CA2856123C - Process for preparing metal difluorochelatoborates, and use as battery electrolytes or additives in electrochemical cells - Google Patents
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Abstract
The invention relates to a process for preparing metal difluorochelatoborates, in which a metal bis(chelato)borate of the formula M[BL2] is reacted with boron trifluoride and a metal fluoride (MF) and/or a metal salt of the chelating ligand (M2L) where M+ is a monovalent cation selected from the group consisting of lithium, sodium, potassium and ammonium NR4 +, where R = H, alkyl (C1 to C8) and L is a chelating agent having two terminal oxygen atoms and having the general formula (II), where: when m = 1 and Y1 and Y2 together with C1 form a carbonyl group, n = 0 or 1 and o = 0 or 1 and R1 and R2 are each, independently of one another, H or alkyl having from one to eight carbon atoms (C1-C8) and Y3, Y4 are each, independently of one another, OR3 (R3 = C1-C8-alkyl), then n or o ? 1: p = 0 or 1 and when n and o = 0, p = 1; or Y1, Y2, Y3, Y4 are each, independently of one another, OR3 (R3 = C1-C8-alkyl), m = 1, n = 0 or 1, o = 1 and p = 0; or C2 and C3 are members of a 5- or 6-membered aromatic or heteroaromatic ring (with N, O or S as heteroelement) which can optionally be substituted by alkyl, alkoxy, carboxy or nitrile, where R1, R2, Y3 and Y4 are absent, m = 0 or in the case of 1, Y1 and Y2 together with C1 form a carbonyl group and p is 0 or 1, in an organic, aprotic solvent.
Description
, , - 1 ¨
Process for preparing metal difluorochelatoborates, and use as battery electrolytes or additives in electrochemical cells The invention relates to a process for preparing metal difluorochelatoborates, and their use as battery electrolytes or additives in electrochemical cells.
Mobile electronic devices require increasingly more powerful rechargeable batteries for independently supplying power. In addition to nickel/cadmium and nickel/metal hydride batteries, lithium batteries in particular, which have much higher energy densities than the first-mentioned systems, are suitable for this purpose. In the future, large-scale lithium batteries will also be used, for example, for stationary applications (power back-up) and in the automotive sector for traction purposes (hybrid drives or solely electric drives). Great importance is attached to reliability, in particular for the latter-mentioned applications.
The current generation of lithium-ion batteries presently in use utilizes as an electrolyte liquid, gel, or polymer electrolytes containing LiPF6 as the conductive salt.
This salt starts to decompose when the temperature exceeds approximately 70 C, and forms the highly reactive Lewis acid PF6 according to the formula LiPF6 -4 LiF + PF6 (1).
The acid attacks the organic components of the electrolytes (alkyl carbonates, for example) used according to the prior art. This reaction is exothermic, and may result in "run-away" self-heating. Thus, at the minimum the functionality of the electrochemical cell is impaired, or the cell may be completely destroyed, with hazardous repercussions.
As an alternative electrolyte, solutions of lithium salts containing fluorochelatoborate anion, such as lithiumdifluorooxalatoborate (LiDFOB) (US 6,849,752 Z. Chen, J.
Liu, K.
Amine, Electrochem. Solid State Lett.10 (2007) A45-47) or lithium difluoro(1,2-¨ 2 ¨
benzenediolato(2+0,01-borate (X. Zhao-Ming, J. Power Sources 196 (2011) 8710), among others, have been proposed.
The following discussions focus on the conductive salt LiDFOB. However, they also analogously apply for variations of this structure according to general formula I
_ _ B L M.
Li B\
_ F/
F
LiDFOB General formula I
where M+ is a monovalent cation selected from the group lithium, sodium, potassium, or ammonium NR4+, and R = H or alkyl (Cl to C8, acyclic or cyclic), L is a chelating agent, having two terminal oxygen atoms, with the general formula iN
L= (Y )=0) y2 im R1 R y3 y4 where the following apply:
when m = 1 and Y1 and Y2 together with Cl stand for a carbonyl group, n = 0 or 1 and o = 0 or 1, and R1 and R2 are each independently H or alkyl containing one to eight carbon atoms (C1¨C8), and Y3, Y4 are each independently OR3 (R3 = C1¨C8 alkyl), and when n or o #1, p = 0 or 1, and when n and o = 0, p = 1;
or ¨ 3 ¨
yl, T Y-, Y4 are each independently OR3 (R3 = C1¨C8 alkyl), m = 1, n = 0 or 1, o = 1, and p = 0;
or C2 and C3 are members of a 5- or 6-membered aromatic or heteroaromatic ring (with N, 0, or S as heteroelement) which may optionally be substituted with alkyl, alkoxy, carboxy, or nitrile, where R1, R2, Y3, and Y4 are absent when m = 0, or in the case of m = 1, Y1 and Y2 together with C1 stand for a carbonyl group, and p is 0 or 1.
The conductive salt LiDFOB (M+ = Li and L = C2042-) may be prepared in various ways.
In the reaction of lithium tetrafluoroborate (L1BF4) with 2 equivalents lithium hexafluoroisopropanolate in acetonitrile, initially lithium fluoride (LiF) is eliminated (EP 1195834). The alkoxy ligands of the intermediate product, which are only relatively weakly bonded, are replaced by the better chelate donor, oxalate, in a second step:
F\ /0C H (C F3)2 LiBF4 + Li0--( --Di- Li B
Process for preparing metal difluorochelatoborates, and use as battery electrolytes or additives in electrochemical cells The invention relates to a process for preparing metal difluorochelatoborates, and their use as battery electrolytes or additives in electrochemical cells.
Mobile electronic devices require increasingly more powerful rechargeable batteries for independently supplying power. In addition to nickel/cadmium and nickel/metal hydride batteries, lithium batteries in particular, which have much higher energy densities than the first-mentioned systems, are suitable for this purpose. In the future, large-scale lithium batteries will also be used, for example, for stationary applications (power back-up) and in the automotive sector for traction purposes (hybrid drives or solely electric drives). Great importance is attached to reliability, in particular for the latter-mentioned applications.
The current generation of lithium-ion batteries presently in use utilizes as an electrolyte liquid, gel, or polymer electrolytes containing LiPF6 as the conductive salt.
This salt starts to decompose when the temperature exceeds approximately 70 C, and forms the highly reactive Lewis acid PF6 according to the formula LiPF6 -4 LiF + PF6 (1).
The acid attacks the organic components of the electrolytes (alkyl carbonates, for example) used according to the prior art. This reaction is exothermic, and may result in "run-away" self-heating. Thus, at the minimum the functionality of the electrochemical cell is impaired, or the cell may be completely destroyed, with hazardous repercussions.
As an alternative electrolyte, solutions of lithium salts containing fluorochelatoborate anion, such as lithiumdifluorooxalatoborate (LiDFOB) (US 6,849,752 Z. Chen, J.
Liu, K.
Amine, Electrochem. Solid State Lett.10 (2007) A45-47) or lithium difluoro(1,2-¨ 2 ¨
benzenediolato(2+0,01-borate (X. Zhao-Ming, J. Power Sources 196 (2011) 8710), among others, have been proposed.
The following discussions focus on the conductive salt LiDFOB. However, they also analogously apply for variations of this structure according to general formula I
_ _ B L M.
Li B\
_ F/
F
LiDFOB General formula I
where M+ is a monovalent cation selected from the group lithium, sodium, potassium, or ammonium NR4+, and R = H or alkyl (Cl to C8, acyclic or cyclic), L is a chelating agent, having two terminal oxygen atoms, with the general formula iN
L= (Y )=0) y2 im R1 R y3 y4 where the following apply:
when m = 1 and Y1 and Y2 together with Cl stand for a carbonyl group, n = 0 or 1 and o = 0 or 1, and R1 and R2 are each independently H or alkyl containing one to eight carbon atoms (C1¨C8), and Y3, Y4 are each independently OR3 (R3 = C1¨C8 alkyl), and when n or o #1, p = 0 or 1, and when n and o = 0, p = 1;
or ¨ 3 ¨
yl, T Y-, Y4 are each independently OR3 (R3 = C1¨C8 alkyl), m = 1, n = 0 or 1, o = 1, and p = 0;
or C2 and C3 are members of a 5- or 6-membered aromatic or heteroaromatic ring (with N, 0, or S as heteroelement) which may optionally be substituted with alkyl, alkoxy, carboxy, or nitrile, where R1, R2, Y3, and Y4 are absent when m = 0, or in the case of m = 1, Y1 and Y2 together with C1 stand for a carbonyl group, and p is 0 or 1.
The conductive salt LiDFOB (M+ = Li and L = C2042-) may be prepared in various ways.
In the reaction of lithium tetrafluoroborate (L1BF4) with 2 equivalents lithium hexafluoroisopropanolate in acetonitrile, initially lithium fluoride (LiF) is eliminated (EP 1195834). The alkoxy ligands of the intermediate product, which are only relatively weakly bonded, are replaced by the better chelate donor, oxalate, in a second step:
F\ /0C H (C F3)2 LiBF4 + Li0--( --Di- Li B
-2 LiF
CF3 F OCH(CF3)2 _ (2) 0 \B/ +H2C204 Li 4 ______________ -2 (CF3)2CHOH
In this method it is disadvantageous that LiF remains in the product, the ligand 1,1,1,3,3,3-hexafluoroisopropanol is costly, and the process is complicated due to having two steps.
õ
¨ 4 ¨
In another production method, lithium tetrafluoroborate is reacted with anhydrous oxalic acid and SiCla as auxiliary reagent (EP 1308449):
2 LiBF4 + 2 H2Ox + SiC14 -) Li[F2BOx] + 4 HCI + SiF4 (3) A disadvantage of this synthesis is the formation of the acidic, toxic co-products SiF4 and HCI. In addition, traces of chloride remain in the product. It is known that chloride is corrosive to aluminum, so that a conductive salt which is thus contaminated with chloride corrodes the cathode current collector, generally an aluminum foil, used in Li-ion batteries.
It is also known that in heat aging of equimolar mixtures of LiBF4 and LiBOB
in ethylene carbonate/ethylmethyl carbonate (EC/EMC), LiDFOB forms in a very slow reaction (B.
Lucht, Electrochem. Solid-State Lett. 14(11) A161-A164 (2011)). Thus, when the mixed salt LiDFOB is stored at 100 C, an approximately 80% yield is obtained within weeks. The disadvantages of this method are that the reaction is much too slow for commercial use, and the raw material LiBF4 is costly.
In another method, boron trifluoride, usually in the form of an ether addition product, is reacted with lithium oxalate (S.S. Zhang, Electrochem. Commun. 8 (2006) 1423-1428):
F _ ....---0 \ /
Li2C204 + BF3 = Donor ¨0- Li B= + LiF
/
[ 0---0 F _ (Donor = Et20 or THF) A disadvantage of this method is that the target product LiDFOB is formed in a yield of only 50%, and UBE' forms to the same extent. Namely, the by-product LiF which results according to Equation (4) reacts immediately with boron trifluoride to form LiBF4, so that overall, the following reaction equation applies:
Li2C204 + 2 BF3 4 Li[F2BC204] + LiBF4 (4a) Lastly, LiDFOB may be prepared from lithium tetrafluoroborate and bis(trimethylsilyl)oxalate in acetonitrile solution (C. Schreiner, M.
Amereller, H.
Gores, Chem. Eur. J. 13 (2009) 2270-2272):
- -O¨SiMe3 F\ /O
LiBF4 + I Li B (5) 0 0¨SiMe3 -2 Me3SiF F/ N0---Disadvantages of this method are the high costs, the unavailability of the silyl ester, and occurrence of the by-product trimethylsilyl fluoride.
The object of the invention is to provide a process which, starting from commercially available, easily handled raw materials, forms metal difluorochelatoborates, in particular LiDFOB, in a simple one-step reaction.
The object is achieved by reacting a metal bis(chelato)borate of formula M[BL21 with boron trifluoride and a metal fluoride (ME) and/or a metal salt of the chelate ligand (M2L) in an organic aprotic solvent, where M+ is a monovalent cation selected from the group consisting of lithium, sodium, potassium and ammonium NR4+, where R, identical or different, are selected from the group consisting of H and C1-C8-alkyl (acyclic or cyclic), and L is a chelating agent having two terminal oxygen atoms having the general formula L . (y1¨p P
l y2 m .)/,,c,,,s, _________________________________________ cZ)= ) R1 R, Y3 Y) n 0 where the following apply:
when m = 1 and Y1 and Y2 together with C1 stand for a carbonyl group, n = 0 or 1 and o = 0 or 1, and R1 and R2 are independently H or alkyl containing one to eight carbon atoms, and Y3, Y4 are each independently OR3 (R3 =
C1-C8 alkyl), and when nor o 1, p = 0 or 1, and when n and o = 0, p = 1;
or Yl, Y2, Y3, Y4 are each independently OR3 (R3 = C1¨C8 alkyl), m = 1, n = 0 or 1,0 = 1, and p = 0; or C2 and C3 are members of a 5- or 6-membered aromatic ring or 5- or 6-membered heteroaromatic ring with N, 0, or S as heteroelement, said 5- or 6-membered aromatic ring or 5- or 6- membered heteroaromatic ring being unsubstituted or substituted with at least one radical selected from the group consisting of alkyl, alkoxy, carboxy and nitrite, where R1, R2, Y3 and Y4 are absent when m = 0, or in the case of m = 1, Y1 and Y2 together with C1 stand for a carbonyl group and p is 0 or 1.
The Ci-C8 alkyl group preferably comprises CI-Ca linear alkyls and C3-C8 cycloalkyl.
The reactions may be described by the following general equations:
M2L + M[BL2] + 2 BF3 4 3 M [F2BL] (6) ME + M[BL2] + BF3 2 M [F2BL] (7) For the case of preparation of the particularly preferred conductive salt LiDFOB, lithium bis(oxalato)borate (LiBOB) is reacted with lithium fluoride or lithium oxalate and boron trifluoride:
Li2C204 + LiBOB + 2 BF3 4 3 Li[F2BC204] (8) LiF + LiBOB + BF3 4 2 Li[F2BC204] (9) ¨ 7 ¨
Similarly, the likewise particularly preferred conductive salt lithium difluoromalonatoborate (LiDFMB) is prepared from lithium-bis(malonato)borate and BF3 as well as LiF or lithium malonate (Li2C3H204). Further preferred products are the following: lithium difluorolactatoborate, lithium difluoroglycolatoborate, lithium difluorosalicylatoborate, lithium difluorocatecholatoborate, and the corresponding sodium salts. Aprotic organic solvents, preferably ethers, esters, nitriles, lactones, or carbonates, are used either in pure form or in any given mixture. In addition, hydrocarbons (aromatics or saturated compounds) may be used in mixtures with the above-mentioned functionalized solvents.
The use of solvents which are suitable for use in lithium batteries is very particularly preferred. Such solvents include the following: carboxylic acid esters (dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, propylene carbonate, ethylene carbonate), cyclic ethers such as tetrahydropyran or tetrahydrofuran, polyethers such as 1,2-dimethoxyethane or diethylene glycol dimethyl ether, as well as nitriles such as acetonitrile, adiponitrile, malodinitrile, and glutaronitrile, and lactones such as y-butyrolactone.
The reaction is carried out at temperatures between 0 and 250 C, preferably between 20 and 150 C, particularly preferably between 30 and 130 C.
The sparingly soluble raw materials, i.e., the metal fluorides and/or metal chelate salts, are used in pulverized form, preferably ground. The average particle size is <
100 pm, particularly preferably < 50 pm.
All raw materials, in particular the metal salts and the solvents, are used in anhydrous form; i.e., the water content of the raw materials is < 1000 ppm, preferably <300 ppm.
¨ 8 ¨
In one particularly preferred embodiment, a reaction acceleration catalyst is used. Lewis acids or substances which release or are able to release Lewis acids in the reaction mixture are used as catalyst. Preferred catalysts are compounds of elements Groups 2 through 15 of the periodic table, particularly preferably molecular halides, perfluoroalkyls, perfluoroaryls, and oxo compounds of boron, aluminum, and phosphorus. Examples include the following: aluminum alcoholates (Al(OR)3), boric acid esters (B(OR)3), phosphorus oxides, and phosphorus halides. Very particularly preferred are superacid boron compounds such as B(C6F5)3 (BARF), C6F5B0206F4, and boric acid esters of trivalent oxygen-based chelate ligands such as the following:
r-Ck H3C¨ 0-13 \-0 0 0 0 In addition, very particularly preferred is the catalytic use of LiPF6, which under the above-mentioned reaction conditions is in equilibrium with the strong Lewis acid PF5 (Equation 1). The mentioned catalysts are used in quantities of 20 mol-%
maximum, preferably up to 10 mol-% and particularly preferably up to 5 mol-%, based on the boron trifluoride used.
The process according to the invention is described in general terms below.
The metal salts are placed in the anhydrous solvent. With stirring, boron trifluoride is then either introduced or condensed in the gaseous state, or added in the form of standard solvate complexes such as BF3 x diethyl ether, BF3 x THE, or BF3 x acetonitrile. The use of gaseous BF3 or a solution prepared beforehand with BF3 gas in the desired solvent (for example, a carbonate such as dimethyl carbonate or propylene carbonate) is particularly preferred. The introduction of a solvent, such as diethyl ether, which is uncommon or even detrimental in battery electrolytes, is thus avoided. BF3 is added in a temperature range between 0 C and 150 C, preferably between 10 C and 100 C.
After the BF3 has been added, stirring is performed until the reaction is complete.
The ¨ 9 ¨
progress of the reaction may be conveniently monitored by 11B NMR
measurements, for example.
The process according to the invention may also deviate slightly from the theoretical stoichiometry (Equations 6 through 9). The stoichiometries are preferably selected which result in complete consumption of the raw material BF3, which has a detrimental effect in the battery. For this purpose, the metal salts MF and/or M2L are used in excess. The mentioned metal salts are preferably used in an excess of 0.1 to 100% by weight, particularly preferably in an excess of 1 to 20% by weight.
After the reaction is complete, the reaction solution is clarified by membrane filtration, for example. The reaction solution is then directly usable as such as a battery electrolyte or additive, if no solvents which are detrimental to the battery performance have been used. In the event that detrimental solvents are contained, the synthesized metal difluorochelatoborate according to the invention is obtained in pure form by means of a concentration or crystallization process.
The invention is explained with reference to the following seven examples.
Example 1: Preparation of LiDFOB from LiBOB, lithium oxalate, and BF3 in dimethyl carbonate (DMC) 37.5 g LiBOB and 19.8 g Li2C204 in 229 g anhydrous DMC were placed in a 0.5-L
double shell reactor equipped with a reflux cooler and dropping funnel, and heated to an internal temperature of 70 C. 55.0 g boron trifluoride etherate was then metered in over a period of one hour. The jacket temperature was set so that the reaction mixture was boiling lightly the entire time. After metering was complete, refluxing was continued with occasional withdrawal of samples.
The samples were checked for progress of the reaction by 11B NMR:
Time of sampling I -1.1 ppm* 0 ppm* 3.1 ppm* 7.6 ppm*
L1BF4 BF3 LiDFOB LiBOB
End of metering 41.5 4.7 42.9 10.8 2 h after the reaction 43.0 3.0 45.9 8.2 7.5 h after the reaction 37.8 3.9 47.6 10.7 9 h after the reaction 36.9 2.9 48.4 11.8 11.5 h after the reaction 37.7 2.6 55.3 4.5 18.5 h after the reaction 17.6 2.2 66.7 13.6 26 h after the reaction 9.2 1.9 78.9 8.9 30 h after the reaction 8.8 2.1 81.4 7.7 * Listed values represent the chemical shift of the particular product in the "B NMR
spectrum After a 30-hour reaction time, > 80% of theoretical LiDFOB had formed, and the composition did not change significantly with continued stirring. Thus, a thermodynamic equilibrium mixture was formed. The reaction mixture was filtered, and was used in this form (clear solution) as an electrolyte for lithium batteries.
Example 2: Preparation of LiDFOB from LiBOB, lithium oxalate. and BF3 in dimethyl carbonate (DMC), 5 mol-% LiPF6 catalyst 1.50 g LiBOB and 0.91 g lithium oxalate were dissolved or suspended in 9.16 g DMC in an inerted GC septum glass equipped with a magnetic stirrer, and 0.59 g of a 10%
LiPF6 solution in DMC was added. 2.20 g boron trifluoride etherate was injected into the stirred suspension, which was then heated to 70 C. Samples were withdrawn at specified time intervals and checked for progress of the reaction by11B NMR:
- 1 1 ¨
Time of sampling ¨1.1 ppm* 0 ppm* 3.1 ppm* 7.6 ppm*
LiBF4 BF3 LiDFOB LiBOB
1 h, 70 C 41.5 0.5 46 8 h, 70 C 16 1.1 72 11 12 h, 70 C 14 1.0 79 6 * Listed values represent the chemical shift of the particular product in the spectrum Example 3: Preparation of LiDFOB from LiBOB, lithium oxalate, and BF3 in propylene carbonate (PC), with and without 5 mol- ./0 L1PF6 catalyst 1.50 g LiBOB and 0.79 g lithium oxalate were dissolved or suspended in 9.2 g PC in each of two inerted GC septum glasses equipped with a magnetic stirrer. 0.59 g of a 10% solution of LiPF6 in PC was injected into one of the glasses. 2.20 g boron trifluoride etherate was injected into each of the stirred suspensions, which were then heated to 70 C. Samples were withdrawn at specified time intervals and checked for progress of the reaction by11B NMR:
Reaction time LiBF4 LiDFOB LiBOB
70 C (h) Without With Without With Without With catalyst catalyst catalyst catalyst catalyst catalyst 1 h 32 22 40 62 28 16 2h 31 18 41 71 27 11 9h 28 10 54 83 18 6 Example 4: Preparation of LiDFOB from LiBOB, lithium fluoride and BF3 in propylene carbonate (PC) with 5 mol-`)/0 LiPF6 catalyst 1.50 g LiBOB and 0.23 g ground lithium fluoride were dissolved or suspended in 6.8 g PC in an inerted GC septum glass equipped with a magnetic stirrer, and 0.59 g of a 10% LiPF6 solution in PC was added. 1.10 g boron trifluoride etherate was injected into ¨ 12 ¨
the stirred suspension, which was then heated to 70 C. Samples were withdrawn at specified time intervals and checked for progress of the reaction by11B NMR:
Time of sampling ¨1.1 ppm* 0 ppm* 3.1 ppm* 7.6 ppm*
L1BF4 BF3 LiDFOB LiBOB
1 h, 70 C 19 0.4 68 13 2 h, 70 C 15 0.5 74 11 9 h, 70 C 9 1 86 4 * Listed values represent the chemical shift of the particular product in the spectrum Example 5: Preparation of LiDFOB from LiBOB, lithium fluoride, and BF3 in tetrahydropyran (THP), without catalyst 1.50 g LiBOB and 0.25 g ground lithium fluoride were dissolved or suspended in 8.5 g THP in an inerted GC septum glass equipped with a magnetic stirrer. 1.10 g boron trifluoride etherate was injected into the stirred suspension, which was then heated to 70 C. Samples were withdrawn at specified time intervals and checked for progress of the reaction by11B NMR:
Time of sampling ¨1.1 ppm* 0 ppm* 3.1 ppm* 7.6 ppm*
LiBF4 BF3 LiDFOB LiBOB
15 min, 70 C 28 0 47 25 2 h, 70 C 16 0.5 79 4 * Listed values represent the chemical shift of the particular product in the spectrum Example 6: Preparation of LiDFMB from lithium-bis(malonato)borate (LiBMB), lithium fluoride, and BF3 in propylene carbonate (PC), without catalyst 1.78 g LiBMB and 0.21 g lithium fluoride were suspended in 11 g PC in an inerted GC
septum glass equipped with a magnetic stirrer. 1.14 g boron trifluoride etherate was injected into the stirred suspension, which was then stirred at 100 C. Samples were =
- 13 ¨
withdrawn at specified time intervals and checked for progress of the reaction byliB NMR:
Time of sampling ¨1.2 ppm* 0 ppm* 1.4 ppm*
CF3 F OCH(CF3)2 _ (2) 0 \B/ +H2C204 Li 4 ______________ -2 (CF3)2CHOH
In this method it is disadvantageous that LiF remains in the product, the ligand 1,1,1,3,3,3-hexafluoroisopropanol is costly, and the process is complicated due to having two steps.
õ
¨ 4 ¨
In another production method, lithium tetrafluoroborate is reacted with anhydrous oxalic acid and SiCla as auxiliary reagent (EP 1308449):
2 LiBF4 + 2 H2Ox + SiC14 -) Li[F2BOx] + 4 HCI + SiF4 (3) A disadvantage of this synthesis is the formation of the acidic, toxic co-products SiF4 and HCI. In addition, traces of chloride remain in the product. It is known that chloride is corrosive to aluminum, so that a conductive salt which is thus contaminated with chloride corrodes the cathode current collector, generally an aluminum foil, used in Li-ion batteries.
It is also known that in heat aging of equimolar mixtures of LiBF4 and LiBOB
in ethylene carbonate/ethylmethyl carbonate (EC/EMC), LiDFOB forms in a very slow reaction (B.
Lucht, Electrochem. Solid-State Lett. 14(11) A161-A164 (2011)). Thus, when the mixed salt LiDFOB is stored at 100 C, an approximately 80% yield is obtained within weeks. The disadvantages of this method are that the reaction is much too slow for commercial use, and the raw material LiBF4 is costly.
In another method, boron trifluoride, usually in the form of an ether addition product, is reacted with lithium oxalate (S.S. Zhang, Electrochem. Commun. 8 (2006) 1423-1428):
F _ ....---0 \ /
Li2C204 + BF3 = Donor ¨0- Li B= + LiF
/
[ 0---0 F _ (Donor = Et20 or THF) A disadvantage of this method is that the target product LiDFOB is formed in a yield of only 50%, and UBE' forms to the same extent. Namely, the by-product LiF which results according to Equation (4) reacts immediately with boron trifluoride to form LiBF4, so that overall, the following reaction equation applies:
Li2C204 + 2 BF3 4 Li[F2BC204] + LiBF4 (4a) Lastly, LiDFOB may be prepared from lithium tetrafluoroborate and bis(trimethylsilyl)oxalate in acetonitrile solution (C. Schreiner, M.
Amereller, H.
Gores, Chem. Eur. J. 13 (2009) 2270-2272):
- -O¨SiMe3 F\ /O
LiBF4 + I Li B (5) 0 0¨SiMe3 -2 Me3SiF F/ N0---Disadvantages of this method are the high costs, the unavailability of the silyl ester, and occurrence of the by-product trimethylsilyl fluoride.
The object of the invention is to provide a process which, starting from commercially available, easily handled raw materials, forms metal difluorochelatoborates, in particular LiDFOB, in a simple one-step reaction.
The object is achieved by reacting a metal bis(chelato)borate of formula M[BL21 with boron trifluoride and a metal fluoride (ME) and/or a metal salt of the chelate ligand (M2L) in an organic aprotic solvent, where M+ is a monovalent cation selected from the group consisting of lithium, sodium, potassium and ammonium NR4+, where R, identical or different, are selected from the group consisting of H and C1-C8-alkyl (acyclic or cyclic), and L is a chelating agent having two terminal oxygen atoms having the general formula L . (y1¨p P
l y2 m .)/,,c,,,s, _________________________________________ cZ)= ) R1 R, Y3 Y) n 0 where the following apply:
when m = 1 and Y1 and Y2 together with C1 stand for a carbonyl group, n = 0 or 1 and o = 0 or 1, and R1 and R2 are independently H or alkyl containing one to eight carbon atoms, and Y3, Y4 are each independently OR3 (R3 =
C1-C8 alkyl), and when nor o 1, p = 0 or 1, and when n and o = 0, p = 1;
or Yl, Y2, Y3, Y4 are each independently OR3 (R3 = C1¨C8 alkyl), m = 1, n = 0 or 1,0 = 1, and p = 0; or C2 and C3 are members of a 5- or 6-membered aromatic ring or 5- or 6-membered heteroaromatic ring with N, 0, or S as heteroelement, said 5- or 6-membered aromatic ring or 5- or 6- membered heteroaromatic ring being unsubstituted or substituted with at least one radical selected from the group consisting of alkyl, alkoxy, carboxy and nitrite, where R1, R2, Y3 and Y4 are absent when m = 0, or in the case of m = 1, Y1 and Y2 together with C1 stand for a carbonyl group and p is 0 or 1.
The Ci-C8 alkyl group preferably comprises CI-Ca linear alkyls and C3-C8 cycloalkyl.
The reactions may be described by the following general equations:
M2L + M[BL2] + 2 BF3 4 3 M [F2BL] (6) ME + M[BL2] + BF3 2 M [F2BL] (7) For the case of preparation of the particularly preferred conductive salt LiDFOB, lithium bis(oxalato)borate (LiBOB) is reacted with lithium fluoride or lithium oxalate and boron trifluoride:
Li2C204 + LiBOB + 2 BF3 4 3 Li[F2BC204] (8) LiF + LiBOB + BF3 4 2 Li[F2BC204] (9) ¨ 7 ¨
Similarly, the likewise particularly preferred conductive salt lithium difluoromalonatoborate (LiDFMB) is prepared from lithium-bis(malonato)borate and BF3 as well as LiF or lithium malonate (Li2C3H204). Further preferred products are the following: lithium difluorolactatoborate, lithium difluoroglycolatoborate, lithium difluorosalicylatoborate, lithium difluorocatecholatoborate, and the corresponding sodium salts. Aprotic organic solvents, preferably ethers, esters, nitriles, lactones, or carbonates, are used either in pure form or in any given mixture. In addition, hydrocarbons (aromatics or saturated compounds) may be used in mixtures with the above-mentioned functionalized solvents.
The use of solvents which are suitable for use in lithium batteries is very particularly preferred. Such solvents include the following: carboxylic acid esters (dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, propylene carbonate, ethylene carbonate), cyclic ethers such as tetrahydropyran or tetrahydrofuran, polyethers such as 1,2-dimethoxyethane or diethylene glycol dimethyl ether, as well as nitriles such as acetonitrile, adiponitrile, malodinitrile, and glutaronitrile, and lactones such as y-butyrolactone.
The reaction is carried out at temperatures between 0 and 250 C, preferably between 20 and 150 C, particularly preferably between 30 and 130 C.
The sparingly soluble raw materials, i.e., the metal fluorides and/or metal chelate salts, are used in pulverized form, preferably ground. The average particle size is <
100 pm, particularly preferably < 50 pm.
All raw materials, in particular the metal salts and the solvents, are used in anhydrous form; i.e., the water content of the raw materials is < 1000 ppm, preferably <300 ppm.
¨ 8 ¨
In one particularly preferred embodiment, a reaction acceleration catalyst is used. Lewis acids or substances which release or are able to release Lewis acids in the reaction mixture are used as catalyst. Preferred catalysts are compounds of elements Groups 2 through 15 of the periodic table, particularly preferably molecular halides, perfluoroalkyls, perfluoroaryls, and oxo compounds of boron, aluminum, and phosphorus. Examples include the following: aluminum alcoholates (Al(OR)3), boric acid esters (B(OR)3), phosphorus oxides, and phosphorus halides. Very particularly preferred are superacid boron compounds such as B(C6F5)3 (BARF), C6F5B0206F4, and boric acid esters of trivalent oxygen-based chelate ligands such as the following:
r-Ck H3C¨ 0-13 \-0 0 0 0 In addition, very particularly preferred is the catalytic use of LiPF6, which under the above-mentioned reaction conditions is in equilibrium with the strong Lewis acid PF5 (Equation 1). The mentioned catalysts are used in quantities of 20 mol-%
maximum, preferably up to 10 mol-% and particularly preferably up to 5 mol-%, based on the boron trifluoride used.
The process according to the invention is described in general terms below.
The metal salts are placed in the anhydrous solvent. With stirring, boron trifluoride is then either introduced or condensed in the gaseous state, or added in the form of standard solvate complexes such as BF3 x diethyl ether, BF3 x THE, or BF3 x acetonitrile. The use of gaseous BF3 or a solution prepared beforehand with BF3 gas in the desired solvent (for example, a carbonate such as dimethyl carbonate or propylene carbonate) is particularly preferred. The introduction of a solvent, such as diethyl ether, which is uncommon or even detrimental in battery electrolytes, is thus avoided. BF3 is added in a temperature range between 0 C and 150 C, preferably between 10 C and 100 C.
After the BF3 has been added, stirring is performed until the reaction is complete.
The ¨ 9 ¨
progress of the reaction may be conveniently monitored by 11B NMR
measurements, for example.
The process according to the invention may also deviate slightly from the theoretical stoichiometry (Equations 6 through 9). The stoichiometries are preferably selected which result in complete consumption of the raw material BF3, which has a detrimental effect in the battery. For this purpose, the metal salts MF and/or M2L are used in excess. The mentioned metal salts are preferably used in an excess of 0.1 to 100% by weight, particularly preferably in an excess of 1 to 20% by weight.
After the reaction is complete, the reaction solution is clarified by membrane filtration, for example. The reaction solution is then directly usable as such as a battery electrolyte or additive, if no solvents which are detrimental to the battery performance have been used. In the event that detrimental solvents are contained, the synthesized metal difluorochelatoborate according to the invention is obtained in pure form by means of a concentration or crystallization process.
The invention is explained with reference to the following seven examples.
Example 1: Preparation of LiDFOB from LiBOB, lithium oxalate, and BF3 in dimethyl carbonate (DMC) 37.5 g LiBOB and 19.8 g Li2C204 in 229 g anhydrous DMC were placed in a 0.5-L
double shell reactor equipped with a reflux cooler and dropping funnel, and heated to an internal temperature of 70 C. 55.0 g boron trifluoride etherate was then metered in over a period of one hour. The jacket temperature was set so that the reaction mixture was boiling lightly the entire time. After metering was complete, refluxing was continued with occasional withdrawal of samples.
The samples were checked for progress of the reaction by 11B NMR:
Time of sampling I -1.1 ppm* 0 ppm* 3.1 ppm* 7.6 ppm*
L1BF4 BF3 LiDFOB LiBOB
End of metering 41.5 4.7 42.9 10.8 2 h after the reaction 43.0 3.0 45.9 8.2 7.5 h after the reaction 37.8 3.9 47.6 10.7 9 h after the reaction 36.9 2.9 48.4 11.8 11.5 h after the reaction 37.7 2.6 55.3 4.5 18.5 h after the reaction 17.6 2.2 66.7 13.6 26 h after the reaction 9.2 1.9 78.9 8.9 30 h after the reaction 8.8 2.1 81.4 7.7 * Listed values represent the chemical shift of the particular product in the "B NMR
spectrum After a 30-hour reaction time, > 80% of theoretical LiDFOB had formed, and the composition did not change significantly with continued stirring. Thus, a thermodynamic equilibrium mixture was formed. The reaction mixture was filtered, and was used in this form (clear solution) as an electrolyte for lithium batteries.
Example 2: Preparation of LiDFOB from LiBOB, lithium oxalate. and BF3 in dimethyl carbonate (DMC), 5 mol-% LiPF6 catalyst 1.50 g LiBOB and 0.91 g lithium oxalate were dissolved or suspended in 9.16 g DMC in an inerted GC septum glass equipped with a magnetic stirrer, and 0.59 g of a 10%
LiPF6 solution in DMC was added. 2.20 g boron trifluoride etherate was injected into the stirred suspension, which was then heated to 70 C. Samples were withdrawn at specified time intervals and checked for progress of the reaction by11B NMR:
- 1 1 ¨
Time of sampling ¨1.1 ppm* 0 ppm* 3.1 ppm* 7.6 ppm*
LiBF4 BF3 LiDFOB LiBOB
1 h, 70 C 41.5 0.5 46 8 h, 70 C 16 1.1 72 11 12 h, 70 C 14 1.0 79 6 * Listed values represent the chemical shift of the particular product in the spectrum Example 3: Preparation of LiDFOB from LiBOB, lithium oxalate, and BF3 in propylene carbonate (PC), with and without 5 mol- ./0 L1PF6 catalyst 1.50 g LiBOB and 0.79 g lithium oxalate were dissolved or suspended in 9.2 g PC in each of two inerted GC septum glasses equipped with a magnetic stirrer. 0.59 g of a 10% solution of LiPF6 in PC was injected into one of the glasses. 2.20 g boron trifluoride etherate was injected into each of the stirred suspensions, which were then heated to 70 C. Samples were withdrawn at specified time intervals and checked for progress of the reaction by11B NMR:
Reaction time LiBF4 LiDFOB LiBOB
70 C (h) Without With Without With Without With catalyst catalyst catalyst catalyst catalyst catalyst 1 h 32 22 40 62 28 16 2h 31 18 41 71 27 11 9h 28 10 54 83 18 6 Example 4: Preparation of LiDFOB from LiBOB, lithium fluoride and BF3 in propylene carbonate (PC) with 5 mol-`)/0 LiPF6 catalyst 1.50 g LiBOB and 0.23 g ground lithium fluoride were dissolved or suspended in 6.8 g PC in an inerted GC septum glass equipped with a magnetic stirrer, and 0.59 g of a 10% LiPF6 solution in PC was added. 1.10 g boron trifluoride etherate was injected into ¨ 12 ¨
the stirred suspension, which was then heated to 70 C. Samples were withdrawn at specified time intervals and checked for progress of the reaction by11B NMR:
Time of sampling ¨1.1 ppm* 0 ppm* 3.1 ppm* 7.6 ppm*
L1BF4 BF3 LiDFOB LiBOB
1 h, 70 C 19 0.4 68 13 2 h, 70 C 15 0.5 74 11 9 h, 70 C 9 1 86 4 * Listed values represent the chemical shift of the particular product in the spectrum Example 5: Preparation of LiDFOB from LiBOB, lithium fluoride, and BF3 in tetrahydropyran (THP), without catalyst 1.50 g LiBOB and 0.25 g ground lithium fluoride were dissolved or suspended in 8.5 g THP in an inerted GC septum glass equipped with a magnetic stirrer. 1.10 g boron trifluoride etherate was injected into the stirred suspension, which was then heated to 70 C. Samples were withdrawn at specified time intervals and checked for progress of the reaction by11B NMR:
Time of sampling ¨1.1 ppm* 0 ppm* 3.1 ppm* 7.6 ppm*
LiBF4 BF3 LiDFOB LiBOB
15 min, 70 C 28 0 47 25 2 h, 70 C 16 0.5 79 4 * Listed values represent the chemical shift of the particular product in the spectrum Example 6: Preparation of LiDFMB from lithium-bis(malonato)borate (LiBMB), lithium fluoride, and BF3 in propylene carbonate (PC), without catalyst 1.78 g LiBMB and 0.21 g lithium fluoride were suspended in 11 g PC in an inerted GC
septum glass equipped with a magnetic stirrer. 1.14 g boron trifluoride etherate was injected into the stirred suspension, which was then stirred at 100 C. Samples were =
- 13 ¨
withdrawn at specified time intervals and checked for progress of the reaction byliB NMR:
Time of sampling ¨1.2 ppm* 0 ppm* 1.4 ppm*
3.6 ppm*
LiBF4 BF3 LiDFMB
LiBMB
30 min, 100 C 29 4 54 11 2.5 h, 100 C 29 4 61 5 7 h, 100 C 24 3 70 3 * Listed values represent the chemical shift of the particular product in the spectrum Example 7: Preparation of LiDFMB from lithium-bis(malonato)borate (LiBMB), lithium fluoride, and BF3 in dimethylsulfoxide (DMSO), without catalyst 1.78 g LiBMB and 0.21 g lithium fluoride were dissolved or suspended in 10.5 g DMSO
in an inerted GC septum glass equipped with a magnetic stirrer. 1.14 g boron trifluoride etherate was injected into the stirred suspension, which was then stirred at 100 C. An almost clear reaction solution formed after a short time. Samples were withdrawn at specified time intervals and checked for progress of the reaction by 11B NMR:
Time of sampling ¨1.2 ppm* 0 ppm* 1.4 ppm*
3.6 ppm*
LiBF4 BF3 LiDFMB
LiBMB
30 min, 100 C 19 2 45 34 2.5 h, 100 0 11 0.9 67 20 7 h, 100 C 6 approx. 0 83 11 * Listed values represent the chemical shift of the particular product in the spectrum
LiBF4 BF3 LiDFMB
LiBMB
30 min, 100 C 29 4 54 11 2.5 h, 100 C 29 4 61 5 7 h, 100 C 24 3 70 3 * Listed values represent the chemical shift of the particular product in the spectrum Example 7: Preparation of LiDFMB from lithium-bis(malonato)borate (LiBMB), lithium fluoride, and BF3 in dimethylsulfoxide (DMSO), without catalyst 1.78 g LiBMB and 0.21 g lithium fluoride were dissolved or suspended in 10.5 g DMSO
in an inerted GC septum glass equipped with a magnetic stirrer. 1.14 g boron trifluoride etherate was injected into the stirred suspension, which was then stirred at 100 C. An almost clear reaction solution formed after a short time. Samples were withdrawn at specified time intervals and checked for progress of the reaction by 11B NMR:
Time of sampling ¨1.2 ppm* 0 ppm* 1.4 ppm*
3.6 ppm*
LiBF4 BF3 LiDFMB
LiBMB
30 min, 100 C 19 2 45 34 2.5 h, 100 0 11 0.9 67 20 7 h, 100 C 6 approx. 0 83 11 * Listed values represent the chemical shift of the particular product in the spectrum
Claims (26)
1. Process for preparing metal difluoroborates of the general formula where M+ is a monovalent cation selected from the group consisting of lithium, sodium, potassium, and ammonium of formula NR4+ wherein R, identical or different, is selected from the group consisting of H and C1 to C8-alkyl, and L is a chelating agent, having two terminal oxygen atoms, with the general formula where the following apply:
when m = 1 and Y1 and Y2 together with C1 stand for a carbonyl group, n = 0 or 1 and o = 0 or 1, and R1 and R2 are each independently H or alkyl containing one to eight carbon atoms, and Y3, Y4 are each independently OR3 (R3 = C1¨C8 alkyl), and when n or o .noteq.1, p = 0 or 1, and when n and o = 0, p = 1;
or Y1, Y2, Y3, Y4 are each independently OR3 (R3 = C1¨C8 alkyl), m = 1, n = 0 or 1, o = 1, and p = 0;
or C2 and C3 are members of a 5- or 6-membered aromatic ring or 5- or 6-membered heteroaromatic ring with N, O, or S as heteroelement, said 5- or 6-membered aromatic ring or heteroaromatic ring being unsubstituted or substituted with at least one radical selected from the group consisting of alkyl, alkoxy, carboxy and nitrile, where R1, R2, Y3, and Y4 are absent when m = 0, or in the case of m = 1, Y1 and Y2 together with C1 stand for a carbonyl group, and p is 0 or 1, by reacting a metal bis(chelato)borate of formula M[BL2] where M
and L are as defined above, with boron trifluoride and a metal fluoride MF
where M is as defined above and/or a metal salt of the chelate ligand M2L
where M and L are as defined above, in a solvent which is an organic aprotic solvent.
when m = 1 and Y1 and Y2 together with C1 stand for a carbonyl group, n = 0 or 1 and o = 0 or 1, and R1 and R2 are each independently H or alkyl containing one to eight carbon atoms, and Y3, Y4 are each independently OR3 (R3 = C1¨C8 alkyl), and when n or o .noteq.1, p = 0 or 1, and when n and o = 0, p = 1;
or Y1, Y2, Y3, Y4 are each independently OR3 (R3 = C1¨C8 alkyl), m = 1, n = 0 or 1, o = 1, and p = 0;
or C2 and C3 are members of a 5- or 6-membered aromatic ring or 5- or 6-membered heteroaromatic ring with N, O, or S as heteroelement, said 5- or 6-membered aromatic ring or heteroaromatic ring being unsubstituted or substituted with at least one radical selected from the group consisting of alkyl, alkoxy, carboxy and nitrile, where R1, R2, Y3, and Y4 are absent when m = 0, or in the case of m = 1, Y1 and Y2 together with C1 stand for a carbonyl group, and p is 0 or 1, by reacting a metal bis(chelato)borate of formula M[BL2] where M
and L are as defined above, with boron trifluoride and a metal fluoride MF
where M is as defined above and/or a metal salt of the chelate ligand M2L
where M and L are as defined above, in a solvent which is an organic aprotic solvent.
2. Process according to claim 1, characterized in that M+ = Li+ and L = C2O4 2-(oxalate) or C3H2O4 2- (malonate), and that lithiumdifluorooxalatoborate (LiDFOB) or lithiumdifluoromalonatoborate (LiDFMB) are obtained as products.
3. Process according to claim 1 or 2, characterized in that ethers, esters, nitriles, lactones, or alkyl carbonates, either in pure form or in any given mixture, are used as the solvent.
4. Process according to any one of claims 1 to 3, characterized in that carboxylic acid esters, cyclic ethers, polyethers, nitriles, and lactones are used as the solvent.
5. Process according to claim 4, characterized in that the carboxylic acid esters are selected from the group consisting of dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, propylene carbonate and ethylene carbonate.
6. Process according to claim 4, characterized in that the cyclic ethers are selected from the group consisting of tetrahydropyran and tetrahydrofuran.
7. Process according to claim 4, characterized in that the polyethers are selected from the group consisting of 1,2-dimethoxyethane and diethylene glycol dimethyl ether.
8. Process according to claim 4, characterized in that the nitriles are selected from the group consisting of acetonitrile, adiponitrile, malodinitrile and glutaronitrile.
9. Process according to claim 4, characterized in that the lactone is y-butyrolactone.
10. Process according to any one of claims 1 to 9, characterized in that the reaction is carried out at temperatures of 0 to 250°C.
11. Process according to any one of claims 1 to 9, characterized in that the reaction is carried out at temperatures of 20 to 150°C.
12. Process according to any one of claims 1 to 9, characterized in that the reaction is carried out at temperatures of 30 to 130°C.
13. Process according to any one of claims 1 to 12, characterized in that said metal bis(chelato)borate of formula M[BL2], said boron trifluoride, said metal fluoride MF and/or said metal salt of the chelate ligand M2L are ground raw materials.
14. Process according to claim 13, characterized in that the raw materials have an average particle size < 100 µm.
15. Process according to claim 13 or 14, characterized in that the raw materials have an average particle size < 50 µm.
16. Process according to any one of claims 1 to 15, characterized in that the metal fluoride MF and/or the metal salt of the chelate ligand M2L are used in excess.
17. Process according to any one of claims 1 to 16, characterized in that the metal fluorides MF and/or the metal salt of the chelate ligand M2L are used in an excess of 0.1 to 100% by weight.
18. Process according to any one of claims 1 to 16, characterized in that the metal fluorides MF and/or the metal salt of the chelate ligand M2L are used in an excess of 1 to 20% by weight.
19. Process according to any one of claims 1 to 18, characterized in that a catalyst is further used, and characterized in that the catalyst contains or is composed of a Lewis acid or a substance which is able to release a Lewis acid in the reaction mixture.
20. Process according to claim 19, characterized in that the catalyst is selected from the group consisting of compounds of elements Groups 2 through 15 of the periodic table and mixtures thereof.
21. Process according to claim 19, characterized in that the catalyst is selected from the group consisting of molecular halides, perfluoroalkyls, perfluoroaryls and oxo compounds of elements selected from the group consisting of boron, aluminum and phosphorus, and mixtures thereof.
22. Process according to claim 19, characterized in that the catalyst is selected from the group consisting of aluminum alcoholates (Al(OR)3), boric acid esters (B(OR)3), phosphorus oxides, phosphorus halides, and mixtures thereof.
23. Process according to claim 19, characterized in that LiPF6 is used as the catalyst.
24. Process according to any one of claims 19 to 23, characterized in that the catalyst is used in quantities of 20 mol-% maximum, based on the boron trifluoride used.
25. Process according to any one of claims 19 to 23, characterized in that the catalyst is used in quantities up to 10 mol-%, based on the boron trifluoride used.
26. Process according to any one of claims 19 to 23, characterized in that the catalyst is used in quantities up to 5 mol-%, based on the boron trifluoride used.
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| PCT/EP2012/072603 WO2013072359A1 (en) | 2011-11-14 | 2012-11-14 | Process for preparing metal difluorochelatoborates and use as battery electrolytes or additives in electrochemical cells |
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| CN108475823B (en) * | 2015-12-18 | 2022-07-12 | 巴斯夫欧洲公司 | Non-aqueous electrolyte for lithium ion batteries comprising asymmetric borate salts |
| CN105541890B (en) * | 2016-01-27 | 2017-08-29 | 太原理工大学 | A kind of synthetic method of difluoro oxalate Boratex |
| CN107017434B (en) * | 2016-01-28 | 2019-06-11 | 宁德新能源科技有限公司 | Non-aqueous electrolyte and lithium ion secondary battery |
| US10450329B2 (en) | 2016-02-05 | 2019-10-22 | Gotion Inc. | Preparation of difluoro chelato borate salts |
| CN107305963A (en) * | 2016-04-25 | 2017-10-31 | 上海交通大学 | Electrolyte for lithium-sulfur cell and preparation method thereof |
| CN105870504B (en) * | 2016-05-04 | 2019-11-22 | 宁德新能源科技有限公司 | A kind of electrolytic solution and lithium ion battery |
| US10287302B2 (en) * | 2017-06-12 | 2019-05-14 | Seeo, Inc. | Method for synthesis of lithium fluorinated borate salts |
| CN109134522A (en) * | 2017-06-16 | 2019-01-04 | 中国科学院青岛生物能源与过程研究所 | Double hydroxyl chelating fluoroalkyl borates and its preparation method and application |
| CN108101931B (en) * | 2017-12-19 | 2019-10-29 | 河南师范大学 | A kind of double oxalic acid boric acid ammonium salt [NHR1R2R3][BC4O8] and preparation method thereof |
| CN111138462B (en) * | 2018-11-05 | 2022-10-21 | 江苏国泰超威新材料有限公司 | Preparation method and application of 2-fluoro-malonic acid lithium difluoroborate |
| JP7155898B2 (en) * | 2018-11-08 | 2022-10-19 | 株式会社豊田自動織機 | Electrolyte and secondary battery |
| US11649358B2 (en) | 2019-09-11 | 2023-05-16 | Uchicago Argonne, Llc | Borate salts, polymers and composites |
| CN111592559A (en) * | 2020-05-22 | 2020-08-28 | 兰州理工大学 | A kind of method for one-step synthesis of sodium difluorooxalate borate |
| CN111883827A (en) * | 2020-07-16 | 2020-11-03 | 香河昆仑化学制品有限公司 | Non-aqueous electrolyte of lithium ion battery and lithium ion battery |
| CN113800525A (en) * | 2021-11-03 | 2021-12-17 | 九江天赐高新材料有限公司 | Method for co-producing fluosilicate and hydrochloric acid by using boron salt tail gas |
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| DE10108592C1 (en) | 2001-02-22 | 2002-08-14 | Chemetall Gmbh | Borchelate complexes, processes for their preparation and their use |
| US6849752B2 (en) | 2001-11-05 | 2005-02-01 | Central Glass Company, Ltd. | Process for synthesizing ionic metal complex |
| DE102004011522A1 (en) * | 2004-03-08 | 2005-09-29 | Chemetall Gmbh | Conductive salts for lithium-ion batteries and their production |
| DE102010008331A1 (en) * | 2009-02-18 | 2010-08-19 | Chemetall Gmbh | Galvanic cell with a lithium metal or a lithium metal-containing alloy as the anode material |
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| US9260456B2 (en) | 2016-02-16 |
| US20140288331A1 (en) | 2014-09-25 |
| JP2014533293A (en) | 2014-12-11 |
| CN104185636B (en) | 2016-08-17 |
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