(2-cyanoethyl) phosphonium salt-based electrolyte composition, and battery comprising same

Abstract

The present invention relates to a (2-cyanoethyl) phosphonium salt-based electrolyte composition and to the battery comprising same. More particularly, the present invention relates to an improved electrolyte composition for a lithium-ion or sodium-ion battery leading to improved capacity and cyclability. The electrolyte composition comprises a lithium or sodium salt, an aprotic organic solvent, and a (2-cyanoethyl) phosphonium salt compound.

Description

ELECTROLYTE COMPOSITION BASED ON (2-CYANOETHYL)PHOSPHONIUM SALT AND BATTERY COMPRISING SAME

[0001] The present invention relates to an electrolyte composition based on (2-cyanoethyl)phosphonium salt and the battery comprising it. More particularly, it relates to an improved electrolyte composition for a lithium-ion or sodium-ion battery leading to improved capacity and cyclability. This electrolyte composition comprises a lithium or sodium salt, an aprotic organic solvent, a (2-cyanoethyl)phosphonium salt compound. Field of invention

[0002] An electrochemical battery is assembled from a cathode (positive electrode), an anode (negative electrode), a separator, and an electrolyte. The operating principle is based on the reversible exchange of ions between the cathode and the anode. The anode material is oxidized and the electrolyte components are reduced, and the cathode material is reduced and the electrolyte components are oxidized. Through these redox reactions, a battery is charged by converting electrical energy into chemical energy. The electrolyte plays an important role in transporting ions between the cathode and the anode. Different compounds are used in electrolytes.Some electrolyte compounds degrade and participate in the formation of the solid electrolyte interphase (SEI) and the formation of the cathode electrolyte interphase (CEI) to improve the properties and therefore the performance of the electrochemical cell, including cyclability, coulombic efficiency and capacity.

[0003] Current electrolyte technology uses compounds that do not provide sufficient improvement in the capacity and lifetime of the electrochemical cell.

[0004] The state of the art describes various compounds such as vinylene carbonate (commonly called VC), fluoroethylene carbonate (commonly called FEC), 1,3,6-hexanetricarbonitrile, acetonitrile, siloxanes, sulfates, sulfites, phosphates etc. which do not allow to achieve excellent cyclability i.e. long battery life and excellent capacity while maintaining good electrolyte conductivity. They are not thermally stable and do not allow to be soluble in variable proportions in the electrolyte solvent to adapt to the choice of electrode materials.

[0005] “The Role of Electrolyte Additives on the Interfacial Chemistry and Thermal Reactivity of Si-Anode-Based Li-Ion Battery,” ACS Applied Energy Materials 2019 2 (9), 6513-6527, describes common compounds that, despite their beneficial characteristics, lead to persistent problems. For example, the presence of VC in the electrolyte can lead to excessively high cell impedance. In another example, the presence of FEC in the electrolyte can lead to significant gassing at elevated temperatures and thus a risk of thermal runaway.

[0006] “Classical solid electrolyte interphase additives, such as vinylene carbonate and fluoroethylene carbonate, have limited potential for simultaneously achieving a long lifespan and fast chargeability in high-energy-density lithium-ion batteries (LIBs).” Parket al., 2021, describes the development of new electrolyte compounds for high-energy-density Li-ion batteries. This reference describes the disadvantages of conventional electrolyte compounds such as vinylene carbonate and fluoroethylene carbonate; they do not simultaneously achieve a sufficient lifespan (cyclability) and a sufficiently fast chargeability in high-energy-density lithium-ion batteries.

[0007] Document DE102008021271 describes an electrolyte comprising a mono(2-cyanoethyl)phosphonium salt.

[0008] Document JP2018056013 also describes an electrolyte comprising a mono(2-cyanoethyl)phosphonium salt.

[0009] (2-Cyanoethyl)phosphonium salt compounds are particularly interesting because they are stable up to a temperature of 250 °C; these compounds allow one or other of its members to be chosen to adapt to the nature of the electrode as well as to modulate its solubility in the electrolyte solvent and not to be the cause of an increase in the internal resistance of the electrochemical cell during the SEI and / or IEC formation step. However, mono(2-cyanoethyl)phosphonium compounds have the disadvantage of having to be in higher concentration to achieve the same efficiency over time as bis(2-cyanoethyl)phosphonium compounds or tris(2-cyanoethyl)phosphonium compounds.Indeed, to achieve the same efficiency, it is appropriate to multiply the concentration of mono(2-cyanoethyl)phosphonium whereas when the phosphonium molecule carries two or three 2-cyanoethyl chains, only a lower concentration of molecule is needed. This is important to avoid too high viscosity and therefore avoid a decrease in the conductivity of the electrolyte. There is a need for a thermally stable electrolyte compound, soluble in variable proportions in the electrolyte solvent to meet the need for the choice of electrodes and maintain excellent capacity, excellent cyclability as well as good conductivity and electrochemical stability of the battery.

[0010] The inventors of the present invention have developed a new electrolyte composition for lithium-ion and sodium-ion batteries providing these systems with good cyclability and good capacity.

[0011] According to a first aspect of the invention, the electrolyte composition comprises a (2-cyanoethyl)phosphonium salt of formula (I)

[0012] (I)

[0013] in which

[0014] X- is selected from fluoroalkyl phosphates, fluoroalkyl phosphinates, fluoroalkyl phosphonates, acetates, triflates, imides, amides, methanides, borates, phosphates, sulfonimides or aluminates;

[0015] R1 is independently selected from an unsubstituted -CH2-CH2-CN chain, by a C1-C20 alkyl, a C3-C6 cycloalkyl, a C2-C20 alkenyl, a C5-C8 cycloalkenyl, a C2-C20 alkynyl, a vinylbenzyl group; in which the hydrogen atoms may be substituted by a fluorine, a -CF3, an ether, an alkyl group, a perfluorinated alkyl group, a silyl group, a siloxy group, a sulfoxide group, a nitrile group, a thioether group or combinations thereof;

[0016] R2 is independently selected from a C1-C20 alkyl group, a C3-C6 cycloalkyl group, a C2-C20 alkenyl group, a C5-C8 cycloalkenyl group, a C2-C20 alkynyl group, a vinylbenzyl group; wherein the hydrogen atoms may be substituted by a fluorine, a -CF3, an ether, an alkyl group, a perfluorinated alkyl group, a silyl group, a siloxy group, a sulfoxide group, a nitrile group, a thioether group or combinations thereof.

[0017] According to a second aspect, the invention relates to a battery comprising an anode, a cathode and an electrolyte composition based on a (2-cyanoethyl)phosphonium salt compound as represented by formula (I). Advantages of the invention

[0018] The invention proposes a new family of electrolyte compositions for batteries based on phosphonium salt. These compositions make it possible to have an electrolyte that will be used in a battery with good cyclability and capacity. This leads to obtaining a high-performance and durable battery.

[0019] This new family of electrolyte compositions has several advantages.

[0020] First, the electrolyte compounds in this family combine the properties of nitrile present at least twice within the molecule and that of the phosphorus atom which allows better transport of Li+ ions. The molar ratio of the compound as a function of the number of nitrile functions carried by the compound is also improved. Indeed, the more nitrile functions there are in the compound, the less it will be necessary to increase the mass of the added compound; each compound has an optimum concentration for which the conductivity is maximum. The concentration will be lower and the conductivity will thus be improved.

[0021] The nitrile function adds specific polarity and reactivity. This also influences other physical properties such as dipole moment and dielectric constant. In addition, the nitrile function adds solvation properties to the phosphonium cations intra- and intermolecularly, which improves the mobility of Li ions. + .

[0022] Second, the (2-cyanoethyl)phosphonium salt is thermally stable up to 250 °C. This allows it on the one hand not to decompose into by-products that could be unfavorable to the good performance of the battery. On the other hand, the nitrile chemical function allows it to participate in the formation of the SEI and CEI in a sacrificial way to preserve the chemical properties of the other electrolyte compounds in order to obtain a stable and efficient SEI for the good performance of the battery. This compound makes it possible to form an SEI at a temperature of 45 °C.

[0023] Third, the compound is soluble in the electrolyte solvent in varying proportions to meet the need to adapt to the nature of the electrode materials. Indeed, this compound, by its ionic nature, is soluble in a proportion necessary for the type of electrode chosen.

[0024] This new family of electrolyte compositions makes it possible to meet this need.

[0025] Fourthly, a large number of electrolyte molecules are accessible by replacing the R1 and R2 radicals, which makes it possible to have the molecule most suited to the electrochemical system, particularly with regard to the choice of electrodes and to achieve a high voltage.

[0026] Fifth, the process of synthesizing electrolyte compounds of this family of compositions is industrializable.

[0027] The battery has a high capacity and a long cyclability due to the nature of the electrolyte salts, namely the presence of the phosphorus atom and the presence of at least two 2-cyanoethyl chains, the electrolyte molecule being in monomeric or dimeric form. The dimer being a homodimer, the nature of the chemical substitution remaining the same, the monomer and the dimer will have similar chemical properties.

[0028] The preferred compounds are bis(2-cyanoethyl)phosphonium and tris(2-cyanoethyl)phosphonium compounds. Detailed description of the invention

[0029] A first subject of the invention relates to an electrolyte composition comprising a Lithium salt or a Sodium salt, an aprotic organic solvent and an electrolyte compound, wherein said electrolyte compound comprises a (2-cyanoethyl)phosphonium salt as represented by formula (I):

[0030] (I)

[0031] in which

[0032] X- is selected from fluoroalkyl phosphates, fluoroalkyl phosphinates, fluoroalkyl phosphonates, acetates, triflates, imides, amides, methanides, borates, phosphates, sulfonimides or aluminates;

[0033] R1 is independently selected from the group consisting of an unsubstituted -CH2-CH2-CN chain, a C1-C20 alkyl, a C3-C6 cycloalkyl, a C2-C20 alkenyl, a C5-C8 cycloalkenyl, a C2-C20 alkynyl, a vinylbenzyl group; wherein the hydrogen atoms may be substituted by a fluorine, a -CF3, an ether, an alkyl group, a fluorinated alkyl group, a silyl group, a siloxy group, a sulfoxide group, a nitrile group, a thioether group or combinations thereof.

[0034] R2 is independently selected from the group consisting of a C1-C20 alkyl group, a C3-C6 cycloalkyl group, a C2-C20 alkenyl group, a C5-C8 cycloalkenyl group, a C2-C20 alkynyl group, a vinylbenzyl group; wherein the hydrogen atoms may be substituted by a fluorine, a -CF3, an ether, an alkyl group, a perfluorinated alkyl group, a silyl group, a siloxy group, a sulfoxide group, a nitrile group, a thioether group or combinations thereof.

[0035] Hydrogen atoms can therefore be partially substituted as long as the molecule is stable.

[0036] The term "alkyl" means a saturated, straight or branched aliphatic radical having the indicated number of carbon atoms. The alkyl moiety may be straight or branched chain

[0037] The term "alkenyl" means an alkyl group, as defined above, comprising at least one C=C double bond.

[0038] The term "alkynyl" means an alkyl group, as defined above, comprising at least one C≡C triple bond.

[0039] The term "cycloalkyl" refers to a collection of saturated or partially unsaturated rings, whether monocyclic, bicyclic, bridged polycyclic, or spiro. Monocyclic rings include, for example, cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl rings.

[0040] In a particularly preferred embodiment, the (2-cyanoethyl)phosphonium salt comprises three 2-cyanoethyl chains and corresponds to formula (II) in which

[0041] X- is selected from fluoroalkyl phosphates, fluoroalkyl phosphinates, fluoroalkyl phosphonates, acetates, triflates, imides, amides, methanides, borates, phosphates, sulfonimides or aluminates;

[0042] R1 is independently selected from C1-C20 alkyl, C3-C6 cycloalkyl, C2-C20 alkenyl, C5-C8 cycloalkenyl, C2-C20 alkynyl, vinylbenzyl; wherein the hydrogen atoms may be substituted by fluorine, -CF3, ether, alkyl, perfluorinated alkyl, silyl, siloxy, sulfoxide, nitrile, thioether or combinations thereof.

[0043] R2 is independently selected from a C1-C20 alkyl group, a C3-C6 cycloalkyl group, a C2-C20 alkenyl group, a C5-C8 cycloalkenyl group, a C2-C20 alkynyl group, a vinylbenzyl group; wherein the hydrogen atoms may be substituted by a fluorine, a -CF3, an ether, an alkyl group, a perfluorinated alkyl group, a silyl group, a siloxy group, a sulfoxide group, a nitrile group, a thioether group or combinations thereof.

[0044] In a more particularly preferred embodiment, R1 is a C1-C10 alkyl in which the hydrogen atoms may be substituted by a fluorine, a -CF3, an ether, an alkyl group, a perfluorinated alkyl group, a silyl group, a siloxy group, a nitrile group, a sulfoxide group, a thioether group or combinations thereof;

[0045] Even more preferably, R1 is selected from methyl or C1-C4 alkyl in which the hydrogen atoms may be substituted by fluorine, -CF3, ether, alkyl group, perfluorinated alkyl group, silyl group, siloxy group, nitrile group, sulfoxide group, thioether group or combinations thereof; and R2 is C1-C10 alkyl in which the hydrogen atoms may be substituted by fluorine, -CF3, ether, alkyl group, perfluorinated alkyl group, silyl group, siloxy group, sulfoxide group, nitrile group, thioether group or combinations thereof;and more preferably R2 is a C1-C4 alkyl in which the hydrogen atoms may be substituted by a fluorine, a -CF3, an ether, an alkyl group, a perfluorinated alkyl group, a silyl group, a siloxy group, a nitrile group, a sulfoxide group, a thioether group or combinations thereof and most preferably among a methyl, an ethyl, a propyl, an iso-butyl, an n-butyl, or an allyl.;

[0046] In a preferred embodiment, difluorobis(oxalato)borate, acetate., N-ethyl-N-methyl-functionalized sulfonimide, (difluoromethanesulfonyl)(trifluoromethanesulfonyl)imide, (methanesulfonyl)(trifluoromethanesulfonyl)imide, (difluoromethanesulfonyl)(fluoromethanesulfonyl)imide, (methanesulfonyl)(fluoromethanesulfonyl)imide.

[0047] In an even more preferred embodiment, X- is selected from FSI or TFSI.

[0048] Preferred embodiments as to the choice of anion X - set out above can be combined with the preferred embodiments as to the choice of groups R1 and R2 set out previously.

[0049] In a preferred embodiment, the (2-cyanoethyl)phosphonium salt comprises three 2-cyanoethyl chains and corresponds to formula (II)

[0050] (II)

[0051] in which

[0052] X- is selected from fluoroalkyl phosphates, fluoroalkyl phosphinates, fluoroalkyl phosphonates, acetates, triflates, imides, amides, methanides, borates, phosphates, sulfonimides or aluminates;

[0053] R2 is independently selected from a C1-C20 alkyl group, a C3-C6 cycloalkyl group, a C2-C20 alkenyl group, a C5-C8 cycloalkenyl group, a C2-C20 alkynyl group, a vinylbenzyl group; wherein the hydrogen atoms may be substituted by a fluorine, a -CF3, an ether, an alkyl group, a perfluorinated alkyl group, a silyl group, a siloxy group, a sulfoxide group, a nitrile group, a thioether group or combinations thereof.

[0054] In a preferred embodiment, R2 is C1-C10 alkyl in which the hydrogen atoms may be substituted by fluorine, -CF3, ether, alkyl group, perfluorinated alkyl group, silyl group, siloxy, sulfoxide group, nitrile group, thioether group or combinations thereof; more preferably R2 is selected from C1-C4 alkyl in which the hydrogen atoms may be substituted by fluorine, -CF3, ether, alkyl group, perfluorinated alkyl group, silyl group, siloxy group, sulfoxide group, nitrile group, thioether group or combinations thereof; most preferably R2 is chosen from methyl, ethyl, propyl, isobutyl, n-butyl or allyl.

[0055] In a preferred embodiment, difluorobis(oxalato)borate, acetate.N-ethyl-N-methyl-functionalized sulfonimide, (difluoromethanesulfonyl)(trifluoromethanesulfonyl)imide, (methanesulfonyl)(trifluoromethanesulfonyl)imide, (difluoromethanesulfonyl)(fluoromethanesulfonyl)imide, (methanesulfonyl)(fluoromethanesulfonyl)imide.

[0056] In an even more preferred embodiment, X- is selected from FSI or TFSI.

[0057] Preferred embodiments as to the choice of anion X - set out above can be combined with the preferred embodiments as to the choice of groups R1 and R2 set out previously.

[0058] In a particular embodiment the (2-cyanoethyl)phosphonium salt is in the form of a phosphonium salt dimer as represented by formula (III),

[0059] (III)

[0060] in which

[0061] Z is chosen from C1-C20 alkyl di-radicals of the type –(CH2) n – which may comprise one or more ethers or which may comprise one or more chains of the type –CH2–Y–CH2– with Y=S or SO or SO2; preferably the alkyl diradical is an ethyl, propyl, butyl or pentyl diradical.

[0062] X- is selected from fluoroalkyl phosphates, fluoroalkyl phosphinates, fluoroalkyl phosphonates, acetates, triflates, imides, amides, methanides, borates, phosphates, sulfonimides or aluminates;

[0063] R2 is independently selected from the group consisting of unsubstituted -CH2-CH2-CN, C1-C20 alkyl, C3-C6 cycloalkyl, C2-C20 alkenyl, C5-C8 cycloalkenyl, C2-C20 alkynyl, vinylbenzyl, vinylbenzyl; wherein the hydrogen atoms may be substituted by fluorine, -CF3, ether, alkyl, perfluorinated alkyl, silyl, siloxy, sulfoxide, nitrile, thioether, or combinations thereof.

[0064] In a more particularly preferred embodiment, R2 is a C1-C10 alkyl in which the hydrogen atoms may be substituted by a fluorine, a -CF3, an ether, an alkyl group, a perfluorinated alkyl group, a silyl group, a siloxy group, a sulfoxide group, a thioether group or combinations thereof.

[0065] Even more preferably, R2 is chosen from a methyl or a C1-C4 alkyl in which the hydrogen atoms may be substituted by a fluorine, a -CF3, an ether, an alkyl group, a perfluorinated alkyl group, a silyl group, a siloxy group, a sulfoxide group, a thioether group or combinations thereof.

[0066] In a preferred embodiment, difluorobis(oxalato)borate, acetate.N-ethyl-N-methyl-functionalized sulfonimide, (difluoromethanesulfonyl)(trifluoromethanesulfonyl)imide, (methanesulfonyl)(trifluoromethanesulfonyl)imide, (difluoromethanesulfonyl)(fluoromethanesulfonyl)imide, (methanesulfonyl)(fluoromethanesulfonyl)imide.

[0067] In an even more preferred embodiment, X- is selected from FSI or TFSI.

[0068] Preferred embodiments as to the choice of anion X - set out above can be combined with the preferred embodiments as to the choice of R2 groups set out previously.

[0069] The invention therefore relates to an electrolyte composition comprising a lithium or sodium salt, an aprotic organic solvent and a (2-cyanoethyl)phosphonium salt compound as described above.

[0070] According to a preferred embodiment, the aprotic organic solvent is selected from an ionic liquid, a carbonate, a glyme, an alkyl sulfonamide or a mixture thereof.

[0071] In a preferred embodiment, the solvent is an ionic liquid.

[0072] As used herein, "ionic liquid" means a molten salt at a temperature below 100°C.

[0073] When the solvent is an ionic liquid, it comprises (i) a cation selected from an imidazolium, or a pyrrolidinium, a morpholinium, a pyridinium, a piperidinium, a phosphonium, an ammonium and (ii) an anion selected from hexafluorophosphate (PF6-), tetrafluoroborate (BF4-), bis(trifluoromethanesulfonyl)imide (TFSI), bis(fluorosulfonyl)imide (FSI), dicyanamide (DCA), 4,5-dicyano-2-(trifluoromethyl)imidazolide (TDI), fluorosulfonyl-(trifluoromethanesulfonyl)imide (FTFSI), (difluoromethanesulfonyl)(trifluoromethanesulfonyl)imide (DFTFSI), bis(oxalato)borate (BOB), difluoro(oxalato)borate (DFOB).

[0074] In a preferred embodiment, the selected ionic liquids are of high quality [purity 99.9%; H2O ≤ 5 ppm; halides ≤ 1 ppm; lithium, sodium and potassium ≤ 10 ppm; organic nitrogen compounds ≤ 10 ppm; 20-10 Hazen color test].

[0075] In a preferred embodiment, the electrolyte composition comprises at least 30% ionic liquid, in particular at least 50% ionic liquid and preferably at least 70% ionic liquid.

[0076] Phophonium salts according to the invention are described in the experimental part: P1(2CN)3FSI, P14(2CN)2FSI, P13(2CN)2FSI, P14(2CN)2FSI and Pbutene(2CN)3FSI.

[0077] A second subject of the invention is a battery comprising a cathode, an anode, a separator and the electrolyte comprising a (2-cyanoethyl)phosphonium salt compound as described above.

[0078] In a particular embodiment, the battery according to the invention can provide an energy density greater than 350 Wh / kg when the electrolyte is composed of ionic liquid and the (2-cyanoethyl)phosphonium salt compound. Indeed, the compound is compatible with the performances of ionic liquids such as non-flammability, high voltage and use with high temperatures.

[0079] The active material for the cathode is selected from: For a Lithium-ion battery: a lithium intercalating compound, selected from lithium-iron phosphate, (LiFePO4), lithium-nickel-manganese-cobalt oxide, (LiNixMnyCozO2), doped lithium-nickel-manganese-cobalt oxide, (LiNixMnyCozO2), lithium-cobalt oxide (LiCoO2), doped lithium-cobalt oxide, lithium-nickel oxide (LiNiO2), doped lithium-nickel oxide, lithium-manganese oxide (LiMn2O4), doped lithium-manganese oxide, NCA, lithium-vanadium oxide, doped lithium-vanadium oxide, lithium and mixed metal oxides, Lithium Manganese Nickel Oxide (LMNO), lithium and transition metal oxides mixed, doped lithium and mixed transition metal oxides (NCA, LMNX,), lithium vanadium phosphate, lithium manganese phosphate, lithium cobalt phosphate, lithium and mixed metal phosphates, metal sulfides and their combinations.For a Sodium-ion battery: a metal oxide such as VO2, V2O5, H2V3O8, b- MnO2;.

[0080] layered NaMOX such as Na0.71CoO2, Na0.7MnO2, b-NaMnO2, Na1.1V3O7.9, Na2RuO3, Na2 / 3[Ni1 / 3Mn2 / 3]O2, Na0.67Co0.5Mn0.5O2, Na0.66Li0.18Mn0.71Ni0.21Co0.08O2+x; 1D tunnel oxides such as Na0.44MnO2, Na0.66[Mn0.66Ti0.34]O2, Na0.61[Mn0.27Fe0.34Ti0.39]O2; fluorides such as FeO0.7F1.3 and NaFeF3; sulfates such as Na2Fe2(SO4)3 and Eldfellite NaFe(SO4)2; phosphates NaFePO4 and FePO4 ; Na3V2(PO4)3, Na3V2(PO4)3, Na3V2(PO4)3@C@rGO, Na3V2(PO4)3 / C, NaVOPO4; pyrophosphates such as Na2CoP2O7, Na2FeP2O7 and Na3.12Fe2.44(P2O7)2;

[0081] fluorophosphates such as NaVPO4F, Na3V2(PO4)2F3, Na3V2O2(PO4)2F@RuO2, Na3(VO1-xPO4)2F1+2x, Na3.5V2(PO4)2F3; mixed phosphates such as Na7V4(P2O7)4(PO4), Na3MnPO4CO3; hexacyanometalates such as MnHCMn PBAs, Na1.32Mn[Fe(CN)6]0.83.3.5H2O, NaxCo[Fe(CN)6]0.90·2.9H2O; critical metal-free cathodes such as Na2C6O6, Na6C6O6, SSDC, C6Cl4O2 / CMK, PTCDA-PI, poly(anthraquinonyl imide)s and functionalized graphite; Prussian white analogs; analogues of Prussian blue.

[0082] The active material for the anode is selected from:For a Lithium-ion battery:a lithium-containing titanium composite oxide (LTO);mixture of niobium oxides (XNO) of metals (Me) such as Si, Sn, Li, Zn, Mg, Cd, Ce, Ni and Fe or alloys thereof;graphite, graphene, including particles of natural graphite, artificial graphite, meso-carbon microbeads (MCMB) and carbon (including soft carbon, hard carbon, carbon nanofibers and carbon nanotubes);silicon (Si), silicon / graphite composites, silicon combinations of germanium (Ge), tin (Sn), lead (Pb), antimony (Sb), bismuth (Bi), zinc (Zn), aluminum (Al), nickel (Ni), cobalt (Co), manganese (Mn), titanium (Ti), iron (Fe) and cadmium (Cd); alloys or intermetallic compounds of Si, Ge, Sn, Pb, Sb, Bi, Zn, Al or Cd with other elements, said alloys or compounds being stoichiometric or non-stoichiometric;oxides, carbides, nitrides, sulfides, phosphides, selenides and tellurides of Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, Fe, Ni, Co, Ti, Mn or Cd, and their mixtures or composites; oxides (MeOx) of metals (Me); composites of metals (Me) with carbon; MXene materials, [M; xC where X = 2,3,4). For a sodium-ion battery: oxide, sulfide, selenide, phosphide and MOF-based materials and carbon-based materials; carbon-based materials include expanded graphite, N-doped expanded graphite, carbon black, amorphous carbon, carbon microspheres, hard carbon, meso-strong soft carbon, carbon nanotubes, graphene nanosheets, nitrogen-doped CNTs, N-doped graphene foam, N-doped porous nanofibers, microporous carbon and cube-shaped porous carbon;oxides include MnO2 nanoflowers, NiO nanosheets, porous SnO, porous SnO2 nanotubes, porous 3D Fe3O4–C, porous CuO-RGO, ultrasmall nitrogen-doped MnO-CNTs, CuS microflowers, SnS2-RGO, Co3S4-PANI, ZnS-RGO, NiS-RGO, Co3S4-PANI, MoS2–C, nitrogen-doped WS2-conductive carbon nanosheets, Sb3Se3-RGO nanorods, MoSe2-carbon fiber, multi-shell Sn4P3 nanostructures, Sn4P3–C nanospheres, Se4P4, CoP nanoparticles, FeP nanorod arrays on carbon fabric, MoP-C, CUP2-C, hollow NiO / Ni graphene, nitrogen-doped yellow-shell structured CoSe / C; Na metal;

[0083] In a preferred embodiment, for Lithium-ion and Sodium-ion batteries, when the cathode is Lithium Manganese Nickel Oxide (LMNO) then the anode is graphite or Lithium Titanate (LTO); when the cathode is Nickel Manganese Cobalt 532 (NMC532) then the anode is graphite; when the cathode is Nickel Manganese Cobalt 622 (NMC622) then the anode is graphite; when the cathode is Nickel Manganese Cobalt 811 (NMC811) then the anode is graphite when the cathode is Lithium Iron Phosphate (LFP) then the anode is graphite; when the cathode is Lithium Iron Phosphate (LFP) then the anode is graphite.

[0084] Separators can be made of:

[0085] - a microporous polymer membrane which is a semi-crystalline polyolefin such as polyethylene (PE), polypropylene (PP), high density polyethylene (HDPE), PE-PP, PS-PP, polyethylene terephthalate-polypropylene blends (PET-PP), polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN); polyoxymethylene, poly(4-methyl-1-pentene); nonwoven fabric mats such as cellulose, polyolefin, polyamide, polytetrafluoroethylene (PTFE), polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP), polyvinyl chloride (PVC), polyester. Other types of polymers are polyolefin-based materials and their blends such as polyethylene-polypropylene. Grafted polymers such as siloxane-grafted polyethylene separators, poly(methylmethacrylate)-grafted microporous separators. Polyvinylidene fluoride (PVDF) nanofiber webs. Polytriphenylamine (PTPAn) modified separator.Polymer electrolytes such as ionic polymer electrolytes.

[0086] Examples of such ionic polymers are compounds formed from, for example, poly(diallyldimethylammonium) with an anion selected from hexafluorophosphate (PF6-), tetrafluoroborate (BF4-), bis(trifluoromethanesulfonyl)imide (TFSI), bis(fluorosulfonyl)imide (FSI), dicyanamide (DCA), 4,5-dicyano-2-(trifluoromethyl)imidazolide (TDI), fluorosulfonyl-(trifluoromethanesulfonyl)imide (FTFSI) and (difluoromethanesulfonyl) (trifluoromethanesulfonyl)imide (DFTFSI), bis(oxalato)borate (BOB), difluoro(oxalato)borate (DFOB).

[0087] - Ionic liquid polymers with additional ionic liquids (or without), mixed polymer / copolymer electrolytes of polyethylene oxide (PEO), polyvinylpyrrolidone, polyethylene oxide, polyacrylonitrile, polyethylene glycols, glymes, fluorinated polymers to any other combination of polymer electrolytes and ionic liquids or to a combination of ionic liquids and ionic liquid polymer.

[0088] - Polymerizable ionic liquid;

[0089] - Inorganic composite separator such as metal oxide powders (TiO2, ZrO2, LiAlO2, Al2O3, MgO, CaCO3) in a polymer matrix (PVDF-HFP, PTFE), AlO(OH) / polyvinyl alcohol (PVA) on PET; ceramic separators such as alumina or ceramic particles mixed with polymers or a combination of polymers and / or ionic liquids; surface-coated polymer such as a gel-like polymer film (PEO, PVDF-HFP) on microporous membranes; impregnation of a gel-like polymer electrolyte such as an ionic liquid-based electrolyte into microporous membranes; glass fibers; conductive glass separators. The separators may also comprise solid-state electrolytes such as solid ceramic electrolytes and solid polymer electrolytes.

[0090] In a preferred embodiment, the battery comprises an electrolyte composition comprising an ionic liquid solvent and the (2-cyanoethyl)phosphonium salt compound described in formulas (I), (II) or (III) as well as a cathode of Lithium Manganese Nickel Oxide (LMNO) material.

[0091] In a particular embodiment, the battery comprises a cathode, an electrolyte as described above and a separator.

[0092] In a particular embodiment, the battery comprises a separator and an electrolyte which are identical. This is particularly the case when the electrolyte is solid because it also acts as a separator. BRIEF DESCRIPTION OF THE FIGURES

[0093] : Graph showing the charge / discharge profiles of the cell (LMNO / Graphite) at charge and discharge rates of 0.1 C and the 10th, 100th, 250th and 450th cycles at 0.5 C from 2 V to 5 V versus Li+ / Li for the electrolyte 1 M LiFSI in PYR13FSI + 0.063 mol / kg of Tris(2-cyanoethyl)methylphosphonium bis(fluorosulfonyl)imide (P1(2CN)3FSI) at 20 °C.

[0094] : Graph showing the charge / discharge profiles of the cell (LMNO / Graphite) at charge and discharge rates of 0.1 C and the 10th and 47th cycles at 0.5 C from 2 V to 5 V versus Li+ / Li for 1 M LiFSI electrolyte in PYR13FSI at 20 °C.

[0095] : Graph showing discharge capacities and coulombic efficiencies versus cycle number for whole cells (LMNO / Graphite) with and without Tris(2-cyanoethyl)methylphosphonium bis(fluorosulfonyl)imide (P1(2CN)3FSI) compound at a charge and discharge rate of 0.5 C from 2 V to 5 V versus Li+ / Li at 20 °C.

[0096] : Graph showing the charge / discharge profiles of the cell (LMNO / Graphite) at charge and discharge rates of 0.1 C and the 10th, 50th, 150th and 274th cycles at 0.5 C from 2 V to 5 V versus Li+ / Li for the electrolyte 1M LiFSI in PYR13FSI + 0.063 mol / kg of Bis(2-cyanoethyl)butylmethylphosphonium bis(fluorosulfonyl)imide (P14(2CN)2FSI) at 20 °C.

[0097] : Graph showing the charge / discharge profiles of the battery (LMNO / Graphite) at charge and discharge rates of 0.1 C and the 10 ème , 50 ème , 150 ème and 247 èmecycles at 0.5 C from 2 V to 5 V versus Li+ / Li for 1M LiFSI electrolyte in PYR13FSI at 20 °C.

[0098] :Graph showing discharge capacities and coulombic efficiencies versus cycle number for whole cells (LMNO / Graphite) with and without Bis(2-cyanoethyl)butylmethylphosphoniumbis(fluorosulfonyl)imide(P14(2CN)2FSI) compound at a charge and discharge rate of 0.5 C between 2V and 5V versus Li+ / Li at 20 °C.

[0099] : Graph showing the charge / discharge profiles of the battery (LMNO / LTO) at charge and discharge rates of 0.05 C, 0.2 C and 0.5 C from 1.2 V to 3.5 V compared to Li + / Li for the electrolyte 1M LiFSI in PYR13FSI + 0.126 mol / kg Bis(2-cyanoethyl)propylmethylphosphonium bis(fluorosulfonyl)imide (P13(2CN)2FSI) at 20 °C.

[0100] : Graph showing the charge / discharge profiles of the battery (LMNO / LTO) at charge and discharge rates of 0.05 C, 0.2 C and 0.5 C from 1.2 V to 3.5 V compared to Li + / Li for 1M LiFSI electrolyte in PYR13FSI at 20°C.

[0101] : Graph showing discharge capacities and coulombic efficiencies as a function of cycle number for whole cells (LMNO / LTO) with and without Bis(2-cyanoethyl)propylmethylphosphonium bis(fluorosulfonyl)imide (P13(2CN)2FSI) compound at different charge and discharge rates from 1.2 V to 3.5 V versus Li + / Li at 20°C.

[0102] : Graph showing discharge capacities and coulombic efficiencies as a function of cycle number for whole cells (NMC622 / Gr) with and without P14(2CN)2FSI compound at different charge and discharge rates from 2 V to 4.2 V versus Li+ / Li at room temperature (RT).

[0103] : Graph showing discharge capacities and coulombic efficiencies as a function of cycle number for whole cells (NMC622 / Gr) with and without Bis(2-cyanoethyl)butylmethylphosphonium bis(fluorosulfonyl)imide (P14(2CN)2FSI) compound at long C / 2 cycling from 2 V to 4.2 V versus Li+ / Li at room temperature (RT).

[0104] : Graph showing discharge capacities and coulombic efficiencies as a function of cycle number for whole cells (NMC532 / Graphite) with and without bis(2-cyanoethyl)ethylmethylphosphonium bis(fluorosulfonyl)imide compound

[0105] (P12(2CN)2FSI) at different charge and discharge rates between 2.5 V to 4.2 V versus Li+ / Li at 45 °C.

[0106] : Graph showing the charge / discharge profiles of the battery (LMNO / Graphite) at a C rate of 0.5C from 3.5 V to 5 V versus Li+ / Li for the electrolyte 3M LiFSI in N1113FSI + 0.0105 mol / kg Pbutene(2CN)3FSI at 25°C.

[0107] : Graph showing the discharge capacities and coulombic efficiencies of a whole cell (LMNO / Graphite) with Pbutene(2CN)3FSI at a C rate of C / 2 between 3.5V to 5V versus Li+ / Li at 25°C.

[0108] : Graph showing the discharge capacities of a whole cell (LMNO / Lithium metal) with P14(2CN)2FSI at a C rate of C / 2 between 3.5V to 5V versus Li+ / Li at 25°C.

[0109] : Graph showing the charge and discharge capacities of a whole cell (Prussian Blue / Hard Carbon) with P14(2CN)2FSI at C rates of 0.05C, 0.1C and 0.14C between 2V and 4V versus Na+ / Na at 25°C. EXAMPLES

[0110] EXAMPLE 1: Preparation of electrolyte and button batteries

[0111] In a glove box under an inert atmosphere (Argon) with water and O2 contents below 1 ppm, the metal salt is dissolved in an aprotic organic solvent at a desired concentration. One or more compounds are then added and mixed to obtain a homogeneous electrolyte solution.

[0112] Complete button cells (CR2032) are assembled in a glove box under argon atmosphere with contents of less than 1 ppm in O2 and H2O. The electrodes used are commercial and they were purchased already coated on the current collectors (aluminum and copper). They have capacities between 1 and 4 mAh / cm 2 and are cut into discs of 13 mm diameter.

[0113] The electrodes are separated by a 16 mm diameter separator with a thickness between 11 and 180 µm, which can be made of different materials. The separator is then soaked in electrolyte. The button cells were then sealed by a button cell crimping instrument to obtain a battery before performing the electrochemical characterizations.

[0114] Electrochemical impedance spectroscopy (EIS) and galvanostatic cycling measurements were performed using a VMP3 potentiostat (BioLogic) and a multi-channel battery cycler (Arbin Inc). Impedance (EIS) measurements were performed on two-electrode cells at open-circuit bias by applying a 10 mV RMS sine wave at frequencies ranging from 1 MHz to 10 mHz.

[0115] Galvanostatic cycling is achieved by charging and discharging the cells at different constant currents at the maximum and minimum cut-off voltages specific to the different combinations of active materials.

[0116] The impedances and galvanostatic cycling were carried out in a climatic chamber maintaining a constant temperature of 20°C.

[0117] EXAMPLE 2: PREPARATION OF AN LMNO / Graphite BATTERY WITH AND WITHOUT COMPOUND [P1(2CN)3FSI] and CHARGING AND DISCHARGING THE BATTERY

[0118] In a glove box under inert atmosphere (Argon) with water and O2 content less than 1 ppm, the lithium salt LiFSI (0.936 g) is dissolved in the ionic liquid PYR13FSI (6.045 g) to obtain the desired concentration, the compound (2-cyanoethyl)phosphonium P1(2CN)3FSI (0.170 g) is then added and mixed to obtain a homogeneous electrolyte solution.

[0119] The batteries were prepared according to the method described in Example 1. Table 1 below lists the different cathode / anode / electrolyte combinations tested in the battery.

[0120]

[0121] Table 1: LMNO cathode / Graphite anode / electrolyte combinations tested in battery.

[0122] The batteries were tested by galvanostatic cycling from 2 to 5 V at different C rates: 0.1 C and 0.5 C in a climatic chamber at 20 °C.

[0123] The, in which the electrolyte contains the compound P1(2CN)3FSI, shows a discharge capacity loss of 7% between 0.1C and 0.5C respectively 114.54 mAh / g and 106.33 mAh / g. As the charge and discharge rate increases, the polarization between charge and discharge increases. For cycling at 0.5 C, the discharge capacity loss in 450 cycles is 18.5% (from 114.54 to 93.30 mAh / g).

[0124] The, in which the electrolyte does not contain the compound P1(2CN)3FSI shows a discharge capacity loss of 38% between 0.1 C and 0.5 C respectively 118.54 mAh / g and 73.22 mAh / g. For charges and discharges at a rate of 0.5 C, the profiles differ slightly from those of 0.1 C. Indeed, the transition plateaus are less well defined, more particularly that of 4.56 V.

[0125] Comparing the charge / discharge profiles of the two systems, those containing the (2-cyanoethyl)phosphonium compound are more stable.

[0126]

[0127] Table 2: Characteristics of batteries with an LMNO / Graphite system at 0.5 C with and without (2-cyanoethyl)phosphonium compound.

[0128] Table 2 and show the discharge capacity as a function of the number of cycles of the two systems, with and without (2-cyanoethyl)phosphonium salt compound, as well as their coulombic efficiencies.

[0129] Without the (2-cyanoethyl)phosphonium salt compound, the battery discharge capacity decreases from the first cycles for charge and discharge rates of 0.5 C unlike the system containing the (2-cyanoethyl)phosphonium compound for which the capacity remains stable longer, 12% capacity loss in 450 cycles (106.23mAh / g to 93.39mAh / g) at 100% DoD. The coulombic efficiency is also higher for the electrolyte containing the (2-cyanoethyl)phosphonium, it is close to 99.9% compared to 99.2% without it.

[0130] EXAMPLE 3: PREPARATION OF AN LMNO / Graphite BATTERY WITH AND WITHOUT COMPOUND [P14(2CN)2FSI] and CHARGING AND DISCHARGING THE BATTERY

[0131] In a glove box under an inert atmosphere (Argon) with a water and O2 content lower than 1 ppm, the lithium salt LiFSI (0.936 g) is dissolved in the ionic liquid PYR13FSI (6.045 g) to obtain the desired concentration, a (2-cyanoethyl)phosphonium compound P14(2CN)2FSI (0.172 g) is then added and mixed to obtain a homogeneous electrolyte solution.

[0132] The batteries were prepared according to the method described in Example 1. Table 3 below lists the different cathode / anode / electrolyte combinations tested in the battery.

[0133]

[0134] Table 3: LMNO cathode / Graphite anode / electrolyte combinations tested in battery.

[0135] The batteries were tested by galvanostatic cycling from 2 to 5 V at different C rates: 0.1 C and 0.5 C in a climatic chamber at 20 °C.

[0136] The, in which the electrolyte contains the compound P14(2CN)2FSI, shows a discharge capacity loss of 7.5% between 0.1 C and 0.5 C respectively 124.08 mAh / g and 114.73 mAh / g. As the charge and discharge rates increase, the polarization between charge and discharge increases. For cycling at 0.5 C, the discharge capacity loss in 243 cycles is 4.5% (from 114.73 to 109.63mAh / g).

[0137] The, in which the electrolyte does not contain the compound P14(2CN)2FSI, shows a discharge capacity loss of 9% between 0.1 C and 0.5 C respectively 117.19 mAh / g and 107.02 mAh / g. At a charge and discharge rate of 0.2 C, the discharge capacity decreases by 13% between the 10th and 247th cycle in C / 2 from 107.02mAh / g to 93.39mAh / g.

[0138] The capacity loss is less significant for the system in which the electrolyte contains the compound P14(2CN)2FSI.

[0139]

[0140] Table 4: Characteristics of batteries with an LMNO / Graphite system at 0.5 C with and without P14(2CN)2FSI compound.

[0141] Table 4 and show the discharge capacity as a function of number of cycles of the two systems, with and without (2-cyanoethyl)phosphonium salt compound.

[0142] Without P14(2CN)2FSI compound, the first cycle discharge capacity at a charge and discharge rate of 0.5 C is lower than with the (2-cyanoethyl)phosphonium compound (respectively 107.99 mAh / g and 115.30 mAh / g). Regarding cyclability, the capacity of the system containing the P14(2CN)2FSI compound is more stable during the cycles. Indeed, taking into account the first 247 cycles, the capacity loss for the system without P14(2CN)2FSI compound is 13.1% compared to 4.9% for the one containing the P14(2CN)2FSI compound. The coulombic efficiency is also higher for the electrolyte containing (2-cyanoethyl)phosphonium.

[0143] EXAMPLE 4: PREPARATION OF AN LMNO / LTO BATTERY WITH AND WITHOUT [P13(2CN)2FSI] COMPOUND AND CHARGING AND DISCHARGING THE BATTERY

[0144] In a glove box under an inert atmosphere (Argon) with a water and O2 content lower than 1 ppm, the lithium salt LiFSI (0.936 g) is dissolved in the ionic liquid PYR13FSI (6.045 g) to obtain the desired concentration, a (2-cyanoethyl)phosphonium compound P13(2CN)2FSI (0.331 g) is then added and mixed to obtain a homogeneous electrolyte solution.

[0145] The batteries were prepared according to the method described in Example 1. Table 5 below lists the different cathode / anode / electrolyte combinations tested in the battery.

[0146]

[0147] Table 5: LMNO cathode / LTO anode / electrolyte combinations tested in battery.

[0148] The batteries were tested by galvanostatic cycling from 1.2 to 3.5 V at different C rates: 0.05 C, 0.1 C, 0.14 C, 0.2 C, 0.33 C and 0.5 C in a climatic chamber at 20 °C.

[0149] The, in which the electrolyte contains the compound P13(2CN)2FSI, shows a capacity loss in discharge of 14% between 0.05 C and 0.5 C respectively 141.08 mAh / g and 121.44 mAh / g. As the charge and discharge rate increases, the polarization between charge and discharge increases.

[0150] The, in which the electrolyte does not contain the compound P13(2CN)2FSI, shows a loss of capacity in discharge of 30% between 0.05 C and 0.5 C respectively 131.54 mAh / g and 91.22 mAh / g. From the rate 0.2 C, the charge / discharge profile differs by 0.05 C. Indeed, the disappearance of one of the transition plateaus is observed around 2.5 V, this can be due to an irreversible consumption of Li ions +during the formation of passivation films on the surface of the electrodes. When there are no longer enough Li ions + to participate in the Mn4 conversion process + / Mn3 + , the transition plateau disappears.

[0151] Comparing the charge / discharge profiles of the two systems, the one containing the (2-cyanoethyl)phosphonium compound is more stable because no transition plateau disappears during the cycles. This P13(2CN)2FSI compound plays a role in the formation of the passivation film and therefore reduces the irreversible consumption of Li ions + during cycles.

[0152]

[0153] Table 6: Characteristics of batteries with LMNO / LTO system at 0.05 C and 0.5 C with and without compound.

[0154] Table 6 and show the discharge capacity of the two systems, with and without (2-cyanoethyl)phosphonium salt compound.

[0155] Without P13(2CN)2FSI compound, the battery discharge capacity decreases from C / 10 unlike the system containing the (2-cyanoethyl)phosphonium compound for which the capacity remains stable longer and higher for C rates up to 0.5 C. The coulombic efficiency is also higher with the formulation containing (2-cyanoethyl)phosphonium.

[0156] EXAMPLE 5: PREPARATION OF AN MC622 / Graphite BATTERY WITH AND WITHOUT [P14(2CN)2FSI] COMPOUND AND CHARGING AND DISCHARGING THE BATTERY

[0157] In a glove box under inert atmosphere (Argon) with water and O2 content less than 1 ppm, lithium salt LiFSI (1.00g) is dissolved in ionic liquid EMIMFSI (6.49g) in a desired concentration, a (2-cyanoethyl)phosphonium compound P14(2CN)2FSI (0.184g) is then added and mixed to obtain a homogeneous solution.

[0158] The batteries were prepared according to the method described in Example 1.

[0159]

[0160] Table 7: NMC622 cathode / electrolyte / Graphite anode combinations tested in battery.

[0161] The batteries were tested by galvanostatic cycling from 2 to 4.2V at different C rates: 0.05C, 0.1C, 0.14C, 0.2C, 0.33C and 0.5C at room temperature (RT).

[0162]

[0163] Table 8: Characteristics of batteries with NMC622 / Gr system at 0.05 C and 0.5 C with and without compound.

[0164] Table 8 and Figures 10 and 11 show the discharge capacity as a function of the number of cycles of the two systems, with and without compound. L shows the first 60 cycles and L shows the continuation of the cycles at C / 2 up to 250 cycles at room temperature.

[0165] Without the compound, the battery discharge capacity gradually decreases, unlike the system containing the (2-cyanoethyl)phosphonium compound, for which the capacity at different charge and discharge rates is better preserved. La shows that the effect is even more pronounced on the return to charge and discharge rates of 0.1 C, where the discharge capacity retention capacity is significantly lower without the (2-cyanoethyl)phosphonium than with it. The coulombic efficiency is also higher with the formulation containing the (2-cyanoethyl)phosphonium.

[0166] EXAMPLE 6: Comparative table showing the impact of the number of nitrile functional groups on the concentration required to achieve the molecule's effectiveness.

[0167]

[0168] Table 9Comparative table showing the ratio of molar mass of the molecule / number of nitrile functions carried by the molecule.

[0169] For the same electrode system, when using P1(2CN)3FSI, 129g of molecule will be required, whereas for P14(2CN)2FSI, 195g of molecule will be required for the same efficiency, which results in a higher concentration and therefore a reduction in conductivity.

[0170]

[0171] Table 10: At equivalent product concentration (electrolyte compound), capacity retentions with molecules containing two or three nitrile functions are greater than with molecules containing a single nitrile function.

[0172] Example 7: PREPARATION OF AN NMC532 / GRAPHITE BATTERY WITH AND WITHOUT COMPOUND [P12(2CN)2FSI] AND CHARGING AND DISCHARGING THE BATTERY

[0173] In a glove box under inert atmosphere (Argon) with water and O2 content less than 1 ppm, lithium salt LiFSI (0.936 g) is dissolved in ionic liquid PYR13FSI (6.045 g) to obtain the desired concentration, a (2-cyanoethyl)phosphonium compound P12(2CN)2FSI (0.320 g) is then added and mixed to obtain a homogeneous electrolyte solution.

[0174] The batteries were prepared according to the method described in Example 1. Table 11 below lists the different cathode / anode / electrolyte combinations tested in the battery.

[0175]

[0176] Table 11: NMC532 cathode / Graphite anode / electrolyte combinations tested in battery.

[0177] The batteries were tested by galvanostatic cycling from 2.5 to 4.2 V at different C rates: 0.05 C, 0.1 C, 0.14 C, 0.2 C, 0.33 C and 0.5 C in a climatic chamber at 45 °C.

[0178]

[0179] Table 12: Characteristics of batteries with an NMC532 / Graphite system at 0.05 C and 0.5 C with and without compound

[0180] Table 12 and show the discharge capacity as a function of number of cycles of the two systems, with and without (2-cyanoethyl)phosphonium salt compound at 45 °C.

[0181] The, in which the electrolyte contains the compound P12(2CN)2FSI, shows a discharge capacity loss of 8.6% between 0.05 C and 0.5 C respectively 1.5 mAh / cm² and 1.37 mAh / cm² against a discharge capacity loss of 16% for the electrolyte not containing the (2-cyanoethyl)phosphonium compound.

[0182] Lamontre shows that the capacity at a rate of 0.05C for the electrolyte containing the compound P12(2CN)2FSI is greater than in the electrolyte not containing the compound, 1.50 mAh / cm² against 1.06mAh / cm².

[0183] Without P12(2CN)2FSI compound, the battery discharge capacity is not stable from the first cycles unlike the system containing the (2-cyanoethyl)phosphonium compound for which the discharge capacity remains stable longer and is higher for C rates up to 0.5 C. The coulombic efficiency is also higher with the formulation containing (2-cyanoethyl)phosphonium.

[0184] EXAMPLE 8: PREPARATION OF AN LMNO / GRAPHITE BATTERY WITH [Pbutene(2CN)3FSI] CHARGING AND DISCHARGING THE BATTERY

[0185] In a glove box under an inert atmosphere (Argon) with a water and O2 content lower than 1 ppm, a 3mol / L solution of lithium salt LiFSI in the ionic liquid N1113FSI at 45°C is prepared. For 5g of this solution, Pbutene(2CN)3FSI (0.0225 g) is added at a desired concentration. Everything is mixed to obtain a homogeneous solution.

[0186] The battery was prepared according to the method described in Example 1. Table 13 below lists the cathode / anode / electrolyte combination tested in the battery.

[0187] Positive Electrode / Negative Electrode Capacity / Electrolyte Capacity LMNO – 1.05mAh / cm²Graphite – 1.43mAh / cm²3M LiFSI in N1113FSI + 0.0105 mol / kg Pbutene(2CN)3FSI

[0188] Table 13: LMNO cathode / Graphite anode / electrolyte combination tested in battery.

[0189] The battery was tested in galvanostatic cycling from 3.5 to 5V at a rate of C: 0.5C in a climatic chamber at 25°C.

[0190] Lamontre shows a loss of capacity in discharge of 7.3% between the 1 er cycle in 0.5C and 490 ème cycle in 0.5C going from 112.23mAh / g to 103.98mAh / g respectively. At 490 èmecycle as well as throughout the galvanostatic cycling, the potential plateaus corresponding to the mechanisms of (de)lithiation of the materials of the system are not degraded.

[0191] ElectrolyteC-rateCharge capacity (mAh / g)Discharge capacity (mAh / g)Efficiency (%)3M LiFSI in N1113FSI + 0.0105 mol / kg Pbutene(2CN)3FSI0.5C(1 er cycle)112.86112.2399.443M LiFSI in N1113FSI + 0.0105 mol / kg Pbutene(2CN)3FSI0.5C(490 ème cycle)104.03103.9899.95

[0192] Table 14: Characteristics of a battery with an LMNO / Graphite system at 0.5C.

[0193] Table 14 and show the discharge capacity of a system with [Pbutene(2CN)3FSI]

[0194] With [Pbutene(2CN)3FSI] the first cycle discharge capacity at a C rate of 0.5C is 112.23mAh / g. Regarding cyclability, the capacity of the system containing Pbutene(2CN)3FSI is stable over the cycles. Indeed, taking into account the first 490 cycles, the capacity retention for the system containing [Pbutene(2CN)3FSI] is 92.7% with a charge and discharge depth of 100%. The coulombic efficiency is also high for the electrolyte containing [Pbutene(2CN)3FSI], i.e. 99.95% at 490 ème cycles.

[0195] EXAMPLE 9: PREPARATION OF AN LMNO / Lithium Metal BATTERY WITH [P14(2CN)2FSI] CHARGING AND DISCHARGING THE BATTERY

[0196] In a glove box under inert atmosphere (Argon) with water and O2 content less than 1 ppm, lithium salt LiFSI (3.74g) is dissolved in ionic liquid N1114FSI (10.51g) in a desired concentration, P14(2CN)2FSI (0.35g) is then added and mixed to obtain a homogeneous solution.

[0197] The battery was prepared according to the method described in Example 1. Table 15 below lists the cathode / anode / electrolyte combination tested in the battery.

[0198] Positive Electrode / Negative Electrode Capacity / Electrolyte CapacityLMNO – 1.07mAh / cm²Lithium metal2M LiFSI in N1114FSI + 0.0628 mol / kg P14(2CN)2FSI

[0199] Table 15: LMNO cathode / Lithium metal anode / electrolyte combination tested in battery.

[0200] The battery was tested in galvanostatic cycling from 3.5 to 5V at a C rate of 0.5C in a climatic chamber at 25°C.

[0201] ElectrolyteC-rateDischarge capacity (mAh / g)2M LiFSI in N1114FSI + 0.0628 mol / kg P14(2CN)2FSI0.5C(1 er cycle)136.592M LiFSI in N1114FSI + 0.0628 mol / kg P14(2CN)2FSI0.5C(180 ème cycle)136.26

[0202] Table 16: Characteristics of a battery with an LMNO / Lithium metal system at 0.5C.

[0203] Table 16 and show the discharge capacity of a system with [P14(2CN)2FSI].

[0204] With [P14(2CN)2FSI], the first cycle discharge capacity at a C rate of 0.5C is 136.59mAh / g. Regarding cyclability, the capacity of the system containing P14(2CN)2FSI is stable over the cycles. Indeed, after 180 cycles, no significant capacity loss is observed for the system containing [P14(2CN)2FSI] for a charge and discharge depth of 100%.

[0205] EXAMPLE 10: PREPARATION OF A PRUSSIAN BLUE / CARBONEDUR[P14(2CN)2FSI] BATTERY

[0206] In a glove box under inert atmosphere (Argon) with water and O2 content less than 1 ppm, sodium salt NaFSI (2.03g) is dissolved in ionic liquid N1114FSI (11.76g) in a desired concentration, P14(2CN)2FSI (0.339g) is then added and mixed to obtain a homogeneous solution.

[0207] The battery was prepared according to the method described in Example 1. Table 17 below lists the cathode / anode / electrolyte combination tested in the battery.

[0208] Positive Electrode / Capacity Negative Electrode / Capacity Electrolytes Prussian Blue – 0.56mAh / cm² Hard Carbon – 0.85mAh / cm² 1M NaFSI in N1114FSI + 0.0628 mol / kg P14(2CN)2FSI

[0209] Table 17: Prussian Blue cathode / Hard Carbon anode / electrolyte combination tested in battery.

[0210] ElectrolyteC-rateCharge capacity (%)Discharge capacity (%)Efficiency (%)1M NaFSI in N1114FSI + 0.0628 mol / kg P14(2CN)2FSI0.05C10094.4294.420.1C76.7075.9398.980.14C62.3362.0299.44

[0211] Table 18: Characteristics of a battery with a Prussian Blue / Hard Carbon system at different C rates.

[0212] Table 18 shows that with P14(2CN)2FSI, the coulombic efficiencies at C rates of 0.1C and 0.14C are 98.98% and 99.44% respectively.

Claims

An electrolyte composition comprising a lithium salt or a sodium salt, an aprotic organic solvent and an electrolyte compound, wherein said electrolyte compound comprises a (2-cyanoethyl)phosphonium salt as represented by formula (I): (I)wherein:X- is selected from fluoroalkyl phosphates, fluoroalkyl phosphinates, fluoroalkyl phosphonates, acetates, triflates, imides, amides, methanides, borates, phosphates, sulfonimides or aluminates;R1 isindependently selected from an unsubstituted -CH2-CH2-CN chain, a C1-C20 alkyl, a C3-C6 cycloalkyl, a C2-C20 alkenyl, a C5-C8 cycloalkenyl, a C2-C20 alkynyl, a vinylbenzyl group; in which the hydrogen atoms may be substituted by a fluorine, a -CF3, an ether, an alkyl group, a perfluorinated alkyl group, a silyl group, a siloxy group, a sulfoxide group, a nitrile group, a thioether group or combinations thereof.R2 is independently selected from a C1-C20 alkyl group, a C3-C6 cycloalkyl group, a C2-C20 alkenyl group, a C5-C8 cycloalkenyl group, a C2-C20 alkynyl group, a vinylbenzyl group; wherein the hydrogen atoms may be substituted by a fluorine, a -CF3, an ether, an alkyl group, a perfluorinated alkyl group, a silyl group, a siloxy group, a sulfoxide group, a nitrile group, a thioether group or combinations thereof. The electrolyte composition of claim 1 wherein R1 is selected from unsubstituted -CH2-CH2-CN chain, C1-C10 alkyl wherein the hydrogen atoms may be substituted by fluorine, -CF3, ether, alkyl group, perfluorinated alkyl group, silyl group, siloxy group, sulfoxide group, nitrile group, thioether group or combinations thereof; and R2 is C1-C10 alkyl wherein the hydrogen atoms may be substituted by fluorine, -CF3, ether, alkyl group, perfluorinated alkyl group, silyl group, siloxy group, sulfoxide group, nitrile group, thioether group or combinations thereof. An electrolyte composition according to claim 2 wherein R1 is selected from methyl or C1-C4 alkyl wherein the hydrogen atoms may be substituted by fluorine, -CF3, ether, alkyl, perfluorinated alkyl, silyl, siloxy, sulfoxide, nitrile, thioether or combinations thereof; and wherein R2 is selected from methyl, ethyl, propyl, isobutyl, n-butyl or allyl. An electrolyte composition according to claim 1 wherein:X- is selected from fluoroalkyl phosphates, fluoroalkyl phosphinates, fluoroalkyl phosphonates, acetates, triflates, imides, amides, methides, borates, phosphates, sulfonimides or aluminates;R1 is independently selected from C1-C20 alkyl, C3-C6 cycloalkyl, C2-C20 alkenyl, C5-C8 cycloalkenyl, C2-C20 alkynyl, vinylbenzyl; in which the hydrogen atoms may be substituted by a fluorine, a -CF3, an ether, an alkyl group, a perfluorinated alkyl group, a silyl group, a siloxy group, a sulfoxide group, a thioether group or combinations thereof.R2 is independently selected from C1-C20 alkyl, C3-C6 cycloalkyl, C2-C20 alkenyl, C5-C8 cycloalkenyl, C2-C20 alkynyl, vinylbenzyl; wherein the hydrogen atoms may be substituted by fluorine, -CF3, ether, alkyl, perfluorinated alkyl, silyl, siloxy, sulfoxide, thioether or combinations thereof. An electrolyte composition according to claim 4 wherein R1 and R2 are independently selected from C1-C10 alkyl wherein the hydrogen atoms may be substituted by fluorine, -CF3, ether, alkyl group, perfluorinated alkyl group, silyl group, siloxy group, sulfoxide group, thioether group or combinations thereof. An electrolyte composition according to claim 5 wherein R1 is selected from methyl or C1-C4 alkyl in which the hydrogen atoms may be substituted by fluorine, -CF3, ether, alkyl, perfluorinated alkyl, silyl, siloxy, sulfoxide, thioether or combinations thereof; and R2 is selected from methyl, ethyl, propyl, isobutyl, n-butyl or allyl. Electrolyte composition according to one of claims 1 to 6 in which the anion is chosen from bis(fluorosulfonyl)imide (FSI), bis(trifluoromethanesulfonyl)imide (TFSI), tetrafluoroborate, hexafluorophosphate, dicyanamide, triflate, 4,5-dicyano-2-(trifluoromethyl)imidazolate, fluorosulfonyl(trifluoromethanesulfonyl)imide, bis(oxalato)borate, difluorobis(oxalato)borate, acetate., N-ethyl-N-methyl-functionalized sulfonimide, (difluoromethanesulfonyl)(trifluoromethanesulfonyl)imide, (methanesulfonyl)(trifluoromethanesulfonyl)imide, (difluoromethanesulfonyl)(fluoromethanesulfonyl)imide, (methanesulfonyl)(fluoromethanesulfonyl)imide. Electrolyte composition according to claim 7 wherein the anion X- is chosen from FSI or TFSI. Electrolyte composition according to claim 1, the (2-cyanoethyl)phosphonium salt of which is represented by the formula (II): (II)whereinX- is selected from fluoroalkyl phosphates, fluoroalkyl phosphinates, fluoroalkyl phosphonates, acetates, triflates, imides, amides, methides, borates, phosphates, sulfonimides or aluminates; andR2 is independently selected from C1-C20 alkyl, C3-C6 cycloalkyl, C2-C20 alkenyl, C5-C8 cycloalkenyl, C2-C20 alkynyl, vinylbenzyl; in which the hydrogen atoms may be substituted by a fluorine, a -CF3, an ether, an alkyl group, a perfluorinated alkyl group, a silyl group, a siloxy group, a sulfoxide group, a thioether group or combinations thereof. An electrolyte composition according to claim 9 wherein R2 is C1-C10 alkyl wherein the hydrogen atoms may be substituted by fluorine, -CF3, ether, alkyl group, perfluorinated alkyl group, silyl group, siloxy group, sulfoxide group, thioether group or combinations thereof. An electrolyte composition according to claim 10 wherein R2 is selected from C1-C4 alkyl wherein the hydrogen atoms may be substituted by fluorine, -CF3, ether, alkyl group, perfluorinated alkyl group, silyl group, siloxy group, sulfoxide group, thioether group or combinations thereof. An electrolyte composition according to claim 11 wherein R2 is selected from methyl, ethyl, propyl, isobutyl, n-butyl or allyl. Electrolyte composition according to one of claims 9 to 12 in which the anion is chosen from bis(fluorosulfonyl)imide (FSI), bis(trifluoromethanesulfonyl)imide (TFSI), tetrafluoroborate, hexafluorophosphate, dicyanamide, triflate, 4,5-dicyano-2-(trifluoromethyl)imidazolate, fluorosulfonyl(trifluoromethanesulfonyl)imide, bis(oxalato)borate, difluorobis(oxalato)borate, acetate., N-ethyl-N-methyl-functionalized sulfonimide, (difluoromethanesulfonyl)(trifluoromethanesulfonyl)imide, (methanesulfonyl)(trifluoromethanesulfonyl)imide, (difluoromethanesulfonyl)(fluoromethanesulfonyl)imide, (methanesulfonyl)(fluoromethanesulfonyl)imide. Electrolyte composition according to claim 13 wherein the anion X- is selected from FSI or TFSI. An electrolyte composition according to claim 1 wherein the (2-cyanoethyl)phosphonium salt is in the form of a phosphonium salt dimer, said dimer being represented by formula (III) (III) in which Z is chosen from C1-C20 alkyl di-radicals of the type –(CH2) n– which may comprise one or more ethers or which may comprise one or more chains of the type –CH2–Y–CH2– with Y=S or SO or SO2; preferably the alkyl diradical is an ethyl, propyl, butyl or pentyl diradical;X- is chosen from fluoroalkyl phosphates, fluoroalkyl phosphinates, fluoroalkyl phosphonates, acetates, triflates, imides, amides, methides, borates, phosphates, sulfonimides or aluminates;R2 is independently chosen from an unsubstituted -CH2-CH2-CN chain, by a C1-C20 alkyl, a C3-C6 cycloalkyl, a C2-C20 alkenyl, a C5-C8 cycloalkenyl, a C2-C20 alkynyl, a vinylbenzyl group; wherein the hydrogen atoms may be substituted by fluorine, -CF3, ether, alkyl, perfluorinated alkyl, silyl, siloxy, sulfoxide, nitrile, thioether or combinations thereof; An electrolyte composition according to claim 15 wherein R2 is C1-C10 alkyl wherein the hydrogen atoms may be substituted by fluorine, -CF3, ether, alkyl group, perfluorinated alkyl group, silyl group, siloxy group, sulfoxide group, thioether group or combinations thereof. An electrolyte composition according to claim 16 wherein R2 is selected from methyl or C1-C4 alkyl in which the hydrogen atoms may be substituted by fluorine, -CF3, ether, alkyl, perfluorinated alkyl, silyl, siloxy, sulfoxide, thioether or combinations thereof; and R2 is selected from methyl, ethyl, propyl, isobutyl, n-butyl or allyl. Electrolyte composition according to one of claims 15 to 17 in which the anion is chosen from bis(fluorosulfonyl)imide (FSI), bis(trifluoromethanesulfonyl)imide (TFSI), tetrafluoroborate, hexafluorophosphate, dicyanamide, triflate, 4,5-dicyano-2-(trifluoromethyl)imidazolate, fluorosulfonyl(trifluoromethanesulfonyl)imide, bis(oxalato)borate, difluorobis(oxalato)borate, acetate., N-ethyl-N-methyl-functionalized sulfonimide, (difluoromethanesulfonyl)(trifluoromethanesulfonyl)imide, (methanesulfonyl)(trifluoromethanesulfonyl)imide, (difluoromethanesulfonyl)(fluoromethanesulfonyl)imide, (methanesulfonyl)(fluoromethanesulfonyl)imide. Electrolyte composition according to claim 18 wherein the anion X- is selected from FSI or TFSI. An electrolyte composition according to one of claims 1 to 19 wherein said aprotic organic solvent is selected from an ionic liquid, a carbonate, a glyme, an alkyl sulfonamide or a mixture thereof. Electrolyte composition according to one of claims 1 to 20 wherein the ionic liquid comprises (i) a cation selected from an imidazolium, or based on pyrrolidinium, morpholinium, pyridinium, piperidinium, phosphonium, ammonium and (ii) an anion selected from hexafluorophosphate (PF6), tetrafluoroborate (BF4), bis(trifluoromethanesulfonyl)imide (TFSI), bis(fluorosulfonyl)imide (FSI), dicyanamide (DCA), 4,5-dicyano-2-(trifluoromethyl)imidazolide (TDI), fluorosulfonyl-(trifluoromethanesulfonyl)imide (FTFSI), (difluoromethanesulfonyl)(trifluoromethanesulfonyl)imide (DFTFSI), bis(oxalato)borate (BOB), difluoro(oxalato)borate (DFOB). Electrolyte composition according to one of claims 1 to 21 comprising a lithium or sodium salt, an electrolyte compound as defined in one of claims 1, 4 or 9 and an ionic liquid. A battery comprising a cathode, a separator and an electrolyte composition as described in one of claims 1 to 22. Battery comprising a cathode, an anode, a separator and an electrolyte composition as defined in one of claims 1 to 22. Battery according to one of claims 23 or 2 where the separator and the electrolyte are identical. Battery according to one of claims 23 to 25 in which the cathode is chosen fromFor a Lithium battery: a lithium intercalating compound, chosen from lithium-iron phosphate, (LiFePO4), lithium-nickel-manganese-cobalt oxide, (LiNixMnyCozO2), doped lithium-nickel-manganese-cobalt oxide, (LiNixMnyCozO2), lithium-cobalt oxide (LiCoO2), doped lithium-cobalt oxide, lithium-nickel oxide (LiNiO2), doped lithium-nickel oxide, lithium-manganese oxide (LiMn2O4), doped lithium-manganese oxide, NCA, lithium-vanadium oxide, doped lithium-vanadium oxide, lithium and mixed metal oxides, Lithium Manganese Nickel Oxide (LMNO), lithium and mixed transition metal oxides, doped lithium and mixed transition metal oxides (NCA, LMNX,), lithium vanadium phosphate, lithium manganese phosphate, lithium cobalt phosphate, lithium and mixed metal phosphates,metal sulfides and their combinations. For a sodium-ion battery: a metal oxide such as VO2, V2O5, H2V3O8, b-MnO2; layered NaMOX such as Na0.71CoO2, Na0.7MnO2, b-NaMnO2, Na1.1V3O7.9, Na2RuO3, Na2 / 3[Ni1 / 3Mn2 / 3]O2, Na0.67Co0.5Mn0.5O2, Na0.66Li0.18Mn0.71Ni0.21Co0.08O2+x; 1D tunnel oxides such as Na0.44MnO2, Na0.66[Mn0.66Ti0.34]O2, Na0.61[Mn0.27Fe0.34Ti0.39]O2; fluorides such as FeO0.7F1.3 and NaFeF3; sulfates such as Na2Fe2(SO4)3 and Eldfellite NaFe(SO4)2; phosphates NaFePO4 and FePO4; Na3V2(PO4)3, Na3V2(PO4)3, Na3V2(PO4)3@C@rGO, Na3V2(PO4)3 / C, NaVOPO4; pyrophosphates such as Na2CoP2O7, Na2FeP2O7 and Na3.12Fe2.44(P2O7)2; fluorophosphates such as NaVPO4F, Na3V2(PO4)2F3, Na3V2O2(PO4)2F@RuO2, Na3(VO1-xPO4)2F1+2x, Na3.5V2(PO4)2F3; mixed phosphates such as Na7V4(P2O7)4(PO4), Na3MnPO4CO3; hexacyanometalates such as MnHCMn PBAs, Na1.32Mn[Fe(CN)6]0.83.3.5H2O,NaxCo[Fe(CN)6]0.90·2.9H2O; critical metal-free cathodes such as Na2C6O6, Na6C6O6, SSDC, C6Cl4O2 / CMK, PTCDA-PI, poly(anthraquinonyl imide)s and functionalized graphite; Prussian white analoguesPrussian blue analogues, Battery according to one of claims 24 to 26 in which the anode is chosen from:For a Lithium-ion battery:a titanium composite oxide containing lithium;mixture of niobium oxides (XNO);metals (Me) such as Si, Sn, Li, Zn, Mg, Cd, Ce, Ni and Fe or alloys thereof;graphite, graphene, including particles of natural graphite, artificial graphite, meso-carbon microbeads (MCMB) and carbon (including soft carbon, hard carbon, carbon nanofibers and carbon nanotubes);silicon (Si), silicon / graphite composites, combinations of silicon of germanium (Ge), tin (Sn), lead (Pb), antimony (Sb), bismuth (Bi), zinc (Zn), aluminum (Al), nickel (Ni), cobalt (Co), manganese (Mn), titanium (Ti), iron (Fe) and cadmium (Cd);alloys or intermetallic compounds of Si, Ge, Sn, Pb, Sb, Bi, Zn, Al or Cd with other elements, said alloys or compounds being stoichiometric or non-stoichiometric;oxides, carbides, nitrides, sulfides, phosphides, selenides and tellurides of Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, Fe, Ni, Co, Ti, Mn or Cd, and mixtures or composites thereof;oxides (MeOx) of metals (Me);and composites of metals (Me) with carbon;MXene materials, [M; xC where X = 2,3,4). For a sodium-ion battery: oxide, sulfide, selenide, phosphide and MOF-based materials and carbon-based materials; carbon-based materials include expanded graphite, N-doped expanded graphite, carbon black, amorphous carbon, carbon microspheres, hard carbon, meso-strong soft carbon, carbon nanotubes, graphene nanosheets, nitrogen-doped CNTs, N-doped graphene foam, N-doped porous nanofibers, microporous carbon and cube-shaped porous carbon;oxides include MnO2 nanoflowers, NiO nanosheets, porous SnO, porous SnO2 nanotubes, porous 3D Fe3O4–C, porous CuO-RGO, ultrasmall nitrogen-doped MnO-CNTs, CuS microflowers, SnS2-RGO, Co3S4-PANI, ZnS-RGO, NiS-RGO, Co3S4-PANI, MoS2–C, nitrogen-doped WS2-conductive carbon nanosheets, Sb3Se3-RGO nanorods, MoSe2-carbon fiber, multi-shell Sn4P3 nanostructures, Sn4P3–C nanospheres, Se4P4, CoP nanoparticles, FeP nanorod arrays on carbon fabric, MoP-C, CUP2-C, hollow NiO / Ni graphene, nitrogen-doped yellow-shell structured CoSe / C; Na metal; Battery according to one of claims 24 to 27 in which when the cathode is made of LMNO then the anode is made of graphite or LTO; when the cathode is made of NMC532 then the anode is made of graphite; when the cathode is made of NMC622 then the anode is made of graphite; when the cathode is made of LFP then the anode is made of graphite; when the cathode is made of LFP then the anode is made of LTO.

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