Fluorinated carbonates comprising two oxygen bearing functional groups

Abstract

Fluorinated carbonates comprising two oxygen bearing functional groups, methods for the preparation thereof, and their use as solvent or solvent additive for lithium ion batteries and supercapacitors are disclosed.

Claims

1. A method for the manufacture of a compound of general formula (I),
R.sup.1CFYOC(O)O[(CX.sup.1X.sup.2).sub.mO].sub.nR.sup.2 wherein R.sup.1 is hydrogen, alkyl, alkylene, alkylyne, aryl, fluorosubstituted alkyl, or fluorosubstituted aryl ; Y is hydrogen, fluorine, or alkyl; R.sup.2 is hydrogen, alkyl, alkylene, alkylyne, aryl, fluorosubstituted alkyl, fluorosubstituted aryl, or C(O)OR.sup.2, wherein R.sup.2 is hydrogen, alkyl, aryl, fluorosubstituted alkyl, fluorosubstituted aryl; X.sup.1 and X.sup.2 are independently hydrogen, fluorine, or alkyl; and m and n are independently 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10; the method comprising a step of reacting a compound of general formula (II),
R.sup.1CFYOC(O)F (II) wherein R.sup.1 and Y have the meaning is given above; with an compound of general formula (III),
HO[(CX.sup.1X.sup.2).sub.mO].sub.nOH (III) wherein n, m, X.sup.1, and X.sup.2 have the meanings as given above.

2. A solvent additive or solvent for lithium ion batteries, lithium air batteries, lithium sulphur batteries, supercapacitors or hybrid supercapacitors comprising a compound of general formula (I),
R.sup.1CFYOC(O)O[(CX.sup.1X.sup.2).sub.mO].sub.nR.sup.2 (I) wherein R.sup.1 is hydrogen, alkyl, alkylene, alkylyne, aryl, fluorosubstituted alkyl, or fluorosubstituted aryl; Y is hydrogen, fluorine, or alkyl; R.sup.2 is hydrogen, alkyl, alkylene, alkylyne, aryl, fluorosubstituted alkyl, fluorosubstituted aryl, or C(O)OR.sup.2, wherein R.sup.2 is hydrogen, alkyl, aryl, fluorosubstituted alkyl, fluorosubstituted aryl; X.sup.1 and X.sup.2 are independently hydrogen, fluorine, or alkyl; and m and n are independently 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10.

3. A solvent composition for lithium ion batteries, lithium air batteries, lithium sulfur batteries, supercapacitors or hybrid supercapacitors, comprising at least one solvent useful for lithium ion batteries or supercapacitors and at least one compound of general formula (I),
R.sup.1CFYOC(O)O[(CX.sup.1X.sup.2).sub.mO].sub.nR.sup.2 (I) wherein R.sup.1 is hydrogen, alkyl, alkylene, alkylyne, aryl, fluorosubstituted alkyl, or fluorosubstituted aryl; Y is hydrogen, fluorine, or alkyl; R.sup.2 is hydrogen, alkyl, alkylene, alkylyne, aryl, fluorosubstituted alkyl, fluorosubstituted aryl, or C(O)OR.sup.2, wherein R.sup.2 is hydrogen, alkyl, aryl, fluorosubstituted alkyl, fluorosubstituted aryl; X.sup.1 and X.sup.2 are independently hydrogen, fluorine, or alkyl; and m and n are independently 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10.

4. An electrolyte composition for lithium ion batteries, lithium air batteries, lithium sulfur batteries, supercapacitors or hybrid supercapacitors, comprising at least one solvent useful for lithium ion batteries or supercapacitors, at least one electrolyte salt, and at least one compound of general formula (I),
R.sup.1CFYOC(O)O[(CX.sup.1X.sup.2).sub.mO].sub.nR.sup.2 (I) wherein R.sup.1 is hydrogen, alkyl, alkylene, alkylyne, aryl, fluorosubstituted alkyl, or fluorosubstituted aryl; Y is hydrogen, fluorine, or alkyl; R.sup.2 is hydrogen, alkyl, alkylene, alkylyne, aryl, fluorosubstituted alkyl, fluorosubstituted aryl, or C(O)OR.sup.2, wherein R.sup.2 is hydrogen, alkyl, aryl, fluorosubstituted alkyl, fluorosubstituted aryl; X.sup.1 and X.sup.2 are independently hydrogen, fluorine, or alkyl; and m and n are independently 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10.

5. A lithium ion battery, a lithium air battery, a lithium sulfur battery, a supercapacitor or a hybrid supercapacitor containing at least one compound of general formula (I),
R.sup.1CFYOC(O)O[(CX.sup.1X.sup.2).sub.mO].sub.nR.sup.2 (I) wherein R.sup.1 is hydrogen, alkyl, alkylene, alkylyne, aryl, fluorosubstituted alkyl, or fluorosubstituted aryl; Y is hydrogen, fluorine, or alkyl; R.sup.2 is hydrogen, alkyl, alkylene, alkylyne, aryl, fluorosubstituted alkyl, fluorosubstituted aryl, or C(O)OR.sup.2, wherein R.sup.2 is hydrogen, alkyl, aryl, fluorosubstituted alkyl, fluorosubstituted aryl; X.sup.1 and X.sup.2 are independently hydrogen, fluorine, or alkyl; and m and n are independently 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10.

Description

EXAMPLES

Example 1

Synthesis of ethane-1,2-diyl-bis(1-fluoroethyl) dicarbonate

(1) A 2.5 l PFA-reactor equipped with a temperated double mantle, a reflux condenser and a mechanical stirrer was charged with 1315 g 1-fluoroethyl fluoroformate. After chilling the material to 3 C., a mixture of 267 g pyridine and 288 g ethylene glycol was slowly added over a period of 2.5 hours. The reaction temperature was kept below 55 C. After cooling down to room temperature, the mixture was washed three times with citric acid solution (30% in deionized water, 200 g, 100 g, 100 g). After drying over molecular sieve (120 g) for 3 days followed by filtration, the product was obtained as a colourless liquid in a yield of 1031 g with a purity >82% (GC assay). The product can optionally be purified further by distillation giving a purity >99.9% (GC assay).

Example 2

1-fluoroethyl 2-methoxyethyl carbonate

(2) A 2.5 1 PFA-reactor equipped with a temperated double mantle, a reflux condenser and a mechanical stirrer was charged with 1315 g 1-fluoroethyl fluoroformate. After chilling the material to 3 C., a mixture of 288 g pyridine and 800 g 2-methoxyethanol was slowly added over a period of 3 hours. The reaction temperature was kept below 45 C. After cooling down to room temperature, the mixture was washed three times with citric acid solution (30% in deionized water, 210 g, 130 g, 160 g). After drying over molecular sieve (140 g) for 3 days followed by filtration, the product was obtained as a colourless liquid in a yield of 1323 g (84%) with a purity >89% (GC assay). The product can optionally be purified further by distillation giving a purity >99.9% (GC assay).

Example 3

Linear Sweep Voltammetry (LSV)

(3) Tests were performed in a beaker-type cell comprising three electrodes as follows for measurement of the oxidation potential: a) Li metal as reference electrode b) LiCoO.sub.2 as working electrode c) Li metal as counter electrode

(4) A standard electrolyte (1.0 M LiPF.sub.6 in a 1:2 vol/vol % mixture of ethylene carbonate and dimethylcarbonate) was used. The respective inventive compound to be tested was added to this standard electrolyte at a concentration of 1 wt %.

(5) Tests were performed using an electrochemical analyzer in a voltage range from 3.0 to 7.0 V with a scan rate of 0.1 mVs.sup.1.

(6) FIG. 1 shows the results of the LSV testes.

(7) Curve (1): standard electrolyte

(8) Curve (2): standard electrolyte with 1 wt % ethane-1,2-diyl-bis(1-fluoroethyl) dicarbonate

(9) During the LSV test with the electrolyte comprising ethane-1,2-diyl-bis(1-fluoroethyl) dicarbonate, decomposition of the electrolyte was suppressed as compared to the standard STD electrolyte.

Example 4

Cyclic Voltammetry (CV)

(10) Tests were performed in a beaker-type cell comprising three electrodes as follows : d) Li metal as reference electrode e) Artificial graphite (SCMG-AR) as working electrode f) Li metal as counter electrode

(11) A standard electrolyte (1.0 M LiPF.sub.6 in a 1:2 vol/vol % mixture of ethylene carbonate and dimethylcarbonate) was used. The respective inventive compound to be tested was added to this standard electrolyte at a concentration of 1 wt %.

(12) Tests were performed for 3 cycles using an electrochemical analyzer in a voltage range from 3.0 to 0.0 V with a scan rate of 1.0 mVs.sup.1.

(13) FIG. 2 shows the results (3 time cycles) of the CV test.

(14) Curve (1): standard electrolyte with 1 wt % ethane-1,2-diyl-bis(1-fluoroethyl) dicarbonate

(15) During the first cycle of the CV test, SEI formation (reduction) on the surface of the anode starting at 0.9V was shown. The electrolyte decomposition was therefore prevented in the second and third cycle.

Example 5

Performance TestingMono Full Cell

(16) Test system: Mono full cell consisting of: [LiNi.sub.1/3Co.sub.1/3Mn.sub.1/3O.sub.2 (Ecopro): Super-P (conductive carbon black obtainable from MMM Carbon, Belgium): PVdF (Solef 5130 from Solvay Specialty Polymers) binder=92:4:4 (wt. %)] as positive electrode and [SCMG-AR (artificial graphite obtainable from Showa Denko): Super-P (conductive carbon black obtainable from MMM Carbon, Belgium): PVdF (Solef 5130 from Solvay Specialty Polymers) binder=90:4:6 (wt. %)] as negative electrode. Polyethylene was used as separator. A standard electrolyte composition [(1.0M LiPF.sub.6/ethylene carbonate+dimethyl carbonate (1:2 (v/v)] was used to which the fluorinated additives according to the invention were added under dry room atmosphere.

(17) The preparation of the mono full cells consisted of the following steps in that order: (1) mixing, (2) coating & drying, (3) pressing, (4) slitting, (5) tap welding, (6) pouch cutting, (7) assembly (stacking),(8) mono cell 2-side sealing, (9) electrolyte filling, and (10) vacuum sealing.

(18) For the Cycle Performance, 200 cycles were performed in the range of 3.0V4.4V under C-rate of 1.0.

(19) FIG. 3 shows the unexpected advantageous effect of ethan-1,2-diyl-bis(1-fluoroethyl dicarbonate) in a concentration of 1 wt % (x-axis: cycle number, y-axis: discharge capacity [mAh/g]): initial discharge capacity was 152.2 (mAh/g) and after 200 discharge cycles, capacity was 144.3 (mAh/g). In a comparative example, use of the standard electrolyte composition resulted in an initial discharge capacity of 147.2 (mAh/g), and after 200 cycles, discharge capacity of 143.2 (mAh/g).