Tabless cylindrical electric battery cell

Abstract

The invention relates to a method for manufacturing a cylindrical electric battery cell (10) for an electric propulsion vehicle, the cell (10) comprising: - a winding (1) of electrodes and separators including, in series, a first electrode sheet (3), a first separator, a second electrode sheet of opposite polarity to the first electrode sheet and a second separator; - at least one current-collecting tab (4) connected to the first electrode sheet, projecting at a first end of the winding; and - a cylindrical metal housing (2) housing the winding, the method comprising a metal additive manufacturing step, at the first end, of a current collector in contact with the cylindrical metal housing and fusing at least a portion of the current-collecting tab so as to electrically connect the first electrode sheet to the cylindrical metal housing.

Description

Cylindrical type electric battery cell without tabs

[0001] The present invention relates to the technical field of cylindrical cells for electric vehicle batteries. More particularly, the present invention relates to the manufacture of a cylindrical cell, including in particular the electrical connection of an electrode foil of this cell to a cylindrical housing containing it.

[0002] A cylindrical type electric battery cell includes a cylindrical casing housing a winding of electrodes and separators comprising successively a positive electrode (or cathode) sheet, a first insulating separator sheet, a negative electrode (or anode) sheet and a second insulating separator sheet.

[0003] The first current-collecting tabs connected to the cathode and the second current-collecting tabs connected to the anode protrude, respectively, from a first end and a second opposite end of the electrode and separator winding.

[0004] A current collector in the form of a solid or perforated disc is mounted in a plane perpendicular to the central axis of the electrode and separator winding and is welded to the first or second current collection tabs to electrically connect the anode or cathode to the cylindrical housing. This results in an electrical and mechanical connection of an electrode of the cylindrical cell to the housing by means of an added current collector.

[0005] However, the fixing of such a current collector requires high industrial precision in the sense that it must be correctly dimensioned to fit the housing and one end of the winding, be accurately referred concentrically to said winding and be reliably and securely fixed, on the one hand, to the current collection tabs and, on the other hand, to the housing.

[0006] One object of the present invention is to remedy the aforementioned drawbacks.

[0007] Another object of the present invention is to improve the reliability of the electrical and mechanical connection between the housing and the winding of electrodes and separators.

[0008] Another object of the present invention is to improve the resistance of cylindrical type electric battery cells to shocks and vibrations.

[0009] Another object of the present invention is to propose a more compact and safer construction of cylindrical cells for electric batteries for electric vehicles.

[0010] To this end, a method for manufacturing a cylindrical electric battery cell for an electric propulsion vehicle is proposed, said cell comprising: - a winding of electrodes and separators successively comprising a first electrode sheet, a first separator, a second electrode sheet of opposite polarity to the first electrode sheet and a second separator; at least one current collection tab connected to the first electrode sheet protruding from a first end of said winding; - a cylindrical metal case housing said winding, said method comprising a metallic additive manufacturing step, at said first end, of a current collector in contact with the cylindrical metal case and fusing at least a part of said current collection tab so as to electrically connect the first electrode sheet to the cylindrical metal case.

[0011] Various additional features can be provided, alone or in combination: - the metal additive manufacturing step includes laser deposition of metal in powder form; - the current collector has a thickness between 0.05mm and 5mm; - the metal additive manufacturing step includes laser deposition of copper, the first electrode sheet being a negative electrode sheet to which the current collection tab containing copper is connected; - the metal additive manufacturing step includes laser deposition of aluminium, the first electrode sheet being a positive electrode sheet to which the current collection tab containing aluminium is connected;- the current collector electrically connecting the negative electrode sheet to the cylindrical metal case has a thickness less than the thickness of the current collector electrically connecting the positive electrode sheet to the cylindrical metal case; - the current collection tab is formed by cutting into the first electrode sheet.

[0012] Secondly, a cylindrical electric battery cell for an electric propulsion vehicle is proposed, comprising: a winding of electrodes and separators having successively a first electrode sheet, a first separator, a second electrode sheet of opposite polarity to the first electrode sheet and a second separator, at least one current collection tab connected to the first electrode sheet protruding from a first end of said winding; a cylindrical metal case housing said winding; the first electrode sheet being electrically connected to the cylindrical metal case according to the method presented above.

[0013] In one embodiment, the first electrode sheet and the current collection tab are manufactured as a single piece.

[0014] Other features and advantages of the invention will become clearer and more concrete upon reading the following description of embodiments, which is made with reference to the figure illustrating a cylindrical electric battery cell according to various embodiments.

[0015] Referring to the figure, a cylindrical electric battery cell for an electric vehicle is shown, comprising a winding of electrodes and separators and a cylindrical metal casing housing this winding. The cylindrical metal casing is in the form of a hollow cylindrical metal enclosure designed to contain (or house) the winding of electrodes and separators. Once the winding is in place, an electrolyte is injected into the cylindrical metal casing.

[0016] The electrode and separator winding 1 comprises successively a first electrode sheet 3 (for example, an anode), a first separator, a second electrode sheet of opposite polarity to the first electrode sheet 1, and a second separator. At least one current-collecting tab 4 connected to the first electrode sheet 3 (or to the second electrode sheet) protrudes from a first end of the winding 1.

[0017] In one embodiment, the current-collecting tab 4 is advantageously manufactured as a single unit with the first electrode sheet 3. In other words, the first electrode sheet 3 and the current-collecting tab 4 are manufactured as a single continuous piece, without any separate mechanical connection or interface between them. Put another way, the first electrode sheet 3 and the current-collecting tab 4 are in the form of a single piece. Such a design can be achieved by extending a portion of the material of the first electrode sheet 3 to form the current-collecting tab 4, or by cutting (for example, with a laser) the material of the first electrode sheet 3 to create a protruding portion serving as the current-collecting tab 4.

[0018] In a preferred embodiment, the current-collecting tab 4 is formed by cutting (in particular, by laser) in the first electrode sheet 3. Eliminating welds, mechanical junctions, or, more generally, interfaces between the current-collecting tab 4 and the first electrode sheet 3 advantageously reduces potential points of failure, thereby improving the reliability of the cylindrical cell 10. Furthermore, an integrated, i.e., non-attached, connection of the current-collecting tab 4 minimizes electrical resistances, which is beneficial for the electrical performance of the cylindrical cell 10. A first electrode sheet 3 and a current-collecting tab 4 manufactured as a single unit also simplifies and reduces the manufacturing cost of the cylindrical cell 10, as well as its overall weight.

[0019] In one embodiment, an electrical connection of the first electrode sheet 3 to the cylindrical metal housing 2 is achieved by a metal additive manufacturing step (or 3D printing) at the first end of the winding 1. This step involves a current collector in contact with the cylindrical metal housing 2 and fusing (or integrating by fusion) at least a portion of the current collection tab 4, thus electrically connecting the first electrode sheet 3 to the cylindrical metal housing 2. This metal additive manufacturing step fuses the current collection tab 4 to the cylindrical metal housing 2. Advantageously, this results in a compact bond that improves the electrical and mechanical connection of the current collection tab 4 to the cylindrical metal housing 2 using a current collector manufactured directly in situ at the first end of the winding 1 by 3D printing, rather than by an added part.

[0020] By merging the current collection tab4 into the current collector, the result is advantageously a cylindrical cell without a current collection tab, offering greater reliability and increased energy density.

[0021] In one embodiment, the metal additive manufacturing step includes laser metal deposition (LMD) of powdered metal. A metal laser deposition device is configured to fabricate a current collector at the first end of the winding using a powdered metal laser deposition method. Advantageously, this LMD additive manufacturing method allows for the rapid production of a current collector in the form of a substantially uniform coating layer, the thickness of which can be precisely controlled.

[0022] The thickness of the current collector obtained by additive manufacturing is, in one embodiment, between 0.05 mm and 5 mm. This thickness ensures a secure mechanical and electrical connection between the cylindrical metal housing and the first electrode sheet. It also maximizes the available space within the cylindrical metal housing for the electrode winding and separators. Reducing the current collector thickness allows for the integration of a larger electrode, thus increasing the overall capacity of the cylindrical cell. Additive manufacturing of a current collector with a thickness between 0.05 mm and 5 mm, or between 0.05 mm and 0.5 mm, allocates precisely the necessary space, without excess material or encroachment on the cylindrical cell, while optimizing the amount of material required for its manufacture, thereby reducing production costs.

[0023] In one embodiment, the first electrode sheet 3 is a negative electrode sheet (or anode), to which a current-collecting tab 4 containing copper is connected. In this case, the metal additive manufacturing step includes laser deposition of copper. Advantageously, this results in compatibility between the material of the current-collecting tab 4 and that of the 3D-printed current collector, leading to structural integrity of the connection between the first electrode sheet 3 and the cylindrical metal housing 2. Advantageously, this results in a reduction of the risk of cracking and, consequently, a more robust and reliable electrical and mechanical connection between the negative electrode sheet and the cylindrical metal housing 2.

[0024] In another embodiment, the first electrode sheet 3 is a positive electrode sheet (or cathode), to which a current-collecting tab 4 made of aluminum is connected. In this case, the metal additive manufacturing step includes laser deposition of aluminum. Advantageously, this results in compatibility between the material of the current-collecting tab 4 and that of the 3D-printed current collector, leading to structural integrity of the connection between the first electrode sheet 3 and the cylindrical metal housing 2. Advantageously, this results in a reduction of the risk of cracking and, consequently, a more robust and reliable electrical and mechanical connection between the positive electrode sheet and the cylindrical metal housing 2.This embodiment can, in particular, be considered in the case of a cylindrical lithium-iron-phosphate cell (better known as an LFP cell).

[0025] In one embodiment, the current collector electrically connecting the negative electrode foil to the cylindrical metal casing is thinner than the current collector electrically connecting the positive electrode foil to the cylindrical metal casing. This is because a current collector made of copper or containing copper conducts electricity better than one made of aluminum or containing aluminum, thus allowing its thickness to be reduced when connecting the anode to the cylindrical metal casing. Two metal additive manufacturing processes with two different thicknesses can therefore be used to connect the anode or cathode to the cylindrical metal casing, thereby reducing the amount of powdered metal required.

Claims

Method of manufacturing a cylindrical electric battery cell (10) for an electric propulsion vehicle, said cell (10) comprising a winding (1) of electrodes and separators successively comprising a first electrode sheet (3), a first separator, a second electrode sheet of opposite polarity to the first electrode sheet (3) and a second separator; at least one current collection tab (4) connected to the first electrode sheet (3) protruding from a first end of said winding (1);- a cylindrical metal case (2) housing said winding (1), said process being characterized in that it comprises a metallic additive manufacturing step, at said first end, of a current collector in contact with the cylindrical metal case (2) and fusing at least a part of said current collection tab (4) so ​​as to electrically connect the first electrode foil (3) to the cylindrical metal case (2). Manufacturing process according to the preceding claim, characterized in that the metallic additive manufacturing step comprises a laser deposition cladding of metal in powder form. Manufacturing method according to claim 1 or 2, characterized in that the current collector has a thickness between 0.05mm and 5mm. Manufacturing method according to any one of the preceding claims, characterized in that the metal additive manufacturing step includes a copper laser deposition cladding, the first electrode sheet (3) being a negative electrode sheet to which the current collection tab (4) comprising copper is connected. Manufacturing method according to any one of claims 1 to 3, characterized in that the metal additive manufacturing step comprises a laser deposition cladding of aluminium, the first electrode sheet (3) being a positive electrode sheet to which is connected the current collection tab (4) comprising aluminium. Manufacturing method according to claims 4 and 5, characterized in that the current collector electrically connecting the negative electrode sheet to the cylindrical metal housing (2) has a thickness less than the thickness of the current collector electrically connecting the positive electrode sheet to the cylindrical metal housing (2). A manufacturing method according to any one of the preceding claims, characterized in that the current collection tab (4) is formed by cutting into the first electrode sheet (3). Cylindrical electric battery cell (10) for an electric propulsion vehicle comprising - a winding of electrodes and separators successively comprising a first electrode sheet (3), a first separator, a second electrode sheet of opposite polarity to the first electrode sheet and a second separator, at least one current collection tab (4) connected to the first electrode sheet (3) projecting from a first end of said winding (1), - a cylindrical metal case (2) housing said winding (1); this cylindrical cell (10) being characterized in that the first electrode sheet (3) is electrically connected to the cylindrical metal case (2) according to a method in accordance with any one of the preceding claims. Cylindrical cell (10) according to the preceding claim, characterized in that the first electrode sheet (3) and the current collection tab (4) are made in one piece.

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