EP2803100A1 - Detection of a malfunction in an electrochemical accumulator - Google Patents

Detection of a malfunction in an electrochemical accumulator

Info

Publication number
EP2803100A1
EP2803100A1 EP13700502.1A EP13700502A EP2803100A1 EP 2803100 A1 EP2803100 A1 EP 2803100A1 EP 13700502 A EP13700502 A EP 13700502A EP 2803100 A1 EP2803100 A1 EP 2803100A1
Authority
EP
European Patent Office
Prior art keywords
housing
accumulator
electrochemical accumulator
sensor
magnetic field
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP13700502.1A
Other languages
German (de)
French (fr)
Inventor
Pierre Perichon
François Alcouffe
Roland Blanpain
Johann LEJOSNE
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Original Assignee
Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Commissariat a lEnergie Atomique et aux Energies Alternatives CEA filed Critical Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Publication of EP2803100A1 publication Critical patent/EP2803100A1/en
Withdrawn legal-status Critical Current

Links

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
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
    • 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
    • H01M10/04—Construction or manufacture in general
    • H01M10/0422—Cells or battery with cylindrical casing
    • 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
    • H01M10/058—Construction or manufacture
    • H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
    • 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
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • 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
    • H01M10/425—Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing
    • 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
    • H01M10/48—Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte
    • 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
    • H01M10/48—Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte
    • H01M10/486—Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte for measuring temperature
    • 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
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/63—Control systems
    • H01M10/637—Control systems characterised by the use of reversible temperature-sensitive devices, e.g. NTC, PTC or bimetal devices; characterised by control of the internal current flowing through the cells, e.g. by switching
    • 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
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/64—Heating or cooling; Temperature control characterised by the shape of the cells
    • H01M10/643—Cylindrical cells
    • 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
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/65—Means for temperature control structurally associated with the cells
    • H01M10/657—Means for temperature control structurally associated with the cells by electric or electromagnetic means
    • 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
    • H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
    • 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
    • H01M4/42—Alloys based on zinc
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings, jackets or wrappings of a single cell or a single battery
    • H01M50/102—Primary casings, jackets or wrappings of a single cell or a single battery characterised by their shape or physical structure
    • H01M50/107—Primary casings, jackets or wrappings of a single cell or a single battery characterised by their shape or physical structure having curved cross-section, e.g. round or elliptic
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/007—Regulation of charging or discharging current or voltage
    • 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
    • H01M10/48—Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte
    • H01M10/482—Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte for several batteries or cells simultaneously or sequentially
    • 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
    • H01M10/425—Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing
    • H01M2010/4271—Battery management systems including electronic circuits, e.g. control of current or voltage to keep battery in healthy state, cell balancing
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2220/00—Batteries for particular applications
    • H01M2220/30—Batteries in portable systems, e.g. mobile phone, laptop
    • 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
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the invention relates to storage batteries including a large number of electrochemical accumulators.
  • Some accumulators are in the form of cylindrical spiral generators. Such an accumulator includes an electrochemical bundle included in a spiral coil.
  • the spool is formed of the winding of a positive electrode and a negative electrode alternating with first and second layers forming separators.
  • the separators serve to electrically isolate the positive electrode from the negative electrode. Separators are also used to isolate the positive and negative outer portions of the accumulator respectively.
  • the spool is usually housed in a cylindrical sealed metal cup. One side of the metal cup forms the negative pole.
  • the bobbin is bathed in an electrolyte that allows ion exchange.
  • a cover is connected, generally by soldering, to the positive electrode via a connection and forms the positive pole.
  • the lid is electrically isolated from the bucket.
  • Such accumulators Because of the increasingly common use of such accumulators, their manufacturing process is better and better controlled. Such accumulators thus have high reliability. The use of such accumulators is therefore favored for batteries requiring a high level of security and a large number of accumulators. Such batteries are notably produced on a large scale to power laptops.
  • the batteries especially according to the lithium ion technology, have an ever increasing specific energy. Technologically, such accumulators have a limited voltage at their terminals, of the order of 2 to 4 V in most cases. In high voltage and high power applications, the batteries must include a very large number of accumulators connected in series. To facilitate the manipulation and sizing of batteries, the capacity of a battery is adapted by connecting in parallel an adequate number of accumulators. Therefore, such batteries increase the risk of occurrence of a short circuit, with consequences all the more important that the specific energy is high and that the malfunction can spread to a high number of accumulators. Thus, the short-circuited battery can be confronted with thermal runaway with fusion of its various components. This thermal runaway can spread to adjacent accumulators and the system that powers it.
  • the invention aims to solve one or more of these disadvantages.
  • the invention thus relates to an electrochemical accumulator and to a feed system as defined in the appended claims.
  • Other characteristics and advantages of the invention will emerge clearly from the description which is given hereinafter, by way of indication and in no way limitative, with reference to the appended drawings, in which:
  • FIG 1 is a sectional view of an example of accumulator for which the invention can be implemented
  • FIG. 2 is an enlarged schematic sectional view of a local short-circuit at a separator
  • FIG. 3 is a schematic representation of an accumulator provided with a first variant of a temperature measuring device for early detection of a short circuit
  • FIG. 4 is a diagram illustrating the temperatures measured by probes respectively inside and outside of an accumulator at the short-circuit during validation tests of the measuring device;
  • FIG. 5 illustrates the inverse of the magnetic susceptibility of LiFePO 4 as a function of the temperature
  • FIG. 6 illustrates a magnetic field differential measured by the measuring device during a validation test
  • FIG. 7 illustrates the temperature measured by the probe outside the accumulator during the validation test
  • FIG 8 is a schematic representation of a battery including accumulators according to the invention.
  • FIG. 9 is an example of a hysteresis cycle of ferromagnetic material
  • FIG. 10 illustrates the saturation magnetic field of an example of ferromagnetic material as a function of its temperature
  • FIG. 11 illustrates the saturation polarization and the anisotropic field of a hexagonal barium ferrite
  • FIG 12 is a schematic representation of an accumulator provided with a second variant of temperature measuring device for early detection of a short circuit.
  • the invention proposes to measure the temperature inside the housing of an electrochemical accumulator including ferromagnetic material by performing a remanent magnetic field measurement of this ferromagnetic material from outside the housing.
  • the invention makes it possible to carry out a temperature measurement without reducing the tightness of the housing and with increased speed, which makes it possible to reduce the consequences of a possible short-circuit in the accumulator.
  • Ferromagnetic materials exhibit a substantially invariant magnetic susceptibility and a generally non-magnetic magnetization. linear in response to the application of a magnetic field.
  • the magnetization characteristic of a ferromagnetic material is thus usually defined by a diagram as illustrated in FIG. 9. The full curve of the first magnetization is illustrated in solid lines, and the hysteresis cycle of such a material.
  • the magnetization increases until saturation to a value Ms.
  • a residual magnetization or residual Mr is then preserved.
  • the magnetization eventually reaches a saturation value -Ms.
  • the remanent magnetization -Mr is then retained.
  • FIG. 10 illustrates the value Ms for an example of ferromagnetic material such as cobalt, as a function of a ratio T / Tc.
  • T corresponds to the temperature of the material
  • Te corresponds to its Curie temperature, from which any remanent magnetization disappears.
  • the value of the remanent magnetization Mr being proportional to the value Ms, it is also a function of the temperature of the material.
  • the invention proposes to take advantage of the influence of temperature on the remanent magnetization to determine a temperature inside an accumulator case from a remanent magnetic field measurement from the outside of the case. .
  • systems based on a measurement of magnetization of a ferromagnetic material are based on the measurement of the magnetic susceptibility of the material and thus assume the choice of a material having the lowest residual field possible.
  • the invention encourages the use of a material for which the remanent magnetic field is as high as possible.
  • FIG. 1 is a sectional view of an electrochemical accumulator 3.
  • This accumulator 3 is in this case a spiral accumulator of cylindrical shape.
  • Such an accumulator 3 includes a spiral coil.
  • the accumulator 3 comprises a bucket or cylindrical housing 301 in which is housed the spiral wound coil of the electrodes.
  • the bucket or cylindrical housing 301 is typically conductive.
  • the cylindrical cup 301 can be made of metal and be waterproof.
  • the coiled coil comprises a rectangular flexible plate of negative electrode 31, a rectangular plate of positive electrode 33 and two separators 32 and 34.
  • the separators 32 and 34 can be formed in the same folded layer at one end.
  • the electrodes 31 and 33 and the separators 32 and 34 are wound around the axis of the cylindrical cup 301.
  • the electrodes 31 and 32 and the separators 32 and 34 are wound around an insulating shaft 35.
  • This insulating shaft 35 is fixed in the central part of the accumulator 3.
  • the winding is made in such a way as to perform alternating positive-separator-negative electrode-electrode layers separator.
  • Each separator 32, 34 serves to electrically isolate the positive electrode 33 from the negative electrode 31.
  • the separators 32 and 34 can also be used to isolate the positive and negative outer portions of the accumulator 3 respectively.
  • the coil is immersed in an electrolyte which allows ion exchange.
  • a lower face of the bucket 301 forms the negative pole.
  • a positive pole 302 is connected, generally by soldering, to the positive electrode 33 via a connection 37 and a cover 38.
  • the positive pole 302 and the cover 38 are electrically isolated from the bucket 301.
  • a part 303 of the separators 32 and 34 protrudes axially to prevent contact between the electrodes 31 and 33.
  • spacers 36 project axially with respect to the electrodes 31, 33 and The spacers 36 support the connection 37.
  • the spacers 36 may be formed by protrusions of the central turns of the separators 32 and 34. Thus, the spacers 36 prevent the connection 37 from accidentally coming into contact with the electrode. negative 31.
  • Figure 2 is an enlarged sectional view of a layer superposition of the coil in an example of a local short circuit.
  • the separator 32 interposed between the negative electrode 31 and the positive electrode 33 has a through orifice 39.
  • An electric current is established between the electrode 33 and the electrode 31 through the orifice 39, as illustrated by the arrows.
  • the current flowing through the orifice 39 can have a very high amplitude and lead to a heating of the electrodes 31, 33 and the film 32.
  • the heating can induce chain damage within the battery 3. Destruction of the battery 3 may induce sufficient heating to spread to other accumulators adjacent to the rest of a battery or the system to be powered.
  • FIG. 4 is a diagram showing a simulation of malfunctions of an accumulator 3.
  • the dashed curve illustrates the temperature inside the accumulator 3 at the level of a short circuit and the line curve.
  • solid illustrates the temperature measured by a thermocouple type sensor conventionally disposed outside the housing 301.
  • the simulated cycle comprises a first heating phase, followed by a second cooling phase. The measurements were performed by including a controlled heating resistor inside the housing 301.
  • FIG. 3 is a schematic representation of an accumulator 3 according to an exemplary implementation of the invention.
  • the battery 3 may have the structure shown in Figure 1 and thus comprise a housing including two electrodes of opposite polarities immersed in an electrolyte.
  • the positive electrode and the negative electrode can thus each include respective conductive films.
  • the conductive films of these electrodes may be alternately superposed and separated by at least one insulating separator film.
  • the electrode films and the separator films can be superposed alternately in a winding around an axis, so as to form a battery 3 in the form of a coil.
  • Ferromagnetic material is contained in the housing.
  • the ferromagnetic material is for example included in one or both electrodes, in order to increase the amplitude of the remanent magnetic field generated.
  • a lithium-ion-type accumulator 3 contains LiFePO 4, which is an antiferromagnetic material whose susceptibility is low compared to that of certain ferromagnetic materials.
  • FIG. 5 illustrates the inverse of the magnetic susceptibility of LiFePO 4 on the ordinate as a function of its temperature on the abscissa.
  • the ferromagnetic material already present in a lithium-ion battery is sensitive to temperature, which modifies its magnetization to make it very weak when approaching the Curie temperature.
  • additional ferromagnetic material may be included in the accumulator.
  • additional material will advantageously have a Curie temperature of less than 600 ° C., preferably less than 400 ° C. With such a Curie temperature, a good measurement sensitivity will be available at the temperature rise.
  • at least one of the two electrodes may include additional ferromagnetic material. This material will advantageously be chosen for the high amplitude of its remanent magnetic field or its coercive field Hc.
  • One of the two electrodes may thus include barium ferrite or strontium ferrite.
  • the accumulator 3 comprises a magnetic sensor 1 1 placed outside the housing of the accumulator 3.
  • the implantation of the magnetic sensor January 1 thus does not disturb the sealing of the accumulator 3 and does not increase the risks occurrence of a short circuit in the housing.
  • the magnetic sensor 1 1 is capable of measuring the variations of magnetic fields inside the 3.
  • the sensor 1 1 is advantageously coupled to the housing of the battery 3 to have a maximum sensitivity to the variations of magnetic fields inside the housing of the battery 3. In the absence of application of a magnetic field of magnetization from the outside, the sensor 1 1 thus measures the accumulation of the ambient magnetic field and the remanent magnetic field of the interior of the housing.
  • the senor 1 1 is advantageously configured to essentially measure the magnetic field perpendicular to the axis of the accumulator and reject the magnetic field along the axis of this accumulator 3.
  • the sensor 1 1 is less responsive to the charging or discharging currents of the accumulator 3 during normal operation, at the origin of a magnetic field along the axis of the accumulator 3.
  • the variation of the remanent magnetic field generated by the heating of the ferromagnetic material will be generally observable in one direction.
  • Such a field variation will be well measured by a sensor January 1 capable of measuring the radial component of the magnetic field inside the housing as soon as it can align in the direction of said field.
  • a large magnetization of the accumulator 3 is performed prior to its commissioning, in order to obtain a significant level of the remanent magnetic field of the ferromagnetic material.
  • This prior magnetization can define a non-isotropic remanent magnetic field of the ferromagnetic material, with a dominant orientation.
  • the sensor 1 1 is advantageously positioned to measure the remanent magnetic field according to this dominant orientation.
  • the accumulator 3 includes a circuit 13 configured to determine the temperature inside the housing as a function of the measured residual magnetic field. This temperature can be determined on the basis of a temperature law as a function of the measured remanent magnetic field which can be stored in the circuit 1 3. This law can be extrapolated from a curve such as that illustrated in FIG. 0.
  • Figure 11 also illustrates the saturation polarization and anisotropy field versus temperature for hexagonal barium ferrite. Such a diagram can also be used to determine the temperature inside the housing as a function of the measured remanent magnetic field.
  • the battery 3 includes a second magnetic sensor 1 2 also placed outside the housing.
  • This magnetic sensor 1 2 has a sensitivity to the magnetic field inside the lower housing to that of the sensor 1 January.
  • This sensitivity to the magnetic field inside the housing of the sensor 1 2 is advantageously substantially zero.
  • the sensor 1 2 thus measures the ambient field, to take account, for example, of the earth's magnetic field.
  • Such a lower sensitivity can be obtained by moving the sensor 1 2 away from the battery 3 or by separating it from the battery 3 by through a shield.
  • the circuit 1 3 advantageously makes a differential measurement between the magnetic field measured by the sensor 1 1 and the magnetic field measured by the sensor 1 2.
  • the circuit 1 3 can apply a transfer function between the sensors 1 1 and 1 2, for example according to a noise reduction technique with references, such as Wiener filtering.
  • a noise reduction technique with references, such as Wiener filtering.
  • Wiener filtering for relatively weak magnetic fields inside the housing, it is possible to obtain a measurement of the variation of this remanent field generated by a possible heating in a relatively precise manner, by rejecting the influence of the surrounding magnetic field of the accumulator.
  • the accumulator 3 comprises a single sensor 1 1 attached to its housing. This sensor 1 1 is advantageously disposed at mid length along the axis of the accumulator 3, in order to optimally detect temperature increases in the housing over the entire length of the accumulator 3.
  • Several magnetic sensors 1 1 may of course be distributed radially around the accumulator 3, or along the axis of the accumulator 3.
  • the accumulator 3 advantageously comprises a magnetization device 14 of the interior of the housing.
  • the magnetization device 14 is for example configured to generate a magnetic field oriented perpendicularly to the axis of the accumulator 3, prior to measurement by the sensor January 1.
  • the magnetization device 14 is configured to generate a magnetic field inside the housing of the accumulator 3 on command, dynamically.
  • the magnetizer 14 may include a coil configured to apply magnetic field within the housing only when this coil is electrically powered.
  • the circuit 1 3 is configured to alternate the supply of such a coil (and thus the generation of the magnetization magnetic field of the ferromagnetic material) and the recovery of a magnetic field measurement made by the sensor 1 1 ( and if necessary the sensor 1 2).
  • the magnetic field measurement taken into account by the sensor 1 1 (and optionally the sensor 12) corresponds to the remanent magnetic field of the ferromagnetic material inside the housing, used to determine the temperature inside the the accumulator 3.
  • FIG. 6 illustrates the difference of the magnetic fields measured by the magnetic sensors 1 1 and 12.
  • FIG. 7 illustrates the temperature measured in simultaneous during the cycle illustrated in Figure 4 by a thermocouple outside the housing.
  • the sensors 1 1 and 1 2 used are flow gates (known as fluxgates in English) marketed under the reference FLC1 00 by Stefan Mayer Instruments.
  • the differential between the measured magnetic fields (corresponding to the remanent magnetic field) increases rapidly and then gradually decreases as the inside of the battery casing 3 warms up.
  • the differential between the measured magnetic fields decreases rapidly, then progressively increases as the inside of the battery casing 3 cools down.
  • the differential between the magnetic fields returns to its original value, with a difference of only 25nT.
  • thermocouple While it is necessary to immerse a thermocouple in the accumulator 3 to carry out a significant thermal measurement and to identify a possible malfunction, a temperature measurement according to the invention makes it possible to identify a malfunction without altering the integrity of the device. the accumulator 3 and in a reduced time.
  • FIG 8 illustrates a power supply system 1.
  • a battery 2 comprises several electrochemical accumulators 3 according to the invention.
  • An electric charge 5 is connected to the terminals of the battery 2 by means of a controlled switch 1 5.
  • Each accumulator 3 comprises a magnetic sensor 1 1 measuring the remanent magnetic field inside its housing.
  • the sensors 1 1 are connected to a common control circuit 13.
  • the common control circuit 1 3 advantageously controls the respective magnetization devices of the accumulators 3.
  • a common magnetic sensor 1 2 measures the surrounding magnetic field of the battery 2. a differential measurement between each of the remanent magnetic fields measured by the sensors 1 1 and the sensor 1 2, the control circuit 1 3 deduces the temperature inside the housing of each of the accumulators 3.
  • the common control circuit 1 3 advantageously controls the prior application of a magnetization magnetic field by means of the magnetization device 14.
  • the control circuit 1 3 then controls the magnetization device 14 to suppress the magnetic field applied by it.
  • the remnant magnetic field is then measured by differential measurement of the sensors 1 1 and 12, in the absence of the magnetization magnetic field.
  • the control circuit 13 can control the opening of the switch 15 to interrupt the discharge of the battery 2 in the electric charge 5.
  • the control circuit 13 can thus limit the consequences of a short circuit inside one of the accumulators 3.
  • the control circuit 13 thus ensures the supervision of the operation of the accumulators 3.
  • the electric charge 5 is decoupled from the entire battery 2 by means of the switch 15. It is also possible to isolate only an accumulator 3, a malfunction of which has been identified by disconnecting it from the others. accumulators of the battery 2, in order to avoid a discharge of the other accumulators towards it, and guaranteeing the continuity of service of the battery 2. Switches can thus be included in the battery 2 in order to be able to isolate each of the accumulators 3 by a command of the circuit 13.
  • the normal operating temperature is up to 60 ° C or 80 ° C. Beyond the normal operating temperature, the performance of the battery deteriorates strongly and can become dangerous. Up to a safety temperature of 1 10 ° C, or even 130 ° C, the phenomenon is however reversible. Beyond this safety temperature, there is a phenomenon of thermal runaway.
  • the circuit 13 can thus be programmed to generate a first warning signal and to isolate a battery 2 when its temperature is higher than the normal operating temperature, and to generate a second warning signal when the temperature of this battery 2 is greater than the safety temperature for example to activate a fire extinguisher or flooding in an inert gas.
  • the accumulator 3 is a coil accumulator in the illustrated example, the invention naturally also applies to other battery structures, for example an accumulator comprising a stack of electrode and separator films. .
  • an accumulator may in particular have a non-cylindrical shape.
  • the accumulator may for example be prismatic type and include a stack of flat layers of electrodes and separators.
  • the safety of a battery 3 has been described in the context of a discharge of the latter in an electric charge.
  • the safety of a battery 3 can of course also be performed when it is connected to a charging system.

Abstract

The invention relates to an electrochemical accumulator (3), comprising: -a casing (301); -at least two electrodes (31, 33) and an electrolyte contained in the casing; -at least ferromagnetic material contained inside the casing, said ferromagnetic material having remanent magnetism; -a magnetic sensor arranged outside the casing and capable of measuring the variations in magnetic fields inside the casing; -a circuit configured to determine the temperature inside the casing on the basis of the magnetic field measured.

Description

DETECTION D'UN DYSFONCTIONNEMENT DANS UN  DETECTION OF DYSFUNCTION IN A
ACCUMULATEUR ELECTROCHIMIQUE  ELECTROCHEMICAL BATTERY
L'invention concerne les batteries d'accumulateurs incluant un grand nombre d'accumulateurs électrochimiques. The invention relates to storage batteries including a large number of electrochemical accumulators.
Certains accumulateurs se présentent sous la forme de générateurs spiralés de forme cylindrique. Un tel accumulateur inclut un faisceau électrochimique inclus dans un bobineau spiralé. Le bobineau est formé de l'enroulement d'une électrode positive et d'une électrode négative alternant avec des première et deuxième couches formant des séparateurs. Les séparateurs servent à isoler électriquement l'électrode positive de l'électrode négative. Les séparateurs servent également à isoler les parties extérieures respectivement positive et négative de l'accumulateur.  Some accumulators are in the form of cylindrical spiral generators. Such an accumulator includes an electrochemical bundle included in a spiral coil. The spool is formed of the winding of a positive electrode and a negative electrode alternating with first and second layers forming separators. The separators serve to electrically isolate the positive electrode from the negative electrode. Separators are also used to isolate the positive and negative outer portions of the accumulator respectively.
Le bobineau est généralement logé dans un godet métallique étanche cylindrique. Une face du godet métallique forme le pôle négatif. Le bobineau est baigné dans un électrolyte qui permet un échange ionique. Un couvercle est connecté, généralement par soudure, à l'électrode positive par l'intermédiaire d'une connexion et forme le pôle positif. Le couvercle est isolé électriquement du godet.  The spool is usually housed in a cylindrical sealed metal cup. One side of the metal cup forms the negative pole. The bobbin is bathed in an electrolyte that allows ion exchange. A cover is connected, generally by soldering, to the positive electrode via a connection and forms the positive pole. The lid is electrically isolated from the bucket.
Du fait de l'utilisation de plus en plus courante de tels accumulateurs, leur processus de fabrication est de mieux en mieux contrôlé. De tels accumulateurs présentent ainsi une fiabilité élevée. L'utilisation de tels accumulateurs est donc favorisée pour des batteries nécessitant un niveau de sécurité élevé et un grand nombre d'accumulateurs. De telles batteries sont notamment produites à grande échelle pour alimenter des ordinateurs portables.  Because of the increasingly common use of such accumulators, their manufacturing process is better and better controlled. Such accumulators thus have high reliability. The use of such accumulators is therefore favored for batteries requiring a high level of security and a large number of accumulators. Such batteries are notably produced on a large scale to power laptops.
Bien que rare, un dysfonctionnement possible d'un tel accumulateur est l'apparition d'un court-circuit par percement d'un séparateur. D'après différentes études, un tel court-circuit se déclenche du fait d'un percement localisé d'un séparateur. Les principales causes à l'origine d'un tel percement sont une usure du séparateur, la création de dendrites métalliques dans certaines conditions de fonctionnement, ou la présence de débris indésirables dans l'accumulateur suite à un processus de fabrication mal contrôlé.  Although rare, a possible malfunction of such a battery is the appearance of a short circuit by piercing a separator. According to various studies, such a short circuit is triggered due to a localized boring of a separator. The main causes of such a breakthrough are wear of the separator, the creation of metal dendrites under certain operating conditions, or the presence of unwanted debris in the accumulator following a poorly controlled manufacturing process.
Les batteries, en particulier selon la technologie lithium ion, disposent d'une énergie spécifique sans cesse accrue. Technologiquement, de tels accumulateurs présentent une tension limitée à leurs bornes, de l'ordre de 2 à 4 V dans la plupart des cas. Dans des applications haute tension et forte puissance, les batteries doivent inclure un très grand nombre d'accumulateurs connectés en série. Pour faciliter la manipulation et le dimensionnement de batteries, la capacité d'une batterie est adaptée en connectant en parallèle un nombre adéquat d'accumulateurs. Par conséquent, de telles batteries multiplient les risques d'apparition d'un court-circuit, avec des conséquences d'autant plus importantes que l'énergie spécifique est élevée et que le dysfonctionnement peut se propager à un nombre élevé d'accumulateurs. Ainsi, l'accumulateur en court-circuit peut être confronté à un emballement thermique avec fusion de ses différents composants. Cet emballement thermique peut se propager à des accumulateurs adjacents et au système qui l'alimente. The batteries, especially according to the lithium ion technology, have an ever increasing specific energy. Technologically, such accumulators have a limited voltage at their terminals, of the order of 2 to 4 V in most cases. In high voltage and high power applications, the batteries must include a very large number of accumulators connected in series. To facilitate the manipulation and sizing of batteries, the capacity of a battery is adapted by connecting in parallel an adequate number of accumulators. Therefore, such batteries increase the risk of occurrence of a short circuit, with consequences all the more important that the specific energy is high and that the malfunction can spread to a high number of accumulators. Thus, the short-circuited battery can be confronted with thermal runaway with fusion of its various components. This thermal runaway can spread to adjacent accumulators and the system that powers it.
Des développements techniques réalisés sur de tels accumulateurs ont essentiellement porté sur le renforcement des séparateurs et sur la composition des électrodes afin de limiter la probabilité de percement et/ou d'accroître la résistance dans un éventuel court-circuit. Les solutions proposées induisent une augmentation sensible du prix de revient de l'accumulateur, un accroissement sensible de son volume et/ou une amélioration limitée de la sécurité de l'accumulateur, ce qui peut s'avérer incompatible avec des applications grand public ou de transport.  Technical developments carried out on such accumulators have mainly focused on the reinforcement of the separators and on the composition of the electrodes in order to limit the probability of piercing and / or to increase the resistance in a possible short circuit. The proposed solutions induce a significant increase in the cost price of the accumulator, a significant increase in its volume and / or a limited improvement in the safety of the accumulator, which may prove to be incompatible with consumer or commercial applications. transport.
Il est connu d'accoler une sonde de température à un accumulateur pour identifier et prévenir certains types de dysfonctionnements. En fonction de la résistance du court-circuit accidentel, on obtiendra un échauffement plus ou moins rapide de l'accumulateur. Pour un échauffement lent généré par le court- circuit, un tel échauffement est délicat à distinguer des variations de température de l'environnement ou des variations de température dues aux courants de fonctionnement traversant l'accumulateur. Pour un échauffement rapide, un échauffement rapide et important intervient initialement de façon localisée. Sur la paroi extérieure de l'accumulateur, réchauffement apparaît beaucoup plus tardivement et initialement de façon localisée. Un réchauffement global de l'accumulateur n'intervient que plus tardivement. Ainsi, lorsque la sonde de température externe permet de façon certaine de déterminer l'apparition d'un court-circuit, il est souvent trop tard pour éviter la destruction de l'accumulateur. Du fait de l'inflammabilité de certains matériaux d'accumulateurs, la destruction de l'accumulateur peut s'accompagner d'un départ de feu.  It is known to attach a temperature probe to an accumulator to identify and prevent certain types of malfunctions. Depending on the resistance of the accidental short-circuit, we will get a more or less rapid heating of the accumulator. For a slow heating generated by the short circuit, such heating is difficult to distinguish from changes in environmental temperature or temperature variations due to operating currents through the accumulator. For rapid heating, rapid and significant heating initially occurs in a localized manner. On the outer wall of the accumulator, warming appears much later and initially in a localized way. Global warming of the accumulator occurs only later. Thus, when the external temperature sensor is certain to determine the occurrence of a short circuit, it is often too late to avoid the destruction of the battery. Due to the flammability of some battery materials, the destruction of the battery can be accompanied by a fire.
L'inclusion de sondes de température à l'intérieur d'un accumulateur s'avérerait à la fois inefficace pour la plupart des dysfonctionnements et risquerait au contraire de constituer structurellement une source supplémentaire de risques d'apparition de courts-circuits. Par conséquent, devant l'impossibilité de détecter à temps une augmentation de température dans un accumulateur, les concepteurs peuvent être amenés à choisir des chimies d'accumulateurs plus sûre mais non optimales en termes de performances. Ce choix est d'autant plus primordial pour des applications de puissance et en présence d'utilisateurs.  The inclusion of temperature probes inside an accumulator would prove to be both inefficient for most malfunctions and could, on the contrary, constitute a structural additional source of risks of occurrence of short circuits. Therefore, in view of the impossibility of detecting a temperature increase in a battery in time, the designers may have to choose battery chemistries that are safer but not optimal in terms of performance. This choice is all the more important for power applications and in the presence of users.
L'invention vise à résoudre un ou plusieurs de ces inconvénients. L'invention porte ainsi sur un accumulateur électrochimique et sur un système d'alimentation tels que définis dans les revendications annexées. D'autres caractéristiques et avantages de l'invention ressortiront clairement de la description qui en est faite ci-après, à titre indicatif et nullement limitatif, en référence aux dessins annexés, dans lesquels : The invention aims to solve one or more of these disadvantages. The invention thus relates to an electrochemical accumulator and to a feed system as defined in the appended claims. Other characteristics and advantages of the invention will emerge clearly from the description which is given hereinafter, by way of indication and in no way limitative, with reference to the appended drawings, in which:
-la figure 1 est une vue en coupe d'un exemple d'accumulateur pour lequel l'invention peut être mise en œuvre ;  FIG 1 is a sectional view of an example of accumulator for which the invention can be implemented;
-la figure 2 est une vue en coupe schématique agrandie d'un court-circuit local au niveau d'un séparateur ;  FIG. 2 is an enlarged schematic sectional view of a local short-circuit at a separator;
-la figure 3 est une représentation schématique d'un accumulateur muni d'une première variante de dispositif de mesure de température pour une détection anticipée d'un court-circuit ;  FIG. 3 is a schematic representation of an accumulator provided with a first variant of a temperature measuring device for early detection of a short circuit;
-la figure 4 est un diagramme illustrant les températures mesurées par des sondes respectivement à l'intérieur et à l'extérieur d'un accumulateur au niveau du court-circuit lors d'essais de validation du dispositif de mesure ;  FIG. 4 is a diagram illustrating the temperatures measured by probes respectively inside and outside of an accumulator at the short-circuit during validation tests of the measuring device;
-la figure 5 illustre l'inverse de la susceptibilité magnétique du LiFeP04 en fonction de la température ; FIG. 5 illustrates the inverse of the magnetic susceptibility of LiFePO 4 as a function of the temperature;
-la figure 6 illustre un différentiel de champ magnétique mesuré par le dispositif de mesure durant un essai de validation ;  FIG. 6 illustrates a magnetic field differential measured by the measuring device during a validation test;
-la figure 7 illustre la température mesurée par la sonde à l'extérieur de l'accumulateur durant l'essai de validation ;  FIG. 7 illustrates the temperature measured by the probe outside the accumulator during the validation test;
-la figure 8 est une représentation schématique d'une batterie incluant des accumulateurs selon l'invention ;  FIG 8 is a schematic representation of a battery including accumulators according to the invention;
-la figure 9 est un exemple de cycle d'hystérésis de matériau ferromagnétique ;  FIG. 9 is an example of a hysteresis cycle of ferromagnetic material;
-la figure 1 0 illustre le champ magnétique de saturation d'un exemple de matériau ferromagnétique en fonction de sa température ;  FIG. 10 illustrates the saturation magnetic field of an example of ferromagnetic material as a function of its temperature;
-la figure 1 1 illustre la polarisation à saturation et le champ d'anisotropie d'une ferrite hexagonale de baryum ;  FIG. 11 illustrates the saturation polarization and the anisotropic field of a hexagonal barium ferrite;
-la figure 12 est une représentation schématique d'un accumulateur muni d'une deuxième variante de dispositif de mesure de température pour une détection anticipée d'un court-circuit.  FIG 12 is a schematic representation of an accumulator provided with a second variant of temperature measuring device for early detection of a short circuit.
L'invention propose de mesurer la température à l'intérieur du boîtier d'un accumulateur électrochimique incluant du matériau ferromagnétique en réalisant une mesure de champ magnétique rémanent de ce matériau ferromagnétique depuis l'extérieur du boîtier. The invention proposes to measure the temperature inside the housing of an electrochemical accumulator including ferromagnetic material by performing a remanent magnetic field measurement of this ferromagnetic material from outside the housing.
L'invention permet de réaliser une mesure de température sans amoindrir l'étanchéité du boîtier et avec une rapidité accrue, ce qui permet de réduire les conséquences d'un éventuel court-circuit dans l'accumulateur. Les matériaux ferromagnétiques présentent une susceptibilité magnétique sensiblement invariante et une aimantation généralement non linéaire en réponse à l'application d'un champ magnétique. La caractéristique d'aimantation d'un matériau ferromagnétique est ainsi usuellement définie par un diagramme tel qu'illustré à la figure 9. On a illustré en trait plein la courbe de première aimantation, et en pointillés le cycle d'hystérésis d'un tel matériau. The invention makes it possible to carry out a temperature measurement without reducing the tightness of the housing and with increased speed, which makes it possible to reduce the consequences of a possible short-circuit in the accumulator. Ferromagnetic materials exhibit a substantially invariant magnetic susceptibility and a generally non-magnetic magnetization. linear in response to the application of a magnetic field. The magnetization characteristic of a ferromagnetic material is thus usually defined by a diagram as illustrated in FIG. 9. The full curve of the first magnetization is illustrated in solid lines, and the hysteresis cycle of such a material.
Sous l'action d'un champ magnétique croissant, l'aimantation augmente jusqu'à saturation à une valeur Ms. En supprimant le champ magnétique H, une aimantation rémanente ou résiduelle Mr est alors conservée. En appliquant un champ magnétique négatif avec une amplitude croissante, l'aimantation finit par atteindre une valeur de saturation -Ms. En supprimant le champ magnétique H, l'aimantation rémanente -Mr est alors conservée.  Under the action of a growing magnetic field, the magnetization increases until saturation to a value Ms. By removing the magnetic field H, a residual magnetization or residual Mr is then preserved. By applying a negative magnetic field with increasing amplitude, the magnetization eventually reaches a saturation value -Ms. By removing the magnetic field H, the remanent magnetization -Mr is then retained.
La figure 1 0 illustre la valeur Ms pour un exemple de matériau ferromagnétique tel que du Cobalt, en fonction d'un rapport T/Tc. T correspond à la température du matériau, Te correspond à sa température de Curie, à partir de laquelle disparaît toute aimantation rémanente. La valeur de l'aimantation rémanente Mr étant proportionnelle à la valeur Ms, elle est également fonction de la température du matériau. L'invention propose de mettre à profit l'influence de la température sur l'aimantation rémanente pour déterminer une température à l'intérieur d'un boîtier d'accumulateur à partir d'une mesure de champ magnétique rémanent depuis l'extérieur du boîtier.  FIG. 10 illustrates the value Ms for an example of ferromagnetic material such as cobalt, as a function of a ratio T / Tc. T corresponds to the temperature of the material, Te corresponds to its Curie temperature, from which any remanent magnetization disappears. The value of the remanent magnetization Mr being proportional to the value Ms, it is also a function of the temperature of the material. The invention proposes to take advantage of the influence of temperature on the remanent magnetization to determine a temperature inside an accumulator case from a remanent magnetic field measurement from the outside of the case. .
Usuellement, les systèmes basés sur une mesure d'aimantation d'un matériau ferromagnétique sont basés sur la mesure de la susceptibilité magnétique du matériau et supposent ainsi le choix d'un matériau ayant un champ rémanent le plus faible possible. Au contraire, l'invention incite à utiliser un matériau pour lequel le champ magnétique rémanent est le plus élevé possible.  Usually, systems based on a measurement of magnetization of a ferromagnetic material are based on the measurement of the magnetic susceptibility of the material and thus assume the choice of a material having the lowest residual field possible. On the contrary, the invention encourages the use of a material for which the remanent magnetic field is as high as possible.
La figure 1 est une vue en coupe d'un accumulateur électrochimique 3. Cet accumulateur 3 est en l'occurrence un accumulateur spiralé de forme cylindrique. Un tel accumulateur 3 inclut un bobineau spiralé. L'accumulateur 3 comprend un godet ou boîtier cylindrique 301 dans lequel est logé le bobineau spiralé des électrodes. Le godet ou boîtier cylindrique 301 est typiquement conducteur. Le godet cylindrique 301 peut être réalisé en métal et être étanche. Le bobineau spiralé comporte une plaque rectangulaire souple d'électrode négative 31 , une plaque rectangulaire souple d'électrode positive 33 et deux séparateurs 32 et 34. Les séparateurs 32 et 34 peuvent être formés dans une même couche repliée à une extrémité. Les électrodes 31 et 33 et les séparateurs 32 et 34 sont enroulés autour de l'axe du godet cylindrique 301 . En l'occurrence, les électrodes 31 et 32 et les séparateurs 32 et 34 sont enroulés autour d'un arbre isolant 35. Cet arbre isolant 35 est fixé dans la partie centrale de l'accumulateur 3. L'enroulement est réalisé de façon à réaliser une alternance de couches électrode positive-séparateur-électrode négative- séparateur. Chaque séparateur 32, 34 sert à isoler électriquement l'électrode positive 33 de l'électrode négative 31 . Les séparateurs 32 et 34 peuvent également servir à isoler entre elles les parties extérieures respectivement positive et négative de l'accumulateur 3. Le bobineau est baigné dans un électrolyte qui permet un échange ionique. FIG. 1 is a sectional view of an electrochemical accumulator 3. This accumulator 3 is in this case a spiral accumulator of cylindrical shape. Such an accumulator 3 includes a spiral coil. The accumulator 3 comprises a bucket or cylindrical housing 301 in which is housed the spiral wound coil of the electrodes. The bucket or cylindrical housing 301 is typically conductive. The cylindrical cup 301 can be made of metal and be waterproof. The coiled coil comprises a rectangular flexible plate of negative electrode 31, a rectangular plate of positive electrode 33 and two separators 32 and 34. The separators 32 and 34 can be formed in the same folded layer at one end. The electrodes 31 and 33 and the separators 32 and 34 are wound around the axis of the cylindrical cup 301. In this case, the electrodes 31 and 32 and the separators 32 and 34 are wound around an insulating shaft 35. This insulating shaft 35 is fixed in the central part of the accumulator 3. The winding is made in such a way as to perform alternating positive-separator-negative electrode-electrode layers separator. Each separator 32, 34 serves to electrically isolate the positive electrode 33 from the negative electrode 31. The separators 32 and 34 can also be used to isolate the positive and negative outer portions of the accumulator 3 respectively. The coil is immersed in an electrolyte which allows ion exchange.
Une face inférieure du godet 301 forme le pôle négatif. Un pôle positif 302 est connecté, généralement par soudure, à l'électrode positive 33 par l'intermédiaire d'une connexion 37 et d'un couvercle 38. Le pôle positif 302 et le couvercle 38 sont isolés électriquement du godet 301 .  A lower face of the bucket 301 forms the negative pole. A positive pole 302 is connected, generally by soldering, to the positive electrode 33 via a connection 37 and a cover 38. The positive pole 302 and the cover 38 are electrically isolated from the bucket 301.
Une partie 303 des séparateurs 32 et 34 est en saillie axialement pour éviter un contact entre les électrodes 31 et 33. A proximité de l'axe de l'accumulateur 3, des entretoises 36 sont en saillie axialement par rapport aux électrodes 31 , 33 et aux séparateurs 32, 34. Les entretoises 36 supportent la connexion 37. Les entretoises 36 peuvent être formées par des saillies des spires centrales des séparateurs 32 et 34. Ainsi, les entretoises 36 empêchent que la connexion 37 vienne accidentellement en contact avec l'électrode négative 31 .  A part 303 of the separators 32 and 34 protrudes axially to prevent contact between the electrodes 31 and 33. In the vicinity of the axis of the accumulator 3, spacers 36 project axially with respect to the electrodes 31, 33 and The spacers 36 support the connection 37. The spacers 36 may be formed by protrusions of the central turns of the separators 32 and 34. Thus, the spacers 36 prevent the connection 37 from accidentally coming into contact with the electrode. negative 31.
La figure 2 est une vue en coupe agrandie d'une superposition de couches du bobineau lors d'un exemple de court-circuit local. Dans l'exemple, le séparateur 32 interposé entre l'électrode négative 31 et l'électrode positive 33 comporte un orifice traversant 39. Un courant électrique s'établit entre l'électrode 33 et l'électrode 31 à travers l'orifice 39, comme illustré par les flèches. Étant donnée la quantité d'énergie pouvant être stockée dans les électrodes 31 et 33, le courant traversant l'orifice 39 peut présenter une amplitude très élevée et conduire à un échauffement des électrodes 31 , 33 et du film 32. L'échauffement peut induire une détérioration en chaîne à l'intérieur de l'accumulateur 3. Une destruction de l'accumulateur 3 peut induire un réchauffement suffisant pour se propager à d'autres accumulateurs adjacents du reste d'une batterie ou au système à alimenter.  Figure 2 is an enlarged sectional view of a layer superposition of the coil in an example of a local short circuit. In the example, the separator 32 interposed between the negative electrode 31 and the positive electrode 33 has a through orifice 39. An electric current is established between the electrode 33 and the electrode 31 through the orifice 39, as illustrated by the arrows. Given the amount of energy that can be stored in the electrodes 31 and 33, the current flowing through the orifice 39 can have a very high amplitude and lead to a heating of the electrodes 31, 33 and the film 32. The heating can induce chain damage within the battery 3. Destruction of the battery 3 may induce sufficient heating to spread to other accumulators adjacent to the rest of a battery or the system to be powered.
La figure 4 est un diagramme représentant une simulation de dysfonctionnements d'un accumulateur 3. Dans ce diagramme, la courbe en pointillés illustre la température à l'intérieur de l'accumulateur 3 au niveau d'un court-circuit et la courbe en trait plein illustre la température mesurée par un capteur de type thermocouple disposé de façon classique à l'extérieur du boîtier 301 . Le cycle simulé comprend une première phase d'échauffement, suivie d'une deuxième phase de refroidissement. Les mesures ont été effectuées en incluant une résistance chauffante commandée à l'intérieur du boîtier 301 .  FIG. 4 is a diagram showing a simulation of malfunctions of an accumulator 3. In this diagram, the dashed curve illustrates the temperature inside the accumulator 3 at the level of a short circuit and the line curve. solid illustrates the temperature measured by a thermocouple type sensor conventionally disposed outside the housing 301. The simulated cycle comprises a first heating phase, followed by a second cooling phase. The measurements were performed by including a controlled heating resistor inside the housing 301.
On constate que la température mesurée à l'extérieur par le thermocouple ne s'élève que lentement et avec un certain retard. Par ailleurs, cette température mesurée à l'extérieur du boîtier 301 garde une amplitude relativement limitée, qu'il est délicat de dissocier d'un échauffement usuel en cours de décharge de l'accumulateur 3. Il est nécessaire d'attendre une durée conséquente avant de pouvoir déterminer que la température extérieure a atteint une amplitude anormale liée à un court-circuit. La figure 3 est une représentation schématique d'un accumulateur 3 selon un exemple de mise en oeuvre de l'invention. L'accumulateur 3 peut présenter la structure illustrée à la figure 1 et ainsi comprendre un boîtier incluant deux électrodes de polarités opposées plongées dans un électrolyte. L'électrode positive et l'électrode négative peuvent ainsi chacune inclure des films conducteurs respectifs. Les films conducteurs de ces électrodes peuvent être superposés en alternance et séparés par au moins un film séparateur isolant. Comme dans l'exemple de la figure 1 , les films d'électrode et les films séparateurs peuvent être superposés en alternance dans un enroulement autour d'un axe, de façon à former un accumulateur 3 sous forme de bobineau. It can be seen that the temperature measured outside by the thermocouple only rises slowly and with a certain delay. Furthermore, this temperature measured outside the housing 301 retains a relatively limited amplitude, which is difficult to dissociate from a conventional heating in discharge course of the accumulator 3. It is necessary to wait a substantial time before it can be determined that the outside temperature has reached an abnormal amplitude related to a short circuit. Figure 3 is a schematic representation of an accumulator 3 according to an exemplary implementation of the invention. The battery 3 may have the structure shown in Figure 1 and thus comprise a housing including two electrodes of opposite polarities immersed in an electrolyte. The positive electrode and the negative electrode can thus each include respective conductive films. The conductive films of these electrodes may be alternately superposed and separated by at least one insulating separator film. As in the example of FIG. 1, the electrode films and the separator films can be superposed alternately in a winding around an axis, so as to form a battery 3 in the form of a coil.
Du matériau ferromagnétique est contenu dans le boîtier. Le matériau ferromagnétique est par exemple inclus dans une ou les deux électrodes, afin d'accroître l'amplitude du champ magnétique rémanent généré. Pour sa part, un accumulateur 3 de type lithium-ion contient du LiFeP04 qui est un matériau antiferromagnétique dont la susceptibilité est faible par rapport à celle de certains matériaux ferromagnétiques. La figure 5 illustre l'inverse de la susceptibilité magnétique du LiFeP04 en ordonnée en fonction de sa température en abscisse. D'une manière générale, le matériau ferromagnétique déjà présent dans une pile lithium-ion est sensible à la température, ce qui modifie son aimantation jusqu'à la rendre très faible lorsqu'on se rapproche de la température de Curie. Ferromagnetic material is contained in the housing. The ferromagnetic material is for example included in one or both electrodes, in order to increase the amplitude of the remanent magnetic field generated. For its part, a lithium-ion-type accumulator 3 contains LiFePO 4, which is an antiferromagnetic material whose susceptibility is low compared to that of certain ferromagnetic materials. FIG. 5 illustrates the inverse of the magnetic susceptibility of LiFePO 4 on the ordinate as a function of its temperature on the abscissa. In general, the ferromagnetic material already present in a lithium-ion battery is sensitive to temperature, which modifies its magnetization to make it very weak when approaching the Curie temperature.
Si le matériau des électrodes à la base de la réaction électrochimique n'est que trop faiblement ferromagnétique, du matériau additionnel ferromagnétique peut être inclus dans l'accumulateur. Un tel matériau additionnel présentera avantageusement une température de Curie inférieure à 600 °C, de préférence inférieure à 400 °C. Avec une telle température de Curie, on disposera d'une bonne sensibilité de mesure à l'élévation de température. Par exemple, au moins l'une des deux électrodes peut inclure un matériau additionnel ferromagnétique. Ce matériau sera avantageusement choisi pour l'amplitude élevée de son champ magnétique rémanent ou de son champ coercitif Hc. L'une des deux électrodes peut ainsi inclure de la ferrite de baryum ou de la ferrite de strontium.  If the material of the electrodes at the base of the electrochemical reaction is only too weakly ferromagnetic, additional ferromagnetic material may be included in the accumulator. Such additional material will advantageously have a Curie temperature of less than 600 ° C., preferably less than 400 ° C. With such a Curie temperature, a good measurement sensitivity will be available at the temperature rise. For example, at least one of the two electrodes may include additional ferromagnetic material. This material will advantageously be chosen for the high amplitude of its remanent magnetic field or its coercive field Hc. One of the two electrodes may thus include barium ferrite or strontium ferrite.
L'accumulateur 3 comprend un capteur magnétique 1 1 placé à l'extérieur du boîtier de l'accumulateur 3. L'implantation du capteur magnétique 1 1 ne perturbe ainsi pas l'étanchéité de l'accumulateur 3 et n'accroît pas les risques d'apparition d'un court-circuit dans le boîtier. Le capteur magnétique 1 1 est susceptible de mesurer les variations de champs magnétiques à l'intérieur du boîtier de l'accumulateur 3. Le capteur 1 1 est avantageusement accolé au boîtier de l'accumulateur 3 pour présenter une sensibilité maximale aux variations de champs magnétiques à l'intérieur du boîtier de l'accumulateur 3. En l'absence d'application d'un champ magnétique d'aimantation depuis l'extérieur, le capteur 1 1 mesure ainsi le cumul du champ magnétique ambiant et du champ magnétique rémanent de l'intérieur du boîtier. The accumulator 3 comprises a magnetic sensor 1 1 placed outside the housing of the accumulator 3. The implantation of the magnetic sensor January 1 thus does not disturb the sealing of the accumulator 3 and does not increase the risks occurrence of a short circuit in the housing. The magnetic sensor 1 1 is capable of measuring the variations of magnetic fields inside the 3. The sensor 1 1 is advantageously coupled to the housing of the battery 3 to have a maximum sensitivity to the variations of magnetic fields inside the housing of the battery 3. In the absence of application of a magnetic field of magnetization from the outside, the sensor 1 1 thus measures the accumulation of the ambient magnetic field and the remanent magnetic field of the interior of the housing.
Dans un accumulateur 3 cylindrique, le capteur 1 1 est avantageusement configuré pour mesurer essentiellement le champ magnétique perpendiculaire à l'axe de l'accumulateur et rejeter le champ magnétique selon l'axe de cet accumulateur 3. Ainsi, le capteur 1 1 est moins sensible aux courants de charge ou de décharge de l'accumulateur 3 en fonctionnement normal, à l'origine d'un champ magnétique selon l'axe de l'accumulateur 3. La variation du champ magnétique rémanent généré par le réchauffement du matériau ferromagnétique sera généralement observable selon une direction. Une telle variation de champ sera bien mesurée par un capteur 1 1 capable de mesurer la composante radiale du champ magnétique à l'intérieur du boîtier dès lors qu'il pourra s'aligner selon la direction dudit champ. Dans cet exemple, une importante aimantation de l'accumulateur 3 est réalisée préalablement à sa mise en service, afin d'obtenir un niveau significatif du champ magnétique rémanent du matériau ferromagnétique. Cette aimantation préalable peut définir un champ magnétique rémanent non isotrope du matériau ferromagnétique, avec une orientation dominante. Le capteur 1 1 est avantageusement positionné pour mesurer le champ magnétique rémanent selon cette orientation dominante.  In a cylindrical accumulator 3, the sensor 1 1 is advantageously configured to essentially measure the magnetic field perpendicular to the axis of the accumulator and reject the magnetic field along the axis of this accumulator 3. Thus, the sensor 1 1 is less responsive to the charging or discharging currents of the accumulator 3 during normal operation, at the origin of a magnetic field along the axis of the accumulator 3. The variation of the remanent magnetic field generated by the heating of the ferromagnetic material will be generally observable in one direction. Such a field variation will be well measured by a sensor January 1 capable of measuring the radial component of the magnetic field inside the housing as soon as it can align in the direction of said field. In this example, a large magnetization of the accumulator 3 is performed prior to its commissioning, in order to obtain a significant level of the remanent magnetic field of the ferromagnetic material. This prior magnetization can define a non-isotropic remanent magnetic field of the ferromagnetic material, with a dominant orientation. The sensor 1 1 is advantageously positioned to measure the remanent magnetic field according to this dominant orientation.
L'accumulateur 3 inclut un circuit 1 3 configuré pour déterminer la température à l'intérieur du boîtier en fonction du champ magnétique rémanent mesuré. Cette température peut être déterminée sur la base d'une loi de température en fonction du champ magnétique rémanent mesuré qui peut être mémorisée dans le circuit 1 3. Cette loi peut être extrapolée à partir d'une courbe telle que celle illustrée à la figure 1 0. La figure 1 1 illustre également la polarisation à saturation et le champ d'anisotropie en fonction de la température pour une ferrite hexagonale de baryum. Un tel diagramme peut également être utilisé pour déterminer la température à l'intérieur du boîtier en fonction du champ magnétique rémanent mesuré.  The accumulator 3 includes a circuit 13 configured to determine the temperature inside the housing as a function of the measured residual magnetic field. This temperature can be determined on the basis of a temperature law as a function of the measured remanent magnetic field which can be stored in the circuit 1 3. This law can be extrapolated from a curve such as that illustrated in FIG. 0. Figure 11 also illustrates the saturation polarization and anisotropy field versus temperature for hexagonal barium ferrite. Such a diagram can also be used to determine the temperature inside the housing as a function of the measured remanent magnetic field.
Avantageusement, l'accumulateur 3 inclut un second capteur magnétique 1 2 également placé à l'extérieur du boîtier. Ce capteur magnétique 1 2 présente une sensibilité au champ magnétique à l'intérieur du boîtier inférieure à celle du capteur 1 1 . Cette sensibilité au champ magnétique à l'intérieur du boîtier du capteur 1 2 est avantageusement sensiblement nulle. Le capteur 1 2 mesure ainsi le champ ambiant, pour tenir compte par exemple du champ magnétique terrestre. Une telle sensibilité inférieure peut être obtenue en éloignant le capteur 1 2 de l'accumulateur 3 ou en le séparant de l'accumulateur 3 par l'intermédiaire d'un blindage. Le circuit 1 3 réalise avantageusement une mesure différentielle entre le champ magnétique mesuré par le capteur 1 1 et le champ magnétique mesuré par le capteur 1 2. En présence de certaines sources parasites plus proches avec un encombrement fréquentiel donné, le circuit 1 3 peut appliquer une fonction de transfert entre les capteurs 1 1 et 1 2, par exemple selon une technique de réduction de bruit avec références, comme le filtrage de Wiener. Ainsi, pour des champs magnétiques relativement faibles à l'intérieur du boîtier, on peut obtenir une mesure de la variation de ce champ rémanent généré par un éventuel échauffement de façon relativement précise, en rejetant l'influence du champ magnétique environnant de l'accumulateur 3. Dans cet exemple, l'accumulateur 3 comprend un unique capteur 1 1 accolé à son boîtier. Ce capteur 1 1 est avantageusement disposé à mi longueur le long de l'axe de l'accumulateur 3, afin de pouvoir détecter de façon optimale des augmentations de température dans le boîtier sur toute la longueur de l'accumulateur 3. Plusieurs capteurs magnétiques 1 1 pourront bien entendu être répartis radialement autour de l'accumulateur 3, ou le long de l'axe de l'accumulateur 3. Advantageously, the battery 3 includes a second magnetic sensor 1 2 also placed outside the housing. This magnetic sensor 1 2 has a sensitivity to the magnetic field inside the lower housing to that of the sensor 1 January. This sensitivity to the magnetic field inside the housing of the sensor 1 2 is advantageously substantially zero. The sensor 1 2 thus measures the ambient field, to take account, for example, of the earth's magnetic field. Such a lower sensitivity can be obtained by moving the sensor 1 2 away from the battery 3 or by separating it from the battery 3 by through a shield. The circuit 1 3 advantageously makes a differential measurement between the magnetic field measured by the sensor 1 1 and the magnetic field measured by the sensor 1 2. In the presence of certain parasitic sources closer with a given frequency congestion, the circuit 1 3 can apply a transfer function between the sensors 1 1 and 1 2, for example according to a noise reduction technique with references, such as Wiener filtering. Thus, for relatively weak magnetic fields inside the housing, it is possible to obtain a measurement of the variation of this remanent field generated by a possible heating in a relatively precise manner, by rejecting the influence of the surrounding magnetic field of the accumulator. 3. In this example, the accumulator 3 comprises a single sensor 1 1 attached to its housing. This sensor 1 1 is advantageously disposed at mid length along the axis of the accumulator 3, in order to optimally detect temperature increases in the housing over the entire length of the accumulator 3. Several magnetic sensors 1 1 may of course be distributed radially around the accumulator 3, or along the axis of the accumulator 3.
Afin de renforcer l'amplitude de la variation du champ magnétique rémanent généré par un échauffement du matériau ferromagnétique dans le boîtier du fait d'un éventuel court-circuit, afin de maîtriser l'orientation dudit champ vis-à-vis de l'orientation du capteur 1 1 , ou afin de permettre de recalibrer le champ magnétique rémanent, selon la deuxième variante illustrée à la figure 12, l'accumulateur 3 comprend avantageusement un dispositif d'aimantation 14 de l'intérieur du boîtier. Le dispositif d'aimantation 14 est par exemple configuré pour générer un champ magnétique orienté perpendiculairement à l'axe de l'accumulateur 3, préalablement à une mesure par le capteur 1 1 . Avantageusement, le dispositif d'aimantation 14 est configuré pour générer un champ magnétique à l'intérieur du boîtier de l'accumulateur 3 sur commande, de façon dynamique. Ainsi, le dispositif d'aimantation 14 peut inclure un bobinage configuré pour appliquer à champ magnétique à l'intérieur du boîtier seulement lorsque ce bobinage est alimenté électriquement.  In order to enhance the amplitude of the variation of the remanent magnetic field generated by a heating of the ferromagnetic material in the housing due to a possible short-circuit, in order to control the orientation of said field vis-à-vis the orientation of the sensor 1 1, or to allow to recalibrate the remanent magnetic field, according to the second variant illustrated in Figure 12, the accumulator 3 advantageously comprises a magnetization device 14 of the interior of the housing. The magnetization device 14 is for example configured to generate a magnetic field oriented perpendicularly to the axis of the accumulator 3, prior to measurement by the sensor January 1. Advantageously, the magnetization device 14 is configured to generate a magnetic field inside the housing of the accumulator 3 on command, dynamically. Thus, the magnetizer 14 may include a coil configured to apply magnetic field within the housing only when this coil is electrically powered.
Avantageusement, le circuit 1 3 est configuré pour alterner l'alimentation d'une telle bobine (et ainsi la génération du champ magnétique d'aimantation du matériau ferromagnétique) et la récupération d'une mesure de champ magnétique réalisée par le capteur 1 1 (et le cas échéant le capteur 1 2). Ainsi, la mesure de champ magnétique prise en compte par le capteur 1 1 (et le cas échéant le capteur 12) correspond bien au champ magnétique rémanent du matériau ferromagnétique à l'intérieur du boîtier, utilisée pour déterminer la température à l'intérieur de l'accumulateur 3. La figure 6 illustre la différence des champs magnétiques mesurés par les capteurs magnétiques 1 1 et 12. La figure 7 illustre la température mesurée en simultané lors du cycle illustré à la figure 4 par un thermocouple extérieur au boîtier. Les capteurs 1 1 et 1 2 utilisés sont des portes de flux (dites fluxgates en langue anglaise) commercialisées sous la référence FLC1 00 par la société Stefan Mayer Instruments. Advantageously, the circuit 1 3 is configured to alternate the supply of such a coil (and thus the generation of the magnetization magnetic field of the ferromagnetic material) and the recovery of a magnetic field measurement made by the sensor 1 1 ( and if necessary the sensor 1 2). Thus, the magnetic field measurement taken into account by the sensor 1 1 (and optionally the sensor 12) corresponds to the remanent magnetic field of the ferromagnetic material inside the housing, used to determine the temperature inside the the accumulator 3. FIG. 6 illustrates the difference of the magnetic fields measured by the magnetic sensors 1 1 and 12. FIG. 7 illustrates the temperature measured in simultaneous during the cycle illustrated in Figure 4 by a thermocouple outside the housing. The sensors 1 1 and 1 2 used are flow gates (known as fluxgates in English) marketed under the reference FLC1 00 by Stefan Mayer Instruments.
Lors du réchauffement, le différentiel entre les champs magnétiques mesurés (correspondant au champ magnétique rémanent) augmente rapidement puis décroît progressivement au fur et à mesure du réchauffement à l'intérieur du boîtier de l'accumulateur 3. Lorsque la phase de refroidissement est initiée, le différentiel entre les champs magnétiques mesurés diminue rapidement, puis croît progressivement au fur et à mesure du refroidissement à l'intérieur du boîtier de l'accumulateur 3. À la fin du refroidissement, lorsque l'intérieur du boîtier de l'accumulateur 3 retrouve sa température initiale, le différentiel entre les champs magnétiques retrouve quasiment sa valeur d'origine, avec un écart de seulement 25nT. Ainsi, on peut considérer que la mesure de champs magnétiques permet de réaliser des mesures de température répétitives de façon très fiable.  During the heating, the differential between the measured magnetic fields (corresponding to the remanent magnetic field) increases rapidly and then gradually decreases as the inside of the battery casing 3 warms up. When the cooling phase is initiated, the differential between the measured magnetic fields decreases rapidly, then progressively increases as the inside of the battery casing 3 cools down. At the end of the cooling, when the inside of the casing of the accumulator 3 recovers its initial temperature, the differential between the magnetic fields returns to its original value, with a difference of only 25nT. Thus, it can be considered that the measurement of magnetic fields makes it possible to perform repetitive temperature measurements in a very reliable manner.
Alors qu'il est nécessaire de plonger un thermocouple dans l'accumulateur 3 pour effectuer une mesure thermique significative et permettre d'identifier un éventuel dysfonctionnement, une mesure de température selon l'invention permet d'identifier un dysfonctionnement sans altérer l'intégrité de l'accumulateur 3 et en un temps réduit.  While it is necessary to immerse a thermocouple in the accumulator 3 to carry out a significant thermal measurement and to identify a possible malfunction, a temperature measurement according to the invention makes it possible to identify a malfunction without altering the integrity of the device. the accumulator 3 and in a reduced time.
La figure 8 illustre un système d'alimentation électrique 1 . Dans ce système d'alimentation, une batterie 2 comprend plusieurs accumulateurs électrochimiques 3 selon l'invention. Une charge électrique 5 est connectée aux bornes de la batterie 2 par l'intermédiaire d'un interrupteur commandé 1 5. Figure 8 illustrates a power supply system 1. In this power system, a battery 2 comprises several electrochemical accumulators 3 according to the invention. An electric charge 5 is connected to the terminals of the battery 2 by means of a controlled switch 1 5.
Chaque accumulateur 3 comprend un capteur magnétique 1 1 mesurant le champ magnétique rémanent à l'intérieur de son boîtier. Les capteurs 1 1 sont connectés à un circuit de commande commun 13. Le circuit de commande commun 1 3 commande avantageusement des dispositifs d'aimantation respectifs des accumulateurs 3. Un capteur magnétique commun 1 2 mesure le champ magnétique environnant de la batterie 2. Par une mesure différentielle entre chacun des champs magnétiques rémanents mesurés par les capteurs 1 1 et par le capteur 1 2, le circuit de commande 1 3 déduit la température à l'intérieur du boîtier de chacun des accumulateurs 3.  Each accumulator 3 comprises a magnetic sensor 1 1 measuring the remanent magnetic field inside its housing. The sensors 1 1 are connected to a common control circuit 13. The common control circuit 1 3 advantageously controls the respective magnetization devices of the accumulators 3. A common magnetic sensor 1 2 measures the surrounding magnetic field of the battery 2. a differential measurement between each of the remanent magnetic fields measured by the sensors 1 1 and the sensor 1 2, the control circuit 1 3 deduces the temperature inside the housing of each of the accumulators 3.
Dans la deuxième variante, le circuit de commande commun 1 3 commande avantageusement l'application préalable d'un champ magnétique d'aimantation par l'intermédiaire du dispositif d'aimantation 14. Le circuit de commande 1 3 commande ensuite le dispositif d'aimantation 14 pour supprimer le champ magnétique appliqué par celui-ci. Le champ magnétique rémanent est alors mesuré par mesure différentielle des capteurs 1 1 et 12, en absence du champ magnétique d'aimantation. In the second variant, the common control circuit 1 3 advantageously controls the prior application of a magnetization magnetic field by means of the magnetization device 14. The control circuit 1 3 then controls the magnetization device 14 to suppress the magnetic field applied by it. The remnant magnetic field is then measured by differential measurement of the sensors 1 1 and 12, in the absence of the magnetization magnetic field.
Lorsque la température déterminée pour l'un des accumulateurs 3 dépasse un seuil, le circuit de commande 13 peut commander l'ouverture de l'interrupteur 15 afin d'interrompre la décharge de la batterie 2 dans la charge électrique 5. Le circuit de commande 13 peut ainsi limiter les conséquences d'un court-circuit à l'intérieur de l'un des accumulateurs 3. Le circuit de commande 13 assure ainsi la supervision du fonctionnement des accumulateurs 3.  When the temperature determined for one of the accumulators 3 exceeds a threshold, the control circuit 13 can control the opening of the switch 15 to interrupt the discharge of the battery 2 in the electric charge 5. The control circuit 13 can thus limit the consequences of a short circuit inside one of the accumulators 3. The control circuit 13 thus ensures the supervision of the operation of the accumulators 3.
Dans cet exemple, la charge électrique 5 est découplée de l'ensemble de la batterie 2 par l'intermédiaire de l'interrupteur 15. On peut également envisager d'isoler uniquement un accumulateur 3 dont un dysfonctionnement a été identifié en le déconnectant des autres accumulateurs de la batterie 2, afin d'éviter une décharge des autres accumulateurs vers celui-ci, et en garantissant la continuité de service de la batterie 2. Des interrupteurs peuvent ainsi être inclus dans la batterie 2 afin de pouvoir isoler chacun des accumulateurs 3 par une commande du circuit 13.  In this example, the electric charge 5 is decoupled from the entire battery 2 by means of the switch 15. It is also possible to isolate only an accumulator 3, a malfunction of which has been identified by disconnecting it from the others. accumulators of the battery 2, in order to avoid a discharge of the other accumulators towards it, and guaranteeing the continuity of service of the battery 2. Switches can thus be included in the battery 2 in order to be able to isolate each of the accumulators 3 by a command of the circuit 13.
Pour les batteries au lithium, la température normale de fonctionnement s'étend jusqu'à 60 °C, voire 80 °C. Au-delà de la température normale de fonctionnement, les performances de la batterie se dégradent fortement et celle- ci peut devenir dangereuse. Jusqu'à une température de sécurité de 1 10°C, voire 130°C, le phénomène est cependant réversible. Au-delà de cette température de sécurité, on est confronté à un phénomène d'emballement thermique. Le circuit 13 peut ainsi être programmé pour générer un premier signal d'alerte et isoler une batterie 2 lorsque sa température est supérieure à la température normale de fonctionnement, et générer un deuxième signal d'alerte lorsque la température de cette batterie 2 est supérieure à la température de sécurité en vue par exemple d'activer un extincteur ou un noyage dans un gaz inerte. Bien que l'accumulateur 3 soit un accumulateur à bobineau dans l'exemple illustré, l'invention s'applique bien entendu également à d'autres structures d'accumulateurs, par exemple un accumulateur comportant un empilement de films d'électrode et de séparateur. Un tel accumulateur peut notamment présenter une forme non cylindrique. L'accumulateur peut par exemple être de type prismatique et inclure un empilement de couches plates d'électrodes et de séparateurs.  For lithium batteries, the normal operating temperature is up to 60 ° C or 80 ° C. Beyond the normal operating temperature, the performance of the battery deteriorates strongly and can become dangerous. Up to a safety temperature of 1 10 ° C, or even 130 ° C, the phenomenon is however reversible. Beyond this safety temperature, there is a phenomenon of thermal runaway. The circuit 13 can thus be programmed to generate a first warning signal and to isolate a battery 2 when its temperature is higher than the normal operating temperature, and to generate a second warning signal when the temperature of this battery 2 is greater than the safety temperature for example to activate a fire extinguisher or flooding in an inert gas. Although the accumulator 3 is a coil accumulator in the illustrated example, the invention naturally also applies to other battery structures, for example an accumulator comprising a stack of electrode and separator films. . Such an accumulator may in particular have a non-cylindrical shape. The accumulator may for example be prismatic type and include a stack of flat layers of electrodes and separators.
La mise en sécurité d'un accumulateur 3 a été décrite dans le cadre d'une décharge de celui-ci dans une charge électrique. La mise en sécurité d'un accumulateur 3 peut bien entendu également être effectuée lorsque celui-ci est connecté à un système de recharge.  The safety of a battery 3 has been described in the context of a discharge of the latter in an electric charge. The safety of a battery 3 can of course also be performed when it is connected to a charging system.

Claims

REVENDICATIONS
1 . Accumulateur électrochimique (3), caractérisé en ce qu'il comprend : 1. Electrochemical accumulator (3), characterized in that it comprises:
-un boîtier (301 ) ; a housing (301);
-au moins deux électrodes (31 ,33) et un électrolyte contenus dans le boîtier ; -au moins du matériau ferromagnétique contenu dans le boîtier et présentant une aimantation rémanente; at least two electrodes (31, 33) and an electrolyte contained in the housing; at least the ferromagnetic material contained in the housing and having a remanent magnetization;
-un capteur magnétique disposé à l'extérieur du boîtier et susceptible de mesurer le champs magnétiques rémanent dudit matériau ferromagnétique ;  a magnetic sensor disposed outside the housing and capable of measuring the remanent magnetic fields of said ferromagnetic material;
-un circuit configuré pour déterminer la température à l'intérieur du boîtier en fonction du champ magnétique rémanent mesuré. a circuit configured to determine the temperature inside the housing as a function of the measured residual magnetic field.
2. Accumulateur électrochimique (3) selon la revendication 1 , dans lequel lesdites électrodes incluent chacune un film d'électrode respectif, lesdits films d'électrode (31 , 33) étant superposés en alternance, lesdits films d'électrode étant séparés par au moins un film séparateur isolant (32, 34). An electrochemical accumulator (3) according to claim 1, wherein said electrodes each include a respective electrode film, said electrode films (31,33) being alternately superimposed, said electrode films being separated by at least one an insulating separating film (32, 34).
3. Accumulateur électrochimique (3) selon la revendication 1 ou 2, dans lequel lesdits films (31 , 32, 33, 34) sont enroulés autour d'un même axe. 3. electrochemical accumulator (3) according to claim 1 or 2, wherein said films (31, 32, 33, 34) are wound around a same axis.
4. Accumulateur électrochimique (3) selon la revendication 3, dans lequel ledit capteur est susceptible de mesurer la composante du champ magnétique à l'intérieur du boîtier selon une perpendiculaire audit axe. 4. electrochemical accumulator (3) according to claim 3, wherein said sensor is capable of measuring the component of the magnetic field inside the housing at a perpendicular to said axis.
5. Accumulateur électrochimique (3) selon l'une quelconque des revendications précédentes, dans lequel au moins une desdites électrodes inclut du LiFeP04. An electrochemical accumulator (3) according to any one of the preceding claims, wherein at least one of said electrodes includes LiFePO4.
6. Accumulateur électrochimique (3) selon l'une quelconque des revendications précédentes, dans lequel au moins une desdites électrodes inclut de la ferrite de strontium ou de la ferrite de baryum. An electrochemical accumulator (3) according to any one of the preceding claims, wherein at least one of said electrodes includes strontium ferrite or barium ferrite.
7. Accumulateur électrochimique selon l'une quelconque des revendications précédentes, dans lequel au moins une desdites électrodes inclut un matériau présentant une polarisation à saturation supérieure à 0,4 T à 0°C. An electrochemical accumulator according to any one of the preceding claims, wherein at least one of said electrodes includes a material having a saturation polarization greater than 0.4 T at 0 ° C.
8. Accumulateur électrochimique (3) selon l'une quelconque des revendications précédentes, dans lequel ledit matériau ferromagnétique présente une température de Curie inférieure à 600 °C. An electrochemical accumulator (3) according to any one of the preceding claims, wherein said ferromagnetic material has a Curie temperature of less than 600 ° C.
9. Accumulateur électrochimique (3) selon l'une quelconque des revendications précédentes, dans lequel ledit capteur magnétique est un premier capteur magnétique (1 1 ), l'accumulateur incluant en outre un deuxième capteur magnétique (1 2) disposé à l'extérieur du boîtier (301 ) et présentant une sensibilité au champ magnétique de l'intérieur du boîtier inférieure à la sensibilité du premier capteur magnétique à ce même champ. Electrochemical accumulator (3) according to any one of the preceding claims, wherein said magnetic sensor is a first sensor. magnetic (1 1), the accumulator further including a second magnetic sensor (1 2) disposed outside the housing (301) and having a magnetic field sensitivity of the interior of the housing less than the sensitivity of the first sensor magnetic at this same field.
1 0. Accumulateur électrochimique (3) selon la revendication 9, dans lequel le circuit (1 3) détermine la température à l'intérieur du boîtier (301 ) en fonction de la différence entre le champ mesuré par le premier capteur (1 1 ) et le champ mesuré par le deuxième capteur (1 2). Electrochemical accumulator (3) according to claim 9, wherein the circuit (1 3) determines the temperature inside the housing (301) as a function of the difference between the field measured by the first sensor (1 1). and the field measured by the second sensor (1 2).
1 1 . Accumulateur électrochimique selon l'une quelconque des revendications précédentes, incluant un dispositif d'aimantation (14) de l'intérieur du boîtier, le dispositif d'aimantation (14) incluant un bobinage configuré pour appliquer un champ magnétique à l'intérieur du boîtier (301 ) lorsque ce bobinage est alimenté électriquement, ledit circuit (1 3) étant configuré pour commander l'alimentation électrique dudit bobinage et configuré pour récupérer une mesure du capteur magnétique, le circuit (1 3) étant configuré pour commander des alimentations électriques du bobinage et récupérer des mesures du capteur magnétique de façon alternée. 1 1. An electrochemical accumulator as claimed in any preceding claim, including a magnetization device (14) of the interior of the housing, the magnetizer (14) including a coil configured to apply a magnetic field within the housing (301) when this coil is electrically powered, said circuit (1 3) being configured to control the power supply of said coil and configured to recover a measurement of the magnetic sensor, the circuit (1 3) being configured to control power supplies of the winding and recover measurements of the magnetic sensor alternately.
1 2. Accumulateur électrochimique selon l'une quelconque des revendications précédentes, dans lequel ledit capteur magnétique est configuré pour mesurer le champ magnétique rémanent à l'intérieur du boîtier en l'absence d'application d'un champ magnétique d'aimantation à l'intérieur du boîtier. An electrochemical accumulator as claimed in any one of the preceding claims, wherein said magnetic sensor is configured to measure the remanent magnetic field within the housing in the absence of application of a magnetic field of magnetization. inside the case.
1 3. Système d'alimentation (1 ), comprenant : A feeding system (1), comprising:
-un accumulateur électrochimique (3) selon l'une quelconque des revendications précédentes ;  an electrochemical accumulator (3) according to any one of the preceding claims;
-un interrupteur (1 5) connectant/déconnectant sélectivement l'accumulateur électrochimique des bornes du système d'alimentation destinées à être connectées à une charge électrique (5) ;  a switch (1 5) selectively connecting / disconnecting the electrochemical accumulator from the terminals of the supply system for connection to an electrical load (5);
-un circuit de supervision (1 3) du fonctionnement de l'accumulateur électrochimique commandant la déconnexion entre l'accumulateur électrochimique et les bornes du système d'alimentation lorsque la température mesurée par ledit capteur franchit un seuil.  a supervision circuit (1 3) for the operation of the electrochemical accumulator controlling the disconnection between the electrochemical accumulator and the terminals of the supply system when the temperature measured by said sensor crosses a threshold.
EP13700502.1A 2012-01-09 2013-01-08 Detection of a malfunction in an electrochemical accumulator Withdrawn EP2803100A1 (en)

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FR1250191A FR2985613A1 (en) 2012-01-09 2012-01-09 DETECTION OF DYSFUNCTION IN AN ELECTROCHEMICAL BATTERY
PCT/EP2013/050188 WO2013104603A1 (en) 2012-01-09 2013-01-08 Detection of a malfunction in an electrochemical accumulator

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WO2013104603A1 (en) 2013-07-18
FR2985613A1 (en) 2013-07-12

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