Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C67/00—Preparation of carboxylic acid esters
  • C07C67/10—Preparation of carboxylic acid esters by reacting carboxylic acids or symmetrical anhydrides with ester groups or with a carbon-halogen bond
  • C07C67/11—Preparation of carboxylic acid esters by reacting carboxylic acids or symmetrical anhydrides with ester groups or with a carbon-halogen bond being mineral ester groups
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
  • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
  • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
  • H01M10/0566—Liquid materials
  • H01M10/0567—Liquid materials characterised by the additives
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
  • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
  • H01M10/0566—Liquid materials
  • H01M10/0569—Liquid materials characterised by the solvents
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M2300/00—Electrolytes
  • H01M2300/0017—Non-aqueous electrolytes
  • H01M2300/0025—Organic electrolyte
  • H01M2300/0028—Organic electrolyte characterised by the solvent
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/10—Energy storage using batteries

Definitions

• the disclosure hereof relates to the field of organic synthesis. Specifically, this disclosure provides fluorine-containing carboxylic acid esters and methods of preparation thereof.
• Fluorine-containing carboxylic acid esters have many uses including use as an electrolyte solvent in
• electrochemical cells such as lithium ion batteries.
• Fluorine-containing carboxylic acid esters can be produced using several different methods from various starting materials.
• One such method is the reaction of a metal carboxylate with a fluorinated alkyl halide. This reaction, however, can involve the use of an added
• WO 2009/040367 (Weisenhofer) describes the synthesis of a fluorine-containing carboxylic acid ester using the reaction of a metal carboxylate with a fluorinated alkyl halide, with sodium iodide added as a catalyst or promoter.
• the disadvantage of the described method is that it results in the formation of iodide and/or iodine impurities, which are difficult to remove from the final product.
• fluorine-containing carboxylic acid esters of high purity are desired.
• carboxylic acid esters of desirably high levels of purity, and for methods of making those esters that do not result in the formation of impurities in the final product that are difficult or expensive to remove, such as iodide and/or iodine.
• R 1 is a Ci to Cio alkyl group and M + is selected from the group consisting of lithium, sodium, potassium and cesium ion;
• R 2 is a Ci to Cio alkylene group and X is selected from the group consisting of Br and CI;
• R 1 is a Ci to Cio alkyl group and M + is selected from the group consisting of lithium, sodium, potassium and cesium ion;
• R 2 is a Ci to Cio alkylene group and X is selected from the group consisting of Brand CI ;
• R 1 is a Ci to Cio alkyl group and M + is selected from the group consisting of lithium, sodium, potassium and cesium ion;
• R 2 is a Ci to Cio alkylene group and X is selected from the group consisting of Br and CI;
• R 1 is a Ci to Cio alkyl group and M + is selected from the group consisting of lithium, sodium, potassium and cesium ion;
• R 2 is a Ci to Cio alkylene group
• Rl is a CI to CIO alkyl and M+ is at least one of sodium, potassium, or cesium ion; (b) providing a
• R2 is a CI to CIO alkylene group and X is CI and Br; (c) contacting the salt of the carboxylic acid of (a) with the fluorinated alkyl halide of (b) in a reaction medium comprising a polar, aprotic solvent to form a fluorine-containing carboxylic acid ester, wherein the reaction medium does not contain a deliberately added catalyst or promoter; and (d) optionally, recovering the fluorine-containing carboxylic acid ester from the
• fluorine-containing carboxylic acid esters Disclosed herein are fluorine-containing carboxylic acid esters, and methods for the preparation thereof.
• impurities such as iodide (I ⁇ ) and/or iodine (I 2 ) .
• the fluorine-containing carboxylic acid esters prepared by the methods disclosed herein are particularly useful as electrolyte solvents for electrochemical cells, such as a lithium ion battery, for which a high purity solvent is desired.
• Suitable ester products thus include without limitation
• the carboxylic acid ester prepared by the methods hereof contains a single ester group.
• the salt of the carboxylic acid is represented by the formula:
• the cation may be an alkali metal cation, and alkaline earth metal cation such as calcium or magnesium, an alkyl ammonium cation, or ammonium ion.
• the salt of the carboxylic acid is represented by the formula R 1 COO ⁇ M + , wherein R 1 is a Ci to Cio alkyl group and M + is at least one of sodium, potassium or cesium ion, or an alkyl ammonium ion
• R 11 ) (R 12 ) (R 13 ) (R 14 )N + wherein each of R 11 , R 12 , R 13 and R 14 is independently H or a Ci ⁇ C5 alkyl group provided that at least one of them is not H.
• Preferred are tetraalkyl ammonium ions wherein none of R , R , R and R is H.
• Suitable salts of carboxylic acids include without
• mixtures of these salts can also be used.
• a mixture of potassium acetate and sodium acetate can be used.
• the fluorinated alkyl compound used in the methods disclosed herein is represented by the formula: CHF 2 -R 2 -X, wherein R 2 is a Ci to Cio alkylene group or fluoroalkylene group and X is a leaving group selected from the group consisting of Br, CI, and -OS0 2 R 15 where R 15 is aryl, F, CF 3 , C 4 F 9 , alkyl or OC(0)X where X is CI or F.
• alkylene group refers to a divalent group containing carbon and hydrogen, having only carbon-carbon single bonds, and which may be linear or branched.
• fluoroalkylene refers to an alkylene group wherein one or more hydrogens have been replaced by one or more fluorines. Although R 2 can contain fluorines, the group adjacent to X is CH 2 .
• the fluorinated alkyl compound used in the methods disclosed herein is a fluorinated alkyl halide represented by the formula: CHF 2 -R 2 -X, wherein R 2 is a Ci to Cio alkylene group or fluoroalkylene group and X is CI, Br or I.
• X is CI or Br.
• Examples of useful fluorinated alkyl halides include without
• the fluorinated alkyl halide is CHF 2 -C3 ⁇ 4-Br. In another particular embodiment, the
• fluorinated alkyl halide is CHF 2 -CH 2 -CI.
• the fluorinated alkyl halides may be prepared using liquid phase or gas phase methods known in the art, for example using the methods described by Chen et al . (U.S. Patent Application Publication No .2002/0183569) , Bolmer et al . (U.S. Patent No. 6,063,969), Boyce et al . (U.S. Patent No. 5,910,616), or the method described in the Examples herein.
• R 1 and R 2 can optionally contain fluorination
• Terminal CHF 2 and interior CF 2 groups separated from the reaction site by at least one carbon atom are preferred.
• the salt of the carboxylic acid and the fluorinated alkyl compound e.g., a fluorinated alkyl halide, are contacted in the absence of any substance that
• the salt of the carboxylic acid and the fluorinated alkyl compound are contacted in a reaction medium comprising a solvent.
• Suitable solvents include without limitation, nitriles, dinitriles, such as adiponitrile, esters, including esters containing
• the salt of the carboxylic acid and the fluorinated alkyl halide are contacted in a reaction medium comprising a polar, aprotic solvent to form the fluorine-containing carboxylic acid ester.
• a polar, aprotic solvent refers to a solvent having a high dielectric constant and a high dipole moment, but lacking an acidic hydrogen.
• Suitable polar, aprotic solvents can typically be selected from the substituted acid amides, the organic sulfoxides and the cyclic amides, and mixtures thereof.
• the substituted acid amides can be represented by the general formula:
• R 6 -C (O)-N (R 7 )-R 8 where R 6 is selected from the group consisting of hydrogen and a hydrocarbon radical having between 1 and 8 carbon atoms; R 7 and R 8 are selected from the group consisting of hydrogen and an alkyl radical having between 1 and 3 carbon atoms, provided that R 7 and R 8 are not both
• acid amide contains at least two carbon atoms.
• acid amides include N-methylformamide, N, -dimethylformamide,
• organic sulfoxides can be represented by the general formula:
• R 9 -S (O)-R 10 where R and R can be the same or different and are hydrocarbon radicals having between 1 and 8 carbon atoms.
• suitable sulfoxides include dimethylsulfoxide, diethylsulfoxide, ethylpropylsulfoxide, dioctylsulfoxide, benzylmethylsulfoxide, diphenylsulfoxide,
• solvents can be selected from the group consisting of sulfolane, N-methyl-2-pyrrolidone, N, N-dimethyl-2- imidazolidinone, 1 , 3-dimethyl-3 , 4 , 5 , 6-tetrahydro- 2(1H)- pyrimidinone, and mixtures thereof.
• the weight ratio of the solvent to the combined weights of the salt and alkyl halide reactants can be in the range of about 0.5/1 to about 50/1, or in the range of about 0.5/1 to about 20/1, or in the range of about 1/1 to about 10/1.
• the reaction may occur in a batch or in a continuously fed reactor in which one or both reactants and optionally solvent are fed on a continuous basis.
• Product may accumulate in the reactor or be removed on a continuous basis.
• the temperature of the reaction medium is about 20°C to about 200°C, more particularly about 50°C to about 150°C, and more particularly about 80°C to about 120°C.
• the reaction medium may be agitated during the reaction using conventional means such as a magnetic stirrer, an overhead mixer, and the like.
• the reaction pressure can be
• the methods hereof involve contacting a salt of a carboxylic acid with a fluorinated alkyl halide in a reaction medium that does not contain a deliberately added catalyst such as sodium iodide or potassium iodide.
• reaction medium is substantially free of iodide and/or iodine. Therefore, the reaction medium and the resulting fluorine-containing carboxylic acid ester are
• the reaction medium does not contain any deliberately added catalyst or promoter.
• the reaction in WO 2009/40367 is an example of the use of a substance that does participates in the formation of an intermediate or a reactive substrate from the alkyl halide since I- ion from the Nal compound displaces the Br from the alkyl halide before I itself is subsequently displaced from the alkyl halide by the acetate ion. Nal in that reaction thus is also an example of a deliberately added catalyst or promoter.
• the reaction mixture is free or substantially free of one or more of iodine, iodide, bromide, and/or chloride.
• the reaction mixture is free or substantially free of iodine and iodide.
• substantially free is defined as an amount of less than about 10 5 , less than about 10 4 , less than about 10 3 , less than about 5 xlO 2 , less than about 10 2 , less than 10, or less than 1 ppm.
• the fluorine-containing carboxylic acid ester formed in the reaction may optionally be isolated from the reaction medium and purified using methods known in the art, e.g. distillation methods such as vacuum distillation or spinning band distillation. For best results when used as an electrolyte solvent in a lithium ion battery, as discussed below, it is desirable to purify the
• fluorine-containing carboxylic acid esters to a purity level of at least about 99.9%, more particularly at least about 99.99%.
• the content of any one, any two, any three, any four, any five or all six of the following impurities: iodine, iodide, chloride, bromide, water and/or a fluorinated alcohol (such as 1, 1-difluoroethanol) is less than about 10 5 , less than about 10 4 , less than about 10 , less than about 5 xlO , less than about 10 , less than 10, or less than 1 ppm.
• Methods of purification are disclosed herein and known in the art.
• the fluorine-containing carboxylic acid ester prepared by the methods disclosed herein is admixed with at least one electrolyte salt to form an electrolyte composition.
• electrolyte salts include without limitation
• LiPF 6 lithium hexafluorophosphate
• lithium tris (pentafluoroethyl ) trifluorophosphate LiPF 3 (C 2 F 5 ) 3
• mixtures of lithium fluoride and anion receptors such as B(OC 6 F 5 ) 3 .
• the electrolyte salt is lithium hexafluorophosphate .
• the electrolyte salt can be present in the electrolyte
• composition in an amount of about 0.2 to about 2.0 M, more particularly about 0.3 to about 1.5 M, and more
• the electrolyte composition may also contain at least one co-solvent, which is added to the composition along with the fluorine-containing carboxylic acid ester
• Suitable co-solvents include without limitation various carbonates and sulfones.
• suitable co-solvents include without limitation
• co-solvent is ethylene carbonate .
• the fluorine-containing carboxylic acid ester, prepared by the methods disclosed herein, and the co- solvent may be combined in various ratios to form a solvent mixture as used in the electrolyte composition, depending on the desired properties of the electrolyte composition.
• the fluorine-containing carboxylic acid ester comprises about 10% to about 90% by weight of the solvent mixture.
• the fluorine-containing carboxylic acid ester comprises about 40% to about 90% by weight of the solvent mixture.
• the fluorine-containing carboxylic acid ester comprises about 50% to about 80% by weight of the solvent mixture.
• the fluorine-containing carboxylic acid ester comprises about 10% to about 90% by weight of the solvent mixture.
• the fluorine-containing carboxylic acid ester comprises about 40% to about 90% by weight of the solvent mixture.
• the fluorine-containing carboxylic acid ester comprises about 50% to about 80% by weight of the solvent mixture.
• the fluorine-containing carboxylic acid ester comprises about 50% to about 80% by weight of the solvent mixture.
• fluorine-containing carboxylic acid ester comprises about 60% to about 80% by weight of the solvent mixture. In another embodiment, the fluorine-containing carboxylic acid ester comprises about 65% to about 75% by weight of the solvent mixture. In another embodiment, the
• fluorine-containing carboxylic acid ester comprises about 70% by weight of the solvent mixture.
• the electrolyte composition can be contacted with a cathode and an anode to form an electrochemical cell, such as a lithium ion battery.
• a cathode is the electrode of an electrochemical cell at which reduction occurs.
• the cathode is the positively charged electrode.
• a secondary i.e.
• the cathode is the electrode at which reduction occurs during discharge and oxidation occurs during charging.
• An anode is the electrode of an electrochemical cell at which oxidation occurs.
• the anode is the negatively charged electrode.
• a secondary i.e.
• the anode is the electrode at which oxidation occurs during discharge and reduction occurs during charging.
• the fluorine-containing carboxylic acid esters prepared by the method disclosed herein are particularly useful for use in electrochemical cells, such as lithium ion batteries, wherein high purity solvents are desired, because the fluorine-containing carboxylic acid esters are substantially free of impurities such as iodide and/or iodine.
• An electrochemical cell comprises a housing, an anode and a cathode disposed in the housing and in ionically conductive contact with one another, an electrolyte composition, as described above, providing an ionically conductive pathway between the anode and the cathode, and a porous or microporous separator between the anode and the cathode.
• the housing may be any suitable container to house the electrochemical cell components.
• the anode and the cathode may be comprised of any suitable
• materials include without limitation lithium metal, lithium metal alloys, lithium titanate, aluminum,
• cathode materials include without limitation graphite, aluminum, platinum, palladium, electroactive transition metal oxides comprising lithium or sodium, indium tin oxide, and conducting polymers such as polypyrrole and
• the porous separator serves to prevent short
• the porous separator typically consists of a single-ply or multi-ply sheet of a microporous polymer such as polyethylene, polypropylene, or a combination thereof.
• the pore size of the porous separator is sufficiently large to permit transport of ions, but small enough to prevent contact of the anode and cathode either directly or from particle penetration or dendrites which can from on the anode and cathode .
• the electrochemical cell is a lithium ion battery, which is a type of rechargeable battery in which lithium ions move from the anode to the cathode during discharge, and from the cathode to the anode during charge.
• Suitable cathode materials for a lithium ion battery include without limitation
• electroactive transition metal oxides comprising lithium, such as LiCo0 2 , LiNi0 2 , LiMn 2 0 4 or LiV 3 0 8 .
• lithium composite oxides containing lithium and a transition metal may be utilized as the cathode material.
• Suitable examples include composite oxides with the general formula LiM0 2 where M can be any metallic elements or combination of metallic elements such as cobalt, aluminum, chromium, manganese, nickel, iron, vanadium, magnesium, titanium, zirconium, niobium, molybdenum, copper, zinc, indium, strontium, lanthanum, and cesium.
• the active material can be made of a material with the chemical formula LiMn 2 _ x M x 0 4 , where 0 ⁇ x ⁇ l, or a material with the general formula L1MPO 4 where M can be any metallic element or combination of elements such as cobalt, aluminum, chromium, manganese, nickel, iron, vanadium, magnesium, titanium, zirconium, niobium, molybdenum, copper, zinc, indium, strontium, lanthanum, and cesium.
• the cathode of the battery may include any of the active materials that may be held on an electrically conductive member that includes metal or another
• the cathode in the lithium ion battery hereof comprises a cathode active material
• cathode is a stabilized manganese cathode comprising a lithium-containing
• manganese composite oxide in a cathode comprises oxides of the formula Li x Ni y M z Mn 2 - y - z 0 4 - d , wherein x is 0.03 to 1.0; x changes in accordance with release and uptake of lithium ions and electrons during charge and discharge; y is 0.3 to 0.6; M comprises one or more of Cr, Fe, Co, Li, Al, Ga, Nb, Mo, Ti, Zr, Mg, Zn, V, and Cu; z is 0.01 to 0.18, and d is 0 to 0.3. In one embodiment, in the above formula, y is 0.38 to 0.48, z is 0.03 to 0.12, and d is 0 to 0.1. In one embodiment, in the above formula, M is one or more of Li, Cr, Fe, Co, and Ga .
• Stabilized manganese cathodes may also comprise spinel- layered composites which contain a manganese-containing spinel component and a lithium rich layered structure, as described in U.S. Patent No. 7,303,840.
• the cathode active material can be prepared using methods such as the hydroxide precursor method described by Liu et al (J. Phys . Chem., C 13:15073-15079, 2009). In that method, hydroxide precursors are precipitated from a solution containing the required amounts of manganese, nickel and other desired metal (s) acetates by the addition of KOH.
• the cathode active material can be prepared using a solid phase reaction process or a sol-gel process as described in U.S. Patent No. 5,738,957 (Amine).
• the cathode, in which the cathode active material is contained may be prepared by methods such as mixing an effective amount of the cathode active material (e.g.
• a polymer binder such as polyvinylidene difluoride
• conductive carbon in a suitable solvent, such as N-methylpyrrolidone, to generate a paste, which is then coated onto a current collector such as aluminum foil, and dried to form the cathode.
• the lithium ion battery hereof further contains an anode, which comprises an anode active material that is capable of storing and releasing lithium ions.
• suitable anode active materials include without limitation lithium alloys such as lithium-aluminum alloy, lithium-lead alloy, lithium-silicon alloy, lithium-tin alloy and the like; carbon materials such as graphite and mesocarbon microbeads (MCMB) ; phosphorus-containing materials such as black phosphorus, MnP 4 and C0P 3 ; metal oxides such as SnC> 2 , SnO and T1O 2 ; and lithium titanates such as Li 4 Ti 5 0i 2 and Li i 2 0 4 .
• the anode active material is lithium titanate or graphite.
• An anode can be made by a method similar to that described above for a cathode wherein, for example, a binder such as a vinyl fluoride-based copolymer is
• the lithium ion battery hereof also contains a porous separator between the anode and cathode.
• the porous separator serves to prevent short circuiting between the anode and the cathode.
• the porous separator typically consists of a single-ply or multi-ply sheet of a
• microporous polymer such as polyethylene, polypropylene, polyamide or polyimide, or a combination thereof.
• the pore size of the porous separator is sufficiently large to permit transport of ions to provide ionically conductive contact between the anode and cathode, but small enough to prevent contact of the anode and cathode either directly or from particle penetration or dendrites which can from on the anode and cathode. Examples of porous separators suitable for use herein are disclosed in U.S. Application SN 12/963,927 (filed 09 Dec 2010, U.S. Patent Application Publication No. 2012/0149852), which is by this reference incorporated in its entirety as a part hereof for all purposes .
• the housing of the lithium ion battery hereof may be any suitable container to house the lithium ion battery components described above.
• a container may be fabricated in the shape of small or large cylinder, a prismatic case or a pouch.
• the lithium ion battery hereof may be used for grid storage or as a power source in various electronically powered or assisted devices (an "Electronic Device") such as a transportation device (including a motor vehicle, automobile, truck, bus or airplane) , a computer, a
• telecommunications device a camera, a radio, or a power tool .
• millimole ( s ) means molar concentration
• wt ⁇ 6 means percent by weight
• mm means millimeter ( s )
• ppm means parts per million
• h means hour(s)
• min means
• Potassium acetate (Aldrich, Milwaukee, WI, 99 ⁇ 6 ) was dried at 100 °C under a vacuum of 0.5-1 mm of Hg (66.7-133 Pa) for 4 to 5 h.
• the dried material had a water content of less than 5 ppm, as determined by Karl Fischer
• HCF 2 CH 2 Br (290 g, 2 mol, E.I. du Pont de Nemours and Co., 99 ⁇ 6 ) was placed in the addition funnel and was slowly added to the reaction medium. The addition was mildly exothermic and the temperature of the reaction medium rose to 120-130 °C in 15-20 min after the start of the addition.
• reaction medium was cooled down to room temperature and was agitated overnight. Next morning, heating was resumed for another 8 h.
• reaction flask was replaced by a hose adapter with a
• Teflon® valve and the flask was connected to a mechanical vacuum pump through a cold trap (-78 °C, dry-ice/acetone) .
• the reaction product was transferred into the cold trap at 40-50 °C under a vacuum of 1-2 mm Hg (133 to 266 Pa) .
• the transfer took about 4-5 h and resulted in 220-240 g of crude HCF 2 CH 2 OC (0) CH 3 of about 98-98.5% purity, which was contaminated by a small amount of HCF 2 CH 2 Br (about 0.1- 0.2%), HCF 2 CH 2 OH (0.2-0.8%), sulfolane (about 0.3-0.5%) and water (600-800 ppm) .
• Further purification of the crude product was carried out using spinning band distillation at atmospheric pressure. The fraction having a boiling point between 106.5-106.7 °C was collected and the impurity profile was monitored using GC/MS (capillary column
• HP5MS phenyl-methyl siloxane, Agilentl9091S-433, 30. m, 250 ⁇ , 0.25 ⁇ ; carrier gas - He, flow rate 1 mL/min;
• du Pont de Nemours and Co., 99% was placed in the addition funnel and was slowly added to the reaction medium.
• the addition was mildly exothermic and the temperature rose to 120-130 °C in 15-20 min after the start of the addition.
• the addition of HCF 2 CH 2 Br was kept at a rate which maintained the internal temperature at 125-135 °C .
• the addition took about 2-3 h.
• the reaction medium was agitated at 120-130 °C for an additional 6 h (typically the conversion of bromide at this point was about 90-95%) . Then, the reaction medium was cooled down to room
• reaction product was transferred into the cold trap at 40- 50 °C under a vacuum of 1-2 mm Hg (133 to 266 Pa) .
• the transfer took about 3 h and resulted in 48 g of crude HCF 2 CH 2 OC (0) C 2 H 5 of about 98% purity. Further purification of the crude product was carried out using spinning band distillation at atmospheric pressure.
• the fraction having a boiling point between 120.3-120.6 °C was collected and the impurity profile was monitored using GC/MS (capillary column HP5MS, phenyl-methyl siloxane, Agilent 19091S-433, 30 m, 250 ⁇ , 0.25 ⁇ ; carrier gas - He, flow rate 1 mL/min; temperature program: 40 °C, 4 min, temp, ramp 30 °C/min, 230 °C, 20 min) .
• the crude product (43 g) had a purity of 99.91% and contained about 300 ppm of water.
• the solution was syringe filtered through a 0.2 ⁇ PTFE syringe filter.
• To 15.0 mL of the resulting solution was added 2.28 g of lithium hexafluorophosphate (battery grade, Novolyte) and the mixture was shaken for a few minutes until all the solid was dissolved.
• 2-Difluoroethyl propionate prepared as described above, was purified by spinning band distillation twice to 99.990% purity, as determined by gas chromatography using a mass spectrometric detector.
• the purified 2,2- difluoroethyl propionate was dried over 3A molecular sieves (Sigma-Aldrich, Milwaukee, WI). After drying, the water content was determined to be ⁇ 0.5 ppm using Karl Fischer titration.
• the solution was syringe filtered through a 0.2 ⁇ PTFE syringe filter.
• Nonaqueous Electrolyte Composition Comprising 2 , 2-Difluoroethyl Propionate (DFEP) and
• the hydroxide precipitate was next ground and mixed with lithium carbonate. This step was done in 60 g batches using a Fritsche Pulverisette automated mortar and pestle. For each batch the hydroxide mixture was weighed, then ground alone for 5 minutes in the Pulveresette . Then a stoichiometric amount with small excess of lithium carbonate was added to the system. For 53 g of hydroxide 11.2 g of lithium carbonate was added. Grinding was continued for a total of 60 minutes with stops every 10-15 minutes to scrape the material off of the surfaces of the mortar and pestle with a sharp metal spatula. If humidity caused the material to form clumps, it was sieved through a 40 mesh screen once during grinding, then again
• the ground material was fired in air in a box furnace inside shallow rectangular alumina trays.
• the trays were 158 mm by 69 mm in size, and each held about 60 g of material.
• the firing procedure consisted of ramping from room temperature to 900 °C in 15 hours, holding at 900 °C for 12 hours, then cooling to room temperature in 15 hours .
• PVDF polyvinylidene difluoride
• NMP N- methylpyrrolidone
• Kureha America Inc., New York, NY, KFL#1120 Kureha America Inc., New York, NY, KFL#1120
• anhydrous NMP Sigma -Aldrich, Milwaukee, WI
• the slurry was coated on 25 ym thick aluminum foil using a doctor blade, dried on a hot plate at 100 °C for five to seven minutes, then in a vacuum oven at 100 °C for five to seven minutes.
• the resulting 25-mm wide cathode was placed on a 125 ym thick brass sheet and two 38 mm wide brass shim strips of 87 ym thickness were placed on either side of the cathode to control the gap thickness in the calender.
• the electrode and shims were covered with a second 125 ym thick brass sheet, and the assembly was passed through a calender three times using 100 mm diameter steel rolls heated to 125 °C with a nip force of 154, 205, and 356 kg, respectively.
• the cathode was further dried in a vacuum oven at 90 °C at -25 inches of Hg (-85 kPa) for 15 h.
• the slurry was coated on copper foil using a doctor blade, and dried first on a hot plate at 100 °C for five to seven minutes, then in a vacuum oven at 100 °C for five to seven minutes.
• the resulting electrode was calendered at 125 °C to constant thickness as previously described.
• Circular anodes 15 mm in diameter and cathodes 14 mm in diameter were punched out, placed in a heater in the antechamber of a glove box, further dried under vacuum at 90 °C for 15 h, and brought in to an argon glove box (Vacuum Atmospheres, Hawthorne, CA, Nexus purifier) .
• Nonaqueous electrolyte lithium-ion CR2032 coin cells were prepared for
• electrolyte composition of interest were assembled to form the LTO/Fe-LNMO full cells.
• Full cells containing the anode, cathode, and nonaqueous electrolyte shown in Table 1, were cycled using a commercial battery tester (Series 4000, Maccor, Tulsa, OK) in a temperature-controlled chamber at 55 °C using voltage limits of 1.9 to 3.4 V.
• the constant-current charge and discharge currents for the first two cycles were 12 mA/g of LNMO (about 0.1C rate), and subsequent cycles were carried out at 120 mA/g of LNMO for 29 cycles (about 1C rate) then one cycle at 12 mA/g then repeated until T80 was reached.
• T80 is defined as the number of cycles before the cell's discharge capacity has been reduced to 80% of the initial discharge capacity of the third charge-discharge cycle (first cycle at the 1C rate) .
• 2-Difluoroethyl acetate was prepared by reacting potassium acetate with HCF 2 CH 2 C1 in DMSO.
• HCF 2 CH 2 C1 was prepared using a modification of the procedure described by V. Petrov et al . (Journal of
• thermocouple well thermocouple well, a dry-ice condenser, and an addition funnel under flow of dry nitrogen.
• 2-Difluoroethyl propionate was prepared by reacting sodium propionate with HCF 2 CH 2 CI in DMSO using the

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