U.S. patent application number 17/747660 was filed with the patent office on 2022-09-01 for aerosol-based high-temperature synthesis of materials.
The applicant listed for this patent is PRINCETON UNIVERSITY. Invention is credited to Christopher ABRAM, Yiguang JU, Maksym MEZHERICHER.
Application Number | 20220274843 17/747660 |
Document ID | / |
Family ID | 1000006344822 |
Filed Date | 2022-09-01 |
United States Patent
Application |
20220274843 |
Kind Code |
A1 |
JU; Yiguang ; et
al. |
September 1, 2022 |
AEROSOL-BASED HIGH-TEMPERATURE SYNTHESIS OF MATERIALS
Abstract
A material synthesis method may comprise: adding at least one
liquid precursor solution to an atomizer device; generating by the
atomizer device an aerosol comprising liquid droplets; transporting
the aerosol to a reactive zone for evaporating one or more solvents
from the aerosol; and collecting particles synthesized from at
least evaporating the aerosol.
Inventors: |
JU; Yiguang; (Princeton,
NJ) ; MEZHERICHER; Maksym; (Princeton, NJ) ;
ABRAM; Christopher; (Princeton, NJ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
PRINCETON UNIVERSITY |
Princeton |
NJ |
US |
|
|
Family ID: |
1000006344822 |
Appl. No.: |
17/747660 |
Filed: |
May 18, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16604623 |
Oct 11, 2019 |
11358876 |
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PCT/US2018/029961 |
Apr 27, 2018 |
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17747660 |
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62491321 |
Apr 28, 2017 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C01P 2004/51 20130101;
C01B 2203/0238 20130101; C01P 2002/70 20130101; B01J 23/83
20130101; C01G 45/1242 20130101; C01P 2004/62 20130101; C01F 7/16
20130101; C01P 2004/64 20130101; C01P 2004/04 20130101; C01P
2004/34 20130101; C01P 2004/03 20130101; C01P 2002/72 20130101;
C01P 2004/61 20130101; C01G 53/50 20130101; C01F 17/34 20200101;
C01B 13/34 20130101; C01F 17/218 20200101; C01P 2004/53 20130101;
B01J 23/002 20130101 |
International
Class: |
C01F 17/218 20060101
C01F017/218; B01J 23/83 20060101 B01J023/83; B01J 23/00 20060101
B01J023/00; C01F 7/16 20060101 C01F007/16; C01B 13/34 20060101
C01B013/34; C01G 45/12 20060101 C01G045/12; C01G 53/00 20060101
C01G053/00; C01F 17/34 20060101 C01F017/34 |
Goverment Interests
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] This invention was made with government support under Grant
No. CMMI-1449314 awarded by the National. Science Foundation. The
government has certain rights in the invention.
Claims
1. A material synthesis method, comprising: adding at least one
liquid precursor solution to an atomizer device; generating by the
atomizer device an aerosol comprising liquid droplets; transporting
the aerosol to a reactive zone for evaporating one or more solvents
from the aerosol; and collecting particles synthesized from at
least evaporating the aerosol.
2. The method according to claim 1, wherein: the at least one
liquid precursor solution comprises a metal salt dissolved or
diluted in a solvent; the metal salt comprises at least one of
alkaline, transition, or lanthanide metals; the solvent comprises
at least one of water, metal alkoxide, or one or more hydrocarbon
liquids; and the median size of the synthesized particles increases
with the molar concentration of the liquid precursor solution.
3. The method according to claim 1, wherein the at least one liquid
precursor solution has a dynamic viscosity of less than 0.2 Pas and
a molar concentration of 0.001-2 mol/L.
4. The method according to claim 1, wherein: for a sub-micron mode
of the atomizer device, at least 99% of the liquid droplets by
number have a diameter of less than 1 .mu.m and an arithmetic mean
diameter between 0.1 and 1 .mu.m, and the particles are
monodisperse with an average diameter between 5-100 nm; and for a
dual mode of the atomizer device, the liquid droplets are
sub-micron sized in diameter or 1-100 .mu.m in diameter, and the
particles are polydisperse with diameters between 5 nm-10
.mu.m.
5. The method according to claim 1, wherein: the atomizer device
comprises a microspray atomizer; generating the aerosol comprises
introducing an atomizing gas flow into the microspray atomizer and
generating the aerosol in the microspray atomizer; the atomizing
gas comprises at least one of an oxidizer gas, an inert gas, or a
fuel gas; and the atomizing gas flow has a pressure of 1-100
bar.
6. The method according to claim 1, wherein, before transporting
the aerosol to the reactive zone, the method further comprises:
transporting the aerosol to a preheating section; and preheating
the aerosol at a temperature between 50.degree. C. and 500.degree.
C. for evaporating at least a portion of the one or more solvents
from the aerosol for 0.1-10 seconds.
7. The method according to claim 6, wherein: energy for the
preheating is provided by at least one of electrical heating,
combustion heating, or heat exchange with a recirculated exhaust
gas.
8. The method according to claim 1, wherein: the reactive zone
comprises at least one of a flame, plasma, furnace, laser heating,
or electric heating; the reactive zone is at a temperature of
500-10000.degree. C. and a pressure of 500 mbar-10 bar; and
transporting the aerosol to the reactive zone for evaporating one
or more solvents from the aerosol comprises transporting the
aerosol to the reactive zone for evaporating one or more solvents
from the aerosol for 0.1-10 seconds.
9. The method according to claim 1, wherein: transporting the
aerosol to the reactive zone comprises transporting the aerosol to
the reactive zone without preheating; and the synthesized particles
are hollow-structured.
10. The method according to claim 1, further comprising: collecting
the synthesized particles comprises collecting the synthesized
particles from an exhaust stream of the reactive zone by membrane
filtering, electrostatic collection, bag filtering, or cold
trap.
11. The method according to claim 1, the synthesized particles
comprise a metal oxide, fluoride, sulphide, oxysulphide, silicate,
nitrate or nitride; and the synthesized particles comprise
non-aggregated particles.
12. The method according to claim 1, wherein the synthesized
particles comprise particles selected from a group consisting of:
monodisperse Li(Ni.sub.0.33Mn.sub.0.33Co.sub.0.33)O.sub.2 particles
with an average diameter between 5-100 nm, hollow-structured
Li(Ni.sub.0.33Mn.sub.0.33Co.sub.0.33)O.sub.2 particles, and
polydisperse Li(Ni.sub.0.33Mn.sub.0.33Co.sub.0.33)O.sub.2 particles
with diameters between 5 nm-10 .mu.m.
13. A material synthesis system, comprising: an atomizer device for
receiving at least one liquid precursor solution to generate an
aerosol comprising liquid droplets; an atomizer channel; and a
reactor, wherein: the atomizer channel is connected to the atomizer
device at a first end and to the reactor at a second end; the
atomizer channel is at least for transporting the aerosol to the
reactor; and the reactor comprises a reactive zone for evaporating
one or more solvents from the aerosol to obtain particles
synthesized from at least evaporating the aerosol.
14. The system according to claim 13, wherein: the at least one
liquid precursor solution comprises a metal salt dissolved or
diluted in a solvent; the metal salt comprises at least one of
alkaline, transition, or lanthanide metals; the solvent comprises
at least one of water, metal alkoxide, or one or more hydrocarbon
liquids; and the median size of the synthesized particles increases
with the molar concentration of the liquid precursor solution.
15. The system according to claim 13, wherein: for a sub-micron
mode of the atomizer device, at least 99% of the liquid droplets by
number have a diameter of less than 1 .mu.m and an arithmetic mean
diameter between 0.1 and 1 .mu.m, and the particles are
monodisperse with an average diameter between 5-100 nm; and for a
dual mode of the atomizer device, the liquid droplets are
sub-micron sized in diameter or 1-100 .mu.m in diameter, and the
particles are polydisperse with diameters between 5 nm-10
.mu.m.
16. The system according to claim 13, wherein: the atomizer channel
comprises a preheating section for preheating the aerosol at a
temperature between 50.degree. C. and 500.degree. C. for 0.1-10
seconds.
17. The system according to claim 13, wherein: the reactive zone
comprises at least one of a flame, plasma, furnace, laser heating,
or electric heating; the reactive zone is at a temperature of
500-10000.degree. C. and a pressure of 500 mbar-10 bar; and the
reactor comprises the reactive zone for evaporating the one or more
solvents from the aerosol for 0.1-10 seconds to obtain synthesized
particles.
18. A material synthesis method, comprising: adding a first
precursor solution to an atomizer device to generate a first
aerosol comprising first liquid droplets; transporting the first
aerosol to a reactive zone for evaporating one or more first
solvents from the first aerosol to obtain first synthesized
particles of a first size distribution; adding a second precursor
solution to the atomizer device to generate a second aerosol
comprising second liquid droplets; and transporting the second
aerosol to the reactive zone for evaporating one or more second
solvents from the second aerosol to obtain second synthesized
particles of a second size distribution.
19. The method according to claim 18, wherein: the first and second
precursor solutions comprise gasoline and water respectively.
20. The method according to claim 18, wherein: the first and second
size distributions are selected from monodisperse and polydisperse
distributions; the monodisperse distribution is associated with an
average diameter between 5-100 nm, and is obtained from
corresponding liquid droplets that at least 99% by number of which
have a diameter of less than 1 .mu.m or an arithmetic mean diameter
between 0.1 and 1 .mu.m; and the polydisperse distribution is
associated with diameters between 5 nm-10 .mu.m, and is obtained
from corresponding liquid droplets that are sub-micron in diameter
or 1-100 .mu.m in diameter.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application is based on and claims priority to
the U.S. Provisional Application No. 62/491,321, titled "Method for
high temperature synthesis of functional nanoparticles using
sub-micron aerosol droplets" filed on Apr. 28, 2017, the entire
contents of which are incorporated herein by reference.
TECHNICAL FIELD
[0003] The present invention relates to the field of material
science and engineering, and in particular, to high-temperature
synthesis of functional nanoparticles and thin films based on
aerosol droplets.
BACKGROUND
[0004] Nanostructured materials like nanoparticles and thin films
have significant impacts in energy-related and various other
applications for their unique properties. Existing methods for
producing materials in such applications have various
disadvantages. For instance, solid state reactions can be used to
produce metal oxide or lithium orthosilicate particles for
thermochemical energy storage, but the particle size and shape are
difficult to control and subsequent milling/washing steps are
required. Wet chemical (co-precipitation) methods can be used to
produce battery cathode materials but the processing time is very
long (24 hours) and large volumes of toxic waste are produced.
Usually the size distribution of the synthesized particles is
broad, so separation/sieving (such as by air jet siever) is
required, which reduces the product yield. Furthermore, the
particle size of particles produced under the current methods is
generally several microns or more, which is unlikely to meet the
requirement for smaller particles in battery electrode and
catalytic applications greatly. Lastly, some aerosol techniques
such as spray drying or spray flames use either highly dilute
precursor solutions or expensive organometallic precursors to
achieve particle size control, which poses as a significant hurdle
for mass production. Other conventional atomization technologies
require high atomization energy and have poor prospects for
industrial scale-up due to their high production costs.
SUMMARY
[0005] Systems and methods for synthesizing various materials
(e.g., electrochemically, thermochemically, or opto-electronically
active materials) are disclosed. Such materials can be used for
energy conversion and storage.
[0006] According to one aspect of the present disclosure, a
material synthesis method may comprise: adding at least one liquid
precursor solution to an atomizer device; generating by the
atomizer device an aerosol comprising liquid droplets; transporting
the aerosol to a reactive zone for evaporating one or more solvents
from the aerosol; and collecting synthesized particles.
[0007] According to another aspect, a material synthesis system may
comprise: an atomizer device for receiving at least one liquid
precursor solution to generate an aerosol comprising liquid
droplets; an atomizer channel; and a reactor. The atomizer channel
is connected to the atomizer device at a first end and to the
reactor at a second end. The atomizer channel is at least for
transporting the aerosol to the reactor. The reactor comprises a
reactive zone for evaporating one or more solvents from the aerosol
to obtain synthesized particles.
[0008] According to another aspect of the present disclosure, a
material synthesis method may comprise adding a first precursor
solution to an atomizer device to generate a first aerosol
comprising first liquid droplets, transporting the first aerosol to
a reactive zone for evaporating one or more first solvents from the
first aerosol to obtain first synthesized particles of a first size
distribution, adding a second precursor solution to the atomizer
device to generate a second aerosol comprising second liquid
droplets, and transporting the second aerosol to the reactive zone
for evaporating one or more second solvents from the second aerosol
to obtain second synthesized particles of a second size
distribution.
[0009] These and other features of the systems and methods
disclosed herein, as well as the methods of operation and functions
of the related elements of structure and the combination of parts
and economies of manufacture, will become more apparent upon
consideration of the following description and the appended claims
with reference to the accompanying drawings, all of which form a
part of this specification, wherein like reference numerals
designate corresponding parts in the various figures. It is to be
expressly understood, however, that the drawings are for purposes
of illustration and description only and are not intended as a
definition of the limits of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Certain features of various embodiments of the present
technology are set forth with particularity in the appended claims.
A better understanding of the features and advantages of the
technology will be obtained by reference to the following detailed
description that sets forth illustrative embodiments, in which the
principles of the invention are utilized, and the accompanying
drawings of which:
[0011] FIG. 1 is a flowchart illustrating an exemplary material
synthesis method, consistent with various embodiments of the
present disclosure.
[0012] FIG. 2 is a graphical illustration of the exemplary material
synthesis method, consistent with various embodiments of the
present disclosure.
[0013] FIG. 3A is graphical illustration of an atomizer device,
consistent with various embodiments of the present disclosure.
[0014] FIG. 3B is graphical illustration of aerosol generation
using the atomizer, consistent with various embodiments of the
present disclosure.
[0015] FIG. 4A and FIG. 4B are respectively graphical illustrations
of volume-based and number-based droplet size distribution for a
hydrocarbon-liquid-fuel-based precursor solution in the sub-micron
mode, consistent with various embodiments of the present
disclosure.
[0016] FIG. 4C and FIG. 4D are respectively graphical illustrations
of volume-based and number-based droplet size distribution for a
water-based precursor solution for the dual-mode, consistent with
various embodiments of the present disclosure.
[0017] FIG. 5 is a scanning electron microscope (SEM) image of
polydisperse Li(Ni.sub.0.33Mn.sub.0.33Co.sub.0.33)O.sub.2 particles
synthesized from the dual-mode aerosol, consistent with various
embodiments of the present disclosure.
[0018] FIG. 6A is an SEM image of synthesized LiMn.sub.2O.sub.4
battery cathode material, consistent with various embodiments of
the present disclosure.
[0019] FIG. 6B is an SEM image of synthesized Y.sub.2O.sub.3
deposited onto an aluminum foil, consistent with various
embodiments of the present disclosure.
[0020] FIG. 7 is a transmission electron microscope (TEM) image of
synthesized hollow metal oxide Y.sub.2O.sub.3 particles, consistent
with various embodiments of the present disclosure.
[0021] FIG. 8A and FIG. 8B are SEM images of synthesized metal
oxide Y.sub.2O.sub.3 particles, consistent with various embodiments
of the present disclosure.
[0022] FIG. 9A is an SEM image of
Li(Ni.sub.0.33Mn.sub.0.33Co.sub.0.33)O.sub.2 Li-ion battery
materials synthesized with the disclosed method, consistent with
various embodiments of the present disclosure,
[0023] FIG. 9B is a graphical illustration of number-based particle
size distribution of the material shown in FIG. 9A, consistent with
various embodiments of the present disclosure.
[0024] FIG. 9C is an SEM image of
Li(Ni.sub.0.33Mn.sub.0.33Co.sub.0.33)O.sub.2 Li-ion battery
materials synthesized with a conventional (ultrasonic) atomization
method.
[0025] FIG. 9D is a graphical illustration of number-based particle
size distribution of the material shown in FIG. 9C.
[0026] FIG. 10 is a graphical illustration of particle size
distribution of produced metal oxide particles, consistent with
various embodiments of the present disclosure.
[0027] FIG. 11 is an X-ray diffraction pattern of annealed lithium
NMC (lithium nickel manganese cobalt oxide) powders, consistent
with various embodiments of the present disclosure.
[0028] FIG. 12 is a flowchart illustrating an exemplary material
synthesis method, consistent with various embodiments of the
present disclosure.
[0029] FIG. 13 is a flowchart illustrating an exemplary material
synthesis method, consistent with various embodiments of the
present disclosure.
DETAILED DESCRIPTION
[0030] As described in the background, current methods for
synthesizing small structures (e.g., nanoparticles, microparticles,
thin films) are inadequate to meet the application requirements. To
mitigate or overcome such disadvantages in existing technologies,
various material synthesis systems and methods are disclosed.
[0031] In various embodiments, a continuous high-temperature
synthesis method is disclosed. This method can be used for the
production of size and morphology controlled nanomaterials. The
method implements both aerosol droplets produced by an atomizer
device and morphology control steps to produce a scalable hierarchy
of nanostructured materials. For example, monodispersed or
near-monodisperse ultrafine (a narrow distribution in the 5-100 nm
size range, e.g., 5-10 nm, 50-60 nm, 5-20 nm, 10-30 nm, 30-50 nm,
60-80 nm, 80-100 nm) nanoparticles, polydisperse and non-aggregated
particles (a broad distribution in the 5 nm-10 .mu.m size range,
e.g., 5-10 nm nanoparticles and 1-10 .mu.m particles, or a
continuous distribution in the 100 nm-10 .mu.m size range, or
combinations thereof), and hollow-structured particles can be
synthesized through the control of aerosol droplet size,
preheating, and synthesis temperature. Using economically viable
precursors, the produced material can have a targeted crystalline
phase and element composition. Metal oxide, sulphide, nitride,
chloride, fluoride, and carbonate nanoparticles as well as thin
films (e.g., 5 nm-100 .mu.m thick) can be produced based on the
disclosed methods.
[0032] In some exemplary applications, cathode, electrolyte, and
anode nanomaterials for electrochemical energy storage may be
synthesized and used in lithium-ion batteries, sodium batteries,
and solid state batteries. Other applications for the produced
materials may include metal catalysts for chemical conversion of
fuels, photo-active materials for optoelectronic applications
(e.g., solar cells), imaging materials (e.g., scintillators, remote
sensors), thermal chemical materials used in thermochemical energy
storage for solar thermal power generation, thermal power plants,
electrolyte materials for solid-oxide fuel cells, and
functionalized surface coatings (e.g., thin films). Other
applications may include materials of cosmetics, paints, inks, and
nanocomposites (e.g., thin multilayer films), ultra-hard materials,
communication materials (e.g., optical fiber materials, rare-earth
doped materials), displays and lighting, lasers, security and
labelling, counterfeiting, medical diagnosis and treatment
materials (e.g., photodynamic materials, pharmaceuticals), and
remote optical sensor materials.
[0033] In some embodiments, various features are disclosed for
achieving synthesis product particle size and morphology control:
(i) control of the droplet size distribution, where an atomizer
device operates in a sub-micron mode, and the majority of droplets
by number are 100-1000 nm in diameter, or the atomizer device
operates in a dual mode, and the aerosol comprises both sub-micron
droplets and larger droplets in the size range 1-100 .mu.m,
allowing synthesis of monodispersed ultrafine (e.g., 5-100 nm) or
polydisperse (e.g., 5 nm-10 .mu.m) nanomaterials respectively; (ii)
a preheating section to control the particle size and morphology,
respectively, for the production of monodispersed ultrafine
particles (e.g., 5-100 nm) via a gas-to-particle synthesis process,
or hollow-structured particles via a shell formation process; (iii)
the synthesis temperature can be varied to produce either
monodispersed ultrafine nanoparticles (e.g., 5-100 nm) or larger
polydisperse particles (e.g., 5 nm-10 .mu.m). Furthermore,
regarding the material nanostructure, (iv) the applications of the
atomizer device as well as the preheating and synthesis temperature
control in this process can enable formation of polydisperse (e.g.,
5 nm-10 .mu.m) and monodisperse ultrafine nanoparticles (e.g.,
5-100 nm); and (v) hollow-structured particles can be formed using
the appropriate combination of preheating and synthesis
temperature.
[0034] FIG. 1 is a flowchart illustrating an exemplary material
synthesis method, consistent with various embodiments of the
present disclosure. The disclosed exemplary material synthesis
method may comprise continuous high-temperature synthesis steps for
producing size and morphology controlled materials. The produced
materials (e.g., nanomaterials) may be used for energy conversion,
energy storage, imaging, catalysts, and functionalized surface
coatings (thin films). As shown in FIG. 1, the exemplary material
synthesis method may comprise steps 101-107. In FIG. 1, exemplary
product particle properties controlled at each step are provided to
the left of the each step, and exemplary additional process
variables are provided to the right of the each step. The
operations of the exemplary material synthesis method and its
various steps presented herein are intended to be illustrative.
Depending on the implementation, the exemplary material synthesis
method may include additional, fewer, or alternative steps
performed in various orders or in parallel.
[0035] Referring to FIG. 1, in some embodiments, the material
synthesis method comprises: (step 101) preparing liquid precursor
solutions containing desired metal elements and mixing the
precursor solutions; (step 102) generating an aerosol using an
atomizer device; (step 103) in a continuous process, preheating the
aerosol (e.g., in a preheating section between 50-500.degree. C.,
such as, 50-200.degree. C., 100-200.degree. C., 200-300.degree. C.,
300-400.degree. C., 400-500.degree. C., etc.) for 0.1-10 seconds
(e.g., 0.5-5 seconds, 5-10 seconds, etc.), which allows control of
the particle morphology such as formation of hollow-structured
particles); (step 104) transporting the aerosol into a
high-temperature reactive zone (e.g., the reactive zone may be at
500-10000.degree. C., such as, 500-1300.degree. C. for electrical
heating, 800-3000.degree. C. for flame heating, 1000-10000.degree.
C. for plasma heating, 3000-5000.degree. C., 5000-10000.degree. C.,
etc.) and 500 mbar-10 bar pressure (e.g., atmospheric pressure or a
pressure of 1-5 bar, 5-10 bar, etc.) in which the aerosol may stay
for a period of time (e.g., 0.1-10 seconds), the reactive zone
facilitates the production of metal oxide, sulphide, nitride,
chloride, fluoride, carbonate, and other materials), and the
temperature may be controlled to produce ultrafine nanoparticles
(e.g., 5-100 nm size) or larger particles (e.g., 5 nm-10 .mu.m
size); and (step 105) collecting the product particles (e.g., from
an exhaust stream, depositing the product particles directly on a
substrate to generate thin films). Optionally, at (step 106),
additional processing (e.g., annealing) may be implemented to
improve the particle crystalline structure. The synthesized
material can be obtained at (step 107).
[0036] FIG. 1 can be related to FIG. 2, which provides graphical
illustrations of the exemplary material synthesis method,
consistent with various embodiments of the present disclosure. FIG.
2 shows a general schematic diagram of the synthesis method. From
left to right, FIG. 2 illustrates main components of the apparatus
for synthesis, description of governing processes, and the aerosol
droplet modes, preheating control, and product particle size
distributions at certain steps. Referring to FIG. 2, a material
synthesis system may comprise: an atomizer device for receiving at
least one liquid precursor solution to generate an aerosol
comprising liquid droplets; an atomizer channel; and a reactor.
When the atomizer device is implemented as a microspray atomizer,
to generate the aerosol, the atomizer device may be configured to
receive the at least one liquid precursor solution and an atomizing
gas flow. The atomizer device receives the atomizing gas, which may
flow from a submerged portion of the liquid precursor solution. The
atomizing gas may comprise at least one of an oxidizer gas, an
inert gas, or a fuel gas. The atomizing gas flow may have a
pressure of 1-100 bar (e.g., 1-10 bar, 10-50 bar, 50-100 bar,
etc.). The atomizer channel (e.g., tube, pipe, or an alternative
structure) is connected to the atomizer device at a first end and
to the reactor at a second end. The atomizer channel is at least
for transporting the aerosol from the atomizer device to the
reactor. The atomizer channel may comprise an optional preheating
section for preheating the aerosol at a temperature between
50.degree. C. and 500.degree. C. for 0.1-10 seconds. For example,
when no heating is provided to the aerosol between the atomizing
device and the reactor, the synthesized particles may be
hollow-structured. The reactor comprises a reactive zone for
evaporating one or more solvents from the aerosol at a temperature
of 500-10000.degree. C. and a pressure of 500 mbar-10 bar for
0.1-10 seconds to obtain synthesized particles. the reactive zone
may comprise at least one of a flame, plasma, furnace, laser
heating, or electric heating; Each step is described in more
details below. Further details of the material synthesis steps can
be referred to in both FIG. 1 and FIG. 2.
[0037] (Step 101) precursor solution preparation and mixing. In
some embodiments, the metal precursors for the product particles
(e.g., oxides, silicates, oxysulphides, sulphides, fluorides,
nitrides) are initially in the liquid phase or prepared
accordingly. Depending on the material to be formed, salts of the
metals that shall form the product particles are chosen. For
example, precursor solutions used for the material synthesis method
may comprise metal salt(s) (e.g., nitrate, acetate, carbonate,
chloride, sulphide, hydroxide) dissolved in a solvent liquid. The
metal in the metal salt(s) may comprise any alkaline, transition,
or lanthanide (rare-earth) metal(s) or metalloids. For example,
these metal salts may comprise nitrates
(M(NO.sub.3).sub.x.yH.sub.2O), chlorides (MCl.sub.x), acetates
M(O.sub.2C.sub.2H.sub.3).sub.x.yH.sub.2O), etc.
[0038] In some embodiments, to prepare the precursor solutions, the
metal salts are weighed to the correct atomic stoichiometry as
desired in the product particles. The salts (solute) are then
dissolved in a liquid (solvent). The solvent liquid may comprise
water, that is, the solvent does not need to be a fuel that
participates in the chemical reaction by releasing heat. In other
realizations of the material synthesis method the solvent may be a
source of additional heat generation. For example, the solvent may
comprise ethanol, butanol, isopropanol, ethylene glycol, acetic
acid, or other liquid hydrocarbon fuel and combinations of these.
Alternatively, the precursor solution may comprise a metal alkoxide
(e.g., titanium isopropoxide, tetraethyl orthosilicate) and may be
diluted with ethanol. Where the material to be synthesized is a
fluoride, ammonium fluoride may be used as a precursor. Where the
material to be synthesized is a sulphide or oxysulphide, sulphur
chloride may be used as a precursor.
[0039] The elemental ratio of the metals in the precursor solution
controls the composition of the product particles. In some
embodiments, the molar concentration of the precursor liquid may be
between 0.001-2 mol/L (e.g., in the range of 0.1-2 mol/L, 0.001-1
mol/L, 0.1-1 mol/L, 1-2 mol/L, etc.), allowing additional control
of the product particle size. In the droplet to particle formation
mode described below, higher precursor concentrations will result
in larger particles being produced.
[0040] (Step 102) aerosol generation by atomization. In some
embodiments, the prepared precursor solution is atomized, for
example, in an atomizer device. For example, the liquid precursor
solution is contained in a chamber of the atomizer device (e.g.,
microspray atomizer, ultrasonic nebulizer for producing
micron-sized droplets, pressure nozzle such as a diesel injector,
etc.). For the descriptions below including FIG. 3A and FIG. 3B,
the atomizer device is implemented as a microspray atomizer. A
regulated atomizing gas flow (e.g., air, nitrogen, argon, or any
tailored fuel or oxidizer mixture) is introduced into the atomizer
device. The choice of atomizing gas may depend on the downstream
high-temperature process of the material synthesis method. The
pressure of the atomizing gas may be between 1-100 bar. The
atomizing gas may comprise at least one of an oxidizer gas (oxygen
or any oxygen-containing mixture, such as air), an inert gas (e.g.,
argon, nitrogen), or a fuel gas (e.g., hydrogen, or one or more
carbon-containing gases such as methane, ethylene, propane, and
other alkanes and oxygenated fuels like alcohols and ethers).
[0041] FIG. 3A is graphical illustration of an atomizer device 300,
consistent with various embodiments of the present disclosure. The
components of the exemplary atomizer device 300 presented herein
are intended to be illustrative. Depending on the implementation,
the atomizer device 300 may include additional, fewer, or
alternative components.
[0042] In some embodiments, the atomizer device 300 may comprise a
vessel 1, a tube 2, an optional air filter 3, and an air pressure
regulator 4. When incorporated in the material synthesis system of
FIG. 2, the opening 5 directly connects to the atomizer channel as
shown in FIG. 2. The opening 5 may have any shape or type of
connection without limitation by the illustration. The atomizer
device 300 may comprise another opening for receiving the precursor
solution labeled as "fluid" in FIG. 3A. The "air" shown in FIG. 3A
may correspond to the atomizing gas described herein.
[0043] In some embodiments, in the vessel 1, the tube 2 (e.g.,
norprene tubing in a circular or other configurations), is placed
to the liquid. The tube may be floating on the liquid surface and
connected to the pressurized air provided with the filter 3 and the
pressure regulator 4. The air flow rate may be between 1-10000
l/min or higher, or in the range 1-10 l/min, 10-100 l/min, etc. The
tube 2 may be perforated with a needle having a diameter of about
0.6 mm (or alternatively at another suitable value), and
approximately the same number of orifices are above and below the
liquid surface (liquid/air interface). The number of orifices may
be between 10 and 32 per cm, the tube may be between 1.5 and 30 cm,
and the tube outer diameter may be 11 or 12 mm and inner diameter
between 6 and 8.4 mm. The droplets formed in the vessel 1 rise to
an exit at the opening 5. The aerosol formation can be affected by
the process parameters. For example, higher diameter of the
perforation needle provides larger droplets. Similarly, the thinner
is film which covers the emerged orifices, the smaller are the
formed droplets; the greater is the air pressure, the smaller are
the droplets.
[0044] In some embodiments, inside the atomizer, compressed air may
be released through a submerged lower part of a container
containing the solution, forming ensembles of small bubbles. The
bubbles come to the surface of the precursor liquid, forming
created ensembles of thin spherical liquid films (e.g., with an
estimated thickness of less than 500 nm). Simultaneously, high
velocity gas jets cause the disintegration of the liquid films,
forming an aerosol, which comprises precursor solution droplets
suspended in the atomizing gas flow. Further details are described
below with reference to FIG. 3B.
[0045] FIG. 3B is graphical illustration of aerosol generation
using the atomizer, consistent with various embodiments of the
present disclosure. FIG. 3B shows a cross-sectional view of the
tube 2 described with reference to FIG. 3A, and the tube 2 is
provided with orifices 302 (e.g., orifices 302a-302e) perforated in
the walls 301 of the tube 2. The bottom portion of tube 2 is
immersed in a liquid 303, and the upper portion of tube 301 is
exposed to the environment. The material from which the tube 2 is
produced can be of any kind that is suitable to be immersed in the
liquid and can have some degree of elasticity.
[0046] In some embodiments, compressed gas (e.g., the atomizing gas
described herein) is inserted into tube 301. When the compressed
gas is in contact with orifices 302, the pressure difference
between the compressed gas and the outer environment tend to
equalize, and the compressed gas is discharged through orifices 302
by a velocity increasing with said pressure difference. The
material of tube 2 (hollow body) can possess some degree of
elasticity to intensify and regulate the compressed gas discharge
through the orifices, to prevent liquid backflow through the
orifices and also to avert clogging of the orifices when atomizing
suspensions and liquids of high viscosity. For tube 2 made of
elastic material, such as norprene rubber, the size of orifices
perforated in the tube walls and the gas flow rate depend on the
pressure of the supplied compressed gas: the higher the gas
pressure, the greater will be the size of the orifices and vice
versa. Moreover, because of the pressure difference between the
inner and outer sides of the tube 2, the internal parts of elastic
orifices 302 that are in contact with the compressed gas may have
larger sizes than their outer parts that are in contact either with
liquid 303 or with the environment. Therefore, the elastic orifices
may have shapes close to truncated cones (e.g., with a broad end
facing the inside of the tube 2 and a narrow end facing the outside
of the tube 2) and may act as nozzles, accelerating the flow of the
discharging compressed gas and thereby intensifying the atomization
process. In addition, the elasticity of tube 2 allows orifices 302
to function as check valves, preventing backflow from liquid and
environment when the compressed gas is not supplied: due to elastic
expansion of the tube material, orifices perforated in the tube
walls by micron needle may have zero size (will be closed) if there
is no excess pressure of the compressed gas inside tube 2. In case
of clogging of the orifices during the operation, the elasticity of
tube 2 will have advantages because it may allow enlarging the
orifice sizes by supplying higher than operating pressure of the
compressed gas and thus facilitating through-scavenging of the
clogs.
[0047] When the compressed gas is released through the orifices
302d and 302e that are immersed in the liquid, it creates bubbles
304 that climb up and meet compressed gas released from the
orifices 302a, 302b, and 302c that are not immersed in the liquid.
The thin-walled bubbles 304 are broken by the gas jets released
from orifices 302a, 302b, and 302c into drops of very small size
droplets 305, which are pushed away from the tube, providing a
spray of the atomized liquid.
[0048] There are two sets of orifices perforated in tube walls:
orifices 302 a-c that are located at the upper portion of tube 2
and are exposed to the environment, and orifices 302 d-e that are
located at the lower immersed portion of tube 2, exposed to the
liquid material. The number of orifices in each set (lower or
immersed set, and upper or emerged set) and the diameters of the
orifices of each set may be adapted to discharge desired flow rates
of the compressed gas through said upper and lower sets and the
skilled person will easily devise orifice configurations suitable
for a specific need. The tube can be straight or bent in various
spatial configurations, so that said longitudinal axis may have the
shape of, e.g., circle, ellipse, coil etc. Along the tube, some
sections may be entirely immersed or entirely emerged, but at least
some sections must be partially immersed, having the longitudinal
axis located in a plane parallel or identical to the interface
between the liquid and the atmosphere. Alternatively, the atomizer
device can be of various other shapes and configurations, as long
as it comprises a tube that contains a flow of compressed gas, is
partially immersed in a liquid material, and has orifices
perforated in its walls as described.
[0049] Further information of the atomizer can be found from the
following publications, which are incorporated herein by reference
in their entirety: (1) Mezhericher, M., Ladizhensky, I. and Etlin,
I. Atomization of liquids by disintegrating thin liquid films using
gas jets. International Journal of Multiphase Flow 2017, 88:
99-115; (2) Mezhericher M., Ladizhensky I. and Etlin I. U.S. patent
application Ser. No. 15/324,902, filed Jan. 9, 2017; (3)
Mezhericher M., Ladizhensky I. and Etlin I. Liquid-atomization
Method and Device. European Patent Application No. 15848995.5,
filed Feb. 23, 2017; (4) Mezhericher M., Ladizhensky I. and Etlin
I. Liquid-atomization Method and Device. PCT/IL2015/050857;
Publication No. WO2016/055993, published on Apr. 14, 2016; and (5)
Mezhericher M., Ladizhensky I. and Etlin I. Liquid-Atomization
Method and Device. Israel Patent Application, No. 235083, filed
Oct. 7, 2014.
[0050] Referring back to FIG. 1 and FIG. 2, in some embodiments,
the atomizer device may employ a sub-micron droplet mode (e.g.,
droplets of a diameter of 100-1000 nm are obtained), or use a dual
droplet size mode (e.g., sub-micron droplets and 1-100 .mu.m
droplets are obtained). The size distribution of the aerosol
droplets may be controlled via various conditions. For example, the
atomizing gas pressure or the properties of the liquid precursor
may be controlled to change the droplet size. In some cases, the
atomizer may be heated to adjust the properties of the precursor
liquid, thereby controlling the droplet size and to facilitate
efficient droplet generation. Alternatively, various other
atomization methods for obtaining different droplet size
distributions can be used, and combined together to produce
materials with specified size distributions.
[0051] (Step 103) Preheating control. The aerosol obtained from the
step 102 may be passed through a temperature controlled preheating
region for particle morphology control before delivery to the
high-temperature reactive zone downstream. The size distribution
from the step 102 (e.g., sub-micron or dual-mode described above),
coupled with the preheating temperature control in step 103 and
synthesis temperature control in step 104, can be used to control
the size distribution of the synthesized product particles, for
example, monodisperse ultrafine particles (e.g., 5-100 nm size), or
polydisperse particles (e.g., 5 nm-10 .mu.m size).
[0052] In some embodiments, the aerosol flow can be preheated in a
delivery line before feeding into a reactor, to facilitate control
of the synthesized particle morphology. The preheating energy may
be provided by electrical heating, combustion heating, or heat
exchange with recirculated high-temperature exhaust gas described
herein. In one example, the preheating temperatures can be between
50.degree. C. and 500.degree. C. to suppress or eliminate the
formation of (1) hollow particles, or (2) sub-10 nm nanoparticles
formed from the gas-phase-to-particle mode, by slowing the
evaporation rate of solvent from the droplet (e.g., as compared to
directly feeding into the reactor) and therefore providing time for
the solute to diffuse within the droplets. A residence time in the
preheating section may be 0.1-10 seconds.
[0053] (Step 104) reactor reaction. The aerosol from the step 103
is delivered to a reactive zone, where the solvent liquid
evaporates and reacts in the high-temperature reactor to form
product particles. A reactor or an alternative apparatus may
provide the high-temperature reactive zone. Chemical conversion of
the precursor into product particles occurs inside the reactor. The
high-temperature may be achieved with a flame, a heated volume, a
plasma, laser heating, electric heating, or their combination with
or without additional gaseous precursors. Active flame, plasma
radicals, or other energy sources can accelerate the production of
homogeneous particles. The aerosol may pass directly through the
reactive zone, or high-temperature gas(es) may be generated (e.g.,
by the flame or another energy source) and mixed with the aerosol
stream to burn in the reactive zone (e.g., methane can be added to
the aerosol stream and the mixture can be burnt with oxygen in a
non-premixed co-flow burner configuration).
[0054] In some embodiments, the reaction temperature in the reactor
may be 500-10000.degree. C., the pressure of the reactor may be 500
mbar-10 bar, and the residence time in the reactor may be 0.1-10
seconds. The high-temperature reactive zone may be formed by the
burning of fuel and oxidizer. The fuel may contain carbon (e.g.,
methane, ethylene, propane and other alkanes and oxygenated fuels
like alcohols and ethers). Alternatively, the fuel may comprise
hydrogen (e.g., for high purity applications). The oxidizer stream
may comprise air or a tailored oxygen/inert gas mixtures. The
reactive zone may be surrounded by a co-flow of inert or oxidizing
gases. The flowrates of the gases may be controlled using any
ordinary method of flow regulation.
[0055] In some embodiments, the flame provides heat that evaporates
the solvent and drives the reaction of the precursors into product
particles. The flame also provides active radicals that accelerate
the formation of crystalline product particles. The combination of
flame structure, reactor residence time, fuel-oxidizer mixture, and
precursor solvent controls the synthesis conditions, thereby
controlling the crystallinity (e.g., crystal phase, crystallite
size), hollowness, core-shell, or dense particles.
[0056] In some embodiments, the high-temperature reactive zone may
be formed using a plasma discharge. In this case, the aerosol
stream is introduced into the reaction chamber together with
additional gases required for the formation of the product
particles. The additional gases may comprise air, nitrogen, helium,
argon, ammonia, or fluorine-containing gases. Electrical energy is
imparted to the aerosol flow. For example, the reactor may comprise
two electrodes with a voltage applied to them to generate a
discharge, thereby forming the plasma. The discharge raises the gas
temperature to evaporate the solvent. Active species in the plasma
may assist in driving the chemical reactions, which form the
product particles. In this case, the nature of the plasma discharge
and flow residence time controls the morphology and the
crystallinity of the product particles.
[0057] In some embodiments, the high-temperature reactive zone is
formed by an electrically-heated reactor, for example, in a tubular
furnace configuration. The reactor provides heat to the aerosol
stream, evaporating the droplets and forming the product particles.
The reactor temperature and residence time control crystallinity,
microstructure, and morphology of the product particles.
[0058] Regardless of the reactor configuration, the material
synthesis method comprises two primary routes for forming the
product particles: droplet-to-particle (one particle forms from
each droplet) and gas-to-particle (multiple particles form from
each vaporized droplet) formation routes.
[0059] For the droplet-to-particle route, the solvent evaporates
more slowly, and one particle forms from each droplet. The product
particle size is between 10 nm and 10 .mu.m (e.g., in the range of
10-50 nm, 50-100 nm, 100 nm-500 nm, 500 nm-1 .mu.m, 1-10 .mu.m,
etc.), depending primarily on the atomizer device operation mode,
precursor concentration, and preheating and reactor synthesis
temperatures. For example, in the dual-mode, the synthesized
particles may be polydisperse (e.g., 5 nm-10 .mu.m). For another
example, higher precursor concentrations may result in formation of
larger particles. For another example, higher preheating
temperatures may lead to formation of dense, smaller particles. For
another example, lower synthesis temperatures may favor the
formation of particles via this droplet-to-particle route. Further,
it is possible to enhance the formation of hollow particles (shell
formation) by using a low preheating temperature or no preheating,
with intermediate downstream synthesis temperatures.
[0060] For the gas-to-particle route, the precursor is first
vaporized into the gas-phase, and then particles form via
nucleation and growth from the precursor vapor. In some
embodiments, high synthesis temperatures (e.g., .about.2500.degree.
C.) and/or highly energetic plasma discharges (e.g.,
.about.10000.degree. C.) may drive the gas-to-particle synthesis
route to form ultrafine nanoparticles (5-100 nm) from the gas
phase. This formation route may depend on the atomizer device
operation mode, and preheating and reactor synthesis temperatures.
For example, in the sub-micron atomizer operation mode, the
particles may be predominantly ultrafine (5-100 nm). For another
example, in the sub-micron atomizer operation mode, the high
surface area of the droplets enhances the formation of ultrafine
nanoparticles (5-100 nm) from the gas phase. For another example,
preheating suppresses the gas-to-particle formation route by at
least reducing the droplet vaporization rate. For another example,
high synthesis temperatures favor the gas-to-particle formation
route. Further, the reactor pressure may be atmospheric or the
reactor pressure may be varied to adjust the particle morphology.
Low reactor pressures may promote the formation of ultrafine
nanoparticles (5-100 nm) via the gas-to-particle synthesis route
due to higher vaporization rate at lower pressures.
[0061] (Step 105) particle collection. Through the variation of
preheating and synthesis temperature following the
gas-phase-to-particle mode, droplet-to-particle mode, and
shell-to-hollow-particle mode, the morphology of nanoparticles such
as monodispersed ultra-fine particles (5-100 nm), hollow particles,
and polydisperse larger particles (5 nm-10 .mu.m) can be
controlled. The product particles may be collected from the process
exhaust stream or directly deposited on a surface (thin films). The
material synthesis system may comprise at least one of a membrane
filter, electrostatic collector, a bag filter, a cold trap, or a
substrate for collecting the synthesized particles from an exhaust
stream of the reactor. For example, the particles may be collected
from the exhaust stream using membrane filters, electrostatic
collection, bag filters, cold trap, or any other suitable method.
For another example, the nanoparticles can be deposited directly
onto a substrate to form nanostructured thin films.
[0062] (Step 106) additional processing. Additional processing
(e.g., annealing) may be implemented to improve the particle
crystalline structure. The annealing temperature and duration can
be configured to control the crystal phase and crystallite size.
The synthesized material can be obtained at (step 107).
[0063] FIG. 4A to FIG. 11 illustrate controlling the synthesis of
metal oxide nanoparticles and lithium-containing transition metal
oxide particles (e.g., Li(Ni.sub.0.33Mn.sub.0.33Co.sub.0.33)O.sub.2
for lithium-ion battery cathodes) with three different particle
morphologies (monodispersed ultra-fine particles (5-100 nm), hollow
particles, and polydisperse larger particles (5 nm-10 .mu.m)).
[0064] In some embodiments, nitrates of lithium metal and nitrates
of the transition metals nickel, manganese, and cobalt are
dissolved in deionized water. The elemental ratios of the
transition metals may be arbitrarily chosen. In one example, the
atomic ratio of transition metals is 1:1:1, with the ratio of total
transition metals to lithium 1:1, to form the electrochemically
active cathode material
Li(Ni.sub.0.33Mn.sub.0.33Co.sub.0.33)O.sub.2. The total molar
concentration of precursor salts in the mixture is 1 mol/L. In
another example, the ratio of lithium to a single transition metal
may be 1:2 to form the electrochemically active material
LiMn.sub.2O.sub.4. In another example, a single metal precursor may
be used, to form the metal oxide product M.sub.2O.sub.3, where M is
a metal (e.g., yttrium, Y). For example, Y.sub.2O.sub.3 particles
can be formed (where yttrium nitrate is dissolved in deionized
water forming precursor liquid, which is supplied into the chamber
of the atomization device).
[0065] In some embodiments, the prepared precursor solution is
added to the atomizer described above. An atomizing gas comprising
air is delivered to the atomizer at a pressure of approximately 2
bar(g). An aerosol of precursor solution droplets is generated in
the atomizer, according to the process described above.
[0066] The precursor solution droplets may have a volume-based
(mass-based) size distribution as shown in FIG. 4A-FIG. 4D. FIG. 4A
and FIG. 4B are respectively graphical illustrations of
volume-based and number-based droplet size distribution for a
hydrocarbon-liquid-fuel-based precursor solution in the sub-micron
mode, consistent with various embodiments of the present
disclosure. In FIG. 4A and FIG. 4B, the droplets obtained from the
corresponding liquid precursor are 95 RON (Research Octane Number)
gasoline fuel droplets, with a viscosity of 0.46 mPa-s, a surface
tension of 17 mN/m, and a density of 734 kg/m.sup.3. As shown in
FIG. 4A, in the sub-micron aerosol mode, the droplet mass is evenly
distributed between the sub-micron range and the 1-100 .mu.m range.
There exists a cubic relationship between the diameter and volume
of spherical droplets. For example, 1000 droplets with a diameter
of 100 nm have the same total volume as a single droplet with a
diameter of 1 .mu.m. Therefore, the right peak in FIG. 4A may
correspond to very few micron-size droplets in FIG. 4B, and as
shown in FIG. 4B, the vast majority (e.g., more than 99% by number)
of droplets are in the sub-micron range (e.g., 100-1000 nm size).
This sub-micron distribution is more suitable for producing
monodisperse particles in the synthesis process.
[0067] FIG. 4C and FIG. 4D are respectively graphical illustrations
of volume-based and number-based droplet size distribution for a
water-based precursor solution for the dual-mode, consistent with
various embodiments of the present disclosure. In FIG. 4C and FIG.
4D, the droplets obtained from the corresponding liquid precursor
are deionized water droplets, with a viscosity of 0.89 mPa-s, a
surface tension of 72.8 mN/m, and a density of 998 kg/m.sup.3. As
shown in FIG. 4C, in the dual mode, the mass is weighted toward the
1-100 .mu.m droplet size range. As shown in FIG. 4D, by numbers,
the atomizer produces droplets of a broader size distribution than
the sub-micron mode, and the aerosol comprises both sub-micron and
larger droplets 1-100 .mu.m, which correspond to the "dual modes."
This dual-mode distribution is more suitable for producing
polydisperse particles in the synthesis process.
[0068] In some embodiments, the aerosol can be delivered through a
preheating section with an exit temperature of, for example,
50-500.degree. C. For example, the preheating may be delivered by
electrical resistance heaters. The aerosol may be delivered to the
reactive zone. The reactive zone may comprise a diffusion flame
burner operated with gases containing, for example, methane,
oxygen, and nitrogen. An air co-flow surrounds the burner. The
entire reactive zone may be enclosed and operated at atmospheric
pressure. The aerosol flow is injected into the burner. The
adiabatic temperature of the mixed gases is between
700-2500.degree. C. The residence time of the aerosol in the
reactor is 0.1-10 seconds (e.g., 0.5-5 seconds). The product
particles may be collected from an exhaust stream using a filter
assisted with a vacuum pump, or using an electrostatic
precipitator. The particles may also be directly deposited onto a
substrate for the formation of thin films.
[0069] FIG. 5 is a scanning electron microscope (SEM)image of
polydisperse Li(Ni.sub.0.33Mn.sub.0.33Co.sub.0.33)O.sub.2 particles
synthesized from the dual-mode aerosol, consistent with various
embodiments of the present disclosure. According to the
above-described material synthesis method, the polydisperse
Li(Ni.sub.0.33Mn.sub.0.33Co.sub.0.33)O.sub.2 particles may be
synthesized at a temperature of 900.degree. C. with a preheating
temperature of 230.degree. C. The preheating can prevent the
formation of hollow particles. FIG. 5 has thus demonstrated the
polydisperse particle synthesis using the atomizer device aerosol
mode control and synthesis temperature control.
[0070] FIG. 6A is an SEM image of synthesized LiMn.sub.2O.sub.4
battery cathode material, consistent with various embodiments of
the present disclosure. According to the above-described material
synthesis method, ultrafine LiMn.sub.2O.sub.4 battery cathode
particle material may be prepared at a process temperature of
2500.degree. C. FIG. 6B is an SEM image of synthesized
Y.sub.2O.sub.3 deposited onto an aluminum foil, consistent with
various embodiments of the present disclosure. According to the
above-described material synthesis method, ultrafine Y.sub.2O.sub.3
particles deposited onto an aluminum foil may be prepared at a
process temperature of 2500.degree. C. FIG. 6A and FIG. 6B have
thus demonstrated ultrafine particle synthesis using synthesis
temperature control.
[0071] FIG. 7 is a transmission electron microscope (TEM) image of
synthesized hollow metal oxide Y.sub.2O.sub.3 particles, consistent
with various embodiments of the present disclosure. According to
the above-described material synthesis method, hollow metal oxide
Y.sub.2O.sub.3 particles may be prepared from micron-sized droplets
and heated in a reactive zone at a process temperature of
900.degree. C. without preheating. In the absence of preheating,
the rapid solvent evaporation in the reactor may cause the solute
to precipitate on the droplet surface, and because the downstream
synthesis temperature is low, hollow product particles are formed.
FIG. 7 has thus demonstrated hollow-structured particle
synthesis.
[0072] FIG. 8A and FIG. 8B are SEM images of synthesized metal
oxide Y.sub.2O.sub.3 particles, consistent with various embodiments
of the present disclosure. FIG. 8A shows synthesized metal oxide
Y.sub.2O.sub.3 particles prepared at a process temperature of
1600.degree. C. without preheating. The resultant Y.sub.2O.sub.3
particles are hollow and have a large (>1 .mu.m) size, and many
nanoparticles are also formed by the gas-to-particle route.
[0073] FIG. 8B shows synthesized metal oxide Y.sub.2O.sub.3
particles prepared at a process temperature of 1600.degree. C. with
preheating at 200.degree. C., and otherwise similar to the process
of FIG. 8A. The resultant Y.sub.2O.sub.3 particles are dense,
because during the slow preheating, no shell is formed. Further,
nanoparticle formation from the gas-phase is significantly reduced.
FIG. 8A and FIG. 8B have thus demonstrated particle morphology
control using preheating.
[0074] FIG. 9A is an SEM image of
Li(Ni.sub.0.33Mn.sub.0.33Co.sub.0.33)O.sub.2 Li-ion battery
materials synthesized with the disclosed method, and FIG. 9B is a
graphical illustration of number-based particle size distribution
of the material shown in FIG. 9A, consistent with various
embodiments of the present disclosure. The material may be prepared
using the above-described atomizer device, and followed by a
preheating temperature of 110.degree. C. and a process temperature
of 1250.degree. C.
[0075] FIG. 9C is an SEM image of
Li(Ni.sub.0.33Mn.sub.0.33Co.sub.0.33)O.sub.2 Li-ion battery
materials synthesized with a conventional ultrasonic atomization
method, and FIG. 9D is a graphical illustration of number-based
particle size distribution of the material shown in FIG. 9C.
Compared with the conventional method, FIG. 9A and FIG. 9B show
that the disclosed synthesis method using the atomizer device, for
example, a microspray atomizer, produces a mixture of many smaller
and some larger particles, and therefore the resultant material has
a higher packing density and an improved volumetric energy density.
Also, using the atomizer device, the median particle size is
smaller than the particles produced using the conventional
atomization technique. FIG. 9A and FIG. 9B have thus demonstrated
using the atomizer device to produce polydisperse
nanoparticles.
[0076] FIG. 10 is a graphical illustration of particle size
distribution of produced metal oxide particles, consistent with
various embodiments of the present disclosure. FIG. 10 shows
polydisperse nanoparticle synthesized using the dual mode aerosol,
and tailoring of the precursor concentration to change the median
particle size. Particle distributions corresponding to three
different precursor concentrations (1M, 0.1M, and 0.01M) are shown,
in which higher precursor concentrations result in larger particles
being produced. FIG. 10 has thus demonstrated the control of
particle size distribution using sub-micron aerosols.
[0077] FIG. 11 is an X-ray diffraction pattern of annealed lithium
NMC (lithium nickel manganese cobalt oxide) powders, consistent
with various embodiments of the present disclosure. The materials
can be applied in lithium-ion batteries. The illustrated peaks
correspond to ICDD (International Center for Diffraction Data)
datacard 056-0147, indicating the crystalline structure of the
material.
[0078] FIG. 12 is a flowchart illustrating an exemplary material
synthesis method 600, consistent with various embodiments of the
present disclosure. The operations of the exemplary material
synthesis method 600 and its various steps presented herein are
intended to be illustrative. Depending on the implementation, the
exemplary material synthesis method 600 may include additional,
fewer, or alternative steps performed in various orders or in
parallel.
[0079] Step 601 comprises adding at least one liquid precursor
solution to an atomizer device. In some embodiments, the at least
one liquid precursor solution may comprise a metal salt dissolved
or diluted in a solvent. The metal salt may comprise at least one
of alkaline, transition, or lanthanide metals. The solvent may
comprise at least one of water, metal alkoxide, or one or more
hydrocarbon liquids. The median size of the synthesized particles
by the method 600 may increase with the molar concentration of the
liquid precursor solution. The at least one liquid precursor
solution may have a dynamic viscosity of less than 0.2 Pas and a
molar concentration of 0.001-2 mol/L (e.g., 0.1-2 mol/L).
[0080] Step 602 comprises generating by the atomizer device an
aerosol comprising liquid droplets. In some embodiments, for a
sub-micron mode of the atomizer device, at least 99% of the liquid
droplets by number have a diameter of less than 1 .mu.m and an
arithmetic mean diameter between 0.1 and 1 .mu.m, and the particles
produced by the method 600 are monodisperse with an average
diameter between 5-100 nm. For a dual mode of the atomizer device,
the liquid droplets are sub-micron sized in diameter or 1-100 .mu.m
in diameter, and the particles produced by the method 600 are
polydisperse with diameters between 5 nm-10 .mu.m. For example, the
atomizer device may comprise a microspray atomizer. Generating the
aerosol may comprise introducing an atomizing gas flow into the
microspray atomizer and generating the aerosol in the microspray
atomizer. The atomizing gas may comprise at least one of an
oxidizer gas, an inert gas, or a fuel gas. The atomizing gas flow
may have a pressure of 1-100 bar (e.g., 1-10 bar).
[0081] Optional step 603 comprises transporting the aerosol to a
preheating section for evaporating at least a portion of the one or
more solvents from the aerosol. For example, preheating the aerosol
may be performed at a temperature between 50.degree. C. and
500.degree. C. for evaporating at least the portion of the one or
more solvents from the aerosol for 0.1-10 seconds. Energy for the
preheating can be provided by at least one of electrical heating,
combustion heating, or heat exchange with a recirculated exhaust
gas.
[0082] Step 604 comprises transporting the aerosol to a reactive
zone for evaporating one or more solvents from the aerosol. The
reactive zone may comprise at least one of a flame, plasma,
furnace, laser heating, or electric heating for supplying energy.
The reactive zone may be at a temperature of 500-10000.degree. C.
and a pressure of 500 mbar-10 bar. Transporting the aerosol to the
reactive zone for evaporating one or more solvents from the aerosol
may comprise transporting the aerosol to the reactive zone for
evaporating one or more solvents from the aerosol for 0.1-10
seconds (e.g., 0.5-5 seconds). In some embodiments, transporting
the aerosol to the reactive zone may comprise transporting the
aerosol to the reactive zone without preheating, and the
synthesized particles by the method 600 are hollow-structured.
[0083] Step 605 comprises collecting particles synthesized from at
least evaporating the aerosol. In some embodiments, collecting the
synthesized particles comprises collecting the synthesized
particles from an exhaust stream of the reactive zone by membrane
filtering, electrostatic collection, bag filtering, or cold trap.
The synthesized particles may comprise a metal oxide, fluoride,
sulphide, oxysulphide, silicate, nitrate or nitride. The
synthesized particles may comprise homogeneous and non-aggregated
particles. For example, the synthesized particles may comprise
particles selected from a group consisting of: monodisperse
Li(Ni.sub.0.33Mn.sub.0.33Co.sub.0.33)O.sub.2 particles with an
average diameter between 5-100 nm, hollow-structured
Li(Ni.sub.0.33Mn.sub.0.33Co.sub.0.33)O.sub.2 particles,
LiMn.sub.2O.sub.4 which has a mean diameter between 5-10 nm, and
polydisperse Li(Ni.sub.0.33Mn.sub.0.33Co.sub.0.33)O.sub.2 particles
with diameters between 5 nm-10 .mu.m. Further details of the method
600 can be found above with reference to FIG. 1 to FIG. 11.
[0084] FIG. 13 is a flowchart illustrating an exemplary material
synthesis method 700, consistent with various embodiments of the
present disclosure. The operations of the exemplary material
synthesis method 700 and its various steps presented herein are
intended to be illustrative. Depending on the implementation, the
exemplary material synthesis method 700 may include additional,
fewer, or alternative steps performed in various orders or in
parallel.
[0085] Step 701 comprises adding a first precursor solution to an
atomizer device to generate a first aerosol comprising first liquid
droplets. Step 702 comprises transporting the first aerosol to a
reactive zone for evaporating one or more first solvents from the
first aerosol to obtain first synthesized particles of a first size
distribution. Step 703 comprises adding a second precursor solution
to the atomizer device to generate a second aerosol comprising
second liquid droplets. Step 704 comprises transporting the second
aerosol to the reactive zone for evaporating one or more second
solvents from the second aerosol to obtain second synthesized
particles of a second size distribution. Before the step 703 is
performed, the atomizer device may be emptied such that no first
precursor solution is left. In some embodiments, the first
precursor solution may comprise gasoline, and the second precursor
solution may comprise water. Alternatively, the first precursor
solution may comprise water, and the second precursor solution may
comprise gasoline. In addition, various other liquids can be used
instead of gasoline and water. The liquids may have various
different viscosity, density, and surface tension measurements. In
some embodiments, droplets of higher viscosity, surface tension,
and density (e.g., no less than deionized water in such
measurements) may be used for the dual mode of the atomizer device,
while droplets of lower viscosity, surface tension, and density
(e.g., no more than 95 RON gasoline in such measurements) may be
used for the submicron mode of the atomizer device.
[0086] In some embodiments, generating the first or second aerosol
comprises disintegrating liquid films of the first or second
precursor solution respectively with gas jets; and the first and
second precursor solutions are associated with different surface
tensions.
[0087] In some embodiments, the first and second size distributions
are selected from monodisperse and polydisperse distributions
(e.g., the first size distribution may be monodisperse and the
second distribution may be polydisperse and vice versa). The
monodisperse distribution is associated with an average diameter
between 5-100 nm, and is obtained from corresponding liquid
droplets that at least 99% by number of which have a diameter of
less than 1 .mu.m or an arithmetic mean diameter between 0.1 and 1
.mu.m. The polydisperse distribution is associated with diameters
between 5 nm-10 .mu.m, and is obtained from corresponding liquid
droplets that are sub-micron in diameter or 1-100 .mu.m in
diameter. The monodisperse distribution may correspond to the
above-described sub-micron mode, and the polydisperse distribution
may correspond to the above-described dual mode. Various other
synthesis conditions (e.g., preheating and reactor temperature,
pressure, and residence time) can be referred to from the above
descriptions.
[0088] As such, various materials can be efficiently synthesized by
the disclosed method. For example, controlling the nanostructure
and size of cathode and anode materials (e.g., layered transition
metal oxide particles such as
Li(Ni.sub.0.33Mn.sub.0.33Co.sub.0.33)O.sub.2) allows reduction of
Li-ion diffusion time, increased surface areas and packing density,
and optimization of electronic conduction to enhance battery
specific capacity and charge/discharge rates, while also reducing
adverse chemical reactions and/or structural changes. The particle
size control methods disclosed herein can, in a single processing
step, benefit battery calendar lifetime, cycle numbers, and battery
safety. The single processing step can obviate the
separation/sieving required in existing technologies. A further
example is the tailoring of optical properties to improve
absorption efficiency of photoactive materials such as
transition-metal doped TiO.sub.2. Still another example is the
increased catalytic activity of nanomaterials (e.g., rare-earth
perovskites or noble metals on code supports) due to the extremely
high specific surface area. Yet another example is to control
particle size and morphology of thermal-chemical energy storage
materials to achieve efficient and fast energy storage. A further
example is the synthesis of thin films using a combination of
different nanomaterials to control the sensitivity and
functionality of thin films.
[0089] The present disclosure recites many ranges in, for example,
temperature, pressure, dimension, time, etc. In some instances, a
broad range is given with exemplary narrower ranges. These
exemplary narrower ranges are not repeated in other instances where
the broad range is described, but are also applicable in those
instances.
[0090] Advantages of the disclosed material synthesis method
include: versatility (nanoparticles of different materials can be
manufactured, using solvents with very different properties),
simplicity, controllable particle sizes including a monodisperse
ultrafine mode and a polydisperse mode, very short process time,
scalability of production rate, and economic efficiency (low costs
required for construction and operation).
[0091] The various features and processes described above may be
used independently of one another, or may be combined in various
ways. All possible combinations and sub-combinations are intended
to fall within the scope of this disclosure. In addition, certain
method or process blocks may be omitted in some implementations.
The methods and processes described herein are also not limited to
any particular sequence, and the blocks or states relating thereto
can be performed in other sequences that are appropriate. For
example, described blocks or states may be performed in an order
other than that specifically disclosed, or multiple blocks or
states may be combined in a single block or state. The example
blocks or states may be performed in serial, in parallel, or in
some other manner. Blocks or states may be added to or removed from
the disclosed example embodiments. The example systems and
components described herein may be configured differently than
described. For example, elements may be added to, removed from, or
rearranged compared to the disclosed example embodiments.
[0092] Throughout this specification, plural instances may
implement components, operations, or structures described as a
single instance. Although individual operations of one or more
methods are illustrated and described as separate operations, one
or more of the individual operations may be performed concurrently,
and nothing requires that the operations be performed in the order
illustrated. Structures and functionality presented as separate
components in example configurations may be implemented as a
combined structure or component. Similarly, structures and
functionality presented as a single component may be implemented as
separate components. These and other variations, modifications,
additions, and improvements fall within the scope of the subject
matter herein.
[0093] Although an overview of the subject matter has been
described with reference to specific example embodiments, various
modifications and changes may be made to these embodiments without
departing from the broader scope of embodiments of the present
disclosure. Such embodiments of the subject matter may be referred
to herein, individually or collectively, by the term "invention"
merely for convenience and without intending to voluntarily limit
the scope of this application to any single disclosure or concept
if more than one is, in fact, disclosed.
[0094] The Detailed Description is not to betaken in a limiting
sense, and the scope of various embodiments is defined only by the
appended claims, along with the full range of equivalents to which
such claims are entitled.
* * * * *