Patent Publication Number: US-2022238856-A1

Title: Battery carbon fiber electrode making machine and method

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This patent application is a divisional of, and hence claims the benefit of, U.S. patent application Ser. No. 16/823,754, with a filing date of Mar. 19, 2020, entitled “BATTERY CARBON FIBER ELECTRODE MAKING MACHINE AND METHOD,” which is herein incorporated by reference in its entirety. 
    
    
     INTRODUCTION 
     A variety of different types of batteries have electrodes of a carbon fiber material connected to a lead conductor. There is a need for a way to cost effectively mass produce electrodes of a carbon fiber material attached to a lead conductor. 
     The present invention relates generally to battery electrodes of a carbon fiber material and more particularly to a machine for and method of making battery composite electrodes with a carbon fiber material electrically connected with a lead conductor. 
     SUMMARY 
     In an embodiment, a process of making a composite battery electrode may involve several steps. One step includes providing a longitudinally elongate strip of an electrically conductive carbon fiber material. Another step includes casting an electrically conductive lead or lead alloy ribbon with a continuous flow of liquid lead or lead alloy along and attached to a longitudinally elongate portion of the strip of carbon fiber material. Yet another step includes severing the strip of carbon fiber material with the attached ribbon into a plurality of electrodes, each electrode with a portion of the carbon fiber material having a portion of the ribbon attached thereto. 
     In an embodiment, a process of making a composite battery electrode may involve several steps. One step includes unwinding a longitudinally elongate strip of an electrically conductive carbon fiber material for engagement of the strip of carbon fiber material with a rotatable drum. Another step includes supplying liquid lead or lead alloy to a cavity of the rotatable drum via a shoe residing in complementary mating confrontation with a portion of a periphery of the rotatable drum. The liquid lead or lead alloy is supplied at a longitudinally elongate portion of the strip of carbon fiber material and establishes a solidified electrically conductive lead or lead alloy ribbon at the longitudinally elongate portion of the strip of carbon fiber material. Yet another step includes retaining a portion or more of the strip of carbon fiber material on the rotatable drum via a plurality of spaced apart grippers disposed on the rotatable drum. 
     In an embodiment, a process of making a composite battery electrode may involve several steps. One step includes unwinding a longitudinally elongate strip of an electrically conductive carbon fiber material for engagement of the strip of carbon fiber material with a rotatable drum. Another step includes supplying liquid lead or lead alloy to a cavity of the rotatable drum via a shoe. The liquid lead or lead alloy establishes a solidified electrically conductive lead or lead alloy ribbon at a longitudinally elongate portion of the strip of carbon fiber material. Yet another step includes retaining a portion or more of the strip of carbon fiber material on the rotatable drum via a multitude of spaced apart spikes disposed on the rotatable drum. And another step includes forcing a portion or more of the strip of carbon fiber material into engagement with the spikes as the rotatable drum is rotated. Another step includes limiting a generally axial extent to which liquid lead or lead alloy is supplied in the cavity of the rotatable drum by way of a rib. Yet another step includes severing the strip of carbon fiber material with the solidified electrically conductive lead or lead alloy ribbon into a multitude of composite battery electrodes. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following detailed description of preferred embodiments and best mode of a method and machine for making battery electrodes of a carbon fiber material connected to a lead or lead alloy conductor will be set forth with reference to the accompanying drawings in which: 
         FIG. 1  is a fragmentary plan view of a longitudinally elongate composite strip of a carbon fiber material with a lead conductor ribbon attached along each elongate edge of the strip of carbon fiber material; 
         FIG. 2  is a fragmentary plan view a longitudinally elongate composite strip of a carbon fiber material with a lead conductor ribbon attached along each elongate edge of the strip with equally spaced apart locator holes through each lead ribbon; 
         FIG. 3  is a fragmentary plan view of a longitudinally elongate composite strip of a carbon fiber material with a lead conductor ribbon attached along each elongate edge of the strip with lugs of each lead ribbon; 
         FIG. 4  is a side view of a machine for casting a lead ribbon attached along one or both edges of an elongate strip of carbon fiber material; 
         FIG. 5  is an end view of the machine of  FIG. 4 ; 
         FIG. 6  is a semi-schematic perspective view of a device for unwinding a roll of an elongate strip of carbon fiber material and feeding it onto the drum of the machine of  FIG. 4 ; 
         FIG. 7  is a semi-schematic side view with portions broken away of the device of  FIG. 6 ; 
         FIG. 8  is a plan view of a portion of a periphery of a casting drum of the machine of  FIG. 4 ; 
         FIG. 9  is an enlarged view of the portion within the circle A of  FIG. 8 ; 
         FIG. 10  is an enlarged fragmentary sectional view taken on line B-B of  FIG. 9 ; 
         FIG. 11  is an enlarged fragmentary sectional view taken on line C-C of  FIG. 9 ; 
         FIG. 12  is an enlarged fragmentary sectional view taken on line D-D of  FIG. 9 ; 
         FIG. 13  is a front view of a shoe of the machine of  FIG. 4 ; 
         FIG. 14  is an end view of the shoe of  FIG. 13 ; 
         FIG. 15  is an enlarged fragmentary sectional view taken on line E-E of  FIG. 13 ; 
         FIG. 16  is an enlarged fragmentary top view of the shoe of  FIG. 13 ; and 
         FIG. 17  is a semi-schematic enlarged fragmentary sectional view of the shoe confronting the drum of the machine  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring in more detail to the drawings,  FIG. 1  illustrate a longitudinally elongate composite strip  20  of electrically conductive carbon fiber material  22  with a longitudinally elongate electrically conductive cast lead or lead alloy ribbon  24  (hereinafter lead ribbon) attached to each longitudinal edge  26  of the carbon fiber material.  FIG. 2  illustrates the elongate composite strip  20  with locator indicia desirably in the form of uniformly longitudinally spaced apart holes  28  in each lead ribbon. These holes  28  may be formed when casting the lead ribbon or after the lead ribbon has been cast to the carbon fiber material  22  such as by punching the holes through each lead ribbon.  FIG. 3  illustrates the elongate composite strip  20  in which each lead ribbon  24 ′ includes equally longitudinally spaced apart lugs  30  which may be formed either when casting the lead ribbons or by stamping, punching, severing or otherwise cutting away portions of each cast ribbon  24  to form the lugs thereof. To form individual electrodes  32  of carbon fiber material with a lead ribbon attached along one edge, all forms of the elongate strip may  20  be severed longitudinally as indicated by the broken line  34  and transversely as indicated by broken lines  36 . Alternatively, a composite longitudinally elongate strip may be formed with a lead ribbon along only one longitudinal edge of a strip of carbon fiber material and severed transversely to form a plurality of individual electrodes  32 . 
     Typically, each lead ribbon may have a nominal thickness in the range of about 0.030 to 0.080 of an inch and a transverse width in the range of about 1.2 to 2.0 inches. The carbon fiber material may have a thickness in the range of about 0.030 to 0.180 of an inch and for automotive batteries a transverse width of about 6 to 12 inches and desirably 8 to 10 inches if lead ribbons will be attached along both longitudinal edges and a transverse width in the range of about 3 to 6 inches if a lead ribbon will be attached along only one longitudinal edge. For stationary batteries the carbon fiber material may have a transverse width in the range of about 6 to 12 inches where a lead ribbon is attached along only one longitudinally elongate edge. Typically, the carbon fiber material may include a variety of electrically conductive carbon or graphite fibers (hereinafter both referred to as carbon fiber material) which may be several hundred feet in length and sufficiently flexible that they may be coiled into rolls. Suitable elongate strips of carbon fiber material commonly referred to as carbon fiber felt are commercially available. 
     A suitable method of making carbon fiber electrodes  32  includes casting liquid lead or a liquid lead alloy into an electrically conductive lead ribbon  24  along one or both edges  26  of a longitudinally elongate strip of carbon fiber material  22  to produce a composite strip  20  and thereafter severing the carbon fiber material and attached lead ribbon or ribbons to form a plurality of individual electrodes  32 . Depending on the desired application and downstream processing of the composite strip  20 , each lead ribbon may have locator holes  28  and/or lugs  30  either cast therein or subsequently formed by various punching, stamping, cutting, shearing, and/or severing operations which remove portions of the cast lead ribbon to form the locator holes in and/or lugs of the cast lead ribbon. 
       FIGS. 3 and 4  illustrate a machine  40  for continuously casting a conductive lead or lead alloy ribbon  24  attached along one or both edges  26  of a longitudinally elongate strip  22  of carbon fiber material. The machine may include a frame  42  on which a casting drum  44  is journaled for rotation by a motor  46  which is desirably a variable speed electric motor drivingly connected with the drum such as by a suitable belt  48  or chain. Portions of a longitudinally elongate strip  22  of a carbon fiber material may be received on the drum  44  and the drum may have a cavity  50  ( FIGS. 8-10 ) for casting a continuous lead ribbon or ribbons  24  respectively attached to one or both longitudinally extending edges of the carbon fiber strip of material. As shown in  FIGS. 6 and 7 , a roll  52  of the carbon fiber material may be unwound and disposed on the rotating drum  44  by a uncoiling device  54 . In operation of the machine  40 , liquid lead is supplied through a shoe  56  to a proportion of a cavity(s)  50  to cast and attach a lead ribbon or ribbons  24  along one or both longitudinal edge portions of the carbon fiber strip  22  of material. Liquid lead under pressure may be supplied from a lead pot  58  of a melting furnace  60  by a pump  62  through a conduit  64  to an inlet of the shoe  56  with excess liquid lead returned to the lead pot through a return conduit  66 . Typically, the liquid lead may be supplied to the shoe  56  by the pump at a super-atmospheric pressure and a temperature in the range of about 700 to 1,100 degrees F. On a peripheral portion of the drum  50  generally opposite the shoe  56  there may be a series of thermostatically controlled water spray nozzles  68  for maintaining the outer peripheral surface of the drum at a predetermined desired temperature in the range of about 200 to 400 degrees F. The composite strip  20  of carbon fiber material with a lead ribbon or ribbons attached thereto is removed from the drum as a longitudinally elongate continuous composite strip  20  which may thereafter be severed into individual electrodes. 
     For retaining a portion of the carbon fiber strip  22  of material on the drum  44  while the lead ribbon or ribbons  22  are cast thereon, as shown in  FIGS. 8 and 9 , a plurality of circumferentially and axially spaced apart spikes  72  are disposed circumferentially continuously around peripheral surface  74  of the drum. As shown in  FIG. 11 , each spike may project substantially radially outward of the peripheral surface  74  of the drum typically on the order of about 0.04 to 0.06 of an inch and be tapered at an included angle typically in the range of 10 to 20 degrees and desirably about 15 degrees relative to its axis to a relatively sharp point at its distal end. In operation of the machine, these spikes  72  extend into the strip of carbon fiber so that it does not move relative to the drum while the lead ribbon or ribbons  22  are cast thereon. As shown schematically in  FIGS. 6 and 7  the unwinding device  54  disposes succeeding portions of the carbon fiber strip  22  onto the drum  44  and into engagement with the spikes  72 . This unwinding device  54  may include an arbor  76  on which a roll  52  of the strip  22  of carbon fiber material may be rotatably received, a guide band  78  for directing portions of the strip as it is unrolled onto the rotating drum, and rollers  80  for forcing the strip onto the spikes  72  as it passes between the rollers and the rotating drum. Desirably the rollers  80  extend transversely across the entire width of the strip and are journaled to freely rotate in response to rotation of the drum  44  and the advancement of the carbon fiber strip  22  onto the drum. Of course, persons of ordinary skill may readily devise other devices for applying successive portions for a strip  22  of a carbon fiber material onto the rotating drum  44  and into engagement with the spikes  72 . 
     For casting each lead ribbon  24 , the drum  44  may have a separate cavity  50  recessed in and extending circumferentially continuously around the peripheral surface of the drum. In the drawings only one cavity  50  for casting one lead ribbon  24  along one longitudinal edge  26  of a carbon fiber strip  22  is shown, and will be described in detail. However, for making a composite strip  20  with a lead ribbon  24  attached to each longitudinal edge  26  of a carbon fiber strip two separate cavities  50  may be provided each adjacent to and somewhat underlapping one of the longitudinal edges  26  of the strip  22  of carbon fiber. The cavity underlaps and may also overlap an adjacent edge portion  26  of the carbon fiber material and desirably has an axial end provided by a circumferentially continuous rib  82  or raised portion which tends to limit the generally axial extent to which liquid lead flows into and around the edge portion  26  of the carbon fiber strip. To at least some extent, the liquid lead penetrates into an edge portion of the carbon fiber material extending into the cavity and when solidified attaches or secures the lead ribbon to the carbon fiber materials and provides an electrically conductive path or conductor for the carbon fiber material. In at least some instances the liquid lead may saturate at least part of the edge portion of the carbon fiber material. 
     Desirably to cast a lead ribbon  24  having a sinuous surface with a plurality of circumferentially spaced apart and transversely extending cogs or grooves, the cavity  50  may have a plurality of circumferentially spaced apart and axially extending bars or lands  84  in the cavity and disposed completely around the cavity. As shown in  FIG. 12 , each land  84  extends generally radially outward of the base of the cavity and may have a height or extent less than the depth of the cavity so that the outer face  86  of each land is disposed radially below or inboard of the peripheral surface  74  of the drum. The generally axial outer edge  88  of the cavity is desirably axially outboard of the adjacent end of the lands  84 . The serrated, sinuous or cogged surface of each lead ribbon ensures that when solidified and while the ribbon is still being carried by the rotating drum  44 , it does not move or shift generally circumferentially with respect to the portion of the strip  22  of carbon fiber on the drum to which it is joined or attached and after removal from the drum it may facilitate further downstream processing of the elongate composite strip  20  such as for advancing the strip or web through a die for punching locator holes, forming lugs on of the lead ribbons, pasting the composite strip, cutting or severing the composite strip into individual battery electrodes, etc. 
     In operation of the machine  40 , liquid lead is continuously supplied to the cavity  50  of the rotating drum  44  through the shoe  56 . As shown in  FIGS. 13 and 14  the shoe  56  has an arcuate outer face  90  for complimentary mating engagement with a portion of the periphery of the drum  44 . The shoe  56  may supply liquid lead to each cavity  50  of the drum with a continuous flow of liquid lead through a separate orifice  92  opening through the arcuate face  90  of the shoe. Desirably the orifice  92  may have two outlet openings  94  &amp;  96 , slightly spaced apart from each other. The openings  94  and  96  may have a generally rectangular configuration and the opening  96  may be elongate and disposed longitudinally generally parallel to the axis of rotation of the drum. Typically, the opening  94  of the orifice through the face  90  has an axial extent in the range of about 0.15 to 0.25 and desirably about 0.18 of an inch and in assembly overlies an edge portion  26  of the strip  22  of carbon material. The opening  96  of the orifice may have an axial extent in the range of about 1.0 to 1.04, desirably about 1.03 of an inch and in assembly overlies the cavity  50  in the drum  44 . Both openings of the orifice may have a circumferential extent in the range of about 0.2 to 0.3 and desirably about 0.25 of an inch and may be axially separated by about 0.12 of an inch. As shown in  FIGS. 15 and 17  liquid lead may be supplied under pressure to both a passage  98  extending generally axially through the shoe  56  and through a tube  106  received in the passage. The passage  98  may open onto the orifice outlet openings  94  &amp;  96  through a passage  102  defined by tapered walls around the periphery of the orifice. Desirably the orifice passage  102  has axial end walls  104  tapered or inclined at an included angle of about 35 degrees and side walls  96  tapered or inclined at an included angle of about 20 degrees relative to a radius of the arcuate face extending through the orifice as shown in  FIG. 15 . The passage  98  extends through the shoe and in cross section ( FIG. 15 ) has a generally circular portion  108  which adjacent its upper edge merges into the orifice passage  102  and adjacent its lower edge merges into a kidney or bowl-shaped portion  110  extending below the lower edge of the orifice passage  102  and rising to merge into the lower edge of the orifice passage  102  relative to the direction of rotation  112  of the drum. As shown in  FIGS. 15 and 17 , desirably liquid lead is also supplied to the orifice through the tube  100  with a plurality of apertures or holes  112  opening toward the orifice passage  102  and a downstream end wall  114  with through holes  116 . In use, excess liquid lead not entering the cavity  50  is returned through the downstream end of the shoe passage  98  to the furnace pot  58  of liquid lead. The apertures or holes  112  through the tube  100  tend to direct liquid lead generally radially through the orifice  92  and into the cavity  50  of the rotating drum  44  to facilitate casting of a solid lead ribbon  24 . Excess liquid lead flowing through the shoe  56  heats it and insures liquid lead at a desired temperature is supplied to the cavity  50 . 
     Ribs  120  and  122  project outwardly from the face  90  of the shoe and in assembly with the drum as shown in  FIG. 17  extend into the cavity  50  adjacent its axial ends to in use inhibit liquid lead from flowing upstream relative to the direction of rotation  112  of the drum. Short ribs  124  and  126  projecting outwardly from the face  90  of the shoe and disposed generally axially outward of the orifice  92 , in operation of the machine  40 , tend to also inhibit and reduce the extent of axial flow of liquid lead into the carbon fiber material. In operation of the machine  40 , the extent of the axial flow of liquid lead into the carbon fiber strip  22  is also reduced by compression of a proportion this strip between the circumferential rib  82  of the drum and the opposed face  90  of the shoe. However, the extent of this compression must be limited so that the carbon fiber material is not tom or unduly stressed by movement of it by the drum  44  relative to the shoe  56 . The extent to which this compression of the carbon fiber material must be limited to avoid tearing or undue stretching of the carbon fiber material may need to be empirically determined depending on various factors including the thickness and density of the strip  22  of the carbon fiber material, the speed at which the drum  44  rotates, the width of this rib  82 , etc. Itis believed the carbon fiber material may be compressed to 30% to 50% of its uncompressed nominal thickness. For a carbon fiber material having a nominal thickness of about 0.060 of an inch, a rib  82  with an axial width of about 0.06 of an inch and a rotary drum speed of about 80 to 100 lineal feet/minute, a compression of the strip to a thickness of about 0.020 of an inch has been empirically determined to be satisfactory. If desired small vent holes  128  of about 0.94 of an inch in diameter may be provided through the face  90  of the shoe and upstream of the orifice  92  relative to the direction of rotation  112  of the drum. 
     The forms of the invention herein disclosed constitute presently preferred embodiments and many other forms and embodiments are possible. It is not intended herein to mention all the possible equivalent forms or ramifications of the invention. It is understood that the terms used herein are merely descriptive, rather than limiting, and that various changes may be made without departing from the spirit or scope of the invention.