U.S. patent application number 17/744314 was filed with the patent office on 2022-08-25 for battery electrode coatings applied by waterborne electrodeposition.
This patent application is currently assigned to PPG Industries Ohio, Inc.. The applicant listed for this patent is PPG Industries Ohio, Inc.. Invention is credited to Stuart D. Hellring, Chad A. Landis, Jacob W. Mohin, Landon J. Oakes, Kurt G. Olson.
Application Number | 20220271269 17/744314 |
Document ID | / |
Family ID | |
Filed Date | 2022-08-25 |
United States Patent
Application |
20220271269 |
Kind Code |
A1 |
Hellring; Stuart D. ; et
al. |
August 25, 2022 |
BATTERY ELECTRODE COATINGS APPLIED BY WATERBORNE
ELECTRODEPOSITION
Abstract
The present invention is directed towards a method of coating a
substrate comprising electrocoating an electrodepositable coating
composition onto the substrate, the electrodepositable coating
composition comprising a binder comprising a pH-dependent rheology
modifier; an electrochemically active material and/or an
electrically conductive agent; and an aqueous medium. Also
disclosed are electrodepositable coating compositions, coated
substrates and electrical storage devices.
Inventors: |
Hellring; Stuart D.;
(Pittsburgh, PA) ; Oakes; Landon J.; (Cambridge,
MA) ; Olson; Kurt G.; (Gibsonia, PA) ; Landis;
Chad A.; (Oakmont, PA) ; Mohin; Jacob W.;
(Gibsonia, PA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
PPG Industries Ohio, Inc. |
Cleveland |
OH |
US |
|
|
Assignee: |
PPG Industries Ohio, Inc.
Cleveland
OH
|
Appl. No.: |
17/744314 |
Filed: |
May 13, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16227320 |
Dec 20, 2018 |
11355741 |
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17744314 |
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International
Class: |
H01M 4/131 20060101
H01M004/131; H01M 4/04 20060101 H01M004/04; H01M 4/1391 20060101
H01M004/1391; H01M 4/62 20060101 H01M004/62 |
Claims
1. A method of coating a substrate comprising: electrocoating an
electrodepositable coating composition onto at least a portion of
the substrate, wherein the electrodepositable coating composition
comprises: a binder comprising a pH-dependent rheology modifier; an
electrochemically active material and/or an electrically conductive
agent; and an aqueous medium.
2. The method of claim 1, wherein the pH-dependent rheology
modifier comprises an alkali-swellable rheology modifier, a
hydrophobically modified alkali-swellable rheology modifier.
3. The method of claim 2, wherein a composition of water and the
alkali-swellable rheology modifier at 4.25% by weight of the total
composition has an increase in viscosity of at least 500 cps over
an increase in pH value of 3 pH units within the pH range of 3 to
12, as measured using a Brookfield viscometer using a #4 spindle
and operated at 20 RPMs.
4. The method of claim 2, wherein the alkali-swellable rheology
modifier comprises a crosslinked alkali-swellable rheology
modifier.
5. The method of claim 4, wherein the crosslinked alkali-swellable
rheology modifier comprises constitutional units comprising the
residue of a monoethylenically unsaturated carboxylic acid, a
C.sub.1 to C.sub.6 alkyl (meth)acrylate monomer, and a cros
slinking monomer.
6. The method of claim 5, wherein the crosslinked alkali-swellable
rheology modifier comprises constitutional units comprising the
residue of: 20 to 65% by weight of the monoethylenically
unsaturated carboxylic acid; 20 to 80% by weight of the C.sub.1 to
C.sub.6 alkyl (meth)acrylate monomer; and 0.1 to 3% by weight of
the crosslinking monomer, based on the total weight of the
crosslinked alkali-swellable rheology modifier.
7. The method of claim 4, wherein the crosslinked hydrophobically
modified alkali-swellable rheology modifier comprises
constitutional units comprising the residue of a monoethylenically
unsaturated carboxylic acid, a C.sub.1 to C.sub.6 alkyl
(meth)acrylate monomer, and a monoethylenically unsaturated alkyl
alkoxylate monomer.
8. The method of claim 7, wherein the hydrophobically modified
alkali-swellable rheology modifier comprises constitutional units
comprising the residue of: 2 to 70% by weight of the
monoethylenically unsaturated carboxylic acid; 20 to 80% by weight
of the C.sub.1 to C.sub.6 alkyl (meth)acrylate monomer; and 0.5 to
60% by weight of the monoethylenically unsaturated alkyl alkoxylate
monomer, based on the total weight of the hydrophobically modified
alkali-swellable rheology modifier.
9. The method of claim 1, wherein the pH-dependent rheology
modifier comprises an acid-swellable rheology modifier.
10. The method of claim 1, wherein the binder further comprises a
non-fluorinated organic film-forming polymer.
11. The method of claim 10, wherein the non-fluorinated organic
film-forming polymer comprises polysaccharides, polyacrylates,
polyethylene, polystyrene, polyvinyl alcohol, poly (methyl
acrylate), poly (vinyl acetate), polyacrylonitrile, polyimide,
polyurethane, polyvinyl butyral, polyvinyl pyrrolidone, styrene
butadiene rubber, xanthan gum, or combinations thereof.
12. The method of claim 1, wherein the electrochemically active
material comprises LiCoO.sub.2, LiNiO.sub.2, LiFePO.sub.4,
LiFeCoPO.sub.4, LiCoPO.sub.4, LiMnO.sub.2, LiMn.sub.2O.sub.4,
Li(NiMnCo)O.sub.2, Li(NiCoAl)O.sub.2, carbon-coated LiFePO.sub.4,
sulfur, LiO.sub.2, FeF.sub.2 and FeF.sub.3, Si, aluminum, tin,
SnCo, Fe.sub.3O.sub.4, or combinations thereof.
13. The method of claim 1, wherein the electrochemically active
material comprises graphite, lithium titanate, lithium vanadium
phosphate, silicon, silicon compounds, tin, tin compounds, sulfur,
sulfur compounds, lithium metal, graphene, or a combination
thereof.
14. The method of claim 1, wherein the electrically conductive
agent comprises conductive carbon black, carbon nanotubes,
graphene, graphite, carbon fibers, fullerenes, and combinations
thereof.
15. The method of claim 1, further comprising a crosslinking
agent.
16. The method of claim 15, wherein the crosslinking agent
comprises carbodiimide.
17. The method of claim 15, wherein the electrodepositable coating
composition comprises: (a) 0.1% to 10% by weight of the
pH-dependent rheology modifier; (b) 0.02% to 2% by weight of the
crosslinking agent; (c) 45% to 99% by weight of the
electrochemically active material; (d) optionally 0.5% to 20% by
weight of the electrically conductive agent; and (e) optionally
0.1% to 9.9% by weight of a non-fluorinated organic film-forming
polymer; the % by weight based on the total solids weight of the
electrodepositable composition.
18. The method of claim 1, wherein the VOC of the
electrodepositable coating composition is no more than 500 g/L.
19. The method of claim 1, wherein a coating produced on a
substrate by the method of claim 1 has a 90.degree. peel strength
at least 10% greater than a coating produced from a comparative
coating composition at a similar mass loading that is not applied
by electrodeposition, the 90.degree. peel strength measured
according to PEEL STRENGTH TEST METHOD.
20. The method of claim 1, wherein the electrodepositable coating
composition is substantially free of fluoropolymer.
21. The method of claim 1, wherein the electrodepositable coating
composition is substantially free of cellulose-based materials.
22. The method of claim 1, wherein the pH-dependent rheology
modifier is substantially free of amide, glycidyl and hydroxyl
groups.
23. The method of claim 1, wherein the pH-dependent rheology
modifier is substantially free of the residue of constitutional
units comprising aromatic vinyl monomers.
24. A coated substrate comprising an electrical current collector
and a coating formed on at least a portion of the electrical
current collector according to the method of claim 1.
25. The coated substrate of claim 24, wherein the electrical
current collector comprises aluminum, copper, steel, stainless
steel, nickel, conductive carbon, a conductive primer coating, or a
porous polymer.
26. The coated substrate of claim 24, wherein the coated substrate
comprises a positive electrode.
27. The coated substrate of claim 24, wherein the coated substrate
comprises a negative electrode.
28. An electrical storage device comprising: (a) an electrode
comprising the coated substrate of claim 24; (b) a
counter-electrode, and (c) an electrolyte.
29. The electrical storage device of claim 28, wherein the
electrical storage device comprises a cell, a battery pack, a
secondary battery, a capacitor, or a supercapacitor.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 16/227,320 entitled "BATTERY ELECTRODE
COATINGS APPLIED BY WATERBORNE ELECTRODEPOSITION", filed Dec. 20,
2018, and published as Publication Number 2020/0203707, which is
incorporated herein by reference in its entirety.
FIELD OF THE INVENTION
[0002] The present invention is directed towards electrodepositable
coating compositions and battery electrode coatings applied by
waterborne electrodeposition.
BACKGROUND INFORMATION
[0003] There is a trend in the electronics industry to produce
smaller devices, powered by smaller and lighter batteries.
Batteries with a negative electrode--such as a carbonaceous
material, and a positive electrode--such as lithium metal oxides
can provide relatively high power and low weight. Binders for
producing such electrodes are usually combined with the negative
electrode or positive electrode in the form of a solventborne or
waterborne slurry. The solventborne slurries present safety, health
and environmental dangers. Many organic solvents are toxic and
flammable, volatile in nature, carcinogenic and involve special
manufacturing controls to mitigate risk and reduce environmental
pollution, and the waterborne slurries have oftentimes produced
unsatisfactory electrodes having poor adhesion and/or poor battery
performance. Once applied, the bound ingredients are able to
tolerate large volume expansion and contraction during charge and
discharge cycles without losing interconnectivity within the
electrodes. Interconnectivity of the active ingredients in an
electrode is extremely important in battery performance, especially
during charging and discharging cycles, as electrons must move
through the electrode, and lithium ion mobility requires
interconnectivity within the electrode between particles. Improved
battery performance and adhesion of the coating to the electrical
current collector are desired, particularly without the use of
carcinogenic materials and environmental pollution.
SUMMARY OF THE INVENTION
[0004] Disclosed herein is an electrodepositable coating
composition comprising a binder comprising a pH-dependent rheology
modifier comprising the residue of a crosslinking monomer and/or a
monoethylenically unsaturated alkylated alkoxylate monomer; an
electrochemically active material and/or an electrically conductive
agent; and an aqueous medium.
[0005] Also disclosed herein is a method of coating a substrate
comprising electrocoating an electrodepositable coating composition
onto the substrate, the electrodepositable coating composition
comprising a binder comprising a pH-dependent rheology modifier; an
electrochemically active material and/or an electrically conductive
agent; and an aqueous medium.
[0006] Further disclosed herein are coated substrates and
electrical storage devices.
DETAILED DESCRIPTION OF THE INVENTION
[0007] As stated above, the present invention is directed to an
electrodepositable coating composition comprising a binder
comprising a pH-dependent rheology modifier comprising the residue
of a crosslinking monomer and/or a monoethylenically unsaturated
alkylated ethoxylate monomer; an electrochemically active material
and/or an electrically conductive agent; and an aqueous medium.
[0008] According to the present invention, the term
"electrodepositable coating composition" refers to a composition
that is capable of being deposited onto an electrically conductive
substrate under the influence of an applied electrical
potential.
[0009] According to the present invention, the electrodepositable
coating composition comprises a binder. The binder serves to bind
together particles of the electrodepositable coating composition,
such as the electrochemically active material, the electrically
conductive agent or both, upon electrodeposition of the coating
composition onto a substrate. The binder comprises a film-forming
polymer and optionally may further comprise a crosslinking agent
that comprises functional groups reactive with functional groups
present on the film-forming polymer. The film-forming polymer and
crosslinking agent may comprise organic compounds.
[0010] According to the present invention, the film-forming polymer
of the binder comprises a pH-dependent rheology modifier. The
pH-dependent rheology modifier may comprise a portion of or all of
the film-forming polymer and/or binder. As used herein, the term
"pH-dependent rheology modifier" refers to an organic compound,
such as a polymer, that has a variable rheological effect based
upon the pH of the composition. The pH-dependent rheology modifier
may affect the viscosity of the composition on the principle of
significant volume changes of the pH-dependent rheology modifier
induced by changes in the pH of the composition. For example, the
pH-dependent rheology modifier may be soluble at a pH range and
provide certain rheological properties and may be insoluble and
coalesce at a critical pH value (and above or below based upon the
type of pH-dependent rheology modifier) which causes a reduction in
the viscosity of the composition due to a reduction in the volume
of the rheology modifier. The relationship between the pH of the
composition and viscosity due to the presence of the pH-dependent
rheology modifier may be non-linear. The pH-dependent rheology
modifier may comprise an alkali-swellable rheology modifier or an
acid swellable rheology modifier, depending upon the type of
electrodeposition that the electrodepositable coating composition
is to be employed. For example, alkali-swellable rheology modifiers
may be used for anionic electrodeposition, whereas acid swellable
rheology modifiers may be used for cathodic electrodeposition.
[0011] As used herein, the term "alkali-swellable rheology
modifier" refers to a rheology modifier that increases the
viscosity of a composition (i.e., thickens the composition) as the
pH of the composition increases. The alkali-swellable rheology
modifier may increase viscosity at a pH of about 2.5 or greater,
such as about 3 or greater, such as about 3.5 or greater, such as
about 4 or greater, such as about 4.5 or greater, such as about 5
or greater.
[0012] Non-limiting examples of alkali-swellable rheology modifiers
include alkali-swellable emulsions (ASE), hydrophobically modified
alkali-swellable emulsions (HASE), star polymers, and other
materials that provide pH-triggered rheological changes at low pH,
such as the pH values described herein. The alkali-swellable
rheology modifiers may comprise addition polymers having
constitutional units comprising the residue of ethylenically
unsaturated monomers. For example, the alkali-swellable rheology
modifiers may comprise addition polymers having constitutional
units comprising, consisting essentially of, or consisting of the
residue of: (a) 2 to 70% by weight of a monoethylenically
unsaturated carboxylic acid, such as 20 to 70% by weight, such as
25 to 55% by weight, such as 35 to 55% by weight, such as 40 to 50%
by weight, such as 45 to 50% by weight; (b) 20 to 80% by weight of
a C.sub.1 to C.sub.6 alkyl (meth)acrylate, such as 35 to 65% by
weight, such as 40 to 60% by weight, such as 40 to 50% by weight,
such as 45 to 50% by weight; and at least one of (c) 0 to 3% by
weight of a crosslinking monomer, such as 0.1 to 3% by weight, such
as 0.1 to 2% by weight; and/or (d) 0 to 60% by weight of a
monoethylenically unsaturated alkyl alkoxylate monomer, such as 0.5
to 60% by weight, such as 10 to 50% by weight, the % by weight
being based on the total weight of the addition polymer. The ASE
rheology modifiers may comprise (a) and (b) and may optionally
further comprise (c), and the HASE rheology modifiers may comprise
(a), (b) and (d), and may optionally further comprise (c). When (c)
is present, the pH-dependent rheology modifier may be referred to
as a crosslinked pH-dependent rheology modifier. When the acid
groups have a high degree of protonation (i.e., are un-neutralized)
at low pH, the rheology modifier is insoluble in water and does not
thicken the composition, whereas when the acid is substantially
deprotonated (i.e., substantially neutralized) at higher pH values,
the rheology modifier becomes soluble or dispersible (such as
micelles or microgels) and thickens the composition.
[0013] The (a) monoethylenically unsaturated carboxylic acid may
comprise a C3 to C8 monoethylenically unsaturated carboxylic acid
such as acrylic acid, methacrylic acid, and the like, as well as
combinations thereof.
[0014] The (b) C.sub.1 to C.sub.8 alkyl (meth)acrylate may comprise
a C.sub.1 to C.sub.6 alkyl (meth)acrylate, such as a C.sub.1 to
C.sub.4 alkyl (meth)acrylate. The C.sub.1 to C.sub.8 alkyl
(meth)acrylate may comprise a non-substituted C.sub.1 to C.sub.8
alkyl (meth)acrylate such as, for example, methyl (meth)acrylate,
ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl
(meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate,
pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl
(meth)acrylate, heptyl (meth)acrylate, isoheptyl (meth)acrylate,
2-ethylhexyl (meth)acrylate, or combinations thereof.
[0015] The (c) crosslinking monomer may comprise a
polyethylenically unsaturated monomer such as ethylene glycol
di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, divinylbenzene,
trimethylolpropane diallyl ether, tetraallyl pentaerythritol,
triallyl pentaerythritol, diallyl pentaerythritol, diallyl
phthalate, triallyl cyanurate, bisphenol A diallyl ether, methylene
bisacrylamide, allyl sucroses, and the like, as well as
combinations thereof.
[0016] The (d) monoethylenically unsaturated alkylated ethoxylate
monomer may comprise a monomer having a polymerizable group, a
hydrophobic group and a bivalent polyether group of a poly(alkylene
oxide) chain, such as a poly(ethylene oxide) chain having about
5-150 ethylene oxide units, such as 6-10 ethylene oxide units, and
optionally 0-5 propylene oxide units. The hydrophobic group is
typically an alkyl group having 6-22 carbon atoms (such as a
dodecyl group) or an alkaryl group having 8-22 carbon atoms (such
as octyl phenol). The bivalent polyether group typically links the
hydrophobic group to the polymerizable group. Examples of the
bivalent polyether group linking group and hydrophobic group are a
bicycloheptyl-polyether group, a bicycloheptenyl-polyether group or
a branched C.sub.5-C.sub.50 alkyl-polyether group, wherein the
bicycloheptyl-polyether or bicycloheptenyl-polyether group may
optionally be substituted on one or more ring carbon atoms by one
or two C.sub.1-C.sub.6 alkyl groups per carbon atom.
[0017] In addition to the monomers described above, the
pH-dependent rheology modifier may comprise other ethylenically
unsaturated monomers. Examples thereof include substituted alkyl
(meth)acrylate monomers substituted with functional groups such as
hydroxyl, amino, amide, glycidyl, thiol, and other functional
groups; alkyl (meth)acrylate monomers containing fluorine; aromatic
vinyl monomers; and the like. Alternatively, the pH-dependent
rheology modifier may be substantially free, essentially free, or
completely free of such monomers. As used herein, a pH-dependent
rheology modifier is substantially free or essentially free of a
monomer when constitutional units of that monomer are present, if
at all, in an amount of less than 0.1% by weight or less than 0.01%
by weight, respectively, based on the total weight of the
pH-dependent rheology modifier.
[0018] The pH-dependent rheology modifier may be substantially
free, essentially free, or completely free of amide, glycidyl or
hydroxyl functional groups. As used herein, a pH-dependent rheology
modifier is substantially free or essentially free of amide,
glycidyl or hydroxyl functional groups if such groups are present,
if at all, in an amount of less than 1% or less than 0.1% based on
the total number of functional groups present in the pH-dependent
rheology modifier.
[0019] The pH-dependent rheology modifier may comprise, consist
essentially of, or consist of constitutional units of the residue
of methacrylic acid, ethyl acrylate and a cros slinking monomer,
present in the amounts described above.
[0020] The pH-dependent rheology modifier may comprise, consist
essentially of, or consist of constitutional units of the residue
of methacrylic acid, ethyl acrylate and a monoethylenically
unsaturated alkyl alkoxylate monomer, present in the amounts
described above.
[0021] The pH-dependent rheology modifier may comprise, consist
essentially of, or consist of methacrylic acid, ethyl acrylate, a
cros slinking monomer and a monoethylenically unsaturated alkyl
alkoxylate monomer, present in the amounts described above.
[0022] Commercially available pH-dependent rheology modifiers
include alkali-swellable emulsions such as ACRYSOL ASE-60,
hydrophobically modified alkali-swellable emulsions such as ACRYSOL
HASE TT-615, and ACRYSOL DR-180 HASE, each of which is available
from the Dow Chemical Company, and star polymers, including those
produced by atom transfer radical polymerization, such as
fracASSIST.RTM. prototype 2 from ATRP Solutions.
[0023] Exemplary viscosity data showing the impact of the
alkali-swellable rheology modifier across a range of pH values of a
composition was obtained for some non-limiting examples of
alkali-swellable rheology modifiers using a Brookfield viscometer
operated at 20 RPMs and using a #4 spindle. The alkali-swellable
rheology modifiers ACRYSOL ASE-60, ACRYSOL HASE TT-615, and ACRYSOL
DR-180 HASE were characterized at 4.25% solids in a solution of
deionized water. A star polymer (fracASSIST.RTM. prototype 2) was
investigated at 0.81% solids due to the limited solubility of the
polymer at low pH. The pH was adjusted through the addition of
dimethyl ethanolamine ("DMEA"). The viscosity measurements in
centipoise (cps) across the range of pH values is provided below in
Table 1.
TABLE-US-00001 TABLE 1 Rheology Modifier ACRYSOL ACRYSOL fracASSIST
.RTM. ACRYSOL ASE-60 HASE-TT-615 prototype 2 DR-180 HASE Property
Viscos- Viscos- Viscos- Viscos- pH ity pH ity pH ity pH ity 3.53 0
4.24 0 4.04 0 4.30 0 6.31 2,010 5.90 454 6.09 2,274 6.10 90 6.43
19,280 6.40 15,600 7.23 2,352 6.20 11,160 6.77 19,130 7.04
Off-scale 7.68 1,914 7.13 Off-scale 7.42 17,760 -- -- 8.72 1,590 --
--
[0024] As shown in Table 1, a composition of water and an
alkali-swellable rheology modifier at 4.25% by weight of the total
composition may have an increase in viscosity of at least 500 cps
over an increase in pH value of 3 pH units within the pH range of 3
to 12, such as an increase of at least 1,000 cps, such as an
increase of at least 2,000 cps, such as an increase of at least
3,000 cps, such as an increase of at least 5,000 cps, such as an
increase of at least 7,000 cps, such as an increase of at least
8,000 cps, such as an increase of at least 9,000 cps, such as an
increase of at least 10,000 cps, such as an increase of at least
12,000 cps, such as an increase of at least 14,000 cps, or more.
For example, as shown for the ACRYSOL ASE-60 alkali-swellable
rheology modifier in Table 1, an increase in pH from about 3.5 to
about 6.5 results in an increase in the viscosity of the
composition of about 19,000 cps. A composition of water and an
alkali-swellable rheology modifier at 4.25% by weight of the total
composition may result in a corresponding decrease in the viscosity
of the composition over a corresponding decrease in pH value.
[0025] As shown in Table 1, a 4.25% by weight solution of the
alkali-swellable rheology modifier, the % by weight based on the
total weight of the solution, may have a viscosity increase of at
least 1,000 cps when measured from about pH 4 to about pH 7, such
as at least 1,500 cps, such as at least 1,900 cps, such as at least
5,000 cps, such as at least 10,000 cps, such as at least 15,000
cps, such as at least 17,000 cps, as measured using a Brookfield
viscometer using a #4 spindle and operated at 20 RPMs. A
composition of water and an alkali-swellable rheology modifier at
4.25% by weight of the total composition may result in a
corresponding decrease in the viscosity of the composition over a
corresponding decrease in pH value.
[0026] As shown in Table 1, a 4.25% by weight solution of the
alkali-swellable rheology modifier, the % by weight based on the
total weight of the solution, may have a viscosity increase of at
least 1,000 cps when measured from about pH 4 to about pH 6.5, such
as at least 1,500 cps, such as at least 1,900 cps, such as at least
5,000 cps, such as at least 10,000 cps, such as at least 15,000
cps, such as at least 17,000 cps, as measured using a Brookfield
viscometer using a #4 spindle and operated at 20 RPMs. A
composition of water and an alkali-swellable rheology modifier at
4.25% by weight of the total composition may result in a
corresponding decrease in the viscosity of the composition over a
corresponding decrease in pH value.
[0027] As shown in Table 1, a composition of water and an
alkali-swellable rheology modifier of a star polymer at 0.81% by
weight of the total composition may have a viscosity increase of at
least 400 cps when measured from about pH 4 to about pH 6.5, such
as at least 600 cps, such as at least 800 cps, such as at least
1,000 cps, such as at least 1,200 cps, such as at least 1,400 cps,
such as at least 2,000 cps, such as at least 2,200 cps, as measured
using a Brookfield viscometer using a #4 spindle and operated at 20
RPMs.
[0028] As used herein, the term "star polymer" refers to branched
polymers with a general structure consisting of several (three or
more) linear chains connected to a central core. The core of the
polymer can be an atom, molecule, or macromolecule; the chains, or
"arms", may include variable-length organic chains. Star-shaped
polymers in which the arms are all equivalent in length and
structure are considered homogeneous, and ones with variable
lengths and structures are considered heterogeneous.
[0029] As used herein, the term "acid-swellable rheology modifier"
refers to a rheology modifier that is insoluble at high pH and does
not thicken the composition and is soluble at lower pH and thickens
the composition. The acid-swellable rheology modifier may increase
viscosity at a pH of about 4 or less, such as about 4.5 or less,
such as about 5 or less, such as about 6 or less.
[0030] The pH-dependent rheology modifier may be present in the
electrodepositable coating composition in an amount of at least 10%
by weight, such as at least 20% by weight, such as at least 30% by
weight, such as at least 40%, such as at least 50% by weight, such
as at least 60% by weight, such as at least 70% by weight, such as
at least 75% by weight, such as at least 80% by weight, such as at
least 85% by weight, such as at least 90% by weight, such as at
least 93% by weight, such as at least 95% by weight, such as 100%
by weight, and may be present in an amount of no more than 100% by
weight, such as no more than 99% by weight, such as no more than
95% by weight, such as no more than 93% by weight, based on the
total solids weight of the binder solids. The pH-dependent rheology
modifier may be present in the electrodepositable coating
composition in an amount of 10% to 100% by weight, such as 20% to
100% by weight, such as 30% to 100% by weight, 40% to 100% by
weight, 50% to 100% by weight, 60% to 100% by weight, 70% to 100%
by weight, 75% to 100% by weight, 80% to 100% by weight, 85% to
100% by weight, 90% to 100% by weight, 93% to 100% by weight, 95%
to 100% by weight, such as 50% to 99% by weight, such as 75% to 95%
by weight, such as 87% to 93% by weight, based on the total solids
weight of the binder solids.
[0031] The pH-dependent rheology modifier may be present in the
electrodepositable coating composition in an amount of at least
0.1% by weight, such as at least 0.2% by weight, such as at least
0.3% by weight, such as at least 1% by weight, such as at least
1.5% by weight, such as at least 2% by weight, and may be present
in an amount of no more than 10% by weight, such as no more than 5%
by weight, such as no more than 4.5% by weight, such as no more
than 4% by weight, such as no more than 3% by weight, such as no
more than 2% by weight, such as no more than 1% by weight, based on
the total solids weight of the electrodepositable coating
composition. The pH-dependent rheology modifier may be present in
the electrodepositable coating composition in an amount of 0.1% to
10% by weight, such as 0.2% to 10% by weight, such as 0.3% to 10%
by weight, such as 1% to 7% by weight, such as 1.5% to 5% by
weight, such as 2% to 4.5% by weight, such as 3% to 4% by weight,
based on the total solids weight of the electrodepositable coating
composition.
[0032] It has been surprisingly discovered that the use of the
pH-dependent rheology modifier in the electrodepositable coating
composition in the amounts herein allows for the production of
electrodes by electrodeposition. Comparable electrodepositable
coating compositions that do not include the pH-dependent rheology
modifier were not able to produce electrodes by electrodeposition.
Without intending to be bound by any theory, it is believed that
the pH dependence of the rheology modifier assists in the
electrodeposition of the electrodepositable coating composition
because the significant difference in pH of the electrodeposition
bath at the surface of the electrode to be coated relative to the
rest of the electrodeposition bath causes the pH-dependent rheology
modifier to undergo a significant reduction in volume at or in
close proximity to the surface of the electrode to be coated
inducing coalescence of the pH-dependent rheology modifier and
other components of the electrodepositable coating composition on
the surface of the electrode to be coated. For example, the pH at
the surface of the anode in anodic electrodeposition is
significantly reduced relative to the rest of the deposition bath.
Likewise, the pH at the surface cathode in cathodic
electrodeposition is significantly higher than the rest of the
electrodeposition bath. The difference in pH at the surface of the
electrode to be coated during electrodeposition relative to the
electrodepositable bath in a static state may be at least 6 units,
such as at least 7 units, such as at least 8 units.
[0033] The pH of the electrodepositable coating composition will
depend upon the type of electrodeposition in which the composition
is to be used, as well as additives, such as pigments, fillers, and
the like, included in the electrodepositable coating composition.
For example, an anionic electrodepositable coating composition may
have a pH from about 6 to about 12, such as about 6.5 to about 11,
such as about 7 to about 10.5. In contrast, a cationic
electrodepositable coating composition may have a pH from about 4.5
to about 10, such as about 4.5 to about 5.5, such as about 8 to
about 9.5.
[0034] According to the present invention, the electrodepositable
coating composition further comprises an aqueous medium comprising
water. As used herein, the term "aqueous medium" refers to a liquid
medium comprising more than 50% by weight water, based on the total
weight of the aqueous medium. Such aqueous mediums may comprise
less than 50% by weight organic solvent, or less than 40% by weight
organic solvent, or less than 30% by weight organic solvent, or
less than 20% by weight organic solvent, or less than 10% by weight
organic solvent, or less than 5% by weight organic solvent, or less
than 1% by weight organic solvent, or less than 0.8% by weight
organic solvent, or less than 0.1% by weight organic solvent, based
on the total weight of the aqueous medium. Water comprises more
than 50% by weight of the aqueous medium, such as at least 60% by
weight, such as at least 70% by weight, such as at least 80% by
weight, such as at least 85% by weight, such as at least 90% by
weight, such as at least 95% by weight, such as at least 99% by
weight, such as at least 99.9% by weight, such as 100% by weight,
based on the total weight of the aqueous medium. Water may comprise
50.1% to 100% by weight, such as 70% to 100% by weight, such as 80%
to 100% by weight, such as 85% to 100% by weight, such as 90% to
100% by weight, such as 95% to 100% by weight, such as 99% to 100%
by weight, such as 99.9% to 100% by weight, based on the total
weight of the aqueous medium. The aqueous medium may further
comprise one or more organic solvent(s). Examples of suitable
organic solvents include oxygenated organic solvents, such as
monoalkyl ethers of ethylene glycol, diethylene glycol, propylene
glycol, and dipropylene glycol which contain from 1 to 10 carbon
atoms in the alkyl group, such as the monoethyl and monobutyl
ethers of these glycols. Examples of other at least partially
water-miscible solvents include alcohols such as ethanol,
isopropanol, butanol and diacetone alcohol. The electrodepositable
coating composition may in particular be provided in the form of a
dispersion, such as an aqueous dispersion.
[0035] Organic solvent is oftentimes added to a waterborne
formulation to modify viscosity within a desired range. The organic
solvent added to the electrodepositable coating composition, or
other waterborne formulation, may induce polymer swelling to
achieve viscosity modification. The use of pH-dependent rheology
modifiers described herein may allow for a reduction in the total
amount of organic solvent required to meet desired viscosity
targets to reduce the environmental impact of the compositions.
Accordingly, use of the pH-dependent rheology modifier as described
above in an electrodepositable coating composition may allow for
production of electrodepositable coating compositions having a
lower volatile organic content (VOC) than previously produced
waterborne formulations. As used herein, the term "volatile organic
content" or "VOC" refers to organic compounds having a boiling
point of less than 250.degree. C. As used herein, the term "boiling
point" refers to the boiling point of a substance at standard
atmospheric pressure of 101.325 kPa (1.01325 bar or 1 atm), also
referred to as the normal boiling point. The volatile organic
content includes volatile organic solvents. As used herein, the
term "volatile organic solvent" refers to organic compounds having
a boiling point of less than 250.degree. C., such as less than
200.degree. C. For example, the VOC of the electrodepositable
coating composition of the present invention may be no more than
500 g/L, such as no more than 300 g/L, such as no more than 150
g/L, such as no more than 50 g/L, such as no more than 1 g/L, such
as 0 g/L, and may range from 0 to 500 g/L, such as 0.1 to 300 g/L,
such as 0.1 to 150 g/L, such as 0.1 to 50 g/L, such as 0.1 to 1
g/L. The VOC may be calculated according to the following
formula:
VOC .function. ( g / L ) = total .times. .times. weight .times.
.times. of .times. .times. VOC .function. ( g ) volume .times.
.times. of .times. .times. total .times. .times. composition
.times. .times. ( L ) - volume .times. .times. of .times. .times.
water .times. .times. ( L ) ##EQU00001##
[0036] The organic solvent may be present, if at all, in an amount
of less than 30% by weight, such as less than 20% by weight, such
as less than 10% by weight, such as less than 5% by weight, such as
less than 3% by weight, such as less than 1% by weight, such as
less than 0.5% by weight, such as less than 0.3% by weight, such as
less than 0.1% by weight, such as 0.0% by weight, based on the
total weight of the electrodepositable coating composition.
[0037] Water is present in the aqueous medium such that the total
amount of water present in the electrodepositable coating
composition is at least 40% by weight, such as at least 45% by
weight, such as at least 50% by weight, such as at least 55% by
weight, such as at least 60% by weight, such as at least 65% by
weight, such as at least 70% by weight, such as at least 75% by
weight, such as at least 80% by weight, such as at least 85% by
weight, such as at least 90% by weight, such as at least 95% by
weight, and may be present in an amount of no more than 99% by
weight, such as no more than 95% by weight, such as no more than
90% by weight, such as no more than 85% by weight, such as no more
than 80% by weight, such as no more than 75% by weight, based on
the total weight of the electrodepositable coating composition.
Water may be present in an amount of 40% to 99% by weight, such as
45% to 99% by weight, such as 50% to 99% by weight, such as 60% to
99% by weight, such as 65% to 99% by weight, such as 70% to 99% by
weight, such as 75% to 99% by weight, such as 80% to 99% by weight,
such as 85% to 99% by weight, such as 90% to 99% by weight, such as
40% to 90% by weight, such as 45% to 85% by weight, such as 50% to
80% by weight, such as 60% to 75% by weight, based on the total
weight of the electrodepositable coating composition.
[0038] The electrodepositable coating composition may have a solids
content of no more than 60% by weight, such as no more than 55% by
weight, such as no more than 50% by weight, such as no more than
45% by weight, such as no more than 40% by weight, such as no more
than 35% by weight, such as no more than 30% by weight, such as no
more than 25% by weight, such as no more than 20% by weight, such
as no more than 15% by weight, such as no more than 10% by weight,
such as no more than 5% by weight, such as no more than 1% by
weight, based on the total weight of the electrodepositable coating
composition. The electrodepositable coating composition may have a
solids content of 0.1% to 60% by weight, such as 0.1% to 55% by
weight, such as 0.1% to 50% by weight, such as 0.1% to 45% by
weight, such as 0.1% to 40% by weight, such as 0.1% to 35% by
weight, such as 0.1% to 30% by weight, such as 0.1% to 25% by
weight, such as 0.1% to 20% by weight, such as 0.1% to 15% by
weight, such as 0.1% to 10% by weight, such as 0.1% to 5% by
weight, such as 0.1% to 1% by weight, based on the total weight of
the electrodepositable coating composition.
[0039] The electrodepositable coating composition may be packaged
in the form of a concentrate that is diluted with water and
optionally organic solvent prior to use as an electrodepositable
coating composition. Upon dilution, the electrodepositable coating
composition should have a solids and water content as described
herein.
[0040] According to the present invention, the electrodepositable
coating composition may optionally further comprise an
electrochemically active material. The material constituting the
electrochemically active material contained in the
electrodepositable coating composition is not particularly limited
and a suitable material can be selected according to the type of an
electrical storage device of interest.
[0041] The electrochemically active material may comprise a
material for use as an active material for a positive electrode.
The electrochemically active material for a positive electrode may
comprise a material capable of incorporating lithium (including
incorporation through lithium intercalation/deintercalation), a
material capable of lithium conversion, or combinations thereof.
Non-limiting examples of electrochemically active materials capable
of incorporating lithium include LiCoO.sub.2, LiNiO.sub.2,
LiFePO.sub.4, LiFeCoPO.sub.4, LiCoPO.sub.4, LiMnO.sub.2,
LiMn.sub.2O.sub.4, Li(NiMnCo)O.sub.2, Li(NiCoAl)O.sub.2,
carbon-coated LiFePO.sub.4, and combinations thereof. Ratios of the
transition metals present in the electrochemically active materials
may vary. For example, Li(NiMnCo)O.sub.2 (sometimes referred to as
"NMC") may have ratios of Ni:Mn:Co of 1:1:1, 5:3:2, 6:2:2, and
8:1:1. Non-limiting examples of materials capable of lithium
conversion include sulfur, LiO.sub.2, FeF.sub.2 and FeF.sub.3, Si,
aluminum, tin, SnCo, Fe.sub.3O.sub.4, and combinations thereof.
[0042] The electrochemically active material may comprise a
material for use as an active material for a negative electrode.
The electrochemically active material for a negative electrode may
comprise graphite, lithium titanate (LTO), lithium vanadium
phosphate (LVP), silicon, silicon compounds, tin, tin compounds,
sulfur, sulfur compounds, lithium metal, graphene, or a combination
thereof.
[0043] The electrochemically active material may be present in the
electrodepositable coating composition in an amount of at least 45%
by weight, such as at least 70% by weight, such as at least 80% by
weight, such as at least 90% by weight, such as at least 91% by
weight, and may be present in an amount of no more than 99% by
weight, such as no more than 98% by weight, such as no more than
95% by weight, based on the total solids weight of the
electrodepositable composition. The electrochemically active
material may be present in the electrodepositable coating
composition in amount of 45% to 99% by weight, such as 70% to 98%
by weight, such as 80% to 95% by weight, such as 90% to 95% by
weight, such as 91% to 95% by weight, based on the total solids
weight of the electrodepositable coating composition.
[0044] The electrodepositable coating composition of the present
invention may optionally further comprise an electrically
conductive agent. Non-limiting examples of electrically conductive
agents include carbonaceous materials such as, activated carbon,
carbon black such as acetylene black and furnace black, graphite,
graphene, carbon nanotubes, carbon fibers, fullerene, and
combinations thereof. It should be noted graphite may be used as
both an electrochemically active material for negative electrodes
as well as an electrically conductive agent, but an electrically
conductive material is typically omitted when graphite is used as
the electrochemically active material.
[0045] The electrically conductive agent may also comprise any
active carbon that has a high-surface area, such as a BET surface
area of greater than 100 m.sup.2/g. As used herein, the term "BET
surface area" refers to a specific surface area determined by
nitrogen adsorption according to the ASTM D 3663-78 standard based
on the Brunauer-Emmett-Teller method described in the periodical
"The Journal of the American Chemical Society", 60, 309 (1938). In
some examples, the conductive carbon can have a BET surface area of
100 m.sup.2/g to 1,000 m.sup.2/g, such as 150 m.sup.2/g to 600
m.sup.2/g, such as 100 m.sup.2/g to 400 m.sup.2/g, such as 200
m.sup.2/g to 400 m.sup.2/g. In some examples, the conductive carbon
can have a BET surface area of about 200 m.sup.2/g. A suitable
conductive carbon material is LITX 200 commercially available from
Cabot Corporation.
[0046] The electrically conductive agent may be present in the
electrodepositable coating composition in amounts of 0.5% to 20% by
weight, such as 1% to 20% by weight, such as 2% to 10% by weight,
such as 2.5% to 7% by weight, such as 3% to 5% by weight, based on
the total solids weight of the electrodepositable coating
composition.
[0047] As mentioned above, the binder may optionally further
comprise a crosslinking agent. The crosslinking agent should be
soluble or dispersible in the aqueous medium and be reactive with
active hydrogen groups of the pH-dependent rheology modifier and
any other resinous film-forming polymers optionally present in the
composition. Non-limiting examples of suitable crosslinking agents
include aminoplast resins, blocked polyisocyanates, carbodiimide,
and polyepoxides.
[0048] Examples of aminoplast resins for use as a crossslinking
agent are those which are formed by reacting a triazine such as
melamine or benzoguanamine with formaldehyde. These reaction
products contain reactive N-methylol groups. Usually, these
reactive groups are etherified with methanol, ethanol or butanol
including mixtures thereof to moderate their reactivity. For the
chemistry preparation and use of aminoplast resins, see "The
Chemistry and Applications of Amino Crosslinking Agents or
Aminoplast", Vol. V, Part II, page 21 ff., edited by Dr. Oldring;
John Wiley & Sons/Cita Technology Limited, London, 1998. These
resins are commercially available under the trademark MAPRENAL.RTM.
such as MAPRENAL MF980 and under the trademark CYMEL.RTM. such as
CYMEL 303 and CYMEL 1128, available from Cytec Industries.
[0049] Blocked polyisocyanate crosslinking agents are typically
diisocyanates such as toluene diisocyanate, 1,6-hexamethylene
diisocyanate and isophorone diisocyanate including isocyanato
dimers and trimers thereof in which the isocyanate groups are
reacted ("blocked") with a material such as epsilon-caprolactam and
methylethyl ketoxime. At curing temperatures, the blocking agents
unblock exposing isocyanate functionality that is reactive with the
hydroxyl functionality associated with the (meth)acrylic polymer.
Blocked polyisocyanate crosslinking agents are commercially
available from Covestro as DESMODUR BL.
[0050] Carbodiimide crosslinking agents may be in monomeric or
polymeric form, or a mixture thereof. Carbodiimide crosslinking
agents refer to compounds having the following structure:
R - N = C = N - R ` ##EQU00002##
wherein R and R' may each individually comprise an aliphatic,
aromatic, alkylaromatic, carboxylic, or heterocyclic group.
Examples of commercially available carbodiimide crosslinking agents
include, for example, those sold under the trade name CARBODILITE
available from Nisshinbo Chemical Inc., such as CARBODILITE
V-02-L2, CARBODILITE SV-02, CARBODILITE E-02, CARBODILITE SW-12G,
CARBODILITE V-10 and CARBODILITE E-05.
[0051] Examples of polyepoxide crosslinking agents are
epoxy-containing (meth)acrylic polymers such as those prepared from
glycidyl methacrylate copolymerized with other vinyl monomers,
polyglycidyl ethers of polyhydric phenols such as the diglycidyl
ether of bisphenol A; and cycloaliphatic polyepoxides such as
3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate and
bis(3,4-epoxy-6-methylcyclohexyl-methyl) adipate.
[0052] The crosslinking agent may be present in the
electrodepositable coating composition in amounts of 0% to 30% by
weight, such as 5% to 20% by weight, such as 5% to 15% by weight,
such as 7% to 12% by weight, the % by weight being based on the
total weight of the binder solids.
[0053] The crosslinking agent may be present in the
electrodepositable coating composition in amounts of 0% to 2% by
weight, such as 0.1% to 1% by weight, such as 0.2% to 0.8% by
weight, such as 0.3% to 0.5% by weight, the % by weight being based
on the total solids weight of the electrodepositable coating
composition.
[0054] As used herein, the term "binder solids" may be used
synonymously with "resin solids" and includes the pH-dependent
rheology modifier, and, if present, the crosslinking agent, the
non-fluorinated organic film-forming polymer, and the adhesion
promoter. As used herein, the term "binder dispersion" refers to a
dispersion of the binder solids in the aqueous medium.
[0055] The binder may comprise, consist essentially of, or consist
of the pH-dependent rheology modifier in an amount of 10% to 100%
by weight, such as 50% to 95% by weight, such as 70% to 93% by
weight, such as 87% to 92% by weight; and the crosslinking agent,
if present, in amounts of 0% to 30% by weight, such as 5% to 15% by
weight, such as 7% to 13% by weight, the % by weight being based on
the total weight of the binder solids.
[0056] The binder may optionally further comprise a non-fluorinated
organic film-forming polymer. The non-fluorinated organic
film-forming polymer is different than the pH-dependent rheology
modifier described herein. The non-fluorinated organic film-forming
polymer may comprise polysaccharides, polyacrylates, polyethylene,
polystyrene, polyvinyl alcohol, poly (methyl acrylate), poly (vinyl
acetate), polyacrylonitrile, polyimide, polyurethane, polyvinyl
butyral, polyvinyl pyrrolidone, styrene butadiene rubber, xanthan
gum, or combinations thereof.
[0057] The non-fluorinated organic film-forming polymer may be
present, if at all, in an amount of 0% to 90% by weight, such as
20% to 60% by weight, such as 25% to 40% by weight, based on the
total weight of the binder solids.
[0058] The non-fluorinated organic film-forming polymer may be
present, if at all, in an amount of at least 0% to 9.9% by weight,
such as 0.1% to 5% by weight, such as 0.2% to 2% by weight, such as
0.3% to 0.5% by weight, based on the total solids weight of the
electrodepositable coating composition.
[0059] The electrodepositable coating composition may also be
substantially free, essentially free, or completely free of any or
all of the non-fluorinated organic film-forming polymer described
herein.
[0060] The binder solids may be present in the electrodepositable
coating composition in amounts of 0.1% to 20% by weight, such as
0.2% to 10% by weight, such as 0.3% to 8% by weight, such as 0.5%
to 5% by weight, such as 1% to 3% by weight, such as 1.5% to 2.5%
by weight, such as 1% to 2% by weight, based on the total solids
weight of the electrodepositable coating composition.
[0061] The total solids of the electrodepositable coating
composition may be at least 0.1% by weight, such as at least 1% by
weight, such as at least 3% by weight, such as at least 5% by
weight, such as at least 7% by weight, such as at least 10% by
weight, such as at least 20% by weight, such as at least 30% by
weight, such as at least 40% by weight, and may be no more than 60%
by weight, such as no more than 50% by weight, such as no more than
40% by weight, such as no more than 30% by weight, such as no more
than 25% by weight, such as no more than 20% by weight, such as no
more than 15% by weight, such as no more than 12% by weight, such
as no more than 10% by weight, such as no more than 7% by weight,
such as no more than 5% by weight, based on the total weight of the
electrodepositable coating composition. The total solids of the
electrodepositable coating composition may be 0.1% to 60% by
weight, such as 0.1% to 50% by weight, such as 0.1% to 40% by
weight, such as 0.1% to 30% by weight, such as 0.1% to 25% by
weight, such as 0.1% to 20% by weight, such as 0.1% to 15% by
weight, such as 0.1% to 12% by weight, such as 0.1% to 10% by
weight, such as 0.1% to 7% by weight, such as 0.1% to 5% by weight,
such as 1% to 60% by weight, such as 1% to 50% by weight, such as
1% to 40% by weight, such as 1% to 30% by weight, such as 1% to 25%
by weight, such as 1% to 20% by weight, such as 1% to 15% by
weight, such as 1% to 12% by weight, such as 1% to 10% by weight,
such as 1% to 7% by weight, such as 1% to 5% by weight based on the
total weight of the electrodepositable coating composition.
[0062] The electrodepositable coating composition may comprise,
consist essentially of, or consist of the electrochemically active
material in an amount of 45% to 99% by weight, such as 70% to 98%
by weight, such as 80% to 95% by weight, such as 90% to 95% by
weight, such as 91% to 95% by weight; the electrically conductive
agent in an amount of 0.5% to 20% by weight, such as 1% to 20% by
weight, such as 2% to 10% by weight, such as 2.5% to 7% by weight,
such as 3% to 5% by weight; and the pH-dependent rheology modifier
in an amount of 0.1% to 10% by weight, such as 0.2% to 10% by
weight, such as 0.3% to 10% by weight, such as 1% to 7% by weight,
such as 1.5% to 5% by weight, such as 2% to 4.5% by weight, such as
3% to 4% by weight; and optionally the crosslinking agent in an
amount of 0% to 2% by weight, such as 0.1% to 1% by weight, such as
0.2% to 0.8% by weight, such as 0.3% to 0.5% by weight; the
non-fluorinated organic film-forming polymer in an amount of at
least 0% to 9.9% by weight, such as 0.1% to 5% by weight, such as
0.2% to 2% by weight, such as 0.3% to 0.5% by weight, based on the
total solids weight of the electrodepositable coating composition;
and water in an amount of 40% to 99% by weight, such as 45% to 99%
by weight, such as 50% to 99% by weight, such as 60% to 99% by
weight, such as 65% to 99% by weight, such as 70% to 99% by weight,
such as 75% to 99% by weight, such as 80% to 99% by weight, such as
85% to 99% by weight, such as 90% to 99% by weight, such as 40% to
90% by weight, such as 45% to 85% by weight, such as 50% to 80% by
weight, such as 60% to 75% by weight, based on the total weight of
the electrodepositable coating composition.
[0063] The electrodepositable coating composition may optionally
further comprise an adhesion promoter. The adhesion promoter may
comprise an acid-functional polyolefin or a thermoplastic
material.
[0064] The acid-functional polyolefin adhesion promoter may
comprise an ethylene-(meth)acrylic acid copolymer, such as an
ethylene-acrylic acid copolymer or an ethylene-methacrylic acid
copolymer. The ethylene-acrylic acid copolymer may comprise
constitutional units comprising 10% to 50% by weight acrylic acid,
such as 15% to 30% by weight, such as 17% to 25% by weight, such as
about 20% by weight, based on the total weight of the
ethylene-acrylic acid copolymer, and 50% to 90% by weight ethylene,
such as 70% to 85% by weight, such as 75% to 83% by weight, such as
about 80% by weight, based on the total weight of the
ethylene-acrylic acid copolymer. A commercially available example
of such an addition polymer includes PRIMACOR 5980i, available from
the Dow Chemical Company.
[0065] The adhesion promoter may be present in the
electrodepositable coating composition in an amount of 1% to 60% by
weight, such as 10% to 40% by weight, such as 25% to 35% by weight,
based on the total weight of the binder solids (including the
adhesion promoter).
[0066] The electrodepositable coating composition may optionally
further comprise a pH adjustment agent. The pH adjustment agent may
comprise an acid or base. The acid may comprise, for example,
phosphoric acid or carbonic acid. The base may comprise, for
example, lithium hydroxide, lithium carbonate, or
dimethylethanolamine (DMEA). Any suitable amount of pH adjustment
agent needed to adjust the pH of the electrodepositable coating
composition to the desired pH range may be used.
[0067] The present invention is also directed to an
electrodepositable coating composition comprising, consisting
essentially of, or consisting of (a) a pH-dependent rheology
modifier; (b) an electrically conductive agent; and (c) an aqueous
medium comprising water; wherein water is present in an amount of
at least 40% by weight, based on the total weight of the
electrodepositable coating composition. The pH-dependent rheology,
the crosslinking agent, and the aqueous medium may be the same
materials and present in the same amounts as described above.
[0068] The electrically conductive agent may be the same as those
described above. The electrically conductive agent may be present
in the electrodepositable coating composition in an amount of at
least 45% by weight, such as at least 70% by weight, such as at
least 80% by weight, such as at least 90% by weight, such as at
least 91% by weight, and may be present in an amount of no more
than 99% by weight, such as no more than 98% by weight, such as no
more than 95% by weight, based on the total solids weight of the
electrodepositable composition. The electrically conductive agent
may be present in the electrodepositable coating composition in
amount of 45% to 99% by weight, such as 70% to 98% by weight, such
as 80% to 95% by weight, such as 90% to 95% by weight, such as 91%
to 95% by weight, based on the total solids weight of the
electrodepositable coating composition.
[0069] The electrodepositable coating composition comprising,
consisting essentially of, or consisting of (a) the pH-dependent
rheology modifier; (b) the electrically conductive agent; and (d)
the aqueous medium comprising water may further comprise the
optional ingredients described above, including the crosslinking
agent, non-fluorinated organic film-forming polymer, adhesion
promoter and pH adjustment agent, in the amounts as described
above.
[0070] The present invention is also directed to methods for
coating a substrate. The electrodepositable coating composition may
be electrodeposited upon any electrically conductive substrate.
Suitable substrates include metal substrates, metal alloy
substrates, and/or substrates that have been metallized, such as
nickel-plated plastic. Additionally, substrates may comprise
non-metal conductive materials including composite materials such
as, for example, materials comprising carbon fibers or conductive
carbon. According to the present invention, the metal or metal
alloy may comprise cold rolled steel, hot rolled steel, steel
coated with zinc metal, zinc compounds, or zinc alloys, such as
electrogalvanized steel, hot-dipped galvanized steel, galvanealed
steel, and steel plated with zinc alloy. Aluminum alloys of the
1XXX, 2XXX, 3XXX, 4XXX, SXXX, 6XXX, 7XXX or 8XXX series as well as
clad aluminum alloys and cast aluminum alloys of the A356 series
also may be used as the substrate. Magnesium alloys of the AZ31B,
AZ91C, AM60B, or EV31A series also may be used as the substrate.
The substrate used in the present invention may also comprise
titanium and/or titanium alloys. Other suitable non-ferrous metals
include copper and magnesium, as well as alloys of these materials.
The substrate may be in the form of a current collector comprising
a conductive material, and the conductive material may comprise a
metal such as iron, copper, aluminum, nickel, and alloys thereof,
as well as stainless steel. Other suitable conductive substrates
include conductive carbon; a material coated with a conductive
primer; a pre-made battery electrode for preparation of a
multi-layered battery electrode; an electrically conductive porous
polymer; and a porous polymer comprising a conductive composite.
The substrate may also comprise an electrically insulating porous
polymer wherein the substrate is coated using a conductive backing,
such as, for example, by the method and with the apparatus
disclosed in U.S. Publication No. 2016/0317974 at paragraphs [0054]
to [0058].
[0071] The method for coating a substrate may comprise
electrodepositing an electrodepositable coating composition as
described above to at least a portion of the substrate and at least
partially curing the coating composition to form an at least
partially cured coating on the substrate. According to the present
invention, the method may comprise (a) electrodepositing onto at
least a portion of the substrate an electrodepositable coating
composition of the present invention and (b) heating the coated
substrate to a temperature and for a time sufficient to cure the
electrodeposited coating on the substrate.
[0072] In the methods of the present invention, a coating is
applied onto or over at least a portion of the substrate via an
electrodeposition process. In such a process, an electrically
conductive substrate (such as any of those described earlier)
serving as an electrode (such as an anode in anionic
electrodeposition) in an electrical circuit comprising the
electrode and a counter-electrode (such as a cathode in anionic
electrodeposition) is immersed in the electrodepositable coating
composition of the present invention. An electric current is passed
between the electrodes to cause the coating to deposit on the
substrate. The applied voltage may be varied and can be, for
example, as low as one volt to as high as several thousand volts
but is often between 50 and 500 volts. The current density is often
between 0.5 ampere and 15 amperes per square foot. The residence
time of the substrate in the composition may be from 10 to 180
seconds.
[0073] After electrocoating, the substrate is removed from the bath
and may be baked in an oven. For example, the coated substrate may
be baked at temperatures of 400.degree. C. or lower, such as
300.degree. C. or lower, such as 275.degree. C. or lower, such as
255.degree. C. or lower, such as 225.degree. C. or lower, such as
200.degree. C. or lower, such as 100.degree. C. to 400.degree. C.,
such as 200.degree. C. to 400.degree. C., such as 240.degree. C. to
300.degree. C., for 10 to 60 minutes. In other cases, after
electrocoating and removal of the substrate from the bath, the
coated substrate may simply be allowed to dry under ambient
conditions. As used herein, "ambient conditions" refers to
atmospheric air having a relative humidity of 10 to 100 percent and
a temperature in the range of -10 to 120.degree. C., such as 5 to
80.degree. C., in some cases 10 to 60.degree. C. and, in yet other
cases, 15 to 40.degree. C.
[0074] The present invention is also directed to an electrode
comprising an electrical current collector and a film formed on the
electrical current collector, wherein the film is deposited from
the electrodepositable coating composition described above. The
electrode may be a positive electrode or a negative electrode and
may be manufactured by depositing the above-described
electrodepositable coating composition to the surface of the
current collector to form a coating film, and subsequently drying
and/or curing the coating film.
[0075] The coating film of the electrode may comprise a
cross-linked coating. As used herein, the term "cross-linked
coating" refers to a coating wherein functional groups of the
pH-dependent rheology modifier have reacted with functional groups
of the crosslinking agent to form covalent bonds that cross-link
the component molecules of the binder. The adhesion promoter and
non-fluorinated organic film-forming polymer, if present, may also
have functional groups reactive with functional groups of the
crosslinking agent and may also serve to cross-link the
coating.
[0076] The current collector may comprise a conductive material,
and the conductive material may comprise a metal such as iron,
copper, aluminum, nickel, and alloys thereof, as well as stainless
steel. For example, the current collector may comprise aluminum or
copper in the form of a mesh, sheet or foil. Although the shape and
thickness of the current collector are not particularly limited,
the current collector may have a thickness of about 0.001 to 0.5
mm, such as a mesh, sheet or foil having a thickness of about 0.001
to 0.5 mm.
[0077] In addition, the current collector may be pretreated with a
pretreatment composition prior to depositing the electrodepositable
coating composition of the present invention. As used herein, the
term "pretreatment composition" refers to a composition that upon
contact with the current collector, reacts with and chemically
alters the current collector surface and binds to it to form a
protective layer. The pretreatment composition may be a
pretreatment composition comprising a group IIIB and/or IVB metal.
As used herein, the term "group IIIB and/or IVB metal" refers to an
element that is in group IIIB or group IVB of the CAS Periodic
Table of the Elements as is shown, for example, in the Handbook of
Chemistry and Physics, 63.sup.rd edition (1983). Where applicable,
the metal themselves may be used, however, a group IIIB and/or IVB
metal compound may also be used. As used herein, the term "group
IIIB and/or IVB metal compound" refers to compounds that include at
least one element that is in group IIIB or group IVB of the CAS
Periodic Table of the Elements. Suitable pretreatment compositions
and methods for pretreating the current collector are described in
U.S. Pat. No. 9,273,399 at col. 4, line 60 to col. 10, line 26, the
cited portion of which is incorporated herein by reference. The
pretreatment composition may be used to treat current collectors
used to produce positive electrodes or negative electrodes.
[0078] To prepare an electrode for a lithium ion electrical storage
device, an electrodepositable coating composition comprising the
electrochemically active material, an electrically conductive
agent, a binder comprising the pH-dependent rheology modifier, and
optional ingredients, is prepared by combining the ingredients to
form the electrodepositable coating composition. These substances
can be mixed together by agitation with a known means such as a
stirrer, bead mill or high-pressure homogenizer. Exemplary methods
for preparing such composition are presented in the examples
below.
[0079] The thickness of the coating formed after electrodeposition
may be at least 1 micron, such as 1 to 1,000 microns (.mu.m), such
as 10 to 500 .mu.m, such as 50 to 250 .mu.m, such as 75 to 200
.mu.m.
[0080] Drying and/or crosslinking the coating film after
application, if applicable, can be done, for example, by heating at
elevated temperature, such as at least 50.degree. C., such as at
least 60.degree. C., such as 50-400.degree. C., such as
100-300.degree. C., such as 150-280.degree. C., such as
200-275.degree. C., such as 225-270.degree. C., such as
235-265.degree. C., such as 240-260.degree. C. The time of heating
will depend somewhat on the temperature. Generally, higher
temperatures require less time for curing. Typically, curing times
are for at least 5 minutes, such as 5 to 60 minutes. The
temperature and time should be sufficient such that the binder in
the cured film is crosslinked (if applicable), that is, covalent
bonds are formed between co-reactive groups on the pH-dependent
rheology modifier and non-fluorinated organic film-forming polymer
(if present), such as carboxylic acid groups and hydroxyl groups,
and the reactive groups of the crosslinking agent, such as
N-methylol and/or the N-methylol ether groups of an aminoplast,
isocyanato groups of a blocked polyisocyanate crosslinking agent.
The crosslinked binder may be substantially solvent resistant to
the solvents of the electrolyte mentioned below. Other methods of
drying the coating film include ambient temperature drying,
microwave drying and infrared drying, and other methods of curing
the coating film include e-beam curing and UV curing.
[0081] According to the present invention, electrodes produced by
electrodeposition using the electrodepositable coating composition
of the present invention may have improved adhesion over comparable
aqueous coating compositions applied by other methods, such as, for
example, casting. For example, the 90.degree. peel strength
adhesion of the coating to the substrate may be measured using a
Mark-10 (model DC.sub.4060) motorized test stand equipped with a
mechanically driven 90.degree. peel stage. A 12.7 mm strip of the
coated substrate may be cut and anchored to the stage using
adhesive tape. Peel strength may be gauged as the force required to
delaminate the coating film from the substrate. Lateral movement of
the peel stage may be actively driven at the same rate as the
vertical movement of the peel head to ensure a 90.degree. peel and
provide an accurate and reproducible measure of peel strength. This
test method may be referred to herein as PEEL STRENGTH TEST METHOD.
The 90.degree. peel strength adhesion may be at least 10% greater
than a comparative coating composition at a similar mass loading,
such as at least 15% greater, such as at least 20% greater, such as
at least 25% greater, such as at least 30% greater, such as at
least 40% greater, such as at least 50% greater, such as at least
60% greater, such as at least 70% greater, such as at least 80%
greater, such as at least 90% greater, such as at least 100%
greater, as measured according to PEEL STRENGTH TEST METHOD. As
used herein, the term "comparative coating composition" refers to
aqueous compositions that do not include the pH-dependent rheology
modifier and otherwise have similar amounts of components as the
electrodepositable coating compositions of the present invention.
As used herein, the term "at a similar mass loading" refers to a
coating having a loading within 0.1 mg/cm.sup.2.
[0082] The 90.degree. peel strength adhesion may be at least 100
N/m at a mass loading of 2.15 g/cm.sup.2, such as at least 125 N/m,
such as at least 135 N/m, such as at least 145 N/m, such as at
least 155 N/m, such as at least 165 N/m, such as at least 175 N/m,
such as at least 180 N/m, as measured according to PEEL STRENGTH
TEST METHOD.
[0083] The present invention is also directed to an electrical
storage device. An electrical storage device according to the
present invention may be manufactured by using one or more of the
above electrodes prepared from the electrodepositable coating
composition of the present invention. The electrical storage device
comprises an electrode, a counter electrode and an electrolyte. The
electrode, counter-electrode or both may comprise the electrode of
the present invention, as long as one electrode is a positive
electrode and one electrode is a negative electrode. Electrical
storage devices according to the present invention include a cell,
a battery, a battery pack, a secondary battery, a capacitor, and a
supercapacitor.
[0084] The electrical storage device includes an electrolytic
solution and can be manufactured by using parts such as a separator
in accordance with a commonly used method. As a more specific
manufacturing method, a negative electrode and a positive electrode
are assembled together with a separator therebetween, the resulting
assembly is rolled or bent in accordance with the shape of a
battery and put into a battery container, an electrolytic solution
is injected into the battery container, and the battery container
is sealed up. The shape of the battery may be like a coin, button
or sheet, cylindrical, square or flat.
[0085] The electrolytic solution may be liquid or gel, and an
electrolytic solution which can serve effectively as a battery may
be selected from among known electrolytic solutions which are used
in electrical storage devices in accordance with the types of a
negative electrode active material and a positive electrode active
material. The electrolytic solution may be a solution containing an
electrolyte dissolved in a suitable solvent. The electrolyte may be
conventionally known lithium salt for lithium ion secondary
batteries. Examples of the lithium salt include LiClO.sub.4,
LiBF.sub.4, LiPF.sub.6, LiCF.sub.3CO.sub.2, LiAsF.sub.6,
LiSbF.sub.6, LiB.sub.10Cl.sub.10, LiAlCl.sub.4, LiCl, LiBr,
LiB(C.sub.2H.sub.5).sub.4, LiB(C.sub.6H.sub.5).sub.4,
LiCF.sub.3SO.sub.3, LiCH.sub.3SO.sub.3, LiC.sub.4F.sub.9SO.sub.3,
Li(CF.sub.3SO.sub.2).sub.2N, LiB.sub.4CH.sub.3SO.sub.3Li and
CF.sub.3SO.sub.3Li. The solvent for dissolving the above
electrolyte is not particularly limited and examples thereof
include carbonate compounds such as propylene carbonate, ethylene
carbonate, butylene carbonate, dimethyl carbonate, methyl ethyl
carbonate and diethyl carbonate; lactone compounds such as
.gamma.-butyl lactone; ether compounds such as trimethoxymethane,
1,2-dimethoxyethane, diethyl ether, 2-ethoxyethane, tetrahydrofuran
and 2-methyltetrahydrofuran; and sulfoxide compounds such as
dimethyl sulfoxide. The concentration of the electrolyte in the
electrolytic solution may be 0.5 to 3.0 mole/L, such as 0.7 to 2.0
mole/L.
[0086] During discharge of a lithium ion electrical storage device,
lithium ions may be released from the negative electrode and carry
the current to the positive electrode. This process may include the
process known as deintercalation. During charging, the lithium ions
migrate from the electrochemically active material in the positive
electrode to the negative electrode where they become embedded in
the electrochemically active material present in the negative
electrode. This process may include the process known as
intercalation.
[0087] The electrodepositable coating composition may be
substantially free, essentially free, or completely free of
fugitive adhesion promoter. As used herein, the term "fugitive
adhesion promoter" refers to N-methyl-2-pyrrolidone (NMP),
dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide (DMSO),
hexamethylphosphamide, dioxane, tetrahydrofuran, tetramethylurea,
triethyl phosphate, trimethyl phosphate, dimethyl succinate,
diethyl succinate and tetraethyl urea. As used herein, an
electrodepositable coating composition substantially free of
fugitive adhesion promoter includes less than 1% by weight fugitive
adhesion promoter, if any at all, based on the total weight of the
electrodepositable coating composition. As used herein, an
electrodepositable coating composition essentially free of fugitive
adhesion promoter includes less than 0.1% by weight fugitive
adhesion promoter, if any at all, based on the total weight of the
electrodepositable coating composition. When present, the fugitive
adhesion promoter may be present in an amount of less than 1% by
weight, such as less than 0.9% by weight, such as less than 0.1% by
weight, such as less than 0.01% by weight, such as less than 0.001%
by weight, based on the total weight of the electrodepositable
coating composition. When present, the fugitive adhesion promoter
may be present in an amount of less than 2% by weight, such as less
than 1% by weight, such as less than 0.1% by weight, such as less
than 0.01% by weight, such as less than 0.001% by weight, based on
the total solids weight of the electrodepositable coating
composition.
[0088] According to the present invention, the electrodepositable
coating composition may be substantially free, essentially free or
completely free of fluoropolymer. As used herein, the term
fluoropolymer refers to polymers and copolymers comprising the
residue of vinylidene fluoride, such as, for example,
polyvinylidene fluoride (PVDF). As used herein, the "polyvinylidene
fluoride polymer" includes homopolymers, copolymers, such as binary
copolymers, and terpolymers, including high molecular weight
homopolymers, copolymers, and terpolymers. Such (co)polymers
include those containing at least 50 mole percent, such as at least
75 mole %, and at least 80 mole %, and at least 85 mole % of the
residue of vinylidene fluoride (also known as vinylidene
difluoride). The vinylidene fluoride monomer may be copolymerized
with at least one comonomer selected from the group consisting of
tetrafluoroethylene, trifluoroethylene, chlorotrifluoroethylene,
hexafluoropropene, vinyl fluoride, pentafluoropropene,
tetrafluoropropene, perfluoromethyl vinyl ether, perfluoropropyl
vinyl ether and any other monomer that would readily copolymerize
with vinylidene fluoride in order to produce the fluoropolymer of
the present invention. The fluoropolymer may also comprise a PVDF
homopolymer. As used herein, the electrodepositable coating
composition is substantially free or essentially free of
fluoropolymer when fluoropolymer is present, if at all, in an
amount of less than 5% by weight or less than 0.2% by weight,
respectively, based on the total weight of the binder solids.
[0089] According to the present invention, the electrodepositable
coating composition may be substantially free, essentially free or
completely free of polyethylene, polytetrafluoroethylene,
tetrafluoroethylene-hexafluoropropylene copolymer, and/or
polyacrylonitrile derivatives.
[0090] The electrodepositable coating composition may be
substantially free of graphene oxide. As used herein, an
electrodepositable composition is substantially free or essentially
free of graphene oxide when graphene oxide is present, if at all,
in an amount less than 5% by weight or less than 1% by weight,
respectively, based on the total solids weight of the
electrodepositable coating composition.
[0091] The pH-dependent rheology modifier may be substantially
free, essentially free, or completely free of the residue of a
carboxylic acid amide monomer unit. As used herein, a pH-dependent
rheology modifier is substantially free or essentially free of
carboxylic acid amide monomer units when carboxylic acid amide
monomer units are present, if at all, in an amount less than 0.1%
by weight or less than 0.01% by weight, respectively, based on the
total weight of the pH-dependent rheology modifier.
[0092] The electrodepositable coating may be substantially free,
essentially free, or completely free of isophorone.
[0093] The electrodepositable coating may be substantially free,
essentially free, or completely free of a cellulose derivative.
Non-limiting examples of cellulose derivatives includes
carboxymethylcellulose and salts thereof (CMC). CMC is a cellulosic
ether in which a portion of the hydroxyl groups on the
anhydroglucose rings are substituted with carboxymethyl groups.
[0094] The electrodepositable coating may be substantially free,
essentially free, or completely free of multi-functional hydrazide
compounds. As used herein, an electrodepositable composition is
substantially free or essentially free of multi-functional
hydrazide compounds when multi-functional hydrazide compounds are
present, if at all, in an amount less than 0.1% by weight or less
than 0.01% by weight, respectively, based on the total binder
solids weight of the electrodepositable coating composition.
[0095] The electrodepositable coating may be substantially free,
essentially free, or completely free of styrene-butadiene rubber
(SBR), acrylonitrile butadiene rubber or acrylic rubber. As used
herein, an electrodepositable composition is substantially free or
essentially free of styrene-butadiene rubber (SBR), acrylonitrile
butadiene rubber or acrylic rubber when styrene-butadiene rubber
(SBR), acrylonitrile butadiene rubber or acrylic rubber is present,
if at all, in an amount less than 5% by weight or less than 1% by
weight, respectively, based on the total binder solids weight of
the electrodepositable coating composition.
[0096] The electrodepositable coating may be substantially free,
essentially free, or completely free of poly(meth)acrylic acid
having more than 70% by weight (meth)acrylic acid functional
monomers, based on the total weight of the poly(meth)acrylic acid.
As used herein, an electrodepositable composition is substantially
free or essentially free of poly(meth)acrylic acid when
poly(meth)acrylic acid is present, if at all, in an amount less
than 5% by weight or less than 1% by weight, respectively, based on
the total binder solids weight of the electrodepositable coating
composition.
[0097] The electrodepositable coating composition may be
substantially free, essentially free, or completely free of
particulate polymers containing the residue of an aliphatic
conjugated diene monomer unit and an aromatic vinyl monomer unit.
As used herein, an electrodepositable composition is substantially
free or essentially free of such particular polymers when the
particular polymer is present, if at all, in an amount less than 5%
by weight or less than 1% by weight, respectively, based on the
total weight of the binder solids.
[0098] As used herein, the term "polymer" refers broadly to
oligomers and both homopolymers and copolymers. The term "resin" is
used interchangeably with "polymer".
[0099] The terms "acrylic" and "acrylate" are used interchangeably
(unless to do so would alter the intended meaning) and include
acrylic acids, anhydrides, and derivatives thereof, such as their
C.sub.1-C.sub.5 alkyl esters, lower alkyl-substituted acrylic
acids, e.g., C.sub.1-C.sub.2 substituted acrylic acids, such as
methacrylic acid, 2-ethylacrylic acid, etc., and their
C.sub.1-C.sub.4 alkyl esters, unless clearly indicated otherwise.
The terms "(meth)acrylic" or "(meth)acrylate" are intended to cover
both the acrylic/acrylate and methacrylic/methacrylate forms of the
indicated material, e.g., a (meth)acrylate monomer. The term
"(meth)acrylic polymer" refers to polymers prepared from one or
more (meth)acrylic monomers.
[0100] As used herein molecular weights are determined by gel
permeation chromatography using a polystyrene standard. Unless
otherwise indicated molecular weights are on a weight average
basis.
[0101] The term "glass transition temperature" is a theoretical
value being the glass transition temperature as calculated by the
method of Fox on the basis of monomer composition of the monomer
charge according to T. G. Fox, Bull. Am. Phys. Soc. (Ser. II) 1,
123 (1956) and J. Brandrup, E. H. Immergut, Polymer Handbook
3.sup.rd edition, John Wiley, New York, 1989.
[0102] As used herein, unless otherwise defined, the term
"substantially free" means that the component is present, if at
all, in an amount of less than 5% by weight, based on the total
weight of the electrodepositable coating composition.
[0103] As used herein, unless otherwise defined, the term
"essentially free" means that the component is present, if at all,
in an amount of less than 1% by weight, based on the total weight
of the electrodepositable coating composition.
[0104] As used herein, unless otherwise defined, the term
"completely free" means that the component is not present in the
electrodepositable coating composition, i.e., 0.00% by weight,
based on the total weight of the electrodepositable coating
composition.
[0105] As used herein, the term "total solids" refers to the
non-volatile components of the electrodepositable coating
composition of the present invention and specifically excludes the
aqueous medium. The total solids include at least the binder,
electrochemically active material and/or electrically conductive
agent, adhesion promoter, and crosslinking agent, if present.
[0106] For purposes of the detailed description, it is to be
understood that the invention may assume various alternative
variations and step sequences, except where expressly specified to
the contrary. Moreover, other than in any operating examples, or
where otherwise indicated, all numbers such as those expressing
values, amounts, percentages, ranges, subranges and fractions may
be read as if prefaced by the word "about", even if the term does
not expressly appear. Accordingly, unless indicated to the
contrary, the numerical parameters set forth in the following
specification and attached claims are approximations that may vary
depending upon the desired properties to be obtained by the present
invention. At the very least, and not as an attempt to limit the
application of the doctrine of equivalents to the scope of the
claims, each numerical parameter should at least be construed in
light of the number of reported significant digits and by applying
ordinary rounding techniques. Where a closed or open-ended
numerical range is described herein, all numbers, values, amounts,
percentages, subranges and fractions within or encompassed by the
numerical range are to be considered as being specifically included
in and belonging to the original disclosure of this application as
if these numbers, values, amounts, percentages, subranges and
fractions had been explicitly written out in their entirety.
[0107] Notwithstanding that the numerical ranges and parameters
setting forth the broad scope of the invention are approximations,
the numerical values set forth in the specific examples are
reported as precisely as possible. Any numerical value, however,
inherently contains certain errors necessarily resulting from the
standard variation found in their respective testing
measurements.
[0108] As used herein, unless indicated otherwise, a plural term
can encompass its singular counterpart and vice versa, unless
indicated otherwise. For example, although reference is made herein
to "an" electrochemically active material, "an" electrically
conductive agent, "a" pH-dependent rheology modifier, "a"
crosslinking agent, a combination (i.e., a plurality) of these
components can be used. In addition, in this application, the use
of "or" means "and/or" unless specifically stated otherwise, even
though "and/or" may be explicitly used in certain instances.
[0109] As used herein, "including", "containing" and like terms are
understood in the context of this application to be synonymous with
"comprising" and are therefore open-ended and do not exclude the
presence of additional undescribed or unrecited elements,
materials, ingredients or method steps. As used herein, "consisting
of" is understood in the context of this application to exclude the
presence of any unspecified element, ingredient or method step. As
used herein, "consisting essentially of" is understood in the
context of this application to include the specified elements,
materials, ingredients or method steps "and those that do not
materially affect the basic and novel characteristic(s)" of what is
being described.
[0110] As used herein, the terms "on", "onto", "applied on",
"applied onto", "formed on", "deposited on", "deposited onto", mean
formed, overlaid, deposited, or provided on but not necessarily in
contact with the surface. For example, an electrodepositable
coating composition "deposited onto" a substrate does not preclude
the presence of one or more other intervening coating layers of the
same or different composition located between the
electrodepositable coating composition and the substrate.
[0111] Whereas specific embodiments of the invention have been
described in detail, it will be appreciated by those skilled in the
art that various modifications and alternatives to those details
could be developed in light of the overall teachings of the
disclosure. Accordingly, the particular arrangements disclosed are
meant to be illustrative only and not limiting as to the scope of
the invention which is to be given the full breadth of the claims
appended and any and all equivalents thereof.
ASPECTS
[0112] In view of the foregoing, the present invention thus relates
inter alia, without being limited thereto, to the following
aspects:
1. An electrodepositable coating composition comprising: [0113] a
binder comprising a pH-dependent rheology modifier comprising the
residue of a crosslinking monomer and/or a monoethylenically
unsaturated alkylated alkoxylate monomer; [0114] an
electrochemically active material and/or an electrically conductive
agent; and [0115] an aqueous medium. 2. The electrodepositable
coating composition of Aspect 1, wherein the pH-dependent rheology
modifier comprises an alkali-swellable rheology modifier, a
hydrophobically modified alkali-swellable rheology modifier, or a
star polymer. 3. The electrodepositable coating composition of
Aspect 2, wherein a composition of water and the alkali-swellable
rheology modifier at 4.25% by weight of the total composition may
have an increase in viscosity of at least 500 cps over an increase
in pH value of 3 pH unit over a pH range of 3 to 12, as measured
using a Brookfield viscometer using a #4 spindle and operated at 20
RPMs. 4. The electrodepositable coating composition of any one of
Aspects 1-3, wherein the pH-dependent rheology modifier comprises a
crosslinked alkali-swellable rheology modifier comprising the
residue of the crosslinking monomer. 5. The electrodepositable
coating composition of Aspect 4, wherein the crosslinked
alkali-swellable rheology modifier comprises constitutional units
comprising the residue of a monoethylenically unsaturated
carboxylic acid, a C.sub.1 to C.sub.6 alkyl (meth)acrylate monomer,
and the cros slinking monomer. 6. The electrodepositable coating
composition of Aspect 5, wherein the crosslinked alkali-swellable
rheology modifier comprises constitutional units comprising the
residue of: [0116] 20 to 65% by weight of the monoethylenically
unsaturated carboxylic acid; [0117] 20 to 80% by weight of the
C.sub.1 to C.sub.6 alkyl (meth)acrylate monomer; and [0118] 0.1 to
3% by weight of the crosslinking monomer, based on the total weight
of the crosslinked alkali-swellable rheology modifier. 7. The
electrodepositable coating composition of any one of Aspects 1-3,
wherein the pH-dependent rheology modifier comprises a
hydrophobically modified alkali-swellable rheology modifier
comprising the residue of the monoethylenically unsaturated alkyl
alkoxylate monomer. 8. The electrodepositable coating composition
of any one of Aspects 1-3 or 7, wherein the hydrophobically
modified alkali-swellable rheology modifier comprises
constitutional units comprising the residue of a monoethylenically
unsaturated carboxylic acid; a C.sub.1 to C.sub.6 alkyl
(meth)acrylate monomer; and the monoethylenically unsaturated alkyl
alkoxylate monomer. 9. The electrodepositable coating composition
of Aspect 8, wherein the hydrophobically modified alkali-swellable
rheology modifier comprises constitutional units comprising the
residue of:
[0119] 2 to 70% by weight of the monoethylenically unsaturated
carboxylic acid;
[0120] 20 to 80% by weight of the C.sub.1 to C.sub.6 alkyl
(meth)acrylate monomer; and
[0121] 0.5 to 60% by weight of the monoethylenically unsaturated
alkyl alkoxylate monomer, based on the total weight of the
hydrophobically modified alkali-swellable rheology modifier.
10. The electrodepositable coating composition of any one of
Aspects 1-6, wherein the crosslinking monomer comprises monomers
having at least two ethylenically unsaturated groups per monomer.
11. The electrodepositable coating composition of Aspect 1, wherein
the pH-dependent rheology modifier comprises an acid-swellable
rheology modifier. 12. The electrodepositable coating composition
of any one of the preceding Aspects, further comprising a
crosslinking agent. 13. The electrodepositable coating composition
of Aspect 12, wherein the crosslinking agent comprises
carbodiimide. 14. The electrodepositable coating composition of any
one of the preceding Aspects, wherein the binder further comprises
a non-fluorinated organic film-forming polymer. 15. The
electrodepositable coating composition of Aspect 14, wherein the
non-fluorinated organic film-forming polymer comprises
polysaccharides, polyacrylates, polyethylene, polystyrene,
polyvinyl alcohol, poly (methyl acrylate), poly (vinyl acetate),
polyacrylonitrile, polyimide, polyurethane, polyvinyl butyral,
polyvinyl pyrrolidone, styrene butadiene rubber, xanthan gum, or
combinations thereof. 16. The electrodepositable coating
composition of any one of the preceding Aspects, wherein the
electrochemically active material comprises a positive electrode
active material comprising LiCoO.sub.2, LiNiO.sub.2, LiFePO.sub.4,
LiFeCoPO.sub.4, LiCoPO.sub.4, LiMnO.sub.2, LiMn.sub.2O.sub.4,
Li(NiMnCo)O.sub.2, Li(NiCoAl)O.sub.2, carbon-coated LiFePO.sub.4,
sulfur, LiO.sub.2, FeF.sub.2 and FeF.sub.3, Si, aluminum, tin,
SnCo, Fe.sub.3O.sub.4, or combinations thereof; or a negative
electrode active material comprising graphite, lithium titanate,
lithium vanadium phosphate, silicon, silicon compounds, tin, tin
compounds, sulfur, sulfur compounds, lithium metal, graphene, or a
combination thereof. 17. The electrodepositable coating composition
of any one of the preceding Aspects, wherein the electrically
conductive agent comprises conductive carbon black, carbon
nanotubes, graphene, graphite, carbon fibers, fullerenes, and
combinations thereof. 18. The electrodepositable coating
composition of any one of the preceding Aspects, wherein the
electrodepositable coating composition comprises: [0122] (a) 0.1%
to 10% by weight of the pH-dependent rheology modifier; [0123] (b)
0.02% to 2% by weight of the crosslinking agent; [0124] (c) 45% to
99% by weight of the electrochemically active material; [0125] (d)
optionally 0.5% to 20% by weight of the electrically conductive
agent; and [0126] (e) optionally 0.1% to 9.9% by weight of a
non-fluorinated organic film-forming polymer; the % by weight based
on the total solids weight of the electrodepositable composition.
19. The electrodepositable coating composition of any one of the
preceding Aspects, wherein the VOC of the electrodepositable
coating composition is no more than 500 g/L. 20. The
electrodepositable coating composition of any one of the preceding
Aspects, wherein a coating produced on the substrate by
electrodeposition of the electrodepositable coating composition of
any one of Aspects 1-13 has a 90.degree. peel strength at least 10%
greater than a coating produced from a comparative coating
composition at a similar mass loading that is not applied by
electrodeposition, the 90.degree. peel strength measured according
to PEEL STRENGTH TEST METHOD. 21. The electrodepositable coating
composition of any one of the preceding Aspects, wherein a coating
produced on the substrate by electrocoating the electrodepositable
coating composition of any one of Aspects 1-19 has a 90.degree.
peel strength of at least 100 N/m at a mass loading of 2.15
mg/cm.sup.2, as measured according to PEEL STRENGTH TEST METHOD.
22. The electrodepositable coating composition of any one of the
preceding Aspects, wherein the electrodepositable coating
composition is substantially free of fluoropolymer. 23. The
electrodepositable coating composition of any one of the preceding
Aspects, wherein the binder consists essentially of the
pH-dependent rheology modifier and the carbodiimide cros slinking
agent. 24. The electrodepositable coating composition of any one of
the preceding Aspects, wherein the electrodepositable coating
composition is substantially free of cellulose-based materials,
polyvinyl alcohol, polycarboxylic acid, and salts thereof. 25. The
electrodepositable coating composition of any one of the preceding
Aspects, wherein the electrodepositable coating composition is
substantially free of multi-functional hydrazide compounds. 26. The
electrodepositable coating composition of any one of the preceding
Aspects, wherein the electrodepositable coating composition is
substantially free of particulate polymers containing the residue
of an aliphatic conjugated diene monomer unit and an aromatic vinyl
monomer unit. 27. The electrodepositable coating composition of any
one of the preceding Aspects, wherein the pH-dependent rheology
modifier is substantially free of amide, glycidyl and hydroxyl
groups. 28. The electrodepositable coating composition of any one
of the preceding Aspects, wherein the pH-dependent rheology
modifier is substantially free of the residue of constitutional
units comprising aromatic vinyl monomers. 29. A method of coating a
substrate comprising: [0127] electrocoating an electrodepositable
coating composition onto the substrate, the electrodepositable
coating composition comprising: [0128] a binder comprising a
pH-dependent rheology modifier; [0129] an electrochemically active
material and/or an electrically conductive agent; and [0130] an
aqueous medium. 30. The method of Aspect 29, wherein the binder
further comprises a non-fluorinated organic film-forming polymer.
31. The method of Aspect 30, wherein the non-fluorinated organic
film-forming polymer comprises polysaccharides, polyacrylates,
polyethylene, polystyrene, polyvinyl alcohol, poly (methyl
acrylate), poly (vinyl acetate), polyacrylonitrile, polyimide,
polyurethane, polyvinyl butyral, polyvinyl pyrrolidone, styrene
butadiene rubber, xanthan gum, or combinations thereof. 32. The
method of Aspect 24 or Aspect 25, wherein the binder comprises:
[0131] 5% to 99% by weight of the pH-dependent rheology modifier;
and [0132] 1% to 94% by weight of the non-fluorinated organic
film-forming polymer, based on the total weight of the binder. 33.
The method of any one of Aspects 29-32, wherein the binder further
comprises a cros slinking agent. 34. The method of Aspect 33,
wherein the crosslinking agent comprises a carbodiimide,
aminoplast, oxazaline, polyisocyanate, or combinations thereof. 35.
The method of any one of Aspects 29-34, wherein the
electrochemically active material comprises LiCoO.sub.2,
LiNiO.sub.2, LiFePO.sub.4, LiFeCoPO.sub.4, LiCoPO.sub.4,
LiMnO.sub.2, LiMn.sub.2O.sub.4, Li(NiMnCo)O.sub.2,
Li(NiCoAl)O.sub.2, carbon-coated LiFePO.sub.4, or a combination
thereof. 36. The method of any one of Aspects 29-34, wherein the
electrochemically active material comprises sulfur, LiO.sub.2,
FeF.sub.2 and FeF.sub.3, Si, aluminum, tin, SnCo, Fe.sub.3O.sub.4,
or combinations thereof. 37. The method of any one of Aspects
29-34, wherein the electrochemically active material comprises
graphite, lithium titanate, lithium vanadium phosphate, silicon,
silicon compounds, tin, tin compounds, sulfur, sulfur compounds,
lithium metal, graphene, or a combination thereof. 38. The method
of any one of Aspects 29-37, wherein the pH-dependent rheology
modifier comprises an alkali-swellable rheology modifier. 39. The
method of Aspect 38, wherein a composition of water and the
alkali-swellable rheology modifier at 4.25% by weight of the total
composition may have an increase in viscosity of at least 500 cps
over an increase in pH value of 3 pH units within the pH range of 3
to 12, as measured using a Brookfield viscometer using a #4 spindle
and operated at 20 RPMs. 40. The method of any one of Aspects
29-37, wherein the pH-dependent rheology modifier comprises an
acid-swellable rheology modifier. 41. The method of any one of
Aspects 29-40, wherein the electrically conductive agent comprises
conductive carbon black, carbon nanotubes, graphene, graphite,
carbon fibers, fullerenes, and combinations thereof. 42. The method
of any one of Aspects 29-41, wherein the electrodepositable coating
composition comprises: [0133] (a) 0.1% to 10% by weight of the
pH-dependent rheology modifier; [0134] (b) 45% to 99% by weight of
the electrochemically active material; [0135] (c) optionally 0.5%
to 20% by weight of the electrically conductive agent; [0136] (d)
optionally 0.02% to 2% by weight of a crosslinking agent; and
[0137] (e) optionally 0.1% to 10% by weight of a non-fluorinated
organic film-forming polymer; the % by weight based on the total
solids weight of the electrodepositable composition. 43. The method
of any one of Aspects 29-42, wherein the VOC of the
electrodepositable coating composition is no more than 500 g/L. 44.
The method of any one of Aspects 29-43, wherein a coating produced
on the substrate by the method of any one of Aspects 23-37 has a
90.degree. peel strength at least 10% greater than a coating
produced from a comparative coating composition at a similar mass
loading that is not applied by electrodeposition, the 90.degree.
peel strength measured according to PEEL STRENGTH TEST METHOD. 45.
The method of any one of Aspects 29-43, wherein a coating produced
on the substrate by the method of any one of Aspects 23-38 has a
90.degree. peel strength of at least 100 N/m at a mass loading of
at least 2.15 mg/cm.sup.2, as measured according to PEEL STRENGTH
TEST METHOD. 46. The method of any one of Aspects 29-43, wherein
the method has a mass deposition rate of the electrodepositable
coating composition of at least 0.04 mg/cm.sup.2/s when
electrocoated using an applied voltage of 30V and a separation of
2.7cm between a counter electrode and the substrate. 47. The method
of any one of Aspects 29-46, wherein the electrodepositable coating
composition is substantially free of fluoropolymer. 48. The method
of coating a substrate according to any one of Aspects 29-47
wherein the electrodepositable coating composition is an
electrodepositable coating composition of any one of Aspects 1-28.
49. A coated substrate comprising an electrical current collector
and a coating formed on at least a portion of the electrical
current collector according to the method of any one of Aspects
29-48. 50. The coated substrate of Aspect 49, wherein the
electrical current collector comprises aluminum, copper, steel,
stainless steel, nickel, conductive carbon, a conductive primer
coating, or a porous polymer. 51. The coated substrate of Aspect 49
or Aspect 50, wherein the coated substrate comprises a positive
electrode. 52. The coated substrate of Aspect 49 or Aspect 50,
wherein the coated substrate comprises a negative electrode. 53. An
electrical storage device comprising: [0138] (a) an electrode
comprising the coated substrate of any one of Aspects 49-52; [0139]
(b) a counter-electrode, and [0140] (c) an electrolyte. 54. The
electrical storage device of Aspect 53, wherein the electrical
storage device comprises a cell. 55. The electrical storage device
of Aspect 53, wherein the electrical storage device comprises a
battery pack. 56. The electrical storage device of Aspect 53,
wherein the electrical storage device comprises a secondary
battery. 57. The electrical storage device of Aspect 53, wherein
the electrical storage device comprises a capacitor. 58. The
electrical storage device of Aspect 53, wherein the electrical
storage device comprises a supercapacitor.
[0141] Illustrating the invention are the following examples,
which, however, are not to be considered as limiting the invention
to their details. Unless otherwise indicated, all parts and
percentages in the following examples, as well as throughout the
specification, are by weight.
EXAMPLES
[0142] Example 1--Preparation of Electrodepositable Coating
Composition and Application by Electrodeposition: To a plastic cup
was added 10.954 g of the alkali swellable emulsion HASE TT-615
from DOW Chemicals (3.26 g of solid material, 4.0 wt. % of total
solids), 5.076 g of ethanol, and 65.9 g of water. This mixture was
mixed in a centrifugal mixer at 2000 RPMs for 5 minutes. Next, 75.0
g (92 wt. % of total solids) of Lithium Iron Phosphate positive
electrode electrochemically active material acquired from Gelon was
added to the mixture and mixed in centrifugal mixer at 2000 RPMs
for 5 minutes. Next, 3.26 g of carbon black (SUPER P, from
available from Imerys, 4.0 wt. % of total solids) was added to the
mixture and mixed in a centrifugal mixer at 2000 RPMs for 5
minutes. Finally, 9.0 g of Hexyl CELLOSOLVE glycol ether from DOW
Chemical and 3.0 g of DOWANOL PnB glycol ether from DOW Chemical
were added to the composition and mixed in a centrifugal mixer at
2000 RPMs for 5 minutes.
[0143] The electrodepositable coating composition was diluted to
10% total solids by the addition of 634.0 g of water under constant
stirring. After 30 minutes of stirring, electrocoat was performed.
An application of 30V was applied to a 4 cm.times.6 cm
carbon-coated aluminum foil immersed 3 cm into the solution with a
separation of 2.7 cm from a 4 cm.times.6 cm aluminum counter
electrode immersed 3 cm into the composition. Constant stirring was
maintained during the electrodeposition process. Depositions at 10
s, 20 s, and 30 s yielded a mass deposition rate of 0.18
mg/cm.sup.2/s. The coated substrates were baked in a box oven at
60.degree. C. for 15 minutes followed by an additional bake at
246.degree. C. for 10 minutes. The coated substrates were pressed
to 35% porosity using a calendar press from Innovative Machine
Corporation.
[0144] The adhesion of battery coatings to the substrate was
measured using a Mark-10 (model DC.sub.4060) motorized test stand
equipped with a mechanically driven 90.degree. peel stage. A 12.7
mm strip of the film from Example 1 cut and anchored to the stage
using adhesive tape. Peel strength was gauged as the force required
to delaminate the film from the substrate. Lateral movement of the
peel stage is actively driven at the same rate as the vertical
movement of the peel head to ensure a 90.degree. peel and provide
an accurate and reproducible measure of peel strength. This test
method is referred to herein as the PEEL STRENGTH TEST METHOD. The
90.degree. peel strength of the electrocoated film was 26.1 N/m at
a mass loading of 3.36 mg/cm.sup.2.
[0145] Comparative Example 2--Preparation of Coating Composition
and Application to Substrate by Drawdown Method: To a plastic cup
was added 10.954 g of a pH-dependent rheology modifier (ACRYSOL
HASE TT-615 from DOW Chemical, 3.26 g of solid material, 4 wt. % of
total solids), 5.076 g of ethanol, and 65.9 g of water. This
mixture was mixed in a centrifugal mixer at 2000 RPMs for 5
minutes. Next, 75.0 g (92 wt. % of total solids) of Lithium Iron
Phosphate positive electrode electrochemically active material
acquired from Gelon was added to the mixture and mixed in
centrifugal mixer at 2000 RPMs for 5 minutes. Next, 3.26 g of
carbon black (SUPER P, from available from Imerys, 4.0 wt. % of
total solids) was added to the mixture and mixed in a centrifugal
mixer at 2000 RPMs for 5 minutes. Finally, 9.0 g of hexyl
CELLOSOLVE glycol ether from DOW Chemical and 3.0 g of DOWANOL PNB
glycol ether from DOW Chemical were added and the slurry was mixed
in a centrifugal mixer at 2000 RPMs for 5 minutes.
[0146] The slurry was cast onto a carbon-coated aluminum foil using
an automatic drawdown table with a gap height of 50 .mu.m. Samples
were baked in a box oven at 60.degree. C. for 15 minutes followed
by an additional bake at 246.degree. C. for 10 minutes. Samples
were pressed to 35% porosity using a calendar press from Innovative
Machine Corporation.
[0147] The coating was tested for adhesion using the same method as
in Example 1. The 90.degree. peel strength of the electrocoated
film was 14 N/m at a mass loading of 3.05 mg/cm.sup.2.
[0148] Example 1 and Comparative Example 2 demonstrate a
significant improvement in adhesion for a coating applied by
electrodeposition over a coating applied by drawdown despite the
only difference between the coating compositions of Example 1 and
Comparative Example 2 was the formulation and application for an
electrocoat in Example 1 in comparison to a formulation and
application by drawdown slurry in Comparative Example 2.
[0149] Example 3--Preparation of Electrodepositable Coating
Composition and Application by Electrodeposition: To a plastic cup
was added 9.86 g of a pH-dependent rheology modifier (ACRYSOL HASE
TT-615 from DOW Chemical, 2.93 g of solid material, 3.6 wt. % of
total solids), 5.076 g of ethanol, 65.9 g of water, and 0.815 g of
crosslinking agent (CARBODILITE V-02-L2, available from Nisshinbo
Chemical Inc., 0.33 g solid material, 0.40 wt. % of total solids).
This mixture was mixed in a centrifugal mixer at 2000 RPMs for 5
minutes. Next, 75.0 g (92 wt. % of total solids) of Lithium Iron
Phosphate positive electrode electrochemically active material
acquired from Gelon was added to the mixture and mixed in
centrifugal mixer at 2000 RPMs for 5 minutes. Next, 3.26 g of
carbon black (SUPER P, from available from Imerys, 4.0 wt. % of
total solids) was added to the mixture and mixed in a centrifugal
mixer at 2000 RPMs for 5 minutes. Finally, 9.0 g of Hexyl
CELLOSOLVE glycol ether from DOW Chemical and 3.0 g of DOWANOL PnB
glycol ether from DOW Chemical were added to the composition and
mixed in a centrifugal mixer at 2000 RPMs for 5 minutes.
[0150] The composition was diluted to 10% total solids by the
addition of 634.0 g of water under constant stirring. After 30
minutes of stirring, electrocoat was performed using the same
method as described in Example 1. Depositions at 10 s, 20 s, and 30
s yielded a mass deposition rate of 0.09 mg/cm.sup.2/s. Films were
baked at a temperature of 245.degree. C. for 10 minutes and pressed
to a porosity of 35% using a calendar press from Innovative Machine
Corporation.
[0151] Coatings at three different mass loadings were tested for
adhesion using the same method as in Example 1. The results are
included in Table 1 below.
TABLE-US-00002 TABLE 1 Mass (mg/cm.sup.2) Peel Strength (N/m) 2.15
184 2.90 57 3.56 38
[0152] Comparative Example 4--Preparation of Coating Composition
and Application to Substrate by Drawdown Method: To a plastic cup
was added 9.86 g of a pH-dependent rheology modifier (ACRYSOL HASE
TT-615 from DOW Chemical Co., 2.93 g of solid material, 3.6 wt. %
of total solids), 5.076 g of ethanol, 65.9 g of water, and 0.815 g
of crosslinking agent (CARBODILITE V-02-L2, available from
Nisshinbo Chemical Inc., 0.33 g of solid material, 0.40 wt. % of
total solids). This mixture was mixed in a centrifugal mixer at
2000 RPMs for 5 minutes. Next, 75.0 g (92 wt. % of total solids) of
Lithium Iron Phosphate positive electrode electrochemically active
material acquired from Gelon was added to the mixture and mixed in
centrifugal mixer at 2000 RPMs for 5 minutes. Next, 3.26 g of
carbon black (SUPER P, from available from Imerys, 4.0 wt. % of
total solids) was added to the mixture and mixed in a centrifugal
mixer at 2000 RPMs for 5 minutes. Finally, 9.0 g of hexyl
CELLOSOLVE from DOW Chemical and 3.0 g of DOWANOL PNB from DOW
Chemical was added to the composition and mixed in a centrifugal
mixer at 2000 RPMs for 5 minutes. The slurry was cast onto a
carbon-coated aluminum foil using an automatic drawdown table with
a gap height of 50 .mu.m. Samples were baked in a box oven at
60.degree. C. for 15 minutes followed by an additional bake at
246.degree. C. for 10 minutes. Samples were calendared to 35%
porosity.
[0153] Coatings at three different mass loadings were tested for
adhesion using the same method as in Example 1. The results are
included in Table 2 below.
TABLE-US-00003 TABLE 2 mass (mg/cm.sup.2) Peel Strength (N/m) 1.75
122 2.02 57 3.2 15
[0154] Adhesion of a coating is expected to decrease as the mass
loading of the coating increases. As shown in Tables 1 and 2, the
coatings produced by electrodeposition each outperform coatings
produced by drawdown in terms of 90.degree. peel strength adhesion
for coatings having similar (or even greater) mass loadings. For
example, a 2.15 mg/cm.sup.2 mass loading coating produced by
electrodeposition demonstrated a significant improvement in peel
strength relative to a lower loading level of 1.75 mg/cm.sup.2
produced by drawdown. Likewise, a coating produced by
electrodeposition having a mass loading of 3.56 mg/cm.sup.2
possessed a peel strength twice as large as the 3.2 mg/cm.sup.2
coating produced by drawdown. These results are despite the only
difference between the coating compositions of Example 3 and
Comparative Example 4 was the formulation and application for an
electrocoat in Example 3 in comparison to a formulation and
application by drawdown slurry in Comparative Example 4.
[0155] Evaluation of Coated Substrates as Electrodes in a Coin
Cell: Coin cells were fabricated from the positive electrodes
produced in Example 1 and Comparative Example 2 paired with a
lithium metal negative electrode. A ceramic coated 20 .mu.m thick
Celgard separator was used as the separator. The electrolyte was
comprised of 1.2 M LiPF.sub.6 in EC:EMC at a 3:7 ratio. The coin
cell was fabricated using 316 stainless steel casings and pairing a
1 cm diameter positive electrode with a 1.5 cm diameter lithium
anode and 60 .mu.l of electrolyte solution. Testing of the
batteries was performed on an Arbin battery tester using a single
formation step at 0.1 C followed by three cycles at each rate
specified in Table 3. Battery cycling was characterized by cycling
the batteries at 1 C after the rate study was completed.
TABLE-US-00004 TABLE 3 Table 3. Battery capacity for half-cell
lithium ion batteries cycled at a rate of 0.1 C to 1.6 C and after
50 cycles at 1.0 C. Capacity at Capacity at Capacity at Capacity at
Capacity at Capacity at 1 C after 50 Example 0.1 C 0.2 C 0.4 C 0.8
C 1.6 C cycles 1 172 169 159 136 102 13 3 172 168 158 147 125
131
[0156] The data provided in Table 3 demonstrates improved battery
performance using the electrode produced by electrodeposition of
the electrodepositable coating composition of Example 3 that
includes a crosslinking agent over the electrode produced from the
electrodepositable coating composition of Example 1 that does not
include the crosslinking agent.
[0157] Example 5--Preparation of Electrodepositable Coating
Composition and Application by Electrodeposition: To a plastic cup
was added 3.286 g of a pH-dependent rheology modifier (ACRYSOL HASE
TT-615 from DOW Chemical, 1.09 g of solid material, 3.6 wt. % of
total solids), 23.0 g of water, and 0.272 g of crosslinking agent
(CARBODILITE V-02-L2, available from Nisshinbo Chemical Inc., 0.11
g solid material, 0.40 wt. % of total solids). This mixture was
mixed in a centrifugal mixer at 2000 RPMs for 5 minutes. Next, 25.0
g (92 wt. % of total solids) of Lithium Iron Phosphate positive
electrode electrochemically active material acquired from Gelon was
added to the mixture and mixed in centrifugal mixer at 2000 RPMs
for 5 minutes. Next, 1.09 g of carbon black (SUPER P, from
available from Imerys, 4.0 wt. % of total solids) was added to the
mixture and mixed in a centrifugal mixer at 2000 RPMs for 5
minutes. The electrodepositable coating composition was diluted to
10% total solids by the addition of 219.0 g of water under constant
stirring. Electrocoat was performed as in Example 1. Depositions at
10 s, 20 s, and 30 s yielded a mass deposition rate of 0.11
mg/cm.sup.2/s.
[0158] Comparative Example 6--Preparation of Coating Composition
and Application to Substrate by Drawdown Method: To a plastic cup
was added 3.286 g of a pH-dependent rheology modifier (ACRYSOL HASE
TT-615 from DOW Chemical, 1.09 g of solid material, 3.6 wt. % of
total solids), 23.0 g of water, and 0.272 g of CARBODILITE V-02-L2
(0.40 wt. %) acquired from Nisshinbo Chemical Inc (0.11 g of solid
material). This mixture was mixed in a centrifugal mixer at 2000
RPMs for 5 minutes. Next, 25.0 g (92 wt. % of total solids) of
Lithium Iron Phosphate cathode material acquired from Gelon was
added to the mixture and mixed in centrifugal mixer at 2000 RPMs
for 5 minutes. Next, 1.09 g of carbon black (SUPER P, from
available from Imerys, 4.0 wt. % of total solids) was added to the
mixture and mixed in a centrifugal mixer at 2000 RPMs for 5
minutes. The slurry was cast onto a carbon-coated aluminum foil
using an automatic drawdown table with a gap height of 100
.mu.m.
[0159] Evaluation of Surface Energy: An electrocoated film from
Example 5 using 30 s of deposition time and the drawdown film from
Comparative Example 6 were evaluated for evaluation of surface
energy based upon a water contact angle analysis. Samples were
baked in a box oven at 245.degree. C. for 10 minutes prior to the
measurement. The contact angle of water was measured using a drop
shape analyzer (DSA 100 available from KRUSS GmbH). The measurement
procedure was performed according to ASTM D7334-08 with two
measurements being collected from three drops, per liquid. A drop
volume of 2.0 .mu.L was used. Temperature and humidity at the time
of testing were 75.degree. F. and 3%, respectively. The water
contact angle of the electrocoated film from Example 5 was
120.7.degree. and the water contact angle of the drawdown film from
Comparative Example 6 was 115.5.degree. . The water contact angle
analysis indicates that the electrocoated film of Example 5 had a
higher surface energy than the film applied by a drawdown method in
Comparative Example 6.
[0160] Example 7--Preparation of Electrodepositable Coating
Composition and Application by Electrodeposition: To a plastic cup
was added 3.49 g of a pH-dependent rheology modifier (ACRYSOL
ASE-60 from DOW Chemical, 0.98 g of solid material, 3.6 wt. % of
total solids), 23.0 g of water, and 0.272 g of crosslinking agent
(CARBODILITE V-02-L2, available from Nisshinbo Chemical Inc., 0.11
g of solid material, 0.40 wt. % of total solids). This mixture was
mixed in a centrifugal mixer at 2000 RPMs for 5 minutes. Next, 25.0
g (92 wt. % of total solids) of Lithium Nickel Manganese Cobalt
Oxide (LiNi.sub.0.6Co.sub.0.2Mn.sub.0.2O.sub.2, NCM622) positive
electrode electrochemically active material acquired from Gelon was
added to the mixture and mixed in centrifugal mixer at 2000 RPMs
for 5 minutes. Next, 1.09 g of carbon black (SUPER P, from
available from Imerys, 4.0 wt. % of total solids) was added to the
mixture and mixed in a centrifugal mixer at 2000 RPMs for 5
minutes. The slurry was diluted to 10% total solids by the addition
of 219.0 g of water under constant stir. After 30 minutes of
stirring, electrocoat was performed according to the procedure of
Example 1. Depositions at 10 s, 20 s, and 30 s yielded a mass
deposition rate of 0.91 mg/cm.sup.2/s.
[0161] Example 8--Preparation of a 0 VOC Electrodepositable Coating
Composition and Application by Electrodeposition: To a plastic cup
was added 3.286 g of a pH-dependent rheology modifier (ACRYSOL HASE
TT-615 from DOW Chemical, 1.09 g of solid material, 3.6 wt. % of
total solids), 23.0 g of water, and 0.272 g of a crosslinking agent
(CARBODILITE V-02-L2, available from Nisshinbo Chemical Inc., 0.11
g of solid material, 0.40 wt. % of total solids). This mixture was
mixed in a centrifugal mixer at 2000 RPMs for 5 minutes. Next, 25.0
g (92 wt. % of total solids) of Lithium Iron Phosphate positive
electrode electrochemically active material acquired from Gelon was
added to the mixture and mixed in centrifugal mixer at 2000 RPMs
for 5 minutes. Next, 1.09 g of carbon black (SUPER P, from
available from Imerys, 4.0 wt. % of total solids) was added to the
mixture and mixed in a centrifugal mixer at 2000 RPMs for 5
minutes. The electrodepositable coating composition was diluted to
10% total solids by the addition of 219.0 g of water under constant
stirring. After 30 minutes of stirring, electrocoat was performed
according to the procedure of Example 1. Depositions at 10 s, 20 s,
and 30 s yielded a mass deposition rate of 0.11 mg/cm.sup.2/s.
[0162] It will be appreciated by skilled artisans that numerous
modifications and variations are possible in light of the above
disclosure without departing from the broad inventive concepts
described and exemplified herein. Accordingly, it is therefore to
be understood that the foregoing disclosure is merely illustrative
of various exemplary aspects of this application and that numerous
modifications and variations can be readily made by skilled
artisans which are within the spirit and scope of this application
and the accompanying claims.
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