U.S. patent application number 17/702056 was filed with the patent office on 2022-07-07 for method for drying and purifying lithium bis(fluorosulfonyl)imide salt.
This patent application is currently assigned to Arkema France. The applicant listed for this patent is Arkema France. Invention is credited to Gregory SCHMIDT, Remy TEISSIER.
Application Number | 20220216520 17/702056 |
Document ID | / |
Family ID | 1000006215231 |
Filed Date | 2022-07-07 |
United States Patent
Application |
20220216520 |
Kind Code |
A1 |
SCHMIDT; Gregory ; et
al. |
July 7, 2022 |
METHOD FOR DRYING AND PURIFYING LITHIUM BIS(FLUOROSULFONYL)IMIDE
SALT
Abstract
A method for drying and purifying a lithium
bis(fluorosulfonyl)imide salt. Also, a method for producing a
lithium bis(fluorosulfonyl)imide salt which is then dried and
purified by the method. Further, a composition containing lithium
bis(fluorosulfonyl)imide salt having a water content by mass of
between 5 and 45 ppm. And, the use of the composition C in Li-ion
batteries.
Inventors: |
SCHMIDT; Gregory; (Saint
Andeol le Chateau, FR) ; TEISSIER; Remy;
(Francheville, FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Arkema France |
Colombes |
|
FR |
|
|
Assignee: |
Arkema France
Colombes
FR
|
Family ID: |
1000006215231 |
Appl. No.: |
17/702056 |
Filed: |
March 23, 2022 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
16331850 |
Mar 8, 2019 |
11316200 |
|
|
PCT/FR2017/053446 |
Dec 7, 2017 |
|
|
|
17702056 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C01P 2006/40 20130101;
H01M 10/0525 20130101; H01M 10/0568 20130101; H01M 2300/0025
20130101; B01D 9/0009 20130101; C01B 21/086 20130101; B01D 3/36
20130101; B01D 11/0492 20130101 |
International
Class: |
H01M 10/0568 20060101
H01M010/0568; B01D 3/36 20060101 B01D003/36; B01D 9/00 20060101
B01D009/00; B01D 11/04 20060101 B01D011/04; C01B 21/086 20060101
C01B021/086; H01M 10/0525 20060101 H01M010/0525 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 8, 2016 |
FR |
1662129 |
Claims
1. A process for drying and purifying a lithium
bis(fluorosulfonyl)imide salt in solution in an organic solvent S1,
said process comprising the following steps: a) addition of
deionized water to dissolve and extract the lithium
bis(fluorosulfonyl)imide salt, forming an aqueous solution of said
salt; a') optional concentration of said aqueous solution; b)
extraction of the lithium bis(fluorosulfonyl)imide salt from said
aqueous solution, with an organic solvent S2 forming an azeotropic
mixture with water, this step being repeated at least once; c)
concentration of said lithium bis(fluorosulfonyl)imide salt by
evaporation of said organic solvent S2 and of the water, and d)
optionally, crystallization of the lithium bis(fluorosulfonyl)imide
salt.
2. The process as claimed in claim 1, comprising step a') of
concentration of said aqueous solution.
3. The process as claimed in claim 1, in which step a) is such that
the mass of deionized water is greater than or equal to a third of
the mass of the initial solution of the lithium
bis(fluorosulfonyl)imide salt in the organic solvent S1.
4. The process as claimed in claim 1, in which the organic solvent
S2 is chosen from the group constituted of esters, nitriles,
ethers, chlorinated solvents, aromatic solvents, and mixtures
thereof.
5. The process as claimed in claim 1, in which the organic solvent
S1 is chosen from the group constituted of esters, nitriles,
ethers, chlorinated solvents and aromatic solvents, and mixtures
thereof.
6. The process as claimed in claim 1, in which the organic solvent
S2/water mass ratio, during an extraction, ranges from 1/6 to
1/1.
7. The process as claimed in claim 1, also comprising, between step
b) and step c), a step c') of concentration of the organic solution
obtained on conclusion of step b), to obtain an organic solution
with a mass content of LiFSI of between 20% and 60%.
8. The process as claimed in claim 1, in which, during step c), the
organic phases formed during step b) are pooled and concentrated by
evaporation at a temperature of between 30.degree. C. and
100.degree. C., and at a pressure of between 200 mbar abs and 0.5
mbar abs.
9. The process as claimed in claim 1, in which the organic phase
separated from the aqueous solution extracted in step a) is not
reintroduced into the subsequent steps b) to d) of the process.
10. The process as claimed in claim 1, in which the lithium
bis(fluorosulfonyl)imide salt obtained on conclusion of step c)
comprises less than 10% by weight of residual solvent.
11. The process as claimed in claim 1, in which, during step d),
the lithium bis(fluorosulfonyl)imide salt is crystallized under
cold conditions at a temperature of less than or equal to
25.degree. C., optionally in an organic solvent S3 chosen from
chlorinated solvents, and aromatic solvents, said salt optionally
being recovered by filtration.
12. The process as claimed in claim 1, wherein it leads to a
lithium bis(fluorosulfonyl)imide salt having a mass content of
water of less than or equal to 45 ppm by mass relative to the total
mass of said salt.
13. A process for manufacturing a lithium bis(fluorosulfonyl)imide
salt, comprising the following steps: i. synthesis of
bis(chlorosulfonyl)imide from sulfamic acid; ii. fluorination of
bis(chlorosulfonyl)imide to bis(fluorosulfonyl)imide; and iii.
preparation of the alkali metal or alkaline-earth metal salt of
bis(fluorosulfonyl)imide by neutralization of the
bis(fluorosulfonyl)imide; iv. cation exchange to obtain a lithium
bis(fluorosulfonyl)imide salt; and v. drying and purification
process as claimed in claim 1.
14. The process as claimed in claim 13, leading to the formation of
a lithium bis(fluorosulfonyl)imide salt having a mass content of
water of less than or equal to 45 ppm by mass relative to the total
mass of said salt.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a divisional of U.S. application
Ser. No. 16/331,850, filed on Mar. 8, 2019, which is a U.S.
national stage of International Application No. PCT/FR2017/053446,
filed on Dec. 7, 2017, which claims the benefit of French
Application No. 1662129, filed on Dec. 8, 2016. The entire contents
of each of U.S. application Ser. No. 16/331,850, International
Application No. PCT/FR2017/053446, and French Application No.
1662129 are hereby incorporated herein by reference in their
entirety.
TECHNICAL FIELD
[0002] The present invention relates to the field of Li-ion
batteries. More particularly, the invention relates to a process
for drying and purifying a lithium bis(fluorosulfonyl)imide
salt.
[0003] The invention also relates to a process for manufacturing a
lithium bis(fluorosulfonyl)imide salt, which has been dried and
purified by means of the drying and purification process according
to the invention.
[0004] The present invention also relates to a lithium
bis(fluorosulfonyl)imide salt comprising a reduced content of
water, and various uses thereof.
[0005] The development of higher-power batteries is required for
the Li-ion battery market. This is done by increasing the nominal
voltage of Li-ion batteries. To achieve the targeted voltages,
high-purity electrolytes are required. By virtue of their very low
basicity, anions of sulfonylimide type are increasingly used in the
field of energy storage in the form of inorganic salts in
batteries, or of organic salts in supercapacitors or in the field
of ionic liquids.
[0006] In the specific field of Li-ion batteries, the salt that is
currently the most widely used is LiPF.sub.6. This salt has many
drawbacks, such as limited thermal stability, sensitivity to
hydrolysis and thus poorer safety of the battery. Recently, novel
salts bearing the fluorosulfonyl group FSO.sub.2.sup.- have been
studied and have demonstrated many advantages such as better ion
conductivity and resistance to hydrolysis. One of these salts,
LiFSI has shown highly advantageous properties which make it a good
candidate for replacing LiPF.sub.6.
[0007] The identification and quantification of impurities in salts
and/or electrolytes and the understanding of their impacts on
battery performance have become paramount. For example, on account
of their interference with electrochemical reactions, impurities
bearing a labile proton lead to overall reduced performance
qualities and stability for Li-ion batteries. The application of
Li-ion batteries makes it necessary to have high-purity products
(minimum amount of impurities and in particular with a very low
residual moisture content).
[0008] U.S. Pat. No. 9,079,780 describes various methods for
concentrating LiFSI, to overcome the formation of byproducts:
[0009] drying under a stream of dry inert gas; and/or [0010]
concentration of an LiFSI solution via a thin-film evaporator.
[0011] The examples of said document describe the production of
LiFSI with high contents of water, for example between 58 and 323
ppm, and varied contents of other impurities. Such salts in
particular have drawbacks such as problems of corrosion, safety,
etc.
[0012] There is a need for a novel process for drying a lithium
bis(fluorosulfonyl)imide salt which makes it possible especially to
obtain said salt with a reduced content of residual water.
[0013] There is also a need to provide novel LiFSI compositions
which do not have at least one of the drawbacks of the known LiFSI
salts, and which are especially compatible with applications in
electronics, such as Li-ion batteries.
DETAILED DESCRIPTION
[0014] The present invention relates to a process for drying and
purifying a lithium bis(fluorosulfonyl)imide salt in solution in an
organic solvent S1, said process comprising the following steps:
[0015] a) addition of deionized water to dissolve and extract the
lithium bis(fluorosulfonyl)imide salt, forming an aqueous solution
of said salt; [0016] a') optional concentration of said aqueous
solution; [0017] b) extraction of the lithium
bis(fluorosulfonyl)imide salt from said aqueous solution, with an
organic solvent S2 forming an azeotropic mixture with water, this
step being repeated at least once; [0018] c) concentration of said
lithium bis(fluorosulfonyl)imide salt by evaporation of said
organic solvent S2 and of the water, and [0019] d) optional
crystallization of the lithium bis(fluorosulfonyl)imide salt.
[0020] In the context of the invention, the terms "lithium salt of
bis(fluorosulfonyl)imide", "lithium bis(sulfonyl)imide", "LiFSI",
"LiN(FSO.sub.2).sub.2", "lithium bis(sulfonyl)imide" and "lithium
bis(fluorosulfonyl)imide" are used equivalently.
[0021] In the context of the invention, the term "ppm" is
understood as ppm on a weight basis.
[0022] In the context of the invention, the term "salt with a water
content of less than or equal to 40 ppm by weight" means, for
example, a salt with a water content of less than or equal to 40
ppm by weight relative to the total weight of said salt.
[0023] The initial solution of lithium bis(fluorosulfonyl)imide
salt may come from any synthesis of the lithium
bis(fluorosulfonyl)imide salt, in particular comprising the
following steps: [0024] i) synthesis of bis(chlorosulfonyl)imide;
[0025] ii) fluorination of bis(chlorosulfonyl)imide to
bis(fluorosulfonyl)imide; [0026] iii) preparation of an alkali
metal or alkaline-earth metal salt of bis(fluorosulfonyl)imide by
neutralization of the bis(fluorosulfonyl)imide; [0027] iv) cation
exchange to obtain the lithium bis(fluorosulfonyl)imide salt.
[0028] On conclusion of these steps, the lithium
bis(fluorosulfonyl)imide salt is preferably obtained in solution in
an organic solvent (corresponding in particular to the solvent S1),
at a mass concentration of between 5% and 50% by mass relative to
the total mass of the solution.
[0029] Such a process is described, for example, in WO
2015/158979.
[0030] According to one embodiment, the abovementioned organic
solvent S1 is chosen from the group constituted of esters,
nitriles, ethers, chlorinated solvents and aromatic solvents, and
mixtures thereof. Preferably, the solvent S1 is chosen from
dichloromethane, ethyl acetate, butyl acetate, tetrahydrofuran,
acetonitrile and diethyl ether, and mixtures thereof. Preferably,
the organic solvent S1 is butyl acetate.
[0031] According to the invention, the organic solvent S1 and the
organic solvent S2 may be identical or different.
[0032] Preferably, the organic solvent S1 and the organic solvent
S2 are identical.
[0033] According to one embodiment, the mass content of LiFSI in
the organic solvent S1 is between 5% and 55%, preferably between 5%
and 50%, preferentially between 10% and 55%, advantageously between
10% and 50%, for example between 10% and 40%, in particular between
15% and 40% and preferentially between 25% and 35% by mass,
relative to the total mass of the solution.
[0034] According to one embodiment, step a) of the purification and
drying process according to the invention comprises the addition of
deionized water to the solution of LiFSI in the abovementioned
organic solvent S1, for example obtained during previous synthetic
steps, to allow the dissolution of said salt and the extraction of
said salt into water (aqueous phase).
[0035] The extraction may be performed via any known extraction
means. The extraction may typically be the separation of an aqueous
phase (aqueous solution of said salt in the present case) and of an
organic phase.
[0036] According to the invention, step a) of the process may be
repeated at least once.
[0037] The drying and purification step of the invention may
comprise one or more extractions with deionized water, for example
three extractions. In a first extraction, an amount of deionized
water corresponding to half of the mass of the initial solution may
be added, followed by an amount equal to about a third of the mass
of the initial solution during the second extraction, and then an
amount equal to about a quarter of the mass of the initial solution
during the third extraction.
[0038] According to a preferred embodiment, step a) is such that
the mass of deionized water is greater than or equal to a third,
preferably greater than or equal to half, of the mass of the
initial solution of LiFSI in the organic solvent S1 (in the case of
a single extraction, or for the first extraction only if step a) is
repeated at least once).
[0039] The process according to the invention may comprise the
addition of a volume of deionized water in step a) of greater than
or equal to a third, preferably greater than or equal to half of
the volume of solvent S1 of the initial solution.
[0040] In the case of multiple extractions (repetition of step a)),
the extracted aqueous phases are pooled together to form a single
aqueous phase.
[0041] Step a) advantageously allows the production of an aqueous
phase and an organic phase, which are separate. Step b) is thus
advantageously performed on the aqueous solution extracted in step
a) (single aqueous phase or pooled aqueous phases in the case of
repetition of step a)).
[0042] Preferably, in the process according to the invention, the
organic phase(s) separated from the aqueous solution extracted in
step a) (comprising the organic solvent S1 and LiFSI) are not
reintroduced into the subsequent steps b) to d) of the process; in
particular, they are not subsequently pooled with the organic
phases extracted during step b) (comprising the organic solvent
S2).
[0043] On conclusion of step a), an aqueous solution of LiFSI is
obtained in particular.
[0044] According to one embodiment, the mass content of LiFSI in
the aqueous solution is between 5% and 35%, preferably between 10%
and 25%, relative to the total mass of the solution.
[0045] The drying and purification process according to the
invention may comprise a concentration step a') between step a) and
step b), preferably to obtain an aqueous solution of LiFSI
comprising a mass content of LiFSI of between 20% and 80%, in
particular between 25% and 75%, preferably between 25% and 70%,
advantageously between 30% and 65% relative to the total mass of
the solution. The concentration step may be performed with a rotary
evaporator under reduced pressure, at a pressure below 50 mbar abs
(preferably below 30 mbar abs), and in particular at a temperature
of between 25.degree. C. and 60.degree. C., for example at
40.degree. C.
[0046] Preferably, the drying and purification process according to
the invention comprises step a'). After concentration a') of the
aqueous solution obtained on conclusion of step a), a concentrated
aqueous solution of LiFSI is obtained.
[0047] The LiFSI, contained in the aqueous solution obtained on
conclusion of step a) or of an optional concentration step a') or
of another optional intermediate step, may then be recovered by
extraction with an organic solvent S2, said solvent S2 forming an
azeotrope with water (step b)). Step b) of the process according to
the invention leads in particular, after extraction, to an organic
phase, saturated with water, containing the LiFSI (it is a solution
of LiFSI in the organic solvent S2, said solution being saturated
with water).
[0048] The extraction typically allows the separation of an aqueous
phase and of an organic phase (solution of LiFSI in the solvent S2
in the present case).
[0049] Step b) advantageously allows the production of an aqueous
phase and an organic phase, which are separate.
[0050] The solvent S2 for extraction of the LiFSI salt dissolved in
deionized water is advantageously: [0051] a good solvent for the
LiFSI salt, i.e. the LiFSI may have a solubility of greater than or
equal to 10% by weight relative to the total weight of the sum
LiFSI plus solvent; and/or [0052] sparingly soluble in water, i.e.
it has a solubility of less than or equal to 1% by weight relative
to the total weight of the sum solvent plus water.
[0053] According to one embodiment, the organic solvent S2 is
chosen from the group constituted of esters, nitriles, ethers,
chlorinated solvents and aromatic solvents, and mixtures thereof.
Preferably, the solvent S2 is chosen from ethers and esters, and
mixtures thereof. For example, mention may be made of methyl
t-butyl ether, cyclopentyl methyl ether, ethyl acetate, propyl
acetate, butyl acetate, dichloromethane, tetrahydrofuran,
acetonitrile and diethyl ether, and mixtures thereof. Preferably,
the solvent S2 is chosen from methyl t-butyl ether, cyclopentyl
methyl ether, ethyl acetate, propyl acetate and butyl acetate, and
mixtures thereof.
[0054] Preferably, the organic solvent S2 is butyl acetate.
[0055] The extraction step b) is repeated at least once, preferably
from one to ten times and in particular four times. The organic
phases may then be pooled into a single phase before step c).
[0056] Preferably, in the process according to the invention, the
organic phases extracted during step b) are not pooled with the
organic phase(s) obtained during step a).
[0057] For each extraction, the mass amount of organic solvent S2
used may range between 1/6 and 1 times the mass of the aqueous
phase. Preferably, the organic solvent S2/water mass ratio, during
an extraction of step b), ranges from 1/6 to 1/1, the number of
extractions ranging in particular from 2 to 10.
[0058] Preferably, during the extraction step b), the organic
solvent S2 is added to the aqueous solution obtained on conclusion
of step a) (or of the optional step a')).
[0059] According to one embodiment, the mass content of LiFSI in
solution in the organic phase is between 5% and 35%, preferably
between 10% and 25% by mass, relative to the total mass of the
solution.
[0060] The drying and purification process according to the
invention may comprise a concentration step c') (preconcentration)
between step b) and step c), preferably to obtain a solution of
LiFSI in the organic solvent S2 comprising a mass content of LiFSI
of between 20% and 60% and preferably between 30% and 50% by mass
relative to the total mass of the solution.
[0061] The preconcentration step c') may be performed at a
temperature ranging from 25.degree. C. to 60.degree. C., preferably
from 25.degree. C. to 45.degree. C., optionally under reduced
pressure, for example at a pressure below 50 mbar abs, in
particular at a pressure below 30 mbar abs.
[0062] The preconcentration step c') may be performed with a rotary
evaporator under reduced pressure, especially at 40.degree. C. and
at a pressure below 30 mbar abs.
[0063] According to one embodiment, step c) of the process
according to the invention consists in concentrating the solution
of LiFSI in the organic solvent S2 (obtained especially on
conclusion of step b) or of the optional step c')).
[0064] According to one embodiment, the concentration step c) is
performed under reduced pressure, preferably at a pressure of
between 200 mbar abs and 0.5 mbar abs, so as advantageously to
avoid high temperatures which promote the decomposition of the
LiFSI, for example for a time of between 2 minutes and 48 hours,
and preferably between 5 minutes and 24 hours, in particular
between 10 minutes and 2 hours. The duration of step c) is
especially between 45 minutes and 1 hour 15 minutes in order, for
example, to concentrate 1000 g of LiFSI solution in the solvent S2.
The temperature range of the concentration step may be between
30.degree. C. and 100.degree. C. and preferably between 40.degree.
C. and 90.degree. C.
[0065] In particular, the drying and purification process according
to the invention is such that, during step c), the organic phases
formed on conclusion of step b) are pooled and concentrated by
evaporation at a temperature of between 30.degree. C. and
100.degree. C., preferably between 40.degree. C. and 90.degree. C.,
and at a pressure of between 200 mbar abs and 0.5 mbar abs.
[0066] Any apparatus for concentrating by evaporation of the
solvent may be used, in particular any apparatus making it possible
to reduce the duration of the concentration step in order
advantageously to reduce the risk of decomposition of the LiFSI
salt. Mention may be made, for example, of a rotary evaporator, a
thin-film (also known as a "scraped-film") evaporator or any other
apparatus enabling concentration.
[0067] Among the thin-layer evaporators, mention may be made
especially of the thin-layer evaporators sold by the companies Buss
SMS Ganzler ex Luwa AG, UIC GmbH or VTA Process.
[0068] According to a preferred embodiment, the concentration step
c) is performed under reduced pressure, especially at a pressure of
less than 30 mbar abs, in a thin-film evaporator, at a particular
temperature of 90.degree. C., for a time of 1 hour, especially to
concentrate 150 g of solution.
[0069] The drying and purification process according to the
invention advantageously makes it possible to obtain an LiFSI salt
in particular having a water content of less than or equal to 45
ppm by weight, preferably less than or equal to 40 ppm by weight.
The process according to the invention advantageously allows the
production of an LiFSI salt that is compatible with applications in
electrolytes for Li-ion batteries.
[0070] According to one embodiment, the water/solvent azeotrope
generally has a lower boiling point than that of the solvent S2
alone, which advantageously makes it possible to avoid or reduce
the possible decomposition of the LiFSI salt. The water/solvent
azeotrope formed in the process according to the invention
advantageously makes it possible to remove the water.
[0071] According to the invention, on conclusion of the
abovementioned step c), the LiFSI may be obtained in solid form,
and in particular in crystalline form, or in the form of a
concentrated solution, the concentrated solution comprising less
than 10% by weight of residual solvent, preferably less than 5% by
weight.
[0072] According to one embodiment, the process according to the
invention also comprises a step d) of crystallization of the
lithium bis(fluorosulfonyl)imide salt obtained on conclusion of the
abovementioned step c).
[0073] Preferably, during step d), the LiFSI is crystallized under
cold conditions, especially at a temperature of less than or equal
to 25.degree. C.
[0074] Preferably, step d) of crystallization of the LiFSI is
performed in an organic solvent S3 (crystallization solvent) chosen
from chlorinated solvents, for instance dichloromethane, and
aromatic solvents, for instance toluene, in particular at a
temperature of less than or equal to 25.degree. C. Preferably, the
LiFSI crystallized on conclusion of step d) is recovered by
filtration.
[0075] According to a preferred embodiment, the process according
to the invention does not comprise a filtration step, in particular
with a step of filtering molecules having a size of between 0.1 and
10 .mu.m, between step a) and the abovementioned step c).
[0076] The process according to the invention may comprise
intermediate steps between the abovementioned steps of the process.
Preferably, the process does not comprise intermediate steps
between the abovementioned steps.
[0077] According to one embodiment, the process for drying and
purifying a lithium bis(fluorosulfonyl)imide salt in solution in an
organic solvent S1, according to the invention, comprises the
following four steps: [0078] a) addition of deionized water to the
solution of LiFSI in an organic solvent S1, allowing extraction of
the LiFSI salt into water, this step preferably being repeated at
least once; [0079] a') optional concentration of said aqueous
solution; [0080] b) extraction of said LiFSI salt using an organic
solvent S2 which forms an azeotropic mixture with water; [0081] c)
concentration of the LiFSI by evaporation of said organic solvent
S2 in particular entraining the water with the solvent due to the
existence of the azeotrope solvent S2/water; and [0082] d)
crystallization of the bis(fluorosulfonyl)imide salt.
[0083] According to one embodiment, the drying and purification
process according to the invention comprises the following steps:
[0084] a) addition of deionized water to the solution of LiFSI in
the organic solvent S1, especially in butyl acetate, to dissolve
and extract the lithium bis(fluorosulfonyl)imide salt, forming an
aqueous solution of said salt, this step being repeated preferably
at least once; [0085] the mass content of LiFSI in the organic
solvent S1 in particular being between 5% and 55%; [0086] a')
optional concentration of the solution obtained on conclusion of
step a), to obtain an aqueous solution of LiFSI with an LiFSI
content of between 20% and 80%, preferably between 30% and 65%;
[0087] b) extraction of the lithium bis(fluorosulfonyl)imide salt
from said aqueous solution, with an organic solvent S2 which forms
an azeotropic mixture with water, this step being repeated at least
once; [0088] c') optional step of concentration of the organic
solution obtained on conclusion of step b), to obtain an organic
solution with a mass content of LiFSI of between 20% and 60%;
[0089] c) concentration of the lithium bis(fluorosulfonyl)imide
salt by evaporation of said organic solvent S2 and of the water, at
a temperature between 30.degree. C. and 100.degree. C., preferably
between 40.degree. C. and 90.degree. C., and at a pressure between
200 mbar abs and 0.5 mbar abs; [0090] d) optional crystallization
of the lithium bis(fluorosulfonyl)imide salt in an organic solvent
S3 chosen from chlorinated solvents, for instance dichloromethane,
and aromatic solvents, for instance toluene, at a temperature of
less than or equal to 25.degree. C.; [0091] d') optional filtration
to recover the LiFSI.
[0092] According to one embodiment, the drying and purification
process according to the invention comprises the following steps:
[0093] a) addition of deionized water to the solution of LiFSI in
the organic solvent S1, especially in butyl acetate, to dissolve
and extract the lithium bis(fluorosulfonyl)imide salt, forming an
aqueous solution of said salt, this step preferably being repeated
at least once; [0094] the mass content of LiFSI in the organic
solvent S1 in particular being between 5% and 55%; [0095] a')
concentration of the solution obtained on conclusion of step a), to
obtain an aqueous solution of LiFSI with an LiFSI content of
between 20% and 80%, preferably between 30% and 65%, especially at
40.degree. C. and at a pressure of less than 30 mbar abs; [0096] b)
extraction of the lithium bis(fluorosulfonyl)imide salt from said
aqueous solution, with an organic solvent S2 which forms an
azeotropic mixture with water, this step being repeated at least
once; [0097] c) concentration of the lithium
bis(fluorosulfonyl)imide salt by evaporation of said organic
solvent S2 and of the water, at a temperature between 30.degree. C.
and 100.degree. C., preferably between 40.degree. C. and 90.degree.
C., and at a pressure between 200 mbar abs and 0.5 mbar abs; [0098]
d) crystallization of the lithium bis(fluorosulfonyl)imide salt in
an organic solvent S3 chosen from chlorinated solvents, for
instance dichloromethane, and aromatic solvents, for instance
toluene, at a temperature of less than or equal to 25.degree. C.;
[0099] d') filtration to recover the LiFSI.
[0100] The process according to the invention makes it possible to
obtain LiFSI advantageously having a water content of less than or
equal to 45 ppm, in particular less than or equal to 40 ppm by mass
relative to the total mass of said LiFSI.
[0101] Preferably, the process according to the invention leads to
an LiFSI having a mass proportion of water of, for example, between
5 and 45 ppm, between 8 and 45 ppm, between 9 and 45 ppm, between
10 and 45 ppm, between 12 and 45 ppm, between 15 and 45 ppm,
between 20 and 45 ppm, between 25 and 45 ppm, between 30 and 45
ppm, between 5 and 40, between 8 and 40 ppm, between 9 and 40,
between 10 and 40 ppm, between 12 and 40 ppm, between 15 and 40
ppm, between 20 and 40 ppm, between 25 and 40 ppm, or between 30
and 40 ppm by mass relative to the total mass of said salt.
[0102] Preferably, the process according to the invention leads to
an LiFSI salt in which the mass proportion of sulfate ions is, for
example, less than or equal to 200 ppm, less than or equal to 160
ppm, less than or equal to 150 ppm, less than or equal to 130 ppm,
less than or equal to 120 ppm, less than or equal to 110 ppm, less
than or equal to 100 ppm, or less than or equal to 90 ppm by mass
relative to the total mass of said salt.
[0103] Preferably, the process according to the invention leads to
an LiFSI salt in which the mass proportion of sulfate ions is, for
example, between 5 and 200 ppm, between 5 and 160 ppm, between 5
and 150 ppm, between 5 and 140 ppm, between 5 and 130 ppm, between
5 and 120 ppm, between 5 and 110 ppm, between 5 and 100 ppm,
between 5 and 80 ppm, between 8 and 200 ppm, between 8 and 160 ppm,
between 8 and 150 ppm, between 8 and 140 ppm, between 8 and 130
ppm, between 8 and 120 ppm, between 8 and 110 ppm, between 8 and
100 ppm, between 8 and 80 ppm, between 10 and 160 ppm, between 10
and 150 ppm, between 10 and 140 ppm, between 10 and 130 ppm,
between 10 and 120 ppm, between 10 and 110 ppm, between 10 and 100
ppm, between 10 and 80 ppm, between 15 and 160 ppm, between 15 and
150 ppm, between 15 and 140 ppm, between 15 and 130 ppm, between 15
and 120 ppm, between 15 and 110 ppm, between 15 and 100 ppm,
between 15 and 80 ppm, between 20 and 200 ppm, between 20 and 160
ppm, between 20 and 150 ppm, between 20 and 140 ppm, between 20 and
130 ppm, between 20 and 120 ppm, between 20 and 110 ppm, between 20
and 100 ppm, between 20 and 80 ppm, between 25 and 160 ppm, between
25 and 150 ppm, between 25 and 140 ppm, between 25 and 130 ppm,
between 25 and 120 ppm, between 25 and 110 ppm, between 25 and 100
ppm, or between 25 and 80 ppm by mass relative to the total mass of
said salt.
[0104] Advantageously, the process according to the invention leads
to an LiFSI salt in which the mass content of Cl.sup.- is less than
or equal to 50 ppm, preferentially less than or equal to 40 ppm by
mass relative to the total mass of said salt.
[0105] The process according to the invention advantageously makes
it possible to obtain an LiFSI in which the mass contents of other
impurities are as follows: F.sup.-.ltoreq.200 ppm (preferably
.ltoreq.50 ppm), FSO.sub.3Li.sup.-.ltoreq.200 ppm,
FSO.sub.2NH.sub.2.ltoreq.200 ppm, CO.sub.3.sup.2-.ltoreq.50 ppm,
ClO.sub.3.sup.-.ltoreq.50 ppm, ClO.sub.4.sup.-.ltoreq.50 ppm,
NO.sub.2.sup.-.ltoreq.50 ppm, NO.sub.3.sup.-.ltoreq.50 ppm,
Si.ltoreq.40 ppm, Mg.ltoreq.10 ppm, Fe.ltoreq.10 ppm, Ca.ltoreq.10
ppm, Pb.ltoreq.10 ppm, Cu.ltoreq.10 ppm, Cr.ltoreq.10 ppm,
Ni.ltoreq.10 ppm, Al.ltoreq.10 ppm, Zn.ltoreq.10 ppm, and
Na.ltoreq.10 ppm.
[0106] According to one embodiment, the process according to the
invention advantageously leads to an LiFSI salt comprising: [0107]
a mass content of water of less than or equal to 45 ppm, preferably
less than or equal to 40 ppm, preferably between 5 and 40 ppm,
preferably between 8 and 40 ppm, in particular between 10 and 40
ppm, preferentially between 12 and 40 ppm, for example between 15
and 40 ppm, especially between 20 and 40 ppm, advantageously
between 25 and 40 ppm and even more advantageously between 30 and
40 ppm; [0108] a mass content of sulfate ions of less than or equal
to 200 ppm, in particular less than or equal to 160 ppm, for
example less than or equal to 150 ppm, in particular less than or
equal to 130 ppm, preferentially less than or equal to 120 ppm,
more preferentially still less than or equal to 100 ppm; [0109] a
mass content of Cl.sup.- of less than or equal to 50 ppm; [0110] a
mass content of F.sup.- of less than or equal to 200 ppm,
preferably less than or equal to 50 ppm; [0111] a mass content of
LiFSO.sub.3 of less than or equal to 200 ppm; [0112] a mass content
of FSO.sub.2NH.sub.2 of less than or equal to 200 ppm; [0113] a
mass content of CO.sub.3.sup.2- of less than or equal to 50 ppm;
[0114] a mass content of ClO.sub.3.sup.- of less than or equal to
50 ppm; [0115] a mass content of ClO.sub.4.sup.- of less than or
equal to 50 ppm; [0116] a mass content of NO.sub.2.sup.- of less
than or equal to 50 ppm; [0117] a mass content of NO.sub.3.sup.- of
less than or equal to 50 ppm; [0118] a mass content of Si of less
than or equal to 40 ppm; [0119] a mass content of Mg of less than
or equal to 10 ppm; [0120] a mass content of Fe of less than or
equal to 10 ppm; [0121] a mass content of Ca of less than or equal
to 10 ppm; [0122] a mass content of Pb of less than or equal to 10
ppm; [0123] a mass content of Cu of less than or equal to 10 ppm;
[0124] a mass content of Cr of less than or equal to 10 ppm; [0125]
a mass content of Ni of less than or equal to 10 ppm; [0126] a mass
content of Al of less than or equal to 10 ppm; [0127] a mass
content of Zn of less than or equal to 10 ppm; and [0128] a mass
content of Na of less than or equal to 10 ppm.
[0129] The LiFSI salt obtained according to the process of the
invention is advantageously suitable for use in Li-ion battery
electrolytes.
[0130] The present invention also relates to an LiFSI salt which
may be obtained according to the purification and drying process as
described previously, and their use in Li-ion battery
electrolytes.
[0131] The invention also relates to a process for manufacturing a
lithium bis(fluorosulfonyl)imide salt, which comprises, in addition
to steps i) to iv) mentioned above, steps a) to d) of the drying
and purification process according to the invention.
[0132] According to a second aspect, the invention relates to a
process for preparing a lithium bis(fluorosulfonyl)imide salt,
which comprises, upstream of steps a) to d) of the abovementioned
drying and purification process, the following steps i) to iv):
[0133] i) synthesis of bis(chlorosulfonyl)imide; [0134] ii)
fluorination of bis(chlorosulfonyl)imide to
bis(fluorosulfonyl)imide; [0135] iii) preparation of the alkali
metal or alkaline-earth metal salt of bis(fluorosulfonyl)imide by
neutralization of the bis(fluorosulfonyl)imide; [0136] iv) cation
exchange to obtain a lithium bis(fluorosulfonyl)imide salt.
[0137] According to one embodiment, the lithium
bis(fluorosulfonyl)imide salt is prepared as described below.
[0138] According to one embodiment, the present invention relates
to a process for preparing a lithium bis(fluorosulfonyl)imide salt,
comprising the following steps: [0139] i) synthesis of
bis(chlorosulfonyl)imide from sulfamic acid; [0140] ii)
fluorination of bis(chlorosulfonyl)imide to
bis(fluorosulfonyl)imide; [0141] iii) preparation of the alkali
metal or alkaline-earth metal salt of bis(fluorosulfonyl)imide by
neutralization of the bis(fluorosulfonyl)imide, in particular using
an aqueous solution of a base chosen from alkali metal or
alkaline-earth metal carbonates, and alkali metal or alkaline-earth
metal hydroxides; [0142] iv) cation exchange to obtain a lithium
bis(fluorosulfonyl)imide salt; [0143] v) abovementioned drying and
purification process according to the invention, comprising steps
a) to d) as described above.
[0144] The process for preparing the lithium
bis(fluorosulfonyl)imide salt according to the invention
advantageously leads to an LiFSI salt having a mass content of
water of less than or equal to 45 ppm, preferably less than or
equal to 40 ppm by mass relative to the total mass of said
salt.
Step i): Synthesis of Bis(Chlorosulfonyl)Imide
[0145] Compound (A) containing two chlorosulfonyl groups
(bis(chlorosulfonyl)imide) may be prepared from sulfamic acid, in
particular according to the following scheme:
##STR00001##
[0146] According to one embodiment, the reaction temperature is
between 30.degree. C. and 150.degree. C.
[0147] According to one embodiment, the reaction time is between 1
hour and 7 days.
[0148] According to one embodiment, the reaction may be performed
at a pressure of between 1 bar absolute and 7 bar absolute.
[0149] According to one embodiment, the reagents may be
chlorosulfonic acid (ClSO.sub.3H), and a chlorinating agent chosen
from thionyl chloride (SOCl.sub.2), oxalyl chloride (COCl).sub.2,
phosphorus pentachloride (PCl.sub.5), phosphonyl trichloride
(PCl.sub.3), phosphoryl trichloride (POCl.sub.3), and mixtures
thereof.
[0150] According to the invention, a catalyst chosen from a
tertiary amine such as methylamine, triethylamine,
diethylmethylamine; pyridine; and 2,6-lutidine, may be
[0151] added to accelerate the reaction. According to one
embodiment, the mole ratio between the chlorosulfonic acid and the
sulfamic acid is between 1 and 5.
[0152] According to one embodiment, the mole ratio between the
chlorinating agent and the sulfamic acid is between 2 and 5.
[0153] According to one embodiment, the reagents may be sulfamic
acid, and sulfuric acid or oleum, and a chlorinating agent chosen
from thionyl chloride (SOCl.sub.2), oxalyl chloride (COCl).sub.2,
phosphorus pentachloride (PCl.sub.5), phosphonyl trichloride
(PCl.sub.3), phosphoryl trichloride (POCl.sub.3), and mixtures
thereof. A catalyst chosen from a tertiary amine such as
methylamine, triethylamine, diethylmethylamine, pyridine and
2,6-lutidine may be added to accelerate the reaction. According to
one embodiment, the mole ratio between the sulfuric acid (or the
oleum) and the sulfamic acid is between 0.7 and 5. According to one
embodiment, the mole ratio between the chlorinating agent and the
sulfamic acid is between 3 and 10.
Step ii): Fluorination of Bis(Chlorosulfonyl)Imide to
Bis(Fluorosulfonyl)Imide
[0154] The process for preparing the LiFSI salt may comprise at
least one step of reacting a compound of formula (A), obtained
especially on conclusion of the abovementioned step i), with
anhydrous hydrofluoric acid, in at least one organic solvent.
[0155] Step ii) especially allows the fluorination of compound (A)
to a compound (B) as described below.
[0156] The fluorination step with anhydrous hydrofluoric acid,
according to the present invention, may be represented
schematically as follows:
##STR00002##
[0157] Preferably, the solvent used in the abovementioned step ii)
is an organic solvent, in particular having a donor number of
between 1 and 70, advantageously between 5 and 65. The donor number
of a solvent represents the value -.DELTA.H, .DELTA.H being the
enthalpy of the interaction between the solvent and antimony
pentachloride (Journal of Solution Chemistry, vol. 13, No. 9,
1984). Organic solvents that may especially be mentioned include
esters, nitriles or dinitriles, ethers or diethers, amines and
phosphines. Combinations thereof may also be used as organic
solvent.
[0158] Methyl acetate, ethyl acetate, butyl acetate, acetonitrile,
propionitrile, isobutyronitrile, glutaronitrile, dioxane,
tetrahydrofuran, triethylamine, tripropylamine,
diethylisopropylamine, pyridine, trimethylphosphine,
triethylphosphine, diethylisopropylphosphine and mixtures thereof
may be suitable for use as solvents.
[0159] Preferably, the solvent is an organic solvent soluble in
water.
[0160] Preferably, the organic solvent is dioxane.
[0161] The reaction step with anhydrous hydrofluoric acid may be
performed at a temperature T preferably between 0.degree. C. and
the boiling point of the solvent or solvent mixture used.
Advantageously, this temperature is between 5.degree. C. and the
boiling point of the solvent or solvent mixture.
[0162] The reaction step with anhydrous hydrofluoric acid may be
performed at a pressure P preferably between 0 and 16 bar abs.
[0163] This step is preferably performed by dissolving the compound
of formula (A) in the solvent or the solvent mixture, prior to the
step of reaction with anhydrous HF.
[0164] The mass ratio between the compound of formula (A) and the
solvent or solvent mixture is preferably between 0.001 and 10, and
advantageously between 0.005 and 5.
[0165] According to one embodiment, HF is introduced into the
reaction medium preferably in gaseous form.
[0166] The mole ratio x between the HF and the compound of formula
(A) used is preferably between 2 and 10, and advantageously between
2 and 5.
[0167] The step of reaction with HF may be performed in a closed
medium or in an open medium; preferably, step iii) is performed in
an open medium with evolution of HCl in gaseous form.
[0168] The use of a donor solvent in particular allows the
formation of a solvent-HF complex, and thus to enhance the
nucleophilicity of the fluorine atom. The use of such a complex
advantageously allows mild fluorination of the compound of formula
(A), thus avoiding spurious cleavage reactions.
Step iii): Preparation of the Bis(Fluorosulfonyl)Imide Salt by
Neutralization of the Bis(Fluorosulfonyl)Imide
[0169] According to one embodiment, the process for preparing the
lithium bis(fluorosulfonyl)imide salt comprises, on conclusion of
the fluorination step ii), a neutralization step (step iii)).
[0170] According to one embodiment, the neutralization step is
performed using an aqueous solution of a base chosen from alkali
metal or alkaline-earth metal carbonates of formula
MCO.sub.3nH.sub.2O or alkali metal or alkaline-earth metal
hydroxides MOHnH.sub.2O with M representing a monovalent alkali
metal or alkaline-earth metal cation. Preferably, MOH represents
NaOH, KOH RbOH or CsOH. Preferably, MCO.sub.3 represents
Na.sub.2CO.sub.3, K.sub.2CO.sub.3, Rb.sub.2CO.sub.3 or
Cs.sub.2CO.sub.3.
[0171] Preferably, M does not represent Li.
[0172] Preferably, the base used is not a base comprising lithium.
Preferably, the base used comprises potassium.
[0173] The abovementioned step iii) is especially performed
according to the following scheme:
##STR00003##
[0174] Preferably, the neutralization step leads to a solution of
(C) with a pH of greater than 4.
[0175] In particular, the residual HF and/or the residual HCl
dissolved in the solvent reacts with the base described above, so
as to form an alkali metal or alkaline-earth metal fluoride MF (or
a mixture of fluorides MF), or, respectively, an alkali metal or
alkaline-earth metal chloride MCl (or a mixture of chlorides MCl).
The neutralization reaction may be performed, for example, by
adding an aqueous solution of the chosen base. The base/compound
(B) mole ratio may be, for example, from 1 to 5 when the base is a
hydroxide, or from 0.5 to 5 (or from 2 to 10) when the base is a
carbonate. The reaction temperature may be, for example, between
-10.degree. C. and 40.degree. C.
[0176] According to the invention, the aqueous solution comprising
compound (C) may then be filtered.
[0177] Depending on the nature of the alkali metal or
alkaline-earth metal, the product (C) may be present in the
filtrate or in the filtered solid. The alkali metal or
alkaline-earth metal fluorides are especially present in the
filtered solid, but may also be found in the filtrate.
[0178] Two different steps for recovering the product (C) may be
used on conclusion of step iii), depending on where the product (C)
is predominantly found: step R1 or step R2.
[0179] According to a first recovery method (step R1), when the
product (C) is predominantly contained in the aqueous phase
(filtrate), the aqueous phase may be extracted with an organic
solvent chosen from the following families: esters, nitriles,
ethers, chlorinated solvents, aromatic solvents, and mixtures
thereof. Preferably, the organic solvent is chosen from
dichloromethane, ethyl acetate, butyl acetate, tetrahydrofuran,
acetonitrile and diethyl ether, and mixtures thereof. In
particular, it is butyl acetate.
[0180] For each extraction, the mass amount of organic solvent used
may range between 1/6 and 1 times the mass of the aqueous phase.
The number of extractions may be between 2 and 10. Preferably, the
organic phase resulting from the extraction has a mass content of
bis(fluorosulfonyl)imide salt ranging from 5% to 50% by mass. The
organic phase may then be concentrated to reach a
bis(fluorosulfonyl)imide salt concentration of between 5% and 55%,
preferably between 10% and 50% by mass, said concentration possibly
being achieved by any evaporation means known to those skilled in
the art.
[0181] According to a second recovery method (step R2), when it is
mainly contained in the cake (filtered solid), the product (C) may
be recovered by washing the cake with an organic solvent chosen
from the following families: esters, nitriles, ethers, chlorinated
solvents, aromatic solvents, and mixtures thereof. Preferably, the
organic solvent is chosen from dichloromethane, ethyl acetate,
butyl acetate, tetrahydrofuran, acetonitrile and diethyl ether, and
mixtures thereof. In particular, it is butyl acetate.
[0182] The mass amount of organic solvent used may range between 1
and 10 times the weight of the cake. The total amount of organic
solvent intended for the washing may be used in a single portion or
in several portions for the purpose especially of optimizing the
dissolution of the product (C). Preferably, the organic phase
resulting from the extraction has a mass content of LiFSI salt
ranging from 5% to 50% by mass. The organic phase may then be
concentrated to reach a bis(fluorosulfonyl)imide salt concentration
of between 5% and 55%, preferably between 10% and 50% by mass, said
concentration possibly being achieved by any evaporation means
known to those skilled in the art.
[0183] Preferably, compound (C) is such that M=K.
Step iv): Cation Exchange to Obtain a Lithium
Bis(Fluorosulfonyl)Imide Salt
[0184] A final cation-exchange step may be performed, for example
according to the following scheme:
##STR00004##
in which M.sup.1=Li and X may be a fluoride, a chloride, a
carbonate, a hydroxide, a sulfate, a chlorate, a perchlorate, a
nitrite or a nitrate.
[0185] The salt M.sup.1X may be dissolved in a polar organic
solvent chosen from the following families: alcohols, nitriles and
carbonates. Examples that may especially be mentioned include
methanol, ethanol, acetonitrile, dimethyl carbonate and ethyl
methyl carbonate. This solution may be poured into a solution of
product (C) in an organic solvent chosen from the following
families: esters, nitriles, ethers, chlorinated solvents, aromatic
solvents, and mixtures thereof. Preferably, the solvent is chosen
from dichloromethane, ethyl acetate, butyl acetate,
tetrahydrofuran, acetonitrile and diethyl ether, and mixtures
thereof. Preferably, the solvent is butyl acetate.
[0186] The mole ratio of product (C) relative to M.sup.1X may vary:
it may be at least equal to 1 and less than 5. Preferably, the mole
ratio (C)/M.sup.1X is between 1.2 and 2.
[0187] The reaction medium may be left stirring for between 1 and
24 hours at a temperature of between, for example, 0 and 50.degree.
C. At the end of the reaction, the reaction medium may be filtered
to remove the precipitated MX formed. The filtrate may then be
concentrated to remove the solvent for the salt M.sup.1X with a
boiling point of less than or equal to 90.degree. C. A precipitate
of MX may then form again and may be removed by filtration. By
means of this purification, the relative mass content of the
impurity M relative to the product (D) is advantageously less than
or equal to 500 ppm.
[0188] According to a first embodiment, the solution of the product
(D) obtained after the filtration(s) is evaporated, with a
thin-film evaporator, with an atomizer, with a rotary evaporator,
or with any other apparatus for solvent evaporation.
[0189] Compound (D) may then be subjected to the purification and
drying process according to the invention described above,
especially comprising the following steps: [0190] a) addition of
deionized water to form an aqueous solution of compound (D)
(lithium bis(fluorosulfonyl)imide salt); [0191] a') optional
concentration of said aqueous solution; [0192] b) extraction of the
lithium bis(fluorosulfonyl)imide salt from said aqueous solution,
using an organic solvent S2 forming an azeotropic mixture with
water, this step being repeated at least once; [0193] c)
concentration of the lithium bis(fluorosulfonyl)imide salt by
evaporation of said organic solvent S2 and of the water, and [0194]
d) optional crystallization of the lithium bis(fluorosulfonyl)imide
salt.
[0195] The product (D) purified according to the process of the
invention is advantageously in the form of a white powder.
[0196] The present invention also relates to a lithium
bis(fluorosulfonyl)imide salt comprising a mass content of water of
between 5 and 45 ppm, preferably between 5 and 40 ppm by mass
relative to the total mass of said salt.
[0197] The present invention also relates to a composition C
comprising: [0198] at least 99.80%, preferably at least 99.85%,
advantageously at least 99.90% and preferentially at least 99.95%
by weight of lithium bis(fluorosulfonyl)imide salt (LiFSI) relative
to the total weight of the composition; and [0199] between 5 ppm
and 45 ppm, preferably between 5 and 40 ppm by mass of water
relative to the total mass of composition C.
[0200] In the LiFSI salt according to the invention (or in
composition C according to the invention), the mass proportion of
water may be, for example, between 8 and 45 ppm, between 9 and 45
ppm, between 10 and 45 ppm, between 11 and 45 ppm, between 12 and
45 ppm, between 13 and 45 ppm, between 14 and 45 ppm, between 15
and 45 ppm, between 16 and 45 ppm, between 17 and 45 ppm, between
18 and 45 ppm, between 19 and 45 ppm, between 20 and 45 ppm,
between 21 and 45 ppm, between 22 and 45 ppm, between 23 and 45
ppm, between 24 and 45 ppm, between 25 and 45 ppm, between 26 and
45 ppm, between 27 and 45 ppm, between 28 and 45 ppm, between 29
and 45 ppm, between 30 and 45 ppm, between 8 and 40 ppm, between 9
and 40 ppm, between 10 and 40 ppm, between 11 and 40 ppm, between
12 and 40 ppm, between 13 and 40 ppm, between 14 and 40 ppm,
between 15 and 40 ppm, between 16 and 40 ppm, between 17 and 40
ppm, between 18 and 40 ppm, between 19 and 40 ppm, between 20 and
40 ppm, between 21 and 40 ppm, between 22 and 40 ppm, between 23
and 40 ppm, between 24 and 40 ppm, between 25 and 40 ppm, between
26 and 40 ppm, between 27 and 40 ppm, between 28 and 40 ppm,
between 29 and 40 ppm or between 30 and 40 ppm by mass relative to
the total mass of said salt (or, respectively, relative to the
total mass of composition C).
[0201] In the LiFSI salt according to the invention (or in
composition C according to the invention), the mass proportion of
sulfate ions may be, for example, less than or equal to 200 ppm,
less than or equal to 160 ppm, less than or equal to 150 ppm, less
than or equal to 130 ppm, less than or equal to 120 ppm, less than
or equal to 110 ppm, less than or equal to 100 ppm, or less than or
equal to 90 ppm by mass relative to the total mass of said salt
(or, respectively, relative to the total mass of composition
C).
[0202] In the LiFSI salt according to the invention (or in
composition C according to the invention), the mass proportion of
sulfate ions may be, for example, between 5 and 200 ppm, between 5
and 160 ppm, between 5 and 150 ppm, between 5 and 140 ppm, between
5 and 130 ppm, between 5 and 120 ppm, between 5 and 110 ppm,
between 5 and 100 ppm, between 5 and 80 ppm, between 8 and 200 ppm,
between 8 and 160 ppm, between 8 and 150 ppm, between 8 and 140
ppm, between 8 and 130 ppm, between 8 and 120 ppm, between 8 and
110 ppm, between 8 and 100 ppm, between 8 and 80 ppm, between 10
and 160 ppm, between 10 and 150 ppm, between 10 and 140 ppm,
between 10 and 130 ppm, between 10 and 120 ppm, between 10 and 110
ppm, between 10 and 100 ppm, between 10 and 80 ppm, between 15 and
160 ppm, between 15 and 150 ppm, between 15 and 140 ppm, between 15
and 130 ppm, between 15 and 120 ppm, between 15 and 110 ppm,
between 15 and 100 ppm, between 15 and 80 ppm, between 20 and 200
ppm, between 20 and 160 ppm, between 20 and 150 ppm, between 20 and
140 ppm, between 20 and 130 ppm, between 20 and 120 ppm, between 20
and 110 ppm, between 20 and 100 ppm, between 20 and 80 ppm, between
25 and 160 ppm, between 25 and 150 ppm, between 25 and 140 ppm,
between 25 and 130 ppm, between 25 and 120 ppm, between 25 and 110
ppm, between 25 and 100 ppm, or between 25 and 80 ppm by mass
relative to the total mass of said salt (or, respectively, relative
to the total mass of composition C).
[0203] According to one embodiment, the LiFSI salt (or composition
C according to the invention) has a content of Cl.sup.- ions of
less than or equal to 50 ppm by weight relative to the total weight
of said salt (or, respectively, relative to the total weight of
composition C).
[0204] In particular, the LiFSI salt according to the invention (or
composition C according to the invention) comprises the following
impurities: F.sup.-.ltoreq.200 ppm (preferably .ltoreq.50 ppm),
FSO.sub.3Li.ltoreq.200 ppm, FSO.sub.2NH.sub.2.ltoreq.200 ppm,
CO.sub.3.sup.2-.ltoreq.50 ppm, ClO.sup.-.ltoreq.50 ppm,
ClO.sub.4.sup.-.ltoreq.50 ppm, NO.sub.2.sup.-.ltoreq.50 ppm,
NO.sub.3.sup.-.ltoreq.50 ppm, Si.ltoreq.40 ppm, Mg.ltoreq.10 ppm,
Fe.ltoreq.10 ppm, Ca.ltoreq.10 ppm, Pb.ltoreq.10 ppm, Cu.ltoreq.10
ppm, Cr.ltoreq.10 ppm, Ni.ltoreq.10 ppm, Al.ltoreq.10 ppm,
Zn.ltoreq.10 ppm, and Na.ltoreq.10 ppm.
[0205] According to a preferred embodiment, the LiFSI according to
the invention (or composition C according to the invention)
comprises: [0206] a mass content of water of between 5 and 45 ppm,
and in particular between, for example, 8 and 45 ppm, between 9 and
45 ppm, between 10 and 45 ppm, between 11 and 45 ppm, between 12
and 45 ppm, between 13 and 45 ppm, between 14 and 45 ppm, between
15 and 45 ppm, between 16 and 45 ppm, between 17 and 45 ppm,
between 18 and 45 ppm, between 19 and 45 ppm, between 20 and 45
ppm, between 21 and 45 ppm, between 22 and 45 ppm, between 23 and
45, between 24 and 45 ppm, between 25 and 45, between 26 and 45
ppm, between 27 and 45 ppm, between 28 and 45 ppm, between 29 and
45 ppm, between 30 and 45 ppm, or between 30 and 40 ppm by mass
relative to the total mass of said salt (or, respectively, relative
to the total mass of composition C); [0207] a mass content of
sulfate ions of less than or equal to 200 ppm, for example between
5 and 200 ppm, between 5 and 160 ppm, between 5 and 150 ppm,
between 5 and 140 ppm, between 5 and 130 ppm, between 5 and 120
ppm, between 5 and 110 ppm, between 5 and 100 ppm, between 5 and 80
ppm, between 8 and 200 ppm, between 8 and 160 ppm, between 8 and
150 ppm, between 8 and 140 ppm, between 8 and 130 ppm, between 8
and 120 ppm, between 8 and 110 ppm, between 8 and 100 ppm, between
8 and 80 ppm, between 10 and 160 ppm, between 10 and 150 ppm,
between 10 and 140 ppm, between 10 and 130 ppm, between 10 and 120
ppm, between 10 and 110 ppm, between 10 and 100 ppm, between 10 and
80 ppm, between 15 and 160 ppm, between 15 and 150 ppm, between 15
and 140 ppm, between 15 and 130 ppm, between 15 and 120 ppm,
between 15 and 110 ppm, between 15 and 100 ppm, between 15 and 80
ppm, between 20 and 200 ppm, between 20 and 160 ppm, between 20 and
150 ppm, between 20 and 140 ppm, between 20 and 130 ppm, between 20
and 120 ppm, between 20 and 110 ppm, between 20 and 100 ppm,
between 20 and 80 ppm, between 25 and 160 ppm, between 25 and 150
ppm, between 25 and 140 ppm, between 25 and 130 ppm, between 25 and
120 ppm, between 25 and 110 ppm, between 25 and 100 ppm, or between
25 and 80 ppm by mass relative to the total mass of said salt (or,
respectively, relative to the total mass of composition C); and
[0208] a mass content of Cl.sup.- of less than or equal to 50 ppm
by weight; [0209] a mass content of F.sup.- of less than or equal
to 200 ppm, preferably less than or equal to 50 ppm; [0210] a mass
content of FSO.sub.3Li of less than or equal to 200 ppm; [0211] a
mass content of FSO.sub.2NH.sub.2 of less than or equal to 200 ppm;
[0212] a mass content of CO.sub.3.sup.2- of less than or equal to
50 ppm; [0213] a mass content of ClO.sub.3.sup.- of less than or
equal to 50 ppm; [0214] a mass content of ClO.sub.4.sup.- of less
than or equal to 50 ppm; [0215] a mass content of NO.sub.2.sup.- of
less than or equal to 50 ppm; [0216] a mass content of
NO.sub.3.sup.- of less than or equal to 50 ppm; [0217] a mass
content of Si of less than or equal to 40 ppm; [0218] a mass
content of Mg of less than or equal to 10 ppm; [0219] a mass
content of Fe of less than or equal to 10 ppm; [0220] a mass
content of Ca of less than or equal to 10 ppm; [0221] a mass
content of Pb of less than or equal to 10 ppm; [0222] a mass
content of Cu of less than or equal to 10 ppm; [0223] a mass
content of Cr of less than or equal to 10 ppm; [0224] a mass
content of Ni of less than or equal to 10 ppm; [0225] a mass
content of Al of less than or equal to 10 ppm; [0226] a mass
content of Zn of less than or equal to 10 ppm; and [0227] a mass
content of Na of less than or equal to 10 ppm.
[0228] The present invention also relates to the use of the LiFSI
salt according to the invention (or composition C according to the
invention) in Li-ion batteries, especially in Li-ion battery
electrolytes.
[0229] In particular, the LiFSI salt according to the invention (or
composition C according to the invention) may be used in Li-ion
batteries of mobile devices (for example cellphones, cameras,
tablet or laptop computers), or electric vehicles, or for storing
renewable energy (such as photovoltaic or wind energy).
[0230] The LiFSI salt (or composition C according to the invention)
may be used especially in batteries of "pocket" type (also known as
"pouch cells").
[0231] The LiFSI salt (or composition C according to the invention)
may advantageously be used in applications at high or low
temperature.
[0232] The LiFSI salt according to the invention (or composition C
according to the invention) advantageously has at least one of the
following advantages: [0233] reduction of the risks of
short-circuiting, of ignition or of explosion of the battery;
[0234] longer service life; [0235] increase in the number of
charging cycles; [0236] reduction or even elimination of corrosion
of the battery constituents, such as the Al collector; [0237]
reduction of the risks of swelling of the battery, especially of
flexible batteries of "pocket" type (known as "pouch cells");
[0238] good resistance to high and/or low temperature.
[0239] In the context of the invention, the term "between x and y"
or "ranging from x to y" means a range in which the limits x and y
are included. For example, the temperature "between 30 and
100.degree. C." especially includes the values 30.degree. C. and
100.degree. C.
[0240] All the embodiments described above may be combined with
each other. In particular, each embodiment of any step of the
process of the invention may be combined with another particular
embodiment.
[0241] The present invention is illustrated by the example which
follows, to which it is not, however, limited.
Example 1: Purification and Analysis of the Contents of Impurities
in the Lithium Bis(Fluorosulfonyl)Imide Salt Prepared by the
Process According to the Invention
[0242] Various impurities present in the lithium
bis(fluorosulfonyl)imide salt were analyzed and the results
obtained are presented below.
Purification of a Solution of LiFSI in Butyl Acetate
[0243] A solution is taken containing 166 g of LiFSI (which may be
obtained, for example, according to the process described in WO
2015/158979) in 830 g of butyl acetate. It is concentrated in a
rotary evaporator heated to 40.degree. C. under vacuum (pressure
<30 mbar abs). A solution is obtained whose solids content is
34% by mass. Aqueous extraction of the LiFSI contained is performed
three times (addition of 1/2 mass of water relative to the mass of
the concentrated solution (solids content of 34% by mass), and then
1/3 mass of water relative to the mass of the concentrated solution
(solids content of 34% by mass) and then 1/4 of mass of water
relative to the mass of the concentrated solution (solids content
of 34% by mass)). The aqueous phases are pooled (the solids content
is 18% by mass) and concentrated by evaporation under vacuum
(P<30 mbar abs) at 40.degree. C., to obtain a solution whose
solids content is 32% by mass. The LiFSI recovery yield is 73%. The
LiFSI dissolved in water is then re-extracted with four successive
extractions in butyl acetate by 1/4 of the mass of the aqueous
solution. A solution of LiFSI in butyl acetate is obtained (the
solids content being about 12%). The LiFSI extraction yield is
62%.
Drying of the LiFSI
[0244] The solvent-phase extractions are pooled and concentrated
first on a rotary evaporator at 40.degree. C. under reduced
pressure (P<30 mbar abs). A solution of LiFSI whose solids
content is 42% is obtained. The final concentration is performed on
a thin-film evaporator (of Luwa type) at 90.degree. C. with an
internal surface area of 0.04 m.sup.2 and under a pressure of 5
mbar abs for a time of 1 hour 11 minutes. 72 g of LiFSI which
crystallizes when cold are obtained, and are recovered by
filtration, the analysis of which is given below.
Sampling for the Quantification of Li, Na and Trace Elements from
the List Provided:
[0245] The sample of the lithium bis(fluorosulfonyl)imide salt
obtained according to the process described above is dissolved in
ultra-pure water. Two dilutions were used: 1 g/l for the
determination of the Na, and the elements Ag, Al, As, Ba, Si, Cd,
Co, Cr, Cu, Ni, Pb, Sb, Se, Sn, Sr, Ti and Zn in trace amount, and
0.1 g/l for the analysis of the lithium.
Panoramic Qualitative Analysis:
[0246] The ICP-AES (inductively-coupled plasma spectrometry)
conditions applied for the "panoramic" semiquantitative analysis of
the elements in trace amount are: [0247] Output power of the plasma
source: 1150 W [0248] Flow rate of the nebulization gas: 0.7 L/min
[0249] Cooling rate=16 L/min [0250] Torch height: 12 mm [0251] Pump
speed: 50 rpm [0252] Spectral bandwidth: 7 pm to 200 nm, 3.5 nm per
pixel [0253] Wavelength range: 167 nm to 847 nm.
[0254] The ICP-AES quantification method for measuring Li, Na used
five calibration points. The ICP-AES data are obtained on an ICAP
6500 spectrometer (Thermo Electronics).
[0255] For the analysis of the elements in trace amount Ag, Al, As,
Ba, Si, Cd, Co, Cr, Cu, Ni, Pb, Sb, Se, Sn, Sr, Ti, Zn, the
semiquantitative method is based on two calibration points.
[0256] For the two methods, sampling is performed by addition of
standards to the sample itself so as to minimize the matrix
effects.
[0257] ICP-AES is preferred to cationic chromatography in aqueous
solution for the measurement of the elements Li and Na.
[0258] The conditions for analysis of the anions in ion
chromatography (IC) are as follows: [0259] Thermo ICS 5000 DUAL
machine; [0260] AS16-HC column; [0261] Flow rate 1 ml/min; [0262]
Eluent isocratic KOH at 20 mmol/l; [0263] Conductimetric detection;
[0264] ASRS 4 mm suppressor with 50 mA of imposed current; [0265]
Injection of 25 .mu.l of LiFSI solutions at 5 g/l and 10 g/l
depending on the sensitivity required for the anionic species
present; [0266] Calibration of each anionic species with five
synthetic solutions ranging from 0.1 mg/l up to 25 mg/l.
[0267] The NMR analysis conditions for the fluorinated species such
as FSO.sub.3Li and FSO.sub.2NH.sub.2 in .sup.1H and .sup.19F NMR
are as follows: [0268] Equipment: The NMR spectra and
quantifications were performed on a Bruker AV 400 spectrometer, at
t 376.47 MHz for .sup.19F, on a 5 mm probe of BBFO.sup.+ type.
[0269] Sampling: The samples are dissolved in DMSO-d6 (about 30 mg
in 0.6 ml). In the case of detection of fluorides or of addition of
LiF serving to check the undesirable presence of fluorides, the
solvent used is D.sub.2O on account of the insolubility of LiF in
DMSO. [0270] Quantification: The relative quantification in
fluorine-19 NMR (.sup.19F NMR) is performed by integration of the
signals for the fluorinated species, weighted by the number of
fluorines contributing to the signal, which is a method well known
to those skilled in the art.
[0271] The absolute quantification in .sup.19F NMR is performed by
dosed addition of .alpha.?.alpha.?.alpha.-trifluorotoluene (TFT,
Aldrich) to the tube containing the sample, and by integration of
the signals for the fluorinated species to be assayed in comparison
with that of the CF.sub.3 of this internal standard, according to
the method that is well known to those skilled in the art. The
quantification limit for a species is of the order of a 50th of a
ppm. [0272] Water content: Performed by Karl Fischer assay on a 684
KF coulometer coupled to an 860 KF Thermoprep (Metrohm
equipment).
[0273] The solid sample of LiFSI is transferred in a glovebox into
a suitable Thermoprep bottle. It is heated at 50.degree. C. for 30
minutes and the gas phase is then introduced into the assay cell of
the KF titrimeter.
[0274] The results obtained are presented in table I.
TABLE-US-00001 TABLE I Species Amount Analysis method
FSO.sub.2NH.sub.2 ND .sup.19F NMR FSO.sub.3Li ND .sup.19F NMR
H.sub.2O 34 ppm Karl Fischer SO.sub.4.sup.2- 80 ppm Cl Cl- 35 ppm
Cl F- <50 ppm NMR CO.sub.3.sup.2- ND Cl ClO.sub.3.sup.- ND Cl
ClO.sub.4.sup.- ND Cl NO.sub.2.sup.- ND Cl NO.sub.3.sup.- ND Cl Mg
ND ICP Si ND FX Fe ND ICP Ca ND ICP Pb ND ICP Cu ND ICP Cr ND ICP
Ni ND ICP Al ND ICP Zn ND ICP Na ND ICP ND: not detected
[0275] The purification and drying process according to the
invention advantageously makes it possible to obtain an LiFSI salt
with a low content of residual water, namely less than or equal to
40 ppm, and a low content of impurities. For example, the sulfate
content is less than 100 ppm, and is especially 80 ppm.
Embodiments
[0276] 1. A process for drying and purifying a lithium
bis(fluorosulfonyl)imide salt in solution in an organic solvent S1,
said process comprising the following steps: [0277] a) addition of
deionized water to dissolve and extract the lithium
bis(fluorosulfonyl)imide salt, forming an aqueous solution of said
salt, this step preferably being repeated at least once; [0278] a')
optional concentration of said aqueous solution;
[0279] b) extraction of the lithium bis(fluorosulfonyl)imide salt
from said aqueous solution, with an organic solvent S2 forming an
azeotropic mixture with water, this step being repeated at least
once; [0280] c) concentration of said lithium
bis(fluorosulfonyl)imide salt by evaporation of said organic
solvent S2 and of the water, and [0281] d) optionally,
crystallization of the lithium bis(fluorosulfonyl)imide salt.
[0282] 2. The process as in embodiment 1, comprising step a') of
concentration of said aqueous solution, preferably to obtain an
aqueous solution comprising a lithium bis(fluorosulfonyl)imide salt
content of between 20% and 80%, preferentially between 30% and
65%.
[0283] 3. The process as in either of embodiments 1 and 2, in which
step a) is such that the mass of deionized water is greater than or
equal to a third and preferably greater than or equal to half of
the mass of the initial solution of the lithium
bis(fluorosulfonyl)imide salt in the organic solvent S1.
[0284] 4. The process as in any one of embodiments 1 to 3, in which
the organic solvent S2 is chosen from the group constituted of
esters, nitriles, ethers, chlorinated solvents, aromatic solvents,
and mixtures thereof, the organic solvent S2 in particular being
chosen from the group constituted of methyl t-butyl ether,
cyclopentyl methyl ether, ethyl acetate, propyl acetate, butyl
acetate, and mixtures thereof, said organic solvent S2
preferentially being butyl acetate.
[0285] 5. The process as in any one of embodiments 1 to 4, in which
the organic solvent S1 is chosen from the group constituted of
esters, nitriles, ethers, chlorinated solvents and aromatic
solvents, and mixtures thereof, the solvent S1 being chosen in
particular from dichloromethane, ethyl acetate, butyl acetate,
tetrahydrofuran, acetonitrile and diethyl ether, and mixtures
thereof.
[0286] 6. The process as in any one of embodiments 1 to 5, in which
the organic solvent S2/water mass ratio, during an extraction,
ranges from 1/6 to 1/1, the number of extractions ranging in
particular from 2 to 10.
[0287] 7. The process as in any one of embodiments 1 to 6, also
comprising, between step b) and step c), a step c') of
concentration of the organic solution obtained on conclusion of
step b), to obtain an organic solution with a mass content of LiFSI
of between 20% and 60%.
[0288] 8. The process as in any one of embodiments 1 to 7, in
which, during step c), the organic phases formed during step b) are
pooled and concentrated by evaporation at a temperature of between
30.degree. C. and 100.degree. C., preferably between 40.degree. C.
and 90.degree. C., and at a pressure of between 200 mbar abs and
0.5 mbar abs.
[0289] 9. The process as in any one of embodiments 1 to 8, in which
the organic phase separated from the aqueous solution extracted in
step a) is not reintroduced into the subsequent steps b) to d) of
the process, and in particular it is not pooled with the organic
phases extracted during step b).
[0290] 10. The process as in any one of embodiments 1 to 9, in
which the lithium bis(fluorosulfonyl)imide salt obtained on
conclusion of step c) comprises less than 10% by weight of residual
solvent, preferably less than 5% by weight.
[0291] 11. The process as in any one of embodiments 1 to 10, in
which, during step d), the lithium bis(fluorosulfonyl)imide salt is
crystallized under cold conditions at a temperature of less than or
equal to 25.degree. C., optionally in an organic solvent S3 chosen
from chlorinated solvents, for instance dichloromethane, and
aromatic solvents, for instance toluene, said salt optionally being
recovered by filtration.
[0292] 12. The process as in any one of embodiments 1 to 11,
characterized in that it leads to a lithium
bis(fluorosulfonyl)imide salt having a mass content of water of
less than or equal to 45 ppm by mass relative to the total mass of
said salt.
[0293] 13. A process for manufacturing a lithium
bis(fluorosulfonyl)imide salt, comprising the following steps:
[0294] i. synthesis of bis(chlorosulfonyl)imide from sulfamic acid;
[0295] ii. fluorination of bis(chlorosulfonyl)imide to
bis(fluorosulfonyl)imide; and [0296] iii. preparation of the alkali
metal or alkaline-earth metal salt of bis(fluorosulfonyl)imide by
neutralization of the bis(fluorosulfonyl)imide, in particular using
an aqueous solution of a base chosen from alkali metal or
alkaline-earth metal carbonates, and alkali metal or alkaline-earth
metal hydroxides; [0297] iv. cation exchange to obtain a lithium
bis(fluorosulfonyl)imide salt; and [0298] v. drying and
purification process as in any one of embodiments 1 to 12.
[0299] 14. The process as in embodiment 13, leading to the
formation of a lithium bis(fluorosulfonyl)imide salt having a mass
content of water of less than or equal to 45 ppm by mass relative
to the total mass of said salt.
[0300] 15. A composition C comprising: [0301] at least 99.80%,
preferably at least 99.85%, advantageously at least 99.90% and
preferentially at least 99.95% by weight of lithium
bis(fluorosulfonyl)imide (LiFSI) salt relative to the total weight
of said composition C; [0302] between 5 ppm and 45 ppm, preferably
between 5 and 40 ppm by mass of water relative to the total mass of
said composition C.
[0303] 16. The composition C as in embodiment 15, comprising a mass
content of sulfate ions of less than or equal to 200 ppm,
preferably between 5 and 160 ppm by mass relative to the total mass
of said composition C.
[0304] 17. The composition C as in either of embodiments 15 and 16,
comprising: [0305] a mass content of water of between 5 and 45 ppm,
and in particular between, for example, 8 and 45 ppm, between 9 and
45 ppm, between 10 and 45 ppm, between 11 and 45 ppm, between 12
and 45 ppm, between 13 and 45 ppm, between 14 and 45 ppm, between
15 and 45 ppm, between 16 and 45 ppm, between 17 and 45 ppm,
between 18 and 45 ppm, between 19 and 45 ppm, between 20 and 45
ppm, between 21 and 45 ppm, between 22 and 45 ppm, between 23 and
45 ppm, between 24 and 45 ppm, between 25 and 45 ppm, between 26
and 45 ppm, between 27 and 45 ppm, between 28 and 45 ppm, between
29 and 45 ppm, between 30 and 45 ppm, or between 30 and 40 ppm by
mass relative to the total mass of said composition C; [0306] a
mass content of sulfate ions of less than or equal to 200 ppm, for
example between 5 and 200 ppm, between 5 and 160 ppm, between 5 and
150 ppm, between 5 and 140 ppm, between 5 and 130 ppm, between 5
and 120 ppm, between 5 and 110 ppm, between 5 and 100 ppm, between
5 and 80 ppm, between 8 and 200 ppm, between 8 and 160 ppm, between
8 and 150 ppm, between 8 and 140 ppm, between 8 and 130 ppm,
between 8 and 120 ppm, between 8 and 110 ppm, between 8 and 100
ppm, between 8 and 80 ppm, between 10 and 160 ppm, between 10 and
150 ppm, between 10 and 140 ppm, between 10 and 130 ppm, between 10
and 120 ppm, between 10 and 110 ppm, between 10 and 100 ppm,
between 10 and 80 ppm, between 15 and 160 ppm, between 15 and 150
ppm, between 15 and 140 ppm, between 15 and 130 ppm, between 15 and
120 ppm, between 15 and 110 ppm, between 15 and 100 ppm, between 15
and 80 ppm, between 20 and 200 ppm, between 20 and 160 ppm, between
20 and 150 ppm, between 20 and 140 ppm, between 20 and 130 ppm,
between 20 and 120 ppm, between 20 and 110 ppm, between 20 and 100
ppm, between 20 and 80 ppm, between 25 and 160 ppm, between 25 and
150 ppm, between 25 and 140 ppm, between 25 and 130 ppm, between 25
and 120 ppm, between 25 and 110 ppm, between 25 and 100 ppm, or
between 25 and 80 ppm by mass relative to the total mass of said
composition C; and [0307] a mass content of Cl.sup.- of less than
or equal to 50 ppm by weight; [0308] a mass content of F.sup.- of
less than or equal to 200 ppm, preferably less than or equal to 50
ppm; [0309] a mass content of LiFSO.sub.3 of less than or equal to
200 ppm; [0310] a mass content of FSO.sub.2NH.sub.2 of less than or
equal to 200 ppm; [0311] a mass content of CO.sub.3.sup.2- of less
than or equal to 50 ppm; [0312] a mass content of ClO.sub.3.sup.-
of less than or equal to 50 ppm; [0313] a mass content of
ClO.sub.4.sup.- of less than or equal to 50 ppm; [0314] a mass
content of NO.sub.2.sup.- of less than or equal to 50 ppm; [0315] a
mass content of NO.sub.3.sup.- of less than or equal to 50 ppm;
[0316] a mass content of Si of less than or equal to 40 ppm; [0317]
a mass content of Mg of less than or equal to 10 ppm; [0318] a mass
content of Fe of less than or equal to 10 ppm; [0319] a mass
content of Ca of less than or equal to 10 ppm; [0320] a mass
content of Pb of less than or equal to 10 ppm; [0321] a mass
content of Cu of less than or equal to 10 ppm; [0322] a mass
content of Cr of less than or equal to 10 ppm; [0323] a mass
content of Ni of less than or equal to 10 ppm; [0324] a mass
content of Al of less than or equal to 10 ppm; [0325] a mass
content of Zn of less than or equal to 10 ppm; and [0326] a mass
content of Na of less than or equal to 10 ppm.
[0327] 18. The use of a composition C as in any one of embodiments
15 to 17, in Li-ion batteries.
[0328] 19. The use as in embodiment 18, in mobile devices, for
example cellphones, cameras, tablet or laptop computers, in
electric vehicles, or in the storage of renewable energy (such as
photovoltaic or wind energy).
* * * * *