U.S. patent application number 14/581768 was filed with the patent office on 2016-06-23 for functionalized carboranyl magnesium electrolyte for magnesium battery.
The applicant listed for this patent is Toyota Motor Engineering & Manufacturing North America, Inc.. Invention is credited to Rana Mohtadi, Oscar Tutusaus.
Application Number | 20160181662 14/581768 |
Document ID | / |
Family ID | 56130511 |
Filed Date | 2016-06-23 |
United States Patent
Application |
20160181662 |
Kind Code |
A1 |
Tutusaus; Oscar ; et
al. |
June 23, 2016 |
FUNCTIONALIZED CARBORANYL MAGNESIUM ELECTROLYTE FOR MAGNESIUM
BATTERY
Abstract
An electrochemical device is provided having a functionalized
carboranyl magnesium electrolyte. Specifically the disclosure
relates to an electrochemical device having a magnesium anode, a
cathode, a current collector made of non-noble metal, and a
functionalized carboranyl magnesium electrolyte. The functionalized
carboranyl electrolyte includes a carboranyl anion functionalized
with at least one halide, or one alkyl, aryl, alkoxy, aryloxy
groups, or their partially or completely fluorinated analogues. In
contact with the electrolyte, the non-noble metal cathodic current
collector has unusually high oxidative stability >3.0V vs. a
magnesium reference. Processes for making the electrochemical
device are additionally provided.
Inventors: |
Tutusaus; Oscar; (Ann Arbor,
MI) ; Mohtadi; Rana; (Northville, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Toyota Motor Engineering & Manufacturing North America,
Inc. |
Erlanger |
KY |
US |
|
|
Family ID: |
56130511 |
Appl. No.: |
14/581768 |
Filed: |
December 23, 2014 |
Current U.S.
Class: |
429/188 ;
29/623.1 |
Current CPC
Class: |
H01M 4/38 20130101; H01M
2300/0025 20130101; H01M 2004/027 20130101; H01M 10/058 20130101;
H01M 4/466 20130101; H01M 10/0568 20130101; H01M 10/054 20130101;
Y02E 60/10 20130101 |
International
Class: |
H01M 10/0568 20060101
H01M010/0568; H01M 4/137 20060101 H01M004/137; H01M 4/134 20060101
H01M004/134; H01M 10/054 20060101 H01M010/054; H01M 10/058 20060101
H01M010/058 |
Claims
1. An electrochemical device, comprising: an anode comprising
magnesium; a cathode; and an electrolyte in contact with the anode
and the cathode, the electrolyte comprising a functionalized
carboranyl magnesium salt having a formula of:
Mg(CB.sub.iH.sub.[(i+1)-j-k]X.sub.jR.sub.k).sub.2, Formula I:
Mg(C.sub.2B.sub.(i-1)H.sub.(i-j-k)X.sub.jR.sub.k).sub.2, or Formula
II: a combination of at least two of the foregoing, wherein i is an
integer within a range of 5 through 11, inclusive; j is an integer
within a range of 0 through i inclusive; k is an integer between 0
and i inclusive; each X, independently of each other X, is
fluorine, chlorine, bromine, or iodine; and each R, independently
of each other R, is an alkyl, aryl, alkoxy, aryloxy, their
partially or completely fluorinated analogues, or a moiety
combining the aforementioned functionalities.
2. The electrochemical device as recited in claim 1, wherein the
electrolyte comprises a functionalized carboranyl magnesium salt
having a formula according to Formula I.
3. The electrochemical device as recited in claim 1, wherein an
anion of the functionalized carboranyl magnesium salt of any of
formulae I-II is an icosahedral closo-carboranyl anion.
4. The electrochemical device as recited in claim 1, wherein the
functionalized carboranyl magnesium salt is obtained by contacting
functionalized carboranyl silver salt with a magnesium halide.
5. The electrochemical device as recited in claim 1, wherein the
electrolyte is stable at an electrical potential greater than 3.0
V.
6. The electrochemical device as recited in claim 1, wherein the
cathode comprises an organic cathode material.
7. A process for preparing an electrochemical device, comprising:
contacting an anode and a cathode with an electrolyte comprising a
functionalized carboranyl magnesium salt having a formula of:
Mg(CB.sub.iH.sub.[(i+1)-j-k]X.sub.jR.sub.k).sub.2, Formula I:
Mg(C.sub.2B.sub.(i-1)H.sub.(i-j-k)X.sub.jR.sub.k).sub.2, or Formula
II: a combination of at least two of the foregoing, wherein i is an
integer within a range of 5 through 11, inclusive; j is an integer
within a range of 0 through i inclusive; k is an integer between 0
and i inclusive; each X, independently of each other X, is
fluorine, chlorine, bromine, or iodine; and each R, independently
of each other R, is an alkyl, aryl, alkoxy, aryloxy, their
partially or completely fluorinated analogues, or a moiety
combining the aforementioned functionalities.
8. The process as recited in claim 7, wherein the electrolyte
comprises a functionalized carboranyl magnesium salt having a
formula according to Formula I.
9. The process as recited in claim 7, wherein the functionalized
carboranyl magnesium salt comprises an icosahedral closo-carboranyl
anion.
10. The process as recited in claim 7, wherein the functionalized
carboranyl magnesium salt is obtained by contacting functionalized
carboranyl silver salt with a magnesium halide.
11. The process as recited in claim 7, wherein the electrolyte is
stable at an electrical potential greater than 3.0V.
Description
BACKGROUND
[0001] The present disclosure is directed in part to an
electrochemical device having a functionalized carboranyl magnesium
electrolyte. The present disclosure is also directed to a method
for making such an electrolytic cell.
[0002] Magnesium batteries have received significant attention as
potential replacements for lithium batteries due to their high
volumetric capacity, lack of dendrite formation, and the relative
inexpensiveness of magnesium. Discovery and development of suitable
electrolytes for magnesium batteries has proven challenging
however. Conventional inorganic magnesium salts have typically been
found incompatible with reversible magnesium deposition as they
tend to form an ion-blocking layer at the magnesium electrode
during their electrochemical reduction. On the other hand, organic
magnesium salts such as those derived from Grignard reagents have
been found to be highly corrosive, particularly toward non-noble
cathodes, possibly due to the presence of chloride co-anions.
[0003] Previous studies have shown the electrochemical
compatibility and non-corrosiveness of magnesium boron clusters
such as MgB.sub.12H.sub.12 with magnesium electrodes and their use
in magnesium batteries. While having comparable electrochemical
compatibility and non-corrosiveness in a magnesium cell as compared
to the closo-borate containing electrolytes, the carboranyl
electrolytes benefit from the inherently superior solubility of
carboranyl clusters, relative to closo-borate clusters, in ethereal
solvent.
[0004] In order to maximize current density it would be
advantageous to develop electrolyte salts for use in magnesium
batteries having yet higher solubility in suitable solvents.
SUMMARY
[0005] Disclosed, in various non-limiting embodiments, are
electrochemical devices having a carboranyl magnesium electrolyte
and a process of forming these electrochemical devices.
[0006] An electrochemical device is provided having a
magnesium-containing anode, a cathode, and an electrolyte. The
electrolyte includes a functionalized carboranyl magnesium salt
having a formula of:
Mg(CB.sub.iH.sub.[(i+1)-j-k]X.sub.jR.sub.k).sub.2, Formula I:
Mg(C.sub.2B.sub.(i-1)H.sub.(i-j-k)X.sub.jR.sub.k).sub.2, or Formula
II:
a combination of at least two of the foregoing, wherein i is an
integer within a range of 5 through 11, inclusive; j is an integer
within a range of 0 through i inclusive; k is an integer between 0
and i inclusive; each X, independently of each other X, is
fluorine, chlorine, bromine, or iodine; and each R, independently
of each other R, is an alkyl, aryl, alkoxy, aryloxy, their
partially or completely fluorinated analogues, or a moiety
combining the aforementioned functionalities.
[0007] In yet another embodiment, provided herein is a process for
preparing an electrochemical device. The process includes a step of
connecting a magnesium-containing anode and a cathode via an
external electrically conductive structure. The process also
includes a step of contacting the anode and cathode with an
electrolyte. The electrolyte includes a functionalized carboranyl
magnesium salt having a formula of:
Mg(CB.sub.iH.sub.[(i+1)-j-k]X.sub.jR.sub.k).sub.2, Formula I:
Mg(C.sub.2B.sub.(i-1)H.sub.(i-j-k)X.sub.jR.sub.k).sub.2, or Formula
II:
a combination of at least two of the foregoing, wherein i is an
integer within a range of 5 through 11, inclusive; j is an integer
within a range of 0 through i inclusive; k is an integer between 0
and i inclusive; each X, independently of each other X, is
fluorine, chlorine, bromine, or iodine; and each R, independently
of each other R, is an alkyl, aryl, alkoxy, aryloxy, their
partially or completely fluorinated analogues, or a moiety
combining the aforementioned functionalities.
[0008] These and other features of the electrochemical device
having a functionalized carboranyl magnesium electrolyte, and the
process for making the same, will become apparent from the
following detailed description when read in conjunction with the
figures and examples, which are exemplary, not limiting.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] For a better understanding of the processes and devices
having a functionalized carboranyl magnesium electrolyte, with
regard to the particular variations and examples discussed herein,
reference is made to the accompanying figures, in which:
[0010] FIG. 1 is a cyclic voltammogram of a platinum (Pt) working
electrode in contact with 0.2 M
Mg(CB.sub.11H.sub.11(CH.sub.3)).sub.2 in tetraethylene glycol
dimethyl ether (tetraglyme) at a scan rate of 5 mV/s; and
[0011] FIG. 2 is a cyclic voltammogram of a Pt working electrode in
contact with 0.1 M Mg(CB.sub.11H.sub.12).sub.2 in tetraglyme at a
scan rate of 5 mV/s.
DETAILED DESCRIPTION
[0012] The present disclosure provides electrochemical devices
having electrolytes that include functionalized carboranyl
magnesium salts. The results described here indicate that the
present, functionalized carboranyl magnesium salts are capable of
mediating reversible magnesium deposition at a magnesium anode,
while being relatively non-corrosive and oxidatively stable at the
cathodic current collector in a manner previously shown for
non-functionalized carboranyl magnesium containing electrolytes.
The present electrolytes are functionalized on the carboranyl anion
with one or more alkyl or other substantially non-polar moieties in
order to increase the electrolyte solubility in ethereal
solvent.
[0013] The functionalized carboranyl magnesium salts can thus be
particularly beneficial for use as electrolytes in magnesium
batteries having a cathodic current collector made of non-noble
metals such as stainless steel. The presently disclosed
functionalized carboranyl magnesium salts combine the properties of
electrochemical compatibility with reversible and repeated
magnesium deposition at the magnesium anode, lack of corrosiveness
at the cathodic current collector, and high solubility for enhanced
energy density.
[0014] Accordingly, provided herein is an electrochemical device
that includes an anode; a cathode; and an electrolyte in contact
with the anode and the cathode. In general, the electrolyte will
contain a salt having at least one magnesium cation (Mg.sup.2+) and
at least one functionalized carboranyl anion per stoichiometric
unit. In some instances, the electrolyte will comprise a
functionalized carboranyl magnesium salt having a formula of:
Mg(CB.sub.iH.sub.[(i+1)-j-k]X.sub.jR.sub.k).sub.2, Formula I:
Mg(C.sub.2B.sub.(i-1)H.sub.(i-j-k)X.sub.jR.sub.k).sub.2, or Formula
II:
a combination of at least two of the foregoing, wherein i is an
integer within a range of 5 through 11, inclusive; j is an integer
within a range of 0 through i inclusive; k is an integer between 0
and i inclusive; each X, independently of each other X, is
fluorine, chlorine, bromine, or iodine; and each R, independently
of each other R, is an alkyl, aryl, alkoxy, aryloxy, their
partially or completely fluorinated analogues, or a moiety
combining the aforementioned functionalities. In many
implementations, at least one of j and k will be equal to or
greater than 1. In some implementations, k will be equal to or
greater than 1.
[0015] In some implementations, the electrochemical device will
include an electrolyte containing a functionalized carboranyl
magnesium salt according to Formula I, with or without the other
functionalized carboranyl salt according to Formula II.
[0016] As used herein, the term "alkyl" refers to a branched or
straight-chain alkyl group having 1 to 18 carbons (C1-C18) which
can optionally be partially or completely fluorinated. The term
"aryl" as used herein refers to an aromatic hydrocarbon group
having 6 to 14 carbons (C6-14), such as phenyl or naphthyl. An aryl
can also optionally be partially or completely fluorinated. The
term "alkoxy" as used herein refers to group having a formula
--R.sub.alk where R.sub.alk is an alkyl as defined above. An alkoxy
group can optionally be partially or completely fluorinated. The
term "aryloxy" as used herein refers to a group having a formula
--R.sub.aryl, where R.sub.aryl is an aryl group as defined above.
An aryloxy group can optionally be partially or completely
fluorinated.
[0017] Generally, the functionalized carboranyl anion, represented
above as [CB.sub.iH.sub.[(i+1)-j-k]X.sub.jR.sub.k].sup.- or
[C.sub.2B.sub.(i-1)H.sub.(i-j-k)X.sub.jR.sub.k].sup.- will be a
functionalized anion of a closo-carborane. In some instances, it
will be a functionalized anion of an icosahedral-closo-carborane,
wherein the cumulative number of carbon and boron atoms, exclusive
of H, X, and R groups, is 12.
[0018] In some implementations of the disclosed electrochemical
device in which the functionalized carboranyl magnesium salt is a
salt according to Formula I, R can be covalently attached to the
carbon of the carboranyl anion. In some implementations wherein the
functionalized carboranyl magnesium salt is a salt according to
Formula I, R can be alkyl. In some such implementations, R can be
methyl or hexyl.
[0019] The functionalized carboranyl magnesium salts employed in
the electrochemical device described herein are materials that are
either soluble or partially soluble in ethereal solvents under
normal operating conditions for the associated electrochemical
device. Suitable ethereal solvents can include, but are not limited
to, tetrahydrofuran (THF), 1,2-dimethoxyethane (glyme),
bis(2-methoxyethyl) ether (diglyme), triethylene glycol dimethyl
ether (triglyme), tetraethylene glycol dimethyl ether (tetraglyme),
or any other ethereal solvent capable of solubilizing the
functionalized carboranyl magnesium electrolyte employed and
suitable to the configuration and requirements of the
electrochemical device. In certain embodiments, the functionalized
carboranyl magnesium electrolyte will have solubility in any of the
aforementioned solvents of at least 0.01 M at 25.degree. C. and
atmospheric pressure. Typically, a functionalized carboranyl
magnesium salt of the present disclosure will have higher
solubility in a given ethereal solvent than does an analogous
carboranyl magnesium salt lacking any functional groups, X or
R.
[0020] In some implementations, functionalized carboranyl magnesium
salts can be obtained by a salt metathesis reaction between a
functionalized carboranyl silver precursor and a magnesium halide.
For example, a solution of magnesium halide, such as magnesium
bromide can be added to a solution of functionalized carboranyl
silver salt, such as Ag(CB.sub.11H.sub.11(CH.sub.3)).
Functionalized carboranyl silver precursor can be prepared fully
solvent dry according to published methods. Typically both the
magnesium halide and functionalized carboranyl silver reactants
would be present in an ethereal solvent such as THF. The solid
product resulting from reaction of the magnesium halide and the
functionalized carboranyl silver salt, can be separated from the
filtrate by filtration. In some cases, the collected solid is
composed of solely silver halide, and the functionalized carboranyl
magnesium salt can be obtained by removal of the solvent from the
filtrate. In some instances, the collected solid contains the
functionalized carboranyl magnesium salt in addition to the silver
halide; and the functionalized carboranyl magnesium salt can be
purified by extraction with an alkylated glycol, such as
tetraglyme. The salt metathesis reaction generally proceeds
according to Reactions A1 and A2:
MgY.sub.2+2Ag(CB.sub.iH.sub.[(i+1)-j-k]X.sub.jR.sub.k).fwdarw.Mg(CB.sub.-
iH.sub.[(i+1)-j-k]X.sub.jR.sub.k).sub.2+2 AgY, A1,
MgY.sub.2+2Ag(C.sub.2B.sub.(i-1)H.sub.(i-j-k)X.sub.jR.sub.k).fwdarw.Mg(C-
.sub.2B.sub.(i-1)H.sub.(i-j-k)X.sub.jR.sub.k).sub.2+2AgY, A2,
where X, R, i, j, and k are as defined above, and Y is fluorine,
chlorine, bromine, or iodine, independently of X. It is to be
understood that functionalized carboranyl magnesium salts of the
present disclosure can be derived from a wide variety of
functionalized carboranyl metal precursor salts using salt
metathesis reactions of the type shown in Reactions A1 and A2, and
that these reactions are not limited to using silver salts as
precursors. For example, a functionalized carboranyl cesium salt of
the type shown below in Example 1 is a suitable precursor for
production of the corresponding functionalized carboranyl magnesium
salt via salt metathesis.
[0021] The electrolytes comprising functionalized carboranyl
magnesium salts provided herein, when placed under an electric
potential in a disclosed electrochemical device, exhibit high
oxidative stability of well over 3.0 V (vs. Mg reference). In some
instances the oxidative stability of the electrolytes exceeds 3.5 V
vs. Mg.
[0022] In an example, Mg(CB.sub.11H.sub.11(CH.sub.3)).sub.2 in
tetraglyme has oxidative stability to about 3.5 V vs. Mg on a
platinum disk cathode as measured against a magnesium reference
electrode, as shown in FIG. 1. Comparing FIG. 1 to FIG. 2, the
electrolyte containing a functionalized carboranyl magnesium salt
supports a similar current density to that of an electrolyte
containing an analogous non-functionalized carboranyl magnesium
salt, Mg(CB.sub.11H.sub.12).sub.2, in an otherwise similarly
configured cell. Additionally, the electrolyte containing a
functionalized carboranyl magnesium salt has similar oxidative
stability compared to that of the electrolyte containing its
analogous non-functionalized carboranyl magnesium salt. The
functionalized and non-functionalized carboranyl magnesium salts
are each oxidatively stable in this case at an electrical potential
up to about 3.5 V vs. Mg.
[0023] An electrochemical device according to the present
disclosure and having an electrolyte which includes a
functionalized carboranyl magnesium salt will, in many
implementations, be a magnesium battery wherein a
reduction/oxidation reaction according to Reaction B occurs:
Mg.sup.0Mg.sup.2++2e.sup.- B.
[0024] In many implementations, the electrochemical device will be
a secondary battery or a subunit of a secondary battery. In such
implementations, it is to be understood that the term "anode" as
used herein refers to an electrode at which magnesium oxidation
occurs during device discharge and at which magnesium reduction
occurs during device charge. Similarly, it is to be understood that
the term "cathode" refers in such implementations to an electrode
at which a cathode material reduction occurs during device
discharge and at which a cathode material oxidation occurs during
device charge.
[0025] In such implementations, the anode can comprise any material
or combination of materials effective to participate in
electrochemical oxidation of magnesium during a device discharge.
Similarly, the anode can comprise any material or combination of
materials effective to participate in electrochemical reduction of
magnesium cations and to incorporate reduced magnesium during a
device charging event. In some implementations, the anode can
consist essentially of elemental magnesium (i.e. magnesium atoms
having no formal charge) or comprise at least one surface layer of
elemental magnesium. In other implementations, the anode can
comprise a magnesium-containing alloy and/or an insertion-type
magnesium electrode such as a tin electrode, containing magnesium
in complex or alloy with other materials to the extent the cell is
charged.
[0026] The cathode can comprise any material or combination of
materials effective to participate in electrochemical insertion of
a cathode material during a device discharge. Similarly, the
cathode can comprise any material or combination of materials
effective to participate in electrochemical extraction of said
cathode material during a device charging event. In some
variations, the cathode material which is inserted at the cathode
during a device discharge and extracted from the cathode during
device charging event can comprise magnesium. Suitable but
non-exclusive examples of cathode materials can include a Chevrel
phase molybdenum composition such as Mo.sub.6S.sub.8 FeSiO.sub.4
(reversibly MgFeSiO.sub.4), MnO.sub.2, MgFePO.sub.4, sulfur,
organosulfur compounds, an organic cathode material such as
poly(2,2,6,6-tetramethyl-piperidinyl-1-oxy-4-yl methacrylate)
(PTMA), air or any other suitable materials.
[0027] The electrochemical device can additionally include at least
one external conductor, configured to enable electrical
communication between the anode and the cathode. In a simple
implementation, the at least one external conductor can be a single
conductor such as a wire connected at one end to the anode and at
an opposite end to the cathode. In other implementations, the at
least one external conductor can include a plurality of conductors
putting the anode and the cathode in electrical communication with
a power supply device configured to apply an electric potential to
the electrochemical device during a charging event, with other
electrical devices situated to receive power from the
electrochemical device, or both.
[0028] Also provided herein is a process for preparing an
electrochemical device. The process includes a step of contacting
an anode and a cathode with an electrolyte comprising a
functionalized carboranyl magnesium salt. The anode, the cathode,
and the electrolyte are all as described above with respect to the
disclosed electrochemical device. The process can include an
additional step of putting the anode and the cathode into
electrical communication with one another via at least one external
conductor. The at least one external conductor, when present, is
also as described above with reference to the electrochemical
device.
[0029] Various aspects of the present disclosure are further
illustrated with respect to the following Examples. It is to be
understood that these Examples are provided to illustrate specific
embodiments of the present disclosure and should not be construed
as limiting the scope of the present disclosure in or to any
particular aspect.
Example 1
Synthesis of Cesium 1-hexyl-1-carba-closo-dodecaborate,
Cs[1-Hex-CB.sub.11H.sub.11].
[0030] To a solution of Cs(CB.sub.11H.sub.12) (1.38 g, 5 mmol) in
dry THF (40 mL) under argon, n-BuLi solution in hexane (1.6 M, 6.4
mL, 10.24 mmol) was added drop-wise with stirring at -78.degree. C.
The reaction mixture was stirred for 15 min at -78.degree. C., then
warmed to 0.degree. C. and further stirred for 1 h. The resulting
white suspension was added hexyl iodide (1.9 ml, 12.9 mmol) at
0.degree. C., then the mixture was allowed to warm to room
temperature and stirred for 5 h. Water was added slowly and the
solvent was removed under vacuum. The residue was extracted with
Et.sub.2O (3.times.50 mL), and the resulting solution was washed
with a 20% aqueous solution of CsCl (2.times.50 mL). The combined
CsCl wash was extracted with Et.sub.2O (3.times.50 mL). The
combined organic phase was dried over Cs.sub.2CO.sub.3 and
evaporated to dryness. The residue was recrystallized from hot
water, washed with water and pentane, and dried at under vacuum at
120.degree. C. to obtain Cs(1-Hex-CB.sub.11H.sub.11) as a white
solid. It is to be understood that an analogous route can be
employed for the synthesis of Cesium
1-methyl-1-carba-closo-dodecaborate, the precursor to the
functionalized carboranyl magnesium salt employed in the
electrochemical device of FIG. 1. As noted above, the
functionalized carboranyl cesium salt is a suitable precursor for
production of the corresponding functionalized carboranyl magnesium
salt via salt metathesis.
Example 2
Preparation of Electrochemical Devices and Testing Thereof
[0031] Electrochemical testing was conducted in a three-electrode
BASi 4 dram shell vial placed inside an MBraun glove box at
25.degree. C. at less than 0.1 ppm O.sub.2 and H.sub.2O content.
The electrodes used in all experiments were as follows: working
electrode--0.02 cm.sup.2 platinum; counter electrode--magnesium
ribbon (BASi); reference electrode--magnesium wire (BASi). The
working electrode was polished, sonicated, and kept in a dry vacuum
oven prior to each experiment. The surfaces of all magnesium
electrodes were thoroughly rubbed with a glass slide prior to use
to remove any possible oxides.
[0032] Electrochemical testing was conducted using a BioLogic
potentiostat operated at a scan rate of 5 mVs.sup.-1 and data were
acquired and analyzed with EC-lab Software.RTM..
[0033] While particular embodiments have been described,
alternatives, modifications, variations, improvements, and
substantial equivalents that are or may be presently unforeseen may
arise to applicants or others skilled in the art. Accordingly, the
appended claims as filed and as they may be amended, are intended
to embrace all such alternatives, modifications variations,
improvements, and substantial equivalents.
* * * * *