Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • 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
  • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
  • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • 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
  • H01M4/04—Processes of manufacture in general
  • H01M4/0402—Methods of deposition of the material
  • H01M4/0404—Methods of deposition of the material by coating on electrode collectors
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
  • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
  • H01M10/44—Methods for charging or discharging
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • 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
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
  • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • 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
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
  • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
  • H01M4/1315—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx containing halogen atoms, e.g. LiCoOxFy
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • 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
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
  • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • 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
  • H01M4/362—Composites
  • H01M4/364—Composites as mixtures
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • 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
  • H01—ELECTRIC ELEMENTS
  • 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
  • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • 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
  • H01—ELECTRIC ELEMENTS
  • 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
  • H01M4/624—Electric conductive fillers
  • H01M4/625—Carbon or graphite
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • 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
  • H01M4/64—Carriers or collectors
  • H01M4/66—Selection of materials
  • H01M4/661—Metal or alloys, e.g. alloy coatings
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/10—Energy storage using batteries

Definitions

• the present invention relates to an electrode composition that can be used in a lithium-ion battery, a method for preparing this composition, such an electrode and a lithium-ion battery whose cell or each cell incorporates this electrode.
• lithium-ion batteries where the negative electrode is composed of lithium metal (a material that poses safety problems in the presence of a liquid electrolyte), and lithium-ion batteries. ion, where the lithium remains in the ionic state.
• Lithium-ion batteries consist of at least two faradic conducting electrodes of different polarities, the negative or anode electrode and the positive electrode or cathode, electrodes between which is a separator which consists of an electrical insulator impregnated with an aprotic electrolyte based on Li + cations ensuring the ionic conductivity.
• the electrolytes used in these lithium-ion batteries are usually constituted by a lithium salt, for example of formula LiPF 6 , LiAsF 6 , L1CF3SO3 or L1CIO4, which is dissolved in a mixture of non-aqueous solvents such as acetonitrile, tetrahydrofuran or most often a carbonate for example of ethylene or propylene.
• a lithium-ion battery is based on the reversible exchange of the lithium ion between the anode and the cathode during charging and discharge of the battery, and it has a high energy density for a very low mass thanks to to the physical properties of lithium.
• the active material of the anode of a lithium-ion battery is designed to be the seat of a reversible insertion / deinsertion of lithium and is typically made of graphite (theoretical capacity of 370 mAh / g and redox potential of 0.05 V with respect to the Li + / Li couple) or alternatively of oxides mixed metals among which there are lithiated titanium oxides of formula Li Ti 5 Oi 2, for example.
• the active material of the cathode it is usually composed of an oxide of a transition metal or a lithium iron phosphate.
• Electrodes must also contain an electrically conductive compound, such as carbon black and, to give them sufficient mechanical cohesion, a polymeric binder.
• an electrically conductive compound such as carbon black and, to give them sufficient mechanical cohesion, a polymeric binder.
• the lithium-ion battery electrodes are most often manufactured by a liquid process comprising successively a step of dissolving or dispersing the ingredients of the electrode in a solvent, a step of spreading the solution or dispersion obtained on a metal current collector, then finally a step of evaporation of the solvent.
• Processes using an organic solvent (such as that presented in US-A1-2010 / 0112441) have drawbacks in the fields of environment and safety, in particular the fact that it is necessary to evaporate quantities. These solvents are toxic or flammable.
• the processes using an aqueous solvent their major disadvantage is that the electrode must be dried very thoroughly before it can be used, the traces of water limiting the useful life of lithium batteries.
• EP-B1-1489673 can be cited for the description of a method of manufacturing a graphite-based anode, an elastomeric binder and using an aqueous solvent.
• US-A-5,749,927 discloses a method for the continuous preparation by extrusion of lithium polymer battery electrodes, which comprises mixing the electrode active material with an electrical conductor and a solid electrolyte composition comprising a polymeric binder such as a polyacrylonitrile (PAN), a polyvinylidene difluoride (PVDF) or polyvinylpyrrolidone (PVP), a lithium salt and a propylene carbonate / ethylene carbonate mixture in large excess relative to this polymer.
• PAN polyacrylonitrile
• PVDF polyvinylidene difluoride
• PVPVP polyvinylpyrrolidone
• the mass fraction of active material present in the obtained anode polymer composition is less than 70%, being clearly insufficient for a lithium-ion battery.
• Document WO-A1 -2013 / 090487 teaches in its exemplary embodiments to use a polar aliphatic polyolefin composed of polyvinylidene fluoride (PVDF) as binder in a substantially solvent-free process for preparing a cathode composition for a lithium-ion battery in depositing the cathode composition on a collector by friction.
• PVDF polyvinylidene fluoride
• US-B2-6,939,383 discloses using as a binder, in a lithium-ion battery electrode composition prepared without solvent in a multi-screw extruder, an ionically conductive polyether comprising a polar polymer of a an alkene oxide such as an ethylene oxide-propylene oxide-allyl glycidyl ether copolymer, optionally combined with a non-ionically conductive polymer such as a PVDF, a PAN, PVP, an ethylene-propylene-diene terpolymer ( EPDM) or a styrene-butadiene copolymer (SBR) prepared in emulsion.
• an ionically conductive polyether comprising a polar polymer of a an alkene oxide such as an ethylene oxide-propylene oxide-allyl glycidyl ether copolymer, optionally combined with a non-ionically conductive polymer such as a PVDF, a PAN
• the mass fraction of active material present in the electrode composition is only 64.5%, which is clearly insufficient for a lithium-ion battery.
• US-B1-7,820,328 teaches using a thermoplastic polymer as a binder in a wet or dry lithium-ion battery electrode composition with thermal decomposition of a sacrificial polymer such as ethyl cellulose. , an acrylic resin, a polyvinyl alcohol, a polyvinyl butyral or a polyalkene carbonate.
• This decomposition is carried out under an inert atmosphere (ie non-oxidizing, for example under argon) for an anode composition and in an atmosphere that is either inert or oxidizing (eg under air) for a cathode composition.
• an inert atmosphere ie non-oxidizing, for example under argon
• an atmosphere that is either inert or oxidizing eg under air
• This document does not contain any example of the preparation of an anode or cathode composition with a specific active ingredient and a binder, indicating only that the conditions of decomposition of the sacrificial polymer under an inert or oxidizing atmosphere are carefully controlled. so as not to degrade the other ingredients of the composition such as the binder which is thus not modified and can be chosen from polyethylenes, polypropylenes and fluorinated polyolefins such as PVDF or PTFE.
• Document EP-B-1 639 860 in the name of the Applicant teaches to prepare by melting and without evaporation of solvent an anode composition for lithium-ion battery comprising more than 85% of active material by mass, a polymeric binder constituted a crosslinked diene elastomer such as a hydrogenated nitrile rubber (HNBR), and a nonvolatile organic compound for use in the battery electrolyte solvent.
• a polymeric binder constituted a crosslinked diene elastomer such as a hydrogenated nitrile rubber (HNBR), and a nonvolatile organic compound for use in the battery electrolyte solvent.
• HNBR hydrogenated nitrile rubber
• Document WO-A2-2015 / 124835 also in the name of the Applicant presents a composition of electrode for lithium-ion battery prepared by molten route and without evaporation of solvent, using a sacrificial polymeric phase which is mixture with an active material, with a polymeric binder chosen to be compatible with this phase and with a conductive filler for obtaining a precursor mixture, which is then removed to obtain improved plasticization and fluidity during the implementation. melted mixture despite a mass fraction of active material usable in the composition greater than 80%.
• This document advocates Embodiments of using a binder derived from a polar elastomer which is a HNBR or an ethylene-ethyl acrylate copolymer for its compatibility with the sacrificial phase, which is also polar, which is a polyalkene carbonate, to avoid phase macroseparation.
• a binder derived from a polar elastomer which is a HNBR or an ethylene-ethyl acrylate copolymer for its compatibility with the sacrificial phase, which is also polar, which is a polyalkene carbonate, to avoid phase macroseparation.
• binder polymers subject to their compatibility with the chosen sacrificial phase, so that the latter is continuous in the precursor mixture in which the binder is in the dispersed or co-continuous phase
• these other polymers may be chosen from polyolefins in the broad sense and elastomers such as polyisoprenes.
• This compatibility constraint between binder and sacrificial phase therefore requires the use of a binder of polarity similar to that of the sacrificial phase to avoid having two separate phases in the precursor mixture.
• the electrode compositions presented in these last two documents are generally satisfactory for a lithium-ion battery, however the Applicant has sought in recent research to further improve their electrochemical properties and in particular their reversibility during the first charge-discharge cycle. , their capacity in particular at the C / 5 and C / 2 regimes and their rate of capacity retention after 20 cycles.
• An object of the present invention is therefore to propose a novel electrode composition for a lithium-ion battery containing an active substance of greater than 85% by weight, which is particularly suitable for being used by melting and without solvent without that the chosen binder is compatible with the sacrificial phase, while being able to confer on the electrode an increased reversibility in the first charge-discharge cycle, a capacitance and a cyclability (ie retention of the capacitance after a multitude of cycles) both improved.
• This object is achieved in that the Applicant has surprisingly discovered that if a polyolefin modified as a polymeric binder derived from an apolar aliphatic polyolefin is mixed with this active substance and with an electrically conductive filler.
• the present invention goes against the teaching of the aforementioned document WO-A2-2015 / 124835, because it uses for the binder an apolar starting polymer not compatible with the polar sacrificial phase and further incompatible with the also polar electrolyte used for the battery, starting polymer which is specifically an apolar aliphatic polyolefin (ie excluding in the family of polyolefins aromatic polyolefins and polar polyolefins) and which is modified in a very particular and controlled manner in the composition obtained after elimination of the sacrificial phase, by adding these oxygenated groups such that the modified polyolefin satisfies the aforementioned restricted range for its oxygen mass content.
• starting polymer which is specifically an apolar aliphatic polyolefin (ie excluding in the family of polyolefins aromatic polyolefins and polar polyolefins) and which is modified in a very particular and controlled manner in the composition obtained after elimination of the s
• an electrode composition according to the invention can be used in a lithium-ion battery, the composition comprising an active material capable of performing a reversible insertion / deinsertion of lithium into said electrode, an electrically conductive charge and a polymeric binder comprising at least one modified polyolefin, and this composition is such that said at least one modified polyolefin is derived from an apolar aliphatic polyolefin and incorporates CO and OH oxygen groups having an oxygen atom mass content included between 2% and 10%.
• these oxygenated groups coupled to this oxygen content by mass of 2% to 10% result in the fact that said at least one modified polyolefin which is functionalized by these groups is more polar than the apolar aliphatic polyolefin of departure, while remaining generally apolar (ie little polar) by this operation whose rate in the chain of the modified polyolefin is controlled so as to be sufficient (see mass content in oxygen of at least 2%) but not too high (see oxygen mass content of not more than 10%) to obtain the targeted electrochemical properties including reversibility in the first cycle, the capacity for a C / 5 regime and cyclability of the electrode (ie its capacity retention).
• the Applicant has established in comparative tests that a functionalization of the apolar aliphatic polyolefin insufficient (ie with said mass content less than 2% and for example zero, the apolar polyolefin is not modified in this case) or excessive (ie with said mass content higher than 10%) led to unsatisfactory electrochemical properties for a lithium-ion battery electrode, with in particular a first charge-discharge cycle efficiency and a capacity at a C / 5 rate all two insufficient for this application.
• this particular functionalization of the apolar aliphatic polyolefin advantageously allows in a melt process, and unexpectedly in view of the teaching of the above-mentioned document WO-A2-2015/124835, to couple this nonpolar aliphatic polyolefin forming a binder to a sacrificial polymeric phase on the contrary polar (eg based on at least one polymer of alkene carbonate) thus incompatible with this apolar polyolefin of departure.
• apolar aliphatic polyolefin also makes it possible to use it as a binder in a conventional liquid process.
• said at least one modified polyolefin has an oxygen atom mass content of between 3% and 7% inclusive.
• carbonyl groups preferably comprising carboxylic acid, ketone and optionally ester functions, aldehyde groups, and
• polyolefin in a manner known in the present description an aliphatic or aromatic polymer, homopolymer or copolymer (“copolymer” including by definition terpolymers), derived from at least one alkene and optionally additionally from a comonomer other than an alkene.
• aliphatic polyolefin is meant a non-aromatic hydrocarbon polyolefin, which may be linear or branched, thus excluding in particular the polymers of an alkene oxide, alkene carbonate and homopolymers and copolymers derived from a vinylaromatic monomer such as styrene.
• apolar aliphatic polyolefins that can be used according to the invention exclude polyolefins with polar functional groups such as halogenated polyolefins, for example polyvinylidene polyfluorides or polyvinylchlorides (PVDF or PVDC), polyhexafluoropropylenes and polytetrafluoroethylenes (PTFE).
• PVDF polyvinylidene polyfluorides or polyvinylchlorides
• PVDF polyhexafluoropropylenes
• PTFE polytetrafluoroethylenes
• said apolar aliphatic polyolefin may be chosen from the group consisting of homopolymers of an aliphatic olefin, copolymers of at least two aliphatic olefins and mixtures thereof.
• the apolar aliphatic polyolefin may be a linear or branched non-halogenated homopolymer of an aliphatic monoolefin, of the type: thermoplastic, preferably chosen from polyethylenes (eg of low or high density, respectively LDPE or HDPE), polypropylenes (PP), polybutenes-1 and polymethylpentenes, or
• elastomer preferably chosen from polyisobutylenes.
• said apolar aliphatic polyolefin may be a linear or branched non-halogenated copolymer of two aliphatic mono-olefins, of the type:
• thermoplastic preferably chosen from ethylene-octene (e.g., non-limiting ELITE® 5230 G), ethylene-butene, propylene-butene and ethylene-butene-hexene copolymers, or
• elastomer preferably chosen from copolymers of ethylene and an alpha-olefin such as, for example, ethylene-propylene copolymers (EPM) and ethylene-propylene-diene terpolymers (EPDM).
• EPM ethylene-propylene copolymers
• EPDM ethylene-propylene-diene terpolymers
• said apolar aliphatic polyolefin may have a mass ratio of units derived from ethylene of greater than 50%, being for example a copolymer predominantly derived from ethylene and in a minor amount from 1-octene, and / or an EPDM.
• these apolar aliphatic polyolefins such as EPDM or polyethylenes, have the advantage of being inexpensive, especially in comparison with the HNBRs and the ethylene-ethyl acrylate copolymers used in the prior art in the melted process.
• said at least one modified polyolefin may be the product of a controlled thermal oxidation reaction, under an atmosphere comprising oxygen at an oxygen partial pressure greater than 10 4 Pa ( 0.1 bar) and at an oxidation temperature between 200 ° C and 300 ° C, said apolar aliphatic polyolefin with the oxygen of said atmosphere, said thermal oxidation reaction being controlled so that said content mass of oxygen atoms in said at least one modified polyolefin is between 2% and 10% inclusive.
• the composition is obtained by melting and without evaporation of solvent, being the product of said thermal oxidation applied to a precursor mixture which comprises a polar sacrificial polymeric phase, said active ingredient, said an electrically conductive filler and said apolar aliphatic polyolefin so that said polar sacrificial polymeric phase and said apolar aliphatic polyolefin form two separate phases in said precursor mixture, the thermal oxidation decomposing said polar sacrificial polymeric phase and oxidizing only said apolar aliphatic polyolefin to produce said reaction binds it to oxygenated groups.
• this precursor mixture of the composition is distinguished from that known from the above-mentioned document WO-A2-2015 / 124835 in which the binder was either dispersed in the continuous sacrificial polymeric phase, or co-continuous with this phase.
• said polar sacrificial polymeric phase usable in this first mode preferably comprises at least one polymer of an alkene carbonate, and may be present in a residual form and degraded in the composition finally obtained.
• the composition is obtained by a liquid route, being the product of said thermal oxidation applied to a precursor mixture comprising said active material, said electrically conductive filler and said apolar aliphatic polyolefin which are dissolved or dispersed. in a solvent evaporated prior to said thermal oxidation reaction.
• said polymeric binder is not crosslinked, and may consist of said at least one modified polyolefin.
• the composition may comprise: - According to a mass fraction greater than 85% and preferably equal to or greater than 90%, said active material which comprises a lithium-ion battery grade graphite when said electrode is an anode (this graphite is for example artificial graphite C-NERGY ® L-SERIES of Timcal or of one of the PGPT100, PGPT200, PGPT202 series of Targray) or, when said electrode is a cathode, an alloy of lithiated oxides of transition metals preferably selected from the group consisting of alloys lithiated oxides of nickel, manganese and cobalt (NMC) and lithiated oxide alloys of nickel, cobalt and aluminum (NCA),
• NMC manganese and cobalt
• NCA lithiated oxide alloys of nickel, cobalt and aluminum
• said polymeric binder having a mass fraction of less than 5%, preferably of between 2% and 4%, and
• said electrically conductive charge which is selected from the group consisting of carbon blacks in particular of high purity, expanded graphites, carbon fibers, carbon nanotubes, graphenes and their mixtures, according to a mass fraction of between 1
• this mass fraction of more than 85% of said active material in the electrode composition contributes to imparting high performance to the lithium-ion battery incorporating it.
• a method of preparation according to the invention of an electrode composition as defined above comprises successively:
• composition comprising said active ingredient, at least one said apolar aliphatic polyolefin and said electrically conductive filler, for obtaining a precursor mixture of said composition
• a film deposit of said precursor mixture on a metal current collector and c) a thermal oxidation reaction of said film under an atmosphere comprising oxygen at an oxygen partial pressure of greater than 10 4 Pa and at an oxidation temperature of between 200 ° C and 300 ° C, preferably higher at 240.degree. C. and below 290.degree. C. for a variable oxidation period (which may vary from a few minutes to 30 minutes or more), by controlling said thermal oxidation reaction so that, in the composition obtained, said atomic mass content oxygen in said at least one modified polyolefin with CO and OH oxygen groups is between 2% and 10% inclusive.
• this method according to the invention requires precise control of said reaction to obtain this particular operation, particularly characterized by this range of oxygen content, representative of the minimum and maximum levels of operation by these groups to be achieved, by adapting the conditions of temperature, pressure and thermal oxidation time at the selected apolar aliphatic polyolefin. Indeed, these conditions can vary considerably from one polymer to another to generate these CO and OH groups and said oxygen content.
• step a) by mixing said ingredients by melt and without evaporation of solvent, said ingredients further comprising a polar sacrificial polymeric phase which preferably comprises at least one polymer of an alkene carbonate and which is present in said precursor mixture in a volume fraction preferably greater than 30% and even more preferably greater than 40%, said apolar aliphatic polyolefin and said polar sacrificial phase forming, after said mixing, two separate phases in said precursor mixture, and
• step c) by a controlled temperature rise of a starting temperature preferably between 40 ° C. and 60 ° C. at said oxidation temperature and then by an isotherm at said oxidation temperature during said period of time; oxidation, to eliminate at least partially said polar sacrificial polymeric phase by thermal decomposition.
• said polar sacrificial polymeric phase may advantageously comprise:
• a poly (alkene carbonate) polyol having a weight-average molecular mass of between 500 g / mol and 5000 g / mol, and
• step a) by liquid grinding said ingredients dissolved or dispersed in a solvent
• step c) by a controlled annealing of said film at said oxidation temperature, after evaporation of said solvent following step b).
• an agent for solubilizing said apolar aliphatic polyolefin in the solvent especially in the case where the latter is a thermoplastic homopolymer or copolymer of ethylene (eg a polyethylene or copolymer ethylene-octene), this agent being, for example, dichlorobenzene.
• An electrode according to the invention is able to form an anode or a cathode of lithium-ion battery, and it comprises: a film which consists of a composition as defined above including said first and second modes and which has a thickness of at least 50 ⁇ , for example between 50 ⁇ and 100 ⁇ , and
• the electrode may be able to confer on the lithium-ion battery incorporating a first charge-discharge efficiency greater than 60%, said first charge-discharge cycle being implemented at a rate of C / 5 between 1 V and 10 mV for an anode and between 4.3 V and 2.5 V for a cathode.
• said film consists of a composition obtained by molten liver as presented above, and the electrode may advantageously be able to confer on the lithium-ion battery incorporating said yield of first charge-discharge cycle that is greater than 75%.
• the electrode may be an anode comprising a lithium-ion battery grade graphite for said active material, and may advantageously be able to confer on the lithium-ion battery incorporating it for cycles implemented between 1 V and 10 mV:
• said charge-discharge first cycle efficiency which is greater than 85% and preferably greater than 88%, and / or
• a capacity at a C / 5 rate greater than 250 mAh / g of electrode and preferably equal to or greater than 275 mAh / g of electrode, and / or
• a retention rate of capacity at a C / 5 regime after 20 cycles relative to the first cycle which is equal to or greater than 95% and for example 100%.
• the electrode may be a cathode comprising an alloy of lithiated oxides of transition metals preferably selected from the group consisting of alloys of lithiated oxides of nickel, manganese and cobalt (NMC) and alloys lithiated oxides of nickel, cobalt and aluminum (NCA) for said active ingredient, the electrode may advantageously be able to confer on the lithium-ion battery incorporating it for cycles implemented between 4.3 V and 2.5 V:
• a retention rate of capacity at a C / 2 regime with respect to the first cycle which is equal to or greater than 95% and for example of
• a lithium-ion battery according to the invention comprises at least one cell comprising an anode, a cathode and an electrolyte based on a lithium salt and a non-aqueous solvent, and the battery is characterized in that said anode and / or said cathode each consist of an electrode as defined above.
• FIG. 1 is a graph illustrating the absorbance spectra measured by Fourier Transform Infrared Spectroscopy (FTIR for short) showing the evolution of the absorbance as a function of the wavenumber of two elastomer films consisting of a first binder control formed of an unmodified EPDM and a first binder according to the invention formed from the same modified EPDM, and
• FTIR Fourier Transform Infrared Spectroscopy
• FIG. 2 is a graph illustrating the absorbance spectra measured by FTIR showing the evolution of the absorbance as a function of the wavenumber of two thermoplastic films consisting of a second control binder formed of an unmodified polyethylene and a second binder according to the invention formed of the same modified polyethylene.
• ingredients were used: a) as anode active material, an artificial graphite grade lithium-ion battery;
• d) as a solvent for the liquid route, heptane (Aldrich); e) as a sacrificial polymeric phase for the melt process, a blend of two polypropylene carbonates (PPC): a liquid and diol-terminated denomination Converge® Polyol 212-10 of Novomer, present in this phase according to a 65% mass fraction, and the other QPAC® 40 solid from Empower Materials, present in this phase at a mass fraction of 35%;
• PPC polypropylene carbonates
• HNBR Zetpol® 0020 control binder Zeon Chemicals
• f1 a terpolymer according to the invention EPDM Vistalon® 8600 (Exxon Mobil) having a mass content of ethylene of 58.0% and an ethylidene norbornene (ENB) level of 8.9%; or
• Two control anodes C1 and Li-ion battery of the invention 11 were made by mixing the ingredients a), c1), d), f1) in a ball mill and then coating the dispersion obtained after mixing on a metal strip forming a current collector, subsequent drying and annealing.
• the active material, the conductive filler and the binder (dissolved in heptane with a 1: 10 weight ratio) were first mixed in heptane by grinding in a ball mill for 3 minutes. at 350 rpm.
• the dispersions obtained were then coated on a bare copper strip of thickness 12 ⁇ , using an opening squeegee of 150 ⁇ . After evaporation of the solvent at 60 ° C for 2 hours, the coated film was annealed at 250 ° C for 30 min. for the anode 11 of the invention by a controlled oxidation of the film in ambient air having the effect of modifying the EPDM binder as explained below in connection with FIG. 1, it being specified that the control anode C1 was obtained without this annealing. A final thickness was obtained for each of the two anodes ranging from 50 m to 100 ⁇ .
• the anode compositions C1, 11 thus obtained each had the following formulation, expressed in mass fractions:
• the mixtures thus obtained were calendered at room temperature using an external Scamex cylinder mixer until a film thickness of 200 ⁇ was obtained, then they were further calendered at 50 ° C. to reach a thickness of 50. ⁇ .
• the resulting films were deposited on a copper collector using a 70 ° C sheet-fed calender.
• the anode and cathode precursor films were placed in an oven to extract the sacrificial phase (solid and liquid CPAP). They were subjected to a controlled ramp temperature of 50 ° C to 250 ° C and an isotherm of 30 min. at 250 ° C by subjecting them to thermal oxidation in ambient air, to decompose this sacrificial phase and functionalize the corresponding binder f0), f1) or f2).
• binder f1 modified according to the invention for 14 and binder f2) modified according to the invention for 15.
• cathode 14 ' has been obtained by the same molten protocol, which differs only from the cathode 14, in that its final thickness was 80 ⁇ instead of the 50 ⁇ obtained for 14.
• the composition of the cathode 14 ' was thus obtained from the same precursor mixture as for 14 and presented the same formulation as that of 14 after elimination of the same sacrificial phase e).
• FTIR FTIR
• spectroscopy giving absorbance spectra as a function of the wavenumber.
• first Cf1 films 100 ⁇ thick each formed of the binder f1) consisting of Vistalon® 8600 EPDM, and five five-part Cf1 films were deposited on copper by evaporation of a solution in heptane.
• each of the first and second films Cf1 and Cf2 thus deposited for 30 min. at 250 ° C. under ambient air, so as to obtain the CO and OH groups modifying these binders f1 and f2) according to the invention.
• Each of the films Cf1, If1, Cf2, If2 was then studied by FTIR in "ATR" mode (for "attenuated total reflectance" in English, ie attenuated total reflectance).
• the mass ratio of oxygen atoms in each of the five second If2 films of this polyethylene modified by elemental analysis was measured, and an average value of 4.5% with a standard deviation was found for this rate. 0.65% for the five measurements.
• Protocol for electrochemical characterization of liquid prepared C1 and 11 anodes, melted anodes C2 and 12, 13 and molten cathodes 14, 15, 14 ' The anodes were punched out C1, C2, 11, 12, 13 and the cathodes 14, 15, 14 '(diameter 16 mm, area 2.01 cm 2 ) and weighed. The mass of active material was determined by subtracting the mass of the bare current collector prepared under the same conditions (heat treatments). They were put in an oven directly connected to a glove box. They were dried at 100 ° C under vacuum for 12 hours and then transferred to the glove box (argon atmosphere: 0.1 ppm H 2 O and 0.1 ppm O 2 ).
• the button cells (CR1620 format) were then assembled using a lithium metal counter-electrode, a Cellgard 2500 separator and a LiPF6 EC / DMC battery grade electrolyte (50% / 50% by mass ratio). Batteries were characterized on a Biostat VMP3 potentiostat, realizing:
• Table 1 below gives the results of this characterization for the anodes C1, 11, C2, 12, 13 and the cathodes 14, 15 within each cell thus obtained.
• Table 1 further shows that the cathodes 14 and 15 obtained by melt respectively with EPDM and polyethylene binders, each modified by the same controlled thermal oxidation, gave the cells incorporating them with C / 2, C, 2C and 5C capacities. similar and satisfactory.
• Table 2 shows that the cathode 14 'obtained by melt with the EPDM binder modified by this same controlled thermal oxidation also conferred on the battery incorporating satisfactory C / 5 and C / 2 capacities, with in particular a very high degree of cyclability. satisfactory after 20 and even 40 cycles (see the rate of retention of capacity at C / 2 after 20 and 40 cycles which is 100%).

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• 2017
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