Abstract:
This document discusses, among other things, an insulative member that is configured around a cathode, and methods and assemblies incorporation the insulative member. In an example, the insulative members protect the edge of the cathode material from damage, prevents the migration of cathode material into contact with an anode, or prevents a metal substrate in the cathode from shorting against an adjacent anode.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a continuation-in-part of U.S. patent application Ser. No. 10/360,551, filed on Feb. 7, 2003 to O&#39;Phelan et al., entitled “Batteries including a Flat Plate Design.” 
     
    
     TECHNICAL FIELD  
       [0002]     This patent document pertains generally to batteries, and more particularly, but not by way of limitation, to an insulative member on a battery cathode.  
       BACKGROUND  
       [0003]     A patient who is prone to irregular heart rhythms may have a miniature heart device, such as defibrillator and cardioverter, implanted in his or her body. Devices such as these detect the onset of an abnormal heart rhythm and apply a corrective electrical therapy to the heart.  
         [0004]     A defibrillator or cardioverter generally includes one or more leads, a battery for supplying power, circuitry for detecting an abnormal heart rhythm, and a capacitor for delivering a burst of electric current through one or more leads to the heart. The battery, circuitry and capacitor are typically contained in a housing. The one or more leads typically have a proximal end coupled to the housing and a distal end secured in or around the heart.  
         [0005]     The basic components that make up a battery are an anode, a cathode, and a separator between the anode and the cathode. A battery typically also includes an electrolyte and packaging hardware, which may include a medical device housing.  
       SUMMARY  
       [0006]     An example battery includes an anode, a cathode having a peripheral edge, a separator configured between the anode and the cathode, and at least one insert-molded insulative member molded over at least a first portion of the peripheral edge of the cathode.  
         [0007]     Another example battery is a flat-stacked battery including at least one cathode having a peripheral edge, at least one anode located below the at least one cathode, at least one separator located between the at least one anode and the at least one cathode, and at least one insulative member extending over at least a portion of the peripheral edge of the cathode. The at least one insulative member has a lip extending beneath the at least one cathode. The at least one anode is aligned against the lip.  
         [0008]     An example implantable device includes a housing, at least one lead, circuitry configured to send and receive electrical impulses through the lead, and a battery configured to provide electrical power to the circuitry. The battery includes at least one cathode having a peripheral edge, at least one anode located below the at least one cathode, at least one separator located between the at least one anode and the at least one cathode, and at least one insulative member extending over at least a portion of the peripheral edge of the cathode. The at least one insulative member has a lip extending beneath the at least one cathode. The at least one anode is aligned against the lip.  
         [0009]     An example method includes placing a cathode in a mold, the cathode having a peripheral edge, injecting a polymer into the mold, the polymer surrounding at least a portion of the peripheral edge of the cathode, and removing the cathode and polymer from the mold. The polymer forms at least one insulative member that extends over at least a portion of the peripheral edge of the cathode.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  illustrates a medical device and a heart.  
         [0011]      FIG. 2  is a partially cut-away perspective view of a cathode and an insulative member extending around the cathode.  
         [0012]      FIG. 3A  is a top view of a cathode and an insulative member extending around the cathode.  
         [0013]      FIG. 3B  is a top view of a cathode and an insulative member that does not extend over the entire peripheral edge of a cathode.  
         [0014]      FIG. 3C  is a top view of a cathode and a plurality of insulative members located at corner portions of the cathode.  
         [0015]      FIG. 4  is a cross-sectional perspective view of a cathode, metal substrate, and an insulative member.  
         [0016]      FIG. 5  is a partially cut-away cross-sectional schematic representation of a flat stacked battery including an exemplary insulative member.  
         [0017]      FIG. 6A  is a cross-sectional schematic representation of a stack assembly that includes an exemplary insulative member.  
         [0018]      FIG. 6B  is a cross-sectional schematic representation of a stack assembly that includes an exemplary insulative member.  
         [0019]      FIG. 6C  is a cross-sectional perspective view of an exemplary insulative member.  
         [0020]      FIGS. 7A and 7B  are cross-sectional schematic representations of a stack that includes an exemplary insulative member having a plurality of lips extending under a plurality of respective cathodes.  
         [0021]      FIGS. 8A  is a perspective view of a rolled battery including an insulative member.  
         [0022]      FIG. 8B  is a perspective view of an elliptically wound battery including an insulative member.  
         [0023]      FIGS. 9A, 9B , and  9 C illustrate a method of forming an insulative member on a cathode using an insert molding process.  
     
    
     DETAILED DESCRIPTION  
       [0024]     A battery assembly includes at least one insulative member that extends around a portion of a peripheral edge of a cathode. In an example, the cathode and insulative member are part of a medical device, such as the device shown in  FIG. 1 . Damage, degradation, and shorts can all reduce the life of a battery. In an example, the insulative member protects the edge of the cathode material from damage, prevents the migration of cathode material into contact with an anode, or prevents a metal substrate in the cathode from shorting against an adjacent anode. Exemplary insulative members on cathodes are shown in  FIG. 2 ,  FIGS. 3A-3C , and  FIG. 4 . In an example, the cathode and insulative member are part of a flat stacked battery, as shown, for example, in  FIG. 5 ,  FIGS. 6A-6C , and  FIGS. 7A-7B . In another example, the cathode and insulative member are incorporated into a rolled battery or elliptically wound battery, as shown in  FIGS. 8A and 8B  respectively. In an example, one or more insulative members are mechanically pressed onto a cathode. In an example, one or more insulative members are insert molded around a cathode, as illustrated in  FIG. 9A-9C .  
         [0025]     Referring now to  FIG. 1 , a battery is contained in an exemplary implantable device  105 . In an example, the device  105  includes a lead assembly  115  extending into a heart  120  and a housing  110  containing a battery. In an example, the device also includes a second lead  125  that extends into the left side of the heart. In an example, the implantable device includes a defibrillator circuit, and the battery is configured to supply a high energy signal through the defibrillator circuit. A battery typically includes at least one cathode, at least one anode, and at least one separator configured between the cathode and anode.  
         [0026]     Referring now to  FIG. 2 , an insulative member  205  extends around at least a portion of a peripheral edge  210  of a cathode  215 . In an example, the cathode  215  is made using a pressed powder technique. In another example, the cathode  215  is made using a slurry coating technique. In an example, the insulative member includes a polymer such as polypropylene, polyethylene, or polyimide. The insulative member is insulative in the sense that it is not electrically conductive. In an example, the insulative member protects the peripheral edge  210  of the cathode.  
         [0027]     In an example, the insulative member includes an inwardly-facing surface  220 . During assembly of a battery, the inwardly-facing surface  220  facilitates alignment of an anode with respect to the cathode. While the inwardly-facing surface  220  is shown perpendicular to a top surface  225  of the cathode, in other examples, the inwardly-facing surface is inclined towards or away from the top surface  225 .  
         [0028]     Referring now to  FIGS. 3A, 3B , and  3 C, top views of three examples of insulative member configurations are shown.  FIG. 3A  shows a top an insulative member  305  that extends around the entire periphery of a cathode  315 . The insulative member extends past an electrical contact  320  that protrudes from an edge of the cathode. In an example, the electrical contact  320  protrudes through the insulative member  305 . In another example, the insulative member extends below or above the electrical contact. In an example, the insulative member does not extend around the entire peripheral edge of the cathode. For example, the insulative member shown in  FIG. 3B  does not extend over a portion  325  of the peripheral edge  310  of the cathode proximate the contact  320 . In another example, shown in  FIG. 3C , insulative members  305  extend around the peripheral edge  310  proximate comer portions  330  of the cathode, which tend to be more vulnerable to damage and degradation.  
         [0029]      FIG. 4  shows a partial cross-sectional perspective view of an exemplary insulative member  405  that extends over an edge  410  of a cathode  415 . The cathode is configured on a metallic substrate  420 . A lower lip  430  extends under a lower surface  435  of the cathode. An upper lip  440  extends over an upper surface  445  of the cathode. In an example, the metallic substrate  420  includes expanded metal or a metal mesh. In an example, a portion  450  of the metallic substrate  420  protrudes from the cathode. In an example, the portion  450  that protrudes from the cathode is the end of a wire that is part of a wire mesh substrate. In an example, the portion of the metallic substrate  420  extends into the insulative member  405  or is otherwise confined by the insulative member. Confinement of portions of the metallic substrate that protrude from the cathode prevent shorting between the metallic substrate and adjacent anodes.  
         [0030]     Referring again to  FIG. 4 , a region  425  proximate the peripheral edge of the cathode has a reduced thickness. The reduced thickness permits use of a smaller insulative member, thereby conserving space in the housing of the medical device. In an example, the reduced thickness is created using a coining procedure. In an example, the insulative member  425  is insert molded around the cathode  415 . In another example, the insulative member  425  is mechanically pressed onto the cathode  415 .  
         [0031]     In an example, an insulative member, such as the member shown in  FIG. 4 , facilitates battery assembly procedures. In an example, the insulative member allows handling of the cathode by the insulative member to avoid damaging the cathode. In an example, the cathode is graspable and positionable by touching only the insulative member. In an example, a cathode is assembled into a flat stack battery, such as the stack shown in  FIG. 5 , by grasping the insulative member and positioning the cathode in a battery stack. In another example, the insulative member is manipulated to wind the cathode, an anode, and one or more separators into a rolled or elliptically wound battery assembly, as shown in  FIGS. 8A and 8B  respectively. In an example, the insulative member acts as a bumper that protects the edge of the cathode from impact or abrasion.  
         [0032]     Referring now to  FIG. 5 , a partially cut-away, cross-sectional schematic representation of a flat stacked battery assembly  500  is shown. The battery assembly  500  includes a plurality of insulative members  505  as well as a plurality of anodes  510 , cathodes  515 , and separators  520 . The stack is shown partially cut-away to permit labeling of anodes  510  and separators  520 . A separator  520  is provided between each anode  510  and cathode  515  to prevent direct contact between anodes and cathodes. The stacked assembly  500  can be formed, for example, by positioning the bottom cathode  525  by handling an insulative member  530  that is coupled to the bottom cathode, placing a separator on the cathode  525 , placing an anode on the separator, and placing a second separator on the anode. The process is then repeated, beginning with a second cathode  535  that is coupled to a second insulative member  540 . While eleven cathode layers and ten anode layers are shown in  FIG. 5 , more or fewer layers can be used. In another example, the layers are wider or thinner than shown in the schematic representation of  FIG. 5 . In an example, a cathode is 0.018 inches thick, an anode is 0.008 inches thick, and separator is 0.001 inches thick. In an example, a stack includes 12 cathodes, eleven anodes, and eleven separators, and the stack is approximately 0.315 inches thick.  
         [0033]      FIGS. 6A and 6B  show partial cross-sectional schematic illustrations of further examples of a stacked battery assembly  600 ,  601 . The stacked battery assembly includes include a plurality of insulative members  605 , anodes  610 , cathodes  615 , and separators  620  configured between the anodes and cathodes.  FIG. 6C  shows a cross-sectional perspective view of a portion of the insulative member shown in  FIGS. 6A and 6B . The insulative member  605  includes a lip  625  that extends beneath a cathode  615 . In an example, the separator  620  extends over an upper surface of the lip, and the cathode extends over the separator, as shown in  FIG. 6A . In another example, shown in  FIG. 6B , the cathode rests directly on the upper surface  630  of the lip  625 . In an example, the lip also has a lower surface  631  that contacts a separator or anode below the lip. While two layers are shown for purposes of illustration in  FIG. 6A , it is understood that a stack of  12  or more cathodes can be constructed.  
         [0034]     Referring now to  FIG. 6C , in an example, the lip  625  on the insulative member  605  includes a first inwardly-facing surface  635  that facilitates alignment of an anode with respect to the insulative member. In an example, the insulative member also includes a second inwardly-facing surface  640  that extends below the lip  625  and facilitates alignment of the insulative member with a cathode that is situated below the insulative member. In an example, the insulative member  605  also includes a third inwardly-facing surface  645  that extends above the lip  625  and facilitates alignment of the cathode above the lip  625  with the insulative member  605 . In an example, one or more of the surfaces  635 ,  640 ,  645  are inclined toward or away from an adjacent anode or cathode.  
         [0035]      FIG. 7A  shows a partial cross-sectional schematic illustration of another example of a stacked battery assembly  700 . The assembly includes at least one insulative member  705  and a plurality of an anodes  710 , cathodes  715 , and separators  720 . The insulative member includes a plurality of lips  725  that extend under the stacked cathodes  715 . In an example, the separators  720  extend over at least a portion of the lips  725 , as shown in  FIG. 7A , and the cathodes  715  rest on the separators. In an alternative example, the cathodes rest directly on the lips.  
         [0036]     In an example, the insulative member shown in  FIG. 7A  allows construction of a stack from the bottom up. As shown in  FIG. 7A , an upper portion of the insulative member  705  can be bent away from the stack. This allows anodes, cathodes, and separators to be stacked on a lip without obstruction from other lips above. For example, in  FIG. 7A , components are stacked on the lower two lips, and a separator and cathode have been stacked on the third lip. To build the next layer in the stack, another separator  740  is assembled on the top cathode  735 , and then some of the bending in the insulative member is relieved to bring the fourth lip  730  into position, as shown in  FIG. 7B . Next, an anode  745  is aligned against the fourth lip  730  and positioned against the top separator  740 . Then, a separator, cathode, and another separator are assembly on top of the anode. This assembly process is repeated until a desired stack height is reached.  
         [0037]     In an example, the insulative members shown in FIGS.  5 ,  6 A-C, and  7 A-B extend partially or fully around the perimeter of a cathode as shown, for example, in  FIGS. 3A and 3B . In another example, multiple insulative members are distributed around the perimeter of the cathode, for example as shown in  FIG. 3C .  
         [0038]      FIG. 8A  shows a rolled battery  800  that includes an insulative members  805 , on a proximal end of a cathode  820  that is rolled with a pair of separators  815  and an anode  810 . In an example, a second insulative member is provided on a distal end of the cathode.  FIG. 8B  shows an elliptically would battery  801  that includes an insulative member  805  on a proximal end of a cathode  820  that is wound around a mandrel  825  with a pair of separators  815  and an anode  810 . In an example, a second insulative member is provided on a distal end of the elliptically-would cathode In an exemplary method, the insulative members are insert molded or mechanically pressed onto the cathode in a flat configuration, and the cathode is then assembled with the anode and separator and rolled or wound.  
         [0039]      FIGS. 9A-9C  illustrates a method of insert molding an insulative member around a cathode. A cathode  905  for a stacked, rolled, or elliptically wound battery is inserted into a cavity  910  in a mold  915 , as shown in  FIG. 9A . The mold  915  is closed, as shown in  FIG. 9B , and polymer is inserted into the cavity in the mold. The polymer flows around the cathode  905 . The polymer forms one or more insulative members  920  around the cathode. The cathode and insert-molded insulative member(s) are removed from the mold, as shown in  FIG. 9C . In an example, this process is repeated for a plurality of cathodes. In an example, cathodes are grasped by the insulative member and arranged in a stack with other battery components, such as anodes and separators.  
         [0040]     Examples of the various cathodes, insulative members, and battery assemblies shown and described in this application can be used in an implantable medical device, such as a defibrillator or cardioverter. The cathodes, insulative members, and battery assemblies can also be used in other implantable medical devices that deliver an electrical therapy to parts of the body other than the heart, as well as in non-implantable devices.  
         [0041]     The above specification, examples and data provide a complete description of the manufacture and use of the composition of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.