METHOD FOR FORMING AND AGING CELLS FOR ELECTRIC BATTERIES

Abstract

TITLE: METHOD FOR CONTROLLING A CONTINUOUS LINE A method for forming and aging a set of cells for an electric battery comprising successively: a measurement step for each cell of said set of a characteristic indicating a quality of said cell, said characteristic being selected from a pre-established list of characteristics; a classification step of the cells into at least two categories according to the results of the measurements obtained in the preceding step; and a differentiated treatment of the cells of said at least two categories by applying a formation and aging cycle adapted to each category. Figure for the abstract: Figure 4

Description

Title of the invention: METHOD FOR FORMING AND AGING CELLS FOR BATTERIES ELECTRIC Designation of the technical field concerned

[0001] The invention relates to the process of manufacturing cells for electric batteries.

[0002] The invention relates more specifically to the formation and aging phase during which the cells are conditioned to obtain a good lifespan and a significant load capacity during use. Technical problems addressed by the invention

[0003] An electric battery cell is a device that converts chemical energy into electrical energy. It is composed of several key components, including: Anode: The anode is the negative electrode of the cell where chemical oxidation takes place during battery discharge. Cathode: The cathode is the positive electrode of the cell where chemical reduction takes place during battery discharge. Electrolyte: The electrolyte is a conductive material that allows ions to move between the anode and cathode to balance charges during the charging and discharging process. Separator: The separator is a thin membrane that physically isolates the anode from the cathode while allowing the selective passage of ions.

[0004] One of the important distinctions in battery cells is the type of electrolyte used. The main distinction is between solid-state batteries and liquid electrolyte batteries: Solid-state battery: In a solid-state battery, the electrolyte is in solid form and can be a polymer, ceramic, or gel. Wet battery: Wet batteries use a liquid electrolyte, usually a solution of dissolved ions.

[0005] During the formation and aging phase, the cells are charged and then electrically discharged successively so as to form what is called the SEI (Solid Electrolyte Interface) at the electrodes (cathode and anode).

[0006] SEI is a passivation layer that forms on the electrodes, around the graphite particles. It results from the reduction of organic solvents by lithium. Passivation limits the future formation of SEI while allowing the crossing lithium ions. It is necessary for the stability of the cell but it must be formed initially in a controlled manner so as not to grow excessively, consuming all the lithium ions.

[0007] The SEI evolves with time and the use of the cells. This aging limits the capacity of the cells. To avoid this, controlled aging of the cells is carried out during their manufacture. The aging step consists of storing the cells in specific conditions, for example an ambient temperature of approximately 20°C or a high temperature of approximately 50°C, for a relatively long period of a few days to a few weeks.

[0008] The formation and aging phase generally starts with an aging step, for example at room temperature.

[0009] The formation and aging phase generally occurs at the end of cell manufacturing, after the electrolyte filling step.

[0010] This consumes a lot of electricity, particularly with the succession of charges of a large number of cells.

[0011] This step is also crucial to ensure good quality and longevity of the cells.

[0012] Furthermore, manufacturing defects in the cells can impact the formation of SEL.

[0013] The current state of the art does not allow the formation of the SEI to be optimized to achieve the theoretical longevity of the cells, nor to optimize the electricity consumption during the formation of the SEI.

[0014] The invention makes it possible to overcome these problems, by allowing a formation and aging phase adapted to the characteristics of the cells. Summary of the invention

[0015] According to the invention, the cells are placed in a first container, for example a rack, at the start of the formation and aging phase or at the end of the first aging, before the first charge.

[0016] According to the invention, a method is proposed for forming and aging a set of cells for an electric battery, characterized in that it successively comprises,

[0017] . a measurement step for each cell of said set of a characteristic indicating a quality of said cell, said characteristic being selected from a pre-established list of characteristics,

[0018] . a step of classifying the cells into at least two categories according to the results of the measurements obtained in the previous step,

[0019] . a differentiated treatment of the cells of said at least two categories by ap- implementation of a training and aging cycle adapted to each category.

[0020] According to the invention, the characteristic, or the combination of characteristics, measured is indicative of the state of a cell.

[0021] Advantageously according to the invention, the classification of cells into categories makes it possible to adjust the formation and aging phase to the characteristics of each category of cells, according to their characteristics measured or determined from the measurements carried out. This makes it possible to optimize the formation and aging phase and the quality of the cell at the end of it.

[0022] The categorization of cells is for example carried out in three categories, a “Best quality” category, a “Medium quality” category and a “Low quality” category. According to another example, it can include a fourth “Poor quality” category.

[0023] After their classification, the cells can be removed from their original container to be paired in containers containing only cells of the same category.

[0024] Handling means make it possible to remove cells from a first container to place them in a second container where they are grouped by category.

[0025] Advantageously, the handling means make it possible to handle several cells simultaneously.

[0026] The containers can then continue the formation and aging phase with a cycle which is specific to them and which is adapted to the category of cells contained in each container.

[0027] Advantageously, each cell is individually electrically powered by a removable means allowing the removal of a cell from said container while keeping the other cells energized.

[0028] Advantageously according to the invention, the characteristic measured is an internal resistance of the cell and / or an open circuit voltage at the terminals of the cell, and / or an impedance of the cell.

[0029] The internal resistance of the cells is measured in DC mode (direct current) and / or in AC mode (alternating current).

[0030] The simplified Randles model, see [Fig.8], is a simplified representation of an electric battery cell to describe its electrochemical behavior.

[0031] The simplified Randles model has three components, the solution resistance Rs, the charge transfer resistance Rct and the electrochemical double layer capacitance Cdl.

[0032] Knowledge of the three quantities of the simplified Randles model allows a better understanding of the behavior of the cell, and in particular to detect short circuits or other malfunctions.

[0033] The solution resistance Rs is equivalent to the internal resistance of the cell in DC mode. The charge transfer resistance Rct is equivalent to the internal resistance of the cell in AC mode.

[0034] Advantageously according to the invention, the classification of the cells is carried out as a function of a solution resistance Rs of the cell, and / or a charge transfer resistance Rct of the cell, and / or an electrochemical double layer capacity Cdl of the cell, determined for the measurement results obtained.

[0035] Measuring the open circuit voltage across the cell terminals makes it possible to determine the state of charge of the cell.

[0036] Measuring the cell impedance makes it possible to know all the values ​​of each component of the simplified Randles model, Rs, Rct and Cdl.

[0037] To determine the three quantities of the simplified Randles model, an Electrochemical Impedance Spectroscopy (EIS) can be carried out. It consists of carrying out an impedance measurement under different conditions. The different measurement points obtained make it possible to determine these three quantities.

[0038] According to an exemplary embodiment of the invention, the measured characteristic is a geometric characteristic of the cell.

[0039] The measurement of geometric characteristics of the cell makes it possible to detect defects in the internal structure of the battery such as swelling, poor stacking of the electrode layers, or poor dimensions.

[0040] According to another exemplary embodiment of the invention, the characteristic of the cells measured is a characteristic of the electrolyte.

[0041] If the electrolyte is liquid, the measured characteristic relates, for example, to the quality of the penetration of the electrolyte at the interfaces with the electrodes of the cell.

[0042] If the electrolyte is solid, the measured characteristic relates to the quality of the polymerization of the electrolyte or to the homogeneity of the electrolyte.

[0043] The measurement of electrolyte characteristics makes it possible to measure defects of poor penetration of the electrolyte at the interfaces with the electrodes for liquid electrolytes, and areas of non-polymerization or non-homogeneity for so-called solid battery cells.

[0044] The measurement of geometric characteristics and characteristics of the electrolyte is for example carried out using an X-ray scanner. The scanner makes it possible to obtain one or more images of a cell or a part of it.

[0045] These images are compared to reference images corresponding to cell type images corresponding to quality categories, for example “Best quality”.

[0046] For the categorization of a cell, one or more images of it are taken under similar shooting conditions used to obtain the reference images so that they can be compared.

[0047] The assessment of the categorization of a cell based on the image, or the plurality of images, obtained for it can be carried out by an artificial intelligence which has learned to distinguish the quality of the cell according to the characteristics of its images.

[0048] Taking one or more images of a cell may require removing the cell from the cell container in which it is located to place it facing the X-ray scanner, and then placing it back in that container or another.

[0049] Advantageously, the handling of the cells for taking images is carried out automatically by a robotic system. The taking of images and their processing can also be automated.

[0050] For example, the characteristic measured for liquid electrolytes relates to a defect of poor penetration of the electrolyte at the interfaces with the electrodes, and / or in that it relates to areas of non-polymerization and / or non-homogeneity for solid electrolytes.

[0051] Advantageously, the classification of the cells is carried out according to a combination of measured or determined characteristics of said cells.

[0052] The combination of measurements (electrical or other) is advantageous because it allows better distinction between cell categories.

[0053] According to an exemplary embodiment of the invention, the step of measuring the characteristic of each cell is carried out before a first charge of the cells.

[0054] The measurement is carried out during the first aging of the cells or at the end of it. This has the advantage of optimizing the first charge of the formation and aging phase, for optimal efficiency of the process.

[0055] According to another exemplary embodiment of the invention, the step of measuring the characteristic of each cell is carried out during a first charge of said cells, or at the end of this charge.

[0056] The measurement during the first charge makes it possible to take into account the behavior of the cells during charging. The measurement at the end of the first charge makes it possible to take into account the evolution of the cells during it.

[0057] According to another example, the measurement is carried out within the first hour following the start of the first load of a formation and aging phase.

[0058] Carrying out the measurement of at least one characteristic (electrical or other) of the cells in the first hour following the start of the first charge of the formation and aging phase makes it possible to ensure that the cells have stable chemical / electrical behavior and thus to be able to have measurements in a usage situation. standard.

[0059] According to another example, the measurement is carried out during aging of the cell, or at the end of this aging, after a first charge.

[0060] Carrying out the measurement of at least one characteristic (electrical or other) of the cells during aging after a first charge, or at the end of this, makes it possible to make an initial sorting of the defective cells, and thus to optimize the space of the aging part.

[0061] The measurement is advantageously carried out during or at the end of the aging which follows the first charge of the cells. This is generally carried out at high temperature, for example at 50°C.

[0062] According to the invention, after the categorization step, the cells of the same category are grouped in one or more containers.

[0063] Grouping cells of the same category into one or more containers facilitates the application of the same training and aging cycle to these cells. The electrical power supply of a container and the control of the electrical power injected into the cells placed in this container are thus simplified.

[0064] Advantageously according to the invention, the method comprises a second step of measuring a characteristic of each cell, said second measurement step being carried out during a training and aging cycle after said measurement, the second measurement step being followed by a second step of categorizing the cells into at least two new categories according to the measurement results obtained in the second measurement step.

[0065] The second step of categorizing the cells during the training and aging phase makes it possible to adjust and optimize the rest of the training and aging cycle by cell category.

[0066] The second categorization step can allow a second, finer sorting of the cells, after a first rapid sorting of the cells after the first categorization step. Brief description of the figures

[0067] Other characteristics and advantages of the invention will appear during the reading of the detailed description which follows for the understanding of which reference will be made to the appended drawings in which:

[0068] [Fig.l] is a schematic and partially represented view, in top view, of a cell container before the start of a formation and aging phase according to the invention,

[0069] [Fig.2] is a schematic and partially represented view of the cell container of [Fig.l] after a categorization of the cells according to the invention,

[0070] [Fig.3] is a schematic and partially represented view, in top view, of three cell containers after arranging the cells of [Fig.2] in different containers according to the characteristics of the cells,

[0071] [Fig.4] is a diagram illustrating a first example of a training phase and aging according to a first exemplary embodiment of the invention,

[0072] [Fig.5] is a diagram illustrating a second example of a training phase and aging according to a second exemplary embodiment of the invention,

[0073] [Fig.6] is a diagram illustrating a third example of a training phase and aging according to a third exemplary embodiment of the invention,

[0074] [Fig.7] is a diagram illustrating a fourth example of a training phase and aging according to a fourth embodiment of the invention, and

[0075] [Fig.8] is a diagram illustrating the simplified Randles model, which is an implementation equation of the electrical behavior of an electric battery cell.

[0076] [Fig.l] illustrates an example of container 1 of cells 2 before the start of a formation and aging phase according to the invention. To simplify the representation, the container only comprises nine cells knowing that an industrial container can contain around fifty or more.

[0077] Each cell comprises terminals 3 to which a device 4 for measuring at least one characteristic of said cell can be connected, or devices successively measuring different characteristics of the cell.

[0078] [Fig.2] shows the state of container 1 after a step of classifying the cells into three categories C1, C2, C3 according to the results of the measurements carried out on the cells.

[0079] In this example, six cells are classified as category Cl, two are classified as category C2 and one is classified as category C3.

[0080] [Fig. 3] shows the state of container 1 after moving the cells of categories C2 and C3 into other containers 1b, 1c. Only the cells of category C1 were kept in container 1. The two cells of category C2 were placed in a container 1b intended to contain only cells of category C2 and the cell of category C3 was placed in a container 1c intended to contain only cells of category C3.

[0081] Alternatively, the cells of category Cl are moved into a container intended to contain only cells of category CL. This is done in particular when the containers 1 and the containers 1b and 1c are of different natures.

[0082] Alternatively, the cells are maintained in the container 1 where the measurement of at least one characteristic of said cells is carried out, after the categorization of the cells. The cells then follow a phase of formation and aging differentiated according to their category but remaining positioned in the same container.

[0083] [Fig.4] is a diagram partially illustrating a first example of a cycle of a formation and aging phase according to a first example of application of the invention. In this diagram, we have on the abscissa the time of progress of the formation and aging phase of a set of cells and, on the ordinate, the state of charge of said cells.

[0084] To simplify the description and the figures, the cycle of a formation and aging phase is represented in Figures 4 to 7 on a single diagram, without taking into account a cell movement time, while cells can be moved into different containers after the cell classification step. Similarly, cells can be stored at different locations between the aging phases and the charging / discharging phases.

[0085] Similarly, in the diagrams of Figures 4 to 7, only the beginning of the total formation and aging cycle is represented, which may include a large number of successive sequences of charging and discharging the cells.

[0086] In this example, the step M of measuring at least one characteristic (electrical or other) of the cells contained in the container 1 is carried out at time t10 after precharging the cells to a charge level N10.

[0087] Still to simplify the diagram and the description, all the cells follow the same precharge curve from t0 to t10. Depending on the characteristics of the cells, they can charge more or less quickly so that the charge level reached at t10 can be different depending on the cells.

[0088] After the measurement of step M, the cell categorization step is carried out and they are divided into three categories according to the measurement result, as shown in [Fig.3],

[0089] According to the invention, the parameters of the rest of the training and aging phase are adjusted and optimized for each category of cells according to the results obtained during the measurement in step M.

[0090] The formation and aging phase continues with high-temperature aging, from time t10 to time t20. In this example, the cell charge decreases from level N10 to level N20, which is identical for all three cell categories. Similarly, the speed at which the cell charge level decreases from level N10 to level N20 is the same for all three cell categories.

[0091] According to other examples of application of the invention, or according to other behaviors of the cells according to their characteristics, the charge level N20, and / or the rate of descent to the charge level N20, may be different for each category of cells. The charge level may also be maintained at the level N10 during the duration of the high-temperature aging.

[0092] At the end of high temperature aging, the formation and aging phase continues, for a first category of cells, with a cycle of charge cells from t20 to t30, discharge from t30 to t40 then charge again.

[0093] For this first category of cell, the charge between t20 and t30 is carried out at a charge level N30 lower than the maximum charge of the cells. For the other two categories, the cells are charged to 100%. Similarly, for the first category of cell, the discharge is carried out up to a level N40 where a charge level is maintained whereas for the other two categories of cell, the discharge is total. The rates at which the charge and discharge are carried out are different here depending on the cell categories.

[0094] After the first cell charge / discharge cycle shown in [Fig.4], for example from t20 to t40 for the first category of cells, a plurality of other charge / discharge cycles can be carried out depending on the nature and categories of the cells.

[0095] [Fig. 5] is a diagram similar to that of [Fig. 4] illustrating a second example of application of the invention. In this example, the step M of measuring at least one characteristic (electrical or other) of the cells contained in the container 1 is carried out at time t1 1 after precharging the cells to a charge level NI 1 which may be lower than that of the first example of embodiment represented in [Fig. 4].

[0096] After the measurement, the cells are divided into three categories according to the measurement result.

[0097] Again, the parameters of the training and aging phase are adjusted and optimized for each cell category for the rest of the training and aging cycle.

[0098] The formation and aging phase continues with an additional charge of the cells to a charge level N21. For a first category of cells, it is carried out between t1 1 and t21.

[0099] In this example, the charge level N21 is the same for the three cell categories while the rate of rise to this charge level N21 is different depending on the cell category. According to other examples of application of the invention, the charge level N21 may be different depending on the cell category.

[0100] After reaching the charge level N21, the formation and aging phase of the first category of cells continues from t21 to t31 by aging at high temperature. In this example, the charge of the cells drops from level N21 to a level N31, which is identical for the three categories of cells. Similarly, the speed at which the charge of the cells drops from level N21 to level N31 is here the same for the three categories of cells. According to other examples of application of the invention, or according to other behaviors of the cells according to their characteristics, the charge level N31, and / or the speed of descent to the charge level N31, may be different for each category of cells. Similarly, the charge level may be maintained at N21 level for the duration of high temperature aging.

[0101] At the end of the high-temperature aging, the formation and aging phase of the first category of cells continues with a cycle of charging from t31 to t41, discharging from t41 to t51 and then charging the cells again. In this exemplary embodiment, the charge level reached by the cells at the end of charging is different depending on the cell category. For a first category of cell, charging is carried out up to a level N41. For the other two categories of cell, charging is total. Similarly, the discharge of the first category of cell is partial, up to a level N51 while it is total for the other two categories of cell. The rates at which charging and discharging are carried out are also different depending on the cell categories.

[0102] After the first cell charge / discharge cycle shown in [Fig.5], a plurality of other charge / discharge cycles can be carried out depending on the nature and categories of the cells.

[0103] [Fig. 6] is a diagram similar to that of Figures 4 and 5 illustrating a third example of application of the invention. In this example, step M of measuring at least one characteristic (electrical or other) of the cells contained in the container 1 is carried out after aging at room temperature of the cells from t0 to t12. The cells have not, at this stage, yet been charged.

[0104] After measurement, the cells are divided into three categories according to the measurement result.

[0105] The formation and aging phase continues from t12 to t22, for a first category of cells, by a first charge of the cells to a charge level N12. In this example, the charge level N12 is the same for the three categories of cells while the rate of rise to this charge level N12 is different depending on the category of cells.

[0106] According to other examples of application of the invention, the charge level N12 may be different depending on the category of cells or the rate of rise to this charge level N12 may be identical for the three categories.

[0107] After reaching the charge level N12, the formation and aging phase of the first category of cells continues from t22 to t32 by aging at high temperature. In this example, the charge of the cells drops from level N12 to an identical level N22 for the three categories of cells. Similarly, the speed at which the charge of the cells drops from level N12 to level N22 is here the same for the three categories of cells. According to other examples of application of the invention, or according to other behaviors of the cells according to their characteristics, the charge level N22, and / or the speed of descent to the charge level N22, may be different for each category of cells. Similarly, the charge level may be maintained at level N12 for the duration of high temperature aging.

[0108] At the end of high temperature aging, the formation and aging phase of the first category of cells continues with a cycle of charging from t32 to t42, discharging from t42 to t52 and then charging the cells again.

[0109] In this embodiment, the charge level N32 reached by the cells of a first category is limited at the end of charging while it is 100% for the other two cell categories. Similarly, the charge level N42 reached by the cells of the first cell category after discharging is higher than that of the other two cell categories, the latter being completely discharged. The speeds at which charging and discharging are carried out are also different depending on the cell categories.

[0110] After the first cell charge / discharge cycle, shown in [Fig.6] from t32 to t52 for the first category of cells, a plurality of other charge / discharge cycles can be carried out depending on the nature and categories of the cells.

[0111] [Fig.7] is a diagram similar to that of Figures 4, 5 and 6 illustrating a fourth example of application of the invention for a single category of cell.

[0112] In this example, a first step M of measuring at least one characteristic (electrical or other) of the cells is carried out after precharging the cells to a charge level N13.

[0113] The formation and aging phase continues from 113 to t23 by high temperature aging. In this example, the cell charge decreases from level N13 to level N23.

[0114] At the end of the high temperature aging, the formation and aging phase continues from t23 to t33 by a total charge of the cells, then a total discharge from t33 to t43 then again a charge of the cells from t43 to t53 to a level N33.

[0115] In this example, the charge level N33 is higher than that of the level N13. It could be equal or lower.

[0116] A new measurement of at least one characteristic (electrical or other) of the cells is carried out at this charge level N33 in order to verify the possible evolution of at least one characteristic of the cells since the start of the formation and aging cycle.

[0117] Depending on the measurement result, the rest of the training and aging cycle is continued by maintaining the initially planned cycle or by adjusting them according to the results of the measurement carried out at load level N33.

[0118] Other measurements of at least one characteristic (electrical or other) of the cells may be carried out at other times during the formation and aging phase in order to verify the evolution of at least one characteristic of the cells and to adjust the rest of the cycle, if necessary, according to the results of the measurements.

[0119] [Fig.8] is a schematic of the simplified Randles model representative of a typical cell. It consists of three important elements: the solution resistance Rs, the charge transfer resistance Rct and an electrochemical double layer capacitance Cdl.

[0120] The tables below illustrate the criteria taken into account for the categorization of cells, according to an example of application of the invention. Cell categories; Best quality Average quality Low quality Poor quality Electrical characteristics of the cells (via an ElS measurement) ! Resistance of : ; solution Rs 1 1 Resistance of i ! charge transfer : | Rct : Lower than 10% compared to the standard Lower than 10% compared to the standard Between -10% and +5% compared to the standard Between -10% and +5% compared to the standard Between +5% and +10% compared to the standard Between +5% and +10% compared to the standard Greater than 10% compared to the standard Greater than 10% compared to the standard ; Double layer capacity : ; electrochemical 1 ] edi i Greater than 10% compared to the standard Between 10% and -5% compared to the standard Between -5% and -10% compared to the standard Less than 10% compared to the standard 1 State of charge (via : ! measurement of the : ; circuit voltage I ;open) 1 Difference less than 1% from the set value Difference between 1-2% from the set value Difference between 2-3% from the set value Difference more than 3% from the set value Geometric characteristics of the cells; Swelling l Difference in volume from requirements less than 0.5% Difference in volume from requirements between 0.5-1% Difference in volume from requirements between 1-2% Difference in volume from requirements more than 2% ! Bad î ! stacking of : ; layers I ! of electrodes I Intersection of non-stacked surfaces less than 0.05% of the surface area of ​​a layer Intersection of non-stacked surfaces between 0.05-0.075% of the surface area of ​​a layer Intersection of non-stacked surfaces between 0.075-0.1% of the surface area of ​​a layer intersection of non-stacked surfaces greater than 0.1% of the surface area of ​​a layer;Dimensions: Length / width / height differences from requirements less than 0.5% Length / width / height differences from requirements between 0.5-1% Length / width / height differences from requirements between 1-2% Length / width / height differences from requirements greater than 2%; 1 Cell Categories Best Quality Medium Quality < Low Quality ; Poor Quality | Electrolyte characteristics Poor penetration of the electrolyte at the interfaces with the electrodes Difference in correlation with the “best quality” reference image less than 15% Difference in correlation with the “medium quality” reference image less than 15% Difference in correlation with the “low quality” reference image: less than 15% Difference in correlation with the “poor quality” reference image less than 15% Non-polymerization zone Difference in correlation with the “best quality” reference image less than 15% Difference in correlation with the “medium quality” reference image less than 15% Difference in correlation with the “low quality” reference image less than 15% Difference in correlation with the “poor quality” reference image less than 15%non-homogeneity Difference in correlation with the “best quality” reference image Less than 15% Difference in correlation with the “medium quality” reference image less than 15%: Difference in correlation with the “low quality” reference image: less than 15% i Difference in correlation with the “poor quality” reference image less than 15%

[0121] The setpoint value, in the context of the state of charge of a cell, is a value (generally in percentage) set by the manufacturer of electric battery cells.

[0122] For example, if all the results of the measurements carried out on a cell comply with the criteria required for the best quality cells, said cell will be categorized as such and it will follow a formation and aging phase adapted to this category of cells.

[0123] For example, cells are categorized according to the worst result obtained. Thus, if all but one of the results for a cell are of the best quality but one result corresponds to a low-quality cell, the cell may be categorized as low-quality.

[0124] A weighting grid for the different criteria could be considered so that the categorization of a cell takes into account the relative weight of each criterion. Thus, for example, if only one measurement is in the Medium quality category but this measurement has a low weighting, the cell could nevertheless be classified as Best quality.

[0125] The examples of application of the invention described to illustrate the invention are not limiting. Other cycles can be carried out according to the initial characteristics of the cells and according to the characteristics targeted at the end of formation and aging.

Claims

Claims

1. Method for forming and aging a set of cells (2) for an electric battery, characterized in that it successively comprises, . a step of measuring for each cell of said set a characteristic indicating a quality of said cell, said characteristic being selected from a pre-established list of characteristics, . a step of classifying the cells into at least two categories according to the results of the measurements obtained in the previous step, . a differentiated treatment of the cells of said at least two categories by applying a training and aging cycle adapted to each category.

2. Method according to claim 1, characterized in that the measured characteristic is an internal resistance of the cell (2) and / or an open circuit voltage at the terminals (3) of the cell, and / or an impedance of the cell.

3. Method according to one of the preceding claims, characterized in that the classification of the cells (2) is carried out according to a solution resistance (Rs) of the cell, and / or a charge transfer resistance (Rct) of the cell, and / or an electrochemical double layer capacitance (Cdl) of the cell, determined for the measurement results obtained.

4. Method according to claim 1, characterized in that the measured characteristic is a geometric characteristic of the cell.

5. Method according to claim 1, characterized in that the measured characteristic is a characteristic of an electrolyte of the cell.

6. Method according to one of the preceding claims, characterized in that the classification of the cells is carried out according to a combination of measured or determined characteristics of said cells.

7. Method according to one of the preceding claims, characterized in that the step of measuring the characteristic of each cell is carried out before a first charge of the cells.

8. Method according to one of claims 1 to 6, characterized in that the step of measuring the characteristic of each cell is carried out during a first charge of said cells, or at the end of this charge.

9. Method according to the preceding claim, characterized in that the measurement is carried out within the first hour following the start of the first charge of a training and aging phase.

10. Method according to one of claims 1 to 6, characterized in that the measurement is carried out during aging of the cell, or at the end of this aging, after a first charge.

11. Method according to one of the preceding claims, characterized in that, after the classification step, the cells of the same category are grouped in one or more containers.

12. Method according to one of the preceding claims, characterized in that it comprises a second step of measuring a characteristic of each cell, said second measurement step being carried out during a training and aging cycle after said measurement, the second measurement step being followed by a second step of classifying the cells into at least two new categories according to the measurement results obtained in the second measurement step.

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