Method for extracting lithium from batteries comprising solid metallic lithium

Abstract

The invention relates to a method (300) for extracting lithium from an assembly of at least one battery cell of a battery comprising solid metallic lithium, such as a lithium-metal-polymer battery, the method (300) comprising an extraction phase (306), the extraction phase comprising the following steps: - positioning (308) the assembly in an orientation in which a first edge of the assembly is located below a second edge of the assembly opposite the first edge, one or more negative electrodes extending from the first edge and one or more positive electrodes extending from the second edge; and - heating (310) the assembly to a processing temperature greater than or equal to the melting temperature of the solid metallic lithium. The invention also relates to an apparatus for implementing the method.

Description

[0001] The present invention relates to a method for extracting lithium from a battery comprising solid metallic lithium.

[0002] The field of the invention is that of batteries based on solid metallic lithium, and in particular that of lithium-metal-polymer batteries, and more particularly that of the recycling of these batteries. Background Art

[0003] Batteries based on solid metallic lithium, such as lithium-metal-polymer Batteries are known. These batteries are increasingly used, for example, in electric vehicles or charging stations. The number of batteries has continued to increase over the years.

[0004] The life of batteries is not infinite, and it seems necessary to recycle these batteries. Now, even at the end of their life, The battery still contains solid metallic lithium, which can be reused in other batteries or other fields and its value cannot be underestimated.

[0005] However, there is currently no technology that allows for the satisfactory recovery of solid metallic lithium from batteries.

[0006] The object of the present invention is to overcome this disadvantage.

[0007] Another object of the present invention is to propose a method for recovering solid metallic lithium from a component of at least one electrical energy storage cell.

[0008] A further object of the present invention is to specify a method for recovering solid metallic lithium from a component of at least one electrical energy storage cell in a simple manner.

[0009] Another object of the present invention is to propose a method for recovering solid metallic lithium from components of at least one electrical energy storage unit in an efficient manner while limiting and managing potential short circuit effects during recovery. Summary of the invention

[0010] The first solution proposed by the present invention

[0011] According to a first solution, the invention makes it possible to achieve at least one of these objectives by a method for extracting lithium from an assembly of at least one battery cell in a battery containing solid metallic lithium, such as a lithium-metal-polymer battery, said method comprising an extraction phase comprising the following steps:

[0012] - positioning the assembly in an orientation in which a first edge of the assembly is located below a second edge of the assembly opposite the first edge, from which one or more negative electrodes extend, and from which one or more positive electrodes extend.

[0013] - Heating the assembly to a temperature greater than or equal to the melting temperature of the solid metallic lithium, this temperature being called the processing temperature.

[0014] The method according to the invention proposes to recover lithium from a battery comprising solid lithium by treating the battery cells constituting said battery individually or collectively.

[0015] Furthermore, the method according to the invention proposes to recover metallic lithium, preferably solid metallic lithium, from the assembly of at least one battery cell in which the lithium is in liquid state by heating the assembly of said battery cell to a processing temperature greater than the melting temperature of solid metallic lithium. Once the metallic lithium melts, the metallic lithium will naturally drain from each battery cell in whole or in part under the action of gravity.

[0016] The process according to the invention therefore allows a simple and not very complicated recovery of solid metallic lithium.

[0017] Furthermore, the method according to the invention proposes a specific orientation for each cell, each cell having a minimum inclination angle so that the first edge from which the negative electrode extends is below the level of the second edge from which the positive electrode extends, opposite to the first edge. This orientation of each cell makes it possible, on the one hand, to promote the flow of the molten lithium out of the cell by gravity and, on the other hand, to avoid contact between the molten lithium and the positive electrode or the current collector of the positive electrode, which could cause an electrical short circuit or an arc, which could cause a fire.

[0018] In this application, an "electrical energy storage cell" refers to a component comprising at least:

[0019] a negative electrode formed of or comprising a solid metallic lithium layer;

[0020] - positive electrode,

[0021] a solid electrolyte, which in particular comprises a lithium salt, which is arranged between the positive electrode and the negative electrode, and

[0022] - A current collector on the positive electrode side.

[0023] In this application, "solid metallic lithium" can include:

[0024] - pure metallic lithium; or

[0025] - a combination of at least one metallic lithium alloy; or

[0026] - A combination of pure metallic lithium and at least one metallic lithium alloy.

[0027] When the "solid metallic lithium" comprises a combination of different forms of lithium (such as those described above) having different melting temperatures, then the heating step heats the components of the battery cell to a processing temperature greater than or equal to:

[0028] - the lowest temperature among said different melting temperatures; and

[0029] -Preferably, the highest temperature among said different melting temperatures.

[0030] According to one non-limiting example embodiment, the processing temperature is greater than or equal to 180.5°C.

[0031] According to an embodiment example, the processing temperature is less than or equal to the maximum temperature, for example 300°C.

[0032] The assembly can include a single or just one battery cell.

[0033] The assembly can include a plurality of battery cells assembled or in particular stacked in an assembly direction. The assembly direction can be perpendicular to a plane formed by each battery cell.

[0034] In particular, the assembly can correspond to a battery in which the battery cells are connected in series.

[0035] According to a preferred embodiment, the positioning step enables vertical positioning of the battery cell assembly, wherein the first edge is positioned downward.

[0036] Thus, the gravity flow of molten lithium out of each battery cell is improved.

[0037] Furthermore, the risk of contact between the molten lithium and the positive electrode or electrodes is reduced or zero.

[0038] Preferably, the step of heating the battery cell assembly can be performed under an inert gas.

[0039] The method according to the invention therefore reduces the risk of accidents, in particular the risk of fire.

[0040] Furthermore, the method according to the invention makes it possible to avoid the formation of polluting compounds resulting from undesired or uncontrolled physicochemical reactions during lithium extraction.

[0041] According to a non-limiting example, the inert gas can be or include any of the following gases: helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn).

[0042] According to another embodiment, the step of heating the battery cell assembly can be performed under vacuum.

[0043] According to a particularly advantageous feature, the method according to the invention can also comprise a step of charging the battery cell assembly prior to the extraction phase, said extraction phase being applied to said charged assembly.

[0044] The fact of charging one or more cells and carrying out the extraction phase on the charged cells makes it possible to increase the lithium extraction yield. In fact, the charging of the cells makes it possible to shift the lithium ions towards the negative electrode, which allows to increase the recoverable amount of lithium.

[0045] Each battery cell can be charged individually, or by charging the battery cell stack.

[0046] According to a particularly advantageous embodiment, the extraction phase can also include a step of compressing the battery cell assembly.

[0047] As a result, molten lithium is forced out of each battery cell, which increases the amount of lithium that is recovered.

[0048] The compression step can be performed continuously throughout the extraction phase. In this case, each cell is subjected to partial or full compression throughout the duration of the extraction phase.

[0049] Alternatively, the compression step can be performed one or more times during the extraction phase alone. In this case, the extraction phase includes the moment when the battery cell assembly is not compressed.

[0050] Advantageously, the compressing step can apply compression to the surface of the assembly by sweeping across the surface of the battery cell assembly from the second edge to the first edge. Thus, the molten lithium is gradually conveyed / directed toward the first edge from which the one or more negative electrodes extend, which increases the amount of lithium recovered and reduces the risk of contact between the lithium and the one or more positive electrodes.

[0051] For example, the compressing step can be performed by passing the battery cell assembly between two rollers.

[0052] According to another example, the compressing step can be performed by pressing the battery cell assembly against the bearing surface via a compression roller.

[0053] Compression can be applied by successive passes, with each pass sweeping across the surface of the battery cell assembly starting from the second edge to the first edge.

[0054] The gap between the compression rollers, or the gap between the compression rollers and the bearing surface, can correspond to the thickness of the battery cell assembly minus the thickness of the one or more solid metallic lithium layers. This allows compression to be applied while the solid lithium remains in the battery cell assembly.

[0055] The gap between two compression rollers or between a compression roller and a bearing surface can be reduced with successive passes so as to still apply compression to the battery cell assembly.

[0056] The passing speed between the compression rollers, or the speed of one compression roller, and more generally the sweeping speed, can be from a few millimeters to tens of millimeters per second.

[0057] Furthermore, the method according to the invention can comprise a step of removing at least one electrical connector (also called “crimp connector”) from at least one battery cell before the extraction phase.

[0058] This makes it possible to facilitate handling of the battery cell assembly.

[0059] Furthermore, the method according to the invention can comprise, before the extraction phase, a step of removing excess material at the level of at least one edge, and in particular each edge, of the battery cell assembly.

[0060] According to another aspect of the invention, a device for extracting lithium from an assembly of at least one battery cell of a battery comprising solid metallic lithium, such as a lithium-metal-polymer battery, is proposed, the device comprising:

[0061] - means for positioning the assembly in an orientation in which a first edge of the assembly, from which one or more negative electrodes extend, and a second edge of the assembly, opposite the first edge, from which one or more positive electrodes extend; and

[0062] - Heating means configured to heat the assembly to a processing temperature greater than or equal to the melting temperature of the solid metallic lithium.

[0063] Typically, the device includes means configured to implement any combination of at least one of the above features, which are not described in detail here for the sake of brevity.

[0064] In particular, the heating device can comprise an oven.

[0065] Advantageously, the oven can be filled with an inert gas, or placed under vacuum.

[0066] The device according to the invention can also comprise means for compressing the battery cell assembly.

[0067] The compression device can comprise at least one roller.

[0068] In particular, the compression device can include a single roller that presses the battery cell assembly against the bearing surface.The bearing surface can be heated to accelerate the temperature increase of the battery cell assembly.

[0069] Alternatively, the compression device can include two rollers between which the battery cell assembly passes.

[0070] Typically, the compression device can be configured to apply continuous compression throughout the extraction phase.

[0071] Alternatively, the compression device can be configured to apply one or more compressions discontinuously over time during the extraction phase. In this case, the extraction phase includes the moment when the battery cell assembly is not subjected to compression.

[0072] Advantageously, the compression step can be configured to apply the compression at a constant or variable value, stepwise from the second edge to the first edge, or by sweeping across the surface of the battery cell assembly. Thus, the molten lithium is gradually conveyed / guided toward the first edge located at a low position, which increases the amount of lithium recovered and reduces the risk of contact between the lithium and one or more positive electrodes.

[0073] In the case of using one or two compression rollers, compression can be applied to the battery cell assembly by successive passes. Each pass applies compression by sweeping across the surface of the battery cell assembly from the second edge to the first edge. At the end of each pass, compression can be stopped by withdrawing the roller or by withdrawing the roller from the bearing surface to return to the second edge to start a new pass.

[0074] The distance between the rollers, or the distance between the compression roller and the bearing surface, can decrease with successive passes, in particular between two successive passes.

[0075] The method according to the present invention can be implemented to process a plurality of battery cell assemblies, in particular a plurality of battery cell assemblies forming a battery pack and being connected together in parallel within the battery pack.

[0076] At least two battery cell assemblies can be aligned side by side without overlapping, for example, in a direction parallel to the first edge.

[0077] In this case, compression can be applied to the at least two battery cell assemblies by one and the same compression device, ie a set of rollers, or one roller cooperating with a bearing surface.

[0078] The second solution proposed by the present invention

[0079] According to a second solution, the invention makes it possible to achieve at least one of these objectives by a method for extracting lithium from an assembly of at least one battery cell in a battery containing solid metallic lithium, such as a lithium-metal-polymer battery, said method comprising an extraction phase comprising the following steps:

[0080] - positioning the assembly in an orientation in which a first edge of the assembly is located above a second edge of the assembly opposite the first edge, from which one or more negative electrodes extend, and from which one or more positive electrodes extend.

[0081] - a step of immersing the battery cell assembly in a liquid that is denser than liquid lithium and electrically insulating; and

[0082] - Heating the assembly to a temperature greater than or equal to the melting temperature of the solid metallic lithium, this temperature being called the processing temperature.

[0083] The method according to the invention proposes to recover lithium from a battery comprising lithium by treating the battery cells constituting said battery individually or collectively.

[0084] Furthermore, the method according to the invention proposes to recover metallic lithium from the assembly of at least one battery cell in which the lithium is in the liquid state, by heating the assembly of said battery cell to a processing temperature which is greater than the melting temperature of the solid metallic lithium. Once melted, the metallic lithium is naturally discharged from each battery cell under the influence of the density difference. Thus, the method according to the invention allows a simple and not very complicated recovery of solid metallic lithium.

[0085] Furthermore, the method according to the invention proposes a specific orientation for each battery cell, each battery cell having a minimum inclination angle so that the first edge from which the negative electrode extends is located above the level of the second edge from which the positive electrode extends, opposite to the first edge. This orientation of each battery cell makes it possible, on the one hand, to promote the flow of molten lithium out of the battery cell by density differences, and on the other hand to avoid contact between the molten lithium and the positive electrode or the collector of the positive electrode, such contact being able to cause an electrical short circuit, which can cause a fire. Furthermore, immersing the battery cell assembly in a liquid makes it possible to improve the dissipation of heat from the battery cell, in particular during a short circuit, and thus significantly limit its impact.

[0086] In this application, an "electrical energy storage cell" refers to a component comprising at least:

[0087] a negative electrode formed from or comprising a solid metallic lithium layer;

[0088] - positive electrode,

[0089] a solid electrolyte, which in particular comprises a lithium salt, which is arranged between the positive electrode and the negative electrode, and

[0090] - A current collector on the positive electrode side.

[0091] In this application, "density" refers to the ratio between the mass density of the liquid in question and the mass density of water.

[0092] In this application, "solid metallic lithium" can include:

[0093] - pure metallic lithium; or

[0094] - a combination of at least one metallic lithium alloy; or

[0095] - A combination of pure metallic lithium and at least one metallic lithium alloy.

[0096] When the "solid metallic lithium" comprises a combination of different forms of lithium (such as those described above) having different melting temperatures, then the heating step heats the components of the battery cell to a processing temperature greater than or equal to:

[0097] - the lowest temperature among said different melting temperatures; or preferably, the lowest temperature among said different melting temperatures, or

[0098] - A combination of different temperatures, for example, or via a temperature gradient extending from a first edge to a second edge.

[0099] According to one non-limiting example embodiment, in the case of using pure metallic lithium, the processing temperature is greater than or equal to 180.5°C.

[0100] According to an embodiment example, the processing temperature is less than or equal to the maximum temperature, for example 300°C.

[0101] The assembly can include a single or just one battery cell.

[0102] The assembly can include a plurality of battery cells assembled or in particular stacked in an assembly direction. The assembly direction can be perpendicular to a plane formed by each battery cell.

[0103] In particular, the assembly can correspond to a battery in which the battery cells are connected in series.

[0104] According to a preferred embodiment, the positioning step enables vertical positioning of the battery cell assembly, wherein the first edge is positioned upward.

[0105] Therefore, the flow of molten lithium out of each battery cell by density difference is improved.

[0106] Furthermore, the risk of contact between the molten lithium and the positive electrode or electrodes is reduced or zero.

[0107] Preferably, the immersing step is performed by completely immersing the battery cell assembly in the liquid.

[0108] The method according to the invention thus reduces the risk of accidents, in particular the risk of fire. Furthermore, the method according to the invention makes it possible to avoid the formation of polluting compounds generated by undesired or uncontrolled physicochemical reactions during the extraction of lithium, in particular by controlling the treatment temperature and the density of the liquid so that only lithium or lithium alloys can be extracted.

[0109] According to a particularly advantageous feature, the method according to the invention can also comprise a step of charging the battery cell assembly prior to the extraction phase, said extraction phase being applied to said charged assembly.

[0110] The fact of charging one or more cells and carrying out the extraction phase on the charged cells makes it possible to increase the lithium extraction yield. In fact, the charging of the cells makes it possible to shift the lithium ions towards the negative electrode, which allows to increase the recoverable amount of lithium.

[0111] Each battery cell can be charged individually, or by charging the battery cell stack.

[0112] According to a particularly advantageous embodiment, the extraction phase can also include a step of compressing the battery cell assembly.

[0113] As a result, molten lithium is forced out of each battery cell, which increases the amount of lithium recovered and improves the kinetics of the process.

[0114] The compression step can be performed continuously throughout the extraction phase. In this case, each cell is subjected to partial or full compression throughout the duration of the extraction phase.

[0115] Alternatively, the compression step can be performed one or more times during the extraction phase alone. In this case, the extraction phase includes the moment when the battery cell assembly is not compressed.

[0116] Advantageously, the compressing step can apply compression to the surface of the battery cell assembly by sweeping across the surface of the battery cell assembly from the second edge to the first edge. Thus, the molten lithium is gradually conveyed / directed toward the first edge from which the one or more negative electrodes extend, which increases the amount of lithium recovered and reduces the risk of contact between the lithium or lithium alloy and the one or more positive electrodes.

[0117] For example, the compressing step can be performed by passing the battery cell assembly between two rollers.

[0118] According to another example, the compressing step can be performed by pressing the battery cell assembly against the bearing surface via a compression roller.

[0119] The compression step can be applied by successive passes, each pass sweeping across the surface of the battery cell assembly starting from the second edge to the first edge.

[0120] The gap between the compression rollers, or the gap between the compression rollers and the bearing surface, can correspond to the thickness of the battery cell assembly minus the thickness of the one or more solid metallic lithium layers. This allows compression to be applied while the solid lithium remains in the battery cell assembly.

[0121] The gap between two compression rollers or between a compression roller and a bearing surface (also referred to as a platen) can be reduced with successive passes so as to still apply compression to the battery cell assembly.

[0122] The passing speed between the compression rollers, or the speed of the compression rollers cooperating with the press plate, and more generally the sweeping speed, can be from a few millimeters to tens of millimeters per second.

[0123] Furthermore, the method according to the invention can comprise a step of removing at least one electrical connector (also called “crimp connector”) from the battery cell before the extraction phase.

[0124] This makes it possible to facilitate handling of the battery cell assembly.

[0125] Furthermore, the method according to the invention can comprise, before the extraction phase, a step of removing excess material at the level of at least one edge, and in particular each edge, of the battery cell assembly.

[0126] According to another aspect of the same invention, a device for extracting lithium from an assembly of at least one battery cell comprising solid metallic lithium, such as a lithium-metal-polymer battery, is proposed, the device comprising:

[0127] - means for positioning the assembly in an orientation in which a first edge of the assembly, from which one or more negative electrodes extend, is located above a second edge of the assembly opposite the first edge, from which one or more positive electrodes extend;

[0128] - an oven filled with a liquid that is denser than liquid lithium and electrically insulating; and

[0129] - Heating means configured to heat the assembly to a processing temperature greater than or equal to the melting temperature of the solid metallic lithium.

[0130] Generally, the device includes means configured to implement any combination of at least one of the above features, which are not described in detail here for the sake of brevity.

[0131] The liquid can be a natural or synthetic oil, which includes the following physicochemical properties:

[0132] · Hydrophobic and non-reactive with respect to lithium,

[0133] Electrical insulation,

[0134] Its density is greater than that of lithium,

[0135] Thermally stable above the melting temperature of lithium (i.e., 180.5°C),

[0136] · Highest possible flash point and auto-ignition point.

[0137] The device according to the invention can also comprise means for compressing the battery cell assembly.

[0138] The compression device can comprise at least one roller.

[0139] In particular, the compression device can include a single roller that presses the battery cell assembly against the bearing surface.The bearing surface can be heated to accelerate the temperature increase of the battery cell assembly.

[0140] Alternatively, the compression device can include two rollers between which the battery cell assembly passes.

[0141] Typically, the compressing step can be configured to apply continuous compression throughout the extraction phase.

[0142] Alternatively, the compression device can be configured to apply one or more compressions discontinuously over time during the extraction phase. In this case, the extraction phase includes the moment when the battery cell assembly is not subjected to compression.

[0143] Advantageously, the compression device can be configured to apply the compression at a constant or variable value, stepwise from the second edge to the first edge or by sweeping across the surface of the battery cell assembly. Thus, the molten lithium is gradually conveyed / guided towards the first edge located at a low position, which increases the amount of lithium recovered and reduces the risk of contact between the lithium and one or more positive electrodes.

[0144] In the case of using one or two compression rollers, compression can be applied to the battery cell assembly by successive passes. Each pass applies compression by sweeping across the surface of the battery cell assembly from the second edge to the first edge. At the end of each pass, compression can be stopped by withdrawing the roller or by withdrawing the roller from the bearing surface to return to the second edge to start a new pass.

[0145] The distance between the rollers, or the distance between the compression roller and the bearing surface, can decrease with successive passes, and in particular between two successive passes.

[0146] The method according to the present invention can be implemented to process a plurality of battery cell assemblies, in particular a plurality of battery cell assemblies forming a battery pack and being connected together in parallel within the battery pack.

[0147] At least two battery cell assemblies can be aligned side by side without overlapping, for example, in a direction parallel to the first edge.

[0148] In this case, compression can be applied to the at least two battery cell assemblies by one and the same compression device, ie a set of rollers, or one roller cooperating with a bearing surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0149] Other advantages and features will emerge from a reading of the detailed description of non-limiting embodiments and of the accompanying drawings, in which:

[0150] - Figure 1 is a schematic diagram of a non-limiting embodiment example of a battery cell within the meaning of the present invention;

[0151] - Figure 2 is a schematic diagram of a non-limiting embodiment example of a battery cell assembly within the meaning of the present invention;

[0152] - Figure 3 is a first non-limiting example of the method according to the invention following the first proposed solution.

[0153] Schematic diagram of an example of a controllable embodiment;

[0154] - Figure 4 is a second non-limiting example of the method according to the invention following the proposed second solution.

[0155] Schematic diagrams of examples of conventional embodiments; and

[0156] - Figure 5 is a non-limiting example of a device according to the invention following the first solution proposed.

[0157] Schematic diagram of an example of a controllable embodiment;

[0158] - Figure 6 is a first non-limiting example of the method according to the invention following the proposed second solution.

[0159] Schematic diagram of an example of a controllable embodiment;

[0160] - Figure 7 is a second non-limiting example of the method according to the invention following the proposed second solution.

[0161] Schematic diagram of an example of a controllable embodiment;

[0162] - Figure 8is a schematic diagram of a non-limiting embodiment example of a device according to the invention following the proposed second solution.

[0163] It should be understood that the embodiments described herein are by no means limiting. If the selection of features is sufficient to confer a technical advantage or to distinguish the invention from the state of the prior art, it is possible to envisage variations of the invention comprising only a selection of features described below, the selection of which is independent of the other features described. The selection comprises at least one preferably functional feature without structural details or with only a portion of the structural details, as long as the portion of the structural details alone is sufficient to confer a technical advantage or to distinguish the invention from the prior art.

[0164] In the drawings, elements common to several figures are provided with the same reference numerals.

[0165] In this application, "density" refers to the ratio between the mass density of the liquid in question and the mass density of water.

[0166] The liquid can be a natural or synthetic oil, which includes the following physicochemical properties:

[0167] · Hydrophobic and non-reactive with respect to lithium,

[0168] Electrical insulation,

[0169] Its density is greater than that of lithium,

[0170] Thermally stable above the melting temperature of lithium (i.e., 180.5°C),

[0171] · Highest possible flash point and auto-ignition point.

[0172] Figure 1 is a schematic diagram of a non-limiting embodiment example of a battery cell within the meaning of the invention, regardless of which of the two proposed solutions is implemented.

[0173] Figure 1 The battery cell 100 shown in comprises a negative electrode 102 which is formed of or comprises a solid metallic lithium layer.

[0174] The battery cell 100 also includes a positive electrode 104. The positive electrode 104 is typically formed of layers of a composite material based on a polymer and an active material.

[0175] A solid electrolyte layer 106 is arranged between the negative electrode 102 and the positive electrode 104. The solid electrolyte layer 106 can include a lithium salt, for example.

[0176] The battery cell 100 also includes a current collector 108 on one side of the positive electrode 104. The current collector 108 is typically made of aluminum.

[0177] Conventionally, the negative electrode 102 of the battery cell 100 extends beyond the other elements of the battery cell 100 on one side of the first edge 110 of the battery cell 100, here to the right side of the figure; and the positive electrode 104 of the battery cell 100 and / or the current collector 108 (the current collector 108 is connected to the positive electrode 104) extends beyond the other elements of the battery cell 100 on the side of the second edge 112 opposite to the first edge 110. In the example shown, only the current collector 108 extends beyond the assembly 100 on the second edge 112, here to the left side of the figure. In other examples, the extension may involve only the positive electrode 104, or may also involve the positive electrode 104 and the current collector 108.

[0178] certainly, Figure 1 The battery cell 100 shown in is a very simplified version of an implementation, given by way of non-limiting illustration. A battery cell within the meaning of the invention can comprise layers other than those shown, or more layers, or layers whose composition differs from the composition given here as non-limiting examples.

[0179] Figure 2 is a schematic diagram of a non-limiting embodiment example of a battery cell assembly within the meaning of the invention, regardless of which of the two proposed solutions is implemented.

[0180] Figure 2 The battery cell assembly 200 shown in FIG. 2 includes one or more battery cells within the meaning of the present invention.

[0181] In particular, the battery cell assembly 200 includes a plurality of identical battery cells 1001-100 n , these battery cells are arranged perpendicular to each battery cell 100 i The layers are assembled in the direction 202 of the layer plane.

[0182] Each battery cell 100 i Can be used with Figure 1 The battery cells 100 are the same.

[0183] In addition, when i<n, two adjacent battery cells 100 i -100 i+1 A positive electrode 204 is arranged between i and the current collector 206 connected thereto i .

[0184] Example of embodiment according to the first proposed solution

[0185] Figure 3 is a schematic diagram of a first non-limiting embodiment example of the method according to the invention following the proposed first solution;

[0186] Figure 3 The method 300 shown in FIG. 3 comprises a first optional step 302 during which electrical connectors of the battery cell assembly, and in particular current concentrators (also referred to as “crimp connectors”), are removed.

[0187] During an optional step 304 , excess material, in particular solid metallic lithium, is removed at the level of each side edge of the battery cell assembly.

[0188] The method 300 then includes a stage 306 of extracting metallic lithium from the battery cell.

[0189] The extraction stage 306 includes a step 308 of positioning the battery cell assembly in an orientation in which a first edge from which one or more negative electrodes extend is located at a lower level than a second edge from which one or more positive electrodes and current collectors extend. In particular, step 308 positions the battery cell assembly in a vertical orientation, i.e., parallel to the gravity vector, with the one or more negative electrodes extending downward from its edge. Preferably, but by no means limiting, the battery cell assembly remains in this orientation throughout the extraction stage 306.

[0190] The extraction phase 306 also includes a step 310 of heating the battery cell assembly to a processing temperature greater than or equal to the melting temperature of the solid metallic lithium present in the battery cell assembly, for example, a temperature of 180.5° C. This temperature will cause the solid metallic lithium to melt and be extracted from each battery cell by natural drainage under the action of gravity. Preferably, but by no means limiting, the battery cell assembly is maintained at this temperature throughout the extraction phase 306.

[0191] Advantageously, the heating step is carried out in a closed enclosure filled with an inert gas.

[0192] The extraction phase 306 can also include an optional step 312 of compressing the battery cell assembly to flush the molten lithium out of each battery cell. The compression can be performed continuously in all or part of the extraction phase 306. Alternatively, the compression step 312 can be repeated multiple times discontinuously during the extraction phase 306. Preferably, the compression step 312 starts from the second edge from which the one or more positive electrodes extend and moves toward the first edge from which the one or more negative electrodes extend, stepwise or by sweeping across the surface of the battery cell assembly to apply compression.

[0193] Figure 4 is a schematic diagram of another non-limiting embodiment example of the method according to the invention following the first solution proposed.

[0194] Figure 4 The method 400 shown in FIG. 4 includes Figure 3 All steps of method 300.

[0195] Prior to the step of method 300 , method 400 further includes a step 402 of recharging the processed battery cell.

[0196] Each battery cell can be partially or fully recharged.

[0197] The fact of charging each cell makes it possible to increase the amount of lithium available for extraction, since recharging causes the lithium ions to migrate to the negative electrode of the cell.

[0198] Figure 5 is a schematic diagram of a non-limiting embodiment example of a device according to the invention following the first solution proposed.

[0199] Figure 5 The device 500 shown in FIG. 1 can be used to implement the method according to the invention, and in particular Figure 3 and 4 Methods 300 and 400 in.

[0200] The device 500 enables the removal of a charge from a battery cell (e.g. Figure 1 battery cell 100) or from a battery cell assembly (such as Figure 2 Extract and recover some or all of the lithium from component 200).

[0201] The apparatus 500 includes an oven 502 filled with an inert gas or placed under vacuum, which is configured to heat the battery cell to a processing temperature greater than or equal to the melting temperature of solid metallic lithium present in the battery cell, for example 180.5°C or 181°C.

[0202] The device 500 includes a pair of clamps 504 for holding the battery cell 100 or battery cell assembly 200 in a vertical or at least inclined position in which the first edge 110 is positioned below the level of the second edge 112. Each clamp 504 is movably mounted on a vertical rail 506 in order to vertically displace the battery cell or battery cell assembly 200.

[0203] The apparatus 500 further includes a pair of rollers 508, the gap between which corresponds to the thickness of the battery cell 100 or the battery cell assembly 200 minus the thickness of the metallic lithium solid layer. The pair of rollers is positioned so that when the clamp 504 is displaced upward, the battery cell 100, the battery cell assembly 200, respectively, passes between the rollers 508 starting from the second edge 112. Thus, the rollers start from the second edge 112 and move toward the first edge 110 to gradually apply compression to the battery cell 100, the battery cell assembly 200, respectively.

[0204] The apparatus also includes a container 510 for recovering the molten metallic lithium that flows out of each battery cell under gravity. The container 510 must be inert with respect to lithium.

[0205] Example of embodiment according to the proposed second solution

[0206] Figure 6 is a schematic diagram of a non-limiting embodiment example of the method according to the invention following the proposed second solution.

[0207] Figure 6 The method 600 shown in 600 comprises a first optional step 602 during which the electrical connectors, also referred to as “crimp connectors”, of each battery cell are removed.

[0208] During optional step 604 , excess material at the level of each side edge of the battery cell assembly is removed.

[0209] The method 600 then includes a stage 606 of extracting metallic lithium from the battery cell.

[0210] The extraction stage 606 includes a step 608 of positioning the battery cell assembly in an orientation in which the first edge 110 from which the one or more negative electrodes 102 extend is located at a higher level in the vertical direction than the second edge 112 from which the one or more positive electrodes 104 and the current collector extend. In particular, step 608 positions the battery cell assembly in a vertical direction, i.e., parallel to the gravity vector, with the one or more negative electrodes 102 extending downward from its edge. Preferably, but by no means limiting, the battery cell assembly remains in this orientation throughout the extraction stage 606.

[0211] The extraction phase 606 includes a step 609 of immersing the battery cell assembly in a liquid 850 (see Figure 8 ). For example, in Figure 8 In the illustrated embodiment, the liquid 850 is a natural or synthetic oil, such as paraffin oil, which includes the following physicochemical properties:

[0212] · Hydrophobic and non-reactive with respect to lithium,

[0213] Electrical insulation,

[0214] Its density is greater than that of lithium,

[0215] Thermally stable above the melting temperature of lithium (i.e., 180.5°C), and

[0216] The flash point and autoignition point are as high as possible, for example, above 600°C, and at least higher than the processing temperature of the battery cell.

[0217] The immersing step 609 is performed by immersing the battery cell assembly 200 in the liquid 850 so that the liquid 850 completely covers the battery cell assembly 200 .

[0218] This immersion step 609 is particularly advantageous for promoting a significant heat exchange between the battery cell and the liquid 850 , which limits the risk of overheating of the battery cell and the removal of the heat generated during a short circuit and improves the heating dynamics.

[0219] The extraction phase 606 also includes a step 610 of heating the battery cell assembly to a processing temperature greater than or equal to the melting temperature of the solid metallic lithium present in the battery cell assembly, for example a temperature of 180.5°C. In the embodiment presented, the liquid 850 is heated by an oven and transfers heat to the battery cell assembly. Once above the melting temperature of lithium, this temperature causes the solid metallic lithium to melt and be extracted from each battery cell by natural drainage under the action of gravity. Preferably, but by no means limiting, the battery cell assembly is maintained at this temperature throughout the extraction phase 606. The processing temperature must not exceed the degradation temperature of the liquid 850 (specific to each liquid 850), beyond which the liquid 850 degrades. In other words, the liquid 850 changes properties when the threshold temperature is exceeded so that the above characteristics are no longer met. Ideally, the degradation temperature of the liquid must be above +40°C (and, for example, at +60°C to +60°C) relative to the melting temperature of lithium.

[0220] Thus, the method of extracting lithium from a battery allows the effects of a short circuit potential to be limited by flowing lithium through a first edge 110 from which one or more negative electrodes 102 extend, and allows short circuits to be controlled by immersing the battery cell assembly in a liquid that does not react with lithium and improving heat dissipation from the battery cell assembly (particularly during a short circuit).

[0221] The extraction phase 606 can also include an optional step 612 of compressing the battery cell assembly to accelerate the extraction of molten lithium out of each battery cell. Compression can be performed continuously in all or part of the extraction phase 606. Alternatively, the compression step 612 can be repeated multiple times discontinuously during the extraction phase 606. Preferably, the compression step 612 starts from the second edge 112 from which the one or more positive electrodes 104 extend and applies compression moving toward the first edge 110 from which the one or more negative electrodes 102 extend, stepwise or by sweeping across the surface of the battery cell assembly.

[0222] Figure 7 is a schematic diagram of another non-limiting embodiment example of the method according to the invention following the proposed second solution.

[0223] Figure 7 The method 700 shown in FIG. 7 includes Figure 6 All steps of method 600.

[0224] Prior to the step of method 600 , method 700 further includes a step 702 of recharging the processed one or more battery cells.

[0225] Each battery cell can be partially or fully recharged.

[0226] The fact of charging each cell makes it possible to increase the amount of lithium available for extraction, since recharging causes the migration of lithium ions to the negative electrode of the cell, which improves the amount of lithium extracted and the kinetics of the operation.

[0227] Figure 8 is a schematic diagram of a non-limiting embodiment example of a device according to the invention following the proposed second solution.

[0228] Figure 8 The device 800 shown in FIG. 8 can be used to implement the method according to the present invention, and in particular Figure 6 and 7 Methods 600 and 700 in.

[0229] The device 800 enables the removal of a charge from a battery cell (e.g. Figure 1 battery cell 100) or from a battery cell assembly (such as Figure 2 Extract and recover some or all of the lithium from component 200).

[0230] The apparatus 800 includes an oven 802 filled with a liquid 850 configured to heat the battery cells to a processing temperature greater than or equal to the melting temperature of solid metallic lithium present in the battery cells, such as 180.5° C. or 181° C. In the embodiment presented, the liquid 850 is heated by the oven 802 and transfers heat to the battery cell assembly.

[0231] The device 800 includes a pair of clamps 804 for holding the battery cell 100 or battery cell assembly 200 in a vertical or at least inclined position in which the first edge 110 is positioned above the level of the second edge 112. Each clamp 804 is movably mounted on a vertical rail 806 in order to vertically displace the battery cell 100 or battery cell assembly 200.

[0232] The liquid 850 completely covers the battery cell assembly such that the first edge 110 is located below the level of the liquid 850 .

[0233] The apparatus 800 also includes a pair of rollers 808, the gap between which corresponds to the thickness of the battery cell 100 or the battery cell assembly 200 minus the thickness of one or more solid layers of metallic lithium. The pair of rollers is positioned so that when the jaws 804 are displaced upward, the battery cell 100, the battery cell assembly 200, respectively, passes between the rollers 808 starting from the second edge 112. Thus, the rollers start from the second edge 112 and move toward the first edge 110 to gradually apply compression to the battery cell 100, the battery cell assembly 200, respectively.

[0234] Of course, the present invention is not limited to the examples described in detail above.

[0235] For example, the composition of a battery cell comprising solid metallic lithium can differ from Figure 1 The composition indicated in .

[0236] Furthermore, the device according to the invention can comprise different Figure 5 and Figure 7 Such devices may include those shown in, for example, means for severing an electrical connector from a battery cell, means for severing excess from one or each edge.

[0237] For example, the clamps 504 and 804, respectively, can be fixed, and the rollers 508 and 808, respectively, can be movable and can compress the battery cell assembly from the top down, or from the bottom up, according to the present embodiment.

[0238] Additionally, a single oven and multiple pairs of rollers dedicated to one battery cell or battery cell assembly may be used.

[0239] A pair of rollers can be operated to process several adjacent battery cell assemblies simultaneously.

[0240] As an example, step 609 can be performed by immersing the battery cell 100 or the battery cell assembly 200 in the liquid 850 , or by filling the oven 802 with the liquid 850 such that the liquid 850 covers the battery cell assembly 200 , the battery cell 100 , respectively.

[0241] It should be noted that the orientation of the first edge 110 of the assembly from which the one or more negative electrodes 102 extend is a function of the density of the fluid in which the battery cell 100 or battery cell assembly 200 is immersed. In the case where the fluid is a gas, which is covered by the first solution proposed by the present invention, the first edge 110 will be located below the second edge 112 from which the one or more positive electrodes 104 extend, because the density of the gas is lower than that of lithium. In the case where the fluid is a liquid with a density greater than that of lithium, which is covered by the second solution proposed by the present invention, the first edge 110 will be located above the second edge 112.

[0242] In the case where the fluid is a liquid with a density less than lithium, then the orientation of the first edge 110 will be below the second edge 112 as shown in the first embodiment.

[0243] In addition, the compression direction of the battery cell 100 by rollers 508 and 808, respectively, is more conducive to compressing the battery cell from the second edge 112 to the first edge 110. Therefore, depending on the density of the fluid, the compression direction is not consistent, such as Figure 5 and Figure 8 This can be seen in the example shown in .

[0244] The first edge 110 can be characterized in that it defines a side through which the lithium must flow once in a liquid state.

Claims

1. A method for extracting lithium from an assembly (200) of at least one battery cell (100) of a battery comprising solid metallic lithium, the method comprising an extraction phase, the extraction phase comprising the following steps: - positioning the assembly (200) in an orientation in which a first edge (110) of the assembly (200) is located below a second edge (112) of the assembly (200) opposite the first edge (110), from which one or more negative electrodes (102) extend, and from which one or more positive electrodes (104) extend; and - heating the assembly to a temperature greater than or equal to the melting temperature of the solid metallic lithium, This temperature is called the processing temperature.

2. The method according to claim 1, characterized in that The step of positioning performs vertical positioning of the battery cell assembly (200), wherein the first edge (110) is located at the bottom.

3. The method according to claim 1 or 2, characterized in that: The step of heating the assembly (200) of battery cells is performed under an inert gas.

4. The method according to any one of claims 1 or 2, characterized in that The step of heating the assembly (200) of battery cells is performed under vacuum.

5. The method according to claim 1 or 2, characterized in that: It also comprises a step of charging the assembly (200) of battery cells before an extraction phase, said extraction phase being applied to the charged assembly (200).

6. The method according to claim 1 or 2, characterized in that: The extraction phase also comprises a step of compressing the assembly (200) of battery cells.

7. The method according to claim 6, characterized in that The step of compressing applies compression to the surface of the component (200) by sweeping across the surface of the component (200) from the second edge (112) to the first edge (110).

8. The method according to claim 1 or 2, characterized in that: It comprises a step of removing at least one electrical connector from at least one battery cell (100) prior to the extraction phase.

9. The method according to claim 1, characterized in that: The battery is a lithium-metal-polymer battery.

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