Classifications

• • 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
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D233/00—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings
  • C07D233/54—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings having two double bonds between ring members or between ring members and non-ring members
  • C07D233/66—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings having two double bonds between ring members or between ring members and non-ring members with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
  • C07D233/90—Carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D233/00—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings
  • C07D233/54—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings having two double bonds between ring members or between ring members and non-ring members
  • C07D233/66—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings having two double bonds between ring members or between ring members and non-ring members with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
  • C07D233/91—Nitro radicals
  • C07D233/92—Nitro radicals attached in position 4 or 5
  • C07D233/93—Nitro radicals attached in position 4 or 5 with hydrocarbon radicals, substituted by halogen atoms, attached to other ring members
• • 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
  • H01M10/0568—Liquid materials characterised by the solutes
• • 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
• • 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
  • H01M2300/0037—Mixture of solvents
  • H01M2300/004—Three solvents
• • 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 present application refers to the field of batteries, more particularly to the field of electrolyte compositions comprising lithium ions.
• a lithium-ion battery comprises at least one negative electrode (anode), a positive electrode (cathode), a separator and an electrolyte.
• the electrolyte generally consists of a lithium salt dissolved in a solvent which is generally a mixture of organic carbonates, in order to have a good compromise between the viscosity and the dielectric constant. Additives can then be added to improve the stability of the electrolyte salts.
• LiPF6 lithium hexafluorophosphate
• HF hydrofluoric acid
• Other salts have thus been developed, such as LiTFSI (lithium bis (trifluoromethanesulfonyl) imide) and LiFSI (lithium bis (fluorosulfonyl) imide). These salts have little or no decomposition spontaneous and are more stable to hydrolysis than LiPF6. Nevertheless, LiTFSI has the disadvantage of being corrosive for current collectors, particularly aluminum ones.
• the present application relates to an electrolyte composition
• an electrolyte composition comprising lithium hexafluorophosphate, lithium 4,5-dicyano-2- (trifluoromethyl) imidazolate, at least one solvent, and at least one electrolytic additive, said composition comprising:
• a total concentration of lithium hexafluorophosphate and lithium 4,5-dicyano-2- (trifluoromethyl) imidazolate of less than or equal to 1 mol / L relative to the total volume of the composition
• a concentration of lithium 4,5-dicyano-2- (trifluoromethyl) imidazolate of less than or equal to 0.3 mol / L relative to the total volume of the composition.
• the content of lithium 4,5-dicyano-2- (trifluoromethyl) imidazolate is less than or equal to 0.2 mol / L, in particular less than or equal to 0.1 mol / L, preferably less than or equal to 0.08 mol / l, preferably less than or equal to 0.05 mol / l, relative to the total volume of the composition.
• the solvent of the composition is chosen from the group consisting of ethers, carbonic acid esters, cyclic carbonate esters, aliphatic carboxylic acid esters, aromatic carboxylic acid esters, phosphoric acid esters, esters of sulfites, nitriles, amides, alcohols, sulfoxides, sulfolane, nitromethane, 1,3-dimethyl-2-imidazolidinone, 1,3-dimethyl-3,4,5,6-tetrahydro- 2 (1, H) -pyrimidinone, 3-methyl-2-oxazolidinone, and mixtures thereof.
• the solvent is selected from the group consisting of dimethyl carbonate, ethyl and methyl carbonate, diethyl carbonate, diphenyl carbonate, methyl and phenyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, methyl formate, methyl acetate, methyl propionate, ethyl acetate, butyl acetate, and mixtures thereof .
• the solvent may also be selected from ethylene carbonate, diethyl carbonate, and mixtures thereof.
• the electrolyte additive is selected from the group consisting of fluoroethylene carbonate, vinylene carbonate, 4-vinyl-1,3-dioxolan-2-one, allyl carbonate and ethyl acetate.
• the content of electrolytic additive is between 0.1% and 9%, preferably between 0.5% and 4% by weight relative to the combined total mass of solvent (s) and additive.
• the concentration of lithium hexafluorophosphate in the electrolyte composition is greater than or equal to 0.80 mol / L and less than 1 mol / L, preferably between 0.80 and less than 1 mol / L, in particular between 0.90 and 0.99 mol / L, and for example between 0.95 mol / L and 0.99 mol / L.
• the concentration of lithium hexafluorophosphate is about 0.95 mol / L
• the concentration of lithium 4,5-dicyano-2- (trifluoromethyl) imidazolate is about 0.05 mol / L, in relation to the total volume of the composition.
• the present application also relates to the use of a composition as defined herein, in a Li-ion battery, particularly in a temperature range. greater than or equal to 25 ° C, preferably between 25 ° C and 65 ° C, preferably between 40 ° C and 60 ° C.
• the use is in mobile devices, for example mobile phones, cameras, tablets or laptops, in electric vehicles, or in the storage of renewable energy.
• Another embodiment comprises the use of a composition as defined in the present application for improving the life of a Li-ion battery; and / or improving the cycling stability of a Li-ion battery; and / or the reduction of the irreversible capacity of a Li-ion battery; in particular in a temperature range greater than or equal to 25 ° C, preferably between 25 ° C and 65 ° C, preferably between 40 ° C and 60 ° C.
• Another aspect of the present application relates to an electrochemical cell comprising a negative electrode, a positive electrode, and an electrolyte composition as defined herein, interposed between the negative electrode and the positive electrode.
• the negative electrode of the electrochemical cell comprises graphite, carbon fibers, carbon black, lithium, or a mixture thereof, the negative electrode preferably comprising graphite.
• the electrochemical cell as described here can have a capacity retention greater than or equal to 80% after at least 500 charge / discharge cycles with respect to the first cycle, for a load between a voltage Tinf of between 2, 0 and 3.0 volts with respect to Li7Li °, and a voltage Tsup between 3.8 and 4.2 volts with respect to Li7Li °, at a temperature equal to 25 ° C, and at a charging and discharging speed of C.
• the voltage Tinf is equal to 2.8 volts and the voltage T S u P is equal to 4.2 volts
• the electrochemical cell has a capacity retention greater than or equal to 80% after at least 500 charge / discharge cycles relative to the first cycle, for a load between a voltage Tinf of between 2.0 and 3, 0 volts with respect to Li7Li °, and a voltage Tsup between 3.8 and 4.2 volts with respect to Li7Li °, at a temperature equal to 25 ° C, and at a charging and discharging speed of C, the charge being optionally followed by the application of a constant voltage of 4V for 30 minutes, the positive electrode preferably comprising LiFePO 4 .
• the voltage Tinf is equal to 2 volts and the voltage Tsup is equal to 4 volts.
• the charge is followed by the application of a constant voltage of 4V for 30 minutes. According to another embodiment, the charge is not followed by the application of a constant voltage and the capacity retention greater than or equal to 80% after at least 800 charge / discharge cycles with respect to the first cycle.
• the present application also relates to a battery comprising at least one electrochemical cell as described in the present application.
• Another aspect relates to the use of lithium 4,5-dicyano-2- (trifluoromethyl) imidazolate in an electrolyte composition comprising lithium hexafluorophosphate and at least one electrolytic additive, for:
• the composition being such that: the total concentration of lithium 4,5-dicyano-2- (trifluoromethyl) imidazolate and lithium hexafluorophosphate is less than or equal to 1 mol / L relative to the total volume of the composition; and
• the concentration of lithium 4,5-dicyano-2- (trifluoromethyl) imidazolate is less than or equal to 0.3 mol / L, preferentially less than or equal to 0.05 mol / L, relative to the total volume of the composition .
• Figure 1 demonstrates the variation in discharge capacity as a function of the number of cycles performed at 45 ° C as described in Example 1.
• Figure 2 demonstrates the variation in discharge capacity as a function of the number of cycles performed at 60 °. C as described in Example 2.
• Figure 3 demonstrates the variation in discharge capacity as a function of the number of cycles performed at 25 ° C as described in Example 3.
• Figure 4 demonstrates the variation in discharge capacity as a function of the number of cycles performed at 40 ° C as described in Example 3.
• Figure 5 demonstrates the variation in discharge capacity versus the number of cycles performed at 60 ° C as described in Example 3.
• the present application describes electrolyte compositions comprising a concentration and a specific proportion of two lithium salts, a solvent (which may be a mixture of solvents) and an electrolytic additive. More specifically, the electrolyte composition comprises lithium hexafluorophosphate (LiPF6), lithium 4,5-dicyano-2- (trifluoromethyl) imidazolate (LiTDI), at least one solvent, and at least one electrolytic additive.
• LiPF6 lithium hexafluorophosphate
• LiTDI lithium 4,5-dicyano-2- (trifluoromethyl) imidazolate
• the electrolyte composition as described here comprises: a total concentration of lithium hexafluorophosphate and lithium 4,5-dicyano-2- (trifluoromethyl) imidazolate less than or equal to 1 mol / L relative to the total volume of the composition (that is to say, [LiPF 6 ] + [LiTDI] ⁇ 1 mol / L); and
• a concentration of lithium 4,5-dicyano-2- (trifluoromethyl) imidazolate less than or equal to 0.3 mol / L relative to the total volume of the composition (that is, 0 ⁇ [LiTDI] ⁇ 0.3 mol / L).
• the content of lithium 4,5-dicyano-2- (trifluoromethyl) imidazolate is less than or equal to 0.25 mol / L, or less than or equal to 0.2 mol / L, in particular less than or equal to 0.15 mol / L, or less than or equal to 0.1 mol / L, preferably less than or equal to 0.08 mol / L, preferentially less than or equal to 0.05 mol / L, relative to the total volume of the composition.
• the concentration of lithium hexafluorophosphate in the electrolyte composition may be greater than or equal to 0.80 mol / L and less than 1 mol / L, preferably between 0.80 and less than 1 mol / L, in particular between 0.90 and 0.99 mol / L, and for example between 0.95 mol / L and 0.99 mol / L, relative to the total volume of the composition.
• concentrations of lithium hexafluorophosphate and lithium 4,5-dicyano-2- (trifluoromethyl) imidazolate in the electrolyte composition include:
• the electrolyte composition as described in the present application comprises 0.95 mol / L of LiPF6 and 0.05 mol / L of LiTDI, relative to the total volume of the composition.
• the solvent is non-aqueous (organic).
• the solvent of the composition may be selected from the group consisting of ethers, carbonic acid esters, cyclic carbonate esters, aliphatic carboxylic acid esters, aromatic carboxylic acid esters, phosphoric acid, sulfite esters, nitriles, amides, alcohols, sulfoxides, sulfolane, nitromethane, 1,3-dimethyl-2-imidazolidinone, 1,3-dimethyl-3,4 , 5,6-tetrahydro-2 (1, H) -pyrimidinone, 3-methyl-2-oxazolidinone, or a mixture thereof.
• ethers such as, for example, dimethoxyethane (DME), methyl ethers of oligoethylene glycols of 2 to 5 oxyethylene units, dioxolane, dioxane, dibutyl ether, tetrahydrofuran, and their mixtures.
• DME dimethoxyethane
• methyl ethers of oligoethylene glycols of 2 to 5 oxyethylene units dioxolane, dioxane, dibutyl ether, tetrahydrofuran, and their mixtures.
• nitriles there may be mentioned for example acetonitrile, pyruvonitrile, propionitrile, methoxypropionitrile, dimethylaminopropionitrile, butyronitrile, isobutyronitrile, valeronitrile, pivalonitrile, isovaleronitrile, glutaronitrile, methoxyglutaronitrile, 2 methylglutaronitrile, 3-methylglutaronitrile, adiponitrile, malononitrile, and mixtures thereof.
• solvents also include those selected from the group consisting of dimethyl carbonate, ethyl and methyl carbonate, diethyl carbonate, diphenyl carbonate, methyl and phenyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, methyl formate, methyl acetate, methyl propionate, ethyl acetate, butyl acetate, and their mixtures.
• the solvent may also be selected from ethylene carbonate (EC-CAS No. 96-49-1), diethyl carbonate (DEC-CAS No. 105-58-8), and mixtures thereof.
• the solvent is an ethylene carbonate mixture: diethyl carbonate in a ratio between 1: 99 and 99: 1, preferably between 10: 90 and 90: 10, preferably between 40: 60 and 60: 40.
• electrolyte additive examples include fluoroethylene carbonate (FEC), vinylene carbonate, 4-vinyl-1,3-dioxolan-2-one, allyl carbonate and ethyl acetate, vinyl acetate , divinyl adipate, acrylonitrile, 2-vinylpyridine, maleic anhydride, methyl cinnamate, phosphonates, vinyl-containing silane compounds, 2-cyanofuran and mixtures thereof, the electrolyte additive being preferably fluoroethylene carbonate (FEC).
• the content of electrolytic additive may be between 0.1% and 9%, preferably between 0.5% and 4% by weight relative to the combined total mass "solvent (s) + additive".
• the content of electrolyte additive in the electrolyte composition is less than or equal to 2% by weight relative to the combined total mass "solvent (s) + additive".
• the present electrolyte composition is chosen from one of the following compositions (the LiPF 6 and LiTDI concentrations being expressed with respect to the total volume of the composition and the content of additive with respect to the total mass combined "solvent (s) + additive"): i. 0.99 mol / L of LiPFe and 0.01 mol / L of LiTDI, FEC as electrolytic additive (in particular at a content of less than or equal to 2% by mass), and mixture of EC / DEC as solvent;
• the electrolyte composition may be prepared by dissolving, preferably with stirring, salts in appropriate proportions of solvent (s) including the electrolyte additive.
• the electrolyte composition can be prepared by dissolving, preferably stirring, the salts and the electrolyte additive in appropriate proportions of the solvent (s).
• an electrolyte composition of the present application in a Li-ion battery is also envisaged, in particular in a temperature range of greater than or equal to 25 ° C., preferably of between 25 ° C. and 65 ° C. preferably between 40 ° C and 60 ° C.
• the use is in mobile devices, for example mobile phones, cameras, tablets or laptops, in electric vehicles, or for the storage of renewable energy.
• the present application therefore also relates to an electrochemical cell comprising a negative electrode, a positive electrode, and an electrolyte composition as defined herein, interposed between the negative electrode and the positive electrode.
• the electrochemical cell may also include a separator, in which the electrolyte composition of the present application is impregnated.
• the present application also contemplates a battery comprising at least one electrochemical cell defined in this application.
• the battery comprises several of these electrochemical cells, said cells can be assembled in series and / or in parallel.
• negative electrode the electrode which acts as anode, when the battery delivers current (that is to say when it is in the process of discharge) and which makes cathode office when the battery is charging process.
• the negative electrode typically comprises an electrochemically active material, optionally an electronically conductive material, and optionally a binder.
• electrochemically active material means a material capable of reversibly inserting ions, without irreversibly damaging their structure.
• electronically conductive material is meant a material capable of driving electrons.
• the negative electrode of the battery may comprise, as an electrochemically active material of graphite, carbon fibers, carbon black, or a mixture thereof, the negative electrode preferably comprising graphite.
• the negative electrode may also comprise lithium, it may then consist of a metal lithium film or an alloy comprising lithium.
• An example of a negative electrode comprises a bright lithium film prepared by rolling between rolls of a lithium strip.
• the term "positive electrode” means the electrode which acts as cathode, when the battery delivers current (that is to say when it is in the process of discharge) and which serves anode when the battery is charging.
• the positive electrode typically comprises an electrochemically active material, optionally an electronically conductive material, and optionally a binder.
• the positive electrode material may also include, in addition to the electrochemically active material, an electronically conductive material such as a carbon source, including, for example, carbon black, Ketjen ® carbon, Shawinigan carbon, graphite, graphene , carbon nanotubes, carbon fibers (such as gas-phase carbon fibers (VGCF)), non-powdery carbon obtained by carbonization of an organic precursor, or a combination of two or more thereof .
• an electronically conductive material such as a carbon source, including, for example, carbon black, Ketjen ® carbon, Shawinigan carbon, graphite, graphene , carbon nanotubes, carbon fibers (such as gas-phase carbon fibers (VGCF)), non-powdery carbon obtained by carbonization of an organic precursor, or a combination of two or more thereof .
• Other additives may also be present in the material of the positive electrode, such as lithium salts or inorganic particles of ceramic or glass type, or other compatible active materials (for example, sulfur).
• the material of the positive electrode may also comprise a binder.
• binders include linear, branched and / or crosslinked polymeric polyether binders (e.g., polymers based on polyethylene oxide (PEO), or poly (propylene oxide) (PPO) or a mixture of both (or an EO / PO co-polymer), and optionally comprising crosslinkable units), water-soluble binders (such as SBR (styrene-butadiene rubber), NBR (acrylonitrile-butadiene rubber) ), HNBR (hydrogenated NBR), CHR (epichlorohydrin rubber), ACM (acrylate rubber)), or fluoropolymer-type binders (such as PVDF (polyvinylidene fluoride), PTFE (polytetrafluoroethylene), and combinations thereof ).
• Some binders, such as those soluble in water, may also include an additive such as CMC (carboxymethylcellulose).
• the electrochemical cell comprises a negative electrode comprising graphite, a positive electrode comprising LiFePO 4 (LFP) and a mixture of carbon black with carbon fibers and / or carbon nanotubes, and a electrolyte composition as defined herein, interposed between the negative electrode and the positive electrode, the composition preferably being chosen from one of the following compositions (the LiPF 6 and LiTDI concentrations being expressed with respect to the total volume the composition and the additive content in relation to the combined total mass "solvent (s) + additive”): i. 0.99 mol / L of LiPFe and 0.01 mol / L of LiTDI, FEC as electrolytic additive (in particular at a content of less than or equal to 2% by mass), and mixture of EC / DEC as solvent;
• the composition preferably being chosen from one of the following compositions (the LiPF 6 and LiTDI concentrations being expressed with respect to the total volume the composition and the additive content in relation to the combined total mass "solvent (s) + additive"): i. 0.99
• the electrochemical cell as described herein may have a capacity retention greater than or equal to 80% after at least 500 charge / discharge cycles with respect to the first cycle, for a load between a voltage Tinf between 2.0. and 3.0 volts with respect to Li + / Li °, and a voltage T S u P between 3.8 and 4.2 volts with respect to Li + / Li °, at a temperature equal to 45 ° C, and at a charging and discharging rate of C.
• the electrochemical cell as described here can have a capacity retention greater than or equal to 80% after at least 60 charge / discharge cycles relative to the first cycle, for a load between a voltage Tinf between 2.0 and 3.0 volts with respect to Li7Li °, and a voltage Tsup between 3.8 and 4.2 volts with respect to Li7Li °, at a temperature equal to 60 ° C, and at a charging and discharging speed of C / 4, the load being optionally followed by the application of a constant voltage of 4.2V for 1 h.
• the voltage Tinf is equal to 2.8 volts and the voltage Tsup is equal to 4.2 volts
• the charge is followed by the application of a constant voltage as described.
• the electrochemical cell according to the present technology has a capacity retention greater than or equal to 80% after at least 500 cycles charge / discharge with respect to the first cycle, for a load between a voltage Tinf between 2.0 and 3.0 volts with respect to Li + / Li °, and a voltage Tsup of between 3.8 and 4.2 volts with respect to Li + / Li °, at a temperature equal to 25 ° C, and at a charging and discharging rate of C, the charge being optionally followed by the application of a constant voltage of 4V for 30 minutes, the positive electrode preferably comprising LiFePO 4 .
• the voltage Tinf can be equal to 2 volts and the voltage Tsup is equal to 4 volts.
• the charge is followed by the application of a constant voltage as described.
• the electrochemical cell according to the present technology may also have a capacity retention greater than or equal to 80% after at least 200 charge / discharge cycles with respect to the first cycle, for a load between a voltage Tinf between 2.0 and 3, 0 volts with respect to Li7Li °, and a voltage Tsup between 3.8 and 4.2 volts with respect to Li7Li °, at a temperature equal to 40 ° C, and at a charging and discharging rate of C, the charge being optionally followed by the application of a constant voltage of 4V for 30 minutes, the positive electrode preferably comprising LiFePO 4 .
• the voltage Tinf is equal to 2 volts and the voltage Tsup is equal to 4 volts.
• the charge is followed by the application of a constant voltage as described.
• the electrochemical cell of the present technology may have a capacity retention greater than or equal to 80% after at least 100 charge / discharge cycles with respect to the first cycle, for a load between a voltage Tinf of between 2.0 and 3, 0 volts with respect to Li7Li °, and a voltage Tsup between 3.8 and 4.2 volts with respect to Li7Li °, at a temperature equal to 60 ° C, and at a charging and discharging rate of C, the charge being optionally followed by the application of a constant voltage of 4V for 30 minutes, the positive electrode preferably comprising LiFePC.
• the voltage Tinf is equal to 2 volts and the voltage Tsup is equal to 4 volts.
• the charge is followed by the application of a constant voltage as described.
• the present application also relates to the use of the electrolyte composition as described here for:
• Another aspect relates to the use of lithium 4,5-dicyano-2- (trifluoromethyl) imidazolate in an electrolyte composition comprising lithium hexafluorophosphate, and at least one electrolytic additive, for:
• composition in particular in a temperature range greater than or equal to 25 ° C, preferably between 25 ° C and 65 ° C, preferably between 40 ° C and 60 ° C; the composition being such that:
• the total concentration of lithium 4,5-dicyano-2- (trifluoromethyl) imidazolate and lithium hexafluorophosphate is less than or equal to 1 mol / L;
• the concentration of lithium 4,5-dicyano-2- (trifluoromethyl) imidazolate is less than or equal to 0.3 mol / l, preferably less than or equal to 0.05 mol / l.
• the use of lithium 4,5-dicyano-2- (trifluoromethyl) imidazolate in an electrolyte composition as described here and comprising lithium hexafluorophosphate and at least one electrolytic additive makes it possible to improve the life of a Li-ion battery; and / or to improve the cycling stability of a Li-ion battery; and / or decrease the irreversible capacity a Li-ion battery.
• This improvement can occur, in particular in a temperature range greater than or equal to 25 ° C, preferably between 25 ° C and 65 ° C, preferably between 40 ° C and 60 ° C.
• the presence of LiTDI in the electrolyte composition makes it possible to increase the life of the battery (loss of 80% of the initial capacity) by a factor of at least 1.5, or at least 2, in comparison a battery without LiTDI used under the same conditions.
• the life of the battery is multiplied by at least 1.5, or at least 2, or multiplied by a factor in the range of 1.5 to 8, or 2 to 7. It is understood that the measurable or quantifiable values, such as concentrations, volumes, etc. mentioned in this application must be interpreted taking into account the limitations of the method of analysis and the inherent uncertainty of the instrument used.
• between x and y means an interval in which the x and y terminals are included.
• the range "between 1 and 4%” includes in particular the values 1 and 4%.
• the first example carried out consists in dissolving, at room temperature, a salt mixture containing LiPF 6 and LiTDI (or LiPF 6 alone for reference) at a total concentration of 1 mol / L, in a mixture of three carbonates: ethylene (EC), diethyl carbonate (DEC) and carbonate of fluoroethylene (FEC) in respective proportions by weight EC / DEC / FEC: 36.84%, 61.16% and 2%.
• EC ethylene
• DEC diethyl carbonate
• FEC fluoroethylene
• the second example consists in dissolving at room temperature a salt mixture containing LiPF6 and LiTDI (or LiPF6 alone for reference) at a total concentration of 1 mol / L, in a mixture of three carbonates: ethylene carbonate ( EC), diethyl carbonate (DEC) and fluoroethylene carbonate (FEC) in respective proportions by weight of 36.84%, 61.16% and 2% respectively.
• EC ethylene carbonate
• DEC diethyl carbonate
• FEC fluoroethylene carbonate
• a salt mixture containing LiPF6 and LiTDI (or LiPF6 alone for reference) is dissolved at a total concentration of 1 mol / L in a mixture of three carbonates: ethylene carbonate (EC), diethyl (DEC) and fluorethylene carbonate (FEC) in respective proportions by weight 36.84%, 61.16% and 2%.
• EC ethylene carbonate
• DEC diethyl
• FEC fluorethylene carbonate
• LiTDI lithium salt has been demonstrated in the various series of electrochemical tests performed on 10 mAh or 1 1.5 mAh battery-packs.
• the systems studied are LFP (with carbon black and NTC or VGCF) / graphite and NMC / graphite.
• the tests were carried out between 25 ° C and 60 ° C, with or without application of constant voltage at the end of the load.
• LiTDI from 0.05 mol / L
• LiTDI could capture the water molecules and prevent the formation of HF that occurs when the LiPF6 reacts with traces of moisture that may be contained in the cathodes , anodes, separator, solvent, packaging, etc.
• LiTDI does not seem to be affected by the presence of moisture and can increase the life of the battery even at low concentrations.
• the series of tests carried out also demonstrates the good resistance in excessive cycling (application of constant voltage at the end of charging) electrolytes tested when they contain LiTDI (from 0.05 mol / L).
• the tests carried out at ambient temperature on the LFP / graphite system further demonstrate the resistance to excessive cycling (no effect of temperature) electrolytes containing LiTDI, whether with VGCF or NTC type electronic conductors; the life of the battery being multiplied by 2.5 or 3.2 times.

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• 2018
  • 2018-03-09 WO PCT/IB2018/051573 patent/WO2018163127A1/fr active Application Filing
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