Method of forming electrochemical cell of battery pack
By forming multi-layer strips on the conveyor and automatically feeding them to the winding device, the existing battery pack production methods are solved, and a more efficient and safe production process is achieved.
Patent Information
- Application Number
- CN202380044929.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-05-10
- Filing Date
- 2023-05-09
- Publication Date
- 2025-02-07
AI Technical Summary
Existing battery pack production methods are inefficient and costly, especially during mass production, requiring a large amount of temporary storage space and fine operation, limiting production efficiency and safety.
By forming multi-layer strips on the conveyor, the automatic feeding to the winding device is reduced, the need for feeding individual strips is avoided, bottlenecks and safety risks are eliminated, and the production steps of sub-rolls are eliminated.
Improves the efficiency and safety of battery pack production, reduces production time and storage space requirements, and reduces risk exposure to operators.
Smart Images
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Abstract
Description
[0001] manual
[0002] The present invention relates to a method for forming an electrochemical cell for a battery.
[0003] Some types of batteries, such as those commonly used in electric vehicles, include a hollow container within which is an electrochemical cell formed by an anode and a cathode separated by an electrolyte membrane.
[0004] In lithium-ion cylindrical batteries, a cylindrical electrochemical cell called a "jelly roll" or "Swiss roll" is usually used. It consists of four layers of materials in the form of thin foils or sheets. These four layers include a cathode layer (hereinafter also referred to as "cathode"), which is usually composed of elemental (such as lithium) and metal (such as nickel, manganese, cobalt) oxides, an anode layer (hereinafter also referred to as "anode"), such as graphite, and two separator layers (hereinafter also referred to as "separators"), which are composed of, for example, electrically insulating and porous polymer films, which are alternately arranged with the cathode layer and the anode layer to separate them.
[0005] The multi-layered product thus constructed will roll up upon itself to form a jelly roll.
[0006] In conventional cylindrical electrochemical cells, two conductive terminals called "tabs" are welded on opposite sides, one to the cathode and the other to the anode, to form the positive and negative electrodes of the battery pack. Recently, a cylindrical electrochemical cell called "tabless" has been designed, which does not require welding terminals because the side edges of the anode and cathode are bent to serve as the terminals themselves.
[0007] The sizes of cylindrical electrochemical cells are standard. The most common sizes are 1865 (diameter equal to 18 mm, axial length equal to 65 mm) and 2170 (diameter equal to 21 mm, axial length equal to 70 mm) for conventional tabbed cells, and 4680 (diameter equal to 46 mm, axial length equal to 80 mm) for "tabless" cells.
[0008] To produce this type of battery, anodes, cathodes and separators are produced on a large scale in the form of continuous sheets that are wound into individual coils called “mother coils” with an axial dimension of more than one meter.
[0009] The mother roll is then unwound and the individual sheets are cut longitudinally into strips having a transverse width equal to the axial length of the electrochemical cell to be produced. The strips are then individually rewound into smaller rolls, called "daughter rolls".
[0010] The sub-web is processed (eg, by vacuum drying) to remove impurities and brought to a dry environment under controlled environmental conditions for final assembly of the electrochemical cell.
[0011] Each sub-coil is unwound, and strips unwound from the sub-coils of anode, cathode, and separator are typically manually fed simultaneously into a winding device in different directions, placing the cathode (or anode) first, then the separator, then the anode (or cathode), and finally another separator onto the winding device to form a jelly roll.
[0012] Next, terminals are welded to the cathode and anode, and the jelly roll is placed in a hollow cylindrical container filled with an electrolyte solution in liquid form, then closed and subjected to subsequent molding, degassing, aging, and testing operations.
[0013] Applicants note that the above-described production methods are costly in terms of production efficiency, especially when provided on a large scale.
[0014] In practice, the Applicant has observed that the production of the mother coil, its unwinding for cutting into strips, the rewinding of the strips into daughter coils and the unwinding of the daughter coils for assembling electrochemical cells on respective winding devices all require time in the production hall for each of the above-mentioned coils. Therefore, considerable temporary storage space must be provided.
[0015] Furthermore, in the Applicant's opinion, the simultaneous winding of four strips onto a winding device is a delicate operation which, besides requiring a high degree of precision, requires great attention on the part of the operator when manually feeding said strips onto the winding device in order to avoid the risk of injury. This creates a bottleneck in the production process, limiting the number of electrochemical cells that can be produced in a given time.
[0016] The Applicant has observed that the production method summarized above can be improved.
[0017] In fact, the applicant has realised that if the strips are fed onto a conveyor before being individually wound onto a winding device to form a multi-layer strip which is then automatically fed to the winding device, the need to feed individual strips to the winding device would be avoided, thereby eliminating the aforementioned bottleneck and reducing the risk of injury to the operator.
[0018] According to the applicant, each multilayer strip can be formed on the conveyor by cutting the electrode and diaphragm sheets unrolled from the mother coil into parallel strips immediately before or after they are placed on the conveyor. Thus, no sub-coils are required, saving production time and storage space.
[0019] Thus, the present invention in its first aspect relates to a method for forming an electrochemical cell of a battery.
[0020] Preferably, a coil comprising a first diaphragm sheet winding is prepared.
[0021] Preferably, a coil comprising a first electrode sheet winding is prepared.
[0022] Preferably, a coil comprising a second diaphragm sheet winding is prepared.
[0023] Preferably, a coil comprising a second electrode sheet winding is prepared.
[0024] Preferably, the sheets are fed to the conveyor by unwinding from their respective coils.
[0025] Preferably, a plurality of multi-layer strips are formed on the conveyor.
[0026] Preferably, each multilayer strip comprises a first layer of the first diaphragm sheet, a second layer of the first electrode sheet, a third layer of the second diaphragm sheet and a fourth layer of the second electrode sheet.
[0027] Preferably, the second layer overlaps said first layer.
[0028] Preferably, the third layer overlaps said second layer.
[0029] Preferably, the fourth layer overlaps the third layer.
[0030] Preferably, the conveyor is movable in the feed direction.
[0031] Preferably, each multi-layer strip is fed by said conveyor to a respective winding device.
[0032] Preferably, each multilayer strip is wound onto a respective winding device.
[0033] In a second aspect the invention relates to an apparatus for forming an electrochemical cell of a battery.
[0034] Preferably, a service area is provided.
[0035] Preferably, the service area is configured to support a coil comprising a first diaphragm sheet winding.
[0036] Preferably, the service area is configured to support a coil comprising the first electrode sheet winding.
[0037] Preferably, the service area is configured to support a coil comprising the second diaphragm sheet winding.
[0038] Preferably, the service area is configured to support a coil comprising the second electrode sheet winding.
[0039] Preferably, a conveyor is provided.
[0040] Preferably, the conveyor is configured to support a plurality of multi-layer strips.
[0041] Preferably, each multi-layer strip comprises a first layer of said first diaphragm sheet.
[0042] Preferably, each multilayer strip comprises the second layer of said first electrode sheet.
[0043] Preferably, each multi-layer strip comprises a third layer of said second diaphragm sheet.
[0044] Preferably, each multilayer strip comprises a fourth layer of said second electrode sheet.
[0045] Preferably, the second layer overlaps the first layer.
[0046] Preferably, the third layer overlaps the second layer.
[0047] Preferably, the fourth layer overlaps the third layer.
[0048] Preferably, the conveyor is movable in the feed direction.
[0049] Preferably, a plurality of winding devices are arranged downstream of said conveyor with respect to said feed direction.
[0050] Preferably, each winding device is configured to receive a respective multi-layer strip.
[0051] Thus, the multilayer strip is produced directly from the electrode and separator sheets unrolled from the mother coil. In this way, the multilayer strip can be delivered to the winding device without having to produce a sub-coil.
[0052] The multilayer strip is formed on a conveyor, which moves in the feed direction to move them to respective winding devices. In this way, all multilayer strips move in the same direction towards the winding device simultaneously.
[0053] In this way, the production of electrochemical cells requires less operator intervention and can be more easily automated.
[0054] In the present description, terms such as "horizontally", "horizontally", "below", "above" are used to refer to the spatial arrangement in the use configuration of the device according to the invention.
[0055] The term "ambient conditions" is used to refer to the condition of the ambient air that has not been treated with a dehumidification system.
[0056] The term "dry ambient conditions" is used to refer to controlled atmospheric conditions with reduced humidity or further reduced humidity as specified in ISO 7.
[0057] The term "sheet" is used to refer to an object having a thickness of less than 0.5 mm, preferably less than 0.2 mm.
[0058] The electrodes and diaphragm sheets referred to herein have a major dimension defining a longitudinal direction. When the electrodes and diaphragm sheets are placed on a conveyor, the longitudinal direction is parallel to the feed direction of the conveyor.
[0059] The terms "transverse" or "transversely" are used to refer to a direction oblique to the longitudinal direction, preferably perpendicular to the longitudinal direction, and perpendicular to the dimension in which the thickness of the sheet is measured.
[0060] The coils and electrochemical cells referred to in this specification are generally cylindrical.
[0061] The terms "axial" or "axially" are used to refer to a direction parallel to the winding axis of a coil or electrochemical cell.
[0062] The terms "radial" or "radially" are used to refer to a direction perpendicular to the axis of a coil or electrochemical cell.
[0063] The present invention in one or more aspects thereof may have at least one of the following preferred features. Unless expressly stated otherwise, these features may be provided individually or in combination with each other.
[0064] Preferably, the conveyor is arranged below the service area.
[0065] Preferably, the first electrode sheet comprises an anode (or cathode) material.
[0066] Preferably, the second electrode sheet comprises cathode (or anode) material.
[0067] Preferably, the plurality of parallel strips of each sheet are formed by cutting each said sheet longitudinally.
[0068] Preferably, when said sheet material is fed into the conveyor, a plurality of parallel strips of each said sheet material are formed.
[0069] Preferably, a plurality of parallel strips of each said sheet material are formed prior to forming said plurality of multilayer strips on the conveyor.
[0070] Preferably, a first cutting member is provided.
[0071] Preferably, said first cutting member is arranged between said service area and the conveyor.
[0072] Preferably, the first cutting member is configured to cut each sheet longitudinally into parallel strips.
[0073] Preferably, parallel strips of the first diaphragm sheet are placed on the conveyor first, followed by parallel strips of the first electrode sheet, followed by parallel strips of the second diaphragm sheet, followed by parallel strips of the second electrode sheet.
[0074] In this way, the sequence of layers that will form the electrochemical cell is determined.
[0075] Preferably, a plurality of longitudinal pieces of the multi-layer strip are formed.
[0076] Preferably, a plurality of longitudinal pieces of the multilayer strip are formed before each multilayer strip is wound onto a respective winding device.
[0077] Preferably, winding each multi-layer strip onto a respective winding device comprises winding each said longitudinal member onto a respective winding device.
[0078] Preferably, forming said plurality of longitudinal elements of the multi-layer strip comprises periodically and transversely cutting each of said sheets.
[0079] Preferably, said longitudinal elements of the multi-layer strip are all of the same length.
[0080] In a preferred embodiment, each of said sheets is cut periodically and transversely before said parallel strips are placed on a conveyor.
[0081] In an alternative embodiment, the electrode sheets are cut periodically and transversely before placing said parallel strips on the conveyor, and the strips of the diaphragm sheets are cut periodically and transversely after having been placed on the conveyor and before being wound onto the winding device.
[0082] In a preferred embodiment, each of said sheets is cut periodically and transversely after said parallel strips have been formed.
[0083] In an alternative embodiment, each of said sheets is cut periodically and transversely prior to forming said parallel strips.
[0084] Preferably, a second cutting member is provided.
[0085] In a preferred embodiment, a second cutting member is arranged between said service area and the conveyor.
[0086] Preferably, the second cutting member is configured to cut each of said sheets periodically and transversely.
[0087] Preferably, the second cutting member is arranged at or near the first cutting member.
[0088] In an alternative embodiment, a second cutting member for cutting the electrode sheets is arranged between the service area and the conveyor, and a second cutting member for cutting the diaphragm sheets is arranged between the conveyor and the winding device.
[0089] In an embodiment, before and / or after periodically and transversely cutting the electrode sheet, the feeding of the electrode sheet strip to the conveyor may be temporarily stopped or slowed down, thereby creating a gap between two consecutive longitudinal pieces of electrode sheet on the conveyor.
[0090] In this way, for each multilayer strip formed, the longitudinal pieces of the separator sheet protrude longitudinally from the longitudinal pieces of the electrode sheet. The electrochemical cell so formed will therefore have a peripheral portion formed exclusively by the separator sheet. This helps to isolate the electrode sheets.
[0091] Preferably, the parallel strips of first electrode sheet are placed on the conveyor in a position laterally offset relative to the parallel strips of first diaphragm sheet to produce a protruding side edge of the first electrode sheet in each multilayer strip.
[0092] Preferably, the parallel strips of the second diaphragm sheet are placed on the conveyor in a position laterally offset relative to the parallel strips of the first electrode plate.
[0093] Preferably, the parallel strips of the second electrode plate are placed on the conveyor in a position laterally offset relative to the parallel strips of the first and second diaphragm sheets.
[0094] Preferably, parallel strips of second electrode sheets are placed on the conveyor on the side opposite to the protruding side edges of the first electrode sheets to produce protruding side edges of the second electrode sheets in each multilayer strip.
[0095] After the electrochemical cell is wound, the protruding side edges form the electrical terminals of the electrochemical cell electrodes of the "tab-less" structure.
[0096] Preferably, the protruding side edges of the first electrode sheet are bent longitudinally before each multilayer strip is wound onto its respective winding device.
[0097] Preferably, the protruding side edges of the second electrode sheet are bent longitudinally before each multilayer strip is wound onto its respective winding device.
[0098] Preferably, a plurality of flexure members are provided.
[0099] Preferably, the bending members are arranged parallel to each other above the conveyor in a direction parallel to the feed direction.
[0100] Preferably, the bending members are configured to truncate respective side edges of the multi-layer strip.
[0101] In this way, the bending of the side edges mentioned above takes place continuously during the movement of the conveyor in the feed direction.
[0102] Preferably, the plurality of bending members include first bending members, each of the first bending members being configured to cut off a protruding side edge of a respective first electrode sheet.
[0103] Preferably, the plurality of bending members include second bending members, each of the second bending members being configured to cut off a protruding side edge of a respective second electrode sheet.
[0104] Preferably, each flexure has a helical profile.
[0105] Preferably, the helical profile extends along an axis parallel to the feed direction.
[0106] During the movement of the conveyor in the feed direction, the spiral profile gradually bends the above-mentioned protruding side edges.
[0107] Preferably, longitudinally bending the protruding side edge of the first electrode sheet comprises cutting the protruding side edge of the first electrode sheet by a first bending member when the conveyor moves along the feeding direction.
[0108] Preferably, longitudinally bending the protruding side edge of the second electrode sheet includes cutting the protruding side edge of the second electrode sheet by a second bending member when the conveyor moves along the feeding direction.
[0109] Preferably, after each multilayer strip has been wound onto the respective winding device, the protruding side edges of the first electrode sheet are flattened by turning the protruding side edges towards the winding axis of the respective winding device.
[0110] Preferably, after each multilayer strip has been wound onto the respective winding device, the protruding side edges of the second electrode sheet are flattened by turning the protruding side edges towards the winding axis of the respective winding device.
[0111] Flattening the protruding side edges allows the electrochemical cell terminal to be formed in a "lug-less" configuration.
[0112] Preferably, flattening the protruding side edge of the first electrode sheet comprises forming radial folds at the protruding side edge of the first electrode sheet relative to a winding axis of the respective winding device.
[0113] Preferably, flattening the protruding side edge of the second electrode sheet comprises forming radial folds at the protruding side edge of the second electrode sheet relative to a winding axis of the respective winding device.
[0114] Preferably, a plurality of pressurizing members are provided.
[0115] Preferably, each pressing member is arranged on a respective winding device.
[0116] Preferably, each pressing member is configured to flatten the protruding side edges of the first sheet and the second sheet.
[0117] Preferably, a plurality of cuts are formed in said protruding side edges before each multi-layer strip is wound onto a respective winding device.
[0118] The cutouts make the protruding side edges discontinuous in the longitudinal direction and simplify the flattening operation.
[0119] Preferably, a plurality of cuts are formed in said projecting side edges prior to forming the plurality of parallel strips of each sheet.
[0120] Preferably, a plurality of cuts are formed on the protruding side edges by cutting each sheet longitudinally.
[0121] Preferably, when forming the plurality of parallel strips, a plurality of cutouts are formed on the protruding side edges.
[0122] Preferably, the cutout extends on the protruding side edge from a free end of the protruding side edge to a curved inner end.
[0123] Preferably, the cut is J-shaped or sinusoidal. This reduces the risk of the cutting causing the strip to tear.
[0124] Preferably, a third cutting member is provided.
[0125] Preferably, the third cutting member is configured to form the plurality of cutouts on the protruding side edge.
[0126] Preferably, said third cutting member is arranged between said service area and the conveyor.
[0127] In an embodiment, the third cutting member is arranged at the first cutting member or is integrated with the first cutting member.
[0128] In an alternative embodiment, the third cutting member comprises a laser cutting device.
[0129] Preferably, after each longitudinal element has been wound onto a respective winding device, said winding device is replaced by another free winding device for winding thereon a subsequent longitudinal element of the same multilayer strip.
[0130] This reduces the idle time between winding one piece of multi-layered strip and the next.
[0131] In a preferred embodiment, the coil is prepared under dry ambient conditions.
[0132] Preferably, the coil is prepared under dry ambient conditions and maintained under such dry ambient conditions while the sheet is unwound from the coil.
[0133] In various embodiments, preparing the web includes placing the web in a dryer to evaporate solvents and other contaminants from the web.
[0134] In yet another different embodiment, the coil is prepared under atmospheric conditions and maintained under such atmospheric conditions as the sheet is unwound from the coil.
[0135] Preferably, impurities are continuously evaporated from the sheet material after unwinding the sheet material from the coil and before forming the plurality of multilayer strips on the conveyor.
[0136] As the diaphragm sheets are unwound from their respective coils, microwaves may be radiated toward the diaphragm sheets to vaporize impurities therefrom.
[0137] In an embodiment, the conveyor is arranged in a chamber under dry ambient conditions. This reduces the risk of contamination during the formation of the multilayer strip and when feeding it to the winding device.
[0138] Preferably, during feeding of said sheet material onto the conveyor, the sheet material is transferred from atmospheric ambient conditions to dry ambient conditions.
[0139] In various embodiments, the conveyor is placed in a location subject to atmospheric conditions.
[0140] Preferably, after each multi-layer strip is wound onto its respective winding device, the wound multi-layer strip is subjected to a drying process.
[0141] Preferably, the wound multilayer strip is dried by vacuum drying.
[0142] In an embodiment, the winding device is arranged in an offset position along the feed direction.
[0143] The offset position allows for accommodation of the mechanical components necessary to operate the winding apparatus while maintaining multiple layers of strip adjacent to one another.
[0144] In a different embodiment, the winding device is arranged in an offset position along a direction inclined relative to the feeding direction. This enables all longitudinal elements to move the same distance to reach the respective winding device.
[0145] Other features and advantages of the present description will become more apparent from the following detailed description of preferred embodiments thereof, which description is provided by way of illustrative and non-limiting examples, with reference to the accompanying drawings, in which:
[0146] -Figure 1 is a schematic side view of an apparatus for forming an electrochemical cell of a battery made in accordance with the present invention;
[0147] - Figure 2 for Figure 1 A schematic top view of a device with some components removed;
[0148] - Figure 2A for Figure 1 A detailed view of the details of the equipment;
[0149] - Figure 3 are schematic side views of various embodiments of apparatus for forming electrochemical cells of a battery made in accordance with the present invention;
[0150] - Figure 4 for Figure 3 A schematic top view of a device with some components removed;
[0151] - Figure 5 is a schematic top view of a portion of a multilayer strip formed by the apparatus of the preceding figures;
[0152] - Figure 6 for Figure 5 A schematic cross-sectional view of a multilayer strip;
[0153] - Figures 7 to 10 The Figures 1 to 4 Schematic cross-sectional views of a plurality of multilayer strips made in different configurations of a device;
[0154] - Fig.11 for Figure 5 A schematic top view of a detail of a multilayer strip;
[0155] - Fig.12 To be able to Figures 1 to 4 A radial cross-sectional view of an electrochemical cell obtained by using a device;
[0156] - Figures 13 to 16 It is shown that Figures 1 to 4 Schematic cross-sectional view of an electrochemical cell obtained with the device.
[0157] It is to be understood that the representations in the above drawings are not necessarily to scale, nor is the ratio between the parts to be considered. In the drawings, the same or similar elements of different embodiments will be indicated by the same reference numerals.
[0158] exist Figure 1 and Figure 2 Schematically shown in FIG. 1 is a device for forming electrochemical cells of a battery according to the invention, wherein the device is denoted by reference numeral 1 .
[0159] The apparatus 1 comprises a service area 10 configured to support four sheets of coils 11, 12, 13, 14 wound into a continuous strip. The service area 10 comprises four supports 15 (e.g. pins) on which the coils 11, 12, 13, 14 can be mounted and dismounted. The four supports 15 can be driven by motors to rotate the coils 11, 12, 13, 14, or they can be dragged to allow the coils 11, 12, 13, 14 to rotate freely.
[0160] exist Figure 1 In the embodiment shown, four support members 15 are arranged equidistantly in a vertical plane.
[0161] The axial dimension of each coil 11 , 12 , 13 , 14 measured along its respective winding axis is greater than 1 m, preferably about 2 m.
[0162] The diameter of each coil 11, 12, 13, 14 is from 0.4m to 2m, preferably from 0.6m to 1.5m, even more preferably from 0.8m to 1.2m.
[0163] The length of each coil 11, 12, 13, 14 of the wound sheet is 1000m to 100000m, preferably 3000m to 6000m, even more preferably 6000m to 40000m.
[0164] The first coil 11 of the four coils 11, 12, 13, 14 includes a first diaphragm sheet 11a wound in the form of a continuous belt. The first diaphragm sheet 11a is composed of a polymer material (e.g., polyethylene, polypropylene, or a combination of the two), is microporous, electrically insulating, and is configured to be impregnated with an electrolyte. The thickness of the diaphragm sheet 11a is 5 μm to 30 μm, preferably 10 μm to 25 μm, and even more preferably 15 μm to 20 μm.
[0165] The second coil 12 of the four coils 11, 12, 13, 14 comprises a first electrode sheet 12a wound in the form of a continuous strip. The first electrode sheet 12a comprises a conductive metal foil (e.g., an aluminum-based or copper-based metal foil) having a thickness of 2 μm to 20 μm, preferably 4 μm to 15 μm, and even more preferably 6 μm to 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, lithium and one of the following substances: cobalt oxide (LiCoO 2 ), manganese oxide (LiMn 2 O 4 ), nickel manganese cobalt oxide (NMC), lithium iron phosphate (LiFePO 4 ), lithium titanate (Li 2 TiO 3). The total thickness of the first electrode sheet 12a is 50 μm to 200 μm, preferably 100 μm to 150 μm, for example, about 125 μm.
[0166] The first electrode sheet 12a is intended to form, for example, the cathode of an electrochemical cell.
[0167] The third coil 13 of the four coils 11 , 12 , 13 , 14 comprises a second membrane sheet 13 a wound in the form of a continuous strip, similar to the first membrane sheet 11 a .
[0168] The fourth coil 14 of the four coils 11, 12, 13, 14 comprises a second electrode sheet 14a wound in the form of a continuous strip. The second electrode sheet 14a comprises a conductive metal sheet (e.g., an aluminum-based or copper-based conductive metal sheet) having a thickness of 2 μm to 20 μm, preferably 4 μm to 15 μm, and even more preferably 6 μm to 10 μm. The metal foil of the second electrode sheet 14a is coated with an anode material substrate, such as a graphite material, on one or both sides. The second electrode sheet 14a is intended to form, for example, an anode of an electrochemical cell.
[0169] The first diaphragm sheet 11a, the first electrode sheet 12a, the second diaphragm sheet 13a and the second electrode sheet 14a are intended to be unwound from respective coils 11, 12, 13, 14 and fed to the conveyor 20 along respective feed directions D1, D2, D3, D4, preferably parallel to each other.
[0170] exist Figure 1 In the illustrated embodiment, a first turning roller 16a is arranged next to the coils 11, 12, 13, 14 to turn the sheets 11a, 12a, 13a, 14a unwound from the coils 11, 12, 13, 14 toward the conveyor 20, and second turning rollers 16b are arranged in pairs downstream of the first turning roller 16 relative to the feed directions D1, D2, D3 and D4 to convey the sheets 11a, 12a, 13a, 14a turned by the first turning roller 16a to the conveyor 20.
[0171] In the embodiment shown, the service area 10 is arranged in a first chamber under atmospheric environmental conditions. The conveyor 20 is arranged in a second chamber 20a configured to maintain dry environmental conditions. A respective interface 17 is provided at each web 11, 12, 13, 14 between the first chamber 10a and the second chamber 20a. The interface 17 is configured to pass the sheet 11a, 12a, 13a, 14a towards the conveyor 20 while maintaining the dry environmental conditions of the second chamber 20a.
[0172] First cutting members 21, 22, 23, 24 are arranged between the service area 10 and the conveyor 20, preferably in the second chamber 20a, each cutting member to cut the sheets 11a, 12a, 13a, 14a along the respective feeding direction D1, D2, D3, D4 and cut 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 battery pack to be produced. In the preferred embodiment shown, the cross-sectional width of each strip 11b, 12b, 13b, 14b thus obtained is 70 mm to 90 mm, for example about 80 mm.
[0173] Figure 2 The strips 12b obtained after longitudinally cutting the first electrode sheet 12a are shown.
[0174] In a possible embodiment, each first cutting member 21, 22, 23, 24 comprises, for example, a pair of counter-rotating rollers configured to receive the respective sheets 11a, 12a, 13a, 14a therebetween and provided with respective blades configured to cut the sheets 11a, 12a, 13a, 14a longitudinally.
[0175] exist Figure 2 In FIG. 1 , it can be seen that a longitudinal cut 12c is made in the first electrode sheet 12a by the first cutting member 22 to form the strip 12b.
[0176] Second cutting members 26, 27, 28, 29 are arranged between the service area 10 and the conveyor 20, preferably in the second chamber 20a, each cutting member cutting the sheets 11a, 12a, 13a, 14a before they reach the conveyor 20 along a respective feed direction D1, D2, D3, D4.
[0177] In the embodiment shown, the second cutting members 26, 27, 28, 29 are arranged downstream of the first cutting members 21 , 22, 23, 24 in the respective feed direction D1 , D2, D3, D4.
[0178] The second cutting members 26, 27, 28, 29 are configured to periodically and transversely cut the strips 11b, 12b, 13b, 14b into discrete longitudinal pieces. Each longitudinal piece has a length of 5000 mm to 7000 mm, for example about 6000 mm.
[0179] 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 this 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, while the first cutting members 21, 22, 23, 24 act on the sheets 11a, 12a, 13a, 14a that have been cut into longitudinal pieces by the second cutting members 26, 27, 28, 29 to form strips 11b, 12b, 13b, 14b.
[0180] exist Figure 2 In FIG. 1 , the longitudinal cut 12d formed by the second cutting member 27 in the first electrode sheet 12a can be seen.
[0181] Preferably, the conveyor 20 is arranged below the service area 10 and is configured to receive sheets 11a, 12a, 13a, 14a that have been longitudinally cut into parallel strips 11b, 12b, 13b, 14b by first cutting members 21, 22, 23, 24 and transversely cut into longitudinal pieces by second cutting members 26, 27, 28, 29.
[0182] The conveyor 20 comprises a conveyor belt 30 movable in a feed direction D with a horizontal conveyor plane.
[0183] Preferably, the conveyor 20 may move at a speed of 0.5 m / s to 2 m / s, for example, at a speed of about 1 m / s.
[0184] The conveyor 20 receives the longitudinal pieces of the strip 11 b of the first membrane sheet 11 a such that their longitudinal direction is parallel to the feed direction D.
[0185] The conveyor 20 also receives the longitudinal pieces of the strip 12b of the first electrode sheet 12a 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 11b of the first diaphragm sheet 11a.
[0186] Similarly, the conveyor 20 receives the longitudinal pieces of the strip 13b of the second membrane sheet 13a in such a way 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 12b of the first electrode sheet 12a.
[0187] 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 diaphragm sheet 13a.
[0188] In this way, a plurality of multi-layer strips 35 are formed on the conveyor 20, each of the multi-layer strips 35 including a first layer 35a defined by a longitudinal piece of the strip 11b of the first diaphragm 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 diaphragm 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.
[0189] The multi-layer strips 35 obtained from the single strip 11b, the single strip 12b, the single strip 13b and the single strip 14b are arranged sequentially on the conveyor 20 along the feed direction D, while the multi-layer strips 35 obtained from the parallel strips 11b, 12b, 13b, 14b are arranged parallel to each other along the direction orthogonal to the feed direction D on the conveyor 20.
[0190] The webs 11, 12, 13, 14 are positioned relative to the conveyor 20 such that in each multilayer strip 35, the strips 12b of the first electrode sheet 12a (and therefore the second layer 35b) are placed on the respective strips 11b of the first diaphragm sheet 11a at a position laterally offset relative to the respective strips 11b of the first diaphragm sheet 11a (and therefore the first layer 35a); and each strip 13b of the second diaphragm sheet 13a (and therefore the third layer 35c) is placed on the lower strip 11b of the first diaphragm sheet 11a (and therefore the first layer 35c). a) are placed in a laterally aligned position on the respective strips 12b of the first electrode sheet 12a (and therefore the second layer 35b); each strip 14b of the second electrode sheet 14a (and therefore the fourth layer 35d) is placed on the respective strips 13b of the second diaphragm sheet 13a (and therefore the third layer 35c) on the side opposite to the strips 12b of the first electrode sheet 12a (and therefore the second layer 35b) and in a position laterally offset relative to the lower strip 11b of the first isolation sheet 11a (and therefore the first layer 35a).
[0191] For example, the strip 12b of the first electrode sheet 12a (and therefore the second layer 35b) is laterally offset by a distance of 1 mm to 10 mm, preferably 3 mm to 7 mm, for example, about 5 mm; the strip 14b of the second electrode sheet 14a (and therefore the fourth layer 35d) is again laterally offset by a similar distance on the side opposite to the strip 11b of the first diaphragm sheet 11a (and therefore the first layer 35a) and the strip 13b of the second diaphragm sheet 13a (and therefore the third layer 35c), such as Figure 5 and Figure 6 shown.
[0192] In this way, in each multilayer strip 35, a protruding side edge 36 of a first electrode sheet protruding on one side of the strips 11b, 13b relative to the diaphragm sheets 11a, 13a and a protruding side edge 37 of a second electrode sheet 14a protruding on the opposite side of the protruding side edge 36 of the first electrode sheet 12a relative to the strips 11b, 13b of the diaphragm sheets 11a, 13a are produced.
[0193] like Figures 9 and 10 As shown, a plurality of first bending members 40a are arranged on the conveyor 20. The first bending members 40a extend longitudinally along the feed direction D. The first bending members 40a are arranged parallel to each other, and each of them is configured to intercept the protruding side edge 36 of the first electrode sheet 12a of the respective multilayer strip 35 and bend it longitudinally upward.
[0194] Similarly, if Figures 8 to 10 As shown, a plurality of second bending members 40b are arranged on the conveyor 20. The second bending members 40b extend longitudinally along the feed direction D. The second bending members 40b are arranged parallel to each other, side by side with the first bending members 40a, and each of them is configured to intercept the protruding side edge 37 of the second electrode sheet 14a of the respective multilayer strip 35 and bend it longitudinally upward.
[0195] The curved members 40a, 40b have a respective helical profile 41 extending along a helical axis parallel to the feed direction D, starting from a substantially horizontal orientation to an orientation gradually inclined relative to a horizontal plane moving in the feed direction D.
[0196] For example Fig. 9 As shown, in the embodiment shown, the opposing side edges 38, 39 of the strip 11b of the diaphragm sheet 11a and the strip 13b of the diaphragm sheet 13a are also longitudinally bent together with the protruding side edges 36, 37 of the strips 12b, 14b of the electrode sheets 12a, 14a.
[0197] A plurality of winding devices 50 are arranged downstream of the conveyor 20 with respect to the feed direction D.
[0198] Each winding device 50 is configured to receive a respective multi-layer strip 35 .
[0199] Each winding device 50 may, for example, include an electromechanical pin around which the multi-layer strip 35 is wound to form a jelly-roll type electrochemical cell.
[0200] like Figure 2AAs shown in detail in FIG. 1 , an additional winding device 50 a is arranged next to each winding device 50 so that the winding device 50 can be replaced when a longitudinal piece of the multilayer strip 35 is wound to the end on the winding device 50 to receive the next longitudinal piece of the multilayer strip 35 .
[0201] exist Figure 1 and 2 In the embodiment shown, the winding device 50 is arranged offset in the feed direction D in order to accommodate the components required for its operation.
[0202] Figure 3 and Figure 4 Shows something like Figure 1 or Figure 2 The device 1 of the present invention is different in that the winding device 50 is arranged offset in a direction inclined relative to the feeding direction D and preferably also inclined relative to the horizontal plane, so that all multi-layer strips 35 move the same distance from the time they are formed on the conveyor 20 to the time they reach the respective winding device 50. The offset of the winding device 50 can also depend on the mutual position of the coils 11, 12, 13, 14 and the position of the coils 11, 12, 13, 14 relative to the conveyor 20, so that the sheets 11a, 12a, 13a and 14a all move the same distance from the time they are unwound from the coils 11, 12, 13, 14 to the time they are placed on the conveyor 20 in the form of strips 11b, 12b, 13b, 14c to form the multi-layer strip 35.
[0203] In this embodiment, each second cutting member 26, 27, 28, 29 may be configured to transversely cut the strip 11b, 12b, 13b, 14b of the respective sheet 11a, 12a, 13a, 14a by a single straight transverse cut. Figure 4 As shown, the longitudinal elements of the strips 11b, 12b, 13b, 14b of each sheet 11a, 12a, 13a, 14a thus obtained are aligned transversely.
[0204] exist Figure 3 and 4 In an embodiment, the second cutting members 26, 28 can be arranged between the conveyor 20 and the winding device 50 in such a way that the strips 11b, 13b of the diaphragm sheets 11a, 13a extend continuously between the coils 11, 13 and the conveyor 20 and are cut transversely upstream of the winding device 50.
[0205] 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 each other. In this way, the longitudinal pieces of some strips 11b, 12b, 13b, 14b protrude relative to other longitudinal pieces at the longitudinal ends of each longitudinal piece of the multi-layer strip 35.
[0206] exist Figure 4 In the embodiment of the present invention, 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 shorter in the longitudinal direction than the longitudinal pieces of the strips 11b, 13b of the diaphragm sheets 11a, 13a. In this way, at the longitudinal ends of each longitudinal piece of the multilayer strip 35, the longitudinal pieces of the strips 11b, 13b of the diaphragm sheets 11a, 13a protrude longitudinally relative to the longitudinal pieces of the strips 12b, 14b of the electrode sheets 12a, 14a. Figure 4 Respective breaks 55 between consecutive longitudinal pieces of the strip 12b of the first electrode sheet 12a are shown.
[0207] like Fig.12 As shown, a pair of pressing members 80 are provided at each winding device 50 , and the pressing members are configured to flatten the axially protruding protruding side edges 36 , 37 after the multi-layer strip 35 is wound onto the winding device 50 , so that they are inclined toward the winding axis A of the respective winding device 50 .
[0208] In an embodiment, a third cutting member (not shown) is provided. The third cutting member is configured to form a plurality of transverse cuts 60 on the edges of the strip 12b of the first electrode sheet 12a and the strip 14b of the second electrode sheet 14a, such as Fig.11 As shown, these cutouts are intended to form projecting side edges 36 , 37 .
[0209] The third cutting member may, for example, comprise an insert mounted on the rollers of the first cutting member 22 , 24 or a computer numerically controlled laser cutting device.
[0210] The third cutting member is configured to form each cutout 60 from a free end 61 of a side edge of the respective strip 12b , 14b in an oblique direction toward the inside of the strip 12b , 14b to form a curved inner end 62 .
[0211] For example, the cutout 60 may be sinusoidal or J-shaped.
[0212] The plurality of cutouts 60 define a plurality of notches 60 a on the protruding side edges 36 , 37 , and the notches 60 a are configured to be bent by the bending members 40 a , 40 b and turned over by the above-mentioned pressing member 80 .
[0213] To simplify the explanation, Fig.11 In the diagram, reference numerals 60 , 61 , 62 , 60 a are shown at some of these cutouts 60 .
[0214] To produce an electrochemical cell of a battery, four coils 11 , 12 , 13 , 14 of the above-described type are prepared, each comprising a wound first separator sheet 11 a , a wound first electrode sheet 12 a , a wound second separator sheet 13 a and a wound second electrode sheet 14 a .
[0215] The four coils 11 , 12 , 13 , 14 may be formed under atmospheric conditions, and the respective sheets 11 a , 12 a , 13 a , 14 a may be subjected to a contaminant removal treatment, such as a solvent evaporation treatment, before being wound into the respective coils 11 , 12 , 13 , 14 .
[0216] The four coils 11, 12, 13, 14 are mounted on respective supports 15 provided in the service area 10. In the embodiment shown, the service area 10 is kept under atmospheric ambient conditions during the unwinding of the coils 11, 12, 13, 14. In an alternative embodiment not shown, the service area 10 is kept under dry ambient conditions during the unwinding of the coils 11, 12, 13, 14.
[0217] In the preferred embodiment shown, four coils 11 , 12 , 13 , 14 are arranged in the following manner with respect to the feed direction D: starting from the most upstream to the most downstream: the first coil 11 , the second coil 12 , the third coil 13 and the fourth coil 14 .
[0218] In a different embodiment not shown, the four coils 11 , 12 , 13 , 14 may be arranged relative to the feed direction D in the following manner: starting from the most upstream to the most downstream: the second coil 12 , the first coil 11 , the fourth coil 14 and the third coil 13 .
[0219] The sheets 11 a , 12 a , 13 a , and 14 a are unwound from respective coils 11 , 12 , 13 , 14 , and fed to the conveyor 20 along feed directions D1 , D2 , D3 , D4 .
[0220] In an embodiment not shown, the sheets 11a, 12a, 13a and 14a are treated after being unwound from the respective coils 11, 12, 13, 14 to remove any impurities.
[0221] In the preferred embodiment shown, the sheets 11a, 12a, 13a and 14a enter the second chamber 20a having dry ambient conditions through respective interfaces 17. This can be avoided by providing an embodiment in which the conveyor 20 is also maintained under atmospheric ambient conditions.
[0222] Subsequently, the sheets 11a, 12a, 13a, 14a are cut longitudinally by cutting members 21, 22, 23, 24 to form a plurality of parallel strips 11b, 12b, 13b and 14b from each sheet.
[0223] Then, the strips 11b, 12b, 13b and 14b are periodically and transversely cut into a plurality of longitudinal pieces by second cutting members 26, 27, 28, 29.
[0224] exist Figure 3 , Figure 4 In the embodiment of FIG. 1 , the strips 11b, 12b, 13b, 14b of each sheet 11a, 12a, 13a, 14a are cut together by a single straight transverse cut.
[0225] The strips 11b, 12b, 13b, 14b of each multilayer strip 35 can be cut at positions longitudinally offset from each other so that at the longitudinal ends of each longitudinal piece of the multilayer strip 35, some longitudinal pieces of the strips 11b, 12b, 13b, 14b protrude relative to other longitudinal pieces.
[0226] exist Figure 3 , Figure 4 In an embodiment, before or after transversely cutting the strips 12b, 14b of the electrode sheets 12a, 14a, the speed at which the strips 12b, 14b of the electrode sheets 12a, 14a are fed onto the conveyor 20 is temporarily slowed down or stopped to form gaps 55 between continuous longitudinal pieces of the strips 12b, 14b.
[0227] In an embodiment not shown, the cut 60 is formed on the side edge of the strip 12b of the first electrode sheet 12a (the side edge is intended to form the protruding side edge 36 of the first electrode sheet 12a) and on the side edge of the strip 14b of the second electrode sheet 14a (the side edge is intended to form the protruding side edge 37 of the second electrode sheet 14a).
[0228] These cutouts 60 define recesses 60 a on the projecting side edges 36 , 37 .
[0229] The longitudinal pieces of parallel strips 11 b , 12 b , 13 b and 14 b are then placed on the conveyor 20 .
[0230] In the preferred embodiment shown, the strip 11b of the first diaphragm sheet 11a is placed first (specifically, the longitudinal pieces of the strip 11b) and then the strip 12b of the first electrode sheet 12a is placed (specifically, the longitudinal pieces of the strip 12b are placed on the longitudinal pieces of the strip 11b, and the other longitudinal pieces of the strip 11b are placed on the conveyor 20), and then the strip 13b of the second diaphragm sheet 13a is placed (specifically, the longitudinal pieces of the strip 13b are placed on the longitudinal pieces of the strip 12b, and the other longitudinal pieces of the strip 12b are placed on the longitudinal pieces of the strip 11b), and finally the strip 14b of the second electrode sheet 14a is placed (specifically, the longitudinal pieces of the strip 14b are placed on the longitudinal pieces of the strip 13b, and the other longitudinal pieces of the strip 13b are placed on the longitudinal pieces of the strip 12b).
[0231] The order of the strips 11b, 12b, 14b on the conveyor 20 from bottom to top corresponds to the order of the coils 11, 12, 13, 14 with respect to the feed direction D from upstream to downstream.
[0232] Thus, planar, adjacent and parallel longitudinal pieces of the multilayer strip 35 are formed on the conveyor 20, each of the longitudinal pieces comprising respective layers 35a, 35b, 35c, 35d offset as described above, thereby forming 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 multilayer strip 35.
[0233] As the longitudinal pieces of multilayer strip 35 are formed, they are moved in the feed direction D while maintaining the continuous movement of the conveyor belt 30 , thereby feeding the aforementioned longitudinal pieces to the respective winding devices 50 .
[0234] During movement of the conveyor 20, the first and second bending members 40a, 40b bend the protruding side edges 36, 37 of the first and second electrode sheets 12a, 14a and, in the illustrated embodiment, the side edges 38 and 39 of the diaphragm sheets 11a and 13a longitudinally upwards.
[0235] Next, each longitudinal piece of the multilayer strip 35 is wound onto a respective winding device 50. The longitudinal pieces of the multilayer strip 35 can be wound, for example, by rotating the pins of the winding device 50. The longitudinal pieces of the multilayer strip 35 parallel to each other can be wound simultaneously.
[0236] In an embodiment not shown, the strips 12b, 14b of the electrode sheets 12a, 14a are cut periodically and transversely before being fed to the conveyor 20, while the strips 11b, 13b of the diaphragm sheets 11a, 13a are cut periodically and 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 the diaphragm sheets 11a, 13a extend continuously along the conveyor 20, and the longitudinal pieces 12b, 14b of the electrode sheets 12a, 14a are conveyed along the conveyor 20.
[0237] Next, the protruding side edge 36 of the first electrode sheet 12 a and the protruding side edge 37 of the second electrode sheet 14 a are flattened.
[0238] During this flattening process, the protruding side edges 36, 37 can be circumferentially continuous. This will produce a plurality of radial folds on the protruding side edges 36, 37.
[0239] Optionally, the protruding side edges 36, 37 may be separated in the above-mentioned notches 60a by making cuts 60. In this case, adjacent notches 60a partially overlap during flattening.
[0240] Fig.12 A radial cross section of an electrochemical cell 70 is shown, comprising a multilayer strip 35 wound around a respective winding axis A and having respective protruding side edges 36, 37 flattened.
[0241] During winding of each multi-layer strip 35 around a respective winding device 50, the additional winding device 50a remains stationary adjacent to the winding device 50. After winding of the multi-layer strip 35 around the winding device 50, the winding device 50 is removed and replaced by the additional winding device 50a.
[0242] Figures 13 to 16 Schematically shown is a cross section of a respective electrochemical cell 70 that can be obtained by different embodiments according to the invention.
[0243] Fig.13 and Fig.15 The electrochemical cell 70 has, moving from the inside to the outside in the radial direction, a strip 11b of the first diaphragm sheet 11a, a strip 12b of the first electrode sheet 12a, a strip 13b of the second diaphragm sheet 13a, and a strip 14b of the second electrode sheet 14a. This distribution can be achieved by feeding the multilayer strip 35 from above to the winding device 50 and bringing the winding device 50 into contact with the strip 11b of the first diaphragm sheet 11a.
[0244] Fig.14 and Fig.16The electrochemical cell 70 is radially moved from the outside to the inside and has: a strip 11b of the first diaphragm sheet 11a, a strip 12b of the first electrode sheet 12a, a strip 13b of the second diaphragm sheet 13a, and a strip 14b of the second electrode sheet 14a. This distribution is achieved by feeding the multilayer strip 35 from below to the winding device 50 and bringing the winding device 50 into contact with the strip 14b of the second electrode sheet 14a.
[0245] exist Fig.13 and Fig.14 In the electrochemical cell 70 of the embodiment of the present invention, the longitudinal pieces of the strips 12b, 14b of the electrode sheets 12a, 14a are offset in the circumferential direction relative to the longitudinal pieces of the strips 11b, 13b of the diaphragm sheets 11a, 13a. As described above, this is achieved by transversely cutting the sheets 11a, 12a, 13a, 14a at the longitudinally offset positions.
[0246] exist Fig.15 and Fig.16 In the electrochemical cell 70 of the embodiment, 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. As described above, this is achieved by forming gaps 55 between continuous longitudinal pieces of the electrode sheets 12a, 14a. In these embodiments, after winding the multi-layer strips 35, the protruding portions of the separator sheets 11a, 13a can be melted together to stabilize the electrochemical cell 70.
[0247] In an embodiment not shown, in which conveyor 20 is maintained at atmospheric conditions, electrochemical cell 70 is dried after winding, for example by vacuum drying after winding.
[0248] Obviously, a person skilled in the art may make numerous modifications and variations to the invention described above in order to meet specific and contingent needs, while remaining within the scope of protection defined by the appended claims.
Claims
1. A method for forming an electrochemical cell of a battery, comprising: - preparing a coil (11) including a winding of a first diaphragm sheet (11a), a coil (12) including a winding of a first electrode sheet (12a), a coil (13) including a winding of a second diaphragm sheet (13a), and a coil (14) including a winding of a second electrode sheet (14a); - feeding the sheets (11a, 12a, 13a, 14a) to a conveyor (20) by unwinding the sheets from their respective coils (11, 12, 13, 14); - forming a plurality of multilayer strips (35) on the conveyor (20), each multilayer strip (35) comprising a first layer (35a) of the first diaphragm sheet (11a), a second layer (35b) of the first electrode sheet (12a) overlapping the first layer (35a), a third layer (35c) of the second diaphragm sheet (13a) overlapping the second layer (35b), and a fourth layer (35d) of the second electrode sheet (14a) overlapping the third layer (35c), the conveyor (20) being movable along a feed direction (D); - feeding each multilayer strip (35) to a respective winding device (50) via said conveyor (20); - Each multilayer strip (35) is wound onto a respective winding device (50).
2. The method according to claim 1, comprising: 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) when said sheets are fed to a conveyor (20); - On the conveyor (20), firstly, parallel strips (11b) of the first diaphragm sheet (11a) are placed, then parallel strips (12b) of the first electrode sheet (12a), then parallel strips (13b) of the second diaphragm sheet (13a), and then parallel strips (14b) of the second electrode sheet (14a) are placed.
3. The method according to claim 2, wherein: - the parallel strips (12b) of the first electrode sheet (12a) are placed on the conveyor (20) in a position laterally offset relative to the parallel strips (11b) of the first diaphragm sheet (11a) so as to produce a protruding side edge (36) of the first electrode sheet (12a) in each multilayer strip (35); - the parallel strips (14b) of the second diaphragm sheet (13a) are placed on the conveyor (20) in a transversely offset position relative to the parallel strips (12b) of the first electrode sheet (12a); - The parallel strips (14b) of the second electrode sheet (14a) are placed on the conveyor (20) at a position laterally offset relative to the parallel strips (11b, 13b) of the first diaphragm sheet (11a) and the second diaphragm sheet (13a), and opposite to the protruding side edges (36) of the first electrode sheet (12a) to produce protruding side edges (37) of the second electrode sheet (14a) in each multilayer strip (35).
4. The method according to claim 3, comprising: Before each multilayer strip (35) is wound onto a respective winding device (50), the protruding side edges (36) of the first electrode sheet (12a) and the protruding side edges (37) of the second electrode sheet (14a) are bent longitudinally.
5. The method according to claim 4, wherein: - longitudinally bending the protruding side edge (36) of the first electrode sheet (12a) comprises cutting off the protruding side edge (36) of the first electrode sheet (12a) by a first bending member (40a) when the conveyor (20) moves along the feeding direction (D); - longitudinally bending the protruding side edge (37) of the second electrode sheet (14a) includes cutting off the protruding side edge (37) of the second electrode sheet (14a) by a second bending member (40b) when the conveyor (20) moves along the feed direction (D).
6. The method according to claim 5, comprising: After each multilayer strip (35) is wound onto a respective winding device (50), the protruding side edges (36) of the first electrode sheet (12a) and the protruding side edges (37) of the second electrode sheet (14a) are flattened by flipping them toward the winding axis (A) of the respective winding device (50).
7. The method according to any one of claims 4 to 6, comprising: Before each multilayer strip (35) is wound onto a respective winding device (50), a plurality of cuts (60) are made in the protruding side edges (36, 37).
8. Method according to claim 7, wherein the cutout (60) extends from a free end (61) of the protruding side edge (36, 37) to a curved inner end (62).
9. The method according to any one of the preceding claims, comprising: Before each multilayer strip (35) is wound onto its respective winding device (50): - a plurality of longitudinal elements forming a multi-layer strip (35); and wherein winding each multilayer strip (35) onto a respective winding device (50) comprises: - Winding each of said longitudinal elements onto a respective winding device (50).
10. The method according to claim 9 as appended to claim 2, wherein: The plurality of longitudinal pieces forming the multi-layer strips (35) include periodically and 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).
11. Apparatus (1) for forming an electrochemical cell of a battery, comprising: - a service area (10) configured to support a coil (11) including a first diaphragm sheet (11a) winding, a coil (12) including a first electrode sheet (12a) winding, a coil (13) including a second diaphragm sheet (13a) winding and a coil (14) including a second electrode sheet (14a) winding; a conveyor (20) configured to support a plurality of multilayer strips (35), each multilayer strip (35) comprising a first layer (35a) of the first diaphragm sheet (11a), a second layer (35b) of the first electrode sheet (12a) overlapping the first layer (35a), a third layer (35c) of the second diaphragm sheet (13a) overlapping the second layer (35b), and a fourth layer (35d) of the second electrode sheet (14a) overlapping the third layer (35c), the conveyor (20) being movable in a feed direction (D); - a plurality of winding devices (50) arranged downstream of said conveyor (20) with respect to said feed direction (D) and configured to receive each respective multilayer strip (35).
12. The device (1) according to claim 11 further comprises a first cutting member (21, 22, 23, 24), which is arranged between the service area (10) and the conveyor (20) and is configured to cut each of the sheets (11a, 12a, 13a, 14a) longitudinally into parallel strips (11b, 12b, 13b, 14b).
13. The device (1) according to claim 11 or 12 also includes a second cutting member (26, 27, 28, 29), which is arranged between the service area (10) and the conveyor (20) and is configured to periodically and transversely cut each of the sheets (11a, 12a, 13a, 14a).
14. The device (1) according to any one of claims 11 to 13 comprises a plurality of bending members (40a, 40b) arranged parallel to each other above the conveyor (20), the bending members extending in a direction parallel to the feed direction (D) and configured to cut off the respective side edges of the multi-layer strip (35).
15. Apparatus (1) according to claim 14, wherein each of said curved members (40a, 40b) has a helical profile (41 ).