Electric cell and its manufacturing process

Abstract

An electric cell (10) comprising - a cylindrical stack (1) 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; - a housing (6) comprising a cylindrical metal casing (61) having an internal face (62) delimiting a housing in which the cylindrical stack (1) is housed; - a current collector (4) connected to the first electrode sheet; said current collector (4) comprising on its periphery a rim (41) comprising an external lateral face (42) intended to come into contact with the internal face (62); an internal lateral face (43) opposite the external lateral face (42); a slice (44) connecting the external lateral face and the internal lateral face and being intended to receive a weld bead (7) for welding said collector (4) to the internal face (62). Figure for the abstract: Fig.1

Description

Title of the invention: Electric cell and its manufacturing method

[0001] The present invention relates to the technical field of cylindrical cells of electric batteries and to their manufacturing methods.

[0002] The cylindrical cells are manufactured by winding around a mandrel, a successive stack of at least: - a positive electrode sheet or cathode; - an insulating separator sheet; - a negative electrode sheet or anode; - an insulating separator sheet.

[0003] Current collecting tabs devoid of (uncoated or uncovered) active material are provided along the positive and negative electrode sheets in the direction of the longitudinal axis of the cylindrical cell. These current collecting tabs are used to collect and conduct the electric current. These current collecting tabs are folded, folded down or packed in planes perpendicular to the longitudinal axis of the cylindrical cell on either side thereof. A first current collector and a second current collector are, respectively, electrically connected to the anode and the cathode by welding to the current collecting tabs. The anode current collector and the cathode current collector are in the form of two solid or perforated discs intended to form or to be connected to the output terminals (also called poles) of the electric battery.

[0004] The cylindrical stack is housed in a cylindrical casing after which an electrolyte is injected into said cylindrical casing. This casing is in the form of a hollow cylindrical enclosure.

[0005] Once the cylindrical stack is housed in the housing, the current collector is secured to the housing. The securing is carried out from an external face of the housing by welding or by blind stamping.

[0006] Thus the anode current collector is secured to the casing in a haphazard manner because the welding and / or stamping is carried out blindly as previously mentioned. This can have serious consequences as to the stability and quality of the electrical contact of the current collector, in particular that of the anode. In addition, a failure to fix the anode current collector to the bottom of the casing can affect the performance of the cylindrical cell or even be the cause of very serious accidents during use, due to unwanted movement of the current collector.

[0007] An object of the present invention is to facilitate the achievement of a stable and secure electrical connection between the current collector of the anode (or, more equivalent, of the cathode) and the case housing the cylindrical cell.

[0008] Another object of the present invention is to improve the fixing of the current collector.

[0009] Another object of the present invention is to obtain more reliable cells.

[0010] For this purpose, there is proposed, firstly, an electric cell comprising - a cylindrical stack successively comprising a first electrode sheet, a first separator, a second electrode sheet of polarity opposite to the first electrode sheet and a second separator; - a housing comprising a cylindrical metal casing having an internal face delimiting a housing in which the cylindrical stack is housed; - a current collector connected to the first or second electrode sheet; the current collector comprising on its periphery a rim comprising an outer side face intended to come into contact with the inner face of the cylindrical envelope when the cylindrical stack is housed in the housing; an inner side face opposite the outer side face; a slice connecting the outer side face and the inner side face, the cell comprising a weld bead affixed to the edge and to the internal face of the cylindrical envelope to weld the current collector to said internal face of the cylindrical envelope.

[0011] Various additional features may be provided, alone or in combination: - the edge of the rim is substantially flat and extends substantially perpendicular to a longitudinal axis of the cylindrical casing of the housing; - the current collector has a thickness between 0.1 millimeter and 0.6 millimeter; - the thickness of the current collector is approximately equal to 0.35 millimeters; - the thickness of the current collector is substantially uniform over its entire surface; - a total height including the thickness of the current collector and the height of the rim, measured along the longitudinal axis of the cylindrical envelope, is at least equal to two and a half times the thickness of the current collector; - the rim is present on at least two diametrically opposite parts of the periphery of the current collector; - the current collector has, before it comes into contact with the internal face of the cylindrical envelope, an initial diameter greater than the internal diameter of the cylindrical envelope, this current collector bending, when it comes into contact with the cylindrical envelope, at its periphery under the effect of this contact so as to form the rim; - the current collector comprises copper; - the current collector includes nickel.

[0012] Secondly, a method of manufacturing the electric cell presented above is proposed comprising the following steps: - arrangement of the cylindrical stack in the housing so that the outer side face of the rim comes into contact with the inner face of the cylindrical casing; - application of a weld bead on the edge of the rim so as to weld the current collector to the internal face of the cylindrical envelope.

[0013] Various additional features may be provided, alone or in combination: - the method presented above further comprises a step of inserting the current collector into the cylindrical envelope so that this current collector bends, when it comes into contact with the cylindrical envelope, at its periphery under the effect of this contact to form the rim, this current collector having, before it comes into contact with the internal face of the cylindrical envelope, an initial diameter greater than the internal diameter of the cylindrical envelope; - the above further comprises a step of pre-bending the periphery of the current collector (4) with an angle between 20 and 75 degrees, this pre-bending step being prior to the insertion step; - the angle is approximately equal to 60 degrees.

[0014] Other characteristics and advantages of the invention will appear more clearly and concretely on reading the following description of embodiments, which is given with reference to the appended drawings in which:

[0015] [Fig.l] schematically illustrates the connection of a current collector of an anode of a cylindrical cell to the housing of an electric battery according to various embodiments;

[0016] [Fig.2] schematically illustrates steps of a method of manufacturing the aforementioned electric battery according to various embodiments.

[0017] Referring to [Fig.l], there is shown an electric cell 10 comprising - a cylindrical or, more generally, substantially cylindrical stack 1 successively comprising a first electrode sheet 2 (for example, an anode), a first separator, a second electrode sheet of polarity opposite to the first electrode sheet 2 and a second separator; - a housing 6 capable of containing the cylindrical stack 1.; - a current collector 4 connected to the first electrode sheet 2 or to the second electrode sheet. At least a portion of the current collector 4 is, in one embodiment, intended to form an output terminal (or pole) of the cell 10 electric.

[0018] The housing 6 comprises a cylindrical (or, more generally, substantially cylindrical) metal casing 61. The cylindrical casing 61 has an internal face 62 delimiting a housing in which the cylindrical stack 1 is housed.

[0019] The current collector 4 is intended to be welded to the inner face 62 of the cylindrical envelope 61. The inner face 62 of the cylindrical envelope 61 is therefore arranged to be in electrical contact with the current collector 4 itself welded or electrically connected to the current collection tabs of the first electrode sheet 2 or of the second electrode sheet. For better electrical conductivity, the current collector 4 comprises copper and / or nickel.

[0020] For this, the current collector 4 comprises, on its periphery, a rim 41 (or has a rim 41 peripherally). This rim 41 is a raised / folded edge or a projecting part at least partially limiting the current collector 4 (i.e. on at least a part of the periphery of the current collector 4).

[0021] The rim 41 comprises - an external lateral face 42 intended to come into contact with the internal face 62 of the cylindrical envelope 61 when the cylindrical stack 1 is housed in the housing 6 - an inner lateral face 43 opposite the outer lateral face 42; - a slice 44 connecting the outer lateral face 42 to the inner lateral face 43 intended to receive a weld bead 7 for welding the current collector 4 to the inner face 62 of the cylindrical casing 61.

[0022] The electric cell 10 comprises, in fact, a weld bead 7 affixed to the edge 44 and to the internal face 62 of the cylindrical envelope 61 to weld the current collector 4 to the internal face 62 of the cylindrical envelope 61. In this connection, the edge 44 of the rim 41 advantageously serves as a mattress allowing simple and safe (non-hazardous) welding (in particular, by laser) of the current collector 4 to the cylindrical envelope 6.

[0023] The thickness of the current collector 4 or, equivalently, of the edge 44 is, in one embodiment, between 0.1 millimeter and 0.6 millimeter, more preferably between 0.2 millimeter and 0.5 millimeter or even more preferably substantially equal to 0.35 millimeter. The thickness of the current collector 4 is, preferably, substantially homogeneous over its entire surface. It follows that the thickness of the edge 44 is substantially homogeneous over its entire length. The thickness of the edge 44 of the rim 41 offers, in fact, a welding surface making it possible to securely affix a weld bead 7 to weld the current collector 4 to the internal face 62 of the cylindrical casing 61. This results in a reinforcement of the mechanical and electrical connection between the current collector 4 and the box 6.

[0024] The rim 41 advantageously guarantees the mechanical and electrical connection between the current collector 4 and the housing 6 with regard to possible thermal expansions caused by the heating of the elements involved in this connection under the effect of strong electric currents. For this, the height of the rim 41 measured along the longitudinal axis of the cylindrical casing (61) is, in one embodiment, at least equal to one and a half times the thickness of the current collector 4. In other words, a total height comprising the thickness of the current collector 4 and the height of the rim 41, measured along the longitudinal axis of the cylindrical casing 61, is at least equal to two and a half times the thickness of the current collector 4. The height of the rim 41, measured along the longitudinal axis of the cylindrical casing 61, corresponds substantially to the height of the inner lateral face 43 measured along this same longitudinal axis of the cylindrical casing 61.Such dimensions ensure both ease of soldering and a flexible and solid connection between the current collector 4 and the internal face 62 of the cylindrical casing 61 of the housing 6.

[0025] In one embodiment, the edge 44 of the rim 41 is substantially planar and extends substantially perpendicular to a longitudinal axis of the cylindrical casing 61 of the housing 6. Such an arrangement further facilitates the safe application of the weld bead 7. The angle formed by the edge 44 and the internal face 62 can serve as a guide for the application of a weld bead 7, in particular laser.

[0026] In another embodiment, the rim 41 is present on at least two diametrically opposite portions (or diametrically opposite portions in pairs) of the periphery of the current collector 4. This distribution of the rim 41 advantageously improves the stability of the welding attachment of the current collector 4 to the cylindrical casing 61, while optimizing the required length of the welding bead 7. The current collector 4 is, in one embodiment, a foil in the form of a perforated metal disc (in particular, made of copper or nickel-plated copper) having a rim 41 on its outer periphery.

[0027] In one embodiment, the current collector 4 has, before it comes into contact with the internal face 62 of the cylindrical casing 61, an initial diameter greater than the internal diameter of the cylindrical casing 61. This current collector 4 can, in fact, be inserted into the cylindrical casing 61 so as to form, during this insertion, the rim 41 at its periphery. In other words, the rim 41 can be formed by stamping the current collector 4 in the cylindrical casing 61. When the current collector 4 comes into contact with the cylindrical casing 61, it bends at its periphery under the effect of this contact so as to form the rim 41. Referring to [Fig. 2], a method of manufacturing the cell 10 described above comprises a step 21 of arranging (or housing) the cylindrical stack 1 in the housing 6 so that the outer lateral face 42 of the rim 41 comes into contact with the inner face 62 of the cylindrical envelope 61. The current collector 4 is arranged concentrically with the cylindrical envelope 61 so that the outer surface 42 of the rim 41 comes into intimate contact with the inner face 62 of the cylindrical envelope 61 which is, as a result, in electrical contact with the anode 2.

[0028] In one embodiment, when the current collector 4 has, before it comes into contact with the internal face 62 of the cylindrical casing 61, an initial diameter greater than the internal diameter of the cylindrical casing 61, the method for manufacturing the electric cell 10 comprises a step of inserting this current collector 4 into the cylindrical casing 61 so that this current collector 4 bends, when it comes into contact with the cylindrical casing 61, at its periphery under the effect of this contact to form the rim 41. To facilitate this insertion, the periphery of the current collector 4 is preferably pre-bent with an angle of between 20 and 75 degrees, more preferably between 45 and 70 degrees or even more preferably equal to 60 degrees.This pre-folding step advantageously makes it possible to obtain a uniform height of the rim 41 and to accommodate the guidance of the current collector 4 during its insertion into the cylindrical casing 61.

[0029] Next, a weld bead 7 is applied (step 22) to the edge 44 of the rim 41 so as to weld the current collector 4 to the internal face 62 of the cylindrical casing 61. This advantageously results in a solid, direct and non-hazardous fixing, ensuring a mechanical and electrical connection by welding of the current collector 4 with the housing 6. The weld bead 7 may be continuous or discontinuous on the edge 44 of the rim 41.

[0030] It should be noted that the usual prior steps of winding the cylindrical stack 1 and fixing the current collector 4 to the first electrode sheet or to the second electrode sheet are not shown here.

Claims

Claims

1. An electric cell (10) comprising - a cylindrical stack (1) successively comprising a first electrode sheet (2), a first separator, a second electrode sheet of polarity opposite to the first electrode sheet and a second separator; - a housing (6) comprising a cylindrical metal envelope (61) having an internal face (62) delimiting a housing in which the cylindrical stack (1) is housed; - a current collector (4) connected to the first or second electrode sheet; the electric cell (10) being characterized in that the current collector (4) comprises on its periphery a rim (41) comprising an external lateral face (42) intended to come into contact with the internal face (62) of the cylindrical envelope (61) when the cylindrical stack (1) is housed in the housing (6); an internal lateral face (43) opposite the external lateral face (42);a slice (44) connecting the outer lateral face (42) and the inner lateral face (43), the cell (10) comprising a weld bead (7) affixed to the slice (44) and to the inner face (62) of the cylindrical envelope (61) to weld the current collector (4) to said inner face of the cylindrical envelope (61).;

2. Electric cell (10) according to the preceding claim, characterized in that the edge (44) of the rim (41) is substantially flat and extends substantially perpendicular to a longitudinal axis of the cylindrical envelope (61) of the housing (6).

3. Electric cell (10) according to claim 1 or 2, characterized in that the current collector (4) has a thickness of between 0.1 millimeter and 0.6 millimeter.

4. Electric cell (10) according to claim 3, characterized in that the thickness of the current collector (4) is substantially equal to 0.35 millimeters.

5. Electric cell (10) according to claim 3 or 4, characterized in that the thickness of the current collector (4) is substantially uniform over its entire surface.

6. Electric cell (10) according to any one of the preceding claims, characterized in that a total height comprising the thickness of the current collector (4) and the height of the rim (41), measured along the longitudinal axis of the cylindrical envelope (61) is at least equal to two and a half times the thickness of the current collector (4).

7. Electric cell (10) according to any one of the preceding claims, characterized in that the rim (41) is present on at least two diametrically opposite parts of the periphery of the current collector (4).

8. Electric cell (10) according to any one of the preceding claims, characterized in that the current collector (4) has, before it comes into contact with the internal face (62) of the cylindrical envelope (61), an initial diameter greater than the internal diameter of the cylindrical envelope (61), this current collector (4) bending, when it comes into contact with the cylindrical envelope (61), at its periphery under the effect of this contact so as to form the rim (41).

9. An electrical cell (10) according to any one of the preceding claims, characterized in that the current collector (4) comprises copper.

10. An electric cell (10) according to any one of the preceding claims, characterized in that the current collector (4) comprises nickel.

11. Method for manufacturing the electric cell (10) of any one of the preceding claims, comprising the following steps: - arrangement (21) of the cylindrical stack (1) in the housing (6) so that the outer lateral face (42) of the rim (41) comes into contact with the inner face (62) of the cylindrical envelope (61); - application (22) of a weld bead (7) on the edge (44) of the rim (41) so as to weld the current collector (4) to the inner face (62) of the cylindrical envelope (61).

12. Method according to the preceding claim, characterized in that it further comprises a step of inserting the current collector (4) into the cylindrical casing (61) so that this current collector (4) folds, when it comes into contact with the cylindrical casing (61), at its periphery under the effect of this contact to form the rim (41), this current collector (4) having, before it comes into contact with the internal face (62) of the cylindrical casing (61) lindrique, an initial diameter greater than the internal diameter of the cylindrical envelope (61).

13. Method according to the preceding claim, characterized in that it further comprises a step of pre-bending the periphery of the current collector (4) with an angle of between 20 and 75 degrees, this pre-bending step being prior to the insertion step.

14. Method according to the preceding claim, characterized in that the angle is substantially equal to 60 degrees.

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