The present invention relates to lead-acid battery electrode manufacture, including an improved method and apparatus for forming a connection (particularly an electrical, or mechanical connection, or both), to a fibre material, for use as an electrode.

BACKGROUND OF THE INVENTION

In a cell or battery, the positive electrode or electrodes, the negative electrode or electrodes, or both, may be formed of one or more layers of fibre material with a connector or lug (herein generally referred to as lug). The present invention has been described herein sometimes with reference to electrodes of lead-acid (Pb-acid) batteries but may also have application to other battery types such as Li-ion batteries, and in other applications such as in electrodes in solar cells, or in capacitors or supercapacitors, for example.

In a lead-acid battery or cell comprising a fibre electrode (or electrodes), such as a knitted, woven, non-woven fabric, for example (but not exclusively) a glass fibre, a carbon fibre, a PAN fibre, an OPF fibre, a low electrical resistance is desireable between the fibre electrode material and a lug to the external circuit. Similarly, it is desirable that a mechanically durable connection is formed between the fibre electrode material and lug.

To enable fast high-volume manufacture of multiple electrodes, some form of continuous lug forming process is preferable.

In our previous process (US 10,476,069) we describe a continuous pressure impregnation process that provides a lug to a fibre sheet material.

In this specification, where reference has been made to external sources of information, including patent specifications and other documents, this is generally for the purpose of providing a context for discussing the features of the present invention. Unless stated otherwise, reference to such sources of information is not to be construed, in any jurisdiction, as an admission that such sources of information are prior art or form part of the common general knowledge in the art.

For the purpose of this specification, where method steps are described in sequence, the sequence does not necessarily mean that the steps are to be chronologically ordered in that sequence, unless there is no other logical manner of interpreting the sequence.

It is an object of the present invention to provide a method and/or apparatus for forming a connection or lug on or to a fibre materialthat overcomes or at least partially ameliorates some of the abovementioned disadvantages or which at least provides the public with a useful choice.

BRIEF DESCRIPTION OF THE INVENTION

The invention comprises a method and apparatus for forming a connection to a fibre material electrode element, which comprises moving a length of the fibre material continuously, or in steps, through an apparatus that casts a molten lug material into a lug zone part of the fibre material to surround and/or penetrate fibres of the fibre material and form a lug strip in the lug zone.

It is preferred that the fibre material has a length of at least 1 metre, although it is anticipated that many meters will be processed at a time, according to the length of the fibre material available on a roll.

The preferred product is a fibre material with a lug strip along a length of the fibre material and having a width less than a width of the fibre material, comprising a continuous impregnation of a lug material into the fibre material surrounding and/or penetrating and electrically connecting to the fibres of the fibre material as shown in Figure 9.

The lug strip may be formed at or near a length-wise edge of the fibre material and comprising a lug extension beyond an edge of the fibre material. Alternatively, the lug strip may be formed at or near opposing length-wise edges of the fibre material and comprising a lug extension beyond the edges of the fibre material.

Alternatively still, the lug strip may be formed at or near opposing lengthwise edges of two sheets of fibre material arranged side by side (in substantially the same plane), and later separated by dividing or cutting.

Alternatively still, the lug strip may be formed at or near opposing length-wise edges of the same sheet of fibre material, and later separated by dividing or cutting.

Additionally the apparatus/method of the invention may be used to increase the tensile strength of the fibre material along the fibre materials length and width making it stronger than it would otherwise be without.

According to a first aspect the invention broadly comprises an apparatus for continuously forming an electrical and/or mechanical connection to a fibre material electrode element comprising: a casting cavity having an upper and lower surface to define a casting zone, a supply of sheet fibre material having a casting edge, said supply of sheet fibre material supplying fibre material continuously to the casting zone between the upper and lower surfaces and said casting edge further definings the casting cavity, a head supplying molten lead/lead alloy immediately at an upstream extent of the casting zone, wherein said upper and lower surfaces move continuously with said fibre material.

According to another aspect the upper and lower surfaces are counter rotating with respect to one another. According to another aspect the movement of said upper and lower surfaces in said casting zone assist movement of said fibre sheet material through said apparatus.

According to another aspect the upper and lower surfaces are substantially stationary with respect to each other at least in said casting zone.

According to another aspect the upper and lower surfaces are substantially stationary with respect to said fibre sheet material at least in said casting zone.

According to another aspect one of the upper and lower surfaces are a movable continuous belt rotating around at least an upstream roller and a downstream roller.

According to another aspect the apparatus comprises a rotating drum and said casting cavity is formed between an outer peripherial surface of said drum, and a movable continuous belt wrapped and overlying the drum cavity at least in a casting zone, such that the casting cavity is closed in the casting zone by the belt.

According to another aspect one of said upper and lower surface is defined by said rotating drum, and the other of said upper and lower surface is defined by said continuous belt.

According to another aspect at least one drum includes a cutout adapted to receive the fibre sheet such that a pair of lateral edges of said casting cavity are sealed by said at least one cutout on one edge and by said fibre material on another edge.

According to another aspect the open casting cavity on the rotating drum includes closing walls at each side edge, such that the cavity is open only in a tangential direction.

According to another aspect the apparatus further comprises a lead roller adapted to press the continuous belt onto the drum at a upstream extent of the casting zone. According to another aspect the apparatus further comprises a trailing roller adapted to hold the continuous belt a distance from the drum at a downstream extent of the casting zone.

According to another aspect the drum is driven by a drum drive, and the continuous belt is moved by contact with the drum.

According to another aspect the apparatus comprises a pair of rotating belts and said casting cavity is formed between said belts at least in the casting zone, such that the casting cavity is closed in the casting zone by respective upper and lower surfaces of the belts.

According to another aspect at least one of said belts includes a cutout adapted to receive the fibre sheet such that a pair of lateral edges of said casting cavity are sealed by said cutout on one edge and by said fibre material on another edge.

According to another aspect at least one of said belts includes a cutout adapted to receive the fibre sheet such that a pair of lateral edges of said casting cavity are each sealed by said cutout, such that the cavity is open only in a direction normal to a face of the belt.

According to another aspect a divider strip is located between said belts, at least in said casting zone to close an edge of said casting cavity.

According to another aspect said divider strip moves with said upper and lower surfaces.

According to another aspect said divider strip is stationary.

According to another aspect the lower surface is defined by a lower rotating drum, and the upper a surface is defined by an upper drum.

According to another aspect said apparatus further comprises a second supply of sheet fibre material having a casting edge, said supply of sheet fibre material supplying fibre material continuously to the casting zone between the upper and lower surfaces such that the two fibre material sheets, are arranged side by side in the same plane.

According to another aspect the casting edge of the first sheet fibre material is spaced from the casting edge of the second sheet fibre material.

According to another aspect a head supplies molten lead substantially across an entire width of the casting cavity to join said first and second sheets of fibre material.

According to another aspect said apparatus further comprises a cutting element, located downstream of said casting zone to separate said first and second fibre material sheets parallel to said casting edges.

According to another aspect the head supplies molten lead substantially across an entire width of the casting cavity.

According to another aspect the apparatus further comprises at least one heating block adapted to heat at least a leading portion of the casting zone.

According to another aspect the apparatus further comprises a cooling block adapted to extract heat at least from a trailing portion of the casting zone.

According to another aspect the apparatus further comprises a cooling system to extract heat from the casting zone.

According to another aspect the head has a tip shaped to correspond with an entry shape of the casting zone defined by leading portions of the upper and lower moving surfaces.

According to another aspect the invention comprises a method employing the apparatus of any one of the previous claims, comprising: forming a casting cavity between said upper and lower moving surfaces, supplying a fibre sheet material to said casting cavity, supplying a molten lug material to said sheet material while in said casting cavity, allowing said molten material to cool sufficiently, to form a longitudinal lug along said fibre sheet, and withdrawing said sheet.

According to another aspect said method includes a plurality of casting cavities spaced across a width of the fibre material, so as to form multiple lugs.

According to another aspect said lugs are edgewise.

According to another aspect the invention comprises the method or apparatus of the previous clauses, wherein the fibre material is moved: a. continuously, or b. in a stepped movement.

According to another aspect the fibre material is moved at a speed between approximately 10 mm/s and approximately 600 mm/s.

According to another aspect the invention comprises the method or apparatus of the previous clauses, wherein if present: a. the belts are of a high strength steel material, b. The drum of of a steel material, and/or c. The head is of a steel, ceramic, or graphite material.

According to another aspect the invention comprises the method or apparatus of the previous clauses, wherein : a. molten lead is supplied by said head at a temperature between approximately 350°C to 450°C, b. drum cooling is provided by circulating a cooling liquid through the drum, or Other aspects of the invention may become apparent from the following description which is given by way of example only and with reference to the accompanying drawings.

Definitions

In this specification :

• 'lug' means any electrically conductive element or connector which enables external electrical connection of the fibre electrode or of the active material paste within the fibre electrode or both.

• 'lug region' and 'lug zone' are used interchangeably and have the same meaning, being the part of a fibre electrode covered by a lug (or lugs)

• 'matrix' in relation to a lug refers to lug material encapsulating the conductive or non-conductive fibre material in the lug zone in a 3- dimensional structure that has length, width and depth.

• 'Snout' means a lead dispensing head shaped to substantially correspond to the upstream entry region of the casting zone, in order to improve sealing

As used herein the term "and/or" means "and" or "or", or both.

As used herein "(s)" following a noun means the plural and/or singular forms of the noun.

The term "comprising" as used in this specification and claims means "consisting at least in part of". When interpreting statements in this specification and claims which include that term, the features, prefaced by that term in each statement, all need to be present but other features can also be present. Related terms such as "comprise" and "comprised" are to be interpreted in the same manner.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described by way of example only and with reference to the drawings in which: Figure 1 is a schematic view of a fibre material electrode manufacturing apparatus having a drum and belt running over the drum surface forming a continuous casting cavity.

Figure 2 is a cross sectional view of the fibre material electrode manufacturing apparatus of Figure 1 showing the casting cavity and injection head.

Figure 3 is another cross sectional view of a fibre material electrode manufacturing apparatus showing the casting cavity including an optional crush zone, and injection head.

Fig ure 4 is a schematic close-up side view of a drum, showing a heating plate

Figure 5 is another cross sectional view of the fibre material electrode manufacturing apparatus of Figure 1 showing the casting cavity and injection head.

Figure 6 is a schematic view of a fibre material electrode manufacturing apparatus having a pair of belts running against one another forming a continuous casting cavity.

Figure 7 is a cross sectional view of the fibre material electrode manufacturing apparatus of Figure 6 showing the casting cavity and injection head.

Figure 8 is another cross sectional view of the fibre material electrode manufacturing apparatus of Figure 6 showing the casting cavity and injection head.

Figure 9 is a close-up view of a fibre sheet with lug on edge.

Figure 10 is a schematic view of a fibre material electrode manufacturing apparatus having a pair of drums forming a continuous casting cavity.

Figure 11 is a cross sectional view of the fibre material electrode manufacturing apparatus of Figure 10 showing the casting cavity and injection head.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

General

In a battery, typically a lead-acid battery, the positive electrode or electrodes, the negative electrode or electrodes, or both, may be formed with a lug in accordance with the method(s) and/or apparatus of the invention. Preferably the current collector material or the electrode framework and the fibres thereof are flexible, which will assist in accommodating volume changes of the active material attached to and/or retained by the current collector material or electrode framework during battery cycling, and the microscale fibres may also reinforce the active material or paste, both assisting to reduce breaking off ("shedding") of active material from the electrode in use.

Electrode fibre material

The electrode framework or current collector material comprises a network suitable to provide form to the active material or paste to retain the same within the framework. In at least some embodiments the framework is provided with interconnected interstices and/or spaces. In at least some embodiments the electrode framework comprises a foam. In at least some embodiments the electrode framework may be a woven material, a knitted material, or a non-woven material, such as a felt, or a fluid hydro-entangled material, or a bonded fibre material whether woven, knitted or non-woven. The material may comprise filaments extending in a major plane of the material with each filament composed of multiple fibres, with optionally connecting threads extending transversely across the filaments to mechanically connect the filaments.

In at least some embodiments the electrode framework comprises a fibrous material, such as a carbon fibre, an oxidised pan fibre (OPF), glass fibre, silicon carbide fibre or alumina fibre material, that may or may not be a non-conductive material.

The fibre material may be a woven material (comprising intersecting warp and weft fibres), a knitted material, or a non-woven material such as a fluidentangled material and/or a felt material or knitted carbon fibre material. Preferably the fibrous material has been hydro-entangled.

Preferably the fibrous material has been needle punched. Preferably the bulk density of the fibrous material is about 0.05g/cm ³ to 0.2g/cm ³ , or about 0.07 to 0.17g/cm ³ or about 0.08 to 0.15g/cm ³ . The material typically has an average interfibre spacing between fibres in the fibre material of between about 1 and about 5 average fibre diameters and/or less than about 250 microns and in some embodiments less than about 200, less than about 100 microns, less than about 50 microns, less than about 20 microns, or less than about 10 microns. Alternatively, the material has an amount of cylindrical surface of fibres per unit volume of electrode 10 ³ to 10 ⁶ m ² /m ³ . The fibre diameter may be in the range from about 1 micron to about 30 microns, from about 4 microns to about 20 micron, from about 5 microns to about 15 microns. In some embodiments, the average fibre diameter is less than about 20 microns. The voidage in the unimpregnated fibre material may be at least about 93% for example, to about 94% for example, or to about 95% for example, or to about 95% for example, or to about 97% for example, or to about 98% for example, or to about 99% for example. Typically the fibrous material has length and width dimensions in a major plane of the material and an average thickness perpendicular to said major plane of the material, which may be for example about 0.2mm or about 1mm and/or less than 5 mm or less than 3mm or less than 2mm. Felt or other non-woven planar electrode material may be produced to very low thickness such as for example 2.5 mm or less. In at least some embodiments the fibrous material comprises filaments of average length in the range of greater than 2cm.

The fibre material may have a thickness (transverse to a length and width or in plane dimensions of the electrode) many times such as about 10, 20, 50, or 100 times less than the, or any, in plane dimension of the electrode. The thickness may be less than about 5 mm or less than about 3mm or less than about 2mm or about or less than about 1mm or about 0.2 mm for example. Each of the in plane length and width dimensions of the electrode may be greater than about 50 mm or about 100mm for example. Such electrodes have a planar form with low thickness. In preferred forms the electrode is substantially planar and has a dimension from a metal lug for external connection along at least one edge of the electrode equal to or less than about 1000 mm, or less than about 800 mm, or less than about 600 mm, or less than about 500 mm, or less than about 200 mm, or less than about 150mm, or less than about 100 mm or less than about 70 mm, or less than about 50 mm, or about 30 mm or less for example (with or without a macro-scale current collector). Alternatively such a planar form may be formed into a cylindrical electrode for example.

The fibre material may comprise any fibre material that can survive in an acid battery environment, such as a carbon fibre material, a glass fibre material, such as a woven or knitted or non-woven or fluid-entangled or felted fabric or needle felted fabric, such as for example an Oxidised Polyacrylonitrile (PAN) fibre (OPF) or glass fibre or silicon based fibrous material. The fibres, for example, carbon fibres, are typically multifilamentary for woven fabrics but may be monofilament. Non-woven materials with random fibre entanglement and intersections may be advantageous over woven materials with regular intersections of warp and weft fibres at right angles. Suitable carbon fibre material may comprise or be derived from rayon, polyacrylonitrile, phenol resin, or pitch materials or lignin. The average depth of the bulk material may be at least 0.2 millimetres or at least 1 millimetre. At least a majority of the fibres have a mean fibre diameter of less than about 20 microns, or less than about 10 microns.

The fibre sheet material and the fibres thereof may be flexible, which will assist in accommodating volume changes of the active material attached and/or retained to the fibre material during battery cycling, and the microscale fibres may also reinforce the active material, both properties assisting to reduce breaking off ("shedding") of active material from the electrode in use.

Continuous lug manufacture

In accordance with the invention, to enable fast and/or high volume manufacture of muliple electrodes, continuous fibre material is preferably unwound from a roll, preferably of many metres of the material for example, is moved continuously or at least with a stepped movement, through a casting cavity.

In preferred configurations, the casting cavity is temporarily formed by movable (preferably upper and lower) surfaces, through which the fibre sheet material 2 is passed, or moves through, and while within the casting cavity, a molten lug material is introduced, which solidifies upon cooling to form an edgewise lug (and/or in some configurations a longitudinal lug partway between edges of the fibre material, and/or both), that subsequently emerges, at least partly solidified, from the continuous casting cavity.

In the most preferred configurations, the movable (preferably upper and lower) surfaces defining at least part of the casting cavity are arranged in an endless configuration such that they can be continuously cycled. In preferred configurations, the upper and lower surfaces defining the casting cavity are counter rotating.

For example, with reference to figures 1-5 a schematic lug forming apparatus 1 is shown. In this configuration, a rotating drum 4 is provided, and as will be described in more detail later, an outer peripheral surface of drum 4 defines a lower surface of a casting cavity 8. In particular, the casting cavity 8 is defined within cavity cutout 10 in the surface of the drum, within which the fibre material 2 is received.

Movable tensioned belt 7 is provided to wrap around at least a portion of the outer peripheral surface of drum 4. With particular reference to figure 1, tension rollers 18, 5 and 6 are provided to guide belt 7. For example, leading tension roller

5 is located immediately upstream of the casting cavity 8 (see fig 3) and positions the belt 7 on the outer peripheral surface of drum 4. Similarly, trailing tension roller

6 is positioned downstream of the casting cavity 8, and it will be appreciated that this configuration causes belt 7 to wrap around the outer periphery of drum 4, in the region between tension rollers 5 and 6.

As is also shown in figure 1, additional rollers 18 may be included in order to provide tension and/or allow the belt 7 to act continuously against a section of the outer peripheral surface of drum 4.

In some configurations, the leading tension roller 5 and/or trailing tension roller 6 are preferably pressed against drum 4. In other configurations, the leading roller 5 and/or trailing roller 6 may be spaced slightly from drum 4. It will be appreciated that in all preferred configurations, the belt 7 will be wrapped around at least a portion of the outer peripheral surface of drum 4. Preferably, the belt 7 is pulled against the face of the drum 4 (between the leading roller 5 and the trailing roller 6) in order to tightly engage with the drum.

In the preferred drum configurations, the outer peripheral surface of drum 4 includes a cutout 10, for example a circumferential slot, such that a casting cavity 8 is formed between a cutout 10 and the tensioned belt 7. The casting cavity 8 is best shown in the cross-sectional views of figures 2 and 3. In particular, with reference to figure 3 it can be seen that the belt 7 is pressed against an outer peripheral portion 23 of drum 4 (between the edge of the drum 4 and the cutout edge 11), thereby sealing the edge of the casting cavity 8.

With particular reference to figure 2, cutout 10 can be seen in the outer surface of drum 4. Casting cavity 8 can be seen formed in cutout 10 between the outer peripheral surface of rotating drum 4, and the tensioned belt 7. As further shown in figure 2, tension belt 7 wraps around an outer peripheral edge 23 of drum 4, on an edge beyond the casting cavity 8, in order to form an effective seal preventing molten lug material from escaping from casting cavity 8. With further reference to figures 2 and 3, it can be seen that cutout 10 also defines a cutout edge surface 11, which defines an outer edge of casting cavity 8.

It will be appreciated that as the drum 4 and belt 7 move continuously against each other, in the region where belt 7 is wrapped around drum 4, the open cutout 10 is closed by tensioned belt 7 and a continuous casting cavity 8 is defined. The extent to which belt 7 wraps around drum 4, defines the effective length of continuous casting cavity 8, which needs to be sufficiently long, for a given speed, to allow molten lug material to solidify sufficiently before exiting the casting cavity 8 (as a continuous belt 7 leaves contact with the drum 4). It is been found that only the outer surfaces of the molten material may need to solidify (i.e. part of the core may remain molten), in order to allow the lug to exit the casting cavity and maintain its dimensional stability and/or desired surface uniformity. Alternatively, it is envisaged that the drum 4 could be rotated in a stepwise fashion, in order to provide enough 'dwell time' to allow the molten material to solidify sufficiently.

Compared to previously known continuous lug to fibre electrode casting methods, the present configurations allow a comparatively longer casting cavity to be formed, thereby allowing a significantly higher feed rate of the fibre material sheet 2 to be passed through the apparatus 1, as the molten lug material solidifies. Accordingly, a higher production rate is provided. It is envisaged that to further improve the feed rate and/or uniform solidification of the molten lug material, cooling or cooling blocks may also be utilised adjacent the casting cavity in order to extract heat and/or to stablise the temperature of the apparatus and/or system. Such cooling blocks may be cooled using, for example a hot water/glycol mixture (or oil or any other suitable liquid) which is circulated through the interior of the block.

For example, typically the molten lead is introduced into the casting cavity at approximately 400° C, and accordingly all surfaces in contact with the molten lead material that are at a lower temperature will assist it to cool. In particular, it may be desirable/necessary to heat the cooling blocks (to a temperature lower than 400° C, but above ambient temperature), in order to effectively control the cooling rate of the lead. In this sense, the terms "cooling" and/or "cooling block", should be understood in terms of how those elements affect the rate at which the molten material cools.

Accordingly, the top and bottom of the casting cavity 8 are defined by the belt 7 and drum 4 respectively, while the outer edge of the casting cavity (in some embodiments on each side of drum 4) is defined by cutout edge surface 11.

In order to form lug 3 on one or both edges of the fibre material 2, the sheet of fibre material 2 is fed between drum 4 and belt 7, with one or both edges passing through a respective casting cavity 8. It will be appreciated that in some configurations the edge region of the fibre material 2 effectively 'seals' the inner edge of casting cavity 8 (opposite edge surface 11) particularly once impregnated with solidifying molten lug material.

In some configurations (for example as shown in figure 3), an inner edge of casting cavity 8 is defined by a raised section 12. If present, raised section 12 provides a compression zone 19 to the fibre sheet material, that can assist in controlling the penetration of molten lug material into the edge of the fibre material sheet 2, by compressing the fibre material sheet 2.

It will be appreciated that the above-described configurations provide a continuous casting cavity 8 located at least on an edge region of fibre material sheet 2. Accordingly, injector head 9 is provided at a leading edge of casting cavity 8, in order to introduce molten lug material under pressure to the casting cavity 8. As the molten lug material solidifies, an effective seal is formed toward the downstream edge of the casting cavity 8 preventing molten material escaping at one end, as the molten material is introduced at the other. In preferred embodiments, it has been found that injecting molten material under pressure from a gravitational head is sufficient. Alternatively, however it may be advantageous to inject molten material under higher pressure. Similarly, the injector head 9 is preferably shaped to substantially correspond with the shape of the upstream entry region to the casting cavity 8, defined by the leading roller 5 and belt 7 together with the outer peripheral surface of drum 4. This 'snout' arrangement is best shown in the cross sectional view of figure 5.

In some configurations the head 9 includes a number of injection ports 14, in order to more evenly introduce molten lug material into the casting cavity 8. As shown particularly in Figure 5, the tip 24 of the head 9 is quite small, as the height of the casting cavity 8 is also small. For example, the casting cavity may be from less than 1 mm thick, to several millimetres thick for example 5 mm.

In some configurations, the head 9 may be manufactured from graphite, or alternatively steel. An advantage of a graphite head 9 is the potential to eliminate a need for lubricant, while an advantage of the steel head 9 is strength, particularly as a steel head may also be surface treated (e.g. nitrided).

In preferred configurations, the head 9 is gently pressed against the drum 4 and felt 7 to ensure a good fit. For example, the head 9 may be actuated in and out (approximately along a machine direction) via a suitable actuator such as an air cylinder, linear actuator etc. Further, movement of the snout shaped head 9 may be useful to aid cleaning and/or servicing etc. Alternatively, injector head 9 may be spaced a small distance from the belt and/or drum, and still provide an effective seal.

With reference to figure 9 a fibre material sheet 2 is shown including lug 3 formed with a lug strip 3 along a length of the fibre material and having a width less than a width of the fibre material. This fibre material sheet 2 was formed by continuous impregnation of a lug material (lead) into the fibre material surrounding and/or penetrating and electrically connecting to the fibres of the fibre material along an edge as shown in Figure 9.

In order to begin the lug forming process, the apparatus 1 may be run with or without a leader on start up. If running without a leader the fibre material sheet 2 can be pulled through to sit on the drum 4 just before the belt 7. When starting the apparatus the fibre sheet 2 will run through underneath the belt before the head 9 comes into position. That is the fibre sheet 2, is pulled through by contact between both the belt 7 and the drum 4. In some configurations, grip can be enhanced by roughening the outer surface of the drum 4 (for example by abrasive blasting). The start of the run can then be cut off and the fibre material 2 attached to a spool for winding as normal.

Alternatively, if running with a leader on the fibre materal 2, the process is substantially as described above, however the fibre material is manually run through the apparatus for a few meters so it can be attached to the spool for winding. Subsequently, the run can be started and processed as normal.

In some configurations, rotating drum 4 is driven by a suitable motor 25 and control system, while contact between drum 4 and belt 7 drive the belt 7. In alternative configurations, the drive motor may be associated with belt 7, or both the belt 7 and drum 4. In the most preferred configurations, movement between the belt 7 and drum 4 is synchronised such that they do not slip with respect to each other (at least in the region of the casting cavity).

It will be appreciated that movable belt 7 may be tensioned by an additional moving pulley and movable actuators as is generally known in the art. Similarly, the belt 7 may be guided by flanges and/or additional adjustable pulleys as is also generally known.

With particular reference to figure 4, a heating block 13 may be provided in order to provide more even heat to the apparatus. In some preferred configurations, a heating block may be provided to directly heat the back side of the belt, and may also be useful for supporting the belt. For example one or more heater blocks 13 may be provided, including one or more cartridge heaters, in order to warm up the belt(s) relative to ambient temperature. Without additional heating, the belt 7 may be heated unevenly due to the molten lug material being introduced at specific locations (e.g. only at the edges), which may cause the belt to distort and/or warp. Additional targeted heating and/or cooling may be provided to ensure a more even temperature distribution as required. Further, cooling may be provided in the drum in order to extract heat. For example, using a hot water/glycol mixture (or oil or any other suitable liquid) which is circulated through the interior of the drum in order to extract heat from the drum surface.

With reference to figures 6-8 a schematic alternative lug forming apparatus 1 is shown. In this configuration, many elements are essentially shared with the previously described configuration that included rotating drum 4. In this alternative configuration, the lower casting surface is provided by an additional belt 15 arranged to contact belt 7, and between them form casting cavity 8. As shown, additional belt 15 runs on corresponding leading roller 5' and trailing roller 6'. It is anticipated that additional rollers and/or tension rollers may be included in order to further define the path of one or both of these endless belts 7, 15.

In this configuration, belts 7 and 15 also counter rotate with respect to one another. As with the previous configuration, a driving motor 25 may be provided to one of the belts in order to rotate it, while the other may be driven indirectly via contact between the respective belts/rollers. Alternatively, each belt may be driven separately. The driver(s) of the belts are preferably synchronised such that there is little or no relative movement between belts 7 and 15, at least in the casting cavity or casting zone, in order to define a continuous casting cavity 8.

It will be appreciated that the spacing between the leading and trailing rollers of respective belts 7 and 15 where they overlap, will determine the length of the casting cavity 8. As with the previous configuration, this length can be varied according to the requirements of the process such that the molten lug material solidifies sufficiently prior to exiting casting cavity 8. In some configurations it may be desirable to include a backing support block 20 between the leading and trailing rollers in order to provide a support block surface 20 adjacent the moving belts 7 and/or 15, in order to assist the casting cavity 8 to remain dimensionally stable against the pressure injected molten lug material. Further, cooling may be provided in backing support block(s) 20 in order to extract heat. For example, using a hot water/glycol mixture (or oil or any other suitable liquid) which is circulated through the block 20. An advantage of cooling being incorporated into support blocks 20, is that both faces of the lead strip (casting cavity) are called, resulting in more rapid cooling overall which, may enable higher production speeds to be achieved.

As in the previously described example, one or more heater blocks may be provided, including one or more cartridge heaters, at appropriate locations.

In the preferred twin belt configurations, the respective belts 7, 15 are preferably spaced apart in the casting zone, in order to define the upper and lower (movable) surfaces of casting cavity 8. It will be appreciated that the spacing distance will be chosen to accommodate the required thickness of fibre material sheet 2, and the thickness dimension of the formed lug 3. Movement of the rollers 5,6 and /or 5', 6', can easily achieve different spacings as required.

Alternatively, one or both of the twin belts 7,15 may comprise a series of discrete rigid blocks, articulated to form a chain to allow continuous motion around rollers. In such embodiments the blocks provide additional mass to aid with uniform temperature and cooling (heat extraction), although a high dimensional tolerance between adjacent blocks is required otherwise any gaps may allow 'flash' (molten metal seeping between blocks) to appear, causing defects in the finished surface.

As with the previously described configuration, it is important that the casting cavity 8 is effectively sealed against leakage of the injected molten lug material on all boundaries. As with the previous configuration, the upper and lower movable surfaces define the main boundaries of the casting cavity. Similarly, the fibre material sheet 2, (particularly once impregnated with solidifying molten lug material) effectively seals the trailing edge boundary, while the injecting head seals the leading edge boundary. As shown in figures 7 & 8 head 9 is provided at a leading edge of casting cavity 8, in order to introduce molten lug material to the casting cavity 8. Similarly, the head 9 is preferably shaped to substantially correspond with the shape of the upstream entry region to the casting cavity 8, defined by the leading rollers 5, 5' and the respective belts 7 & 15. This arrangement is best shown in figure 8.

In some configurations the head 9 includes a number of injection ports 14, spaced across the width of the casting cavity 8, in order to evenly introduce molten lug material into the casting cavity 8. As shown particularly in Figure 8, the tip of the head 9 is quite small, as the height of the casting cavity 8 is also small. For example, the casting cavity may be from less than 1 mm thick, to several millimetres thick, for example 5 mm.

In order to seal the lateral edges of the casting cavity 8, additional sealing belts (edge dams) 16, 17 are preferably provided (one at each side for configurations where the sheet fibre material 2 is intended to include a lug 3 on each edge as shown in figure 6). As shown in the figures, belt 16 (and 17 if present) run between the counter rotating belts 7, 15 that form the upper and lower movable surfaces of the casting cavity 8, in order to provide outer lateral edges to the casting cavity 8, as is best shown in figure 7. In preferred configurations, the vertical thickness of belts 16, 17 substantially correspond to the height of the casting cavity 8, and/or the spacing between movable belts 7, 15.

The sealing belts 16, 17 are preferably mounted on appropriate rollers, and may include additional tension rollers if required. These belts 16, 17 maybe driven together, or independently and are preferably synchronised with the motion of movable belts 7, 15, such that little or no relative motion occurs at least in the region of the casting zone within casting cavity 8. Alternatively, belt 16, 17 may be moved via contact with movable belts 7 and/or 15.

With reference to figures 10 and 11 a further alternative apparatus 1 configuration will now be described. In this configuration, some elements are shared with the previously described configuration that included rotating drum 4. In this alternative configuration, the upper casting surface is provided by an additional drum 21 arranged adjacent drum 4, and between them form casting cavity 8. As previously described, fibre sheet material 2 is introduced into the casting cavity 8 and runs between the adjacent drums 4, 21, which are spaced apart to define a thickness of the casting cavity 8. Alternatively, it is anticipated that one or both rotating drum 4, 21, may include a cutout (substantially as described first described configuration), in order to provide an appropriate thickness to the casting cavity 8.

As in the previously described configurations, it is anticipated that further heating blocks and/or cooling blocks 20 may be necessary in order to effectively control the solidification process as the molten material exits casting cavity 8. It would also be appreciated in this twin drum configuration that the drums 4, 21, may be relatively larger (compared to the previous configurations) in order to provide a 'longer' casting cavity 8 in the machine direction MD. For example, the diameter of drums 4, 21 may be approximately from around 500 mm to over 2 meters, in order to provide comparable production speeds.

In this configuration, the leading edge seal of the casting cavity 8 is provided by the head 9, and the trailing edge seal is provided by the fibre material 2 and the solidifying molten lead exiting the casting cavity 8, substantially as previously descri bed.

In order to seal the edges of the casting cavity 8, edge dams 22 may be provided as shown in figure 10. These edge dams may provide a stationary flat plate that makes contact with the edge of the drums 4,21 and head 9. Alternatively, the edge dams 22 may be formed integrally with the injection head 9.

With particular reference to the above-described 'twin drum' configuration, it is anticipated that an alternative preferred configuration may provide drums 4, 21 side by side (horizontally). In such a configuration, the fibre sheet 2 product, with cast-on lugs 3, emerges downwards. Accordingly, gravity may assist the casting process. While not shown specifically, the configuration is essentially that shown in figure 11, but rotated 90° in an anticlockwise direction.

It has been found that fibre material sheet 2 having lug(s) 3 cast on one or both edges with apparatus 1 according to the described configurations, results in significantly higher production rates, more consistent product runs with less wastage, almost complete elimination of flash, and/or an improved surface consistency of cast lug 3.

In some embodiments the impregnating lug material is a metal. In one embodiment the metal is Pb or a Pb alloy (herein both referred to inclusively as Pb). In another embodiment the metal is a Zn or a Zn alloy (herein both referred to inclusively as Zn). In another embodiment the metal is Cd or a Cd alloy (herein both referred to inclusively as Cd). In another embodiment the metal is Al or a Al alloy (herein both referred to inclusively as Al). Alternatively the impregnating lug material may be a polymer material such as a conductive polymer for example.

The belts 7,15 are preferably of a high strength steel or alloy with a low rate of thermal expansion, for example approximately 0.25mm thick 17-7 CH-900 steel.

Typically during battery or cell construction the fibre material is impregnated with a paste, which in a preferred form comprises a mixture of Pb and PbO particles of Pb and PbO and a fluid. In some embodiments the fluid is water, an acid or an alcohol. Preferably the acid is dilute sulfuric acid. Preferably the alcohol is ethanol. Alternatively the paste may comprise lead sulphate (PbSO4) particles and dilute sulphuric acid. The Pb-based particles may comprise milled or chemically formed particles which may have a mean size of 10 microns or less, small enough to fit easily into spaces between the fibres. The paste or active material may fill the fibre electrode up to the lug so that the active material contacts or abuts the lug where the fibre enters the lug and electrically connects direct to the lug, not only at the surface of the fibre material on either side but also through the thickness of the fibre material, and along a major part of or substantially all the length of the boundary between the lug material and the non-lug material impregnated fibre material at this boundary. In a preferred embodiment the lug is formed so as to have protrusions of the lug such as Pb protrusions, into the active material impregnated into the carbon fibre material, as described above.

To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention are envisioned without departing from the scope of the invention as defined in the appended claims.

This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more of said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.