Inerting device and method for an electrochemical accumulator

Abstract

Disclosed are an inerting device and method using an electrochemical accumulator cell (1) which comprises a casing (4) enclosing active areas (2) and a dead volume (6), as well as an inerting spacer (17) that consists of a solid porous part, is arranged inside the casing (4) and is included in the dead volume (6).

Description

[0001] DESCRIPTION

[0002] Title: Inerting device and method for electrochemical accumulator

[0003] TECHNICAL FIELD

[0004] The invention relates to the field of electrochemical accumulators and more particularly to inerting means enabling in particular the recycling of electrochemical accumulators.

[0005] Electrochemical accumulators allow the storage of electrical energy and are increasingly common, particularly in widespread applications involving high power, such as the propulsion of electric vehicles. The recycling of electrochemical accumulators is a crucial operation for a sector that is set to become increasingly important. Electrochemical accumulator inerting means are necessary to completely discharge an electrochemical accumulator, whatever its initial state of charge and even if the latter is not known. These inerting means are essential to guarantee the safety and operational security required before any dismantling operation of an electrochemical accumulator as part of its recycling.

[0006] PRIOR ART

[0007] Inerting methods currently known in the context of recycling electrochemical accumulators are generally manual methods, suitable for low rates and offering random operational safety.

[0008] STATEMENT OF THE INVENTION

[0009] The aim of the invention is to improve the means of inerting electrochemical accumulators of the prior art.

[0010] To this end, the invention relates to an electrochemical accumulator cell which comprises an envelope containing active zones and a dead volume, and comprising an inerting spacer consisting of a solid porous part, arranged inside the envelope, and included in the dead volume. According to another object, the invention relates to an inerting system for an electrochemical accumulator cell, comprising:

[0011] - a cell as described previously;

[0012] - a drilling device adapted to form in the cell envelope and in the inerting spacer an inerting conduit opening into the inerting spacer, by drilling the inerting spacer;

[0013] - an injection cannula adapted to be inserted into the inerting conduit and to open into the inerting spacer;

[0014] - a device for injecting an inerting liquid through the injection cannula.

[0015] According to another object, the invention relates to a method for inerting an electrochemical accumulator cell as described previously, comprising the following steps:

[0016] - formation of an inerting conduit in the casing by piercing the casing opposite the inerting spacer, and by piercing the inerting spacer;

[0017] - introduction of an injection cannula into the inerting conduit, the end of the injection cannula opening into the inerting spacer;

[0018] - injection through the injection cannula of a predetermined volume of an inerting liquid.

[0019] The dead volume of the electrochemical accumulator cell is defined as an empty internal volume of the cell, which is outside the active areas consisting of the electrodes and the electrolyte.

[0020] The invention guarantees the inerting of an electrochemical accumulator cell, i.e. the neutralization of any electrochemical reaction within it, which corresponds to a complete discharge of the cell. Inerting is carried out simply and quickly, with a high level of safety.

[0021] An inert electrochemical accumulator cell, devoid of stored energy, can thus be dismantled, crushed or undergo any other suitable recycling process. The invention is particularly advantageous for the recycling of large and high-power accumulator batteries, operations which tend to become essential with the massive distribution of these batteries, and current and future regulations. Indeed, when an electrochemical accumulator battery, for example an electric vehicle battery made up of lithium-ion accumulator cells, is received at a recycling center, its state of charge is not necessarily known in advance, and its cells can potentially contain a significant quantity of energy.The invention allows recycling without having to know the state of charge of the battery, and therefore without having to carry out physicochemical measurements, electrical measurements, or consultations of the BMS (Battery Management System) devices possibly associated with the battery. Recycling operations can begin safely with the certainty of working on electrochemical accumulator cells that do not contain energy.

[0022] The invention allows operations of drilling a conduit and injecting a limited volume of inerting liquid, specific to each cell. These operations take place in a short time, which makes it possible to inert large quantities of electrochemical accumulator cells with small quantities of inerting liquid.

[0023] In addition, for cells whose safety cut-off device has been triggered, for example a CID (Current Interrupt Device), the externally accessible terminals of the cell are no longer both connected to the two potentials. The invention also makes it possible to inert such cells, which can no longer be discharged via their external terminals.

[0024] The electrochemical accumulator cell according to the invention may include the following additional characteristics, alone or in combination:

[0025] - the inerting spacer is placed against the wall of the cell envelope;

[0026] - the cell is cylindrical in shape, the dead volume comprising a central barrel delimited by the active zones, the inerting spacer extending along the longitudinal axis of the central barrel;

[0027] - the cell comprises a plurality of coils, the inerting spacer being arranged in an inter-coil zone; - the cell comprises a flattened coil, the inerting spacer being arranged along the longitudinal axis of the coil, in a zone which is located at the heart of the coil, and which is adjacent to the active zones of greater radius of curvature;

[0028] - the cell has a vent opening into the dead volume, the inerting spacer being arranged opposite the vent;

[0029] - the cell has external signage on the casing identifying the position of the inerting spacer.

[0030] The electrochemical accumulator cell inerting system according to the invention may include the following additional characteristics, alone or in combination:

[0031] - the piercing device and the injection cannula are both formed from a perforating injection cannula;

[0032] - the inerting system comprises a means of identifying the cell and a means of correspondence between the identified electrochemical accumulator cell and: a drilling zone in the casing, opposite the inerting spacer; and a volume of inerting liquid to be injected;

[0033] - the inerting system comprises an inerting support comprising an inerting liquid distribution conduit connected to the injection cannula which is fixed on the inerting support, and a location for the electrochemical accumulator cell arranged so that, when the electrochemical accumulator cell is inserted into the location, the injection cannula opens into the inerting spacer, piercing the inerting spacer.

[0034] The method according to the invention may include the following additional characteristics, alone or in combination:

[0035] - the predetermined volume of an inerting liquid is a volume substantially equal to the dead volume of the electrochemical accumulator cell;

[0036] - the casing comprising a vent, the step of forming an inerting conduit is carried out by piercing the vent; - the electrochemical accumulator cell being cylindrical in shape and the dead volume comprising a central barrel delimited by the active zones, the step of forming an inerting conduit is carried out by piercing the casing in the longitudinal axis of the central barrel;

[0037] - the electrochemical accumulator cell comprising coils, the step of forming an inerting conduit is carried out by piercing the casing in an inter-coil zone;

[0038] - the electrochemical accumulator cell comprising a flattened coil, the step of forming an inerting conduit is carried out by piercing the casing along the longitudinal axis of the coil, opposite a zone which is located at the heart of the coil, and which is adjacent to the active zones of greater radius of curvature;

[0039] - the step of forming an inerting conduit and piercing the inerting spacer, and the step of introducing an injection cannula into the inerting conduit are carried out simultaneously by a perforating injection cannula;

[0040] - the method comprises a preliminary step of identifying the electrochemical accumulator cell and determining: a drilling zone on the casing, this drilling zone being located opposite the inerting spacer; and a volume of inerting liquid to be injected;

[0041] - the method comprises an additional step of controlling the temperature of the electrochemical accumulator cell after the injection step;

[0042] - the method includes a step of alerting the end of inerting when the temperature of the electrochemical accumulator cell falls below a predetermined threshold;

[0043] - the electrochemical accumulator cell comprising a thermal management device, the method comprises a step of controlling the temperature of the electrochemical accumulator cell, and of controlling the thermal management device to maintain the temperature of the electrochemical accumulator cell below a maximum temperature. PRESENTATION OF THE FIGURES

[0044] Other characteristics and advantages of the invention will emerge from the non-limiting description which follows, with reference to the appended drawings in which:

[0045] - figure 1 schematically illustrates an electrochemical accumulator cell;

[0046] - figure 2 illustrates a first step of a process of inerting the cell of figure 1;

[0047] - Figure 3 illustrates a second step of the process;

[0048] - Figure 4 illustrates a third step of the process;

[0049] - Figure 5 is a graph illustrating the inerting of an accumulator cell;

[0050] - figure 6 illustrates the application of the method according to the invention to a particular accumulator cell;

[0051] - figure 7 illustrates another example of an electrochemical accumulator cell according to the invention;

[0052] - Figure 8 is a schematic sectional view of the electrochemical accumulator cell of Figure 7;

[0053] - figure 9 illustrates the application of the inerting process to the electrochemical accumulator cell of figures 7 and 8;

[0054] - Figure 10 and Figure 11 illustrate the application of the inerting process to another type of electrochemical accumulator cell;

[0055] - figure 12 illustrates another example of an electrochemical accumulator cell adapted to benefit from the inerting process;

[0056] - figure 13 illustrates an inerting support;

[0057] - figure 14 illustrates an inerting system according to the invention, comprising the inerting support according to figure 13.

[0058] Elements similar and common to the various embodiments have the same reference numbers in the figures. DETAILED DESCRIPTION

[0059] Figure 1 schematically illustrates in section an electrochemical accumulator cell 1. This illustrative example is a cylindrical accumulator cell, of lithium-ion chemistry.

[0060] The cell 1 comprises a sealed envelope 4 containing active zones 2 which are conventionally made of an alternating winding of electrodes and electrolyte. Inside the envelope 4, the cell 1 further comprises a dead volume 6 consisting of empty spaces outside these active zones 2. In this example of a cylindrical cell, this dead volume 6 comprises in particular a central barrel 3 which is delimited by the winding of electrodes and electrolyte.

[0061] In the context of the present invention, the electrochemical accumulator cell 1 is for example received in a recycling center for its disassembly with a view to the recovery of its constituent elements, in particular the metals it contains, and the proper disposal of the polluting elements. The electrochemical accumulator cell 1 potentially has an unknown charge when it is received in the recycling center.

[0062] The electrochemical accumulator cell 1 will first be inerted in order to release the energy it contains, to bring its voltage back to zero, and thus to allow its disassembly in complete safety.

[0063] The cell 1 further comprises a porous inerting spacer 17, arranged inside the casing 4, and included in the dead volume 6. The inerting spacer 17 is porous, that is to say it is made of an open-pored material so that a conduit pierced in the material of the inerting spacer 17 will be in fluid communication with the exterior of the inerting spacer 17, that is to say here with the dead volume 6 of the cell 1 (the inerting spacer 17 being placed in the dead volume of the cell, or itself creates a dead volume by its presence through the empty spaces, that is to say the pores, which it contains). The inerting spacer 17 is included in the dead volume 6, but it can either represent only a fraction of this dead volume 6 (as illustrated in the figures), or occupy the entire dead volume 6. As illustrated in the figures, the inerting spacer 17 consists of a solid part, which is therefore porous in the sense that it has open pores.

[0064] A first step of the inerting process is illustrated in Figure 2. The electrochemical accumulator cell 1 is first drilled at its casing 4 (operation shown diagrammatically by the drill 7). The drilling thus made forms an inerting conduit 5 in the thickness of the casing 4, this inerting conduit connecting the exterior of the cell and its interior.

[0065] The inerting conduit 5 is made opposite the inerting spacer 17 of the cell 1. In the example illustrated, relating to a cylindrical cell 1, the inerting conduit 5 is made in the center of one of the end faces of the cell 1, along the longitudinal axis of the central barrel 3.

[0066] The diameter of the drill bit 7 is chosen so that drilling does not cause damage to the active zones 2, so as not to cause interference with the active zones 2 (and therefore with the potential charge) of the cell 1. In this example, the drill bit 7 has a diameter smaller than the diameter of the inerting spacer 17. The inerting spacer 17 thus makes it possible to preserve the active zones 2.

[0067] The next step of the inerting process, illustrated in Figure 3, consists of introducing an injection cannula 8 into the inerting conduit 5 so that the end of this injection cannula 8 opens into the inerting spacer 17 of the cell 1.

[0068] The injection cannula 8 is connected to an injection device 9 shown schematically by a syringe in the figures. In a manual implementation of the method, in the case of small-scale recycling of electrochemical accumulator cells, this injection device 9 can actually be a syringe handled by an operator. Alternatively, in the context of more automated recycling centers, with higher rates, the injection device 9 may consist of any suitable injection means, such as: pumps, tanks under regulated pressure with injector, or any other means making it possible to inject a liquid in a quantity controlled by the injection cannula 8.

[0069] Optionally, the injection device 9 can be equipped with a liquid pressure measurement, which makes it possible to identify the end of the filling of the dead volume. The injection device 9 is loaded with an inerting liquid 10 adapted to inerting the cell 1 when this liquid comes into contact with the active zones 2.

[0070] In the present example, the inerting liquid 10 may be deionized water, optionally loaded with salts or conductive particles in order to optimize the inerting. Metal particles, carbon fillers, or microfibers may be used to constitute such a filler. For example, such a filler may advantageously consist of conductive carbon black mixed with a solvent such as dimethyl carbonate.

[0071] The relevant characteristic for the choice of a suitable inerting liquid 10 is its electrical conductivity, which must be non-zero but which must be sufficiently low so as not to induce thermal runaway of the cell during inerting. The inerting liquid 10 preferably has an electrical conductivity of between 10 and 500 mS / cm.

[0072] The next step of the inerting process is illustrated in Figure 4. At this step, the injection device 9 injects a predetermined quantity of inerting liquid 10 into the electrochemical accumulator cell 1. The inerting liquid 10 thus injected spreads into the dead volume 6 and then comes into contact with the active zones 2. The inerting liquid puts the anodic and cathodic layers into a controlled short circuit (by the choice of the inerting liquid), thus initiating the inerting.

[0073] The method according to the invention can be implemented by an inerting system, automated or not, which comprises:

[0074] - a drilling device 7 adapted to make an inerting conduit 5 in the casing and in the inerting spacer 17;

[0075] - an injection cannula 8 adapted to be inserted into the inerting conduit 5;

[0076] - an injection device 9 via the injection cannula 5 of an inerting liquid 10.

[0077] The electrochemical accumulator cell 1 is preferably identified beforehand (using an identification means which may include external identification of cell type and size, or even identification by marked reference, by QR Code, etc.), so that:

[0078] - a drilling zone can be defined as being positioned opposite the inerting spacer 17, so that the drilling step actually leads to an inerting conduit 5 opening into the dead volume of the cell 1 via the inerting spacer 17;

[0079] - the predetermined volume of inerting liquid 10 to be injected can be defined, this volume corresponding to a volume suitable for filling the dead volumes sufficiently so that the inerting liquid 10 comes into contact with all of the active zones 2.

[0080] The correspondence between, on the one hand, the identified cell 1 and, on the other hand, the drilling zone as well as the volume of inerting liquid to be injected, can be carried out by any appropriate means of correspondence, for example by a correspondence table or a local or remote database.

[0081] In the example illustrated in Figure 4, taking into account the internal geometry of the cell 1 of this example, the predetermined volume of injected inerting liquid 10 is substantially equal to the dead volume of the cell 1, which here includes the central barrel 3 and an adjacent transverse volume 11. This injected volume allows the inerting liquid 10 to be in contact with an edge of all the layers of the active zones 2. The inerting liquid 10 can thus create limited electrical conduction between the different stacked layers of the active zones 2, taking into account the electrical conductivity characteristics of the inerting liquid 10.

[0082] Figure 5 is a graph showing an example of a concrete implementation of the method according to the invention. The graph in Figure 5 was obtained following measurements made during the inerting of a lithium-ion cell of type 18 650, very common in industry, with deionized water as the inerting liquid.

[0083] The graph in Figure 5 shows the evolution over time in seconds (on the abscissa) of:

[0084] - the voltage across the terminals of the inerted cell (first curve 12 and abscissa on the left of the graph, in V);

[0085] - the temperature of the inerted cell (second curve 13 and abscissa to the right of the graph, in °C).

[0086] Under the initial conditions, at 0 s, the cell temperature is around 20 °C and the voltage across its terminals is 4.2 V (voltage of a charged 18650 cell). In this implementation, the cell is received for recycling with a state of charge of 100%, which corresponds to the most critical case.

[0087] Following the step of piercing the inerting conduit 5, the step of injecting a predetermined volume of inerting liquid via the injection cannula takes place at time t=0.

[0088] The graph shows that around time t=25,000 s, the voltage of cell 1 drops significantly, in parallel with controlled heating of the cell, allowing the evacuation of the energy it contains. This heating reaches a peak at around 130°C, then falls back to the initial temperature.

[0089] After a time T ov corresponding to approximately 8.8 hours, cell 1 reaches a voltage of 0 V. The cell temperature is then in a downward phase. From time t=35,000 s, cell 1 returns to room temperature and is completely discharged.

[0090] The inerting of the cell took place by means of heating which, in this example, reached 130°C at peak, which is a completely acceptable temperature, without risk of thermal runaway, and which also corresponds to a point in time where the cell is already largely discharged.

[0091] Dismantling and recycling operations can then take place in complete safety.

[0092] Optionally, the inerting process may include an additional step of controlling the temperature of the electrochemical accumulator cell after the step of injecting the inerting liquid. In addition, the process may include an end-of-inerting alert step when the temperature of the accumulator cell falls below a predetermined threshold. In the example illustrated in Figure 5, this threshold could be 40°C, which corresponds to an acceptable temperature for the safe handling of the cell 1, and which corresponds to a complete discharge of the accumulator.

[0093] Figure 6 also illustrates the test relating to the graph of Figure 5, and represents the step of injecting inerting liquid into the inerting conduit 5 of the cell 18 650. These cells being cylindrical, the point chosen here to carry out the step of piercing the inerting conduit 5 is the center of the disc constituting one of the end faces of the cell 1, the inerting spacer 17 being located in the center of this disc, on the other side of the wall.

[0094] Figure 6 therefore illustrates the inerting conduit 5, made in the middle of a face of the cell 1, and the injection device 9 with the injection cannula 8 in place to carry out the injection into the inerting spacer 17 of the cell 1, which is located in the central barrel around which the electrode and electrolyte windings are made (as in the example of figures 1 to 4).

[0095] Figure 7 illustrates another example of an electrochemical accumulator cell for the application of the method. In this example, cell 1 is a prismatic cell, and more precisely a lithium-ion accumulator cell with stacked electrodes, of the “stack” type.

[0096] Figure 8 schematically illustrates the classic constitution of such an electrochemical accumulator cell 1 in which the active zones 2 are made up of a stack of electrodes and electrolyte layers, the electrodes being connected to two connection terminals 14.

[0097] These cells 1 are prismatic here and their casing 4 is provided with a vent 15 forming a safety valve adapted to open when the internal pressure of the cell 1 exceeds a pressure threshold. In this example, the vent 15 is located on the upper face, at the level of the central zone between the two connection terminals 14.

[0098] This cell 1 further comprises the inerting spacer 17 arranged opposite the vent 15 of the cell 1. The inerting spacer 17 is here arranged in such a way that it does not disturb the function of the vent, thanks to its porous nature, and / or its positioning.

[0099] This prismatic cell 1 can also benefit from the inerting process thanks to an operation of drilling the inerting conduit which can be carried out in any portion of the envelope 4, as long as this portion opens into the inerting spacer 17. In the present example, the drilling step is carried out in the vent 15, opposite which the inerting spacer 17 is arranged. By drilling in the vent 15, the inerting conduit 5 will open into the inerting spacer 17.

[0100] Alternatively, the inerting spacer 17 can be positioned at other locations in the dead volume 6 of the cell 1, and the drilling will then be carried out accordingly at these locations.

[0101] Figure 9 illustrates the step of introducing the injection cannula 8 into this inerting conduit 5, which was produced by piercing the vent 15 and the inerting spacer 17. The next step then consists of injecting the inerting liquid 10 into the inerting spacer 17 and therefore into the dead volume 6 which is opposite the vent 15.

[0102] As previously, the injected volume of inerting liquid 10 will be chosen to sufficiently fill the dead volume 6 of the cell 1 until it comes into contact with the entire stack constituting the active zones 2.

[0103] Figure 10 illustrates another example of an electrochemical accumulator cell 1 that can benefit from the inerting method according to the invention. The cell 1 of Figure 10 is a prismatic cell consisting of four coils 16, in this example. Such prismatic electrochemical accumulator cells are made of a juxtaposition of flattened coils and contained in the casing 4. These cells 1 are common in high power and high energy density applications, such as batteries for electric vehicles, which will in the future be recycled on a large scale.

[0104] The method preferably comprises a preliminary step of identifying the electrochemical accumulator cell 1 followed by a step of determining, as a function of this identification, a drilling zone opposite the inerting spacer 17 of the cell 1. This identified drilling zone will guarantee a drilling of the casing 4 which will open into this dead volume 6.

[0105] Figure 10 illustrates the drilling operation of the inerting conduit 5. In this example, the identified drilling zone is a central zone, between the two pairs of coils 16. In this example, the cell 1 has previously been identified as being a prismatic cell with four coils 16, and the chosen drilling zone is located at the geometric center of one of the faces of the cell (the bottom face in the view of Figure 10) to therefore be located opposite an inter-coil space.

[0106] In the example of Figure 10, the inerting spacer 17 occupies the entire inter-coil space of the dead volume 6.

[0107] In the example of Figure 10, the drilling operation is carried out directly by the injection cannula 8. The injection cannula 8 is therefore here a perforating injection cannula, which has for this purpose a tapered end adapted to drill the casing 4 and the inerting spacer 17, and is made of a material suitable for such drilling. For example, for a casing 4 and an inerting spacer 17 made of a polymer, the injection cannula 8 is made of a steel of sufficient hardness for drilling the corresponding thickness of these polymers.

[0108] When the drilling operation with the injection cannula 8 is completed, the injection cannula 8 is already in place in the inerting conduit 5 and the inerting liquid injection step can take place.

[0109] Figure 11 illustrates a variant in which the inerting spacer 17 is formed by a small insert part arranged inside the casing 4, delimiting a secure drilling volume against the wall of the casing 4. The drilling tool (whether a drill 7, a perforating injection cannula 8, or any other element suitable for drilling the casing 4) will be able to carry out the drilling and form the inerting conduit 5 with the guarantee that this operation will not damage any active element inside the casing 4. The inerting spacer 17 being a solid part, the operation of drilling it, in addition to protecting the active elements of the cell, makes it possible to create a conduit inside the inerting spacer 17 which is of the exact desired diameter, in particular the diameter corresponding to the injection cannula 8.The injection cannula 8 can thus be inserted, for example, with a mechanical adjustment corresponding to a slight tightening, which provides additional safety and sealing, in particular, for the injection of inerting liquid with a certain pressure.

[0110] The inerting spacer 17 is a solid porous part, so that a conduit pierced in the material of the inerting spacer 17 will be in fluid communication with the exterior of the inerting spacer 17, that is to say here with the dead volume 6 of the cell 1 (the inerting spacer 17 is in fact placed in the dead volume of the cell, or itself creates a dead volume by its presence).

[0111] Thus, after piercing the casing 4 and then the inerting spacer 17, and the formation of the inerting conduit 5 within this inerting spacer 17, the operation of injecting the inerting liquid 10 into the inerting conduit 5 leads to an injection of this inerting liquid 10 into the dead volume 6, via the inerting spacer 17 included in the dead volume.

[0112] External signage on the casing 4 may possibly be provided to identify the position of the inerting spacer 17. Otherwise, the simple identification of the accumulator cell 1 may make it possible to determine the location of the inerting spacer 17.

[0113] Figure 12 illustrates another example of an electrochemical accumulator cell 1 on which the inerting process is implemented. This is a cell 1 also consisting of a flattened coil 16. Figure 12 is a cross-sectional view of the cell 1, schematically illustrating the layers of windings of the coil 16. The step of drilling such a cell 1 is here carried out along its longitudinal direction, that is to say along an axis perpendicular to the plane of Figure 12.

[0114] Such a cell 1 may advantageously have particularly suitable inerting spacers 17, arranged in areas located at the heart of the coil 16. The inerting spacers 17 are adjacent to the windings with the largest radii of curvature, that is to say they are arranged on either side of the space surrounded by the most central winding of the coil 16. The inerting spacers 17 are well located in the dead volume, for this type of cell 1 consisting of a coil 16. The cell 1 is then safely pierced along its longitudinal axis in the inerting spacers 17.

[0115] Figures 13 and 14 illustrate another embodiment of the inerting method in which the step of piercing an electrochemical accumulator cell 1, to form the inerting conduit 5, is carried out by inserting the cell 1 onto an inerting support 19. Figure 13 illustrates the inerting support 19 alone. The inerting support 19 comprises a distribution conduit 20 supplied with inerting liquid 10 by means (not shown) such as a pump associated with a regulator of the injected volume. The distribution conduit 20 is connected to one or more injection cannulas 8 (three in the illustrated example). The injection cannulas 8 are here perforating cannulas, as in the embodiment of Figure 10, formed by rigid punches adapted not only to inject the inerting liquid 10, but also to carry out the piercing of the casing 4 of the cells 1.

[0116] To carry out the step of piercing a cell 1, the cell 1 is inserted onto the inerting support 19, at a delimited location 21 and the injection cannula 8 pierces the casing 4 of the cell 1, under the effect of the cell 1's own weight and possibly supplemented by the application of a driving force.

[0117] Figure 14 illustrates the inerting support 19 on which three cells 1 have been placed, and which have therefore each undergone the step of drilling an inerting conduit 5 through the casing 4 and into the inerting spacer 17 with their placement on the inerting support 19.

[0118] Each cell 1 has an inerting spacer 17 positioned so as to be perforated by one of the perforating injection cannulas 8.

[0119] The inerting support 19 is adapted to the cells 1 to be inerted, which is the case for example during the series recycling of all identical cells, which have been previously identified. The inerting support 19 is thus calibrated with the locations 21, each intended to position the corresponding cell 1 so that the desired drilling zone on the cell 1 comes in line with an injection cannula 8, when the cell is placed on the inerting support 19.

[0120] When introducing a cell 1 into its location 21, the perforating injection cannula 8 pierces the envelope 4 in the chosen piercing zone, which is opposite the inerting spacer 17 of this cell 1.

[0121] The installation of a cell 1 in its location 21 simultaneously carries out the step of piercing the casing 4 and the inerting spacer 17 to create the injection conduit 5, and the operation of introducing the injection cannula 8. The step of injecting the inerting liquid 17 can then take place thanks to the distribution conduit 20.

[0122] Furthermore, optionally, the method can take advantage of the thermal management device possibly associated with the cell 1. Indeed, certain batteries have a thermal management device adapted to cool the battery and controlled by the BMS battery management system. If these means are operational upon receipt of an electrochemical accumulator cell in a recycling center, the inerting method can comprise steps of implementing this thermal management device. The inerting device can comprise a step of controlling the temperature of the cell 1, and of controlling the thermal management device to maintain the temperature of the cell 1 below a maximum temperature.

[0123] Variants of the inerting method can be implemented. For example, the step of drilling an inerting conduit can be carried out by any means allowing the casing 4 to be pierced at the desired location (drill, perforating injection cannula, punch, etc.).

[0124] The predetermined volume of inerting liquid 10 injected may be a volume substantially equal to the total dead volume of the cell 1. Alternatively, depending on the type of cell 1, this predetermined volume may be less than the dead volume of the cell 1, if such a volume of inerting liquid is able to come into contact with all the active zones 2 of the cell 1.

Claims

CLAIMS 1. Electrochemical accumulator cell (1) which comprises an envelope (4) containing active zones (2) and a dead volume (6), characterized in that it comprises an inerting spacer (17) consisting of a solid porous part, arranged inside the envelope (4), and included in the dead volume (6).

2. Cell according to claim 1, characterized in that it is cylindrical in shape, the dead volume (6) comprising a central barrel (3) delimited by the active zones (2), the inerting spacer (17) extending along the longitudinal axis of the central barrel (3).

3. Cell according to claim 1, characterized in that it comprises a plurality of coils (16), the inerting spacer (17) being arranged in an inter-coil zone.

4. Cell according to claim 1, characterized in that it comprises a flattened coil (16), the inerting spacer (17) being arranged along the longitudinal axis of the coil (16), in a zone which is located at the heart of the coil (16), and which is adjacent to the active zones (2) of greater radius of curvature.

5. Cell according to claim 1, characterized in that it comprises a vent (15) opening into the dead volume (6), the inerting spacer (17) being arranged opposite the vent (15).

6. Cell according to one of the preceding claims, characterized in that it comprises external signage on the casing (4) identifying the position of the inerting spacer (17).

7. Inerting system for electrochemical accumulator cell, characterized in that it comprises: - a cell (4) according to one of claims 1 to 6; - a drilling device (7) adapted to form in the envelope (4) of the cell (4) and in the inerting spacer (17) an inerting conduit (5) opening into the inerting spacer (17); - an injection cannula (8) adapted to be inserted into the inerting conduit (5) and to open into the inerting spacer (17), by piercing the inerting spacer (17); - an injection device (9) via the injection cannula (8) of an inerting liquid (10).

8. Inerting system according to claim 7, characterized in that the piercing device and the injection cannula are both formed from a perforating injection cannula.

9. Inerting system according to one of claims 7 or 8, characterized in that it comprises a means of identifying the cell (1) and a means of correspondence between the identified electrochemical accumulator cell and: a drilling zone in the casing, opposite the inerting spacer (17); and a volume of inerting liquid (10) to be injected.

10. Inerting system according to one of claims 7 to 9, characterized in that it comprises an inerting support (19) comprising a distribution conduit (20) for inerting liquid connected to the injection cannula (8) which is fixed on the inerting support (19), and a location (21) for the electrochemical accumulator cell (1) arranged so that, when the electrochemical accumulator cell (1) is inserted into the location (21), the injection cannula (8) opens into the inerting spacer (17), by piercing the inerting spacer (17).

11. Method for inerting an electrochemical accumulator cell (1) according to one of claims 1 to 6, characterized in that it comprises the following steps: - formation of an inerting conduit (5) in the casing (4) by piercing the casing (4) opposite the inerting spacer (17), and by piercing the inerting spacer (17); - introduction of an injection cannula (8) into the inerting conduit (5), the end of the injection cannula (8) opening into the inerting spacer (17); - injection through the injection cannula (8) of a predetermined volume of an inerting liquid (10).

12. Inerting method according to claim 11, characterized in that the predetermined volume of an inerting liquid (10) is a volume substantially equal to the dead volume (6) of the electrochemical accumulator cell (1).

13. Inerting method according to one of the preceding claims, the casing (4) comprising a vent (15), characterized in that the step of forming an inerting conduit (5) is carried out by piercing the vent (15).

14. Inerting method according to one of claims 11 or 12, the electrochemical accumulator cell (1) being cylindrical in shape and the dead volume (6) comprising a central barrel (3) delimited by the active zones (2), characterized in that the step of forming an inerting conduit (5) is carried out by piercing the casing (4) in the longitudinal axis of the central barrel (3).

15. Inerting method according to one of claims 11 or 12, the electrochemical accumulator cell (1) comprising coils (16), characterized in that the step of forming an inerting conduit (5) is carried out by piercing the casing (4) in an inter-coil zone.

16. Inerting method according to one of claims 11 or 12, the electrochemical accumulator cell (1) comprising a flattened coil (16), characterized in that the step of forming an inerting conduit (5) is carried out by piercing the casing (4) along the longitudinal axis of the coil (16), opposite a zone (18) which is located at the heart of the coil (16), and which is adjacent to the active zones (2) of greater radius of curvature.

17. Inerting method according to one of the preceding claims, characterized in that the step of forming an inerting conduit (5) and drilling of the inerting spacer (17), and the step of introducing an injection cannula (8) into the inerting conduit (5) are carried out simultaneously by a perforating injection cannula (8).

18. Inerting method according to one of the preceding claims, characterized in that it comprises a preliminary step of identifying the electrochemical accumulator cell (1) and determining: a drilling zone on the casing (4), this drilling zone being located opposite the inerting spacer (17); and a volume of inerting liquid (10) to be injected.

19. Inerting method according to one of the preceding claims, characterized in that it comprises an additional step of controlling the temperature of the electrochemical accumulator cell (1) after the injection step.

20. Method according to claim 19, characterized in that it comprises a step of alerting the end of inerting when the temperature of the electrochemical accumulator cell (1) falls below a predetermined threshold.

21. Method according to one of the preceding claims, the electrochemical accumulator cell (1) comprising a thermal management device, characterized in that the method comprises a step of controlling the temperature of the electrochemical accumulator cell (1), and of controlling the thermal management device to maintain the temperature of the electrochemical accumulator cell (1) below a maximum temperature.

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