US-12618914-B2 - Method for determining the service life of an electrochemical cell of a battery in real time

US12618914B2US 12618914 B2US12618914 B2US 12618914B2US-12618914-B2

Abstract

The present invention relates to a method for determining the lifetime of an electrochemical element of a battery in real time as a function of a determined application, applicable in the field of primary type batteries. The method comprises: —a step ( 1 ) of measuring at least one intensity value (I) of the current provided by the electrochemical element and of measuring at least one temperature value (T) of the electrochemical element in the determined application; —a step ( 4 ) of computing total lifetime allowing the availability time of the electrochemical element to be computed on the basis of a determined initial time, as a function of the one or more current intensity value(s) (I) and of the one or more temperature values (T) measured during the measuring step ( 1 ), as a function of a determined value of the capacity of the electrochemical element, of the cut-off voltage of the determined application, and of the background current of the determined application.

Inventors

Sébastien LAURENT
Sébastien Benjamin
Isabelle SOURMEY
Romain CAYZAC
Willy PRODHOMME
Nicolas PAQUIN

Assignees

SAFT

Dates

Publication Date: 20260505
Application Date: 20210311
Priority Date: 20200324

Claims (18)

1 . A method for real-time determination of a service life of an electrochemical cell of a primary battery as a function of a determined application, the method comprising: measuring, from the electrochemical cell in the determined application, at least one current value (I), supplied by the electrochemical cell, and at least one temperature value (T); and determining the service life by calculating an availability time, of the electrochemical cell and starting from a determined initial time, based on the at least one current value (I) and the at least one temperature value (T), as measured from the electrochemical cell in the determined application, and further based on a capacity (C) of the electrochemical cell, a cut-off voltage (Vc) for the determined application, a background current (If) for the determined application, and by determining C×Kp×R/(Imoy+Iad), wherein Kp is a cutoff coefficient (Kp) of the electrochemical cell and is a function of both a maximum current value (Imax), drawn by the determined application, and the cut-off voltage (Vc) for the determined application, Imoy is an average current (Imoy) drawn by the determined application, is obtained from the at least one current value (I), and includes the background current (If) for the determined application, R is a performance (R) in terms of capacity of the electrochemical cell and is a function of both a temperature, of the electrochemical cell in the determined application, and any of the average current (Imoy) and the maximum current value (Imax) drawn by the determined application, and Iad is a self-discharge current (Iad) of the electrochemical cell and is a function of both the average current (Imoy), drawn by the determined application, and the temperature of the electrochemical cell in the determined application.
2 . The method according to claim 1 , wherein the performance (R) and the self-discharge current (Iad) are obtained from respective tables associating the performance (R) and the self-discharge current (Iad) with pairs of values of the at least one temperature value (T) and the any of the average current (Imoy) and the maximum current value (Imax).
3 . The method according to claim 1 , wherein the cutoff coefficient (Kp) is obtained from a table associating the cutoff coefficient (Kp) with pairs of values representing the maximum current value (Imax) and the cut-off voltage (Vc).
4 . The method according to claim 1 , wherein the background current (If) is any of obtained by measurement and as a parameterizable constant.
5 . The method according to claim 1 , further comprising, before determining the service life by calculating the availability time and after measuring the at least one current value (I) and the at least one temperature value (T) storing a profile, for the determined application, the maximum current (Imax), the average current (Imoy), and the at least one temperature value (T).
6 . The method according to claim 5 , wherein the at least one temperature value (T) is stored in a table in association with durations of exposure, representing at least one duration, during which exposure to the at least one temperature value (T) has occurred.
7 . The method according to claim 5 , further comprising checking for a request to calculate the service life, and based on identifying, while checking for the request, that the request has been received, calculating the service life ( 4 ), and based on identifying, while checking for the request, that the request has not been received, implementing: another measuring, from the electrochemical cell in the determined application, of the at least one current value (I), supplied by the electrochemical cell, and the at least one temperature value (T); and another storing of the profile, for the determined application, the maximum current (Imax), the average current (Imoy), and the at least one temperature value (T).
8 . The method according to claim 6 , wherein, in the table, the at least one temperature value (T) is grouped, by temperature thresholds (T), with other temperature values, and the temperature thresholds are associated in the table with the durations of exposure.
9 . The method according to claim 1 , further comprising storing an elapsed time, starting from the determined initial time, and calculating, as a change to the service life, a remaining service life of the electrochemical cell by subtracting the elapsed time from the service life.
10 . The method according to claim 9 , further comprising calculating a state of charge of the electrochemical cell by dividing a value of the remaining service life by a value of the service life.
11 . The method according to claim 1 , wherein the capacity (C) of the electrochemical cell corresponds to a nominal capacity of the electrochemical cell, and the determined initial time corresponds to a time at which production of the electrochemical cell was completed.
12 . The method according to claim 1 , wherein the capacity (C) of the electrochemical cell corresponds to a nominal capacity of the electrochemical cell minus a capacity loss during a determined period, and the determined initial time corresponds to a time at which the electrochemical cell was put into use for a first time and is determined to be a time at which production of the electrochemical cell was completed plus a duration of the determined period.
13 . A non-transitory computer-readable storage medium comprising instructions which, when executed by a computer, cause said computer to carry out the method according to claim 1 .
14 . A system for managing a device or installation comprising a battery, said battery comprising at least one electrochemical cell, the system comprising: means for measuring at least one value for the at least one current value (I) supplied by the electrochemical cell and the at least one temperature value (T) of the electrochemical cell in the determined application; and electronic or computer computing means programmed to carry out the method according to claim 1 .
15 . A battery comprising: at least one electrochemical cell; means for measuring at least one value for the at least one current value (I) supplied by the electrochemical cell and at least one temperature value (T) of the electrochemical cell in the determined application of said electrochemical cell; and electronic computing means programmed to carry out the method according to claim 1 .
16 . The battery of claim 15 wherein the at least one electrochemical cell is of a LiSOCl 2 type.
17 . The battery of claim 16 , wherein the at least one electrochemical cell is of the LiSOCl 2 type as a primary cell with a liquid cathode of the LiSOCl 2 type.
18 . The battery of claim 17 , wherein the primary cell comprises a constant no-load voltage, flat profile, throughout a life of the primary cell.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is a National Stage of International Application No. PCT/EP2021/056201 filed Mar. 11, 2021, claiming priority based on French Patent Application No. 2002869 filed Mar. 24, 2020. FIELD OF THE INVENTION The present invention relates to a method for real-time determination of the service life of an electrochemical cell of a battery. It finds an application in the field of primary-type batteries. BACKGROUND ART The determination of the remaining life (or the remaining capacity, or the state of charge) of a primary cell or battery, such as a battery comprising one or more electrochemical cells of the primary lithium type, for example of the lithium thionyl chloride type (LiSOCl2), is a particularly important problem in many applications that use this type of cell or battery, in order to anticipate the replacement of a discharged battery. Solutions for determining the remaining service life of a battery are known, which consist in performing a measurement of the voltage across the battery and using a characteristic curve of the no-load voltage of this battery as a function of its state of charge. However, such solutions are not suitable for application to lithium thionyl chloride electrochemical cells, because in this case the no-load voltage is constant throughout the life of the battery and drops only at the very end of battery life. Applying such a solution therefore is equivalent to generating an alarm indicating to the user that the battery must be replaced, at the very end of service life of the battery, and therefore without actual possibility of anticipating replacement of the battery. Other solutions for determining the remaining life of a primary cell, particularly of the LiSOCl2 type, are also known, which also involve measuring the voltage across the battery, and then analyzing the voltage response to making a demand on the battery. However, this method is complex because it is based on a very fast data acquisition frequency as well as a very precise estimation of the state of passivation of the battery. In the absence of a sufficiently rapid frequency and a sufficiently accurate estimate, the result may be false. Moreover, the conditions under which the demand is made of the battery (current, temperature . . . ) must be reproducible so that results are comparable. This method is therefore difficult to implement. It is also known from document CN103592605, a method for determining the remaining capacity of a primary cell of the LiSOCl2 type from a measurement of current and temperature. However, this method is based on a calculation of capacity loss by a coulometric method (calculation of the Amps-hours discharged) as well as taking account of calendar self-discharge (as a function of temperature only). This method is nevertheless not satisfactory because it does not take the specificities of each application into account. More generally, the known methods are based on the use of theoretical usage profiles. However, if the usage differs from what is expected, the estimate is false with the consequences of either no longer having energy available to perform an operation if the usage has been under-estimated, or the premature replacement of a battery if the usage has been over-estimated. Thus, the aim of the invention is to solve in particular the aforementioned problems, by providing a method for determining in real time the service life of an electrochemical cell of a primary battery which is accurate, and which takes into account the specificities of each application. SUMMARY OF THE INVENTION The invention therefore provides, in a first aspect, a method for real-time determination of the service life of an electrochemical cell of a primary battery as a function of a determined application, the method comprising: a step of measuring at least one value for current supplied by the electrochemical cell and at least one temperature value of the electrochemical cell in the determined application,a total service life calculation step for calculating availability time of the electrochemical cell starting from a determined initial time, as a function of the at least one current value and the at least one temperature value measured during the measurement step, as a function of a determined value of capacity of the electrochemical cell, cut-off voltage for the determined application, and background current for the determined application. Depending upon applications, the background current can represent the majority consumption of a primary battery. This background current corresponds to the permanent consumption of the electronics of the application in question: leakage current of each of the electronic components of the system (for example: consumption of a microcontroller in standby mode). In some embodiments, the method further comprises one or more of the following features, taken alone or in all technically possible combinations: the total service li