Patent Publication Number: US-11387498-B2

Title: Battery lithium cluster growth control

Description:
CLAIM OF PRIORITY 
     This application is a continuation of U.S. application Ser. No. 16/847,823, filed Apr. 14, 2020, which is a continuation of U.S. application Ser. No. 15/583,660, filed May 1, 2017, now issued as U.S. Pat. Ser. No. 10/665,845, which claims the benefit of priority under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application Ser. No. 62/330,317, filed on May 2, 2016, all of which are herein incorporated by reference in their entireties. 
    
    
     BACKGROUND 
     Implantable devices such as pacemakers or defibrillators include a housing holding electronics including batteries. The long-term reliability of batteries is a concern. 
     OVERVIEW 
     Example 1 can include an apparatus including a battery stack including a plurality of alternating anodes and cathodes; wherein each of the anodes is positioned between first and second separators, and wherein a tab of the anode extends out from between the first and second separators; and an edge tape extending across a top of the first and second separators. 
     In Example 2, the apparatus of Example 1 can optionally include wherein the edge tape covers over a portion of the tab. 
     In Example 3, the apparatus of any of Examples 1-2 can optionally include wherein the edge tape includes a first tape strip on a first side of the first separator and a second tape strip on an opposite side of the second separator. 
     In Example 4, the apparatus of any of Examples 1-3 can optionally include a battery case, wherein the battery stack is enclosed within the battery case. 
     In Example 5, the apparatus of any of Examples 1-4 can optionally include a case tape located on an inner surface of the case proximate a feedthrough, wherein the tape at least partially covers the bottom surface of the case and extends to at least partially cover two sidewalls of the case. 
     In Example 6, the apparatus of any of Examples 1-5 can optionally include wherein the battery stack is enclosed within a soaker pad enclosure. 
     In Example 7, the apparatus of any of Examples 1-6 can optionally include wherein the cathodes are enclosed in separator bags. 
     In Example 8, the apparatus of any of Examples 1-7 can optionally include wherein the edge tape includes a polyamide tape. 
     In Example 9, the apparatus of any of Examples 1-8 can optionally include wherein the edge tape includes a tape strip having a first portion and a second portion higher than the first portion, wherein the second, higher portion is located over the anode tab. 
     In Example 10, the apparatus of any of Examples 1-9 can optionally include wherein the battery stack includes lithium anodes with a layer of lithium located on a collector and wherein the edge tape is approximately as thick as the layer of lithium. 
     In Example 11 an apparatus can include an implantable housing holding electronics; a battery located within the implantable housing, the battery including a battery case and a battery stack within the case, the battery stack including a plurality of alternating anodes and cathodes, wherein each anode is positioned between first and second separators, and wherein a tab of the anode extends out from between the first and second separators; an edge tape extending across a top of the first and second separators; and a case tape located on an inner surface of the battery case proximate a feedthrough, wherein the case tape at least partially covers a bottom surface of the case and extends at least partially up two sidewalls of the case. 
     In Example 12 the apparatus of Example 11 can optionally include wherein the edge tape covers over a portion of the tab. 
     In Example 13, the apparatus of any of Examples 11-12 can optionally include wherein the edge tape includes a first tape strip on a first side of the first separator and a second tape strip on an opposite side of the second separator. 
     In Example 14, the apparatus of any of Examples 11-13 can optionally include wherein the battery stack is enclosed within a soaker pad enclosure. 
     In Example 15, the apparatus of any of Examples 11-14 can optionally include wherein the cathodes are enclosed in separator bags. 
     In Example 16, the apparatus of any of Examples 11-15 can optionally include wherein the edge tape includes a tape strip having a first portion and a second portion higher than the first portion, wherein the second, higher portion is located over the anode tab. 
     In Example 17, the apparatus of any of Examples 11-16 can optionally include wherein the battery stack includes lithium anodes with a layer of lithium located on a collector and wherein the edge tape is approximately as thick as the layer of lithium. 
     In Example 18 a method can include stacking a plurality of alternating anodes and cathodes into a battery stack, wherein each anode is positioned between first and second separators, and wherein a tab of the anode extends out from between the first and second separators; and placing an edge tape extending across a top of the first and second separators. 
     In Example 19, the method of Example 18 can optionally include wherein the anode is a lithium anode with lithium located on a collector, and wherein the edge tape is positioned such that it cover a top edge of the collector but does not cover the lithium. 
     In Example 20, the method of any of Examples 18-19 can optionally include providing a battery case; positioning a case tape on an inner surface of the battery case proximate a feedthrough, wherein the case tape at least partially covers a bottom surface of the case and extends at least partially up two sidewalls of the case; and placing the battery stack into the battery case. 
     These examples can be combined in any permutation or combination. This overview is intended to provide an overview of subject matter of the present patent application. It is not intended to provide an exclusive or exhaustive explanation of the invention. The detailed description is included to provide further information about the present patent application. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings, which are not necessarily drawn to scale, like numerals may describe similar components in different views. Like numerals having different letter suffixes may represent different instances of similar components. The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document. 
         FIG. 1  shows an implantable medical device in accordance with one example. 
         FIG. 2  shows an exploded view of a battery, in accordance with one embodiment. 
         FIG. 3  shows a top view of the battery stack of  FIG. 2 . 
         FIG. 4  shows a top view of an anode in accordance with one example. 
         FIG. 5  shows a close-up view of the anode of  FIG. 4 . 
         FIG. 6  shows a case tape, in accordance with one embodiment. 
         FIG. 7  shows another view of the case tape of  FIG. 6 . 
         FIG. 8  shows a perspective view of the case tape within a battery case, in accordance with one embodiment. 
         FIG. 9  shows a perspective view of a battery stack within a soaker pad in accordance with one embodiment. 
         FIG. 10  shows a perspective view of the unfolded soaker tape of  FIG. 9 . 
         FIG. 11  shows a top view of a cathode enclosed with a bag, in accordance with one embodiment. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows an implantable medical device  100  in accordance with one example. The implantable medical device  100  includes a metallic housing  110  and an attached header  120 . The header  120  includes one or more ports  122  to receive a terminal pin  124  of an implantable lead  130 . The lead  130  is configured to deliver pacing pulses, defibrillation shock energy, or cardioversion therapy to a heart, for example. The implantable medical device  100  can be implanted in a surgically-formed pocket in a patient&#39;s chest or other desired location. 
     The implantable medical device  100  generally includes electronic components  142  to perform signal analysis, processing, and control. The implantable medical device  100  can include a power supply such as a battery  150 , or a capacitor, and other components housed within housing  110 . The implantable medical device  100  can include microprocessors to provide processing and evaluation to determine and deliver electrical shocks and pulses of different energy levels and timing for ventricular defibrillation, cardioversion, and pacing to a heart in response to cardiac arrhythmia including fibrillation, tachycardia, and bradycardia via one or more electrodes of the lead  130 . 
     This device  100  includes one or more connector blocks  140  that connect to feedthroughs  152  to electrically communicate between the header  120  and the electronics  142  and battery  150  within housing  100 . Terminal contacts  126  on terminal  124  contact the connector blocks  140  to electrically communicate with electrodes on the lead  130 . 
     In other examples, the battery packaging subject matter discussed below can be used for other battery-powered device, such as sensors. 
       FIG. 2  shows an exploded view of the battery  150 , in accordance with one embodiment. 
     The battery  150  can include a metallic case  200  defining a chamber  202  which holds a battery stack  204 . In one embodiment, the case  200  can be manufactured from a conductive material, such as stainless steel. The case  20  can include a base  206  and a lid  208  positionable on an upper rim of base  206 . 
     The battery stack  204  can include including a plurality of alternating anodes  210  and cathodes  212 . Each of the anodes  212  can be positioned between first and second separators  213 ,  215 , with a tab  218  of the anode  212  extending out from between the first and second separators  213 ,  215 . In an example, the first and second separators  213 ,  215  can be sealed to form a separator bag  214 . 
     Each cathode  212  can include a cathode tab  216  and each anode  210  can include the anode tab  218 . As noted, the anode tabs  218  can extend out of the separator bag  214 . An electrolyte is placed in the case  200 . 
     After assembly the cathode tabs  216  are electrically connected to each and the anode tabs  218  are electrically connected to each other. A feedthrough post  220  can pass through the case  200  to stack  204  and is electrically insulated from case  200 . The feedthrough post  220  can be connected to the cathode tabs  216 , while the anode tabs  218  can be directly attached to the case  200 , which can itself act as the anode terminal. In some embodiments, these roles are reversed and the cathode tab can be connected to the case and the anode tab can connect to a feedthrough. In some embodiments, two feedthroughs can be provided, one for the anode and one for the cathode, 
       FIG. 3  shows a top view of the battery stack  204 . In one example, the anodes  210  can be formed of a lithium layer on a collector, such as a nickel collector. The cathodes  212  can be formed of a cathode material, such as MnO 2 , coated to a stainless steel wire-mesh collector. 
     One problem with lithium batteries is minimizing lithium cluster growth in the battery. The lithium cluster growth can initiate where electrolyte pooling is in contact with the anodic surface. In some examples, the pooling and cluster growth can form anywhere within the separator/anode assembly. For example, two areas of lithium cluster growth problems are in the area  302  where the anode tabs  218  come together where a lithium growth can be formed. Also, sometimes an anodic cluster can burst through the separator at an area  304  near the cathode tabs  216  and contact the cathode tab  216 , causing a short circuit. 
     The present discussion includes various packaging methods to prevent and minimize lithium cluster growths in the battery stack  204 . 
       FIG. 4  shows a top view of the anode  218 , in accordance with one example; and  FIG. 5  shows a close-up view of an upper portion of the anode  210 . 
     As discussed, each anode  210  can be positioned between first and second separators which can be sealed to form a sealed separator bag  214 . Various embodiments include separator bags  214  made of a pair of separator layers. The bag is formed around the anode  210  by providing two layers of the separator lavers and forming an edge weld seal around the perimeter of the separator layers, forming the separator bag  214 . Other separator layers, including additional materials, are within the scope of the present subject matter. An unwelded portion of the separator bag  214  allows tab  218  to extend therethrough. 
     A problem can arise when electrolyte pools along the upper portion of the anode  210  between the anode  210  and the sealed edge  310  of the separator bag  214 . In one embodiment, an edge tape  312  is positioned extending across a top of the first and second separators of separator bag  214  and the top of anode  210 . The edge tape  312  can include a first tape strip  311  on a first side of the first separator of separator bag  214  and a second tape strip  316  on an opposite, second side of the second separator of the separator bag  214 . The pair of tape strips  314 ,  316  are mirror images of each other. In an example, the edge tape  312  can include a polyamide tape, or other suitable tape. In one example, the edge tape  312  can be approximately as thick as the thickness of the layer of lithium of the anode. In another example, a single edge tape  312  is used that can wrap around the anode  210  and extend across a top of the first and second separators of separator bag  214  and the top of anode  210 . 
     By extending the edge tape  312  across the entire top portion of the separator bag  214 , pooling of electrolyte inside the separator bag  214  along the top edge of the anode  218  can be minimized, thus reducing cluster growth. 
     The edge tape  312  can include a first portion  320  and a second portion  322  that is higher than the first portion  320 . The second, higher portion  322  is located over the anode tab  218 . In one example, the edge tape  312  can be positioned such that it covers a top edge of a collector  330  but does not cover a lithium layer  332 . 
     Another technique to minimize results of lithium cluster growth includes providing a case tape.  FIG. 6  shows a case tape  400 , in accordance with one embodiment.  FIG. 7  shows another view of the case tape  400  folded for insertion into the case; and  FIG. 8  shows a perspective view of the case tape  400  within the battery case  200 . 
     The case tape  400  can include a generally irregular shape and can be modified depending on the shape of the battery case. Here, when folded, the case tape  400  has two edges  402  and  404  that curve upward relative to a main portion  406  of the case tape. When the case tape  400  is placed within the case the case tape  400  is positioned and located on an inner surface  410  of the case proximate the feedthrough  220 , and the case tape  400  at least partially covers the bottom surface  412  of the case  200  and extends to at least partially cover two sidewalls  414  and  416  of the case  200 . In one example, the open side wall area proximate the feedthrough  220  can further be covered with a medical adhesive to seal the anodic battery case surface where the case tape  400  does not cover. 
     This enlarged case tape  400  prevents any electrolyte pooling from touching the anodic surface, thus minimizing lithium clusters from forming. 
       FIG. 9  shows a perspective view of the battery stack  204  within a soaker pad assembly  500  in accordance with one embodiment.  FIG. 10  shows a perspective view of the unfolded soaker pad assembly  500 . 
     The soaker pad assembly  500  includes an internal soaker pad  502 , which can be formed of CELGARD, or other suitable material, and an external tape  504 , which can be formed of polyamide tape or other suitable tape. The assembly  500  can be designed to be wrapped around the battery stack  204  so that the soaker pad  502  is adjacent the edges of the stack  204 . A middle hole  506  can be cut-out of the soaker pad assembly to improve electrolyte wetting of the battery stack. A plurality of fingers  510  are formed in each of the tape  504  and the soaker pad  502  to provide the proper shape when the assembly  500  is wrapped around the stack  204 . 
     The soaker pad assembly  500  is designed to soak or wick up electrolyte from the anode separator bag perimeter. This can help prevent lithium growth clusters. Moreover, by displacing electrolyte away from the anode perimeter, the soaker bag assembly  500  allows for more electrolyte to be housed around the cathodes. This allows the battery to have access to more electrolyte later in the battery&#39;s life cycle. 
       FIG. 11  shows a top view of the cathode  212  enclosed within a bag  600 , in accordance with one embodiment. 
     In this example, the cathode is also enclosed within a separator bag with the tab extending out of the bag  600 . By using bag  600 , the electrolyte from the anode can be better held by the cathode to prevent pooling and to help prevent lithium cluster growth. 
     In forming a battery using one or more of these techniques described above, a battery stack is formed by stacking a plurality of alternating anodes and cathodes into a battery stack. In an example, each anode is enclosed in a separator bag, with a tab of the anode extends out of the separator bag. An edge tape is positioned so as to extend across a top of the separator bag. The edge tape can be positioned such that the edge tape covers a top edge of the anode collector but does not cover the lithium portion. 
     Another optional technique is to position a case tape on an inner surface of the battery case proximate the feedthrough. The case tape is sized and positioned such that the case tape at least partially covers a bottom surface of the case and extends at least partially up two sidewalls of the case. 
     Another optional technique is placing the battery stack into a soaker bag assembly prior to inserting the stack into the battery case. Optionally, the cathode can also be bagged. 
     In various embodiments, any one or all 4 or any combination of these techniques can be used to help minimize lithium cluster growth. 
     Additional Notes 
     The above detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments in which the invention can be practiced. These embodiments are also referred to herein as “examples.” Such examples can include elements in addition to those shown or described. However, the present inventors also contemplate examples in which only those elements shown or described are provided. Moreover, the present inventors also contemplate examples using any combination or permutation of those elements shown or described (or one or more aspects thereof), either with respect to a particular example (or one or more aspects thereof), or with respect to other examples (or one or more aspects thereof) shown or described herein. 
     All publications, patents, and patent documents referred to in this document are incorporated by reference herein in their entirety, as though individually incorporated by reference. In the event of inconsistent usages between this document and those documents so incorporated by reference, the usage in the incorporated reference(s) should be considered supplementary to that of this document; for irreconcilable inconsistencies, the usage in this document controls. 
     In this document, the terms “a” or “an” are used, as is common in patent documents, to include one or more than one, independent of any other instances or usages of “at least one” or “one or more.” in this document, the term “or” is used to refer to a nonexclusive or, such that “A or B” includes “A but not B,” “B but not A,” and “A and B,” unless otherwise indicated. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Also, in the following claims, the terms “including” and “comprising” are open-ended, that is, a system, device, article, or process that includes elements in addition to those listed after such a term in a claim are still deemed to fall within the scope of that claim. Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects.