U.S. patent application number 14/968815 was filed with the patent office on 2016-10-20 for hybrid thin-film battery.
The applicant listed for this patent is Sapurast Research, LLC. Invention is credited to Bernd J. Neudecker, Shawn W. Snyder.
Application Number | 20160308173 14/968815 |
Document ID | / |
Family ID | 38685525 |
Filed Date | 2016-10-20 |
United States Patent
Application |
20160308173 |
Kind Code |
A1 |
Neudecker; Bernd J. ; et
al. |
October 20, 2016 |
HYBRID THIN-FILM BATTERY
Abstract
An electrochemical device is claimed and disclosed wherein
certain embodiments have a cathode greater than about 4 .mu.m and
less than about 200 .mu.m thick; a thin electrolyte less than about
10 .mu.m thick; and an anode less than about 30 .mu.m thick.
Another claimed and disclosed electrochemical device includes a
cathode greater than about 0.5 .mu.m and less than about 200 .mu.m
thick; a thin electrolyte less than about 10 .mu.m thick; and an
anode less than about 30 .mu.m thick, wherein the cathode is
fabricated by a non-vapor phase deposition method. A non-vacuum
deposited cathode may be rechargeable or non-rechargeable. The
cathode may be made of CF.sub.x (carbon fluoride) material,
wherein, for example, 0<x<4. The electrochemical device may
also include a substrate, a current collector, an anode current
collector, encapsulation and a moderating layer.
Inventors: |
Neudecker; Bernd J.; (Los
Gatos, CA) ; Snyder; Shawn W.; (Cupertino,
CA) |
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Applicant: |
Name |
City |
State |
Country |
Type |
Sapurast Research, LLC |
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Family ID: |
38685525 |
Appl. No.: |
14/968815 |
Filed: |
December 14, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14041575 |
Sep 30, 2013 |
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14968815 |
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11748471 |
May 14, 2007 |
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14041575 |
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11687032 |
Mar 16, 2007 |
8236443 |
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11748471 |
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11561277 |
Nov 17, 2006 |
8445130 |
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11687032 |
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60782792 |
Mar 16, 2006 |
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60759479 |
Jan 17, 2006 |
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60737613 |
Nov 17, 2005 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 23/58 20130101;
H01M 2/26 20130101; H01M 6/40 20130101; H01M 10/0525 20130101; H01M
10/0585 20130101; Y02E 60/10 20130101; H01M 2/0207 20130101; H01M
2/08 20130101; H01L 2924/0002 20130101; H01M 10/052 20130101; H01M
10/0562 20130101; Y10T 29/49114 20150115; H01M 10/425 20130101;
H01M 2300/0068 20130101; Y10T 29/4911 20150115; Y02P 70/50
20151101; H01M 2220/30 20130101; H01M 10/0436 20130101; H01L
2924/0002 20130101; H01L 2924/00 20130101 |
International
Class: |
H01M 2/02 20060101
H01M002/02; H01M 2/08 20060101 H01M002/08; H01M 10/0585 20060101
H01M010/0585; H01M 10/0525 20060101 H01M010/0525; H01M 10/0562
20060101 H01M010/0562; H01M 10/42 20060101 H01M010/42; H01M 10/04
20060101 H01M010/04 |
Claims
1. An electrochemical device comprising: a non-vapor phase
deposited cathode; a layer on the cathode; an anode; and a vapor
phase deposited electrolyte deposited over the layer on said
cathode, wherein the anode is positioned over the vapor phase
deposited electrolyte.
2. The electrochemical device of claim 1, further comprising an
encapsulation layer deposited over said anode, the encapsulation
layer comprising a ceramic-metal composite laminate.
3. The electrochemical device of claim 2, wherein said
ceramic-metal composite laminate is multiple alternating layers of
(1) ceramic zirconium nitride and metal zirconium or (2) ceramic
titanium mitride and metal titanium.
4. The electrochemical device of claim 2, wherein said
ceramic-metal composite laminate comprises metallic sub-layers
comprising at least one element selected from the group consisting
of: zirconium and titanium.
5. The electrochemical device of claim 4, wherein said ceramic
sub-layers comprise nitrides.
6. The electrochemical device of claim 2, further comprising a
modulating layer between the encapsulation layer and the anode.
7. The electrochemical device of claim 2, wherein the encapsulation
layer is at the periphery of said electrochemical device.
8. The electrochemical device of claim 1, further comprising a
flexible circuit board, wherein said electrochemical device is
positioned on the flexible circuit board.
9. The electrochemical device of claim 1, wherein said cathode
comprises LiCoO.sub.2, said electrolyte comprises Lithium
Phosphorus Oxynitride (LiPON), and said anode comprises
Lithium.
10. The electrochemical device of claim 1, wherein said anode is
lithium.
11. The electrochemical device of claim 1, wherein said electrolyte
is Lithium Phosphorus Oxynitride (LiPON).
12. The electrochemical device of claim 1, wherein said cathode is
LiCoO.sub.2.
13. The electrochemical device of claim 1, further comprising a
substrate.
14. The electrochemical device of claim 1, wherein said electrolyte
is a thin-film electrolyte.
15. The electrochemical device of claim 1, wherein said electrolyte
comprises Lithium Phosphorus Oxynitride (LiPON).
16. The electrochemical device of claim 1, wherein said electrolyte
is deposited directly on said cathode.
17. The electrochemical device of claim 1, wherein said
electrochemical device is encapsulated with a material selected
from ceramic multi-layer thin-film encapsulate, polymer composite,
metal foil, adhesive, and metal can.
18. The electrochemical device of claim 1, wherein said
electrochemical device is encapsulated with an encapsulation grown
by a vacuum vapor phase process.
19. The electrochemical device of claim 18, wherein said
encapsulation consists of a multilayer stack of inorganic compounds
and metals.
20. The electrochemical device of claim 18, wherein said
encapsulation is separated from the negative anode by an interposed
modulation layer.
21. The electrochemical device of claim 1, further comprising a
cathode current collector.
22. The electrochemical device of claim 1, further comprising an
anode current collector.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of U.S. patent
application Ser. No. 14/041,575, filed Sep. 30, 2013, which is a
continuation of U.S. patent application Ser. No. 11/748,471, filed
May 14, 2007 (now Abandoned), which is a continuation of U.S.
patent application Ser. No. 11/687,032, filed Mar. 16, 2007 (issued
as U.S. Pat. No. 8,236,443), which is a continuation-in-part of
U.S. patent application Ser. No. 11/561,277, filed Nov. 17, 2006
(issued as U.S. Pat. No. 8,445,130), which claims the benefits of
the earlier filing dates of co-pending U.S. Provisional Application
No. 60/782,792, filed Mar. 16, 2006; U.S. Provisional Application
No. 60/759,479, filed Jan. 17, 2006; and U.S. Provisional
Application No. 60/737,613, filed Nov. 17, 2005, which are all
incorporated herein by reference in their entirety.
FIELD OF THE INVENTION
[0002] The field of this invention relates to electrochemical
devices and methods of manufacturing thereof, and more
particularly, the composition, method of depositing, and
fabrication of solid-state, thin-film, secondary and primary
electrochemical devices, including batteries.
BACKGROUND
[0003] Thick positive cathodes are good for creating energy-rich
thin-film batteries. A thick positive cathode substantially
increases the active cathode mass per unit area. Unfortunately,
producing such cathodes with typical vacuum vapor phase processes
has been problematic.
[0004] Cathodes made with a typical vacuum vapor phase method have
a number of limitations. For instance, vacuum vapor phase deposited
materials typically grow in columns as schematically shown in FIG.
1. This figure depicts schematically and in cross-sectional view
three microscopic columns, grown by a vacuum vapor phase deposition
method, of the positive cathode layer of an electrochemical device.
As the columns grow through the process, the bases of these columns
remain anchored to the substrate surface and the cross sectional
area of these bases remains virtually fixed as the height of the
columns grows. As the height of the columns increases, the aspect
ratio (height of column/width of column) increases and the cathode
film consisting of these columns and thus the entire device becomes
mechanically unstable, typically around an aspect ratio of 15.
Thus, there are limitations to the height, and therefore the
thickness, of columns grown with a vacuum deposition processes.
Limitations on the height directly correspond to the thickness of
the cathode and the energy of an electrochemical device per unit
area that can be produced using a vacuum vapor phase deposition
method. Furthermore, thick cathodes take a relatively long time to
grow using a vacuum vapor phase process and are, therefore, quite
expensive. For instance, LiCoO.sub.2 positive cathodes grown in a
vacuum vapor phase deposition method above about 3 .mu.m become
overly expensive because of their long deposition time.
[0005] Thus, there is demand for electrochemical devices whose
cathodes can be produced thick and reliably while being fabricated
quickly and inexpensively. Further, it would be desirable to
accomplish these demands using any of the many well-known non-vapor
phase deposition techniques and processes, such as slurry coating,
Meyer rod coating, direct and reverse roll coating, doctor blade
coating, spin coating, electrophoretic deposition, sol-gel
deposition, spray coating, dip coating, and ink-jetting, to name a
few.
[0006] Depositing a thicker cathode in order to increase the energy
of an electrochemical device per unit area results in an increased,
overall thickness of the device. Because an overall thickness
increase of a milli, micro, or nano device is typically
undesirable, the device manufacturer has to explore options of how
to compensate for or offset such a thickness increase. A generally
valid and desirable approach is to minimize the thickness and
volume of all of the non-energy providing components inside an
electrochemical device.
[0007] One of the options is to reduce the non-energy providing
packaging of an electrochemical device. Both the encapsulation and
the substrate are inherent and usually large, fractional parts of
the packaging.
[0008] For instance, the reduction of an encapsulation thickness
from 100 micrometers, which is a typical thickness for a laminate
encapsulation, to a true thin-film encapsulation in the range of
1-10 micrometers would allow the electrochemical device
manufacturer, for example, to increase the thickness of the energy
bearing cathode by almost 100 micrometers without any discernible
overall thickness change of the device. This design approach
substantially improves the volumetric quantities of energy,
capacity, and power of the electrochemical device. Because these
physical performance quantities are required to be delivered in the
smallest volume possible for most any milli, micro, or nano
electrochemical device, the reduction of the non-energy providing
components inside an electrochemical device is critically important
for its acceptance in the marketplace.
[0009] The other option is to fabricate an electrochemical device
onto the thinnest possible substrate, if used, traded or sold as a
standalone device. This is different from the non-standalone case
wherein the device manufacturer may exploit an existing, free
surface in an electronic device (chip surface, printed circuit
board surface, etc.) and then directly integrate, fabricate or
deposit the electrochemical device onto that free surface. This
surface then serves as the electrochemical device's substrate as
well. One may consider such an electrochemical device being
configured with a zero-thickness substrate because no further
substrate thickness was introduced by the electrochemical device
into the final electronic device. In the more common, standalone
case, however, the limits of substrate thinness are reached when it
does not provide adequate chemical and physical, mainly mechanical,
protection or functionality anymore to support the electrochemical
device. Because most vacuum deposited cathode materials require
high-temperature processing to fully develop all of their physical
properties, which in turn creates film stresses that are translated
into the substrate, the mechanical properties of these vacuum vapor
deposited cathode materials may challenge any substrate in terms of
mechanical deformation.
[0010] The typical result of vacuum vapor phase deposited films in
conjunction with high-temperature processing is a bending, warping,
or general deformation of the substrate and thus the entire
electrochemical device. If this situation occurs, then completing
the fabrication of the electrochemical device becomes difficult, in
addition to the mere fact that a deformed electrochemical device is
not well suited for device integration. In contrast, non-vapor
phase deposited cathode materials may be fabricated with most or
even all of their important physical properties already developed
at the time of deposition, so that any high-temperature processing
becomes redundant. Hence, non-vapor phase deposited cathode
materials and other components of an electrochemical device create
less stress in the substrate and allow the use of a thinner
substrate without the risk of substantially deforming it.
[0011] Accordingly, there is also a need for capsulation that
exhibits fairly high-temperature characteristics.
[0012] Thus, there is demand for an electrochemical device (i)
whose cathode can be produced thick and reliably while being
fabricated quickly and inexpensively, (ii) whose substrate
thickness is as thin as possible while not being deformed by the
component layers of the electrochemical device, (iii) whose
encapsulation is fabricated as thin as possible while still
providing adequate protection against the ambient in which these
devices are operated, and/or (iv) whose encapsulation is composed
of high-temperature materials that provide the entire
electrochemical device with increased thermal resilience.
SUMMARY
[0013] Various aspects and embodiments of the present invention, as
described in more detail and by example below, address certain of
the shortfalls of the background technology and emerging needs in
the relevant industries.
[0014] One aspect of the invention is an electrochemical device
comprising a positive cathode greater than about 0.5 .mu.m and less
than about 200 .mu.m thick; a thin electrolyte less than about 10
.mu.m thick; and an anode less than about 30 .mu.m thick. The
device may also comprise a substrate, current collectors,
terminals, a moisture protection layer, and an encapsulation. In an
embodiment of the invention, the cathode may be greater than about
5 .mu.m and less than about 100 .mu.m thick. The cathode may also
be greater than about 30 .mu.m and less than about 80 .mu.m
thick.
[0015] Another aspect of the invention is an electrochemical device
comprising a non-vapor phase deposited cathode, an anode, and an
electrolyte that is less than 10 .mu.m thick. In an embodiment of
the invention, the cathode may be greater than about 0.5 .mu.m and
less than about 200 .mu.m thick, and the anode may be less than
about 30 .mu.m thick.
[0016] A cathode in accordance with an aspect of an embodiment of
the invention may be non-vapor phase deposited. The cathode may be
deposited by one of the following methods: slurry coating, Meyer
rod coating, direct and reverse roll coating, doctor blade coating,
spin coating, electrophoretic deposition or ink-jetting.
[0017] The cathode may comprise LiCoO.sub.2, LiMn.sub.2O.sub.4,
LiMnO.sub.2, LiNiO.sub.2, LiFePO.sub.4, LiVO.sub.2, and any mixture
or chemical derivative thereof. Alternatively these cathode
materials may be doped with elements from the groups 1 through 17
of the periodic table.
[0018] In an embodiment, the electrolyte may comprise lithium
phosphorus oxynitride (LiPON). The electrolyte may comprise a
thin-film electrolyte. The electrolyte may be deposited by a vacuum
vapor phase growth method or non-vapor phase method.
[0019] The anode may comprise lithium, a lithium alloy or a metal,
which can form a solid solution or a chemical compound with
lithium, or a so-called lithium-ion compound suitable for use as a
negative anode material in lithium based batteries, such as, for
example, Li.sub.4Ti.sub.5O.sub.12.
[0020] In a further aspect of an embodiment of the invention, an
electrochemical device may also be encapsulated with an
encapsulation process selected from the group consisting of vacuum
vapor phase grown thin-film encapsulation, pressure-heat lamination
as described by Snyder et al. in U.S. Pat. No. 6,916,679, the
contents of which are hereby incorporated herein by reference in
its entirety, metal foil attachment, and metal canning.
[0021] The device may further comprise a cathode current collector
and an optional anode current collector on top or underneath of the
thin electrolyte layer. The electrolyte immediately underneath the
optional anode current collector may be protected by a moisture
barrier, such as ZrO.sub.2, if the encapsulation has an opening
that allows the optional anode current collector to be in direct
contact with ambient atmosphere.
[0022] According to an aspect of an embodiment of the present
invention, non-vapor phase fabrication methods may be used to form
a positive cathode, and the cathode combined with cell components
of an electrochemical device that are all, or in part fabricated by
vacuum vapor phase methods. Exemplary embodiments that utilize such
a combination of different methods are viewed as hybrid fabrication
methods and resulting devices, for example, a "hybrid thin-film
battery."
[0023] In another aspect of an embodiment of the invention, the
non-vapor phase fabrication of the positive cathode does not
require a high-temperature fabrication step, which limits the
stress development inside the component layer stack of an
electrochemical device. This in turn allows use of a thinner
substrate. Although thinner substrates may be prone to undesirable
deformation under a given magnitude of stress, tradeoffs from using
a thin substrate include a thinner electrochemical device for a
given energy, capacity, and power performance. In other words, the
use of a thinner substrate allows for increases in the volumetric
quantities of energy, capacity, and power of an electrochemical
device.
[0024] In another aspect, the cathode may be vacuum vapor phase
grown, or fabricated by a non-vapor phase method, and then may be
mechanically embossed or otherwise formed into structures that
increase its surface area within the same previously coated
footprint, but with resulting increased maximum thickness and
decreased minimum thickness. This structure or architecture
minimizes the average distance of any volume element inside the
cathode relative to the neighboring solid state thin-film
electrolyte layer, which, unlike in electrochemical devices with
gel or liquid type electrolytes, typically does not intimately
penetrate the cathode bulk. Therefore, minimizing the average
distance of any volume element inside the cathode relative to the
solid state thin-film electrolyte reduces the ionic diffusion
lengths during operation of the electrochemical device, which in
turn improves its power capability.
[0025] A further aspect of an embodiment of the invention involves
mixing electronic conducting material such as carbon into an
embossed or other surface-increased cathode structure to minimize
electronic diffusion lengths inside the cathode bulk to improve the
power capability of an electrochemical device.
[0026] In another aspect of an embodiment of the invention, an
electrochemical device includes a thin-film encapsulation
comprising or consisting of inorganic material that exhibits fairly
good high-temperature characteristics.
[0027] In another aspect of an embodiment of the invention, a
thin-film encapsulation is used to minimize the thickness
contribution of the encapsulation to the overall thickness of the
electrochemical device.
[0028] In another aspect, a thin encapsulation, such as a thin-film
encapsulation, can overcompensate or at least compensate in full,
or in part for any thickness increase of the cathode relative to
the overall thickness of the electrochemical device. In addition,
and compared with, for example, a pressure-heat laminate, the use
of a thinner encapsulation directly increases the volumetric
quantities of energy, capacity, and power of a given
electrochemical device.
[0029] In yet another aspect of an embodiment of the invention, a
thin-film encapsulation consists of multiple inorganic layers that
all exhibit intrinsic, high-temperature stability, a characteristic
that raises to some extent the temperature stability and resilience
of the entire electrochemical device.
BRIEF DESCRIPTION OF THE FIGURES
[0030] The accompanying drawings, which are included to provide a
further understanding of the invention and are incorporated in and
constitute a part of this specification, illustrate exemplary
embodiments of the invention that together with the description
serve to explain the principles of the invention. In the
drawings:
[0031] FIG. 1 schematically shows a cathode with columns grown
according to methods used in the prior art.
[0032] FIG. 2 illustrates a hybrid thin-film electrochemical device
according to an exemplary embodiment of the present invention.
[0033] FIG. 3 shows a cross-sectional view of a scanning electron
micrograph of a composite LiCoO.sub.2 cathode deposited by slurry
coating and then coated with a LiPON thin-film electrolyte
according to an exemplary embodiment of the invention.
[0034] FIG. 4 illustrates the electrochemical cycle behavior of an
electrochemical device using the composite LiCoO.sub.2 cathode and
the LiPON thin-film from FIG. 3 according to an exemplary
embodiment of the invention.
[0035] FIG. 5 depicts a scanning electron micrograph of a 9 .mu.m
thick, fully crystalline LiCoO.sub.2 positive cathode film
fabricated by electrophoretic deposition according to an exemplary
embodiment of the invention.
[0036] FIG. 6 shows the current-discharge voltage performance of a
thin-film electrochemical device whose LiCoO.sub.2 positive cathode
was fabricated by electrophoretic deposition according to an
exemplary embodiment of the invention.
[0037] FIG. 7 shows the reversible discharge capacity as a function
of cycle number of a thin-film electrochemical device whose
LiCoO.sub.2 positive cathode was fabricated by electrophoretic
deposition according to an exemplary embodiment of the
invention.
[0038] FIG. 8 shows a scanning electron micrograph of an about 15
.mu.m thick, fully crystalline LiCoO.sub.2 positive cathode film
deposited by ink-jetting according to an exemplary embodiment of
the invention.
[0039] FIG. 9 shows a hybrid thin-film electrochemical device
without a substrate according to an exemplary embodiment of the
present invention.
[0040] FIG. 10 shows a multi-layer thin-film used to encapsulate an
electrochemical device according to an exemplary embodiment of the
present invention.
[0041] FIG. 11 shows the electrochemical device shown in FIG. 2,
including a modulating LiPON layer and a multi-layer thin-film
encapsulation layer according to an exemplary embodiment of the
present invention.
[0042] FIG. 12 shows an inverted thin-film battery configuration
according to an exemplary embodiment of the present invention.
[0043] FIG. 13 shows an exemplary embodiment of an inverted
thin-film battery.
[0044] FIG. 14 shows an exemplary embodiment of an embossed cathode
layer.
DETAILED DESCRIPTION
[0045] FIG. 1 illustrates a schematic cross-sectional view of a
typical cathode layer 120 fabricated onto a metal current collector
101 over a substrate 100. In electrochemical devices produced by
vacuum vapor phase deposition processes, the cathode may grow, for
example, in columns 120 with inter-columnar void space 111. Also
shown in FIG. 1 is a next layer in the fabrication process sequence
of the thin-film electrochemical device, the electrolyte 110 with a
typical bridging structure over the inter-columnar void space
111.
[0046] FIG. 2 shows a hybrid thin-film electrochemical device with
a cathode 210 deposited without using a vacuum vapor phase process
according to an exemplary embodiment of the present invention. In
this embodiment, a cathode 210 is directly deposited onto a
substrate 200. If metallically conducting, for example, the
substrate 200 in this embodiment may also serve as the cathode
current collector. Otherwise, a metallically conducting current
collector (not shown) may be interposed between the substrate 200
and the cathode 210. The cathode 210, for example, may comprise
LiCoO.sub.2, LiMn.sub.2O.sub.4, LiMnO.sub.2, LiNiO.sub.2,
LiFePO.sub.4, LiVO.sub.2, or any mixture or chemical derivative
thereof. The cathode 210, for example, in one embodiment, may be
between about 0.5 .mu.m and about 200 .mu.m thick. In a preferred
embodiment, the cathode 210, for example, may be between about 5
and about 100 .mu.m thick. In a most preferred embodiment, for
example, the cathode 210 may be between about 30 to about 80 .mu.m
thick.
[0047] As shown in FIG. 2, an electrolyte layer 220 may be
deposited on the top surface of the cathode layer 210. The
electrolyte layer may, for example, comprise lithium phosphorus
oxynitride (LiPON) or other solid state thin-film electrolytes such
as LiAlF.sub.4, as discussed in U.S. Pat. No. 4,367,267, or
Li.sub.3PO.sub.4 doped Li.sub.4SiS.sub.4, as discussed by Yamamura
et al. in U.S. Pat. No. 5,217,826. Both of these patents are
incorporated herein in their entirety by reference. This
electrolyte layer 220 may, for example, be less then about 10 .mu.m
thick.
[0048] The cathode 210 is thick when compared to the relative sizes
of the electrolyte 220, substrate 200, and an anode 230 formed over
the electrolyte 220. In other embodiments, the relative size of the
cathode 210 is also thick in comparison to the anode current
collector 240, as well as a thin-film encapsulation 250.
[0049] The electrolyte 220 may be deposited on the cathode 210
using a variety of methods. These methods may include, for example,
vacuum vapor phase growth methods or non-vapor phase methods.
Vacuum vapor phase methods may include, for example, reactive or
non-reactive RF magnetron sputtering, reactive or non-reactive DC
diode sputtering, reactive or non-reactive thermal (resistive)
evaporation, reactive or non-reactive electron beam evaporation,
ion-beam assisted deposition, plasma enhanced chemical vapor
deposition or the like. Non-vapor phase methods may include, for
example, spin coating, ink-jetting, thermal spray deposition or dip
coating. Spin coating is discussed, for example, by Stetter et al.
in U.S. Pat. No. 4,795,543; Venkatasetty in U.S. Pat. No.
4,948,490; or Schmidt et al. in U.S. Pat. No. 6,005,705. One such
ink-jetting process is disclosed by Delnick in U.S. Pat. No.
5,865,860. A thermal spray deposition process is disclosed by Inda
in U.S. Patent Publication No. 2004/0106046. Dip coating is
discussed by Kejha in U.S. Pat. No. 5,443,602 and U.S. Pat. No.
6,134,773. Each of the above patents and patent publications is
incorporated herein by reference in its entirety.
[0050] As shown in FIG. 2, the next layer on top of the electrolyte
is the thin negative anode layer 230. The thin anode 230 may
comprise, for example, lithium, lithium alloys, metals that can
form solid solutions or chemical compounds with lithium, or a
so-called lithium-ion compound that may be used as a negative anode
material in lithium based batteries, such as, for example,
Li.sub.4Ti.sub.5O.sub.12. The thin anode layer 230, for example,
may be less than about 30 .mu.m thick. The thin anode may make
contact with the anode current collector 240, which can be accessed
electrically through an opening 260 in the encapsulation 250. In
one embodiment the anode current collector is less than about 2
.mu.m thick. The thin-film encapsulation 250, for example, may be
electrically conducting in certain areas and thus may, in some
embodiments, serve as an anode current collector. In such
embodiments, a separately deposited anode current collector 240
would not be necessary. The thin-film encapsulation 250 may, for
example, be less than about 250 .mu.m thick.
[0051] The cathode 210 in FIG. 2 may be deposited on the substrate
200 using a variety of deposition methods. In one specific
embodiment, the cathode material 210 is deposited using a non-vapor
phase deposition method. Non-vapor phase deposition methods are not
performed in a vacuum environment. A number of non-vapor phase
deposition methods are known in the art. A few exemplary methods
include, slurry coating, Meyer rod coating, direct and reverse roll
coating, doctor blade coating, spin coating, electrophoretic
deposition, sol-gel deposition, spray coating, dip coating, and
ink-jetting, to name a few. Any other non-vapor phase deposition
methods or methods that do not require deposition in a vacuum may
be used without deviating from the spirit, scope or embodiments of
the present invention. These non-vapor phase, non-vacuum deposition
methods may produce a single phase cathode or a composite cathode.
The composite cathode may be deposited either on a nanoscopic,
microscopic, or milliscopic scale and may consist of organic and/or
inorganic matter which, in addition, may be polymerized, such as
poly(vinyl pyrrolidone), sulfur nitride (SN).sub.x, nano-tubed
carbon or acetylene black.
[0052] All of the depositions mentioned herein, may, for example,
be followed by a drying step with temperatures below about
150.degree. C., and/or a low-temperature drying and adhesion
improving step with temperatures between about 150.degree. C. to
about 400.degree. C., and/or a high temperature anneal step ranging
from about 400.degree. C. to about 1000.degree. C. These steps may
help, for example, in drying, improving adhesion, formation of the
correct film phase, and/or crystallization. The cathode deposition
material may be used either in pure form or mixed with binder
material, with or without carbon-type, metal-type or alloy-type
electrical conduction enhancers. When the cathode material
comprises a mixed form rather than a pure form, such cathode
materials may be composite cathode materials.
[0053] The method of slurry coating has been used in battery
fabrication as shown, for example, by Hikaru et al. in U.S. Pat.
No. 6,114,062, or by Kinsman in U.S. Pat. No. 4,125,686, which are
incorporated herein in the entirety by reference. Slurry coating
may lead to the deposition of a composite electrode consisting of
the electrochemical active material, which is in the form of finely
dispersed powder particles that are bonded together using a
polymeric binder and some form of electrical conduction enhancer,
such as carbon black or the like. Also, the slurry contains
solvents which need to be evaporated and/or pyrolyzed after film
deposition.
[0054] According to an exemplary embodiment, a composite cathode
may be deposited from slurry including or consisting of fully
crystalline LiCoO.sub.2 powder, a polyimide binder, and a graphite
electrical conduction enhancer. This slurry may then be coated onto
an Al foil substrate and dried at temperatures below about
150.degree. C. in ambient air for less than about 2 days.
Subsequently, in this embodiment, the cathode may be coated, for
example, with an about 2 .mu.m LiPON thin-film electrolyte, an
about 3 .mu.m thick Li negative anode, and an about 0.3 .mu.m thick
Cu anode current collector. Finally, an about 100 .mu.m thick heat
and pressure sensitive metal-polymer laminate, which may serve to
encapsulate the electrochemical device, may be applied to the
electrochemical device so that the electrochemical performance of
the device may be tested in the ambient.
[0055] In an exemplary another embodiment, the dried slurry coating
may require an additional drying, adhesion, formation, and/or
crystallization steps at temperatures up to about 1000.degree. C.,
as described above, to finalize the structure of the cathode or
composite cathode. This method is quick, simple and can produce
thick cathodes without using a vacuum vapor phase method.
Furthermore, the resulting cathode does not have the mechanical
instability as those produced by vacuum vapor phase deposition
methods.
[0056] The cathode 210 in FIG. 2 may be modified as shown, for
example, in FIG. 14 through mechanical displacement or removal
means including embossing, stamping, abrading, scraping, forming
and the like. This layer modification may be performed on either
the wet or completely dried cathode. This cathode surface
modification improves the ion transfer efficiency between the
cathode bulk and the thin-film electrolyte, for example, consisting
of a LiPON layer (not shown), and thus improves the power
performance of the electrochemical device.
[0057] Further improvement in power capability may be accomplished
when cathode 210 comprises a composite material including or
consisting of at least the electrochemically active cathode
material, for example LiCoO.sub.2, and a carbonaceous electronic
conduction enhancer, which serves to minimize the electronic
diffusion lengths inside the composite cathode bulk.
[0058] FIG. 3 shows a cross-sectional view of a scanning electron
micrograph showing an exemplary LiPON coated composite cathode. The
dimension calibration bar at the very left side in the left picture
is about 9 .mu.m long; and the one in the insert picture on the
right side represents a length of about 3 .mu.m.
[0059] An electrochemical cycling performance of an electrochemical
device according to an exemplary embodiment of the present
invention is shown in FIG. 4.
[0060] According to an exemplary embodiment of the invention, a
composite cathode may be deposited by Meyer rod coating of a
viscous suspension or solution containing, for example, LiCoO.sub.2
powder, as described by Principe et al. in U.S. Pat. No. 6,079,352,
which is incorporated herein by reference in its entirety.
Alternatively, a polymeric binder, such as, for example, a
polyimide, and/or an electrical conduction enhancer, such as
graphite, may be admixed. This coating on a substrate, such as an
Al foil substrate, may then be dried at temperatures below, for
example, about 150.degree. C. in air for less than about 2 days.
Subsequently, in this embodiment the cathode may be coated, for
example, with an about 2 .mu.m LiPON thin-film electrolyte, an
about 3 .mu.m thick Li negative anode, and an about 0.3 .mu.m thick
Cu anode current collector. Finally, an about 100 .mu.m thick heat
and pressure sensitive metal-polymer laminate, which may serve to
encapsulate the electrochemical device, may be applied to the
electrochemical device so that the electrochemical performance of
the device may be tested in the ambient.
[0061] In an exemplary embodiment, a dried Meyer rod coating may
require an additional drying, adhesion, formation, and/or
crystallization steps at temperatures up to, for example, about
1000.degree. C., as described above, to finalize the structure of
the cathode or composite cathode. This method is quick, simple and
can produce thick cathodes without using a vacuum vapor phase
method. Furthermore, the resulting cathode does not have the
mechanical instability as those produced by vacuum vapor phase
deposition methods.
[0062] According to an exemplary embodiment of the invention, a
composite cathode may be deposited by direct and/or reverse roll
coating of a viscous suspension or solution, containing, for
example, LiCoO.sub.2 powder as described by Davis et al. in U.S.
Pat. No. 3,535,295, which is incorporated herein by reference in
its entirety. Alternatively, a polymeric binder, such as, for
example, a polyimide, and/or an electrical conduction enhancer,
such as graphite, may be admixed. This coating onto a substrate,
such as an Al foil substrate, may then be dried at temperatures
below about 150.degree. C. in ambient air for less than about 2
days. Subsequently, in this embodiment, the cathode may be coated,
for example, with an about 2 .mu.m LiPON thin-film electrolyte, an
about 3 .mu.m thick Li negative anode, and an about 0.3 .mu.m thick
Cu anode current collector. Finally, an about 100 .mu.m thick heat
and pressure sensitive metal-polymer laminate, which may serve to
encapsulate the electrochemical device, may be applied to the
electrochemical device so that the electrochemical performance of
the device may be tested in the ambient.
[0063] In an exemplary embodiment, a dried direct or reverse roll
coated deposit may require an additional drying, adhesion,
formation, and/or crystallization steps at temperatures up to, for
example, about 1000.degree. C., as described above, to finalize the
structure of the cathode or composite cathode. This method is
quick, simple and can produce thick cathodes without using a vacuum
vapor phase method. Furthermore, the resulting cathode does not
have the mechanical instability as those produced by vacuum vapor
phase deposition methods.
[0064] According to an exemplary embodiment of the invention, a
thick cathode may be deposited on a substrate via a doctor blade
technique as disclosed by Brown in GB Patent No. 947518, which is
incorporated herein in its entirety by reference. This deposition
method is analogous to spreading butter. Accordingly, for example,
a fine blade slices into some cathode material paste, consisting of
the electrochemically active material, in precursor or final form,
mixed with solvents, binders, and potentially electrical conduction
enhancer materials, and then spreads the cathode material paste
under a certain thickness directly onto a substrate. Depending on
the formulation of the cathode material paste, additional drying,
adhesion, formation and/or crystallization steps at temperatures of
up to about 1000.degree. C., as described above, may be used to
form the final cathode or composite cathode. This method is quick,
simple and can produce thick cathodes without using a vacuum vapor
phase method. Furthermore, the resulting cathode does not have the
mechanical instability as those produced by vacuum vapor phase
deposition methods.
[0065] Spin coating is used in the thin-film coating industry,
using a variety of standard spin coaters offered by many well-known
manufacturers, such as Hitachi disclosed in JP Patent No. 1320728
and incorporated herein by reference in its entirety. Using a spin
coating technique, a cathode powder is suspended or dispersed in a
solvent of a low boiling point (high volatility), such as, for
example, water, low-molecular mass alcohols, low-molecular mass
ethers, low-molecular mass ketones, low-molecular mass esters,
low-molecular mass hydrocarbons, etc. This suspension may then be
dropped onto a fast spinning substrate (typically about 1000-3000
rpm) and is thus spread out quickly into a thin-film over the
substrate due to the high centrifugal forces exerted on the
droplets. Because of the extremely low mass or volume per unit
area, thin-films of a volatile solvent evaporate quickly leaving
the solute or suspended or dispersed material precipitated on the
substrate. The spin coating process may be repeated multiple times
so as to increase the thickness of a given film. To further the
evaporation process of the solvent and the precipitation of the
solute, or suspended or dispersed material, the spinning substrate
may be heated. Alternatively, the spin coating suspension may
additionally contain binder material or binder precursor material
as well as electrical conduction enhancer material. All of these
materials do not and are not intended to evaporate during the
spin-coating process, either conducted at ambient conditions or at
elevated temperatures, as described above, and/or vacuum. Depending
on the spin coating suspension formulations, an additional drying,
adhesion, formation, and/or crystallization step at temperatures of
up to about 1000.degree. C., as described above, may be required to
form the final cathode or composite cathode.
[0066] According to an exemplary embodiment of the present
invention, a non-vapor phase LiCoO.sub.2 cathode film may be
developed using electrophoretic deposition as discussed by Kanamura
et al. in 3 Electrochem. Solid State Letters 259-62 (2000) or by
Lusk in GB Patent No. 1298746, both of which are incorporated
herein by reference in their entirety. For example, micron size,
fully crystallized LiCoO.sub.2 particles may be suspended in a
solution of acetone, isopropanol, and/or iodine and may enable the
electrophoretic deposition of, for example, an about 9 .mu.m thick,
fully crystalline LiCoO.sub.2 cathode film onto stainless steel
substrate without any columnar structure. This process may be
performed, for example, at less than about 120VDC within about 30
minutes at room temperature.
[0067] FIG. 5 depicts a scanning electron micrograph of an
exemplary positive cathode film in cross-sectional view deposited
with electrophoretic deposition. The potential iodine impurity
concentration of the film shown in the figure is below the
detection limits (<1 wt %) of the energy dispersive x-ray
spectroscopic method employed. Electrochemical cells may also be
fabricated with thinner LiCoO.sub.2 composite cathodes by
electrophoretic deposition, for example, in a solution consisting
of about 200 ml acetone, about 23 mg I.sub.2, about 38 mg carbon
black, and about 53 mg poly(tetrafluoroethylene) (PTFE) into which
about 1 g of fully crystalline LiCoO.sub.2 particle powder was
suspended. In such an embodiment, the driving voltage of 50VDC for
this electrophoretic deposition may be applied, for example, for
about 30 seconds. Following which, the so-deposited LiCoO.sub.2
composite film may be annealed at approximately about 377.degree.
C. in air for about 4 hours to improve adhesion to the conductive
substrate. Subsequently, the fabrication of the electrochemical
device may be completed by depositing an about 2 .mu.m thick LiPON
electrolyte using RF magnetron sputter over the LiCoO.sub.2
composite cathode, then fabricating approximately about 0.3 .mu.m
thick Cu anode current collector film by electron beam evaporation,
which may then be followed by a thermal (resistive) vacuum
deposition of an about 3 .mu.m thick metallic Li anode. The
current-discharge voltage performance of such an electrochemical
device is presented in FIG. 6, while its electrochemical cycle
stability is shown in FIG. 7. Depending on the formulation of the
electrophoretic suspension, an additional drying, adhesion,
formation, and/or crystallization step at temperatures of up to
about 1000.degree. C., as described above, may be required to form
the final cathode or composite cathode.
[0068] According to an exemplary embodiment, a thick cathode may be
deposited using a sol-gel method. In this embodiment, for example,
an oxidic cathode film material to be deposited is provided in a
precursor state, such as aqueous or alcoholic sols or gels of
lithium and cobalt ions that are electrically balanced by anionic
counter ions or chelates. These anionic counter ions or chelates
may comprise, for example, nitrate, glycolate, hydroxide, citrate,
carboxylates, oxalate, alcoholate, or acetylacetonate. Such
formulations may be dip coated or sprayed onto the substrate and
then dried at elevated temperatures for extended periods of time,
for example, less than 2 days. In addition, the so-fabricated films
may be subjected to a high-temperature pyrolysis process so as to
convert the anionic counter ions or chelates quantitatively into
pure oxides. This method is discussed in the Ph.D Thesis of Bernd
J. Neudecker, Stuttgart, Germany (1994); by Plichta et al., in 139
J. Electrochem. Soc. 1509-13 (1992); and by Nazri, U.S. Pat. No.
5,604,057. Alternatively, the sol-gel may additionally contain
binder material or binder precursor material, as well as electrical
conduction enhancer material. All of these additives do not, and
are also not intended to evaporate during the drying process,
either done at ambient conditions or at elevated temperatures, as
described above, and/or vacuum. Depending on these sol-gel
formulations, an additional drying, adhesion, formation, and/or
crystallization step at temperatures of up to about 1000.degree.
C., as described above, may be required to form the final cathode
or composite cathode.
[0069] In an exemplary embodiment of the present invention, the
thick cathode may be deposited using an ink-jet method. Ink-jetting
of oxide film electrodes is discussed by Watanabe Kyoichi et al. in
JP 2005011656, Speakman in U.S. Pat. No. 6,713,389 and Hopkins et
al. in U.S. Pat. No. 6,780,208, which are incorporated herein in
their entirety by reference. In one embodiment of the present
invention, fully crystallized LiCoO.sub.2 powder may be milled to
about 0.55 .mu.m in average particle size, and then dispersed in an
aqueous solution of about 0.05 vol % iso-octanol, about 5 vol %
isopropanol, about 10 vol % ethylene glycol monobutyl ether, and
about 10 vol % ethylene glycol. This solution may then be sonicated
for about 1 hour to form a suitable ink-jet solution. The
LiCoO.sub.2 films may then be deposited through a print head and
wetted ceramic, for example, about 250 .mu.m thick Al.sub.2O.sub.3
plates, and a stainless steel substrates well, for example, an
about 50 .mu.m foil. Subsequent to the printing, the as-deposited
LiCoO.sub.2 films may be dried in air at about 200.degree. C. for
about 2 hours in order to drive off excess solvent and improve the
adhesion of the LiCoO.sub.2 film to its substrate. A dried
LiCoO.sub.2 film thickness of about 15 .mu.m may be achieved based
on ten print head passes over the same substrate region. A
cross-sectional scanning electron micrograph view of such a
LiCoO.sub.2 film is shown in FIG. 8. Alternatively, the ink-jet
solution or suspension may contain binder material, binder
precursor material, and/or electrical conduction enhancer material.
If used, each of these materials do not, and are also not intended
to evaporate during the drying process, whether at ambient
conditions or at elevated temperatures, as described above, and/or
in a vacuum. Depending on these formulations of the ink-jet
solution or suspension, an additional drying, adhesion, formation,
and/or crystallization step at temperatures of up to about
1000.degree. C., as described above, may be required to form the
final cathode or composite cathode.
[0070] According to an exemplary embodiment, a cathode fabricated
by a non-vapor phase deposition may be coated, in its finished or
unfinished state, for example, with an inert, metallically
conducting layer, such as gold. Subsequently, a finished or
unfinished cathode and an inert, metallically conducting coating
may be, for example, heated together for further drying, adhesion,
formation, and/or crystallization during which processes the inert,
metallically conducting coating may be substantially absorbed into
the pores, voids, and crevices of the cathode, thus improving the
electrical conduction of the cathode.
[0071] The anode in the exemplary embodiments described above may
be deposited using a variety of methods. For example, the anode
material may be deposited using a vacuum vapor phase growth method,
or a non-vapor phase growth method, such as ink-jetting or dip
coating.
[0072] An exemplary embodiment of the present invention includes
depositing a negative anode material via a vacuum vapor phase
growth method. Typical vapor phase growth methods for negative
anodes include, but are not limited to, reactive or non-reactive RF
magnetron sputtering, reactive or non-reactive DC diode sputtering,
reactive or non-reactive thermal (resistive) evaporation, reactive
or non-reactive electron beam evaporation, ion-beam assisted
deposition, or plasma enhanced chemical vapor deposition. The
negative anode may either be, for example, metallic lithium, a
lithium alloy, or a metal that can form a solid solution or a
chemical compounds with lithium.
[0073] Other exemplary embodiments may include non-vapor phase
growth methods for depositing a negative anode. For example,
non-vapor phase growth methods, such as ink-jetting of metallic
lithium powder mixtures may be used to deposit a negative anode.
Such methods are described by Nelson et al. in U.S. Patent
Publication No. 2005/0239917. As well, for example, one could
simply dip a sample into molten lithium under a protective
atmosphere and allow the resulting film on the sample to cool and
solidify. Analogously, one may fabricate a lithium-ion anode, such
as metallic tin, by dipping a sample into molten tin under air
atmosphere or transfer the molten or hot tin on a flattened face of
a, for example, rod and then stamp the tin onto the sample.
[0074] A dip coating technique via sol-gel route may similarly work
for depositing negative anode materials as described, for example,
by Patrusheva et al. in RU Patent No. 2241281C2, which is
incorporated herein by reference in its entirety. For example,
SnO.sub.2 based Li-ion anodes using suitable anionic formulations
of alkoxides may be used, as described by Toki Motoyuki in U.S.
Pat. No. 6,235,260, which is also incorporated herein by reference
in it entirety.
[0075] FIG. 9 shows an exemplary hybrid thin-film electrochemical
device fabricated without a substrate according to an embodiment of
the present invention. This device is similar to that shown in FIG.
2, but does not have a substrate. Instead, the device is spatially
terminated by a thin metal layer 300 that may be used, for example,
as a current collector and electrical terminal. In addition to this
thin metal layer 300, the device in FIG. 9 comprises at least a
cathode 310, an electrolyte 320, and an anode 330.
[0076] The embodiments described above may be encapsulated using an
encapsulation 350 selected from the group consisting of vacuum
vapor phase grown thin-film encapsulation, pressure-heat lamination
of protective polymer composites as described by Snyder et al. in
U.S. Pat. No. 6,916,679, pressure-heat lamination of metal foils
coated with pressure-heat sensitive adhesive surfaces, and metal
canning.
[0077] An anode current collector 340, such as Zr may be interposed
between the electrolyte 320, the anode 330, and the encapsulation
350. Furthermore, a moisture barrier may be applied between the
anode current collector 340 and the underlying moisture sensitive
electrolyte 320 to protect latter from the environment. A material
having moisture blocking properties may be selected: a) from the
group of metals, semi-metals, alloys, borides, carbides, diamond,
diamond-like carbon, silicides, nitrides, phosphides, oxides,
fluorides, chlorides, bromides, iodides; b) from the group of any
multinary compounds composed of borides, carbides, suicides,
nitrides, phosphides, oxides, fluorides, chlorides, bromides, and
iodides; or c) from the group of high-temperature stable organic
polymers and high-temperature stable silicones. This moisture
barrier, for example, may comprise ZrO.sub.2 or ZrN and may be part
of the anode current collector 340 that may be gradiented in terms
of its oxide or nitride content thus reaching a stoichiometry of
ZrO.sub.2 or ZrN near the interface to the electrolyte.
[0078] FIG. 10 shows an embodiment of an electrochemical device
with a multilayer thin-film encapsulation material. The multilayer
thin-film encapsulation 400 may be comprised, for example, of
multiple strong metallic getter layers 410 with alternating
amorphous or glassy oxide or nitride layers 420 thereof. The strong
metallic getter layers 410 are used to protect the device from
moisture and oxygen based on their superior gettering ability for
H.sub.2O and O2. The strong metallic getter layers may, for
example, be comprised of Zr, Y, Ti, Cr, Al, or any alloy thereof.
The glassy or amorphous layers 420 may be the oxides or nitrides of
the metal or metals used in the getter layers, such as, for
example, ZrO.sub.2, ZrN, Y.sub.2O.sub.3, YN, TiO.sub.2, TiN,
Cr.sub.2O.sub.3, CrN, Al.sub.2O.sub.3, AIN, or any multi-element
compound thereof. The mechanically dense glassy or amorphous layers
being substantially free of grain boundaries may, for example,
effectively block any moisture or oxygen diffusion through said
oxides or nitrides. As a result, the multilayer thin-film
encapsulation may effectively protect the underlying, air sensitive
metallic anode.
[0079] In another exemplary embodiment, for example, the multilayer
thin-film encapsulation consists of inorganic high-temperature
stable or resilient materials. Using such an encapsulation
increases the high temperature stability of the electrochemical
device as compared with an electrochemical device that employs
polymeric components in its encapsulation, such as is the case in
the above-mentioned pressure-heat laminated encapsulation described
by Snyder et al. in U.S. Pat. No. 6,916,679.
[0080] Another exemplary embodiment of inorganic high-temperature
stable or resilient materials may include a multilayer thin-film
encapsulation having vacuum vapor phase deposited alternating
layers. For example, a thin-film encapsulation may comprise or
consist of 30 alternating 1000 .ANG. thick layers of the sequence
ZrO.sub.2 /Zr/ZrO.sub.2/Zr/ . . . or ZrN/Zr/ZrN/Zr/ . . . ,
although it is to be understood that different sized thickness,
periods and materials may be used. These alternating layers may be
deposited at less than about 100.degree. C. substrate temperature
in one vacuum chamber pump-down from ambient pressures, for
example. Such an exemplary 30 multilayer thin-film encapsulation
may, for example, be only about 3 .mu.m thick and high-temperature
stable to far above about 300.degree. C.
[0081] As those skilled in the art will appreciate, the mere
thinness of such a thin-film encapsulation directly increases the
energy, capacity, and power of a given electrochemical device per
unit volume (volumetric energy, volumetric capacity, and volumetric
power) compared with an electrochemical device that uses a
pressure-heat laminated encapsulation, which is typically thicker
by at least one order of magnitude than the presented thin-film
encapsulation of about 3 .mu.m. For example, the volumetric
quantities of energy, capacity, and power can increase three-fold
when for a given electrochemical device of, for example, 150 .mu.m
in total packaged thickness, which may comprise an actual
electrochemical cell of, for example, 10 .mu.m in thickness, a, for
example, 35 .mu.m thick substrate, and a, for example, 100 .mu.m
thick pressure-heat laminate, the encapsulation is replaced by a
thin-film encapsulation of, for example, 3 .mu.m in thickness,
which results in an overall thickness of the electrochemical device
of 48 .mu.m.
[0082] FIG. 11 shows an electrochemical device according to an
exemplary embodiment of the present invention. In addition to the
electrically conductive substrate 500, the positive cathode 510,
the electrolyte film 520, the negative anode 530, the anode current
collector 540, and the electrical insulation layer 550, this
embodiment includes an encapsulation layer 570. This encapsulation
may be, for example, a multilayer encapsulation as described above
and as shown in FIG. 10. Between the encapsulation layer 570 and
the anode 530, for example, a second LiPON layer 560 may be
interposed. The encapsulation layer 570 may be fabricated onto the
anode 530, which may comprise metallic lithium. The softness of the
anode 530 material may cause the encapsulation layer 570 to crack
due to the mechanically weak fundament provided by the soft anode
530 and/or the stress imbalance at the interface of the anode 530
encapsulation 570. Once cracked, the encapsulation 570 may cause
exposure of the sensitive anode 530 to the ambient, which may
destroy the anode. Using a glassy LiPON (or derivative) modulator
layer 560, for example, may mechanically stabilize the soft anode
surface while chemically encapsulating it.
[0083] FIG. 11, the cathode 510 may be thick when compared to the
relative sizes of the electrolyte 520, substrate 500 (and cathode
current collector in some embodiments), anode 530, anode current
collector 540, electrical insulation layer 550, modulating LiPON
layer 560, and thin-film encapsulation 570.
[0084] The underlying LiPON electrolyte layer 520 together with the
overlying LiPON modulator layer 560 confine the interposed anode
530 while protecting it, not only mechanically, but also
chemically. In this configuration, a metallic anode 530, such as,
for example, metallic Lithium, may be melted when heated above its
melting point at about 181.degree. C. Due to its spatial
confinement, chemical protection, and inertness towards LiPON well
above the melting point of lithium, the metallic lithium anode 530
remains fixed at location and intact as a negative anode material
inside of the described electrochemical device. This engineering
design also enables the described electrochemical device being used
in solder reflow processing or flip chip processing.
[0085] Many materials may be used as the anode, for example, copper
lithium alloy or solid solutions, such as, Li.sub.xCu, Li.sub.xZr,
Li.sub.xV, Li.sub.xW, Li.sub.xBe, Li.sub.xBeyCu, etc. Those skilled
in the art will recognize these and other materials that may be
used for the anode. These alloys or solid solutions of lithium may
offer stronger mechanical properties compared with soft metallic
lithium, and thus may allow the direct deposition of the multilayer
thin-film encapsulation 570 without the use of the above-described
LiPON modulator layer 560 interposed between the soft negative
metallic anode 530 and the multilayer thin-film encapsulation 570.
In such case, the LiPON modulator layer 560 may be redundant.
[0086] In an example of the embodiment shown in FIG. 11, an
electrochemical device may be fabricated, for example, onto a 25.4
mm.times.25.4 mm large aluminum substrate of 25 .mu.m in thickness
(500), coated with a 80 .mu.m.times.3.3 cm.sup.2 large LiCoO.sub.2
composite positive cathode consisting of 62 volume % of LiCoO.sub.2
powder and the volume balance of polymeric binder and
electronically conducting carbon black powder (510), a 1.5 .mu.m
thin film of solid state LiPON electrolyte (520), a 10 .mu.m thick
negative, metallic lithium anode (530), a 0.5 .mu.m thick nickel
anode current collector (540), a 0.5 .mu.m thick ZrO.sub.2
electrical insulation layer (550), a 0.5 .mu.m thick LiPON
modulator layer (560), and a 3 .mu.m thick multilayer thin-film
encapsulation layer consisting of fifteen 1000 .ANG. thick Zr/1000
.ANG. thick ZrO.sub.2 bi-stacks (570). In this example, the
electrochemical device is 120 .mu.m thick at its thickest
cross-section and provides 10 mAh of continuous capacity within the
voltage range of 4.2-3.0V with an average voltage of 4.0V, which
results in a volumetric energy of 520 Wh/liter for the fully
packaged electrochemical device. When using a 10 .mu.m aluminum
substrate instead of the 25 .mu.m thick one, then the volumetric
energy of this device increases from 520 Wh/liter to 590
Wh/liter.
[0087] In another exemplary embodiment, a barrier layer may be
included. This barrier layer may be deposited onto a substrate,
such as, for example, a metal foil substrate, wherein the barrier
layer chemically separates the battery part (i.e.,
electrochemically active cell) from the substrate part of an
electrochemical apparatus. The barrier may prevent diffusion of any
contaminants entering the battery from the substrate as well as,
for example, block ions from escaping the battery and diffusing
into the substrate during both battery fabrication and during
battery operating and storage conditions. Certain potentially
suitable materials for a barrier layer may include poor ion
conducting materials, for example, such as borides, carbides,
diamond, diamond-like carbon, silicides, nitrides, phosphides,
oxides, fluorides, chlorides, bromides, iodides, and any multinary
compounds thereof. Of those compounds, electrically insulating
materials may further prevent possible reactions between the
substrate and the battery layers from occurring. For example, if a
possible chemical reaction includes the diffusion of ions and
electrons, an insulating barrier would provide a way to block the
electrons, and thus prevent any such chemical reaction. However, a
barrier layer may comprise electrically conducting materials as
well, as long as they do not conduct any of the ions of the
substrate or battery layer materials. For instance, ZrN is an
effective conducting layer that will prevent ion conduction. In
some cases metals, alloys, and/or semi-metals may serve as a
sufficient barrier layer depending on the anneal temperatures
applied during the battery fabrication process and substrate
material used. The diffusion barrier layer may, for example, be
single or multi-phase, crystalline, glassy, amorphous or any
mixture thereof, although glassy and amorphous structures are
preferred in some applications due to their lack of grain
boundaries that would otherwise serve as locations for increased,
but unwanted, ion and electron conduction.
[0088] A thin-film encapsulation layer, such as the one shown in
FIGS. 10 and 11, may, for example, tent over the device. Therefore,
a flexible encapsulation may, for example, be used to allow the
device to expand and contract. The above-described glass-metal
multilayer encapsulation possesses appropriate flexible properties,
which can be tailored, for example, by changing the sputter
deposition parameters, which then changes the densities of the
glass and/or metal. Another approach to tuning the mechanical
properties of the constituents of the thin-film encapsulation, and
thus also the thin-film encapsulation itself may include changing
the stoichiometry of one or more constituents of the thin-film
encapsulant. For instance, ZrN can be changed to Zr.sub.2N, which
is equivalent to depriving the particular composition of this layer
of nitride. Alternatively, one can change the metals in the stack.
For example, instead of a Zr, ZrN, Zr, ZrN stack, one could
fabricate a multilayer thin-film encapsulation consisting of Zr,
AlN, Cr, TiN.
[0089] Some of the embodiments above discuss a thick positive
cathode that is inexpensive and reliable. The thick cathode may
also be configured with a thin electrolyte, a thin anode, and a
thin encapsulation so as to maximize the volumetric densities of
capacity, energy, and power of the resulting electrochemical
device.
[0090] FIG. 12 shows another embodiment of the present invention,
which depicts a configuration variant of the electrochemical device
shown in FIG. 2 and termed inverted thin-film battery
configuration. The negative anode 610 is chosen from the same
materials and fabricated by the same methods as described for FIG.
2, when deposited directly onto substrate 600, which in turn is
electrically conducting and chemically inert, such as, for example,
Cu foil, to the anode 610. In this particular configuration, the
substrate also serves as the anode current collector and negative
terminal of a battery. If the substrate 600 is electrically
insulating, then an additional anode current collector, consisting
of, for example, Cu or Ni, may be interposed between said substrate
600 and the negative anode 610 (not shown). Electrical access to
this anode current collector may be accomplished, for example, by
either extending the anode current collector beyond the edge of the
encapsulation 650 or providing an opening in the substrate 600. The
opening in the substrate may then be filled with a conductive
material, such as a Cu paste, in a manner that this material makes
electrical contact with the anode current collector. Using the same
materials and methods as for the electrolyte in FIG. 2, the
electrolyte 620 is deposited over the anode 610. Using the same
materials and methods as for the positive cathode in FIG. 2, the
positive cathode 630 is deposited over the electrolyte 620. To
allow electrical access to the positive cathode 630, a cathode
current collector 640, such as Al or Au, is fabricated on top of
the positive cathode 630. If encapsulation 650 is used on an
electrochemical device, then one may provide an opening 660 in
encapsulation 650 to allow electrical access to the positive
cathode 630.
[0091] Analogously, an electrochemical device may be fabricated
with inverted thin-film battery configuration using the elements,
materials and methods described in regard to FIG. 11. Such an
electrochemical device, for example, is shown in FIG. 13. First, a
negative anode 710 is directly deposited onto a chemically inert
substrate 700. To avoid short-circuiting of an electrochemical
device, an electrically insulating layer 750 may be fabricated,
which may be partially coated with an electrolyte 720 and may
entirely tent over the anode 710. After depositing the electrolyte
720, the positive cathode 730 may be deposited followed by a
cathode current collector 740. To employ a thin-film encapsulation
770 over the existing layers in the fabrication sequence of the
electrochemical device, a mechanical and chemical modulation layer
760, for example, may be applied mainly over that area in the
battery part of the electrochemical device which is defined by the
cathode. Those skilled in the art will appreciate that the
invention covers additional inverted configurations, which may be
achieved by way of combining constituent parts of the non-inverted
batteries described above.
[0092] In another embodiment, a barrier layer may be fabricated
between the substrate and the battery part of the electrochemical
device as described in U.S. patent application Ser. No. 11/209,536,
entitled Electrochemical Apparatus with Barrier Layer Protected
Substrate, filed 23 Aug. 2005, and incorporated by reference herein
in its entirety. Depending on the material and configuration of the
barrier layer, one or more additional current collectors may be
fabricated onto the barrier layer so as to improve the electrical
contact to the positive cathode, the negative anode or both.
[0093] The embodiments described above are exemplary only. One
skilled in the art may recognize variations from the embodiments
specifically described here, which are intended to be within the
scope of this disclosure. As such, the invention is limited only by
the following claims. Thus, it is intended that the present
invention cover the modifications of this invention provided they
come within the scope of the appended claims and their equivalents.
Further, specific explanations or theories regarding the formation
or performance of electrochemical devices according to the present
invention are presented for explanation only and are not to be
considered limiting with respect to the scope of the present
disclosure or the claims.
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