and tear and that, at the relatively high production rates typical of electrolytic cells, blades may have to be replaced relatively frequently, leading to downtimes and increased costs.

[0018] The Applicant therefore perceived that, if cutting the tabs was not performed, scrap and particulate matter would be avoided and replacement of the blades would not be required. The present invention therefore relates, in a first aspect thereof, to an apparatus for coupling electrode tabs of an electrochemical cell semifinished product of the type comprising flat electrode portions superimposed on each other along a transverse direction, wherein a plurality of electrode tabs are superimposed on each other in a transverse direction at a longitudinal end of the semi-finished product.

[0019] Preferably, a movable pressing mechanism is provided in the transverse direction between a resting configuration and a pressing configuration.

[0020] Preferably, in said pressing configuration, said pressing mechanism is configured to press said tabs together in the transverse direction.

[0021] Preferably, said pressing mechanism, when in the pressing configuration, defines a gap, extended in a longitudinal direction, comprising an end opening and configured to contain said pressed tabs.

[0022] Preferably, there is provided a punch movable in the longitudinal direction in at least one compacting position.

[0023] Preferably, in the compacting position, the punch is inserted into said gap through said end opening.

[0024] Preferably, in the compacting position, the punch is configured to press at least some tabs of said plurality of tabs in the longitudinal direction.

[0025] In a second aspect thereof, the present invention relates to a method for coupling electrode tabs of electrochemical cells comprising.

[0026] Preferably, an electrochemical cell semi-finished product is provided of the type comprising flat electrode portions superimposed on each other along a transverse direction, wherein a plurality of electrode tabs are superimposed on each other in the transverse direction at a longitudinal end of the semi-finished product. Preferably, said tabs are pressed together in the transverse direction, and preferably at the same time, said pressed tabs are housed in a gap extended in the longitudinal direction.

[0027] Preferably, at least some tabs of said plurality of tabs are pressed in the longitudinal direction into said gap through an end opening of said gap.

[0028] The Applicant found that by housing the tabs in a gap, pressing the tabs in the transverse direction and then pressing the tabs in the longitudinal direction with a punch, the longitudinal ends of the tabs, offset from each other, are compacted within the gap, getting crumpled.

[0029] The Applicant found that the tabs thus compacted remain joined together and can subsequently be welded to the battery terminals without requiring cutting.

[0030] A "flat portion" is defined as a portion of material having two dimensions much larger than a third dimension, e.g. at least two orders of magnitude, preferably at least four. Such a portion may be a distinct object, such as a flat sheet, or a portion of a complex object, such as a portion of a web comprising multiple portions.

[0031] A "punch" is defined as a body elongated in at least one main direction and intended to be pressed against a material and configured to cause permanent deformation in that material without itself undergoing permanent deformation.

[0032] The term "longitudinal direction", when used in reference to the electrochemical cell semi-finished product, means a direction parallel to the flat electrode portions of the semi-finished product. When used with reference to the apparatus for coupling electrode tabs of an electrochemical cell semi-finished product, the term "longitudinal direction" means a direction parallel to the movement direction of the punch. In use, the apparatus for coupling electrode tabs requires the electrolytic cell semi-finished product to be arranged in a predetermined position with the respective flat portions parallel to the movement direction of the punch. Therefore, the longitudinal direction of the semifinished product coincides with the longitudinal direction of the apparatus.

[0033] Terms such as "longitudinal", "longitudinally" and the like are used with reference to directions parallel to the longitudinal direction or to quantities measured parallel to the longitudinal direction.

[0034] The term "transverse direction", when used in reference to the electrochemical cell semi-finished product, means a direction perpendicular to the flat electrode portions of the semi-finished product. When used with reference to the apparatus for coupling electrode tabs of an electrochemical cell semi-finished product, the term "transverse direction" means a direction perpendicular to the movement direction of the punch. In use, the transverse direction of the semi-finished product coincides with the transverse direction of the apparatus. The transverse direction is perpendicular to the longitudinal direction.

[0035] Terms such as "transverse", "transversely" and the like are used with reference to directions parallel to the transverse direction or to quantities measured parallel to the transverse direction.

[0036] The present invention may have, in one or both of its aspects, at least one of the preferred features described below. Such features may be present individually or in combination with each other, unless expressly stated otherwise, both in the apparatus and in the method of the present invention.

[0037] Preferably, a support is configured to support said electrolytic cell semifinished product in a predetermined position with said flat electrode portions oriented in the longitudinal direction.

[0038] Preferably, locking devices are provided. The locking devices are configured to lock said semi-finished product onto said support in said predetermined position.

[0039] Preferably, said pressing mechanism comprises a first block comprising a first gap surface.

[0040] Preferably, said pressing mechanism comprises a second block with a second gap surface facing the first gap surface of the first block.

[0041] Preferably, said first block and second block are movable towards and away from each other between said resting configuration and said pressing configuration.

[0042] Preferably, in the pressing configuration said first gap surface and said second gap surface are maintained at a predetermined distance defining said gap.

[0043] Preferably, said first gap surface is flat.

[0044] Preferably, said first gap surface is flat.

[0045] Preferably, said pressing mechanism comprises an abutment surface.

[0046] Preferably, said second block has said abutment surface.

[0047] Preferably, said abutment surface is contiguous to said second gap surface.

[0048] Preferably, said abutment surface is coplanar to said second gap surface.

[0049] Preferably, in the pressing configuration said abutment surface is configured to abut said plurality of tabs. Preferably, said tabs extend from the respective flat electrode portions to respective longitudinal ends.

[0050] Preferably, said tabs comprise respective proximal portions.

[0051] Preferably, said tabs comprise respective intermediate portions.

[0052] Preferably, said tabs comprise respective distal portions.

[0053] Preferably, said proximal portions extend between the respective flat electrode portions and the intermediate portions of the respective tabs.

[0054] Preferably, said intermediate portions extend between the proximal portions of the respective tabs and the distal portions of the respective tabs.

[0055] Preferably, said distal portions extend between the intermediate portions of the respective tabs and the longitudinal ends of the respective tabs.

[0056] Preferably, said pressing mechanism comprises a clamping member configured to transversely press respective intermediate portions of said tabs towards said abutment surface in the pressing configuration.

[0057] Preferably, said clamping member is configured to longitudinally block said intermediate portions while said punch moves towards the compacting position to press distal portions of said tabs.

[0058] Preferably, said clamping member comprises a clamping surface.

[0059] Preferably, said clamping surface is arranged longitudinally adjacent to said first gap surface.

[0060] Preferably, said clamping surface protrudes transversely towards the abutment surface with respect to the first gap surface. Preferably, said punch is shaped like a plate.

[0061] Preferably, said punch comprises an end surface configured to engage at least some of said tabs.

[0062] Preferably, said punch has a first longitudinal sliding surface configured to slide against said first gap surface.

[0063] Preferably, said punch has a second longitudinal sliding surface configured to slide against said second gap surface.

[0064] Preferably, said end surface extends from the first longitudinal sliding surface to the second longitudinal sliding surface.

[0065] Preferably, said punch is configured to stop at the compacting position when said end surface is at, or substantially at, or in proximity to said clamping surface.

[0066] Preferably, said end surface faces said support configured to support the electrolytic cell semi-finished product.

[0067] Preferably, said clamping device is movably mounted on said first block.

[0068] Preferably, said clamping device is rotatably mounted on said first block.

[0069] Preferably, said pressing mechanism comprises a pressing member mounted between the clamping member and the first block.

[0070] Preferably, said pressing member is configured to exert pressure against said clamping member in the pressing configuration to press said clamping surface towards said abutment surface.

[0071] Preferably, said pressing member is of the elastic type.

[0072] Preferably, said plurality of tabs comprises a first tab, a second tab and a plurality of intermediate tabs interposed between the first tab and the second tab.

[0073] Preferably, said tabs are placed in a transverse succession and the first tab and the second tab are respectively the first and last of said succession.

[0074] Preferably, said clamping surface is configured to abut against a first tab of said plurality of tabs.

[0075] Preferably, said clamping surface is configured to compress said pressing member when the pressing mechanism moves from the resting configuration to the pressing configuration.

[0076] Preferably, the end surface of said punch is concave, preferably with a circumferential arc shape in cross-section.

[0077] Preferably said cross-sectional shape is seen in a sectional plane parallel to said longitudinal direction and said transverse direction.

[0078] Preferably said gap has a predetermined transverse extension.

[0079] Preferably said punch has a thickness measured in the transverse direction that is smaller than the transverse extension of the gap by a value comprised between 0 pm and 10 pm, preferably between 2 pm and 8 pm, more preferably between 3 pm and 7 pm, even more preferably between 4 pm and 6 pm, for example about 5 pm.

[0080] Preferably an applicator is provided.

[0081] Preferably said applicator is configured to apply a junction element to said plurality of tabs.

[0082] Preferably said junction element comprises a first portion in the form of a plate. Preferably said junction element comprises a second portion in the form of a plate.

[0083] Preferably said junction element comprises a joining potion between the first portion and the second portion.

[0084] Preferably said applicator is configured to interpose said plurality of tabs between the first portion and the second portion of the junction element.

[0085] Preferably said applicator is configured to press said first portion and said second portion of the junction element towards each other against said plurality of tabs to plastically deform said joining portion.

[0086] Preferably said junction element is a plate folded in a V-shape.

[0087] Preferably, said joining portion has a concave surface.

[0088] Preferably, the concave surface of the joining portion is substantially the same shape as the end surface of the punch.

[0089] Preferably, a welder is provided, preferably a laser welder, configured to weld together said first portion of the junction element, said plurality of tabs, and said second portion of the junction element.

[0090] The Applicant found that in this way the welding has satisfactory results as the junction element prevents the formation of drops of molten material on the tabs and the sublimation of the tab material.

[0091] Preferably, a pair of folders is provided, transversely movable independently of said pressing mechanism towards and away from each other between a resting position, in which said folders do not engage said tabs and a folding position in which said folders engage said tabs to fold said tabs towards a longitudinal coupling plane.

[0092] Preferably, said folders are configured to engage the proximal portion of said tabs.

[0093] Preferably, pressing said tabs together in the transverse direction is carried out by means of said pressing mechanism.

[0094] Preferably, pressing said tabs together in the transverse direction comprises pressing said intermediate portions of said tabs together in order to longitudinally block said intermediate portions.

[0095] Preferably, transversely pressing respective intermediate portions of said tabs to longitudinally block said intermediate portions is carried out by means of said clamping member.

[0096] Preferably, housing said pressed tabs in a gap comprises housing said distal portions of said tabs in said gap.

[0097] Preferably, pressing at least some tabs of said plurality of tabs in a longitudinal direction is carried out by means of said punch.

[0098] Preferably, pressing at least some tabs of said plurality of tabs in the longitudinal direction comprises pressing said distal portions of said tabs.

[0099] Preferably, pressing said tabs together in a transverse direction comprises keeping a thickness of said gap greater than or equal to a sum of thicknesses of said tabs in an undeformed condition.

[0100] Preferably, applying said junction element to said plurality of tabs is provided.

[0101] Preferably, applying said junction element to said plurality of tabs comprises interposing said plurality of tabs between the first portion and the second portion of the junction element.

[0102] Preferably, applying said junction element to said plurality of tabs comprises pressing said first portion and said second portion towards each other against said plurality of tabs to plastically deform said joining portion.

[0103] Preferably, applying said junction element to said plurality of tabs is carried out by means of said applicator.

[0104] Preferably, welding together said first portion, said tabs and said second portion is provided.

[0105] Preferably, in the pressing configuration, the clamping surface is arranged longitudinally between said first gap surface and said support.

[0106] Preferably, a movable frame is provided on which said pressing mechanism and punch are mounted, whereby said movable frame is movable longitudinally between a distal position and a proximal position with respect to said support.

[0107] Further characteristics and advantages of the present invention will become clearer from the following detailed description of a preferred embodiment thereof, with reference to the appended drawings and provided by way of indicative and non-limiting example, in which:

[0108] - Figure 1 shows a schematic sectional view of an electrochemical cell semi-finished product of the type comprising flat electrode portions superimposed on each other along a transverse direction;

[0109] - Figure 2 shows a sectional view of an apparatus for coupling electrode tabs of an electrochemical cell semi-finished product made according to the present invention.

[0110] - Figure 3 shows an enlarged view of the apparatus in Figure 2;

[0111] - Figure 4 shows a schematic end section view of the semi-finished product in Figure 1 comprising a plurality of tabs folded towards a longitudinal coupling plane;

[0112] - Figure 5 shows a detail of the apparatus in Figure 2 in a different operating configuration;

[0113] - Figure 6 shows an enlarged view of the apparatus in Figure 5;

[0114] - Figure 7 shows a detail of the apparatus in Figure 2 in a different operating configuration;

[0115] - Figure 8 shows an enlarged view of the apparatus in Figure 7;

[0116] - Figure 9 shows a detail of the apparatus in Figure 2 in a different operating configuration;

[0117] - Figure 10 shows an enlarged view of the apparatus in Figure 9;

[0118] - Figure 11 shows a detail of the apparatus in Figure 2 in a different operating configuration.

[0119] The representations in the accompanying figures are not necessarily intended to be in scale and do not necessarily respect the proportions between the various parts.

[0120] A sectional view of a semi-finished product 1 for the construction of an electrolytic cell is schematically illustrated in Figure 1. The semi-finished product 1 comprises a positive and a negative electrode, separated by separators.

[0121] Both the positive electrode and the negative electrode, themselves known, comprise a shaped metal foil on which a layer of active electrode material is deposited. The positive and negative electrode foils have a thickness comprised between 5 pm and 20 pm, preferably between 7 pm and 16 pm, even more preferably between 8 pm and 14 pm, e.g. 10 pm. The separators are in the form of sheets or webs of dielectric material, which are also themselves known, of a thickness comprised between 10 pm and 30 pm, preferably between 15 pm and 25 pm, even more preferably between 18 pm and 22 pm, e.g. 20 pm.

[0122] The positive electrode, the negative electrode and the separators comprise flat portions 2, 3, 4 placed alternately on top of each other. Without loss of generality, the flat portions 2, 3, 4 can be formed from single stacked sheets or from portions of a folded or wound web defining multiple flat portions.

[0123] In a first embodiment of the semi-finished product 1, the positive electrode and the negative electrode each comprise a plurality of individual electrode sheets 2, 3, stacked alternately to form a stack of electrode sheets. The separators comprise a plurality of individual separator sheets 4 interposed with the electrode sheets 2, 3 in such a way that each electrode sheet 2, 3 is separated from the adjacent electrode sheets 2, 3 of opposite polarity by a separator sheet 4.

[0124] In a second embodiment of the semi-finished product 1, the positive electrode and the negative electrode each comprise a plurality of individual electrode sheets 2, 3 stacked alternately to form a stack of electrode sheets 2, 3. The separators are formed by a single separator web folded in a zig-zag pattern between the electrode sheets to define a plurality of flat portions of separator web 4 connected by folds of the separator web, so that each electrode sheet 2, 3 is separated from adjacent electrode sheets of opposite polarity by respective flat portions of separator web 4.

[0125] In a third embodiment, the positive electrode is in the form of a positive electrode web, the negative electrode is in the form of a negative electrode web, and the separators are in the form of two separator webs. The webs are superimposed by alternating the separator webs with the electrode webs and wound in such a way as to create flat portions of positive electrode 2, negative electrode 3, and separator 4 superimposed with each other and curved connecting portions between the flat portions 2, 3, 4.

[0126] The semi-finished product 1 defines a centreline plane M parallel to the electrode flat portions 2, 3 and separator flat portions 4. The centreline plane M is placed in the middle, in the transverse direction, of the semifinished product 1.

[0127] The semi-finished product 1 comprises a plurality of positive electrode tabs 5 and a plurality of negative electrode tabs 6. Each positive electrode tab 5 is connected to a respective positive electrode flat portion 2. Each negative electrode tab 6 is connected to a respective negative electrode flat portion 3. Preferably, the positive electrode tabs 5 and negative electrode tabs 6 are formed by seamlessly shaped portions of the metal foil of the respective electrodes. The positive electrode tabs 5 and negative electrode tab 6 are not coated with active electrode material.

[0128] The positive electrode tabs 5 of the semi-finished product 1 protrude longitudinally from the electrode flat portions 2, 3 and separator flat portions 4 and are superimposed on each other transversely. Similarly, the negative electrode tabs 6 of the semi-finished product 1 protrude longitudinally from the electrode flat portions 2, 3 and separator flat portions 4 and are superimposed on each other transversely. The positive electrode tabs 5 are spaced from the negative electrode tabs 6 so that they are electrically isolated from each other. In the illustrated embodiment, the positive electrode tabs 5 are arranged at a longitudinal end la of the semi-finished product 1 and the negative electrode tabs 6 are arranged at an opposite longitudinal end lb of the semi-finished product 1. The positive electrode tabs 5 and the negative electrode tabs 6 are conceptually similar. In the remainder of this description and in the appended claims the expression "plurality of tabs 7" will refer to tabs 7 superimposed transversely with one other, which may be either positive electrode tabs 5 or negative electrode tabs 6.

[0129] No other components of the semi-finished product 1, such as separators or electrodes, are interposed between the tabs 7. Each pair of adjacent tabs 7 is spaced from each other by the thickness of two separator flat portions 4 and one electrode flat portion 2; 3.

[0130] Each tab 7 extends longitudinally from a respective electrode flat portion of 2; 3 to a longitudinal end 7a. Each tab 7 comprises a proximal portion 8a, adjacent to the respective electrode flat portion 2; 3, and extended towards the respective longitudinal end 7a, a distal portion 8b extended from the longitudinal end 7a towards the proximal portion 8a, and an intermediate portion 8c extended between the proximal portion 8a and the distal portion 8b.

[0131] The plurality of tabs 7 comprises a first tab 9 and a second tab 9b. The first tab 9a and the second tab 9b are the two tabs 7 placed at the respective transverse ends of the plurality of tabs 7. The plurality of tabs 7 further comprises a plurality of intermediate tabs 9c transversely interposed between the first tab 9a and the second tab 9b.

[0132] An apparatus 10 for coupling electrode tabs of an electrochemical cell is illustrated in Figure 2. The apparatus 10 comprises a support 11 configured to support a semi-finished product 1 of the type described above in a predetermined configuration. In the embodiment shown, the support 11 is movable along a production line. The support 11 comprises a support plane 12. In use, the semi-finished product 1 is placed on the support plane 12 with the respective positive electrode flat portions 2, negative electrode flat portions 3 and separator flat portions 4 parallel to the support plane 12. The support plane is parallel to the longitudinal direction.

[0133] Clamping devices 13 are also provided, configured to clamp the semifinished product 1 on the support plane 12. In the form illustrated, the clamping devices 13 comprise two pressers 14 configured to press the semi-finished product 1 against the support plane.

[0134] The following description refers to components of the apparatus 10 configured to couple together a plurality of tabs 7, which may be positive electrode tabs 5 or negative electrode tabs 6. In the embodiment illustrated, the apparatus 10 comprises components similar to those described and configured to couple together the opposite polarity electrode tabs of the semi-finished product 1, which will not be further described.

[0135] The apparatus 10 comprises a pair of folders 15 movable towards each other in a transverse direction between a resting position and a folding position. Each folder 15 comprises a folding body 16 extended in a transverse direction and a contact portion 17 configured to contact a respective tab 7. In the embodiment illustrated, the contact portion 17 is a roller.

[0136] In the resting position, the contact portions 17 of the two folders 15 are offset from each other. In the folding position, the contact portions 17 are pressed towards each other in a longitudinal coupling plane P. In the embodiment shown, the coupling plane P corresponds to the centreline plane M.

[0137] The folders 15 are configured to contact the proximal portions 8a of the first tab 9a and the second tab 9b and to fold the proximal portions 8a of the tabs 7 by placing the tabs 7 against each other at the respective intermediate portions 9c and distal portions 9b. The proximal portions 8a are folded towards the coupling plane P and the intermediate portions 9c and distal portions 9b are placed against each other at the coupling plane P.

[0138] As shown in Figure 4, as a result of the folding, the ends 7a of the tabs 7 are longitudinally misaligned. The extension of the proximal portions 8a folded towards the coupling plane P depends on their distance from the coupling plane P, and the longitudinal extension of the intermediate portions 9c and distal portions 9b, is lower the greater the original distance of the tab 7 from the coupling plane P.

[0139] The apparatus 10 comprises a pressing mechanism 20, configured to press the tabs 7 together, preferably the distal portions 9 placed against each other of the tabs 7.

[0140] The pressing mechanism 20 comprises a movable frame 21, movable longitudinally on one or more longitudinal guides 22.

[0141] The pressing mechanism 20 comprises a first block 23 movable transversely to the movable frame 21. The first block 23 comprises a first gap surface 24 extended longitudinally. The first gap surface 24 is flat.

[0142] The pressing mechanism 20 further comprises a clamping device 25 mounted on the first block 23. The clamping member 25 is movable in relation to the first block 23. In the embodiment illustrated, the clamping member 25 is hinged to the first block 23 and is rotatable about an axis of rotation R. The axis of rotation R is perpendicular to both the longitudinal and transverse directions.

[0143] The clamping device 25 comprises a clamping surface 26 facing the folding plane P. The clamping surface 26 extends in a substantially longitudinal direction. The clamping surface 26 is adjacent to the first gap surface 24. The clamping surface 26 is longitudinally interposed between the support 11 (and, in the operating configuration, to the electrodes 2, 3 and separators 4 of the semi-finished product 1) and the first gap surface 24. A rotation of the clamping device 25 about the axis of rotation R. results in a transverse movement of the clamping surface 26.

[0144] A pressing member (not shown), preferably of the elastic type, is placed between the clamping member 25 and the first block 23. The pressing device is configured to exert a force against the clamping device 25 to press the clamping surface 26 towards the coupling plane P.

[0145] The pressing mechanism 20 comprises a second block 30 movable transversely relative to the movable frame 21 towards and away from the first block 23. The second block 30 comprises a second, longitudinally extended gap surface 31. The second gap surface 31 faces the first gap surface 24. The second gap surface 31 is parallel to the first gap surface 24. The second block 30 further comprises an abutment surface 32. The abutment surface 32 faces the clamping surface 26. The abutment surface 32 is contiguous, and preferably coplanar, to the second gap surface 31.

[0146] The pressing mechanism 20 further comprises a stop member 35 configured to stop the first block 23 and the second block 30 at a predetermined, preferably adjustable, distance. In the illustrated embodiment, the stop member 35 comprises a screw 36 in threaded coupling with the first block 23. A stop body 37 is mounted in threaded coupling on the second block 30. The screw 36 is configured to abut against the stop body 37 to stop the first block 23 and the second block 30 at the predetermined distance.

[0147] The pressing mechanism 20 is movable in the transverse direction between a resting configuration and a pressing configuration.

[0148] In the resting configuration, the pressing mechanism 20 does not engage the tabs 7. In the pressing configuration, the pressing mechanism 20 is configured to press the tabs 7 together in the transverse direction.

[0149] In the resting configuration, the clamping member 25 is kept by the pressing member in a position where the clamping surface 26 protrudes from the first gap surface 24 towards the abutment surface 32.

[0150] The first block 23 and the second block 30 are movable in the transverse direction between the resting configuration and the pressing configuration. In the pressing configuration, the first block 23 and the second block 30 are closer together than in the resting configuration. Furthermore, in the pressing configuration, the first block 23 and the second block 30 are closer to the coupling plane P than in the resting configuration.

[0151] In the pressing configuration, a gap 40 extended in the longitudinal direction is defined between the first gap surface 24 and the second gap surface 31. The gap 40 runs along the coupling plane P, preferably symmetrically. The gap 40 has an end opening 41. The end opening 41 is open at a longitudinal end of the gap 40, on the opposite side with respect to the clamping surface 26.

[0152] The gap 40 has a transverse extension at least an order of magnitude smaller than its longitudinal extension. The transverse extension of the gap 40 is adjustable, preferably by adjusting the stop member 35.

[0153] The transverse extension of the gap 40 is comprised between 0.2 mm and 1 mm, preferably between 0.3 mm and 0.8 mm, more preferably between 0.4 mm and 0.6 mm, even more preferably between 0.45 mm and 0.55 mm, e.g. approximately 0.50 mm. The gap 40 is configured to house the tabs 7, in particular the distal portions 8b of the tabs 7. The gap 40 is configured to house the tabs 7 without substantially exerting pressure on them in the transverse direction through the first gap surface 24 and the second gap surface 31.

[0154] In the pressing configuration, the clamping member 25 presses the tabs

[0155] 7 against the abutment surface 32 with a predetermined force. The clamping surface 26 is placed in abutment against the intermediate portion 8c of the first tab 9a. The intermediate portion 8c of the second tab is placed in abutment against the abutment surface 32. The intermediate tabs 9c are pressed between the first tab 9a and the second tab 9b at the respective intermediate portions 8c by the clamping member 25. The pressure exerted by the clamping member 25 is generated by the spring-loaded pressing member moving the first block 23 towards the second block 30 and bringing the clamping surface 26 in abutment against the tabs 7.

[0156] The pressure exerted by the clamping device 25 against the tabs 7 keeps the intermediate portion 8c of the tabs in a fixed position in the longitudinal direction.

[0157] The apparatus 10 further comprises a 50 punch. The punch 50 is mounted on a movable punch frame 51 in the longitudinal direction. The punch 50 is shaped like a plate extended in the longitudinal direction. The punch 50 is oriented parallel to the coupling plane P. The punch 50 has a thickness, measured in the transverse direction, less than the thickness of gap 40. The difference in thickness between the punch 50 and the gap 40 is comprised between 0 pm and 10 pm, preferably between 2 pm and

[0158] 8 pm, more preferably between 3 pm and 7 pm, even more preferably between 4 pm and 6 pm, e.g. approximately 5 pm. Preferably, the thickness of the punch 50 is essentially equal to the sum of the thicknesses of the tabs 7.

[0159] The punch 50 has a depth, measured in a direction perpendicular to the longitudinal direction and the transverse direction, greater than or equal to the depth of the tabs 7.

[0160] The punch 50 comprises a concave end surface 52. The end surface 52 faces the support 11. In use, the end surface 52 faces the tabs 7. In the embodiment illustrated, the end surface 52 has a circumferential arc shape in cross-section.

[0161] The punch 50 is movable longitudinally between a resting position, illustrated in Figures 5 and 6, and a compacting position, illustrated in Figures 7 and 8, while the pressing mechanism 20 is in the pressing position.

[0162] In the resting position, the punch does not engage the tabs 7 inside the gap 40. Preferably, in the resting configuration, the punch 50 is outside the gap 40.

[0163] In the compacting configuration, the punch 50 engages the tabs 7 to compact them. Moving from the resting position towards the compacting position, the punch 50 enters the gap 40 through the end opening 41 and slides into the gap 40 towards the support 11 (and, in the operating configuration, to the electrodes and separators of the semi-finished product 1).

[0164] Moving from the resting position to the compacting position, the punch 50 intercepts the ends 7a of the tabs 7 and compacts the distal portions 8b by pressing them longitudinally towards the respective intermediate portions 8c. In particular, the punch 50 compacts the distal portions 8b crumpling them. The punch 50 contacts the distal portions 8b at the end surface 52. By pressing the crumpled distal portions 8b, the punch 50 stamps a counter-shape on the distal portions 8b of the tabs 7 to the end surface. In the embodiment illustrated, the punch 50 stamps a rounded shape on the distal portions 8b, preferably a circumferential arc shape when viewed in cross-section.

[0165] The punch 50 stops in the compacting position, with the end surface 52 at the clamping surface 26.

[0166] The punch 50 is configured to exert a pressure against the distal portions 8b of the tabs 7 such as to compact them, so that they occupy substantially all the space in the gap 40 not occupied by the punch 50 itself.

[0167] The punch 50 is controlled so as to exert a predetermined pressure against the tabs 7, preferably adjustable. The punch is made of a material with physical characteristics such that it does not undergo permanent deformation while exerting maximum pressure against the tabs 7 in the compacting position.

[0168] The pressure exerted by the clamping device 25 against the intermediate portions 8c in the transverse direction is such that longitudinal sliding of the intermediate portions 8c is prevented while the punch 50 presses the tabs 7 longitudinally towards the compacting position. Preferably, the pressure exerted by the clamping member 25 against the intermediate portions 8c is at least one order of magnitude, preferably at least two orders of magnitude, greater than a pressure exerted by the first gap surface 24 or the second gap surface 31 against the plurality of tabs 7.

[0169] The apparatus 10 further comprises an applicator 60 configured to apply a junction element 61 to the plurality of pressed and compacted tabs 7. The junction element 61 comprises a V-shaped folded plate made of conductive material, preferably metal. This plate has a thickness comprised more preferably between 0.10 mm and 0.50 mm, preferably between 0.15 mm and 0.40 mm, more preferably between 0.20 mm and 0.30 mm, even more preferably between 0.23 mm and 0.27 mm, e.g. approximately 0.25 mm.

[0170] The junction element 61 comprises a first portion 62 in the form of a plate, a second portion 63 in the form of a plate, inclined with respect to the first portion 62, and a joining portion 64 between the first portion 62 and the second portion 63. The first portion 62 and the second portion 63 form an acute angle. The first portion 62 the second portion 63 and the joining portion 64 are made in a single piece. The joining portion 64 preferably has a curved surface 65 facing between the first portion 62 and the second portion 63. The curved surface 65 is concave. Preferably, the curved surface 65 is substantially the same shape as the end surface 52 of the punch 50.

[0171] The applicator 60 comprises an applicator frame 70 movable in the longitudinal direction.

[0172] The applicator 60 comprises a first support portion 71 configured to contact the joining portion 64 of the junction element 61. The first support portion 71 is mounted on the applicator frame 70 and is movable longitudinally relative to the applicator frame 70 between a support position and a resting position.

[0173] The applicator 60 further comprises a second support portion 72 configured to contact a free end of the first portion 62, distal to the joining portion 64, and a third support portion 73 configured to contact a free end of the second portion 63, distal to the joining portion 64. The second support portion 72 and the third support portion 73 are mounted on the applicator frame 70 and are movable transversely with respect to the applicator frame 70 towards and away from each other between a support position, illustrated in Figures 9 and 10, and an application position, illustrated in Figure 11.

[0174] The applicator 60 can be configured in a support configuration, in which it stably supports the junction element 61 by contacting it with the first support portion 71, the second support portion 72 and the third support portion 73, all three in the support position.

[0175] In the support configuration, the applicator 60 can bring the junction element 61 to the previously pressed and compacted tabs 7 by longitudinally translating the applicator frame 70 towards the tabs 7, so as to interpose the tabs 7 between the first portion 62 and the second portion 63, as illustrated in Figures 9 and 10.

[0176] The joining portion 64 of the junction element 61 can thus be brought to a longitudinal end of the pressed and compacted tabs 7.

[0177] Preferably, the longitudinal end of the tabs 7 has a curved surface, stamped by the end surface 52 of the punch, counter-shaped to the curved surface 65 of the junction element 61.

[0178] The applicator 60 can also be configured in an application configuration. Moving from the support configuration to the application configuration, the second support portion 72 and the third support portion 73 move towards each other, plastically deforming the junction element 61 so as to reduce the angle between the first portion 62 and the second portion 63. The second support portion 72 and the third support portion 73 stop in the application configuration, in which the first portion 62 and the second portion 63 are clamped on the tabs 7 and substantially parallel to the coupling plane P.

[0179] The apparatus 10 may also include a welder, not illustrated, preferably a laser welder. The welder is configured to weld together the first portion 62 of the junction element 61, the tabs 7 and the second portion 63, following the application of the junction element 61.

Claims

CLAIMS1. Apparatus (10) for coupling electrode tabs (7) of an electrochemical cell semi-finished product (1) of the type comprising flat electrode portions (2; 3) superimposed on each other along a transverse direction, wherein a plurality of electrode tabs (7) are superimposed on each other in the transverse direction at a longitudinal end (la; lb) of the semifinished product (1), the apparatus (10) comprising: a pressing mechanism (20) movable in the transverse direction between a resting configuration and a pressing configuration, wherein in said pressing configuration said pressing mechanism (20) is configured to press together in the transverse direction said tabs (7) and wherein said pressing mechanism (20), when in the pressing configuration, defines a gap (40), extended in a longitudinal direction, comprising an end opening (41) and configured to contain said pressed tabs (7); a punch (50) movable in the longitudinal direction in at least one compacting position in which the punch (50) is inserted in said gap (40) through said end opening (41), wherein in the compacting position the punch (50) is configured to press at least some tabs (7) of said plurality of tabs (7) in the longitudinal direction.

2. Apparatus (10) according to claim 1, wherein said pressing mechanism (20) comprises: a first block (23) comprising a first gap surface (24); a second block (30) comprising a second gap surface (31) facing the first gap surface (24) of the first block (23); wherein said first block (23) and second block (30) are movable towards and away from each other between said resting configuration and said pressing configuration, and wherein in the pressing configuration said first gap surface (23) and said second gap surface (30) are kept at a predetermined distancedefining said gap (40).

3. Apparatus (10) according to claim 1 or 2, wherein said pressing mechanism (20) further comprises: an abutment surface (32), wherein in the pressing configuration said abutment surface (32) is configured to abut said plurality of tabs (7); and a clamping member (25) configured to transversely press respective intermediate portions (8c) of said tabs (7) towards said abutment surface (32) in the pressing configuration to longitudinally block said intermediate portions (8c) while said punch (50) moves towards the compacting position to press distal portions (8b) of said tabs (7) extended from said intermediate portions (8c) to respective longitudinal ends (7a) of said tabs (7).

4. Apparatus (10) according to claims 2 and 3, wherein said clamping member (25) comprises a clamping surface (26) longitudinally adjacent to said first gap surface (24), and wherein said clamping surface (26) projects transversely towards the abutment surface (32) with respect to the first gap surface (24).

5. Apparatus (10) according to claim 4 wherein said punch (50) comprises an end surface (52) configured to engage at least some of said tabs (7), and wherein said punch (50) is configured to stop in the compacting position when said end surface (52) is at said clamping surface (26).

6. Apparatus (10) according to claim 4 or 5, wherein said clamping member (25) is movably mounted on said first block (23) and wherein said pressing mechanism (20) comprises a pressing member mountedbetween the clamping member (25) and the first block (23) and configured to exert a pressure against said clamping member (25) in the pressing configuration to press said clamping surface (26) towards said abutment surface (32).

7. Apparatus (10) according to claim 6, wherein said pressing member is of the elastic type and wherein said clamping surface (26) is configured to abut against a first tab (9a) of said plurality of tabs (7) and compress said pressing member when the pressing mechanism (20) moves from the resting configuration to the pressing configuration.

8. Apparatus (10) according to any one of the preceding claims, wherein said punch (50) comprises an end surface (52) configured to engage at least some of said tabs (7) by moving towards the compacting position, and wherein said end surface (52) is concave, preferably with a circumferential arc shape in cross-section.

9. Apparatus (10) according to any one of the preceding claims, wherein said gap (40) has a predetermined transverse extension and said punch (50) has a thickness measured in the transverse direction that is smaller than the transverse extension of the gap (40) by a value comprised between 0 pm and 10 pm, preferably between 2 pm and 8 pm, more preferably between 3 pm and 7 pm, even more preferably between 4 pm and 6 pm, for example about 5 pm.

10. Apparatus (10) according to any one of the preceding claims, comprising an applicator (60) configured to apply a junction element (61), comprising a first portion (62) in the form of a plate, a second portion (63) in the form of a plate and a joining portion (64) between the first portion (62) and the second portion (63), to said plurality of tabs (7),wherein said applicator (60) is configured to interpose said plurality of tabs (7) between the first portion (62) and the second portion (63) of the junction element (61) and press said first portion (62) and said second portion (63) towards each other against said plurality of tabs (7) to plastically deform said joining portion (64)11. Apparatus according to claim 10, comprising a welder, preferably a laser welder, configured to weld together said first portion (62) of the junction element, said plurality of tabs (7), and said second portion (63) of the junction element (61).

12. Apparatus according to any one of the preceding claims further comprising a pair of folders (15) transversely movable independently of said pressing mechanism (20) towards and away from each other between a resting position, in which said folders (15) do not engage said tabs (7) and a folding position in which said folders (15) engage said tabs (7) to fold said tabs (7) towards a longitudinal coupling plane (P).

13. Method for coupling electrochemical cell electrode tabs comprising: providing an electrochemical cell semi-finished product (1) of the type comprising flat electrode portions (2;3) superimposed on each other along a transverse direction, wherein a plurality of electrode tabs (7) are superimposed on each other in the transverse direction at a longitudinal end (la; lb) of the semi-finished product (1); pressing said tabs (7) together in the transverse direction and at the same time housing said pressed tabs (7) in a gap (40) extended in a longitudinal direction, pressing at least some tabs (7) of said plurality of tabs (7) in the longitudinal direction in said gap (40) through an end opening (41) of said gap (40).

14. Method according to claim 13, wherein: pressing said tabs (7) together in the transverse direction comprises transversely pressing respective intermediate portions (8c) of said tabs (7) to longitudinally block said intermediate portions (8c); housing said pressed tabs (7) in a gap (40) comprises housing in said gap (40) distal portions (8b) of said tabs (7) extended from said intermediate portions (8c) to respective longitudinal ends (7a) of said tabs (7); pressing at least some tabs (7) of said plurality of tabs (7) in the longitudinal direction comprises pressing said distal portions (8b) of said tabs (7).

15. Method according to claim 13 or 14, wherein pressing said tabs (7) together in the transverse direction comprises keeping a thickness of said gap (40) greater than or equal to a sum of thicknesses of said tabs (7) in an undeformed condition.

16. Method according to any one of claims 13 to 15 comprising applying a junction element (61), comprising a first portion (62) in the form of a plate, a second portion (63) in the form of a plate and a joining portion (64) between the first portion (62) and the second portion (63), to said plurality of tabs (7), by interposing said plurality of tabs (7) between the first portion (62) and the second portion (63) of the junction element (61) and by pressing said first portion (62) and said second portion (63) towards each other against said plurality of tabs (7) to plastically deform said joining portion (64).

17. Method according to claim 16 comprising welding together said first portion (62), said tabs (7) and said second portion (63).

Images