U.S. patent application number 11/375509 was filed with the patent office on 2007-09-20 for nanoporous polymer electrolyte.
This patent application is currently assigned to TDA Research, Inc.. Invention is credited to Brian Elliott, Vinh Nguyen.
Application Number | 20070218371 11/375509 |
Document ID | / |
Family ID | 38518242 |
Filed Date | 2007-09-20 |
United States Patent
Application |
20070218371 |
Kind Code |
A1 |
Elliott; Brian ; et
al. |
September 20, 2007 |
Nanoporous polymer electrolyte
Abstract
A nanoporous polymer electrolyte and methods for making the
polymer electrolyte are disclosed. The polymer electrolyte
comprises a crosslinked self-assembly of a polymerizable salt
surfactant, wherein the crosslinked self-assembly includes
nanopores and wherein the crosslinked self-assembly has a
conductivity of at least 1.0.times.10.sup.-6 S/cm at 25.degree. C.
The method of making a polymer electrolyte comprises providing a
polymerizable salt surfactant. The method further comprises
crosslinking the polymerizable salt surfactant to form a nanoporous
polymer electrolyte.
Inventors: |
Elliott; Brian; (Wheat
Ridge, CO) ; Nguyen; Vinh; (Wheat Ridge, CO) |
Correspondence
Address: |
CONLEY ROSE, P.C.;David A. Rose
P. O. BOX 3267
HOUSTON
TX
77253-3267
US
|
Assignee: |
TDA Research, Inc.
Wheat Ridge
CO
|
Family ID: |
38518242 |
Appl. No.: |
11/375509 |
Filed: |
March 14, 2006 |
Current U.S.
Class: |
429/307 ;
429/314; 429/316 |
Current CPC
Class: |
H01M 10/0565 20130101;
H01M 50/411 20210101; Y02P 70/50 20151101; Y02E 60/10 20130101;
H01M 8/1023 20130101; H01M 8/106 20130101; H01M 8/1067 20130101;
H01M 8/1072 20130101; Y02E 60/50 20130101; H01M 50/44 20210101;
H01M 50/403 20210101 |
Class at
Publication: |
429/307 ;
429/316; 429/314 |
International
Class: |
H01M 10/40 20060101
H01M010/40 |
Goverment Interests
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0001] This invention was made, at least in part, with funding from
the Department of Energy Contract No. DE-FG02-04ER84093.
Accordingly, the U.S. government may have certain rights in the
invention.
Claims
1. A polymer electrolyte comprising: a crosslinked self-assembly of
a polymerizable salt surfactant, wherein the crosslinked
self-assembly includes nanopores and wherein the crosslinked
self-assembly has a conductivity of at least 1.0.times.10.sup.-6
S/cm at 25.degree. C.
2. The polymer electrolyte of claim 1, wherein the polymerizable
salt surfactant has the formula: [(X)R].sub.nL(I).sub.xM where: X
is a polymerizable functional group; R is a tail group; n is an
integer signifying the number of tail groups; I is an ionic head
group; x is an integer signifying the number of ionic head groups;
L is a linking moiety that connects the one or more tail groups to
I; and M is a cationic group.
3. The polymer electrolyte of claim 2, wherein the I group
comprises an aromatic sulfonate or a fluorinated compound.
4. The polymer electrolyte of claim 3, wherein the aromatic
sulfonate comprises a nitro aniline sulfonate, an amino aniline
sulfonate, a methyl aniline sulfonate, an amino toluene sulfonate,
a benzene disulfonate, or a sulfanilyl group.
5. The polymer electrolyte of claim 3, wherein the fluorinated
compound comprises a fluorinated amino acid.
6. The polymer electrolyte of claim 5, wherein the fluorinated
amino acid comprises .alpha.,.alpha.-difluoro-.beta.-alanine.
7. The polymer electrolyte of claim 2, wherein M comprises an
alkali metal selected from the group consisting of Li.sup.+,
Na.sup.+, K.sup.+, Rb.sup.+, Cs.sup.+, and combinations
thereof.
8. The polymer electrolyte of claim 2, wherein M comprises
Li.sup.+.
9. The polymer electrolyte of claim 2, wherein M comprises an
alkaline earth metal selected from the group consisting of
Be.sup.2+, Mg.sup.2+, Ca.sup.2+, Sr.sup.2+, or Ba.sup.2+, and
combinations thereof.
10. The polymer electrolyte of claim 2, wherein M comprises a
transition metal selected from the group consisting of Ag.sup.+,
Ni.sup.2+, Ni.sup.3+, Cd.sup.3+, or Zn.sup.2+, and combinations
thereof.
11. The polymer electrolyte of claim 2, wherein X comprises an
acrylate, a methacrylate, a diene, an alkynyl group, an allyl
group, a vinyl group, an acrylamide, a hydroxyl group, a fumarate
group, an isocyanate group, or combinations thereof.
12. The polymer electrolyte of claim 2, wherein L comprises an
alkylene group, an amide group, an ether group, an amine group, an
alkene group or combinations thereof.
13. The polymer electrolyte of claim 2, wherein L comprises an
aromatic group.
14. The polymer electrolyte of claim 11, wherein the aromatic group
comprises a benzyl group, a cyclohexyl group, a halo-benzyl group,
a phenyl group, a phenacyl group, an aniline group, a benzoyl
group, a benzoyloxy group, a benzyloxycarbonyl group, a
nitrobenzoyl group, or a nitrobenzyl group.
15. The polymer electrolyte of claim 2, wherein R comprises a
hydrocarbon chain.
16. The polymer electrolyte of claim 13, wherein the hydrocarbon
chain contains between 5 and 20 carbons.
17. The polymer electrolyte of claim 2, wherein n is 3.
18. The polymer electrolyte of claim 2, wherein x is 1.
19. The polymer electrolyte of claim 1, wherein the polymerizable
salt surfactant comprises a lyotropic liquid crystal (LLC)
monomer.
20. The polymer electrolyte of claim 1, wherein the nanopores have
an average pore size in the range between about 5 Angstrom and
about 50 Angstroms.
21. The polymer electrolyte of claim 1, wherein the crosslinked
self-assembly comprises a hexagonal phase, an inverted hexagonal
phase, or combinations thereof.
22. The polymer electrolyte of claim 1, wherein the crosslinked
self-assembly comprises a cubic phase, a bicontinuous cubic phase,
or combinations thereof.
23. The polymer electrolyte of claim 1, wherein the crosslinked
self-assembly comprises a lamellar phase.
24. The polymer electrolyte of claim 1, wherein the crosslinked
self-assembly comprises a crosslinking agent selected from the
group consisting of an ethylene glycol dimethacrylate derivative,
an ethylene glycol diacrylate derivative, a methyelenebisacrylamide
derivative, or a divinylbenzene derivative.
25. The polymer electrolyte of claim 1 wherein the crosslinked
self-assembly has a conductivity of at least 1.0.times.10-5 S/cm at
25.degree. C.
26. A method of making a polymer electrolyte comprising: a)
providing a polymerizable salt surfactant; and b) crosslinking the
polymerizable salt surfactant to form a nanoporous polymer
electrolyte.
27. The method of claim 26, wherein the polymerizable salt
surfactant has the formula: [(X)R].sub.nL(I).sub.xM where: X is a
polymerizable functional group; R is a tail group; n is an integer
signifying the number of tail groups; I is an ionic head group
having a first charge; x is an integer signifying the number of
ionic head groups; L is a linking moiety that connects the one or
more tail groups to the ionic head group; and M is an ionic group
having a second charge, wherein the second charge is opposite the
first charge.
28. The method of claim 26, wherein I comprises a cation.
29. The method of claim 26, wherein I comprises phosphonium or
ammonium.
30. The method of claim 26, wherein M comprises an anion selected
from the group consisting of a hydroxyl, a halide, a benzoate, a
halogenated benzoate, a carboxylate, a halogenated carboxylate, or
an acetate.
31. The method of claim 26, wherein M comprises OH.sup.-.
32. The method of claim 26, wherein the first charge is a positive
charge.
33. The method of claim 26, wherein x is 2.
34. The method of claim 26, wherein n is 2.
35. The method of claim 26, wherein the polymerizable salt
surfactant further comprises a Gemini surfactant having the
following structure: ##STR2## wherein Y is an aliphatic group.
36. The method of claim 35, wherein Y contains between 1 to 10
carbons.
37. The method of claim 26, wherein the crosslinking the
polymerizable salt surfactant comprises photopolymerization,
thermal crosslinking, electron-beam irradiation or chemical
crosslinking.
38. The method of claim 26, wherein the providing a polymerizable
salt surfactant comprises synthesizing the polymerizable salt
surfactant.
39. The method of claim 38, wherein the synthesizing the
polymerizable salt surfactant comprises reacting an acid chloride
and a salt precursor.
40. The method of claim 39, wherein the salt precursor comprises a
sulfonate derivative selected from the group consisting of
metanilate, sulfanilate, nitro aniline sulfonate, amino aniline
sulfonate, methyl aniline sulfonate, or amino phenol sulfonate.
41. The method of claim 39, wherein the acid chloride comprises a
benzoyl derivative.
42. The method of claim 26, further comprising providing a
hydrophobic polymer and combining the hydrophobic polymer with the
polymerizable salt surfactant.
43. The method of claim 42, wherein the hydrophobic polymer
comprises butyl rubber, halobutyl rubber, butadiene rubber,
neoprene rubber, styrene-butadiene rubber, poly(propylene oxide),
poly(vinylchloride), poly(propylene), poly(ethylene),
poly(acrylates), poly(methacrylates), poly(styrene), poly(amides),
polyesters, poly(lactic acid), poly(glycolic acid), or combinations
thereof.
44. The method of claim 26, further comprising providing a
crosslinking agent selected from the group consisting of an
ethylene glycol dimethacrylate derivative, an ethylene glycol
diacrylate derivative, a methyelenebisacrylamide derivative, or a
divinylbenzene derivative.
45. The method of claim 26, further comprising casting the
polymerizable surfactant on to a substrate to form a film or
coating.
46. The method of claim 45, further comprising dissolving the
polymerizable surfactant in a solvent selected from the group
consisting of acetone, tetrahydrofuran, acetonitrile, hexane,
water, dichloromethane, ethyl acetate, toluene or chloroform before
casting the polymerizable surfactant on the substrate.
47. The method of claim 45, wherein the substrate comprises a
metal, a polymer, a composite, or combinations thereof.
48. The method of claim 45, wherein the substrate comprises a
macroporous polymer membrane support.
49. The method of claim 26, further comprising pouring the
polymerizable surfactant into a mold.
50. A battery comprising a nanoporous polymer electrolyte, wherein
the nanoporous polymer electrolyte comprises a crosslinked
self-assembly of a polymerizable surfactant having a conductivity
of at least 1.times.10.sup.-6 S/cm at 25.degree. C.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0002] Not applicable.
BACKGROUND
[0003] 1. Field of the Invention
[0004] This invention relates generally to the field of polymer
electrolytes. More specifically, the invention relates to the use
of polymerizable salt surfactants as a nanoporous polymer
electrolyte.
[0005] 2. Background of the Invention
[0006] Many portable electronic devices as well as electric, hybrid
and fuel cell vehicles require high performance rechargeable
batteries. Presently, lithium batteries are the battery of choice
due to its high energy density and power. The key to market success
for electric vehicles is the energy storage device, which limits
driving distance and acceleration. Rechargeable lithium batteries
are the most promising technology for storing energy and delivering
it on demand for electric vehicles because lithium batteries
potentially have high energy densities (400 Wh/kg) and high power
densities (800 W/kg), and therefore can meet, in principle, all of
the performance requirements.
[0007] One aspect of the lithium battery assembly that needs to be
improved in order to make rechargeable battery performance suitable
for applications such as electric vehicles is the electrolyte. The
electrolyte usually comprises a separator material and the
electrolyte itself. The separator material allows lithium ion
exchange, but prevents electrical conduction between the anode and
cathode. The electrolyte is generally a lithium salt (such as
LiCF.sub.3SO.sub.3 or LiPF.sub.6) dissolved in an organic solvent
(for example ethylene carbonate and propylene carbonate), while the
separator material is usually a polymer, although there are many
variations, ranging from solvent in polymer "gels" to solvent-free
polymer electrolytes. Solvent-based batteries often contain
flammable liquid and are potentially unsafe. Additionally, solvents
tend to participate in undesired reactions at the battery
electrodes and can leak out of the casing.
[0008] Conversely, solvent-free polymer systems, such as
polyethylene oxide (PEO) with lithium salts are safer, but have
inherently low ionic conductivity, especially at low temperatures
(i.e. lower than 10.sup.-8 S/cm at -40.degree. C.). It is desirable
to have an electrolyte/separator material for battery systems (in
electric vehicles for example) that is polymeric, has a high
Li.sup.+ capacity (concentration) and a usefully high Li+
conduction at temperatures ranging from -40 to 85.degree. C.
[0009] Most polymer electrolytes developed to date have been based
primarily on alkyl-ethers such as polyethylene oxide (PEO) modified
with lithium salts. These electrolytes are not stable enough to be
used with metallic lithium anodes. Resistive layers form at the
interface due to mobility of anions, and lithium metal particles
and dendrites form upon charging and discharging (which then
migrate into the soft polymer electrolytes and form short
circuits). Additionally, these electrolytes are dual ion conductors
where ionic conduction is dominated by the anion and lithium
transport accounts for only 30 to 50% of the total ionic
conduction. In this type of electrolyte, ion conduction depends
primarily on polymer segmental motion (i.e. thermal motion).
However, polymer segmental motion is a function of temperature and
the conductivity is significantly reduced at low temperature as the
polymer motion decreases. Low temperature conductivity can be
improved by adding non-aqueous liquid additives to the electrolyte,
but this in not practical due to concerns about dimensional
stability and leakage.
[0010] Consequently, there is a need for in the art for a polymer
electrolyte that exhibits good room temperature conductivity and
very little decrease in conductivity at low temperatures, without
the addition of volatile solvents or plasticizers.
BRIEF SUMMARY
[0011] These and other needs in the art are addressed in one
embodiment by a polymer electrolyte comprising a crosslinked
self-assembly of a polymerizable salt surfactant, wherein the
polymer electrolyte includes nanopores and wherein the polymer
electrolyte has a conductivity of at least 1.0.times.10.sup.-6 S/cm
at 25.degree. C.
[0012] In another embodiment, these and other needs in the art are
addressed in a method of making a polymer electrolyte comprising
providing a polymerizable salt surfactant. The method further
comprises crosslinking the polymerizable salt surfactant to form a
nanoporous polymer electrolyte.
[0013] The present invention relates to a dimensionally stable fast
ion conductor that does not depend on polymer segmental motion for
ion transport. Thus, it can operate over a wide temperature range,
such as, for example, -40 to 85.degree. C. The ion transport is
facilitated by site-to-site hopping between extremely closely
spaced and ordered anion sites. As a result, this material has good
low temperature ionic conductivity. The conductivity remains
virtually unchanged over this temperature range. In contrast,
present polymer electrolytes lose several orders of magnitude in
conductivity over the same temperature range.
[0014] The present polymerizable surfactants may be used to form a
polymer electrolyte that includes nanostructures such as nanopores.
Preferred nanostructures provide closely spaced lithium binding
sites. The close proximity of the binding sites provides rapid
site-to-site transfer of the lithium ions resulting in higher ionic
conductivity. These lithium electrolytes may be made from pure
polymerizable surfactants, composites of surfactants with other
polymers and even mixtures of polymerizable surfactants.
[0015] The foregoing has outlined rather broadly the features and
technical advantages of the present invention in order that the
detailed description of the invention that follows may be better
understood. Additional features and advantages of the invention
will be described hereinafter. It should be appreciated by those
skilled in the art that the concepts and the specific embodiments
disclosed herein may be readily utilized as a basis for modifying
or designing other structures for carrying out the same purposes of
the present invention. It should also be realized by those skilled
in the art that such equivalent constructions do not depart from
the scope of the invention as set forth in the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] For a detailed description of the preferred embodiments of
the invention, reference will now be made to the accompanying
drawings in which:
[0017] FIG. 1 illustrates an embodiment of the polymer electrolyte
as a separator membrane in a lithium rechargeable battery;
[0018] FIG. 2 illustrates a close-up view of a nanoporous,
self-assembled polymer membrane for use in lithium ion
batteries;
[0019] FIG. 3 illustrates the process by which polymerized
surfactants self-assemble;
[0020] FIG. 4 illustrates various embodiments of lyotropic liquid
crystal assemblies;
[0021] FIG. 5 illustrates the X-ray diffraction of a hexagonal
structure;
[0022] FIG. 6 illustrates the structure of a cubic phase;
[0023] FIG. 7 illustrates the self-assembly process for forming
nanostructured materials from polymerizable surfactants;
[0024] FIG. 8 illustrates the preparation of a lithium sulfanilate
salt monomer;
[0025] FIG. 9 is an X-ray diffraction spectrum of a lithium
sulfanilate salt monomer;
[0026] FIG. 10 illustrates the preparation of a sulfanilic acid
polymerizable surfactant;
[0027] FIG. 11 is an X-ray diffraction spectrum of the sulfanilic
acid polymerizable surfactant;
[0028] FIG. 12 illustrates the preparation of a polymerizable
sodium sulfanilate surfactant;
[0029] FIG. 13 is an X-ray diffraction spectrum of a sodium
sulfanilate salt monomer described in Example 2;
[0030] FIG. 14 shows the equivalent circuit used to analyze the
electro impedance spectroscopy (EIS) data;
[0031] FIG. 15 is the Nyquist plot for the data obtained by EIS for
the polymer electrolyte described in Example 4, part A;
[0032] FIG. 16 is the Nyquist plot for the data obtained by EIS for
the polymer electrolyte described in Example 4, part B;
[0033] FIG. 17 illustrates the initial preparation of a bromo diene
precursor for synthesis of a polymerizable surfactant with diene
functional groups;
[0034] FIG. 18 illustrates the preparation of a polymerizable
surfactant with diene functional groups;
[0035] FIG. 19 shows examples of cubic phase forming surfactants
and analogous cubic phase forming polymerizable surfactants;
[0036] FIG. 20 show example of additional polymerizable surfactants
that could form the cubic phase;
[0037] FIG. 21 illustrates polymerizable surfactants that have
fluorinated head groups;
[0038] FIG. 22 shows examples of anionic surfactants;
[0039] FIG. 23 shows an example of a "Gemini" surfactant with
phosphonium head groups.
NOTATION AND NOMENCLATURE
[0040] Certain terms are used throughout the following description
and claims to refer to particular system components. This document
does not intend to distinguish between components that differ in
name but not function.
[0041] In the following discussion and in the claims, the terms
"including" and "comprising" are used in an open-ended fashion, and
thus should be interpreted to mean "including, but not limited to .
. . ".
[0042] The term "nanopores" or "nanoporous" refers to structured
channels on the scale of 1 to 100 nm, which are capable of
transporting ions.
[0043] The term "battery" means any device that is capable of
storing energy and making it available in electrical form.
[0044] The term "polymerizable" describes a chemical compound
capable of forming a polymeric compound.
[0045] The term "transference number" means the total fraction of
charge carried across the battery separator by either the cations
or the anions participating in the energy-providing electrochemical
reactions. A transference number of 1.0 means that only the
participating ions are being transported across the separator.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0046] FIG. 1 illustrates an application of a nanoporous polymer
electrolyte 12 in a battery 10. The polymer electrolyte 12 may be
placed between an anode 14 and a cathode 16. Anode 14 may comprise
a metal oxide such as lithium oxide, lithium cobalt oxide, lithium
manganese oxides, lithium metal oxides doped with other trace
metals, or any other suitable anode material. Cathode 16 may
comprise a metal oxide, carbon black, and a binder. The battery may
be flanked by current collectors 30 and 32. The current collectors
may comprise any suitable metal such as copper or aluminum.
[0047] In certain embodiments, the polymer electrolyte 12 may
comprise a self-assembling polymerizable surfactant 20. In specific
embodiments, the polymerizable surfactants may contain a negatively
charged or anionic head-group and one or more hydrophobic tails
that may be covalently bonded by a polymerization reaction. Each
hydrophobic tail may comprise a functional group that may be
polymerizable. Because the charged sites are crosslinked into the
polymer membrane via a polymerization reaction, only positively
charged can ions be transported. Because the self-assembled
molecules provide closely spaced and ordered anion sites, the
membrane material may have a transport/transference number of near
1.0. In particular embodiments, the polymerizable surfactant may
possess novel characteristics that allow it to self assemble into
nanostructured phases and form nanopores 18. Polymers having
substantially uniform nanopore sizes may be synthesized with pore
diameters in a range between about 1 Angstrom to about 50
Angstroms.
[0048] The polymerizable surfactants described in the invention
provide a dimensionally stable fast ion conductor that does not
depend on polymer segmental motion for ion transport. Instead, ion
transport in the present polymer is facilitated by site-to-site
hopping between the extremely closely spaced and ordered ion sites.
The close proximity of the binding sites in the present polymers
allows rapid site-to-site transfer of ions, resulting in higher
ionic conductivity. As a result, this material can operate over a
wide temperature range and has good low temperature ionic
conductivity. The conductivity may remain virtually unchanged or
may only change slightly over a wide temperature range
[0049] The polymerizable surfactant from which the electrolyte is
formed may comprise a lyotropic liquid crystal (LLC) monomer.
Lyotropic liquid crystal (LLC) mesogens or monomers are amphiphilic
molecules containing one or more hydrophobic organic tails and a
hydrophilic headgroup. The amphiphilic character of these molecules
encourages them to self-organize into aggregate structures, with
the tails forming hydrophobic regions and the polar headgroups
defining the interface of phase-separated domains. These aggregates
may be relatively simple individual structures such as micelles and
vesicles or highly ordered yet fluid condensed assemblies with
specific nanometer-scale geometries known collectively as LLC
phases (FIG. 4).
[0050] LLC phases are well-suited for the production of
nanostructured organic materials. Their architectures may
incorporate hydrophobic and hydrophilic (or charged) compounds in
separate domains with well-defined nano-scale geometries, and may
be especially attractive for the production of nanostructured
materials, with only the caveat that LLC phases are inherently
fluid and therefore lack the robustness required for most materials
applications. Thus, the electrolyte materials of the present
invention may use polymerizable LLC surfactants to form nanoporous
polymers.
[0051] Polymerizable or crosslinkable LLC mesogens may solve the
problem caused by the fluid nature of LLC assemblies. Polymerizable
surfactants may comprise molecules having a pair of hydrophobic and
hydrophilic components together with one or more polymerizable
groups in their structure. These polymerizable surfactants may be
used to form surfactant phases to produce useful materials with
highly regular nano-scale architectural features (i.e. pores,
etc.).
A. Polymer Electrolyte Composition
[0052] Generally, embodiments of a nanoporous polymer electrolyte
may comprise a polymerizable LLC salt surfactant with the following
structure, [(X)R].sub.nL(I).sub.xM where:
[0053] X may be any suitable polymerizable functional group;
[0054] R may be any suitable tail group;
[0055] n may be an integer signifying the number of tail
groups;
[0056] I may be any suitable ionic head group having a first
charge;
[0057] x may be an integer signifying the number of ionic head
groups;
[0058] L may be a linking moiety that connects the one or more tail
groups to the anion head group; and
[0059] M may be any ion having a second charge, wherein the second
charge is opposite the first charge.
[0060] The ionic head group on the surfactant, I, may comprise an
anionic head group including without limitation sulfonates,
fluorinated sulfonates, aromatic sulfonates, and substituted
aromatic sulfonates. In particular embodiments, the anionic head
group may comprise a benzene sulfonate derivative. The benzene
sulfonate derivatives may comprise any number and type of
substituents on the benzene ring. Examples of benzene sulfonate
derivatives include without limitation, nitro aniline sulfonate,
amino aniline sulfonate, methyl aniline sulfonate, amino phenol
sulfonate, metanilate, or sulfanilate. Further examples of
substituents that may be incorporated into the benzene sulfonate
derivative include without limitation, alkyl groups, halogens,
carbonyls, hydroxyls, etc. The number of ionic groups, x, is
limited only by the number of available linking site on the L
group. However, in many embodiments, x will equal 1.
[0061] The ionic head group may also comprise any suitable anionic
fluorinated head groups. Examples of fluorinated anionic head
groups include without limitation, amino difluorocarboxylates,
fluorinated alkyl sulfonates, or fluorinated amino acids. Without
being limited by theory, it is believed that using polymerizable
surfactants with a sulfonated or fluoronated head group may result
in a sufficiently higher degree of cation dissociation due to the
electron withdrawing nature of the aromatic ring resulting in
higher room temperature conductivity. In embodiments where the head
group is anionic, the surfactant serves as a cation conductor.
[0062] In an alternative embodiment, I may comprise a cationic head
group. Examples of suitable cationic head groups include without
limitation, phosphonium or ammonium. In such embodiments, the
resulting polymer serves as an anion conductor. In certain
embodiments with cationic head groups, a "Gemini" structure may be
formed, in which the surfactant comprises two cationic head groups
and two tail groups, R (See FIGS. 22 and 23). In such cases, the
cationic surfactant may have the following general Gemini
structure: ##STR1##
[0063] Y may be any group capable of connecting the ionic head
groups. Generally, Y may comprise an aliphatic chain or group. The
chain may comprise from 1 to 10 carbon atoms, alternatively 6
carbon atoms. Other examples of suitable Y groups include without
limitation, alkanes, alkenyl chains, aromatics, and combinations
thereof.
[0064] The I group may have a first charge that is positive or
negative. The first charge may comprise any amount of charge such
as 1+, 2+, 3+, 1-, 2-, 3-, etc. In preferred embodiments, the I
group has either a 1+ or 1- charge. The M group preferably has a
second charge that is the opposite of the first charge. In other
words, if the I group comprises a positive charge, the M group
comprises a negative charge. The amount of the first charge does
not necessarily have to be equal to the second charge. In
particular embodiments, the M group may comprise a charge that is
greater than 1+ or less than 1- and the I group may comprise a 1+
or 1- charge. In such embodiments, a plurality of surfactants may
share each M group. By way of example only, the M group may be
Mg.sup.2+ and the I group may be an aromatic sulfonate with a 1-
charge. In this case, two surfactants with a 1- charge may share a
single Mg.sup.2+ cation.
[0065] The linking moiety, L, may comprise any appropriate group or
molecule that is capable of connecting I with the one or more tail
groups. In some embodiments, L may comprise a single alkylene group
or a multiple alkylene chain. i.e., (--CH.sub.2--).sub.n. In other
embodiments, L may comprise an ether linkage, i.e., --CH2-O--CH2-.
Furthermore, L may comprise an amine linkage group, i.e., --NH--.
In select embodiments, L may comprise a cyclic or aromatic group.
In particular, L may comprise a benzyl group, a cyclohexyl group, a
halo-benzyl group, a phenyl group, a phenacyl group, an aniline
group, a benzoyl group, a benzoyloxy group, a benzyloxycarbonyl
group, a nitrobenzoyl group, or a nitrobenzyl group. Moreover, L
may comprise combinations or derivatives of the aforementioned
linkers.
[0066] R may comprise any suitable hydrophobic tail group. For
example, R may comprise a hydrocarbon chain containing between 1
and 30 carbon atoms, alternatively between 5 and 20 carbons, or
between 8 and 15 carbons. R may also comprise an unsaturated
hydrocarbon chain of alkenyl groups, i.e., (--CH.dbd.CH--). R may
optionally comprise various combinations of heteroatoms and
functional groups such as ether linkages (O), amine linkages
(--NH--), amide linkages (--NH--CO--), carbonyl linkages (--CO--),
and combinations thereof.
[0067] In addition, the LLC salt surfactant may comprise one or
more RX groups. In other words, n may equal 1, 2, 3, etc.
Typically, the LLC salt surfactant will include three RX tail
groups. In other embodiments, the polymerizable surfactant may
comprise two tail groups. The number of tail groups, RX, is
typically limited only by the number of linkages available to L,
the linking moiety. In certain embodiments with more than one tail
group, each R group may comprise different chain lengths.
[0068] When I comprises an anionic head group, M may comprise any
cation capable of forming a salt. Suitable cations include alkali
metals such as Na.sup.+, Li.sup.+, K.sup.+, Rb.sup.+, or Cs.sup.+
cations. Other suitable cations may also comprise an alkaline earth
metal including without limitation, Be.sup.2+, Mg.sup.2+,
Ca.sup.2+, Sr.sup.2+, or Ba.sup.2+ cations. Additionally, M may
comprise a transition metal cation including without limitation,
Ag.sup.+, Ni.sup.2+, Ni.sup.3+, Cd.sup.3+, or Zn.sup.2+. In other
embodiments, the cation may comprise protons, H.sup.+.
Alternatively, M may comprise an anion when I comprises a cationic
head group. Examples of suitable anions include without limitation,
hydroxyls, halides, acetates, carboxylates, halogenated
carboxylates, polyoxymetalates, or benzoates. For example, M may
comprise OH.sup.- or Br.sup.-.
[0069] X may comprise any polymerizable functional group. As
defined herein, polymerizable functional group means any chemical
moiety that is capable of being crosslinked or covalently bonded
with another chemical moiety with some form of initiation. Examples
of appropriate functional groups include without limitation,
acrylates, methacrylates, dienes, alkynyl groups, allyl groups,
vinyl groups, acrylamides, hydroxyl groups, fumarate groups,
isocyanates, styrenes, terminal olefins, or combinations thereof.
In embodiments where the LLC monomer comprises more than one tail
group, R, the polymerizable functional group, X, may be the same
for each tail group. In other embodiments, X may be different for
each tail group, R.
[0070] The LLC salt surfactant may be synthesized by any reaction
pathway known to one skilled in the art. However, the polymerizable
salt surfactant generally may be synthesized from the reaction of
an acid chloride with a salt precursor. The acid chloride may
comprise a benzoyl chloride derivative. According to one
embodiment, the acid chloride may be synthesized from the reaction
of a benzoic acid derivative with a chloride compound. For example,
a benzoic acid derivative may be reacted with thionyl chloride.
Another example of chlorides that may be used is oxalyl
chloride.
[0071] The salt precursor generally comprises a sulfonate
derivative and a cation. The sulfonate derivative may generally
have the same structure as the eventual I group in the
polymerizable salt surfactant product. Examples of suitable
sulfonate derivatives include without limitation, metanilate,
sulfanilate, nitro aniline sulfonate, amino aniline sulfonate,
methyl aniline sulfonate, or amino phenol sulfonate. In alternative
embodiments, the salt precursor may comprise a fluorinated amino
acid derivative with a base. An example of a fluorinated amino acid
derivative includes .alpha.,.alpha.-difluoro-.beta.-alanine. The
base typically may contain the desired M.sup.+ cation. As an
example, a salt precursor may comprise a lithium cation and a
sulfanilate (see Example 1).
[0072] The nanoporous structure of the electrolyte forms
spontaneously because lyotropic liquid crystals or polymerizable
surfactants self-assemble into complex and highly ordered molecular
assemblies. The LLC amphiphiles may aggregate into the same types
of assemblies as their non-polymerizable analogues, but may also be
capable of being covalently linked to their nearest neighbors in
situ to form robust polymer networks that retain the original
structure. Micelles, inverse micelles, and microemulsions may be
polymerized with retention of phase microstructure. Lamellar
assemblies such as vesicles, lipid microtubules and the lamellar
(L) phase may also be successfully polymerized. Several complex
phases may also be polymerized, including the normal hexagonal
phase (HI), the inverted hexagonal phase (HII), and the
bi-continuous cubic (QII, Pn3m) phase.
[0073] Some typical phases that lyotropic liquid crystals may form
are shown in FIG. 4. In some embodiments, the LLC salt monomer may
form inverted hexagonal 50 and bi-continuous cubic phases 60; of
which both phases may form continuous porous pathways for cation
transport. A porous polymer film of the inverted hexagonal phase 50
may have pore channels 52 aligned randomly (see FIG. 4), but with
enough of them aligned roughly normal to the surface of the film to
form continuous diffusion pathways for cations (see FIG. 1). The
bi-continuous cubic phase 60 may form a 3-dimensional network of
interconnected pores 62. However, specific alignment of the pores
is not required in order to form continuous channels.
[0074] The phase structure (self-assembled crystal structure) may
be evaluated using x-ray diffraction. The inverted hexagonal
structure (and hexagonal structures in general) generates a
characteristic X-ray diffraction pattern. For hexagonal phases, the
d.sub.100 plane and the d.sub.110 plane generate X-ray reflections
at an interval of 1 .times. : .times. 1 3 .times. : .times. 1 4
.times. : ##EQU1## etc. FIG. 5 illustrates the x-ray scattering for
a hexagonal crystal structure. Lamellar structures exhibit x-ray
reflection at intervals of 1:1/2:1/3: etc. Cubic phases exhibit
x-ray reflections at intervals of 1 6 .times. : .times. 1 8 .
##EQU2## There are several geometric variations of the cubic phase.
A typical structure is shown in FIG. 6. X-ray diffraction allows
for unequivocal confirmation of the phase structure and is
particularly useful for distinguishing between lyotropic liquid
crystals in the lamellar, hexagonal and cubic phases. B. Polymer
Electrolyte Fabrication
[0075] The polymerizable LLC salt surfactants of the present
invention may be crosslinked or polymerized into a variety of
configurations to form a polymer electrolyte. The polymerizable
surfactants may be crosslinked in a mold to form a desired shape.
In another embodiment, the polymerizable surfactants may be cast as
a film or coating on to any substrate and crosslinked to form the
polymer electrolyte. Examples of suitable substrates include
without limitation, steel, metal, polymer, composites, or
combinations thereof. In another embodiment, the polymerizable
surfactants may first fill or partially fill the pores of a
macroporous polymer membrane support and then may be crosslinked to
form the polymer electrolyte. The polymerizable surfactant may be
dissolved in a suitable solvent to create a casting solution.
Examples of suitable solvents include without limitation,
tetrahydrofuran, acetonitrile, hexane, acetone, water,
dichloromethane, ethyl acetate, toluene or chloroform. Once cast on
to the substrate, the solvent may be allowed to evaporate leaving
the polymerizable surfactant film. The polymerizable surfactant may
be cast by any means such as wet-film draw down, spraying, dip
coating, or spin coating. The film may then be crosslinked by a
variety of methods.
[0076] In particular embodiments, the polymerizable surfactant
self-assemblies may be polymerized or crosslinked to form a solid,
nanoporous polymer electrolyte. In some embodiments, the LLC
monomer or polymerizable salt surfactant may be photopolymerized by
irradiation with light over a wide temperature range. The
wavelength of light that may be used to crosslink the polymer
electrolyte may range from about 300 nm to about 500 nm. In
particular, UV light may be used. The photopolymerization may be
facilitated by the addition of a photoinitiator. Examples of
suitable photoinitiators include without limitation, benzophenone,
isopropyl thioxanthone, benzyl dimethyl ketal, acylphosphine
oxides, or combinations thereof. Alternatively, the polymerizable
LLC salt monomers may be crosslinked using a chemical initiator.
Examples of suitable chemical initiators include without limitation
benzoyl peroxide ammonium persulfate, or peroxides. In other
embodiments, the salt monomers may be crosslinked via thermal
crosslinking, i.e., the application of heat. For thermal
crosslinking, a thermally activated initiator may be used such as
2-2'-azo-bis-isobutyrylnitrile (AIBN). In yet other embodiments,
the polymerizable surfactants may be crosslinked via electron-beam
irradiation.
[0077] In further embodiments, a crosslinking agent may be added to
the polymerizable salt surfactant to increase the crosslinking
density and/or mechanical properties of the polymer electrolyte.
However, it is to be understood that the polymerizable surfactant
may be crosslinked without the need for either crosslinking agent
or initiator. The crosslinking agent may comprise any compounds
having polymerizable functional groups. Examples of suitable
crosslinking agents include without limitation, ethylene glycol
dimethacrylate derivatives, ethylene glycol diacrylate derivatives,
methyelenebisacrylamide derivatives, divinylbenzene, or
combinations thereof.
[0078] The polymer electrolytes formed by the above methods are
expected to have conductivities at 25.degree. C. of at least
1.times.10.sup.-6 S/cm, more preferably at least 2.times.10.sup.-6
S/cm, and still more preferably at least 1.times.10.sup.-5 S/cm. At
-35.degree. C., the present polymer electrolyte are expected to
have conductivities of at least 1.times.10.sup.-6 S/cm, more
preferably at least 2.times.10.sup.-6 S/cm, and still more
preferably at least 1.times.10.sup.-5 S/cm.
[0079] The mechanical properties of the polymer electrolyte may be
modified by making composites of hydrophobic polymers and lyotropic
liquid crystals or polymerizable surfactants. By way of example
only, linear polymers may be incorporated into the structures
formed by the polymerizable surfactants. Examples of linear
polymers include, without limitation, butyl rubber, halobutyl
rubber, butadiene rubber, neoprene rubber, styrene-butadiene
rubber, poly(propylene oxide), poly(vinylchloride),
poly(propylene), poly(ethylene), poly(acrylates),
poly(methacrylates), poly(styrene), poly(amides), polyesters,
poly(lactic acid), poly(glycolic acid), or combinations thereof.
The resulting material may be more flexible than the polymerized
surfactants without linear polymers.
[0080] To further illustrate various illustrative embodiments of
the present invention, the following examples are provided.
EXAMPLE 1
Preparation of Lithium Sulfanilate Salt Monomer
[0081] This example details the preparation of a polymerizable
surfactant containing a lithium salt headgroup, which may be used
to make polymer lithium electrolytes.
Preparation of Acid Chloride Precursor
[0082] First, an acid chloride is prepared as depicted in step 1 of
FIG. 1. All glassware was heated in an oven at 110.degree. C. for 2
hours, and all anhydrous solvents were further dried with molecular
sieves and purged with argon for 10 min, prior to the synthesis.
First, 3,4,5-tris(11'-acryloyloxyundecyloxy)benzoic acid (1.09 g,
1.3 mmol) and a trace amount of 2,6-di-tert-butyl-4-methylphenol
stabilizer were dissolved in anhydrous CH.sub.2Cl.sub.2 (25 mL) in
a 50 mL Schlenk flask under an argon atmosphere. Thionyl chloride
(0.57 mL, 7.8 mmol) was then injected by syringe directly into the
solution with constant stirring. The flask was covered with
aluminum foil, and the mixture was continually stirred for an
overnight.
[0083] The solvent and the excess thionyl chloride were then
removed under reduced pressure at room temperature for 4 h (using a
water bath to obtain room temperature and an additional trap to
isolate thionyl chloride) to afford a yellow oil. This oil was used
as the starting material in the final step.
Preparation of Sulfanilate Lithium Salt Precursor
[0084] Next, a sulfanilate lithium salt precursor is prepared
according to step 2 in FIG. 8. Sulfanilic acid (1.35 g, 7.8 mmol)
and LiOH (0.187 g, 7.8 mmol) were added in water (10 mL) with
constant stirring. This step results in an available lone pair of
electrons on the amino group to react with the acid chloride at the
next and final step. After stirring 20 min, the clear solution was
then dried in vacuum overnight to obtain a dried sulfanilate
lithium salt precursor. The solid was used as the starting material
in the final step.
[0085] Once the lithium salt precursor and the acid chloride are
prepared, the lithium sulfanilate salt monomer can be synthesized
as shown in step 3 of FIG. 8. The prepared acid chloride oil from
step 1 was dissolved in THF (100 mL, regular grade). Potassium
carbonate (1.08 g, 7.8 mmol) was then added to the solution to
neutralize any inorganic acidic products from step 1. The mixture
was stirred for 10 minutes. Next, sulfanilate lithium salt
precursor (prepared from step 2) was added, and the mixture was
heated to reflux (65.degree. C.) in air overnight. Lastly, the
insoluble solid was filtered and discarded. The clear pale yellow
solution was then dried using rotary evaporator. The solid product
was further dried under reduced pressure at room temperature for 48
h to afford a pure lithium sulfanilate salt monomer. The lithium
salt product (about 1 g) was then dissolved in chloroform
containing 5 wt % 1-hydroxycyclohexylphenylketone (7 g, w 0.536%)
to make up the casting solution mixture (w 12.5%) for casting films
of the lithium electrolyte.
[0086] A sample of the lithium sulfanilate salt monomer was
prepared for X-ray diffraction to identify if any liquid crystal
order was present. The X-ray diffraction (XRD) spectrum in FIG. 9
indicates that there is most likely hexagonal ordering with a
d.sub.100 repeat distance of 37 Angstroms. Without any secondary
peak, it was not possible to unequivocally identify the crystal
structure, However, the d.sub.100 spacing was much closer to that
of an analogous sodium salt (see example 3) of 35.5 than the
lamellar phase of the acid, which had a primary spacing of 43.5
(see example 2/step 2). Based on geometric arguments, the structure
of the lithium sulfanilate salt monomer was most likely
hexagonal.
EXAMPLE 2
Preparation of a Sodium Sulfanilate Headgroup Polymerizable
Surfactant
[0087] This sodium sulfanilate surfactant is a variation of the
lithium polymerizable surfactant in Example 1. The XRD spectrum of
this sulfanilic acid polymerizable surfactant was used to help
identify the phase structure for the material in Example 1.
[0088] The acid chloride precursor was identical to the compound
described in step 1 of Example 1. To prepare the sodium sulfanilate
salt monomer, the prepared acid chloride oil was dissolved in THF
(100 mL, Aldrich 178810) (see FIG. 10). Potassium carbonate (1.08g,
7.8 mmol) was then added to the solution to neutralize any
inorganic acidic products from previous step. The mixture was
stirred for 10 minutes. Next, sulfanilate sodium salt (1.52 g, 7.8
mmol, Aldrich 251283) was added, and the mixture was heated to
reflux (65.degree. C., in air) overnight. The insoluble solid
(excess potassium carbonate and sulfanilate sodium salt) was then
filtered and discarded. The clear pale yellow solution was finally
acidified by passing through a column packed with acidic
ion-exchange resin in the following step.
[0089] A sample of the sodium sulfanilate salt monomer was prepared
for X-ray diffraction to identify if any liquid crystal order was
present. The following X-ray diffraction spectrum indicates that
there is a clear hexagonal ordering (inverted hexagonal based on
geometry of the surfactant) with a d100 spacing distance of 38.5
Angstroms (secondary peak at 23.5 roughly 1/ 3*38.5).
EXAMPLE 3
Preparation of the Sulfanilic Acid Liquid Crystal Monomer
[0090] The liquid crystal monomer may be synthesized by running the
sodium polymerizable surfactant of Example 2 through an
ion-exchanger resin. The sodium sulfanilate surfactant was
synthesized by following steps 1 and 2 in Example 2.
[0091] The acidic ion-exchange column was prepared from AG 50W-X8
Resin (100 g, Bio-Rad, 143-5451) in THF. The resin was first
stirred in a solution of HCl (200 mL, 6M) for 3 h. The first HCl
solution was then removed, and the resin was continually stirred in
a second solution of HCl (200 mL, 6M) for 3 h. The second HCl
solution was then removed, and the resin was finally stirred in a
third solution of HCl (200 mL, 6M) for 12 h. The slurry gel was
then packed in a column (3 cm diameter), washed with excess water
to remove HCl, and then washed with THF (150 mL) to completely
remove water from the column. Next, the sodium salt solution in THF
was passed through the acidic ion-exchange resin. The THF was
finally removed under vacuum at about 40.degree. C. to collect an
oily liquid. The oil was further dried under reduced pressure at
room temperature to afford a pure sulfanilic acid monomer as a pale
yellow solid.
[0092] A sample of the sulfanilic acid liquid crystal monomer was
prepared for X-ray diffraction to identify if any liquid crystal
order was present. The following X-ray diffraction spectrum
indicates that there is some lamellar ordering with a repeat
distance of 43.5 Angstroms (secondary peak at 23.0 roughly
1/2*43.5, and tertiary peak at 15.9 roughly 1/3*43.5). The matching
of the secondary and tertiary peaks did not exactly line up with
the expected lamellar peaks, but they were closer to lamellar than
the other possible phase, hexagonal. There were also additional
peaks indicating crystal ordering.
EXAMPLE 4
Casting and Testing Lithium Electrolyte Films
Polyethylene Oxide, PEO, Lithium Salt Films
[0093] Lithium salt and PEO solutions were wet cast onto stainless
steel sheets (2 mm thickness) using a 4-mil draw down knife. The
solutions contained 21.4% solids and therefore the 4 mil wet films
dried leaving a 0.856 mil coating. (Equivalent to 21.4 .mu.m
coatings). The solvent was evaporated under ambient room conditions
in a fume hood.
[0094] Specifically, lithium trifluoromethanesulfonate (1 g, 6.41
mmol) was dissolved in 5 mL of THF. In another container,
poly(ethylene oxide) (6.41 mL, 7.24 g, Mv=100,000 amu) was
dissolved in 25 mL of CHCl.sub.3. The two solutions were then mixed
and the THF was evaporated to form a 1M CF.sub.3SO.sub.3Li in PEO
electrolyte.
[0095] The electrolyte and solvent solution was then coated onto a
stainless steel shim (2-mil thickness) using a 4-mil draw-bar. A
piece of coated stainless steel (area=1 cm.sup.2) was assembled
into CR2025 coin cell battery parts using an internal wave spring
and spacer disk to insure proper contact with both ends of the
battery coin cell. The electrolyte film contained in the stainless
steel battery assembly was tested using potentiostatic electrical
impedance spectroscopy (EIS).
[0096] An equivalent circuit was used to evaluate the electrolyte
resistance (FIG. 14). R.sub.E is the electrolyte (ionic)
resistance, R.sub.T is the charge transfer resistance and C is the
capacitance (at low frequency).
[0097] Based on the equivalent circuit, the model fit to the data
gave the following values: R.sub.E=2339.OMEGA.,
RT=1.17*10.sup.5.OMEGA., and C=2.19*10.sup.-10 F. The Nyquist plot
of the data is shown in FIG. 15.
[0098] The electrolyte conductivity is calculated using the
equation: .sigma.=t/(A*R.sub.E), where t is the thickness of
electrolyte film, and A is the area of the electrolyte film. Thus
for t=0.00214 cm and A=1 cm.sup.2, .OMEGA.=9.times.10.sup.-7 S/cm
(at 22.degree. C.). This is consistent with published values for
lithium conductivity in PEO in the absence of any solvent or
plasticizer [Handbook of Batteries, 3rd Ed., David Linden and
Thomas B. Reddy, editors, McGraw-Hill, New York, 2002, pg
34.15.]
Polymerizable Surfactant Films
[0099] The lithium salt (sulfanilate) polymerizable surfactant from
Example 1 (1 g) was dissolved in CHCl.sub.3 containing 5%
1-hydroxycyclohexylphenylketone (7 g, w 0.536%) to make up a
casting solution with 12.5 wt % polymerizable surfactant.
[0100] A drop of this electrolyte solution was then pipetted onto a
piece of a microporous non-woven ultra-high molecular weight
polyethylene membrane support. (DSM Solutec--membrane trade name of
"Solupor". The membrane thickness was 20 microns (pore size=0.8
.mu.m, porosity=82%). The solution was absorbed by the membrane and
the solvent was allowed to evaporate. The previously white membrane
was now transparent. The polymerizable surfactants that were filled
inside the support membrane were crosslinked under ultra-violet
light (50 mW/cm.sup.2 320-500 nm for 10 minutes, under a nitrogen
atmosphere) using a commercial spot curing apparatus (Novacure
2100, EXFO). After photopolymerization the membrane was transparent
and still flexible. The membrane was inserted inside a CR2025 coin
cell battery housing (with a wave spring and spacer disk) and
analyzed by potentiostatic EIS. Base on the equivalent circuit
(FIG. 14), R.sub.E=1261.OMEGA., R.sub.T=1.02*10.sup.8.OMEGA.,
C=1.36*10.sup.-10 F. The Nyquist plot from the EIS is shown in FIG.
16. Thus, the lithium ion conductivity is
.sigma.=1.58.times.10.sup.-6 S/cm (at 22.degree. C.). The same coin
cell (with this electrolyte) was analyzed at -35.degree. C., and
the conductivity was measured to be .sigma.=2.7.times.10.sup.-6
S/cm (at -35.degree. C.).
EXAMPLE 5
Sulfanilic Acid Lithium Salt with Diene Polymerizable Groups
Preparation of Pyridinium Chloro Chromate
[0101] Chromium (VI) oxide (48 g, 0.48 mol) was dissolved in 6M HCl
(88 mL, 0.53 mol) at 40.degree. C. to form an orange solution. (See
FIG. 17). The solution was then cooled to 10.degree. C., and
pyridine (38.8 mL, 0.48 mol) was added to the solution. A yellow
orange precipitate was slowly formed. After the solution was heated
to 40.degree. C., the precipitate was dissolved. Aluminum oxide
basic (380 g, 3.73 mol) was added to the solution, and the mixture
was stirred well with a stir rod. The resulting solid was dried
under vacuum and stored under argon atmosphere.
Preparation of 11-Bromo-undecanal
[0102] 11-Bromo-1-undecanol (16.08 g, 0.0640 mol) and
PCC/Al.sub.2O.sub.3 (110.0 g, 0.104 mol) were combined and placed
in a 3-neck round-bottom flask equipped with a mechanical stir bar
under an argon atmosphere. Anhydrous CH.sub.2Cl.sub.2 (200 mL) was
added to the flask, and the reaction mixture was stirred at room
temperature for 16 hours. (See FIG. 17).
[0103] Diethyl ether (60 mL) was then added to dilute the reaction
mixture. Using fritted filter funnel with Florisil (60-100 mesh),
the solid was filtered and washed with diethyl ether (200 mL). The
organic solvents were finally removed under vacuum at about
40.degree. C. to collect an oily liquid product.
Preparation of Matteson's Reagent
[0104] All glassware was heated in an oven at 110.degree. C. for 2
hours, and all anhydrous solvents were further dried with molecular
sieves and purged with argon for 10 min, prior to the
synthesis.
[0105] To a 500 mL 3-neck round bottom flask equipped with a stir
bar and an addition funnel, a solution of
N,N,N',N'-tetramethylethylenediamine (19.6 mL, 0.13 mol) in 80 mL
of anhydrous THF was cooled to -78.degree. C. under argon purge
with an acetone/dry ice bath. (See FIG. 17). Then, 1.3M sec-BuLi
solution (100 mL, 0.13 mol) was added to the solution.
Allyltrimethylsilane (20.7 mL, 0.13 mol) was mixed with 20 mL of
anhydrous THF and added dropwise to the flask from the addition
funnel. The temperature was kept at -78.degree. C. for 30 min.
Then, the temperature was slowly raised to but not higher than
-40.degree. C. in the course of 2 hours by controlling the amount
of dry ice in the acetone bath.
[0106] To another 1000 mL 3-neck round bottom flask equipped with a
mechanical stir bar, a solution of
2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (26.5 mL, 0.13
mol) in 60 mL of anhydrous THF was cooled to -78.degree. C. under
argon purge with an acetone/dry ice bath. The lithiated solution
was then transferred to the 1000 mL flask through a cannula. The
mixture was allowed to warm up to room temperature and stirred for
14 hours.
[0107] The clear product solution was next added to a mixture of
saturated aqueous NH4Cl (150 mL), 1M HCl (150 mL), and
CH.sub.2Cl.sub.2 (300 mL). The mixture was extracted with diethyl
ether (300 mL), and the organic fraction was washed with H.sub.2O
(3.times.150 mL) and brine, NaCl and water (1.times.100 mL). The
organic fraction was dried with MgSO.sub.4, filtered, and the
solvent was evaporated in vacuum at about 40.degree. C. to afford
the crude product. After fractional distillation under reduced
pressure at 75.degree. C. water bath, the pure product was
collected as a clear colorless liquid.
Synthesis of 14-Bromo-tetradeca-1,3-diene
[0108] To a 250 mL round-bottom flask, 11-Bromo-undecanal (4.98 g,
20.0 mmol) was dissolved in 100 mL of diethyl ether. Matteson's
reagent (6.71 g, 28.0 mmol) was then added, and the reaction
mixture was stirred at room temperature for two days. During this
time, the flask was covered with aluminum foil. (See FIG. 17).
[0109] Next, triethanolamine (4.56 g, 30.0 mmol) was added to the
solution, and the mixture was stirred for an additional 2 h, and a
white precipitate formed. After decantation, the organic solution
was washed with saturated NaHCO.sub.3 (2.times.50 mL) and brine,
NaCl and water (2.times.50 mL). The organic fraction was dried with
MgSO4, filtered, and the solvent was evaporated in vacuum at about
40.degree. C. to afford an oily liquid.
[0110] To another 250 mL round-bottom flask, the resulting oily
liquid was mixed with THF (20 mL) and concentrated H.sub.2SO.sub.4
(3 drops). The reaction mixture was stirred at room temperature for
16 h. During this time, the flask was covered with aluminum
foil.
[0111] The reaction mixture was then diluted with hexane (50 mL),
washed with H.sub.2O (1.times.50 mL) and brine, NaCl and water
(1.times.50 mL). The organic fraction was dried with MgSO.sub.4,
filtered, and the solvent was evaporated in vacuum at about
40.degree. C. to afford the crude product. The resulting crude
product was purified by silica gel (230-400 Mesh) column
chromatography (100% hexane) to afford a clear, colorless
liquid.
Preparation of 3,4,5-tris((11,13-tetradecadienyl)oxy)benzoic
acid
[0112] As illustrated in FIG. 18, methyl 3,4,5-trihydroxybenzoate
(2.11 g, 11.4 mmol) and 14-bromo-tetradeca-1,3-diene (10.0 g, 36.6
mmol) were dissolved in methyl ethyl ketone (200 mL) in a
round-bottom flask. Potassium carbonate (17.4 g, 126 mmol) was
added to the flask and the flask was fitted with a reflux
condenser. The mixture was continually stirred at 90.degree. C. for
48 hours. The solution was then allowed to cool to room
temperature, and the insoluble solid was filtered and washed with
ethyl acetate (2.times.200 mL). The supernatant liquor and ethyl
acetate used to wash the insoluble solid were combined and
extracted with H2O (3.times.200 mL). The organic phase was then
separated, dried with MgSO.sub.4, filtered, and the solvent was
evaporated in vacuum at about 40.degree. C. to afford a yellow oily
liquid. The oil was used in the next step without further
purification.
[0113] In the next step as shown in FIG. 18, the yellow oil
prepared above, 3,4,5-tris((11,13-tetradecadienyl)oxy)benzoate, was
dissolved in a solution of ethanol (400 mL), H.sub.2O (80 mL), and
NaOH (3.21 g, 80.2 mmol) in a round-bottom flask equipped with a
reflux condenser and a magnetic stir bar. The mixture was then
stirred and refluxed at 80.degree. C. for 12 hours. After this
period, the solution was cooled to 0.degree. C. using an ice bath
and acidified to pH 5.0 with hydrochloric acid (42 mL, 3M) to
afford a pale brown precipitate. The precipitate was then filtered,
washed with hexane (2.times.100 mL), and dried overnight under
vacuum to collect a white solid.
Preparation of the Tri-diene Acid Chloride
[0114] All glassware was heated in an oven at 110.degree. C. for 2
hours, and all anhydrous solvents were further dried with molecular
sieves and purged with argon for 10 min, prior to the synthesis.
First, 3,4,5-tris((11,13-tetradecadienyl)oxy)benzoic acid (1.09 g,
1.46 mmol) and a trace amount of 2,6-di-tert-butyl-4-methylphenol
stabilizer were dissolved in anhydrous CH.sub.2Cl.sub.2 (25 mL) in
a 50 mL Schlenk flask under an argon atmosphere. Thionyl chloride
(0.64 mL, 8.76 mmol) was then injected by syringe directly into the
solution with constant stirring. The flask was covered with
aluminum foil, and the mixture was continually stirred
overnight.
Preparation of Sulfanilate Lithium Salt Precursor
[0115] The seventh step is equivalent to Example 1, step 2.
Preparation of Lithium Sulfanilate Salt Monomer
[0116] The prepared acid chloride oil (prepared from step 1) was
dissolved in THF (100 mL, regular grade). Potassium carbonate (1.21
g, 8.76 mmol) was then added to the solution to neutralize any
inorganic acidic products from step 1. The mixture was stirred for
10 minutes.
[0117] Next, sulfanilate lithium salt precursor (prepared from step
2) was added, and the mixture was heated to reflux (65.degree. C.)
in air overnight. Lastly, the insoluble solid was filtered and
discarded. The clear pale yellow solution was then dried using
rotary evaporator. The solid product was further dried under
reduced pressure at room temperature for 48 h to afford a pure
lithium sulfanilate diene salt monomer. The lithium salt product
(about 1 g) was then dissolved in
1-hydroxycyclohexylphenylketone/THF solution (7 g, w 0.536%) to
make up solution for casting films of the lithium electrolyte onto
membrane supports.
EXAMPLE 6
Linear Polymerizable Surfactants that Form the Bi-Continuous Cubic
Phase for Nanoporous Polymer Lithium Electrolytes
[0118] There are several relatively simple lipid surfactants which
may form a cubic phase. Of notable interest are sodium
dodecylsulfate (forming a cubic phase at 64% surfactant, 36% polar
solvent, at 45 to 90.degree. C.), potassium dodecanoate (forming a
cubic phase at 66% surfactant, and at 20 C) and potassium
tetradecanoate (forming a cubic phase at 62% surfactant, and at
100.degree. C.). The surfactants may also form the cubic phase with
a variety of other cations such as lithium.
[0119] The surfactants that may be formed from the proposed
polymerizable analogues are shown in FIG. 19. The use of diene
reactive groups may minimize potential reactivity of chemical bonds
in the surfactant with lithium metal (a potential anode material in
lithium rechargeable batteries), however acrylate and methacrylate
versions may also be possible. Additional potential cubic phase
forming polymerizable surfactants are shown in FIG. 20.
EXAMPLE 7
Polymerizable Surfactants with Fluorinated Headgroups for Lithium
Ion Polymer Electrolytes
[0120] Polymerizable surfactants containing fluorinated sulfonic
acid head groups may also be excellent lithium conductors due to
the electron withdrawing nature of the fluorine atoms, which makes
the charge on the base site weaker allowing the lithium greater
dissociation and mobility. The procedure for making the fluorinated
surfactants is based on published work by Marchand-Brynaert herein
incorporated by reference (A Cheguillaume, S Lacroix, and J
Marchand-Brynaert, "A practical synthesis of
2,2-difluoro-3-amino-propanoic acid
(.alpha.,.alpha.-difluoro-.beta.-alanine), Tetrahedron Letters 44
(2003) 2375-2377) and a reaction known as the Reformatsky-type
reaction. This synthetic approach was developed for use in
medicinal chemistry because the fluorinated amino acid has utility
as an 18F-labeled radiopharmaceutical.
[0121] Specifically, the surfactants in FIGS. 20 and 21 have either
an acrylate or diene polymerizable groups and fluorinated acid
headgroups. The three-tailed surfactants may form the inverted
hexagonal phase, while the linear surfactants may form the
bi-continuous cubic phase.
EXAMPLE 8
Cationic Polymerizable Surfactants for Making Polymer
Electrolytes
[0122] Self-assembled polymerizable surfactants may also be used as
proton or hydroxyl conductors for applications such as fuel cell
membranes or in nickel-cadmium batteries. Polymer electrolytes may
be made from cationic surfactants. These cationic surfactants may
comprise cationic head groups such as phosphonium or ammonium. The
cationic surfactant may additionally have a "Gemini" structure with
two linked cationic head groups and two tail groups (See FIG.
22(a)). The cation head groups may be linked by y number of carbons
in the chain and the tail group may comprise x number of carbons in
the chain. In general, x may comprise from 6 to 18 carbons,
alternatively 10 carbons; y may comprise from 1 to 10 carbons,
alternatively 6 carbons. Alternatively, the cationic surfactant may
have a single head group and one or more tails (See FIGS. 22(b)
& (c)). An example of a potential surfactant for forming an
anion conductor may be a phosphonium "Gemini" surfactant with a
halide anion such as Br.sup.- as shown in FIG. 23. These
surfactants may form a bi-continuous cubic phase with a
3-dimensional network of pores which may be capable of conducting
anions.
[0123] Although the present invention and its advantages have been
described in detail, it should be understood that various changes,
substitutions and alterations may be made herein without departing
from the spirit and scope of the invention as defined by the
appended claims.
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