TECHNICAL FIELD

The present invention relates to the field of chemical components for electrolyte compositions which are useful in electrochemical cells, such as lithium-ion batteries.

More specifically, the invention provides new solvents, additives and/or electrolyte salts and their combinations, which are suitable to improve various characteristics of electrolyte compositions and, in fine, of the electrochemical cells in which said electrolyte compositions are incorporated.

BACKGROUND ART

Among the electrochemical cells, lithium-ion batteries are rechargeable batteries that are commonly used in various devices, such as portable home electronics, energy storage systems or electric vehicles. Depending on their final usage, the expectations of lithium-ion batteries in terms of safety, performance and cost are more and more challenging. Various approaches have been investigated to overcome the limitations of commonly used lithium-ion batteries. For example, new electrode materials have been developed to improve capacity. Another approach has and still consists in formulating electrolyte compositions with specific chemical solvents, additives and electrolyte salts to improve various characteristics of the battery such as cycling performance, reversible capacity and bulging limitation.

Despite the efforts in the art, we believe that there is still room for improvement for providing electrolyte compositions ingredients capable of fulfilling the required specifications of electrolyte compositions, especially those intended to be used in lithium-ion batteries.

Especially, at cathode potentials above about 4.35 V, the electrolyte solvents can decompose, which can result in a loss of battery performance. Electrolyte decomposition can also occur, generating gas which can cause swelling of the battery. There remains a need for an electrolyte composition that, when used in a lithium ion battery, can exhibit high cycle performance at low and high temperature, storage performance at high temperature, and power at low temperature.

We are reporting that several publications belonging to other unrelated technical field disclose some organic compounds:

- A scientific publication of Klaas Verschueren et al. (“Discovery of a potent protein kinase D inhibitor: insights in the binding mode of pyrazolo[3,4-d]pyrimidine analogues”, Med. Chem. Commun., 2017, 8, 640-646) discloses a compound in Scheme 3 obtained by reaction between an acid chloride and malononitrile under basic conditions. This compound is only used as intermediate compound.

- The Japanese patent application JP 2003-096042 A discloses that a compound represented by general formula (I) can be used as starting material to produce an alpha-cyanocarbonyl compound. -A scientific publication of Zvi Rappoport et al. (« Observable Enols of Anhydrides: Claimed Literature Systems, Calculations, and predictions”, Helvetica Chimica Acta, Vol.84, 2001 , p. l405- 1431) discloses some observations related to enols of carboxylic acids, esters, and amides. In particular, the keto/enol couple 41/42 is studied by theoretical calculations only.

These prior art documents do not relate to the technical field of battery. Furthermore, they fail to disclose any chemical components that are useful ingredients for electrolyte compositions, and especially any new fluorinated compounds.

BRIEF DESCRIPTION OF THE INVENTION

The above technical problems are solved thanks to the invention such as recited in the claims. The Applicant discovered new chemical components and/or new combinations of chemical components that are useful ingredients for electrolyte compositions intended to be used in electrochemical cells, especially in lithium ion batteries. The chemical components according to the present invention can be used as solvents, additives or electrolyte salts depending on their chemical structure and their amount in the electrolyte composition. They can notably improve various performance characteristics of an electrolyte composition to be used in an electrochemical cell, such as quality of the solid electrolyte interphase (SEI) that will forms on the electrodes surface in use, chemical stability, ionic conductivity, thermal stability, reversible capacity, cycle characteristics and gas generation.

DEFINITIONS

In the present disclosure, the expression“ranging from ... to .. should be understood has including the limits.

The term "electrolyte composition" as used herein, refers to a non-aqueous liquid chemical composition suitable for use as an electrolyte in an electrochemical cell.

The term“solvent” in connection with said electrolyte composition typically refers to a compound that is present in the electrolyte composition in an amount of at least 20% wt relative to the total weight of the electrolyte composition.

The term“additive” in connection with said electrolyte composition typically refers to a compound that is present in the electrolyte composition in an amount of less than 20% wt relative to the total weight of the electrolyte composition.

The term "electrolyte salt" as used herein, refers to an ionic salt that is at least partially soluble in the electrolyte composition and that at least partially dissociates into ions in the electrolyte composition to form a conductive electrolyte composition.

An“electrolyte solvent” as defined herein is a solvent or a solvent mixture for an electrolyte composition. The term“alkyl” refers to a linear or branched, saturated or unsaturated, substituted or unsubstituted, hydrocarbon chain, which comprises or not heteroatoms such as P, B, N, O, and/or S. For illustrative purposes and without being exhaustive, as possible substituents, mention can be made of halogens, alkyl, cycloalkyl, aryl, heteroaryl and/or heterocyclyl groups. A cycloalkyl group may contain up to 8 carbon atoms. An aryl group may be a monocyclic or bicyclic aromatic group. The aryl group may contain from 5 to 12 carbon atoms. A heteroaryl group may be a monocyclic or bicyclic group. The heteroaryl group may contain from 1 to 12 carbon atoms and one or more N, O or S atoms. The heteroaryl group may be a 5 or 6-membered ring containing one or more N atoms. A heterocyclyl group may be a monocyclic or bicyclic group. The heterocyclyl group may contain from 1 to 12 carbon atoms and one or more N, O or S atoms. According to an embodiment, said “alkyl” group is linear. According to an embodiment, said“alkyl” group is a Ci to C alkyl group. According to an embodiment, said“alkyl” group is saturated. According to an embodiment, said “alkyl” group is unsubstituted. According to an embodiment, said“alkyl” group does not comprise heteroatoms. Any of these embodiments can be combined with one another. Preferably,“alkyl” means a saturated, unsubstituted group comprising only carbon and hydrogen atoms, preferably 1 to 4 carbon atoms.

The term "halogenoalkyl" specifically refers to an alkyl group as defined above comprising at least one halogen atom. Especially the term“fluoroalkyl” refers to an alkyl group comprising at least one fluorine atom. The term "perhalogenoalkyl" refers to an alkyl group comprising only halogen atoms, in addition to the carbon atoms, and devoid of hydrogen atoms. The term “perfluoroalkyl” especially refers to an alkyl group comprising only fluorine atoms, in addition to the carbon atoms, and devoid of hydrogen atoms.

The term“halogenoalkoxy” specifically refers to an alkoxy group (well known to those skilled in the art) wherein at least one hydrogen atom is substituted by a halogen atom. The term “fluoroalkoxy” especially refers to an alkoxy group wherein at least one hydrogen atom is substituted by fluorine.

The term "reaction medium" refers to the medium in which the reaction takes place. The reaction medium comprises the reaction solvent when the reaction is performed in a solvent, the catalyst when a catalyst is used, and, depending on the progression of the reaction, the reactants and/or the products of the reaction. In addition, it can comprise additives and impurities.

The term“anode” refers to the electrode of an electrochemical cell, at which oxidation occurs. In a secondary (i.e. rechargeable) battery, the anode is the electrode at which oxidation occurs during discharge and reduction occurs during charging.

The term“cathode” refers to the electrode of an electrochemical cell, at which reduction occurs. In a secondary (i.e. rechargeable) battery, the cathode is the electrode at which reduction occurs during discharge and oxidation occurs during charging. The term“lithium ion battery” refers to 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.

The equilibrium potential between lithium and lithium ion is the potential of a reference electrode using lithium metal in contact with the non-aqueous electrolyte containing lithium salt at a concentration sufficient to give about 1 mole/liter of lithium ion concentration, and subjected to sufficiently small currents so that the potential of the reference electrode is not significantly altered from its equilibrium value (Li/Li ⁺ ). The potential of such a Li/Li ⁺ reference electrode is assigned here the value of 0.0V. Potential of an anode or cathode means the potential difference between the anode or cathode and that of a Li/Li ⁺ reference electrode. Herein voltage means the voltage difference between the cathode and the anode of a cell, neither electrode of which may be operating at a potential of O.OV.

An“energy storage device” is a device that is designed to provide electrical energy on demand, such as a battery or a capacitor. Energy storage devices contemplated herein at least in part provide energy from electrochemical sources.

The term“SEI”, as used herein, refers to a solid electrolyte interphase layer formed on the active material of an electrode. A lithium-ion secondary electrochemical cell is assembled in an uncharged state and must be charged (a process called formation) for use. During the first few charging events (battery formation) of a lithium-ion secondary electrochemical cell, components of the electrolyte are reduced or otherwise decomposed or incorporated onto the surface of the negative active material and oxidized or otherwise decomposed or incorporated onto the surface of the positive active material, electrochemically forming a solid-electrolyte interphase on the active materials. These layers, which are electrically insulating but ionically conducting, help prevent decomposition of the electrolyte and can extend the cycle life and improve the performance of the battery. On the anode, the SEI can suppress the reductive decomposition of the electrolyte; on the cathode, the SEI can suppress the oxidation of the electrolyte components.

DESCRIPTION OF THE INVENTION

One subject matter of the invention is an electrolyte composition, comprising at least one electrolyte salt and at least one compound of formula (V), tautomers, salts, and solvates thereof:

wherein Ri denotes H, a halogen atom, an alkyl group or a halogenoalkyl group; Rio denotes H or an alkyl group. In one embodiment, Ri denotes H or an alkyl group, preferably a C i to C alkyl group, more preferably a Ci to C ₃ alkyl group, a Ci to C ₂ alkyl group, especially a Ci alkyl group. In one sub embodiment, Ri denotes CH ₃ .

In one alternative embodiment, Ri denotes a halogen atom being preferably fluorine, or a halogenoalkyl group being preferably a fluoroalkyl group. Ri denotes more preferably a halogenoalkyl group, still more preferably a Ci to C ₄ halogenoalkyl group and even more preferably a Ci to C ₄ fluoroalkyl group; the latter can be perfluorinated. More preferably, Ri denotes a Ci to C ₃ fluoro- or perfluoroalkyl group, still more preferably a Ci to C ₂ fluoro- or perfluoroalkyl group. Ri can especially be selected from: -CH ₂ F, -CHF ₂ , -CF ₃ , -CH ₂ -CH ₂ F, -CH ₂ -CHF ₂ , -CH ₂ -CF ₃ , -CHF- CH ₃ , -CHF-CH ₂ F, -CHF-CHF ₂ , -CHF-CF ₃ , -CF ₂ -CH ₃ , -CF ₂ -CH ₂ F, -CF ₂ -CHF ₂ , and -CF ₂ -CF ₃ . In a sub-embodiment, Ri is a Ci fluoro- or perfluoroalkyl group. It can especially be selected from -CFFF, -CHF ₂ , and -CF ₃ . In one sub-embodiment Ri is -CF ₃ . In another sub-embodiment Ri is -CHF ₂ . In one sub-embodiment, Ri is -CH ₂ F.

Rio denotes H or an alkyl group being preferably a Ci to C ₄ alkyl group, more preferably H or a Ci to C ₃ alkyl group, more preferably H or a Ci to C ₂ alkyl group, more preferably H or a Ci alkyl group. Still more preferably, Rio is H.

Tautomer forms of the compound of formula (V) according to the invention (including tautomer forms of the salts and solvates thereof) are included within the scope of the present invention. When Rio is H, the compound of formula (V) may be in equilibrium with the enol compound (V’):

Keto-enol tautomerism can be represented as follow:

According to the present invention, tautomer forms of the compound (V) is included within the definition of the compound (V) itself, and thus the enol compound (V’) is included within the definition of the compound (V). Compound (V) may be referred as the free unsolvated keto molecule, whereas compound (V’) may be referred as the free unsolvated enol molecule.

Salts of the compound of formula (V) according to the invention are included within the scope of the present invention. Alkali metal salts are preferred, especially lithium salt, sodium salts, and potassium salt.

According to one embodiment, lithium salts of compound of formula (V) (or tautomers and/or solvates thereof) are preferred.

According to another embodiment, sodium salts of compound of formula (V) (or tautomers and/or solvates thereof) are preferred.

In the present text, the expression“free compound” refers to a compound which is not a salt.

Solvates of the compound of formula (V) according to the invention are included within the scope of the present invention. Without wishing to be bound by ant theory, the investors believe that the compounds of formula (V) (or tautomers or salts thereof) may form solvate compounds with solvent molecules. For example, monosolvate compounds have been identified with ethyl acetate, with diisopropyl ether and with acetonitrile.

Preferred compounds of formula (V) are given in table 1. Among these compounds, compound (V).l is particularly preferred.

Table 1: preferred compounds of formula (V)

Another subject matter of the invention is a compound of formula (V), tautomers, salts, and solvates thereof:

O

Rio (V)

wherein Ri denotes a fluoroalkyl group, and Rio denotes H or an alkyl group. Ri denotes more preferably a Ci to C fluoroalkyl group; the latter can be perfluorinated. More preferably, Ri denotes a Ci to C ₃ fluoro- or perfluoroalkyl group, still more preferably a Ci to C ₂ fluoro- or perfluoroalkyl group. Ri can especially be selected from: -CH ₂ F, -CHF ₂ , -CF ₃ , -CH ₂ - CH ₂ F, -CH ₂ -CHF ₂ , -CH ₂ -CF ₃ , -CHF-CH ₃ , -CHF-CH ₂ F, -CHF-CHF ₂ , -CHF-CF ₃ , -CF ₂ -CH ₃ , -CF ₂ - CFFF, -CF ₂ -CHF ₂ , and -CF ₂ -CF ₃ . In a sub-embodiment, Ri is a Ci fluoro- or perfluoroalkyl group. It can especially be selected from -CFFF, -CHF ₂ , and -CF ₃ . In one sub-embodiment Ri is -CF ₃ . In another sub-embodiment Ri is -CHF ₂ . In one sub-embodiment, Ri is -CH ₂ F.

Preferred compounds of formula (V) are given in table 2. Among these compounds, compound (V).l is particularly preferred.

Table 2: preferred compounds of formula (V)

Another subject-matter of the invention is a process for manufacturing the compound of formula (V), which comprises a step of reacting a compound of formula (iii) with a compound of formula (1 ₄ )

wherein

Ri denotes H, a halogen atom, an alkyl group or a halogenoalkyl group;

Rio denotes H or an alkyl group;

X denotes a halogen atom, a -OH group, a -OC(0)Ri group, a -OR group wherein R is a an alkyl group.

In one embodiment, Ri denotes H or an alkyl group, preferably an alkyl group, especially a Ci to C ₄ alkyl group.

In one alternative embodiment, Ri denotes a halogen atom being preferably fluorine, or a halogenoalkyl group being preferably a fluoroalkyl group. Ri denotes more preferably a halogenoalkyl group, still more preferably a Ci to C ₄ halogenoalkyl group and even more preferably a Ci to C ₄ fluoroalkyl group; the latter can be perfluorinated. More preferably, Ri denotes a Ci to C ₃ fluoro- or perfluoroalkyl group, still more preferably a Ci to C ₂ fluoro- or perfluoroalkyl group. Ri can especially be selected from: -CH ₂ F, -CHF ₂ , -CF ₃ , -CH ₂ -CH ₂ F, -CH ₂ -CHF ₂ , -CH ₂ -CF ₃ , -CHF- CH ₃ , -CHF-CH2F, -CHF-CHF ₂ , -CHF-CF _B , -CF ₂ -CH _3J -CF ₂ -CH ₂ F, -CF ₂ -CHF _2J and -CF ₂ -CF ₃ . In a sub-embodiment, Ri is a Ci fluoro- or perfluoroalkyl group. It can especially be selected from -CH ₂ F, -CHF ₂ , and -CF ₃ . In one sub-embodiment Ri is -CF ₃ . In another sub-embodiment Ri is -CHF ₂ . In one sub-embodiment, Ri is -CH ₂ F.

Rio denotes H or an alkyl group being preferably a C i to C alkyl group, more preferably H or a Ci to C ₃ alkyl group, more preferably H or a Ci to C ₂ alkyl group, more preferably H or a Ci alkyl group. Still more preferably, Rio is H.

In one embodiment, X denotes a halogen atom, preferably a chlorine atom.

In one embodiment, X denotes a -OR group, where R is a Ci to C alkyl group, more preferably a Ci to C ₃ alkyl group, even more preferably a Ci to C ₂ alkyl group. Still preferably, R is ethyl.

The initial molar ratio (compound of formula (^/compound of formula (iii)) preferably ranges from 0.60 to 1.40, more preferably from 0.70 to 1.10 and still preferably from 0.85 to 1.00.

The reaction step between compound (U) and a (iii) is preferably performed by means of a base. Such base is useful to deprotonate the carbon atom between the two cyanide functions in compound (iii) which will react more easily with compound (U). As suitable bases, mention can be made of trialkylamines, hydrides of alkali metals or alkaline earth metals, alkoxides of alkali metals or alkaline earth metals, carbonates of alkali metals or alkaline earth metals, organoalkali reagents. The trialkylamine is preferably selected from C1-C4 trialkylamines wherein the alkyl groups can be the same or different, being preferably triethylamine. Hydrides and alkoxides of alkali metals are preferred, especially those of sodium and potassium, still preferably those of sodium, such as sodium hydride or sodium ethoxide. Organoalkali reagents may also be preferred, especially organolithium reagents, i.e. organometallic compounds that contain carbon- lithium bonds, such as butyllithium.

According to a sub-embodiment, before performing the reaction between compound ( _¾ ) and a (iii), compound (iii) is first contacted with said base and then the obtained solution is put in contact with compound (14). Because of the exothermicity of the contacting step with the base, it is preferable to perform it under cooling and/or by contacting compound (iii) with the base progressively and/or under stirring. The amount of base to be used depends on the amount of compound (iii). It can be used in a catalytic amount as well as in excess relative to compound (iii). The molar ratio (base/compound(iii)) can typically range from 0.01 : 1 to 2: 1.

When the step of reaction between compound (¾) and compound (iii) is performed by means of an hydride of alkali metal, or and organoalkali reagent, then an alkali salt of the compound of formula (V) may be obtained. According to one specific embodiment, the step of reaction between compound (¾) and compound (iii) is performed by means of sodium hydride, and sodium salt of the compound of formula (V) is obtained. According to another specific embodiment, the step of reaction between compound (U) and compound (iii) is performed by means of lithium hydride or butyllithium, and lithium salt of the compound of formula (V) is obtained. The process according to the present invention may further comprise an additional step consisting in acidifying said alkali salt of the compound of formula (V) to obtain a free compound of formula (V). The acidification step could be carried out with any acid compound acid enough compared to the pKa of the compound of formula (V). For instance, trifluoroacetic acid can be used.

The reaction step between compound (¾) and a (iii) can be performed in a solvent, especially when a base in a solid form (salt) is used in order to solubilize said base. For this purpose, an organic solvent, preferably aprotic, is suitable. As suitable solvents, mention can be made of ethers like tetrahydrofuran, nitrogen-containing solvents like acetonitrile and dimethylformamide, and sulfur- containing solvents like dimethylsulfoxide. Ether solvents are preferred, especially tetrahydrofuran. The amount of solvent to be used can be readily determined by a person skilled in the art.

According to a sub-embodiment, before performing the reaction between compound ( _¾ ) and a (iii) and preferably before contacting compound (iii) with said base, compound (iii) is dissolved in said solvent. The amount of solvent to be used can be readily determined by a person skilled in the art. Typically, compound (iii) shall be dissolved at a concentration of 0.1 to 1.0 M of solvent.

Compound (U) can optionally be contacted with the solvent prior to the step of reaction thereof with compound (iii) to ease the contacting of the reactants during the reaction step.

The reaction step between compound of formula ( _¾ ) with compound of formula (iii) can be performed at a temperature ranging from 0°C to 100°C, preferably from 5°C to 70°C, more preferably from 10°C to 60°C, still more preferably from 15°C to 50°C. It can advantageously be performed at ambient temperature (20°C to 25°C).

It is advantageous to perform the reaction step between compound (U) with compound (iii) in two stages, by first contacting compound (U) with compound (iii) at a temperature ranging from 0°C to 10°C and preferably by maintaining the temperature below 10°C until completion of this contacting stage, and then by raising the temperature to a temperature ranging from 15°C to 50°C, preferably from 20°C to 25°C for the time necessary to complete the reaction.

The reaction is preferably performed at atmospheric pressure.

Reaction time to perform the reaction between compound of formula (U) with compound of formula (iii) can vary widely as a function of the reaction temperature chosen. It can range from 30 minutes to one day, especially from 45 minutes to 12 hours, more particularly from 1 hour to 5 hours.

The progress of the reaction between compound (U) and compound (iii) can be monitored by the degree of conversion of the compound of formula (U), which is the molar ratio of the amount of compound of formula (¾) which has been consumed to the initial amount of compound of formula (k) in the reaction medium, this degree being readily calculated after dosing compound of formula (k) remaining in the reaction medium.

The reaction medium can then be treated in a way known per se in order to separate the different compounds present, especially to isolate the compound of formula (V) obtained. It makes it possible for the remaining starting materials to be recycled in order to produce an additional amount of the targeted compound of formula (V). One or more liquid/solid separation operations can be carried out, for example in order to separate possible solid impurities from the reaction medium. The techniques used can be crystallization, filtration on different types of supports, centrifugation, separation on settling and evaporation, this list not being exhaustive. Alternatively or in addition, one or more liquid/liquid separation operations can be carried out in order to separate and/or purify the product obtained. The techniques used can be distillation, liquid/liquid extraction, separation by reverse osmosis or separation by ion-exchange resins, this list not being exhaustive. These liquid/solid and liquid/liquid separation operations can be carried out under continuous or batch conditions, it being possible for a person skilled in the art to choose the most appropriate conditions.

Accordingly, the process for making compound of formula (V) can additionally comprise a step which consists in isolating compound (V), for instance by performing at least one filtration, liquid-liquid extraction and/or distillation. For the liquid-liquid extraction, a (polar or non-polar) aprotic solvent is preferably used. Mention can be made of esters such as ethyl acetate, methyl acetate, ethyl propionate; chlorinated solvents such as dichloromethane; ethers such as diethyl ether; being preferably an ester and more preferably ethylacetate. Preferably, isolated compound of formula (V) has a purity degree of at least 94 % wt, 95% wt, 96% wt, 97% wt, 98 % wt, or even 99 % wt. As possible by-products to get rid of, a compound of formula HX wherein X is such as described above in connection with compound (U) may be produced ft can be removed by any known method, for example one of the methods described above, especially by distillation. Whenever a base containing an alkali or alkaline earth metal is used, the corresponding alkali or alkaline earth metal halogenide may be present in the reaction medium ft can be removed by any know methods such as, for instance, filtration.

The process can additionally comprise a step which consists in separating part or all of the unreacted compound of formula (¾) and (iii) and in recycling these compounds in the process.

Another subject-matter of the invention is the use, as component for an electrolyte composition, especially one suitable for electrochemical cells such as lithium ion batteries, of a compound of formula (V) as described above.

Compound(s) of formula (V) can advantageously be used for said electrolyte composition as solvent(s) or additive(s), depending on the amount added in the electrolyte composition.

One object of the present invention is accordingly an electrolyte composition, especially one suitable for an electrochemical cell such as a lithium-ion battery, comprising at least one compound selected from compounds (V) described above or a mixture thereof and at least one electrolyte salt.

Said at least one compound of formula (V) or mixtures thereof can advantageously be present in the electrolyte composition in an amount ranging from 0.05% to 95%, preferably from 0.8% to 70%, more preferably from 1% to 50%, more preferably from 2% to 20%, even more preferably from 3% to 10%, by weight relative to the total weight of the electrolyte composition. According to an embodiment wherein said compound of formula (V) is an additive, it may be present in the electrolyte composition in the range from 0.05 to about 20 percent by weight, based on the total weight of the electrolyte composition, for example in the range of from 0.05 to about 10 percent by weight, or from 0.1 to about 5.0 percent by weight, or from 0.3 to about 4.0 percent by weight, or from 0.5 to 2.0 percent by weight.

According to an embodiment wherein said compound of formula (V) is a solvent, it may be present in the electrolyte composition in the range from about 20% to about 99.95% by weight of the electrolyte composition.

The electrolyte composition according to the invention can further comprise at least one of the following compounds:

-a compound of formula (VIII)

wherein A is Si or C;

Li, L ₂ and L ₃ , which can be the same or different, independently denote a substituted or unsubstituted, linear or branched, saturated or unsaturated, C ₁ -C ₄ alkylene, C ₃ -C ₁₂ cycloalkylene, C ₃ -C ₁₂ arylene, or C ₄ -C ₁₆ arylenealkylene group, optionally comprising at least one heteroatom selected from N, O and S;

Rii, Rh and Rh, which can be the same or different, independently denote H, a halogen atom, a linear or branched C 1 -CV alkyl, C2-C8 alkenyl, C2-C8 alkynyl, or C6-C10 aryl group, optionally comprising at least one substituent selected from a halogens, hydroxyl, alkoxy, carbonyl, and carboxyl groups, and/or optionally comprising at least one heteroatom selected from N, O and S;

-a compound of formula (IX)

wherein Ri denotes H, a halogen atom, an alkyl group or a fluoroalkyl group;

L ₄ denotes a simple bond or a substituted or unsubstituted, linear or branched, saturated or unsaturated, C ₁ -C ₄ alkylene, C3-C ₁₂ cycloalkylene, C3-C ₁₂ arylene, or C ₄ -C ₁₆ arylenealkylene group, optionally comprising at least one heteroatom selected from N, O and S;

Rh denotes H, a linear or branched Ci-Cs alkyl, C2-C8 alkenyl, C2-C8 alkynyl, or C6-C10 aryl group, optionally comprising at least one substituent selected from a halogens, hydroxyl, alkoxy, carbonyl, and carboxyl groups, and/or optionally comprising at least one heteroatom selected from N, O and S;

-a compound of formula (X)

wherein Ri denotes H, a halogen atom, an alkyl group or a halogenoalkyl group;

L5 denotes a simple bond or a substituted or unsubstituted, linear or branched, saturated or unsaturated, C1-C4 alkylene, C3-C12 cycloalkylene, C3-C12 arylene, or C4-C16 arylenealkylene group, optionnaly comprising at least one heteroatom selected from N, O and S;

Ris denotes H, a linear or branched Ci-Cs alkyl, C2-C8 alkenyl, C2-C8 alkynyl, or C6-C10 aryl group, optionally comprising at least one substituent selected from a halogens, hydroxyl, alkoxy, carbonyl, and carboxyl groups, and/or optionally comprising at least one heteroatom selected from N, O and S;

-a compound of formula (XI)

wherein M3 is H, a metal or N^RieRfrRbRk), wherein Ri ₆ , R17, Ris and R¾ _> , which can be the same or different, independently denote H or a C1-C12 alkyl group.

-a compound of formula (XII)

wherein Riio and Rin, which can be the same or different, independently denote H, a Ci-Cs alkyl, C2-C8 alkenyl, C2-C8 alkynyl, or C6-C10 aryl group, optionally comprising at least one substituent selected from halogens, hydroxyl, alkoxy, carbonyl, and carboxyl groups;

-a compound of formula (XIII)

wherein Ri denotes H, a halogen atom, an alkyl group or a halogenoalkyl group;

Le is a simple bond or a substituted or unsubstituted, linear or branched, saturated or unsaturated, Ci- C ₄ alkylene, C ₃ -C ₁₂ cycloalkylene, C ₃ -C ₁₂ arylene, or C ₄ -C ₁₆ arylenealkylene group, optionally comprising at least one heteroatom selected from N, O and S;

M4 is H, a metal or N(Ri ₆ Ri ₇ RisRi ₉ ), wherein Ri6, R1 ₇ , Ris and R1 ₉ , which can be the same or different, independently denote H or a C1-C12 alkyl group;

-a compound of formula (XIV)

wherein X3 and X4, which can be the same or different, are independently selected from:

^■ NR1 ₁₂ where R1 ₁₂ is H, a C ₁ -C ₄ alkyl group, a C ₁ -C ₄ alkenyl group or a C ₁ -C ₄ alkynyl group;

^■ C R i 1 3 IR i 1 ₄ where R1 ₁₃ and R1 ₄ , which can be the same or different, are independently H, a C ₁ -C ₄ alkyl group, a C ₁ -C ₄ alkenyl group or a C ₁ -C ₄ alkynyl group;

^■ and O;

Rii5, Ri _l e, Rin and Riis, which can be the same or different, are independently selected from H, a halogen atom, a C ₁ -C ₄ alkyl group and a C ₁ -C ₄ halogenoalkyl group;

y is an integer ranging from 0 to 2 such as (1.7)0 stands for a simple bond and when y is 1 or 2, L7 stands for a CRii ₉ Ri ₂ o group where R1 ₁₉ and R1 ₂₀ , which can be the same or different, are H, a C ₁ -C ₄ alkyl group, a C ₁ -C ₄ alkenyl group or a C ₁ -C ₄ alkynyl group;

-a compound of formula (XV)

wherein Ri denotes H, a halogen atom, a C ₁ -C ₄ alkyl group or a C ₁ -C ₄ halogenoalkyl group; L8 is a simple bond or a substituted or unsubstituted, linear or branched, saturated or unsaturated, Ci-C ₄ alkylene, C ₃ -C ₁₂ cycloalkylene, C ₃ -C ₁₂ arylene, or C ₄ -C ₁₆ arylenealkylene group, optionnaly comprising at least one heteroatom selected from N, O and S;

-a compound of formula (XVI)

wherein Ri denotes H, a halogen atom, a C ₁ -C ₄ alkyl group or a C ₁ -C ₄ halogenoalkyl group;

n; denotes an integer greater than or equal to 2,

R1 ₂₃ denotes a n,- valent linkage group comprising at least one carbon atom and atoms selected from C, H, a halogen atom and O, and the S atom of the -SO ₂ R ₁ group is bound to a carbon atom of the R1 ₂₃ group;

-a compound of formula (XVII)

wherein R1 ₂₄ and R1 ₂₅ , which can be the same or different, are independently selected from H, a halogen atom, a C ₁ -C ₄ alkyl group, and a C ₁ -C ₄ halogenoalkyl group;

-and mixtures thereof.

In connection with compound of formula (VIII), according to an embodiment, A is Si. In this case, Li, L ₂ , and L ₃ which can be the same or different, preferably independently denote a simple bond or a substituted or unsubstituted, linear or branched, saturated or unsaturated, C ₁ -C ₄ alkylene, being more preferably a simple bond. Also according to this embodiment, Rii, RF and R1 ₃ , which can be the same or different, preferably independently denote a linear or branched Ci-Cs alkyl, C ₂ - C ₈ alkenyl, C ₂ -C ₈ alkynyl, more preferably a linear or branched C ₁ -C ₄ alkyl and still more preferably methyl.

Still in connection with compound of formula (VIII), according to another embodiment, A is C. In this case, Li, L ₂ , and L ₃ which can be the same or different, preferably independently denote a substituted or unsubstituted, linear or branched, saturated or unsaturated, C ₁ -C ₄ alkylene, more preferably a C ₁ -C ₃ alkylene, still more preferably a C ₁ -C ₂ alkylene, even more preferably -CH ₂ -. Also according to this embodiment, Rii, RF and R1 ₃ , which can be the same or different, preferably independently denote a fluorine atom or a linear or branched C ₁ -C ₄ fluoro or perfluoroalkyl group, being preferably F. In connection with compound of formula (IX), L ₄ denotes preferably a substituted or unsubstituted, linear or branched, saturated or unsaturated, C ₁ -C ₄ alkylene, more preferably a C ₁ -C ₃ alkylene, still more preferably a C ₁ -C ₂ alkylene, even more preferably CH ₂ . RL preferably denotes a linear or branched Ci-Cs alkyl, more preferably a C ₁ -C ₄ alkyl, still more preferably a C ₁ -C ₂ alkyl and even more preferably CH ₃ . Ri preferably denotes a C ₁ -C ₄ fluoro or perfluoroalkyl group, more preferably a C ₁ -C ₃ fluoro or perfluoroalkyl group, still more preferably a C ₁ -C ₂ fluoro or perfluoroalkyl group and even more preferably a Ci fluoro or perfluoroalkyl group, such as in particular CF ₃ .

In connection with compound of formula (X), L ₅ denotes preferably a simple bond or a substituted or unsubstituted, linear or branched, saturated or unsaturated, C ₁ -C ₄ alkylene, more preferably a simple bond or a C ₁ -C ₃ alkylene, still more preferably a simple bond or a C ₁ -C ₂ alkylene, even more preferably a simple bond or CH ₂ . Ri preferably denotes a C ₁ -C ₄ fluoro or perfluoroalkyl group, more preferably a C ₁ -C ₃ fluoro or perfluoroalkyl group, still more preferably a C ₁ -C ₂ fluoro or perfluoroalkyl group and even more preferably a Ci fluoro or perfluoroalkyl group. In one sub embodiment, L ₅ is a simple bond and Ri is CH ₂ F or CF ₃ . In another sub-embodiment, L ₅ is CFL and Ri is CHF ₂ . In any cases, Ris preferably denotes a linear or branched Ci-Cs alkyl, more preferably a C ₁ -C ₄ alkyl, still more preferably a C ₁ -C ₂ alkyl and even more preferably CH ₃ .

In connection with compound of formula (XI), M ₃ is preferably a metal selected from alkali metals and rare earth metals; more preferably from alkali metals, especially Li and Na; and still more preferably Li.

In connection with compound of formula (XII), Riio and Riu, which can be the same or different, preferably independently denote a Ci-Cs alkyl, more preferably a C ₁ -C ₄ alkyl, still more preferably a C ₁ -C ₂ alkyl and even more preferably CH ₃ .

In connection with compound of formula (XIII), Ri preferably denotes a C ₁ -C ₄ fluoro or perfluoroalkyl group, more preferably a C ₁ -C ₃ fluoro or perfluoroalkyl group, still more preferably a C ₁ -C ₂ fluoro or perfluoroalkyl group and even more preferably a Ci fluoro or perfluoroalkyl group, such as in particular CF ₃ . Lr, preferably denotes a simple bond or a substituted or unsubstituted, linear or branched, saturated or unsaturated, C ₁ -C ₄ alkylene, being more preferably a simple bond. IVL is preferably a metal selected from alkali metals and rare earth metals; more preferably from alkali metals, especially Li and Na; and still more preferably Li.

In connection with compound of formula (XIV), according to one embodiment, X ₃ is NR1 ₁₂ where R1 ₁₂ is H, a C ₁ -C ₄ alkyl group, a C ₁ -C ₄ alkenyl group or a C ₁ -C ₄ alkynyl group. Preferably, R1 ₁₂ is a C ₁ -C ₄ alkyl group, more preferably a C ₁ -C ₂ alkyl group and more preferably CH ₃ . In this case, X ₄ is preferably C Ri 3 Ri ₄ where R1 ₁₃ and Rii ₄ , which can be the same or different, are independently H, a C ₁ -C ₄ alkyl group, a C ₁ -C ₄ alkenyl group or a C ₁ -C ₄ alkynyl group. Rio and Ri ₄ , are preferably independently H or a C ₁ -C ₄ alkyl group, and more preferably both H. According to the same embodiment, Rii Rii ₆ , Rin and Rii x, which can be the same or different, are preferably independently selected from H and a C ₁ -C ₄ alkyl group, being more preferably H.

According to another embodiment, X3 is O. In this case, ¾ is preferably O. According to the same embodiment, Rin, Rii ₆ , Rin and Rin, which can be the same or different, are preferably independently selected from H and a halogen atom, more preferably from H and fluorine. In one sub embodiment, Rin, Rin and Rin are both H and Rin is fluorine.

Still in connection with compound of formula (XIV), y is preferably equal to 0 such as (In)o stands for a simple bond.

In connection with compound of formula (XV), Ri preferably denotes a C ₁ -C ₄ fluoro or perfluoroalkyl group, more preferably a C ₁ -C ₃ fluoro or perfluoroalkyl group, still more preferably a C ₁ -C ₂ fluoro or perfluoroalkyl group and even more preferably a Ci fluoroalkyl group, such as in particular CHF ₂ . Lx preferably denotes a substituted or unsubstituted, linear or branched, saturated or unsaturated, C ₁ -C ₄ alkylene, being more preferably a C ₁ -C ₃ alkylene, still more preferably a Ci- C ₂ alkylene, even more preferably CH ₂ .

In connection with compound of formula (XVI), Ri denotes preferably a halogen atom or a C ₁ -C ₄ halogenoalkyl group, more preferably F or a C ₁ -C ₄ fluoro or perfluoroalkyl group and still preferably Ri is F. The index n, preferably denotes an integer equal to 2 so that R1 ₂₃ denotes a divalent linkage. R1 ₂₃ preferably denotes an alkylene, more preferably a Ci-Ce alkylene, a C ₁ -C ₅ alkylene, a C ₁ -C ₄ alkylene and more preferably a C ₃ alkylene, especially C ₃ H ₆ .

In connection with compound of formula (XVII), R1 ₂₄ and R1 ₂₅ , which can be the same or different, are preferably selected from H, F, a C ₁ -C ₄ alkyl group, and a C ₁ -C ₄ fluoroalkyl group. RL ₄ is preferably selected from F and a C ₁ -C ₄ fluoroalkyl group, being preferably F. R1 ₂₅ is preferably selected from H, F and a C ₁ -C ₄ fluoroalkyl group, being more preferably selected from H and F. In one sub-embodiment, RF ₄ is F and R1 ₂₅ is H. In another sub-embodiment, RL ₄ and R1 ₂₅ are both F.

Said at least one compound of formula (VIII), (IX), (X), (XI), (XII), (XIII), (XIV), (XV), (XVI) or mixture thereof can be present in the electrolyte composition in an amount ranging from 0.05% to 94.5%, preferably from 0.8% to 70%, more preferably from 1% to 50%, more preferably from 2% to 20%, even more preferably from 3% to 10%, by weight relative to the total weight of the electrolyte composition.

The electrolyte composition according to the invention can further comprise at least one non- fluorinated cyclic carbonate, preferably selected from ethylene carbonate, propylene carbonate, vinylene carbonate, ethyl propyl vinylene carbonate, vinyl ethylene carbonate, dimethylvinylene carbonate, and mixtures thereof.

Said non-fluorinated cyclic carbonate can be present in the electrolyte composition in an amount ranging from 5% to 50%, preferably from 10% to 45%, more preferably from 12% to 40%, more preferably from 15% to 35%, even more preferably from 17% to 30%, by weight relative to the total weight of the electrolyte composition. The electrolyte composition according to the invention can further comprise at least one non- fluorinated acyclic carbonate, preferably selected from ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, di-tert-butyl carbonate, dipropyl carbonate, di-tert-butyl carbonate, dipropyl carbonate, methyl propyl carbonate, methyl butyl carbonate, ethyl butyl carbonate, propyl butyl carbonate, dibutyl carbonate, and mixtures thereof.

Said non-fluorinated acyclic carbonate can be present in the electrolyte composition in an amount ranging from 5% to 50%, preferably from 10% to 45%, more preferably from 12% to 40%, more preferably from 15% to 35%, even more preferably from 17% to 30%, by weight relative to the total weight of the electrolyte composition.

The electrolyte composition according to the invention can further comprise at least one fluorinated carbonate, preferably selected from 4-fluoro-l,3-dioxolan-2-one; 4-fluoro-4-methyl-l,3- dioxolan-2-one; 4-fluoro-5-methyl-l,3-dioxolan-2-one; 4-fluoro-4,5-dimethyl-l,3-dioxolan-2-one;

4.5-difluoro-l,3-dioxolan-2-one; 4,5-difluoro-4-methyl-l,3-dioxolan-2-one; 4,5-difluoro-4,5- dimethyl-l,3-dioxolan-2-one; 4,4-difluoro-l,3-dioxolan-2-one; 4,4,5-trifluoro-l,3-dioxolan-2-one;

4.4.5.5-tetrafluoro-l,3-dioxolan-2-one; and mixtures thereof; being preferably 4-fluoro-l,3- dioxolan-2-one.

Said fluorinated carbonate can be present in the electrolyte composition in an amount ranging from 0.05% to 20%, preferably from 0.8% to 15%, more preferably from l% to 10%, more preferably from 2% to 10%, even more preferably from 3% to 10%, by weight relative to the total weight of the electrolyte composition.

The electrolyte composition according to the invention can further comprise at least one compound selected from:

-a fluorinated acyclic carboxylic acid ester represented by the formula:

R13-COO-R14,

-a fluorinated acyclic carbonate represented by the formula:

R15-OCOO-R16,

-a fluorinated acyclic ether represented by the formula:

R17-O-R18,

- and mixtures thereof,

wherein

i) R ₁₃ is H, an alkyl group, or a fluoroalkyl group;

ii) R ₁₅ and Rn is each independently a fluoroalkyl group and can be either the same as or different from each other;

iii) R ₁₄ , Ri ₆ , and Ri x is each independently an alkyl group or a fluoroalkyl group and can be either the same as or different from each other;

iv) either or both of R ₁₃ and R ₁₄ comprises fluorine; and v) R _B and R _M , R _B and Ri ₆ , Rn and R _B , each taken as a pair, comprise at least two carbon atoms but not more than seven carbon atoms.

These compounds can advantageously be used as solvents in the electrolyte compositions according to the present invention (hereinafter referred to as the“fluorinated solvents”).

Preferably, none of RB, RM, RB, RB, Rn, nor RB contains a FCTh- group or a -FCH- group.

In another embodiment, R _B and R _B in the formula above do not contain fluorine, and Rn and R _B contain fluorine.

Suitable fluorinated acyclic carboxylic acid esters are represented by the formula:

RB-COO-RM

wherein

i) R _B is H, an alkyl group, or a fluoroalkyl group;

ii) R _M is an alkyl group or a fluoroalkyl group;

iii) either or both of R _B and Rn comprises fluorine; and

iv) R _B and R _M , taken as a pair, comprise at least two carbon atoms but not more than seven carbon atoms.

In one embodiment, R _B is H and R _M is a fluoroalkyl group. In one embodiment, R _B is an alkyl group and R _M is a fluoroalkyl group. In one embodiment, R _B is a fluoroalkyl group and R _M is an alkyl group. In one embodiment, R _B is a fluoroalkyl group and R _M is a fluoroalkyl group, and R _B and R _M can be either the same as or different from each other. In one embodiment, R _B comprises one carbon atom. In one embodiment, R _B comprises two carbon atoms.

In another embodiment, R _B and R _M are as defined herein above, and R _B and R _M , taken as a pair, comprise at least two carbon atoms but not more than seven carbon atoms and further comprise at least two fluorine atoms, with the proviso that neither R _B nor R _M contains a FCFfi- group or a - FCH- group.

In one embodiment, the number of carbon atoms in R _B in the formula above is 1, 3, 4, or 5.

In another embodiment, the number of carbon atoms in R _B in the formula above is 1.

Examples of suitable fluorinated acyclic carboxylic acid esters include without limitation CH ₃ -COO-CH ₂ CF ₂ H (2,2-difluoroethyl acetate, CAS No. 1550-44-3), CH ₃ -COO-CH ₂ CF ₃ (2,2,2- trifluoroethyl acetate, CAS No. 406-95-1), CH ₃ CH ₂ -COO-CH ₂ CF ₂ H (2,2-difluoroethyl propionate, CAS No. 1133129-90-4), CH ₃ -COO-CH ₂ CH ₂ CF ₂ H (3,3-difluoropropyl acetate), CH ₃ CH ₂ -COO- CH ₂ CH ₂ CF ₂ H (3,3-difluoropropyl propionate), F ₂ CHCH ₂ -COO-CH ₃ , F ₂ CHCH ₂ -COO-CH ₂ CH ₃ , and F ₂ CHCH ₂ CH ₂ -COO-CH ₂ CH ₃ (ethyl 4,4-difluorobutanoate, CAS No. 1240725-43-2), H-COO- CH ₂ CF ₂ H (difluoroethyl formate, CAS No. 1137875-58-1), H-COO-CH ₂ CF ₃ (trifluoroethyl formate, CAS No. 32042-38-9), and mixtures thereof. According to a preferred embodiment, the fluorinated acyclic carboxylic acid ester comprises 2,2-difluoroethyl acetate (CH ₃ -COO-CH ₂ CF ₂ H). According to another preferred embodiment, the fluorinated acyclic carboxylic acid ester comprises 2,2- difluoroethyl propionate (CH ₃ CH ₂ -COO-CH ₂ CF ₂ H). According to another preferred embodiment, the fluorinated acyclic carboxylic acid ester comprises 2,2,2-trifluoroethyl acetate (CH ₃ -COO- CH ₂ CF ₃ ). According to another preferred embodiment, the fluorinated acyclic carboxylic acid ester comprises 2,2-difluoroethyl formate (H-COO-CH ₂ CF ₂ H).

Suitable fluorinated acyclic carbonates are represented by the formula

R15-OCOO-R16

wherein

i) R ₁₅ is a fluoroalkyl group;

ii) Ri ₆ is an alkyl group or a fluoroalkyl group; and

iii) R ₁₅ and Ri ₆ taken as a pair comprise at least two carbon atoms but not more than seven carbon atoms.

In one embodiment, R ₁₅ is a fluoroalkyl group and Ri ₆ is an alkyl group. In one embodiment, R ₁₅ is a fluoroalkyl group and Ri ₆ is a fluoroalkyl group, and R ₁₅ and Ri ₆ can be either the same as or different from each other. In one embodiment, R ₁₅ comprises one carbon atom. In one embodiment, R ₁₅ comprises two carbon atoms.

In another embodiment, R ₁₅ and Ri ₆ are as defined herein above, and R ₁₅ and Ri ₆ , taken as a pair, comprise at least two carbon atoms but not more than seven carbon atoms and further comprise at least two fluorine atoms, with the proviso that neither R ₁₅ nor Ri ₆ contains a FCFb- group or a - FCH- group.

Examples of suitable fluorinated acyclic carbonates include without limitation CH ₃ - 0C(0)0-CH ₂ CF ₂ H (methyl 2,2-difluoroethyl carbonate, CAS No. 916678-13-2), C1¾-0C(0)0-

CH ₂ CF ₃ (methyl 2,2,2-trifluoroethyl carbonate, CAS No. 156783-95-8), C1¾-0C(0)0- CH ₂ CF ₂ CF ₂ H (methyl 2,2,3,3-tetrafluoropropyl carbonate, CAS No.156783-98-1), HCF ₂ CH ₂ - OCOO-CH ₂ CH ₃ (ethyl 2,2-difluoroethyl carbonate, CAS No. 916678-14-3), and CF ₃ CH ₂ -OCOO- CH ₂ CH ₃ (ethyl 2,2,2-trifluoroethyl carbonate, CAS No. 156783-96-9).

Suitable fluorinated acyclic ethers are represented by the formula

R17-O-R18

wherein

i) Rn is a fluoroalkyl group;

ii) Ri ₈ is an alkyl group or a fluoroalkyl group; and

iii) Rn and Ri ₈ taken as a pair comprise at least two carbon atoms but not more than seven carbon atoms.

In one embodiment, Rn is a fluoroalkyl group and Rn is an alkyl group. In one embodiment, Rn is a fluoroalkyl group and Rn is a fluoroalkyl group, and Rn and Rn can be either the same as or different from each other. In one embodiment, Rn comprises one carbon atom. In one embodiment, Rn comprises two carbon atoms.

In another embodiment, Rn and Rn are as defined herein above, and Rn and Rn, taken as a pair, comprise at least two carbon atoms but not more than seven carbon atoms and further comprise at least two fluorine atoms, with the proviso that neither Rn nor Ri* contains a FCH2- group or a - FCH- group.

Examples of suitable fluorinated acyclic ethers include without limitation HCF2CF2CH2-O- CF2CF2H (CAS No. 16627-68-2) and HCF2CH2-O-CF2CF2H (CAS No. 50807-77-7).

As explained above, the electrolyte composition according to the invention may comprise, advantageously as solvent, a fluorinated acyclic carboxylic acid ester, a fluorinated acyclic carbonate, a fluorinated acyclic ether, or mixtures thereof. As used herein, the term“mixtures thereof’ encompasses both mixtures within and mixtures between solvent classes, for example mixtures of two or more fluorinated acyclic carboxylic acid esters, and also mixtures of fluorinated acyclic carboxylic acid esters and fluorinated acyclic carbonates, for example. Non-limiting examples include a mixture of 2,2-difluoroethyl acetate and 2,2-difluoroethyl propionate; and a mixture of 2,2- difluoroethyl acetate and 2,2 difluoroethyl methyl carbonate.

The fluorinated acyclic carboxylic acid ester, the fluorinated acyclic carbonate and/or the fluorinated acyclic ether can be present in the electrolyte composition in an amount ranging from 5% to 95%, preferably from 10% to 80%, more preferably from 20% to 75%, more preferably from 30% to 70%, even more preferably from 50% to 70%, by weight relative to the total weight of the electrolyte composition.

The electrolyte composition according to the invention further comprises at least one electrolyte salt. Said electrolyte salt is preferably a lithium salt when the electrolyte composition is to be used in a lithium-ion battery. The lithium electrolyte salt is preferably selected from hexafluorophosphate (LiPFr,), lithium bis(trifluoromethyl)tetrafluorophosphate (LiPF i(CF3)2), lithium bis(pentafluoroethyl)tetrafluorophosphate (LiPFriCFFxp), lithium tris(pentafluoroethyl)trifluorophosphate (LiPFTCFFflx), lithium bis(trifluoromethanesulfonyl)imide (LiN(CF3S0 ₂ ) ₂ ), lithium bis(perfluoroethanesulfonyl)imide LiNfCFFxSChF, LiNfCFFsSChF, lithium (fluorosulfonyl) (nonafluorobutanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium hexafluoroantimonate, lithium tetrachloroaluminate, L1AIO4, lithium trifluoromethanesulfonate, lithium nonafluorobutanesulfonate, lithium tris(trifluoromethanesulfonyl)methide, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, LFB^F^- _x H _x where x is an integer equal to 0 to 8, and mixtures of lithium fluoride and anion receptors such as B(OOTf. The lithium electrolyte salt is preferably selected from lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide and lithium bis(trifluoromethanesulfonyl)imide, and is preferably hexafluorophosphate.

The electrolyte salt is present in the electrolyte composition of the invention in an amount ranging from 5% to 20%, preferably from 6% to 18%, more preferably from 8% to 17%, more preferably from 9% to 16%, even more preferably from 11% to 16%, by weight relative to the total weight of the electrolyte composition. One further object of the invention is the use of at least one compound of formula (I) to (VII) such as defined above, eventually in combination with at least one compound of formula (VIII) to (XVII) such as defined above, as component(s) of an electrolyte composition, especially one suitable for an electrochemical cells such as a lithium-ion battery.

One other object of the present invention is an electrochemical cell comprising:

(a) a housing;

(b) an anode and a cathode disposed in the housing and in ionically conductive contact with one another;

(c) an electrolyte composition according to the invention.

Especially, there is provided herein an electrochemical cell comprising a housing, an anode and a cathode disposed in the housing and in ionically conductive contact with one another, an electrolyte composition, as described herein above providing an ionically conductive pathway between the anode and the cathode, and a porous or microporous separator between the anode and the cathode. According to a preferred embodiment, the electrochemical cell is a lithium ion battery.

The housing may be any suitable container to house the electrochemical cell components. Housing materials are well known in the art and can include, for example, metal and polymeric housings. While the shape of the housing is not particularly important, suitable housings can be fabricated in the shape of a small or large cylinder, a prismatic case, or a pouch. The anode and the cathode may be comprised of any suitable conducting material depending on the type of electrochemical cell. Suitable examples of anode materials include without limitation lithium metal, lithium metal alloys, lithium titanate, aluminum, platinum, palladium, graphite, transition metal oxides, and lithiated tin oxide. Suitable examples of 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 polyvinylferrocene.

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, 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 the cathode, but small enough to prevent contact of the anode and cathode either directly or from particle penetration or dendrites which can form 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, now U.S. Patent No. 8,518,525).

Many different types of materials are known that can function as the anode or the cathode. In some embodiments, the cathode can include, for example, cathode electroactive materials comprising lithium and transition metals, such as L1C0O2, LiNiCE, LiMmO i, LiCoo.2Nio.2O2, L1V3O8, LiNio.5Mn1.5O4; LiFeP0 ₄ , LiMnPO i, L1C0PO4, and L1VPO4F. In other embodiments, the cathode active materials can include, for example:

Li _a CoG _b 0 ₂ , where 0.90 < a < 1.8, and 0.001 < b < 0.1 ;

Li _a Ni _b Mn _c Co _{d e} 0 _2-f Z _f , where 0.8 < a < 1.2, 0.1 < b < 0.9, 0.0 < c < 0.7, 0.05 < d < 0.4, 0 < e < 0.2, wherein the sum of b+c+d+e is about 1, and 0<f<0.08;

Li _a Ai-b,RbD2, where 0.90 < a < 1.8 and 0 < b < 0.5;

Li _a Ei- _b R _b 0 _2-c D _c , where 0.90 < a < 1.8, 0 < b < 0.5 and 0 < c < 0.05;

Li _a Nii_ _b-c Co _b R _c 0 _2-d Z _d , where 0.9 < a < 1.8, 0 < b < 0.4, 0 < c < 0.05, and 0 < d < 0.05; Lii+ _z Nii- _x -yCo _x AlyCL, where 0 < x < 0.3, 0 < y <0.1, and 0 < z < 0.06.

In the above chemical formulas, A is Ni, Co, Mn, or a combination thereof; D is O, F, S, P, or a combination thereof; E is Co, Mn, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; R is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, Zr, Ti, a rare earth element, or a combination thereof; Z is F, S, P, or a combination thereof. Suitable cathodes include those disclosed in U.S. Patent Nos. 5,962,166; 6,680,145; 6,964,828; 7,026,070; 7,078,128; 7,303,840; 7,381,496; 7,468,223; 7,541,114; 7,718,319; 7,981,544; 8,389,160; 8,394,534; and 8,535,832, and the references therein. By“rare earth element” is meant the lanthanide elements from La to Lu, and Y and Sc.

In another embodiment the cathode material is an NMC cathode; that is, a LiNiMnCoO cathode, more specifically, cathodes in which

the atomic ratio ofNi:Mn:Co is 1 : 1 : 1 (Li _a Nii _4>c Co _b R _c 0 _2-d Z _d where 0.98 < a < 1.05, 0 < d < 0.05, b = 0.333, c = 0.333, where R comprises Mn); or

the atomic ratio of Ni:Mn:Co is 5:3:2 (Li _a Nii _4>c Co _b R _c 0 _2-d Z _d where 0.98 < a < 1.05, 0 < d < 0.05, c = 0.3, b = 0.2, where R comprises Mn).

In another embodiment, the cathode comprises a material of the formula Li _a Mn _b J _c 04Z _d , wherein J is Ni, Co, Mn, Cr, Fe, Cu, V, Ti, Zr, Mo, B, Al, Ga, Si, Li, Mg, Ca, Sr, Zn, Sn, a rare earth element, or a combination thereof; Z is F, S, P, or a combination thereof; and 0.9 < a < 1.2, 1.3 < b < 2.2, 0 < c < 0.7, 0 < d < 0.4.

In another embodiment, the cathode in the electrochemical cell or lithium ion battery disclosed herein comprises a cathode active material exhibiting greater than 30 mAh/g capacity in the potential range greater than 4.6 V versus a Li/Li ⁺ reference electrode. One example of such a cathode is a stabilized manganese cathode comprising a lithium-containing manganese composite oxide having a spinel structure as cathode active material. The lithium-containing manganese composite oxide in a cathode suitable for use herein comprises oxides of the formula Li _x Ni _y M _z Mn2- _y-z 04- _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.

In another embodiment, the cathode comprises a composite material represented by the structure of Formula:

wherein:

x is about 0.005 to about 0.1;

A comprises one or more of Mn or Ti;

Q comprises one or more of Al, Ca, Co, Cr, Cu, Fe, Ga, Mg, Nb, Ni, Ti, V, Zn, Zr or Y;

e is 0 to about 0.3;

v is 0 to about 0.5.

w is 0 to about 0.6;

M comprises one or more of Al, Ca, Co, Cr, Cu, Fe, Ga, Li, Mg, Mn, Nb, Ni, Si, Ti, V, Zn, Zr or Y;

d is 0 to about 0.5;

y is about 0 to about 1 ; and

z is about 0.3 to about 1 ; and

wherein the Li _y Mn2- _z M _z 04- _d component has a spinel structure and the Li2- _w Q _w+v Ai- _v 03-e component has a layered structure.

In the above formula, x can be preferably about 0 to about 0.1.

In another embodiment, the cathode in the lithium ion battery disclosed herein comprises

Li _a Ai- _x R _x DO i- _f Z _f ,

wherein:

A is Fe, Mn, Ni, Co, V, or a combination thereof;

R is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, Zr, Ti, a rare earth element, or a combination thereof;

D is P, S, Si, or a combination thereof;

Z is F, Cl, S, or a combination thereof;

- 0.8 < a < 2.2;

0 < x < 0.3; and

- 0 < f< 0.l.

In another embodiment, the cathode in the lithium ion battery ore electrochemical cell disclosed herein comprises a cathode active material which is charged to a potential greater than or equal to about 4.1 V, or greater than or equal to 4.35 V, or greater than 4.5 V, or greater than or equal to 4.6 V versus a Li/Li ⁺ reference electrode. Other examples are layered- layered high-capacity oxygen- release cathodes such as those described in U.S. Patent No. 7,468,223 charged to upper charging potentials above 4.5 V.

In some embodiments, the cathode comprises a cathode active material exhibiting greater than 30 mAh/g capacity in the potential range greater than 4.6 V versus a Li/Li ⁺ reference electrode, or a cathode active material which is charged to a potential greater than or equal to 4.35 V versus a Li/Li ⁺ reference electrode.

A cathode active material suitable for use herein can be prepared using methods such as the hydroxide precursor method described by Liu et al (./. 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 resulting precipitate is oven-dried and then fired with the required amount of LiOLPLLO at about 800 to about l000°C in oxygen for 3 to 24 hours. Alternatively, 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).

A cathode, in which the cathode active material is contained, suitable for use herein may be prepared by methods such as mixing an effective amount of the cathode active material (e.g. about 70 wt% to about 97 wt%), a polymer binder, such as polyvinylidene difluoride, and 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.

An electrochemical cell or lithium ion battery as disclosed herein further contains an anode, which comprises an anode active material that is capable of storing and releasing lithium ions. Examples of suitable anode active materials include, for example, lithium alloys such as lithium- aluminum alloy, lithium- lead alloy, lithium-silicon alloy, and lithium-tin alloy; carbon materials such as graphite and mesocarbon microbeads (MCMB); phosphorus-containing materials such as black phosphorus, M11P4 and C0P3; metal oxides such as SnCL, SnO and T1O2; nanocomposites containing antimony or tin, for example nanocomposites containing antimony, oxides of aluminum, titanium, or molybdenum, and carbon, such as those described by Yoon et al (Chem. Mater. 21, 3898-3904, 2009); and lithium titanates such as LLThOi : and LiTLO i. ln one embodiment, the anode active material is lithium titanate or graphite ln another embodiment, the anode is 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 dissolved or dispersed in an organic solvent or water, which is then mixed with the active, conductive material to obtain a paste. The paste is coated onto a metal foil, preferably aluminum or copper foil, to be used as the current collector. The paste is dried, preferably with heat, so that the active mass is bonded to the current collector. Suitable anode active materials and anodes are available commercially from companies such as Hitachi, NE1 lnc. (Somerset, NJ), and Farasis Energy lnc. (Hayward, CA). The electrochemical cell as disclosed herein can be used in a variety of applications. For example, the electrochemical cell can be used for grid storage or as a power source in various electronically powered or assisted devices (“Electronic Device”) such as a computer, a camera, a radio, a power tool, a telecommunications device, or a transportation device (including a motor vehicle, automobile, truck, bus or airplane).

One other object of the present invention is an electronic device, a transportation device, or a telecommunications device, comprising an electrochemical cell according to the invention.

One other object of the present invention is a method for forming an electrolyte composition. The method comprises combining a) at least one compound selected from those of formula (V), b) at least one electrolyte salt, c) optionally at least one compound selected from those of formula (VIII) to (XVII), to form the electrolyte composition. In some embodiments, other components, especially such as those described above in connection with the electrolyte composition of the invention, are combined according to this method. Mention can be made of non-fluorinated cyclic carbonates, non- fluorinated acyclic carbonates, fluorinated cyclic carbonates, fluorinated acyclic carboxylic acids, fluorinated acyclic carbonates and/or fluorinated acyclic ethers described above. The components can be combined in any suitable order. The step of combining can be accomplished by adding the individual components of the electrolyte composition sequentially or at the same time. In some embodiments, the components a) and c) are combined to make a first solution. After the formation of the first solution, an amount of the electrolyte salt is added to the first solution in order to produce the electrolyte composition having the desired concentration of electrolyte salt. Alternatively, the components a) and b) are combined to make a first solution, and after the formation of the first solution an amount of component c) and/or the other optional components is added to produce the electrolyte composition. Typically, the electrolyte composition is stirred during and/or after the addition of the components in order to form a homogeneous mixture.

Should the disclosure of any patents, patent applications, and publications which are incorporated herein by reference conflict with the description of the present application to the extent that it may render a term unclear, the present description shall take precedence.

The claims are integral part of the description of the present application.

The invention will now be further described in examples without intending to limit it.

EXAMPLES

The present invention is further defined in the following examples. It should be understood that these examples, while indicating preferred embodiments of the invention, are given by way of illustration only. From the above discussion and these examples, one skilled in the art can ascertain the essential characteristics of this invention, and without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various uses and conditions.

Preparation of the compounds

Otherwise indicated, the raw materials used are commercially available. Mention can be made especially of: tetrahydrofuran (Sigma-Aldrich, Germany), trifluoroacetyl chloride (Sigma- Aldrich, Germany), malononitrile (Sigma-Aldrich, Germany), sodium hydride (Sigma-Aldrich, Germany).

Example 1: synthesis of trilluoroacetylmalononitrile (compound (V).l)

To a solution of trifluoroacetyl chloride F ₃ CCOCI (l68.5g, lmol) in THF (500ml), maintained at 0-5°C is added a sodium salt of malononitrile* (90g, l .02mol) in THF (300ml); the temperature is maintained at 5-lO°C during the addition and then raised to 20°C; the corresponding suspension is stirred during lh.

After filtration of the crude mixture and evaporation of the solvent, trifluoroacetyl malononitrile is isolated by vacuum distillation (l30g, yield 80%, purity > 95% by quantitative ¹⁹ F NMR).

*the sodium salt of malononitrile is obtained by treating malononitrile with NaH in THF: 1 eq NaH is added portionwise to the solution of malononitrile in THF by moderate cooling; during addition, gas (hydrogen) is generated. Generation of gas stops when the sodium salt of malononitrile is fully formed.

Example 2: synthesis of lithium trifluoromethylmalononitrile ethyl acetate solvate

Malononitrile l3.28g (0.20lmol) was dissolved in l 80ml of THF and cooled to 0°C. Then 85ml of 2.5M nBuLi in hexanes was added dropwise under Ar atmosphere and stirred 20min. Finally, 30g (0.21 l2mol) of ethyl trifluoroacetate was added and reaction mixture was stirred at 60°C for l6h. Solvents were evaporated under vacuum and concentrated product was passed through silica gel column with ethyl acetate as mobile phase. Collected fractions with product were concentrated under vacuum until brown-red resin was formed. NMR spectra showed, that lithium salt solvate with ethyl acetate (1 : 1) is formed.

Example 3: synthesis of lithium trifluoromethylmalononitrile diisopropyl ether monosolvate

To lithium trifluoromethylmalononitrile ethyl acetate solvate obtained according to Example 2 (50.07g), diisopropyl ether was added and efficiently stirred. Slowly resin is converted to dark creamy solid. Maceration was repeated 6-7 times with fresh portions of ether (200ml), with decantation. After final maceration product was dried under reduced pressure, yielding lithium salt solvate as creamy, highly hygroscopic powder, with correct HPLC and NMR data.

Example 4: synthesis of trifluoromethylmalononitrile diisopropyl ether monosolvate

Lithium trifluoromethylmalononitrile diisopropyl ether solvate obtained in Example 3 (45.39g, O.l68mol) was dissolved in l20ml of THF and cooled to 0°C. Then l3ml of TFA was added dropwise and stirred for lOmin. Such solution was poured on chromatography column and was immediately purified using EtOAc:hexane (8:2) as mobile phase. Fractions were collected and evaporated under vacuum. To the brown red oily residue, diisopropyl ether was added, causing fast precipitation of free trifluoromethylmalononitrile diisopropyl ether monosolvate. Product was washed 4 times with 250ml of diisopropyl ether. Excess of solvent was removed by decantation, the residue was dried under vacuum for 48 h, giving product as white-creamy, very hygroscopic powder.

Example 5: synthesis of free unsolvated trifluoromethylmalononitrile

Malononitrile 9.9lg (O.l5mol) was dissolved in 220ml of THF and cooled to 0°C. Then 6.6g of 60% NaH (0.165mol) was added in four portions under Ar atmosphere and stirred 30 min. Finally, 23.44g (O.l65mol) of ethyl trifluoroacetate was added and reaction mixture was stirred at gentle reflux for l6h. Reaction medium was cooled to 0°C, l2.7ml of TFA was added dropwise, the mixture was concentrated to 110-120ml and poured directly on silicagel column. Compound was purified with EtOAc:hexane 8:2 as mobile phase, pure fractions were collected and evaporated, yielding brown-red oil. Such oil was added dropwise to 300ml of intensively stirred diisopropyl ether. Precipitated solid was macerated 3 times with 300ml of diisopropyl ether and evaporated to dryness. The product was further purified with column chromatography in mobile phase DCM:AcCN 7:3, then 6:4. Collected fractions were evaporated yielding red oil, which crystallized when cooled. It was then pulverized and dried under vacuum overnight. Pinkish, crystalline powder of free non-solvated trifluoromethylmalononitrile was obtained as proved by NMR analyses.

Preparation of the electrolyte compositions In addition to the compounds synthesized in example 1, the following battery grades compounds (called hereinafter compounds C) are used for the preparation of the electrolytes composition:

tris(trimethylsilyl) phosphate (CAS 10497-05-09) (Sigma- Aldrich, Germany),

tris(trifluoroethyl)phosphate (CAS 358-63-4) (Tokyo Chemical Industry, Japan),

methyl 3,3,3-trifluoropropanonate (CAS 18830-44-9) (TCI Chemicals, India),

1.1-difluoro-2-(methylsulfonyl)ethane (CAS 1214268-07-1), prepared by the method described in WO 2015/051141

(fluoromethylsulfonyl)methane (CAS 94404-44-1), prepared from dimethylsulfoxide and (diethyl amino)sulfur trifluoride according to the method described in J-R. McCarthy, ./. Am. Soc., 107, 735-736 (1985),

trifluoro(methylsulfonyl)methane (CAS 421-82-9) (Apolloscientific, UK),

lithium biscyano(trifluoromethylsulfonyl)methide (CAS 210043-24-6), prepared according to example 2 of US6576159 from malononitrile, lithium hydride and 1- (trifluoromethanesulfonyl)imidazole,

lithium tris (oxalato)phosphate (CAS 321201-33-6), prepared according to examples 1 and 2 of EP1203001,

2.2-dimethyl-l,3,2-dioxasilolane-4,5-dione, prepared according to example “synthesis of dimethylsilyl oxalate” of WO2018/033357 from Solvay,

2-methylisothiazolidine- 1,1 -dioxide (CAS 83634-83-7) (Parchem, USA)

4-fluoro-l,

3.2-dioxathiolane-2, 2-dioxide (CAS 23910-98-7) prepared according to example 2 of CN105541789,

(2-oxo- l,3-dioxolan-4-yl)-2,2-difluoromethylacetate (CAS 1337958-06-1), prepared according to example 2 of US8735005,

1.3-Propanedisulfonyl difluoride (CAS 110073-91-1) prepared according to Journal of Fluorine Chemistry, 1997, vol. 83, # 2, p. 145-149,

3-Fluoro-2,5-furandione (CAS 2714-23-0) (Angene, UK)

3.4-Diffluoro-2,5-furandione (CAS 669-78-3) (Carbosynth)

Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC), all battery grade, were purchased at ENchem. Lithium hexafluorophosphate (LiPFr,), battery grade, was purchased at ENchem. 4-fluoro-l, 3-dioxolane-2-one (FEC), battery grade, was purchased at Solvay. 2,2-difluoroethyl acetate (DFEA) was purchased at Solvay. 4,5-difluoro-l,3-dioxolane-2-one, battery grade, was provided by Solvay. ft was obtained by a fluorination process of ethylene carbonate such as described in EP 2483231.

Electrolyte compositions are prepared by first mixing the solvents EC, EMC, DMC in their respective volume ratios EC/EMC/DMC (2:2:6) and dissolving the lithium salt LiPF ₆ in the appropriate amount to yield 1.5 M composition. Compound obtained from example 1 is added to each electrolyte composition in an amount of 2% (For each electrolyte composition prepared, the amount of added compound is given in weight relative to the total weight of the composition). Other electrolyte compositions are prepared in the same manner but by adding further at least one of the compounds C in an amount of 2% in weight relative to the total weight of the composition. As the results of moisture measurement, the moisture content of all the electrolytes compositions is under 10 mg/kg of composition (Karl Fisher method).

Preparation of the pouch cells

Pouch cells are purchased from Pred Materials (New York, N.Y.) and are 600 mAh cells containing an NMC 532 cathode and a graphitic anode.

Before use, the pouch cells are dried in the antechamber of a dry box under vacuum 4 days at 55°C and vacuum -lOOkPa. Approximately 2.0 gram of electrolyte composition is injected through the bottom, and the bottom edge sealed in a vacuum sealer. For each example, two pouch cells are prepared using the same electrolyte composition.

Pouch cells Assembly and Formation

The cells are held in an environmental chamber (model BTU-433, Espec North America, Hudsonville, Michigan) and evaluated using a battery tester (Series 4000, Maccor, Tulsa, OK) for the formation procedures (at 25 °C, 60 °C) and the high temperature cycling (at 45 °C).

The pouch cells are conditioned using the following cycling procedure ln a first cycle, the cell is charged for 3 hours at 0.1 C, corresponding to approximately 30 % state of charge; this is followed by 24 hour rest at 60 °C. The pouch cell is degassed and resealed in a vacuum sealer. The cell is pressed using hot press at 70 °C during 3 sec.

For the second cycle, the cell is charged at constant current (CC charge) of 0.5 C to 4.35 V followed by a CV voltage-hold step at 4.35 V until current dropped below 0.05C and rested lOmin. This is followed by a CC discharge at 0.5C to 3.0 V and rested lOmin. This cycle is repeated 3 times and it is used as a check of the capacity of the cell.

The final step for formation of pouch cell is charged at constant current (CC charge) of 0.5C to SOC30.

For the 25 °C cycles and the 45 °C cycling described below, the cells also have a 10 min rest following each charge and each discharge step.

Cycling method

The cells are placed in an environmental chamber at 25°C and 45 °C and cycled: CC charge 1C to 4.35 V and CV charge to 0.05C, and CC discharge at 1C to 3.0 V.

Storage procedure

The cells are placed in an environmental chamber at 70 °C with SOC 100, CC charge 1C to 4.35 V and CV charge to 0.05C, initial thickness checked. After 1 week later, they are put out from oven, the thickness is measured by Vernier calipers, the residual and recovery capacity is measured with CC discharge at 1C to 3.0V, and DC-IR is checked.

Ionic conductivity measure procedure

The electrolytes are measured by LCR meter in temperature control chamber at -20°C even 60°C.

Results

The tests show that the cells containing the electrolyte compositions according to the invention comprising at least one compound selected from those of formulae (V) optionally in combination with at least one compound selected from those of formulae (VIII) to (XVII) have improved performance characteristics, especially regarding quality of the solid electrolyte interphase (SEI) formed on the electrodes surface, chemical stability, ionic conductivity, thermal stability, reversible capacity, cycle characteristics and/or gas generation.