U.S. patent application number 13/977131 was filed with the patent office on 2013-10-17 for method of increasing an energy density and an achievable power output of an energy storage device.
The applicant listed for this patent is Tomm V. Aldridge, Zhaohui Chen, Scott B. Clendenning, Donald S. Gardner, John L. Gustafson, Eric C. Hannah, Wei C. Jin. Invention is credited to Tomm V. Aldridge, Zhaohui Chen, Scott B. Clendenning, Donald S. Gardner, John L. Gustafson, Eric C. Hannah, Wei C. Jin.
Application Number | 20130273261 13/977131 |
Document ID | / |
Family ID | 47996197 |
Filed Date | 2013-10-17 |
United States Patent
Application |
20130273261 |
Kind Code |
A1 |
Gardner; Donald S. ; et
al. |
October 17, 2013 |
METHOD OF INCREASING AN ENERGY DENSITY AND AN ACHIEVABLE POWER
OUTPUT OF AN ENERGY STORAGE DEVICE
Abstract
Methods of increasing an energy density of an energy storage
device involve increasing the capacitance of the energy storage
device by depositing a material into a porous structure of the
energy storage device using an atomic layer deposition process, by
performing a procedure designed to increase a distance to which an
electrolyte penetrates within channels of the porous structure, or
by placing a dielectric material into the porous structure. Another
method involves annealing the energy storage device in order to
cause an electrically conductive substance to diffuse to a surface
of the structure and form an electrically conductive layer thereon.
Another method of increasing energy density involves increasing the
breakdown voltage and another method involves forming a
pseudocapacitor. A method of increasing an achievable power output
of an energy storage device involves depositing an electrically
conductive material into the porous structure.
Inventors: |
Gardner; Donald S.; (Los
Altos, CA) ; Chen; Zhaohui; (San Jose, CA) ;
Jin; Wei C.; (San Diego, CA) ; Clendenning; Scott
B.; (Portland, OR) ; Hannah; Eric C.; (Pebble
Beach, CA) ; Aldridge; Tomm V.; (Olympia, WA)
; Gustafson; John L.; (Pleasanton, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Gardner; Donald S.
Chen; Zhaohui
Jin; Wei C.
Clendenning; Scott B.
Hannah; Eric C.
Aldridge; Tomm V.
Gustafson; John L. |
Los Altos
San Jose
San Diego
Portland
Pebble Beach
Olympia
Pleasanton |
CA
CA
CA
OR
CA
WA
CA |
US
US
US
US
US
US
US |
|
|
Family ID: |
47996197 |
Appl. No.: |
13/977131 |
Filed: |
September 30, 2011 |
PCT Filed: |
September 30, 2011 |
PCT NO: |
PCT/US11/54372 |
371 Date: |
June 28, 2013 |
Current U.S.
Class: |
427/560 ;
205/122; 427/126.1; 427/58; 427/79 |
Current CPC
Class: |
H01G 11/86 20130101;
H01G 11/26 20130101; H01G 11/30 20130101; H01G 11/14 20130101; H01G
11/58 20130101; Y02E 60/13 20130101 |
Class at
Publication: |
427/560 ; 427/58;
427/126.1; 427/79; 205/122 |
International
Class: |
H01G 9/00 20060101
H01G009/00 |
Claims
1-57. (canceled)
58. A method of increasing an energy density of an energy storage
device, the method comprising: providing the energy storage device,
wherein the energy storage device comprises at least one porous
structure containing multiple channels and wherein each one of the
channels has an opening to a surface of the porous structure; and
increasing a capacitance of the energy storage device by:
performing a procedure designed to increase a distance to which an
electrolyte penetrates within the channels; and introducing the
electrolyte before, during, or after the performance of the
procedure.
59. The method of claim 58 wherein: the porous structure comprises
one of silicon, germanium, and a silicon-germanium alloy.
60. The method of claim 58 wherein: the procedure comprises one of:
placing the energy storage device in a vacuum; subjecting the
energy storage device to ultrasonic signals; subjecting the energy
storage device to a pressure differential; applying a surface
treatment to a surface of the channels; and placing the energy
storage device in a centrifuge.
61. The method of claim 60 wherein: the surface treatment comprises
making the surface more wettable by depositing a material on
surfaces of the channels.
62. A method of increasing an energy density of an energy storage
device, the method comprising: providing the energy storage device,
wherein the energy storage device comprises at least one porous
structure containing multiple channels, wherein each one of the
channels has an opening to a surface of the porous structure, and
wherein the electrically conductive structure comprises an alloy
composed at least in part of a first substance and an electrically
conductive second substance; and annealing the energy storage
device in order to cause the electrically conductive second
substance to diffuse to a surface of the electrically conductive
structure and form an electrically conductive layer thereon.
63. The method of claim 62 wherein: the porous structure comprises
one of silicon, germanium, and a silicon-germanium alloy.
64. A method of increasing an energy density of an energy storage
device, the method comprising: providing the energy storage device,
wherein the energy storage device comprises at least one porous
structure containing multiple channels and further comprises an
electrolyte in physical contact with the porous structure, and
wherein each one of the channels has an opening to a surface of the
porous structure; and increasing a capacitance of the energy
storage device by placing a dielectric material into the porous
structure.
65. The method of claim 64 wherein: the porous structure comprises
one of silicon, germanium, and a silicon-germanium alloy.
66. The method of claim 64 wherein: placing the dielectric material
into the porous structure comprises using one of: an
electrografting nanotechnology process; a hydrothermal growth
process; an electroplating process; an atomic layer deposition
process; a sol-gel synthesis process; and a venetian glass
approach.
67. The method of claim 66 wherein: at least some of the channels
extend completely through the porous structure; and the atomic
layer deposition process comprises a through-substrate atomic layer
deposition process.
68. The method of claim 64 wherein: the dielectric material is
diffusion limited.
69. A method of increasing an energy density of an energy storage
device, the method comprising: providing the energy storage device,
wherein the energy storage device comprises at least one porous
structure containing multiple channels, and wherein each one of the
channels has an opening to a surface of the porous structure;
increasing a capacitance of the energy storage device by depositing
a material into the porous structure using an atomic layer
deposition process; and adjusting at least one of a pressure and an
exposure time of the atomic layer deposition process based on an
aspect ratio of at least one of the channels.
70. The method of claim 69 wherein: the porous structure comprises
one of silicon, germanium, and a silicon-germanium alloy.
71. The method of claim 69 wherein: the aspect ratio is at least
10.sup.3; and for each precursor cycle, the exposure time is at
least 10 seconds or the pressure is at least 0.1 Torr.
72. The method of claim 69 wherein: the energy storage device
comprises an electrolyte in physical contact with the porous
structure; and the material is a dielectric material having a
dielectric constant higher than that of the electrolyte.
73. A method of increasing an achievable power output of an energy
storage device, the method comprising: providing the energy storage
device, wherein the energy storage device comprises at least one
porous structure containing multiple channels, and wherein each one
of the channels has an opening to a surface of the porous
structure; and depositing an electrically conductive material into
the porous structure.
74. The method of claim 73 wherein: depositing the electrically
conductive material into the porous structure is accomplished using
an atomic layer deposition process or an electroplating
process.
75. The method of claim 73 wherein: the porous structure comprises
one of silicon, germanium, and a silicon-germanium alloy.
76. The method of claim 75 wherein: the porous structure comprises
silicon; the electrically conductive material is TiN; and the
method further comprises depositing a passivation layer on the
silicon prior to the deposition of the electrically conductive
material, the passivation layer comprising TiO.sub.2.
77. The method of claim 73 further comprising: depositing a
dielectric material into the porous structure.
78. The method of claim 77 wherein: the dielectric material is
diffusion limited.
79. A method of increasing an energy density of an energy storage
device, the method comprising: providing the energy storage device,
wherein the energy storage device comprises at least one porous
structure containing multiple channels, wherein each one of the
channels has an opening to a surface of the porous structure; and
increasing a breakdown voltage of the energy storage device by
placing an ionic liquid in physical contact with the porous
structure.
80. The method of claim 79 wherein: the porous structure comprises
one of silicon, germanium, and a silicon-germanium alloy.
81. The method of claim 79 further comprising: depositing a
dielectric material into the porous structure.
82. A method of increasing the energy density of an energy storage
device, the method comprising: providing the energy storage device,
wherein the energy storage device comprises at least one porous
structure containing multiple channels, wherein each one of the
channels has an opening to a surface of the porous structure; and
depositing a material into the porous structure in order to form a
pseudocapacitor.
83. The method of claim 82 wherein: the porous structure comprises
one of silicon, germanium, and a silicon-germanium alloy.
84. The method of claim 82 wherein: the material is a transition
metal oxide.
85. The method of claim 82 wherein: depositing the material into
the porous structure is accomplished using an atomic layer
deposition process.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is related to International Application No.
PCT/US2010/029821, filed on Apr. 2, 2010 and assigned to the same
assignee to which the present application is assigned.
FIELD OF THE INVENTION
[0002] The disclosed embodiments of the invention relate generally
to energy storage devices, and relate more particularly to methods
of enhancing the performance of energy storage devices.
BACKGROUND OF THE INVENTION
[0003] Modern societies depend on the ready availability of energy.
As the demand for energy increases, devices capable of efficiently
storing energy become increasingly important. As a result, energy
storage devices, including batteries, capacitors, pseudocapacitors,
ultracapacitors, hybrid ultracapacitors, and the like are being
extensively used in the electronics realm and beyond. In
particular, capacitors are widely used for applications ranging
from electrical circuitry and power delivery to voltage regulation
and battery replacement. Electric double-layer capacitors (EDLCs),
also referred to as ultracapacitors (among other names), are
characterized by high energy storage capacity as well as other
desirable characteristics including high power density, small size,
and low weight, and have thus become promising candidates for use
in several energy storage applications. Because the energy of a
capacitor depends on the capacitance and the voltage as shown in
Equation 1,
E = 1 2 CV 2 [ Eq . 1 ] ##EQU00001##
increasing the capacitance and/or (especially) the voltage of an
ultracapacitor will result in an increase in energy storage
capacity and energy density. Other parameters affecting
ultracapacitor performance may also be targeted for
improvement.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] The disclosed embodiments will be better understood from a
reading of the following detailed description, taken in conjunction
with the accompanying figures in the drawings in which:
[0005] FIGS. 1 and 2 are cross-sectional views of an energy storage
device according to embodiments of the invention;
[0006] FIGS. 3a and 3b are plan and cross-sectional views,
respectively, of a porous structure of an energy storage device
according to embodiments of the invention;
[0007] FIGS. 4, 5, 8-10, and 12 are flowcharts illustrating methods
of increasing an energy density of an energy storage device
according to embodiments of the invention;
[0008] FIG. 6 is a schematic depiction of an electric double layer
formed within an energy storage device according to an embodiment
of the invention;
[0009] FIG. 7 is a cross-sectional view of a channel of an energy
storage device according to an embodiment of the invention; and
[0010] FIG. 11 is a flowchart illustrating a method of increasing
an achievable power output of an energy storage device according to
an embodiment of the invention.
[0011] For simplicity and clarity of illustration, the drawing
figures illustrate the general manner of construction, and
descriptions and details of well-known features and techniques may
be omitted to avoid unnecessarily obscuring the discussion of the
described embodiments of the invention. Additionally, elements in
the drawing figures are not necessarily drawn to scale. For
example, the dimensions of some of the elements in the figures may
be exaggerated relative to other elements to help improve
understanding of embodiments of the present invention. Certain
figures may be shown in an idealized fashion in order to aid
understanding, such as when structures are shown having straight
lines, sharp angles, and/or parallel planes or the like that under
real-world conditions would likely be significantly less symmetric
and orderly. The same reference numerals in different figures
denote the same elements, while similar reference numerals may, but
do not necessarily, denote similar elements.
[0012] The terms "first," "second," "third," "fourth," and the like
in the description and in the claims, if any, are used for
distinguishing between similar elements and not necessarily for
describing a particular sequential or chronological order. It is to
be understood that the terms so used are interchangeable under
appropriate circumstances such that the embodiments of the
invention described herein are, for example, capable of operation
in sequences other than those illustrated or otherwise described
herein. Similarly, if a method is described herein as comprising a
series of steps, the order of such steps as presented herein is not
necessarily the only order in which such steps may be performed,
and certain of the stated steps may possibly be omitted and/or
certain other steps not described herein may possibly be added to
the method. Furthermore, the terms "comprise," "include," "have,"
and any variations thereof, are intended to cover a non-exclusive
inclusion, such that a process, method, article, or apparatus that
comprises a list of elements is not necessarily limited to those
elements, but may include other elements not expressly listed or
inherent to such process, method, article, or apparatus.
[0013] The terms "left," "right," "front," "back," "top," "bottom,"
"over," "under," and the like in the description and in the claims,
if any, are used for descriptive purposes and not necessarily for
describing permanent relative positions unless otherwise indicated
either specifically or by context. It is to be understood that the
terms so used are interchangeable under appropriate circumstances
such that the embodiments of the invention described herein are,
for example, capable of operation in other orientations than those
illustrated or otherwise described herein. The term "coupled," as
used herein, is defined as directly or indirectly connected in an
electrical or non-electrical manner. Objects described herein as
being "adjacent to" each other may be in physical contact with each
other, in close proximity to each other, or in the same general
region or area as each other, as appropriate for the context in
which the phrase is used. Occurrences of the phrase "in one
embodiment" herein do not necessarily all refer to the same
embodiment.
DETAILED DESCRIPTION OF THE DRAWINGS
[0014] In the related case referenced above (International
Application No. PCT/US2010/029821), there was disclosed an energy
storage device (referred to there as a charge storage device)
comprising at least one electrically conductive structure that
includes a porous structure containing multiple channels, each one
of which has an opening to a surface of the porous structure.
(These channels typically, according to embodiments of the
invention, have aspect ratios (length to diameter) of 100 or
greater.) Such energy storage devices will again be described in
detail in the present disclosure. Embodiments of the present
invention are directed to enhancing the performance, and in
particular the energy density and the achievable power output, of
an energy storage device of a type such as is described herein and
in the related case. Many of the methods disclosed herein are
directed to the deposition or other application of various
substances and materials into high aspect ratio channels.
[0015] As used herein, the term "energy storage device" explicitly
includes EDLCs (ultracapacitors), hybrid ultracapacitors, and
pseudocapacitors, all of which are discussed in more detail below,
as well as batteries, fuel cells, and similar devices that store
energy.
[0016] Although they operate according to similar principles,
ultracapacitors differ from conventional parallel plate capacitors
in certain important respects. One significant difference concerns
the charge separation mechanism: for ultracapacitors this typically
takes the form of a so-called electric double layer, or EDL, rather
than of the dielectric of a conventional capacitor. The EDL is
created by the electrochemical behavior of ions at an interface
between a high-surface area electrode and an electrolyte, and
results in an effective separation of charge in spite of the fact
that the layers are so close together. (Physical separation
distances are on the order of a single nanometer.) Thus, a typical
ultracapacitor may be thought of as storing charge in its EDL. Each
layer of the EDL is electrically conductive but the properties of
the double layer prevent current from flowing across the boundary
between them. (The EDL is further discussed below in connection
with FIG. 6.)
[0017] As is true in conventional capacitors, capacitance in an
ultracapacitor is proportional to the surface area of the
electrodes. Thus, one could make a very high-capacitance capacitor
using, for example, a porous silicon electrode oxidized with
silicon dioxide (SiO.sub.2) along with a metal or polysilicon
structure as the other electrode. The very high surface area of the
porous silicon would be a major contributor to the high capacitance
that could be achieved with such a capacitor. The capacitance could
be increased still further--even significantly increased--by
placing an electrolyte 150 in physical contact with the porous
structure, thereby introducing an EDL.
[0018] Electrolyte 150 (as well as other electrolytes described
herein) is represented in the drawings using a random arrangement
of circles. This representation is intended to convey the idea that
the electrolyte is a substance (liquid or solid) containing free
ions. The circles were chosen for convenience and are not intended
to imply any limitation as to the electrolyte components or
qualities, including any limitation with respect to the size,
shape, or number of the ions. One type of electrolyte that may be
used in accordance with embodiments of the invention is an ionic
liquid. Another is an electrolyte (e.g., LiPF.sub.6) comprising an
ion-containing solvent. Organic electrolytes and solid-state
electrolytes are also possible.
[0019] Pseudocapacitors are energy storage devices that behave like
capacitors but also exhibit reactions that result in charge
storage. Typically, one of the electrodes of a pseudocapacitor is
coated with a transition metal oxide such as MnO.sub.2, RuO.sub.2,
NiO.sub.x, Nb.sub.2O.sub.5, V.sub.2O.sub.5, etc., or with other
materials including WC (tungsten carbide), any suitable conducting
polymer, or a similar material. These materials can be used with an
electrolyte such as potassium hydroxide (KOH); when the device is
charged the potassium will react with the material in a reaction
that allows energy to be stored in a manner similar to a battery's
energy storage mechanism. More specifically, these materials store
energy through highly-reversible surface redox (faradic) reactions,
but at the same time the electric double layer energy storage
mechanism remains in place and provides the potential for high
power. A potential downside of a pseudocapacitor is that they, like
batteries, may degrade, thus allowing only a few hundred to a few
thousand discharge cycles.
[0020] Hybrid ultracapacitors are energy storage devices that
combine the attributes of ultracapacitors and batteries. In one
example, an electrode coated with a lithium ion material is
combined with an ultracapacitor in order to create a device that
has an ultracapacitor's rapid charge and discharge characteristics
and a battery's high energy density. On the other hand, hybrid
ultracapacitors, like batteries and pseudocapacitors, have shorter
expected lifespans than do ultracapacitors.
[0021] In one embodiment of the invention, a method of increasing
an energy density of an energy storage device comprises increasing
the capacitance of the energy storage device by depositing a
material into the porous structure using an atomic layer deposition
process and adjusting at least one of a pressure and an exposure
time of the atomic layer deposition process based on an aspect
ratio of at least one of the channels. In another embodiment, the
method comprises increasing the capacitance by performing a
procedure designed to increase a distance to which an electrolyte
penetrates within the channels. In another embodiment, the method
comprises increasing the capacitance by placing a dielectric
material into the porous structure. In still another embodiment, a
method of increasing the energy density comprises adding a
transition metal oxide to an ultracapacitor in order to create a
pseudocapacitor, and in yet another embodiment, the method
comprises increasing the breakdown voltage.
[0022] In another embodiment, the electrically conductive structure
of the energy storage device further comprises an alloy composed at
least in part of a first substance and an electrically conductive
second substance, and the method comprises annealing the energy
storage device in order to cause the electrically conductive second
substance to diffuse to a surface of the electrically conductive
structure and form an electrically conductive layer thereon. In
another embodiment, a method of increasing an achievable power
output of an energy storage device comprises depositing an
electrically conductive material into the porous structure.
[0023] Referring now to the drawings, FIGS. 1 and 2 are
cross-sectional views of an energy storage device 100 to which
methods according to embodiments of the invention are directed. As
illustrated in FIGS. 1 and 2, energy storage device 100 comprises
an electrically conductive structure 110 and an electrically
conductive structure 120 separated from each other by a separator
or insulator 130. Insulator 130 prevents electrically conductive
structures 110 and 120 from physically contacting each other so as
to prevent an electrical short circuit. In other embodiments, for
reasons discussed below, a separator is not necessary and can be
omitted.
[0024] At least one of electrically conductive structures 110 and
120 comprises a porous structure containing multiple channels, each
one of which has an opening to a surface of the porous structure.
As an example, the porous structure may be formed within a
conductive or a semiconductive material. Alternatively, the porous
structure may be formed within an insulating material (e.g.,
alumina) that has been coated with an electrically conductive film
(e.g., an ALD conductive film such as TiN). In this regards,
materials having greater electrical conductivity are advantageous
because of their lower effective series resistance. In the
illustrated embodiments both electrically conductive structure 110
and electrically conductive structure 120 comprise such a porous
structure. Accordingly, electrically conductive structure 110
comprises channels 111 with openings 112 to a surface 115 of the
corresponding porous structure and electrically conductive
structure 120 comprises channels 121 with openings 122 to a surface
125 of the corresponding porous structure. In an embodiment where
only one of electrically conductive structures 110 and 120
comprises a porous structure with multiple channels, the other
electrically conductive structure can be, for example, a metal
electrode or a polysilicon structure.
[0025] Various configurations of energy storage device 100 are
possible. In the embodiment of FIG. 1, for example, energy storage
device 100 comprises two distinct porous structures (that is,
electrically conductive structure 110 and electrically conductive
structure 120) that have been bonded together face-to-face with
separator 130 in between. As another example, in the embodiment of
FIG. 2 energy storage device 100 comprises a single planar porous
structure in which a first section (electrically conductive
structure 110) is separated from a second section (electrically
conductive structure 120) by a trench 231 containing separator 130.
One of the electrically conductive structures will be the positive
side and the other electrically conductive structure will be the
negative side. Separator 130 permits the transfer of ions but
prevents the electrodes from physically contacting each other
(which could cause an electrical malfunction in the device). As an
example, a porous plastic material could be used as separator 130.
It should be noted that the separator, although shown in FIG. 2,
may not be necessary in the configuration illustrated there because
other mechanisms (e.g., the small bridge connecting structures 110
and 120, a connection to a non-illustrated supporting layer or
other support structure) are in place that will maintain a physical
separation between structures 110 and 120. For example,
electrically conductive structures 110 and 120 could each be
attached to a ceramic package that would act as an electrical
insulator and would therefore electrically insulate the two
electrically conductive structures from each other by keeping them
physically separate.
[0026] The small bridge of material shown in FIG. 2 and mentioned
above may itself, if left unaddressed, act as an electrical short
between the two electrically conductive structures. There are
several possible solutions, however. For example, the bridge may be
removed using a polishing operation (and the conductive structure
held apart by some other means). Alternatively, the electrically
conductive structures may be formed in a heavily-doped top layer or
region of a wafer while the trench extends down to an underlying
lightly-doped substrate that is not a very good conductor. Or a
silicon-on-insulator structure may be used.
[0027] As an example, the porous structure of electrically
conductive structures 110 and 120 can be created by a wet etch
process in which a liquid etchant applied to a surface of the
electrically conductive structures etches away portions of the
electrically conductive structure in a way that is at least
somewhat similar to the way water is able to carve channels in
rock. This is why each one of the channels has an opening to the
surface of the electrically conductive structure; the wet etch
method is incapable of creating fully-enclosed cavities, i.e.,
cavities with no opening to the surface, like an air babble trapped
inside a rock, within the porous structure. This is not to say that
those openings cannot be covered with other materials or otherwise
closed up because of the presence of or addition of other
materials--that is in fact likely to occur in several
embodiments--but, whether covered or not, the described openings to
the surface are a feature of each channel in each porous structure
according to at least one embodiment of the invention. (One
embodiment in which the openings may be covered up is one in which
a layer of epitaxial silicon as a location for circuitry or other
wiring is grown on top of the channels).
[0028] It should be noted that the FIG. 1 and FIG. 2 depictions of
the porous structures are highly idealized in that, to mention just
one example, all of channels 111 and 121 are shown as only
extending vertically. In reality the channels would branch off in
multiple directions to creak a tangled, disorderly pattern that may
look something like the porous structure shown in FIG. 3.
[0029] FIGS. 3a and 3b are scanning electron microscope (SEM)
images of, respectively, a surface and a cross-sectional slice of a
porous structure 300 (in this case porous silicon) according to
embodiments of the invention. As illustrated, porous structure 300
contains multiple channels 311. It should be understood that
channels 311 are likely to twist and turn along their lengths such
that a single channel may have both vertical and horizontal
portions as well as portions that are neither completely vertical
nor completely horizontal but fall somewhere in between. Note that
in FIG. 3b, the channels extend near to but do not quite reach a
bottom of the etched structure, thus leaving a layer 312 of
un-etched silicon underneath the channels.
[0030] With the right etchant, it should be possible to make porous
structures having the described characteristics from a wide variety
of materials. As an example, a porous silicon structure may be
created by etching a silicon substrate with a mixture of
hydrofluoric acid and ethanol. More generally, porous silicon and
other porous structures may be formed by such processes as
anodization and stain etching.
[0031] Besides porous silicon, which has already been mentioned,
some other materials that may be especially well-suited for energy
storage devices according to embodiments of the invention are
porous germanium and porous tin. Possible advantages of using
porous silicon include its compatibility with existing silicon
technology. Porous germanium enjoys a similar advantage as a result
of existing technology for that material and, as compared to
silicon, enjoys the further possible advantage that its native
oxide (germanium oxide) is water-soluble and so is easily removed.
(The native oxide that forms on the surface of silicon may trap
charge--which is an undesirable result--especially where the
silicon porosity is greater than about 20 percent.) Porous
germanium is also highly compatible with silicon technology.
Possible advantages of using porous tin, which is a zero-band-gap
material, include its enhanced conductivity with respect to certain
other conductive and semiconductive materials. Other materials may
also be used for the porous structure, including silicon carbide,
alloys such as an alloy of silicon and germanium, and metals such
as copper, aluminum, nickel, calcium, tungsten, molybdenum, and
manganese.
[0032] Embodiments of the invention may make use of very narrow
channels. In certain embodiments (to be described in detail below),
an electrolyte is introduced into the channels. For example, the
electrolyte may be an organic electrolyte or an ionic liquid.
Molecules in the electrolyte may be on the order of 2 nanometers
(nm). In at least one embodiment, therefore, a smallest dimension
of each one of the channels is no less than 2 nm so as to permit
the electrolyte to flow freely along the entire length of the
channels.
[0033] Forcing (or otherwise enabling) an electrolyte to penetrate
deep within the channels increases the overall capacitance of the
energy storage device, leading to an increase in energy density.
Embodiments of the invention address several other techniques
(besides tailoring the size of the channels as mentioned above) for
increasing a distance by which the electrolyte penetrates within
the channels (with the consequent increases in capacitance and
energy density). Described below are several procedures designed to
increase a distance by which an electrolyte penetrates within the
channels of an energy storage device of a type that has been
described herein. The procedures may also allow the use of
electrolytes having viscosities that would otherwise be too high.
The particulars of each procedure determine whether the electrolyte
should be introduced before, during, or after the performance of
the procedure (or whether the timing of the electrolyte
introduction doesn't matter).
[0034] FIG. 4 is a flowchart illustrating a method 400 of
increasing an energy density of an energy storage device according
to an embodiment of the invention. A step 410 of method 400 is to
provide an energy storage device comprising at least one porous
structure containing multiple channels, wherein each one of the
channels has an opening to a surface of the porous structure. In
other words, method 400 is directed to an energy storage device of
a type described herein.
[0035] A step 420 of method 400 is to increase the capacitance of
the energy storage device by performing a procedure designed to
increase a distance to which an electrolyte (or a precursor or
other deposition agent, an ionic fluid, or the like) penetrates
within the channels. As mentioned, depending on the procedure the
electrolyte may be introduced before, during, or after the
performance of the procedure.
[0036] One such procedure comprises placing the energy storage
device in a vacuum and then applying the electrolyte. Another
procedure comprises subjecting the energy storage device to
ultrasonic vibration. Still another procedure comprises placing the
energy storage device in a centrifuge, in which case it has been
found that rotating the centrifuge at a rate of at least 500
rotations per minute works well to drive the electrolyte into the
channels as desired. In some embodiments, the channels of the
porous structure extend completely through the porous structure. A
structure of this kind could be advantageous in forming enhanced
energy storage devices in conjunction with electrolyte solutions,
separators, and conductive electrodes as described elsewhere in
this document. In such continuous-channel embodiments, the
penetration distance of an electrolyte (or other substance) can be
increased by using a pressure differential, a thermal gradient,
osmotic pumping, and the like, as well as ultrasonic vibration,
which was mentioned earlier.
[0037] Yet another procedure comprises applying a surface treatment
to a surface of the channels. In one embodiment, the surface
treatment comprises making those surfaces more wettable by
depositing a material on surfaces of the channels. There are
several materials that have been found to work well for this
purpose, including (but not limited to) TiO.sub.2, TiN, TaN, SiN,
MN, Al.sub.2O.sub.3, HfO.sub.2, Ta.sub.2O.sub.5, Er.sub.2O.sub.3,
TiAlN, and Nb.sub.2O.sub.5. Certain of these materials (notably
TiN, HfO.sub.2, and Ta.sub.2O.sub.5) work well in conjunction with
organic electrolytes; certain others (notably TiO.sub.2, TiN, and
HfO.sub.2) work well in conjunction with ionic liquids and solid
state electrolytes.
[0038] Referring again to FIG. 1, energy storage device 100 further
comprises (in the illustrated embodiment) an electrically
conductive coating 140 on at least a portion of the porous
structure and in at least some of channels 111 and/or channels 121.
Such an electrically conductive coating may be necessary in order
to maintain or enhance the conductivity of the porous
structure--especially where the porosity of the porous structure
exceeds about 20 percent. As an example, electrically conductive
coating 140 may be a silicide or a germanide. As another example,
electrically conductive coating 140 may be a coating of metal or a
metal alloy such as, for example, aluminum, nickel, tin, copper,
palladium, ruthenium, and tungsten, or other electrical conductors
such as carbon (graphene), WN.sub.2, TiN, AlTiN, TaN, W--Ti--N,
Ti--Si--N, W--Si--N, Ti--B--N, and Mo--N. Each of the listed
materials has the advantage of being used in existing CMOS
technology. Furthermore, the noble metals may be of particular
interest in cases where superior resistance to oxidation is
desired. Other metals such as nickel and calcium as well as
silicides or germanides of any of the foregoing may also be used.
These materials may be applied using processes such as
electroplating, chemical vapor deposition (CVD), and/or atomic
layer deposition (ALD).
[0039] In cases where the at least one electrically conductive
structure of the energy storage device comprises an alloy composed
at least in part of a first substance and an electrically
conductive second substance, an alternative application method may
be employed. This method (also described below as method 500)
involves annealing the energy storage device in order to cause the
electrically conductive second substance to diffuse to a surface of
the electrically conductive structure and form an electrically
conductive layer thereon. It should be understood that the surface
on which the electrically conductive layer is formed includes the
interior surfaces within the channel and not just the surface
(e.g., surface 115 or surface 125) in which the channel is
formed.
[0040] FIG. 5 is a flowchart illustrating a method 500 of
increasing an energy density of an energy storage device according
to an embodiment of the invention. A step 510 of method 500 is to
provide an energy storage device comprising at least one porous
structure containing multiple channels, wherein each one of the
channels has an opening to a surface of the porous structure.
Additionally, the electrically conductive structure comprises an
alloy composed at least in part of a first substance and an
electrically conductive second substance. In other words, method
500 is directed to an energy storage device of a type described
herein.
[0041] A step 520 of method 500 is to anneal the energy storage
device in order to cause the electrically conductive second
substance to diffuse to a surface of the electrically conductive
structure and torr an electrically conductive layer thereon.
[0042] As one example, the alloy may be silicon carbide (SiC). This
substance may be applied to at least some of the channels of an
energy storage device of the kind described herein using, for
example, any of the techniques listed above. Following such
application, an anneal may be performed. The anneal causes the
carbon in the SiC to diffuse to the surface of the SiC alloy and
form a layer of electrically conductive graphite for other
electrically conductive carbon allotrope). It should be noted that
after the anneal takes place the material may no longer exhibit the
configuration that characterizes the alloy. It therefore may at
that point be misleading to continue referring to the material as
an alloy. For SiC, for example, the carbon, after the performance
of the anneal, will have diffused out of the alloy to form the
described electrically conductive layer and what remains is some
amalgamation of silicon and carbon--call it Si--C--and not
necessarily the precise substance known as SiC.
[0043] In an embodiment where electrolyte 150 is used, an electric
double layer is formed within the channels of the porous structure
as depicted schematically in FIG. 6. In that figure, an electrical
double layer (EDL) 630 has been formed within one of channels 111.
EDL 630 is made up of two layers of ions, one of which is the
electrical charge of the sidewalls of channel 111 (depicted as
being positive in FIG. 6 but which could also be negative) and the
other of which is formed by free ions in the electrolyte. EDL 630
electrically insulates the surface, thus providing the charge
separation necessary for the capacitor to function. The large
capacitance and hence energy storage potential of electrolytic
ultracapacitors arises due to the small (approximately 1 nm)
separation between electrolyte ions and the electrode.
[0044] In some embodiments of the invention, a dielectric material
may be placed between the electrolyte and the porous structure in
order to further enhance the capacitance of the energy storage
device. The following paragraphs are directed to methods according
to embodiments of the invention in which a capacitance (and hence
the energy storage density) of an energy storage device (having a
porous structure of a type described herein) is increased by
placing a dielectric material into the porous structure along with
an electrolyte or an ionic liquid. It should be mentioned here that
certain embodiments of the invention are independent of an added
dielectric; these embodiments involve simply the ionic liquid (or
other electrolyte) in the porous structure. It should also be
mentioned here that dielectric materials may be introduced into the
channels for other reasons besides increasing capacitance. Other
motivations for adding dielectric materials include surface
passivation and wettability enhancement, both of which are
addressed below.
[0045] FIG. 7 is a cross-sectional view of one of channels 111 of
energy storage device 100 according to an embodiment of the
invention in which a dielectric material 515 is located between
electrolyte 150 and porous structure 110. (The EDL is not shown in
FIG. 7 in order to avoid unnecessarily complicating the
drawing.)
[0046] FIG. 8 is a flowchart illustrating a method 800 of
increasing an energy density of an energy storage device according
to an embodiment of the invention. A step 810 of method 800 is to
provide an energy storage device comprising at least one porous
structure containing multiple channels, wherein each one of the
channels has an opening to a surface of the porous structure.
Additionally, the energy storage device further comprises an
electrolyte in physical contact with the porous structure. In other
words, method 800 is directed to an energy storage device of a type
described herein.
[0047] A step 820 of method 800 is to increase a capacitance of the
energy storage device by placing a dielectric material into the
porous structure. Any of several methods may be used to accomplish
step 820. In various embodiments such placement may be accomplished
using an electrografting nanotechnology process, a hydrothermal
growth process, an electroplating process, and an atomic layer
deposition process. Any of these approaches may be suitable for
filling high aspect ratio structures with dielectric materials.
Electrografting and hydrothermal growth techniques may be less
expensive than ALD, and may be better suited to high volume
manufacturing. Electroplating is a widely-used, cost-effective
technique that can be used to deposit elemental metallic
conductors. In one particular embodiment, nickel may be
electroplated onto a silicon substrate in order to achieve porous
nickel silicide. On the other hand, ALD works very well with higher
aspect ratios and permits deposition into smaller openings that do
not have to be electrically conductive.
[0048] Additional methods for placing the dielectric material into
the porous structure include a sol-gel synthesis process and a
venetian glass approach, Sol-gel synthesis is a chemical process in
which the material of interest is created using chemistry instead
of using (expensive) vacuum deposition equipment; this method is
well-suited for introducing nanoparticles having very high
dielectric constants (for boosting capacitance) into high aspect
ratio channels (provided the channel openings are wide enough for
the nanoparticles to fit within them). A venetian glass approach is
good for making long fibers with high surface area out of high-k
dielectric materials (defined herein as materials having a
dielectric constant of 3.9 or above).
[0049] One way in which a dielectric material can increase the
capacitance (and therefore the energy density) of an energy storage
device is by increasing an overall dielectric constant of the
energy storage device, while another way is by increasing the
surface wettability for an electrolyte. (Recall from above that
dielectric materials may in some (though not necessarily all)
embodiments be used in conjunction with electrolytes.) Yet another
way is through surface passivation: a dielectric material can be
used to chemically interact with dangling bonds at surfaces of the
energy storage device and thus render them chemically inert. In one
example, a TiO.sub.2 layer (0.5 nm thick) was deposited on a porous
silicon structure in order to passivate the silicon surface. An
electrically conductive TiN film was then deposited over the
TiO.sub.2 (for reasons that will be discussed below). One advantage
of such passivation is that it counteracts the effects of hydrogen
desorption (an effect observed at temperatures of 350.degree. C.
and above--a range that may be used for ALD) that, if left
unaddressed, can cause the energy storage device to glow red hot as
a result of an interaction between dangling bonds at the surfaces
of the device and the surrounding air.
[0050] Stated simply, the wettability of a material is a measure of
the degree to which a liquid is able to spread out over a surface
of that material. If a droplet of the liquid is able to completely
spread out and form a film on the material's surface (i.e., where
the contact angle between the droplet and the surface is zero), the
material is said to be perfectly wettable. In the context of the
present discussion, greater wettability is preferred because the
greater degree of spreading it allows leads to higher capacitances
and energy densities. More particularly, a greater wettability
assists in the process of driving the electrolyte down deeper
within the channels.
[0051] In light of the foregoing, in some embodiments of the
invention increasing an overall dielectric constant of the energy
storage device is done by introducing (for example by using one of
the methods mentioned above) a dielectric material having a
dielectric constant higher than that of the electrolyte (e.g.,
higher than the dielectric constant of the solvent of an organic
electrolyte). In other embodiments a material is introduced that
improves a wettability of the surface of the porous structure for
the electrolyte. (In other words, the material allows the
electrolyte to flow more easily across the surface of the porous
structure.) This latter material might be one that has a dielectric
constant lower than that of the electrolyte, or it might be one
that, like the dielectric material mentioned in the first sentence
of this paragraph, has a dielectric constant higher than that of
the electrolyte (in which case it would be especially conducive to
capacitance increases and would therefore be especially
advantageous).
[0052] Various candidates have been discovered for the dielectric
constant- and wettability-increasing materials discussed above. As
a first example, TiO.sub.2 may be deposited by ALD and may, because
it is diffusion limited, travel all the way to the ends of high
aspect ratio channels. A substance is characterized herein as
"diffusion limited" if it reacts slowly enough that it
diffuses--that is, travels--the entire length of the channel before
it reacts and creates a blockage therein. This property is
determined at least in part by the reactive sticking coefficient
and the nanopore size. A diffusion limited substance stands in
contrast to a "reaction limited" substance, which undergoes a
reaction before traversing the entire length of the channel,
thereby blocking the channel. In one embodiment, TiO.sub.2
increased the wettability of the surface of the energy storage
device to such a degree that a ten-fold increase in capacitance was
observed. In various embodiments, an electrolyte--perhaps having a
dielectric constant slightly higher than the TiO.sub.2--may
subsequently be introduced into the channels. Good results have
been obtained using both organic electrolytes and ionic liquids,
with higher capacitance generally being observed with the former
and higher voltages generally being observed with the latter. Other
examples of acceptable materials--several (though not all) of
which, advantageously, have dielectric constants greater than
40--include HfO.sub.2, HfTaO, HfTiON, HfTaON, Hf--Ti--Ta--O,
HfSiO.sub.4, HfTiO.sub.4, HfAlO.sub.3, HfBiON, Ta.sub.2O.sub.5,
Nb.sub.2O.sub.5, TiO.sub.2, BaTiO.sub.3, BaSrTiO.sub.3 (BST),
BaZrO.sub.3, ZrTiO.sub.4, ZrO.sub.2, La.sub.2O.sub.3,
Si.sub.3N.sub.4, SrTiO.sub.3 (STO), Al.sub.2O.sub.3, and
Er.sub.2O.sub.3. (Of these, at least Ta.sub.2O.sub.5 and TiO.sub.2
are also very good wetting agents, as mentioned above, and thus are
doubly advantageous.) The substances containing aluminum and
hafnium were observed to react more quickly than what might be
considered ideal (i.e., they were somewhat reaction limited), but
might both be useful in at least certain embodiments in spite of
that. Substances containing strontium tend to cause the dielectric
constant to drop--an undesirable result--but at the same time tend
to decrease leakage and increase breakdown voltage both of which
are desirable results.
[0053] In some embodiments, as has been mentioned, the electrolyte
is an ionic liquid. Ionic liquids are in some cases preferable to
organic electrolytes because ionic liquids can increase the
breakdown voltage of the energy storage device. This is especially
desirable because energy increases with the square of the voltage
according to Equation 1, meaning that even small increases in
available voltage yield larger increases--sometimes much larger
increases--in energy storage capacity. Examples of ionic liquids
(with double layer capacitance (if known) in units of
.mu.F/cm.sup.2 shown in brackets following each name) include:
IMIM-BF.sub.4 (1-Ethyl-3-methylimidazolium Tetrafluoroborate), EMIM
BF.sub.4 [10.6], EMIM OTF [12.4], EMIM NTF [11.7], 1.5 M
EMI-TfSI/PC [9.1], 1M Et.sub.4NBF.sub.4/PC [7.0], 0.1M KCl/H.sub.2O
[15.1], 3M H.sub.2SO.sub.4/H.sub.2O [14.6], BMPL NTF
(1-Butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide),
PDEA NTF (Ethyl-dimethyl-propylammonium
bis(trifluoromethylsulfonyl)imide), and EMIM FAP
(1-Ethyl-3-methylimidazolium
tris(pentafluoroethyl)trifluorophosphate). For each substance,
either the pure ionic liquid or its acetonitrile mixture/solution
may be used.
[0054] FIG. 9 is a flowchart illustrating a method 900 of
increasing an energy density of an energy storage device according
to an embodiment of the invention directed at least in part to
increasing a breakdown voltage of the energy storage device. A step
910 of method 900 is to provide an energy storage device comprising
at least one porous structure containing multiple channels, wherein
each one of the channels has an opening to a surface of the porous
structure. In other words, method 900 is directed to an energy
storage device of a type described herein.
[0055] A step 920 of method 900 is to increase a breakdown voltage
of the energy storage device by placing an ionic liquid in physical
contact with the porous structure. In various embodiments, the
electrolyte may be used in conjunction with a dielectric material
in ways and tier reasons such as those that have been discussed
above. Accordingly, the dielectric material can in some embodiments
have a dielectric constant higher than that of the electrolyte
and/or can improve a wettability of the surface of the porous
structure for the ionic liquid.
[0056] The foregoing discussion included a reference to the
deposition of a dielectric material into the porous structure of an
energy storage device, and as part of that discussion it was
mentioned that the deposition may be accomplished using ALD. The
ALD concept will now be revisited in a slightly more general
context in connection with additional embodiments of the invention
and with reference to FIG. 10, which is a flowchart illustrating a
method 1000 of increasing an energy density of an energy storage
device in accordance with an embodiment of the invention.
[0057] A step 1010 of method 1000 is to provide an energy storage
device comprising at least one porous structure containing multiple
channels, wherein each one of the channels has an opening to a
surface of the porous structure. In other words, method 1000 is
directed to an energy storage device of a type described
herein.
[0058] A step 1020 of method 1000 is to increase a capacitance of
the energy storage device by depositing a material (not necessarily
a dielectric material) into the porous structure using an atomic
layer deposition process. Through-substrate ALD can be used to coat
channels in the porous structure for wafers that are etched
completely through, in which case the deposition process may be
much faster. In one embodiment this may be done using a
roll-to-roll ALD process. In another embodiment, the process may be
accomplished using a batch ALD reactor that can operate between 0.1
and 760 Torr. Another advantage of using ALD is that it can help
terminate the bonds at the surface or improve the wettability of
the surface. As has been mentioned elsewhere herein, increasing the
wettability allows an electrolyte to penetrate deeper into the
channels of the porous structure, thereby increasing capacitance.
Terminating surface bonds might alter the charging/discharging
behavior of the capacitor so that it is more physical and less
chemical. More specifically, it has been found that some of the
energy of the energy storage device is actually being stored as a
surface reaction, and that reduces the device's power. An
ALD-deposited material placed within the channels of the porous
structure can terminate dangling bonds at the surfaces of the
channels in order to mitigate this effect.
[0059] A step 1030 of method 1000 is to adjust at least one of a
pressure and an exposure time of the atomic layer deposition
process based on an aspect ratio of at least one of the
channels.
[0060] In one embodiment, the aspect ratio is at least 10.sup.3 and
for each precursor in a cycle the exposure time is at least 10
seconds and the pressure is at least 0.1 Torr. Of course, lower
pressures will also work as long as longer exposure times are
accepted. Similarly, shorter times can be achieved at even higher
pressures. At relatively higher pressures and/or longer times, the
amount of precursor used can become substantial. In order to reduce
the precursor amount, and therefore the related cost, embodiments
of the invention make use of the "stop-flow" ALD technique, in
which the precursor flow is stopped during the exposure time so as
to reduce the amount of precursor used.
[0061] Many cycles are typically needed in order to deposit an A/D
film, and within each cycle two precursors are typically
alternated--with a purge cycle in between to remove one precursor
before the other one is introduced. (The second of the two
precursors to be introduced is sometimes referred to as the
coreactant.) ALD purge cycles are usually performed using an inert
gas such as N.sub.2 or Ar. In some circumstances a vacuum purge may
also be used, as this additional purge may be necessary to
completely remove precursors/coreactants and byproducts and to
avoid undesirable chemical vapor deposition processes. In one
particular case, a TiO.sub.2 film about 4-5 nanometers thick was
deposited using a 40-cycle ALD process at 400.degree. C. in which
each cycle incorporated a 20-second exposure to TiCl.sub.4 followed
by a 180-second purge, a 10-second exposure to H.sub.2O, and
another 180-second purge.
[0062] An ALD process can also be used to increase an achievable
power output of an energy storage device, as can other processes
that are discussed herein and/or are known in the art. These
concepts will now be discussed in connection with FIG. 11, which is
a flowchart illustrating a method 1100 according to an embodiment
of the invention.
[0063] A step 1110 of method 1100 is to provide an energy storage
device comprising at least one porous structure containing multiple
channels, wherein each one of the channels has an opening to a
surface of the porous structure. In other words, method 1100 is
directed to an energy storage device of a type described
herein.
[0064] A step 1120 of method 1100 is to deposit an electrically
conductive material into the porous structure. The electrically
conductive material in the porous structure reduces effective
series resistance (ESR), thereby improving performance. For
example, a device having lower ESR is able to deliver higher power
(which may be manifested in terms of greater acceleration, more
horse power, etc.). In contrast, higher ESR (a condition that
prevails inside a typical battery) limits the amount of available
energy, at least partially due to the fact that much of the energy
is wasted as heat. Examples of suitable electrically conductive
materials include, but are not limited to, tungsten, aluminum,
copper, nickel, carbon (graphene), palladium, ruthenium, tin, and
alloys including AlTiN, TiN, WN.sub.2, TaN, W--Ti--N, Ti--Si--N,
W--Si--N, Ti--B--N, and Mo--N. In one scenario, a very conductive
TiN film (resistivity as low as .about.20 .mu.ohm-cm) could be
deposited using an ALD process at substrate temperatures of
.about.300-400.degree. C. In another scenario, oxygen co-reactant
based ALD processes could be used to deposit Pd or Ru.
[0065] In one embodiment, step 1120 is accomplished using an atomic
layer deposition process. In another embodiment, step 1120 is
accomplished using an electroplating process. As mentioned above,
other deposition and material formation processes are also
possible.
[0066] In another embodiment, step 1120 may be combined with the
deposition of a dielectric in order to form a conductor-dielectric
bi-layer on top of which an electrolyte may be added. Depending on
the materials chosen, good results may be obtained for reduced ESR,
increased capacitance and/or breakdown voltage, and so forth. In
certain embodiments the materials may be deposited using ALD, but
any of the deposition techniques disclosed herein or as known in
the art may be used. One advantage of using ALD in this scenario is
that the conductive layer and the dielectric layer can be deposited
(sequentially) in the same deposition chamber, thus representing
some cost savings.
[0067] Several methods of increasing an energy storage density of
an energy storage device have been disclosed herein. Another such
method will now be discussed in connection with FIG. 12, which is a
flowchart illustrating a method 1200 according to an embodiment of
the invention.
[0068] A step 1210 of method 1200 is to provide an energy storage
device comprising at least one porous structure containing multiple
channels, wherein each one of the channels has an opening to a
surface of the porous structure. In other words, method 1200 is
directed to an energy storage device of a type described
herein.
[0069] A step 1220 of method 1200 is to deposit a material into the
porous structure in order to form a pseudocapacitor. In some
embodiments the material can be a transition metal oxide such as,
for example, MnO.sub.2, RuO.sub.2, NiO.sub.x, Nb.sub.2O.sub.5, or
V.sub.2O.sub.5. In other embodiments the material could be WC or a
conducting polymer. In the same or other embodiments, depositing
the material into the porous structure is accomplished using an
atomic layer deposition process. Other deposition or formation
methods are also possible.
[0070] Although the invention has been described with reference to
specific embodiments, it will be understood by those skilled in the
art that various changes may be made without departing from the
spirit or scope of the invention. Accordingly, the disclosure of
embodiments of the invention is intended to be illustrative of the
scope of the invention and is not intended to be limiting. It is
intended that the scope of the invention shall be limited only to
the extent required by the appended claims. For example, to one of
ordinary skill in the art, it will be readily apparent that the
energy storage device and the related structures and methods
discussed herein may be implemented in a variety of embodiments,
and that the foregoing discussion of certain of these embodiments
does not necessarily represent a complete description of all
possible embodiments.
[0071] Additionally, benefits, other advantages, and solutions to
problems have been described with regard to specific embodiments.
The benefits, advantages, solutions to problems, and any element or
elements that may cause any benefit, advantage, or solution to
occur or become more pronounced, however, are not to be construed
as critical, required, or essential features or elements of any or
all of the claims.
[0072] Moreover, embodiments and limitations disclosed herein are
not dedicated to the public under the doctrine of dedication if the
embodiments and/or limitations: (1) are not expressly claimed in
the claims; and (2) are or are potentially equivalents of express
elements and/or limitations in the claims under the doctrine of
equivalents.
* * * * *