Cell for electric battery and its manufacturing process
By cutting the inactive portions of electrodes to form flexible tabs and using support portions on the current collectors to secure them, the challenges of attaching current collection tabs in cylindrical battery cell production are addressed, resulting in improved efficiency and reduced scrap rates.
Patent Information
- Application Number
- FR2022012793
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2022-12-05
- Publication Date
- 2025-05-23
- Estimated Expiration
- 2042-12-05
AI Technical Summary
The production of cylindrical electric battery cells is hindered by the tedious and time-consuming process of attaching current collection tabs, which can lead to defects, reduced performance, and increased scrap rates.
The solution involves creating flexible current collection tabs by cutting the inactive portions of the electrodes after winding, and using support portions on the current collectors to fold and secure these tabs, reducing the number of cuts and simplifying the folding process.
This method allows for the production of cylindrical battery cells at an industrial rate with lower scrap rates and maintained conductivity, as the number of cuts is reduced and the tabs are easier to fold and secure.
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Abstract
Description
Title of the invention: Cell for electric battery and its manufacturing method Technical field of the invention
[0001] The invention relates to the field of electric batteries for electric motor vehicles. In particular, the invention relates to electric battery cells. More specifically, the invention relates to cylindrical type cells. Technical background
[0002] Cylindrical type electric battery cells are increasingly used in the automotive industry.
[0003] The advantage of cylindrical cells lies in their ability to store a significant amount of energy in a small volume. They therefore occupy less space in the motor vehicle for a given energy storage capacity.
[0004] The energy storage capacity of a cylindrical cell is a function of its diameter. Thus, the larger the diameter of a cylindrical cell, the greater its capacity to store energy.
[0005] The cylindrical cells are manufactured by winding around a mandrel, a successive stack of at least: - a positive electrode sheet, - an insulating separator sheet, - a negative electrode sheet, - an insulating separator sheet.
[0006] Along the electrode sheets, current collection tabs are attached and fixed to said positive and negative electrode sheets. Although automated, this operation is particularly tedious and slows down the production rate of so-called cylindrical cells. In addition, a defect in the attachment and / or contact between the tabs and the electrodes can reduce the performance of the cylindrical cells, or even cause short circuits.
[0007] In order to overcome these problems, manufacturers have proposed doing away with tabs added and then fixed to the electrodes.
[0008] One of these solutions consists of making cuts directly on the electrode sheets to form current collection tabs before winding around a rotating mandrel. Once winding is complete, these tabs are folded and brought into contact with an attached current collector.
[0009] A disadvantage of this method is that it requires many cuts to the during a cutting operation carried out before winding around the mandrel. A slowdown in the production rate of the cells is then observed due to the high number of cuts to be made.
[0010] Another disadvantage of this method is that the current collecting tabs can be damaged during winding around the mandrel, said tabs being thin, they can easily be damaged during handling operations.
[0011] Another disadvantage of this method lies in the difficulty of folding the tabs due, among other things, to their large number. In addition, fixing the tabs in the folded position is tedious and encounters technical difficulties when it comes to achieving industrial rates.
[0012] The invention therefore aims to solve the aforementioned problems. Summary of the invention
[0013] To this end, there is proposed firstly an electric battery cell for an electrically powered vehicle, said cell comprising at least one successive stack of a sheet: - a first electrode comprising a first active portion coated with an active material and a first inactive portion, - a first insulating separator, - a second electrode comprising a second active portion coated with an active material and a second inactive portion, - a second insulating separator, at least one stack being wound on itself around a central axis so as to form a cylinder, said cell comprising a first end from which the first inactive portion protrudes, a cell in which the first inactive portion has at least two cuts so as to form between said cuts flexible current collecting tabs, said cell comprising a first current collector provided with at least one first support portion intended to come into contact with the current collecting tabs and to keep said flexible current collecting tabs in the folded position.
[0014] The production of such cells can be carried out at an industrial rate, because the number of cuts is lower and this without loss of efficiency of the cell because the conductivity is maintained at acceptable levels. Folding is made easier due to the lower number of current collection tabs compared to current cells. The scrap rate is thus significantly lower.
[0015] Various additional features may be provided alone or in combination: - this comprises a second end opposite the first end along the central axis, second end from which the second inactive portion projects, cell in which the second inactive portion comprises at least two cutouts so as to form between said cutouts current collection tabs, said cell comprising a second current collector provided with at least one second support portion intended to come into contact with the foldable current collection tabs and hold them in the folded position; - the current collecting tabs are folded over each other, from one periphery of the cell towards the central axis; - the at least one first support portion of the first current collector is secured to the current collection tabs of the first electrode and the at least one second support portion of the second current collector is secured to the current collection tabs of the second electrode; - this comprises, at each end, several portions of foldable current collection tabs distinct from one another, and the first and second current collectors comprise several support portions distinct from one another, each support portion being intended to come into contact with a portion of current collection tabs to hold the current collection tabs in the folded position; - the current collectors are metal discs comprising an inner face arranged opposite the electrode and an outer face opposite the inner face, cell in which at least one support portion projects from the inner face along the central axis; - each support portion extends over a length between a proximal end located on the side of the central axis and a distal end opposite the proximal end and located on the side of the periphery of said cell, the length being measured along a radial axis passing through each support portion, said radial axis being secant and substantially perpendicular to the central axis, cell in which the cutouts extend over a length substantially equal to the length; - each support portion has a height, measured from the inner face to the contact face and along the central axis, said height decreasing as one moves along the length from the periphery of the metal disc towards the central axis; - the inner face is arranged at a distance from the electrodes.
[0016] Secondly, an electric battery is proposed comprising a plurality of cells as previously described and connectors intended to connect said cells together.
[0017] Thirdly, there is provided a method of manufacturing a cell such as pre- previously described, the method comprising: - an operation of providing a sheet of a first electrode comprising a first active portion and a first inactive portion, - an operation of supplying a sheet of a first insulating separator, - an operation of providing a sheet of a second electrode comprising a second active portion and a second inactive portion, - an operation of supplying a sheet of a second insulating separator, - an operation of successively stacking the first electrode, the first insulating separator, the second electrode, the second insulating separator so as to form a stack in which the first electrode and the second electrode are laterally offset relative to each other so that the first inactive portion and the second inactive portion protrude at least partly outside the stack - an operation of rolling the stack onto itself to substantially form a cylinder, said cylinder comprising a first end from which the first inactive portion projects beyond the stack and a second end from which the second inactive portion projects beyond the stack, - a cutting operation, subsequent to the winding operation, of the first inactive portion and the second inactive portion, so as to form current collection tabs, - an operation of removing the first current collector and the second current collector respectively on the first end and on the second end so that the at least one support portion comes into contact with the at least one portion of current collection tabs so as to bend the current collection tabs.
[0018] The method comprises an operation of welding the support portions of the current collectors to the current collecting tabs. Brief description of the figures
[0019] 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:
[0020] [Fig-1] [Fig. 1] is a schematic cross-sectional representation of a part of a cylindrical cell according to the invention;
[0021] [Fig.2] [Fig.2] is a schematic representation in top view of a current collector according to the invention;
[0022] [Fig.3] [Fig.3] is a schematic cross-sectional representation of the current collector of [Fig.2];
[0023] [Fig.4] [Fig.4] is a schematic representation in top view of a current collector according to the invention;
[0024] [Fig.5] [Fig.5] is a schematic cross-sectional representation of the current collector of [Fig.4];
[0025] [Fig.6] [Fig.6] is a schematic representation of one end of a cell according to the invention;
[0026] [Fig.7] [Fig.7] is a schematic representation of another end of the cell according to the invention. Detailed description of the invention
[0027] In [Fig.l] an electric battery cell 1 is shown. The cell 1 is intended to power an electrically powered vehicle. The cell 1 comprises at least one successive stack of a sheet: - of a first electrode 2, - a first insulating separator 3, - a second electrode 4, - a second insulating separator 5.
[0028] The stack is wound on itself around a central axis 8 so as to substantially form a cylinder.
[0029] The first electrode 2 comprises a first active portion 9, which is coated with an active material, and a first inactive portion 10, which is not coated with active material. Thus the first inactive portion 10 is a metal, for example aluminum or copper.
[0030] The second electrode 4 comprises a second active portion 11, which is coated with an active material, and a second inactive portion 12, which is not coated with active material. Thus the second inactive portion 12 is a metal, for example aluminum or copper.
[0031] The cell 1 comprises a first end 13. From this first end 13, the first inactive portion 10 projects. By "projection" is meant the fact that the first inactive portion 10 extends at least in part, along the central axis 8, beyond the separators 3, 5.
[0032] As can be seen in Figures 6 and 7, the first inactive portion 10 comprises at least two cutouts 14. In the embodiment shown in the drawings, the first inactive portion 10 comprises eight cutouts 14 forming four first tab portions 15. The cutouts 14 make it possible to form foldable current collecting tabs 16.
[0033] The cell 1 comprises a first current collector 17. The first current collector 17 comprises at least a first support portion 18. The first portion 18 support is intended to come into contact with the foldable current collection tabs 16 and hold them in the folded position.
[0034] The production of such cells 1 can be carried out at an industrial rate, because the number of cuts 14 is smaller and this without loss of efficiency of the cell 1 because the conductivity is maintained at acceptable levels. Folding is made easier due to the smaller number of current collection tabs 14 compared to current cells. The scrap rate is thus significantly lower.
[0035] Advantageously, the cell 1 comprises a second end 19, opposite the first end 13 along the central axis 8. The second inactive portion 12 projects from this second end 19. By "projection" is meant the fact that the second inactive portion 12 extends, along the central axis 8, beyond the separators 3, 5.
[0036] Advantageously, the second inactive portion 12 comprises at least two cutouts 14 forming between said cutouts 14 current collection tabs 16. In the embodiment shown in the drawings, the second inactive portion 12 comprises eight cutouts 14 forming four second tab portions 32.
[0037] Advantageously, the cell 1 comprises a second current collector 20 provided with at least one second support portion 21. The second support portion 21 is intended to come into contact with the foldable current tabs 16 and hold them in the folded position.
[0038] It is advantageous for the second end 19 to be identical to the first end 13 for reasons of production homogenization. This simplifies the manufacturing process of the cells 1.
[0039] Advantageously, the current collection tabs 16 are folded over each other as can be seen in [Fig. 1]. They are folded from a periphery 22 of the cell 1 in the direction of the central axis 8.
[0040] It is advantageous to bend the current collection tabs 16 in this direction because this avoids the risk of short circuits.
[0041] Advantageously, the first support portions 18 of the first current collector 17 are secured to the current collection tabs 16 of the first electrode 2. Advantageously, the second support portions 21 of the second current collector 20 are secured to the current collection tabs 16 of the second electrode 4. The securing is carried out for example by welding.
[0042] By only securing the support portions 18, 21 to the current collection tabs 16, the number of welds is reduced while maintaining acceptable electrical conductivity. This makes it possible to improve production rates.
[0043] Advantageously, the first current collector 17 comprises four first support portions 18 distinct from each other. Each first support portion 18 is intended to come into contact with a first portion 15 of current collection tabs and hold the current collection tabs 16 in the folded position.
[0044] Advantageously, the second current collector 20 comprises four second support portions 21 distinct from each other. Each second support portion 21 is intended to come into contact with a second portion 32 of current tabs and hold the current collection tabs 16 in the folded position.
[0045] Advantageously, the first and second current collectors 17, 20 are in the form of a metal disc. The metal disc comprises an inner face 23 arranged opposite the electrode 2, 4 and an outer face 24 opposite the inner face 23. The support portions 18, 21 project from the inner face 23, along the central axis 8.
[0046] Such support portions 18, 21 ensure contact with the current collection tabs 16.
[0047] Advantageously, each support portion 18, 21 extends over a length L. The length L is measured along a radial axis 25 passing through the support portion 18, 21. The radial axis 25 is substantially perpendicular to the central axis 8. The radial axis 25 intersects the central axis 8. The length L is measured between a proximal end 26 located on the side of the central axis 8 and a distal end 27 opposite the proximal end 26 along the radial axis 25 substantially perpendicular to the central axis 8. The distal end 27 is located on the side of the periphery 22 of the cell 1. The cutouts 14 extend over a length substantially equal to the length L.
[0048] It should be noted that there are as many radial axes 25 as there are support portions 18, 21. In this case, each support portion 18, 21 is associated with its radial axis 25 passing through said support portion 18, 21, substantially perpendicular to the central axis 8 and intersecting said central axis 8.
[0049] The length of the support portions 18, 21 and that of the cutouts 14 being substantially equal, the contact is optimal and the conductivity is maintained at an acceptable level.
[0050] Advantageously, two neighboring cutouts are separated from each other by a distance DI less than or equal to 80% of an internal diameter D2. The internal diameter D2 corresponds to the external diameter of the winding mandrel.
[0051] Such a distance DI makes it possible to easily fold the current collection tabs 16.
[0052] Advantageously, the support portions 18, 21 of the current collectors comprise a contact face 28 intended to come into contact with the current collection tabs 16.
[0053] This allows optimal conductivity to be maintained.
[0054] Advantageously, the support portion 18, 21 has a height H measured according to a direction parallel to the central axis 8. The height H is measured from the inner face 23 to the contact face 28 of the support portions. The height H decreases as one moves along the length L and this from the periphery 22 of the cell 1 in the direction of the central axis 8.
[0055] This makes it possible to ensure folding of the current collection tabs 16 in the direction of the central axis 8 and thus facilitate folding in the correct direction by simply positioning the current collectors 17, 20.
[0056] Advantageously, the inner face 23 of the first current collector 17 and of the second current collector 20 are respectively arranged at a distance from the first electrode 2 and from the second electrode 4. There is thus no contact between the inner face 23 and the inactive portions of the electrodes.
[0057] Advantageously, the first portions 15 of tabs are arranged at 90° to each other. Thus the first portions 15 of tabs form an angle α of 90° between them.
[0058] Advantageously, the second portions 32 of tabs are arranged at 90° to each other. Thus the second portions 32 of tabs form an angle α of 90° between them.
[0059] This allows for better conductivity by reducing the distance traveled by electrons in the electrode sheets. The performance of the cell is thus improved.
[0060] As can be seen in [Fig.l], the cell is assembled by inserting the assembly comprising the wound stack and the current collectors into a rigid cylindrical capsule 29. The second current collector 20, which is the negative pole, is in contact with the cylindrical capsule 29, thus the cylindrical capsule 29 is negatively polarized. Conversely, the first current collector 17 is positively polarized and is not in direct contact with the cylindrical capsule 29. The cell 1 comprises a cap 30 attached and fixed to the first current collector 17 and thus positively polarized. As can be seen in [Fig.l], insulating elements 31 are arranged between the first current collector 17 and the cylindrical capsule 29. Other insulating elements 31 are arranged between the cap 30 and the cylindrical capsule 29. These insulating elements 31 make it possible to avoid short circuits.
[0061] The invention also relates to an electric battery (not shown in the drawings) comprising several cells 1. The battery comprises connectors intended to interconnect the cells together.
[0062] In the following a method of manufacturing the cell will be described.
[0063] The method comprises a supply operation: - a sheet of a first electrode comprising a first active portion and a first inactive portion, - a sheet of a first insulating separator, - a sheet of a second electrode comprising a second active portion and a second inactive portion, - a sheet of a second separator.
[0064] The method comprises an operation of successively stacking the first electrode, the first insulating separator, the second electrode and the second insulating separator. The stacking is carried out in such a way: - that at the first end, the first inactive portion projects beyond the stack, and - that at the second end, the second inactive portion projects beyond the stack.
[0065] The method comprises an operation of rolling up the stack on itself to substantially form a cylinder. Thus, at the first end of the cylinder, the first inactive portion projects from the stack while at the second end of the cylinder, the second inactive portion projects from the stack.
[0066] The method comprises a cutting operation, subsequent to the winding operation. The cutting makes it possible to form current collection tabs. In the embodiment shown in the drawings, eight cuts are made to form four portions of current collection tabs on each end of the cell.
[0067] The method comprises an operation of removing the first current collector and the second current collector respectively on the first end and on the second end. This removal is carried out so that each support portion comes into contact with a portion of current collection tabs. The contact causes the current collection tabs to tilt towards the central axis.
[0068] The production of such cells can be carried out at an industrial rate, because the number of cuts is more reasonable without loss of efficiency of the cell. In addition, the current collection tabs are not damaged because the cuts are made after winding and not before winding. Folding is also made easier due to the smaller number of current tabs compared to current cells. The scrap rate is thus significantly lower.
[0069] Advantageously, the method comprises an operation of welding the support portions to the current collection tabs, this making it possible to secure the current collectors to said current collection tabs.
Claims
Claims
1. Electric battery cell (1) for an electrically powered vehicle, said cell (1) comprising at least one successive stack of a sheet: - a first electrode (2) comprising a first active portion (9) coated with an active material and a first inactive portion (10), - a first insulating separator (3), - a second electrode (4) comprising a second active portion (11) coated with an active material and a second inactive portion (12), - a second insulating separator (5), said at least one stack being wound on itself around a central axis (8) so as to form a cylinder, said cell (1) comprising a first end (13) from which the first inactive portion (10) protrudes, cell (1) in which the first inactive portion (10) comprises at least two cutouts (14) so as to form between said cutouts (14) foldable current collection tabs (16), said cell comprising a first current collector (17) provided with at least a first support portion (18) intended to come into contact with the current collection tabs (16) and maintain said foldable current collection tabs (16) in the folded position, the cell (1) comprising a second end (19) opposite the first end (13) along the central axis (8), second end (19) from which the second inactive portion (12) protrudes,cell (1) in which the second inactive portion (12) comprises at least two cutouts (14) so as to form between said cutouts (14) current collection tabs (16), said cell (1) comprising a second current collector (20) provided with at least one second support portion (21) intended to come into contact with the foldable current collection tabs (16) and hold them in the folded position, the at least one first support portion (18) of the first current collector (17) is secured to the current collection tabs (16) of the first electrode (2) and the at least one second support portion (21) of the second current collector (20) is secured to the current collection tabs (16) of the second electrode (4), cell (1) in which the current collectors (17, 20) are metal discs, comprising an inner face (23) arranged opposite the electrode (2, 3) and an outer face (24) opposite the inner face (23), cell (1) in which the at least one support portion (18, 21) projects from the inner face (23) along the central axis (8), cell in which each support portion (18, 21) extends over a length (L) between a proximal end (26) located on the side of the central axis (8) and a distal end (27) opposite the proximal end (26) and located on the side of the periphery (22) of said cell (1), the length (L) being measured along a radial axis (25) passing through each support portion (18, 21), said radial axis (25) being secant and substantially perpendicular to the central axis (8), cell (1) in which the cutouts (14) extend over a length substantially equal to the length (L) and each support portion (18, 21) has a height (H),measured from the inner face (23) to a contact face (28) and along the central axis (8), said height (H) decreasing as one moves along the length (L) from the periphery (22) of the metal disc towards the central axis (8).,
2. Cell (1) according to claim 1 wherein the current collecting tabs (16) are folded over each other, from a periphery (22) of the cell (1) towards the central axis (8).
3. Cell (1) according to any one of the preceding claims, in which it comprises, at each end (13, 19), several portions (15, 32) of foldable current collection tabs distinct from each other, and the first and second current collectors (17, 20) comprise several support portions (18, 21) distinct from each other, each support portion (18, 21) being intended to come into contact with a portion (15, 32) of current collection tabs to maintain the current collection tabs (16) in the folded position.
4. Cell (1) according to any one of the preceding claims in which the inner face (23) is arranged at a distance from the electrodes (2,
5. An electric battery comprising a plurality of cells (1) according to any one of the preceding claims and connectors intended to connect the cells together.
6. A method of manufacturing a cell according to any one of claims 1 to 4, comprising: - an operation of providing a sheet of a first electrode
7. comprising a first active portion and a first inactive portion, - an operation of providing a sheet of a first insulating separator, - an operation of providing a sheet of a second electrode comprising a second active portion and a second inactive portion, - an operation of supplying a sheet of a second insulating separator, - an operation of successively stacking the first electrode, the first insulating separator, the second electrode, the second insulating separator so as to form a stack in which the first electrode and the second electrode are laterally offset relative to each other so that the first inactive portion and the second inactive portion protrude at least partly outside the stack, - an operation of rolling the stack onto itself to substantially form a cylinder, said cylinder comprising a first end from which the first inactive portion projects beyond the stack and a second end from which the second inactive portion projects beyond the stack, - a cutting operation, subsequent to the winding operation, of the first inactive portion and the second inactive portion, so as to form current collection tabs, - an operation of removing the first current collector and the second current collector respectively on the first end and on the second end so that the at least one support portion comes into contact with the at least one portion of current collection tabs so as to bend the current collection tabs. A method according to claim 6 wherein it comprises an operation of welding the bearing portions of the current collectors to the current collecting tabs.