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  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F126/00—Homopolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a single or double bond to nitrogen or by a heterocyclic ring containing nitrogen
  • C08F126/06—Homopolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a single or double bond to nitrogen or by a heterocyclic ring containing nitrogen by a heterocyclic ring containing nitrogen
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  • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
  • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
  • C08F220/04—Acids; Metal salts or ammonium salts thereof
  • C08F220/06—Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof
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  • C08F222/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a carboxyl radical and containing at least one other carboxyl radical in the molecule; Salts, anhydrides, esters, amides, imides, or nitriles thereof
  • C08F222/04—Anhydrides, e.g. cyclic anhydrides
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  • C08F226/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a single or double bond to nitrogen or by a heterocyclic ring containing nitrogen
  • C08F226/06—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a single or double bond to nitrogen or by a heterocyclic ring containing nitrogen by a heterocyclic ring containing nitrogen
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  • C08F230/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and containing phosphorus, selenium, tellurium or a metal
  • C08F230/04—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and containing phosphorus, selenium, tellurium or a metal containing a metal
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  • C08F293/00—Macromolecular compounds obtained by polymerisation on to a macromolecule having groups capable of inducing the formation of new polymer chains bound exclusively at one or both ends of the starting macromolecule
  • C08F293/005—Macromolecular compounds obtained by polymerisation on to a macromolecule having groups capable of inducing the formation of new polymer chains bound exclusively at one or both ends of the starting macromolecule using free radical "living" or "controlled" polymerisation, e.g. using a complexing agent
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  • C08F299/00—Macromolecular compounds obtained by interreacting polymers involving only carbon-to-carbon unsaturated bond reactions, in the absence of non-macromolecular monomers
  • C08F299/02—Macromolecular compounds obtained by interreacting polymers involving only carbon-to-carbon unsaturated bond reactions, in the absence of non-macromolecular monomers from unsaturated polycondensates
  • C08F299/022—Macromolecular compounds obtained by interreacting polymers involving only carbon-to-carbon unsaturated bond reactions, in the absence of non-macromolecular monomers from unsaturated polycondensates from polycondensates with side or terminal unsaturations
  • C08F299/024—Macromolecular compounds obtained by interreacting polymers involving only carbon-to-carbon unsaturated bond reactions, in the absence of non-macromolecular monomers from unsaturated polycondensates from polycondensates with side or terminal unsaturations the unsaturation being in acrylic or methacrylic groups
• • H—ELECTRICITY
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  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
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  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
  • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• • H—ELECTRICITY
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  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
  • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
  • H01M10/0565—Polymeric materials, e.g. gel-type or solid-type
• • H—ELECTRICITY
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  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/36—Selection of substances as active materials, active masses, active liquids
  • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
  • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
  • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
• • H—ELECTRICITY
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  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
  • H01M4/621—Binders
  • H01M4/622—Binders being polymers
• • H—ELECTRICITY
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  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
  • H01M4/621—Binders
  • H01M4/622—Binders being polymers
  • H01M4/623—Binders being polymers fluorinated polymers
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  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
  • H01M50/411—Organic material
  • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
  • H01M50/417—Polyolefins
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  • C08F2438/00—Living radical polymerisation
  • C08F2438/03—Use of a di- or tri-thiocarbonylthio compound, e.g. di- or tri-thioester, di- or tri-thiocarbamate, or a xanthate as chain transfer agent, e.g . Reversible Addition Fragmentation chain Transfer [RAFT] or Macromolecular Design via Interchange of Xanthates [MADIX]
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  • H01M2300/00—Electrolytes
  • H01M2300/0017—Non-aqueous electrolytes
  • H01M2300/0065—Solid electrolytes
  • H01M2300/0082—Organic polymers
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• • H—ELECTRICITY
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  • H01M4/36—Selection of substances as active materials, active masses, active liquids
  • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
  • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
• • H—ELECTRICITY
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  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/36—Selection of substances as active materials, active masses, active liquids
  • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
  • H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/10—Energy storage using batteries

Definitions

• the technical field generally relates to polymers comprising monomeric units derived from vinylimidazole derivatives, their methods of production and their use in electrochemical cells, for instance, in composite electrodes and/or in polymer electrolytes.
• polymer binders are commonly used to promote cohesion between active material particles and mechanical adhesion of the active material to the current collector.
• Traditional polymer binders comprised in a composite electrode are electrochemically inactive and chemically inert over the potential range used. However, they significantly contribute to the mass and stability of the battery (see Yamamoto, H et al., Lithium-Ion Batteries: Science and Technologies. Springer New York, 2009, 163-179).
• PVDF polyvinyl difluoride
• NMP N-methyl-2-pyrrolidone
• PVDF dissolved in NMP is an effective electrochemically inert polymeric binder, it holds significant drawbacks for its use in industrial applications, such as production costs and solvent evaporation post electrode coating, which requires a substantial amount of energy (Lux, S. F. et ai, Supra). Furthermore, when in contact with the battery electrolyte, PVDF induces the formation of lithium fluoride which accelerates the binder's chemical degradation (see Guerfi, A. et ai., Supra) thereby increasing the battery degradation rate and, consequently, reducing its useful life.
• Carboxymethyl cellulose (CMC) used in combination with styrene-butadiene rubber (SBR) is another common example of polymeric coating used in the field of rechargeable batteries.
• SBR styrene-butadiene rubber
• CMC/SBR binders can be used in combination with active materials such as LiFeP04 and LTO (Chou, S.L. et ai., Physical Chemistry Chemical Physics, 16.38 (2014): 20347-20359) but are known to be ineffective with materials like LCO (Lee, J.T.
• CMC/SBR binders are electrochemically inactive and do not contribute positively to the battery efficiency.
• Poly (acrylonitrile) (PAN), poly (acrylic acid) (PAA) and poly (vinyl alcohol) (PVA) have also been used as polymeric binders for composite electrodes (Cai, Z. P. et ai, Journal of Power Sources, 189.1 (2009): 547-551 ; Gong, L. et al., Electrochemistry Communications, 29 (2013): 45-47; Park, H.K. et ai, Electrochemistry Communications, 13.10 (201 1 ): 1051 -1053).
• polymeric binders having reduced production and/or use costs or incorporating a monomer promoting the diffusion of ions within composite electrodes and/or electrolytes in electrochemical cells.
• the present technology relates to a polymer comprising monomeric units derived from Formulae I and II:
• R 1 and R 2 are each independently selected from H, CN, F, and optionally fluorinated Ci -
• R 3 is selected from a hydrogen atom and an optionally substituted Ci-6alkyl group
• R 4 , R 6 , and R 7 are each independently selected from a hydrogen atom and optionally substituted Ci-6alkyl
• R 5 is selected from -CO2H, optionally substituted -C02Ci-6alkyl, -C(0)NH2, optionally substituted -OCi-6alkyl, optionally substituted Cearyl, optionally substituted Cs-6heteroaryl, -CN, -SO3H, -SO2NH2, and optionally substituted -SOsCi-ealkyl; or R 5 taken together with R 7 and their adjacent carbon atoms form a 5 or 6-membered heterocycle; or a salt thereof.
• R 1 and R 2 are each independently selected from H, CN, F, and optionally fluorinated Ci- 6 alkyl;
• R 3 is selected from a hydrogen atom and an optionally substituted C1-6 alkyl group; or a salt thereof.
• a polymer for use in an element of an electrochemical cell, in the electrode material, in the electrolyte composition and/or in the separator is either a homopolymer comprising monomeric units derived from Formula I or a copolymer comprising monomeric units derived from Formulae I and II.
• an electrode material comprising a polymer and an electrochemically active material.
• said polymer is either a homopolymer comprising monomeric units derived from Formula I or a copolymer comprising monomeric units derived from Formulae I and II.
• an electrolyte comprising either a homopolymer comprising monomeric units derived from Formula I or a copolymer comprising monomeric units derived from Formulae I and II.
• an electrolyte comprising a separator and an electrolyte composition, wherein said separator comprises either a homopolymer comprising monomeric units derived from Formula I or a copolymer comprising monomeric units derived from Formulae I and II.
• an electrochemical cell comprising a negative electrode, a positive electrode and an electrolyte, wherein at least one of the negative electrode, positive electrode and electrolyte comprises either a homopolymer comprising monomeric units derived from Formula I or a copolymer comprising monomeric units derived from Formulae I and II.
• an electrochemical cell comprising a negative electrode, a positive electrode and an electrolyte, wherein at least one of the negative electrode and positive electrode comprises an electrode material comprising either a homopolymer comprising monomeric units derived from Formula I or a copolymer comprising monomeric units derived from Formulae I and II and an electrochemically active material.
• the present technology relates to an electrochemical cell comprising a negative electrode, a positive electrode and an electrolyte, wherein the electrolyte comprises either a homopolymer comprising monomeric units derived from Formula I or a copolymer comprising monomeric units derived from Formulae I and II.
• Figure 1 displays an electrochemical impedance spectrum recorded with LFP/Li cells.
• the square line is recorded with a LFP/Li cell comprising the cathode material C3 (i.e. comprising P(AA-co-2-vinyl-4,5-dicyanoimidazole)) and the diamond line is recorded with a reference LFP/Li cell comprising the cathode material C1 using a PVdF binder.
• Figure 2 displays an electrochemical impedance spectrum recorded with LTO/Li half- cells.
• the discontinued line is recorded with a LTO/Li half-cell comprising the anode material A3 (i.e. comprising P(AA-co-2-vinyl-4,5-dicyanoimidazole) and the full line is recorded with a reference LTO/Li half-cell comprising the anode material A4 using a CMC/SBR binder.
• A3 i.e. comprising P(AA-co-2-vinyl-4,5-dicyanoimidazole
• Figure 3 displays an electrochemical impedance spectrum recorded with a LFP/LTO cell at a state of charge of 50%.
• the square line is the reference cell (CelH ) and the star line represents a cell comprising P(AA-co-2-vinyl-4,5-dicyanoimidazole) (Cell 3).
• Figure 4 displays an electrochemical impedance spectrum recorded with a LFP/LTO cell recorded at a temperature of -30°C and a state of charge of 50%.
• the triangle line is the reference cell (CelH ) and the circle line is a cell comprising P(AA-co-2-vinyl-4,5- dicyanoimidazole) (Cell 3).
• Figure 5 displays a graph of the charge (a) and discharge (b) load characteristics of LFP/Li cells.
• the capacity retention after charge-discharge cycles was evaluated at different charge and discharge rates (1 C, 2 C and 4 C) and recorded at a temperature of 25°C.
• the results are presented for a reference LFP/Li cell comprising the cathode material C3 and a reference LFP/Li cell comprising the cathode material C1 .
• Figure 6 displays a graph of the charge (a) and discharge (b) load characteristics of LFP/LTO cells.
• the capacity retention was evaluated at different charge and discharge rates (1 C, 2 C, 4 C and 10 C) and recorded at a temperature of 25°C.
• the results are presented for the reference Cell 4 (see table 3), for Cell 5 (see table 3) and for Cell 6 (see table 3).
• Figure 7 displays a graph of the charge (a) and discharge (b) load characteristics of LFP/LTO cells.
• the capacity retention was evaluated at different charge and discharge rates (1 C, 2 C, 4 C and 10 C) and recorded at a temperature of 25°C.
• the results are presented for the reference Cell 1 (see table 3), for Cell 3 (see table 3) and for Cell 3 after heating it at 45°C.
• Figure 8 displays a graph of the charge (a) and discharge (b) load characteristics of LFP/LTO cells.
• the capacity retention was evaluated at different charge and discharge rates (1 C, 2 C and 4 C) and recorded at a temperature of -15°C.
• the results are presented for the reference Cell 1 (see table 3), for Cell 3 (see table 3) and for Cell 3 after heating it at 45°C.
• Figure 9 displays a graph of the charge (a) and discharge (b) load characteristics of LFP/LTO cells. The capacity retention was evaluated at different charge and discharge rates (1 C, 2 C and 4 C) and recorded at a temperature of 25°C. The results are presented for the reference Cell 1 (see table 3) and for Cell 7 (see table 3).
• Figure 10 displays a Fourier transform infrared spectroscopy (FTIR) spectrum of a copolymer of 2-vinyl-4,5-dicyanoimidazole and acrylic acid. The analysis was performed at a temperature of 25°C.
• FTIR Fourier transform infrared spectroscopy
• Figure 1 1 displays a FTIR spectrum of the copolymer of 2-vinyl-4,5-dicyanoimidazole and acrylic acid. The analysis was performed after heating of the polymer at a temperature of 45°C (see Example 5(d)).
• the expression "monomeric units derived from” and equivalent expressions used herein refer to a polymer repeat units which is the result of a polymerizable monomer after its polymerization. For example, referring to a monomeric unit derived from a vinyl group is equvalent to a reference to its ethylene polymerized form.
• alkyl refers to saturated hydrocarbons having from one to sixteen carbon atoms, including linear or branched alkyl groups.
• alkyl groups include, without limitation, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, isopropyl, fe/f-butyl, sec-butyl, isobutyl, and the like.
• alkyl group is located between two functional groups, then the term alkyl also encompasses alkylene groups such as methylene, ethylene, propylene, and the like.
• the term "Ci-C n alkyl” refers to an alkyl group having from 1 to the indicated "n" number of carbon atoms.
• alkoxy as used herein means an alkyl group having an oxygen atom attached thereto.
• Representative alkoxy groups include groups having 1 to about 6 carbon atoms, e.g., methoxy, ethoxy, propoxy, fe/f-butoxy and the like.
• Examples of alkoxy groups include methoxy, ethoxy, isopropyloxy, propoxy, butoxy, pentoxy, glycidyloxy, fluorom ethoxy, difluoromethoxy, trifluoromethoxy, chloromethoxy, dichloromethoxy, trichloromethoxy groups and the like.
• alkoxy includes both unsubstituted or substituted alkoxy groups.
• cycloalkyl and equivalent expressions refer to a group comprising a saturated or partially unsaturated (non-aromatic) carbocyclic ring in a monocyclic or polycyclic ring system, including spiro (sharing one atom) or fused (sharing at least one bond) carbocyclic ring systems, having from three to fifteen ring members.
• cycloalkyl groups include, without limitation, cyclopropyl, cyclobutyl, cyclopentyl, cyclopenten-1 -yl, cyclopenten-2-yl, cyclopenten-3-yl, cyclohexyl, cyclohexen-1 -yl, cyclohexen-2-yl, cyclohexen-3-yl, cycloheptyl, bicyclo[4,3,0]nonanyl, norbornyl, and the like.
• the term cycloalkyl includes both unsubstituted cycloalkyl groups and substituted cycloalkyl groups.
• C3-C n cycloalkyl refers to a cycloalkyl group having from 3 to the indicated "n" number of carbon atoms in the ring structure.
• heterocycloalkyl refers to a group comprising a saturated or partially unsaturated (non-aromatic) carbocyclic ring in a monocyclic or polycyclic ring system, including spiro (sharing one atom) or fused (sharing at least one bond) carbocyclic ring systems, having from three to fifteen ring members, where one or more (up to six) ring members are substituted or unsubstituted heteroatoms (e.g. N, O, S, P) or groups containing such heteroatoms (e.g.
• Heterocycloalkyl groups may be C- attached or heteroatom -attached (e.g. via a nitrogen atom) where such is possible.
• heterocycloalkyl groups include, without limitation, pyrrolidino, tetrahydrofuranyl, tetrahydrodithienyl, tetrahydropyranyl, tetrahydrothiopyranyl, piperidino, morpholino, thiomorpholino, thioxanyl, piperazinyl, azetidinyl, oxetanyl, thietanyl, homopiperidinyl, oxepanyl, thiepanyl, oxazepinyl, diazepinyl, thiazepinyl, 1 ,2,3,6-tetrahydropyridinyl, 2-pyrrolinyl, 3-pyrrolinyl, 2H-pyranyl, 4H-pyranyl, dioxanyl, 1 ,3-dioxolanyl, pyrazolinyl, dithianyl, dithiolanyl, dihydro
• aryl refers to aromatic groups having 4n+2 ⁇ ( ⁇ ) electrons, wherein n is an integer from 1 to 3, in a conjugated monocyclic or polycyclic system (fused or not) and having from six to fourteen ring atoms.
• a polycyclic ring system includes at least one aromatic ring.
• Aryl may be directly attached, or connected via a Ci-C3alkyl group (also referred to as arylalkyl or aralkyl).
• aryl groups include, without limitation, phenyl, benzyl, phenethyl, 1 -phenylethyl, tolyl, naphthyl, biphenyl, terphenyl, indenyl, benzocyclooctenyl, benzocycloheptenyl, azulenyl, acenaphthylenyl, fluorenyl, phenanthrenyl, anthracenyl, and the like.
• aryl includes both unsubstituted aryl groups and substituted aryl groups.
• C6-C n aryl refers to an aryl group having from 6 to the indicated "n" number of carbons in the ring structure.
• heteroaryl includes refer to aromatic groups having 4n+2 ⁇ ( ⁇ ) electrons, wherein n is an integer from 1 to 3, in a conjugated monocyclic or polycyclic system (fused or not) and having five to fourteen ring members, including one to six substituted or unsubstituted heteroatoms (e.g. N, O, S) or groups containing such heteroatoms (e.g. NH, NRx (Rx is alkyl, acyl, aryl, heteroaryl or cycloalkyl), SO, and the like).
• a polycyclic ring system includes at least one heteroaromatic ring.
• Heteroaryls may be directly attached, or connected via a Ci-C3alkyl group (also referred to as heteroarylalkyi or heteroaralkyl). Heteroaryl groups may be C-attached or heteroatom -attached (e.g. via a nitrogen atom), where such is possible.
• substituted when in association with any of the foregoing groups refers to a group substituted at one or more position with appropriate substituents.
• substituents include, without limitation, cyano, halogen (e.g. F, CI, Br), hydroxy, primary, secondary or tertiary amine, amide, nitro, azido, trifluoromethyl, lower alkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, lower alkoxy, aryloxy, benzyloxy, benzyl, carboxylate, alkoxycarbonyl, sulfonyl, sulfonate, sulfonamide, silane, siloxane, thiocarboxylate, phosphonato, phosphinato, oxo, and the like.
• the present technology relates to polymers comprising monomeric units derived from vinylimidazole derivatives. For instance, these polymers are for use in electrochemical cells such as binders in electrode materials or as part of an electrolyte composition.
• the present technology thus proposes polymers which may be used as polymeric binders in composite electrodes to improve their ionic conductivity, these polymers incorporating moieties with an affinity to ions, especially alkali or alkaline earth metal ions such as lithium ions.
• polymeric binders may decrease the electrode resistance, for example, at low temperature, and/or increase cell capacity.
• incorporating a vinylimidazole derivative monomer such as 2-vinyl-4,5-dicyanoimidazole, in the polymer may significantly reduce the electrode's resistance during the electrochemical reaction and thus increase the cell's capacity retention.
• the solubility of the present polymers, especially in their salt form may also reduce the need to use toxic solvents.
• an imidazole derivative polymer or of a copolymer of acrylic acid or a derivative thereof and an imidazole derivative (such as vinyldicyanoimidazole) in an electrode material binder for instance, used as a co-binder with a compatible polymer such as poly(acrylic acid).
• This polymer or copolymer may also be part of an electrolyte composition, e.g. a solid or gel polymer electrolyte.
• the polymer comprises monomeric units derived from a vinylimidazole derivative of Formula I:
• R 1 and R 2 are each independently selected from H, CN, F, and optionally fluorinated Ci 6 alkyl;
• R 3 is selected from a hydrogen atom and an optionally substituted C1-6 alkyl group; or a salt thereof.
• R 1 and R 2 may each be independently selected from CN and optionally fluorinated Ci-6alkyl. In one example, at least one of R 1 and R 2 is CN , or both are CN.
• R 3 may be a hydrogen atom, a methyl group or a trifluoromethyl group. For instance, R 3 is a hydrogen atom.
• the polymer comprises between 10 mol% and 90 mol% of monomeric units derived from a vinylimidazole derivative of Formula I, or between 10 mol% and 60 mol%, or between 15 mol% and 40 mol%, each upper and lower values being included.
• polystyrene resin may further comprise monomeric units derived from Formula II:
• R 4 , R 6 , and R 7 are each independently selected from a hydrogen atom and optionally substituted Ci-6alkyl
• R 5 is selected from -CO2H, optionally substituted -C02Ci-6alkyl, -C(0)NH2, optionally substituted -OCi-6alkyl, optionally substituted Cearyl, optionally substituted Cs-6heteroaryl, -CN, -SO3H, -SO2NH2, and optionally substituted -SOsCi-e alkyl; or
• R 5 taken together with R 7 and their adjacent carbon atoms form a 5 or 6-membered heterocycle; or a salt thereof.
• R 4 , R 6 , and R 7 are H. In another example, two of R 4 , R 6 , and R 7 are H or each of R 4 , R 6 , and R 7 is H. In one example, R 4 is H. In another example, R 4 is an optionally substituted Ci-6alkyl group, e.g. a methyl group. In other examples, R 5 is -CO2H or R 5 is an optionally substituted -C02Ci-6alkyl group, for example, a -C02(glycidyl) group, or R 5 is an optionally substituted -OCi-6alkyl group, for example, a -O(glycidyl) or -Obutyl group. Other examples include alternatives where R 5 taken together with R 7 and their adjacent carbon atoms form a 5-membered heterocycle, e.g. a maleic anhydride or maleimide group.
• Non-limiting examples of salts of the polymers include alkali and alkaline earth metal salts.
• salts compatible with the other elements of an electrochemical cell in which the polymer is intended for use e.g. a lithium salt, sodium salt, potassium salt, magnesium salt, and the like.
• the number average molecular weight of the polymer may range from 2 000 to 50 000 g/mol, or from 3 000 to 10 000 g/mol.
• the present polymer may be illustrated as a homopolymer of Formula III, or a salt thereof:
• R 1 , R 2 , and R 3 are as herein defined;
• L 1 and L 2 are independently selected from H, an alkyl group, a residue of a polymerisation initiator, and a linker between two or more of the polymer chains; and n 1 is an integer selected such that the number average molecular weight is, for instance, from 2 000 to 50 000 g/mol, or from 3 000 to 10 000 g/mol, or a salt thereof.
• linkers include, without limitations, alkyl, alkoxyl, and aryl groups, each of which may be further substituted.
• L 1 and L 2 are independently linear or branched alkyl groups optionally comprising two or more functional groups comprising heteroatoms selected from oxygen, nitrogen and sulfur (e.g. groups including ether, ester, carboxamide, carbamate, urea, carbonate, their sulfur-containing equivalents, etc.) each attached to a polymer chain in a linear, star or comb configuration.
• the present polymer may also be a copolymer, for instance, a random copolymer, block copolymer, star, branched or hyperbranched copolymer (e.g. including comb, dendritic, etc.).
• the copolymer comprises at least 10 mol% of monomeric units derived from a vinylimidazole of Formula I, or from about 10 mol% to about 50 mol%, for instance, from about 20 mol% to about 40 mol%, or about 30 mol%.
• the present polymer may be illustrated as a random or block copolymer of Formula IV, or a salt thereof:
• n 2 and n 3 are integers representing the number of each monomeric units within the polymer and are selected such that the number average molecular weight is, for instance, from 2 000 to 50 000 g/mol, or from about 3 000 to about 10 000 g/mol, or a salt thereof.
• the ratio n 2 :n 3 may range from 9: 1 to 1 : 1 , or from 4: 1 to 3:2, or about 7:3.
• the present polymer may be illustrated as a random or block copolymer of Formula V, or a salt thereof:
• L 3 is selected from linear or branched alkyl groups and linkers between polymer chains, e.g. a crosslinkable or crosslinked monomer; and n 4 and n 5 are integers each selected from 1 to 4; or a salt thereof.
• the ratio (n 2 x n 4 ) : (n 3 x n 5 ) may range from 9: 1 to 1 : 1 , or from 4:1 to 3:2, or about 7:3.
• n 4 + n 5 3 or 4.
• L 3 is selected from branched alkyl groups or functionalized branched alkyl groups, e.g. pentaerythritol tetra(alkylate ester) derivatives and other similar compounds.
• copolymers of the present technology could be made with different micro-structure such as block copolymers, statistical random copolymers, star copolymers, hyperbranched copolymers, graft copolymers, etc.
• the copolymer may comprise a polymer of Formula III or IV and further comprise monomeric units comprising 2 or more polymerizable functional groups (e.g. double bond or other groups), for instance, having a star or comb configuration.
• the copolymer may also further comprise cross-linkable monomeric units.
• Polymerization of the monomers may be accomplished by any known procedure and method of initiation, for instance, by radical polymerization. When the polymer is a homopolymer, it may be prepared by a polymerization process as illustrated in Scheme
• the initiator may any suitable polymerization initiator, such as peroxides (e.g. hydrogen peroxide, benzoyl peroxide, dicumyl peroxide), azo compounds (e.g. azobisisobutyronitrile (AIBN)), persulfates (e.g. potassium persulfate).
• peroxides e.g. hydrogen peroxide, benzoyl peroxide, dicumyl peroxide
• azo compounds e.g. azobisisobutyronitrile (AIBN)
• persulfates e.g. potassium persulfate
• Polymerization may be further initiated by photolysis, thermal treatment, and any other suitable means. For instance, polymerization may be initiated by ionizing radiation, electrolysis, etc.
• R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , L 1 , L 2 , n 2 and n 3 are as herein defined, or salts thereof.
• the initiator is as defined above.
• the synthesis may be achieved by reversible addition-fragmentation chain transfer polymerization (or RAFT).
• RAFT agent S,S-dibenzyl trithiocarbonate displayed in Scheme 3 is specific for acrylic acid.
• Other known RAFT agents may also be used.
• the polymer could also be prepared and used as its metallic salt form as defined above, e.g. as its lithiated salt form and dissolved in water or as its basic (neutral) form dissolved in NMP, MeCN, DMF or DMSO, for application on a support.
• the block and star copolymer structures can be achieved using controlled radical polymerization, including RAFT polymerization, nitroxide-mediated radical polymerization and atom transfer radical polymerization.
• Scheme 4 illustrates an example of a star copolymerization processes.
• This example comprises a first polymerization of acrylic acid with a star RAFT agent, i.e. pentaerythritol tetrakis[2-(dodecylthiocarbonothioylthio)-2-methylpropionate].
• RAFT agent i.e. pentaerythritol tetrakis[2-(dodecylthiocarbonothioylthio)-2-methylpropionate.
• Each wavy line represents a polymer chain as herein defined, only one of such polymer chains being illustrated for clarity purposes.
• the present technology also relates to electrode materials comprising the polymer defined herein and an electrochemically active material, for instance in the form of particles.
• the electrochemically active material may be a material for use in a negative electrode or a positive electrode.
• Non-limitative examples of electrochemically active materials include titanates and lithium titanates (e.g. T1O2, Li2Ti03, Li 4 TisOi 2, H2T15O11 , H2TU09, or a combination thereof), lithium metal phosphates and metal phosphates (e.g. LiM'P04 and M'P04 where I is Fe, Ni, Mn, Co, or a combination thereof), vanadium oxides (e.g.
• the active material is selected from lithium iron phosphate (LFP), lithium manganese iron phosphate (LMFP), lithium titanate (LTO), graphite, and lithium nickel manganese cobalt oxide (NMC).
• LFP lithium iron phosphate
• LMFP lithium manganese iron phosphate
• LTO lithium titanate
• NMC lithium nickel manganese cobalt oxide
• Other electrochemically active materials may also further include carbon sources such as graphite.
• the particles may be freshly formed or of commercial source, in the form of microparticles or nanoparticles and may further include a coating such as a carbon coating.
• the electrode material may also optionally include additional components like conductive materials, salts, inorganic particles, glass or ceramic particles, and the like.
• conductive materials include carbon black, KetjenTM black, acetylene black, graphite, graphene, carbon fibers, nanofibers (e.g. VGCF) or nanotubes, or a combination thereof.
• Electrodes comprising the present electrode material may be manufactured by preparing an electrode composition including the electrochemically active material, a polymer as defined herein and optional additional elements, including conductive agent, etc. Preparation of the electrode material may be made by dry or wet mixing (e.g. in the presence of a solvent), for instance, by techniques such as mechanofusion, planetary mixer, and the like. The composition is then applied on a support (e.g. current collector), for instance, by spreading by the « Doctor blade » method, by casting, coating, dip- coating, extrusion, calendering, and other methods known in the art. In the case of wet mixing, the electrode material is then dried to remove any traces of the solvent used during the mixing step. The drying may include an initial heating step at normal pressure followed by a drying step performed by heating under vacuum.
• the polymer (the first polymer) as herein defined may be present at a concentration of up to 10 wt% in the total weight of the electrode material, or up to 5 wt%, at a concentration of between 0.1 wt% and 5 wt%, or between 0.4 wt% and 3 wt%, 0.5 wt% and 2 wt% or between 1 wt% and 2 wt%.
• the binder composition may further comprise a second polymer, for instance, selected from polymers based on glycidyl, acrylic or methacrylic acid, vinyl alkyl ether, thiol-containing monomers, and the like.
• the second polymer is a polymer comprising monomeric units based on compounds of Formula II, such polymer being free of monomeric units derived from vinylimidazoles of Formula I, for instance, a homopolymer of monomeric units based on compounds of Formula II.
• the second polymer is a poly(acrylic acid) or poly(methacrylic acid) polymer, preferably poly(acrylic acid).
• the second polymer is selected from fluorine containing polymers (e.g. PVdF, PTFE, etc.), water soluble binders (e.g.
• cellulose-based binders e.g. carboxyalkylcellulose, hydroxyalkylcellulose, and combinations
• carboxyalkylcellulose may be carboxymethylcellulose (CMC) or carboxyethylcellulose.
• second polymers include ion-conductive polymer binders such as block copolymers composed of at least one lithium-ion solvating segment and at least one cross-linkable segment (e.g.
• the weight ratio of the first polymer (as herein defined) to the second polymer may be within the range of from 1 :9 to 7:3, or from 1 :4 to 3:2, or from about 1 :3 to about 1 : 1 , or from about 1 :2 to about 1 : 1 .
• the second polymer may serve, for example, to adjust one or more properties of the electrode material, e.g. adhesion of the electrode material to the adjacent elements of the cell, e.g. the current collector and/or polymer electrolyte.
• the combination of the two polymers may provide the right balance between adhesion and flexibility.
• the polymer may also be used in a composition for coating particles of the electrochemically active material as herein defined, i.e. the coating composition serving as a shell in a core-shell structure.
• the shell composition may comprise a polymer as herein defined at a concentration of, for example, between 5 wt% and 100 wt%, or between 10 wt% and 50 wt%, or between 25 wt% and 75 wt%, or between 50 wt% and 100 wt%, or between 5 wt% and 25 wt%, or between 40 wt% and 75 wt%.
• Such a shell composition may further include additional elements as for the aforementioned binder compositions.
• the electrode composition herein described may further include a binder, comprising or not a polymer as herein defined.
• the present polymer may also be used in an electrolyte composition, for instance, in a gel or solid polymer electrolyte.
• the concentration of the present polymer within the electrolyte composition may be up to 50%, up to 10 wt%, or up to 5 wt%, for example, at a concentration of between 0.1 wt% and 5 wt%, or between 0.4 wt% and 3 wt%, 0.5 wt% and 2 wt% or between 1 wt% and 2 wt%.
• the electrolyte composition may further comprise a second polymer. Examples of second electrolyte polymers include those describe for the binder composition.
• the second polymer electrolyte may be a PEO-based polymer, PVdF, CMC or PVA (polyvinyl acetate).
• Other examples of polymers may be used as second polymer in electrolyte compositions, e.g. polyethyleneglycol-based polymers such as poly(ethylene glycol) methyl acrylate or methacrylate, etc.
• Various additives may also be included in the polymer electrolyte composition to improve its properties, including salts compatible with the other elements of the electrochemical cell or inorganic materials.
• Electrochemical cells and batteries comprising them are also herein contemplated, wherein at least one element of the electrochemical cells comprises the present polymer.
• Such element may be an electrode material, electrolyte composition or counter-electrode material.
• the electrode comprises an electrode material as herein defined.
• the electrolyte comprises an electrolyte composition as herein defined.
• the electrode comprises an electrode material as herein defined, and the electrolyte comprises an electrolyte composition as herein defined.
• the electrode and counter-electrode each independently comprise an electrode material as herein defined.
• the electrode and counter-electrode each independently comprise an electrode material as herein defined, and the electrolyte comprises an electrolyte composition as herein defined.
• the battery is a lithium or lithium-ion battery, e.g. a rechargeable battery. In other examples, the battery is a sodium or potassium battery.
• the electrolyte may be a liquid, gel or solid electrolyte compatible with the electrochemically active materials of the electrode and counter- electrode.
• the electrolyte may further comprise a separator.
• the electrolyte may also be a solid or gel solution of a salt in a polar solvating polymer.
• electrolyte salts include lithium salts such as LiTFSI, LiPF6, LiDCTA, LiBETI, LiFSI, L1BF4, LiBOB, and combinations thereof.
• solid polar solvating polymers comprise linear, branched and/or cross-linked polyether polymers, such as those based on poly(ethylene oxide) (PEO), poly(propylene oxide) (PPO), or on a mixture thereof, optionally further including cross-linkable units.
• additives may be present in electrolyte compositions such as glass particles, ceramics, for instance, nano-ceramics (e.g. AI2O3, ⁇ 2, S1O2, and other similar compounds). These may be added to the polymer electrolyte matrix to improve its mechanical properties and thus limit the formation of dendrites of the salt (Li, Na, etc.) during charging.
• nano-ceramics e.g. AI2O3, ⁇ 2, S1O2, and other similar compounds.
• the electrochemically active material of the counter-electrode may be selected from any known material, including the electrochemically active material (selected for redox compatibility with the electrode active material) defined above as well as alkali metal films, e.g. metallic lithium film or an alloy thereof.
• the counter-electrode material may not include the present polymer when it consists of a film of metallic material.
• the electrode electrochemically active material comprises a lithium metal phosphate or metal phosphate (e.g. LiFePO4, LiMnPO4, LiMnFePO4 and the like) and the counter-electrode electrochemically active material comprises a titanate or lithium titanate (e.g. Li 4 Ti5Oi2).
• the electrode electrochemically active material comprises a lithium metal phosphate or metal phosphate and the counter-electrode electrochemically active material comprises a metallic lithium film.
• the electrochemical cell as herein defined in electrical or hybrid vehicles, or in ubiquitous information technology devices.
• contemplated uses include mobile devices, such as mobile phones, cameras, tablets or laptops, electric or hybrid vehicles, or in the storage of renewable energy.
• Example 1 Homopolymerization
• This example illustrates the homopolymerization of 2-vinyl-4,5-dicyanoimidazole.
• 1 .5 g of vinylimidazole derivative and 50 ml_ of acetonitrile or dioxane was introduced in a round-bottomed flask and the solution was bubbled with nitrogen for 30 minutes to remove oxygen.
• 58 mg of AIBN was then added and the solution was heated to 70°C under nitrogen for at least 12 hours.
• the polymer was then purified by precipitation in 10 volumes of toluene or a mixture of hexanes and diethyl ether (2: 1 ), separated and dried under vacuum for 12 hours.
• a standard production yield obtained using the procedure described in Example 1 (a) was about 95 %.
• This example illustrates the homopolymerization of lithiated 2-vinyl-4,5-dicyanoimidazole.
• 1 .5 g of vinylimidazole derivative, 0.4 g of lithium hydroxide and 20 ml_ of demineralised water are introduced in a round-bottomed flask.
• the solution is stirred at room temperature for 1 hour and then bubbled with nitrogen for 30 minutes to remove oxygen.
• 36 mg of potassium persulfate K2S2O8 (KPS) is then added and the solution is heated to 90°C under nitrogen for at least 24 hours.
• KPS potassium persulfate K2S2O8
• the polymer is then purified by precipitation in 10 volumes of acetonitrile, separated and dried under vacuum for 12 hours.
• Example 2 Copolymerization (a) Random copolymerization of 2-vinyl-4,5-dicyanoimidazole and acrylic acid
• This example illustrates the copolymerization of 2-vinyl-4,5-dicyanoimidazole and acrylic acid.
• 0.40 g of vinylimidazole derivative, 0.50 g of acrylic acid and 15 mL of acetonitrile or dioxane were introduced in a round-bottomed flask and the solution was bubbled with nitrogen for 30 minutes to remove oxygen.
• 12 mg of AIBN was then added and the solution was heated to 70°C under nitrogen for at least 12 hours.
• the polymer was then purified by precipitation in 10 volumes of toluene or a mixture of hexanes and diethyl ether (2:1 ), separated and dried under vacuum for 12 hours.
• a standard production yield obtained using the procedure described in Example 2(a) was about 50-60%.
• This example illustrates the random copolymerization of lithiated 2-vinyl-4,5- dicyanoimidazole and acrylic acid.
• 0.40 g of vinylimidazole derivative, 0.26 g of lithium hydroxide monohydrate and 50 mL of demineralized water were introduced in a round-bottomed flask. The solution was stirred for 1 hour at room temperature to solubilize the imidazole derivative in water. Once solubilized, 0.50 g of acrylic acid was introduced in the round-bottomed flask and the solution obtained was bubbled with nitrogen for 30 minutes to remove oxygen. 25 mg of KPS was added and the solution was heated to 80°C under nitrogen for at least 48 hours. The polymer obtained using this procedure was then purified by precipitation in 10 volumes of acetonitrile and dried under vacuum for 12 hours. A standard production yield obtained using the procedure described in Example 2(b) was about 74%.
• This procedure comprises 2 steps in which the first step comprises the block copolymerization of poly(acrylic acid) by RAFT polymerization.
• the first step comprises the block copolymerization of poly(acrylic acid) by RAFT polymerization.
• acrylic acid 0.102 g of S,S-dibenzyl trithiocarbonate (RAFT CTA) and 15 mL of dioxane were introduced in a round-bottomed flask.
• the solution was stirred at room temperature and bubbled with nitrogen for 30 minutes to remove oxygen.
• 31 .8 mg of AIBN was added and the solution was heated to 80°C under nitrogen for at least 6 hours.
• the polymer was then purified by precipitation in 10 volumes of hexanes or toluene and dried under vacuum for 12 hours.
• the second step comprises the formation of the second block comprising vinylimidazole monomer units.
• 1 .0 g of the previous polymer (PAA-RAFT), 2.0 g. of imidazole derivative and 50 ml of dioxane were added in a round-bottomed flask.
• the solution was stirred at room temperature and bubbled with nitrogen for 30 minutes to remove oxygen.
• 47 mg of AIBN was then added to the reaction mixture and the solution was heated at 90°C under nitrogen for at least 24 hours.
• the polymer was then purified by precipitation in 10 volumes of a mixture of hexanes and diethyl ether (2: 1 ) and dried under vacuum for 12 hours.
• a standard production yield obtained using the procedure described in Example 2(c) was about 82%.
• Example 3 Star Copolymerization of block copolymers of 2-vinyl-4,5- dicyanoimidazole and acrylic acid
• This process is a 2 steps process in which the first step describes the block copolymerization of poly(acrylic acid) by RAFT polymerization.
• To perform this copolymerization 3.09 g of acrylic acid, 0.104 g of the 4 arms RAFT agent pentaerythritol tetrakis[2-(dodecylthiocarbonothioylthio)-2-methylpropionate] (DDMAT RAFT) and 15 mL of dioxane are introduced in a round-bottomed flask. The solution is stirred at room temperature and bubbled with nitrogen for 30 minutes to remove oxygen. 31 .8 mg of the initiator AIBN is added and the solution is heated to 80°C under nitrogen for at least 6 hours. The polymer is then purified by precipitation in 10 volumes of hexanes or toluene and dried at 80°C under vacuum for 12 hours. The polymer is stored at 4°C.
• the second step of Example 3 describes the formation of the second block comprising the vinylimidazole.
• the preparation consists of adding 1 .0 g of the previous polymer (PAA-RAFT), 2.0 g of imidazole derivative and 50 ml of dioxane in a round-bottomed flask. The solution is stirred at room temperature and bubbled with nitrogen for 30 minutes to remove oxygen. 47 mg of the initiator AIBN is added in the flask and the solution is heated to 90°C under nitrogen for at least 24 hours. The polymer is then purified by precipitation in 10 volumes of a mixture of hexanes and diethyl ether (2: 1 ) and dried at 60°C under vacuum for 12 hours.
• cathodes (C3, C4, and C6) comprising a polymer as defined herein and reference cathodes (C1 , C2, and C5) for comparative purposes were prepared in the weight ratios detailed in Table 1 .
• PAA 450 000 g/mol
• the materials were prepared by mixing the electrochemically active material, carbon and polymer(s) in a solvent to obtain a slurry using a planetary centrifugal deaeration mixer from Thinky Corporation.
• the solvent used in the preparation of the materials of Cathodes C1 , C3 and C5 was NMP while the solvent used for Cathodes C2, C4 and C6 was water.
• the PAA and Polymer 1 were used as solutions in NMP respectively at concentrations of 1 1 % and 10%.
• the PAA and Polymer 1 were used as solutions in water respectively at concentrations of 10% and 6.5%.
• the slurries obtained were then casted on aluminum current collectors using the Doctor blade method and dried.
• Example of anode (A2) comprising the polymer as defined herein and a reference anode (A1 ) for comparative purposes were prepared in the weight ratios detailed in Table 2.
• EAM Electrochemically active material
• LTO Li 4 TisOi2
• Anode materials were prepared by mixing the electrochemically active material, carbon and polymer(s) in water to obtain a slurry using a planetary centrifugal deaeration mixer from Thinky Corporation. In the preparation of the material of Anode A2, Polymer 1 was used as a solution in water at a concentration of 6.5%. The slurries obtained was then casted on aluminum current collectors using the Doctor blade method and dried.
• Cells or half-cells comprising the cathode material C3, the cathode material C1 (comparative), the anode material A3, or the anode material A4 (comparative) with lithium metal counter-electrodes were also assembled as described in the present example.
• LFP/LTO cells Prior to the electrochemical testing, LFP/LTO cells, the LFP/Li cells and LTO/Li half-cells were submitted twice to a charge and discharge cycle at 0.2 C at 25 °C.
• xC was the current to fully charge/discharge cell capacity in 1/x hour.
• 1 C, 2C, 4C and 10C were representing respectively the current to charge or discharge at full capacity in 1 hour, 30 minutes, 15 minutes, and 6 minutes.
• the charges were performed in the constant current - constant voltage (CC-CV) mode, the voltage was 3.9 V, the current was 0.2 C and the cut off current was 0.03 mA.
• the discharges were performed in the constant current (CC) mode, the cut off voltage was 2.0 V and current was 0.2 C.
• the voltage was 1 .0 V, the current was 0.2 C and the cut off current was 0.03 mA.
• the discharges were performed in the CC mode, the cut off voltage was 2.7 V and current was 0.2 C.
• the charges were performed in the CC-CV mode, the voltage was 2.4 V, the current was 0.2 C and the cut off current was 0.03 mA.
• the discharges were performed in the CC mode, the cut off voltage was 0.5 V and current was 0.2 C.
• LFP/Li cells comprising the cathode C3 or the cathode C1 (comparative), were assembled as described in Example 4 then, charged and discharged at 0.2 C, 1 .0 C, 4.0 C and 10.0 C. Subsequently, the cells were submitted to a full charge and discharge once again at 0.2 C.
• LFP/LTO cells were assembled as described in Example 4 then, charged and discharged at 0.2 C, 1 .0 C, 2.0 C, 4.0 C, 10.0 C. Subsequently, the cells were submitted to a full charge and discharge once again at 0.2 C.
• LFP/LTO cells and LFP/Li cells were charged at 1 C and then charged again at 0.2 C. Afterwards, the cells were discharged at 0.2 C and charged at 2 C.
• LFP/LTO cells and LFP/Li cells were discharged at 1 C and then discharged again at 0.2 C. Afterwards, the cells were charged at 0.2 C and discharged at 2 C.
• the capacity retention percentage was calculated using the following equation:
• Capacity at 0.2C (1) For the LFP/Li cells, the capacity in the CC region was used for the calculation of the charge load characteristics. The charges were, once again, performed in the CC - CV mode, the voltage was 2.4V, the current was xC and the cut off current was 0.03 mA. The discharges were then performed in the CC mode, the cut off voltage was 0.5 V and the current was xC.
• the capacity in the CC region was used for the calculation of the charge load characteristics.
• the charges were, once again, performed in the CC - CV mode, the voltage was 2.4V, the current was xC and the cut off current was 0.03 mA.
• the discharges were then performed in the CC mode, the cut off voltage was 0.5 V and the current was xC.
• Electrochemical impedance spectroscopy was performed on LFP/Li cells.
• Figure 1 displays an impedance spectrum recorded with this system at a temperature of 25°C.
• an LFP/Li cell comprising the cathode material C3, that was prepared according to the procedure of Example 4, displayed less resistance at 25°C compared with a reference LFP/Li cell comprising the cathode material C1 using PVDF as binder.
• FIG. 2 displays an impedance spectrum recorded with this system at a temperature of 25°C.
• an LTO/Li half- cell comprising the anode material A3, that was prepared according to the procedure of Example 4, displayed less resistance compared with a reference LTO/Li half-cell comprising the anode material A4 using a CMC/SBR binder.
• Cell 3 that was prepared according to the procedure of Example 4, displayed less resistance at 25°C compared with LFP using PVDF as binder (Cell 1 ).
• the resistance at the end of the semi-circle of the reference is 4.5 Ohm for Cell 1 while it is 1 .0 Ohm for Cell 3.
• the EIS was performed using the LFP/LTO coin cell mentioned above at a state of charge of 50%, with a frequency range of 1 MHz to 10 mHz and an AC amplitude of 10 mV.
• Table 4 Impedance
• Figure 4 displays the Nyquist plot at -30°C.
• the resistance at the end of the semi-circle of the reference is 19 Ohm for Cell 1 while the resistance for Cell 3 is 1 1 Ohm.
• the EIS was performed using the LFP/LTO coin cell mentioned above at a state of charge of 50%, with a frequency range of 1 MHz to 10 mHz and an AC amplitude of 10 mV.
• Figure 5 displays a graph of the charge (a) and discharge (b) load characteristics of an LFP/Li cell, comprising the cathode material C3 (i.e. comprising P(AA-co-2-vinyl-4,5-dicyanoimidazole)) and of a reference LFP/Li cell comprising the cathode material C1 using PVDF as binder.
• the capacity retention after charge-discharge cycles was evaluated at different charge and discharge rates (1 C, 2C and 4C) and recorded at a temperature of 25°C.
• the presence of PAA-2-vinyl-4,5-dicyanoimidazole in a LFP/Li cell has a significant influence on the capacity retention and an even greater one at high charge and discharge rates.
• Figure 8 showcases the influence of the 2-vinyl-4,5-dicyanoimidazole on capacity retention when the cell is charged (a) and discharged (b) at a low temperature of -15°C for LFP/LTO coin cells (Cell 1 compared to Cell 3 and Cell 3 after heating at 45°C). Although, not as significant as in Figures 6 and 7, a difference on the capacity retention at high rate of charge and discharge (4 C) can also be observed at low temperature.

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