MXPA01013467A - Nonaqueous electrolyte lithium secondary batteries. - Google Patents

Abstract

This invention relates to electrolyte solution compositions useful in lithium-ion batteries. These electrolytes feature lower volatility than solutions known in the art while retaining excellent battery performance using graphite based negative electrode active materials.

Description

LITHIUM SECONDARY BATTERIES WITH NON-AQUEOUS ELECTROLYTE FIELD OF THE INVENTION The present invention relates to electrolyte solution compositions and lithium ion batteries that employ these electrolyte solutions. These electrolytes impart lower volatility than the solutions known in the art, while excellent battery development is maintained using graphite-based negative electrode active materials.

BACKGROUND OF THE INVENTION Lithium-ion batteries are now under intensive development around the world, to provide a new generation of secondary or rechargeable batteries. Whatever the specific design method, they all have in common an electrolyte comprising an ionic species and an aprotic fluid, referred to herein as an electrolyte solvent, to provide a physical medium by means of which the ionic species can move. In general, commercial lithium-ion batteries exhibit a high open-circuit voltage, typically 3.6 to 3.8 volts. This means that during charging, a voltage as high as ca. 4.2 volts will be reached normally, with transient voltages located even higher. The secondary lithium batteries are distinguished from the REF. : 134464 Primary metal lithium batteries of the art not only in which the voltages to which the components of the batteries are exposed are generally high, but also in that the components of the batteries of a lithium-ion battery must resist the exposure repeated to these highly oxidizing conditions during numerous charge / discharge cycles. Each component of the lithium ion battery must be able to withstand repeated exposure to the very high electrochemical oxidation and reduction potentials that these voltages represent. Many well known electrolyte solvents suitable for use in other types of batteries simply do not exhibit the stability required for the use of the lithium ion battery. It seems that it is not a generalized scheme in the art beyond the trial and error to select the electrolyte solvents that will exhibit the required stability. In practice, this has prevented the choice of electrolyte solvents used in the art of lithium ion batteries with respect to acyclic and cyclic organic carbonates, primary dimethyl carbonate (DMC), diethyl carbonate (DEC), carbonate ethyl methyl (EMC), propylene carbonate (PC) and ethylene carbonate (EC) and monoesters, such as methyl acetate (MA), ethyl acetate (EA), methyl formate (MF), methyl propionate (MP), Ethyl propionate (EP) and gamma-butyrolactone (GBL) as described in BA Jonson, and R.E. White, "Characterization of Commercially Available Li-ion Batteries", Journal of Powe Sources, 70, 48-54, (1998). More frequently, this electrolyte solvents are used in combinations comprising a cyclic organic carbonate, usually EC or PC an acyclic carbonate, usually DMC, DEC or EMC, as described in U.S. Pat. No. 5,525,443 for Matsushita. These combinations have been found in practice to achieve an excellent combination of the desired properties, such as high ionic conductivity over a wide range of temperature and relatively low volatility, while achieving excellent life time and performance in lithium ion batteries. . The state of the art is also well described in "Organic Electrolytes for Rechargeable Lithium Batteries", by M. Morita, M. Ishikawa, and Y. Matsuda, in Ch. 7 of Li-Ion-Ion Batteries Fundamentals and Performance, Ed. By M Wakihara and O. Yamamoto, Wiley VCH, 1998. The art of patents describing electrolyte solvents for use in lithium ion batteries is bulky. The described electrolyte solvents suitable for use in lithium ion batteries fall into three broad categories: (1) organic carbonates substituted with halogen, such as 2-fluoroethylene carbonate, (2) mixtures of organic carbonates with acyclic or cyclic esters, such as EC + DMC + methyl format, and (3) unsaturated organic carbonates such as vinylene carbonate.

The following are representative of the scope of the art: U.S. 5,192,629 wherein mixtures of ethylene carbonate and dimethyl carbonate are described in ratios of 20/80 to 80/20; U.S. 5,474,862 wherein a combination of cyclic and acyclic organic carbonates is described with CH3CHC (0) OR where R = C to C3 alkyl; U.S. 5,571,635 wherein a combination of EC, PC, and chloroethylene carbonate is described; U.S. 5,578,395, wherein a combination of EC, dimethoxyethane (DME), and butylene carbonate (BC) is described; U.S. 5,626,981, wherein a combination of a cyclic and acyclic organic carbonate, and an unsaturated organic carbonate such as vinylene carbonate (VC); U.S. 5,626,985, wherein a combination of a cyclic and acyclic organic carbonate with 40-80% ether such as DME is disclosed; U.S. 5,633,099 wherein acyclic asymmetric fluorine substituted organic carbonates are described; U.S. 5,659,062, wherein CH3OC (O) OCH2CR3 is described wherein R = Ci to C2 alkyl, alkyl substituted with F, or F; and, U.S. 5,773,165, where EC / PC (50-60%) is described in combination with GBL (10-25%), DMC, and EC / MA. In each case in the art, an acyclic ester or an acyclic organic carbonate is a component required in the composition to achieve the ionic conductivity that is thought to be that required for most applications of the lithium ion battery. However, acyclic esters and acyclic organic carbonates are undesirable and flammable fugitives under some conditions contemplated for the manufacture of batteries. There is a clear need in the art for high conductivity electrolyte compositions that have reduced volatility and flammability. Webber, U.S. Patent No. 5,219,683, discloses the use of solvents of the type Y-0-XOC (0) -R where R is a Ci-Cio alkyl group, X is an acyclic Ci-Cß group and Y is a Ci-Cio alkyl group or a carbonyl group. Its preferred composition includes ethylene glycol diacetate preferably mixed with propylene carbonate and a salt, such as lithium trifluoromethane sulfonate. The use of diacetate solvents in primary lithium batteries, such as the Li / FeS2 battery, is claimed. The maximum voltage at which the solvents are exposed is approximately 2 volts. Horiba et al., JP 86017106, employs diesters of dicarboxylic acids in primary lithium batteries. The exemplified battery had an open circuit voltage of 2.9 V, and was not recharged. Liu et al., WO 99/44246, disclose lithium ion polymer batteries prepared using plasticizers based on dibasic dialkyl adipate esters. According to Liu et al., The adipate ester plasticizer is substantially removed from the battery by an extraction process prior to the addition of the battery electrolyte. However, Liu et al. shows that the residual adipate ester plasticizer up to as much as 20% weight does not affect the operation of the battery. Chang in WO 00/01027 describes the use of malonate diesters that do not contain alpha hydrogens as the electrolyte solvent in lithium ion batteries.

BRIEF DESCRIPTION OF THE INVENTION The present invention provides an electrode composition comprising a lithium electrolyte solution in ionically conductive contact with a graphite-based electrode active material, wherein the solution comprises a lithium electrolyte and a solvent represented by the formula: RxC (0) OR2OC (0) R3 (I) or by the formula R1OC (0) R2C (0) OR3 (II) where R1 and R3 each independently designate an acyclic alkyl radical of 1-4 carbons, C (O) designates a carbonyl radical, and R2 is a 2 or 3 carbon alkenyl radical. The present invention further provides a lithium ion battery comprising a positive electrode, a negative electrode, a separator disposed between the positive and negative electrodes, and an electrolyte solution comprising a solvent, and lithium ions, at least one of the anode, cathode, or separator that is in ionically conductive contact with the electrolyte solution; and the solvent represented by the formula: Rt toi or ^ oc toj R3 (I) o. by the formula: R1OC (0) R2C (0) OR3 (II) wherein R1 and R3 each independently designates an acyclic alkyl radical of 1-4 carbons, C (O) designates a carbonyl radical, and R2 is an alkenyl radical of 2 or 3 carbons.

DETAILED DESCRIPTION OF THE INVENTION For the purposes of the present invention, the term "electrolyte solvent" will refer to any composition of matter that is liquid under the conditions of use in a lithium battery and serves to provide the medium in which one or more ionic species dissolves and through which the ionic species are transported, while the battery is subjected to electric charge or discharge. The term "lithium electrolyte" will refer to any composition of matter that provides the lithium ions for solution in and transport through the electrolyte solvent. The term "electrolyte solution" will refer to the electrolyte solvent having dissolved in this lithium ion as provided by the lithium electrolyte. It is surprisingly found in the present invention that certain esters having two or more ester groups known in the art only as suitable solvents for primary lithium batteries are highly suitable for the considerably more demanding oxidant environment of the rechargeable lithium ion electrochemical cells. Esters having two or more ester groups, characterized by desirably higher boiling points than the monoesters and acyclic organic carbonates previously employed in lithium ion batteries, are now found to be preferred replacements thereof, preferably in combination with cyclic organic carbonates, to meet the need for electrolyte solvents with reduced flammability and volatility, while continuing to impart high ionic conductivity and high oxidative stability in secondary lithium ion batteries. The esters of the present invention are used to replace the monoesters and acyclic organic carbonates of the art, in whole or in part, in the ionically conductive components used in lithium ion batteries. The esters suitable for the practice of the present invention are represented by the formula: ################################################################################################################# acyclic alkyl radical of 1-4 carbons, C (0) designates a carbonyl radical, and R2 denotes a two or three carbon alkenyl radical, Preferably, R1 and R3 are the same, more preferably R1 and R3 are methyl groups or ethyl and n = 2. More preferably, the diester is dimethyl succinate, CH3OC (0) CH2CH2C (0) 0CH3 In one embodiment of the invention, an electrolyte solvent is formed by combining at least one diester suitable for practicing the invention with a cyclic carbonate, preferably propylene carbonate or ethylene carbonate, in a volume ratio of 90:10 to 30:70 In the preferred embodiment, the ethylene carbonate and dimethyl succinate are combined in a volume ratio of 67:33 respectively.

In another embodiment, at least one diester suitable for the practice of the invention is combined with at least one component of a lithium ion battery, the components being a positive electrode, a negative electrode and a separator according to the teachings of the art. as it is practiced with other liquid electrolyte solvents. In the case of positive and negative electrodes, the. The electrolyte solvent is mixed with the active electrode material and any adjuvant thereof, in accordance with practice in the art. In the case of the separator, if the separator is a porous body, the electrolyte solvent is inhibited within the pores. In the case of a semipermeable membrane, the electrolyte solvent is absorbed by the membrane. In the case of an ionomeric membrane, the electrolyte solvent is absorbed by the ionomer. The electrolyte solvent of the invention must be in ionic contact with at least the positive electrode, the negative electrode or the separator so that the electrochemical process is carried out. Usually, the electrolyte solvent will be in ionically conductive contact with all three. In the practice of the invention, the electrolyte solvent must be combined with one or more electrolytes which will provide ions to the electrolyte, thereby making it ionically conductive. Suitable electrolytes include lithium salts of low molecular weight and ionic polymers, known as ionomers. Suitable low molecular weight lithium salts include the organic and inorganic salts, such as LiPF6, LiBF4, LiC104, LiAsF6, LiN (S02CF3) 2, LiN (S02CF2CF3) 2, LiC (S02CF3) 3, among others. The molar concentration of the lithium ions in the electrolyte solution could be from 0.1 to 3.0 M, with a preferred range of 0.5 to 1.5 M. When the ionic species is an ionomer, it may be desirable to still add an amount of the salt of low molecular weight lithium to the electrolyte solvent in concentrations in the range of 0.01 to 1.0 M. The lithium battery of the present invention can be a liquid cell using a porous polyolefin spacer superimposed between the layers of the electrode film, as described in "Performance of the First Lithium-ion Battery and Its Process Technology", by Y. Nishi, Cap. 8 of Li thium-ion Bateries, Fundamen táis and Performance, Ed. By M. Wakihara and O. Yamamoto, Wiley VCH, 1998. In one embodiment, the lithium battery of the present invention is a cell using an electrolyte of polymer as the separator layer and within the layers of the electrode film, thus allowing the lamination and assembly of the thin film prismatic batteries. In one embodiment, the polymer electrolyte could comprise a nonionic polymer, such as described in U.S. Pat. No. 5,456,000, and the electrolyte solvent of the invention. In a further embodiment, the polymer electrolyte could comprise an ionic polymer, such as the perfluorinated sulfonate ionomer described in Doyle et al., WO 98/20573 and the electrolyte solvent of the invention. In the composition of the electrode of the invention, a negative electrode is formed by combining at least one ester suitable for the practice of the invention with an active electrode material based on graphite, and a lithium electrolyte. By "graphite based" is meant an active electrode material which is substantially made of graphite but which could contain such interstitial stimulants and other additives and substituents as are known in the art. Numerous methods are known in the art for combining elements of the composition, and any convenient method can be used. These methods include mixing by stirring, melt mixing or sequential film making and rinsing in or injection of the electrolyte solution. The active graphite-based electrode materials are micro-accounts of mesocarbon, such as MCMB available in Osaka Gas or carbon fibers, such as Melblon® available in Petoca that are capable of reaching >280 mAh / g of reversible capacity for the insertion of lithium. Other suitable carbon-based electrode active materials include graphite flakes, PCG graphite available from Osaka Gas, petroleum coke, hard coal and natural graphite. In one embodiment, the lithium electrolyte could be either a lithium salt, preferably LiPF6, LiBF4, LiC104, LiAsF6, LiN (S02CF3) 2, LiN (S02CF2CF3) 2, LiC (S02CF3) 3, more preferably, LiPF6. In an alternative embodiment, the lithium electrolyte is an ionomer. The preferred ionomer is a polymer comprising monomer units of vinylidene fluoride (VF2) further comprising 2-50 mol% of monomer units having pendant groups comprising the radical represented by the formula: - (OCF2CFR) a0CF2 (CFR ' ) bS02X "(Li +) (Y) c (Z) d wherein R and R 'are independently selected from F, Cl or a perfluoroalkyl group having from 1 to 10 carbon atoms optionally substituted by one or more ether oxygens; a = 0, 1 or 2, b = 0 to 6, X is O, C or N with the condition that c = d = 0 when X is O, c = d = l when X is C and c = l and d = 0 when X is N, with the additional proviso that when X is C, Y and Z are electron extraction groups selected from the group consisting of CN, S02Rf, S02R3, P (0) (0R3) 2, C02R3, P ( 0) R32, C (0) Rf, C (O) R3 and cycloalkenyl groups formed with the same, wherein Rf is a perfluoroalkyl group of 1-10 carbons, optionally substituted with one or more ether oxygens; R3 is a group alq uyl of 1-6 carbons optionally substituted with one or more ether oxygens, or an optionally substituted aryl group; And and Z are the same or different; or, when d = 0, Y could be an electron extraction group represented by the formula -S02R'f wherein R'f is the radical represented by the formula - (Rf "S02N ~ ((Li +) S02) mRf ' '' wherein m = 0 or 1 and Rf "is -CnF2n- and Rf '' 'is -CNF2n + 1 wherein n = l-10, optionally substituted with one or more ether oxygens. Preferably, R is trifluoromethyl, R 'is F, a = 1, b = 1, when X is C, Y and Z are CN or C02R3 where R3 is C2H5, while when X is N, Y is preferably S02Rf, where Rf is CF3 or C2F5. The preferred ionomer of the invention could be synthesized according to the methods shown in copending U.S. Patent Nos. 6,025,092 and WO 99/45048 which are incorporated herein by reference in their respective totals. In a preferred embodiment, the electrode composition will additionally contain a polymeric binder and an electronically conductive additive, such as carbon black such as Super P carbon black (MMM Carbon). In a preferred embodiment, wherein the separator is a PVDF / HFP copolymer membrane, the preferred binder is PVDF / HFP. In an alternative preferred embodiment wherein the spacer is a preferred ionomer of the invention, the preferred binder is the same or a closely related ionomer. A preferred electrode of the invention, which is a negative electrode suitable for use in the lithium ion cell of the invention, is formed by combining a diester with an active electrode material based on graphite, carbon black and the preferred ionomer of the invention in proportions of 62 parts of graphite, 4 parts of carbon black, 10 parts of ionomer and the balance a preferred electrolyte solvent of the invention to form the preferred electrode composition. The composition thus formed is fed to a screw-type plasticizer extruder, wherein the blend is mixed, homogenized and formed into a sheet or film by melt extrusion substantially in accordance with the methods shown in the co-pending United States Patent. No. 6,287,722 which is incorporated herein by reference in the entirety. In a preferred alternative embodiment, an electrode film of the invention is formed of 65 parts of graphite mesocarbon microbeads such as MCMB, 3.25 parts of carbon black and 10 parts of polyvinylidene-hexafluoropropylene fluoride copolymer (PVDF / HFP) , such as Kynar FLEX® 2801 (Elf Atochem) as a polymer binder, and the remainder dibutyl phthalate (Aldrich) as a plasticizer for the polymer binder. One method for forming the preferred electrode film of the invention is to disperse or dissolve the components thereof in acetone or other suitable solvents for PVDF / HFP, heating to ca. 60 ° C to form a mixture followed by application of the mixture as a coating on an appropriate substrate such as Mylar® polyester film (DuPont Company). Any means for coating the substrate, such as molding in solution using the well-known doctor-blade technique, could be employed. The substrate thus coated is preferably dried at a temperature up to ca. 60 ° C under vacuum, and then pressed or otherwise subjected to contact pressure to compress the electrode coating to form a smooth surface. The dibutyl phthalate plasticizer is extracted by immersing the dried coated substrate in a volatile solvent, such as diethyl ether or methanol for at least 15 minutes, followed by drying under moderate vacuum at room temperature for at least one hour. The film is separated from the substrate before or during the extraction step. The film thus dried and extracted may be immersed in an electrolyte solution, preferably a 1.0 M solution of LiPF6, in a solvent comprising a diester of the present invention. It is found in the practice of the invention that the ether / esters as shown by Webber, op. Ci t. , they are oxidatively less stable than the diesters, so that they degrade after smaller charge / discharge cycles and therefore, are less preferred. An example of such ether / esters would be 2-ethoxy ethyl acetate. The lithium ion cell of the present invention comprises a positive electrode, a negative electrode and a separator, at least one of which, preferably all of which, will be in ionically conductive contact with the electrolyte solvent of the invention. The lithium ion cell will also contain current collectors typically composed of metallic foils or meshes or metallized plastics, where the metal is composed of aluminum (for the cathode) and copper (for the anode). One skilled in the art will recognize that under normal operating circumstances, all the components of the cell will be in contact, since it is by virtue of the ionically conductive contact between the components of the cell that the cell operates. The positive electrode of the lithium ion cell of the present invention is preferably a mixture of the preferred diester of the invention and a lithium-containing transition metal oxide which is capable of absorbing and releasing lithium ions at a capacity of >100 mAh / g such as LiCo02, LiNi02, LiNixCoy02 and LiMn20. The lithium ion cell of the invention could be formed by any means as is known in the art. The components of the cell could be combined first in the dry state, with the electrolyte solution added as a final step in the process. Otherwise, the electrolyte solution could be added at any stage in the process. In a preferred method for the formation of the lithium ion cell of the invention, as described in copending U.S. Patent No. 6,287,722, which is incorporated herein by reference to the entire, the electrolyte solvent of the invention is mixing first with an ionomer and such as other ingredients are necessary or preferred in the composition of the component of the particular cell that is formed. The resulting composition is then subjected to a film forming step by melt extrusion using a screw type extruder. The other components of the lithium ion cell of the invention could be formed in a similar manner. The negative electrode is preferably formed by combining graphite powder, carbon black, the ionomer resin and the electrolyte solvent of the invention and extruded into a film or sheet. Similarly, the separator is formed by extruding a mixture of the electrolyte solvent and the preferred ionomer, the mixture is then extruded into a film or sheet. In the most preferred embodiment, the various layers of the different components of the lithium ion cell of the invention are laminated together in a continuous process. It is known in the art that under some circumstances, small amounts of additional solvents could provide improvements in the properties of the battery, such as high and low temperature cycling behavior and ability. Therefore, it may be desirable to combine the preferred mixture of dimethyl succinate and ethylene carbonate with an additional component chosen from cyclic carbonates (other than EC), acyclic carbonates or acyclic esters. The present invention is further illustrated in the following specific embodiments.

EXAMPLES EXAMPLE 1 A button type cell 2032 of non-aqueous electrolyte lithium ion was prepared using the procedures known in the art. Parts of the button-type cell (container, cover, spacer and packing) and flange machine of the button-type cell were purchased from Osen Corp. The positive electrode used in the button-type cell was cast in solution of acetone, dried in air, and circular 12 mm sections were punched using bronze perforators. The positive electrode film had a composition of 65 parts of LiCo02 (FMC Corp.), 10 parts of Kynar FLEX® 2801 (Elf Atochem) and 6.5 parts of Super P of carbon black (MMM Carbon). The remainder of the electrode contained dibutyl phthalate (Aldrich) as a plasticizer which was removed by extraction with diethyl ether for 30 minutes followed by drying under vacuum at 23 ° C for one hour. The anode film was also melted from acetone, dried and punched to the 12 mm diameter shape. The anode was composed of 65 parts of MCMB 2528 (Osaka Gas), 10 parts of Kynar FLEX® 2801 and 3.25 parts of Super P carbon black. The anode was removed and dried using the procedures identical to the cathode. The anode and cathode films were superimposed around an 18 mm diameter sheet of Celgard® 3501 separating film of 26 μm (Celanese Corp.). The electrolyte solution was obtained by dissolving 1.52 grams of LiPF6 in 10 ml of a solution composed of 2 parts by volume of EC (Selectipur, 99 +%, EM Industries) and 1 part by volume of dimethyl succinate (DBE4, 98%, Aldrich). The EC was used as received from EM Industries. The dimethyl succinate was dried on molecular sieves (Type 3A, E.M. Industries) for two days before use and had a water content less than 100 ppm based on Karl Fisher analysis. The two electrode films and the separating film were each rinsed individually in an electrolyte solution composed of 1.0 M LiPF6 in EC: dimethyl succinate 2: 1 for one hour before mounting the button cell inside a handling box with gloves purged with argon from Vacuum Atmospheres. The button-type cell was charged first using 0.5 mA current to a higher cut-off voltage of 4.2 V. The cell was then discharged at 0.5 mA to a discharge cutoff potential of 2.8 V. Capacity was measured in each cycle. The difference between the capacity on the first charge and the capacity on the first subsequent discharge, represented as a capacity ratio (discharge capacity / load capacity), is referred to as the reversible capacity. After five identical charge-discharge cycles, the impedance of the cell was measured at a frequency of 0.01 Hz. The cycle life of the button cell is defined as the first cycle that reaches only 80% of the initial capacity of the cell. the cell. The values of the reversible capacity, impedance and cycle life are shown in Table 1.

EXAMPLE 2 A button cell was made using the procedures identical to those given in Example 1, but the electrolyte solvent was a 2: 1 by volume mixture of ethylene carbonate and dimethyl glutarate (DBE5, 98%, Aldrich) , respectively. DBE5 was dried on molecular sieves for two days before use and had a water content less than 100 ppm based on the Karl Fisher analysis. The button cell was manufactured and tested using the procedures described in Example 1 and the results are given in Table 1.

EXAMPLE 3 A button cell was made using the procedures identical to those given in Example 1, but the electrolyte solvent was a 2: 1 by volume mixture of ethylene carbonate and ethylene glycol diacetate (EGD, 99%, Aldrich ), respectively. EGD was dried on molecular sieves for two days before use and had a water content less than 100 ppm based on the Karl Fisher analysis. The button cell was manufactured and tested using the procedures described in Example 1 and the results are given in Table 1.

EXAMPLE 4 A button-type cell was made using the procedures identical to those given in Example 1, but the electrolyte solvent was a 1: 2 by volume mixture of ethylene carbonate and DBE4, respectively. The button cell was manufactured and tested using the procedures described in Example 1 and the results are given in Table 1.

EXAMPLE 5 A button-type cell was made using the procedures identical to those given in Example 1, but the electrolyte solvent was a 2: 1 by volume mixture of ethylene carbonate and diethyl succinate (DES, 99%, Aldrich) , respectively. DES was dried on molecular sieves for two days before use and had a water content less than 100 ppm based on the Karl Fisher analysis. The button cell was manufactured and tested using the procedures described in Example 1 and the results are given in Table 1.

EXAMPLE 6 A button cell was manufactured using the procedures identical to those given in Example 1, but the electrolyte solvent was a 2: 1: 1 by volume mixture of ethylene carbonate, propylene carbonate and DBE4, respectively. The button cell was manufactured and tested using the procedures described in Example 1 and the results are given in Table 1.

EXAMPLE 7 A button cell was manufactured using the procedures identical to those given in Example 1, but the electrolyte solvent was DBE4 alone. The limiting solubility of LiPF6 is DBE4 alone was approximately 0.5M, which was the concentration used for this experiment. The button cell was manufactured and tested using the procedures described in Example 1 and the results are given in Table 1.

EXAMPLE 8 A button-type cell was made using the procedures identical to those given in Example 1, but the electrolyte solvent was a 1: 2 by volume mixture of propylene carbonate and DBE4, respectively. The button cell was manufactured and tested using the procedures described in Example 1 and the results are given in Table 1.

EXAMPLE 9 A button cell was made using the procedures identical to those given in Example 1, but the electrolyte solvent was a 1: 1: 1 by volume mixture of ethylene carbonate, DBE4 and dimethyl glutarate (DBE5, Aldrich ), respectively. The button cell was manufactured and tested using the procedures described in Example 1 and the results are given in Table 1.

EXAMPLE 10 A button cell was made using the procedures identical to those given in Example 1, but the electrolyte solvent was a 2: 1 by volume mixture of ethylene carbonate and dimethyl 1,4-cyclohexane dicarboxylate (DMCH, 97%, Aldrich), respectively. The DMCH was dried on molecular sieves for two days before use and had a water content less than 100 ppm based on the Karl Fisher analysis. The button cell was manufactured and tested using the procedures described in Example 1 and the results are given in Table 1.

EXAMPLE 11 A button-type cell was made using the procedures identical to those given in Example 1, but the electrolyte solvent was a 2: 1 by volume mixture of ethylene carbonate and 2-ethyoxyethyl acetate (EEA, 99%). +, Aldrich), respectively. The EAA was dried on molecular sieves for two days before use and had a water content less than 100 ppm based on the Karl Fisher analysis. The button cell was manufactured and tested using the procedures described in Example 1 and the results are given in Table 1.

EXAMPLE 12 Preparation of 1,3-diacetoxy-2-acetoxymethyl-2-methyl-propane 1.1, I-Tris (hydroxymethyl) ethane (60 g, 0.5 mol) was treated with acetic anhydride (200 mL, 2.1 mol) and sodium acetate (2.0 g, 0.024 mol). The resulting mixture was heated at 35 ° C for 18 hr and then 135 ° C for 0.5 hr. The cooled reaction mixture was added to 1 liter of crushed ice and neutralized using sodium bicarbonate (pH to ca. The mixture was extracted twice with ether, and the combined ether layer was washed with saturated sodium chloride solution and dried using sodium sulfate / magnesium sulfate. Evaporation and distillation gave 115 g of colorless oil, eg 94 ° C (0.1 mm). H NMR (CDC13): 4.02 (s, CH20), 2.08 (s, CH3C (0)), 1.02 (s, CH3). A button cell was made using the procedures identical to those given in Example 1, but the electrolyte solution was a 2: 1 by volume mixture of ethylene carbonate and 1,3-diacetoxy-2-acetoxymethyl-2-methyl. - propane (TA, prepared as described above), respectively. The button cell was manufactured and tested using the procedures described in Example 1 and the results are given in Table 1.

TABLE 1 Summary of Performance Results on Li-Ion Button Cells.

EXAMPLE 13 A portion of the lithium ionomer was formed by copolymerization of vinylidene fluoride with microfluidized PSEPVE followed by hydrolysis in a 1M solution of Li2C03 in a 50/50 mixture of MeOH and water, and then dried. The reservoir of a MicroFluidizer ™ was charged with a solution of 22 g of ammonium perfluorooctanoate in 260 ml of demineralized water. The pump was started and the fluids were allowed to recirculate to mix the surfactant solution with 50 ml of pure demineralized water kept inside the apparatus. 250 g of perfluorosulfonyl fluoride ethoxy propyl vinyl ether (PSEPVE) was slowly added to the tank and the system allowed to recirculate for 20 min to produce a well dispersed PSEPVE emulsion. The output flow was then directed to a 500 ml volumetric flask. The tank was then pumped, 100 ml of demineralized water was added and pumped through the system to wash the remaining emulsion of PSEPVE completely and bring the level in the volumetric flask to the mark. The emulsion was translucent blue as it came out of the MicroFluidizer ™. The concentration of the emulsion was 0.5 g of PSEPVE / ml. A 4-L horizontal stainless steel stirred polymerization reactor was flushed with nitrogen and conditioned by charging with 2 liters of demineralized water, 5 g of ammonium persulfate, 5 g of ammonium perfluorooctanoate, after stirring at 200 rpm, while that the contents of the container were heated to 100 ° C / 15 min. The vessel was cooled, the contents were discharged until dissipated and the vessel was rinsed 3 times with 2 liters of demineralized water. The reactor was charged with 1.65 liters of demineralized water and 6 g of ammonium perfluorooctanoate. The reactor was sealed, pressurized with nitrogen at 7.02 kg / cm2 (100 psi) and vented (3 cycles). The reactor was evacuated to -0.9845 kg / cm2 (-14 psi) and washed with vinylidene fluoride (VF2) at 0 kg / cm2 (0 psi) (3 cycles), at which time an aqueous preload of 20 was pumped. ml, containing 10 g of emulsified PSEPVE and 0.9 g of perfluoro-octanoate, as prepared in the previous example. Stirring was started at 200 rpm and the reactor temperature was brought to 60 ° C. The reactor was pressurized with VF to 21.07 kg / cm2 (300 psi) at which time 0.9 g of potassium persulfate dissolved in 20 ml of demineralized water was pumped at a rate of 10 ml / min. The polymerization was started at 0.07 hr. VF2 and PSEPVE were fed to the reactor, in a mol ratio of 1: 1, as needed to maintain pressure in the reactor of 21.07 kg / cm2 (300 psi). After 215 g of PSEPVE was fed to the reactor, the PSEPVE feed was discontinued. The polymerization was continued for a total time of 4.72 hr, only VF2 was fed as needed to maintain pressure in the reactor of 21.07 kg / cm2 (300 psi), until a total of 334 g of VF2 had been fed to the reactor. The polymerization was terminated to produce a white milky latex that contained 23% polymer solids. The polymer latex was frozen and thawed. The agglomerated polymer was vigorously washed 4 times in 18.92 liters (5 gal) of hot filtered tap water (50 ° C), then washed once in 18.92 liters (5 gal) of demineralized water (20 ° C). After the final wash, the polymer was a fine white powder. The washed polymer was dried at 100 ° C / 24 hr under partial vacuum sparged with nitrogen to yield 520 g of fine white polymer powder. Thick films 0.0635 cm (0.025 inches) pressed at 200 ° C were translucent white, clean and free of voids or visible color. Analysis:% C = 30.41% weight; % S = 3.12% weight; % H = 1.78% weight (8.4% mole of PSEPVE, equivalent weight = 1146 g / eq); DSC analysis: Tg = -24 ° C (I), Tm = 166 ° C.

The polymer prepared above (100 g) was combined under an inert atmosphere with methanol (500 ml) and lithium carbonate (6.9 g) in a 1-liter 3-necked flask equipped with a mechanical stirrer., addition funnel and distillation head. The suspension was allowed to stir at 25 ° C for 22 h at which time 200 ml of toluene was added and the contents were heated to reflux. Toluene / methanol was distilled from the reaction, pure toluene was added to the flask to collect the lost volume. When the temperature of the distillation head reached 105 ° C, ethylene carbonate (10 g) was added. An additional 300 ml of distillate was collected, at which time the distillate was collected in fractions and analyzed. When the toluene fraction in the distillate exceeded 99.5%, the distillation was stopped and the contents of the reaction were cooled to 25 ° C. The polymer was filtered under an inert atmosphere and dried under vacuum to yield 105.7 g of almost white polymer. The analysis of F19 nmr (DMFd) showed a complete absence of sulfonyl fluoride. The polymer was transferred into a glove box with purged argon from Vacuum Atmospheres in a sealed container and opened inside the glove box. 0.5 grams of the polymer portion were mixed with 1.5 grams of a 2: 1 by volume mixture of ethylene carbonate (EC, Selectipur, EM Industries) and DBE4 (DBE4, Aldrich) in a glass ampoule and heated to 100 ° C. C for several hours until completely mixed. This mixture formed a moist, clear gel of rubber consistency due to cooling to room temperature. The mixture was then melt pressed using a Carver Hydraulic Unit Model # 3912 press with a compression plate temperature of 120 ° C and a 1 kb piston force between two 5 mil thick sheets of Kapton® polyimide film. The resulting film was clear and uniform and 76.2-101.6 micrometers (3-4 mils) thick. Once cooled to room temperature, a 1.0 cm by 1.5 cm membrane sample of this melt-pressed film was cut using a razor and the conductivity was determined according to the four-point probe method of Doyle et al, WO 98 / 20573. The ionic conductivity was equal to 7.04x10"4 S / cm.

EXAMPLE 14 A horizontal autoclave 4-L with a mechanical stirrer was purged with nitrogen and charged with 150 g of PSEPVE pre-emulsified in perfluorooctanoate aqueous ammonium (prepared using 35 g ammonium perfluorooctanoate and 600 mL water in the Microfluidizer ™ of According to the methods described in Example 13, it was then diluted to 1.0 liters with distilled water, and 1500 mL of distilled water.The reactor was evacuated, then pressurized to O psig with vinylidene fluoride (3 times), heated to 60 ° C, pressurized to 21.07 kg / cm2 (300 psig) with vinylidene fluoride and stirred at 200 rpm A solution of potassium persulfate (0.6%, 50 mL) was added over a period of 5 min. of the reactor was maintained at 21.07 kg / cm2 (300 psi) until 220 g had been fed after the addition of the initiator.The stirring was stopped and the reactor was cooled and vented.The resulting milky dispersion was frozen and thawed to coagulate the product that it was filtered through nylon cloth and washed with water repeatedly to remove the surfactant. After air drying, the polymer portion was dried in a vacuum oven purged with nitrogen at 100 ° C for 24 hr to give 350 g of the product. 19F NMR (acetone): +45.2 (s, a = 1.00), -78.0 to -80.0 (m's, a = 7.876), -90.0 (m's, a = 21.343), -108 to -116 (series of m, a = 6.446), -122.0 to -127.5 (m's, combined a = 2.4296), -143.0 (bd s, a = 1.283), consistent with PSEPVE% mol = 9.1%. Within the experimental error, all the liquid comonomer charged to the reactor was counted in the copolymer of the collected product. TGA (10 ° / min, N2): no weight loss up to 375 ° C. DSC (20 ° / min): maximum melting transition width at 159.1 ° C (23.1 J / g); Tg = -23 ° C. A 3-necked flask equipped with 3 liter stirrer upper pallet (support Teflon®), reflux condenser and thermocouple port was charged with 200 g of copolymer VF2 / PSEPVE (183.4 mequivalents of S02F), methanol (1700 ml), and lithium carbonate (13.6 g, 184 mequiv.). The mixture was stirred for 24 hr at room temperature. Toluene (300 mL) was added, and the mixture was heated to reflux to remove the solvent. The methanol / toluene azeotrope was collected while additional toluene was added to maintain the volume in the reactor without change. The distillation was continued until the polymer had precipitated and the distillate temperature had reached ca. 108 ° C. Ethylene carbonate (15.8 mL, 18.8 g of distillate, stored on screens) was added, and the distillation was continued until the distillate was free of methanol. The suspension was cooled to room temperature and filtered using a dry nitrogen-purged pressure funnel. The residual toluene was removed under nitrogen and the product was transferred in a dry atmosphere to provide 221.7 g of a white powder, which flows freely. 19F NMR (acetone-d6) characterized: -76 to -82 (signals bd, a = 7.00), -91.2 (s major), -91.65, -93.4 and -95.06 (s minor, combined a = 18.418), -108 a -112 (bd), singles bd to -113.5 and -115.8, bd ma -117.2 (combined a = 5.328), -123 (center of bd m) and -127 (center of bd m, combined a = 2.128), -145 (center of bd m, a = 1.212). The integration was consistent with 9.5% mole of Li-PSEPVE. 1 H NMR (acetone-de) was consistent with one molecule of ethylene carbonate per lithium ion bonded to polymer.

A negative electrode composition was formed in the following manner. Using manual mixing in a 225 ml glass container inside a glove box under a dry nitrogen atmosphere, 5.1 grams of a vinylidene fluoride (VF2) copolymer with 9.5 mol% of perfluoro-2- (2- fluorosulfonyl ethoxide) propyl vinyl ether in the Li + ionomer form was combined with 34.8 grams of graphite MCMB 6-28 from Osaka Gas Chemicals Co, 2.4 grams of Super P carbon black from MMM Coal, 17.7 grams of a 4: 1 by volume mixture of ethylene carbonate and propylene carbonate from EM Industries. The composition of the negative electrode thus formed was formed fused in a CSI-Max extruder, model 194, enclosed in a glove box purged with dry nitrogen. The extrusion conditions were as follows: Rotor temperature: 130 ° C Head temperature: 130 ° C Space between the rotor and the head: 0.25 cm Rotor speed: 192 rpm. The molten material was extruded through a circular mold with a diameter of 0.32 cm, and collected in a sealed glass vessel under dry nitrogen. A sample of the composition of the negative electrode thus extruded was melt pressed to form a negative electrode film with a thickness of 0.015 cm using a Pasadena hydraulic press with a compression plate temperature of 110 ° C and a piston force of 20 klbs. The electronic conductivity of this film was found to be 0.98 S / cm using the method of Example 14. A composition of the positive electrode was formed in the following manner. Using manual mixing in a 225 ml glass vessel inside a glove box under an atmosphere of dry nitrogen, 4.8 grams of the Li ionomer used in the negative electrode composition was combined with 34.8 grams of LiCo02 from EM Industries , 3.0 grams of Super P carbon black from MMM Coal, 1.2 grams of carbon black Ensaco 350 from MMM Coal and 16.2 grams of a 4: 1 by volume blend of ethylene carbonate and propylene carbonate from EM Industries. The composition of the positive electrode thus formed was cast in a CSI-Max extruder, model 194, enclosed in a glove box purged with dry nitrogen at the same conditions used to process the negative electrode material. A sample of the extruded material was melt pressed to form a 0.013 cm thick film using a Pasadena hydraulic press with a compression plate temperature of 110 ° C and a piston force of 20,000 lbs. The electronic conductivity of this film was found to be 0.134 S / cm. Samples of the film of both of these electrodes having a diameter of 12 mm and thicknesses of approximately 228.6 micrometers (9 mils) (for the cathode) and 101.6 micrometers (4 mils) (for the anode) were drilled using a drilling rig. stainless steel and were used for mounting in a button cell as described above. To form a membrane separator, the lithium ionomer used in the negative and positive electrode compositions was transferred in a glove box with nitrogen purge from Vacuum Atmospheres in a sealed container and opened inside the glove box. 0.5 grams of the polymer portion were mixed with 1.0 grams of EC, 0.25 grams of PC and 0.050 grams of LiPF6 (EM Industries) in a glass ampoule and heated at 100 ° C for several hours until thoroughly mixed. This mixture formed a wet gel, sprayed due to cooling to room temperature. The mixture was then melt pressed using a Carver Hydraulic Unit Model # 3912 press at 115 ° C and 2 klbs pressure between two sheets of 127 micrometer (5 mil) thickness of Kapton® polyimide film. The resulting film was clear and uniform and of thickness of 76.2 micrometers (3 mils). A circular sample of 18 mm diameter was drilled from this film to be used as a separator. The electrode and separator films thus manufactured were immersed in a solution of LiPF6 1.0 M in EC / DBE4 2: 1 as described in Example 1. The films were allowed to rinse in this electrolyte solution for two hours, then removed and They were dried firmly before use. The electrodes and separator film were mounted in a button-sized cell of size 2032 that was fabricated using methods known in the art. The button cell was tested using the procedures described in Example 1. The capacity of the button cell on the first charge was 4.69 mAh, while the capacity returned on the first download was 3.87 mAh, giving a reversible fraction of 82.5%. The impedance of the button type cell at a frequency of 0.01 Hz was equal to 35 Ohm-cm2. When discharged at a high discharge rate equivalent to speed 1C (total capacity returned in one hour), the button cell reached 88.3% capacity at the lowest discharge speeds. The cycle life of the button cell to the point where the capacity decreased to less than 80% of its initial capacity was 146 cycles. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (33)

1. CLAIMS Having described the invention as above, the content of the following claims is claimed as property: 1. An electrode composition comprising a lithium electrolyte solution in ionically conductive contact with a graphite-based electrode active material, characterized in that the solution comprises a lithium electrolyte and a solvent represented by the formula: R1C (0) OR2OC (0) ) R3 (I) or by the formula R1OC (0) R2C (0) OR3 (II) where R1 and R3 each independently designates an acyclic alkyl radical of 1-4 carbons, C (0) designates a carbonyl radical, and R2 is a 2 or 3 carbon alkenyl radical. 2. The composition of the electrode according to claim 1, characterized in that R1 and R3 are methyl or ethyl groups. 3. The composition of the electrode according to claim 1, characterized in that the solvent is dimethyl succinate represented by the formula: CH3OC (0) CH2CH2C (0) OCH34. The composition of the electrode according to claim 1, characterized in that it also comprises a cyclic carbonate. 5. The composition of the electrode according to claim 4, characterized in that the cyclic carbonate is ethylene carbonate. 6. The composition of the electrode according to claim 3, characterized in that it further comprises ethylene carbonate, wherein the volume ratio of ethylene carbonate to dimethyl succinate is ca. 2 parts of ethylene carbonate to 1 part of dimethyl succinate. 7. The composition of the electrode according to claim 1, characterized in that the graphite-based electrode active material is microcarbon mesocarbon graphite or graphite fibers. 8. The composition of the electrode according to claim 1, characterized in that the lithium electrolyte comprises an organic or inorganic lithium salt. 9. The composition of the electrode according to claim 8, characterized in that the lithium salt is selected from the group consisting of LiPF6, LiBF, LiC104, LIAsF6, LiN (S02CF3) 2, LiN (S02CF2CF3) 2, LiC (S02CF3) 3. The composition of the electrode according to claim 1, characterized in that the lithium electrolyte comprises a fluorinated lithium ionomer. 11. The composition of the electrode according to claim 10, characterized in that the fluorinated lithium ionomer is a polymer comprising monomer units of vinylidene fluoride (VF2) further comprising 2-50 mol% of monomer units having pendant groups, comprising the radical represented by the formula: - (OCF2CFR) a0CF2 (CFR ') bS02X "(Li +) (Y) c (Z) d wherein R and R' are independently selected from F, Cl or a perfluoroalkyl group having 1 at 10 carbon atoms optionally substituted by one or more ether oxygens, a = 0, 1 or 2, b = 0 to 6, X is O, C or N with the proviso that c = d = 0 when X is O , c = d = l when X is C and c = lyd = 0 when X is N, with the additional proviso that when X is C, Y and Z are electron extraction groups selected from the group consisting of CN, S02Rf, S02R3, P (0) (OR3) 2, C02R3, P (0) R32, C (0) Rf, C (0) R3 and cycloalkenyl groups formed therewith, wherein Rf is a perfluoroalkyl group ilo of 1-10 carbons, optionally substituted with one or more ether oxygens; R3 is an alkyl group of 1-6 carbons optionally substituted with one or more ether oxygens, or an optionally substituted aryl group; And and Z are the same or different; or, when d = 0, Y could be an electron extraction group represented by the formula -S02R 'f wherein R'f is the radical represented by the formula - (Rf "S02N ~ ((Li +) S02) mRf' '' where m = 0 or 1 and Rf "is -CnF2n- and Rf" 'is -CnF2n +? where n = l-10, optionally substituted with one or more ether oxygens 12. The composition of the compliance electrode with claim 11, characterized in that R is trifluoromethyl, R 'is F, a = l, b = l, when X is C, Y and Z are CN or C02R3 where R3 is C2H5; and, when X is N, Y is preferably S02Rf, where Rf is CF3 or C2F5. 13. The composition of the electrode according to claim 11, characterized in that Y = 0. 14. The composition of the electrode according to claim 11, characterized in that Y = N. 15. The composition of the electrode according to claim 11, characterized in that Y = C. 16. The composition of the electrode according to claim 1, characterized in that the lithium electrolyte comprises a mixture of a fluorinated lithium ionomer and a lithium salt. 17. The composition of the electrode according to claim 1, characterized in that it also comprises a fluorinated polymeric binder. 18. A lithium ion battery, comprising a positive electrode, a negative electrode, a separator disposed between the positive and negative electrode, characterized in that at least one of the positive electrode, negative electrode or separator comprises a fluorinated lithium ionomer, and a electrolyte solution comprising a solvent and lithium ions, at least one anode, cathode or separator is in ionically conductive contact with the electrolyte solution; and the solvent is represented by the formula: R1C (0) 0R20C (0) R3 (I) or by the formula R10C (0) R2C (0) 0R3 (II) wherein Ri and R3 each independently designate an acyclic alkyl radical of 1-4 carbons, C (0) designates a carbonyl radical, and R2 is a 2 or 3 carbon alkenyl radical. 19. The lithium ion battery according to claim 18, characterized in that Rx and R3 are methyl or ethyl groups. 20. The lithium ion battery according to claim 18, characterized in that the solvent is dimethyl succinate represented by the formula: CH30C (O) CH2CH2C (O) 0CH3. 21. The lithium ion battery according to claim 18, characterized in that it also comprises a cyclic carbonate. 22. The lithium ion battery according to claim 21, characterized in that the cyclic carbonate is ethylene carbonate. 23. The lithium ion battery according to claim 20, characterized in that it further comprises ethylene carbonate wherein the volume ratio of ethylene carbonate to dimethyl succinate is ca. 2 parts of ethylene carbonate to 1 part of dimethyl succinate. 24. The lithium ion battery according to claim 19, characterized in that the electrolyte solution further comprises a lithium salt selected from the group consisting of LiPF6, LiBF4, LiC104, LiAsF6, LiN (S02CF3) 2, LiN (S02CF2CF3) 2 and LiC (S02CF3) 3. 25. The lithium ion battery according to claim 18, characterized in that the fluorinated lithium ionomer is a polymer comprising monomer units of vinylidene fluoride (VF2) further comprising 2-50 mol% of monomer units having pendant groups comprising the radical represented by the formula: - (0CF2CFR) a0CF2 (CFR ') bS02X ~ (Li +) (Y) c (Z) d wherein R and R' are independently selected from F, Cl or a perfluoroalkyl group having from 1 to 10 carbon atoms optionally substituted by one or more ether oxygens; a = 0, 1 or 2; b = 0 to 6; X is 0, C or N with the proviso that c = d = 0 when X is O, c = d = l when X is C and c = l and d = 0 when X is N; with the additional proviso that when X is C, Y and Z are electron extraction groups selected from the group consisting of CN, S02Rf, S02R3, P (0) (0R3) 2, C02R3, P (0) R32, C (0) Rf, C (0) R3 and cycloalkenyl groups formed therewith, wherein Rf is a perfluoroalkyl group of 1-10 carbons, optionally substituted with one or more ether oxygens; R3 is an alkyl group of 1-6 carbons optionally substituted with one or more ether oxygens, or an optionally substituted aryl group; And and Z are the same or different; or, when d = 0, Y could be an electron extraction group represented by the formula -S02R 'f wherein R' is the radical represented by the formula - (Rf "S02N ~ ((Li +) S02) mRf ' '' where m = 0 or 1 and Rf "is -CnF2n- and Rf" 'is -CnF2n +? where n = l-10, optionally substituted with one or more ether oxygens 26. The lithium ion battery of according to claim 25, characterized in that R is trifluoromethyl, R 'is F, a = 1, b = 1, when X is C, Y and Z are CN or C02R3 where R3 is C2H5, and, when X is N, Y is preferably S02Rf where Rf is CF3 or C2F5 27. The lithium ion battery according to claim 25, characterized in that Y = 0. 28. The lithium ion battery according to claim 25, characterized in that Y = No. 29. The lithium ion battery according to claim 25, characterized in that Y = C 30. The lithium ion battery according to claim 18, characterized in that the solution of the The electrolyte comprises a mixture of a fluorinated lithium ionomer and a lithium salt containing fluorine. 31. The lithium ion battery according to claim 18, characterized in that the separator is the ionomer according to claim 25. 32. The lithium ion battery according to claim 18, characterized in that the negative electrode is manufactured from the electrode composition according to claim 1. 33. The lithium ion battery according to claim 18, characterized in that the negative electrode is made of the electrode composition according to claim 6.