U.S. patent application number 11/861344 was filed with the patent office on 2008-01-17 for headspace insulator for electrochemical cells.
Invention is credited to David P. Haas, William G. Howard, Jeffrey S. Lund.
Application Number | 20080010816 11/861344 |
Document ID | / |
Family ID | 34592232 |
Filed Date | 2008-01-17 |
United States Patent
Application |
20080010816 |
Kind Code |
A1 |
Howard; William G. ; et
al. |
January 17, 2008 |
HEADSPACE INSULATOR FOR ELECTROCHEMICAL CELLS
Abstract
A headspace insulator for a battery cell operatively coupled to
circuitry within an implantable medical device in including one or
more of the following: (a) a body of electrically and thermally
insulating material disposed between a battery electrode assembly
and a battery cover, (b) a receiving area within the body that
receives and isolates a battery feedthrough pin, (c) an indentation
within the receiving area retaining the feedthrough pin within the
receiving area, (d) a raised portion coupled to a battery cover
providing an air gap between the cover and the headspace insulator
near case-to-cover weld areas, (e) a feedthrough aperture adapted
to receive a feedthrough assembly, (f) a pin aperture that receives
the feedthrough pin, (g) a fillport aperture for electrolyte fluid
flow through the headspace insulator, and (h) a slot that locates a
battery weld bracket and isolates it from the feedthrough pin.
Inventors: |
Howard; William G.;
(Roseville, MN) ; Haas; David P.; (Brooklyn Park,
MN) ; Lund; Jeffrey S.; (Forest Lake, MN) |
Correspondence
Address: |
MEDTRONIC, INC.
710 MEDTRONIC PARKWAY NE
MINNEAPOLIS
MN
55432-9924
US
|
Family ID: |
34592232 |
Appl. No.: |
11/861344 |
Filed: |
September 26, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10723317 |
Nov 26, 2003 |
7294432 |
|
|
11861344 |
Sep 26, 2007 |
|
|
|
Current U.S.
Class: |
29/623.2 ;
29/623.1 |
Current CPC
Class: |
Y10T 29/49108 20150115;
H01M 50/60 20210101; H01M 50/172 20210101; Y10T 29/49114 20150115;
Y10T 29/4911 20150115; H01M 50/636 20210101; H01M 6/16 20130101;
H01M 50/528 20210101 |
Class at
Publication: |
029/623.2 ;
029/623.1 |
International
Class: |
H01M 2/08 20060101
H01M002/08; H01M 6/02 20060101 H01M006/02 |
Claims
1. A method of manufacturing a battery for an implantable medical
device, comprising: placing a case liner and a coil insulator over
an electrode assembly; coupling a weld bracket to a battery cover;
coupling a headspace insulator to the battery cover; bending the
feedthrough pin; locking a distal end of the feedthrough pin into a
receiving area in the headspace insulator; aligning the headspace
insulator with the electrode assembly so a second electrode tab on
the electrode assembly is accepted within a second electrode
opening in the headspace insulator and a first electrode tab on the
electrode assembly is accepted within a first electrode opening in
the headspace insulator; coupling the second electrode tab and the
distal end of the feedthrough pin; coupling the first electrode tab
and the weld bracket; placing the electrode assembly within the
battery case; and coupling the battery cover to the battery
case.
2. A method according to claim 1, further comprising the step of
filling the battery case with an electrolyte through a fill
port.
3. A method according to claim 2, further comprising the step of
sealing the battery case with a closing ball and button.
4. A method according to claim 1, wherein the coil insulator is
comprised of slits to receive the first electrode tab and the
second electrode tab.
Description
CROSS REFERENCE TO PRIORITY APPLICATION
[0001] This application is a divisional of application Ser. No.
10/723,317, filed Nov. 26, 2003, now allowed.
FIELD OF THE INVENTION
[0002] The present invention relates to the field of power sources
such as primary batteries, capacitors and rechargeable batteries
for devices such as an implantable medical device (IMD). More
particularly, the present invention relates to an improved
headspace insulator for an electrochemical cell adapted to be
operatively coupled to electronic circuitry within an IMD.
Furthermore, the present invention relates to electrochemical cells
comprising a novel headspace insulator and a method of fabricating
an electrochemical cell incorporating said headspace insulator.
BACKGROUND OF THE INVENTION
[0003] Implantable medical devices are used to treat patients
suffering from a variety of conditions. An example of an IMD
include implantable pulse generators (e.g., a cardiac pacemaker)
and implantable cardioverter-defibrillators (ICDs), which are
electronic medical devices that monitor the electrical activity of
the heart and provide electrical stimulation to one or more of the
heart chambers, when necessary. For example, a pacemaker senses an
arrhythmia, i.e., a disturbance in heart rhythm, and provides
appropriate electrical stimulation pulses, at a controlled rate, to
selected chambers of the heart in order to correct the arrhythmia
and restore the proper heart rhythm. The types of arrhythmias that
may be detected and corrected by pacemakers include bradycardias,
which are unusually slow heart rates, and certain tachycardias,
which are unusually fast heart rates.
[0004] Implantable cardioverter-defibrillators also detect
arrhythmias and provide appropriate electrical stimulation pulses
to selected chambers of the heart to correct the abnormal heart
rate. In contrast to pacemakers, however, an ICD can also provide
more power. This is because ICDs are designed to correct
fibrillation, which is a rapid, unsynchronized quivering of one or
more heart chambers, and severe tachycardia, where the heartbeats
are very fast but coordinated. To correct such arrhythmias, an ICD
delivers a low, moderate, or high-energy shock to the heart.
[0005] In order to perform their pacing and/or
cardioverting-defibrillating functions, pacemakers and ICDs must
have an energy source, e.g., a battery. An example of a prior
battery is shown with reference to FIG. 1. The exploded perspective
view of a prior battery solution is shown having a battery cover 10
and a headspace insulator 12 along with a battery case 14 and an
electrode assembly 16. Battery cover 10 includes a feedthrough 18
through which feedthrough pin 20 is inserted. The feedthrough pin
20 is conductively insulated from the cover 10 by glass where it
passes through the cover 10.
[0006] The feedthrough pin 20 is generally bent to align itself
with connector tabs 22 extending from electrode assembly 16. The
battery cover 10 also includes a fill port 24 used to introduce an
appropriate electrolyte solution after which the fill port 24 is
hermetically sealed by any suitable method.
[0007] The headspace insulator 12 is generally located below
battery cover 10 and above a coil insulator in the headspace above
the coiled electrode assembly 16 and below the cover 10. The
headspace insulator 12 is provided to electrically insulate the
feedthrough pin 20 from case 14 and battery cover 10. The headspace
insulator 12 forms a chamber in connection with the upper surface
of the coil insulator isolating the feedthrough pin 20 and the
connector tabs 22 to which it is attached.
[0008] While these prior battery solutions operate well to provide
an energy source for an IMD there is room for improvement in the
headspace design. Specifically, these prior solutions cannot hold
the feedthrough pin in a uniform isolated location. In prior
battery designs, a bend or a coil is formed in the feedthrough pin
to act as a strain relief. This prevents the feedthrough pin from
being in a rigid condition, such as if the pin was connected
directly to a tab without a bend in the feedthrough pin. However,
with a bend in the feedthrough pin there is little give to prevent
any fatigue of the wire or the joint where the feedthrough pin
enters the feedthrough through the glass during a shock or
vibration event. Therefore, the bend acts as a cushion.
[0009] The prior headspace insulator is typically a thermoformed
thin-walled plastic component. It is not precisely located with
respect to other internal battery components and is susceptible to
deformation during the assembly process. While this condition does
not present any compromise to the intent of the headspace insulator
design, it can affect manufacturing yields.
[0010] One of the variables associated with prior coiled electrode
battery designs and assembly methods involves the length of the
feedthrough pin between the pin-to-glass interface of the
feedthrough and the pin-to-tab weld. This length is determined
during the pin-to tab welding operation. Previous coiled electrode
battery designs employed a "hinged" cover. The design welded the
feedthrough pin to the tab(s) of one electrode of the coiled
electrode assembly. The electrode assembly was then seated into the
case. The cover was then seated into the case to complete the
assembly. The feedthrough pin was shaped to have a coil or bend
placed in the pin prior to welding the pin to the tab(s). The coil
or bend in the pin was located between the glass of the feedthrough
and the pin to tab weld. This coil offered strain relief to the
pin, the pin-to-tab weld, and the pin-to-glass interface during
electrode insertion into the case and subsequent cover insertion
into the case. Due to the variations in the shape of the
feedthrough pin, caused from material springiness, general handling
of the pin, and the tab weld personnel, the length of the pin
between the pin-to-glass interface and the pin-to-tab weld varied
from one assembly to the next. This non-uniform pin length caused
the case to cover insertion processing to be inconsistent.
[0011] Attempts were made to prevent the stresses on the weld by
providing a coil in the feedthrough pin. However, this increased
the length of the feedthrough pin, which in turn increased the
resistance of the pin. This was an undesirable result as the
resistance consumed power from the battery.
BRIEF SUMMARY OF THE INVENTION
[0012] A battery in embodiments of the invention may include one or
more of the following features: (a) an electrode assembly having a
second electrode tab and a first electrode tab, (b) a battery case
having the electrode assembly within the battery case, (c) a
battery cover having a feedthrough, the battery cover being coupled
to the battery case, (d) a headspace insulator having a receiving
area, (e) a feedthrough assembly having a ferrule, feedthrough pin,
and insulating member, the feedthrough pin having a distal end
locked into the receiving area and coupled to the second electrode
tab, (f) a weld bracket coupled to the battery cover, the weld
bracket being coupled to the first electrode tab, (g) a second
electrode opening to accept the second electrode tab, and a first
electrode opening to accept the first electrode tab, (h) a case
liner, (i) a coil insulator having slits, the coil insulator and
the case liner enclosing the electrode assembly with the second
electrode tab and the first electrode tab extending through the
slits.
[0013] A headspace insulator for a battery in an IMD in one or more
embodiments of the present invention may include one or more of the
following features: (a) a body of electrically and thermally
insulating material disposed between a battery electrode assembly
and a battery cover, (b) a receiving area within the body that
receives and isolates a battery feedthrough pin, (c) an indentation
within the receiving area that holds the feedthrough pin in place
once the feedthrough pin is within the receiving area, (d) a raised
portion that couples to a battery cover and provides an air gap
between the cover and the headspace insulator near a battery case
to battery cover weld areas, (e) a feedthrough aperture that
receives a battery feedthrough assembly, (f) a pin aperture that
receives the feedthrough pin, (g) a fillport aperture that allows
an electrolyte to pass through the headspace insulator into the
electrode assembly, and (h) a slot that locates a battery weld
bracket and isolates it from the feedthrough pin.
[0014] Methods of manufacturing a battery for an IMD according to
the present invention may include one or more of the following
steps: (a) placing a case liner and a coil insulator over an
electrode assembly, (b) coupling a weld bracket to a battery cover,
(c) coupling a headspace insulator to the battery cover, (d)
bending the feedthrough pin, (e) locking a distal end of the
feedthrough pin into a receiving area in the headspace insulator,
(f) aligning the headspace insulator with the electrode assembly so
a second electrode tab on the electrode assembly is accepted within
a second electrode opening in the headspace insulator and a first
electrode tab on the electrode assembly is accepted within a first
electrode opening in the headspace insulator, (g) coupling the
second electrode tab and the distal end of the feedthrough pin, (h)
coupling the first electrode tab and the weld bracket, (i) placing
the electrode assembly within the battery case, (j) coupling the
battery cover to the battery case, (k) filling the battery case
with an electrolyte through a fill port, and (l) sealing the
battery with a closing ball and button.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is an exploded perspective view of a prior battery
design.
[0016] FIG. 2 is a cutaway perspective view of a battery case,
electrode assembly, case liner, coil insulator, battery cover, and
a headspace insulator in an embodiment according to the present
invention.
[0017] FIG. 3 is a cutaway perspective view of the electrode
assembly as shown in FIG. 2.
[0018] FIG. 4 is an exploded perspective view of a battery case,
electrode assembly, case liner, coil insulator, battery cover, and
a headspace insulator in an embodiment according to the present
invention.
[0019] FIG. 5 is a cutaway side profile view of a headspace
insulator in the embodiment shown in FIG. 6.
[0020] FIG. 6 is an underside profile view of a headspace insulator
in an embodiment of the present invention.
[0021] FIG. 7 is an overhead profile view of a headspace insulator
in an embodiment of the present invention.
[0022] FIG. 8 is a cutaway side profile view of a headspace
insulator in the embodiment shown in FIG. 6.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
[0023] The following discussion is presented to enable a person
skilled in the art to make and use the invention. Various
modifications to the illustrated embodiments will be readily
apparent to those skilled in the art, and the generic principles
herein may be applied to other embodiments and applications without
departing from the spirit and scope of the present invention as
defined by the appended claims. Thus, the present invention is not
intended to be limited to the embodiments shown, but is to be
accorded the widest scope consistent with the principles and
features disclosed herein. The following detailed description is to
be read with reference to the figures, in which like elements in
different figures have like reference numerals. The figures, which
are not necessarily to scale, depict selected embodiments and are
not intended to limit the scope of the invention. Skilled artisans
will recognize the examples provided herein have many useful
alternatives fall within the scope of the invention.
[0024] The present invention is not limited to ICDs and may be
employed in many various types of electronic and mechanical devices
for treating patient medical conditions such as pacemakers,
defibrillators, neurostimulators, and therapeutic substance
delivery pumps. It is to be further understood; moreover, the
present invention is not limited to high current batteries and may
be utilized for low or medium current batteries and for
rechargeable batteries as well. For purposes of illustration only,
however, the present invention is below described in the context of
high current batteries.
[0025] As used herein, the terms battery or batteries include a
single electrochemical cell or cells. Batteries are volumetrically
constrained systems in which the components in the case of the
battery cannot exceed the available volume of the battery case.
Furthermore, the relative amounts of some of the components can be
important to provide the desired amount of energy at the desired
discharge rates. A discussion of the various considerations in
designing the electrodes and the desired volume of electrolyte
needed to accompany them in, for example, a lithium/silver vanadium
oxide (Li/SVO) battery is discussed in U.S. Pat. No. 5,458,997
(Crespi et al.). Generally, however, the battery must include the
electrodes and additional volume for the electrolyte required to
provide a functioning battery.
[0026] With reference to FIG. 2, an exploded perspective view of a
battery case, electrode assembly, case liner, coil insulator,
battery cover, and a headspace insulator in an embodiment according
to the present invention is shown. A battery 40 according to the
present invention includes a case 42 and an electrode assembly 44.
Case 42 is generally made of a medical grade titanium, however, it
is contemplated that case 42 could be made of almost any type of
metal such as aluminum and stainless steel, as long as the metal is
compatible with the battery's chemistry in order to prevent
corrosion. Further, it is contemplated case 42 could be
manufactured from most any process including but not limited to
machining, casting, drawing, or metal injection molding. Case 42 is
designed to enclose electrode assembly 44 and be sealed by a
battery cover 46. While sides 48 of case 42 are generally planar it
is contemplated sides 48 could be generally arcuate in shape. This
construction would provide a number of advantages including the
ability to accommodate one of the curved or arcuate ends of a
coiled electrode assembly 44. Arcuate sides could also nest within
an arcuate edge of an IMD such as an implantable cardiac
defibrillator.
[0027] The details regarding construction of electrode assembly 44,
such as positive and negative electrodes, electrode pouches, etc.,
are secondary to the present invention and will be described
generally below with a more complete discussion being found in,
e.g., U.S. Pat. No. 5,458,997 (Crespi et al.).
[0028] Electrode assembly 44 is generally a wound or coiled
structure similar to those disclosed in, e.g., U.S. Pat. No.
5,486,215 (Kelm et al.). However, other electrode assembly
configurations such as a folded and interleaved electrodes
disclosed in, e.g., U.S. Pat No. 5,154,989 (Howard et al.) or
simply individual electrodes. As a result, the electrode assemblies
typically exhibit two generally planar sides, bounded by two
opposing generally arcuate edges and two opposing generally planar
ends. The composition of the electrode assemblies can vary,
although one illustrated electrode assembly includes a wound core
of lithium/silver vanadium oxide (Li/SVO) battery as discussed in,
e.g., U.S. Pat. No. 5,458,997 (Crespi et al.). Other battery
chemistries are also anticipated, such as those described in U.S.
Pat. No. 5,180,642 (Weiss et al) and U.S. Pat. No. 4,302,518 and
4,357,215 (Goodenough et al).
[0029] With reference to FIG. 3, a cutaway perspective view of the
electrode assembly as shown in FIG. 2 is shown. Electrode assembly
44 generally includes a second electrode 80, a first electrode 82,
and a porous, electrically non-conductive separator material 84
encapsulating either or both of second electrode 80 and first
electrode 82. These three components are generally placed together
and wound to form electrode assembly 44. Second electrode 80 of
electrode assembly 44 can comprise a number of different materials
including second electrode active material located on a second
electrode conductor element. In this embodiment the second
electrode is an anode in the case of a primary cell or the negative
electrode in the case of a rechargeable cell. Examples of suitable
electrode active materials include, but are not limited to: alkali
metals, materials selected from Group IA of the Periodic Table of
Elements, including lithium, sodium, potassium, etc., and their
alloys and intermetallic compounds including, e.g., Li--Si, Li--B,
and Li--Si--B alloys and intermetallic compounds, insertion or
intercalation materials such as carbon, or tin-oxide. Examples of
suitable materials for anode or negative electrode conductor
element include, but are not limited to: stainless steel, nickel,
or titanium. The details regarding construction of electrode
assembly 44, such as positive and negative electrodes, are
described with a more complete discussion being found in, e.g.,
U.S. Pat. No. 5,439,760 (Howard et al.).
[0030] First electrode portion 82 of electrode assembly 44
generally includes a first electrode active material located on a
first electrode current collector, which also conducts the flow of
electrons between the first electrode active materials, and first
electrode terminals of electrode assembly 44. In this embodiment
the first electrode is a cathode in the case of a primary cell or
the positive electrode in the case of a rechargeable cell. Examples
of materials suitable for use as first electrode active material
include, but are not limited to: a metal oxide, a mixed metal
oxide, a metal, and combinations thereof. Suitable first electrode
active materials include silver vanadium oxide (SVO), copper
vanadium oxide, copper silver vanadium oxide (CSVO), manganese
dioxide, titanium disulfide, copper oxide, copper sulfide, iron
sulfide, iron disulfide, and fluorinated carbon, and mixtures
thereof, including lithiated oxides of metals such as manganese,
cobalt, and nickel.
[0031] Generally, cathode or positive electrode active material
comprises a mixed metal oxide formed by chemical addition, reaction
or otherwise intimate contact or by thermal spray coating process
of various metal sulfides, metal oxides or metal oxide/elemental
metal combinations. The materials thereby produced contain metals
and oxides of Groups IB, IIB, IIIB, IVB, VB, VIB, VIIB, and VIII of
the Periodic Table of Elements, which includes noble metals and/or
their oxide compounds.
[0032] First cathode and positive electrode materials can be
provided in a binder material such as a fluoro-resin powder,
generally polyvinylidine fluoride or polytetrafluoroethylene (PTFE)
powder also includes another electrically conductive material such
as graphite powder, acetylene black powder, and carbon black
powder. In some cases, however, no binder or other conductive
material is required for the first electrode.
[0033] Separator material 84 should electrically insulate second
electrode 80 from first electrode 82. The material is generally
wettable by the cell electrolyte, sufficiently porous to allow the
electrolyte to flow through separator material 84, and maintain
physical and chemical integrity within the cell during operation.
Examples of suitable separator materials include, but are not
limited to: polyethylenetetrafluoroethylene, ceramics, non-woven
glass, glass fiber material, polypropylene, and polyethylene. As
illustrated, separator 84 consists of three layers. A polyethylene
layer is sandwiched between two layers of polypropylene. The
polyethylene layer has a lower melting point than the polypropylene
and provides a shut down mechanism in case of cell over heating.
The electrode separation is different than other lithium-ion cells
in that two layers of separator are used between second electrode
80 and first electrode 82.
[0034] As illustrated, the electrolyte solution can be an alkali
metal salt in an organic solvent such as a lithium salt (i.e. 1.0M
LiCIO.sub.4 or LiAsF.sub.6) in a 50/50 mixture of propylene
carbonate and dimethoxyethane.
[0035] As best seen in FIG. 4, a coil insulator 54 is located on
electrode assembly 44 when assembled, which is discussed in more
detail below. Coil insulator 54 includes slits 56 and 58 to
accommodate first electrode tab 52 and second electrode tab 50.
Coil insulator 54 further includes aperture 61 allowing electrolyte
to enter and surround electrode assembly 44. Generally insulator 54
is comprised of ETFE, however, it is contemplated other materials
could be used such as HDDE, polypropylene, polyurethane,
fluoropolymers, and the like. Insulator 54 performs several
functions including working in conjunction with case liner 60 to
isolate case 42 and cover 46 from electrode assembly 44. It also
provides mechanical stability for electrode assembly 44. In
addition, it serves to hold electrode assembly 44 together which
substantially aids in the manufacturing of battery 40.
[0036] Electrode assembly 44 is also generally inserted into an
electrically non-conductive case liner 60 during assembly. Case
liner 60 generally extends at its top edge above the edge of
electrode assembly 44 to overlap with coil insulator 54. Case liner
60 is generally comprised of ETFE, however, other types of
materials are contemplated such as polypropylene, silicone rubber,
polyurethane, fluoropolymers, and the like. Case liner 60 generally
has substantially similar dimensions to case 42 except case liner
60 would have slightly smaller dimensions so it can rest inside of
battery case 42.
[0037] FIGS. 2 and 4 also depict battery cover 46 and a headspace
insulator 62 along with case 42 and electrode assembly 44. Similar
to case 42, cover 46 is comprised of medical grade titanium to
provide a strong and reliable weld creating a hermetic seal with
battery case 42. However, it is contemplated cover 46 could be made
of any type of material as long as the material was
electrochemically compatible. Illustrated battery cover 46 includes
a feedthrough aperture 64 through which feedthrough assembly 68 is
inserted. Feedthrough assembly contains a ferrule 67, a insulating
member 65, and a feedthrough pin 66. Feedthrough pin 66 is
comprised of niobium; however, any conductive material could be
utilized without departing from the spirit of the invention.
Niobium is generally chosen for its low resistivity, its material
compatibility during welding with titanium, and its coefficient of
expansion when heated. Niobium and titanium are compatible metals,
meaning when they are welded together a strong reliable weld is
created.
[0038] Feedthrough pin 66 is generally conductively insulated from
cover 46 by feedthrough assembly 68 where it passes through cover
46. Insulating member 65 is comprised of CABAL-12
(calcium-boro-aluminate), TA-23 glass or other glasses, which
provides electrical isolation of feedthrough pin 66 from cover 46.
The pin material is in part selected for its ability to join with
insulating member 65, which results in a hermetic seal. CABAL-12 is
very corrosion resistant as well as a good insulator. Therefore,
CABAL-12 provides for good insulation between pin 66 and cover 46
as well as being resistant to the corrosive effects of the
electrolyte. However, other materials besides glass can be
utilized, such as ceramic materials, without departing from the
spirit of the invention. Battery cover 46 also includes a fill port
70 used to introduce an appropriate electrolyte solution after
which fill port 70 is hermetically sealed by any suitable
method.
[0039] Headspace insulator 62 is generally located below battery
cover 46 and above coil insulator 54, i.e., in the headspace above
coiled electrode assembly 44 and below the cover 46. Generally,
headspace insulator 62 is comprised of ETFE (Ethylene
Tetrafluoroethylene), however, other insulative materials are
contemplated such as polypropylene. ETFE is stable at both second
electrode 80 and first electrode 82 potentials and has a relatively
high melting temperature. Headspace insulator 62 preferably covers
distal end 72 of feedthrough pin 66, first electrode tab 52, and
second electrode tab 50. While electrode assembly 44 is described
as having a first and second electrode tab, it is fully
contemplated each electrode could have a plurality of tabs without
departing from the spirit of the invention. Insulator 62 is
designed to provide thermal protection to coiled electrode assembly
44 from the weld joining case 42 and cover 46 by providing an air
gap between the headspace insulator and the cover in the area of
the case to cover weld. Insulator 62 prevents electrical shorts by
providing electrical insulation between the first electrode tab 52,
second electrode tab 50, and bracket 74 and their conductive
surfaces. Illustrated weld bracket 74 serves as conductor between
first electrode tab 52 and battery cover 46. Weld bracket 74 is a
nickel foil piece that is welded to both cover 46 and first
electrode tab 52.
[0040] Battery 40 in FIGS. 2 and 4 can be thought of as consisting
of three major functional portions. They are the encasement,
insulation, and active component portions. The encasement or
closure portion consists of case 42, cover 46, feedthrough assembly
68, fillport 70, ball 112, button 114, and electrical connections.
The major functions of the encasement are to provide a hermetic
seal, a port for adding electrolyte and isolated electrical
connections. The major function of the insulators is to prevent
electrical shorts. The insulators consist of headspace insulator
62, coil insulator 54, and case liner 60. The active portion of the
cell is where the electrochemistry/energy storage occurs. It
consists of the electrolyte and coiled electrode assembly 44.
Coiled electrode assembly 44 consists of second electrode 80, first
electrode 82, and two layers of separator 84.
[0041] With reference to FIG. 5, a cutaway side profile view of a
headspace insulator in the embodiment shown in FIG. 6 is shown. As
illustrated, headspace insulator 62 has a generally parallelepiped
shape and has a solid construction except for portions of insulator
62 which are missing and will be discussed below. A raised portion
90 contacts the underside of battery cover 46 and provides an air
gap between cover 46 and insulator 62 near the weld areas where
cover 46 and case 42 meet (see FIG. 7 and 8). Generally, raised
portion 90 is positioned to the underside of battery cover 46. It
is contemplated insulator 62 could be attached to the underside of
battery cover 46 in other fashions, such as, a snapping assembly,
or fasteners without departing from the spirit of the present
invention. Feedthrough aperture 92 receives feedthrough assembly 68
(shown in FIG. 4) when insulator 62 (shown in FIG. 4) is placed on
battery cover 46 (shown in FIG. 4) as will be discussed in detail
below. Similarly, pin aperture 94 receives feedthrough pin 66
(shown in FIG. 4). As can be seen, an inner portion of pin aperture
94 has a curvature 96, which provides support for pin 66 when the
manufacturer bends pin 66 (shown in FIG. 4) after insertion to
place distal end 72 into receiving area 98. Receiving area acts to
hold distal end 72 still during any shock or vibration occurrences
as well as isolate pin 66 (shown in FIG. 4) from contact with any
other polarized surfaces. Indentations 100 assist to hold distal
end 72 (shown in FIG. 4) in place once distal end 72 is pressed
into receiving area 98, as will be described in more detail below.
As can be further seen, there is a second electrode opening 102 for
receiving second electrode tab 50 and a first electrode opening 104
for receiving first electrode tab 52. There is also a fillport
aperture 106, which allows electrolyte to pass through insulator 62
to electrode assembly 44.
[0042] With reference to FIG. 6, an underside profile view of a
headspace insulator in an embodiment of the present invention is
shown. As can be shown, insulator 62 has a slot 108 to receive weld
bracket 74. Slot 108 allows for weld bracket 74 to fit between
insulator 62 and the inside surface of battery case 42. Slot 108 is
also isolated from receiving area 98 and second electrode opening
102 to prevent any shorting between the positive and negative
polarities. Further shown in FIG. 6 is pin aperture 94, receiving
area 98, indentations 100, second electrode opening 102, first
electrode opening 104, and fillport aperture 106.
[0043] With reference to FIG. 7, an overhead profile view of a
headspace insulator in an embodiment of the present invention is
shown. Further shown is feedthrough aperture 92, pin aperture 94,
raised portion 90, slot 108, and fillport aperture 106.
[0044] With reference again to FIGS. 2 and 4, battery 40 is
generally constructed according to the discussion below. Battery 40
can be put together in three sections. Section one contains battery
case 42. Section two contains case liner 60, electrode assembly 44,
and coil insulator 54. Section three contains headspace insulator
62, battery cover 46, weld bracket 74, feedthrough pin 66, and
feedthrough assembly 68. With section two, case liner 60 and coil
insulator 54 are placed over electrode assembly 44 with second
electrode tab 50 and first electrode tab 52 extending through slits
56 and 58. With section three, weld bracket 74 is welded to cover
46. Raised portion 90 of headspace insulator 62 is positioned on
the underside of cover 62 with slot 108 accepting weld bracket 74.
Feedthrough assembly 68 with feedthrough pin 66 is inserted into
feedthrough 64 and accepted by feedthrough aperture 92 and pin
aperture 94 respectively. Feedthrough pin 66 is then bent over
along curvature 96 towards receiving area 98. Feedthrough pin 66 is
then placed into receiving area 98 and locked into place by
indentations 100. This electrically isolates feedthrough pin 66
from case 42, cover 46, weld bracket 74, first electrode tab 52 or
any other element which has an opposing polarity to feedthrough pin
66.
[0045] The section three assembly is then aligned with the section
two assembly so second electrode tab 50 is accepted within second
electrode opening 102 and first electrode tab 52 is accepted within
first electrode opening 104 where second electrode tab 50 is
adjacent to distal end 72 of feedthrough pin 66 and first electrode
tab 52 is adjacent to weld bracket 74. Second electrode tab 50 and
distal end 72 of feedthrough pin 66 are then welded together as is
first electrode tab 52 and weld bracket 74. It is contemplated
other methods of attachment could be used such as rivets and
crimping without departing from the spirit of the invention. At
this point the assembly can be inserted it into battery case 42.
Cover 46 is then laser welded to battery case 42. Battery 40 is
then filled full of electrolyte through fill port 70 and sealed
with a closing ball 112 and button 114 and welded shut to
hermetically seal battery 40. It is contemplated the steps for
manufacturing battery 40 can be alternated without departing from
the spirit of the invention.
[0046] Insulator 62 provides many advantages over the prior
solutions. Insulator 62 provides an insulating layer around ferrule
67 that prevents feedthrough pin 66 from electrically shorting to
ferrule 67. Insulator 62 provides for receiving area 98 that
locates feedthrough pin 66 in a fixed location which is
reproducible from battery to battery. Receiving area 98 has
indentations which lock feedthrough pin 66 into receiving area 98.
Insulator 62 provides for slot 108 to provide a fixed location for
weld plate 74. Insulator 62 provides raised portion 90 which
provides an air gap and keeps insulator 62 away form the weld areas
joining the case 42 to cover 46 to prevent any melting of insulator
62. Insulator 62 provides openings 102 and 104 for the manufacturer
to easily weld tabs 50 and 52 to pin 66 and bracket 74
respectively. Insulator 62 isolates the different polarities of
battery 40, by creating a physical barrier between tab 50/pin 66
and tab 52/bracket 74/case 42/cover 46. Insulator 62 is fixed with
respect to feedthrough pin 66 and tabs 50 and 52, which allows for
reproducible and mechanically robust welds. insulator 62, when
assembled with electrode assembly 44 and coil insulator 54, forms
an assembly that can be inserted into case 42 without distorting or
bending feedthrough pin 66 or tabs 50 and 52.
[0047] It will be appreciated the present invention can take many
forms and embodiments. The true essence and spirit of this
invention are defined in the appended claims, and it is not
intended the embodiment of the invention presented herein should
limit the scope thereof.
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