Method and unit for manufacturing a cell for an electric battery

Abstract

The invention relates to a method for producing an electric cell comprising a plurality of electrodes stacked on top of one another and separated from one another by a porous separator film, the method comprising: - a step of producing the electrodes; - a step of stacking the electrodes one on top of another to form a stack of electrodes, wherein the electrodes are separated by a porous separator film, in which method the step of producing the electrodes comprises: - an operation of unwinding a wound electrode sheet (4); and - a primary marking operation of marking the electrode sheet (4) by means of a primary identification element (5), wherein the marking operation is carried out after the operation of unwinding the electrode sheet (4), and wherein the marking operation is repeated continuously as the wound electrode sheet is unwound.

Description

Method and unit for manufacturing a cell for an electric battery Technical field of the invention

[0001] The invention relates to the field of rechargeable electric batteries for electric motor vehicles. In particular, the invention relates to the manufacture of electric cells intended to equip electric batteries. More specifically, the invention relates to a method and a unit for manufacturing lithium-ion electrochemical cells of the "pouch" type, i.e. cells in a bag. The invention may also relate to a method and a unit for manufacturing lithium-ion electrochemical cells of the prismatic type. Technical background

[0002] There are several types of electric cells. These include, for example, pouch cells and prismatic cells. These types of cells can contain one or more stacks of electrodes. An electrode stack is formed by stacking electrodes on top of each other. Electrodes of opposite polarity are separated from each other by a porous separator film.

[0003] Manufacturers want to be able to achieve complete traceability of electrodes from their production to their assembly.

[0004] In particular, manufacturers want to be able to know the characteristics of each electrode as well as their relative position in the electrode stack.

[0005] Attempts to achieve complete traceability of electrodes have proved unsuccessful. There are several reasons for these failures, including, among others: - industrial production rates that make marking operations extremely complex, and - the very nature of the electrodes, which are thin, on the order of a few tens of micrometers.

[0006] The invention therefore aims to propose a functional technical solution allowing complete traceability of the electrodes.

[0007] To this end, there is firstly proposed a method for producing an electric cell comprising a plurality of electrodes stacked on top of each other and separated from each other by a porous separator film, the method comprising:- a step of producing the electrodes,- a step of stacking the electrodes on top of each other to form a stack of electrodes, said electrodes being separated by a porous separator film,method in which the step of producing the electrodes comprises:- an operation of unwinding a coil of an electrode sheet, and- an operation of primary marking the electrode sheet by means of a primary identification element, said marking operation being carried out after the operation of unwinding the electrode sheet, said marking operation being repeated continuously as long as the coil of electrode sheet is unwound,- an operation of cutting the electrode sheet so as to form electrodes distinct from one another, said primary marking operation being carried out before said cutting operation;method in which the step of stacking the electrodes comprises:- an operation of secondary marking of the stack of electrodes by means of a secondary identification element;- an operation of reading the primary identification element of each electrode,- a plurality of operations of stacking the electrodes on top of one another separated by a porous separator film,- an operation of reading the secondary identification element,- an operation of associating the information of each of the electrodes of the stack of electrodes and their respective position in the stack of electrodes, this association being carried out with the secondary identification element,this information being known thanks to the reading operations of the primary identification elements of each electrode.,

[0008] By marking the electrode sheet with a primary identification element, it becomes possible to ensure complete traceability of the electrode. In particular, it becomes possible to record all the parameters inherent in the manufacture of the electrodes.

[0009] The operation of associating the information of each of the electrodes of the electrode stack and their respective position in the electrode stack makes it possible to know precisely the information and the position in the stack of each electrode. This advantageously results in complete traceability of the electrodes from their production to their assembly. Thanks to such an association, the primary identification elements can be sectioned, while being able to obtain all the information relating to each electrode of the electrode stack by reading the secondary identification element.

[0010] Various additional features may be provided alone or in combination:- this comprises an operation of coating an active material on the electrode sheet, in which method the primary marking operation is carried out before said coating operation, in which method this comprises:- an operation of reading the primary identification element, and- an operation of associating at least one parameter inherent to the coating operation with the primary identification element identified during the operation of reading said primary identification element;- this comprises an operation of calendering the electrode sheet, in which method the primary marking operation is carried out before said calendering operation, in which method it comprises:- an operation of reading the primary identification element, and- an operation of associating at least one parameter inherent to the calendering operation with the primary identification element identified during the operation of reading said primary identification element;- this comprises an operation of drying the electrode sheet, in which method the primary marking operation is carried out before said drying operation, in which method it comprises:- an operation of reading the primary identification element, and- an operation of associating at least one parameter inherent to the drying operation with the primary identification element identified during the operation of reading said primary identification element;this comprises:- an operation of reading the primary identification element, and- an operation of associating at least one parameter inherent to the cutting operation with the primary identification element identified during the operation of reading said primary identification element;- this comprises a step of cutting the primary identification elements, so that the electrode stack now only comprises one secondary identification element;- the operation of marking the primary identification element is carried out so that two primary identification elements are separated by a separation distance of between 35 millimeters and 110 millimeters, which separation distance is measured in a direction of movement of the electrode sheet;- the operation of marking the primary identification element is carried out so that two primary identification elements are separated by a separation distance less than a width of the electrodes measured in a direction of movement of the electrode sheet; - the separation distance is substantially equal to 38 millimeters; - the operation of marking the primary identification element is carried out so that the primary identification elements are located at an end distance, greater than or equal to 1 millimeter, said end distance being measured from a lateral end of the electrode sheet in a transverse direction substantially perpendicular to the direction of movement and in a plane of the electrode sheet;- the primary marking operation of the primary identification element is carried out so that said primary identification elements are located on a metal portion of the electrode sheet not coated with an active material and said primary identification elements are located at a lateral distance from an active portion of the electrode sheet coated with an active material, and the lateral distance being measured in a transverse direction substantially perpendicular to the direction of movement of the electrode sheet and in a plane of the electrode sheet, method in which, the lateral distance is at least equal to 5 millimeters;- the lateral distance is at least equal to 5 millimeters;- the lateral distance is at least equal to 11 millimeters.;

[0011] Secondly, an electric cell obtained by means of a method as previously described is proposed.

[0012] Thirdly, an electric cell production unit is proposed, the unit comprising:- an electrode production unit comprising a device for unwinding a reel of electrode sheet and a device for printing a primary identification element,- an electrode stacking unit,- a computer unit, the cell production unit being capable of implementing a method as previously described.

[0013] Various additional features may be provided alone or in combination:- the electrode production unit comprises:- a coating device comprising a device for reading a primary identification element;- the electrode production unit comprises:- a calendering device comprising a device for reading a primary identification element;- the electrode production unit comprises:- a drying device comprising a device for reading a primary identification element;- the electrode production unit comprises:- a cutting device comprising a device for reading a primary identification element;- it comprises a device for printing a secondary identification element and at least one device for reading a secondary identification element;- it comprises a cutting device. Brief description of the figures

[0014] Other characteristics and advantages of the invention will appear during the reading of the detailed description which follows for the understanding of which reference will be made to the appended drawings in which:

[0015] is a schematic representation of a method according to the invention.

[0016] is a schematic representation of a stack of electrodes according to the invention.

[0017] is a schematic representation of an electrode sheet according to the invention.

[0018] is a schematic representation of a cell production unit according to the invention. Detailed description of the invention

[0019] In the following a method 1 for producing an electric cell will be described.

[0020] The cell comprises a plurality of electrodes 2. The electrodes 2 are stacked on top of each other and separated from each other by a porous separator film 3.

[0021] The method 1 comprises, among other things, a step E1 of producing the electrodes 2 and a step E2 of stacking the electrodes 2 on top of each other to form a stack 32 of electrodes.

[0022] Step E1 of producing the electrodes 2 comprises an operation O1 of unwinding a coil 6 of an electrode sheet 4. Initially, that is to say in the coil 6, the electrode sheet 4 is a metal sheet which contains for example copper or aluminum depending on whether it is used as an anode or cathode.

[0023] With reference to the, the production step E1 comprises an operation O2 of primary marking of the electrode sheet 4. The primary marking operation O2 consists of affixing a primary identification element 5 on the electrode sheet 4.

[0024] The primary marking operation O2 is carried out after the operation O1 of unwinding the electrode sheet 4 and is repeated continuously. The primary marking operation O2 is advantageously carried out substantially immediately after unwinding the electrode sheet 4 and in particular before said electrode sheet 4 undergoes other operations. In other words, a primary identification element 5 is affixed to the electrode sheet 4 while the latter is continuously unwound.

[0025] The primary identification element 5 is affixed by means of a primary printing device 27. The primary identification element 5 is for example a QR code.

[0026] By thus marking the electrode sheet 4 with a primary identification element 5, it becomes possible to ensure complete traceability of the electrode 2. In particular, it becomes possible to record all the parameters inherent in the manufacture of the electrodes 2.

[0027] Advantageously, the production step E1 comprises an operation O3 of coating an active material carried out by means of a coating device 7. The electrode sheet 4 is coated with an active material which is the site of electrochemical reactions, useful for the operation of the electric cell.

[0028] Advantageously, the primary marking operation is carried out before the coating operation. Indeed, and as previously mentioned, the primary marking operation is carried out substantially immediately after the operation of unwinding the electrode sheet.

[0029] The method comprises an operation O4 of reading the primary identification element. This reading operation is carried out by means of a reading device 8 specific to the coating device 7.

[0030] The method 1 comprises an operation O5 of associating at least one parameter inherent to the coating operation O3 with the primary identification element 5 identified during the reading operation O4 specific to the coating operation.

[0031] In other words, a reading of the primary identification element 5 is carried out, the parameters of the coating operation O3 such as for example the pressure, temperature and all the other parameters of interest are associated with the primary identification element 5. This association is carried out by storing in a computer unit 9 said parameters associated with the corresponding primary identification element 5.

[0032] Thus it becomes possible to precisely assign the parameters inherent to the O3 coating operation to a given electrode 2.

[0033] Advantageously, the operation O4 of reading the primary identification element 5 is carried out before the coating operation O3 in order to facilitate the association operation O5.

[0034] Advantageously, the production step E1 comprises a calendering operation O6. The electrode sheet 2 is passed through a calendering device 10.

[0035] Advantageously, the primary marking operation O2 is carried out before the calendering operation O6. Indeed, and as previously mentioned, the primary marking operation O2 is carried out substantially immediately after the operation O1 of unwinding the electrode sheet 4.

[0036] The method 1 comprises an operation O7 of reading the primary identification element. This reading operation O7 is carried out by means of a reading device 11 specific to the calendering device 10.

[0037] The method 1 comprises an operation O8 of associating at least one parameter inherent to the calendering operation O6 with the primary identification element 5 identified during the reading operation O7 specific to the calendering operation O6.

[0038] In other words, a reading of the primary identification element 5 is carried out, the parameters of the calendering operation O6 such as for example the pressure, temperature and all the other parameters of interest are associated with the primary identification element 5. This association is carried out by storing in the computer unit 9 the said parameters associated with the corresponding primary identification element 5.

[0039] Thus it becomes possible to precisely assign the parameters inherent to the calendering operation O6 to a given electrode 2.

[0040] Advantageously, the operation O7 of reading the primary identification element 5 is carried out before the calendering operation O6 in order to facilitate the association operation O8.

[0041] Advantageously, the method 1 comprises a drying operation O9. The electrode sheet 4 is passed through a drying machine 12.

[0042] Advantageously, the primary marking operation O2 is carried out before the drying operation O9. Indeed, and as previously mentioned, the primary marking operation O2 is carried out substantially immediately after the operation O1 of unwinding the electrode sheet 4.

[0043] The method 1 comprises an operation O10 of reading the primary identification element. This reading operation O10 is carried out by means of a reading device 13 specific to the drying machine 12.

[0044] The method 1 comprises an operation O11 of associating at least one parameter inherent to the drying operation O9 with the primary identification element 5 identified during the reading operation O10 specific to the drying operation O9.

[0045] In other words, a reading of the primary identification element 5 is carried out, the parameters of the drying operation O9 such as for example the pressure, temperature and all the other parameters deemed to be of interest are associated with the primary identification element 5. This association is carried out by storing in the computer unit 9 the said parameters associated with the corresponding primary identification element 5.

[0046] Thus it becomes possible to precisely assign the parameters inherent to the drying operation O9 to a given electrode 2.

[0047] Advantageously, the operation O10 of reading the primary identification element 5 is carried out before the drying operation O9 in order to facilitate the association operation O11.

[0048] Advantageously, the method 1 comprises a cutting operation O12. The electrode sheet 4 is passed through a cutting device 14. The electrode sheet 4 is cut to obtain electrodes 2 that are distinct from each other.

[0049] Advantageously, the primary marking operation O2 is carried out before the cutting operation O12. Indeed, and as previously mentioned, the primary marking operation O2 is carried out substantially immediately after the operation O1 of unwinding the electrode sheet 4.

[0050] The method 1 comprises an operation O13 of reading the primary identification element 5. This reading operation O13 is carried out by means of a reading device 15 specific to the cutting device 14.

[0051] The method 1 comprises an operation O14 of associating at least one parameter inherent to the cutting operation O12 with the primary identification element 5 identified during the reading operation O13 specific to the cutting operation O12.

[0052] In other words, a reading of the primary identification element 5 is carried out, the parameters of the cutting operation O12 deemed to be of interest are associated with the primary identification element 5. This association is carried out by storing in the computer unit 9 said parameters associated with the corresponding primary identification element 5.

[0053] Thus it becomes possible to precisely assign the parameters inherent to the cutting operation O12 to a given electrode 2.

[0054] Advantageously, operation O13 of reading the primary identification element is carried out before operation O12 of cutting in order to facilitate the association operation.

[0055] As previously mentioned, the method 1 comprises a step E2 of stacking the electrodes 2 on top of each other, which are separated from each other by a porous separator film 3. This stacking step E2 is subsequent to the step E1 of producing the electrodes 2.

[0056] This results in a stack of 32 electrodes.

[0057] Advantageously, the stacking step E2 comprises stacking operations O15 to obtain the stack 32 of electrodes and a secondary marking operation O16 of the stack 32 of electrodes. A secondary identification element 16 is affixed to the stack 32 of electrodes. The secondary identification element 16 is for example of the QR code type.

[0058] By thus marking the stack 32 of electrodes with a secondary identification element 16, it becomes possible to ensure complete traceability of the stack 32 of electrodes. In particular, it becomes possible to record all the parameters inherent in the manufacture of the electrodes 2 and to associate them with the secondary identification element 16.

[0059] The stacking step E2 is carried out in a stacking unit 17. The stacking unit 17 is capable of moving the electrodes 2 to form the stack 32 of electrodes. The stacking unit 17 comprises at least one reading device 18 capable of reading the primary and secondary identification elements 5, 16. In practice, two reading devices 18 may be necessary, one dedicated to reading the primary identification element 5 and the other dedicated to reading the secondary identification element 16.

[0060] Advantageously, in the stacking step E2, the method 1 comprises an operation O17 of reading the primary identification element 5 of each electrode 2.

[0061] The method 1 comprises a plurality of operations O15 of stacking electrodes 2 on top of each other while separating them by a porous separator film 3.

[0062] Method 1 includes a secondary marking operation O16.

[0063] Method 1 comprises an operation O19 of reading the secondary identification element.

[0064] The method 1 comprises an operation O18 of associating the information of each of the electrodes 2 of the stack 32 of electrodes with the secondary identification element 16. This is made possible by the operation O17 of reading the primary identification element 5 which makes it possible to know all the information relating to each electrode 2.

[0065] The data relating to the electrode stack 32 is stored in the computer unit 9.

[0066] Thus it becomes possible, by reading the secondary identification element 16, to know the information relating to each electrode 2 of a given stack 32 of electrodes. In addition it becomes possible to know precisely the position of each electrode 2 in the stack 32 of electrodes as well as its parameters. Complete traceability is thus achieved.

[0067] Advantageously, the method 1 comprises a step E3 of sectioning the primary identification elements 5. The sectioning step E3 is carried out once the stack 32 of electrodes has been obtained and the operations O18 of association with the secondary identification element 16 of the stack 32 of electrodes have been carried out. A given stack 32 of electrodes then only comprises one secondary identification element 16. Indeed, only the secondary identification element 16 is of interest. All the information relating to each electrode 2 of the stack 32 of electrodes can be obtained by reading the secondary identification element 16.

[0068] Advantageously, in the primary marking operation O2, two primary identification elements 5 are affixed so as to be separated from each other by a separation distance D1 measured substantially along a direction 19 of movement of the electrode sheet 4. The separation distance D1 is advantageously between 35 millimeters and 110 millimeters. The distance D1 is chosen so as to be less than a width of the electrodes measured along the direction 19 of movement. In this way, it is ensured that the electrode 2 obtained following the operation O12 of cutting the electrode sheet 4 comprises at least one primary identification element 5. The important thing is to ensure that there is at least one primary identification element 5 on each electrode 2.There may be more than one primary identification element 5 on a given electrode 2 without this posing a technical problem, the computer unit 9 being able to manage the presence of possible duplicates.

[0069] Advantageously, the separation distance D1 is substantially equal to 38 millimeters. In this way, it is ensured that the electrode 2 obtained following the operation O12 of cutting the electrode sheet 4 comprises at least one primary identification element 5. This is particularly true, in particular with regard to electrodes 2 having a width measured in the direction 19 greater than 38 millimeters.

[0070] After the coating operation O3, the electrode sheet 4 comprises a metallic portion 20 and an active portion 21. The metallic portion 20 is devoid of active material and the active portion 21 is coated with active material.

[0071] Advantageously, the primary identification elements 5 are affixed to the metal portion 20 of the electrode sheet 4.

[0072] Advantageously, the primary identification elements 5 are arranged at a lateral distance D2 from the active portion 21. The lateral distance D2 is measured in a transverse direction 22 substantially perpendicular to the direction 19 of movement of the electrode sheet 4 and in a plane 23 of the electrode sheet (4). The lateral distance D2 is advantageously at least equal to 5 millimeters.

[0073] Such a lateral distance D2 allows good reading of the primary identification element 5. Indeed, such a lateral distance D2 makes it possible to avoid the slightest reading defect by the reading devices 8, 11, 13, 15, 18.

[0074] Advantageously, the lateral distance D2 is at least equal to 5 millimeters. Such a lateral distance D2 allows good reading of the primary identification element 5. Indeed, such a lateral distance D2 makes it possible to avoid reading defects by the reading devices 8, 11, 13, 15, 18. The lateral distance D2 is at least equal to 11 millimeters, which makes it possible to avoid any reading defects.

[0075] Advantageously, the primary identification elements 5 are located at an end distance D3. The end distance D3 is greater than 1 millimeter. The distance D3 is measured from a lateral end 40 of the electrode sheet 4 and in the transverse direction 22 towards the active portion 21. Thus it becomes possible to avoid any error in reading the primary identification element 5.

[0076] Advantageously, the method 1 makes it possible to obtain an electric cell having a secondary identification element 16. The information relating to each of the electrodes 2 contained in the cell can be obtained by reading the secondary identification element 16 and recovered from the computer unit 9.

[0077] Advantageously, the method 1 is implemented by a unit 24 for producing electric cells. The unit 24 for producing electric cells comprises a unit 25 for producing electrodes comprising a device 26 for unwinding the reel 6 of electrode sheet 4 and a device 27 for printing a primary identification element 5. The cell production unit 24 comprises a unit 17 for stacking electrodes 2 and the computer unit 9.

[0078] The electrode production unit 24 comprises: - the coating device 7 comprising a device 8 for reading a primary identification element 5, - the calendering device 10 comprising a device 11 for reading a primary identification element 5, - the drying device 12 comprising a device 13 for reading a primary identification element 5, - the cutting device 14 comprising a device 15 for reading a primary identification element.

[0079] Advantageously, the cell production unit 24 comprises a device 29 for printing a secondary identification element 16 and at least one reading device 30 capable of reading a primary identification element 5 and a secondary identification element 16. In particular, it is the electrode stacking unit 17 which comprises the device 29 for printing a secondary identification element and the at least one reading device 30 capable of reading a primary identification element 5 and a secondary identification element 16.

[0080] Advantageously, the cell production unit 24 comprises a sectioning device 31. The sectioning device 31 is capable and intended to section the primary identification element 5.

Claims

Method (1) for producing an electric cell comprising a plurality of electrodes (2) stacked on top of each other and separated from each other by a porous separator film (3), the method comprising:- a step (E1) of producing the electrodes (2),- a step (E2) of stacking the electrodes (2) on top of each other to form a stack (32) of electrodes, said electrodes (2) being separated by a porous separator film (3),method in which the step (E1) of producing the electrodes (2) comprises:- an operation (O1) of unwinding a reel (6) of an electrode sheet (4), and- an operation (O2) of primary marking of the electrode sheet (4) by means of a primary identification element (5), said marking operation (O2) being carried out after the operation (O1) of unwinding the electrode sheet (4), said marking operation (O2) being repeated continuously as long as the coil of electrode sheet is unwound,- an operation (O12) of cutting the electrode sheet (4) so ​​as to form electrodes (2) distinct from each other, method in which the primary marking operation (O2) is carried out before said cutting operation (O12); method in which the step (E2) of stacking the electrodes (2) comprises: - an operation (O16) of secondary marking of the stack of electrodes by means of a secondary identification element (16); - an operation (O17) of reading the primary identification element (5) of each (2) electrode, - a plurality of operations (O15) of stacking the electrodes (2) on top of each other separated by a porous separator film (3), - an operation (O19) of reading the secondary identification element, - an operation (O18) of associating the information of each of the electrodes of the stack of electrodes and their position respective in the stack (32) of electrodes, this association being carried out with the secondary identification element (16),this information being known thanks to the operations (O17) of reading the primary identification elements (5) of each electrode (2)., Method (1) according to claim 1 wherein it comprises an operation (O3) of coating an active material on the electrode sheet (4), method (1) in which the primary marking operation (O2) is carried out before said coating operation (O3), method (O1) in which it comprises:- an operation (O4) of reading the primary identification element (5), and- an operation (O5) of associating at least one parameter inherent to the coating operation with the primary identification element (5) identified during the operation (O4) of reading said primary identification element (5). Method (1) according to any one of the preceding claims, in which it comprises an operation (O6) of calendering the electrode sheet (4), method (1) in which the primary marking operation (O2) is carried out before said calendering operation (O6), method (1) in which it comprises: - an operation (O7) of reading the primary identification element (5), and - an operation (O8) of associating at least one parameter inherent to the calendering operation (O8) with the primary identification element (5) identified during the operation (O7) of reading said primary identification element (5). Method (1) according to any one of the preceding claims, in which it comprises an operation (O9) of drying the sheet (4) the electrode, method in which the primary marking operation (O2) is carried out before said drying operation (O9), method (1) in which it comprises:- an operation (O10) of reading the primary identification element (5), and- an operation (O11) of associating at least one parameter inherent to the drying operation (O9) with the primary identification element (5) identified during the operation (O10) of reading said primary identification element (5). Method (1) according to any one of the preceding claims, in which it comprises - an operation (O13) of reading the primary identification element (5), and - an operation (O14) of associating at least one parameter inherent to the cutting operation (O12) with the primary identification element (5) identified during the operation (O13) of reading said primary identification element (5). Method (1) according to any one of the preceding claims, in which it comprises a step (E3) of cutting the primary identification elements (5), so that the electrode stack (32) only comprises one secondary identification element (16). Method (1) according to any one of the preceding claims, in which the operation (O2) of marking the primary identification element is carried out so that two primary identification elements (5) are separated by a separation distance (D1) of between 35 millimeters and 110 millimeters, which separation distance (D1) is measured along a direction (19) of movement of the electrode sheet (4). Method according to any one of the preceding claims, in which the operation (O2) of marking the primary identification element is carried out so that two primary identification elements (5) are separated by a separation distance (D1) less than a width of the electrodes (2) measured in a direction (19) of movement of the electrode sheet (4). Method (1) according to claim 7 or claim 8 in which the separation distance (D1) is substantially equal to 38 millimeters. Method (1) according to any one of claims 7 to 9 wherein the operation (O2) of marking the primary identification element (5) is carried out so that the primary identification elements (5) are located at an end distance (D3) greater than or equal to 1 millimeter, said end distance (D3) being measured from a lateral end (40) of the electrode sheet (4) in a transverse direction (22) substantially perpendicular to the direction (19) of movement and in a plane (23) of the electrode sheet (4). Method (1) according to any one of the preceding claims, in which the operation (O2) of primary marking of the primary identification element (5) is carried out so that said primary identification elements (5) are located on a metallic portion (20) of the electrode sheet (4) not coated with an active material and said primary identification elements (5) are located at a lateral distance (D2) from an active portion (21) of the electrode sheet (4) coated with an active material, and the lateral distance (D2) being measured in a transverse direction (22) substantially perpendicular to the direction (19) of movement of the electrode sheet (4) and in a plane (23) of the electrode sheet, method (1) in which the lateral distance (D2) is at least equal to 5 millimeters. Method (1) according to claim 11 in which the lateral distance (D2) is at least equal to 11 millimeters. Electrical cell comprising a secondary identification element (16), said cell being obtained by means of a method according to any one of claims 1 to 6 and according to any one of claims 7 to 12 further dependent on any one of claims 1 to 6. Unit (24) for producing electric cells, the unit (24) comprising:- a unit (25) for producing electrodes (2) comprising a device (26) for unwinding a reel (6) of electrode sheet (4) and a device (27) for printing a primary identification element (5),- a unit (17) for stacking electrodes (2),- a computer unit (9),the cell production unit (24) being capable of implementing a method (1) according to claim 1 and a method (1) according to any one of claims 7 to 12 further dependent on claim 1. Unit (24) according to claim 14 in which the unit (25) for producing electrodes (2) comprises:- a coating device (7) comprising a device (8) for reading a primary identification element (5), the unit (24) being capable of implementing a method (1) according to claim 2. Unit (24) according to any one of claims 14 or 15 in which the electrode production unit (25) comprises:- a calendering device (10) comprising a device (11) for reading a primary identification element (5), the unit (24) being capable of implementing a method (1) according to claim 3. Unit (24) according to any one of claims 14 to 16 in which the electrode production unit (25) comprises:- a drying device (12) comprising a device (13) for reading a primary identification element (5), the unit (24) being capable of implementing a method (1) according to claim 4. Unit (24) according to any one of claims 14 to 17 in which the electrode production unit (25) comprises:- a cutting device (14) comprising a device (15) for reading a primary identification element, the unit (24) being capable of implementing a method (1) according to claim 5. Unit (24) according to any one of claims 14 to 18, in which the latter comprises a device (29) for printing a secondary identification element (16) and at least one device (30) for reading a secondary identification element, said unit (24) being capable of implementing a method (1) according to claim 1. Unit (24) according to any one of claims 14 to 19 wherein it comprises a sectioning device (31), the unit (24) being capable of implementing a method (1) according to claim 6.

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