Method for opening and discharging an electrochemical cell of an ionic insertion-disinsertion battery and method for recycling an ionic insertion-disinsertion battery

Abstract

The invention relates to a method for opening and discharging an electrochemical cell of an ionic insertion-disinsertion battery, comprising a casing in which are housed a negative electrode, a positive electrode, a separator and an electrolyte, which comprises the following operations: opening the electrochemical cell at the level of one or more zones of the casing, at least the opening zone(s) being brought into contact with a liquid L1, then discharging the electrochemical cell by bringing the cell into contact with a liquid L2, and which is characterized in that: - the liquid L1 comprises a solvent based on an alcohol and optionally a redox mediator, while the liquid L2 comprises a solvent based on an alcohol jointly with a redox mediator; and - the liquids L1 and L2 are free of chlorine.It also relates to a recycling process for an ionic insertion-disinsertion battery that employs this opening and discharging process. Applications: recycling of lithium-ion, sodium-ion, potassium-ion, calcium-ion, or magnesium-ion batteries.

Description

Title of the invention: Method for opening and discharging an electrochemical cell of an ionic insertion-disinsertion battery and method for recycling an ionic insertion-disinsertion battery technical field

[0001] The invention relates to the field of recycling used, defective, damaged or discarded batteries.

[0002] More specifically, the invention relates to a method of opening and discharging an electrochemical cell of an ionic insertion-disinsertion battery for the purpose of recycling the valuable fractions of this cell.

[0003] It also relates to a method of recycling an ionic insertion-disinsertion battery implementing this opening and discharge method.

[0004] The invention, which allows for the safe opening and neutralization of electrochemical battery cells operating on the principle of insertion-disinsertion - also known as intercalation-disintercalation - of metallic ions within the constituent materials of the electrodes of these electrochemical cells, finds particular application in the recycling of lithium-ion (or Li-ion), sodium-ion (or Na-ion), potassium-ion (or K-ion), calcium-ion (or Ca-ion) or magnesium-ion (or Mg-ion) type batteries, and especially Li-ion batteries. Prior art

[0005] The market for batteries and, in particular, for lithium batteries of the Li-ion type is currently expanding rapidly due, on the one hand, to the continued development of so-called "mobile" devices (mobile phones, touch tablets, cameras, laptops, etc.) and, on the other hand, to the emergence of new applications related to the development of hybrid or all-electric transport vehicles and the storage of intermittently produced energy (wind turbines, solar panels, etc.).

[0006] Beyond the regulatory recycling constraints imposed by the European Union, there are three reasons to recycle used, damaged or discarded batteries: - an environmental reason, namely that batteries represent waste that is harmful to the environment if they are not properly managed, and the use of materials from recycling instead of mining resources helps to reduce the environmental impact; - a safety reason, namely that batteries are dangerous objects that can be a source of fires, particularly in waste disposal sites; and - a strategic reason, namely that batteries contain critical and strategic metals whose recovery can contribute to their supply.

[0007] Battery recycling is therefore a major issue.

[0008] The electrochemical cells of Li-ion batteries are each composed of a casing which can be flexible, for example made of a polymer, or rigid, for example made of steel, and in which are housed a negative electrode, a positive electrode, a separator and an electrolyte.

[0009] The negative electrode is typically made of a mixture of a carbonaceous material such as graphite powder, and an organic binder of the sodium carboxymethylcellulose or poly(styrene / butadiene) type, which is deposited on a copper foil forming a current collector.

[0010] The positive electrode is typically made of a mixture comprising a lithia material (such as a lithia metal phosphate such as LiFePO4, a lithia metal oxide of the type LiCoO2, LiMnO2, LiNiO2, LiNixMnyCozO2 with x + y + z = 1 (also known by the abbreviation NMC) such as LiNii / 3Mni / 3Coi / 3O2 or LiNio,6Mnoj2Coo>2O2, or LiNixCoyAlzO2 with x + y + z = 1 (also known by the abbreviation NCA) such as LiNio.sCoojsAlo.osCL), a graphite powder and an organic binder of the PVDF type, this mixture being deposited on an aluminum foil also forming a current collector.

[0011] As for the electrolyte, it typically comprises a lithium salt (for example, LiPF6, LiCF3SO3, LiBF4, LiAsF6 or LiC104) as well as additives to slow down side reactions in solution in an organic solvent or a mixture of organic solvents (for example, a mixture of carbonates).

[0012] The operation of an electrochemical cell of a Li-ion battery is as follows.

[0013] During the charging of this cell induced by an external energy input, the positive electrode is the site of an oxidation reaction which results in the release, by the lithia material of this electrode, of lithium ions into the electrolyte and of electrons into the external circuit which connects the two current collectors, while the negative electrode is the site of a reduction reaction which results in the insertion of the lithium ions thus released into the carbon material of this electrode with a consumption of the electrons supplied by the external circuit.

[0014] During the discharge of the cell, the reactions are reversed: it is therefore the negative electrode which is the site of an oxidation reaction with, as a result, a release of lithium ions by the carbon material of this electrode while the positive electrode is the site of a reduction reaction with, as a result, an insertion of the lithium ions thus released into the lithia material of this electrode.

[0015] This operating principle is called: rocking-chair mechanism.

[0016] As they are used, Li-ion batteries lose capacity and must be replaced.

[0017] However, many end-of-life batteries still have a relatively high residual charge level and their crushing is likely to produce significant sparks or ignitions, or even explosions.

[0018] Other Li-ion batteries must also be recycled, such as defective, damaged, or discarded batteries. However, defective or damaged battery cells may have significant deposits of metallic lithium on the negative electrode, which are highly reactive when exposed to air or water. Like end-of-life battery cells, defective or damaged battery cells cannot be opened safely and must therefore be handled with the utmost care.

[0019] Typically, upstream of a battery recycling process, such as for Li-ion batteries, a pretreatment is carried out including a battery sorting phase, a battery dismantling phase to release the electrochemical cells that compose them, and a phase of securing these electrochemical cells. Pyrometallurgical and / or hydrometallurgical treatments are then carried out to recover the various materials and metals contained in the electrochemical cells.

[0020] Currently, the main problem lies in the phase of securing the electrochemical cells.

[0021] Indeed, during a loss of containment, leaks of the electrolyte, a toxic, flammable, and corrosive product, occur in both liquid and gaseous forms. The vapors thus generated, when mixed with air, can form an explosive atmosphere (ATEX) that is liable to ignite upon contact with an ignition source such as a spark or a hot surface, thereby causing an explosion. Furthermore, lithium salts present in electrolytes such as LiPF6, LiBF4, LiAsF6, and LiClO4 can release particularly toxic and corrosive fumes containing phosphorus, fluorine, and / or lithium. Hydrofluoric acid (HF) can also be formed. Therefore, batteries, even when completely discharged, must be opened in a well-ventilated area free from the risk of sparks in order to mitigate the risks of flammability and toxicity associated with the electrolytes.

[0022] Recently, it has been proposed to use an ionic liquid or a deep eutectic solvent to perform the safety-making of electrochemical cells of Li-ion or Na-ion batteries.

[0023] Thus, EP-A-3 948 994 describes a method for neutralizing an electro-cell Li-ion or Na-ion chemical which consists of discharging this cell by bringing it into contact, in particular by immersion, with a solution comprising an ionic liquid as well as a so-called oxidizing redox species, capable of being reduced on the negative electrode of the electrochemical cell and, thus, of causing a discharge of the electrochemical cell.

[0024] EP-A-3 948 993 also describes a method for grinding a Li-ion or Na-ion electrochemical cell in which the cell is ground in a solution comprising an ionic liquid and a so-called oxidizing redox species, the function of which is, again, to allow the electrochemical cell to discharge simultaneously with the grinding. Thanks to the ionic liquid, the grinding of the electrochemical cell can be carried out safely and, in particular, by preventing the formation of an explosive atmosphere.

[0025] Finally, WO-A-2023 / 067275 describes a method for opening a Li-ion or Na-ion electrochemical cell in which this cell is immersed in a solution comprising, in addition to a so-called oxidizing redox species, an ionic liquid or a deep eutectic solvent formed of a choline chloride and a hydrogen bond donor, and then opened by means of a cutting tool.

[0026] Although these processes undoubtedly have an interest, the inventor, continuing his work on the safety of electrochemical battery cells and, in particular, Li-ion batteries, has set himself the goal of providing a process which, while allowing the safe neutralization of an electrochemical cell, does not require the use of ionic liquids and deep eutectic solvents based on choline chloride, these liquids and solvents being, in fact, relatively expensive and, moreover, corrosive.

[0027] The inventor also set himself the goal that this process should be simple to implement and applicable to the treatment, on an industrial scale, of worn, defective, damaged or discarded electrochemical cells. Description of the invention

[0028] These objectives are achieved by the invention which relates to a method for opening and discharging an electrochemical ion insertion-disinsertion battery cell, comprising a casing in which are housed a negative electrode, a positive electrode, a separator and an electrolyte, which method comprises the following operations: a) opening of the electrochemical cell at one or more zones of the envelope, at least the opening zone(s) being brought into contact with a liquid L1; then b) discharge of the electrochemical cell by bringing the cell into contact with a liquid L2; and which is characterized in that: - Liquid L1 comprises an alcohol-based solvent and optionally a redox mediator in solution in that solvent, while liquid L2 comprises an alcohol-based solvent jointly with a redox mediator in solution in that solvent; and - liquids L1 and L2 are chlorine-free.

[0029] Thus, according to the invention, it is achieved: - opening the electrochemical cell at one or more points on its envelope to make the inside of the cell accessible, and more specifically, its two electrodes, at least the opening point(s) being brought into contact with a liquid L1 which, in particular, dissipates the heat produced by the opening operation at this point(s) and thus prevents thermal runaway of the electrochemical cell that could lead to ignition or even an explosion of the cell, this liquid comprising a solvent based on an alcohol and optionally a redox mediator but being chlorine-free, then - the discharge of the electrochemical cell by bringing this cell into contact with a liquid L2 suitable for enabling, through redox reactions, a deactivation of the electrochemical cell and, by the same token, a safety measure for this cell, this liquid comprising a solvent based on an alcohol as well as a redox mediator but also being free of chlorine.

[0030] The absence of chlorine in the L1 and L2 liquids not only avoids the corrosion phenomena observed with the use of ionic liquids or deep eutectic solvents based on choline chloride and reduces the costs associated with the use of these liquids and solvents, but also improves the efficiency of the process, in particular by increasing the discharge kinetics.

[0031] In the foregoing and following, the term "redox mediator," also called "redox couple," refers to an oxidizing / reducing (Ox / Red) couple in solution where the oxidant can be reduced at the negative electrode of the electrochemical cell while the reductant can be oxidized at the positive electrode of that cell. Thus, when a liquid containing a redox mediator is brought into contact with the interior of the electrochemical cell, the reduction of the oxidant coupled with the oxidation of the reductant leads to ionic disinsertion at the negative electrode and migration of the disinserted ions via the electrolyte to the positive electrode where they are immobilized. The redox mediator thus induces, in a sense, a "forced" discharge of the electrochemical cell.Furthermore, the reduction of the oxidant and the oxidation of the reducer allow the formation of new oxidant / reducer species and / or the regeneration of the oxidant / reducer species initially present in solution which will, in turn, be reduced / oxidized at the level of the . electrodes.

[0032] Furthermore, the expression "comprising a solvent based on an alcohol", applied to liquids L1 and L2, means that more than 50% of the total number of moles of solvent present in these liquids are moles of an alcohol, it being understood that the molar alcohol content of the solvent can reach 100%, in which case the solvent consists solely of an alcohol.

[0033] The expression "free of chlorine", applied to liquids L1 and L2, means that these liquids do not contain chlorine in any form whatsoever (ionic, molecular, ...).

[0034] Furthermore, we hear: - by positive electrode, the electrode that acted as the cathode when the electrochemical cell delivered current while in use, that is, when it was discharging, and acted as the anode when the electrochemical cell was charging; and - by negative electrode, the electrode which, conversely, acted as an anode when the electrochemical cell delivered current and acted as a cathode when the electrochemical cell was in the process of charging.

[0035] According to the invention, the opening of the electrochemical cell is preferably carried out by a technique which does not cause excessive deformation of this cell, such as crushing, so as to avoid the occurrence, during this opening, of an internal short circuit likely to lead to thermal runaway and explosion of the electrochemical cell.

[0036] Furthermore, the opening of the electrochemical cell is preferably achieved by a technique which, to ensure the opening, involves one or more non-electrically conductive or weakly electrically conductive elements or of which at least the part of this or these elements which is intended to be in contact with the electrochemical cell is made of a non-electrically conductive or weakly electrically conductive material, that is to say in a material whose electrical resistance is preferably equal to or greater than 100 mohms, for example in a ceramic (silicon carbide or nitride, alumina, tungsten carbide, etc.) or in diamond.

[0037] The opening of the electrochemical cell can be achieved by grinding but it is preferably achieved by cutting (or slicing, the words cutting and slicing being considered here as synonyms) or by drilling all or part of the cell envelope so as to partially or totally open this envelope.

[0038] Thus, the opening of the electrochemical cell can notably be achieved by knife cutting (or blade cutting), guillotine cutting, wire cutting, ultrasonic cutting, laser cutting, saw cutting (for example, using a circular saw or band saw), or cutting with a grinder or disc cutter (by for example, by means of a resinoid grinding wheel), by cutting by means of a jet of pressurized liquid, charged or not with abrasive particles (such as garnet particles) or by drilling, for example by means of a drill bit, it being understood that, in all cases, it will be preferable - as previously indicated - that the cutting or drilling tool used or, at the very least, the part of this tool which is intended to be in contact with the electrochemical cell or the abrasive particles used (in the case where the opening is made by means of a jet of abrasive liquid) be made of a non-electrically conductive or weakly electrically conductive material.

[0039] Among these techniques, preference is given to cutting the electrochemical cell and, more specifically, to cutting with wire, saw or grinder, with preference given to cutting with a grinder, in particular with a resinoid grinding wheel.

[0040] In any event, the opening of the electrochemical cell is carried out in the presence of the liquid L1 which is brought into contact with at least the opening area(s), or even with the whole of the cell or even with the whole of the battery module including this cell.

[0041] Preferably, this contacting includes - or is achieved by - spraying (or projecting a jet) of the liquid L1 onto the opening area(s) of the electrochemical cell or onto the whole of this cell or of the battery module comprising this cell, this spraying being such that the electrochemical cell or the battery module is partially or totally immersed in the liquid L1 during the opening.

[0042] Alternatively, contact can be made by immediately immersing the electrochemical cell or the battery module including this cell in the liquid Ll.

[0043] According to the invention, the liquid Ll is advantageously a liquid which has at least the following characteristics: - not to be viscous or only very slightly viscous, that is to say, preferably to have a dynamic viscosity of no more than 40 mPa.s at room temperature (20-25 °C) so as to facilitate, on the one hand, its spraying, typically by spraying, and, on the other hand, its filtration, once loaded with debris from the operation of opening the electrochemical cell, with a view to reusing this liquid for opening other electrochemical cells; - preferably exhibit a flash point of at least 50 °C and, even better, at least 55 °C; - to be as biodegradable as possible so that its use on an industrial scale has the least possible impact on the environment; and - in the case where the liquid Ll is intended to contain a redox mediator, to allow dissolution of this mediator.

[0044] As previously stated, the liquid L1 may be free of redox mediator, in which case, in addition to dissipating the heat generated by the opening of the electrochemical cell, the liquid L1 prevents the electrochemical cell from discharging during opening and thus controls the cell's reactivity. This can be particularly advantageous if the opening and discharging operations of the electrochemical cell are carried out in two separate areas of the same workshop or in two different workshops, and if the implementation of the process of the invention involves transferring the electrochemical cell, particularly under air, from one area to another or from one workshop to another.

[0045] In which case, in addition to the aforementioned characteristics, the liquid L1 advantageously exhibits an electrical resistance greater than 10 ohms, preferably greater than 100 ohms, with preference given to a liquid that has no ionic conductivity or very low ionic conductivity, i.e., at most 1000 qS / cm at 25 °C. This is particularly desirable to avoid, or at least minimize, the degradation of the solvent in liquid L1 and the reactivity of electrochemical cells, especially when processing electrochemical cells with high voltages (typically greater than 12 V).

[0046] The solvent of a liquid L1 of this type may, for example, consist solely of an alcohol or comprise this alcohol mixed with deionized water (whose resistivity typically ranges from 1 to 10 MQ.cm at 25 °C) or ultrapure water, for example of the Milli-Q type (whose resistivity is 18.2 MQ.cm at 25 °C) and / or with one or more organic co-solvents, in a molar ratio alcohol / water, alcohol / organic co-solvent(s) or alcohol / (water + organic co-solvent(s)) greater than 1.

[0047] Alternatively, the liquid L1 may include a redox mediator if it is desired to initiate the discharge of the electrochemical cell during its opening, in which case this liquid does not have to satisfy the resistivity criterion mentioned above.

[0048] As previously indicated, the discharge of the electrochemical cell is achieved by bringing the electrochemical cell into contact with the liquid L2.

[0049] In accordance with the invention, this contact is preferably made by immersion, preferably total (i.e. of the whole), of the electrochemical cell or the battery module comprising this cell in the liquid L2.

[0050] Furthermore, the liquid L2, which, as previously indicated, comprises a solvent based on an alcohol and a redox mediator, advantageously exhibits dynamic viscosity, volatility, biodegradability and cost characteristics similar to those previously stated for the liquid L1, as well as an ability to dissolve the redox mediator that one wishes to use.

[0051] According to the invention, the liquid L2 may comprise the same solvent as the liquid L1 or a solvent different from it.

[0052] Similarly, if liquid L1 includes a redox mediator, then liquid L2 may include the same redox mediator as liquid L1 or a different redox mediator.

[0053] Thus, in accordance with the invention, it is possible to carry out the opening and discharging operations with, for example: - liquids L1 and L2 which differ from each other both in that they include different solvents (due to their qualitative and / or quantitative composition) and in that liquid L1 does not include a redox mediator; - liquids L1 and L2 which include the same solvent but which differ from each other in that liquid L1 does not include a redox mediator; - liquids L1 and L2 which include the same solvent and which both include a redox mediator but which differ from each other in that they do not include the same redox mediator; - liquids L1 and L2 which include the same solvent and the same redox mediator but which differ from each other in that liquid L2 has a higher redox mediator content than liquid L1 (the reverse not being desirable); - liquids L1 and L2 which, although both containing a redox mediator, or even the same redox mediator, differ from each other in that they contain different solvents; or - liquids L1 and L2 which are identical, both in their qualitative and quantitative composition.

[0054] In the context of the invention, preference is given to the use of: - of a liquid L1 whose solvent is identical to the solvent of liquid L2 but which is free of redox mediator, or - of a liquid L1 which is identical to liquid L2, This is particularly due to the cost of implementing the process.

[0055] In the case of using different liquids L1 and L2, then the opening and discharge operations will necessarily be carried out in two successive steps, separated in time, whereas, in the case of using identical liquids L1 and L2, the opening and discharge operations may also be carried out in two successive steps, separated in time, but preference will be given to carrying out these operations in a single step and using one and the same liquid.

[0056] In general, preference will be given to using liquids L1 and L2 comprising the same solvent or solvents of very similar qualitative and / or quantitative compositions in order to minimize the costs of implementing the process.

[0057] In any event, the alcohol present in the solvent of liquid L1 and / or in the solvent of the liquid L2 or constituent of this (these) solvent(s) - in the case where this alcohol represents 100% of the total number of moles of solvent - is advantageously a diol, preferably a glycol and, even better: - ethylene glycol, with the formula CH2OH-CH2OH, which has a dynamic viscosity of 21 mPa.s at 20 °C, a saturated vapor pressure of 7 Pa at 20 °C, a boiling point of 197.5 °C at normal atmospheric pressure (i.e. 1 atm), or - propylene glycol, with the formula CH3-CHOH-CH2OH, which has a dynamic viscosity of 56 mPa.s at 20 °C, a saturated vapor pressure of 10.6 Pa at 20 °C and a boiling point of 188.2 °C at normal atmospheric pressure, or - a mixture of these.

[0058] Preferably, the solvent of liquid L1 and / or the solvent of liquid L2 is (are) made up of ethylene glycol or propylene glycol or a mixture of these, with preference given to ethylene glycol.

[0059] As for the redox mediator present in liquid L2 and, optionally, in liquid L1, it may be a metallic electrochemical couple such as a Mn2+ / Mn3+, Co2+ / Co3+, Cr2+ / Cr3+, Cr3+ / Cr6+, V2+ / V3+, V4+ / V5+, Sn2+ / Sn4+, Ag+ / Ag2+, Cu+ / Cu2+, Ru4+ / Ru8+ or Fe2+ / Fe3+ couple, which may be supplied to the solvent of liquid L2 and, where applicable, to the solvent of liquid L1 in the form of a metallic salt other than a chloride, for example of the sulfate, nitrate, phosphate, sulfide, ascorbate type, etc., in the form of an organometallic complex, for example metallocene (Fc / Fc+) of the ferrocene, manganocene, colbaltocene, chromocene, vanadocene type, etc., or of a salt of an organometallic complex other than a chloride.

[0060] Among these electrochemical couples, preference is given to: - on the one hand, to the Fe2+ / Fe3+ couple, which is advantageously supplied to the solvent of liquid L2 and, where applicable, to the solvent of liquid L1 in the form of a ferric salt, for example in the form of iron(III) sulfate, iron(III) nitrate or iron(III) phosphate (also called iron orthophosphate), the iron ions having the additional advantage of being reduced to metallic iron, allowing metallic deposition in the reactive zone or zones, which is particularly favorable to the discharge of the cell; and - on the other hand, to the Cu+ / Cu2+ couple, which is advantageously supplied to the solvent of liquid L2 and, where appropriate, to the solvent of liquid L1 in the form of a copper(II) salt, for example in the form of copper(II) sulfate, copper(II) nitrate or copper(II) phosphate, the copper ions also having the advantage of being reduced to metallic copper and allowing a metallic deposition in the reactive zone(s), particularly favorable to the discharge of the cell.

[0061] Alternatively, the redox mediator may also include an electrochemical couple of an organic nature such as a quinone / hydroquinone couple.

[0062] In accordance with the invention, it is also possible to provide for the presence in liquid L1 and / or liquid L2 of: * of a co-solvent for, for example: - lower their viscosity and / or flammability, in which case the co-solvent may be water or an organic co-solvent such as vinylene carbonate, γ-butyrolactone or propylene carbonate, it being understood that, in the case where liquid L1 does not contain a redox mediator, the water will preferably be deionized or ultrapure water as previously indicated; or - reduce their saturated vapor pressure, in which case the co-solvent will be, for example, a low molecular weight polyethylene glycol, i.e., less than 600 g / mol; or - to provide a function of extinguishing agent and / or flame retardant so as to further reduce the risk of flammability of the electrochemical cell, in which case the co-solvent will be, for example, a trialkyl phosphate such as trimethyl phosphate or triethyl phosphate, this triethyl phosphate being able to be fluorinated such as tris(2,2,2-trifluoroethyl phosphate); it being understood that, in all cases, the molar ratio of alcohol / co-solvent(s) will always be greater than 1; * of a salt (other than chloride), suitable for promoting the ionic conductivity of liquid L1 and / or liquid L2, such as an aluminium sulfate or a sodium sulfate, it being understood that this salt will only be present in liquid L2 if it is desired that liquid L1 not be ionically conductive or only very slightly so; * a drying agent, which may be a salt (other than chloride) incapable of participating in electrode reactions or reacting with the solvent, for example magnesium sulfate (MgSO4), sodium sulfate (Na2SO4), calcium sulfate (CaSO4), potassium carbonate (K2CO3), sodium hydroxide (NaOH) or potassium hydroxide (KOH), it being understood that, here too, this salt will only be present in liquid L2 if it is desired that liquid L1 be non-ionically conductive or only very slightly so; or * of a salt stabilizer(s) of the carbonate type (K2CO3 for example) or phosphate.

[0063] Preferably: - either liquid L1 consists of ethylene glycol while liquid L2 consists of ethylene glycol and iron sulfate, - either liquid L1 and liquid L2 are both made up of ethylene glycol and iron sulfate.

[0064] According to the invention, the operation of opening the electrochemical cell can be carried out under an inert atmosphere, for example under argon, nitrogen, carbon dioxide or one of their mixtures, for greater safety with regard to the fire triangle. Thus, the opening operation of the electrochemical cell can be carried out in an enclosure supplied with an inert gas or a mixture of inert gases and which is associated with a control system, in particular of the oxygen content, or even of the extraction of the gases produced during this opening operation.

[0065] Alternatively and preferably, the opening operation is carried out under air.

[0066] For better heat dissipation when opening the electrochemical cell, the liquid L1 can advantageously be cooled before being brought into contact with at least the opening area(s) of the electrochemical cell, or even with the whole of this cell or the battery module comprising it.

[0067] As for the liquid L2 which is brought into contact with the electrochemical cell during the discharge operation, it is preferable that its temperature not exceed 60 °C to prevent the electrolyte of this cell from degrading and the occurrence of a thermal runaway process likely to lead to an explosion of the electrochemical cell.

[0068] Preferably, the liquid L2 will be at room temperature, i.e. around 20-25 °C.

[0069] In accordance with the invention, the opening and discharge operations of the electrochemical cell can be carried out: - in a single step, in which case they will necessarily be carried out in the same workshop, or even in the same enclosure if the opening operation is carried out under a controlled atmosphere, or - in two successive stages, in which case they may be carried out in two separate areas of the same workshop or in two different workshops, and the process will include an intermediate stage corresponding to the transfer of the electrochemical cell from the first area or workshop to the second area or workshop. Preferably, this transfer will be carried out in air, it being understood that contact between the liquid L1 and at least the opening(s) of the electrochemical cell, or even with the entire cell or the battery module comprising it, may or may not be maintained during this transfer.

[0070] According to the invention, the electrochemical cell can be a cell from a lithium-ion, sodium-ion, potassium-ion, calcium-ion or magnesium-ion battery.

[0071] Preferably, the electrochemical cell is a cell from a lithium-ion or sodium-ion battery, with preference given to a lithium-ion battery.

[0072] In particular, the electrochemical cell is a lithium-ion battery cell whose positive electrode comprises a lithium metal oxide NMC, i.e., of formula LiNixMnyCozO2 with x + y + z = 1 such as LiNii / 3Mni / 3Coi / 3O2 or LiNio,6Mno,2CoOj2O2, or a lithium metal oxide NCA, i.e., of formula LiNixCoyAlzO2 with x + y + z = 1 such that LiNio.sCoo,15Alo,0502.

[0073] The invention further relates to a method for recycling an ionic insertion-disinsertion battery which includes the implementation of an opening and discharge method as previously described.

[0074] In the preceding and following, "battery" means both a battery module corresponding to a series or parallel assembly of a plurality of identical electrochemical cells, and a battery block (or battery pack) corresponding to an assembly of several identical battery modules.

[0075] Here too, the battery can be a lithium-ion, sodium-ion, potassium-ion, calcium-ion or magnesium-ion battery, preference being given to a lithium-ion or sodium-ion battery and, even more so, to a lithium-ion battery.

[0076] In particular, the lithium-ion battery is a battery which comprises electrochemical cells whose positive electrode comprises a lithia metal oxide NMC, that is to say of formula LiNixMnyCozO2 with x + y + z = 1 such as LiNii / 3Mni / 3Coi / 3O2 or LiNio,6Mnoj2Coo>202, or a lithia metal oxide NCA, that is to say of formula LiNixCoyAlzO2 with x + y + z = 1 such as LiNio.sCoo,,15A1o,0502.

[0077] Other features and advantages of the process of the invention will become apparent from the following supplementary description, which relates to tests which have validated this process and which refers to the attached figures.

[0078] It goes without saying, however, that this additional description is given only as an illustration of the process of the invention and should in no case be interpreted as a limitation thereof. Brief description of the figures

[0079] [Fig. 1] illustrates the evolution over time, denoted t and expressed in minutes, of the voltage, denoted U and expressed in volts, and of the temperature, denoted T and expressed in °C, of ​​a Li-ion cell subjected to the opening and discharge process of the invention according to a first embodiment of this process; in this figure, curve 1 corresponds to the voltage while curve 2 corresponds to the temperature.

[0080] [Fig.2] is a figure analogous to [Fig.1] but for a second embodiment of the method of the invention.

[0081] [Fig.3] is also a figure analogous to [Fig.1] but for a third embodiment of the method of the invention.

[0082] Detailed description of particular implementation methods

[0083] Example 1: Opening and discharging a Li-ion cell in an ethylene glycol solution comprising 0.01 mol / L of iron(III) sulfate

[0084] A first Li-ion 18650 cell, of NMC chemistry and exhibiting a nominal capacity of 3 Ah, a voltage of 3.7 V and a state of charge of 30%, on a first opening and discharge test by the method of the invention.

[0085] In the present example, the cutting and discharge operations are carried out in a single step, at ambient temperature and atmosphere, using one and the same solution for both operations, namely an ethylene glycol solution comprising 0.01 mol / L of iron sulfate as a redox mediator.

[0086] To do this, the cell is first sprayed with the ethylene glycol solution until it is totally immersed in this solution, then, with the spraying maintained, the cell is cut using an alumina-based resinoid grinding wheel, at a speed of 1 mm / s, until a notch 7 mm deep is obtained (i.e. for less than 10 seconds).

[0087] The cell is then left immersed in the ethylene glycol solution until it has a charge state of 0% (i.e. a voltage of 2.5 V instead of 3.7 V), without recirculation or thermalization of this solution.

[0088] As shown by [Fig. 1], which corresponds to the monitoring of the voltage U (in volts) and the temperature T (in °C) of the cell over time (in minutes), the voltage of the cell gradually decreases after the cutting and spraying stops, materialized by the arrow fl on this figure and the state of charge of 0% is reached in 5 hours and 26 minutes, i.e. C / 16.3.

[0089] The measurement of the cell temperature during the test shows a heating of this cell but this heating is sufficiently low (since the maximum temperature of the cell is 29.6 °C) to allow an opening and a discharge without risk of explosion or ignition.

[0090] Example 2: Opening and discharging a Li-ion cell in an ethylene glycol solution comprising 0.04 mol / L of iron(III) sulfate

[0091] A second 18650 Li-ion cell having the same characteristics of chemistry, voltage, nominal capacity and state of charge as the cell tested in Example 1 is subjected to a second opening and discharge test by the method of the invention.

[0092] This test differs from the test in Example 1 only in that the solution used for opening and discharging the cell is an ethylene glycol solution comprising 0.04 mol / L of iron(III) sulfate, all other operating conditions being identical to those mentioned in Example 1.

[0093] As shown in [Fig.2], which corresponds to the monitoring of the voltage U (in volts) of the cell and the temperature T (in °C) of this cell over time (in minutes), a state of charge of 0% is obtained in 29 minutes, i.e. C / 1.5.

[0094] The cell heating is greater than that observed in the test of Example 1 since the cell temperature, initially 25.5 °C, reaches a The maximum value is 43.6 °C. This maximum temperature is nevertheless low enough that the cell can be opened and discharged without risk of explosion or ignition.

[0095] Example 3: Opening and discharging a Li-ion cell in an ethylene glycol solution comprising 0.08 mol / L of iron(III) sulfate

[0096] A third 18650 Li-ion cell having the same characteristics of chemistry, voltage, nominal capacity and state of charge as the cells tested in the previous examples is subjected to a third opening and discharge test by the method of the invention.

[0097] This test differs from previous tests only in that the solution used for opening and discharging the cell is an ethylene glycol solution comprising 0.08 mol / L of iron(III) sulfate, all other operating conditions being identical to those mentioned in Example 1.

[0098] As shown in [Fig.3], which corresponds to the monitoring of the voltage U (in volts) of the cell and the temperature T (in °C) of this cell over time (in minutes), a state of charge of 0% is obtained in 16 minutes, i.e. C / 0.8.

[0099] The heating of the cell is substantially the same as that observed in the test of Example 2, since the cell temperature, initially 23.3 °C, reaches a maximum value of 40.9 °C. Here too, this maximum temperature is nevertheless sufficiently low for the opening and discharge of the cell to be carried out without risk of explosion or ignition. REFERENCES CITED

[0100] EP-A-3 948 994

[0101] EP-A-3 948 993

[0102] WO-A-2023 / 067275

Claims

Demands

1. A method for opening and discharging an electrochemical cell of an ionic insertion-disinsertion battery, comprising a casing in which are housed a negative electrode, a positive electrode, a separator and an electrolyte, which comprises the following operations: a) opening the electrochemical cell at one or more zones of the casing, at least the opening zone(s) being brought into contact with a liquid L1; then b) discharging the electrochemical cell by bringing the cell into contact with a liquid L2; and which is characterized in that: - the liquid L1 comprises a solvent based on an alcohol and optionally a redox mediator in solution in this solvent, while the liquid L2 comprises a solvent based on an alcohol together with a redox mediator in solution in this solvent; and - the liquids L1 and L2 are chlorine-free.

2. A method according to claim 1, wherein the opening of the cell comprises a cut or a hole in all or part of the shell of the electrochemical cell.

3. A method according to claim 1 or claim 2, wherein, in step a), the contacting of at least the opening area(s) with the liquid L1 comprises spraying the liquid L1 onto at least the opening area(s).

4. A method according to any one of claims 1 to 3, wherein, in step b), the contacting of the electrochemical cell with the liquid L2 comprises an immersion of the cell in the liquid L2.

5. A method according to any one of claims 1 to 4, wherein the alcohol of the solvent of liquid L1 and / or of the solvent of liquid L2 is a diol, preferably a glycol.

6. A method according to any one of claims 1 to 5, wherein the alcohol of the solvent of liquid L1 and / or of the solvent of liquid L2 is selected from ethylene glycol, propylene glycol and mixtures thereof.

7. A method according to any one of claims 1 to 6, wherein the solvent of liquid L1 and / or the solvent of liquid L2 is (are) made up of ethylene glycol or propylene glycol or a mixture thereof.

8. A method according to any one of claims 1 to 7, wherein the

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18. The solvent of liquid L1 and the solvent of liquid L2 are made of ethylene glycol. A process according to any one of claims 1 to 8, wherein the redox mediator of liquid L1 and / or liquid L2 is an electrochemical couple selected from Mn2+ / Mn3+, Co2+ / Co3+, Cr2+ / Cr3+, Cr3+ / Cr6+, N2+IN 3+, V4+ / V5+, Sn2+ / Sn4+, Ag+ / Ag2+, Cu+ / Cu2+, Ru4+ / Ru8+ and Fe2+ / Fe3+, which is supplied to the solvent in the form of a metallic salt other than a chloride, an organometallic complex or a salt of an organometallic complex other than a chloride. A process according to claim 9, wherein the electrochemical couple is Fe2+ / Fe3+ which is supplied in the form of a ferric salt, or Cu+ / Cu2+ which is supplied in the form of a copper salt. A method according to any one of claims 1 to 10, wherein the solvent of liquid L1 is identical to the solvent of liquid L2 but liquid L1 is free of redox mediator. A method according to claim 11, wherein liquid L1 consists of ethylene glycol while liquid L2 consists of ethylene glycol and iron sulfate. A method according to any one of claims 1 to 10, wherein the liquid L1 is identical to the liquid L2. A process according to claim 13, wherein liquid L1 and liquid L2 consist of ethylene glycol and iron sulfate. A method according to any one of claims 1 to 14, wherein the opening and discharging operations are carried out in a single step and using the same liquid for both opening and discharging. A method for recycling an ionic insertion-disinsertion battery, comprising implementing an opening and discharging method according to any one of claims 1 to 15. A method according to any one of claims 1 to 16, wherein the battery is a lithium-ion, sodium-ion, potassium-ion, calcium-ion or magnesium-ion battery and, preferably, a lithium-ion or sodium-ion battery. Method according to claim 17, wherein the battery is a lithium-ion battery and, preferably, a battery which comprises electrochemical cells whose positive electrode comprises a lithia metal oxide of formula LiNixMnyCozO2 with x + y + z= or of formula LiNixCoyAlzO2 with x + y + z = 1.

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