Method for forming an electrochemical cell of an electric battery - Patents.com
By forming multi-layer strips directly from unwound electrode and separator sheets on a conveyor, the manufacturing process for cylindrical electrochemical cells is streamlined, addressing inefficiencies and safety concerns, resulting in improved production efficiency and reduced costs.
Patent Information
- Application Number
- JP2024566315
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-05-10
- Filing Date
- 2023-05-09
- Publication Date
- 2025-05-20
AI Technical Summary
The existing manufacturing process for cylindrical electrochemical cells, such as those used in electric vehicles, is inefficient and costly due to the need for unwinding, cutting, and rewinding of large mother coils into daughter coils, which requires significant temporary storage space and manual intervention, leading to bottlenecks and safety risks.
A method and apparatus that forms multi-layer strips directly from unwound electrode and separator sheets from mother coils on a conveyor, eliminating the need for daughter coils by simultaneously feeding these sheets to a winding device, allowing for automated and efficient assembly of electrochemical cells.
This approach reduces manufacturing time, minimizes storage needs, and enhances safety by automating the assembly process, thereby increasing production efficiency and reducing manual intervention.
Smart Images
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Abstract
Description
[Technical field]
[0001] The present invention relates to a method for forming an electrochemical cell of an electric battery. [Background technology]
[0002] Some types of electric batteries, such as those commonly used in electric vehicles, have a hollow container within which is an electrochemical cell formed of an anode and a cathode separated by an electrolyte membrane.
[0003] Lithium-ion cylindrical electric batteries commonly employ a cylindrical electrochemical cell known as a "jelly roll" or "Swiss roll". Such an electrochemical cell is composed of four layers of material in the form of a thin foil or sheet. The four layers typically include a cathode layer (hereinafter also simply referred to as "cathode") made of an oxide of an element such as lithium and a metal such as nickel, manganese, or cobalt, an anode layer (hereinafter also simply referred to as "anode"), e.g., graphite, and two separator layers (hereinafter also simply referred to as "separators"), e.g., made of an electrically insulating porous polymer membrane, arranged alternately to separate the cathode layer from the anode layer.
[0004] The multi-layer product thus constructed is then wound upon itself to form a jellyroll.
[0005] In a conventional cylindrical electrochemical cell, two conductive terminals called "tabs" are welded to either side of the cathode and anode to create the positive and negative poles of the electric battery. Recently, a type of cylindrical electrochemical cell called "tabless" has been devised in which the side edges of the anode and cathode are bent to act as terminals, eliminating the need for welding terminals.
[0006] There are standards for the sizes of cylindrical electrochemical cells. The most common sizes are the 1865 (18 mm diameter, 65 mm axial length) and 2170 (21 mm diameter, 70 mm axial length) for traditional tab cells, and the 4680 (46 mm diameter, 80 mm axial length) for "tabless" cells.
[0007] To manufacture this type of cell, the anode, cathode and separator are manufactured on a large scale in the form of continuous sheets wound into individual coils known as "mother coils" with axial dimensions of one or more meters.
[0008] The mother coil is then unwound and the individual sheets are cut longitudinally into strips of transverse width equal to the axial length of the electrochemical cell being fabricated, which are then individually rewound into smaller coils known as "daughter coils."
[0009] The daughter coils are processed to remove impurities, for example by vacuum drying, and transported to a dry environment under controlled environmental conditions for final assembly of the electrochemical cell.
[0010] Each daughter coil is unwound and the unwound strips from the daughter coils of anode, cathode, and separator are simultaneously fed, typically by hand, along different directions to a winding device, placing first the cathode (or anode), then the separator, then the anode (or cathode), and finally another separator on the winding device, thus creating a jelly roll.
[0011] Terminals are then welded to the cathode and anode, and the jelly roll is placed into a hollow cylindrical container filled with the electrolyte solution in liquid form, sealed, and subjected to subsequent forming, degassing, aging, and testing steps.
[0012] The Applicant has found that the above manufacturing process is costly in terms of manufacturing efficiency, especially when large scale is involved. Indeed, the Applicant has found that manufacturing the mother coil, unwinding and cutting the mother coil into strips, rewinding the strips into daughter coils, unwinding the daughter coils and assembling the electrochemical cells on their respective winding devices requires holding time at the manufacturing plant for each of the above coils. Therefore, significant temporary storage space needs to be provided.
[0013] Moreover, in the applicant's opinion, the simultaneous winding of four strips onto a winding device is a delicate operation, requiring a high degree of precision as well as a high degree of vigilance on the part of the operator manually feeding said strips onto the winding device to prevent the risk of injury, thus creating a bottleneck in the production process and limiting the number of electrochemical cells that can be produced in a given time frame.
[0014] The applicant has determined that the above manufacturing process can be improved.
[0015] Indeed, the applicant has realised that if said strips are fed onto a conveyor before being individually wound onto a winding device to create multi-layer strips which are automatically fed to the winding device, the need to feed individual strips to the winding device is avoided, thus eliminating the aforementioned bottleneck and reducing the risk of injury to workers.
[0016] According to the applicant, each multi-layer strip may be formed on the conveyor by cutting the electrode and separator sheets unwound from the mother coil into parallel strips either before or immediately after placement on the conveyor, thus eliminating the need for daughter coils and saving manufacturing time and storage space. Summary of the Invention
[0017] Thus, in a first aspect, the present invention relates to a method of forming an electrochemical cell of an electric battery.
[0018] Preferably, a coil is provided having a winding of a first separator sheet.
[0019] Preferably, a coil is provided having turns of the first electrode sheet.
[0020] Preferably, a coil is provided having turns of the second electrode sheet.
[0021] Preferably, the sheets are fed to the conveyor by being unwound from respective coils.
[0022] Preferably, the sheets are fed to the conveyor by being unwound from respective coils.
[0023] Preferably, a plurality of multi-layer strips are formed on a conveyor.
[0024] Preferably, each multi-layer strip comprises a first layer of the first separator sheet, a second layer of the first electrode sheet, a third layer of the second separator sheet, and a fourth layer of the second electrode sheet.
[0025] Preferably, the second layer overlies said first layer.
[0026] Preferably, a third layer overlies said second layer.
[0027] Preferably, a fourth layer overlies said third layer.
[0028] Preferably, said conveyor is movable along a feed direction.
[0029] Preferably, each multi-layer strip is fed by said conveyor to a respective winding device.
[0030] Preferably, each multi-layer strip is wound on a respective winding device.
[0031] In a second aspect thereof, the present invention relates to an apparatus for forming an electrochemical cell of an electric battery.
[0032] Preferably, a service area is provided.
[0033] Preferably, the service area is configured to support a coil having a winding of the first separator sheet.
[0034] Preferably, the service area is configured to support a coil having turns of the first electrode sheet.
[0035] Preferably, the service area is configured to support a coil having a winding of the second separator sheet.
[0036] Preferably, the service area is configured to support a coil having turns of the second electrode sheet.
[0037] Preferably, a conveyor is provided.
[0038] Preferably, the conveyor is configured to support a plurality of multi-layer strips.
[0039] Preferably, each multi-layer strip comprises a first layer of said first separator sheet.
[0040] Preferably, each multi-layer strip comprises a second layer of said first electrode sheet.
[0041] Preferably, each multi-layer strip comprises a third layer of said second separator sheet.
[0042] Preferably, each multi-layer strip comprises a fourth layer of said second electrode sheet.
[0043] Preferably, said second layer overlies said first layer.
[0044] Preferably, said third layer overlies said second layer.
[0045] Preferably, said fourth layer overlies said third layer.
[0046] Preferably, said conveyor is movable along a feed direction.
[0047] Preferably, downstream of said conveyor relative to said feed direction a number of winding devices are arranged.
[0048] Preferably, each of said winding devices is configured to receive a respective multi-layer strip.
[0049] In this way, the multi-layer strip is made directly from the electrode sheets and separator sheets unwound from the mother coil, and in this way the multi-layer strip can be fed to a winding device without making daughter coils.
[0050] The multi-layer strips are formed on a conveyor that moves along a feed direction to move the multi-layer strips towards respective winding devices, such that all the multi-layer strips move simultaneously in the same direction towards the winding device.
[0051] In this manner, the manufacture of the electrochemical cell requires less operator intervention and can be more easily automated.
[0052] As used herein, terms such as "horizontal," "horizontally," "lower," and "upper" are used in reference to spatial orientation of the device of the present invention in its configuration for use.
[0053] The term "ambient ambient conditions" is used to refer to conditions in which the surrounding air has not been treated with a dehumidification system. The term "dry ambient conditions" is used to refer to controlled environmental conditions with reduced or further reduced humidity as specified in ISO 7.
[0054] The term "sheet" is used to refer to a body having a thickness of less than 0.5 mm, preferably less than 0.2 mm.
[0055] The electrode sheets and separator sheets referred to herein have a predominant dimension that defines a longitudinal direction, which, when the electrode sheets and separator sheets are placed on a conveyor, is parallel to the feed direction of the conveyor.
[0056] The terms "transverse" or "transversely" are used to refer to a direction inclined to the longitudinal direction, preferably perpendicular to the longitudinal direction, and perpendicular to the dimension along which the thickness of the sheet is measured.
[0057] The coils and electrochemical cells referred to herein are essentially cylindrical in shape.
[0058] The terms "axial" or "axially" are used to refer to a direction parallel to the winding axis of a coil or electrochemical cell.
[0059] The terms "radial" or "radially" are used to refer to a direction perpendicular to the axis of a coil or electrochemical cell.
[0060] The present invention, in one or more of its aspects, may comprise at least one of the preferred features described below, which may be provided individually or in any combination with one another, unless expressly stated otherwise.
[0061] Preferably, the conveyor is located below the service area.
[0062] Preferably, the first electrode sheet comprises an anode (or cathode) material.
[0063] Preferably, the second electrode sheet comprises a cathode (or anode) material.
[0064] Preferably, the plurality of parallel strips of each of said sheets are formed by cutting each of said respective sheets longitudinally.
[0065] Preferably, the multiple parallel strips of each of said sheets are formed as the sheet is fed towards the conveyor.
[0066] Preferably, a plurality of parallel strips of each of said sheets are formed prior to forming said plurality of multi-layer strips on a conveyor.
[0067] Preferably a first cutting member is provided.
[0068] Preferably, the first cutting member is located between the service area and a conveyor.
[0069] Preferably, the first cutting member is configured to cut each of the sheets longitudinally into parallel strips.
[0070] Preferably, the parallel strips of the first separator sheet are laid on the conveyor first, then the parallel strips of the first electrode sheet, then the parallel strips of the second separator sheet, then the parallel strips of the second electrode sheet.
[0071] In this manner, the order of layers forming the electrochemical cell is determined.
[0072] Preferably, multiple longitudinal pieces of the multi-layer strip are formed.
[0073] Preferably, multiple longitudinal pieces of the multi-layer strip are formed prior to winding each multi-layer strip on a respective winding device.
[0074] Preferably, winding each multi-layer strip on a respective winding device comprises winding each of said longitudinal pieces on a respective winding device.
[0075] Preferably, forming said plurality of longitudinal pieces of multi-layer strip comprises periodically transversely cutting each of said sheets.
[0076] Preferably, said longitudinal pieces of the multi-layer strip are all of the same length.
[0077] In a preferred embodiment, each of the sheets is periodically transversely cut prior to placing the parallel strips on a conveyor.
[0078] In an alternative embodiment, the electrode sheet is periodically cut transversely before the parallel strips are placed on the conveyor, and the separator sheet strip is periodically cut transversely after being placed on the conveyor and before being wound on a winding device.
[0079] In a preferred embodiment, each of the sheets is periodically transversely cut after forming the parallel strips.
[0080] In an alternative embodiment, each of the sheets is periodically transversely cut prior to forming the parallel strips.
[0081] Preferably, a second cutting member is provided.
[0082] In a preferred embodiment, a second cutting member is disposed between the service area and the conveyor.
[0083] Preferably the second cutting member is configured to periodically cut transversely through each said sheet.
[0084] Preferably, the second cutting member is located at or adjacent to the first cutting member.
[0085] In an alternative embodiment, a second cutting member for cutting the electrode sheet is disposed between the service area and the conveyor, and a second cutting member for cutting the separator sheet is disposed between the conveyor and the winding device.
[0086] In one embodiment, the feeding of the strip of electrode sheet to the conveyor may be temporarily stopped or slowed down before and / or after the electrode sheet is periodically cut transversely to create a gap between two successive longitudinal pieces of electrode sheet on the conveyor.
[0087] In this way, for each piece of the multi-layer strip formed, a longitudinal piece of the separator sheet projects longitudinally from a longitudinal piece of the electrode sheet, and the electrochemical cell so formed has a periphery formed only by the separator sheet, which serves to separate the electrode sheets.
[0088] Preferably, the parallel strips of the first electrode sheet are laid on the conveyor at a transversely offset position relative to the parallel strips of the first separator sheet to create protruding side edges of the first electrode sheet in each multi-layer strip.
[0089] Preferably, the parallel strips of the second separator sheet are placed on the conveyor at a position transversely offset relative to the parallel strips of the first electrode sheet.
[0090] Preferably, the parallel strips of the second electrode sheet are placed on the conveyor at a position transversely offset relative to the parallel strips of the first and second separator sheets.
[0091] Preferably, parallel strips of the second electrode sheet are laid on the conveyor opposite the protruding side edge of the first electrode sheet to create a protruding side edge of the second electrode sheet in each multi-layer strip.
[0092] The protruding side edges form electrical terminals for the electrodes of the electrochemical cell in a "tabless" configuration after winding of the electrochemical cell.
[0093] Preferably, before winding each multi-layer strip onto a respective winding device, the protruding side edge of the first electrode sheet is bent longitudinally.
[0094] Preferably, before winding each multi-layer strip onto a respective winding device, the protruding side edge of the second electrode sheet is bent longitudinally.
[0095] Preferably, a plurality of bending members is provided.
[0096] Preferably, the bending members are arranged parallel to one another above said conveyor along a direction parallel to said feed direction.
[0097] Preferably, the bending members are configured to intercept respective side edges of said multi-layer strip.
[0098] In this way, the aforementioned bending of the side edges takes place continuously during the movement of the conveyor along the feed direction.
[0099] Preferably, the plurality of bending members includes first bending members, each first bending member configured to intercept a protruding side edge of a respective first electrode sheet.
[0100] Preferably, the plurality of bending members includes second bending members, each second bending member configured to intercept a protruding side edge of a respective second electrode sheet.
[0101] Preferably, each bending member has a helical shape.
[0102] Preferably, said helical shape extends along an axis parallel to the feed direction.
[0103] The helical shape causes said protruding side edges to gradually bend during movement of the conveyor along the feed direction.
[0104] Preferably, bending the protruding side edge of the first electrode sheet longitudinally comprises intercepting the protruding side edge of the first electrode sheet with a first bending member while the conveyor moves along said feed direction.
[0105] Preferably, bending the protruding side edge of the second electrode sheet longitudinally comprises intercepting the protruding side edge of the second electrode sheet with a second bending member while the conveyor moves along said feed direction.
[0106] Preferably, after each multi-layer strip has been wound onto a respective winding device, the protruding side edge of the first electrode sheet is flattened by being turned towards the winding axis of the respective winding device.
[0107] Preferably, after each multi-layer strip has been wound onto a respective winding device, the protruding side edge of the second electrode sheet is flattened by being turned towards the winding axis of the respective winding device.
[0108] The flattening of the protruding side edges allows the terminals of the electrochemical cell to be made in a "tabless" configuration.
[0109] Preferably, flattening the protruding side edge of the first electrode sheet comprises forming a radial fold at the protruding side edge of the first electrode sheet relative to a winding axis of the respective winding device.
[0110] Preferably, flattening the protruding side edge of the second electrode sheet comprises forming a radial crease at the protruding side edge of the second electrode sheet relative to a winding axis of the respective winding device.
[0111] Preferably, a plurality of biasing members are provided.
[0112] Preferably, each of these pressure members is arranged on a respective winding device.
[0113] Preferably, each of the pressing members is configured to flatten a protruding side edge of the first sheet and the second sheet.
[0114] Preferably, before winding each multi-layer strip onto a respective winding device, a number of cuts are made in said protruding side edges.
[0115] This break separates the protruding side edges along their length, simplifying flattening.
[0116] Preferably, a plurality of cuts are made in said protruding side edges prior to forming a plurality of parallel strips of each of said sheets.
[0117] Preferably, a plurality of cuts are made in said projecting side edges by cutting longitudinally through each of said sheets.
[0118] Preferably, a plurality of cuts are made in said protruding side edges when forming said plurality of parallel strips.
[0119] Preferably, said discontinuity extends in said protruding side edge from a free end to a curved inner end of said protruding side edge.
[0120] Preferably, the shape of the cut is J-shaped or sinusoidal, which reduces the risk that the cut will cause the strip to break.
[0121] Preferably, a third cutting member is provided.
[0122] Preferably, a third cutting member is configured to make said plurality of cuts at said protruding side edges.
[0123] Preferably, the third cutting member is located between the service area and the conveyor.
[0124] In one embodiment, the third cutting member is disposed on or integral with the first cutting member.
[0125] In an alternative embodiment, the third cutting member comprises a laser cutting device.
[0126] Preferably, after each longitudinal piece has been wound on a respective winding device, said winding device is replaced by a further free winding device for winding thereon a subsequent longitudinal piece of the same multi-layer strip.
[0127] This reduces the dead time between winding one piece of the multi-layer strip and the next.
[0128] In a preferred embodiment, the coil is prepared in dry environmental conditions.
[0129] Preferably, the coil is provided under dry environmental conditions and is maintained under such dry environmental conditions while the sheet is unwound from the coil.
[0130] In various embodiments, preparing the coil includes placing the coil in a dryer to evaporate solvent and other contaminants from the coil.
[0131] In yet another embodiment, the coil is provided at ambient conditions and maintained at such ambient conditions while the sheet is unwound from the coil.
[0132] Preferably, impurities are continuously evaporated from the sheet after it is unwound from the coil and before it is formed into the plurality of multi-layer strips on the conveyor.
[0133] Microwaves may be directed at the separator sheets as they are unwound from their respective coils to evaporate impurities.
[0134] In one embodiment, the conveyor is located in a room with dry environmental conditions, which reduces the risk of contamination during the formation of the multi-layer strip and during feeding the multi-layer strip to the winding device.
[0135] Preferably, while the sheet is being fed towards the conveyor, the sheet transitions from ambient environmental conditions to dry environmental conditions.
[0136] In various embodiments, the conveyor is located in a location with atmospheric environmental conditions.
[0137] Preferably, after each multi-layer strip is wound on its respective winding device, the wound multi-layer strip is subjected to a drying treatment.
[0138] Preferably, the wound multi-layer strip is dried by vacuum drying.
[0139] In one embodiment, the winding device is arranged at an offset position along the feed direction.
[0140] The offset position allows the multi-layer strips to remain adjacent to one another while accommodating the mechanical components required for the operation of the winding device.
[0141] In a different embodiment, the winding devices are arranged at offset positions along a direction oblique to the feed direction, so that all longitudinal pieces travel the same distance to reach their respective winding devices. [Brief description of the drawings]
[0142] Further features and advantages of the present specification will become apparent from the following detailed description of preferred embodiments thereof, given by way of indicative and non-limiting example, made with reference to the accompanying drawings, in which: [Figure 1]1 is a schematic side view of an apparatus for forming an electrochemical cell of an electric battery made in accordance with the present invention; [Diagram 2] FIG. 2 is a schematic top view of the apparatus of FIG. 1 with some elements removed. [Figure 2A] FIG. 2 is a detailed view showing details of the device of FIG. 1. [Diagram 3] 1A-1D are schematic side views of different embodiments of apparatus for forming electrochemical cells of an electric battery made in accordance with the present invention. [Figure 4] FIG. 4 is a schematic top view of the apparatus of FIG. 3 with some elements removed. [Diagram 5] FIG. 2 is a schematic top view of a portion of a multi-layer strip formed by the apparatus of the previous figure. [Figure 6] 6 is a schematic cross-sectional view of the multilayer strip of FIG. 5. [Figure 7] 5A-5C are schematic cross-sectional views of multi-layer strips made in different configurations using the apparatus of FIGS. [Figure 8] 5A-5C are schematic cross-sectional views of multi-layer strips made in different configurations using the apparatus of FIGS. [Figure 9] 5A-5C are schematic cross-sectional views of multi-layer strips made in different configurations using the apparatus of FIGS. [Figure 10] 5A-5C are schematic cross-sectional views of multi-layer strips made in different configurations using the apparatus of FIGS. [Figure 11] FIG. 6 is a schematic top view showing details of the multi-layer strip of FIG. 5. [Figure 12] FIG. 5 is a radial cross-section of an electrochemical cell that can be obtained by the device of FIGS. [Figure 13] FIG. 5 shows a schematic cross-sectional view of an electrochemical cell that can be obtained by the apparatus of FIGS. [Figure 14] FIG. 5 shows a schematic cross-sectional view of an electrochemical cell that can be obtained by the apparatus of FIGS. [Figure 15] FIG. 5 shows a schematic cross-sectional view of an electrochemical cell that can be obtained by the apparatus of FIGS. [Figure 16] FIG. 5 shows a schematic cross-sectional view of an electrochemical cell that can be obtained by the apparatus of FIGS. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0143] The representation in the above diagram is not necessarily to be considered as being to scale and does not necessarily respect the proportions between the parts. In the drawings, identical or similar elements in different embodiments are designated with the same reference numbers.
[0144] An apparatus for forming an electrochemical cell of an electric battery according to the present invention is shown diagrammatically in FIGS.
[0145] The device 1 has a service area 10 arranged to support four coils 11, 12, 13, 14 of a sheet wound as a continuous tape. The service area 10 has four supports 15, e.g. pins, on which the coils 11, 12, 13, 14 can be engaged and disengaged. The four supports 15 can be electrically driven to effect rotation of the coils 11, 12, 13, 14, or the coils 11, 12, 13, 14 can be freely rotated by tension.
[0146] In the embodiment shown in FIG. 1, the four supports 15 are spaced apart equidistantly from one another in the vertical plane.
[0147] The axial dimension of each of the coils 11, 12, 13, 14, measured along its respective winding axis, is greater than or equal to 1 m, preferably around 2 m.
[0148] The diameter of each of the coils 11, 12, 13, 14 is between 0.4 mm and 2 mm, preferably between 0.6 m and 1.5 m, and more preferably between 0.8 m and 1.2 m.
[0149] The length of the wound sheet of each of the coils 11, 12, 13, 14 is between 1000 m and 100000 m, preferably between 3000 m and 60000 m, and more preferably between 6000 m and 40000 m.
[0150] The first coil 11 of the four coils 11, 12, 13, 14 comprises a winding of a first separator sheet 11a in the form of a continuous tape. The first separator sheet 11a is made of a polymeric material, such as polyethylene, polypropylene or a combination thereof, is microporous and electrically insulating, and is adapted to be impregnated with an electrolyte. The thickness of the separator sheet 11a is between 5 μm and 30 μm, preferably between 10 μm and 25 μm, and more preferably between 15 μm and 20 μm.
[0151] The second coil 12 of the four coils 11, 12, 13, 14 comprises a winding of a first electrode sheet 12a in the form of a continuous tape. The first electrode sheet 12a comprises a conductive metal foil, for example based on aluminum or copper, having a thickness between 2 μm and 20 μm, preferably between 4 μm and 15 μm, more preferably between 6 μm and 10 μm. The metal foil of the first electrode sheet 12a is coated on one or both sides with a substrate of a cathode material, for example comprising lithium and one of cobalt oxide (LiCoO2), manganese oxide (LiMn2O4), nickel manganese cobalt oxide (NMC), iron phosphate (LiFePO4), lithium titanate (Li2TiO3). The total thickness of the first electrode sheet 12a is between 50 μm and 200 μm, preferably between 100 μm and 150 μm, for example about 125 μm.
[0152] The first electrode sheet 12a is intended to form, for example, the cathode of an electrochemical cell.
[0153] A third coil 13 of the four coils 11, 12, 13, 14 has a winding of a second separator sheet 13a in the form of a continuous tape, similar to the first separator sheet 11a.
[0154] The fourth coil 14 of the four coils 11, 12, 13, 14 comprises a winding of a second electrode sheet 14a in the form of a continuous tape. The second electrode sheet 14a comprises a conductive metal sheet, for example an aluminum or copper base, having a thickness between 2 μm and 20 μm, preferably between 4 μm and 15 μm, more preferably between 6 μm and 10 μm. The metal foil of the second electrode sheet 14a is coated on one or both sides with a substrate of anode material, for example a graphitic material. The second electrode sheet 14a is intended to form, for example, the anode of an electrochemical cell.
[0155] It is intended that the first separator sheet 11a, the first electrode sheet 12a, the second separator sheet 13a and the second electrode sheet 14a are unwound from their respective coils 11, 12, 13, 14 and fed to the conveyor 20 along respective feed directions D1, D2, D3, D4 which are preferably parallel to each other.
[0156] In the embodiment shown in FIG. 1, a first deviation roller 16a is arranged alongside the coils 11, 12, 13, 14 to deviate the sheets 11a, 12a, 13a, 14a unwound from the coils 11, 12, 13, 14 towards the conveyor 20, and a pair of second deviation rollers 16b are arranged downstream of the first deviation roller 16 associated with the feed directions D1, D2, D3, D4 to transport the sheets 11a, 12a, 13a, 14a deviated by the first deviation roller 16 towards the conveyor 20.
[0157] In the illustrated embodiment, the service area 10 is located in a first chamber with atmospheric environmental conditions. The conveyor 20 is located in a second chamber 20a configured to maintain dry environmental conditions. Between the first chamber 10a and the second chamber 20a of each coil 11, 12, 13, 14, a respective interface 17 is provided. The interface 17 is configured to pass the sheets 11a, 12a, 13a, 14a towards the conveyor 20 while maintaining the dry environmental conditions of the second chamber 20a.
[0158] Between the service area 10 and the conveyor 20, first cutting members 21, 22, 23, 24 are arranged, preferably in the second chamber 20a, each intercepting the sheets 11a, 12a, 13a, 14a along the respective feed direction D1, D2, D3, D4 and cutting them longitudinally into parallel strips 11b, 12b, 13b, 14b. The cross-sectional width of the strips 11b, 12b, 13b, 14b thus obtained is selected according to the axial length of the electric battery to be manufactured. In the illustrated preferred embodiment, the cross-sectional width of each strip 11b, 12b, 13b, 14b thus obtained is between 70 and 90 mm, for example about 80 mm.
[0159] FIG. 2 shows the strips 12b obtained after longitudinal cutting of the first electrode sheet 12a.
[0160] In a possible embodiment, each of the first cutting members 21, 22, 23, 24 comprises, for example, a pair of counter-rotating rollers configured to receive the respective sheet 11a, 12a, 13a, 14a between them and provided with a respective blade configured to longitudinally cut the sheet 11a, 12a, 13a, 14a.
[0161] In FIG. 2, one can see the longitudinal cuts 12c made by the first cutting member 22 in the first electrode sheet 12a to form strips 12b.
[0162] Between the service area 10 and the conveyor 20 second cutting members 26, 27, 28, 29 are arranged, preferably in the second chamber 20a, each intercepting the sheets 11a, 12a, 13a, 14a along a respective feed direction D1, D2, D3, D4 before they arrive at the conveyor 20.
[0163] In the illustrated embodiment, the second cutting members 26, 27, 28, 29 are arranged downstream of the first cutting members 21, 22, 23, 24 along the respective feed directions D1, D2, D3, D4.
[0164] The second cutting members 26, 27, 28, 29 are configured to periodically transversely cut the strips 11b, 12b, 13b, 14b into separate longitudinal pieces, each having a length between 5000 and 7000 mm, for example about 6000 mm.
[0165] In an alternative embodiment, not shown, the second cutting members 26, 27, 28, 29 may be arranged upstream of the first cutting members 21, 22, 23, 24 along the respective feed directions D1, D2, D3, D4. In such a case, the second cutting members 26, 27, 28, 29 act on the sheets 11a, 12a, 13a, 14a unwound from the coils 11, 12, 13, 14, and the first cutting members 21, 22, 23, 24 act on the sheets 11a, 12a, 13a, 14a already cut into longitudinal pieces by the second cutting members 26, 27, 28, 29 to form strips 11b, 12b, 13b, 14b.
[0166] In FIG. 2, the longitudinal cut 12d made by the second cutting member 27 in the first electrode sheet 12a can be seen.
[0167] The conveyor 20 is preferably positioned below the service area 10 and is configured to receive the sheets 11a, 12a, 13a, 14a which have already been cut longitudinally into parallel strips 11b, 12b, 13b, 14b by first cutting members 21, 22, 23, 24 and transversely into longitudinal pieces by second cutting members 26, 27, 28, 29.
[0168] The conveyor 20 comprises a conveyor belt 30 having a horizontal conveying surface movable along a feed direction D.
[0169] The conveyor 20 may move at a speed preferably between 0.5 and 0.2 m / s, for example around 1 m / s.
[0170] The conveyor 20 receives the longitudinal pieces of the strip 11b of the first separator sheet 11a such that the longitudinal direction of these longitudinal pieces is parallel to the feed direction D.
[0171] The conveyor 20 also receives the longitudinal pieces of the strip 12b of the first electrode sheet 12a such that their longitudinal directions are parallel to the feed direction D. Each of these longitudinal pieces overlaps a respective longitudinal piece of a respective strip 11b of the first separator sheet 11a.
[0172] Similarly, the conveyor 20 receives the longitudinal pieces of the strip 13b of the second separator sheet 13a such that their longitudinal directions are parallel to the feed direction D. Each of these longitudinal pieces overlaps a respective longitudinal piece of a respective strip 12b of the first electrode sheet 12a.
[0173] The conveyor finally receives the longitudinal pieces of the strip 14b of the second electrode sheet 14a such that their longitudinal direction is parallel to the feed direction D. Each of these longitudinal pieces overlaps a respective longitudinal piece of a respective strip 13b of the second separator sheet 13a.
[0174] In this manner, a plurality of multi-layer strips 35 are formed on the conveyor 20, each multi-layer strip 35 having a first layer 35a defined by a longitudinal piece of the strip 11b of the first separator sheet 11a, a second layer 35b overlapping the first layer 35a and defined by a longitudinal piece of the strip 12b of the first electrode sheet 12a, a third layer 35c overlapping the second layer 35b and defined by a longitudinal piece of the strip 13b of the second separator sheet 13a, and a fourth layer 35d overlapping the third layer 35c and defined by a longitudinal piece of the strip 14b of the second electrode sheet 14a.
[0175] The multi-layer strip 35 obtained from the single strip 11b, the single strip 12b, the single strip 13b and the single strip 14b are arranged one after the other on the conveyor 20 along the feed direction D, and the multi-layer strip 35 obtained from the parallel strips 11b, 12b, 13b and 14b are arranged on the conveyor 20 parallel to each other along a direction perpendicular to the feed direction D.
[0176] The positioning of the coils 11, 12, 13, 14 relative to the conveyor 20 is such that, in each multi-layer strip 35, the strip 12b (and therefore the second layer 35b) of the first electrode sheet 12a is placed on the respective strip 11b (and therefore on the first layer 35a) of the first separator sheet 11a in a position transversely offset with respect to the latter, and each strip 13b (and therefore the third layer 35c) of the second separator sheet 13a is placed on the respective strip 12b (and therefore on the second layer 35b) of the first electrode sheet 12a in a position transversely offset with respect to the latter. The second electrode sheet 12a is disposed on a first separator sheet 11a such that each strip 14b (and thus the fourth layer 35d) of the second electrode sheet 14a is disposed on a respective strip 13b of the second separator sheet 13 (and thus on the third layer 35c) in a position transversely offset from the base strip 11b of the first separator sheet 11a (and thus from the first layer 35a) to the opposite side to the strip 12b of the first electrode sheet 12a (and thus the second layer 35b).
[0177] For example, strips 12b of the first electrode sheet 12a (and thus second layer 35b) are transversely offset by a distance of between 1 mm and 10 mm, preferably between 3 mm and 7 mm, for example about 5 mm, and strips 14b of the second electrode sheet 14a (and thus fourth layer 35d) are on the other hand transversely offset by a similar amount relative to strips 11b of the first separator sheet 11a (and thus first layer 35a) and strips 13b of the second separator sheet 13a (and thus third layer 35c), on the opposite side to strips 12b of the first electrode sheet 12a (and thus second layer 35b), as can be seen in Figures 5 and 6.
[0178] In this way, a protruding side edge 36 of the first electrode sheet protruding to one side relative to the strips 11b, 13b of the separator sheets 11a, 13a, and a protruding side edge 37 of the second electrode sheet 14a protruding to the opposite side relative to the protruding side edge 36 of the first electrode sheet 12a relative to the strips 11b, 13b of the separator sheets 11a, 13a, are created in each multi-layer strip 35.
[0179] A plurality of first bending members 40a shown in Figures 9-10 are disposed on the conveyor 20. The first bending members 40a extend in the longitudinal direction along the supply direction D. The first bending members 40a are disposed parallel to one another, and each of the first bending members 40a is configured to interrupt the protruding side edge 36 of the first electrode sheet 12a of the respective multi-layer strip 35 and bend it upward in the longitudinal direction.
[0180] Similarly, a plurality of second bending members 40b as shown in Figures 8 to 10 are disposed on the conveyor 20. The second bending members 40b extend longitudinally along the feeding direction D. The second bending members 40b are disposed parallel to one another alongside the first bending members 40a, and each of the second bending members 40b is configured to interrupt the protruding side edge 37 of the second electrode sheet 14a of the respective multi-layer strip 35 and bend it longitudinally upward.
[0181] The bending elements 40a, 40b have respective helical shapes 41 that extend along a helix axis parallel to the feed direction D from a substantially horizontal orientation to an orientation that is increasingly inclined relative to the horizontal plane moving along the feed direction D.
[0182] For example, as shown in FIG. 9, in the illustrated embodiment, both end side edges 38 of strip 11b of separator sheet 11a and both end side edges 39 of strip 13b of separator sheet 13a are also bent longitudinally along with the protruding side edges 36, 37 of strips 12b, 14b of electrode sheets 12a, 14a.
[0183] Downstream of the conveyor 20 relative to the feed direction D, a number of winding devices 50 are arranged.
[0184] Each winding device 50 is configured to receive a respective multi-layer strip 35 .
[0185] Each winding device 50 may, for example, have a motorized pin around which the multi-layer strip 35 is wound to form a jelly-roll type electrochemical cell.
[0186] As shown in detail in FIG. 2A, an additional winding device 50a is positioned next to each winding device 50 to replace the winding device 50 upon completion of winding of a longitudinal piece of the multi-layer strip 35 so as to receive the next longitudinal piece of the multi-layer strip 35.
[0187] In the embodiment shown in Figures 1 and 2, the winding device 50 is arranged offset along the feed direction D in order to accommodate the parts required for its operation.
[0188] 3 and 4 show an apparatus 1 similar to that of FIG. 1 or 2, with the difference that the winding device 50 is arranged offset along a direction inclined relative to the feed direction D, preferably also relative to the horizontal plane, so that all multi-layer strips 35 travel the same distance after they are formed on the conveyor 20 until they reach the respective winding device 50. The offset of the winding device 50 may also depend on the mutual positions of the coils 11, 12, 13, 14 and of the latter relative to the conveyor 20, so that all of the sheets 11a, 12a, 13a, 14a travel the same distance after they are unwound from the coils 11, 12, 13, 14 until they are deposited on the strips 11b, 12b, 13b, 14c of the conveyor 20 forming the multi-layer strip 35.
[0189] In this embodiment, each second cutting member 26, 27, 28, 29 may be configured to transversely cut the strips 11b, 12b, 13b, 14b of the respective sheets 11a, 12a, 13a, 14a with a single linear transverse cut, so that the longitudinal pieces of the strips 11b, 12b, 13b, 14b of each sheet 11a, 12a, 13a, 14a are transversely aligned as can be seen in FIG.
[0190] In the embodiment of Figures 3 and 4, the second cutting members 26, 28 can be positioned between the conveyor 20 and the winding device 50 such that the strips 11b, 13b of the separator sheets 11a, 13a extend continuously between the coils 11, 13 and the conveyor 20 and are cut transversely upstream of the winding device 50.
[0191] In this embodiment, the second cutting members 26, 27, 28, 29 may also be configured to transversely cut the strips 11b, 12b, 13b, 14b of each multi-layer strip 35 at positions longitudinally offset from one another, such that some longitudinal pieces of the strips 11b, 12b, 13b, 14b project relative to the others at the longitudinal ends of each longitudinal piece of the multi-layer strip 35.
[0192] In the embodiment of Fig. 4, the second cutting members 26, 27, 28, 29 are configured to cut the longitudinal pieces of the strips 12b, 14b of the electrode sheets 12a, 14a so that they are longitudinally shorter than the longitudinal pieces of the strips 11b, 13b of the separator sheets 11a, 13a. In this way, the longitudinal pieces of the strips 11b, 13b of the separator sheets 11a, 13a project longitudinally relative to the longitudinal pieces of the strips 12b, 14b of the electrode sheets 12a, 14a at the longitudinal ends of each longitudinal piece of the multi-layer strip 35. Fig. 4 shows respective cuts 55 between successive longitudinal pieces of the strip 12b of the first electrode sheet 12a.
[0193] As shown in FIG. 12 , each winding device 50 is provided with a pair of pressing members 80 configured to flatten and tilt the axially protruding side edges 36, 37 towards the winding axis A of the respective winding device 50 following winding of the multi-layer strip 35 onto the winding device 50.
[0194] In one embodiment, a third cutting member (not shown) is provided that is configured to make a plurality of transverse cuts 60, shown in FIG. 11, in the edges of the strips 12b of the first electrode sheet 12a and the edges of the strips 14b of the second electrode sheet 14a where the protruding side edges 36, 37 are intended to be formed.
[0195] The third cutting member may include, for example, an insert attached to the rollers of the first cutting members 22, 24, or a computer numerically controlled laser cutting device.
[0196] The third cutting member is configured to make each cut 60 in a diagonal direction from a free edge 61 of the side edge of each strip 12b, 14b toward the inside of the strip 12b, 14b to create a curved inner edge 62.
[0197] For example, the shape of the cuts 60 can be sinusoidal or J-shaped. The cuts 60 define a number of notches 60a in the protruding side edges 36, 37 that are configured to be bent by the bending members 40a, 40b and overturned by the pressing member 80.
[0198] For ease of illustration, reference numbers 60, 61, 62, 60a are shown at some of these cuts 60 in FIG.
[0199] To make an electrochemical cell of an electric battery, four coils 11, 12, 13, 14 of the above type are prepared, each having a winding of a first separator sheet 11a, a winding of a first electrode sheet 12a, a winding of a second separator sheet 13a and a winding of a second electrode sheet 14a.
[0200] The four coils 11, 12, 13, 14 may be formed under ambient conditions and each sheet 11a, 12a, 13a, 14a may be subjected to a contaminant removal treatment, such as a solvent evaporation treatment, before being wound into each coil 11, 12, 13, 14.
[0201] The four coils 11, 12, 13, 14 are mounted on respective supports 15 provided in the service area 10. In the illustrated embodiment, the service area 10 is maintained under ambient environmental conditions while the coils 11, 12, 13, 14 are unwinding. In an alternative embodiment, not shown, the service area 10 is maintained under dry ambient conditions while the coils 11, 12, 13, 14 are unwinding.
[0202] In the illustrated preferred embodiment, the four coils 11, 12, 13, and 14 are arranged in the order of first coil 11, second coil 12, third coil 13, and fourth coil 14 in the supply direction D from the most upstream to the most downstream.
[0203] In a different embodiment not shown, the four coils 11, 12, 13, 14 may be arranged in the following order with respect to the supply direction D from the most upstream to the most downstream: second coil 12, first coil 11, fourth coil 14, third coil 13.
[0204] The sheets 11a, 12a, 13a, 14a are unwound from respective coils 11, 12, 13, 14 and fed towards a conveyor 20 along feed directions D1, D2, D3, D4.
[0205] In an embodiment not shown, the sheets 11a, 12a, 13a, 14a are treated to remove impurities after being unwound from their respective coils 11, 12, 13, 14.
[0206] In the preferred embodiment shown, sheets 11a, 12a, 13a, 14a pass through respective interface 17 into second chamber 20a at dry environmental conditions. This can be avoided by providing an embodiment in which conveyor 20 is also maintained at ambient environmental conditions.
[0207] The sheets 11a, 12a, 13a, 14a are then cut longitudinally by cutting members 21, 22, 23, 24 to form a plurality of parallel strips 11b, 12b, 13b, 14b therefrom, respectively.
[0208] The strips 11b, 12b, 13b, 14b are then cut periodically transversely by second cutting members 26, 27, 28, 29 into a plurality of longitudinal pieces.
[0209] In the embodiment of Figures 3 and 4, the strips 11b, 12b, 13b, 14b of each sheet 11a, 12a, 13a, 14a are all cut together by a single linear transverse cut.
[0210] The strips 11b, 12b, 13b, 14b of each multi-layer strip 35 may be cut at positions offset from one another in the longitudinal direction at the longitudinal ends of each longitudinal piece of the multi-layer strip 35 such that some longitudinal pieces of the strips 11b, 12b, 13b, 14b protrude relative to the other strips.
[0211] In the embodiment of Figures 3 and 4, the feeding of the strips 12b, 14b of electrode sheets 12a, 14a to the conveyor 20 is temporarily slowed or stopped before or after they are transversely cut to form gaps 55 between successive longitudinal pieces of the strips 12b, 14b.
[0212] In an embodiment not shown, the cut 60 is made at the side edge of the strip 12b of the first electrode sheet 12a (said side edge is intended to form the protruding side edge 36 of the first electrode sheet 12a) and at the side edge of the strip 14b of the second electrode sheet 14a (said side edge is intended to form the protruding side edge 37 of the second electrode sheet 14a).
[0213] These cuts 60 define notches 60a in the protruding side edges 36,37.
[0214] The longitudinal pieces of parallel strips 11 b , 12 b , 13 b , 14 b are then placed on a conveyor 20 .
[0215] In the illustrated preferred embodiment, first the strip 11b (specifically the longitudinal piece of strip 11b) of the first separator sheet 11a is placed, then the strip 12b (specifically the longitudinal piece of strip 12b) of the first electrode sheet 12a is placed on the longitudinal piece of strip 11b while the other longitudinal piece of strip 11b is placed on the conveyor 20, then the strip 13b (specifically the longitudinal length of strip 13b) of the second separator sheet 13a is placed on the longitudinal piece of strip 12b while the other longitudinal piece of strip 12b is placed on the longitudinal piece of strip 11b, and finally the strip 14b (specifically the longitudinal piece of strip 14b) of the second electrode sheet 14a is placed on the longitudinal piece of strip 13b while the other longitudinal piece of strip 13b is placed on the longitudinal piece of strip 12b.
[0216] The order of strips 11b, 12b, 14b from bottom to top on the conveyor 20 corresponds to the order of coils 11, 12, 13, 14 from upstream to downstream with respect to the feed direction D.
[0217] In this way, on the conveyor 20, planar, adjacent and parallel longitudinal pieces of multi-layer strips 35 are formed, each of said longitudinal pieces having respective layers 35a, 35b, 35c, 35d offset as described above to form a protruding side edge 36 of the first electrode sheet 12a and a protruding side edge 37 of the second electrode sheet 14a in each longitudinal piece of the multi-layer strip 35.
[0218] Once the longitudinal pieces of the multi-layer strip 35 have been formed, they move in a feed direction D with the conveyor belt 30 in continuous motion so that said longitudinal pieces are fed to respective winding devices 50 .
[0219] During movement of the conveyor 20, the protruding side edge 36 of the first electrode sheet 12a, the protruding side edge 37 of the second electrode sheet 14a, and in the illustrated embodiment the side edges 38, 39 of the separator sheets 11a, 13a are bent longitudinally upwards by the first bending member 40a and the second bending member 40b.
[0220] Each longitudinal piece of the multi-layer strip 35 is then wound on a respective winding device 50. The longitudinal pieces of the multi-layer strip 35 can be wound, for example, by rotation of a pin of the winding device 50. The longitudinal pieces of the multi-layer strip 35 that are parallel to one another can be wound simultaneously.
[0221] In an embodiment not shown, the strips 12b, 14b of electrode sheets 12a, 14a are periodically cut transversely before being fed to the conveyor 20, while the strips 11b, 13b of separator sheets 11a, 13b are periodically cut transversely after being fed to the conveyor 20 and before being fed to the respective winding devices 50. In this embodiment, the strips 11b, 13b of separator sheets 11a, 13a extend continuously along the conveyor 20, transporting the longitudinal pieces 12b, 14b of electrode sheets 12a, 14a along the conveyor 20.
[0222] Next, the protruding side edge 36 of the first electrode sheet 12a and the protruding side edge 37 of the second electrode sheet 14a are flattened. During such flattening, the protruding side edges 36, 37 may be circumferentially continuous. This creates a plurality of radial creases in the protruding side edges 36, 37.
[0223] Alternatively, the protruding side edges 36, 37 may be separated at the notches 60a by making cuts 60. In this case, adjacent notches 60a partially overlap during flattening.
[0224] FIG. 12 shows a radial cross section of an electrochemical cell 70 made up of multiple strips 35 wound about respective winding axes A with respective protruding side edges 36, 37 flattened.
[0225] While each multi-layer strip 35 is being wound around a respective winding device 50, an additional winding device 50a is stationary near the winding device 50. After the multi-layer strip 35 has been wound around the winding device 50, the winding device 50 is removed and the additional winding device 50a replaces the winding device 50.
[0226] 13 to 16 show schematic cross-sections of respective electrochemical cells 70 which may be obtained according to various embodiments of the present invention.
[0227] The electrochemical cell 70 of Figures 13 and 15 has, moving from inside to outside along a radial direction, a strip 11b of a first separator sheet 11a, a strip 12b of a first electrode sheet 12a, a strip 13b of a second separator sheet 13a, and a strip 14b of a second electrode sheet 14a. This distribution can be obtained by feeding the multilayer strip 35 from above to a winding device 50 and bringing the winding device 50 into contact with the strip 11b of the first separator sheet 11a.
[0228] The electrochemical cell 70 of Figures 14 and 16 has, moving from outside to inside along a radial direction, a strip 11b of a first separator sheet 11a, a strip 12b of a first electrode sheet 12a, a strip 13b of a second separator sheet 13a and a strip 14b of a second electrode sheet 14a. This distribution is obtained by feeding the multi-layer strip 35 from below into a winding device 50 and bringing the winding device 50 into contact with the strip 14b of the second electrode sheet 14a.
[0229] In the electrochemical cell 70 of Figures 13 and 14, the longitudinal pieces of the strips 12b, 14b of the electrode sheets 12a, 14a are circumferentially offset from the longitudinal pieces of the strips 11b, 13b of the separator sheets 11a, 13a. This is achieved by transversely cutting the sheets 11a, 12a, 13a, 14a at the longitudinally offset positions, as described above.
[0230] In the electrochemical cell 70 of Figures 15 and 16, the longitudinal pieces of the strips 12b, 14b of the electrode sheets 12a, 14a are shorter than the longitudinal pieces of the strips 11b, 13b of the separator sheets 11a, 13a. This is achieved by forming gaps 55 between successive longitudinal pieces of the electrode sheets 12a, 14a, as described above. In these embodiments, after the multi-layer strip 35 is wound, the protruding portions of the separator sheets 11a, 13a can be fused together to stabilize the electrochemical cell 70.
[0231] In embodiments not shown in which the conveyor 20 is maintained under ambient conditions, the wound electrochemical cells 70 are subjected to a drying step after winding, for example by vacuum drying.
[0232] Obviously, those skilled in the art can make numerous modifications and variations to the above invention to meet specific possible needs, while remaining within the scope of protection defined by the following claims.
Claims
1. 1. A method of forming an electrochemical cell of an electric battery, comprising: Providing a coil (11) having a winding of a first separator sheet (11a), a coil (12) having a winding of a first electrode sheet (12a), a coil (13) having a winding of a second separator sheet (13a), and a coil (14) having a winding of a second electrode sheet (14a); feeding said sheets (11a, 12a, 13a, 14a) towards a conveyor (20) by unwinding them from their respective coils (11, 12, 13, 14); forming a plurality of multi-layer strips (35) on said conveyor (20), each of said multi-layer strips having a first layer (35a) of said first separator sheet (11a), a second layer (35b) of said first electrode sheet (12a) overlapping said first layer (35a), a third layer (35c) of said second separator sheet (13a) overlapping said second layer (35b), and a fourth layer (35d) of said second electrode sheet (14a) overlapping said third layer (35c), said conveyor (20) being movable along a feed direction (D); feeding each multi-layer strip (35) by said conveyor (20) to a respective winding device (50); Winding each multi-layer strip (35) on said respective winding device (50). A method comprising:
2. Prior to forming the plurality of multi-layer strips (35) on the conveyor (20), forming a plurality of parallel strips (11b, 12b, 13b, 14b) of each of said sheets (11a, 12a, 13a, 14a) by longitudinally cutting each of said sheets (11a, 12a, 13a, 14a) as each of said sheets (11a, 12a, 13a, 14a) is fed towards said conveyor (20); placing on said conveyor (20) first the parallel strips (11b) of said first separator sheet (11a), then the parallel strips (12b) of said first electrode sheet (12a), then the parallel strips (13b) of said second separator sheet (13a), then the parallel strips (14b) of said second electrode sheet (14a); The method of claim 1 , comprising:
3. the parallel strips (12b) of the first electrode sheet (12a) are placed on the conveyor (20) at a position transversely offset relative to the parallel strips (11b) of the first separator sheet (11a) to create protruding side edges (36) of the first electrode sheet (12a) in each multi-layer strip (35); the parallel strips (14b) of the second separator sheet (13a) are placed on the conveyor (20) at a position transversely offset relative to the parallel strips (12b) of the first electrode sheet (12a); the parallel strips (14b) of the second electrode sheet (14a) are laid on the conveyor (20) in a position offset transversely to the parallel strips (11b, 13b) of the first separator sheet (11a) and the second separator sheet (13a) opposite the protruding side edge (36) of the first electrode sheet (12a) to create a protruding side edge (37) of the second electrode sheet (14a) in each multi-layer strip (35); The method of claim 2.
4. bending the protruding side edge (36) of the first electrode sheet (12a) and the protruding side edge (37) of the second electrode sheet (14a) in a longitudinal direction before winding each multi-layer strip (35) on the respective winding device (50). The method according to claim 3.
5. bending the protruding side edge (36) of the first electrode sheet (12a) in the longitudinal direction comprises intercepting the protruding side edge (36) of the first electrode sheet (12a) with a first bending member (40a) while the conveyor (20) moves along the feed direction (D); Bending the protruding side edge (37) of the second electrode sheet (14a) in the longitudinal direction comprises intercepting the protruding side edge (37) of the second electrode sheet (14a) with a second bending member (40b) while the conveyor (20) is moving along the feed direction (D). The method according to claim 4.
6. after each multi-layer strip (35) has been wound on its respective winding device (50), flattening the protruding side edge (36) of the first electrode sheet (12a) and the protruding side edge (37) of the second electrode sheet (14a) by tipping them towards a winding axis (A) of the respective winding device (50). The method according to claim 5.
7. making a plurality of cuts (60) in said protruding side edges (36, 37) before winding each multi-layer strip (35) on said respective winding device (50). The method according to any one of claims 4 to 6.
8. The cut (60) extends from a free end (61) of the protruding side edge (36, 37) to a curved inner end (62). The method of claim 7.
9. Before each multi-layer strip (35) is wound on said respective winding device (50), forming a plurality of longitudinal pieces of a multi-layer strip (35); wherein winding each multi-layer strip (35) on said respective winding device (50) comprises: winding each of said longitudinal pieces on said respective winding device (50). The method according to any one of claims 1 to 8.
10. forming the plurality of longitudinal pieces of the multi-layer strip (35) comprises periodically transversely cutting each of the sheets (11a, 12a, 13a, 14a) before or after forming the parallel strips (11b, 12b, 13b, 14b) and before placing the parallel strips (11b, 12b, 13b, 14b) on the conveyor (20); The method according to claim 9 when dependent on claim 2.
11. An apparatus (1) for forming an electrochemical cell of an electric battery, comprising: a service area (10) configured to support a coil (11) having a turn of a first separator sheet (11a), a coil (12) having a turn of a first electrode sheet (12a), a coil (13) having a turn of a second separator sheet (13a), and a coil (14) having a turn of a second electrode sheet (14a); a conveyor (20) configured to support a plurality of multi-layer strips (35), each of the plurality of multi-layer strips (35) having a first layer (35a) of the first separator sheet (11a), a second layer (35b) of the first electrode sheet (12a) overlying the first layer (35a), a third layer (35c) of the second separator sheet (13a) overlying the second layer (35b), and a fourth layer (35d) of the second electrode sheet (14a) overlying the third layer (35c), the conveyor (20) being movable along a feed direction (D); a plurality of winding devices (50) arranged downstream of the conveyor (20) relative to the feeding direction (D) and configured to receive each respective multi-layer strip (35); An apparatus (1).
12. a first cutting member (21, 22, 23, 24) arranged between said service area (10) and said conveyor (20) and configured to longitudinally cut each of said sheets (11a, 12a, 13a, 14a) into parallel strips (11b, 12b, 13b, 14b); 12. Apparatus (1) according to claim 11.
13. a second cutting member (26, 27, 28, 29) arranged between the service area (10) and the conveyor (20) and configured to periodically cut each of the sheets (11a, 12a, 13a, 14a) in a transverse direction; 13. Apparatus (1) according to claim 11 or 12.
14. a plurality of bending members (40a, 40b) arranged parallel to each other above the conveyor (20), extending along a direction parallel to the feeding direction (D) and configured to block respective side edges of the multi-layer strip (35); Apparatus (1) according to any one of claims 11 to 13.
15. Each of the bending members (40a, 40b) has a helical shape (41).
15. Apparatus (1) according to claim 14.