U.S. patent application number 11/279298 was filed with the patent office on 2006-11-23 for method and apparatus for providing a sealed container containing a detectable gas.
Invention is credited to Nicolas Canaple, Michael F. Pyszczek.
Application Number | 20060260713 11/279298 |
Document ID | / |
Family ID | 37499282 |
Filed Date | 2006-11-23 |
United States Patent
Application |
20060260713 |
Kind Code |
A1 |
Pyszczek; Michael F. ; et
al. |
November 23, 2006 |
Method and apparatus for providing a sealed container containing a
detectable gas
Abstract
An apparatus for making a hermetic device containing a
detectable gas and comprising a surface having a fill port
comprising a vacuum pump in communication with the hermetic device
through a vacuum conduit; a liquid reservoir for containing liquid
to be delivered to the hermetic-device; a gas reservoir for
containing a detectable gas to be delivered to the hermetic device;
a transfer vessel for transferring a selected quantity of liquid
and gas to the hermetic device; and a block for passing the
selected quantity of liquid and gas through a fill port of the
hermetic device, and disposing a seal into the fill port. A method
for making a hermetic device containing a detectable gas, and an
exemplary hermetic device comprising an electrochemical cell or a
capacitor are also disclosed.
Inventors: |
Pyszczek; Michael F.;
(Leroy, NY) ; Canaple; Nicolas; (West Seneca,
NY) |
Correspondence
Address: |
GREATBATCH LTD
9645 WEHRLE DRIVE
CLARENCE
NY
14031
US
|
Family ID: |
37499282 |
Appl. No.: |
11/279298 |
Filed: |
April 11, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60673514 |
Apr 22, 2005 |
|
|
|
Current U.S.
Class: |
141/311R |
Current CPC
Class: |
H01M 10/4235 20130101;
H01M 50/183 20210101; H01M 50/60 20210101; H01M 6/5083 20130101;
H01M 10/4228 20130101; Y02E 60/10 20130101; H01M 50/636 20210101;
H01G 9/08 20130101; Y02E 60/13 20130101; H01G 13/04 20130101; H01M
10/4285 20130101; H01M 50/172 20210101 |
Class at
Publication: |
141/311.00R |
International
Class: |
B65B 1/04 20060101
B65B001/04 |
Claims
1. An apparatus for making a hermetic device containing a
detectable gas, the hermetic device comprising a surface including
a fill port therethrough, and the apparatus comprising: a) a vacuum
pump in communication with the hermetic device through a vacuum
conduit; b) a liquid reservoir for containing liquid to be
delivered to the hermetic device; c) a gas reservoir for containing
a detectable gas to be delivered to the hermetic device; d) a
transfer vessel comprised of a housing having a proximal end, a
distal end, and an inner bore; a piston disposed in the inner bore
and operatively connected to a linear actuator by a rod extending
through the proximal end; a discharge port disposed in the distal
end of the housing and connectable to the hermetic device through a
discharge conduit; a first inlet port in the housing in
communication with the liquid reservoir through a liquid conduit,
and a venting port in the housing; e) a block comprising a sealing
surface contactable with the surface of the hermetic device
including the fill port therethrough; a gasket disposable between
the sealing surface and the surface of the device; a discharge
passageway formed in the sealing surface and connectable with the
fill port of the hermetic device; a transfer port in communication
with the discharge passageway and in communication with the
discharge port of the transfer vessel; a seal holding cavity
alignable with the fill port of the hermetic device; a ramrod
alignable with the fill port of the hermetic device, the ramrod
having a distal end disposed in the seal holding cavity, a central
region extending through a bore in a wall of the block, and a
proximal end outside of the block; and f) a fastener adapted to
secure the block to the hermetic device.
2. The apparatus as recited in claim 1 wherein the gas reservoir is
in communication with the transfer vessel through a gas conduit
connected to a second inlet port provided in the housing of the
transfer vessel.
3. The apparatus as recited in claim 1 wherein the vacuum pump is
in communication with the transfer vessel.
4. The apparatus as recited in claim 1 further comprising a three
way valve connected to the discharge conduit of the transfer
vessel, the vacuum conduit, and a common conduit in communication
with the transfer port of the block.
5. The apparatus as recited in claim 1 wherein the liquid reservoir
comprises a receiver vessel including a wall, a bottom, and a sharp
conduit stub in communication with the liquid conduit; and a sealed
container containing a pre-selected amount of liquid to be
delivered to the hermetic device, the sealed container adapted to
be fit in the receiver vessel and comprising a wall, an upper
sealing membrane, and a lower sealing membrane puncturable by the
sharp conduit stub when the sealed container is fitted in the
receiver vessel.
6. The apparatus as recited in claim 1 further comprising a
programmable controller.
7. The apparatus as recited in claim 1 further comprising means for
contacting and dissolving the detectable gas in the liquid to be
delivered to the hermetic device.
8. An apparatus for making a hermetic device containing a
detectable gas, the apparatus comprising: a) a vacuum pump in
communication with the hermetic device through a vacuum conduit; b)
a liquid reservoir for containing liquid to be delivered to the
hermetic device; c) a gas reservoir for containing a detectable gas
to be delivered to the hermetic device; d) means for transferring a
selected quantity of liquid and gas to the hermetic device; and e)
means for passing the selected quantity of liquid and gas through a
fill port of the hermetic device, and disposing a seal into the
fill port.
9. A method for making a hermetic device containing a detectable
gas, the hermetic device comprising a surface including a fill port
therethrough, the method comprising the steps of: a) providing an
apparatus comprising a vacuum pump in communication with the
hermetic device through a vacuum conduit; a liquid reservoir for
containing liquid to be delivered to the hermetic device; a gas
reservoir for containing a detectable gas to be delivered to the
hermetic device; means for delivering a selected quantity of liquid
and detectable gas to the hermetic device; and means for passing
the selected quantity of liquid and the detectable gas through a
fill port of the hermetic device, and discharging a seal disposed
therein into the fill port; b) fastening to the hermetic device the
means for passing the selected quantity of liquid and the
detectable gas and discharging the seal; c) evacuating the hermetic
device; d) delivering the selected quantity of liquid and the
detectable gas into the hermetic device; and e) disposing the seal
in the fill port of the hermetic device.
10. The method as recited in claim 9 wherein the means for
delivering a selected quantity of liquid and gas to the hermetic
device comprises a transfer chamber.
11. The method as recited in claim 10 further comprising the step
of evacuating the transfer chamber.
12. The method as recited in claim 10 further comprising the step
of delivering a selected quantity of liquid to the transfer chamber
prior to delivering the selected quantity of liquid to the hermetic
device.
13. The method as recited in claim 12 further comprising the step
of delivering a selected quantity of the detectable gas to the
transfer chamber prior to delivering the selected quantity of
liquid and selected quantity of the detectable gas to the hermetic
device.
14. The method as recited in claim 9 further comprising the step of
dissolving the detectable gas in the liquid prior to delivering the
selected quantity of liquid and gas into the hermetic device.
15. An electrical energy storage device, which comprises: a) a
container comprised of: i) an enclosing container side wall having
a thickness and defining an interior space; ii) a surface including
an opening in the container side wall, the opening defined by an
opening perimeter; and iii) a seal sealing the opening; b) an
anode; c) a cathode; d) an electrolyte contacting the anode in
electrochemical association with the cathode housed in the interior
space of the container; and e) a detectable dissolved in the
electrolyte, detectable gas being selected from the group
consisting of helium, argon, neon, krypton, xenon, and mixtures
thereof.
16. The electrical energy storage device of claim 15 wherein the
detectable gas is dissolved in the electrolyte to its saturation
point.
17. The electrical energy storage device of claim 15 wherein the
detectable gas is not dissolved in the electrolyte.
18. The electrical energy storage device of claim 15 wherein the
detectable gas is comprised of at least about 99.9 weight percent
helium.
19. The electrical energy storage device of claim 15 wherein the
seal is comprised of a sealing member in a sealing relationship
with the opening perimeter to block the opening.
20. The electrical energy storage device of claim 15 wherein the
seal is comprised of a portion of the container side wall that has
been rendered molten and then cooled to fuse the side wall material
together to block the opening.
Description
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS
[0001] This application claims priority from U.S. Provisional
Application Ser. No. 60/673,514, filed Apr. 22, 2005, the
disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention generally related to quality control
of hermetic devices and, more particularly, to leak detection of
sealed enclosures to ensure their hermeticity after completion of
manufacturing. Leak detection is enabled by providing a detectable
gas within the container during the hermetic device manufacturing
process. Confirming hermeticity is critical for any sealed
enclosure, especially one housing an electrical power source for an
implantable medical device. The power source can be either an
electrochemical cell or a capacitor.
[0004] In either case, the power source includes a negative
electrode and a positive electrode physically segregated from each
other by a separator and provided with an electrolyte. The specific
chemistry of the cell or capacitor is not limited. For example, the
cell can be of either a primary chemistry such as of a
lithium/silver vanadium oxide or lithium/fluorinated carbon
(CF.sub.x) couple or of a secondary chemistry such as a lithium ion
cell and the capacitor could be a wet tantalum electrolytic
type.
[0005] 2. Description of Related Art
[0006] One industry standard for testing the hermeticity of sealed
enclosures is based on helium detection. In this test, the
enclosure is placed in a bombing chamber pressurized with helium. A
typical pressure is 100 psi and resident time is from one hour to
several days. If a leak exists, helium is forced into the void
volume of the enclosure. The time and pressure chosen depend on the
leak size to be measured and the size of the void volume in the
enclosure. After the prescribed time, the enclosure is removed from
the bombing chamber and put in a vacuum leak detector where the
presence of helium indicates a leak.
[0007] This helium detection method is described in U.S. Patent
Application Pub. No. 2005/0079620 to Eberhard et al., which is
assigned to the assignee of the present invention and incorporated
herein by reference. Reference may also be had to ASTM
International Standard F2391-05, "Standard Test Method for
Measuring Package and Seal Integrity Using HELIUM as the Tracer
Gas."
[0008] The method of leak testing in which a bombing chamber is
used is cumbersome and expensive to perform. It requires that the
bombing chamber with a helium source be provided as a separate
apparatus in the cell or capacitor manufacturing operation, and
that separate steps be performed to place the finished electrical
energy storage devices in the bombing chamber, pressurize the
chamber with helium for a period of time (of up to several days),
depressurize the bombing chamber, and move the helium-treated
devices to a helium detection apparatus. These steps are performed
solely for the purpose of infusing a small subset of non-hermetic
(defective) cells or capacitors in a production batch with helium
so that they can be identified in the subsequent helium leak test.
The bombing operation is thus disadvantaged because it requires
additional labor and capital equipment on the cell manufacturing
line, and it reduces the throughput of the line.
SUMMARY OF THE INVENTION
[0009] There is, therefore, need for a method and apparatus for
infusing electrical energy storage device containers with helium or
another detectable gas in the manufacturing process, which requires
minimal capital and labor costs and which has a high production
throughput.
[0010] Accordingly, embodiments of the present invention are
provided that meet at least one or more of the following objects of
the present invention.
[0011] It is an object of this invention to provide a method and
apparatus for infusing a hermetic device with a detectable gas
during the device fabrication process.
[0012] It is an object of this invention to provide a device that
is infused with a detectable gas and hermetically sealed during the
device fabrication process.
[0013] According to the present invention, therefore, an apparatus
for making a hermetic device containing a detectable gas and
comprising a surface having a fill port is provided. The apparatus
comprises a vacuum pump in communication with the hermetic device
through a vacuum conduit; a liquid reservoir for containing liquid
to be delivered to the hermetic device; a gas reservoir for
containing a detectable gas to be delivered to the hermetic device;
means for transferring a selected quantity of liquid and gas to the
hermetic device; and means for passing the selected quantity of
liquid and gas through a fill port of the hermetic device, and
disposing a seal into the fill port.
[0014] The means for transferring a selected quantity of liquid and
gas to the hermetic device may be comprised of a transfer vessel
including a housing having a proximal end, a distal end, and an
inner bore; a piston disposed in the inner bore and operatively
connected to a linear actuator by a rod extending through the
proximal end; a discharge port disposed in the distal end of the
housing and connectable to the hermetic device through a discharge
conduit; a first inlet port in the housing in communication with
the liquid reservoir through a liquid conduit, and a venting port
in the housing.
[0015] The means for passing the selected quantity of liquid and
gas through a fill port of the hermetic device, and disposing a
seal into the fill port may be comprised of a block including a
sealing surface contactable with the surface of the hermetic device
including the fill port therethrough; a gasket disposable between
the sealing surface and the surface of the device; a discharge
passageway formed in the sealing surface and connectable with the
fill port of the hermetic device; a transfer port in communication
with the discharge passageway and in communication with the
discharge port of the transfer vessel; a seal holding cavity
alignable with the fill port of the hermetic device; a ramrod
alignable with the fill port of the hermetic device, the ramrod
having a distal end disposed in the seal holding cavity, a central
region extending through a bore in a wall of the block, and a
proximal end outside of the block. One or more fasteners are
preferably used to secure the block to the hermetic device in order
to attain a temporary seal between the block and the surface of the
hermetic device.
[0016] In one preferred embodiment, the gas reservoir is in
communication with the transfer vessel through a gas conduit
connected to a second inlet port provided in the housing of the
transfer vessel. The vacuum pump may also be in communication with
the transfer vessel for the purpose of evacuating it before the
transfer of liquid thereto, preferably through a venting conduit
and a venting port in the housing of the transfer vessel. A
three-way valve may be used to easily switch between the connection
of the hermetic device to the vacuum pump, and the connection of
the hermetic device to the transfer vessel.
[0017] The liquid reservoir may be comprised of a simple tank with
a liquid conduit from the transfer vessel connected thereto.
Alternatively, the liquid reservoir may be comprised of a receiver
vessel including a wall, a bottom, and a sharp conduit stub in
communication with the liquid conduit.
[0018] The receiver vessel may be shaped to accept a sealed
container containing a pre-selected amount of liquid to be
delivered to the hermetic device. The sealed container comprises a
wall, an upper sealing membrane, and a lower sealing membrane. When
the sealed container is fitted into the receiver vessel, the lower
sealing membrane is punctured by the sharp conduit stub, thereby
connecting the sealed container to the transfer vessel.
[0019] The apparatus preferably further comprises various valves in
the vacuum conduit, the fluid conduit, the vent conduit, and the
gas conduit. These valves are preferably electrically or
pneumatically actuated, and are adapted to be connected to a
programmable logic controller that is provided for automatic
control of the apparatus.
[0020] In another embodiment, the gas reservoir is in communication
with the liquid reservoir, and the apparatus is further comprised
of means for contacting and dissolving the detectable gas in the
liquid to be delivered to the hermetic device, such as a sparger
immersed in the liquid reservoir.
[0021] Also according to the present invention, a method for making
a hermetic device containing a detectable gas is provided
comprising the steps of first providing an apparatus comprising a
vacuum pump in communication with the hermetic device through a
vacuum conduit; a liquid reservoir for containing liquid to be
delivered to the hermetic device; a gas reservoir for containing a
detectable gas to be delivered to the hermetic device; means for
delivering a selected quantity of liquid and gas to the hermetic
device; and means for passing the selected quantity of liquid and
gas through a fill port of the hermetic device, and discharging a
seal disposed therein into the fill port. The method further
comprises the steps of connecting the means for passing the
selected quantity of liquid and gas and discharging the seal to the
hermetic device; evacuating the hermetic device; delivering the
selected quantity of liquid and gas into the hermetic device; and
disposing the seal in the fill port of the hermetic device.
[0022] In the instances wherein means for delivering a selected
quantity of liquid and gas to the hermetic device comprises a
transfer chamber, the method may also include the step of
evacuating the transfer chamber and/or the step of delivering a
selected quantity of liquid to the transfer chamber prior to
delivering the selected quantity of liquid to the hermetic
device.
[0023] The method may include the step of delivering a selected
quantity of gas to the transfer chamber prior to delivering the
selected quantity of liquid and selected quantity of gas to the
hermetic device, or the step of dissolving the detectable gas in
the liquid prior to delivering the selected quantity of liquid and
gas into the hermetic device.
[0024] At the conclusion of the method, the means for passing the
selected quantity of liquid and gas and discharging the seal to the
hermetic device are unfastened and removed from the device.
[0025] Although the method and apparatus are adaptable to making a
wide range of hermetic devices containing a detectable gas, they
are directed in particular to the making of hermetic capacitors or
electrochemical cells containing a detectable gas, which may be
detected in subsequent leak testing of the capacitors or cells.
[0026] Accordingly, there is also provided an electrochemical cell
or capacitor including a container comprised of an enclosing
container side wall having a thickness and defining an interior
space intended to contain a liquid; a surface including an opening
in the container side wall; and a seal blocking the opening. Within
the container, the cell further comprises an anode, a cathode, an
electrolyte and a gaseous cavity within the container including a
detectable gas.
[0027] By the term "detectable gas" is meant a gas, whether
dissolved in the electrolyte, or not, that is not present in air in
more than a trace amount. Air essentially comprises nitrogen and
oxygen. There are also gases such as carbon dioxide and carbon
monoxide, among others, present in air. Therefore, the presence of
the detectable gas outside the confines of the container means that
the container is, in fact, not hermetically sealed. The detectable
gas may be selected from the group consisting of helium, argon,
neon, krypton, xenon, and mixtures thereof. The detectable gas in
the gaseous cavity is preferably helium, and is preferably present
at a saturation concentration. At a saturation concentration, there
is no pressure change inside the container attributed to the
detectable gas. Electrolyte filing typically occurs at about 5
psig. This pressure is allowed to bleed off before the cell is
hermetically closed under ambient pressure.
[0028] This is not to say that the pressure inside the container
will never change during the discharge life of the cell. On the
contrary, there can be some increase or decrease in internal
pressure attributed to electrolyte decomposition and discharge or
cycling of active materials. For example, carbonate-based solvents
are known to decompose and produce carbon dioxide with an attendant
increase in internal pressure above the ambient closing
pressure.
[0029] The foregoing and additional objects, advantages, and
characterizing features of the present invention will become
increasingly more apparent upon a reading of the following detailed
description together with the included drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] The present invention will be described by reference to the
following drawings, in which like numerals refer to like elements,
and in which:
[0031] FIG. 1 is a perspective view of one embodiment of an
electrochemical cell hermetic device;
[0032] FIG. 2 is a cross-sectional view of the electrochemical cell
of FIG. 1, taken along line 2-2 of FIG. 1;
[0033] FIG. 3 is a cross-sectional view of the fill port seal of
the electrochemical cell of FIG. 1, taken along line 3-3 of FIG.
1;
[0034] FIG. 4 is a first alternative fill port seal that may be
used in place of the seal of FIG. 3;
[0035] FIG. 5 is a second alternative fill port seal that may be
used in place of the seal of FIG. 3;
[0036] FIG. 6 is a cross-sectional view of another embodiment of a
fill port being sealed by means of a laser melting the material of
the side wall surrounding the fill port.
[0037] FIG. 7A is a first schematic illustration of an apparatus
for infusing electrolyte and a detectable gas into an
electrochemical cell, and sealing the electrochemical cell; FIG. 7A
also shows performing the step of evacuating the electrochemical
cell;
[0038] FIG. 7B is a second schematic illustration of the apparatus
of FIG. 7A, performing the step of partially filling a transfer
vessel with electrolyte;
[0039] FIG. 7C is a second schematic illustration of the apparatus
of FIG. 7A, performing the step of partially filling a transfer
vessel with helium;
[0040] FIG. 7D is a second schematic illustration of the apparatus
of FIG. 7A, performing the step of injecting the electrolyte and
helium gas into the electrochemical cell; and
[0041] FIG. 8 is a detailed cross-sectional view of one means for
passing a selected quantity of liquid and gas through a fill port
of and electrochemical cell and for deploying a seal into the
filling port after filling the cell with electrolyte and helium
gas.
[0042] The present invention will be described in connection with a
preferred embodiment, however, it will be understood that there is
no intent to limit the invention to the embodiment described. On
the contrary, the intent is to cover all alternatives,
modifications, and equivalents as may be included within the spirit
and scope of the invention as defined by the appended claims.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0043] For a general understanding of the present invention,
reference is made to the drawings. In the drawings, like reference
numerals have been used throughout to designate identical
elements.
[0044] The present invention is directed to methods and apparatus
for making a hermetic device containing a detectable gas. A device
fabricated according to the methods and apparatus of the present
invention may subsequently be placed in a testing device which is
capable of detecting the detectable gas, and thus confirming that
the device is hermetic, or is not hermetic, and therefore is
defective.
[0045] Referring now to the drawings, FIG. 1 shows a perspective
view and FIG. 2 shows a cross-sectional view of an exemplary
electrochemical cell 10 as a hermetic device provided with hermetic
sealing means, for example, spherical shaped sealing member 12.
While cell 10 is shown having a half-rounded shape, it will be
readily apparent to those skilled in the art that in their broadest
form such hermetic sealing means and the method and apparatus of
the present invention are useful with all types and kinds of closed
containers intended to hermetically hold a fluid (both in the
gaseous and liquid form), independent of the spatial orientation of
the container. The closed containers can have various shapes and
sizes, and illustrative cell 10 should not be considered as
limiting the present invention only to electrochemical cells. In
that respect, the hermetic sealing means of the present invention
is useful for providing a gas tight, hermetic seal in any opening
in a container having any shape and size, including but not limited
to e.g., capacitors, material sample vials, sensors, audio devices,
and imaging devices. Further, the method and apparatus of the
present invention are readily adapted for closing electrochemical
cells having various types of chemistries such as alkali
metal/solid cathode or alkali metal/oxyhalide electrochemical cells
of both the solid cathode and liquid catholyte types.
[0046] As shown in FIG. 1, exemplary electrochemical cell 10
includes a casing 14 having spaced-apart front and back side walls
16 and 18 joined by curved end walls 20 and 22 and a curved bottom
wall 24. The open top of the casing 14 is closed by a lid 26. The
lid has an opening 28 that serves as a port for filling the casing
14 with electrolyte after the cell internal components have been
assembled therein and lid 26 has been welded to the casing 14. In
its final and fully assembled condition, the sealing member 12 is
hermetically secured in the electrolyte fill opening 28 to close
the cell in a gas tight manner. The casing 14, lid 26 and sealing
member 12 are preferably of a conductive material. Suitable
materials include nickel, aluminum, stainless steel, mild steel,
nickel plated mild steel and titanium. Preferably, the casing 14,
lid 26 and sealing member 12 are of the same material.
[0047] A terminal lead 30 for either the anode or the cathode is
electrically insulated from the lid 26 and the casing 14 by a
glass-to-metal seal 32. In a case-negative cell configuration, the
lead 30 serves as the cathode terminal and the lid 26 and casing 14
serve as the negative or anode terminal, as is well known to those
skilled in the art.
[0048] Referring now to FIG. 2, exemplary cell 10 is of the liquid
electrolyte type comprised of a cathode electrode having a body 34
of solid cathode material in the form of plates 36, 38 pressed
together and bonded against a cathode current collector 40. The
cathode active material is preferably comprised of a metal, a metal
oxide, a mixed metal oxide or a metal sulfide, and the cathode
current collector 40 is fabricated from a thin sheet of metal.
Suitable materials for the current collector include nickel,
aluminum, stainless steel, mild steel and titanium.
[0049] Cell 10 further includes an anode electrode, generally
designated 42, comprising a unitary, conductive member 44 which
serves as the anode current collector and is fabricated from a thin
sheet of metal such as nickel, having a pair of wing-like sections
46 and 48 joined by an intermediate web section 50. Anode elements
52 and 54 are in pressure bonded contact with and carried by
corresponding ones of the electrode wing-like sections 46 and 48,
respectively.
[0050] The anode element 52 is in operative contact with the
cathode plate 36 through a thin sheet of separator material 56.
Similarly, anode element 54 is in operative contact with cathode
plate 38 through a thin sheet of separator material 58 such that
separator sheets 56 and 58 surround and envelope the cathode body
34 to prevent direct physical contact with the anode plates 52,
54.
[0051] The terminal lead 30 connected to the cathode current
collector 40 extends through a header assembly comprising the
glass-to-metal seal 32 fitted in the lid 26. Lead 30 is the
positive electrical terminal, being connected to the cathode body
34. With the anode 42 being in operative contact with the
conductive casing 14 through the web section 50 of the anode
current collector in electrical contact with the lid 26 welded to
the casing 14, the exemplary cell 10 is in a case-negative
electrical configuration.
[0052] Cell 10 is completed by a liquid electrolyte 60 provided in
casing 14 to activate the anode and the cathode. Electrolyte 60 is
hermetically sealed in the casing 14 closed by lid 26 by the
provision of the sealing member 12.
[0053] FIG. 3 is a cross-sectional view of the fill port seal of
the electrochemical cell of FIG. 1, taken along line 3-3 of FIG. 1.
In one embodiment, the spherically shaped sealing member 12 is
sized to be force-fit into sealing registry with the electrolyte
fill opening 28 to form a secondary seal for the cell 10 until such
time as the primary cell seal is formed by welding member 12 to the
side wall 62 defining and surrounding the opening 28. In other
words, the circumference of the side wall 62 surrounding the fill
opening 28 is dimensioned and disposed to be similarly shaped but
somewhat less in circumference than that of the spherically-shaped
sealing member 12. Then, as the sphere is force-fit into the
opening 28, the circumference of the side wall 62 is expanded by
this force-fit insertion so that the reactive stress force for
recovering the fill opening side wall 62 to its original
circumference is applied to the contact area of sphere 12 thereby
providing the secondary seal between the sphere and the opening
side wall 62. Further, the side wall 62 is provided with a slight
funnel taper 66 adjacent to the inside of the lid which prevents
the sphere 12 from being inserted too far into the opening 28 while
insuring that a projecting bulbous or protrusion portion of the
sphere is flush or slightly recessed with respect to the upper
surface of the lid 26 and is accessible from outside the cell.
Thus, with the sealing sphere in its secondary sealing engagement
with the side wall 62, the protruding portion faces outside the
cell 10 and is easily accessible therefrom. To form the primary
seal and thereby hermetically close the cell, the outwardly
projecting protruding portion of sealing member 12 is fused to
surrounding side wall 62 such as by means of weld 70 in a gas
tight, hermetic engagement.
[0054] By way of example, the illustrative cell 10 shown in FIGS. 1
and 2 can comprise an alkali metal electrochemical cell having a
lithium anode in operative association with a solid cathode. In
that case, the cathode is comprised of silver vanadium oxide
material as described in U.S. Pat. Nos. 4,310,609 and 4,391,729 to
Liang et al., or copper silver vanadium oxide as described in U.S.
Pat. Nos. 5,472,810 and 5,516,340 to Takeuchi et al., all assigned
to the assignee of the present invention, the disclosures of which
are hereby incorporated by reference. Cathode current collector 40
is of titanium and terminal lead 30 is of molybdenum; separators
56, 58 are of polypropylene; electrolyte 60 is a 1.0M to 1.4M
solution of LiAsF.sub.6 or LiPF.sub.6 in a 50:50 mixture of, by
volume, 1, 2-dimethoxyethane and propylene carbonate; glass seal 32
is of TA-23 Hermetic sealing glass; and the sealing member 12, the
casing 14 and the lid 26 are of stainless steel. Further details
regarding electrochemical cell 10, and the primary and secondary
seals as depicted in FIG. 3 are provided in U.S. Pat. No. 6,361,898
to Honegger, which is assigned to the assignee of the present
invention and incorporated herein by reference.
[0055] In accordance with the present invention, the
electrochemical cell 10 is filled through fill port 28 with
electrolyte 60, and a detectable gas using the apparatus and
methods of the present invention, which are described subsequently
in this specification. The detectable gas is preferably delivered
into the cell dissolved in the liquid electrolyte although it may
be as a separate gas phase, or both.
[0056] Following completion of the process of sealing the cell and
enclosing the detectable gas therein, the electrochemical cell 10
is tested to determine if a satisfactory hermetic seal was achieved
by placing the cell in an instrument that is capable of sensing the
presence of the detectable gas. In the instrument, the detectable
gas will only be present if it is leaking from the cell, and thus
the presence of the gas indicates that a hermetic seal of the cell
was not attained. In one preferred embodiment, the detectable gas
is helium, and the gas detection instrument and method may be as
described in the previously discussed U.S. Patent Application Pub.
No. 2005/0079620 to Eberhard et al., or as described in ASTM
International Standard F2391-05.
[0057] The apparatus and method the present invention may be
adapted to fill port seals having alternative configurations. FIG.
4 is a first alternative fill port seal that may be used in place
of the seal of FIG. 3. FIG. 5 is a second alternative fill port
seal embodiment that may be used. Referring first to FIG. 4, a
metal sealing member 13 is fit into a fill aperture 80 comprising a
lower small diameter portion 82, a step 83, and an upper large
diameter portion 84. Sealing member 13 is comprised of a lower
frustoconical portion 15 which engages tightly in a secondary seal
with the sharp edge formed at the intersection of lower portion 82
and step 83 of aperture 80. Sealing member 13 further comprises an
upper cylindrical portion 19 which is disposed within upper portion
84 of aperture 80. A primary seal is subsequently formed between
upper cylindrical portion 19 and upper portion 84 by weld 21.
[0058] Referring now to FIG. 5, a fill aperture 80 is provided as
in the embodiment of FIG. 4. Spherical sealing member 12 is
disposed within lower portion 82 as has been described for sealing
member 12 of cell 10 of FIG. 3 to form a secondary seal.
Subsequently, a second sealing member 23 is installed in the upper
portion 84 of aperture 80, and a primary seal is subsequently
formed between sealing member 23 and upper portion 84 by weld
21.
[0059] Further details on these and other fill port seals that may
be adaptable to the use of the apparatus and methods of the present
invention are provided in U.S. Pat. No. 6,610,443 to Paulot et al.,
which is assigned to the assignee of the present invention and
incorporated herein by reference. It is also noted that this patent
discloses an electrochemical cell including a clamshell configured
casing with hermetic sealing means, and that the apparatus and
methods of the present invention are also applicable to providing a
detectable gas within such a cell.
[0060] In another embodiment of sealing the cell, the fill opening
is sealed without the provision of a sealing member. In this
embodiment, the lid 26 has a bore 81 of a diameter somewhat less
than the previously described electrolyte fill openings or
apertures 28 and 80 of lid 26. Instead of welding a sealing member
or plug into the bore 81, the bore is closed by heating the lid
material surrounding its perimeter with a laser 83. This causes the
side wall material to melt and form a seal 85 sealing the opening
when the molten material fuses together.
[0061] The apparatus and methods for making a hermetic device
containing a detectable gas will now be described with reference in
particular to FIGS. 7A-7D, and FIG. 8. Referring first to FIG. 7A,
apparatus 100 is used to fill a hermetic device such as
electrochemical cell 10 with a liquid and a detectable gas.
Apparatus 100 is comprised of a liquid supply 101, a detectable gas
supply 200, a vacuum system 300, means 400 for transferring a
selected quantity of liquid and gas to the electrochemical cell,
and means 500 for passing the selected quantity of liquid and gas
through a fill port of the electrochemical cell, and disposing a
seal into the fill port. Apparatus 100 may further include a
programmable logic controller 600 that is provided for automatic
control of the apparatus 100.
[0062] Liquid supply 101 is comprised of a liquid reservoir 110
that is connected to a conduit 132 for transferring liquid
contained therein to transfer vessel 401. Liquid supply 101 may
further comprise a control valve 134 disposed in liquid conduit 132
for on-off actuation of flow from liquid reservoir 110 to transfer
vessel 401, and a check valve 136 for preventing any backflow of
liquid or gas from transfer vessel 401 to valve 134 and/or liquid
reservoir 110. Liquid supply 101 may further comprise a pump (not
shown) for assisting in delivery of liquid to transfer vessel 401,
or directly to electrochemical cell 10.
[0063] In one embodiment, liquid reservoir 110 may be comprised of
a simple tank (not shown) for holding the liquid to be delivered to
electrochemical cell 10. In such an embodiment, liquid supply 101
may also comprise a flow meter and/or flow totalizer (not shown)
disposed in conduit 132 for measuring a selected quantity of fluid
to be transferred to electrochemical cell 10. In this embodiment,
conduit 132 may be connected to transfer vessel 401 as depicted in
FIG. 7A, or conduit 132 may be connected into conduit 502 for
delivery directly into electrochemical cell 10.
[0064] In an alternative embodiment depicted in FIG. 7A, the liquid
reservoir 110 may be comprised of a receiver vessel 112 including a
wall 114, a bottom 116, and a sharp conduit stub 118 in
communication with the liquid conduit 132. Receiver vessel 112 may
be shaped to accept a sealed container 122 containing a
pre-selected amount of liquid 90 to be delivered to the
electrochemical cell 10. The sealed container 122 comprises a wall
124, a bottom 126, a lower sealing membrane or septum 127 disposed
upon and sealed to opening 128, and an upper sealing membrane 123.
The headspace 121 in sealed container 122 may contain the same
detectable gas that is provided by gas supply 200. When the sealed
container 122 is fitted into the receiver vessel 112, septum 127 is
punctured by the sharp conduit stub 118, thereby connecting the
sealed container 122 to conduit 132 through opening 128.
[0065] Gas supply 200 is comprised of a gas reservoir 210 that is
connected to a conduit 232 for transferring detectable gas
contained in reservoir 210 to transfer vessel 401. Gas supply 200
may further comprise a control valve 234 disposed in gas conduit
232 for on-off actuation of flow from gas reservoir 210 to transfer
vessel 401, and a check valve 236 for preventing any backflow of
liquid or gas from transfer vessel 401 to valve 234 and/or gas
reservoir 210, and an additional valve and pressure regulator
assembly 238 connected to gas reservoir 210. In one embodiment, gas
reservoir 210 may be a standard commercial gas cylinder that is
capable of containing a gas and/or liquid phase at a pressure of
3,000 pounds per square inch or more.
[0066] In the preferred embodiment, the detectable gas contained in
gas reservoir 210 is helium of at least about 99.9 weight percent
purity. Helium is a preferred gas because it is commercially
available and detectable by known methods, and in particular
because it is highly fugitive due to its small molecular size. Thus
the ability to retain helium within a sealed container is
indicative of hermeticity. In alternative embodiments, other
detectable gases may be used, such as argon, neon, krypton, xenon,
and mixtures thereof.
[0067] Vacuum system 300 is comprised of a vacuum pump 310 driven
by motor 312 and connected to conduit 332, and a control valve 334
disposed in vacuum conduit 332. In the preferred embodiment
depicted in FIG. 7A, vacuum conduit 332 is connected to
electrochemical cell 10 through three way valve 336 and through
conduit 502 of the means 500 for passing the selected quantity of
liquid and gas through the fill port 28 of the electrochemical cell
10. In an early step of the method of the present invention, vacuum
system 300 is used to evacuate electrochemical cell 10 prior to
filling electrochemical cell 10 with electrolyte and detectable
gas. This is done by discharging any evacuated air or other gas in
electrochemical cell 10 out through discharge conduit 338. Vacuum
system may also include a trap (not shown) in conduit 332 for
trapping any traces of liquid and preventing such liquid from
reaching vacuum pump 310.
[0068] In one embodiment, vacuum system 300 may also be used to
evacuate transfer vessel 401 prior to the filling of the transfer
vessel with liquid from liquid supply 101. Referring again to FIG.
7A, vacuum system 300 further comprises conduit 342, which is
connected at tee 344 to vacuum conduit 332, and is connected to
transfer vessel 401 at venting port 442 in housing 410. When
control valve 346 in conduit 342 is opened, vacuum pump 310 will
evacuate transfer vessel 401, as well as cell 10.
[0069] In another embodiment (not shown), vacuum system 300 may be
provided with an alternatively ported valve in place of valve 336,
which allows evacuation of transfer vessel 401 and cell 10
simultaneously, or in sequence, and subsequently allows transfer of
liquid and gas from transfer vessel 401 to cell 10. In this
embodiment, it is not necessary to provide a dedicated vacuum
conduit 342 connected to venting port 442.
[0070] Referring again to FIG. 7A, and in one preferred embodiment,
the means 400 for transferring a selected quantity of liquid and
gas to the electrochemical cell 10 is comprised of a transfer
vessel 401 including a housing 410 having a proximal end 412, a
distal end 414, and an inner bore 416; a piston 420 disposed in the
inner bore 416 and operatively connected to a linear actuator 422
by a rod 424 extending through the proximal end 412; a discharge
port 432 disposed in the distal end of the housing and connectable
to the electrochemical cell 10 through a discharge conduit 434; a
first inlet port 436 in the housing 410 in communication with the
liquid reservoir 110 through liquid conduit 132, and a venting port
442 in the housing 410. Transfer vessel 401 is preferably also
provided with a second inlet port 438 in the housing 410 in
communication with the gas reservoir 210 through gas conduit
232.
[0071] Piston 420 is provided with suitable sealing means (not
shown) such as O-rings and/or lip seals around the circumference
thereof, so that when linear actuator 422 displaces piston 42
axially along bore 416, the entire volume of liquid and gas
contained therein is displaced through discharge port 432, with no
blow-by past piston 420. Linear actuator 422 may be comprised of
various known means for linear translation of an object, such as a
ball screw and stepper motor assembly, a linear stepper motor, a
hydraulic cylinder, and the like.
[0072] It will be apparent that other means 400 for transferring a
selected quantity of liquid and gas to the electrochemical cell may
be used instead of the transfer vessel and piston assembly of FIG.
7A. For example, one may use a flow meter and/or flow totalizer for
measuring the selected quantity of fluid to be transferred to
electrochemical cell 10, with a control valve used to start and
stop the flow of fluid. The flow may be provided by a pressure
source coupled to the fluid reservoir. The pressure source could be
the reservoir of the detectable gas. Alternatively, the flow could
be provided by a metering pump that is disposed in the fluid
conduit between the liquid reservoir 110 and the electrochemical
cell 10.
[0073] Referring again to FIG. 7A and also to FIG. 8 (which depicts
seal 12 having been fitted into fill port 28 of cell 10), the means
500 for passing the selected quantity of liquid and gas through a
fill port of the electrochemical cell 10, and disposing a seal 12
into the fill port 28 may be comprised of a block 510 including a
sealing surface 512 contactable with the surface 27 of the cell 10
including the fill port 28 therethrough; a gasket 514 disposable
between the sealing surface 512 and the surface 27 of the device; a
discharge passageway 520 formed in the sealing surface 512 and
connectable with the fill port 28 of the cell 10; a transfer port
522 in communication with the discharge passageway 520 and in
communication with the discharge port 432 of the transfer vessel
401; a seal holding cavity 524 alignable with the fill port 28 of
the cell 10; and a ramrod 530 alignable with the fill port 28 of
the cell 10. Ramrod 530 is comprised of a distal end 532 disposed
in the seal holding cavity 524 (prior to delivery of the seal 12
into fill port 28), a central region 534 extending through a bore
516 in a wall of the block, and a proximal end outside of the
block. Ramrod 530 is axially movable within bore 516 so that when
ramrod 530 is pushed inwardly, the distal end 532 of ramrod 530
forces seal 12 into fill port 28, thereby sealing fill port 28 as
described previously herein.
[0074] In the embodiment depicted in FIG. 8, ramrod 530 is
slidingly disposed in bore 516. A gasket 518 is provided to prevent
the flow of liquid or gas into or out of the interstitial space
between the central region 534 of ramrod 530 and bore 516 during
vacuum and filling operations. In another embodiment (not shown),
bore 516 may be provided with an extended length, with a portion
thereof being threaded, and a corresponding portion of the central
region 534 of ramrod 530 may also be threaded. Thus, by turning
ramrod 530 within bore 516, the seal 12 may be pushed downwardly
into fill port 28.
[0075] One or more fasteners are preferably used to secure block
510 to cell 10 in order to attain a temporary seal between surface
512 of block 510 and surface 27 of cell 10, and also to place
ramrod 530, seal holding cavity 524, seal 12, and fill port 28 in
alignment prior to the delivery of seal 12 into fill port 28. In
the embodiment depicted in FIGS. 7A and 8, fastener 550 is provided
to attain such sealing and alignment. Fastener 550 is an assembly
comprising a band 552 including a first side region 554 extending
along one side wall 16, a bottom region 556 extending around bottom
wall 24, and a second side region 558 extending along opposite
sidewall 18. The upper portion of first side region 554 of band 550
is temporarily secured to block 10 with one or more fasteners 562,
and upper portion of second side region 558 of band 550 is
temporarily secured to block 10 with one or more fasteners 564.
[0076] Fastener 550 is further provided with a thumb screw 566
threadedly engaged with bottom region 556 of band 550 and provided
with a pad 559 for contacting bottom wall 24 of cell 10. When thumb
screw 566 is screwed inwardly, pad 559 is forced against bottom
wall 24, applying a force indicated by arrow 599, which in turn
forces surface 512 of block 510 against surface 27 of cell 10,
thereby attaining a temporary seal between the surfaces.
[0077] The upper portions of first side region 554 and second side
region 558 of band 550 are provided with tabs 572 and 574
protruding inwardly, so that when fastener 550 is fastened to block
510 and engaged with cell 10, ramrod 530, seal holding cavity 524,
seal 12, and fill port 28 are placed in alignment. Although only
one plane of alignment is depicted in FIGS. 7A and 8, it will be
apparent that an additional band may be provided with fastener 550
in the orthogonal vertical plane to properly align the components
for fitting of the seal 12 in fill port 28.
[0078] When block 510 is fastened to cell 10, before seal 12 is
deployed in fill port 28, discharge passageway 520 is connected to
fill port 28 of cell 10. When vacuum is applied to conduit 502, gas
inside of cell 10 flows outwardly through fill port 28, through
discharge passageway 520, along the central region 534 of ramrod
530, through transfer port 522, and out through conduit 502 as
indicated by arrow 599. In like manner, when liquid electrolyte and
detectable gas are delivered in through conduit 502, they follow
the opposite path into cell 10..
[0079] Referring again to FIG. 7A, seal holding cavity 524 serves
to temporarily hold seal 12 within block 510, prior to the
deployment of seal 12 into fill port 28. In the embodiment depicted
therein, seal holding cavity 524 is provided in its lower region
with a ring 525 of elastomeric material that is partially embedded
in block 510. Prior to the fastening of block 510 to cell 10, the
spherical seal 12 can simply be pushed past ring 525 into seal
holding cavity 524. Ring 525 provides a weak force to hold seal 12
in place until ramrod 530 is used to force seal 12 into fill port
28. Alternatively, seal 12 may be provided with a coating or a
small spot of adhesive that will hold it in cavity 524 until
deployment into fill port 28.
[0080] The means 500 for disposing a seal 12 into the fill port 28
of cell 10 may also be used to dispose seal 12 into a fill port
having the stepped configuration depicted in FIG. 5 and previously
described herein. Additionally, means 500 may be adapted to dispose
the seal 13 of FIG. 4 into a fill port having a stepped
configuration. In such an embodiment, seal 13 is provided with a
threaded bore 86 (FIG. 4), and the distal end 532 of ramrod 530 is
correspondingly threaded so that ramrod 530 can be screwed into the
seal 13 when the seal is placed in block 510. Seal 13 can then be
pushed tightly into the stepped fill port of the cell, and ramrod
530 unscrewed and separated from seal 13.
[0081] Turning now to the fluid connections to block 510, in the
embodiment depicted in FIG. 7A, both the vacuum system 300 and the
transfer vessel 401 may be alternatingly in communication with cell
10, depending upon the position of the porting in three way valve
336. In another embodiment (not shown), block 510 may be provided
with a second transfer port so that vacuum system 300 and transfer
vessel 401 may be separately connected to cell 10.
[0082] Block 510 may also be provided with an additional port 528
for connection to a gauge 529 for monitoring the vacuum or pressure
within block 510 and cell 10.
[0083] As described previously, apparatus 100 preferably comprises
various valves 334, 134, 346, and 234 in the vacuum conduit, the
fluid conduit, the vent conduit, and the gas conduit, as well as
three-way valve 336. These valves are preferably electrically or
pneumatically actuated, and are adapted to be connected to a
programmable logic controller 600 that is provided for automatic
control of the apparatus and method for making the hermetic device.
Controller 600 is also connected to vacuum pump motor 312 and
linear actuator 422.
[0084] Although embodiments of the invention have been described
wherein the detectable gas is delivered to transfer vessel 401 and
subsequently into cell 10 as a separate phase following the
selected quantity of liquid electrolyte, it is not required that
the detectable gas be provided in this manner. Instead, in a
preferred embodiment (not shown) the gas reservoir 210 is in
communication with the liquid reservoir 110, and the apparatus is
further comprised of means for contacting and dissolving the
detectable gas in the liquid to be delivered to the hermetic
device, such as a sparger immersed in the liquid contained within
liquid reservoir 110. The detectable gas such as helium is
dissolved into the liquid electrolyte to its saturation point prior
to delivery into cell 10.
[0085] Also according to the present invention, a method for making
a hermetic device containing a detectable gas is provided.
Referring again to FIG. 7A, the method begins by providing
apparatus 100, and by fastening the means 500 for passing the
selected quantity of liquid and gas and discharging the seal to the
cell 10 as previously described herein and shown in FIG. 7A. Sealed
container 122 containing a pre-selected amount of liquid 90 to be
delivered is placed in receiver vessel as indicated by arrow 199,
puncturing septum 127 as described previously.
[0086] Three way valve 336 is actuated by controller 600 to place
vacuum system 300 in communication with cell 10. Vent valve 346 is
opened to place vacuum system 300 in communication with transfer
vessel 401. Vacuum pump 310 is started, and vacuum valve 334 is
opened. Electrochemical cell 10 and transfer vessel 401 are
evacuated to a pressure of at least about 100 milliTorr, and
preferably about 1.times.10.sup.-6 Torr. When evacuation of cell 10
and vessel 410 is complete, vent valve 346 is closed, and three way
valve 336 is closed, i.e. the porting of three way valve is
positioned so that neither vacuum system 300 or transfer vessel 400
are in communication with cell 10.
[0087] Referring to FIG. 7B, a selected quantity of fluid is
transferred from fluid reservoir 110 to transfer vessel 401. Liquid
valve 334 is opened, and with transfer vessel 401 having been
evacuated, liquid is drawn into transfer vessel from liquid
reservoir 110. The entire selected quantity of liquid contained in
sealed container 122 is transferred. In one embodiment (not shown),
upper seal 123 is an elastic seal and stretched downwardly as the
liquid drains from sealed container 122. Alternatively, sealed
container 122 may be pressurized with detectable gas, which expands
as the liquid is transferred. When the liquid transfer is complete,
liquid valve 334 is closed.
[0088] In another embodiment (not shown), it is not necessary to
evacuate transfer vessel 401 prior to filling it with liquid. In
this embodiment, a pump may be used to transfer the liquid from the
reservoir 110 to the vessel 401, or reservoir 110 may be
pressurized such that the liquid is pressure-fed into transfer
vessel 401. In either case, vent valve 346 is opened, and conduit
342 is not connected to vacuum pump 310, so that the air that is
displaced from vessel 401 during liquid filling is simply vented to
the atmosphere.
[0089] Referring to FIG. 7C, the remaining volume in transfer
vessel 401 is filled with detectable gas. The valve in regulator
assembly 238 is opened, gas valve 234 is opened, and the detectable
gas fills cavity 444 above liquid 90 in transfer vessel 401. In the
event that vessel 401 was not evacuated prior to filling with
liquid and gas, valve 346 is also opened. A sufficient amount of
detectable gas is delivered through cavity 90 so that the air
therein is purged to a point where the gas in the cavity is of
about the same composition as the detectable gas in reservoir 210.
When the delivery of gas to cavity 444 in vessel 401 is complete,
gas valve 234 is closed. It is noted that in the preferred method
where the detectable gas was previously dissolved in the liquid
contained in liquid reservoir 110, the step of delivering
detectable gas to transfer vessel 401 is not necessary.
[0090] Referring to FIG. 7D, the liquid and gas in transfer vessel
401 are transferred to cell 10. Three way valve 336 is actuated so
that the valve porting connects transfer vessel 401 to cell 10.
Linear actuator is operated, pushing piston 420 downwardly, thereby
displacing the liquid 90 and gas in cavity 444 into cell 10. When
piston 420 has fully displaced the liquid and gas from transfer
vessel 401, three way valve 336 is closed. It is noted that
alternate means 400 for transferring the selected quantity of
liquid and gas to the electrochemical cell (such as a pump or a
pressure vessel) as described previously may be used, with the same
result of filling of the cell 10 with liquid and the detectable gas
being achieved.
[0091] Seal 12 is then force-fit into fill port 28 of cell 10 as
indicated by arrow 598. Referring to FIG. 8, electrochemical cell
10 contains liquid electrolyte 60 in which cathode 34 and anode 42
are fully immersed. The detectable gas is at a saturation
concentration in the electrolyte. The detectable gas saturated
electrolyte preferably completely fills the cell container up to
the lid 26.
[0092] At the conclusion of the method, fastener 550 and means 500
for passing the selected quantity of liquid and gas and discharging
the seal to the cell 10 are removed from the cell. Within the
container 14, the resulting cell 10 comprises an anode 42 and a
cathode 34 physically segregated from each other by the separator
58 and activated with electrolyte 60 housed within the container
14. The detectable gas in the electrolyte is preferably helium,
although the other previously discussed gas can be used.
[0093] When the cell manufacturing process as described herein is
completed, the cell may be tested for leakage of the helium as
described previously in the aforementioned U.S. Patent Application
Pub. No. 2005/0079620 to Eberhard et al. No use of a bombing
chamber is needed as a pre-conditioning step before leak testing,
since the cell already contains helium that will be detected if a
hermetic seal was not achieved.
[0094] It is therefore apparent that there has been provided, in
accordance with the present invention, a method and apparatus for
making a hermetic device containing a detectable gas. While this
invention has been described in conjunction with preferred
embodiments thereof, it is evident that many alternatives,
modifications, and variations will be apparent to those skilled in
the art. Accordingly, it is intended to embrace all such
alternatives, modifications and variations that fall within the
spirit and broad scope of the appended claims.
* * * * *