Method for characterising the state of health of a lithium battery with a solid or gel electrolyte and associated devices

Abstract

The invention provides a method for characterising the state of health of at least one electrochemical element (24) of a battery (20), the battery (20) being a battery having a paramagnetic element with a solid or gel electrolyte, the method comprising a step of: - acquiring data relating to the at least one electrochemical element (24), the data comprising a spectrum obtained via the use of an electron paramagnetic resonance technique or an image obtained via the use of an electron paramagnetic resonance technique; and - analysing the acquired data to detect the presence or absence of an abnormal structure of the paramagnetic element in the at least one electrochemical element (24).

Description

[0001] Method for characterizing the state of health of a lithium battery with a solid or gelled electrolyte and associated devices

[0002] The present invention relates to a method for characterizing the state of health of at least one electrochemical element of a battery, the battery being a lithium battery with a solid or gelled electrolyte. The present invention also relates to associated devices, namely a calculator and a characterization device.

[0003] Typically, a battery comprises one or more current accumulators, also called electrochemical generators, cells, or elements. An accumulator is an electricity-generating device in which chemical energy is converted into electrical energy. The chemical energy comes from electrochemically active compounds deposited on at least one face of electrodes arranged in the accumulator. The electrical energy is produced by electrochemical reactions during a discharge of the accumulator. The electrodes, arranged in a container, are electrically connected to current output terminals that ensure electrical continuity between the electrodes and an electrical consumer with which the accumulator is associated.

[0004] In order to increase the electrical power delivered, several sealed accumulators can be combined together to form a battery. Thus, a battery can be divided into modules, each module being composed of one or more accumulators connected together in series and / or in parallel. Thus, a battery can, for example, comprise one or more parallel branches of accumulators connected in series and / or one or more parallel branches of modules connected in series.

[0005] A charging circuit is usually provided to which the battery can be connected to recharge the accumulators.

[0006] Furthermore, an electronic management system comprising measurement sensors and an electronic control circuit, more or less advanced depending on the applications, can be associated with the battery. Such a system makes it possible in particular to organize and control the charging and discharging of the battery, to balance the charging and discharging of the different accumulators in the battery in relation to each other.

[0007] Among these different types of batteries, lithium-ion rechargeable accumulators offer excellent energy and volume densities but present a risk of flammability due to the use of liquid electrolytes.

[0008] As a result, all-solid or hybrid accumulators are being developed, i.e. accumulators using solid or gel electrolytes (for hybrid accumulators). This provides a significant improvement in terms of safety. In particular, solid sulfide electrolytes are reaching a sufficient maturity to consider their industrial application. Their high ionic conductivity values ​​combined with their ductility and limited density make them serious candidates for the first generations of all-solid batteries that can compete with the energy densities of current Li-ion accumulators with liquid electrolytes.

[0009] However, it is desirable to continue developing this type of accumulator, which requires being able to determine the state of health of the battery during operation to optimize its use and lifespan. The state of health is often referred to by the abbreviation SOH, which refers to the English term for "State of Health".

[0010] The SOH state of health allows the aging of the battery to be estimated between a new state and an end-of-life state, or more generally, between an initial state and a final state.

[0011] A SOH determination technique is a technique in which the temperature, voltage, and possibly current values ​​of the battery are monitored to determine a SOH value from aging laws. Such aging laws are obtained from laboratory tests. Applying the aging laws to the monitored values ​​thus gives an estimate of the aging of the battery.

[0012] However, this static type technique assumes homogeneous aging of the battery accumulators and a power circuit without failure between the accumulators.

[0013] Another technique for determining the SOH state of health is a technique in which the ratio of the battery resistance at a given time is calculated by measuring the voltage and current to the resistance of the battery in the new or initial state under the same measurement conditions (in particular under the same temperature conditions). In fact, the resistance increases with the aging of the battery, reflecting a loss of power. In such a case, the expression SOH state of health related to the battery resistance is often used or its abbreviation SOHR which refers to the corresponding English term "State of Health related to battery Resistance".

[0014] It is also known to characterize a resistance on a current step.

[0015] Such a technique consists of measuring the ratio between the voltage variation and the current variation. But such a solution requires a specific additional cycle, and is therefore not natively feasible because it implies the presence of a charger with a significant pulse capacity, which is restrictive for the user.

[0016] Furthermore, such a technique is difficult to reproduce in practice because the pulse time, the state of charge value at the time the pulse is performed, as well as the pulse current, are all variables that influence the resistance measurement. Moreover, even if the technique were feasible and reproducible, the evolution of the chemical properties of the element with aging implies a modification of certain internal parameters such as the time constants for example. Also, such a technique does not provide significant information on the actual aging. As a result, this aging is often minimized when the resistance is estimated on the transient zone of a current step.

[0017] It is also known to obtain the state of health SOH from the ratio of the battery capacity at a given time to the battery capacity in the new or initial state under the same measurement conditions (in particular under the same temperature conditions). In fact, the capacity decreases with aging, reflecting a loss of available energy. In such a case, the expression state of health SOH related to the battery capacity is often used or its abbreviation SOHC which refers to the corresponding English term "State of Health related to battery Capacity".

[0018] Another technique for determining capacity aging is to observe the shape of the element's deformation over a partial cycle.

[0019] However, these methods do not allow the resistance aging of a battery to be determined.

[0020] There is therefore a need for a method for characterizing the state of health of an electrochemical element of an all-solid or hybrid battery which can be implemented under real operating conditions.

[0021] For this purpose, the description describes a method for characterizing the state of health of at least one electrochemical element of a battery, the battery being a battery with a paramagnetic element with an electrolyte in solid or gelled state, the method comprising a step of:

[0022] - acquisition of data relating to the at least one electrochemical element, the data comprising a spectrum obtained by implementing an electronic paramagnetic resonance technique or an image obtained by implementing an electronic paramagnetic resonance technique, and

[0023] - analysis of the acquired data to detect the presence or absence of an abnormal structure of the paramagnetic element in at least one electrochemical element.

[0024] According to particular embodiments, the characterization method has one or more of the following characteristics, taken in isolation or in all technically possible combinations:

[0025] - the abnormal structure is an aggregate or a dendrite. - the method is implemented during the operation of the at least one electrochemical element.

[0026] - the specific data comprises at least one spectrum, the analysis step comprising the recognition of a specific line shape in said at least one spectrum.

[0027] - the acquired data comprises at least one image, the analysis step comprising the search for specific patterns in the at least one image.

[0028] - the method further comprises a step of calculating a parameter of the state of health of the at least one electrochemical element as a function of the presence or absence of an abnormal structure.

[0029] - when at least one abnormal structure is detected during the analysis step, the method further comprises a step of determining at least one property of each abnormal structure.

[0030] - at least one property of each abnormal structure is the location of the abnormal structure.

[0031] - the parameter of the health status of the at least one electrochemical element calculated during the calculation step is also a function of each property determined for each abnormal structure.

[0032] - the method further comprises a step of measuring the temporal evolution of at least one physical quantity of the at least one electrochemical element, the acquired data also comprising the temporal evolution measured in the measurement step.

[0033] - the physical quantity is the pressure within the electrochemical element.

[0034] The description also relates to a calculator adapted to characterize the state of health of at least one electrochemical element of a battery, the battery being a battery with a paramagnetic element with an electrolyte in solid or gel state, the calculator being adapted to:

[0035] - receive data relating to the at least one electrochemical element, the data comprising a spectrum obtained by implementing an electronic paramagnetic resonance technique or an image obtained by implementing an electronic paramagnetic resonance technique, and

[0036] - analyze the acquired data to detect the presence or absence of an abnormal structure of the paramagnetic element in at least one electrochemical element.

[0037] The description also relates to a device for characterizing the state of health of at least one electrochemical element of a battery, the battery being a battery with a paramagnetic element with an electrolyte in solid or gelled state, the characterization device comprising:

[0038] - an imager capable of acquiring data relating to the at least one electrochemical element by an electronic paramagnetic resonance technique, the data comprising a spectrum obtained by implementing an electronic paramagnetic resonance technique or an image obtained by implementing an electronic paramagnetic resonance technique, and

[0039] - a computer capable of analyzing the data acquired by the imager to detect the presence or absence of an abnormal structure of the paramagnetic element in the at least one electrochemical element.

[0040] In this description, the expression "suitable for" means indifferently "adapted for", "adapted to" or "configured for".

[0041] Characteristics and advantages of the invention will appear on reading the description which follows, given solely by way of non-limiting example, and made with reference to the appended drawings, in which:

[0042] - [Fig 1] Figure 1 is a representation of a flowchart of an example of implementation of an example of a method for characterizing an electrochemical element,

[0043] - [Fig 2] Figure 2 is a schematic representation of an example of a battery comprising an electrochemical element on which the characterization method of Figure 1 can be implemented and of an example of a characterization device used in the implementation of the characterization method of Figure 1,

[0044] - [Fig 3] Figure 3 is a schematic representation of part of the characterization device of Figure 2,

[0045] - [Fig 4] Figure 4 is a representation of a flowchart of an example of implementation of another example of a method for characterizing an electrochemical element,

[0046] - [Fig5] Figure 5 is a representation of a flowchart of an example of implementation of yet another example of a method for characterizing an electrochemical element.

[0047] Figure 1 illustrates a flowchart of an example implementation of a characterization method.

[0048] The characterization method is a method for characterizing the state of health of an electrochemical element of a battery 20.

[0049] The battery 20 interacting with a characterization device 22 suitable for implementing the characterization method are shown in FIG. 1. In a manner known per se, a battery is generally an arrangement of a plurality of electrochemical elements but for the sake of simplification of the subject, a case with a single electrochemical element is described in the following, knowing that the transposition to other arrangements is immediate.

[0050] The battery 20 comprises an electrochemical element 24 and a management system 26 for the electrochemical element 24.

[0051] As explained previously, an electrochemical element 24 is an electricity generating device in which chemical energy is converted into electrical energy.

[0052] The electrochemical element 24 therefore delivers a current and a voltage between two terminals.

[0053] In this case, battery 20 is a lithium battery with a solid-state electrolyte.

[0054] The electrochemical element 24 comprises a positive electrode, a negative electrode and an electrolyte.

[0055] The positive electrode (also called cathode) refers to the electrode where electrons enter, and where cations (Li + ) in landfill.

[0056] For the purposes of this example, the positive electrode may be of any known type. The positive electrode typically consists of a conductive support used as a current collector on which the cathode active material and a carbon electronic material are deposited. A binder may also be incorporated into the mixture.

[0057] The cathode active material is not particularly limited. It can be selected from the following groups or their mixtures:

[0058] - a compound (a) of formula LixMi.y. z -wM'yM”zM”' w O2 (LMO2) where M, M', M” and M'” are selected from the group consisting of B, Mg, Al, Si, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, W and Mo with the proviso that at least M or M' or M” or M'” is selected from Mn, Co, Ni, or Fe; M, M', M” and M'” being different from each other; and 0.8 <x<1 ,4 ; 0<y<0,5 ; 0<z<0,5 ; 0<w<0,2 et x+y+z+w<2,1 ;

[0059] - a compound (b) of formula Li x Mn2-y- z M'yM"zO4 (LMO), where M' and M" are selected from the group consisting of B, Mg, Al, Si, Ca, Ti, V, Cr, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb and Mo;. M' and M" being different from each other, and 1 <x<1 ,4 ; 0<y<0,6 ; 0<z<0,2 ;

[0060] - a compound (c) of formula LixFei-yMyPC (LFMP) where M is selected from the group consisting of B, Mg, Al, Si, Ca, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Y, Zr, Nb and Mo; and 0.8 <x<1 ,2 ; 0<y<0,6 ; - un composé (d) de formule Li x Mni.y. z M'yM”zPO4 (LMP), where M' and M” are different from each other and are selected from the group consisting of B, Mg, Al, Si, Ca, Ti, V, Cr, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb and Mo, with 0.8 <x<1 ,2 ; 0<y<0,6 ; 0,0<z<0,2 ;

[0061] - a compound (e) of formula xLi2MnOs; (1 -x)LiMO2 where M is at least one element chosen from Ni, Co and Mn and x<1.

[0062] - a compound (f) of formula Lii +x MO2-yF y of cubic structure where M represents at least one element selected from the group consisting of Na, K, Mg, Ca, B, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Y, Zr, Nb, Mo, Ru, Ag, Sn, Sb, Ta, W, Bi, La, Pr, Eu, Nd and Sm and where 0 < x < 0.5 and 0 < y < 1.

[0063] - a compound (g) of type UVPO4F (LVPF).

[0064] The current collector is, for example, a two-dimensional conductive support such as a solid or perforated strip, based on carbon or metal, for example nickel, steel, stainless steel or aluminum, preferably aluminum. The current collector may be coated on one or both sides with a layer of carbon.

[0065] A current collector is understood to mean an element such as a pad, plate, sheet or other, made of conductive material, connected to the positive or negative electrode, and ensuring the conduction of the flow of electrons between the electrode and the terminals of the battery.

[0066] The carbon electronic material or conductive material is generally selected from graphite, carbon black, acetylene black, soot, graphene, carbon nanotubes or a mixture thereof.

[0067] The carbon electronic material is distributed throughout the active material particles and the current collector.

[0068] The negative electrode (also called the anode) refers to the electrode from which the electrons leave, and from which the cations (Li + ) in landfill.

[0069] The negative electrode typically consists of a conductive support used as a current collector on which the anode active material and a carbon electronic material are deposited. A binder may also be incorporated into the mixture.

[0070] It is understood that in "anode free" systems, a negative electrode is also present (generally initially limited to the current collector only).

[0071] The anodic active material is not particularly limited. It can be selected from the following groups and their mixtures:

[0072] - metallic lithium or a metallic lithium alloy

[0073] - graphite

[0074] - silicon

[0075] - anode-free type

[0076] - a titanium and niobium oxide TNO having the formula LixTia-yMyNbb-zM zO((x+4a+5b) / 2)-c-dXc where:

[0077] • 0 < x < 5; 0 < y < 1; 0 < z < 2; 1 < a < 5; 1 < b < 25; 0.25 < a / b < 2; 0 < c < 2 and 0 < d < 2; ay > 0; bz > 0;

[0078] • M and M' each represent at least one element chosen from the group consisting of Li, Na, K, Mg, Ca, B, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Y, Zr, Nb, Mo, Ru, Ag, Sn, Sb, Ta, W, Bi, La, Pr, Eu, Nd and Sm;

[0079] • X represents at least one element chosen from the group consisting of S, F, Cl and Br.

[0080] • the d index represents an oxygen vacancy. The d index can be less than or equal to 0.5.

[0081] Said at least one titanium and niobium oxide may be chosen from TiNb2O?, Ti2Nb2O?, Ti2Nb2O9 and Ti2Nb O29.

[0082] - a lithiated titanium oxide or a titanium oxide capable of being lithiated. The lithiated titanium oxide is chosen from the following oxides: i) Lix-aMaTiy. b M O4-c-dXc in which:

[0083] • 0 <x<3 ; 1 <y<2,5 ; 0<a<1 ; 0<b<1 ; 0<c<2 et -2,5<d<2,5 ; M représente au moins un élément choisi dans le groupe constitué de Na, K, Mg, Ca, B, Mn, Fe, Co, Cr, Ni, Al, Cu, Ag, Pr, Y et La ;

[0084] • M' represents at least one element chosen from the group consisting of B, Mo, Mn, Ce, Sn, Zr, Si, W, V, Ta, Sb, Nb, Ru, Ag, Fe, Co, Ni, Zn, Al, Cr, La, Pr, Bi, Sc, Eu, Sm, Gd, Ti, Ce, Y and Eu;

[0085] • X represents at least one element chosen from the group consisting of S, F, Cl and Br;

[0086] • the index d represents an oxygen vacancy. The index d can be less than or equal to 0.5. ii) H x TiyO4 in which 0 <x<1 ; 0<y<2, et iii) un mélange des composés i) à ii).

[0087] Examples of lithiated titanium oxides belonging to group i) are spinel Li4Ti50i2, Li2TiOs, ramsdellite Li2Ti3O7, LiTi2C>4, Li x Ti2C>4, with 0 <x<2 et Li2Na2Ti60i4. Un composé LTO préféré a pour formule Li^aMaTis tMbC par exemple Li4Ti50i 2 qui s’écrit encore Li4 / 3Ti5 / 3C> 4.

[0088] The binder possibly present at the positive electrode and the negative electrode has the function of reinforcing the cohesion between the particles of active materials as well as improving the adhesion of the mixture according to the invention to the current collector. The binder may contain one or more of the following elements: polyvinylidene fluoride (PVDF) and its copolymers, polytetrafluoroethylene (PTFE) and its copolymers, polyacrylonitrile (PAN), poly(methyl)- or (butyl)methacrylate, polyvinyl chloride (PVC), poly(vinyl formal), polyester, block polyetheramides, polymers of acrylic acid, methacrylic acid, acrylamide, itaconic acid, sulfonic acid, elastomer and cellulose compounds. The elastomer(s) that can be used as a binder can be chosen from styrene-butadiene (SBR), butadiene-acrylonitrile (NBR), hydrogenated butadiene-acrylonitrile (HNBR), and a mixture of several of these.

[0089] The electrolyte here is a solid electrolyte.

[0090] The electrolyte is notably chosen from sulfur electrolytes, oxide electrolytes, polymer electrolytes, polymer / ceramic hybrid electrolytes and any of their mixtures.

[0091] Preferably, the solid electrolyte is chosen from sulfur electrolytes and polymers.

[0092] More preferably, the solid electrolyte is chosen from sulfur electrolytes, that is to say comprising sulfur, more preferably from sulfide electrolytes, alone or in a mixture with other constituents, such as polymers or gels. Mention may thus be made of partially or completely crystallized sulfides as well as amorphous ones. Examples of these materials may be selected from sulfides of composition A U2S - B P2S5 (with 0 <A<1 ,0<B<1 et A+B = 1 ) et leurs dérivés (par exemple avec dopage Lil, LiBr, LiCI, ...) ; les sulfures de structure argyrodite ; ou type LGPS (Li GeP2Si2), et ses dérivés. Les sulfures formant la couche électrolytique se différencient des composés sulfures formant la couche de revêtement en ce qu’ils présentent une conductivité ionique supérieure à 10 -2 S.nr 1 and electronics between 10 -8 and 10 -10 S.nr 1Electrolytic materials may also include oxysulfides, oxides (garnet, phosphate, anti-perovskite, etc.), hydrides, polymers, gels or ionic liquids that conduct lithium ions.

[0093] Examples of sulfide electrolyte compositions are described in particular in Park, K.H., Bai, Q. Kim, D.H., Oh, D.Y., Zhu, Y., Mo, Y., & Jung, Y.S. (2018). Design Strategies, Practical Considerations, and New Solution Processes of Sulfide Solid Electrolytes for All-Solid-State Batteries. Advanced Energy Materials, 1800035.

[0094] Alternatively, battery 20 is a lithium battery with a gel electrolyte.

[0095] The same compounds as before can be considered for the positive and negative electrodes.

[0096] The term “gelled” is understood to mean an electrolyte having a viscosity less than or equal to 100 mPa.s at 25°C. Of course, these examples are not limiting and the method described later can be used for any type of electrochemical element 24 forming part of an all-solid lithium battery (with a solid-state electrolyte) or hybrid (with a gelled electrolyte).

[0097] The management system 26 is a system suitable for managing the electrochemical element 24.

[0098] The management system 26 generally comprises a set of sensors (for example, voltage, current or temperature) and a computer. These elements are not shown in Figure 2 for reasons of clarity.

[0099] According to the example of figure 2, the characterization device 22 comprises an imager 28 and a calculator 30.

[0100] The imager 28 is capable of acquiring data relating to the electrochemical element 24 by an electronic paramagnetic resonance technique.

[0101] In this case, these data are a spectrum obtained by implementing an electron paramagnetic resonance technique or an image obtained by implementing an electron paramagnetic resonance technique.

[0102] The notion of image here includes both spatial images and spatial representations of a physical quantity.

[0103] In particular, the image can be considered as a representation of the spatial variation of the spectrum of the electrochemical element 24, for example the variation along the central axis of the electrochemical element 24.

[0104] As seen in Figure 2, the imager 28 comprises a cavity 32, a magnetic field generator 34, an excitation unit 36, a detector 38, a waveguide 40 and an adapter 42.

[0105] The cavity 32 is intended to receive the battery 20 comprising the electrochemical element 24 to be studied.

[0106] In the example shown, the cavity 32 has the shape of a rectangular parallelepiped.

[0107] The magnetic field generator 34 is capable of applying a static magnetic field in the cavity 32. The magnetic field generator 34 is, for example, a set of coils supplied with current, the control of the current making it possible to control the amplitude of the static field in the cavity 32.

[0108] The excitation unit 36 ​​is capable of exciting the cavity 32 with an electromagnetic wave. For example, the excitation unit 36 ​​is a microwave source, in particular a microwave source operating at a frequency of between 0.5 GHz and 300 GHz, preferably between 1 GHz and 10 GHz, in particular equal to 9 GHz.

[0109] According to one embodiment, the excitation unit 36 ​​is capable of operating at a frequency between 1 GHz and 2 GHz, preferably at 1 GHz.

[0110] The detector 38 is capable of detecting the absorption by the lithium of the electrochemical element 24 of the microwave excitation emitted by the excitation unit 36.

[0111] It should be noted here that detector 38 is actually capable of detecting the absorption of any paramagnetic species, so that detector 38 is capable of monitoring the evolution of all these species.

[0112] In the example described, the waveguide 40 allows the propagation of microwaves between the adapter 42 on the one hand and the excitation unit 34 and the detector 36 on the other hand. The adapter 42 has an opening in communication with the cavity 32 and allows the propagation of microwaves between the waveguide 40 and the cavity 32.

[0113] The RPE technique and the operation of the different elements of the imager 28 are described more precisely with reference to the description of the implementation of the characterization method according to FIG. 1.

[0114] The computer 30 is capable of carrying out post-processing on the data acquired by the imager 28 to obtain information concerning the state of health of the electrochemical element 24. In this case, the interaction between the computer 30 and a computer program product 50 allows the implementation of steps of the characterization method, certain steps of which are implemented by computer.

[0115] An example of a calculator 30 is illustrated in Figure 3.

[0116] The computer 30 is here a desktop computer. Alternatively, the computer 30 is a rack-mounted computer, a laptop, a tablet, a personal digital assistant (PDA), or a smartphone.

[0117] In specific embodiments, the computer is adapted to operate in real time and / or is in an embedded system, in particular in a vehicle such as an airplane or a car.

[0118] In the case of Figure 3, the computer 30 comprises a calculation unit 52, a user interface 54 and a communication device 56.

[0119] The computing unit 52 is an electronic circuit designed to manipulate and / or transform data represented by electronic or physical quantities in registers of the calculator 30 and / or memories into other similar data corresponding to physical data in the register memories or other types of display devices, transmission devices or storage devices. As specific examples, the computing unit 52 includes a single-core or multi-core processor (such as a central processing unit (CPU), a graphics processing unit (GPU), a microcontroller and a digital signal processor (DSP)), a programmable logic circuit (such as an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a programmable logic device (PLD) and programmable logic arrays (PLA)), a state machine, a logic gate and discrete hardware components.

[0120] The computing unit 52 comprises a data processing unit 58 adapted to process data, in particular by performing calculations, memories 60 adapted to store data and a reader 62 adapted to read a computer-readable medium.

[0121] The user interface 54 includes an input device 64 and an output device 66.

[0122] The input device 64 is a device allowing the user to enter information or commands into the computer 30.

[0123] In Figure 3, the input device 64 is a keyboard. Alternatively, the input device 64 is a pointing device (such as a mouse, a touchpad, and a graphics tablet), a speech recognition device, an eye tracker, or a haptic (motion analysis) device.

[0124] The output device 66 is a graphical user interface, i.e., a display unit designed to provide information to the user of the computer 30.

[0125] In Figure 3, the output device 66 is a display screen for visually presenting the output. In other embodiments, the output device 66 is a printer, an augmented and / or virtual display unit, a speaker or other sound generating device for presenting the output as sound, a vibration and / or odor producing unit, or a unit adapted to produce an electrical signal.

[0126] In a specific embodiment, the input device 64 and the output device 66 are the same component forming human-machine interfaces, such as an interactive display.

[0127] The communication device 56 enables one-way or two-way communication between the components of the computer 30. For example, the communication device 56 is a bus communication system or an input / output interface.

[0128] The presence of the communication device 56 allows that, in certain embodiments, the components of the computer 30 are distant from each other. The computer program product 50 comprises a computer-readable medium 68.

[0129] The computer-readable medium 68 is a tangible device readable by the reader 62 of the computing unit 52.

[0130] Notably, the computer-readable medium 68 is not a transient signal per se, such as radio waves or other freely propagating electromagnetic waves, such as light pulses or electronic signals.

[0131] Such a computer-readable storage medium 68 is, for example, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any combination thereof.

[0132] As a non-exhaustive list of more specific examples, the computer-readable storage medium 68 is a mechanically encoded device, such as punched cards or raised structures in a groove, a floppy disk, a hard disk drive, a read-only memory (ROM), a random access memory (RAM), an erasable programmable read-only memory (EROM), an electrically erasable readable memory (EEPROM), a magneto-optical disk, a static random access memory (SRAM), a compact disk (CD-ROM), a digital versatile disk (DVD), a USB flash drive, a floppy disk, a flash memory, a solid-state disk (SSD), or a PC card such as a PCMCIA memory card.

[0133] A computer program is stored on the computer-readable storage medium 68. The computer program comprises one or more sequences of stored program instructions.

[0134] Such program instructions, when executed by the data processing unit 52, cause steps of the method to be executed.

[0135] For example, the form of the program instructions is a source code form, a computer-executable form, or any intermediate form between source code and a computer-executable form, such as the form resulting from the conversion of the source code via an interpreter, assembler, compiler, linker, or locator. Alternatively, the program instructions are microcode, firmware instructions, state definition data, integrated circuit configuration data (e.g., VHDL), or object code.

[0136] The program instructions are written in any combination of one or more languages, for example an object-oriented programming language (FORTRAN, C++, JAVA, HTML), a procedural programming language (e.g. C language). Alternatively, the program instructions are downloaded from an external source via a network, as is the case, in particular, for applications. In this case, the computer program product comprises a computer-readable data carrier on which the program instructions are stored or a data carrier signal on which the program instructions are encoded.

[0137] In each case, the computer program product 50 comprises instructions that can be loaded into the data processing unit 52 and adapted to cause the execution of the method when executed by the data processing unit 52. Depending on the embodiments, the execution is fully or partially carried out either on the computer 30, i.e. a single computer, or in a system distributed between several computers (in particular via the use of cloud computing).

[0138] In operation, according to the example in Figure 1, the characterization method comprises an acquisition step E10, an analysis step E12 and a calculation step E16.

[0139] During the acquisition step E10, the imager 28 acquires data relating to the electrochemical element by implementing an electronic paramagnetic resonance technique.

[0140] As explained earlier, the data comprises a spectrum or an image.

[0141] Electron paramagnetic resonance is often referred to as EPR. Therefore, for simplicity, the data acquired by the imager 28 are referred to as EPR data in the remainder of the description.

[0142] The EPR technique is a local characterization technique allowing, in a material, to obtain information concerning the nature of the species comprising unpaired or single electrons, as well as information on their concentrations, their reactivity, their environment, their dynamics and the magnetic interactions between these species and with other magnetic species.

[0143] The principle of the EPR technique is based on the Zeeman effect: subjected to the action of an external magnetic field H, the energy levels of a spin S separate into (2S + 1) electronic subspaces (lifting of the degeneracy), each assigned a quantum number m s (m = -S, -S+1 , - S+2, ..., S). This separation of levels is all the greater as H is intense.

[0144] Thus, for the case of a single unpaired electron (for which S = 1 / 2), the presence of the external magnetic field gives rise to (2S + 1 ) = 2 electronic subspaces, corresponding to m s = -1 / 2 and m s = +1 / 2. The magnetic energy E M associated with each of these states is given by the following formula:

[0145] E M = RN S * g * I B * H Where:

[0146] • g is the Landé factor,

[0147] • |i B is the Bohr magneton, and

[0148] • H is the amplitude of the magnetic field.

[0149] Under the action of a second magnetic field (hyperfrequency field or microwave) perpendicular to the first and of much lower amplitude, having a frequency v, a photon of energy hv can be absorbed (or emitted) if the energy separation between the 2 levels concerned, i.e. g * |i B * H, is equal to hv. It is at this particular value of H that a resonance phenomenon occurs.

[0150] Thus, the acquisition step E10 comprises the application of a static magnetic field by the magnetic field generator 34.

[0151] Simultaneously, the excitation unit 36 ​​applies microwave excitation to the cavity 32.

[0152] The cavity 32 then becomes resonant when the cavity 32 absorbs most of the microwave energy emitted by the excitation unit 36.

[0153] The detector 38 then detects the absorption by the electrochemical element 24 of the microwave excitation.

[0154] To give an order of magnitude, the detector 38 is capable of detecting in a field of vision, for example of the order of 2 cm by 7 mm.

[0155] During the analysis step E12, the computer 30 analyzes the acquired RPE data to detect the presence or absence of an abnormal lithium structure in the electrochemical element 24.

[0156] By definition, an abnormal structure is a lithium aggregate that appears irreversibly during cycling.

[0157] The abnormal structure detected is, for example, a lithium aggregate.

[0158] An aggregate is a set of lithium atoms that have a certain cohesion between them and form a compact whole.

[0159] Alternatively or additionally, the abnormal structure detected is, for example, a lithium dendrite.

[0160] Lithium dendrites are metallic microstructures that form in the electrochemical system during the charging process. For example, lithium dendrites form when additional lithium ions accumulate on the anode surface and cannot be absorbed into the anode in time.

[0161] To perform such detection, the computer 30 searches, for example, for specific line shapes in a spectrum. These shapes correspond to abnormal structures. Alternatively or in addition, the computer 30 can search for specific patterns in a spectral image, i.e. an image representing the spatial variation of a spectrum.

[0162] Such an analysis can be carried out, in particular, using a mathematical calculation tool such as Matlab®.

[0163] By way of illustration, it is assumed in the remainder of the description that the computer 30 has detected the presence of an abnormal structure.

[0164] During the calculation step E16, the computer 30 calculates a parameter linked to the state of health of the electrochemical element 12 as a function of the detected presence or not of an abnormal structure.

[0165] In a very simple particular case, the calculated parameter is a binary parameter, a first value indicating the presence of an abnormal structure and a second value indicating the absence of an abnormal structure.

[0166] In another example, the calculated parameter is the number of abnormal structures detected.

[0167] In a more elaborate case, the parameter depends on the number of abnormal structures detected.

[0168] For example, the calculated parameter is a first value if the number of abnormal structures detected is strictly less than a first threshold, a second value if the number of abnormal structures detected is between the first threshold and a second threshold and the third value if the number of abnormal structures detected is strictly greater than the second threshold. By choosing the thresholds, for example using prior tests of the electrochemical element 24, such a calculated parameter makes it possible to obtain three types of state for the electrochemical element 24: a correct operating state, a degraded operating state and a severely degraded operating state.

[0169] The characterization process thus makes it possible to observe the appearance of lithium aggregates or dendrites within electrochemical elements 24 of all-solid or hybrid batteries.

[0170] This observation can be made in operando, that is to say while the electrochemical element 24 is in operation.

[0171] In particular, the characterization method does not require disassembly. Indeed, internal pressures between 1 bar and 30 bars are exerted during the operation of the electrochemical element 24 and returning to atmospheric pressure can create significant changes in the molecular structure of the materials of the electrochemical element 24. Such changes are likely to modify the presence of abnormal structures.

[0172] In addition, the characterization process has very good spatial resolution in the order of micrometers.

[0173] Having such a characterization tool allows us to consider multiple applications.

[0174] For example, it may be possible to consider optimizing the operating conditions of an electrochemical element 24.

[0175] In fact, the growth of lithium dendrites is influenced by several parameters, including current density, temperature, electrolyte, and electrolyte convection. These factors determine the dynamics of the electrolyte.

[0176] By adjusting the operating parameters of the electrochemical element 24 during its use, it is possible to determine operating parameters limiting the appearance of dendrites.

[0177] Similarly, it is possible to use the characterization process to design and / or manufacture more efficient electrochemical elements by selecting electrochemical elements that limit the appearance of abnormal structures.

[0178] Among the electrochemical elements to be selected, many parameters can be varied, such as the nature of the materials used for the electrodes and the electrolyte, the shape of the electrodes or the electrolyte reservoir.

[0179] The characterization process will facilitate such selection work by allowing operational tests to be carried out.

[0180] Other embodiments of the characterization method are conceivable.

[0181] In particular, another embodiment of the characterization method is shown in the flowchart of Figure 4.

[0182] In this case, the characterization method comprises an acquisition step E100, an analysis step E102, a determination step E104 and a calculation step E106.

[0183] The acquisition steps E100 and analysis steps E102 of the characterization method of Figure 4 are respectively similar to the acquisition steps E10 and analysis steps E12 of the characterization method of Figure 1, so that the same remarks apply and are not repeated in the following.

[0184] During the determination step E104, the computer 30 determines at least one property of each abnormal structure detected.

[0185] Indeed, the characteristics of the signal obtained by the EPR data (shape, resonance magnetic field, amplitude) give indications on the local environment of the detected electron. In particular, there is a correlation between the shape, the magnetic field of appearance of the signal and the morphology of the metallic lithium deposits.

[0186] For example, the calculator 30 finds the position of each detected abnormal structure.

[0187] The position is, for example, expressed as the coordinates of the geometric center of the abnormal structure.

[0188] During the calculation step E106, as in the case of step E16 of the method according to FIG. 1, the calculator 30 calculates a parameter linked to the state of health of the electrochemical element 12 as a function of the detected presence or not of an abnormal structure but it also takes into account the determined property of each detected abnormal structure.

[0189] For example, a value could be determined depending on the number of abnormal structures and their nature (typically a very large dendrite corresponds to a poor state of health compared to a short dendrite).

[0190] Taking into account an additional element for the parameter linked to the state of health of the electrochemical element 12 makes it possible to improve the precision of the characterization process.

[0191] Another embodiment of the characterization method is shown in the flowchart of Figure 5.

[0192] In this case, the characterization method comprises an acquisition step E200, a measurement step E202, an analysis step E204 and a calculation step E206.

[0193] The acquisition step E200 of the characterization method of Figure 5 is similar to the acquisition step E10 of the characterization method of Figure 1, so the same remarks apply and are not repeated in the following.

[0194] During the measurement step E202, the characterization device 22 measures the temporal evolution of a physical quantity of the electrochemical element 24.

[0195] For example, the physical quantity is the pressure within the electrochemical element 24 and it is measured using a pressure probe, in particular an in-situ probe positioned in the enclosure of the electrochemical element 24.

[0196] Such a pressure probe is capable of communicating with the computer 30 by wireless communication.

[0197] The acquired data then also include the temporal evolution of the physical quantity.

[0198] During the analysis step E204, the computer 30 analyzes the RPE data and the measured time evolution to detect the presence or absence of an abnormal lithium structure in the electrochemical element 24. Indeed, the evolution of the pressure is the sign of heat dissipation and the heat can be the manifestation of the presence of an abnormal structure.

[0199] Calculation step E206 of the characterization method of Figure 5 is similar to calculation step E14 of the characterization method of Figure 1, so the same remarks apply and are not repeated in the following.

[0200] Taking into account an additional element for the analysis allows for better detection of abnormal structures and therefore improves the precision of the characterization process.

[0201] Of course, it is possible to combine the preceding embodiments when technically possible. In particular, a method comprising the additional steps of the embodiments according to Figures 4 and 5 makes it possible to combine the advantages of these two embodiments to obtain even better precision.

[0202] These advantages are added to the fact that, in all embodiments, the method for characterizing the state of health of an electrochemical element of an all-solid or hybrid battery can be implemented under real operating conditions.

[0203] The characterization process that has just been described makes it possible to characterize in operando the state of health of an electrochemical element of an all-solid or hybrid battery.

[0204] Furthermore, although the method has been described with reference to a lithium battery, the method is usable for any element having paramagnetic properties, i.e. the method can be used generally for a battery with a paramagnetic element. In particular, the paramagnetic element could be copper or sodium.

Claims

CLAIMS 1. Method for characterizing the state of health of at least one electrochemical element (24) of a battery (20), the battery (20) being a battery with a paramagnetic element with an electrolyte in solid or gelled state, the method comprising a step of: - acquisition of data relating to the at least one electrochemical element (24), the data comprising a spectrum obtained by implementing an electronic paramagnetic resonance technique or an image obtained by implementing an electronic paramagnetic resonance technique, and - analysis of the acquired data to detect the presence or absence of an abnormal structure of the paramagnetic element in the at least one electrochemical element (24).

2. Characterization method according to claim 1, wherein the abnormal structure is an aggregate or a dendrite.

3. Characterization method according to claim 1 or 2, wherein the method is implemented during operation of the at least one electrochemical element (24).

4. Characterization method according to any one of claims 1 to 3, in which the acquired data comprises at least one spectrum, the analysis step comprising the recognition of a specific line shape in said at least one spectrum.

5. Characterization method according to any one of claims 1 to 4, in which the specific data comprises at least one image, the analysis step comprising the search for specific patterns in the at least one image.

6. Characterization method according to any one of claims 1 to 5, in which the method further comprises a step of calculating a parameter of the state of health of the at least one electrochemical element (24) as a function of the presence or absence of an abnormal structure.

7. Characterization method according to any one of claims 1 to 6, wherein, when at least one abnormal structure is detected during the analysis step, the method further comprises a step of determining at least one property of each abnormal structure.

8. The characterization method of claim 7, wherein the at least one property of each abnormal structure is the location of the abnormal structure.

9. Characterization method according to claim 7 or 8 in its dependence on claim 6, in which the parameter of the state of health of the at least one electrochemical element (24) calculated during the calculation step is also a function of each property determined for each abnormal structure.

10. Characterization method according to any one of claims 1 to 9, in which the method further comprises a step of measuring the temporal evolution of at least one physical quantity of the at least one electrochemical element (24), the acquired data also comprising the temporal evolution measured in the measurement step.

11. Characterization method according to claim 10, in which the physical quantity is the pressure within the electrochemical element (24).

12. Calculator (30) adapted to characterize the state of health of at least one electrochemical element (24) of a battery (20), the battery (20) being a battery with a paramagnetic element with an electrolyte in solid or gel state, the calculator (30) being adapted to: - receiving data relating to the at least one electrochemical element (24), the data comprising a spectrum obtained by implementing an electronic paramagnetic resonance technique or an image obtained by implementing an electronic paramagnetic resonance technique, and - analyzing the acquired data to detect the presence or absence of an abnormal structure of the paramagnetic element in the at least one electrochemical element (24).

13. Device (22) for characterizing the state of health of at least one electrochemical element (24) of a battery (20), the battery (20) being a battery with a paramagnetic element with an electrolyte in solid or gelled state, the characterization device (22) comprising: - an imager (28) capable of acquiring data relating to the at least one electrochemical element (24) by an electronic paramagnetic resonance technique, the data comprising a spectrum obtained by implementing an electronic paramagnetic resonance technique or an image obtained by implementing an electronic paramagnetic resonance technique, and - a computer (30) capable of analyzing the data acquired by the imager (28) to detect the presence or absence of an abnormal structure of the paramagnetic element in the at least one electrochemical element (24).

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