Estimating SOH and SOC of electrochemical components

Abstract

The present invention relates to a method for estimating the state of health (SOH) of an electrochemical element, comprising: starting a charge or discharge operation of the electrochemical element; measuring a value representing the deformation of the electrochemical element when the charge or discharge operation is performed, the measured deformation value forming a deformation image signal as a function of the amount of electricity passing through the electrochemical element over time; comparing the deformation image signal and a reference image signal, and representing an estimated value of the aging of the electrochemical element by one or more difference values ​​obtained by the comparison.

Description

Technical Field

[0001] The technical field of the present invention relates to methods, systems and programs for estimating the state of health (SOH) and state of charge (SOC) of electrochemical components whose state of charge cannot be continuously and accurately estimated by voltage measurements. Background Art

[0002] An electrochemical generator, or battery, or cell or battery is a device for generating electrical energy, in which chemical energy is converted into electrical energy. The chemical energy consists of electrochemically active compounds placed inside the cell. The electrical energy is generated by electrochemical reactions during the discharge of the cell. The electrodes arranged in the container are electrically connected to current output terminals, which ensure electrical continuity between the electrodes and the electrical load associated with the cell.

[0003] Typically, a battery comprises a plurality of elements that can be grouped together within the same housing. The battery can be divided into a plurality of modules, each module consisting of a plurality of elements connected in series and / or in parallel with one another. The battery is intended to provide electrical energy for external applications. A charging circuit is usually provided to which the battery can be connected in order to recharge the elements. A management system comprising measuring sensors and electronic control circuits, more or less advanced depending on the application, can be associated with the battery.

[0004] There are known standards for calculating the state of health (or SOH, corresponding acronym for State of Health) of electrochemical components and, by extension, batteries. SOH represents the degree of aging of a component between an initial state and a state at a given point in time. The SOH of a component can be calculated by the ratio of the impedance of the component at a given point in time to the impedance of the component in the initial state, or by an estimate of the capacity loss compared to the capacity of the component in the initial state. However, these calculation standards do not allow online characterization of the causes of component aging; in particular, the capacity loss of the negative electrode of lithium electrochemical components and the growth of the passivation layer (SEI, acronym for “solid-electrolyte interface”). For example, methods that provide means for estimating SOH impose full charging or discharging in a restricted regime to ensure a minimum accuracy. This has the consequence of forcing maintenance cycles, and the estimated value of the capacity does not provide the causes of aging.

[0005] There are also known standards for calculating the state of charge (or SOC, the corresponding acronym for State Of Charge) of components, and by extension, batteries. SOC is the amount of energy available in a battery compared to the energy of a fully charged battery. Usually, it is expressed as a percentage and reflects the remaining portion of energy available to the user. Currently, most SOC calculation standards are based on continuous measurement of voltage-current-temperature data. For example, the following two calculation modes that alternate in sequence can be used. The main mode is the coulometric method, that is, the state of charge depends directly on the count of ampere hours and the battery capacity. However, this mode is very sensitive to current measurement errors and estimated values ​​of capacity. If this mode is used alone, voltage offsets may occur. The second mode is usually based on voltage measurement and uses a state of charge table based on the open circuit voltage. However, this second mode is sensitive to the estimation of resistance, and an error in the resistance estimation will lead to an error in the estimation of the open circuit voltage (or OCV, the corresponding acronym for Open Circuit Voltage), and thus to an error in the SOC estimation.

[0006] There are also known elements in which this technology is characterized by a curve of OCV as a function of SOC which shows a slight slope because it has at least one region in which the variation of OCV as a function of SOC changes only slightly and / or can be non-univocal; it is not possible to correlate the voltage measurement with the state of charge. The curve of OCV as a function of SOC can be non-univocal, that is to say there are two points on the curve with the same ordinate but different abscissas. Document EP-A-2 269954 describes an example of such an element for which the variation of the no-load voltage as a function of the state of charge presents an area of ​​state of charge comprised between about 30% and about 90%, wherein the no-load voltage as a function of the average state of charge increases at least 10 times slower than at a state of charge comprised between 90% and 100%. Such an element is called a flat profile electrochemical element or more simply a flat profile element. Aging will cause a change in the relationship between OCV and SOC.

[0007] For such flat profile components, in the region where the curve of OCV as a function of SOC rises slowly, it is not possible to calibrate the SOC on voltage because the measurement uncertainty is too large. Therefore, the calculation of SOC is purely coulometric. This means that during voltage calibration, on the portion of the curve with sufficient slope, a poorly estimated capacity (e.g. due to component aging or even due to current measurement errors) can compensate for SOC deviations. It is known that the state of charge information provided is sufficiently accurate for a portion of the curve of OCV as a function of SOC corresponding to SOC around 90% to 100%, referred to as region 4. Even if the capacity can be estimated well, errors in the current measurement limit the number of cycles allowed in this region 4 without calibration. The current management method for managing such components consists in resetting the SOC information on the voltage on region 4 at a low current to minimize the uncertainty in the resistance value. For some applications, this may impose regular full charging, which is particularly unsuitable for hybrid applications such as railways or buses, where the restrictions are on a daily basis. It is also possible to reset in region 1 of the curve of OCV as a function of SOC; region 1 corresponds to SOC around 0% to 30%. However, this means obtaining knowledge of the error occurring in the SOC by coulometric method towards the end of discharge.

[0008] Therefore, there are currently no methods that are satisfactorily adapted to be able to estimate the state of health and state of charge of an electrochemical component, particularly when the electrochemical component is a flat profile component. Summary of the invention

[0009] Therefore, the present invention provides a method for estimating the state of health (SOH) of an electrochemical element. The method includes starting a charge or discharge operation of the electrochemical element. The method also includes measuring a value representing the deformation of the electrochemical element when the charge or discharge operation is implemented. The measured deformation value forms a deformation image signal as a function of the amount of electricity passing through the electrochemical element over time. The method also includes a comparison between the deformation image signal so formed and a reference image signal. One or more differences between the image signal and the reference image signal are obtained by comparison. The one or more differences represent an estimated value of the aging of the electrochemical element.

[0010] This method improves the estimation of the SOH of an electrochemical element, since it is independent of electrical measurements carried out directly or indirectly across the terminals of the electrochemical element. In fact, the estimation of the SOH is based on the determination of a signal that is an image of the deformation (mechanical) that the electrochemical element has undergone for a given amount of electricity that has passed through it during a charge or discharge operation. However, the morphology depends on the aging of the electrochemical element, that is, the measured values ​​characterize the aging of the element. Therefore, for the same given amount of electricity that has passed through the electrochemical element, the latter will have different deformations as a function of the aging of the electrochemical element. The aging of the electrochemical element can then be estimated by comparison with a reference image signal of the same electrochemical element.

[0011] Since the estimated value of SOH is determined from the deformation of the element and is independent of the specific electrical state applied to the element, the estimation of SOH can be performed without loss of accuracy regardless of the intensity of the current. In addition, the estimation of SOH according to the present invention requires only partial charging or discharging.

[0012] According to various embodiments, any combination of at least one of the following features may be implemented:

[0013] - the one or more differences obtained by the comparison represent an estimate of the growth of the passivation layer (SEI) Growth [N] and estimated value of negative capacity loss C neg_loss [N];

[0014] - the comparison also includes calculating an estimate of the actual capacity of the electrochemical element Capa by using the following formula batt [N]: Capa batt [N]=Capa batt [N-1]-(SEI Growth [N]+C neg_loss [N])

[0015] Among them, Capa batt [N-1] is the reference capacity value;

[0016] - Estimation of the growth of the passivation layer (SEI) Growth [N] is calculated by the following formula: SEI Growth [N] = Ah PeakMin [N-1]-Ah PeakMin [N], where

[0017] Ah PeakMin [N-1] is a first value representing the amount of electricity that has passed through the electrochemical element for the minimum value of the reference image signal, Ah PeakMin[N] is a second value representing the amount of electricity that has passed through the electrochemical element for the minimum value of the deformed image signal; and wherein the estimated value C of the negative capacity loss neg_loss [N] is calculated by the following formula: C neg_loss [N]=(Ah PeakMax [N-1]-Ah PeakMin [N-1])-(Ah PeakMax [N]-Ah PeakMin [N]), where Ah PeakMin [N-1] is the first value representing the amount of electricity that has passed through the electrochemical element for the minimum value of the reference image signal, Ah PeakMin [N] is the second value representing the amount of electricity that has passed through the electrochemical element for the minimum value of the reference image signal, Ah PeakMax [N-1] is a third value representing the amount of electricity that has passed through the electrochemical element for the maximum value of the reference image signal, Ah PeakMax [N] is a fourth value representing the amount of electricity that has passed through the electrochemical element for the maximum value of the deformed image signal;

[0018] - obtaining said reference image signal according to the same steps as the image signal calculated during said charging or discharging operation;

[0019] - the charging or discharging operation is the first charging or discharging operation of the electrochemical element;

[0020] - calculating the time derivative of the reference image signal;

[0021] And, wherein the comparing comprises: a comparison between the calculated derivative and a reference derivative.

[0022] The present invention also provides a method for estimating the state of charge (SOC) of an electrochemical element. The method includes starting a charging or discharging operation of the electrochemical element. The method also includes measuring a value representing the deformation of the electrochemical element when the charging or discharging operation is performed. The measured deformation value forms a deformation image signal as a function of the amount of electricity passing through the electrochemical element over time. A comparison is made between the deformation image signal and a reference image signal. One or more difference values ​​are obtained by the comparison. The difference value represents an estimated value of the aging of the electrochemical element. The method further includes: determining a first value SOC PeakMin and the second value SOC PeakMax The first value SOC is a value within a range of state of charge (SOC) values, and outside the range, the open circuit voltage (OCV) of the electrochemical element can be calibrated, wherein the first value SOC PeakMinrepresents the current SOC of the element for the minimum value of the deformed image signal, the second value SOC PeakMax Represents the current SOC of the element for the maximum value of the deformed image signal.

[0023] This method improves the estimation of the SOC of an electrochemical element, since it is based on the method for estimating SOH described previously; that is, the estimation of SOC is also independent of electrical measurements made directly or indirectly across the terminals of the electrochemical element. Therefore, like the estimation of SOH, the estimation of SOC can be made without loss of accuracy regardless of the intensity of the current; and the estimation of SOC can be made with partial charging or discharging of the element without imposing maintenance cycles. In addition, by using deformed measurements, the calculation of SOC is improved, since the range of SOC values ​​- beyond which open circuit voltage (OCV) calibration can be performed - is accurately determined by precise reference points. Elements with non-univocal OCV curves as a function of SOC accidentally reduce the uncertainty area. In turn, this allows accurate calculation of SOC outside of regions 1 and 4. Therefore, for elements with phase change materials, the functionality of the element is improved by overcoming the limitations of SOC calibration on voltage measurements outside the plateau region. Therefore, the method can allow long-term cycling in the plateau region without SOC offsets associated with current measurement errors. The method allows online recalibration of OCV, improving the accuracy of SOC during voltage measurement calibration.

[0024] According to various embodiments, any combination of at least one of the following features may be implemented:

[0025] - calibrating the open circuit voltage (OCV) of the electrochemical element;

[0026] - The calibration also includes an estimate of the growth of the passivation layer (SEI) Growth [N] and estimated value of negative capacity loss C neg_loss [N] to estimate the aging of the electrochemical element, and wherein the calibrating the open circuit voltage (OCV) of the electrochemical element includes calibrating the open circuit voltage (OCV) of the negative electrode of the electrochemical element by performing the following: calculating an estimated value SEI related to the growth of the passivation layer (SEI) Growth [N] and the estimated value of the negative capacity loss C neg_loss [N] corresponding active material loss (LAM) and / or lithium storage loss (LLI); correcting the open circuit voltage (OCV) of the negative electrode based on the calculation of the active material loss (LAM) and / or lithium storage loss (LLI);

[0027] - The range of determined values ​​includes the discharge operation for the electrochemical element: The value SOC is calculated by the following formulaPeakMin [N]: SOC PeakMin [N] = 100-100*(Ah PeakMin [N] / Capa batt [N]); SOC is calculated by the following formula PeakMax [N]: SOC PeakMax [N] = 100-100*(Ah PeakMax [N] / Capa batt [N]); and, wherein the range of determined values ​​includes a charging operation for the electrochemical element: the minimum value SOC of the range is calculated by the following formula: PeakMin [N]: SOC PeakMin [N] = 100*(Ah PeakMin [N] / Capa batt [N]); the maximum value SOC of the range is calculated by the following formula PeakMax [N]: SOC PeakMax [N] = 100*(Ah PeakMax [N] / Capa batt [N]); among them, Ah PeakMin [N] is the second value representing the amount of electricity that has passed through the electrochemical element for the minimum value of the reference image signal; Ah PeakMax [N] is a fourth value representing the amount of electricity that has passed through the electrochemical element for the maximum value of the deformed image signal; and Capa batt [N] is an estimate of the actual capacity of the electrochemical element;

[0028] - the estimated value of the aging of the electrochemical element including the estimated value of the growth of the passivation layer (SEI) SEI Growth [N] and estimated value of negative capacity loss C neg_loss [N], and wherein the comparison further comprises: calculating an estimated value Capa of the actual capacity of the electrochemical element using the following formula: batt [N]: Capa batt [N]=Capa batt [N-1]-(SEI Growth [N]+C neg_loss [N]); among them, Capa batt [N-1] is the reference capacity value; SEI Growth [N] is an estimate of the growth of the passivation layer (SEI); C neg_loss [N] is an estimate of the negative capacity loss.

[0029] The invention also provides a computer program comprising program code instructions for executing said method for estimating the state of health (SOH) and / or the state of charge (SOC) of an electrochemical component.

[0030] The present invention also provides a computer-readable information storage medium on which the computer program is saved and stored.

[0031] A system is also provided, comprising: a deformation sensor for detecting deformation of an electrochemical element; a management unit for managing the electrochemical element, the management unit communicating with the sensor and comprising a computing unit coupled to a memory storage unit, the memory storage unit storing the computer program and being capable of storing at least a value of a reference image signal, a value of a calculated image signal, and a compared value.

[0032] The system may further include a deformation sensor that is a strain gauge that transmits a voltage forming the deformation image signal as a function of the amount of charge passing through the electrochemical element over time.

[0033] Also provided is an assembly comprising: the system and a battery comprising at least one electrochemical element coupled to the deformation sensor.

[0034] The assembly may further be such that the included electrochemical element is of a type having a state of charge (SOC) curve including a flat region, wherein the relationship between the state of charge and / or the open circuit voltage (OCV) in the flat region is non-bijective. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Embodiments of the invention will now be described by way of non-limiting examples of the invention and with reference to the accompanying drawings, in which:

[0036] Figure 1 is an embodiment of an electrochemical element, wherein a curve of OCV as a function of SOC includes a flat region;

[0037] Figure 2 An embodiment of a deformed image signal for an element;

[0038] Figure 3 is an embodiment of an algorithm flow chart for calculating an estimate of SOH;

[0039] Figure 4 To show Figure 3 An embodiment of the steps in;

[0040] Figure 5 An embodiment of an algorithm flow chart for calibration of a table for calculating SOC from data associated with an estimate of SOH;

[0041] Figure 6 is an embodiment of the algorithm flow chart, which combines Figure 7 The use of the algorithm flowchart enhances the robustness of the SOC estimation through frequent recalibration;

[0042] Figure 7 is an embodiment of the algorithm flow chart, which combines Figure 6 The use of the algorithm flowchart enhances the robustness of the SOC estimation through frequent recalibration;

[0043] Figure 8 To show Figure 3 An embodiment of the steps in;

[0044] Fig. 9 For Figure 8 An embodiment of calculating a value of a deformed image signal to estimate SOH;

[0045] Fig.10 For Figure 8 An embodiment of calculating a value of a deformed image signal to estimate SOC;

[0046] Fig.11 To represent the range of SOC value Figure 8 Embodiments of the determined graph of the deformed image signal, beyond the range of the SOC value can achieve open circuit calibration of the element;

[0047] Fig.12 An embodiment of recalibration of an OCV meter is shown;

[0048] Fig.13 An embodiment of recalibration of an OCV meter is shown;

[0049] Fig.14 An embodiment of recalibration of an OCV meter is shown;

[0050] Fig.15 An embodiment of recalibration of an OCV meter is shown;

[0051] Fig.16 An embodiment of recalibration of an OCV meter is shown;

[0052] Fig.17 An embodiment of a battery; and

[0053] Fig.18 An embodiment of a system for estimating SOH and / or SOC is provided. DETAILED DESCRIPTION

[0054] The present invention relates to the estimation of the state of health (SOH) and state of charge (SOC) of an electrochemical generator (also called, in technical terms, a battery, or an electrochemical element, or even an element or a battery). These terms denote a device for generating electricity by converting chemical energy into electrical energy and should be considered synonymous hereinafter.

[0055] The term "open circuit voltage" (or actually no-load voltage) is understood to mean the voltage measured across the terminals of an element when the element does not draw any current (English "open circuit voltage", and the corresponding French term "open circuit voltage"; according to the definition 482-03-32 of the standard "CEI60050-482:2004", "International Electrotechnical Vocabulary Part 482: Batteries and accumulators").

[0056] The term OCV curve as a function of SOC is understood to mean the voltage variation as a function of the state of charge, or more simply, the OCV curve as a function of SOC is a table relating OCV measurement points as a function of the SOC value.

[0057] The present invention is applicable to a specific type of electrochemical element, whose curve of OCV as a function of SOC includes a portion of the curve with a slight slope, and / or a portion of the curve with zero slope, and / or a non-univocal portion of the curve. This type of electrochemical element is also called a "flat profile electrochemical element" or more simply a "flat profile element"; therefore, the flat profile corresponds to a portion of the curve with a slight slope, and / or a portion of the curve with zero slope, and / or a non-univocal portion of the curve. More generally, a flat profile electrochemical element is an electrochemical element in which at least a portion of the variation of the OCV is included in the measurement error of a sensor used to measure and / or estimate the OCV, and / or a portion of the curve is not unambiguous.

[0058] Figure 1 is an illustrative embodiment of an OCV curve as a function of SOC comprising at least one flat profile. In this embodiment, the component is a lithium-ion component, one positive electrode of which comprises an electrochemically active material such as a lithiated phosphate or of the type described in document EP-A-2 269 954. Figure 1 In the embodiment shown, the curve can be divided into four regions. Measurement accuracy requires that regions 2 and 3 be merged and formed into a single plateau or flat area (region 23). The OCV curve as a function of SOC for region 23 can be non-univocal, that is, there are two points on the curve with the same ordinate (same OCV value) but different abscissas (at least two different SOC values). Region 1 also has a plateau, which greatly reduces the slope area where the voltage can be calibrated. The plateau of region 1 is contained in Figure 1 Further, this region 1 may be most affected by component aging. Region 4 is a region containing a sufficiently steep slope to enable accurate measurement of state of charge information.

[0059] We will now discuss in more detail Figure 1There are three main regions shown in . Region 1: It corresponds to voltages less than or equal to Vmax region 1. The value Vmax region 1 corresponds to a state of charge equal to MinSOC region 2. Vmax region 1 is typically located between 3 and 3.30 V, typically 3.30 V. MinSOC region 2 is typically located in the range of 15% to 30%, typically 30%. In region 1, the voltage varies almost proportionally to the state of charge; that is, a given voltage of the component corresponds to a given state of charge. Region 1 is further subdivided into: a first state of charge region, contained between 0 and less than 10%, in which the voltage of the component varies by more than 300 mV, and a second state of charge region, contained between typically 10% and typically 30%, in which the voltage as a function of the state of charge varies more slowly, for example, an increase of about 100 mV for a state of charge of 20%. This second charge region is contained in Figure 1 The curved part of the ellipse.

[0060] Region 23: It corresponds to a voltage greater than Vmax region 1 and less than Vmin region 4. Vmin region 4 is typically located between 3.35 and 3.45V, typically 3.40V. The value Vmin region 4 corresponds to a state of charge equal to MaxSOC region 3. MaxSOC region 3 is typically located in the range of 80% to 95%, typically 90%. Region 23 typically corresponds to a voltage region comprised between 3.30V and 3.40V, which corresponds to a state of charge comprised between typically 20% and typically 90%. It can be noted that the voltage variation of the element is almost zero for a state of charge comprised between 30% and 60% and for a state of charge comprised between 65% and 90%. In region 23, the voltage variation of the element is very small, typically about 100mV for a state of charge comprised between about 30% and about 90%. This leads to a high degree of inaccuracy in the state of charge in region 23, since a given voltage value may correspond to a state of charge comprised in a wide range of 30%-90%. The zone 23 is subdivided into two sub-zones; a first sub-zone: zone 2 from MinSOC zone 2 to MaxSOC zone 2, that is, from 22% to 60%; and a second sub-zone: zone 3 from MinSOC zone 3 to MaxSOC zone 3, that is, from 65% to 90%. Zone 2 and zone 3 are combined together towards a state of charge comprised between 60% and 65%.

[0061] Region 4: It corresponds to a voltage greater than or equal to Vmin region 4. The value Vmin region 4 corresponds to a state of charge equal to MaxSOC region 3. Vmin region 4 corresponds to a state of charge of about 90%. In this region, the voltage varies proportionally to the state of charge. Its variation is about at least 300 mV. A given voltage of the element corresponds to a given state of charge.

[0062] exist Figure 1 Only one embodiment of a flat profile element is shown, in this sense Figure 1 The embodiments shown in are non-limiting. In general, a flat profile element is an electrochemical element whose positive active material has a charge profile in which the voltage variation as a function of the state of charge is between a state of charge greater than a MinSOC region 2 corresponding to a predetermined voltage Vmax region 1 and a state of charge less than a MaxSOC region 3 corresponding to a voltage Vmin region 4. The value of the open circuit voltage OCV varies between the Vmax region 1 and the Vmax region 2, and this variation is included in the measurement error of the voltage sensor; for example, the accuracy of the sensor is not sufficient to measure the variation of the OCV in region 23.

[0063] Examples of estimating the state of health (SOH) of an electrochemical component are discussed below.

[0064] In a first step, a charging operation or a discharging operation of the electrochemical element is started. The started charging or discharging operation is performed until data is obtained that can generate an estimate of the SOH. During the charging or discharging operation, one or more estimates of the SOH can be generated.

[0065] During the charging or discharging operation, a measurement of a value representing the deformation of the electrochemical element is performed (S300). In other words, the measurement of the value of the deformation of the electrochemical element is performed. The term "deformation of the electrochemical element" is understood to mean a change in the relative size of the electrochemical element. The deformation of the electrochemical element occurring during the electrochemical cycle is a known physical phenomenon; for example, the deformation of lithium-ion elements.

[0066] The values ​​of the measured deformation form a deformation image signal as a function of the amount of electricity that has passed through the electrochemical element over time. In fact, the deformation is measured during a charging operation or, in fact, a discharging operation, which is carried out over a given period of time. Thus, since the beginning of the operation, as the charging or discharging operation progresses, each value representing the relative dimensional change of the element is measured as a function of the amount of electricity that has passed through the element. Alternatively, each value can be measured as a function of the amount of electricity that has passed through the element from a first point in time other than the beginning (start-up) of the charging or discharging operation.

[0067] The measurement of the deformation value of the electrochemical element can be performed using any sensor capable of detecting and generating a value representative of the deformation.

[0068] In an embodiment, the sensor may be an extensometer such as a resistance wire extensometer (also called a strain gauge), which converts the deformation value of the electrochemical element into a voltage value. A resistance wire extensometer can be used to measure small deformation values.

[0069] exist Figure 3In the illustrated embodiment, in step S300, a deformation image signal is obtained as a function of the amount of electricity passing through the electrochemical element over time during the discharge operation of the electrochemical element. In this embodiment, the measured deformation value is converted into a voltage value as a function of time. At the same time as the deformation value is measured, the amount of electricity passing through the electrochemical element as a function of time is also measured. From these two measurements, namely the deformation value over time and the amount of electricity passing through the element, the deformation image signal is obtained (or calculated).

[0070] Figure 2 200 is a graph showing a deformation image signal 200 of a component during a discharge operation. In this embodiment, the deformation image signal is a deformation image signal of an electrochemical component having a cylindrical shape, and it should be understood that the method according to the present invention can be applied regardless of the form of the electrochemical component. The measured deformation value is converted into a voltage value. The deformation image signal 200 evolves as a function of the amount of electricity discharged at C through the component. The amount of electricity is usually expressed in ampere hours (Ah).

[0071] After obtaining the deformation image signal, the deformation image signal is compared with the reference image signal. The comparison can obtain one or more differences of the estimated value characterizing the aging of the electrochemical element. The comparison between the two signals can utilize, but is not limited to, a qualitative comparison method of the two signals, a calculation method between the two signal values. The one or more differences obtained - for example, the behavior of the curve within a range of values ​​on the horizontal axis, or even a value obtained by comparing the values ​​of the two curves - represent structural modifications of the composition (electrodes, separators, etc.) of the electrochemical element for a given amount of electricity that has passed through the electrochemical element. These structural modifications are related to the past use of the element and therefore indicate the health state of the electrochemical element. In other words, the evolution of the deformation between two identical charging or discharging operations is an indicator of the aging of the electrochemical element, or even characterizes the aging of the electrochemical element.

[0072] The comparison between the deformed image signal (formed in step S300) and the reference image signal is performed between two image signals of the same electrochemical element through which at most the same amount of electricity has passed; the term "same" may mean substantially the same, for example, the difference is preferably between ±5% and up to ±20%. The amount of electricity that has passed through the element to obtain the deformed image signal and the reference image signal makes it possible to obtain local minima and maxima of each of the two image signals, with full charge and full discharge not constituting each of the local minima and maxima.

[0073] In an embodiment, similar initial conditions for forming the two image signals to be compared can be set. For example, the two image signals can be obtained from the same charge reference point, which enables comparison of the deformation image signal and the reference image signal that have been obtained for the electrochemical element under similar electrical conditions, significantly improving the accuracy of the estimated value of the aging of the electrochemical element.

[0074] In an embodiment, the reference image signal is obtained in the same way as the method used to obtain the deformed image signal. As previously mentioned, the same electrochemical element has the same current of maximum amount passing through it to form the two signals. This amount of electricity may have passed through the element with the same C / n mechanism, or indeed even with two respective mechanisms. If the deformed image signal is obtained for the discharge operation, the reference signal will also be obtained for the discharge operation, and vice versa.

[0075] By comparing the obtained one or more differences it is possible to obtain an image of the evolution of the structural modification of the composition of the element between two operations of the same type (whether consecutive or not). It should be understood that the difference measured between two consecutive operations can provide the ability to detect severe changes in the element, such as premature or abnormal aging of the element.

[0076] In an embodiment, a reference image signal is obtained for the first charge or discharge operation or one of the first charge or discharge operations of the electrochemical element. "One of the first operations" can be a charge or discharge operation relative to the initial state of the electrochemical element. The initial state can be the initial state of a new element, or the initial state of an aged element (i.e., used), or the initial state of a second life element (i.e., for a new purpose). In all cases, the initial state is the placement of the element in use. Therefore, the reference image signal can be obtained in the case of the first use or the first use of the electrochemical element.

[0077] In an embodiment, the comparison between the image signal and the reference image signal can be implemented by using the time derivative of each of the two signals. If necessary, this makes it possible to facilitate the identification of specific values, such as minimum and maximum values ​​of each of the two signals. This also makes it possible to facilitate the calculation of the comparison. Figure 2 This is illustrated where a time derivative 220 of the signal 200 is displayed. The oscillations experienced by the image signal (eg, for the left and right portions of the image signal 200) are smoothed, facilitating the calculation of the comparison.

[0078] exist Figure 3 In the illustrated embodiment, in step S310 , the time derivative is calculated after acquiring the image signal.

[0079] For example, an estimate of the aging of a component from one or more differences may include an estimate of the growth of a passivation layer (SEI) SEIGrowth Calculation of [N] and estimation of negative capacity loss C neg_loss [N] calculation. SEI growth and negative capacity loss are the two main physicochemical mechanisms that have the greatest impact on the aging of electrochemical devices. Their estimation from device deformation measurements provides a means for accurately estimating the SOH of electrochemical devices.

[0080] In the embodiment, the estimated value C of the negative capacity loss is neg_loss [N] By comparing with the reference capacity of the component Capa batt [N-1] to estimate SOH. As mentioned above, the reference capacity Capa of the electrochemical element batt [N-1] may be its capacity in the initial state, or indeed may even be its capacity after the first charge or discharge operation relative to the initial state. In some embodiments, an estimate of the capacity of an electrochemical element Capa may be calculated using the formula batt [N]:

[0081] Capa batt [N]=Capa batt [N-1]-(SEI Growth [N]+C neg_loss [N])(Equation 1)

[0082] Among them, Capa batt [N-1] is the reference capacity value of the component. batt [N] is also called the actual capacity of a component because it estimates the amount of energy that an aged component can store.

[0083] refer to Figure 3 In the steps S320 to S360 of FIG. 1 , an embodiment will now be discussed in which the SOH is obtained by calculating an estimated value of the actual capacity of the electrochemical element according to the formula (Equation 1). In this embodiment, the estimated value of the growth of the passivation layer (SEI) is performed. Growth Calculation of [N] and estimation of negative capacity loss C neg_loss Calculation of an estimated value of [N]. Furthermore, the comparison between the image signal and the reference image signal is performed using the time derivatives of these two signals.

[0084] Steps S320 to S330 illustrate an embodiment of the calculation of an estimate of the growth of the passivation layer (SEI), denoted as SEI Growth [N]. In step S320, a null value of the temporal derivative of the deformed image signal is identified. This null value allows the identification of a local minimum of the deformed image signal (S300). The identification of this null value of the derivative is achieved using any known mathematical method. This local minimum corresponds to a value denoted as Ah. PeakMinThe value of [N], which represents the amount of electricity that has passed through the electrochemical element. The smallest value corresponding to a fully charged or fully discharged electrochemical element is excluded. Ah PeakMin The scale of [N] is in units of charge, typically ampere hours (Ah). It should be understood that in embodiments where step S310 is not implemented, the local minimum is directly calculated from the image signal using any known method.

[0085] As long as no minimum value can be identified ( S322 ), step S320 is repeated. This may be the case, for example, if the duration of the charging or discharging operation performed is insufficient to obtain a minimum value, excluding complete charging and complete discharging of the electrochemical element.

[0086] At the same time as, or even before, or even after the implementation of steps S320-S322, a null value of the time derivative of the image signal reference is identified. This null value can identify a local minimum of the reference image signal. The identification of the null value of the time derivative of the reference image signal can be calculated by using the same method as for the deformed image signal. Minimum values ​​corresponding to the electrochemical element when fully charged or fully discharged are also excluded. This local minimum corresponds to a value denoted as Ah PeakMin [N-1] value, which also represents the amount of electricity that has passed through the electrochemical element and has the same PeakMin [N] The same scale. It should be understood that in an embodiment where step S310 is not implemented, the local minimum value may be directly calculated based on the reference image signal by any known method.

[0087] Then, in step S330, SEI Growth [N] is calculated by the following formula (Equation 2):

[0088] SEI Growth [N] = Ah PeakMin [N-1]-Ah PeakMin [N](Equation 2)

[0089] Among them, Ah PeakMin [N-1] is the first value of the charge that has passed through the electrochemical element, representing the null value of the derivative of the reference image signal, and Ah PeakMin [N] is a second value representing the amount of electricity that has passed through the electrochemical element for the null value of the derivative of the deformed image signal calculated in step S310.

[0090] It should be understood that in the embodiment where step S310 is not implemented, Ah PeakMin [N-1] is the first value of the amount of electricity that has passed through the electrochemical element for the local minimum value of the reference image signal, and Ah PeakMin[N] is a second value representing the amount of electricity that has passed through the electrochemical element for the local minimum value of the deformation image signal calculated in step S300.

[0091] Steps S340 to S350 illustrate an embodiment of the calculation of an estimate of negative capacity loss, denoted as C neg_loss [N]. In step S340, a second null value of the time derivative of the deformed image signal is identified. This null value allows the identification of a local maximum of the deformed image signal (S300). It is calculated using any known mathematical method. This local maximum corresponds to a value denoted as Ah. PeakMax [N] value, which represents the amount of electricity that has passed through the electrochemical element; Ah PeakMax The scale of [N] is the unit of electric charge, usually ampere-hour (Ah).

[0092] As long as no maximum value can be identified, step S340 (S342) is repeated. This may be the case, for example, if the duration of the charging or discharging operation is not sufficient to obtain a maximum value, and a fully charged or fully discharged element does not constitute a local minimum or maximum.

[0093] At the same time as, or even before, or even after the implementation of steps S340-S342, a second null value of the time derivative of the reference image of the signal is identified. This second null value can make it possible to identify a local maximum of the image signal (S300). The maximum values ​​corresponding to fully charged or fully discharged electrochemical elements are also excluded. The identification of this derivative null value can be implemented by using the same method as for the deformed image signal or any other method. The point on the curve of the reference image signal that reaches this local maximum is denoted by Ah PeakMax [N-1]. Ah PeakMax [N-1] also represents the amount of electricity that has passed through the electrochemical element and has the same PeakMax [N] The same scale. It should be understood that in an embodiment where step S310 is not implemented, the local maximum value may be directly determined based on the reference image signal by using any known method.

[0094] Then, in step S350, C neg_loss [N] is calculated by the following formula (Equation 3):

[0095] C neg_loss [N]=(Ah PeakMax [N-1]-Ah PeakMin [N-1])-(Ah PeakMax [N]-Ah PeakMin [N])(Equation 3)

[0096] Among them, Ah PeakMin[N-1] is the first value of the charge that has passed through the electrochemical element for the first null value of the derivative of the reference image signal, and Ah PeakMin [N] is a second value representing the amount of electricity that has passed through the electrochemical element for the first null value of the derivative of the deformed image signal; Ah PeakMax [N-1] is a third value representing the amount of charge that has passed through the electrochemical element for the second null value of the derivative of the reference image signal, and Ah PeakMax [N] is a fourth value representing the amount of charge that has passed through the electrochemical element for a second null value of the derivative of the deformed image signal.

[0097] It should be understood that in the embodiment where step S310 is not implemented, Ah PeakMax [N-1] is a third value representing the amount of electricity that has passed through the electrochemical element for the local maximum value of the reference image signal, and Ah PeakMax [N] is a fourth value representing the amount of electricity that has passed through the electrochemical element for the local maximum value of the deformation image signal calculated in step S300.

[0098] exist Figure 3 In, C neg_loss [N] is calculated in SEI Growth [N] is calculated after that. It should be understood that it is also possible to neg_loss [N] Then even calculate SEI at the same time Growth [N].

[0099] Thus, local minima and local maxima of the image signal and the reference image signal are identified, respectively. In embodiments, they are identified by finding two null values ​​of the derivative for each image, while in other embodiments, they are identified directly from the two curves. C implemented by Equation 3 neg_loss The calculation of [N] only requires the identification of the minimum and maximum values ​​on each of the two curves of the two signals. Therefore, once the deformation image signal includes a minimum and a maximum value (that is, once two null values ​​of the derivative have been identified), the measurement of the value representing the deformation of the electrochemical element can be stopped, and the fully charged and fully discharged states of the element do not constitute local minimum or maximum values. In addition, since the amount of electricity that has passed through the electrochemical element to obtain the deformation image signal and the reference image signal is at most substantially the same, during the deformation measurement process, the minimum and maximum values ​​of the deformation image signal can be identified once this amount of electricity has actually passed through the element.

[0100] In step S360, the actual capacity of the electrochemical element is estimated by using equation 1. Thus, for two specific points on each of the two curves, a comparison between the time derivative of the image signal and the time derivative of the reference image signal is obtained. This selection of local minima and maxima of the derivative of the image signal and of the derivative of the reference image signal facilitates the calculation of the comparison performed only for these two specific points. In addition, this selection of specific points makes it possible to determine the SEI Growth [N] and C neg_loss [N], which are two main causes of aging of electrochemical components, especially for electrochemical components with a flat profile, and are therefore most suitable for characterizing the aging of the component. Therefore, the difference obtained by comparing the local minimum and maximum values ​​of the image signal and the reference image signal produces an estimate of the aging of the electrochemical component.

[0101] Capa batt [N-1] is the reference capacity value. This value can be the theoretical value of the component capacity. It can be the capacity value of the initial component, or even a capacity value close to the initial component. It can also be used with Capa batt [N] is calculated in the same way; for example, Capa is calculated from the reference image signal batt [N-1]. Capa batt [N] and Capa batt The scale of [N-1] is similar, with the scale being units of charge, usually ampere-hours (Ah).

[0102] In an embodiment, Capa batt [N] can be achieved by considering only SEI Growth [N] or alternatively only consider C neg_loss [N] is used to calculate. This makes it possible to obtain an approximate value for the capacity of the electrochemical element.

[0103] SEI can be estimated separately Growth [N] or C neg_loss The value of [N] is used to determine the degradation state of the electrochemical device.

[0104] Figure 4 Shows Figure 3 The curve 220 is similar to the reference curve 220. Figure 2 The curves discussed are the same and represent the deformation of the image signal of an aged electrochemical element having a cylindrical shape. Curve 400 represents the image signal of the same electrochemical element in an initial state or close to the initial state. Therefore, this curve 400 in this embodiment is a reference image signal compared with curve 220. The local minimum Ah of curve 400 is PeakMin Compared with [N-1], the local minimum value Ah of curve 220 PeakMinThe displacement to the left of [N] is an estimate of SEI growth. Double arrow 222 shows that curve 400 corresponds to (Ah PeakMax [N-1]-Ah PeakMin [N-1]), and the double arrow 224 shows that the curve 220 corresponds to (Ah PeakMax [N]-Ah PeakMin [N]) part. neg_loss The estimated value of [N] is represented by the overlapping portion of the two double arrows 222 and 224 .

[0105] Figure 8 Similar to Figure 4 , the difference is Figure 8 Two additional curves 700, 710 are included, each curve representing a deformed image signal obtained for two different aging states of the element. Curve 400 represents the reference image signal. In increasing order of aging of the electrochemical element, curve 220 represents the first deformed image signal, curve 700 represents the second deformed image signal, and curve 710 represents the third deformed image signal. It should be noted that as the element ages, the local minimum and local maximum values ​​generally shift to the left.

[0106] Fig. 9 To provide Figure 8 The value Ah for each curve shown in PeakMax [N] and Ah PeakMin [N] is a table. The first row corresponds to curve 400, the second row corresponds to curve 220, the third row corresponds to curve 700, and the last row corresponds to curve 710. Since the first row corresponds to the initial element, SEI and C neg_loss The value of is not applicable; the same is true for the last column of the table representing capacity loss.

[0107] The embodiments discussed so far regarding the estimation value of SOH can be combined with each other.

[0108] refer to Figure 5 , discussed below are embodiments of SOC estimation of an electrochemical element using the method for estimating SOH according to the present invention. In order to accurately determine the state of charge of the element, an estimated value of SOH is necessary, because each modification of the actual capacity of the element directly affects the estimated value of the state of charge. These embodiments can especially estimate SOC when the electrochemical element has a flat profile (or even a flat OCV).

[0109] Fig.12 To illustrate a screenshot of the relationship between OCV and SOC, it is expressed as SOC = f(OCV). This relationship is usually contained in a table that relates SOC values ​​to given OCV values. Fig.12As shown, this relationship can be non-bijective, that is, there is no unique single SOC value for a given OCV value. This is the case, for example, for SOC values ​​between 40% and 60%. Furthermore, this relationship changes as the component ages, as Fig.12 As shown. Also in this case, for a given OCV value, there may not be a unique single SOC value. In addition, it can be seen that the left and right parts of the curve are most affected by these modifications; however, these parts correspond to the reference Figure 1 Regions 1 and 4 are discussed, and they are the only regions where calibration can be performed for voltage measurements.

[0110] See back Figure 5 , steps S500 and S510 are similar to Figure 3 Steps S300 and S310, embodiments of which have been discussed previously. More generally, any of the previously discussed SOH estimation embodiments may be implemented.

[0111] Once the SOH is obtained, a range of SOC values ​​is determined, outside of which calibration of the open circuit voltage can be achieved. In other words, calibration of the open circuit voltage in the actual SOC value range cannot be achieved.

[0112] Step S530 is an embodiment of determining a range of SOC values ​​within which a specific point is determined. Thus, this range of SOC values ​​is limited by two specific values: the first value of the range, denoted as SOC PeakMin , and the second value of this range, denoted as SOC PeakMax Each of these two points can be defined as a reference or calibration point on an area of ​​the component where it is not possible to calibrate the SOC over the OCV; this is typically the case on a flat area of ​​a flat profile component.

[0113] SOC PeakMin is the value of SOC for the local minimum of the deformed image signal, and full charge and full discharge do not constitute a local minimum. It should be remembered that Ah PeakMin [N] represents the amount of electricity that has passed through the electrochemical element when the local minimum of the deformed image signal is reached. PeakMin is a first value of the SOC representing a null value of the derivative of the reference image signal, or, as the case may be, a first value of the SOC representing a minimum value of the deformed image signal.

[0114] SOC PeakMax is the SOC value of the local maximum for the deformed image signal, and full charge and full discharge do not constitute local minimums. It should be remembered that Ah PeakMax [N] represents the amount of electricity that has passed through the electrochemical element when the local maximum value of the deformed image signal is reached.PeakMax is a second value of the SOC representing a null value of the derivative of the reference image signal, or, as the case may be, a second value of the SOC representing a maximum value of the deformed image signal.

[0115] SOC PeakMin With SOC PeakMax Each represents the actual value of SOC, that is, these two values ​​are Capa batt Function of [N], Capa batt [N] is the actual capacity of the electrochemical element, not the theoretical capacity.

[0116] In the embodiment where the discharge operation has been initiated, the SOC is calculated by the following formula: PeakMin [N]:

[0117] SOC PeakMin [N] = 100-100*(Ah PeakMin [N] / Capa batt [N])(Equation 4),

[0118] And, the SOC value is calculated by the following formula PeakMax [N]:

[0119] SOC PeakMax [N] = 100-100*(Ah PeakMax [N] / Capa batt [N])(Equation 5),

[0120] In the embodiment where the charging operation has been started, the SOC is calculated by the following formula (Equation 6): PeakMin [N]:

[0121] SOC PeakMin [N] = 100*(Ah PeakMin [N] / Capa batt [N])(Equation 6),

[0122] And, SOC is calculated by the following formula (Equation 7): PeakMax [N]:

[0123] SOC PeakMax [N] = 100*(Ah PeakMax [N] / Capa batt [N])(Equation 7),

[0124] In equations 4, 5, 6, and 7, Capa batt [N] is an estimate of the capacity of the electrochemical element obtained according to the examples discussed for estimating SOH. Figure 3 Explained, value Ah PeakMin [N] and AhPeakMax [N] is defined and obtained.

[0125] Fig.11 for Figure 8 , 400, 220, 700, 710, which are now represented as functions of SOC 400a, 220a, 700a, 710a, respectively. Since this is an embodiment of component discharge, the representation of the image signal as a function of SOC is calculated using the following formula:

[0126] SOC[N]=100-100*(Ah[N] / Capa batt [N])(Equation 8)

[0127] If a charging operation is performed, the representation of the image signal as a function of SOC is calculated using the following formula:

[0128] SOC[N]=100*(Ah[N] / Capa batt [N])(Equation 9)

[0129] Equation 8 and Equation 9 are generalizations of Equation 4 / 5 and Equation 6 / 7, respectively. For any point Ah[N] of the image signal, at least one SOC value (SOC[N]) is associated.

[0130] Fig.11 Each representation of the image signal consists of two calibration points SOC PeakMin and SOC PeakMax , they define the range of current (or even actual) SOC values ​​within which SOC calibration on OCV cannot be performed. It should be remembered that Figure 8 and 11 In the embodiments, the electrochemical elements are identical flat profile elements. It should be noted that for each curve, the Figure 1 Compared to the discussed area 23, included in SOC PeakMin and SOC PeakMax Therefore, SOC PeakMin and SOC PeakMax These two points can significantly improve the calculation of the state of charge of electrochemical elements (especially for flat profile electrochemical elements) by reducing the uncertainty region by allowing calibration over a wider range of state of charge values. Figure 1 The uncertainty region discussed is comprised between approximately 30% and 90% SOC, and in this embodiment, the uncertainty region extends from approximately 50% to 85% SOC.

[0131] Fig.10 To provide Figure 8 The value Ah for each curve shown inPeakMax [N] and Ah PeakMin [N], and it gives Fig.11 The calibration points SOC shown in PeakMin and SOC PeakMax It should be noted that the first row corresponds to curves 400 and 400a, the second row corresponds to curves 220 and 220a, the third row corresponds to curves 700 and 700a, and the last row corresponds to curves 710 and 710a. The first row corresponds to the initial element, and the reference capacity Capa batt The value of [N-1] is associated with the initial element.

[0132] Calculate the calibration point SOC PeakMin and SOC PeakMax Afterwards, that is to say after determining the range of SOC values ​​bounded by these two points, a calibration of the open circuit voltage of the electrochemical element is carried out. This calibration is carried out as a function of an estimate of the ageing of the electrochemical element: it therefore uses the SOH of the electrochemical element and the actual capacity Capa batt [N] to calculate the calibration points.

[0133] exist Figure 5 In steps S540 and S550 of , an embodiment of the OCV calibration of the electrochemical element is proposed; the calibration is performed on the negative electrode of the electrochemical element. In fact, the OCV of the electrochemical element can be defined by the following formula:

[0134] OCV=OCV pos -OCV neg (Equation 10)

[0135] Among them, OCV pos is the OCV of the positive electrode of the component, OCV neg is the OCV of the negative electrode of the component. pos and / or OCV neg Ageing-related modifications act on the OCV of the component.

[0136] Fig.13 Two OCV graphs are shown, one for each electrode of the element. Curve 1200 corresponds to the OCV of the element neg , while curve 1210 corresponds to the OCV of the device pos .

[0137] Fig.14 shows the OCV of the component, which is Fig.12 The difference between the two curves 1200 and 1210.

[0138] In step S540 , calibration of the OCV of the negative electrode is performed.

[0139] In an embodiment, step S540 is implemented as a function of an estimated value of aging of the negative electrode of the electrochemical component ( S540 ).

[0140] The estimation of the aging of the negative electrode of the electrochemical device may include an estimation of the growth of the passivation layer (SEI) SEI Growth Calculation of [N] and estimation of negative capacity loss C neg_loss [N] can be calculated as shown in Figure 3 The calculation of these two estimated values ​​is performed as explained in steps S320 - S330 and S340 - S350 .

[0141] In the case where the electrochemical element is of lithium type, the active lithium loss (loss of lithium inventory, abbreviated as LLI) and the active material loss (loss of active material, abbreviated as LAM) are estimated from the SEI Growth [N] and C neg_loss [N] is calculated. Lithium-type electrochemical components are based on a technology where aging is usually caused primarily by negative capacity loss and growth of the SEI. LLI is primarily associated with the SEI, while LAM is primarily associated with C neg_loss The loss of active lithium (LLI) causes a horizontal shift in the potential curve of the electrode, and the loss of active material (LAM) causes a compression in the potential curve of the electrode of the element. Fig.15 It is shown in Fig.13 And the same curves 1200, 1210 are shown thereon. Initially, the OCV curve 1200 of the negative electrode of the element has a value contained between points 1302 and 1304. Under the action of LLI, the curve 1200 shifts to the left, point 1302 enters position 1308, and point 1304 enters position 1310. At the same time, under the action of LAM, point 1310 is pushed back to position 1306. The curve 1200 is finally shifted to the left and compressed.

[0142] Step S540 also includes correcting the open circuit voltage (OCV) of the negative electrode based on the calculation of loss of active material (LAM) and / or loss of lithium storage (LLI). The OCV table of the negative electrode is recalibrated using the analysis results of aging based on deformation measurement.

[0143] Subsequently, in step S550, the OCV of the element is corrected by using Equation 10, ie, based on the corrected OCV of the negative electrode of the element.

[0144] Fig.16 Similar to Fig.12 , the difference is Fig.16An additional curve is included which represents the OCV curve of the electrochemical element calculated in step S550. This calculated curve is merged with the experimental curve. It should be noted that the calculated OCV is also very close to the experimental OCV in regions 1 and 4, which significantly improves the accuracy of the SOC.

[0145] Thus, the SOC calculation of the electrochemical element is improved by recalibrating the OCV according to aging, enabling accurate calculations in both Region 4 and Region 1. Furthermore, as previously described, the uncertainty region has been reduced in such a way that the SOC over a portion of Region 23 can be recalibrated.

[0146] See back Figure 5 , each time it is determined that the SOH has been updated, calibration steps S530 to S550 may be performed (S520). When no update is detected, only steps S500 and S510 continue to be performed, for example, in order to calculate a new SOH.

[0147] The SOC determination method according to the invention can be combined with other known methods for determining SOC. This combination is advantageous, for example, when the electrochemical element is of a flat profile type or indeed even of a phase change type. It is in fact possible to use a known method for regions 1 and 4 and an SOC estimation method according to the invention for regions 2 and 3. This known method is discussed, for example, in document US2013229154 (A1).

[0148] exist Figure 6 In the embodiment shown, a voltage measurement of the element is performed (S600). When it is determined (S610) that the SOC belongs to region 1 or 4, a calibration of the SOC is performed on the measured OCV by using the relationship SOC=f(OCV). In the embodiment, for example, referring to Figure 1 In the discussed embodiment, SOC values ​​comprised between 0% and 20% are comprised in region 1, values ​​comprised between 20% and 90% are comprised in region 23, and values ​​comprised between 90% and 100% are comprised in region 4. It should be understood that these ranges may vary depending on the type of component and may be determined in any manner.

[0149] exist Figure 7 In the embodiment shown, steps S700 and S710 generate derivatives of the image signal. These steps are similar to Figure 3 Then, if the value Ah is determined PeakMin [N] (S720), then the SOC is calibrated for the SOC value corresponding to the local minimum value of the deformed image signal (S740). Step S720 is similar to step S320, and step S740 is similar to step S530. If the value Ah is not determined PeakMin[N] (S720), then in step S730 try to determine whether there is a value Ah PeakMax [N]. If this is not the case, a return to step S720 occurs. If in step S730 a value Ah is identified PeakMax [N], then the SOC is calibrated for the SOC value corresponding to the local maximum value of the deformed image signal (S750). Step S730 is similar to Figure 3 The two points Ah are similar to step S340, and step S750 is similar to step S530. PeakMin [N] and Ah PeakMax [N] is used to calibrate the SOC over at least a portion of region 23 .

[0150] Fig.18 An embodiment of a system is shown that provides a method for estimating the SOH and / or SOC of an electrochemical element. The system includes a management unit. The management unit includes a computing unit (CPU) 180 connected to a bus 182, and a memory storage unit 184 is connected to the bus 182. The memory storage unit can be a memory storage unit that can be used to store instructions and data required for the operation of a computer program. The memory storage unit can be, but is not limited to, a non-volatile memory storage unit, including: for example, semiconductor memory, such as an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a flash memory unit, a magnetic disk, a magneto-optical disk, a compact disk read-only memory (CD-ROM), a digital versatile disk read-only memory (DVD-ROM), CD. All these elements can be supplemented by or incorporated into an ASIC (acronym for “Application-specific integrated circuits”). The management unit can provide the deformation sensors 186 with means for communicating with the memory storage unit and the computing unit via the bus 182. These deformation sensors can be arranged on one or more electrochemical elements.

[0151] The computer program may include instructions executable by the management unit. The instructions include means for causing the system to perform the method according to the present invention. The program may be saved and stored on any data storage medium, including the memory storage unit of the management unit. For example, the program may be deployed in a digital electronic circuit, or in an IT device, firmware, software application, or a combination thereof. The program may be deployed in the form of a device (e.g., a product tangibly incorporated into a machine-readable storage device for execution by a programmable processor). The steps of the present method may be performed by a programmable processor executing an instruction program, which is used to perform the functions of the present method by operating on input data and generating output. Therefore, the processor may be programmed and coupled to receive data and instructions for transmitting data and instructions to a data storage system, at least one input device, and at least one output device. If necessary, the computer program may be implemented in a procedural programming language or a high-level object-oriented programming language, or in an assembly language or a machine language. In any case, the language may be a compiled or interpreted language. The program may be a complete installation program or an update program. The application of the program on the system in any case results in instructions for executing the present method.

[0152] The program and system can only provide an estimated value of SOH, or even only provide an estimated value of SOC, or even only provide an estimated value of SOH and SOC. It should be understood that when performing an estimation of SOC, the program previously performs an estimation of SOH.

[0153] Fig.18 The memory storage unit of the system shown stores a computer program comprising program code instructions for executing the method for estimating SOH and / or SOC according to the present invention. The memory storage unit is also capable of storing at least the values ​​of the reference image signal. These values ​​are typically Ah PeakMin [N-1] and Ah PeakMax [N-1], and the amount of electricity that has passed through the electrochemical element when the reference image signal is established. These values ​​may also include SOC PeakMin [N-1] and SOC PeakMax [N-1]. The memory storage unit may also store the calculated image signal value and the comparison value. The memory storage unit may also store the reference image signal and / or the derivative of the reference image signal. The memory storage unit may also store one or more reference capacity values ​​Capa batt [N-1].

[0154] In an embodiment, the deformation sensor is a strain gauge that outputs a deformation image voltage over time or in real time. The deformation image signal is formed as a function of the amount of electricity that has passed through the electrochemical element over time, because the amount of electricity that has passed through the electrochemical element is measured in real time. The connection between the real-time deformation image voltage and the amount of electricity that has passed through the electrochemical element over time is direct. More generally, the measurement of the deformation value of the electrochemical element can be performed with any sensor that can detect and generate a value representing the deformation.

[0155] exist Figure 2 , 4 , 8-11, the electrochemical element is in cylindrical form (e.g., a cylindrical battery), and the sensor used is a strain gauge, which is arranged on the surface of the element in a direction substantially perpendicular to the axis of the cylinder; therefore, the strain gauge is arranged in a manner capable of measuring the deformation of the diameter of the cylinder. Still in these embodiments, the strain gauge is also arranged substantially in the middle of the cylinder - that is, the distance between the sensor and the two ends of the cylinder is substantially the same. This positional arrangement of the sensor relative to the cylindrical element makes it possible to measure the deformation in the area with the greatest deformation; this makes it possible, for example, to use sensors with lower sensitivity or sensors with larger measurement errors. It should be understood that the positional arrangement of the sensor is not limited to this embodiment. In general, all configurations are conceivable if the deformation of the element can be measured. For example, different positional arrangements may depend on the shape or form of the electrochemical element, on the type of sensor (sensitivity, measurement error, measurements that may be made in one or two or more directions, etc.).

[0156] In one embodiment, a component includes a SOH-SOC estimation system for estimating the SOH and / or SOC of an electrochemical element, and an electrochemical element. The electrochemical element includes a sensor for measuring a deformation value on the element. The component may include a battery consisting of one or more electrochemical elements. The battery includes a plurality of elements that can be combined together in the same housing. The battery can be divided into a plurality of modules, each module consisting of a plurality of elements connected in series and / or in parallel to each other. The battery is intended to provide electrical energy for external applications. A charging circuit is usually provided, to which the battery can be connected to recharge the element. A management system including measuring sensors and electronic control circuits, which is more or less advanced depending on the application, may be associated with the battery.

[0157] Fig.17An embodiment of a battery configuration, wherein N electrochemical elements (battery 1, battery 2, ..., battery N) are connected in series and arranged together in the same housing to form a first module (module 1). In a similar manner, N electrochemical elements are connected in series and arranged in the Xth housing to form the Xth module (module X). X modules are connected in series to form a battery (Bat). X modules constitute a branch of a circuit. These elements are not necessarily connected in series, but may also be connected in parallel. It is also conceivable to connect certain elements in parallel with each other to obtain a plurality of parallel element combinations, and then connect these combinations of elements in series. Similarly, the battery may include any number of modules, and its configuration is not necessarily limited to series connection. For example, the battery may include p parallel branches, each of which includes at least one element or at least one module.

[0158] Each element may be provided with measuring means for measuring the voltage at its terminals. Preferably, the element is also provided with a device making it possible to measure its operating temperature. The measuring means are placed at judiciously chosen points of the element in order to obtain a representation of its average and / or maximum and / or minimum temperature. If the battery comprises a plurality of elements, each element may be provided with a temperature sensor, which however makes the electronic circuit more complicated.

[0159] The battery must include at least one deformation sensor. One or more deformation sensors can be arranged on the element, or indeed on the module. In practice, the individual elements of the battery include the gauge, since in principle the battery includes identical elements that age and change in a similar manner.

[0160] The method for estimating SOH and / or SOC according to the present invention is applicable to any type of electrochemical element. The method is particularly suitable for electrochemical elements of the type having a no-load voltage (OCV) curve as a function of the state of charge (SOC) containing a flat region, and the relationship between the state of charge and the open circuit voltage (OCV) can be non-bijective. For example, these elements are known from documents EP-A-2 144 075, EP-A-2 239 826 and EP-A-2 309 615, in which a lithium phosphate of at least one transition metal is used as the positive electrode material of the element, in particular a compound of the LiMPO4 type, in which M is selected from a group including Fe, Co, Ni, Mn and mixtures thereof.

[0161] In addition, the method according to the present invention can be applied to any type of electrochemical element, no matter how its form. As a non-limiting example, the electrochemical element can be in the following forms: cylindrical, prismatic, button-shaped, bag-shaped. In one embodiment, the "bag-shaped" type electrochemical element includes at least one battery, which may include a metal plate integrating a positive electrode, a negative electrode and a separator. This battery is derived from the assembly of the juxtaposition of components by parts, which exist in the form of flexible sheets connected together in a housing envelope, thereby forming a "bag-shaped" type element.

Claims

1. A method for estimating the state of health (SOH) of an electrochemical element, comprising: - starting a charging or discharging operation of the electrochemical element; - measuring a value representative of the deformation of the electrochemical element when a charging or discharging operation is performed, the measured deformation value forming a deformation image signal as a function of the amount of electricity passing through the electrochemical element over time; - a comparison is made between the deformed image signal and the reference image signal, wherein one or more differences obtained by the comparison represent an estimated value of the aging of the electrochemical element, wherein the one or more differences obtained by the comparison represent an estimated value of the growth of the passivation layer (SEI) SEI Growth [N] and estimated value of negative capacity loss C neg_loss [N], The estimated value of the aging of the electrochemical element includes an estimated value of the growth of the passivation layer (SEI) SEI Growth [N] and estimated value of negative capacity loss C neg_loss [N].

2. The method according to claim 1, wherein: The comparison also includes: The estimated value Capa of the actual capacity of the electrochemical element is calculated using the following formula: batt [N]: Cape batt [N]=Cap batt [N-1]-(SIX Growth [N]+C neg_loss [N]) in Capa batt [N-1] is the reference capacity value.

3. The method according to claim 1 or 2, wherein: Estimation of the growth of the passivation layer (SEI) SEI Growth [N] is calculated by the following formula: SIX Growth [N]=Ah PeakMin [N-1]-Ah PeakMin [N] in Ah PeakMin [N-1] is a first value representing the amount of electricity that has passed through the electrochemical element for the minimum value of the reference image signal; Ah PeakMin [N] is a second value representing the amount of electricity that has passed through the electrochemical element for the minimum value of the deformed image signal; And, wherein the estimated value C of the negative capacity loss neg_loss [N] is calculated by the following formula: C neg_loss [N]=(Ah PeakMax [N-1]-Oh PeakMin [N−1])–(Ah PeakMax [Next PeakMin [N]) in Ah PeakMin [N-1] is the first value representing the amount of electricity that has passed through the electrochemical element for the minimum value of the reference image signal; Ah PeakMin [N] is the second value representing the amount of electricity that has passed through the electrochemical element for the minimum value of the reference image signal; Ah PeakMax [N-1] is a third value representing the amount of electricity that has passed through the electrochemical element for the maximum value of the reference image signal; Ah PeakMax [N] is a fourth value representing the amount of electricity that has passed through the electrochemical element for the maximum value of the deformed image signal.

4. The method according to claim 3, wherein: The reference image signal is obtained according to the same procedure as the image signal calculated during the charging or discharging operation.

5. The method according to claim 4, wherein: The charging or discharging operation is the first charging or discharging operation of the electrochemical element.

6. The method according to any one of claims 1-2 and 4-5, further comprising: - calculating the time derivative of the reference image signal; And, wherein the comparison includes: - Comparison between the calculated derivative and the reference derivative.

7. A method for estimating the state of charge (SOC) of an electrochemical element, comprising: - starting a charging or discharging operation of the electrochemical element; - measuring a value representative of the deformation of the electrochemical element when a charging or discharging operation is performed, the measured deformation value forming a deformation image signal as a function of the amount of electricity passing through the electrochemical element over time; - a comparison is made between the deformed image signal and the reference image signal, wherein one or more differences obtained by the comparison represent an estimated value of the aging of the electrochemical element, wherein the one or more differences obtained by the comparison represent an estimated value of the growth of the passivation layer (SEI) SEI Growth [N] and estimated value of negative capacity loss C neg_loss [N]; - Determine the SOC value by the first value PeakMin and the second value SOC PeakMax The first value SOC is a value that is defined within a range of state of charge (SOC) values, and outside the range, calibration of the open circuit voltage (OCV) of the electrochemical element can be achieved, wherein the first value SOC PeakMin represents the current SOC of the element for the minimum value of the deformed image signal, the second value SOC PeakMax represents the current SOC of the element for the maximum value of the deformed image signal, The estimated value of the aging of the electrochemical element includes an estimated value of the growth of the passivation layer (SEI) SEI Growth [N] and estimated value of negative capacity loss C neg_loss [N].

8. The method according to claim 7, further comprising the steps of: - Calibrating the open circuit voltage (OCV) of the electrochemical element.

9. The method according to claim 8, wherein: The calibration also includes: estimating the growth of the passivation layer (SEI) Growth [N] and estimated value of negative capacity loss C neg_loss [N] to estimate the aging of the electrochemical device, and wherein the calibrating the open circuit voltage (OCV) of the electrochemical device comprises calibrating the open circuit voltage (OCV) of the negative electrode of the electrochemical device by performing the following: - Calculate the estimated value of the growth of the passivation layer (SEI) Growth [N] and the estimated value of the negative capacity loss C neg_loss [N] Corresponding loss of active material (LAM) and / or loss of lithium storage (LLI); - Correcting the open circuit voltage (OCV) of the negative electrode according to the calculation of loss of active material (LAM) and / or loss of lithium storage (LLI).

10. The method according to any one of claims 7 to 9, wherein: The determination is based on the first value SOC PeakMin and the second value SOC PeakMax The range of state-of-charge (SOC) values ​​defined includes discharge operation for electrochemical devices: - Calculate the SOC value by the following formula PeakMin [N]: SOC PeakMin [N]=100-100*(Ah PeakMin [N] / Layer batt [N]) - Calculate the SOC value by the following formula PeakMax [N]: SOC PeakMax [N]=100-100*(Ah PeakMax [N] / Layer batt [N]) And, wherein the range of determined values ​​includes a charging operation for the electrochemical element: - Calculate the minimum SOC range by the following formula PeakMin [N]: SOC PeakMin [N]=100*(Ah PeakMin [N] / Layer batt [N]) - Calculate the maximum SOC of the range by the following formula PeakMax [N]: SOC PeakMax [N]=100*(Ah PeakMax [N] / Layer batt [N]), in Ah PeakMin [N] is the second value representing the amount of electricity that has passed through the electrochemical element for the minimum value of the reference image signal; Ah PeakMax [N] is a fourth value representing the amount of electricity that has passed through the electrochemical element for the maximum value of the deformed image signal; and Capa batt [N] is an estimate of the actual capacity of the electrochemical element.

11. The method according to claim 10, wherein: The estimated value of the aging of the electrochemical element includes an estimated value of the growth of the passivation layer (SEI) SEI Growth [N] and estimated value of negative capacity loss C neg_loss [N], And, wherein the comparison further comprises: The estimated value Capa of the actual capacity of the electrochemical element is calculated using the following formula: batt [N]: Cape batt [N]=Cap batt [N-1]-(SIX Growth [N]+C neg_loss [N]) in Capa batt [N-1] is the reference capacity value; SEI Growth [N] is an estimate of the growth of the passivation layer (SEI); C neg_loss [N] is an estimate of the negative capacity loss.

12. A computer program product having a computer program stored thereon, which, when executed by a processor, causes the processor to perform the method according to any one of claims 1 to 11.

13. A computer-readable information storage medium having stored thereon the computer program according to the computer program product of claim 12.

14. A system comprising: A deformation sensor for detecting the deformation of the electrochemical element; A management unit for managing the electrochemical element, the management unit communicating with the sensor and comprising a computing unit coupled to a memory storage unit, the memory storage unit storing the computer program according to the computer program product according to claim 12 and being able to store at least the value of the reference image signal, the value of the calculated image signal, and the comparison value.

15. The system of claim 14, wherein: The deformation sensor is a strain gauge that delivers a voltage forming the deformation image signal as a function of the amount of electricity passing through the electrochemical element over time.

16. An assembly comprising: - A system according to claim 14 or 15; - a battery comprising at least one electrochemical element coupled to said deformation sensor.

17. The assembly of claim 16, wherein: The electrochemical element is of a type having a state of charge (SOC) curve including a plateau region, wherein the relationship between the state of charge and / or the open circuit voltage (OCV) in the plateau region is non-bijective.

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