U.S. patent application number 17/308519 was filed with the patent office on 2021-09-02 for solid-state battery.
This patent application is currently assigned to FMC Lithium USA Corp.. The applicant listed for this patent is FMC Lithium USA Corp.. Invention is credited to Kenneth Brian Fitch, William Arthur Greeter, JR., Jian Xia, Marina Yakovleva.
Application Number | 20210273260 17/308519 |
Document ID | / |
Family ID | 1000005564940 |
Filed Date | 2021-09-02 |
United States Patent
Application |
20210273260 |
Kind Code |
A1 |
Yakovleva; Marina ; et
al. |
September 2, 2021 |
SOLID-STATE BATTERY
Abstract
A solid-state battery comprising a cathode, an anode and a solid
electrolyte is provided. In one embodiment, the cathode, anode
and/or solid electrolyte is formed from a printable lithium
composition including lithium metal powder, a polymer binder
compatible with the lithium metal powder, a rheology modifier
compatible with the lithium metal powder, and a solvent compatible
with the lithium metal powder and with the polymer binder. In
another embodiment, lithium is deposited onto the solid electrolyte
with a lithium printable lithium composition including lithium
metal powder, a polymer binder compatible with the lithium metal
powder, a rheology modifier compatible with the lithium metal
powder, and a solvent compatible with the lithium metal powder and
with the polymer binder.
Inventors: |
Yakovleva; Marina;
(Gastonia, NC) ; Fitch; Kenneth Brian;
(Cherryville, NC) ; Xia; Jian; (Belmont, NC)
; Greeter, JR.; William Arthur; (Dallas, NC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FMC Lithium USA Corp. |
Philadelphia |
PA |
US |
|
|
Assignee: |
FMC Lithium USA Corp.
|
Family ID: |
1000005564940 |
Appl. No.: |
17/308519 |
Filed: |
May 5, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16359733 |
Mar 20, 2019 |
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17308519 |
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62646521 |
Mar 22, 2018 |
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62691819 |
Jun 29, 2018 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01M 4/485 20130101;
H01M 4/0411 20130101; H01M 4/139 20130101; H01M 10/0525 20130101;
H01M 2004/027 20130101; H01M 4/364 20130101; H01M 10/052 20130101;
H01M 4/134 20130101; H01M 10/0585 20130101; H01M 4/602 20130101;
H01M 4/624 20130101; H01M 4/0414 20130101; H01M 4/382 20130101;
H01M 4/622 20130101; H01M 4/1395 20130101; H01M 4/0409 20130101;
H01M 10/0565 20130101; H01M 4/0404 20130101 |
International
Class: |
H01M 10/0565 20060101
H01M010/0565; H01M 4/1395 20060101 H01M004/1395; H01M 4/38 20060101
H01M004/38; H01M 4/62 20060101 H01M004/62; H01M 4/134 20060101
H01M004/134; H01M 4/04 20060101 H01M004/04; H01M 10/0585 20060101
H01M010/0585; H01M 10/052 20060101 H01M010/052; H01M 10/0525
20060101 H01M010/0525; H01M 4/139 20060101 H01M004/139; H01M 4/36
20060101 H01M004/36; H01M 4/485 20060101 H01M004/485; H01M 4/60
20060101 H01M004/60 |
Claims
1. A solid-state battery comprising a cathode, an anode and a solid
electrolyte, wherein at least the anode, cathode and/or solid
electrolyte is formed from a printable lithium composition
comprised on a solution basis of: a) 5 to 50 percent of lithium
metal powder, b) 0.1 to 20 of a polymer binder compatible with the
lithium metal powder, c) 0.1 to 30 percent of a rheology modifier
compatible with the lithium metal powder, and d) 50 to 95 percent
of a nonpolar solvent compatible with the lithium metal powder and
with the polymer binder.
2. The solid-state battery of claim 1, wherein the anode and/or
cathode is formed by printing the printable lithium composition
onto the anode and/or cathode.
3. The solid-state battery of claim 1, wherein the anode is formed
by printing the printable lithium composition onto a current
collector.
4. The solid-state battery of claim 1, wherein the anode and/or
cathode is formed by coating the anode and/or cathode with the
printable lithium composition.
5. The solid-state battery of claim 1, wherein the anode and/or
cathode is formed by depositing the printable lithium composition
onto the anode and/or cathode using an electric current.
6. The solid-state battery of claim 1, wherein the lithium powder
is stabilized lithium metal powder.
7. The solid-state battery of claim 1, wherein the rheology
modifier is selected from the group consisting of carbonaceous
materials, silicon-containing materials, tin-containing materials,
Group IIA oxides, Group IIIA oxides, Group IVB oxides, Group VB
oxides and Group VIA oxides.
8. The solid-state battery of claim 7, wherein the carbonaceous
material is selected from the group consisting of carbon black,
carbon nanotubes, graphite, hard carbon, and graphene. lithium
metal powder, a polymer binder compatible with the lithium metal
powder, a rheology modifier compatible with the lithium metal
powder and the polymer binder, and a solvent compatible with the
lithium metal powder and with the polymer binder.
20. The solid-state battery of claim 19, wherein lithium is
deposited onto the solid electrolyte by printing the printable
lithium composition onto the solid electrolyte.
21. The solid-state battery of claim 19, wherein lithium is
deposited onto the solid electrolyte by coating the solid
electrolyte with the printable lithium composition.
22. The solid-state battery of claim 19, wherein the lithium powder
is stabilized lithium metal powder.
23. The solid-state battery of claim 19, wherein the rheology
modifier is selected from the group consisting of carbonaceous
materials, silicon-containing materials, tin-containing materials,
Group IIA oxides, Group IIIA oxides, Group IVB oxides, Group VB
oxides and Group VIA oxides.
24. The solid-state battery of claim 23, wherein the carbonaceous
material is selected from the group consisting of carbon black,
carbon nanotubes, graphite, hard carbon, and graphene.
25. The solid-state battery of claim 23, wherein the
silicon-containing material is selected from the group consisting
of silicon nanotubes and fumed silica.
26. The solid-state battery of claim 23, wherein the Group IVB
oxide is selected from the group consisting of titanium dioxide and
zirconium dioxide.
27. The solid-state battery of claim 23, wherein the Group IIIA
oxide is aluminum oxide.
28. The solid-state battery of claim 19, wherein the polymer binder
has a molecular weight of 1,000 to 8,000,000 and is selected from
the group consisting of unsaturated elastomers, saturated
elastomers, thermoplastics, polyacrylic acid, polyvinylidene
chloride, and polyvinyl acetate.
9. The solid-state battery of claim 7, wherein the
silicon-containing material is selected from the group consisting
of silicon nanotubes and fumed silica.
10. The solid-state battery of claim 7, wherein the Group IVB oxide
is selected from the group consisting of titanium dioxide and
zirconium dioxide.
11. The solid-state battery of claim 7, wherein the Group IIIA
oxide is aluminum oxide.
12. The solid-state battery of claim 1, wherein the polymer binder
has a molecular weight of 1,000 to 8,000,000 and is selected from
the group consisting of unsaturated elastomers, saturated
elastomers, thermoplastics, polyacrylic acid, polyvinylidene
chloride, and polyvinyl acetate.
13. The solid-state battery of claim 12, wherein the unsaturated
elastomer is selected from the group consisting of butadiene
rubber, isobutylene, and styrene butadiene rubber.
14. The solid-state battery of claim 12, wherein the saturated
elastomer is selected from the group consisting of ethylene
propylene diene monomer rubber and ethylene-vinyl acetate.
15. The solid-state battery of claim 12, wherein the thermoplastic
is selected from the group consisting of polystyrene, polyethylene
and polymers of ethylene oxide.
16. The solid-state battery of claim 15, wherein the polymers of
ethylene oxide is selected from the group consisting of
poly(ethylene glycol) and poly(ethylene oxide).
17. The solid-state battery of claim 1, wherein the nonpolar
solvent is selected from the group consisting of alkanes, toluene,
ethylbenzene, cumene, xylene, sulfones, mineral oil, glymes, and
isoparaffinic synthetic hydrocarbon solvents.
18. The solid-state battery of claim 1, wherein the lithium is
deposited onto the solid electrolyte using the printable lithium
composition.
19. A solid-state battery comprising a cathode, an anode and a
solid electrolyte, wherein lithium is deposited onto the solid
electrolyte with a lithium printable lithium composition comprised
of
29. The solid-state battery of claim 28, wherein the unsaturated
elastomer is selected from the group consisting of butadiene
rubber, isobutylene, and styrene butadiene rubber.
30. The solid-state battery of claim 28, wherein the saturated
elastomer is selected from the group consisting of ethylene
propylene diene monomer rubber and ethylene-vinyl acetate.
31. The solid-state battery of claim 28, wherein the thermoplastic
is selected from the group consisting of polystyrene, polyethylene
and polymers of ethylene oxide.
32. The solid-state battery of claim 31, wherein the polymers of
ethylene oxide is selected from the group consisting of
poly(ethylene glycol) and poly(ethylene oxide).
33. The solid-state battery of claim 19, wherein the solvent is
selected from the group consisting of alkanes, toluene,
ethylbenzene, cumene, xylene, sulfones, mineral oil, glymes, and
isoparaffinic synthetic hydrocarbon solvents.
34. The solid-state battery of claim 19, wherein the printable
lithium composition comprises on a solution basis: a) 5 to 50
percent lithium metal powder; b) 0.1 to 20 percent polymer binder;
c) 0.1 to 30 percent rheology modifier; d) 50 to 95 percent
solvent.
35. The solid-state battery of claim 19, wherein the anode is
lithiated using the printable lithium composition.
Description
RELATED APPLICATIONS
[0001] The following application is a continuation of U.S.
application Ser. No. 16/359,733 filed Mar. 20, 2019, which claims
priority to U.S. Provisional No. 62/646,521 filed Mar. 22, 2018,
and U.S. Provisional No. 62/691,819 filed Jun. 29, 2018, the
disclosures of which are incorporated by reference in their
entireties.
FIELD OF THE INVENTION
[0002] The present invention relates to a solid-state battery which
includes a printable lithium composition.
BACKGROUND OF THE INVENTION
[0003] Lithium and lithium-ion secondary or rechargeable batteries
have found use in certain applications such as in cellular phones,
camcorders, and laptop computers, and even more recently, in larger
power application such as in electric vehicles and hybrid electric
vehicles. It is preferred in these applications that the secondary
batteries have the highest specific capacity possible but still
provide safe operating conditions and good cyclability so that the
high specific capacity is maintained in subsequent recharging and
discharging cycles.
[0004] Although there are various constructions for secondary
batteries, each construction includes a positive electrode (or
cathode), a negative electrode (or anode), a separator that
separates the cathode and anode, an electrolyte in electrochemical
communication with the cathode and anode. For secondary lithium
batteries, lithium ions are transferred from the anode to the
cathode through the electrolyte when the secondary battery is being
discharged, i.e., used for its specific application. During the
discharge process, electrons are collected from the anode and pass
to the cathode through an external circuit. When the secondary
battery is being charged, or recharged, the lithium ions are
transferred from the cathode to the anode through the
electrolyte.
[0005] Historically, secondary lithium batteries were produced
using non-lithiated compounds having high specific capacities such
as TiS.sub.2, MoS.sub.2, MnO2, and V.sub.2O.sub.5, as the cathode
active materials. These cathode active materials were coupled with
a lithium metal anode. When the secondary battery was discharged,
lithium ions were transferred from the lithium metal anode to the
cathode through the electrolyte. Unfortunately, upon cycling, the
lithium metal developed dendrites that ultimately caused unsafe
conditions in the battery. As a result, the production of these
types of secondary batteries was stopped in the early 1990s in
favor of lithium-ion batteries.
[0006] Lithium-ion batteries typically use lithium metal oxides
such as LiCoO.sub.2 and LiNiO.sub.2 as cathode active materials
coupled with an active anode material such as a carbon-based
material. It is recognized that there are other anode types based
on silicon oxide, silicon particles and the like. In batteries
utilizing carbon-based anode systems, the lithium dendrite
formation on the anode is substantially avoided, thereby making the
battery safer. However, the lithium, the amount of which determines
the battery capacity, is totally supplied from the cathode. This
limits the choice of cathode active materials because the active
materials must contain removable lithium. Also, delithiated
products corresponding to Li.sub.xCoO.sub.2, Li.sub.xNiO.sub.2
formed during charging and overcharging are not stable. In
particular, these delithiated products tend to react with the
electrolyte and generate heat, which raises safety concerns.
[0007] New lithium-ion cells or batteries are initially in a
discharged state. During the first charge of lithium-ion cell,
lithium moves from the cathode material to the anode active
material. The lithium moving from the cathode to the anode reacts
with an electrolyte material at the surface of the graphite anode,
causing the formation of a passivation film on the anode. The
passivation film formed on the graphite anode is a solid
electrolyte interface (SEI). Upon subsequent discharge, the lithium
consumed by the formation of the SEI is not returned to the
cathode. This results in a lithium-ion cell having a smaller
capacity compared to the initial charge capacity because some of
the lithium has been consumed by the formation of the SEI. The
partial consumption of the available lithium on the first cycle
reduces the capacity of the lithium-ion cell. This phenomenon is
called irreversible capacity and is known to consume about 10% to
more than 20% of the capacity of a lithium ion cell. Thus, after
the initial charge of a lithium-ion cell, the lithium-ion cell
loses about 10% to more than 20% of its capacity.
[0008] One solution has been to use stabilized lithium metal powder
to pre-lithiate the anode. For example, lithium powder can be
stabilized by passivating the metal powder surface with carbon
dioxide such as described in U.S. Pat. Nos. 5,567,474, 5,776,369,
and 5,976,403, the disclosures of which are incorporated herein in
their entireties by reference. The CO.sub.2-passivated lithium
metal powder can be used only in air with low moisture levels for a
limited period of time before the lithium metal content decays
because of the reaction of the lithium metal and air. Another
solution is to apply a coating such as fluorine, wax, phosphorus or
a polymer to the lithium metal powder such as described in U.S.
Pat. Nos. 7,588,623, 8,021,496, 8,377,236 and U.S. Patent
Publication No. 2017/0149052, for example.
[0009] There, however, remains a need for a solid-state battery
having lithiated or prelithiated components for increased energy
density and improved safety and manufacturability.
SUMMARY OF THE INVENTION
[0010] To this end, the present invention provides a solid-state
battery with one or more components prelithiated, or lithiated with
a printable lithium composition. A solid-state battery comprising
the printable lithium composition will have increased energy
density and improved safety and manufacturability.
[0011] The printable lithium composition of the present invention
comprises a lithium metal powder, a polymer binder, wherein the
polymer binder is compatible with the lithium powder, and a
rheology modifier compatible with the lithium powder and the
polymer binder. A solvent may be included in the printable lithium
composition, wherein the solvent is compatible with the lithium
powder and compatible with (e.g., able to form suspension or to
dissolve in) the polymer binder. The solvent may be included as a
component during the initial preparation of the printable lithium
composition or added later after the printable lithium composition
is prepared.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a schematic of a solid-state battery according to
one embodiment of the present invention;
[0013] FIG. 2 is a temperature and pressure profile for the
reactivity testing of SLMP/styrene butadiene/toluene printable
lithium composition; and
[0014] FIG. 3 is a plot showing the cycle performance for a pouch
cell with printable lithium derived thin lithium film as the anode
vs. commercial thin lithium foil.
DETAILED DESCRIPTION OF THE INVENTION
[0015] The foregoing and other aspects of the present invention
will now be described in more detail with respect to the
description and methodologies provided herein. It should be
appreciated that the invention can be embodied in different forms
and should not be construed as limited to the embodiments set forth
herein. Rather, these embodiments are provided so that this
disclosure will be thorough and complete, and will fully convey the
scope of the invention to those skilled in the art.
[0016] The terminology used in the description of the invention
herein is for the purpose of describing particular embodiments only
and is not intended to be limiting of the invention. As used in the
description of the embodiments of the invention and the appended
claims, the singular forms "a", "an" and "the" are intended to
include the plural forms as well, unless the context clearly
indicates otherwise. Also, as used herein, "and/or" refers to and
encompasses any and all possible combinations of one or more of the
associated listed items.
[0017] The term "about," as used herein when referring to a
measurable value such as an amount of a compound, dose, time,
temperature, and the like, is meant to encompass variations of 20%,
10%, 5%, 1%, 0.5%, or even 0.1% of the specified amount. Unless
otherwise defined, all terms, including technical and scientific
terms used in the description, have the same meaning as commonly
understood by one of ordinary skill in the art to which this
invention belongs.
[0018] As used herein, the terms "comprise," "comprises,"
"comprising," "include," "includes" and "including" specify the
presence of stated features, integers, steps, operations, elements,
and/or components, but do not preclude the presence or addition of
one or more other features, integers, steps, operations, elements,
components, and/or groups thereof.
[0019] As used herein, the term "consists essentially of" (and
grammatical variants thereof), as applied to the compositions and
methods of the present invention, means that the
compositions/methods may contain additional components so long as
the additional components do not materially alter the
composition/method. The term "materially alter," as applied to a
composition/method, refers to an increase or decrease in the
effectiveness of the composition/method of at least about 20% or
more.
[0020] All patents, patent applications and publications referred
to herein are incorporated by reference in their entirety. In case
of a conflict in terminology, the present specification is
controlling.
[0021] Referring now to FIG. 1, a solid-state battery 10 comprising
an anode 12, a cathode 14 and a solid electrolyte 16 is provided in
accordance with one embodiment of the present invention. The
solid-state battery may further include an anode current collector
20 and a cathode current collector 22. A printable lithium
composition is applied or deposited to a current collector,
electrode and/or solid electrolyte of the solid-state battery. For
example, the printable lithium composition may be used to form a
monolithic lithium metal anode of various thicknesses and widths
for use in a solid-state battery, including solid-state batteries
as described in U.S. Pat. Nos. 8,252,438 and 9,893,379 and
incorporated herein by reference in their entireties. In yet
another embodiment, the printable lithium composition may be
applied or deposited so as to form a solid electrolyte for a
solid-state battery, and includes combining the ink composition
with a polymer or ceramic material to form a solid electrolyte. The
printable lithium composition comprises a lithium metal powder, one
or more polymer binders, one or more rheology modifiers and may
further include a solvent or co-solvent.
[0022] The printable lithium composition may be applied a current
collector, electrode or solid electrolyte by various methods,
including extruding, coating, printing, painting, dipping, and
spraying as disclosed in U.S. application Ser. No.______ (Attorney
Matter ID 073396.1183, filed concurrently with this application and
hereby incorporated by reference in its entirety). For example, the
anode may be lithiated or prelithiated by printing the printable
lithium composition onto the anode or a current collector, where
the thin lithium film with controlled thickness and width could be
formed, or coating the anode with the printable lithium
composition.
[0023] In one embodiment, the printable lithium composition may be
used to prelithiate a solid electrolyte as described in U.S. Pat.
No. 7,914,930 herein incorporated by reference in its entirety. One
example of a solid-state secondary battery may include a positive
electrode capable of electrochemically absorbing and desorbing
lithium; a negative electrode capable of electrochemically
absorbing and desorbing lithium, the negative electrode including
an active material layer that comprises an active material, the
active material layer being carried on a current collector; and a
non-aqueous electrolyte. A method includes the steps of: reacting
lithium with the active material of the negative electrode by
bringing the printable lithium composition into contact with a
surface of the active material layer of the negative electrode; and
thereafter combining the negative electrode with the positive
electrode to form an electrode assembly.
[0024] As disclosed in U.S. application Ser. No.______ (Attorney
Matter ID. 073396.1116, filed concurrently with this application)
and hereby incorporated by reference in its entirety, the printable
lithium composition comprises a lithium metal powder, a polymer
binder, a rheology modifier and may further include a solvent. The
polymer binder may be compatible with the lithium metal powder. The
rheology modifier may be compatible with the lithium metal powder
and the polymer binder. The solvent may be compatible with the
lithium metal powder and with the polymer binder.
[0025] The lithium metal powder may be in the form of a finely
divided powder. The lithium metal powder typically has a mean
particle size of less than about 80 microns, often less than about
40 microns and sometimes less than about 20 microns. The lithium
metal powder may be a low pyrophoricity stabilized lithium metal
power (SLMP.RTM.) available from FMC Lithium Corp. The lithium
metal powder may also include a substantially continuous layer or
coating of fluorine, wax, phosphorus or a polymer or the
combination thereof (as disclosed in U.S. Pat. Nos. 5,567,474,
5,776,369, and 5,976,403). Lithium metal powder has a significantly
reduced reaction with moisture and air.
[0026] The lithium metal powder may also be alloyed with a metal.
For example, the lithium metal powder may be alloyed with a Group
I-VIII element. Suitable elements from Group IB may include, for
example, copper, silver, or gold. Suitable elements from Group IIB
may include, for example, zinc, cadmium, or mercury. Suitable
elements from Group IIA of the Periodic Table may include
beryllium, magnesium, calcium, strontium, barium, and radium.
Elements from Group IIIA that may be used in the present invention
may include, for example, boron, aluminum, gallium, indium, or
thallium. Elements from Group IVA that may be used in the present
invention may include, for example, carbon, silicon, germanium,
tin, or lead. Elements from Group VA that may be used in the
present invention may include, for example, nitrogen, phosphorus,
or bismuth. Suitable elements from Group VIIIB may include, for
example, nickel, palladium, or platinum.
[0027] The polymer binder is selected so as to be compatible with
the lithium metal powder. "Compatible with" or "compatibility" is
intended to convey that the polymer binder does not violently react
with the lithium metal powder resulting in a safety hazard. The
lithium metal powder and the polymer binder may react to form a
lithium-polymer complex, however, such complex should be stable at
various temperatures. It is recognized that the amount
(concentration) of lithium and polymer binder contribute to the
stability and reactivity. The polymer binder may have a molecular
weight of about 1,000 to about 8,000,000, and often has a molecular
weight of 2,000,000 to 5,000,000. Suitable polymer binders may
include one or more of poly(ethylene oxide), polystyrene,
polyisobutylene, natural rubbers, butadiene rubbers,
styrene-butadiene rubber, polyisoprene rubbers, butyl rubbers,
hydrogenated nitrile butadiene rubbers, epichlorohydrin rubbers,
acrylate rubbers, silicon rubbers, nitrile rubbers, polyacrylic
acid, polyvinylidene chloride, polyvinyl acetate, ethylene
propylene diene termonomer, ethylene vinyl acetate copolymer,
ethylene-propylene copolymers, ethylene-propylene terpolymers,
polybutenes. The binder may also be a wax.
[0028] The rheology modifier is selected to be compatible with the
lithium metal powder and the polymer binder. The rheology modifier
provides rheology properties such as viscosity. The rheology
modifier may also provide conductivity, improved capacity and/or
improved stability/safety depending on the selection of the
rheology modifier. To this end, the rheology modifier may be the
combination of two or more compounds so as to provide different
properties or to provide additive properties. Exemplary rheology
modifiers may include one or more of carbon black, carbon
nanotubes, graphene, silicon nanotubes, graphite, hard carbon and
mixtures, fumed silica, titanium dioxide, zirconium dioxide and
other Group IIA, IIIA, IVB, VB and VIA elements/compounds and
mixtures or blends thereof.
[0029] Solvents compatible with lithium may include acyclic
hydrocarbons, cyclic hydrocarbons, aromatic hydrocarbons,
symmetrical ethers, unsymmetrical ethers, cyclic ethers, alkanes,
sulfones, mineral oil, and mixtures, blends or cosolvents thereof.
Examples of suitable acyclic and cyclic hydrocarbons include
n-hexane, n-heptane, cyclohexane, and the like. Examples of
suitable aromatic hydrocarbons include toluene, ethylbenzene,
xylene, isopropylbenzene (cumene), and the like. Examples of
suitable symmetrical, unsymmetrical and cyclic ethers include
di-n-butyl ether, methyl t-butyl ether, tetrahydrofuran, glymes and
the like. Commercially available isoparaffinic synthetic
hydrocarbon solvents with tailored boiling point ranges such as
Shell Sol.RTM. (Shell Chemicals) or Isopar.RTM. (Exxon) are also
suitable.
[0030] The polymer binder and solvents are selected to be
compatible with each other and with the lithium metal powder. In
general, the binder or solvent should be non-reactive with the
lithium metal powder or in amounts so that any reaction is kept to
a minimum and violent reactions are avoided. The binder and solvent
should be compatible with each other at the temperatures at which
the printable lithium composition is made and will be used.
Preferably the solvent (or co-solvent) will have sufficient
volatility to readily evaporate from the printable lithium
composition (e.g., in slurry form) to provide drying of the
printable lithium composition (slurry) after application.
[0031] The components of the printable lithium composition may be
mixed together as a slurry or paste to have a high concentration of
solid. Thus the slurry/paste may be in the form of a concentrate
with not all of the solvent necessarily added prior to the time of
depositing or applying. In one embodiment, the lithium metal powder
should be uniformly suspended in the solvent so that when applied
or deposited a substantially uniform distribution of lithium metal
powder is deposited or applied. Dry lithium powder may be dispersed
such as by agitating or stirring vigorously to apply high sheer
forces.
[0032] In another embodiment, a mixture of the polymer binder,
rheology modifier, coating reagents, and other potential additives
for the lithium metal powder may be formed and introduced to
contact the lithium droplets during the dispersion at a temperature
above the lithium melting point, or at a lower temperature after
the lithium dispersion has cooled such as described in U.S. Pat.
No. 7,588,623 the disclosure of which is incorporated by reference
in its entirety. The thusly modified lithium metal may be
introduced in a crystalline form or in a solution form in a solvent
of choice. It is understood that combinations of different process
parameters could be used to achieve specific coating and lithium
powder characteristics for particular applications.
[0033] Conventional pre-lithiation surface treatments require
compositions having very low binder content and very high lithium;
for example, see U.S. Pat. No. 9,649,688 the disclosure of which is
incorporated by reference in its entirety. However, embodiments of
the printable lithium composition in accordance with the present
invention can accommodate higher binder ratios, including up to 20
percent on dry basis. Various properties of the printable lithium
composition, such as viscosity and flow, may be modified by
increasing the binder and modifier content up to 50% dry basis
without loss of electrochemical activity of lithium. Increasing the
binder content facilitates the loading of the printable lithium
composition and the flow during printing. For example, in one
embodiment the printable lithium composition comprises about 70%
lithium metal powder and about 30% polymer binder and rheology
modifiers. In another embodiment, the printable lithium composition
may comprise about 85% lithium metal powder and about 15% polymer
binder and rheology modifiers.
[0034] An important aspect of printable lithium compositions is the
rheological stability of the suspension. Because lithium metal has
a low density of 0.534 g/cc, it is difficult to prevent lithium
powder from separating from solvent suspensions. By selection of
lithium metal powder loading, polymer binder and conventional
modifier types and amounts, viscosity and rheology may be tailored
to create the stable suspension of the invention. A preferred
embodiment shows no separation at greater than 90 days. This can be
achieved by designing compositions with very high zero shear
viscosity in the range of 1.times.10.sup.4 cps to 1.times.10.sup.7
cps. It is however very important to the application process that
the compositions, when exposed to shear, exhibit viscosity
characteristics in the ranges claimed.
[0035] The resulting printable lithium composition preferably may
have a viscosity at 10s.sup.-1 about 20 to about 20,000 cps, and
often a viscosity of about 100 to about 10,000 cps. At such
viscosity, the printable lithium composition is a flowable
suspension or gel. The printable lithium composition preferably has
an extended shelf life at room temperature and is stable against
metallic lithium loss at temperatures up to 60.degree. C., often up
to 120.degree. C., and sometimes up to 180.degree. C. The printable
lithium composition may separate somewhat over time but can be
placed back into suspension by mild agitation and/or application of
heat.
[0036] In one embodiment, the printable lithium composition
comprises on a solution basis about 5 to 50 percent lithium metal
powder, about 0.1 to 20 percent polymer binder, about 0.1 to 30
percent rheology modifier and about 50 to 95 percent solvent. In
one embodiment, the printable lithium composition comprises on a
solution basis about 15 to 25 percent lithium metal powder, about
0.3 to 0.6 percent polymer binder having a molecular weight of
4,700,000, about 0.5 to 0.9 percent rheology modifier, and about 75
to 85 percent solvent. Typically, the printable lithium composition
is applied or deposited to a thickness of about 50 microns to 200
microns prior to pressing. After pressing, the thickness can be
reduced to between about 1 to 50 microns. Examples of pressing
techniques are described, for example, in U.S. Pat. Nos. 3,721,113
and 6,232,014 which are incorporated herein by reference in their
entireties.
[0037] In one embodiment, the printable lithium composition is
deposited or applied to an active anode material on a current
collector namely to form a prelithiated anode. Suitable active
anode materials include graphite and other carbon-based materials,
alloys such as tin/cobalt, tin/cobalt/carbon, silicon-carbon,
variety of silicone/tin based composite compounds, germanium-based
composites, titanium based composites, elemental silicon, and
germanium. The anode materials may be a foil, mesh or foam.
Application may be via spraying, extruding, coating, printing,
painting, dipping, and spraying, and are described in co-pending US
Patent Publication No.______ (Attorney Matter 073396.1183), filed
concurrently herewith and incorporated herein by reference in its
entirety.
[0038] In one embodiment, the active anode material and the
printable lithium composition are provided together and extruded
onto the current collector (e.g., copper, nickel, etc.). For
instance, the active anode material and printable lithium
composition may be mixed and co-extruded together. Examples of
active anode materials include graphite, graphite-SiO,
graphite-SnO, SiO, hard carbon and other lithium ion battery and
lithium ion capacitor anode materials. In another embodiment, the
active anode material and the printable lithium composition are
co-extruded to form a layer of the printable lithium composition on
the current collector. The deposition of the printable lithium
composition including the above extrusion technique may include
depositing as wide variety patterns (e.g., dots, stripes),
thicknesses, widths, etc. For example, the printable lithium
composition and active anode material may be deposited as a series
of stripes, such as described in US Publication No. 2014/0186519
incorporated herein by reference in its entirety. The stripes would
form a 3D structure that would account for expansion of the active
anode material during lithiation. For example, silicon may expand
by 300 to 400 percent during lithiation. Such swelling potentially
adversely affects the anode and its performance. By depositing the
printable lithium as a thin stripe in the Y-plane as an alternating
pattern between the silicon anode stripes, the silicon anode
material can expand in the X-plane alleviating electrochemical
grinding and loss of particle electrical contact. Thus, the
printing method can provide a buffer for expansion. In another
example, where the printable lithium formulation is used to form
the anode, it could be co-extruded in a layered fashion along with
the cathode and separator, resulting in a solid-state battery.
[0039] In one embodiment, the printable lithium composition may be
used to pre-lithiate an anode as described in U.S. Pat. No.
9,837,659 herein incorporated by reference in its entirety. For
example, the method includes disposing a layer of printable lithium
composition adjacent to a surface of a pre-fabricated/pre-formed
anode. The pre-fabricated electrode comprises an electroactive
material. In certain variations, the printable lithium composition
may be applied to the carrier/substrate via a deposition process. A
carrier substrate on which the layer of printable lithium
composition may be disposed may be selected from the group
consisting of: polymer films (e.g., polystyrene, polyethylene,
polyethyleneoxide, polyester, polypropylene,
polypolytetrafluoroethylene), ceramic films, copper foil, nickel
foil, or metal foams by way of non-limiting example. Heat may then
be applied to the printable lithium composition layer on the
substrate or the pre-fabricated anode. The printable lithium
composition layer on the substrate or the pre-fabricated anode may
be further compressed together, under applied pressure. The
heating, and optional applied pressure, facilitates transfer of
lithium onto the surface of the substrate or anode. In case of
transfer to the pre-fabricated anode, pressure and heat can result
in mechanical lithiation, especially where the pre-fabricated anode
comprises graphite. In this manner, lithium transfers to the
electrode and due to favorable thermodynamics is incorporated into
the active material.
[0040] In additional embodiments, at least a portion of the
printable lithium composition can be supplied to the anode active
material prior to assembly of the battery. In other words, the
anode can comprise partially lithium-loaded silicon-based active
material, in which the partially loaded active material has a
selected degree of loading of lithium through
intercalation/alloying or the like.
[0041] In one embodiment, the printable lithium composition may be
incorporated into a three-dimensional electrode structure as
described in US Publication No. 2018/0013126 herein incorporated by
reference in its entirety. For example, the printable lithium
composition may be incorporated into a three-dimensional porous
anode, porous current collector or porous polymer or ceramic film,
wherein the printable lithium composition may be deposited
therein.
[0042] In some embodiments, an electrode prelithiated with the
printable lithium composition can be assembled into a cell with the
electrode to be preloaded with lithium. A separator can be placed
between the respective electrodes. Current can be allowed to flow
between the electrodes. For example, an anode prelithiated with the
printable lithium composition of the present invention may be
formed into a second battery such as described in U.S. Pat. No.
6,706,447 herein incorporated by reference in its entirety.
[0043] The cathode is formed of an active material, which is
typically combined with a carbonaceous material and a binder
polymer. The active material used in the cathode is preferably a
material that can be lithiated. Preferably, non-lithiated materials
such as MnO.sub.2, V.sub.2O.sub.5, MoS.sub.2, metal fluorides or
mixtures thereof, Sulphur and sulfur composites can be used as the
active material. However, lithiated materials such as
LiMn.sub.2O.sub.4 and LiMO.sub.2 wherein M is Ni, Co or Mn that can
be further lithiated can also be used. The non-lithiated active
materials are preferred because they generally have higher specific
capacities, lower cost and broader choice of cathode materials in
this construction that can provide increased energy and power over
conventional secondary batteries that include lithiated active
materials.
EXAMPLES
Example 1
[0044] 10 g of solution styrene butadiene rubber (S-SBR Europrene
Sol R 72613) is dissolved in 90 g toluene (99% anhydrous, Sigma
Aldrich) by stirring at 21.degree. C. for 12 hours. 6 g of the 10
wt % SBR (polymer binder) in toluene (solvent) is combined with 0.1
g carbon black (Timcal Super P) (rheology modifier) and 16 g of
toluene and dispersed in a Thinky ARE 250 planetary mixer for 6
minutes at 2000 rpm. 9.3 g of stabilized lithium metal powder
(SLMP.RTM., Livent Corp.) having polymer coating of 20 to 200 .mu.m
and d50 of 20 .mu.m is added to this suspension and dispersed for 3
minutes at 1000 rpm in a Thinky mixer. The printable lithium is
then filtered through 180 .mu.m opening stainless steel mesh. The
printable lithium suspension is then doctor blade coated on to a
copper current collector at a wet thickness of 2 mil (.about.50
.mu.m). FIG. 3 is a plot showing the cycle performance for a pouch
cell with printable lithium derived thin lithium film as the anode
vs. commercial thin lithium foil.
[0045] Example 2
[0046] 10 g of 135,000 molecular weight ethylene propylene diene
terpolymer (EPDM) (Dow Nordel IP 4725P) is dissolved in 90 g
p-xylene (99% anhydrous, Sigma Aldrich) by stirring at 21.degree.
C. for 12 hours. 6 g of the 10 wt % EPDM (polymer binder) in
p-xylene (solvent) is combined with 0.1 g TiO2 (Evonik Industries)
(rheology modifier) and 16 g of toluene and dispersed in a Thinky
ARE 250 planetary mixer for 6 minutes at 2000 rpm. 9.3 g of
stabilized lithium metal powder (SLMP.RTM., Livent Corp.) having
polymer coating of 20 to 200 .mu.m and d50 of 20 .mu.m is added to
this suspension and dispersed for 3 minutes at 1000 rpm in a Thinky
mixer. The printable lithium is then filtered through 180 .mu.m
opening stainless steel mesh. The printable lithium composition is
then doctor blade coated on to a copper current collector at a wet
thickness of 2 mil (.about.50 .mu.m).
Shelf Life Stability
[0047] Printable lithium components must be selected to ensure
chemical stability for long shelf life at room temperature and
stability at elevated temperature for shorter durations such as
during transport or during the drying process. The printable
lithium composition stability was tested using calorimetry. 1.5 g
SLMP was added to a 10 ml volume Hastelloy ARC bomb sample
container. 2.4 g of 4% SBR binder solution was added to the
container. The container was fitted with a 24-ohm resistance heater
and a thermocouple to monitor and control sample temperature. The
bomb sample set-up was loaded into a 350 ml containment vessel
along with insulation. An Advance Reactive Screening Systems Tool
calorimeter by Fauske Industries was used to assess the
compatibility of the printable lithium solutions during a constant
rate temperature ramp to 190.degree. C. The temperature ramp rate
was 2.degree. C./min and the sample temperature was held at
190.degree. C. for 60 minutes. The test was conducted under 200 psi
Argon pressure to prevent boiling of the solvent. FIG. 2 shows the
temperature and pressure profiles for the reactivity testing of a
SLMP/styrene butadiene/toluene printable lithium composition.
Printing Performance
[0048] The quality of the printable lithium composition with regard
to printability is measured by several factors, for example,
consistency of flow which directly impact one's ability to control
lithium loading on a substrate or an electrode surface. An
effective means of measuring flow is Flow Conductance which is an
expression of the loading per square centimeter in relation to the
factors which control the loading--the pressure during extrusion
and the speed of the printer head. It can most simply be thought of
as the inverse of flow resistance.
[0049] The expression is used to allow comparisons between prints
of varying pressures and speeds, and changes in Flow Conductance
can alert one to non-linear relationships of flow with pressure.
These are important for scaling the loading for a printable lithium
up or down depending on the need of the anode or cathode. An ideal
printable lithium composition would behave in a linear fashion to
changes in extrusion pressure.
[0050] To test printability, a printable lithium composition is
filtered through 180 .mu.m opening stainless steel mesh and loaded
into a Nordson EFD 10 ml syringe. The syringe is loaded into a
Nordson EFD HP4x syringe dispenser and attached to a slot die print
head. The slot die print head is equipped with a 100 .mu.m-300
.mu.m thick shim with channel openings designed to deliver the
desired printable lithium composition loading. The slot die head is
mounted on a Loctite 300 Series robot. The print head speed is set
to 200 mm/s and the printing pressure is between 20 and 200 psi
argon, depending on shim and channel design. The print length is 14
cm. In an example printing trial experiment, the printable lithium
composition was printed 30 times from a single syringe at dispenser
settings ranging from 80 psi to 200 psi. For this print trial
experiment, the flow conductance average was
0.14 .times. mg s * cm 2 * lb .times. .times. f in 2
##EQU00001##
with standard deviation of 0.02. Although this printable
composition does not behave in a perfectly linear fashion, the
composition flow response to changes in dispenser pressure is
predictable to allow one skilled in the art to fine tune lithium
loading to the desired level. Thus, at fixed dispenser pressure
conditions the loading of lithium can be controlled very
consistently. For example, for a print of
0.275 .times. m .times. .times. Ah c .times. .times. m 2
##EQU00002##
lithium metal, the CV is about 5%.
Electrochemical Testing
[0051] The pre-lithiation effect of printable lithium composition
can be evaluated by printing the required amount of printable
lithium onto the surface of prefabricated electrodes. The
pre-lithiation lithium amount is determined by testing the anode
material in half-cell format and calculating the lithium required
to compensate for the first cycle losses due to formation of SEI,
or other side reactions. To calculate the necessary amount of
printable lithium, the capacity as lithium metal of the composition
must be known and is approximately 3600 mAh/g dry lithium basis for
the compositions used as examples.
[0052] The pre-lithiation effect is tested using Graphite-SiO/NCA
pouch cells. The Graphite-SiO anode sheet has the following
formulation: artificial graphite (90.06%)+SiO (4.74%)+carbon black
(1.4%)+SBR/CMC (3.8%). The capacity loading of the electrode is
3.59 mAh/cm.sup.2 with 87% first cycle CE (columbic efficiency).
The printable lithium is applied onto a Graphite-SiO anode at 0.15
mg/cm.sup.2 lithium metal. The electrode is dried at 80.degree. C.
for 100 min followed by lamination at a roller gap approximately
75% of the thickness of the electrode. A 7 cm.times.7 cm electrode
is punched from the printable lithium treated anode sheet. The
positive electrode has the following formulation: NCA (96%)+carbon
black (2%)+PVdF (2%). The positive electrode is 6.8 cm.times.6.8 cm
with capacity loading of 3.37 mAh/cm.sup.2. The NCA cathode has 90%
first cycle CE. The anode to cathode capacity ratio is 1.06 and the
baseline for full cell first cycle CE is 77%. Single layer pouch
cells are assembled and 1M LiPF.sub.6/EC+DEC (1:1) is used as the
electrolyte. The cells are pre-conditioned for 12 hours at
21.degree. C. and then the formation cycle is conducted at
40.degree. C. The formation protocol is 0.1 C charge to 4.2V,
constant voltage to 0.01 C and 0.1 C discharge to 2.8V. In the
described test 89% first cycle CE was demonstrated.
[0053] Although the present approach has been illustrated and
described herein with reference to preferred embodiments and
specific examples thereof, it will be readily apparent to those of
ordinary skill in the art that other embodiments and examples may
perform similar functions and/or achieve like results. All such
equivalent embodiments and examples are within the spirit and scope
of the present approach.
* * * * *