Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M6/00—Primary cells; Manufacture thereof
  • H01M6/14—Cells with non-aqueous electrolyte
  • H01M6/16—Cells with non-aqueous electrolyte with organic electrolyte
  • H01M6/162—Cells with non-aqueous electrolyte with organic electrolyte characterised by the electrolyte
  • H01M6/164—Cells with non-aqueous electrolyte with organic electrolyte characterised by the electrolyte by the solvent
• • 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
  • H01M10/056—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
  • H01M10/0566—Liquid materials
  • H01M10/0569—Liquid materials characterised by the solvents
• • 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
  • H01M10/05—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
  • H01M10/0566—Liquid materials
  • H01M10/0568—Liquid materials characterised by the solutes
• • 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
  • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
  • H01M4/381—Alkaline or alkaline earth metals elements
  • H01M4/382—Lithium
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M6/00—Primary cells; Manufacture thereof
  • H01M6/14—Cells with non-aqueous electrolyte
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M6/00—Primary cells; Manufacture thereof
  • H01M6/14—Cells with non-aqueous electrolyte
  • H01M6/16—Cells with non-aqueous electrolyte with organic electrolyte
  • H01M6/162—Cells with non-aqueous electrolyte with organic electrolyte characterised by the electrolyte
  • H01M6/166—Cells with non-aqueous electrolyte with organic electrolyte characterised by the electrolyte by the solute
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M6/00—Primary cells; Manufacture thereof
  • H01M6/14—Cells with non-aqueous electrolyte
  • H01M6/16—Cells with non-aqueous electrolyte with organic electrolyte
  • H01M6/162—Cells with non-aqueous electrolyte with organic electrolyte characterised by the electrolyte
  • H01M6/168—Cells with non-aqueous electrolyte with organic electrolyte characterised by the electrolyte by additives
• • 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
  • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
  • H01M2004/027—Negative electrodes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M2300/00—Electrolytes
  • H01M2300/0017—Non-aqueous electrolytes
  • H01M2300/0025—Organic electrolyte
  • H01M2300/0028—Organic electrolyte characterised by the solvent
  • H01M2300/0034—Fluorinated solvents
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M2300/00—Electrolytes
  • H01M2300/0017—Non-aqueous electrolytes
  • H01M2300/0025—Organic electrolyte
  • H01M2300/0028—Organic electrolyte characterised by the solvent
  • H01M2300/0037—Mixture of solvents
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M2300/00—Electrolytes
  • H01M2300/0017—Non-aqueous electrolytes
  • H01M2300/0025—Organic electrolyte
  • H01M2300/0028—Organic electrolyte characterised by the solvent
  • H01M2300/0037—Mixture of solvents
  • H01M2300/004—Three solvents
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M2300/00—Electrolytes
  • H01M2300/0017—Non-aqueous electrolytes
  • H01M2300/0025—Organic electrolyte
  • H01M2300/0028—Organic electrolyte characterised by the solvent
  • H01M2300/0037—Mixture of solvents
  • H01M2300/0042—Four or more solvents
• • 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
  • H01M4/134—Electrodes based on metals, Si or alloys
• • 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
  • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
  • H01M4/40—Alloys based on alkali metals
  • H01M4/405—Alloys based on lithium
• • 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
• • 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 of the invention is that of electrolyte compositions for electrochemical elements comprising an anode based on lithium metal or based on a lithium alloy.
• element used designates an electrochemical element.
• element and “electrochemical element” will be used interchangeably in the following.
• Primary electrochemical elements of lithium / manganese dioxide type are known from the state of the art. They comprise at least one anode of lithium or of a lithium alloy and at least one cathode, the active material of which is manganese dioxide Mn0 2 .
• the anode and the cathode are impregnated with a liquid organic electrolyte.
• a porous insulator or separator separates the anode and the cathode while allowing the passage of ions.
• the lithium in the anode oxidizes to Li + ions.
• manganese dioxide at oxidation degree + IV is reduced and reacts with Li + ions to form LiMnC at oxidation degree + III.
• the reactions at the electrodes can be summarized as follows:
• the overall discharge reaction of the element is: Li + Mn0 2 -> LiMn0 2 .
• a lithium manganese dioxide type element has interesting characteristics, for example, a relatively high open-circuit voltage of about 3.2 V, a nominal operating voltage of about 3.0 V, and a high electrochemical capacity. Its discharge voltage is stable over almost the entire discharge. It can operate over a wide temperature range from -55 to + 85 ° C.
• An organic liquid electrolyte comprising an organic solvent, a lithium salt and an additive which is an inorganic oxide to which is attached a hydroxide group or a C1 to C10 alkyl group.
• This additive is said to suppress the formation and growth of dendrites on the surface of the lithium anode. This reduces the interfacial resistance between the lithium anode and the electrolyte and therefore improves the mobility of lithium ions. As a result, the life of the element is increased. It can be noted that this document teaches that the presence of carbonates in the electrolyte promotes the formation of dendrites on the surface of the anode and that the presence of these dendrites very significantly reduces the life of the element.
• the subject of the invention is an electrolyte composition comprising:
• said at least one monofluorinated or difluorinated or trifluorinated saturated cyclic carbonate representing at most 1.5% of the mass of solvent
• said at least one ether representing at least 40% of the mass of solvent
• lithium difluorophosphate in an amount representing from 0.1% to 1% relative to the sum of the mass of solvent and the mass of said at least one lithium salt.
• the lithium salt is lithium perchlorate LiClCE.
• said monofluorinated or difluorinated or trifluorinated saturated cyclic carbonate is ethylene monofluorocarbonate (FEC).
• said at least one monofluorinated or difluorinated or trifluorinated saturated cyclic carbonate represents from 0.5% to 1% of the mass of solvent.
• the mixture of at least two saturated cyclic carbonates represents at least 30% of the mass of solvent.
• the mixture of at least two saturated cyclic carbonates represents less than 50% of the mass of solvent.
• said at least one ether is chosen from tetrahydrofuran, 1,3-dioxolane and a mixture of these.
• said at least one ether represents at most 75% of the mass of solvent.
• said at least one ether represents at most 65% of the mass of solvent.
• said at least one ether represents at least 50% of the mass of solvent
• said at least one ether represents at least 60% of the mass of solvent.
• the mixture of at least two saturated cyclic carbonates is:
• the subject of the invention is also an electrochemical element comprising:
• the anode can be metallic lithium or a lithium alloy, for example lithium and aluminum.
• the electrochemical element can be of the primary type.
• the technology of the primary element can be chosen from the following technologies: lithium / MnCh, lithium / CF x , lithium / FeS2, lithium / VO and lithium / L.
• Figure 4 shows the average of the voltage values of three elements of type A and D measured during current taps at a current of C / 6 (83 mA), at a temperature of -40 ° C. These elements were previously freshly filled with electrolyte.
• Figure 5 shows the average of the voltage values of three elements of type A and D measured during current taps at a current of C / 6 (83 mA), at a temperature of -40 ° C. These elements were stored for 30 days at 65 ° C.
• Figure 6 shows the average of the voltage values of three elements of type A and D measured during current taps at a current of C / 6 (83 mA) at a temperature of -40 ° C. These elements were stored for 90 days at 65 ° C.
• FIG. 7 represents the voltage curves of type A and D elements during their discharge at ambient temperature under a current of C / 100.
• FIG. 8 shows the voltage curves of type A and D cells during their discharge at room temperature under a current of C / 100 after they have been stored for 90 days at a temperature of 65 ° C.
• electrolyte composition according to the invention as well as the various constituents of an electrochemical element comprising the electrolyte composition according to the invention will be described in the following.
• Electrolyte composition :
• the electrolyte comprises a solvent comprising: - a mixture of at least two saturated cyclic carbonates, at least one of these saturated cyclic carbonates being monofluorinated or difluorinated or trifluorinated,
• said at least one monofluorinated or difluorinated or trifluorinated saturated cyclic carbonate representing at most 1.5% of the mass of solvent
• said at least one ether representing at least 40% of the mass of solvent.
• the monofluorinated or difluorinated or trifluorinated saturated cyclic carbonate can be chosen from the group consisting of ethylene monofluorocarbonate (FEC), also designated by the term 4-fluoro-1,3-dioxolan-2-one, ethylene difluorocarbonate , ethylene trifluoromethylcarbonate, also designated by the term 4-trifluoro-l, 3-dioxolan-2-one, propylene monofluorocarbonate, propylene difluorocarbonate, propylene trifluorocarbonate and a mixture of these.
• FEC ethylene monofluorocarbonate
• the monofluorinated saturated cyclic carbonate is ethylene monofluorocarbonate.
• the monofluorinated or difluorinated or trifluorinated saturated cyclic carbonate represents at most 1.5% of the mass of the solvent. According to one embodiment, the monofluorinated or difluorinated or trifluorinated saturated cyclic carbonate represents from 0.5% to 1% of the mass of solvent.
• the percentage of saturated monofluorinated or difluorinated or trifluorinated cyclic carbonate is set at a value less than or equal to 1.5% of the mass of solvent in order to limit the growth of the passivation layer (SEI for “Solid Electrolyte Interface”) at the lithium anode surface.
• this passivation layer forms as soon as contact between the electrolyte and the anode is established, that is, when the element is filled with the electrolyte. It is partially dissolved when the element is discharged, then forms again when the element is no longer under stress.
• a percentage greater than 1.5% would lead to a passivation layer that is too thick, which would have the effect of increasing the internal resistance of the element, and therefore the voltage drop of the element in discharge at low temperature under strong currents. Too thick a passivation layer would therefore penalize the capacity of the element. A percentage greater than 1.5% is therefore not suitable for an element comprising a lithium anode.
• the monofluorinated or difluorinated or trifluorinated saturated cyclic carbonate is mixed with at least one non-fluorinated saturated cyclic carbonate which can for example be chosen from ethylene carbonate (EC), propylene carbonate (PC) and butylene carbonate (BC) .
• the mixture of these two cyclic carbonates can represent at least 30% of the mass of solvent.
• the mixture of these two cyclic carbonates can represent less than 50% of the mass of solvent, or less than 40% of the mass of solvent.
• Said at least one ether can be chosen from linear ethers and cyclic ethers. Examples of linear ethers are dimethoxyethane and propyl ethyl ether.
• cyclic ethers examples include tetrahydrofuran (THF) and 1,3-dioxolane (DIOX).
• THF tetrahydrofuran
• DIOX 1,3-dioxolane
• said at least one ether is chosen from cyclic ethers.
• the solvent can comprise a mixture of two cyclic ethers.
• said at least one ether represents at least 40% of the mass of solvent.
• Said at least one ether can represent at least 50% of the mass of solvent, or at least 60% of the mass of solvent.
• Said at least one ether can represent at most 75% of the mass of solvent, or at most 65% of the mass of solvent.
• the solvent comprises or consists of a mixture of propylene carbonate, ethylene monofluorocarbonate, tetrahydrofuran and dioxolane.
• the propylene carbonate can represent from 30 to 40% by mass of solvent.
• Ethylene monofluorocarbonate represents at most 1.5% of the solvent mass.
• Tetrahydrofuran represents from 5 to 10% by weight of solvent.
• the dioxolane can represent from 40 to 70% or from 50 to 60% by mass of solvent.
• the solvent can be free from linear carbonates and / or linear or cyclic esters.
• the electrolyte composition contains at least one lithium salt, other than lithium difluorophosphate.
• This lithium salt can be chosen from lithium perchlorate LiCICL, lithium hexafluorophosphate LiPFr ,, lithium tetrafluoroborate L1BF 4, lithium hexafluoroarsenate Li AsFr ,, lithium hexafluoroantimonate Li SbFr > , trifluoromethanesulfonate lithium L1CF 3 SO 3 , lithium bis (fluorosulfonyl) imide Li (FSC> 2 ) 2 N (LiFSI), lithium trifluoromethanesulfonimide LiN (CF 3 SC> 2 ) 2 (LiTFSI), lithium trifluoromethanesulfonemethide LiC (CF 3 SC> 2 ) 3 (LiTFSM), lithium bisperfluoroethylsulfonimide LiN / CF SO) (LiBETI), lithium 4,5-d
• the concentration of the lithium salt in the electrolyte varies from 0.5 to 2 mol.L 1 , preferably from 0.8 to 1.5 mol.L 1 .
• the electrolyte composition contains lithium difluorophosphate L1PO2F2 in an amount representing from 0.1% to 1% relative to the sum of the mass of solvent and the mass of said at least one lithium salt. According to one embodiment, the electrolyte composition contains lithium difluorophosphate in an amount representing from 0.1% to 0.5%, or from 0.2% to 0.5% relative to the sum of the mass of solvent and the mass of said at least one lithium salt.
• the combined use of a fluorinated cyclic carbonate and lithium difluorophosphate makes it possible to create a thin passivation layer that is not very resistive and stable over time, even if the element is exposed to a temperature above room temperature for a long time. duration, for example several months.
• the low resistivity of the passivation layer allows the element to achieve higher depth of discharge values than an element containing a conventional electrolyte.
• the passivation layer helps maintain the performance of the element over time and extend its life. For example, it has been observed that an electrochemical element of Li / MnCh type maintains its performance for at least 4 years at room temperature.
• the electrolyte can also contain vinylene carbonate (VC).
• VC vinylene carbonate
• the electrolyte composition according to the invention can be used in any electrochemical element comprising a lithium metal or lithium alloy anode. It may be a primary electrochemical element, that is to say non-rechargeable, or a secondary electrochemical element, that is to say rechargeable, for example an element of the Li-S type with electrolyte. solid or liquid. It is advantageously used in a primary element, comprising a cathode, the active material of which is preferably manganese dioxide.
• the cathode is manufactured by covering a current collector with an ink consisting of a mixture essentially comprising the active cathodic material, generally at least one electronically conductive additive and one or more binder (s ).
• the cathodic active material can be solid and selected from the group consisting of CF X with x ⁇ 1;MnCh;FeS2;V2O5; I2 or a mixture of these.
• the electronically conductive additive can be selected from carbon black, graphite, carbon fibers, carbon nanotubes, and a mixture thereof. It can represent from 1 to 15% by mass of the ink.
• the function of the binder is to bind the particles of cathodic active material together as well as to bind them to the current collector on which they are deposited.
• the binder can be chosen from carboxymethylcellulose (CMC), hydroxyethylcellulose (HEC), hydroxypropylcellulose (HPC), hydroxypropylmethylcellulose (HPMC), polyacrylic acid (PAAc), xanthan gum, polyvinyl alcohol PVA , poly (vinyl butyral) (PVB), poly (ethylene oxide) (PEO), a butadiene - styrene copolymer (SBR), polytetrafluoroethylene (PTFE), polyamideimide (P AI), polyimide (PI), a fluorinated copolymer of propylene and ethylene, polyhexafluoropropylene (PPHF), a polyimide, styrene-butadiene rubber (SBR) , poly vinyl alcohol, polyvinylidene fluoride (PVDF
• the current collector is generally a metal strip or a metal grid made of aluminum or an aluminum alloy, with a thickness between 10 and 800 ⁇ m.
• the current collector is coated with the ink obtained by mixing the cathodic active material (s) with the electronically conductive additive (s), the binder (s) ) and an organic or aqueous solvent.
• the current collector is covered with this ink. Then, the coated current collector is dried to evaporate the solvent. After drying, the ink adheres to the current collector to form the cathode.
• the cathodic active material is elemental sulfur, generally incorporated into pores of a porous carbon structure.
• the anode active material is lithium metal or a lithium-based alloy of the formula LiM, where M is selected from the group consisting of Mg, Al, Si, B, Ge, Ga or a mixture thereof. Preferably, M is Al.
• the anodic active material is in the form of a lithium strip or a strip of a lithium alloy to which a current collector is attached.
• the current collector can be solid or have a perforated structure.
• the current collector can be chosen from the group comprising a perforated metal, a metal, a grid, a metallic fabric and is made of a material chosen from among copper, stainless steel and nickel, preferably copper.
• the active material can be attached to the current collector by a rolling process.
• the material of the separator can be chosen from polyolefins, for example polypropylene, polyethylene, polyesters, glass fibers bound together by a polymer, polyimides, polyamides, polyaramid, polyamideimide and cellulose.
• the polyester can be chosen from polyethylene terephthalate (PET) and polybutylene terephthalate (PBT).
• PET polyethylene terephthalate
• PBT polybutylene terephthalate
• the polyester or polypropylene or polyethylene contains or is coated with a material selected from the group consisting of a metal oxide, a carbide, a nitride, a boride, a silicide and a sulfide. This material can be SiCh or AI2O3.
• An electrochemical bundle is formed by interposing a separator between at least one cathode and at least one anode.
• the electrochemical bundle is inserted into the cell's container.
• the container of the element can be of parallelepipedal or cylindrical format.
• the electrochemical bundle can be formed by the stack of electrodes and separators and be in the form of a parallelepiped.
• the format of the container is in this case parallelepipedal (prismatic).
• the electrochemical bundle can also consist of a spiral winding of at least one cathode and at least one anode separated by a separator.
• the format of the container is in this case cylindrical.
• the container is sealed with a lid.
• the cover is provided with an opening for the introduction of the electrolyte.
• the electrolyte composition according to the invention is introduced into the container of the element through a vacuum created in the container by an operator.
• the electrochemical element incorporating the electrolyte composition can be advantageously used in cold environments, for example at a temperature less than or equal to 0 ° C, preferably less than or equal to -20 ° C, which can range down to -40. ° C. It can be used in applications requiring a high discharge current, that is to say a discharge current greater than or equal to C / 6, even greater than or equal to C / 2, or even greater than or equal to C, C being the nominal electrochemical capacity of the element.
• the element comprising the electrolyte composition according to the invention can be used in the field of radio communications, meters, security systems, alarms, distress beacons (ELT, EPIRB) and location systems.
• lithium / MnCh primary electrochemical elements Four types A, B, C and D of lithium / MnCh primary electrochemical elements have been manufactured. They include an anode which is lithium metal and a cathode whose active material is manganese dioxide. The anode and the cathode are separated by a separator based on polyolefin (PE -Polyethylene- or PP -Polypropylene- or a combination of both). Elements differ in the composition of their electrolyte. The following table shows the electrolyte compositions tested: Table 1
• FIG. 3 shows that after 90 days of storage, the highest capacitance is obtained for the electrode of the type D element according to the invention.
• the capacitance measurement gives an indication of the thickness of the passivation layer. In fact, the capacitance increases when the thickness of the passivation layer decreases.
• a weak passivation layer favors a rapid return of the voltage to its nominal value when the element is subjected to a current draw.
• the element having the cathode with the thinnest passivation layer after 90 days of storage is the type D element. The voltage of this element therefore returns more quickly to its nominal value in the event of a current draw at low temperature. .
• L1PO2F2 contributes to the stability of the resistance of the passivation layer (comparison of the results of type B elements compared to those of type A elements).
• the replacement of EC by FEC makes it possible to reinforce the effect obtained by the addition alone of LÎP0 2 F 2 .
• the replacement of EC by FEC makes it possible to stabilize the growth over time of the thickness of the passivation layer (comparison of the results of type D elements compared to those of type B elements).
• type C cells have the lowest capacitance after 90 days of storage.
• the cells were then discharged at 20 ° C at a rate of C / 50 with an amount of electricity of 75 mAh, corresponding to a drop in their state of charge of about 15%.
• the cells were again subjected to a current draw under the same discharge conditions. Their tension was measured.
• the cells were then discharged again at 20 ° C at a rate of C / 50 with an amount of electricity of 75 mAh.
• the alternation of current taps and discharges of an amount of electricity of 75 mAh was repeated until the cells were completely discharged.
• the average of the voltages of the three elements of type A and D after one second of current draw was calculated and was reported in FIG. 4 for the different states of charge considered. It can be seen that the average of the voltages of the D-type elements is higher than that of the A-type elements, thus indicating a lower internal resistance of the anode passivation layer for the D-type elements.
• the three elements of type A and D were stored for 30 days at a temperature of 65 ° C.
• the same measurements as those made on the cells freshly filled with electrolyte were carried out on the cells stored for 30 days at a temperature of 65 ° C.
• the average of the voltages of the three elements of type A and D after one second of current draw was calculated and has been reported in FIG. 5 for the different states of charge considered. It is again noted that the average of the voltages of the elements of type D is higher than that of elements of type A.
• the three elements of type A and D were stored for an additional 60 days at a temperature of 65 ° C. The same measurements as those performed on the cells freshly filled with electrolyte were performed on the cells stored during these additional 60 days. The average of the voltages of the three elements of type A and D after one second of current draw was calculated and was reported in FIG. 6 for the different states of charge considered. It is again noted that the average of the voltages of the elements of type D is higher than that of elements of type A.
• FIG. 8 represents the voltage curves of the elements of these elements during the discharge.

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• 2019
  • 2019-07-24 FR FR1908412A patent/FR3099297B1/fr active Active
• 2020
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