U.S. patent application number 14/265289 was filed with the patent office on 2014-10-30 for rechargeable power source for mobile devices which includes an ultracapacitor.
The applicant listed for this patent is ULTORA, INC.. Invention is credited to PHILIP A. KRAUS, YOU LI, HOANG NGUYEN LY, Cattien V. NGUYEN, DARRELL L. NIEMANN.
Application Number | 20140321027 14/265289 |
Document ID | / |
Family ID | 51789088 |
Filed Date | 2014-10-30 |
United States Patent
Application |
20140321027 |
Kind Code |
A1 |
NGUYEN; Cattien V. ; et
al. |
October 30, 2014 |
Rechargeable Power Source For Mobile Devices Which Includes An
Ultracapacitor
Abstract
Provided herein is a rechargeable power source that can be
quickly charged and use for charging mobile and cordless devices.
The power source includes an ultracapacitor which comprises a
composite structure including carbon nanotubes attached to an oxide
layer.
Inventors: |
NGUYEN; Cattien V.; (SAN
JOSE, CA) ; LI; YOU; (SUNNYVALE, CA) ;
NIEMANN; DARRELL L.; (SANTA CLARA, CA) ; LY; HOANG
NGUYEN; (SAN JOSE, CA) ; KRAUS; PHILIP A.;
(SAN JOSE, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ULTORA, INC. |
SUNNYVALE |
CA |
US |
|
|
Family ID: |
51789088 |
Appl. No.: |
14/265289 |
Filed: |
April 29, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61817819 |
Apr 30, 2013 |
|
|
|
Current U.S.
Class: |
361/502 ;
977/742 |
Current CPC
Class: |
Y10S 977/742 20130101;
Y02E 60/13 20130101; H01G 11/28 20130101; H01G 11/46 20130101; H01G
11/36 20130101; H01G 11/04 20130101; B82Y 30/00 20130101 |
Class at
Publication: |
361/502 ;
977/742 |
International
Class: |
H01G 11/04 20060101
H01G011/04 |
Claims
1. A rechargeable power source which is quickly charged and is used
for charging mobile devices comprising an ultracapacitor used as an
energy storage unit in the power source which has a composite
structure comprising: a metal foil with thickness less than 500 um;
a metal oxide layer disposed on the metal foil surface; and carbon
nanotubes disposed on the metal oxide layer; wherein the metal
oxide layer thickness is less than 100 nm; and wherein the metal
oxide layer is comprised of more than one metal atom.
2. The power source of claim 1, wherein the ultracapacitor is used
in combination with a battery as energy storage unit.
3. The power source of claim 1, wherein the power source is fully
charged in less than 10 minutes.
4. The power source of claim 1, wherein the power source is fully
charged in less than 5 minutes.
5. The power source of claim 1, wherein the power source is fully
charged in less than 1 minute.
6. The power source of claim 1, wherein the total capacity of the
power source is at least 5 mAh or 0.025 Wh.
7. The power source of claim 6, wherein the mobile device is a
Universal Serial Device and is charged by a Universal Serial
Bus.
8. The power source of claim 1, wherein the input for the power
source is an AC plug.
9. The power source of claim 8, wherein the AC plug is connected to
a wall mounted electricity outlet.
10. The power source of claim 1, wherein the power source is
charged at greater than 20W.
11. The power source of claim 1, wherein the power source is
charged at greater than 50W.
12. The power source of claim 1, wherein the power source is
portable.
13. The power source of claim 12, wherein the power source is used
to charge mobile phones.
14. The power source of claim 12, wherein the power source is used
to charge laptop computers.
15. The power source of claim 12, wherein the power source is used
to power a light source.
16. The power source of claim 1, wherein the power source is used
to charge cordless power tools.
17. The power source of claim 1, wherein the ultracapacitor energy
storage unit comprises multiple pairs of stacked electrodes.
18. The power source of claim 1, wherein the carbon nanotubes of
the ultracapacitor comprise a metal oxide coating comprised of
oxides of titanium, vanadium, iron, nickel, manganese, ruthenium,
molybdenum, cobalt, chromium, or combinations thereof.
19. The power source of claim 1, wherein the carbon nanotubes of
the ultracapacitor are unzipped to form open graphine structures or
graphine nanoribbons.
20. The power source of claim 1, wherein the ultracapacitor
comprises electrolytes, aqueous electrolytes, ionic liquids and
electrolytes soluble in organic solvents.
Description
[0001] This application claims priority under 35 U.S.C. .sctn.119
(e) from U.S. Provisional Application Ser. No. 61/817,819, filed
Apr. 30, 2013, which is hereby incorporated by reference in its
entirety.
FIELD
[0002] Provided herein is a rechargeable power source that can be
quickly charged and used for charging mobile devices. The power
source includes an ultracapacitor which comprises a composite
structure including carbon nanotubes attached to an oxide
layer.
BACKGROUND
[0003] Energy storage devices, are increasingly important in
powering a wide variety of devices such as, for example, motor
vehicles, cellular telephones, computers, etc. However, a
significant problem with currently available energy storage devices
is the slow rate of charging of these mobile devices. Typically,
currently available energy storage devices with sufficient energy
density require several hours for full recharging of mobile
devices.
[0004] Accordingly, what is needed is a power source with
sufficient energy density that quickly charges mobile devices.
SUMMARY
[0005] The present invention satisfies these and other needs by
providing, in one aspect, a rechargeable power source which quickly
charges mobile devices. The rechargeable power source includes at
least one ultracapacitor as the energy storage unit in the power
source, in which at least one electrode in the ultracapacitor has a
composite structure. The composite structure includes a metal foil
with thickness less than 500 um, a metal oxide layer disposed on
the metal foil surface and carbon nanotubes disposed on the metal
oxide layer, where the metal oxide layer thickness is less than 100
nm and where the metal oxide layer is comprised of more than one
metal atom.
[0006] In some embodiments, at least one of the metal atoms is a
catalyst for carbon nanotube growth. In other embodiments, the
carbon nanotubes are in electrical ohmic contact with the metal
foil.
DESCRIPTION OF THE FIGURES
[0007] FIG. 1 illustrates carbon nanotubes attached to an oxide
layer dispersed on a metal surface at 200 nm resolution as
visualized by transmission electron microscopy;
[0008] FIG. 2 processing of a composite structure comprising a
metal substrate and carbon nanotubes, where the carbon nanotubes
are attached to the metal oxide layer disposed on the metal
surface;
[0009] FIG. 3 illustrates one-sided carbon nanotube deposition
where carbon nanotubes are attached to a metal oxide layer disposed
on one surface of a metal substrate;
[0010] FIG. 4 illustrates two-sided carbon nanotube deposition
where carbon nanotubes are attached to metal oxide layers disposed
on two surfaces of a metal substrate;
[0011] FIG. 5A illustrates carbon nanotubes attached to a metal
oxide layer disposed on a metal surface in the presence of
amorphous carbon;
[0012] FIG. 5B illustrates carbon nanotubes attached to a metal
oxide layer disposed on a metal surface after amorphous carbon has
been removed;
[0013] FIG. 6 is a block diagram of an exemplary ultracapacitor
comprising composite structures as electrodes.
[0014] FIG. 7 illustrates an example of an energy storage device
composed of a metal substrate with two-sided carbon nanotube
deposition. A 3-electrode layer devices (two 1-side electrodes on
top and bottom and a 2-side electrode sandwiched in the middle is
illustrated. Two separators (dashed) are in between the electrodes.
This device is composed of two of 1-side CNT deposited
electrode.
[0015] FIG. 8A illustrates coupling of carbon nanotubes attached to
a metal oxide layer disposed on a metal surface to a membrane.
[0016] FIG. 8B illustrates submersion in electrolyte solution of
carbon nanotubes attached to a metal oxide layer disposed on a
metal surface to a membrane.
[0017] FIG. 9 illustrates a power source a rechargeable,
fast-charging, portable power source with ultracapacitors (901) as
the energy storage unit. The ultracapacitor portable charger also
contains 1) an AC-DC power converter electronics (902) and an input
adaptor to an AC wall plug (902a) and 2) a DC output regulator
(903) with a DC adaptor to connect to a mobile device such as a
cell phone or laptop computer.
DETAILED DESCRIPTION
Definitions
[0018] Unless defined otherwise, all technical and scientific terms
used herein have the same meaning as is commonly understood by one
of ordinary skill in the art to which this invention belongs. In
the event that there is a plurality of definitions for a term
herein, those in this section prevail unless stated otherwise.
[0019] As used herein "AC plug" refer to a two- or three-prong male
plug for connection with 2 or 3 prong AC electricity outlets that
is commonly found in wall mounted receptacles.
[0020] As used herein "carbon nanotubes" refer to allotropes of
carbon with a cylindrical structure. Carbon nanotubes may have
defects such as inclusion of C5 and/or C7 ring structures, such
that the carbon nanotube is not straight; and may have contain
coiled structures; and may contain randomly distributed defected
sites in the C--C bonding arrangement. Carbon nanotubes may contain
one or more concentric cylindrical layers.
[0021] As used herein "ultracapacitors" include electrochemical
capacitors, electrical double layer capacitors, and
supercapacitors.
[0022] As used herein "chemical vapor deposition" refers to
plasma-enhanced chemical vapor deposition or thermal chemical vapor
deposition.
[0023] As used herein "plasma-enhanced chemical vapor deposition"
refers to the use of plasma (e.g., glow discharge) to transform a
hydrocarbon gas mixture into excited species which deposit carbon
nanotubes on a surface.
[0024] As used herein "thermal chemical vapor deposition" refers to
the thermal decomposition of hydrocarbon vapor in the presence of a
catalyst which may be used to deposit carbon nanotubes on a
surface.
[0025] As used herein "physical vapor deposition" refers to vacuum
deposition methods used to deposit thin films by condensation of a
vaporized of desired film material onto film materials and includes
techniques such as cathodic arc deposition, electron beam
deposition, evaporative deposition, pulsed laser deposition and
sputter deposition.
[0026] As used herein "unzipping" refers to process of full or
partial opening the tubular structures of carbon nanotubes to
increase total surface area of the composite structure. The
unzipping can be accomplished by any oxidation processes. The
carbon nanotubes in the composite structure can be fully unzipped
or be partially unzipped, depending on the condition of the
unzipping process as well as the nature of the defective sites of
the carbon nanotubes in the composite structure.
[0027] Mobile devices, such as cell phones, smart phones, tablets,
and laptop computers are ubiquitous with the advent of wireless
networks and the internet. Also, mobile devices can be a cordless
power tool such as an electric saw, an electric drill, an electric
screw driver, etc. Currently batteries are the main technology and
long charging time is the norm. Ultracapacitors have the ability to
charge at a much faster rate than a typical rechargeable battery
because of the higher power density of an ultracapacitor. Typical
charging time for a battery in a cell phone is between about 2-3
hours. In contrast, an ultracapacitor used in a cell phone can be
charged in tens of seconds to a few minutes. Accordingly, replacing
batteries in mobile devices with high power density ultracapacitors
can dramatically reduce charging time. Using the higher energy
density ultracapacitor technologies described herein maintains the
small size and portability of mobile devices while concurrently
allowing for rapid recharging.
[0028] In one aspect, a power source is provided that is
rechargeable and fast charging, where at least one ultracapacitor
is used as the energy storage unit in the power source and where
the ultracapacitor comprises vertically aligned carbon nanotubes
disposed on a metal oxide layer. In some embodiments, the carbon
nanotubes of the ultracapacitor are unzipped to form open graphine
structures or graphine nanoribbons. In other embodiments, the
ultracapacitor is used in combination with a battery as energy
storage unit. In still other embodiments, the carbon nanotubes of
the ultracapacitor are disposed upon a metal oxide coating
comprised of oxides of titanium, vanadium, iron, nickel, manganese,
ruthenium, molybdenum, cobalt, chromium, or combinations
thereof.
[0029] In some embodiments, the power source is used to charge
mobile phones. In other embodiments, the power source is used to
charge laptop computers. In other embodiments, the power source is
used to charge tablet computers. In still other embodiments, the
power source is used to power a light source. In still other
embodiments, the light source is a flashlight. In still other
embodiments, the power source is used to charge cordless power
tools. In still other embodiments, the power source is
portable.
[0030] In some embodiments, the power source is fully charged in
less than 10 minutes. In other embodiments, the power source is
fully charged in less than 5 minutes. In still other embodiments,
the power source is fully charged in less than 1 minute. In still
some embodiments, the charging of the power source is at a power
greater than 10 W, greater than 20 W, greater than 30 W, greater
than 40 W. In still other embodiments, the charging power of the
power source is greater than 50 W. In still other embodiments, the
total capacity of the power source is at least 5 mAh or 0.025
Wh.
[0031] In some embodiments, the output of the power source is a
power plug for charging mobile devices. In other embodiments, the
mobile device is a Universal Serial Device and is charged by a
Universal Serial Bus. In still other embodiments, the input for the
power source is an AC plug. In still other embodiments, the AC plug
is connected to a wall mounted electricity outlet.
[0032] Referring now to FIG. 9, a rechargeable power source with
ultracapacitors 901 as the energy storage unit is illustrated. The
power source also contains an AC-DC power converter electronics
902, an input AC plug for connecting to AC wall mounted outlet
902a, a DC output regulator 903 with an DC adaptor 903a which
allows for connection to a mobile device such as, for example, a
cell phone or laptop computer.
[0033] In some embodiments, the rechargeable power source may have
either or both the AC-DC power converters electronics and the DC
output regulator being separated housing unit(s) than that of the
package of the ultracapacitors.
[0034] Described below are ultracapacitors which may be used in the
rechargeable power sources described herein. In some aspects, a
composite structure which includes a metal oxide layer disposed on
a metal surface is provided. In some embodiments, the metal surface
has a root mean square roughness of less than about 100 nm. In
other embodiments, the metal surface includes any metal or any
combinations of metals. In other embodiments, the metal surface
comprises two or more of iron, nickel, aluminum, cobalt, copper,
chromium, gold, and combinations thereof. In still other
embodiments, metal surface is laminated on aluminum foils. In still
other embodiments, metal surface is laminated on copper foils.
[0035] In some aspects, a composite structure which includes a
metal oxide layer disposed on a metal surface is provided. In some
embodiments, the metal oxide layer includes any elements and
combinations thereof that catalyze the growth of carbon nanotubes.
In other embodiments, the metal oxide layer comprises oxides of two
or more of iron, nickel, aluminum, cobalt, copper, chromium, gold,
and combinations thereof. In still other embodiments, the metal
oxide layer comprises a catalyst for the growth of carbon
nanotubes. In still other embodiments, the metal oxide layer
includes particles of iron, nickel, aluminum, cobalt, copper,
chromium, gold, and combinations thereof.
[0036] In some embodiments, the metal oxide layer is less than
about 100 nm thick. In other embodiments, the metal oxide layer is
between about 100 nm and about 1 nm thick. In still other
embodiments, the metal oxide layer is between about 75 nm and about
4 nm thick. In still other embodiments, the metal oxide layer is
between about 50 nm and about 4 nm thick. In still other
embodiments, the metal oxide layer is between about 25 nm and about
4 nm thick.
[0037] In some embodiments, the metal surface includes any metal or
any combinations of metals. In other embodiments, the metal surface
includes iron, nickel, aluminum, cobalt, copper, chromium, gold and
combinations thereof. In still other embodiments, the metal surface
comprises one or more alloys comprised of two or more of iron,
nickel, cobalt, copper, chromium, aluminum, and gold. In still
other embodiments, the alloy is a complete solid solution alloy. In
still other embodiments, the alloy is a partial solid solution
alloy. In still other embodiments, the alloy is a substitutional
alloy. In still other embodiments, the alloy is an interstitial
alloy.
[0038] In some embodiments, the metal surface is that of a metal
foil and has a surface smoothness where the root mean square
roughness is less than about 500 nm. In other embodiments, the root
mean square roughness of the metal foil is less than about 200 nm.
In still other embodiments, root mean square roughness of the metal
foil is between about 2 nm and about 200 nm. In still other
embodiments, root mean square roughness of the metal foil is
between about 5 nm and about 100 nm.
[0039] In some embodiments, the metal foil is less than 500 .mu.m
thick. In other embodiments, the metal foil is between about 500
.mu.m and about 10 .mu.m thick. In still other embodiments, the
metal foil is between about 400 .mu.m and about 10 .mu.m thick. In
still other embodiments, the metal foil is between about 300 .mu.m
and about 10 .mu.m thick. In still other embodiments, the metal
foil is between about 200 .mu.m and about 10 .mu.m thick. In still
other embodiments, the metal foil is between about 100 .mu.m and
about 10 .mu.m thick. In still other embodiments, the metal foil is
between about 50 .mu.m and about 10 .mu.m thick.
[0040] In some embodiments, the metal foil is between about 500
.mu.m and about 1 .mu.m thick. In other embodiments, the metal foil
is between about 400 .mu.m and about 1 .mu.m thick. In still other
embodiments, the metal foil is between about 300 gm and about 1
.mu.m thick. In still other embodiments, the metal foil is between
about 200 .mu.m and about 1 .mu.m thick. In still other
embodiments, the metal foil is between about 100 .mu.m and about 1
.mu.m thick. In still other embodiments, the metal foil is between
about 50 .mu.m and about 1 .mu.m thick.
[0041] In some embodiments, the metal foil may be coated with a
material that prevents attachment of the metal oxide layer on the
metal foil (i.e., a protective coating). In other embodiments, the
protective coating may partially cover either side of the metal
foil. In still other embodiments, the protective coating completely
covers one side of the metal foil and partially covers the other
side of the metal foil. In still other embodiments, the protective
coating partially covers one side of the metal foil. In still other
embodiments, the protective coating completely covers one side of
the metal foil. In still other embodiments, neither side of the
metal foil is covered by a protective coating. In still other
embodiments, the protecting coating provides an area without carbon
nanotube for electrical tabs for device integration.
[0042] Generally, the metal foil can have any convenient or useful
width, length or geometric shape. In some embodiments, the metal
foil has a width greater than 1 mm. Generally, the width of the
metal foil may be any convenient width useful in a continuous
roll-to-roll manufacturing process. In some embodiments, the metal
foil has a length greater than 1 mm. In other embodiments, the
metal foil has a length greater than 1 m. In still other
embodiments, the metal foil has a length greater than 10 m. In
still other embodiments, the metal foil has a length greater than
100 m. In still other embodiments, the metal foil has a length
greater than 1000 m.
[0043] In some embodiments, chemical vapor deposition is used to
attach carbon nanotubes to a metal oxide layer disposed on a metal
foil in a continuous roll-to-roll manufacturing process. The only
requirement for the above is that the length of the metal foil is
sufficient for use in a roll-to roll manufacturing process.
Generally, the width and length of the metal foil may be any
convenient dimension for use in a continuous roll-to-roll
manufacturing process. In some embodiments, the length of the metal
foil is greater than 1 meter. In other embodiments, the length of
the metal foil is greater than 10 meters. In still other
embodiments, the length of the metal foil is greater than 100
meters. In still other embodiments, the length of the metal foil is
greater than 1000 meters.
[0044] In some embodiments, chemical vapor deposition is used to
attach carbon nanotubes to a metal oxide layer disposed on a metal
foil in a batch manufacturing process, where one or more metal foil
substrates are processed simultaneously. The metal foil may be
precut into any geometric form such as a circle, square, rectangle,
triangle, pentagon hexagon, etc. or any other form that may be
useful.
[0045] In some embodiments, chemical vapor deposition is used to
attach carbon nanotubes to a metal oxide layer disposed on a metal
foil in a continuous in-line manufacturing process, where one or
more metal foil substrates are processed sequentially through a
processing system with substrates moving linearly or radially
through one or more linked processing environments. The metal foil
may be precut into any geometric form such as a circle, square,
rectangle, triangle, pentagon hexagon, etc. or any other form that
may be useful.
[0046] In some embodiments, chemical vapor deposition is used to
attach carbon nanotubes to a film stack including a metal oxide
layer disposed on a metal foil in a cluster-tool manufacturing
process, where a substrate carrier comprising one or more metal
foil substrates is processed sequentially in one or more linked
processing systems in which a discrete processing step is carried
out sequentially on the substrate carrier. The metal foil may be
precut into any geometric form such as a circle, square, rectangle,
triangle, pentagon hexagon, etc. or any other form that may be
useful.
[0047] Referring now to FIG. 1, a composite structure including
carbon nanotubes 103 attached to metal oxide layer 102 disposed on
metal foil 101 is illustrated from a transmission electron
micrograph. Referring now to FIG. 2, processing of a metal surface
to an electrode including carbon nanotubes attached to a metal
oxide layer disposed on a metal foil is illustrated. Metal surface
200 is processed to metal oxide layer disposed on a metal surface
202 by a variety of processes, supra. Then, carbon nanotubes are
attached to metal oxide disposed on a metal surface 202 to provide
a composite structure comprising carbon nanotubes attached to a
metal oxide layer disposed on a metal foil 204.
[0048] A number of methods exist for making a composite structure
which comprises carbon nanotubes attached to a metal oxide layer
202 disposed on a metal surface 200. In some embodiments, the metal
oxide layer 202 can be deposited on the metal surface 200 by
conventional techniques, well known to those of skill in the art,
such as physical vapor deposition and chemical vapor
deposition.
[0049] In some embodiments, the metal surface 200 may be oxidized
by a variety of methods to provide a composite structure which
includes a metal oxide layer 202 disposed on a metal surface. In
some embodiments, the metal surface is oxidized with an oxidizing
gas at an elevated temperature. In other embodiments, the oxidizing
gas is water vapor, atomic oxygen, diatomic oxygen, ozone, nitric
oxide, nitrous oxide, chlorine, fluorine, or combinations thereof.
In still other embodiments, the elevated temperature is between
about 300.degree. C. and about 1100.degree. C.
[0050] In some embodiments, the metal surface 200 is oxidized by
exposure of the metal foil to an oxidizing agent in solution. In
some embodiments, the metal surface 200 is oxidized with an aqueous
solution comprising an oxidizing agent. In other embodiments, the
oxidizing agent is a peroxide, hydroperoxide, superoxide,
permanganate, chlorate or perchlorate.
[0051] In some embodiments, the metal surface 200 is oxidized with
plasma. In other embodiments, the plasma is formed from water
vapor, atomic oxygen, diatomic oxygen, ozone, nitric oxide, nitrous
oxide, chlorine, fluorine, or combinations thereof at an elevated
temperature. In still other embodiments, the elevated temperature
is between about 25.degree. C. and about 1100.degree. C.
[0052] Referring now to FIG. 3, carbon nanotubes 306 are attached
to metal oxide layer 304 disposed on metal surface 302 to provide a
one-sided carbon nanotube deposition 300. Referring now to FIG. 4,
carbon nanotubes 408 and 410 are attached to metal oxide layers 404
and 406 disposed on metal surface 402 to provide a two-sided carbon
nanotube deposition 400.
[0053] Referring now to FIG. 5 carbon nanotubes 504 are attached to
metal oxide layer 506 disposed on metal surface 504 to form a
composite structure. As a collective, the carbon nanotubes are
highly porous, have a large surface area and high percentage of
usable nanopores (i.e., mesopores between about 2 nm to about 50 nm
in diameter). Carbon nanotubes are chemically inert and
electrically conductive. Carbon nanotubes may be single walled or
multi-walled or combinations thereof. Carbon nanostructures useful
in the composite structures described herein include other forms
such as, for example, toruses, nanobuds and graphenated carbon
nanotubes. In some embodiments, the carbon nanotubes are vertically
aligned. In other embodiments, the carbon nanotubes are in a
vertical tower structure (e.g., perpendicular to the metal foil).
Other carbon nanotube configurations include, for example,
horizontal or random alignment. In some embodiments, the carbon
nanotubes are a random network with a minimal degree of alignment
in the vertical direction.
[0054] In some embodiments, carbon nanotubes 504 are attached to
metal oxide layer 506 by chemical vapor deposition processes. In
other embodiments, carbon nanotubes are attached to a metal oxide
layer disposed on a metal foil by thermal chemical vapor
deposition. In still other embodiments, carbon nanotubes are
attached to metal oxide layer disposed on a metal foil by
plasma-enhanced chemical vapor deposition.
[0055] Thermal chemical vapor deposition of carbon nanotubes is
usually performed with hydrocarbon sources (e.g., methane,
ethylene, acetylene, camphor, naphthalene, ferrocene, benzene,
xylene, ethanol, methanol, cyclohexane, fullerene, etc.), carbon
monoxide, or carbon dioxide at temperatures between about
600.degree. C. and 1200.degree. C. preferably, in the absence of
oxygen or reduced amounts of oxygen.
[0056] Plasma-enhanced chemical vapor deposition of carbon
nanotubes is usually performed with hydrocarbon sources, supra.
Here, electrical energy rather than thermal energy is used to
activate the hydrocarbon to form carbon nanotubes on metal foils at
preferred temperatures between about 300.degree. C. and greater
than 600.degree. C.
[0057] In some embodiments, a portion of the metal oxide layer
disposed on a metal surface is pretreated to prevent attachment of
carbon nanotubes to that portion of the layer. In other
embodiments, a portion of the metal oxide layer disposed on a metal
surface is pretreated with a film such as a metal film or an
organic (polymer) film that prevents the direct growth of carbon
nanotubes in these areas. Films such as those described above can
be deposited, for example, by metal evaporation methods (such as
thermal or e-beam evaporation) or by ink jet printing to give a
desired pattern. Protective films may also be patterned by using a
hard mask and/or photolithography techniques.
[0058] In some embodiments, plasma treatment (e.g., F.sub.2,
NH.sub.3) of carbon nanotubes surfaces is used to increase surface
wettability by increasing the hydrophilicity of the surface. Such
treatment enables ions from electrolytes to access the pores of the
carbon nanotubes which increase charge density.
[0059] Referring to FIG. 5a, during attachment of carbon nanotubes
504 to metal oxide layer 506 disposed on metal surface 502, a side
product is amorphous carbon 508. Amorphous carbon reduces the
porosity of carbon nanotubes, thus decreasing electrode
performance. In some embodiments, selection of hydrocarbon
precursors and control of temperature reduces the amount of
amorphous carbon formed. Amorphous carbon may be removed by a
number of methods including, for example, thermal or plasma
cleaning with O.sub.2 and exposure to strong acid, halogens and
strong oxidants (e.g., H.sub.2O.sub.2). In some embodiments, vapor
which includes water or H.sub.2O.sub.2 or combination thereof may
be used to remove amorphous carbon as described by Deziel et al.,
U.S. Pat. No. 6,972,056. FIG. 5b illustrates carbon nanotubes 504
attached to metal oxide layer 506 disposed on metal surface 502
after amorphous carbon has been removed.
[0060] In some embodiments, a continuous water treatment process is
used to remove impurities such as amorphous carbon from carbon
nanotubes. The process includes a wet inert carrier gas stream
(e.g., argon or nitrogen) and may include an additional dry carrier
gas stream which is added to adjust water concentration. Water is
added using any water infusion method (e.g., bubbler, membrane
transfer system, etc.). In some embodiments, water vapor is
introduced into a process chamber maintained at between 500.degree.
C. and 1200.degree. C. to remove amorphous carbon and other
impurities associated with carbon nanotubes attached to a metal
oxide layer disposed on a metal foil.
[0061] In some embodiments, amorphous carbon is removed in a
discrete step after deposition of carbon nanotubes on a metal oxide
layer disposed on a metal foil. In other embodiments, amorphous
carbon is removed simultaneously during chemical vapor deposition.
In still other embodiments, amorphous carbon is removed
simultaneously during chemical vapor deposition and also in a
discrete second step.
[0062] FIG. 6 is a block diagram of an exemplary ultracapacitor
600, which may be an electrochemical double layer capacitor with an
operating voltage of greater than 0.05 volt. Ultracapacitor 600 has
two carbon nanotube electrodes 604 separated by an electrolytic
membrane 606. In some embodiments, carbon nanotube electrodes 604
may be manufactured in any continuous manufacturing process
including roll to roll fashion. In some embodiments, carbon
nanotube electrodes 604 may be made with or without removal of
amorphous carbon and attached to metal foil which may include
catalysts or binders or may not.
[0063] Electrical leads 610 (e.g., thin metal wires) contact
collectors 602 (e.g., metal foils 602) to make electrical contact.
Ultracapacitor 600 is submerged in an electrolyte solution and
leads 610 are fed out of the solution to facilitate capacitor
operation. Clamp assembly 608 (e.g., coin cells or laminated cells)
holds carbon nanotubes 604 attached to metal foil 602 in close
proximity while membrane 606 maintain electrode separation (i.e.,
electrical isolation) and minimizes the volume of ultracapacitor
600.
[0064] In some embodiments, ultracapacitor 600 consists of two
vertically aligned multi-walled carbon electrode tower electrodes
604 attached to metal foil 602 and an electrolytic membrane 606
(e.g., Celgard or polypropylene) which are immersed in a
conventional aqueous electrolyte (e.g., 45% sulfuric acid or KOH).
In other embodiments, ultracapacitor 600 consists of two vertically
aligned single-walled carbon electrode tower electrodes 604
attached to metal foil 602 and an electrolytic membrane 606 (e.g.,
Celgard or polypropylene) which are immersed in a conventional
aqueous electrolyte (e.g., 45% sulfuric acid or KOH).
[0065] In some embodiments, the ultracapacitor is a
pseudo-capacitor. In some of these embodiments, carbon nanotubes
are loaded with oxide particles (e.g., RuO.sub.2, MnO.sub.2,
Fe.sub.3O.sub.4, NiO.sub.2, MgO.sub.2, etc.). In other of these
embodiments, carbon nanotubes are coated with electrically
conducting polymers (e.g., polypyrrole, polyaniline, polythiophene,
etc.). In some embodiments the ultracapacitor is an asymmetrical
capacitor (i.e., one electrode is different than the other
electrode in the capacitor).
[0066] In some embodiments, the ultracapacitors described herein
can be stacked to form multiple pairs of electrodes. In other
embodiments, the ultracapacitors described herein may be used to
form stacked sheets of electrodes.
[0067] Referring now to FIG. 7, an exemplary three electrode layer
device is illustrated. The device has two 1-side electrodes on the
top and bottom with a two side electrode sandwiched in the middle.
Two separators, as illustrated, are in between the electrodes.
[0068] Referring now to FIG. 8a, electrodes, which include carbon
nanotubes 804 attached to metal oxide layers 806 disposed on metal
surface 802 prepared as described, supra, and a membrane 808 is
selected. Membrane 808 is a porous separator such as, for example,
polypropylene, Nafion, Celgard, Celgard 3400 glass fibers or
cellulose. The electrodes, which include carbon nanotubes 804
attached to metal oxide layers 806 disposed on metal surface 802
are coupled to membrane 808 by a clamp assembly.
[0069] Referring now to FIG. 8b, carbon nanotubes 804 attached to
metal oxide layer 806 disposed on metal surface 802 and coupled to
membrane 808 are immersed in electrolyte (shaded portion of Figure)
which may be a liquid or gel. In some embodiments, carbon nanotubes
804 may be suffused with a gas or combinations thereof including
air. Alternatively, in some embodiments the space around carbon
nanotubes 804 may be evacuated by a vacuum source. In some
embodiments, electrolytes include, for example, aqueous
electrolytes (e.g., sodium sulfate, magnesium sulfate, potassium
chloride, sulfuric acid, magnesium chloride, etc.), organic
solvents (e.g., acetonitrile, propylene carbonate, tetrahydrofuran,
.gamma.-gamma butryolactone, etc.), ionic liquids (e.g.,
1-ethyl-3-methylimidazolium bis(pentafluoroethylsulfonyl)imide,
etc.), electrolyte salts soluble in organic solvents,
(tetralkylammonium salts (e.g., (C.sub.2H.sub.5).sub.4NBF.sub.4,
(C.sub.2H.sub.5).sub.3CH.sub.3NBF.sub.4,
(C.sub.4H.sub.9).sub.4NBF.sub.4, (C.sub.2H.sub.5).sub.4NPF.sub.6,
etc.) tetralkylphosphonium salts (e.g.,
(C.sub.2H.sub.5).sub.4PBF.sub.4, (C.sub.3H.sub.7).sub.4PBF.sub.4,
(C.sub.4H.sub.9).sub.4PBF.sub.4, etc.), lithium salts (e.g.,
LiBF.sub.4, LiPF.sub.6, LiCF.sub.3SO.sub.3, etc.,
N-alkyl-pyridinium salts, 1,3 bisalkyl imidazolium salts, etc.),
etc.
[0070] The composite structures comprising carbon nanotubes
described herein may be used in a wide variety of devices. Carbon
nanotubes may be used as electrodes for ultracapacitors, or lithium
ion batteries. In addition carbon nanotubes may be used in methane
and hydrogen storage, solar cells, electrocatalysts, and catalysts
supports for fuel cells, and porous carbon for lithium sulfur and
lithium oxygen batteries.
[0071] Ultracapacitors which include carbon nanotubes described
herein may be used in a wide variety of applications, such as for
example, electric transportation technology, (e.g., electric
vehicles, electric hybrid vehicles, micro hybrids, catalytic
converter preheater, etc.), electric utility industry (e.g.,
emergency backup power system, grid system stability improvement
system, charging devices, smart grids, etc.) consumer electronics,
(e.g., cellular telephones, cameras, computers, pagers, copy
machines, amplifiers, etc.) batteries (e.g., lithium, magnesium,
aluminum, lead, mercury, iron, cadmium, nickel batteries, etc.)
medical electronics (e.g., defillabrators, drug delivery units,
neurological stimulators, etc.), military devices (e.g., missiles,
aerial vehicles, communication devices, etc.) etc.
[0072] Finally, it should be noted that there are alternative ways
of implementing the present invention. Accordingly, the present
embodiments are to be considered as illustrative and not
restrictive, and the invention is not to be limited to the details
given herein, but may be modified within the scope and equivalents
of the appended claims.
[0073] All publications and patents cited herein are incorporated
by reference in their entirety.
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