Use of 2,3,3,3-tetrafluoropropene for cooling batteries with oxide-type positive electrodes

Abstract

The present invention relates to the use of a refrigerant comprising 2,3,3,3-tetrafluoropropene for cooling a battery of an electric vehicle comprising at least one electrochemical cell having an anode, a cathode and an electrolyte, wherein the cathode is a refrigerant of the formula LiNi x Mn y Co z O2 [wherein x+y+z=1, x>y and x>z] or a compound of formula LiNi x’ Co y’ Al z’ wherein x'+y'+z'=1, x'>y' and x'>z'.

Description

[Technical Field]

[0001] The present invention relates to the use of 2,3,3,3-tetrafluoropropene for cooling batteries containing oxide type positive electrodes. [Background technology]

[0002] It is known to use a vapor compression circuit in vehicles to provide heating or cooling, with the refrigerant circulating through the circuit and thus undergoing evaporation, followed by compression, condensation and expansion to complete the cycle.

[0003] 2,3,3,3-Tetrafluoropropene (HFO-1234yf) is a hydrofluoroolefin that exhibits thermodynamic and thermophysical properties that make it highly favorable for use as a refrigerant, particularly in refrigeration, air conditioning, power production (especially via the Rankine cycle), and heat pump applications. In addition, this product is particularly advantageous because it also exhibits a low global warming potential (GWP).

[0004] Electric vehicles include batteries that contain electrochemical cells. Each electrochemical cell includes a negative electrode, a positive electrode, a separator, and an electrolyte. Depending on the nature of the materials present in the cell, the performance of the battery may be more or less affected depending on the temperature, and in fact the battery may even degrade more or less.

[0005] Document FR2937906 describes a method for heating and / or air conditioning the passenger compartment of an electric vehicle using a reversible cooling loop in which a refrigerant containing 2,3,3,3-tetrafluoropropene circulates. This method is also suitable for hybrid vehicles, designed to run alternately on a heat engine and an electric motor.

[0006] Document EP 2880739 discloses a system for charging electric vehicle batteries, which makes it possible to simultaneously control the temperature of the battery and the temperature of the passenger compartment of the vehicle.

[0007] Document US Pat. No. 5,305,613 describes a system for heating and air conditioning the passenger compartment of an electric vehicle, which is operated before starting the vehicle to increase the comfort of the driver.

[0008] Document US 2015 / 0191072 describes a cooling cycle that makes it possible to perform a heating or air conditioning function, in particular to blow hot air onto the battery.

[0009] The document US 2011 / 0139397 describes a method for controlling the temperature of the interior of an electric vehicle by means of a refrigerant circuit, which is in particular connected to a battery.

[0010] There is a need to ensure optimal performance of electric vehicle batteries and to prevent battery degradation. Summary of the Invention

[0011] The present invention relates to the use of a refrigerant comprising 2,3,3,3-tetrafluoropropene for cooling a battery of an electric vehicle comprising at least one electrochemical cell comprising a negative electrode, a positive electrode and an electrolyte, wherein the positive electrode is a refrigerant of the formula LiNi x Mn y Co z O2 [wherein x+y+z=1, x>y and x>z] or a compound of formula LiNi x’ Co y’ Al z’ wherein x'+y'+z'=1, x'>y' and x'>z'.

[0012] In some embodiments, the battery is maintained at a temperature between a minimum temperature t1 and a maximum temperature t2.

[0013] In some embodiments, the minimum temperature t1 is 10°C or higher and the maximum temperature t2 is 40°C or lower, preferably the minimum temperature t1 is 15°C or higher and the maximum temperature t2 is 30°C or lower, and more preferably the minimum temperature t1 is 16°C or higher and the maximum temperature t2 is 28°C or lower.

[0014] In some embodiments, the refrigerant circulates through a vapor compression circuit.

[0015] In some embodiments, the vapor compression circuit is also suitable for heating the passenger compartment of a vehicle and / or for air conditioning the passenger compartment of a vehicle and / or for heating the battery of a vehicle.

[0016] In some embodiments, the refrigerant consists essentially of 2,3,3,3-tetrafluoropropene.

[0017] In some embodiments, the refrigerant comprises about 78.5% by weight 2,3,3,3-tetrafluoropropene and about 21.5% by weight difluoromethane.

[0018] The present invention also provides a method of conditioning a battery of an electric vehicle, the battery comprising at least one electrochemical cell including a negative electrode, a positive electrode and an electrolyte, the positive electrode having a structure of the formula LiNi x Mn y Co z O2 [wherein x+y+z=1, x>y and x>z] or a compound of formula LiNi x’ Co y’ Al z’ wherein x'+y'+z'=1, x'>y' and x'>z'; and the method comprises: - A method comprising cooling a battery with a refrigerant comprising 2,3,3,3-tetrafluoropropene.

[0019] In some embodiments, the method comprises: - Maintain the vehicle battery at a temperature between minimum temperature t1 and maximum temperature t2 Includes:

[0020] In some embodiments, the minimum temperature t1 is 10°C or higher and the maximum temperature t2 is 40°C or lower, preferably the minimum temperature t1 is 15°C or higher and the maximum temperature t2 is 30°C or lower, and more preferably the minimum temperature t1 is 16°C or higher and the maximum temperature t2 is 28°C or lower.

[0021] In some embodiments, maintaining the vehicle's battery at a temperature between t1 and t2 is performed by alternating between cooling the battery with a refrigerant and heating the battery.

[0022] In some embodiments, heating of the battery is performed by a refrigerant and / or heating of the battery is performed by electrical resistance.

[0023] In some embodiments, the refrigerant circulates through a vapor compression circuit.

[0024] In some embodiments, the refrigerant consists essentially of 2,3,3,3-tetrafluoropropene.

[0025] In some embodiments, the refrigerant comprises about 78.5% by weight 2,3,3,3-tetrafluoropropene and about 21.5% by weight difluoromethane.

[0026] The present invention makes it possible to meet the above-mentioned demands, since it is possible to provide a battery for an electric vehicle, more particularly an electrochemical cell having the formula LiNi x Mn y Co z O2 or LiNi x Co y Al z [where x>y and x>z] as electrochemically active materials. These "high nickel content" materials exhibit many advantages, in particular higher capacity and higher nominal voltage.

[0027] On the other hand, it has been observed that at relatively high temperatures, these materials are prone to deoxidation, which in turn releases oxygen and can cause a combustion reaction with the electrolyte, resulting in irreversible damage (fire, indeed even explosion) to the vehicle.

[0028] The use of 2,3,3,3-tetrafluoropropene as a refrigerant for cooling such batteries has been found to be particularly effective in maintaining the functionality and integrity of the batteries. DETAILED DESCRIPTION OF THE INVENTION

[0029] The invention will now be described in greater detail and in a non-limiting manner in the description that follows.

[0030] Electric vehicle batteries The term "electric vehicle" (optionally "hybrid") is understood to mean an electrically powered device capable of moving or transporting people or materials, the motor of which is supplied with electrical energy (preferably entirely, but possibly only partially in the case of hybrid electric vehicles) by a motor battery, which is more simply called a "battery" in the context of this patent application.

[0031] The electric vehicle is preferably an electric car. Alternatively, the electric vehicle may be an electric truck or an electric bus.

[0032] A battery includes at least one electrochemical cell, and preferably a plurality of electrochemical cells, each of which includes a negative electrode, a positive electrode, and an electrolyte interposed between the negative and positive electrodes.

[0033] Each electrochemical cell may also include a separator impregnated with an electrolyte.

[0034] In a battery, the electrochemical cells can be assembled in series and / or in parallel.

[0035] The term "negative electrode" is understood to mean the electrode that acts as an anode when the battery carries current (i.e., when the battery is in the process of discharging) and as a cathode when the battery is in the process of charging.

[0036] The negative electrode typically comprises an electrochemically active material, optionally an electronically conductive material, and optionally a binder.

[0037] The term "positive electrode" is understood to mean the electrode that acts as a cathode when the battery carries current (i.e., when the battery is in the process of discharging) and as an anode when the battery is in the process of charging.

[0038] The positive electrode typically comprises an electrochemically active material, optionally an electronically conductive material, and optionally a binder.

[0039] The term "electrochemically active material" is understood to mean a material capable of reversibly inserting ions.

[0040] The term "electron-conducting material" is understood to mean a material that is capable of conducting electrons.

[0041] The negative electrode of the electrochemical cell is made of, in particular, graphite, lithium, lithium alloys, type Li4Ti5O, as electrochemically active material. 12 The material may comprise one of lithium titanate or titanium oxide TiO2, silicon or an alloy of lithium and silicon, tin oxide, a lithium intermetallic compound, or a mixture thereof.

[0042] When the negative electrode contains lithium, it can be in the form of a metallic lithium film or an alloy containing lithium. For example, among the lithium-based alloys that can be used, mention can be made of lithium-aluminum alloys, lithium-silica alloys, lithium-tin alloys, Li-Zn, Li3Bi, Li3Cd, and Li3SB. An example of a negative electrode can include an active lithium film prepared by rolling a lithium strip between rollers.

[0043] The positive electrode contains an oxide-type electrochemically active material, which is a lithium / nickel / manganese / cobalt composite oxide [LiNi x Mn y Co z O2 (where x+y+z=1), abbreviated as NMC, where x>y and x>z.], or lithium / nickel / cobalt / aluminum composite oxide with a high nickel content [LiNi x’ Co y’ Al z’ (where x'+y'+z'=1), abbreviated as NCA, where x'>y' and x'>z'.

[0044] Specific examples of these oxides are NMC532(LiNi 0.5 Mn 0.3 Co 0.2 O2), NMC622(LiNi 0.6 Mn 0.2 Co 0.2 O2) and NMC811(LiNi 0.8 Mn 0.1 Co 0.1 O2).

[0045] Mixtures of these oxides may be used. The above oxide materials may, where appropriate, be combined with other oxides, such as manganese dioxide (MnO), iron oxide, copper oxide, nickel oxide, lithium / manganese composite oxides (e.g., Li x Mn2O4 or Li x MnO2), lithium / nickel composition oxide (e.g., Li xNiO2), lithium / cobalt oxides (e.g., Li x CoO2), lithium / nickel / cobalt composite oxides (e.g., LiNi 1-y Co y O2), lithium / transition metal composite oxides, lithium / manganese / nickel composite oxides with spinel structure (e.g., Li x Mn 2-y Ni y O4), vanadium oxide, NMC and NCA oxides that do not have a high nickel content, and mixtures thereof.

[0046] Preferably, the NMC or NCA oxide having a high nickel content represents at least 50% by weight, preferably at least 75% by weight, more preferably at least 90% by weight, and more preferably essentially all of the oxide material present in the positive electrode as the electrochemically active material.

[0047] In addition to the electrochemically active material, the material of each electrode can also include an electronically conductive material such as a carbon source, including, for example, carbon black, Ketjen® carbon, Shawinigan carbon, graphite, graphene, carbon nanotubes, carbon fibers (e.g., vapor-grown carbon fibers or VGCF), non-powdered carbon obtained by carbonization of organic precursors, or a combination of two or more thereof. Other additives, such as lithium salts or ceramic or glass-type inorganic particles, or even other compatible active materials (e.g., sulfur), can also be present in the material of the positive electrode.

[0048] The material of each electrode may also include a binder. Non-limiting examples of binders include linear, branched, and / or crosslinked polyether polymer binders (e.g., polymers based on poly(ethylene oxide) (PEO) or poly(propylene oxide) (PPO) or a mixture of the two (or EO / PO copolymers), optionally containing crosslinkable units), water-soluble binders (e.g., SBR (styrene / butadiene rubber), NBR (acrylonitrile / butadiene rubber), HNBR (hydrogenated NBR), CHR (epichlorohydrin rubber), ACM (acrylate rubber)), or fluoropolymer-type binders (e.g., PVDF (vinylidene polyfluoride), PTFE (polytetrafluoroethylene)), and combinations thereof. Some binders, such as those that are soluble in water, may also include additives such as CMC (carboxymethyl cellulose).

[0049] The separator may be a porous polymer membrane. As a non-limiting example, the separator may be a porous membrane of a polyolefin, such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, or an ethylene / methacrylate copolymer, or a multilayer structure of the above polymers.

[0050] The electrolyte may consist of one or more lithium salts dissolved in a solvent or a mixture of a solvent and one or more additives.

[0051] As non-limiting examples, the lithium salt or salts may be selected from LiPF6 (lithium hexafluorophosphate), LiFSI (lithium bis(fluorosulfonyl)imide), LiTDI (lithium 2-trifluoromethyl-4,5-dicyanoimidazol- ate), LiPOF2, LiB(C2O4)2, LiF2B(C2O4)2, LiBF4, LiNO3, or LiClO4.

[0052] The solvent may be selected from the following non-exhaustive list: ethers, esters, ketones, alcohols, nitriles and carbonates.

[0053] Among the ethers, mention may be made of linear or cyclic ethers such as dimethoxyethane (DME), methyl ethers of oligoethylene glycols of 2 to 5 oxyethylene units, dioxolane, dioxane, dibutyl ether, tetrahydrofuran and mixtures thereof.

[0054] Among the esters, mention may be made of phosphates or sulfites, such as methyl formate, methyl acetate, methyl propionate, ethyl acetate, butyl acetate, γ-butyrolactone or mixtures thereof.

[0055] Among the ketones, particular mention may be made of cyclohexanone.

[0056] Among the alcohols, mention may be made, for example, of ethyl alcohol or isopropyl alcohol.

[0057] Among the nitriles, mention may be made, for example, of acetonitrile, pyruvonitrile, propionitrile, methoxypropionitrile, dimethylaminopropionitrile, butyronitrile, isobutyronitrile, valeronitrile, pivalonitrile, isovaleronitrile, glutaronitrile, methoxyglutaronitrile, 2-methylglutaronitrile, 3-methylglutaronitrile, adiponitrile, malononitrile and mixtures thereof.

[0058] Among carbonates, for example, cyclic carbonates such as ethylene carbonate (EC) (CAS: 96-49-1), propylene carbonate (PC) (CAS: 108-32-7), butylene carbonate (BC) (CAS: 4437-85-8), dimethyl carbonate (DMC) (CAS: 616-38-6), diethyl carbonate (DEC) (CAS: 105-58-8), ethyl methyl carbonate (EMC) (CAS: 623-53-0), diphenyl carbonate (CAS 102-09-0), methyl phenyl carbonate (CAS: 13509-27-8), dipropyl carbonate (DPC) (CAS: 623-96-1), methyl propyl carbonate (MPC) (CAS: 1333-41-1), ethyl propyl carbonate (EPC), vinylene carbonate (VC) (CAS: 872-36-6), fluoroethylene carbonate (FEC) (CAS: 114435-02-8), trifluoropropylene carbonate (CAS: 167951-80-6) or mixtures thereof.

[0059] The additive may be selected from the group consisting of fluoroethylene carbonate (FEC), vinylene carbonate, 4-vinyl-1,3-dioxolan-2-one, pyridazine, vinylpyridazine, quinoline, vinylquinoline, butadiene, sebaconitrile, alkyl disulfides, fluorotoluene, 1,4-dimethoxytetrafluorotoluene, t-butylphenol, di(t-butyl)phenol, tris(pentafluorophenyl)borane, oximes, aliphatic epoxides, halogenated biphenyls, methacrylic acid, allyl ethyl carbonate, vinyl acetate, divinyl adipate, propane sultone, acrylonitrile, 2-vinylpyridine, maleic anhydride, methyl cinnamate, phosphonates, vinyl-containing silane compounds, and 2-cyanofuran.

[0060] refrigerant In the context of the present invention, "HFO-1234yf" refers to 2,3,3,3-tetrafluoropropene.

[0061] The term "refrigerant" is understood to mean a fluid capable of absorbing heat by evaporating at low temperature and pressure and releasing heat by condensing at high temperature and pressure in a vapor compression circuit, depending on the application under consideration. In general, a refrigerant can consist essentially of a single compound or can be a mixture of several compounds.

[0062] The present invention uses a refrigerant that includes HFO-1234yf. Other heat transfer compounds may or may not be present in the refrigerant in combination with HFO-1234yf.

[0063] The refrigerant may be combined with a lubricant and / or additives to form a thermally conductive composition.

[0064] The thermally conductive composition resides and circulates in a vapor compression circuit.

[0065] In some embodiments, the refrigerant of the present invention consists essentially of, or even actually consists of, HFO-1234yf.

[0066] In other embodiments, the refrigerant comprises HFO-1234yf in a mixture with one or more other heat transfer compounds, such as hydrofluorocarbons and / or hydrofluoroolefins and / or hydrocarbons and / or hydrochlorofluoroolefins and / or CO2.

[0067] Among the hydrofluorocarbons, particular mention may be made of difluoromethane (HFC-32), pentafluoroethane (HFC-125), 1,1,2,2-tetrafluoroethane (HFC-134), 1,1,1,2-tetrafluoroethane (HFC-134a), 1,1-difluoroethane (HFC-152a), fluoroethane (HFC-161), 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea), 1,1,1-trifluoropropane (HFC-263fb), and mixtures thereof.

[0068] Among the hydrofluoroolefins, mention may in particular be made of 1,3,3,3-tetrafluoropropene (HFO-1234ze) in the cis and / or trans form, preferably in the trans form, and trifluoroethylene (HFO-1123).

[0069] Among the hydrochlorofluoroolefins, particular mention may be made of 1-chloro-3,3,3-trifluoropropene (HCFO-1233zd) in the cis and / or trans form, preferably in the trans form.

[0070] In some embodiments, the refrigerant comprises at least 50% by weight HFO-1234yf, or at least 60% by weight HFO-1234yf, or at least 70% by weight HFO-1234yf, or at least 80% by weight HFO-1234yf, or at least 90% by weight HFO-1234yf, or at least 95% by weight HFO-1234yf.

[0071] In certain embodiments, the refrigerant consists essentially of, or even actually consists of, HFO-1234yf and HFC-32. The HFO-1234yf content is preferably about 60% to about 95% by weight, more preferably about 70% to about 90% by weight, more preferably about 75% to about 85% by weight, and more preferably about 78.5% by weight; the HFC-32 content is preferably about 5% to about 40% by weight, more preferably about 10% to about 30% by weight, more preferably about 15% to about 25% by weight, and more preferably about 21.5% by weight.

[0072] Additives that can be added to the refrigerant to form the thermally conductive composition can be selected from nanoparticles, stabilizers, surfactants, tracing agents, fluorescent agents, odorous agents, and solubilizing agents, among others.

[0073] The total amount of additives does not exceed 5%, in particular 4%, more in particular 3%, very in particular 2%, indeed even 1% by weight of the refrigerant.

[0074] In certain embodiments, HFO-1234yf contains impurities, which, if present, may represent less than 1% by weight, preferably less than 0.5% by weight, preferably less than 0.1% by weight, preferably less than 0.05% by weight, preferably less than 0.01% by weight, relative to the HFO-1234yf.

[0075] One or more lubricants may be present in the thermal interface composition, and these lubricants may be selected from polyol esters (POEs), polyalkylene glycols (PAGs), or polyvinyl ethers (PVEs).

[0076] The lubricant may represent from 1% to 50% by weight of the thermally conductive composition, preferably from 2% to 40% by weight, and more preferably from 5% to 30% by weight.

[0077] Vapor compression circuit The cooling of the battery according to the invention is preferably carried out by an installation comprising a vapor compression circuit, which contains the above-mentioned refrigerant, which provides the heat transfer.

[0078] In some embodiments, the vapor compression circuit is also suitable for heating the vehicle's battery.

[0079] In some embodiments, the vapor compression circuit is also suitable for heating the passenger compartment of a vehicle.

[0080] In some embodiments, the vapor compression circuit is also suitable for air conditioning (cooling) the passenger compartment of a vehicle.

[0081] For this purpose, the vapor compression circuit may comprise different branches with separate heat exchangers, through which the refrigerant circulates or does not circulate depending on the operating mode. Optionally, the vapor compression circuit may alternatively or additionally comprise means for changing the direction of refrigerant circulation, including, for example, one or more three-way or four-way valves.

[0082] The main stages of the heat transfer process are carried out cyclically, - Evaporation of the refrigerant in the evaporator; - Compression of the refrigerant in the compressor; - condensation of the refrigerant in the condenser; - Refrigerant expansion in the expansion module Includes:

[0083] Evaporation of the refrigerant can be carried out starting from the liquid phase or from a two-phase liquid / vapor mixture.

[0084] Compressors can be hermetic, semi-hermetic, or open. Hermetic compressors include a motor section and a compression section enclosed in a nondismantlable hermetic housing. Semi-hermetic compressors include a motor section and a compression section assembled directly to each other. The coupling between the motor section and the compression section is accessible when the two sections are separated by disassembly. Open compressors include separate motor and compression sections. They can be operated by belt drive or by direct coupling.

[0085] In particular, the compressor may be a dynamic compressor or a positive displacement compressor.

[0086] Dynamic compressors include axial and centrifugal compressors, which may have one or more stages. Mini-centrifugal compressors may also be used.

[0087] Positive displacement compressors include rotary compressors and reciprocating compressors.

[0088] Reciprocating compressors include diaphragm compressors and piston compressors.

[0089] Rotary compressors include screw compressors, lobe compressors, scroll (or helical) compressors, liquid ring compressors and vane compressors. Screw compressors may preferably be twin screw or single screw.

[0090] The practice of the present invention is particularly advantageous when using a scroll compressor due to its good efficiency under conditions typical of electric vehicles.

[0091] In the installations in which it is used, the compressor may include a device for injecting vapor or liquid, which consists in introducing refrigerant in liquid or vapor state into the compressor at a level intermediate between the beginning and the end of compression.

[0092] In the installations in which it is used, the compressor may be driven by an electric motor, or by a gas turbine (for example supplied by the exhaust gases of a vehicle) or by gearing.

[0093] The evaporator and the condenser are heat exchangers. In the present invention, any type of heat exchanger can be used, in particular a parallel flow heat exchanger, or preferably a counter flow heat exchanger.

[0094] The term "countercurrent heat exchanger" is understood to mean a heat exchanger in which heat is exchanged between a first fluid and a second fluid, with a first fluid at the inlet of the exchanger exchanging heat with a second fluid at the outlet of the exchanger and the first fluid at the outlet of the exchanger exchanging heat with a second fluid at the inlet of the exchanger.

[0095] For example, a countercurrent heat exchanger includes a device in which the flow of a first fluid and the flow of a second fluid are in opposite or substantially opposite directions. Also included among countercurrent heat exchangers are exchangers that operate in a countercurrent mode with a countercurrent trend.

[0096] The heat exchanger may in particular be an exchanger with U-tubes, horizontal or vertical tube bundles, spirals, plates or fins.

[0097] The equipment can also optionally include at least one heat transfer fluid circuit used to transfer heat (with or without a change of state) between the circuit of the heat transfer composition and the battery. Preferably, the equipment does not include a heat transfer fluid circuit used to transfer heat between the circuit of the heat transfer composition and the battery. It is also possible to provide a heat exchanger in the circuit containing the heat transfer composition to ensure the exchange of heat between the refrigerant and the air, which is then blown over the battery to ensure the exchange of heat with the battery itself. However, preferably, the heat exchanger in the circuit containing the heat transfer composition is in contact with the battery or is integrated into the battery.

[0098] The equipment can also optionally include two (or more) vapor compression circuits containing the same or different thermal interface compositions. For example, multiple vapor compression circuits can be connected to each other. Preferably, however, the equipment includes a single vapor compression circuit.

[0099] According to the invention, the refrigerant can be superheated between evaporation and compression, ie, between evaporation and compression, the refrigerant can be brought to a temperature higher than the temperature at which evaporation ends.

[0100] The term "evaporation onset temperature" is understood to mean the temperature of the refrigerant at the inlet of the evaporator.

[0101] The term "evaporation end temperature" is understood to mean the temperature of the last drop of refrigerant in liquid form during evaporation (saturated vapor temperature or dew point).

[0102] When the refrigerant is HFO-1234yf alone or an azeotropic mixture containing HFO-1234yf, the evaporation start temperature is equal to the evaporation end temperature under a constant pressure.

[0103] The term "superheat" (herein equivalent to "superheat in the evaporator") means the temperature difference between the maximum temperature reached by the refrigerant before compression (i.e. the maximum temperature reached by the refrigerant at the end of the superheating stage) and the evaporation end temperature. This maximum temperature is generally the temperature of the refrigerant at the inlet of the compressor. It may correspond to the temperature of the refrigerant at the outlet of the evaporator. Alternatively, the refrigerant may be at least partially superheated between the evaporator and the compressor (for example by an internal exchanger). The superheat can be regulated by appropriate management of the installation parameters, in particular by management of the expansion module.

[0104] In the method of the present invention, the heating can be from 1 to 25°C, preferably from 2 to 10°C, preferably from 3 to 7°C, more preferably from 4 to 6°C.

[0105] According to the invention, the refrigerant can be subcooled between condensation and expansion, ie between condensation and expansion, the refrigerant can be brought to a temperature below the end temperature of condensation.

[0106] The term "condensation onset temperature" is understood to mean the temperature of the refrigerant during the appearance of the first drop of refrigerant in the condenser, also called the vapor saturation temperature or dew point.

[0107] The term "condensation end temperature" is understood to mean the temperature of the refrigerant during which the last bubbles of the refrigerant in gaseous form condense, and is also called the saturation temperature or bubble point of the liquid.

[0108] The term "subcooling" (herein equivalent to "subcooling in the condenser") refers to the possible temperature difference (in absolute value) between the minimum temperature reached by the refrigerant before expansion (i.e., the minimum temperature reached by the refrigerant at the end of the subcooling phase) and the end-of-condensation temperature. This minimum temperature is generally the temperature of the refrigerant at the inlet of the expansion module. It may correspond to the temperature of the refrigerant at the outlet of the condenser. Alternatively, the refrigerant may be at least partially subcooled between the condenser and the expansion module (e.g., by an internal exchanger).

[0109] In the method of the present invention, if supercooling is present, the supercooling may be from 1 to 50°C, preferably from 1 to 40°C, preferably from 1 to 30°C, preferably from 1 to 20°C, 1 to 15°C, preferably from 1 to 10°C, and more preferably from 1 to 5°C.

[0110] The expansion module can be a thermostatic valve, called a thermostatic or electronic expansion valve with one or more orifices, or a pressure-regulating pressostatic expansion valve. The expansion module can also be a capillary tube, where expansion of the fluid is achieved by a pressure drop within the tube.

[0111] Refrigerant use The present invention relates to the use of a refrigerant comprising HFO-1234yf for cooling the above-mentioned battery.

[0112] The term "temperature of a battery" is generally understood to mean the temperature of the outer wall of one or more electrochemical cells of the battery.

[0113] The temperature of the battery can be measured by a temperature sensor. If several temperature sensors are present in the battery, the temperature of the battery can be considered to be the average value of the different temperatures measured.

[0114] The cooling can be performed when the vehicle battery is charging. Alternatively, the cooling can be performed when the battery is discharging, especially when starting the vehicle engine, to prevent the battery temperature from becoming too high due to the outside temperature and / or due to the heating inherent in the battery during operation.

[0115] In some embodiments, the cooling can reduce the temperature of the battery by at least 5°C, or at least 10°C, or at least 15°C, or at least 20°C, or at least 25°C, or at least 30°C.

[0116] In some embodiments, the cooling of the battery is continuous over a period of time.

[0117] In some embodiments, cooling of the battery is alternated with periods of pause and even periods during which the battery is actually heated, where the battery may be heated by the vapor compression circuit described above and / or by electrical resistance.

[0118] In some embodiments, cooling and optional heating can maintain the battery temperature within an optimum temperature range, especially when the vehicle is in operation (engine running), since battery performance can be significantly reduced if the battery temperature is too low.

[0119] In one embodiment, the temperature of the vehicle's battery is thus maintained between a minimum temperature t1 and a maximum temperature t2.

[0120] In one embodiment, the minimum temperature t1 is 10°C or higher and the maximum temperature t2 is 40°C or lower, preferably the minimum temperature t1 is 15°C or higher and the maximum temperature t2 is 30°C or lower, and more preferably the minimum temperature t1 is 16°C or higher and the maximum temperature t2 is 28°C or lower.

[0121] Advantageously, a feedback loop exists to modify the operating parameters of the equipment as a function of the measured battery temperature in order to ensure that the desired temperature is maintained.

Claims

1. Use of a refrigerant comprising 2,3,3,3-tetrafluoropropene for cooling a battery of an electric vehicle comprising at least one electrochemical cell comprising an anode, a cathode and an electrolyte, wherein the cathode is a refrigerant of the formula LiNi ｘ Mn ｙ Co ｚ O ２ [wherein x + y + z = 1, x > y and x > z], or a compound of the formula LiNi ｘ’ Co ｙ’ Al ｚ’ O2, where x'+y'+z'=1, x'>y' and x'>z', as an electrochemically active material; the coolant comprises 78.5% by weight of 2,3,3,3-tetrafluoropropene and 21.5% by weight of difluoromethane; and the main stage of the heat transfer process is carried out cyclically; - evaporation of the refrigerant in the evaporator, - Compression of the refrigerant in the compressor, - condensation of the refrigerant in the condenser, and - Refrigerant expansion in the expansion module wherein the refrigerant is superheated between evaporation and compression, the superheat being 1 to 25°C.

2. When the battery reaches the lowest temperature (t １ ) and maximum temperature (t ２ 2. The method of claim 1, wherein the temperature is maintained between 0.5 and 100°C.

3. Minimum temperature (t １ ) is 10 ° C or more and the maximum temperature (t ２ 3. The use according to claim 2, wherein the temperature is 40°C or less.

4. 4. The use according to any one of claims 1 to 3, wherein the refrigerant circulates in a vapor compression circuit.

5. 5. Use according to claim 4, wherein the vapor compression circuit is also used to provide heating for the passenger compartment of the vehicle and / or air conditioning for the passenger compartment of the vehicle and / or heating for the battery of the vehicle.

6. 1. A method of conditioning a battery of an electric vehicle, the battery comprising at least one electrochemical cell including a negative electrode, a positive electrode, and an electrolyte, the positive electrode comprising a compound of the formula LiNi ｘ Mn ｙ Co ｚ O ２ [Wherein, x + y + z = 1, x > y and x > z.], or LiNi ｘ’ Co ｙ’ Al ｚ’ 02, wherein x'+y'+z'=1, x'>y' and x'>z', as an electrochemically active material, and the method comprises: - cooling the battery with a refrigerant containing 78.5% by weight of 2,3,3,3-tetrafluoropropene and 21.5% by weight of difluoromethane; Including, The main stages of the heat transfer process are carried out cyclically, - evaporation of the refrigerant in the evaporator, - Compression of the refrigerant in the compressor, - condensation of the refrigerant in the condenser, and - Refrigerant expansion in the expansion module wherein the refrigerant is superheated between evaporation and compression, the superheat being 1 to 25°C.

7. - Keep the vehicle battery at a minimum temperature (t １ ) and maximum temperature (t ２ ) and maintain the temperature between The method of claim 6, comprising:

8. Minimum temperature (t １ ) is 10 ° C or more and the maximum temperature (t ２ 8. The method of claim 7, wherein the temperature is 40° C. or less.

9. The vehicle battery is kept at a minimum temperature (t １ ) and maximum temperature (t ２ 9. The method of claim 7 or 8, wherein maintaining the battery at a temperature between 0.5 and 1.0°C is performed alternately by cooling the battery with a refrigerant and by heating the battery.

10. 10. The method of claim 9, wherein the heating of the battery is performed by a coolant and / or the heating of the battery is performed by electrical resistance.

11. 11. A method according to any one of claims 6 to 10, wherein the refrigerant circulates in a vapor compression circuit.