SE2350518A1 - A covered terminal rivet for a secondary cell and a method of manufacturing a secondary cell - Google Patents

A covered terminal rivet for a secondary cell and a method of manufacturing a secondary cell

Info

Publication number
SE2350518A1
SE2350518A1 SE2350518A SE2350518A SE2350518A1 SE 2350518 A1 SE2350518 A1 SE 2350518A1 SE 2350518 A SE2350518 A SE 2350518A SE 2350518 A SE2350518 A SE 2350518A SE 2350518 A1 SE2350518 A1 SE 2350518A1
Authority
SE
Sweden
Prior art keywords
rivet
cover
terminal
recess
weld
Prior art date
Application number
SE2350518A
Inventor
Kenya Shatani
Original Assignee
Northvolt Ab
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Northvolt Ab filed Critical Northvolt Ab
Priority to PCT/EP2024/050821 priority Critical patent/WO2024153592A1/en
Publication of SE2350518A1 publication Critical patent/SE2350518A1/en

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/543—Terminals
    • H01M50/564—Terminals characterised by their manufacturing process
    • H01M50/566—Terminals characterised by their manufacturing process by welding, soldering or brazing
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/04—Construction or manufacture in general
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/147—Lids or covers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/172—Arrangements of electric connectors penetrating the casing
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/531—Electrode connections inside a battery casing
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/531—Electrode connections inside a battery casing
    • H01M50/536—Electrode connections inside a battery casing characterised by the method of fixing the leads to the electrodes, e.g. by welding
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/147—Lids or covers
    • H01M50/148—Lids or covers characterised by their shape
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/543—Terminals

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Connection Of Batteries Or Terminals (AREA)

Abstract

This disclosure presents a terminal rivet (1) for a secondary cell (50), the terminal rivet (1) comprising a rivet part (10) comprising a weld recess (12) through which the rivet part (10) may be welded and electrically connected to an internal component (55) of the secondary cell (50), and a cover part (20) configured to be attached to the rivet part (10) to cover the weld recess (12) of the rivet part (10). The disclosure further presents a method of manufacturing a secondary cell.

Description

A COVERED TERMINAL RIVET FOR A SECONDARY CELL AND A METHOD OF MANUFACTURING A SECONDARY CELL TECHNICAL FIELD The present disclosure generally pertains to terminal parts for secondary cells, and more particularly to a terrninal rivet and a method of manufacturing a secondary cell that comprises a terminal rivet.
BACKGROUND In addressing climate change, there is an increasing demand for rechargeable batteries, e.g. to enable electrif1cation of transportation and to supplement reneWable energy. Currently, lithium-ion batteries are becoming increasingly popular. They represent a type of rechargeable battery in Which lithium ions move from the negative electrode to the positive electrode during discharge and back When charging.
As the demand for rechargeable batteries increases, more and more focus is being placed on production speed and cost. To achieve an effective production of rechargeable batteries, the design of the batteries as Well as their manufacturing process can be optimized.
SUMMARY The present disclosure aims at providing improved secondary cells and parts thereof. The improvements may be in energy performance, manufacturing efficiency, decreased amount of material used and assembly simplif1cation.
According to one aspect of the present disclosure, a terminal rivet for a secondary cell is provided. The terminal rivet comprises a rivet part comprising a Weld recess through Which the rivet part may be Welded and electrically connected to an intemal component of the secondary cell. The terminal rivet further comprises a cover part configured to be attached to the rivet part to cover the Weld recess of the rivet part.
The Weld recess allows the rivet part to be Welded to the intemal component through the rivet part, in other Words from an outside of the secondary cell. The Weld recess reduces the material thickness through Which the Welding is performed. In addition, the Weld recess may render the terminal rivet lighter and consume less material, as compared to a solid rivet part. Typically, the axial extension of the Weld recess corresponds to at least half the axial extension of the terminal rivet. The rivet part and the cover part may together provide a flat terminal surface.
The rivet part may comprise a head portion, also referred to as a factory rivet head, and a shaft portion. The shaft portion may after riveting form an intemal rivet head, also referred to as a shop rivet head. The Weld recess may comprise a lateral sideWall that is straight and extends from an open end to a closed end of the Weld recess. The terminal rivet may be entirely formed of metal. The area of the cover part may be substantially larger than the area of the Weld recess.
According to another aspect of the present disclosure, a method of manufacturing a secondary cell comprising terminal rivet is provided. The method comprises conductor Welding a rivet part of a terminal rivet to an intemal component of the secondary cell. The conductor Welding may be performed from an outside of the secondary cell. In other Words, from a position axially outside the terminal rivet When assembled to the secondary cell. The method further comprises cover Welding a cover part of the terminal rivet to the rivet part. The cover Welding may also be performed from an outside of the secondary cell.
Further advantages associated With the present disclosure, and additional conceivable features, Will become clear from the following description of embodiments and examples.
BRIEF DESCRIPTION OF THE DRAWINGS The above and other aspects of the present invention Will now be described in more detail, With reference to the appended figures in Which Figure l is a schematic axial cross-section of a terminal rivet comprising a rivet part and a cover part to be attached to the rivet part, Figure 2 illustrates the terminal rivet of figure l When riveted, and With the cover part attached to the rivet part, Figure 3 is a schematic axial cross-section of a terminal rivet of another example, Where the rivet part and cover part are stepped, Figure 4 illustrates a cylindrical secondary cell together with a terminal rivet, and also at least partly demonstrates a method of manufacturing a secondary cell, and Figures 5 to 8 illustrate other examples of terminal rivets, each comprising a cover part attached to a rivet part.
DETAILED DESCRIPTION The present invention will now be described hereinafter with reference to the accompanying drawings, in which currently preferred examples of the invention are illustrated.
A rechargeable battery, often referred to as a secondary battery, typically comprises one or more secondary cells (herein referred to as "cells") electrically connected to each other. A cell having both terrninals arranged at one end may bring advantages with regards to electrically connecting the cell to a load. Conductors electrically connecting the terrninals to the load may then be positioned on the same end, the terminal end, of the cell. The opposite end may be dedicated to electrolyte filling and venting of gas and/or other ej ecta, and may hence be referred to as the electrolyte-filling end of the cell.
An overpressure may be generated within the cell during operation, in particular upon malfunction of the cell or of the load connected to the cell. Such malfunction may require a pressure release action in which gas and/or other ej ecta is discharged from the cell. It may be advantageous to direct the released gas and/or other ej ecta away from the conductors.
A plurality of cells may typically be positioned at a low position in an electric vehicle. The cells may be arranged with their terminal ends directed upwards and their electrolyte-filling ends directed downwards. Upon malfunction, for example resulting from a faulty electric vehicle charger or a faulty cell, a release of gas and/or other ej ecta from the electrolyte-filling end(s) will be advantageously directed downwards towards the ground beneath the vehicle.
When both terrninals of a cell are arranged at one end of the cell, electrical isolation between the conductors that electrically connect the terrninals to the load is very important. One terminal (typically the negative terminal) may be formed by the enclosure of the cell, also referred to as the can. The other terminal (typically the positive terminal) may be formed by a terminal part that extends through a terminal hole in a can end wall. The terminal part may typically serve the dual purposes of proving an electrical terminal and sealing the can. Advantageously, as in the current examples, the terrninal part may be provided in the form of a rivet.
This disclosure relates to a cell, more precisely a cylindrical cell, having both terrninals arranged at one end. However, the teachings herein can also be applied to other cells, such as cells of other shapes and having the terrninals arranged on different ends or sides of the cell.
Examples of the present disclosure will now be described more fully hereinafter, with reference to the figures. The same reference numbers are used throughout the figures. The invention may, however, be embodied in many different forms and should not be construed as limited to the examples set forth herein; rather, these examples are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to the persons skilled in the art.
Figures 1 to 8 show a terrninal rivet 1 for a secondary cell 50. The secondary cell 50 may be a cylindrical secondary cell, as is illustrated in figure 4 where the dash-dot line illustrates an axis of symmetry. The terrninal rivet 1 comprises a rivet part 10 and a cover part 20.
The rivet part 10 comprises a weld recess 12 through which the rivet part 10 may be welded and electrically connected to an intemal component 55 (see figure 4) of the cell 50. Figure 3 schematically illustrates a laser (dashed trapezoid) generating a laser beam (dotted arrow). The terrninal rivet 1 allows welding through the weld recess 12 of the rivet part 10, which means that a laser beam may travel through the weld recess 12 during welding.
Referring in particular to figure 4, the terrninal rivet comprises 1 proximal end (lower end in the figures), or inner end, that faces the cell 50 and a distal end (upper end in the figures), or outer end, that faces away from the cell 50. The terrninal rivet 1 allows welding from the distal end of the terrninal rivet 1, i.e. from an outside of the cell 50 when the terrninal rivet 1 is assembled thereto.
The cover part 20 is configured to be attached to the rivet part 10 to cover the weld recess 12 of the rivet part 10. In other words, when the cover part 20 is attached to the rivet part 10, the weld recess 12 is covered or closed. As is illustrated, the area of the cover part 20 is substantially larger than the area of the weld recess 12. The area of the cover part 20 may be times larger, or 5 to 15 times larger, than the area of the weld recess 12.
As is shown, the rivet part 10 may comprise a shaft portion 14 adapted to extend through an enclosure wall 52 (see figure 4) of the secondary cell 50 and a head portion 16 adapted to forrn an external terrninal of the secondary cell 50. The head portion 16 may be referred to as a factory rivet head (formed in a rivet factory). The shaft portion 14 may after riveting (deformation, see figure 2) forrn a so-called shop rivet head (formed in a workshop). After cell manufacture, the head portion 16 forms an extemal rivet head and the shaft portion 14 forms an intemal rivet head.
Even though it is conceivable that the terminal rivet 1 comprises further undepicted parts, the terminal rivet 1 may consist solely of the shaft portion 14 and the head portion 16. The shaft portion 14 and the head portion 16 are typically made of metal, and thus the terminal rivet 1 may be entirely made of metal.
As is illustrated, the weld recess 12 may comprise an open end and a closed end. The open (distal) end faces the cover part 20 and the closed (proximal) end comprises a conductor weld region 12w. The closed end, or more in detail the axially outer (here, lower) surface of the conductor weld region 12w, faces the cell 50. The weld recess 12 may have the shape of a cylinder with circular (as shown) or polygonal cross-section. In the current examples, the bottom of the weld recess 12 forms the conductor weld region 12w.
To facilitate welding, the conductor weld region 12w may be least 3 millimeters across. Typically, the conductor weld region 12w measures 3 to 6 millimeters across. As in the present examples, the weld recess 12 may comprises a lateral sidewall that is straight and extends from the open end to the closed end. The illustrated weld recess 12 is circular cylindrical and thus comprises one straight circumferential sidewall. Thus, the diameter d (denoted in figure 3) of the conductor weld region 12w and of the weld recess 12 may be 3 to 6 millimeters.
The depth, or axial extension, of the weld recess 12 typically corresponds to more than half of the height, or axial extension, of the terminal rivet 1. The depth of the weld recess may be 1.5 to 4 millimeters, such as 2 to 3 millimeters. The depth of the weld recess 12 may correspond to 3 to 10 percent of the cell diameter, or preferably 4 to 7 percent of the cell diameter.
The material thickness t (denoted in figure 3) of the rivet part 10 at the conductor Weld region l2W may be selected to facilitate Welding there through. As mentioned, the Welding may be laser beam Welding and the material thickness t may be adapted to the penetration depth of the laser. For example, the material thickness t may be approximately 1 millimeter, a suitable range being 0.5 to 1.5 millimeters.
The material thickness t of the conductor Weld region l2W may be affected by the riveting of the rivet part 10, the above thickness t range applies to the rivet part 10 before riveting.
The rivet part 10 and the cover part 20 may j ointly form a terminal surface 2 (denoted in figures 2 and 5) When the cover part 20 is attached to the rivet part 10. The rivet part 10 and the cover part 20 may, as is illustrated, be conf1gured such that the terminal surface 2 is essentially flat. A flat terminal surface 2 may be advantageous for connecting a conductor to the terminal surface 2 of the terminal rivet 1. The terminal surface 2, in the present examples the distal axial end surface of the terminal rivet 1, may be completely flat.
The rivet part 10 may comprise a cover recess 18 (denoted in figures 1, 3, 5 and 7). The cover recess 18 may be configured to receive the cover part 20, and may facilitate positioning the cover part 20 onto the rivet part 10. As is illustrated in figures 1 to 4 and 8, the shape and size of the cover part 20 may correspond to the shape and size of the cover recess 18. By means of the cover recess 18, the cover part 20 and the rivet part 10 may be joined in a positive fit such that mutual radial movement is hindered. In the present examples, the cover part 20 and the cover recess 18 are essentially disc-shaped.
The cover recess 18, if present, is typically radially larger than the Weld recess 12. A possible altemative solution to obtaining a flat terminal surface 2 Would be f1lling the Weld recess 12 With a plug element or similar. Thus, such a plug element Would not be larger but be of the same (radial) size are the Weld recess 12. HoWever, such an altemative solution is believed more complex as regards placing and securing such a plug element inside the Weld recess 12. Furthermore, the inner dimension of the Weld recess 12 may change as a result of the riveting, Which complicates f1tting a plug element in the Weld recess 12.
The cover part 10 may comprise a cover Welding region 20W arranged radially extemally the Weld recess 12. As illustrated, the cover Welding region 20W may radially surround the Weld 6 recess 12. The cover welding region 20w may be annular. The cover welding region 20w may facilitate welding the cover part 20 to the rivet part 10. The cover welding region 20w may be at least 2 millimeters across. The cover welding region 20w may be annular and have an annulus width of at least 1 millimeter. Thus, as seen across the cover part 20, the two annuli will together have a width exceeding 2 millimeters. The material thickness of the cover welding region 20w may be selected to facilitate welding there through and may be 0.5 to 1.5 millimeters.
As is apprehended from figures 1 and 2, the cover welding region 20w may be welded to the cover recess 18, more precisely to the radial, and here annular, surface of the cover recess 18 of the rivet part 10 on which the cover welding region 20w rests after assembly. The welding is typically performed from the distal end of the terminal rivet 1.
The example illustrated in figure 3 differs from the one of figure 1 in that the rivet part 10 and the cover part 20 are stepped. Referring to figure 3, the cover part 20 may comprise an intemal cover portion 20i and an extemal cover portion 20e, the intemal cover portion 20i protruding axially from the extemal cover portion 20e. The intemal cover portion 20i protrudes axially from the extemal cover portion 20e towards the rivet part 10. The intemal cover portion 20i and the extemal cover portion 20e may be coaxial, as illustrated. The extemal cover portion 20e is annular and radially surrounds the intemal cover portion 20i in a plan view.
Similarly, the rivet part 10 may comprise an intemal cover recess 18i and an extemal cover recess 18e. The intemal cover recess 18i is made in the extemal cover recess 18e. The extemal cover recess 18e is annular and radially surrounds the intemal cover recess 18i in a plan view. The extemal cover recess 18e is adapted to receive the extemal cover portion 20e and the intemal cover recess 18i is adapted to receive the intemal cover portion 20i.
The material thickness of the extemal cover portion 20e may be selected to facilitate welding there through and may be 0.5 to 1.5 millimeters. As is apprehended from figure 3, the extemal cover portion 20e may be welded to the extemal cover recess 18e, more precisely to the radial, and here annular, surface of the rivet part 10 on which the extemal cover portion 20e rests after assembly. The welding is typically performed from the distal end of the terminal rivet 1.
The material thickness of the internal cover portion 20i exceeds the material thickness of the external cover portion 20e, and the internal cover portion 20i may therefore provide mechanical strength to the cover part 20.
Figure 4 illustrates an example layout of a cylindrical secondary cell 50. The cell 50 comprises a cylindrical can (or enclosure) having a can end Wall 52 (the top end Wall of the cylindrical can in figure 4) and an opposite can end (the bottom end Wall). The can end Wall 52 may be formed in one piece With the cylindrical can (as illustrated in figure 4) and the other can end may be formed by a separate can end lid (not shown), or vice versa. Both the can ends may altematively be formed by respective lids.
The cylindrical can may be filled With an electrolyte. An electrode assembly, typically a so- called j elly-roll, is arranged inside the cylindrical can. A j elly-roll is a commonly used type of electrode assembly having a structure in Which a positive electrode and a negative electrode each having a long sheet shape are Wound With an (optional) separator interposed in-between. The cell 50 may further comprises a current collecting plate 55 that is arranged at one end of the electrode assembly. The current collecting plate 55 may be in direct electrical and physical contact With one of the electrodes of the electrode assembly, typically the positive electrode. The current collecting plate may be attached, for example Welded, for example laser beam Welded, to the positive electrode.
The cell 50 may have, as discussed above, both the positive terminal and the negative terminal positioned at one and the same end (the top end in figure 4) of the cell 50. The can end Wall 52 comprises a central terminal through-hole 54 (also referred to as terminal opening) for the terminal part 1 forrning the positive terminal. The negative terminal is electrically connected to the cylindrical can. More precisely, the negative terminal is formed by the outer surface of the can end Wall 52 that surrounds the terminal through-hole 54. Thus, the entire cylindrical can (apart from the terminal part 1 at the top end) may be the negative terminal.
The terminal part 1 of the present examples thus provides an electrical connection to an electrode of the electrode assembly arranged inside the cylindrical can. The terminal part 1 is inserted into the terminal through-hole 54 formed in the can end Wall 52. Typically, a terminal gasket 30 is arranged in the terminal through-hole 54 to electrically isolate the terminal part from the can end Wall 52, and for sealing purposes. The terminal gasket 30 may, as illustrated 8 in figures 4 and 7, comprise a first portion 32 that may be essentially disc-shaped and is positioned between head portion 16 and the can end Wall 52. The terminal gasket 30 may further comprise a second portion 34 that may be circular-cylindrical and surrounds the shaft portion 14. The terminal gasket 30 may comprise a third portion 36 being essentially disc shaped and positioned on the inner side of the can end Wall 52. The third portion 36 may take the shape of a disc, or a truncated cone, for example as a result of the terminal gasket 30 being deforrned upon riveting, as may be apprehended from a comparison of figures 2 and 4 or 7. The deformation of the terminal gasket 30 is illustrated by a curved arrow in figure 7. The terminal gasket 30 may comprise a fourth circular-cylindrical portion 38 that may surround the head portion 16 of the rivet part 10 (see figure 7). The terminal gasket 30 may also comprise several parts instead of being one single part. Altematively, lisolation meansÉ [Ksi]l[cB2]§[Ks3]§[WH4]e. g. in form of a coating may be integrated in the rivet part 10. Such a coating may be advantageous for the sealing performance.
The terminal part 1 protrudes from the terminal through-hole 54 and extends there through into the cylindrical can. The terminal part 1 extends through the can end Wall 52 and has an outer, or distal, end and an inner, or proximal, end. The outer end of the terminal part 1 may form the positive terminal of the cell 50. In the examples of the present disclosure, the terminal part 1 is rotational symmetric around its longitudinal center axis (figure 1).
In the examples of figures 1 to 4 and 8, the rivet part 10 and the cover part 20 jointly form the terminal surface 2. As has been described, in the examples of figures 1 to 4 and 8, the rivet part 10 comprises a cover recess 18 configured to receive the cover part 20, more precisely the entire cover part 20. As is illustrated in figures 1 to 4 and 8, the rivet part 10 may comprise an annular edge that surrounds the cover part 20. Thus, the cover part 20 and an annular edge of the rivet part 10 may j ointly form the terminal surface 2.
The examples illustrated in figures 5 to 7 differ from the ones of figures 1 to 4 and 8 in that the cover part 20 alone forms the terminal surface. In the examples of figures 5 to 7, the cover part 20 covers the entire rivet part 10 (in an axial vieW from above) and forms the terminal surface 2 When attached to the rivet part 10. The terminal surface 2 may be essentially flat also When the cover part 20 forms the entire terminal surface, see figures 5 to 7. In the examples of figures and 6, the terminal surface 2 is completely flat.
Referring to the above paragraph and to a comparison of figures 5 and 3, the example illustrated in figure 5 differs from the one of figure 3 only in that the rivet part 10 does not comprise an annular edge that surrounds the cover part 20.
Similarly, the example illustrated in figure 6 differs from the one of figure 1 in that the rivet part 10 does not comprise an annular edge that surrounds the cover part 20. Furthermore, the cover part 20 of figure 6 is received, more precisely partly received, in the Weld recess 12. In other Words, only a portion of the cover part 20, more precisely only the internal cover portion 20i, is received in the rivet part 10. Thus, in this example, the Weld recess 12 comprises the cover recess 18. The distal end of the Weld recess 12 functions as a cover recess 18. The cover part 20 of the example of figure 6 is T-shaped. The T-shaped cover part comprises a (relatively short) vertical part formed by the intemal cover portion 20i and a horizontal part formed by the extemal cover portion 20e.
The example illustrated in figure 8 differs from the one of figure 6 in that the rivet part 10 comprises an annular edge (as is the case in figure 1) that surrounds the cover part 20. Further, in figure 8 the intemal cover portion 20i is adapted to substantially fill the Weld recess 12. It is to be apprehended that each one of the examples of figures 1 to 7 may comprise an intemal cover portion 20i that is shaped and sized to substantially fill the Weld recess 12.
The example illustrated in figure 7 differs from the other examples in that the Weld recess 12 comprises a lateral sideWall that extends at an angle ot, i.e. not parallel to, to the longitudinal center axis. In each of the examples of figures 1 to 6 and 8, the Weld recess 12 comprises a lateral sideWall that extends parallel to the longitudinal center axis. The Weld recess 12 of the example of figure 7 has a frustoconical shape. Thus, the Weld recess 12 may be cylindrical, as is shown in figures 1 to 6 and 8, or frustoconical as is shown in figure 7. It is to be apprehended that each one of the examples of figures 1 to 6 and 8 may comprise a Weld recess 12 of a frustoconical shape. A frustoconical Weld recess 12 may facilitate Welding, as a laser beam may more easily be applied onto the conductor Weld region 12W.
The lateral sideWall of the Weld recess 12 may preferably extend at an angle ot of 40 to 50 degrees With respect to the longitudinal center axis. A suitable range for the angle u being 30 to 60 degrees.
The example illustrated in figure 7 further differs from the other examples in that the cover part 20 comprises a stepped external (here, upper) surface. i.e. there is a stepped terrninal surface 2. The terrninal surface 2 of figure 7 is essentially flat but not completely flat. The step 22 axially separates a central protruding portion from an annular portion surrounding the central protruding portion. The annular portion may form the cover Welding region 20W, as indicated in figure 7. The central protruding portion may be particularly suitable for connection, typically Welding, of a conductor that electrically connects the terrninal part 1 to a load. The stepped terrninal surface 2 may provide a material thickness of the cover Welding region 20W that is selected to facilitate Welding there through, such as 0.5 to 1.5 millimeters. It is to be apprehended that each one of the examples of figures 1 to 6 and 8 may comprise a cover part comprising a stepped terrninal surface.
The height of the step 22, i.e. the distance that the central protruding portion is axially separated from the surrounding annular portion, may be 0.1 to 0.3 millimetres. The step 22 height may correspond to 0.2 to 0.7 percent of the cell diameter, or preferably 12 to 20 percent of the cell diameter.
As is illustrated in figure 7, the central protruding portion that is defined by the step 22 may be of essentially the same dimension or diameter as the Weld recess 12. Thus, the central protruding portion may cover the Weld recess 12 in a plan view, as is apprehended from the axial cross-section of figure 7. More precisely, if the Weld recess is frustoconical, the central protruding portion that is defined by the step 22 may be of essentially the same dimension as the distal (upper in figure 7) end of the Weld recess 12. Preferably, the central protruding portion that is defined by the step 22 is at least as large as the distal end of the Weld recess 12. The central protruding portion should be of a sufficient size, should it be desired to connect (typically Weld) a conductor thereto.
The diameter central protruding portion that is defined by the step 22 may be 9 to 14 millimeters or preferably 10 to 12 millimeters. The diameter central protruding portion may correspond to 19 to 30, or 22 to 26 percent of the cell diameter.
The conductor Weld region 12W of the example of figure 7 may be least 3 millimeters across.
Preferably, the conductor Weld region 12W of the example of figure 7 measures 5 to 8 11 millimeters across. The diameter of the conductor Weld region 12W may correspond to 6 to 20 percent of the cell diameter, or preferably 12 to 20 percent of the cell diameter.
In some examples, the diameter d (denoted in figure 3) of the conductor Weld region 12W of figures 1 to 6 and 8, and thus of the Weld recess 12, may be 3 to 8 millimeters, preferably 5 to 8 millimeters. The diameter d may correspond to 6 to 20 percent of the cell diameter, or preferably 12 to 20 percent of the cell diameter. may be advantageous to provide a terminal rivet 1 that is relatively compact as measured along the longitudinal center axis. In the present examples, after riveting the axial extension or height (from the bottom to the top of the rivet) of the terminal rivet may be approximately 5 millimeters, or in the range of 3.5 to 7 millimeters. The height of the terminal rivet 1 may correspond to 8 to 15 percent of the cell diameter, or preferably 8 to 12 percent of the cell diameter. Typically, the terminal rivet may protrude 1.5 to 4 millimeters from the surface of the ,É[Kss]§[c1s6]1[WH7]§[WHs]enclosure Wall 52, Which may correspond to 3 to 9 percent of the cell diameter. It may be advantageous to provide a terminal rivet 1 that provides a (typically positive) terminal area of suff1cient size to facilitate connecting a conductor thereto. At the same time, the terminal rivet 1 should not be too large such that there is room for the other (typically negative) terminal that may surround the terminal rivet 1 (see figure 4).
In the present examples, the diameter of the terminal surface 2 of the terminal rivet 1 may be approximately 15 to 23 millimeters, preferably 17 to 20 millimeters. The present terminal rivet 1 may be arranged on a cell 50 of a diameter of approximately 46 millimeters. Thus, the diameter of the terminal surface 2 of the terminal rivet 1 may be approximately 33 to 50 percent of the cell diameter, or preferably 37 to 43 percent of the cell diameter.
A method of manufacturing a secondary cell 50 Will next be described. The method may involve the above-described terminal rivet 1. The method may be understood from figure 4 that illustrates at least two steps of the method, see boxes 110 and 120.
Importantly, the method comprises conductor Welding 110 (the step of Welding is indicated in figure 4) a rivet part 10 of a terminal rivet 1 to an intemal component 55 of the cell 50. The intemal component 55 may, as is disclosed, be a current collecting plate that in tum is electrically connected to an electrode assembly (not shown) inside the cell 50. The conductor 12 Welding 110 may comprise arranging a circular laser Weld to and through the rivet part 10 to attach the rivet part 10 to the internal component 55. Preferably, a number of circular laser Welds, such as two, three or four, are arranged. The number of circular laser Welds may be concentric. The conductor laser Welding may be performed at the above-described conductor Weld region 12W. The method further comprises cover Welding 120 a cover part 20 of the terminal rivet 1 to the rivet part 10 of the terminal rivet 1. The cover Welding 120 may comprise arranging at least one circular laser Weld to and through the cover part 20 to attach the cover part to the rivet part 10. The cover laser Welding may be performed at the above-described cover Welding region 20W, typically radially centrally Within said region 20W.
In some more detail, the method may comprise inserting the rivet part 10 through a terminal opening 54 in an enclosure Wall 52 of the cell 50. This step is performed prior to the conductor Welding 110. Typically, as mentioned, the rivet part 10 is electrically isolated from the enclosure Wall 52 by isolation means 30, such as a terminal gasket. The method may thus comprise positioning a terminal gasket 30 in the terminal opening 54 prior to inserting the rivet part 10. The method may further comprise deforrning the rivet part 10, i.e. performing riveting, to seal the terminal opening 54 and to fasten components, such as the current collecting plate 55, to one another. In detail, the deformation of the rivet part 10 may result in a deformation of the terminal gasket 30 such that a tight seal is obtained. A deforrned rivet part 10, more precisely a deforrned shaft portion 14 of the rivet part 10, is illustrated in figure 2. Next, the conductor Welding 110 may be performed. The method may further comprise positioning the cover part 20 on the rivet part 10 prior to the cover Welding 120.
Although specific terms may be employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation. Therefore, persons skilled in the art Would recognize numerous variations to the described examples that Would still fall Within the scope of the appended claims. As used herein, the terms "comprise/comprises" do not exclude the presence of other elements or steps. Furthermore, although individual features may be included in different claims (or examples), these may possibly advantageously be combined, and the inclusion of different claims (or examples) does not imply that a certain combination of features is not feasible and/or advantageous. In addition, singular references do not exclude a plurality. Finally, reference numerals in the claims are provided merely as a clarifying example and should not be construed as limiting the scope of the claims in any Way. 13

Claims (1)

1.CLAIMS A terminal rivet (1) for a secondary cell (50), the terminal rivet (1) comprising - a rivet part (10) comprising a Weld recess (12) through Which the rivet part (10) may be Welded and electrically connected to an internal component (55) of the secondary cell (50), and - a cover part (20) configured to be attached to the rivet part (10) to cover the Weld recess (12) of the rivet part (10). The terminal rivet (1) of claim 1, Wherein the rivet part (10) comprises a shaft portion (14) adapted to extend through an enclosure Wall (52) of the secondary cell (50) and a head portion (16) adapted to form an extemal terminal of the secondary cell (5 0). The terminal rivet (1) of claim 2, Wherein the rivet part (10) consists of the shaft portion (14) and the head portion (16). The terminal rivet (1) of any preceding claim, Wherein the Weld recess (12) comprises an open end that faces the cover part (20) and a closed end that comprises a conductor Weld region (12W). The terminal rivet (1) of claim 4, Wherein the conductor Weld region (12W) is at leastmillimeters across. The terminal rivet (1) of claim 4 or 5, Wherein the conductor Weld region (12W) is essentially circular. The terminal rivet (1) of claim 6, Wherein the diameter (d) of the conductor Weld region (12W) is at least 3 millimeters. The terminal rivet (1) according to any of claims 5 to 7, Wherein the material thickness (t) of the rivet part (10) at the conductor Weld region (12W) is selected to facilitate Welding there through, the material thickness (t) preferably being 0.5 to
1.5 millimeters. The terminal rivet (1) of any preceding claim, Wherein the rivet part (10) and the cover part (20) jointly forrn a terrninal surface (2) When the cover part (20) is attached to the rivet part (10), the rivet part (10) and the cover part (20) being configured such that the terrninal surface (2) is essentially flat. The terrninal rivet (1) of any preceding claim, Wherein the cover part (10) comprises a cover Welding region (20W) arranged radially extemally the Weld recess (12). The terrninal rivet (1) of any preceding claim, Wherein the cover part (20) comprises an internal cover portion (20i) and an external cover portion (20e), the internal cover portion (20i) protruding axially from the external cover portion (20e), and the rivet part (10) comprises an internal cover recess (18i) that is adapted to receive the internal cover portion (20i) and an external cover recess (18e) that is adapted to receive the external cover portion (20e). The terrninal rivet (1) of the preceding claim, Wherein the material thickness of the extemal cover portion (20e) is selected to facilitate Welding there through and the material thickness of the intemal cover portion (20i) exceeds the material thickness of the extemal cover portion (20e). The terrninal rivet (1) of any preceding claim, Wherein the Weld recess (12) is frustoconical. The terrninal rivet (1) of any preceding claim except claim 9, Wherein the cover part (20) axially lcovers the entire rivet part l[cB9]l[WH1o](10) and forms a terrninal surface (2) When attached to the rivet part (10). A secondary cell (50) comprising the terrninal rivet (1) of any preceding claim.
SE2350518A 2023-01-16 2023-04-28 A covered terminal rivet for a secondary cell and a method of manufacturing a secondary cell SE2350518A1 (en)

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