METHOD FOR THE EXTRACTION OF LITHIUM FROM AN ELECTRIC BATTERY COMPRISING SOLID METALLIC LITHIUM

Abstract

A method for the extraction of lithium from an assembly of at least one cell of an electric battery including solid metallic lithium, such as a Lithium-Metal-Polymer battery, the method having an extraction phase including the following steps: positioning the assembly in an orientation in which a first edge of the assembly from which extend(s) one or more negative electrode or electrodes is located below a second edge of the assembly, opposite the first edge, and from which extend(s) one or more positive electrode or electrodes; and heating the assembly to a treatment temperature greater than or equal to the melting temperature of the solid metallic lithium. An installation implementing such a method is also provided.

Claims

1. A method for the extraction of lithium from an assembly of at least one cell of an electric battery including solid metallic lithium, such as a Lithium-Metal-Polymer battery, said method having an extraction phase comprising the following steps: positioning said assembly in an orientation in which a first edge of said assembly from which extend(s) one or more negative electrode or electrodes is located below a second edge of said assembly, opposite said first edge, and from which extend(s) one or more positive electrode(s); and heating said assembly to a temperature, called treatment temperature, greater than or equal to the melting temperature of said solid metallic lithium.

2. The method according to claim 1, characterized in that the positioning step carries out a vertical positioning of the assembly of cell(s), in which the first edge is located downwards.

3. The method according to claim 1, characterized in that the step of heating the assembly of cell(s) is carried out under inert gas.

4. The method according to claim 1, characterized in that the step of heating the assembly of cell(s) is carried out under vacuum.

5. The method according to claim 1, characterized in that it also comprises, before the extraction phase, a step of electrical charging of the assembly of cell(s), said extraction phase being applied to said charged assembly.

6. The method according to claim 1, characterized in that the extraction phase also comprises a step of compression of the assembly of cell(s).

7. The method according to claim 6, characterized in that the compression step applies a compression to the surface of the assembly by sweeping the surface of the assembly from the second edge to the first edge.

8. The method according to claim 1, characterized in that it comprises, before the extraction phase, a step of removal of at least one electrical connector from at least one cell.

9. An installation for the extraction of lithium from an assembly of at least one cell of an electric battery including solid metallic lithium, such as a Lithium-Metal-Polymer battery, said installation comprising: a means for positioning said assembly in an orientation in which a first edge of said assembly from which extend(s) one or more negative electrode or electrodes is located below a second edge of said assembly, opposite said first edge, and from which extend(s) one or more positive electrode or electrodes; and heating means configured to heat said assembly to a treatment temperature greater than or equal to the melting temperature of said solid metallic lithium.

10. The installation according to claim 9, characterized in that the heating means comprises an oven filled with inert gas.

11. The installation according claim 9, characterized in that it comprises a compression means of the assembly of cell(s).

12. The installation according to claim 11, characterized in that the compression means comprises two rollers between which the assembly of cell(s) is passed.

Description

DESCRIPTION OF THE FIGURES AND EMBODIMENTS

[0147] Other advantages and characteristics will become apparent on examination of the detailed description of embodiments which are in no way limitative, and from the attached drawings in which:

[0148] FIG. 1 is a diagrammatic representation of a non-limitative embodiment example of a cell within the meaning of the present invention;

[0149] FIG. 2 is a diagrammatic representation of a non-limitative embodiment example of an assembly of cells within the meaning of the present invention;

[0150] FIG. 3 is a diagrammatic representation of a first non-limitative embodiment example of a method according to the invention, conforming to the first solution proposed;

[0151] FIG. 4 is a diagrammatic representation of a second non-limitative embodiment example of a method according to the invention, conforming to the first solution proposed; and

[0152] FIG. 5 is a diagrammatic representation of a non-limitative embodiment example of an installation according to the invention, conforming to the first solution proposed;

[0153] FIG. 6 is a diagrammatic representation of a first non-limitative embodiment example of a method according to the invention, conforming to the second solution proposed;

[0154] FIG. 7 is a diagrammatic representation of a second non-limitative embodiment example of a method according to the invention, conforming to the second solution proposed;

[0155] FIG. 8 is a diagrammatic representation of a non-limitative embodiment example of an installation according to the invention, conforming to the second solution proposed.

[0156] It is well understood that the embodiments that will be described hereinafter are in no way limitative. Variants of the invention can be envisaged comprising only a selection of the characteristics described hereinafter, in isolation from the other characteristics described, if this selection of characteristics is sufficient to confer a technical advantage or to differentiate the invention with respect to the state of the prior art. This selection comprises at least one, preferably functional, characteristic without structural details, or with only a part of the structural details if this part alone is sufficient to confer a technical advantage or to differentiate the invention with respect to the state of the prior art.

[0157] In the figures, elements common to several figures retain the same reference.

[0158] In the present application, by “density” is meant the ratio between the mass density of the liquid in question and the mass density of water.

[0159] The liquid can be a natural or synthetic oil, comprising the following physico-chemical properties:

[0160] hydrophobic and non-reactive with respect to lithium,

[0161] electrically insulating,

[0162] having a density greater than that of lithium,

[0163] thermally stable beyond the melting temperature of lithium, i.e. 180.5° C.,

[0164] a flash point, as well as a self-ignition point, as high as possible.

[0165] FIG. 1 is a diagrammatic representation of a non-limitative embodiment example of a cell within the meaning of the present invention, regardless of which of the two proposed solutions is implemented.

[0166] The cell 100, shown in FIG. 1, comprises a negative electrode 102 formed by, or comprising, a layer of solid metallic lithium.

[0167] The cell 100 also comprises a positive electrode 104. The positive electrode 104 is generally formed by a layer of composite based on polymer and active material.

[0168] A layer 106 of solid electrolyte is arranged between the negative electrode 102 and the positive electrode 104. This layer of solid electrolyte 106 can for example comprise lithium salt.

[0169] The cell 100 also comprises a current collector 108 on the side of the positive electrode 104. The current collector 108 is generally produced from aluminium.

[0170] Conventionally, the negative electrode 102 of the cell 100 extends beyond the other elements of the cell 100 on the side of a first edge 110 of the cell 100, here to the right of the figure; and the positive electrode 104 and/or the collector 108 of the cell 100 (said collector 108 is connected to the positive electrode 104) extend(s) beyond the other elements of the cell 100 on the side of a second edge 112, opposite the first edge 110. In the example shown, only the collector 108 extends beyond the assembly 100 on the second edge 112 thereof, here to the left of the figure. In other examples, the extension may involve only the positive electrode 104, or also the positive electrode 104 and the collector 108.

[0171] Of course, the cell 100 shown in FIG. 1 is a very simplified version of realization, given by way of non-limitative illustration. The cell within the meaning of the present invention can comprise layers other than those indicated, or more layers, or layers the composition of which is different from the composition given here by way of non-limitative example.

[0172] FIG. 2 is a diagrammatic representation of a non-limitative embodiment example of an assembly of cell(s) within the meaning of the present invention, regardless of which of the two proposed solutions is implemented.

[0173] The cell assembly 200, shown in FIG. 2, comprises one or more cells within the meaning of the present invention.

[0174] In particular, the cell assembly 200 comprises several identical cells 100.sub.1-100.sub.n, assembled in a direction 202 perpendicular to the plane of the layers of each cell 100.sub.i.

[0175] Each cell 100, may be identical to the cell 100 in FIG. 1.

[0176] In addition, between two adjacent cells 100.sub.i-100.sub.i+1, with i<n, are arranged a positive electrode 204.sub.i and a current collector 206.sub.i which is connected thereto.

Embodiment Examples according to the First Solution Proposed

[0177] FIG. 3 is a diagrammatic representation of a first non-limitative embodiment example of a method according to the invention, conforming to the first solution proposed;

[0178] The method 300, shown in FIG. 3, comprises a first, optional, step 302 during which the electrical connectors, and in particular the current concentrators, also known as “crimp connectors”, of the assembly of cell(s) are removed.

[0179] During an optional step 304, excess material, in particular solid metallic lithium, at the level of each side edge of the assembly of cell(s) is removed.

[0180] Then, the method 300 comprises a phase 306 of extraction of the metallic lithium from the cells.

[0181] The extraction phase 306 comprises a step 308 of positioning the assembly of cell(s) in an orientation in which the first edge from which extend(s) the negative electrode or electrodes is located at a lower level than the second edge from which extend(s) the positive electrode or electrodes and the collectors. In particular, the step 308 positions the assembly of cell(s) in a vertical orientation, i.e. parallel to the gravity vector, with the edge from which extend(s) the negative electrode or electrodes, downwards. Preferentially, but in no way limitatively, the assembly of cell(s) is held in this orientation throughout the entire extraction phase 306.

[0182] The extraction phase 306 also comprises a step 310 of heating the assembly of cell(s) to a treatment temperature greater than or equal to the melting temperature of the solid metallic lithium present in the assembly of cell(s), for example a temperature of 180.5° C. This temperature will cause the melting of the solid metallic lithium and extraction thereof from each cell by natural drainage under the effect of gravity. Preferentially, but in no way limitatively, the assembly of cell(s) is maintained at this temperature throughout the entire extraction phase 306.

[0183] Advantageously, the heating step is carried out in a closed enclosure filled with inert gas.

[0184] The extraction phase 306 can also comprise an optional step 312 of compressing the assembly of cell(s) so as to flush the molten lithium out of each cell. The compression can be carried out continuously over all or part of the extraction phase 306. Alternatively, the compression step 312 can be reiterated discontinuously, several times during the extraction phase 306. Preferentially, the compression step 312 carries out an application of the compression, progressively or by sweeping over the surface of the assembly of cell(s), starting from the second edge from which extend(s) the positive electrode or electrodes and moving towards the first edge from which extend(s) the negative electrode or electrodes.

[0185] FIG. 4 is a diagrammatic representation of another non-limitative embodiment example of a method according to the invention, conforming to the first solution proposed.

[0186] The method 400, shown in FIG. 4, comprises all the steps of the method 300 in FIG. 3.

[0187] The method 400 also comprises, prior to the steps of the method 300, a step 402 carrying out an electrical recharging of the treated cell(s).

[0188] Each cell can be partially or totally recharged.

[0189] The fact of electrically charging each cell makes it possible to increase the quantity of lithium available for extraction, as the electrical recharging causes migration of the lithium ions to the negative electrode of the cell.

[0190] FIG. 5 is a diagrammatic representation of a non-limitative embodiment example of an installation according to the invention, conforming to the first solution proposed.

[0191] The installation 500, shown in FIG. 5, can be used to implement the method according to the invention, and in particular the methods 300 and 400 in FIGS. 3 and 4.

[0192] The installation 500 makes it possible to extract and recover a part or all of the lithium from a battery cell comprising solid metallic lithium, such as for example the cell 100 in FIG. 1, or from an assembly of cells such as the assembly 200 in FIG. 2.

[0193] The installation 500 comprises an oven 502, filled with an inert gas or placed under vacuum, configured to heat the cell to a treatment temperature greater than or equal to the melting temperature of the solid metallic lithium present in the cells, for example 180.5° C. or 181° C.

[0194] The installation 500 comprises a pair of jaws 504 for holding the cell 100, or the 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 jaw 504 is mounted mobile on a vertical rail 506 so as to displace the cell, or the assembly of cells 200, vertically.

[0195] The installation 500 also comprises a pair of rollers 508, having between them a gap corresponding to the thickness of the cell 100, or of the assembly of cells 200, minus the thickness of the solid layer(s) of metallic lithium. The pair of rollers is positioned so that when the jaws 504 are displaced upwards, the cell 100, respectively the assembly of cell(s) 200, passes between the rollers 508, starting from the second edge 112. Thus, the rollers apply a compression to the cell 100, respectively to the cell assembly 200 progressively, starting from the second edge 112 and moving towards the first edge 110.

[0196] The installation also comprises a receptacle 510 for recovering the molten metallic lithium which flows out of each cell under the effect of gravity. The receptacle 510 must be inert with respect to lithium.

Embodiment Examples according to the Second Solution Proposed

[0197] FIG. 6 is a diagrammatic representation of a non-limitative embodiment example of a method according to the invention, conforming to the second solution proposed;

[0198] The method 600, shown in FIG. 6, comprises a first, optional, step 602 during which the electrical connectors, also known as “crimp connectors”, of each battery cell are removed.

[0199] During an optional step 604, excess material at the level of each side edge of the assembly of cells is removed.

[0200] Then, the method 600 comprises a phase 606 of extraction of the metallic lithium from the cells.

[0201] The extraction phase 606 comprises a step 608 of positioning the assembly of cell(s) in an orientation in which the first edge 110 from which extend(s) the negative electrode or electrodes 102 is located at a higher level, in a vertical direction, than the second edge 112 from which extend(s) the positive electrode or electrodes 104 and the collectors. In particular, the step 608 positions the assembly of cell(s) in a vertical orientation, i.e. parallel to the gravity vector, with the edge from which extend(s) the negative electrode or electrodes 102, upwards. Preferentially, but in no way limitatively, the assembly of cell(s) is held in this orientation throughout the entire extraction phase 606.

[0202] The extraction phase 606 comprises a step 609 of immersion of the assembly of cell(s) in a liquid 850 (see FIG. 8). For example in the embodiment shown in FIG. 8, the liquid 850 is a natural or synthetic oil, for example a paraffin oil, comprising the following physico-chemical properties:

[0203] hydrophobic and non-reactive with respect to lithium,

[0204] electrically insulating,

[0205] having a density greater than that of lithium,

[0206] thermally stable beyond the melting temperature of lithium, i.e. 180.5° C., and

[0207] a flash point, as well as a self-ignition point, as high as possible, for example a temperature greater than 600° C., and as a minimum greater than the treatment temperature of the cell.

[0208] The immersion step 609 is carried out by immersing the assembly of cell(s) 200 in the liquid 850 so that the liquid 850 completely covers the assembly of cell(s) 200.

[0209] This immersion step 609 is particularly advantageous for promoting significant heat exchange between the cell and the liquid 850, which limits the risks of overheating of the cell and the evacuation of the calories generated during a short-circuit and improves the heating kinetics.

[0210] The extraction phase 606 also comprises a step 610 of heating the assembly of cell(s) to a treatment temperature greater than or equal to the melting temperature of the solid metallic lithium present in the assembly of cell(s), for example a temperature of 180.5° C. In the embodiment presented, the liquid 850 is heated by the oven, and transfers heat to the assembly of cell(s). Once greater than the melting temperature of lithium, the temperature causes the melting of the solid metallic lithium and extraction thereof from each cell by natural drainage under the effect of gravity. Preferentially, but in no way limitatively, the assembly of cell(s) is maintained at this temperature throughout the entire extraction phase 606. The treatment temperature must not exceed a degradation temperature of the liquid 850, specific to each liquid 850, beyond which the liquid 850 degrades. In other words, the liquid 850, when exceeding a threshold temperature, would change properties so that the aforementioned properties are no longer met. Ideally, the degradation temperature of the liquid must be greater than +40° C. (and for example between +60° C. and +60° C.) with respect to the melting temperature of lithium.

[0211] Thus the method for the extraction of lithium from a battery makes it possible to limit the effects of short-circuit electrical potentials by making the lithium flow via the first edge 110 from which extend(s) the negative electrode or electrodes 102, and to control short-circuits by immersing the assembly of cell(s) in a liquid that does not react with lithium and improving the dissipation of calories from the assembly of cell(s), in particular during a short-circuit.

[0212] The extraction phase 606 can also comprise an optional step 612 of compressing the assembly of cell(s) so as to accelerate the extraction of the molten lithium out of each cell. The compression can be carried out continuously over all or part of the extraction phase 606. Alternatively, the compression step 612 can be reiterated discontinuously, several times during the extraction phase 606. Preferentially, the compression step 612 carries out an application of the compression, progressively or by sweeping over the surface of the assembly of cell(s), starting from the second edge 112 from which extend(s) the positive electrode or electrodes 104 and moving towards the first edge 110 from which extend(s) the negative electrode or electrodes 102.

[0213] FIG. 7 is a diagrammatic representation of another non-limitative embodiment example of a method according to the invention, conforming to the second solution proposed;

[0214] The method 700, shown in FIG. 7, comprises all the steps of the method 600 in FIG. 6.

[0215] The method 700 also comprises, prior to the steps of the method 600, a step 702 carrying out an electrical recharging of the treated cell or cells.

[0216] Each cell can be partially or totally recharged.

[0217] The fact of electrically charging each cell makes it possible to increase the quantity of lithium available for extraction, as the electrical recharging causes migration of the lithium ions to the negative electrode of the cell, which improves the quantity of lithium extracted as well as the kinetics of the operation.

[0218] FIG. 8 is a diagrammatic representation of a non-limitative embodiment example of an installation according to the invention, conforming to the second solution proposed.

[0219] The installation 800, shown in FIG. 8, can be used to implement the method according to the invention, and in particular the methods 600 and 700 in FIGS. 6 and 7.

[0220] The installation 800 makes it possible to extract and recover a part or all of the lithium from a battery cell comprising solid metallic lithium, such as for example the cell 100 in FIG. 1, or from an assembly of cells such as the assembly 200 in FIG. 2.

[0221] The installation 800 comprises an oven 802, filled with a liquid 850, configured to heat the cell to a treatment temperature greater than or equal to the melting temperature of the solid metallic lithium present in the cells, for example 180.5° C. or 181° C. In the embodiment presented, the liquid 850 is heated by the oven 802, and transfers heat to the assembly of cell(s).

[0222] The installation 800 comprises a pair of jaws 804 for holding the cell 100, or the 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 jaw 804 is mounted mobile on a vertical rail 806 so as to displace the cell 100, or the assembly of cells 200, vertically.

[0223] The liquid 850 completely covers the assembly of cell(s), so that the first edge 110 is situated below the level of the liquid 850.

[0224] The installation 800 also comprises a pair of rollers 808, having between them a gap corresponding to the thickness of the cell 100, or of the assembly of cells 200, minus the thickness of the solid layer or layers of metallic lithium. The pair of rollers is positioned so that when the jaws 804 are displaced upwards, the cell 100, respectively the assembly of cell(s) 200, passes between the rollers 808, starting from the second edge 112. Thus, the rollers apply a compression to the cell 100, respectively to the cell assembly 200 progressively, starting from the second edge 112 and moving towards the first edge 110.

[0225] Of course, the invention is not limited to the examples detailed above.

[0226] For example, the composition of the electric battery cell comprising solid metallic lithium can be different to that indicated in FIG. 1.

[0227] In addition, the installation according to the invention can comprise devices other than those shown in FIGS. 5 and 7, such as for example means for cutting off the electrical connectors from the cell, means for cutting off excesses on one, or each, of the edges.

[0228] For example, the jaws, respectively 504 and 804, can be fixed, and it is the rollers, respectively 508 and 808, that can be mobile and can compress the assembly of cell(s) from the top down, respectively from the bottom up, according to the embodiment.

[0229] In addition, it is possible to use a single oven and several pairs of rollers dedicated to one cell or an assembly of cells.

[0230] A pair of rollers can operate in order to simultaneously treat several adjacent assemblies of cell(s).

[0231] By way of example, the step 609 can be carried out by submerging the cell 100 or the assembly of cell(s) 200 in the liquid 850, or by filling the oven 802 with the liquid 850, so that the liquid 850 covers the assembly of cell(s) 200, respectively the cell 100.

[0232] It should be noted that the orientation of the first edge 110 of the assembly, from which extend(s) one or more negative electrode or electrodes 102, is a function of the density of the fluid in which the cell 100, or the assembly 200 of cells, is immersed. In the event that the fluid is a gas, which is covered by the first solution proposed by the present invention, then the first edge 110 will be situated below the second edge 112 from which extend(s) one or more positive electrode or electrodes 104, since the gas has a lower density than the lithium. In the event that the fluid is a liquid denser than the lithium, which is covered by the second solution proposed by the present invention, then the first edge 110 will be situated above the second edge 112.

[0233] In the event that the fluid is a liquid less dense than the lithium, then the orientation of the first edge 110 will be below the second edge 112, as shown in the first embodiment.

[0234] In addition, the direction of compression of the cell 100, by the rollers 508, respectively 808, is more advantageous for compressing the cell from the second edge 112 to the first edge 110. Thus according to the density of the fluid, the direction of compression is not identical, as can be seen in the examples shown in FIGS. 5 and 8.

[0235] The first edge 110 can be characterized by the fact that it defines the side via which the lithium must flow, once it is in the liquid state.