WO2016185452A1

WO2016185452A1 - Electrode plate assemblies and batteries comprising same

Info

Publication number: WO2016185452A1
Application number: PCT/IB2016/053005
Authority: WO
Inventors: Hing Po TSANG
Original assignee: Gp Batteries International Limited
Priority date: 2015-05-21
Filing date: 2016-05-23
Publication date: 2016-11-24

Abstract

A method of forming an assembly of an electrode plate (100) and a current collector (140), the electrode plate (100) having an active region comprising a layer of active material on a substrate plate (120); wherein the method comprises laser welding the current collector (140) to the electrode plate (100) while the active material is on the region to be welded.

Description

ELECTRODE PLATE ASSEMBLIES AND BATTERIES COMPRISING

SAME

Field

[001] The present disclosure relates to electrode plate assemblies, and more particularly to electrode-plate groups of batteries, and batteries or other devices comprising same.

Background

[002] Porous sheet materials are widely used in industries. For example, porous metal sheets such as foamed metal sheets are widely used in energy storage devices in the form of electrode plates. A foamed metal sheet has a higher porosity than its un-foamed counterpart. A higher porosity usually means a larger active surface area and more active substances can be charged and retained. Foamed metal sheets charged with active substances are widely used as electrode plates of rechargeable batteries or other energy storage devices such as capacitors. Foamed electrode plates are connected to the outside environment such as battery terminals via non-porous or solid conductors which are referred to as current collectors. The current collectors provide enhanced rigidity, strength and current density to facilitate battery operations.

[003] A conventional electrode plate assembly comprising a foamed metal sheet and a solid conductor connected by resistance welding is not entirely satisfactory in so far as electrical and mechanical performances are concerned. Summary

[004] An electrode plate assembly comprising an electrode plate and a current collector is disclosed. The electrode plate is a foamed electrode plate comprising a foamed or porous metal sheet or layer and the current collector is connected to the electrode plate by laser welding or a plurality of laser welded joints. An electrode plate assembly thus formed has substantially improved electrical and mechanical performances compared with its resistance welded counterpart.

[005] The foamed or porous metal layer may be compressed, partially compressed or not compressed at locations of laser welding. The porous metal sheet or layer which forms the foamed electrode plate is substantially un-deformed or un-distorted outside the locations of laser welding or outside the locations of the laser welded joints.

Figures

[006] The disclosure and embodiments will be described by way of example with reference to the accompanying Figures, in which: Figure 1 is a schematic diagram depicting an example electrode plate assembly according to the present disclosure,

Figure 2 is a cross-sectional view taking in a longitudinal direction extending along the welding locations on the electrode plate assembly of Figure 1 ,

Figure 3 is an SEM (scanning electron microscope) picture showing a welded junction on the electrode plate assembly of Figure 1 ,

Figure 4A is a schematic diagram depicting a side view of an electrode plate assembly according to the present disclosure,

Figure 4B is a schematic diagram depicting a side view of another example electrode plate assembly according to the present disclosure,

Figure 5 depicts a battery electrode plate group comprising example electrode plate assembly according to the present disclosure,

Figure 6 depicts an example electrode plate group assembly according to the present disclosure,

Figures 6A-6B show example intermediate steps to form the example battery electrode plate group of Figure 6,

Figure 6C is a longitudinal cross sectional view of the example battery electrode plate group of Figure 6 taken along an axis extending along a center line of the current collector cap,

Figure 6D is an enlarged view on a top portion of the example battery electrode plate group Figure 6C, and

Figure 7 is a schematic view depicting a partially wound electrode plate group of Figure 6A. Description

[007] An example electrode plate assembly 100 depicted in Figure 1 comprises a foamed metal sheet 120 and a conductor strip 140. The foamed metal sheet 120 and the conductor strip 140 are connected by laser welded joints 160. The foamed metal sheet is a porous metal sheet and the conductor strip 140 is a solid strip of metal. The solid conductor strip 140 provides enhanced strength, rigidity and/or current density to facilitate electrical and mechanical interfacing between the electrode plate and outside. The conductor strip 140 is joined with the foamed metal sheet 120 by laser welding.

[008] In the example of Figure 1 , the laser welded portion of the conductor strip 140 has a length of about 9-10 mm, a width of about 3.5mm, and 6 welded locations distributed along the length of the welded portion of the conductor strip 140. Of course, the actual dimensions are application and/or requirements dependent. [009] The conductor strip 140 and the foamed metal sheet 120 are in close contact or physical abutment along the length of the laser welded portion 130, as depicted in Figure 2,. The welded conductor strip 140 substantially retains its original or pre-welded shape and there is no noticeable bulging or deformation along the length where laser welded locations present, compared to bulging and deformation which are noticeable on conventional welded counterparts such as resistively welded counterparts. The four laser welded joints depicted in Figure 2 are arranged along the length of the laser welded portion 130.

[0010] Referring to Figure 3, substantial fusion or diffusion between the conductor strip 140 and the foamed metal sheet 120 is revealed in the welded region. In the microstructure image of Figure 3, the foamed elements or portions of the foamed metal sheet 120 project away from the conductor strip 140 and appear as hairy elements. The bases of the hairy elements are substantially integrated or fused with the surface of the conductor strip 140, evidencing substantial fusion or diffusion between the conductor strip 140 and the foamed metal sheet 120. The hairy appearance of the foamed elements projecting from the junction where the conductor strip 140 joins with the foamed metal sheet 120 suggests that the foamed metal sheet retains a higher degree of porosity after such joining or integration.

[001 1] A comparison of the mechanical and electrical characteristics of the laser welded assembly and its resistively welded counterpart is set out in Table 1 below.

Table 1

[0012] The table above shows substantial improvement in mechanical strength and resistance, as well as a substantially higher density of welding spots or welding joints. For example, an improvement of a 12% decrease in resistance, an improvement of a 17% increase in mechanical strength, and 3 times more welding spots in the same length to enhance distributed welding strength have been resulted. For example, the welded region can have a welding density of up to four, for example, one, two or three welding joints, per mm according to the disclosure. [0013] In an example electrode plate assembly as depicted in Figure 4A, the foamed metal sheet 222 is formed with coating 220 on both surfaces of the foamed metal sheet 222. The coating 220 comprises active materials which are filled inside pores of the porous foamed sheet 222. The conductor strip 240 is laser welded to the foamed metal sheet 222. After welding, the conductor strip 240 is in close contact or physical abutment with the foamed metal sheet 222 along the length of the laser welded portion, with its inner surface oppositely facing the foamed metal sheet 222, or more exactly the upper surface of the foamed metal sheet 222. The conductor strip 240 is seated on the foamed metal sheet 222 and is in a groove or channel delineated by the coating 220. The coating 220 cooperate to define a pair of delineating walls which extends along the length of the conductor strip 240 to define the groove or the channel in which the conductor strip 240 seats. The delineating walls are on two lateral sides of the conductor strip 240 along its length and each delineating wall is oppositely facing and proximal to a corresponding lateral side of the conductor strip 240. The conductor strip 240 after laser welding includes a lower surface which is in abutment with the foamed metal sheet 222 and an upper surface which faces away from the foamed metal sheet 222. The lower surface is underneath the upper surface of the coating 220 which define the groove or the channel in which the conductor strip 240 seats. The conductor strip 240 is laser welded to the foamed metal sheet 222 and its lateral sides are proximal or in abutment with the coating 220. In an example, the separation between the conductor slip 240 and a corresponding grove delineating wall is around 0.2mm. In some embodiments, the conductor strip 240 is laser welded to the foamed metal sheet 222 without prepressing of the foamed portion. This results in delineating walls which extend or project upwardly from the substrate in an orthogonal or substantially orthogonal manner.

[0014] In an example electrode plate assembly as depicted in Figure 4B, the foamed metal sheet 322 is formed with coating 320 on both surfaces of the foamed metal sheet 322. The foamed metal sheet 322 and the coating 320 are substantially identical to that of Figure 4A. In this example, the foamed metal sheet 322 is prepressed to define a groove or a channel to house the conductor strip 340 before laser welding. As depicted in Figure 4B, the groove or a channel is wider than that of Figure 4A and the separation between the conductor slip 240 and a corresponding grove delineating wall is larger. In the example, the separation is about 2 mm compared to the around 0.2mm in the example of Figure 4A.

[0015] The electrode plate assembly according to the present disclosure may form the electrode plate group of a battery.

[0016] A battery typically comprises an electrode plate group which is received inside a non- conductive container. An electrode plate group is also referred to as an 'electroplate group' herein for brevity. The non-conductive container is filled with an electrolyte and active regions of the electrode plate group are immersed inside the electrolyte so that electrochemical reactions can take place inside a reaction chamber filled with electrolyte. The electrolyte is also referred to as 'battery liquid'. An electrode plate group of a battery is an assembly comprising a positive electrode plate, a negative electrode plate, and an insulating separator. Each electrode plate has a current collector attached to it to facilitate current transport. The current collectors are then connected to main battery terminals as is known in the art.

[0017] In general, each electrode plate comprises an active region and an inactive region. The active region of each electrode plate is coated with active substances, and the electrode plates are arranged such that the active regions of the positive and negative electrodes are aligned in an oppositely facing manner separated by the insulating separator sheet. During battery charging or discharging, electrochemical reactions will take place on the corresponding active regions of the electrode plates in the presence of the electrolyte. The inactive region of each electrode plate is primarily a lead portion which is for current collection when discharging and for current distribution when charging.

[0018] For a NiMH rechargeable battery, the electrode plate typically comprises a Nickel foamed substrate. The active region of a positive electrode plate is typically coated with Nickel hydroxide as the main active substance. The active region of the negative electrode plate is typically coated with a hydrogen absorbing alloy as the active substance. The separator is usually a polymer sheet such as a polypropylene sheet.

[0019] The active region of the positive electrode plate of the battery comprises a nickel- foamed metal sheet coated or mixed with nickel hydroxide. The active region of the negative electrode plate comprises a nickel or nickel-plated punched metal sheet coated with negative electrode constituting materials which are typically a hydrogen-absorbing alloy. The electrode plates are typically very thin sheets to reduce material costs and weight, since the electrochemical reactions involved in battery charging and/or discharging is primarily surface in nature. Usually, only the active areas are coated with active substances to maximize cost benefits. The active areas of an electrode plate are primarily the regions on the electrode plate which overlap or substantially overlap with adjacent electrode plates of the opposite polarity.

[0020] The lead portions of the positive and negative electrode plates are connected respectively to the positive and negative current collectors. Each of the current collectors is made of a good electrical conductor, and is usually made of nickel, nickel-plated copper, or steel for good thermal and electrical conductivity. The positive and negative current collectors are in turn connected to the positive and negative battery terminals. [0021] In some embodiments, the electrode plate assemblies according to the present disclosure are group to form an electrode plate group of a battery.

[0022] In some examples, the assembly is formed into a stack of electrode plates with the insulating separator sheet intermediate the positive and negative electrode plates so that there is electrical insulation between electrode plates of opposite polarity. A current collector is joined to a corresponding electrode plate and current collectors of the same polarity are joined together and connected to a battery terminal of the battery.

[0023] In some embodiments, the electrode plate group is wound into a coiled electrode plate group for fitting into a cylindrical metal can to form a cylindrical battery, as depicted in Figure 5. In the example battery electrode plate group of Figure 5, the positive electrode plate comprised a foamed metal sheet and the current collector protrudes from the coiled electrode plate group for making external connection.

[0024] There is disclosed an electrode plate assembly comprising an electrode plate and a current collector, wherein the electrode plate includes a layer of active material on a substrate plate to define an active region, and the current collector includes an elongate electrode plate contact surface which is in abutment with the electrode plate and intermediate the active region of the electrode plate; and wherein the electrode plate contact surface of the current collector is physically and electrically connected to the electrode plate by a plurality of laser welded joints, the laser welded joints being distributed along the length of the electrode plate contact surface and intermediate the active region.

[0025] The electrode plate assembly may be part of a battery or other devices such as capacitors.

[0026] The electrode plate contact surface may be delimited by two longitudinal edges and the two longitudinal edges of the electrode plate contact surface is in abutment or edge aligned with the first and second active regions of the electrode plate. The laser welded joints may be distributed along the longitudinal direction. The electrode plate contact surface may be in physical and electrical contact with the active material on the substrate plate.

[0027] The active region may be highly porous and the active material between the current collector and the substrate plate is less or non-porous or has a higher density that the active material in the active region.

[0028] The current collector and the electrode plate may be in abutment or in physical contact between adjacent welding joints.

[0029] Portions of the electrode plate contact surface between adjacent welded joints may be planar or substantially planar. [0030] The electrode plate may be wholly covered with the active material outside the electrode plate contact surface.

[0031] The active material may comprises nickel hydroxide.

[0032] The current collector may be embedded in a channel defined between the first and the second active regions.

[0033] The electrode plate may have a foamed outer surface covered with the active material.

[0034] There is disclosed a battery comprising an electrode plate group, wherein the electrode plate group comprises an assembly of an electrode plate and a current collector disclosed herein.

[0035] The battery may be a NiMH (nickel metal hydride battery).

[0036] A method of forming an assembly of an electrode plate and a current collector is disclosed. The electrode plate includes a layer of active material and the current collector includes an elongate conductor strip which is to form an electrode plate contact surface in abutment with the electrode plate. The active material may be in foamed form on a substrate plate or formed as a foamed sheet. The layer of active material may include an active region. The elongate conductor strip is intermediate the active region of the electrode plate and laser welded.

[0037] The method comprises:

- delineating a reception region on the electrode plate, the reception region being intermediate the active region and has a boundary closely following the outline of the conductor strip contact surface;

positioning the electrode plate contact surface such that the electrode plate contact surface is aligned with the boundary of reception region and in abutting contact with the reception region under pressure; and

applying laser welding to physically and electrically connect the electrode plate contact surface and the conductor strip with a plurality of laser welded joints, the laser welded joints being distributed along the length of the conductor strip contact surface.

[0038] The method may comprise forming a reception channel in the reception region before applying laser welding, the reception channel having a channel bed delineated between a first edge of the first action region and a second edge of the second active region, and placing the current collector such that the conductor strip contact surface is in abutting contact with the channel bed and with a first longitudinal edge of the current collector oppositely facing the first edge and a second longitudinal edge of the current collector oppositely facing the second edge.

[0039] The method may comprise applying laser welding while the active material is on the reception region.

[0040] The method may comprise compressing the active material in the reception region to define the reception region.

[0041] The method may comprise placing the current collector in the reception region with its free edges embedded between active materials before laser welding.

[0042] An example electrode plate group assembly 600 depicted in Figure 6 comprises a coiled electroplate group sub-assembly 630 and a current collector 640. The current collector 640 is a metal plate comprising an end cap portion 642 and an elongate lead portion 644. The electroplate group sub-assembly 630 comprises a positive electrode plate 632, a negative electrode plate 636, and a separator plate 634 which is intermediate the positive electrode plate 632 and the negative electrode plate 636 to provide electrical insulation there-between. The positive electrode plate is a foamed metallic plate as a substrate which is treated with active substances. The positive electrode plate 632, the negative electrode plate 636 and the separator are formed into a stack and are then wound into the coiled electroplate group sub-assembly 630, as depicted in Figures 6A and 7. The electrode plate group assembly 600 is formed by connecting the end cap portion 642 to an axial end of the coiled electroplate group sub-assembly 630 while the coiled electroplate group sub-assembly 630 is held firmly in its coiled shape. More specifically, the coiled electrode plate group 600 is formed by laser welding the end cap portion 642 to the positive electrode plate 632 with the elongate lead portion 644 projecting away therefrom in a direction orthogonal to coiling axis.

[0043] As depicted in Figures 6, 6A and 6B, the end cap portion 642 of the current collector is laser welded to a first axial end of the coiled positive electrode plate 632 with an end cap contact surface orthogonal to the coil axis. The end cap portion 642 of the current collector is laser welded to the positive electrode plate 632 with laser welding spots 662 distributed along a spiralled path following and above the spiral track of the coiled positive electrode plate 632. Where the end cap portion 642 is laser welded to the positive electrode plate 632, fusion and/or diffusion will occur at the laser welding spots connecting the foamed or porous metal of the positive electrode plate 632 and the end cap portion 642 of the current collector.

[0044] The orthogonal disposition relationship between the end cap contact surface and the first axial end of the coiled positive electrode plate 632 means that the end cap contact surface of the current collector is or can be in contact with the entire length or a substantial portion of the length of the coiled positive electrode plate 632. The lengthwise contact relationship means many more laser welding spots 662 can be formed along a free edge of the positive electrode plate 632 to improve connection reliability and to decrease total junction resistance to enhance power performance. The negative electrode plate 636 is axially retracted from the end cap contact surface to provide insulation spacing between the end cap contact surface and the negative electrode plate 636. As shown in Figures 6D and 7, a lengthwise free edge of the negative electrode plate 636 proximal the end cap contact surface is axially retracted from the end cap contact surface and axially retracted from a corresponding lengthwise free edge of the positive electrode plate 632.

[0045] The coiled electrode plate group 600 is to be fitted into a cylindrical metal can to form a cylindrical battery.

[0046] In some embodiments, direct electrical contact between the coiled negative electrode plate 636 and the metal can is formed by friction fitting.

[0047] Where electrical contact between the coiled negative electrode plate 636 and the metal can is formed by friction fitting or friction contact, the negative electrode plate 636 may be the outermost surface of the coiled electroplate group sub-assembly 630 so that the coiled outer surface of the negative electrode plate 636 is in friction contact with the inner surface cylindrical surface of the metal can to form a negative battery terminal.

[0048] Alternatively or additionally, electrical contact between the coiled negative electrode plate 636 and the metal can may be formed by urging an axial end of the coiled negative electrode plate 636 against a second axial end of the metal can which is distal from the first axial end of the coiled positive electrode plate 632.

[0049] In some embodiments, electrical contact between the coiled negative electrode plate 636 and the metal can is formed at a second axial end of the coiled electroplate group subassembly 630 distal from a first axial end where the end cap 640 is laser welded.

[0050] Where electrical contact between the coiled negative electrode plate 636 and the metal can is formed at the second axial end of the coiled electroplate group sub-assembly 630, the electrical contact may be by friction contact or through a welded intermediary.

[0051] Where a welded intermediary is used, the intermediary may be a metal plate which is welded to the second axial end of the coiled electroplate group sub-assembly 630, whether by laser welding or resistive welding.

[0052] Where there is electrical connection between the coiled negative electrode plate 636 and the metal can at the second axial end, the positive electrode plate 632 is axially retracted from the contact surface at the second axial end to provide insulation spacing between the contact surface at the second axial end and the positive electrode plate 632. In example embodiments, a lengthwise free edge of the positive electrode plate 632 proximal the contact surface at the second axial end is axially retracted from the contact surface at the second axial end and axially retracted from a corresponding lengthwise free edge of the negative electrode plate 636.

[0053] In some embodiments, the separator plate 634 is folded at an axial end proximal the end cap portion and extends radially to insulate the corresponding free axial end of the negative electrode plate 636 from positive current collector as defined by the end cap.

[0054] Similarly, the electrode plate of Figures 6, 6A-6B might include a layer of active material on a substrate plate to define an active region, and the current collector might include a racket shaped electrode plate contact surface having its circular portion to be in abutment with lateral edge of the electrode plate and is not necessarily intermediate the active region of the electrode plate; and wherein the electrode plate contact surface of the current collector is physically and electrically connected to lateral edge of the electrode plate by a plurality of laser welded joints 662, the laser welded joints being distributed along the width or about the central axis of the coiled electrode plate group. In other words, the laser welded joints may be distributed along the transversal direction.

[0055] As can be seen from sectional views of Figures 6C-6D, positive and negative electrode plates 632, 636 and separator sheet 634 are wound about the central axis of the battery electrode plate group, such that the laser welded joints between the current collector of respective electrode plates are correspondingly distributed and spaced evenly along the width or the transversal direction of the electrode plate group and also distributed about the central axis thereof.

[0056] Referring to Figure 6D, at the upper portion of the electrode plate group there is a first step/spacing/distance (d) between the lateral end surface of positive electrode plate 632 and the lateral end surface of the negative electrode plate 636. Similarly, there might be a second step between the lateral end surfaces of the negative electrode plate 636 and the positive electrode plate 632 at the lower portion of the electrode plate group. The provision of the first step and/or the second step might prevent the deterioration of the separator sheet during the laser welding between the current collector and respective electrode plates.

[0057] In some embodiments, a further method of forming an assembly of an electrode plate and a current collector is disclosed.

[0058] The method comprises:

- winding the electrode plate into a coiled electrode plate group having a central axis and a coiled upper lateral edge/contact surface and a coiled lower lateral edge/contact surface, positioning the current collector having an electrode plate contact surface such that the electrode plate contact surface covers and being in abutting contact with respective coiled lateral edges/contact surfaces of the electrode plate group; and applying laser welding to physically and electrically connect the respective lateral edges/contact surfaces of the electrode plate and the current collector with a plurality of laser welded joints, the laser welded joints being distributed along the width of the electrode plate contact surface and/or about the central axis of the coiled electrode plate group.

[0059] The upper lateral edge/contact surface may be that of a coiled positive electrode plate or a coiled negative electrode plate. The current collector may be in the form of an end cap having an electrode plate contact surface which is to approach and abut the coiled positive electrode plate or the coiled negative electrode plate in a direction orthogonal to the coiling axis. Laser welding may be applied spirally following the spiral track of the coiled positive electrode plate or the coiled negative electrode plate.

[0060] A foam metal sheet herein has a PPI of 30 or above. PPI is a unit representing porosity and the number associated with the unit indicates the number of cells or pores per inch. Typical foamed metal sheets used in batteries have a typical thickness of between 0.5mm and 3.0mm, a typical porosity of between 95 and 420 PPI. Copper (Cu), zinc (Zn), nickel (Ni), nickel alloy, antimony (Sb), lead (Pb), cobalt (Co), iron (Fe) and palladium (Pd) are commonly metals suitable for forming foamed metal sheets.

[0061] While the disclosure has been described herein with reference to examples, the examples are not intended and should not be used to limit the scope of disclosure.

Claims

1. An electrode plate assembly comprising an electrode plate and a current collector, wherein the electrode plate is a foamed electrode plate comprising a foamed or porous metal layer and the current collector is connected to the electrode plate by laser welding or by a plurality of laser welded joints.

2. An electrode plate assembly according to Claim 1 , wherein the foamed or porous metal layer is compressed, partially compressed or not compressed at locations of laser welding.

3. An electrode plate assembly according to Claims 1 or 2, wherein the foamed or porous metal layer is fused with the current collector at locations of laser welding.

4. An electrode plate assembly according to any preceding Claim, wherein there is fusion or diffusion of the foamed or porous metal layer and the current collector at locations of laser welding.

5. An electrode plate assembly according to any preceding Claim, wherein the current collector is in abutment and/or in close contact with the foamed or porous metal layer in a direction extending along locations of laser welding and between adjacent locations of laser welding.

6. An electrode plate assembly according to any preceding Claim, wherein the current collector is substantially straight and/or flat and un-deformed in a direction extending along locations of laser welding and between adjacent locations of laser welding.

7. An electrode plate assembly according to any preceding Claim, wherein the current collector includes an exposed surface which faces away from the electrode plate and an inner surface which faces towards the electrode plate, the inner surface being in abutment and/or in close contact with the foamed or porous metal layer along locations of laser welding.

8. An electrode plate assembly according to any preceding Claim, wherein thickness at locations of welding is in the region of 1 mm, including 0.6mm, 0.8mm, 1.2mm or 1.4mm.

9. An electrode plate assembly according to any preceding Claim, wherein separation of adjacent locations of laser welding is below 2 mm, including below 1.5mm, further including below 1 mm, even further below 0.5mm.

10. An electrode plate assembly according to any preceding Claim, wherein junction resistance due to said laser welding is lower than junction resistance of a counterpart welded by resistance welding, including 10% lower or 12% lower.

1 1. An electrode plate assembly according to any preceding Claim, wherein junction strength due to said laser welding is higher than junction strength resistance of a counterpart welded by resistance welding, including 10% higher, further including 15% higher and even further including 17% higher in strength.

12. An electrode plate assembly according to Claim 1 , wherein the electrode plate comprises a coating layer on both surfaces of the foamed or porous metal layer, the coating layer is removed along locations of laser welding so that laser welding is between the foamed or porous metal layer of the electrode plate and the current collector.

13. An electrode plate assembly according to any preceding Claim, wherein the electrode plate is in form of a coiled plate having a lateral edge defining a coiled end plane and the current collector is laser welded over the lateral edge and/or covering completely or partially the coiled end plane of the electrode plate with a plurality of laser welded joints.

14. An electrode plate assembly according to Claim 13, wherein the coiled plate has a central axis and the laser welded joints are distributed radially along the coiled end plane and/or about the central axis of the coiled plate.

15. An electrode plate group comprising an electrode plate assembly according to any preceding Claim.

16. A battery or capacitor comprising an electrode plate group of Claim 15.

17. A method of forming an electrode plate assembly, wherein the electrode plate assembly comprises an electrode plate and a current collector, and the electrode plate comprises a foamed or porous metal layer; and wherein the method comprises laser welding the current collector and the electrode plate to form the electrode plate assembly by laser welding.

18. A method of forming an electrode plate assembly according to Claim 17, further comprising a step of winding the electrode plate into a coiled electrode plate having a coiled lateral contact surface.

19. A method of forming an electrode plate assembly according to Claim 18, further comprising a step of positioning the current collector having an electrode plate contact surface such that the electrode plate contact surface covers and being in abutting contact with the lateral contact surface of the electrode plate.

20. A method of forming an electrode plate assembly according to Claims 18 or 19, further comprising a step of laser welding the lateral contact surface of the electrode plate and the current collector with a plurality of laser welded joints, and the laser welded joints are distributed along a coiled end plane defined by the coiled lateral contact surface and/or about a central axis of the coiled electrode plate.