Method for opening and discharging an electrochemical generator - Patent Application 20070122997

Abstract

The present invention provides a method for opening and discharging an electrochemical generator (10) comprising a negative electrode containing lithium or sodium and a positive electrode optionally containing lithium or sodium, the method comprising the following successive steps: - opening the electrochemical generator (10) at the cutting zone using a cutting element (20), preferably a cutting element (20) having an electrical resistance greater than 100 mΩ, the electrochemical generator being carried out while spraying the first solution (100) at the cutting zone; - discharging the electrochemical generator (10) by partially or even completely immersing the electrochemical generator (10) in a second solution (200).

Description

[Technical Field]

[0001] The present invention relates to a method for opening and discharging an electrochemical generator, such as an accumulator, cell or battery, which allows the electrochemical generator to be opened safely and thereafter the recoverable fraction to be recycled.

[0002] The present invention places particular emphasis on the recycling of accumulators or battery-type electrochemical systems, treated separately or as a mixture, and in particular the recycling of Li-ion, Na-ion, or lithium metal type batteries and accumulators. [Background technology]

[0003] An electrochemical generator is a device for converting chemical energy into electrical energy to produce electricity. For example, an electrochemical generator can consist of a cell or a battery.

[0004] The market for storage batteries, and in particular lithium storage batteries of the Li-ion type, is currently expanding rapidly due to, on the one hand, so-called portable applications (smartphones, computers, cameras, etc.) and, on the other hand, new applications related to mobility (electric and hybrid vehicles) and so-called stationary applications (connected to the power grid).

[0005] In recent years, the number of storage batteries has increased, making their recycling a major issue.

[0006] Conventionally, a lithium-ion battery includes an anode, a cathode, a separator, an electrolyte, and a case.

[0007] Generally, the anode is formed from graphite mixed with a PVDF-type binder deposited on a copper sheet, and the cathode is a metallic lithium intercalation material (e.g., LiCoO, LiMnO, LiNiO, 0) mixed with a binder and deposited on an aluminum sheet. <x<1のLiNixCo 1-xO2, Li3NiMnCoO6, or LiFePO4).

[0008] The electrolyte is a mixture of a non-aqueous solvent and a lithium salt, optionally mixed with additives to retard side reactions.

[0009] Lithium-ion batteries work as follows: during charging, lithium desorbs from the metal oxide and inserts into thermodynamically unstable graphite. During discharge, this process is reversed and lithium ions are inserted into the lithium metal oxide.

[0010] As lithium-ion batteries are used, their capacity decreases due to aging and they must be recycled.

[0011] Traditionally, battery recycling involves several steps: - a pre-treatment process including a decomposition stage and a safety stage; - Thermal and / or hydrometallurgical treatments to recover the various valuable materials and metals contained in these batteries and accumulators Includes.

[0012] But in some situations: - Many accumulators or batteries that are recycled may still be at least partially charged, and their shattering can create sparks that can cause serious fires or even explosions, especially in primary lithium batteries (Li-SOCl2). - The cell may be damaged, e.g., if metallic lithium is deposited on the anode, it is highly reactive when exposed to air or water. can complicate recycling.

[0013] Therefore, end-of-life and / or damaged electrochemical systems to be recycled must be treated with great care.

[0014] Therefore, currently the main problem lies in securing and opening these electrochemical systems (primary and secondary) containing lithium.

[0015] In fact, if the seal is lost, electrolyte, toxic, flammable, and corrosive products leak out, not only in liquid but also in gaseous form. This generates vapors that, when mixed with air, can form an explosive atmosphere (ATEX). The explosive atmosphere can ignite upon contact with a spark ignition source or a hot surface. Ignition can then cause an explosion, resulting in thermal and pressure effects. Furthermore, electrolyte salts such as lithium hexafluorophosphate (LiPF), lithium tetrafluoroborate (LiBF), lithium perchlorate (LiClO), and lithium hexafluoroarsenate (LiAsF) can emit particularly toxic and corrosive fumes containing phosphorus, fluorine, and / or lithium. For example, the formation of hydrofluoric acid (HF) can occur during the thermal degradation of Li-ion batteries.

[0016] Currently, various opening methods are based on processes including, for example, flame firing, immersion in liquid nitrogen, immersion of the cell in a saline solution (brine), or opening under an inert atmosphere.

[0017] However, these methods have many drawbacks. For example, thermal methods cause serious problems with gas emissions, especially greenhouse gases, which are harmful and dangerous to humans and the environment. In addition, the required thermal energy and gas treatment significantly affect the economic balance of these methods.

[0018] Wet grinding methods pose significant safety hazards related to the hydrogen evolved during the grinding of the batteries and generate waste fluids, the latter of which has a significant impact on the economic balance of these methods.

[0019] Continuing to use inert gas for battery opening poses significant economic and technical problems. The use of inert gas does not inert the battery, but merely controls the gas atmosphere during waste opening. A complementary process, typically using aqueous solutions, is required to react the lithium and inertize the system. This inevitably leads to the generation of H2, heat, and air, which poses safety issues (risk of explosion). Controlling the reaction rate to reduce these risks has a significant impact on processing speed.

[0020] Finally, discharging in a salt solution does not solve the safety and cost issues. When discharging a battery in a salt solution (brine), its initial voltage exceeds the electrolysis voltage of water, generating gases such as hydrogen and oxygen. These gases must be vented to prevent explosions (irreversible consumption reactions associated with the electrolysis of water). In addition, there are cost issues, on the one hand, due to the very large amounts of water consumed, and, on the other hand, due to the measures required to avoid an explosive atmosphere (ventilation and large amounts of water commensurate with the amount of waste).

[0021] Therefore, it has recently been proposed to open or discharge these generators in an ionic liquid medium.

[0022] Document EP 3 948 994 A1 describes a method for neutralizing an electrochemical generator, which method comprises a discharging step in which the electrochemical generator is placed in contact with a solution of an ionic liquid comprising a solvent ionic liquid and so-called oxidising redox species capable of being reduced at the negative electrode, in order to discharge the electrochemical generator.

[0023] However, such a method cannot be carried out to treat defective batteries / cells, for example those with corroded terminals, or cells equipped with a current interrupt device (CID). In fact, a CID is a mechanical switch present in the accumulator that makes it possible to block access to the battery's terminals, thus making electrical or chemical discharge impossible.

[0024] Document EP 3 948 993 A1 describes a method for opening electrochemical generators by grinding. This method involves grinding the electrochemical generator in an ionic liquid solution containing a solvent ionic liquid and a so-called oxidized redox species that can be reduced at the negative electrode. The electrochemical generator can be discharged simultaneously with the grinding.

[0025] Although this method in an ionic liquid medium can simultaneously solve the problems of ensuring the safety and environmental constraints of accumulators and batteries, it requires complete immersion, which limits the cost (CAPEX and processing speed) of the method. This complicates the method, since batteries become reactive as soon as they are opened. In addition, contamination of the bath by the battery electrolyte is unfavorable for the sustainability and / or efficiency of the method.

[0026] CN 110690520 A describes a method for cutting and disassembling lithium battery modules using a cutting and disassembly device. The lithium battery module is transported sequentially through a first cutting station and then a second cutting station, both of which are equipped with a cutting device. While the lithium battery module is being cut at these stations, the cutting zone must be sprayed with water to cool it and make it flame-retardant. After cutting, the module is transferred to a winding body discharge station equipped with a winding body removal device. This device pushes the winding body into a water bath. The winding body is immersed in water for a set time, so that any residual charge on the winding body is removed, and the metallic lithium deposited on the negative electrode sheet reacts with water during multiple charge-discharge cycles. [Prior art documents] [Patent documents]

[0027] [Patent Document 1] European Patent Application Publication No. 3948994 [Patent Document 2] European Patent Application Publication No. 3948993 [Patent Document 3] Chinese Patent Application Publication No. 110690520 Summary of the Invention [Problem to be solved by the invention]

[0028] The object of the present invention is to propose a method that makes it possible to overcome the drawbacks of the prior art, in particular to ensure the safety of electrochemical generators, which method should be easy to industrialize. [Means for solving the problem]

[0029] To this end, the present invention provides a method for opening and discharging an electrochemical generator (e.g., a Li-ion battery) comprising a negative electrode containing lithium or sodium and a positive electrode optionally containing lithium or sodium, the method comprising the following successive steps: - opening the electrochemical generator using a cutting element, preferably one having an electrical resistance greater than 100 mΩ, carried out while spraying the electrochemical generator with the first solution, at least in the opening zone, - discharging the electrochemical generator by immersing it (partially or completely) in a second solution. The present invention proposes a method including:

[0030] The electrochemical generators to be treated can in particular be cells or modules (combinations of several accumulators), batteries or accumulators. The present invention places particular emphasis on the recycling of batteries and accumulators of the lithium ion type.

[0031] The present invention involves a two-step process: a first step in which the opening of the electrochemical generator is carried out by means of a liquid spray (or a liquid jet), the first solution preventing or mitigating the discharge of the electrochemical generator in order to avoid a rapid discharge that could lead to the risk of fire or explosion of the object; - After the first step, the electrochemical generator is immersed in a second solution to ensure a controlled discharge. This is fundamentally different from the prior art.

[0032] During the opening of the electrochemical generator, a first solution is passed over the electrochemical generator, and at least the portion of the generator to be cut is covered with the first solution. The opening can be performed, for example, under a spray or jet of the first solution.

[0033] This first step allows for heat dissipation when opening.

[0034] The discharging of the electrochemical generator is carried out during the second step by immersion in the second solution, thus making it easier to control the reactivity, and thus the electrochemical generator is passivated or made safe.

[0035] Advantageously, the first solution is one of the following solutions a) to d): a solution a) comprising, preferably consisting of, deionized water, a solution b) comprising, preferably consisting of, an ionic liquid, a solution c) comprising, preferably consisting of, a deep eutectic solvent, - a solution d) comprising, preferably consisting of, an organic solvent is selected from.

[0036] According to a specific embodiment, the first solution is a solution having a resistance greater than 10 ohms, preferably greater than 100 ohms. Even more advantageously, the liquid of the first solution is not an ion conductor. Preferably, the first solution can be, for example, deionized water or an organic solvent. Thus, the ohmic drop prevents the solvent from degrading or reacting with the cell. This is particularly advantageous for avoiding / reducing degradation in the processing of electrochemical generators / modules with large voltages (usually greater than 12 V).

[0037] According to another specific embodiment, the solution used to open the electrochemical generator allows for partial and controlled discharge of the electrochemical generator. The first solution may be reactive. For example, solutions b) to d) may further comprise an electrochemical shuttle. Solution a) may also comprise an electrochemical shuttle. During opening, the discharge of the target is initiated by the introduction of reactive species. To reduce the reactivity of the first stage, a less reactive liquid is preferred. According to this specific embodiment, the first solution may be the same as the second solution.

[0038] Preferably, a first solution having a low or medium viscosity is selected to facilitate subsequent filtration of particles / debris resulting from cutting, for example, the viscosity of the first solution is between 5 cP and 50 cP.

[0039] Advantageously, the second solution is one of the following solutions e) to g): - a solution e) comprising, preferably consisting of, an ionic liquid and an optional electrochemical shuttle, - a solution f) comprising, preferably consisting of, a deep eutectic solvent and an optional electrochemical shuttle, - a solution g) comprising, preferably consisting of, an organic solvent and an electrochemical shuttle; is selected from.

[0040] The electrochemical shuttle may be initially present in the second solution or may be added, for example, after contacting the electrochemical generator with the second solution.

[0041] Advantageously, the first and second solutions are of the following combination: - solution a) and solution f), i.e. the first solution is deionized water and the second solution comprises a deep eutectic solvent, optionally mixed with an electrochemical shuttle; - solution d) and solution f), i.e. the first solution comprises an organic solvent, preferably a glycol solution, such as polyethylene glycol or propylene glycol, and the second solution comprises a deep eutectic solvent, optionally mixed with an electrochemical shuttle; - Solution c) and Solution f), i.e., a first solution comprising a first deep eutectic solvent, optionally mixed with an electrochemical shuttle, and a second solution comprising a second deep eutectic solvent, preferably a second deep eutectic solvent mixed with an electrochemical shuttle. You can choose from:

[0042] According to the latter set, the first deep eutectic solvent and the second deep eutectic solvent may be the same or different.

[0043] Advantageously, the opening and discharging steps are carried out under air.

[0044] Advantageously, the cutting element is a grinder disc or a cutting wire.

[0045] The first step is carried out in an aperture zone (or cutting zone) and the second step is carried out in a discharge zone, preferably the cutting zone being different from the discharge zone.

[0046] Advantageously, between the opening and discharging steps, the generator is moved from the first opening zone (or cutting zone) to the second discharging zone, this movement preferably being carried out under air.

[0047] For example, after the first step is performed, the liquid injection or spraying is stopped and then the electrochemical generator is moved to the discharge zone.

[0048] In general, this method has many advantages, in particular the economic and environmental costs of treating objects can be reduced by performing two distinct steps of opening and then discharging the electrochemical generator.

[0049] The separation of the two opening and discharging steps is particularly advantageous because the opening solution (first solution) is different from the discharging solution (second solution). In fact, contamination of the discharging bath with the battery electrolyte is harmful. In the present case, the contamination occurs essentially during the opening. Therefore, contamination of the discharging bath is limited and discharging is carried out in a third solvent, reducing the method costs (processing costs).

[0050] The first step has the following advantages: - Establishing techniques for opening objects to avoid short circuits; - During the opening of the electrochemical generator, the object is opened under a spray / jet of a liquid capable of cooling it, which favors good heat dissipation in the heat generating zone; - It is very easy to install a system to spray / inject liquid into an electrochemical generator, - Use of low or medium viscosity opening fluids to facilitate filtration of debris / particles exiting the opening; - By using a liquid with low reactivity to the object to be treated, discharge reactions of the object can be avoided or significantly reduced. This reduces deterioration of the opening liquid, keeps the object stable in the air, and allows it to be moved with minimal risk. - reducing the costs of the process by using liquids that are less expensive in terms of their properties and formulation compared to discharge liquids; - Contamination by particles and battery electrolyte occurs substantially in the first solution, reducing the economic impact in terms of losses over multiple processing cycles (aging, training) It has.

[0051] The second step has the following advantages: - Safely discharge electrochemical generators, - The second solution can be used to discharge multiple electrochemical generators simultaneously or sequentially; - By carrying out a discharge process that avoids violent reactions with water and / or air, not only are the issues regarding the management of hydrogen, oxygen and heat, and therefore of explosive atmospheres, avoided (safety, waste disposal, additional economic costs), but the use of large amounts of water, and therefore the disposal of aqueous waste, is also avoided. The use of ionic liquids also prevents corrosion of electrochemical generators. - The discharge does not damage the object and does not consume any reagents; - Discharge is controlled by the properties of the components of the ionic liquid solution, so that discharge can be carried out extremely quickly (e.g., in less than one hour); - the absence of thermal treatment avoids the problems associated with the emission of gases (e.g. greenhouse gases or other gases harmful and dangerous to humans and the environment), in particular the problems associated with their treatment, reducing the economic and energy costs of the process; - Electrochemical generator safety is easy to implement It has.

[0052] Other features and advantages of the present invention will become apparent from the following additional description.

[0053] Of course, this additional description is merely illustrative of the scope of the present invention and should not be construed as limiting this scope in any way.

[0054] The invention will be better understood from the description of exemplary embodiments given for purely informative and non-limiting purposes, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0055] [Figure 1] 1 is a schematic cross-sectional view of an installation for carrying out the method according to a specific embodiment of the present invention; [Figure 2] 4 is a graph showing curves for monitoring the voltage and temperature of a generator before carrying out a method, after opening and discharging the generator, according to a specific embodiment of the present invention; [Figure 3]10 is a graph showing curves for monitoring voltage and temperature in a method of simultaneously performing cutting and discharging by immersion in a discharge solution. [Figure 4] 1 is a graph showing curves for monitoring voltage and temperature in a method according to a specific embodiment of the present invention, in which cutting is performed under a spray of a reaction liquid (first solution), followed by waiting in air, and finally immersion in a reaction liquid (second solution) for discharge. DETAILED DESCRIPTION OF THE INVENTION

[0056] The various parts shown in the drawings are not necessarily to uniform scale in order to make the drawings easier to read.

[0057] The various possibilities (alternatives and embodiments) are to be understood as not being mutually exclusive and can be combined together.

[0058] Furthermore, in the following description, terms that depend on the orientation of a structure, such as "top" or "bottom" of a structure, are applied with the structure being oriented in the manner shown in the figures.

[0059] Electrochemical Generator In the following, the electrochemical generator is, for example, a battery (also called accumulator battery) including an accumulator, a cell, or a number of accumulators, which are connected in series or parallel to form battery modules or electric cells according to the nominal operating voltage and / or the amount of energy to be supplied. In particular, the electrochemical generator may be a Li-ion accumulator.

[0060] The opening and discharging method relates to all electrochemical systems of the accumulator or battery type, treated separately or in combination.

[0061] These various electrochemical devices may be of the metal ion type, such as lithium ion or sodium ion, or Li metal type.

[0062] The electrochemical device can also be a primary system such as Li / MnO2 or a flow battery (redox flow battery).

[0063] Advantageously, an electrochemical generator having a potential exceeding 1.5 V is selected.

[0064] The generator may include a plurality of electrochemical cells, each cell including a first electrode, herein the anode, and a second electrode, herein the cathode, a separator, and an electrolyte. According to another embodiment, the first electrode and the second electrode may be reversed.

[0065] The anode (negative electrode) is preferably graphite which can be deposited on a copper sheet mixed with a carbon-based material, for example, a PVDF type binder. Also, the anode may be a mixed oxide of lithium such as lithium titanate Li4Ti5O 12 (LTO), or a mixed oxide of sodium such as sodium titanate for a Na ion battery. Also, according to the selected technology, it can be a lithium alloy or a sodium alloy.

[0066] The cathode (positive electrode) is a lithium ion insertion material for a Li ion battery. This may be a layered oxide of the LiMO2 type where M represents a transition metal, a phosphate LiMPO4 having an olivine structure, or a spinel compound LiMn2O4. For example, a positive electrode made of LiCoO2, LiMnO2, LiNiO2, Li3NiMnCoO6, LiNi x Co 1-x O2 (0 < x < 1), or LiFePO4 is selected.

[0067] The cathode (positive electrode) is a sodium ion insertion material for a Na ion battery. It can be composed of a sodium oxide-based material containing at least one transition metal element, a sodium phosphate-based material or a sodium sulfate-based material containing at least one transition metal element, a sodium fluoride-based material, or a sulfide-based material containing at least one transition metal element.

[0068] The intercalating material can be mixed with a polyvinylidene fluoride based binder and deposited onto an aluminum sheet.

[0069] The electrolyte contains lithium salts (e.g., LiPF6, LiBF4, LiClO4) or sodium salts (e.g., N3Na), depending on the selected battery technology, dissolved in a mixture of non-aqueous solvents, e.g., binary or ternary mixtures, selected, for example, from solvents based on cyclic carbonates (ethylene carbonate, propylene carbonate, butylene carbonate), linear or branched (dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, dimethoxyethane) in various proportions.

[0070] Alternatively, the electrolyte may be a polymer electrolyte comprising a polymer matrix made of organic and / or inorganic materials, a liquid mixture containing one or more metal salts, and an optional mechanical reinforcement material. The polymer matrix may comprise one or more polymeric materials selected from, for example, polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polyvinylidene hexafluoropropylene (PVDF-HFP), or poly(N-vinylimidazolium) bis(trifluoromethanesulfonylamide), N,N-diethyl-N-(2-methoxyethyl)-N-methylammonium bis(trifluoromethylsulfonyl)imide (DEMM-TFSI)-based poly(ionic liquids).

[0071] The cell may be wound on itself about a winding axis or may have a laminated structure.

[0072] A case, for example a polymer pocket, or a metal package, for example a steel metal package, can ensure the hermeticity of the battery.

[0073] Each electrode is connected to a current collector that passes through the case, forming a terminal (also called an output terminal, electrical pole, or electrical terminal) on the outside of the case. The current collector has two functions: to provide mechanical support for the active material and to ensure electrical conduction to the cell's terminals. The terminals, also called electrical poles or electrical terminals, form the output terminals and are intended to be connected to an "energy receiver."

[0074] Method for opening and discharging an electrochemical generator - Patent Application 20070122997 As shown in FIG. 1, a method for opening and discharging an electrochemical generator includes the following steps: - opening the electrochemical generator 10 using the cutting element 20, the opening being carried out while spraying the first solution 100 onto the part of the electrochemical generator 10 to be opened; - discharging the electrochemical generator by partially or even completely immersing it in the second solution 200; Includes.

[0075] 1st process (opening process) In a first step, the electrochemical generator 10 is at least partially or even completely opened, which allows access to the interior of the electrochemical generator.

[0076] By opening, it is meant at least accessing the electrodes so that the electrochemical generator can be discharged in step 2. For example, opening involves opening the case to access the electrodes.

[0077] The cutting operation, carried out in the presence of an inert liquid, avoids violent reactions with water and / or air. The inert liquid ensures safe opening of the battery / accumulator and allows the battery / accumulator to be discharged during the opening while the cutting tool is introduced into the active core of the material. Finally, the inert liquid favors a cooling medium, allowing heat to be removed during the discharge process.

[0078] The inert liquid is sprayed onto the parts to be cut, for example via a device 30 capable of spraying the first solution 100 onto an electrochemical generator 100 or delivering a jet or spray of the first solution 100. The flow rate is, for example, between 25 L / min and 50 L / min.

[0079] This first step can be carried out on a grid or sieve 40 to filter the first solution after cutting of the electrochemical generator 10, so that particles / debris resulting from cutting can be separated from the first solution 100 and recycled.

[0080] The inert liquid helps maintain a controlled atmosphere (air, water) and acts as a cutting fluid (lubrication and cooling of the cutting zone).

[0081] Advantageously, this first step avoids or significantly limits discharge phenomena after opening of the object. Opening under spray / jet of liquid controls heat dissipation during the opening.

[0082] The first step can be carried out at a temperature ranging from 5° C. to 80° C., preferably from 20° C. to 60° C., and more preferably at room temperature (20 to 25° C.). The first step is preferably carried out at atmospheric pressure (or 1 bar or 101.325 Pa).

[0083] For greater safety, the first step can be carried out under an inert atmosphere, such as argon, carbon dioxide, nitrogen or one of their mixtures.

[0084] For example, the opening process can be coupled with a gas atmosphere control system (inert atmosphere or a correctly dimensioned extraction system) that allows for control of the oxygen concentration. In this way, the assembly is secured (with respect to the fire triangle) and allows for the opening of batteries and accumulators while managing the gas evolution induced by the opening of the cells.

[0085] Preferably, the first step is carried out under air.

[0086] Advantageously, at the end of the opening step, the spraying of the first solution 100 onto the electrochemical generator 10 is stopped.

[0087] The first step is carried out in a first zone, called the cutting zone or opening zone (zone Z1 in FIG. 1).

[0088] The discharge step (second step) is carried out in a second zone called the discharge zone (zone Z2 in FIG. 1).

[0089] Between the opening step and the discharging step, an intermediate step is carried out in which the electrochemical generator is moved from the first zone Z1 to the second zone Z2. For example, the intermediate step may involve moving the electrochemical generator from the zone Z1 containing the spraying means 30 to the tank 50. This intermediate step is preferably carried out under air.

[0090] 2nd process (discharge process) The discharging step consists in partially or preferably completely discharging the electrochemical generator by immersion, which results in the inactivation or safeguarding of the object. As mentioned above, this second step is preferably carried out in the discharge zone (zone 2 in FIG. 1).

[0091] The second step is preferably carried out under air and advantageously, the second step is carried out under atmospheric pressure.

[0092] During this second step, the generator 10 is partially or completely immersed in a second solution, whereby electrical discharge occurs due to immersion in the liquid, causing a chemical reaction.

[0093] The discharge is carried out in a device 50 containing the second solution 200, for example in a tank.

[0094] Advantageously, the thermal energy absorbed during the resistive discharge process can be recovered in a heat exchanger. A continuous circulation between the discharge reactor and the heat exchanger would therefore make it possible to operate a continuous process of discharge and energy recovery. Advantageously, the temperature of the bath into which the accumulator is placed does not exceed 60°C, in order to avoid internal degradation reactions of the battery electrolyte. In this way, runaway processes that could lead to degradation and / or explosion can be avoided.

[0095] Cutting elements for carrying out the opening process The opening is performed by a cutting element 20 (which may also be called a cutting tool) that is not electrically conductive. The cutting element 20 has a sufficiently high resistance to avoid a direct short circuit that would lead to an explosion of the cell. In other words, the cutting element 20 has very low electrical conductivity.

[0096] In particular, we select tools that have resistances that are typically greater than 100 mΩ, for example, between 100 mΩ and 1 kΩ.

[0097] The conductivity of the cutting element is the average conductivity apparent through the sample being cut, which depends on the ratio of insulating to conductive zones, the rotational speed, the advance speed of the grindstone, etc.

[0098] This resistance is the average resistance of the cutting element, at least the part of the cutting element that is intended to penetrate the sample to cut it. The resistance can be measured with a multimeter by placing the sample between two identical conductive plates.

[0099] The preferred technique is one that avoids excessive deformation (crushing, material spreading into adjacent materials, etc.) which would lead to direct and uncontrolled short circuiting leading to thermal runaway and cell explosion.

[0100] By cutting tool is meant a tool capable of comminuting, preferably cutting, material in order to completely or partially open an object in the presence of a liquid capable of cooling the zone subjected to mechanical heating.

[0101] Non-conductive piercing tools may be, non-exhaustively, guillotine-type tools (blades), saws (circular saws, band saws), wire, ultrasonic, drill, abrasive liquid jet cutting tools (containing non-conductive abrasive particles). They may also be non-conductive cutting knives or micro-cutting knives. Advantageously, the cutting element is a cutting wire, a grinding wheel, a circular saw blade (also called a disk) or a band saw.

[0102] This operation is carried out in the presence of the first solution 100 to avoid heat generation and ignition due to reaction of the organic electrolyte of the battery with air, which could lead to fire or explosion.

[0103] The cutting element 20 includes a base support that provides mechanical properties to the cutting element.

[0104] The substrate support may be electrically conductive or electrically insulating. The substrate support may be metallic, resinous, or rubber type.

[0105] The substrate support is covered with an abrasive zone, which has a hardness adapted to the object and material being processed.

[0106] The abrasive zone may be made of, for example, sandstone, emery, diamond, silicon carbide and / or alumina.

[0107] Preferably, the polishing zone is formed by abrasive grains.

[0108] Preferably, the substrate support is covered with an abrasive zone that provides the tool with mechanical properties and a conductive zone that provides the tool with electrical properties.

[0109] The conductive zones are formed, for example, by conductive particles.

[0110] The conductive zones are made, for example, from a metal or metal alloy. For purposes of example, the conductive zones may be copper, iron, steel and / or aluminum, or more broadly, any electrical conductor.

[0111] The conductive zones can be formed by metal particles or metal wires.

[0112] The abrasive and / or conductive particles are preferably particles having dimensions ranging from, for example, a few micrometers to a few centimeters.

[0113] The abrasive grains and / or conductive particles are advantageously mechanically held to the support by a binder, which may be a resin, rubber, silicate, clay, or ceramic.

[0114] The abrasive zones and / or conductive zones may be distributed in a regular or random manner on the substrate.

[0115] The abrasive zones and / or conductive zones may be continuous or discontinuous.

[0116] According to a first alternative embodiment, the opening of the electrochemical generator is carried out by grinding with a wire, which comprises a solid wire-like base that provides mechanical properties, the abrasive properties being provided by adding abrasive grains with a hardness adapted to the object and material to be processed.

[0117] According to a second alternative embodiment, the openings in the electrochemical generator are performed by grinding with a grinder, the grinder's disk comprising a circular base support having first and second parallel major surfaces and side surfaces (also called edges) connecting the two major surfaces.

[0118] The support may be of metallic, plastic or rubber type and is advantageously covered with an electrically insulating abrasive zone and an electrically conductive zone.

[0119] For grinding wheels that include an abrasive zone (preferably abrasive grains) and a conductive zone (preferably conductive wires or particles), various configurations are possible.

[0120] The abrasive zones and conductive zones are, for example, randomly distributed.

[0121] The abrasive and conductive zones can be distributed in a controlled manner.

[0122] According to an alternative embodiment, the abrasive and conductive zones are arranged in a controlled manner to form alternating abrasive and non-abrasive zones.

[0123] According to another alternative embodiment, the conductive zones may be distributed concentrically about the center of the grinding disc.

[0124] According to another alternative embodiment, the conductive zones may be randomly or non-randomly arranged along one or more radii or one or more diameters.

[0125] According to another alternative embodiment, the conductive zones may be located only on the outer periphery of the grinding disc.

[0126] According to another alternative embodiment not shown, the conductive zones are arranged at the ends of the grinding disc.

[0127] The alternation of abrasive and conductive zones can be obtained through coatings formed by thin film deposition techniques such as physical vapor deposition (or PVD), atomic layer deposition (ALD), chemical vapor deposition (or CVD), spin coating, or coating techniques such as dip coating.

[0128] Suitable electrical resistance can also be imparted via a conductive fabric deposited on the exterior surface of the cutting tool, thus separating the mechanical property (abrasiveness, controlled hardness imparted by the abrasive grains contained in the resin) and the electrical property (suitable resistance imparted by the exterior fabric).

[0129] The electrical resistance can also be adjusted by the cutting liquid and operating conditions (temperature, viscosity of the liquid, polishing rate, replacement of the liquid, etc.).

[0130] First Solution 100 The first solution 100 favors cooling of the electrochemical generator 10 and allows for the evacuation of heat during the opening process. To do this, the first solution 100 can be optionally cooled. The first solution can be sprayed / sprayed onto the opening zone and / or zones of the electrochemical generator 10. The first solution can be sprayed / sprayed so as to completely cover the electrochemical generator 10.

[0131] According to a first alternative embodiment, the first solution is a liquid that may be reactive. The introduction of reactive species initiates the discharge of the object during opening. In certain cases where the solution used to open the electrochemical generator is also the solution used to discharge the electrochemical generator, a less reactive liquid is preferred to reduce the reactivity of the first stage.

[0132] In a second alternative embodiment, the function of the first solution is to stabilize the object and avoid discharge. The first solution advantageously has a resistance greater than 10 ohms, preferably greater than 100 ohms, and even more advantageously, the first solution is not an ion conductor (this is the case for pure water and many organic solvents that do not have ions in solution to begin with). Thus, the ohmic drop avoids degradation of the solvent and its reaction with the electrochemical generator 10. This is particularly advantageous for avoiding / reducing degradation due to the operation of the electrochemical generator 10 with high voltages (usually greater than 12 V).

[0133] The properties of the liquid are defined to limit the discharge of the battery and control its reactivity. The absence or very low reactivity ensures control of the object, facilitating its movement under atmospheric conditions and ensuring time for safe movement. The opening solution is inherently uncomplex (nature of components) and inexpensive, so contamination inherent to opening a battery (e.g., leakage of battery electrolyte into the liquid) is less of a concern for this method. Preferably, the first solution is biodegradable, inexpensive, and / or has low volatility. Preferably, the first solution does not cause contamination to the second solution.

[0134] Preferably the liquid used is not highly viscous to facilitate filtration of the apertured particles / particles.

[0135] Preferably, the first solution 100 is a solution of: - a solution containing deionized water, - a solution comprising an ionic liquid, - solutions containing deep eutectic solvents, - Solutions containing organic solvents is selected from.

[0136] By ionic liquid is meant an association comprising at least a cation and an anion that produces a liquid with a melting point below or close to 100°C.

[0137] Deep eutectic solvents (or DES) are different from ionic liquids. The term DES is used for media other than ionic liquid media. Deep eutectic solvents are formed by mixing two or more compounds in the exact proportions corresponding to their eutectic point. The melting point is significantly lower than that of each component, allowing the mixture to remain liquid at room temperature. The fact that most of these solvents are liquid at room temperature makes them easy to use. The synthesis of DES is simple and clean compared to ionic liquids, which require several steps for chemical synthesis and purification. DES is simply made by heating the components that make up the DES in the appropriate proportions and mixing them until a homogeneous, clear liquid is obtained. These components are pairs of hydrogen bond donors and acceptors of this bond.

[0138] These eutectics have the general formula [Cat]+ .[X]- .z[Y], where [Cat]+ is a cation (generally ammonium), [X]- is a halide anion (generally Cl-), [Y] is a Lewis or Bronsted acid that can be complexed by the anion X-, and z is the number of molecules Y.

[0139] These eutectic types are divided into three categories according to the properties of Y. Type 1 eutectic: Y = MClx, e.g., M = Fe, Zn, Sn, Fe, Al, Ga Type 2 eutectic: Y = MClx.yH2O, e.g., M = Cr, Co, Cu, Ni, Fe Type 3 eutectic: Y = RZ, where R corresponds to the carbon chain and Z is a chemical functional group, such as CONH2, COOH, OH, etc.

[0140] As for the solvent, preference may be given to using bio-based solvents (methyl esters, N,N-dimethyldecanamide, N,N-dimethyldec-9-enamide, etc.), acetates (hexyl acetate, butyl acetate, etc.). These examples are not exhaustive. Water can also be used. A low ionic conductivity is preferred to avoid the formation of hydrogen and oxygen.

[0141] For example, if the second solution 200 contains a deep eutectic solvent, the first solution 100 may contain a component of a DES. More generally, one of the liquid components of the DES is selected to be a hydrogen bond donor. The latter must necessarily be a liquid. Preferably, the latter has low viscosity and little or no electrical conductivity.

[0142] By way of example, when the second solution comprises an ethaline-based DES, the first solution advantageously comprises ethylene glycol.

[0143] Ethylene glycol (EG) is a non-ionic liquid with low vapor pressure and very low viscosity, and is a component of ethanol. Alternatively, propylene glycol may be used.

[0144] The first solution may consist of a liquid phase (water, solvent, ionic liquid, deep eutectic solvent). The first solution 100 may further comprise an electrochemical shuttle.

[0145] The electrochemical shuttle, also called a redox mediator or redox couple, is an oxidant / reductant pair (Ox / Red) in solution, where the oxidant can be reduced at the anode (negative electrode) and the reductant can be oxidized at the cathode (positive electrode). The oxidation of the reductant and the reduction of the oxidant can form new oxidant / reductant species and / or regenerate species originally present in the solution. This method is economical because by ensuring that the redox couple in the solution simultaneously and in parallel undergoes redox reactions at the electrodes / terminals of the electrochemical generator, no reagents are consumed and the solution can be used to open (or discharge, if used during the second step) multiple electrochemical generators.

[0146] During the opening of an electrochemical generator, the redox couple reacts with internal components, reducing the potential difference between the electrodes (anode and cathode). This internal discharge also contributes to the safety of the electrochemical generator by reducing the chemical energy (and therefore the potential difference) of the electrodes and reducing the effects of internal short circuits.

[0147] Advantageously, the pair of redox species is a metal pair, preferably Mn 2+ / Mn 3+ , Co 2+ / Co 3+ , Cr 2+ / Cr 3+ , Cr 3+ / Cr 6+ , V 2+ / V 3+ , V 4+ / V 5+ , Sn 2+ / Sn 4+ , Ag+ / Ag 2+ , Cu+ / Cu 2+ , Ru 4+ / Ru 8+ or Fe 2+ / Fe 3+, organic molecule pair, Fc / Fc + metallocene pairs such as, for example, Cl / Cl - or Cl - / Cl3 - and the like.

[0148] For example, iron chloride is used.

[0149] Advantageously, the first solution consists of a liquid phase mixed with the electrochemical shuttle.

[0150] Second solution 200 The second solution 200 is a liquid that allows for chemical discharge of the electrochemical generator by immersion. In certain cases, the second solution 200 has the same composition as the first solution 100.

[0151] By discharge liquid is meant a bath containing a liquid composed of ions (ionic liquid solution, DES solution, organic solution) and species that, in synergy with at least one component of the bath, ensure the discharge of the object (battery / accumulator), these species acting as an electrochemical shuttle, thus discharging and securing / passivating the electrochemical generator 10.

[0152] Therefore, there will be at least a liquid composed of ions called an ionic solvent that ensures ionic conductivity of the ions.

[0153] The second solution is preferably the following solution: - a solution comprising an ionic liquid and an optional electrochemical shuttle; - a solution comprising a deep eutectic solvent and an optional electrochemical shuttle; - a solution comprising an organic solvent and an electrochemical shuttle is selected from one of the following:

[0154] The ionic liquid is a solvent ionic liquid, ie, a thermally and electrochemically stable ionic liquid that minimizes the effects of media degradation during discharge events.

[0155] Mixtures of ionic liquids may be used, with the additional ionic liquid enhancing one or more properties with respect to safety and the discharge process.

[0156] For the solvent ionic liquid LI1 and the additional ionic liquid LI2, cations are selected from the imidazolium, pyrrolidinium, ammonium, piperidinium, and phosphonium families, preferably cations with a wide cation window (i.e., a large stability window) that is wide enough to envisage a cathodic reaction that avoids or minimizes degradation of the ionic liquid, provided that the mixing and association conditions between LI1 and LI2 are met (in terms of the nature and concentration of the anions). Advantageously, LI1 and LI2 have the same cation to enhance the solubility of LI2 in LI1.

[0157] Other associations are possible, with ionic liquids (LI1) in which the cation is associated with anions, either organic or inorganic, preferably with anions having a wide anodic window.

[0158] Advantageously, anions are used that simultaneously provide a moderate viscosity, a low melting temperature (liquid at room temperature), good solubility of the ionic liquid with other species in the solution, and do not lead to hydrolysis (degradation) of the ionic liquid.

[0159] More preferably, mixtures LI1 and LI2 are liquid at room temperature.

[0160] The TFSI anion is an example that meets the aforementioned criteria for many associations, such as the use of ionic liquids based on LI1:[BMIM][TFSI] or [P66614][TFSI], the ionic liquid 1-ethyl-2,3-trimethyleneimidazolium bis(trifluoromethanesulfonyl)imide ([ETMIm][TFSI]), the ionic liquid N,N-diethyl-N-methyl-N-2-methoxyethylammonium bis(trifluoromethylsulfonyl)amide [DEME][TFSA], the ionic liquid N-methyl-N-butylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([PYR14][TFSI]), and the ionic liquid N-methyl-N-propylpiperidinium bis(trifluoromethanesulfonyl)imide (PP13-TFSI). The anion can also be based on bis(fluorosulfonyl)imides (FSA or FSI), such as the ionic liquids N-methyl-N-propylpyrrolidinium FSI (P13-FSI), N-methyl-N-propylpiperidinium FSI (PP13-FSI), 1-ethyl-3-methylimidazolium FSI (EMI-FSI), and the like.

[0161] Preferably, the second solution contains DES, which is a low-cost, non-toxic and low-environmental-impact (biodegradable) medium, the toxicity and biodegradability of which are related to the toxicity and biodegradability of its components.

[0162] According to the general formula of the DES given above, preferably, "Y" is an electrochemical shuttle (e.g., iron and Fe 2+ / Fe 3+ Eutectic mixtures can be formed between ionic liquids with chloride anions and metal salts FeCl2 and FeCl3 in various ratios with various cations. When the water content is low, this type of reaction can also be carried out with type II eutectic mixtures, which incorporate water molecules into the metal salt. Type III eutectic mixtures, which associate ionic liquids and hydrogen bond donor species (Y) with mixtures of the type [LI1] / [Y], where LI1 is a quaternary ammonium and Y is a complexing molecule (hydrogen bond donor) such as urea, ethylene glycol, or thiourea, can also be used.

[0163] The DES may advantageously be choline chloride used in conjunction with an H-bond donor with very low toxicity such as glycerol or urea, thereby ensuring a very low cost and non-toxic DES.

[0164] As an example, choline chloride can be replaced by betaine. These systems have a limited window of electrochemical stability, but can guarantee immersion and passivation of open batteries.

[0165] The shuttle may be initially present in the second solution 200 or may be added to the second solution 200 later.

[0166] The electrochemical shuttle can be used to secure multiple electrochemical generators in series and / or in admixture.

[0167] The redox species allow the electrochemical generator to be deeply or even completely discharged.

[0168] Advantageously, the pair of redox species is one of the pairs previously described for the first solution 100 .

[0169] For example, iron chloride is used.

[0170] The second solution 200 may be stirred.

[0171] The first solution 100 and / or the second solution 200 may further comprise one or more active species selected from, for example, fire extinguishing agents, flame retardants to prevent thermal runaway, battery safety agents (electrochemical shuttles or redox mediators), salt stabilizers, viscosity stabilizers, solubility stabilizers, hydrophobic stabilizers, and conductivity stabilizers.

[0172] The fire extinguishing agent and / or flame retardant may be an alkyl phosphate such as trimethyl phosphate or triethyl phosphate, or may be fluorinated such as a fluorinated alkyl phosphate (e.g., tris(2,2,2-trifluoroethyl)phosphate). The concentration may be between 80% and 5% by weight, preferably between 30% and 10% by weight.

[0173] Among the first and second solution options, preferably: - the first solution is formed by a solvent and the second solution is a DES mixed with an electrochemical shuttle, or the first solution is formed by a DES mixed with an electrochemical shuttle, and the second solution is a DES mixed with an electrochemical shuttle, the first and second solutions being advantageously identical;

[0174] Even more preferably: the first solution is a glycol, for example ethylene glycol or propylene glycol, and the second solution is a mixture of a DES (preferably choline chloride / ethylene glycol or choline chloride / betaine) and an electrochemical shuttle; or The first solution is a mixture of a DES (preferably choline chloride / ethylene glycol or choline chloride / betaine) and an electrochemical shuttle, and the second solution is a mixture of a DES (preferably choline chloride / ethylene glycol or choline chloride / betaine) and an electrochemical shuttle. The first and second solutions may advantageously be identical.

[0175] This method, which is the subject of the present invention, makes it possible to discharge the objects before recycling them by one of pyrometallurgy, hydrometallurgy or a combination thereof.

[0176] The fractionation and decomposition steps can be carried out in advance. For example, the present invention provides a method for the separation and decomposition of a waste product by the following steps: 1- Separation 2- Decomposition 3- Application of the present invention 4- Recycling via conventional routes (pyrometallurgy, hydrometallurgy, etc.) The present invention can be implemented in a method for recycling an electrochemical generator comprising: [Example]

[0177] Illustrative and Non-Limiting Example of an Embodiment Example 1: Opening of the cell in an ethylene glycol medium and discharging in a choline chloride / ethylene glycol medium A prismatic Li-ion cell of NMC chemistry with a nominal capacity of 63 Ah is charged to 100%. The cell is subjected to a crushing-type cut performed in an uncontrolled atmosphere (ambient air) using a resinoid grinding wheel containing an abrasive (Al2O3). The cutting liquid (or first solution 100) is ethylene glycol (EG). This liquid is non-conductive and has a viscosity of 18 cP. The EG liquid is sprayed onto the cutting zone at a flow rate of 10 L / min. The opening operation with the grinding wheel results in a 500 μm thick, approximately 5 cm thick cut. 2 The cutting operation is carried out for 4 minutes, then cutting is stopped and the injection / spraying of the liquid is stopped.

[0178] Figure 2 shows that the cell voltage remains completely constant not only during the cutting stage under ethylene glycol injection, but also after the cutting stage and after EG injection is stopped (labeled as post-cut in Figure 2). The treatment time was intentionally extended to 1 hour to clarify the stability of the cell under air over a very long period of time.

[0179] In parallel, the cell temperature is measured to ensure that the cell is not generating heat or reacting.

[0180] After one hour, the cell is immersed in a second solution 200 formed by mixing choline chloride and ethylene glycol in a 1:3 molar ratio and adding an iron chloride-based electrochemical shuttle. The viscosity of the mixture is approximately 40 cP. This entire process is carried out at room temperature and atmospheric pressure without recirculating or thermally conditioning the liquid (conditions that would degrade it). The cell is then discharged in the discharge solution until the state of charge reaches 0%.

[0181] This technique not only allows the cell to be opened without causing an explosion, but also stabilizes the cell under atmospheric pressure for cell transfer in air, after which the cell can be discharged using a discharge fluid.

[0182] For comparison, a test was performed with a disconnected cell fully immersed in a discharge solution (a 1:3 molar mixture of choline chloride and ethylene glycol with the addition of an iron chloride-based electrochemical shuttle). Figure 3 shows the voltage and temperature changes. A voltage drop and temperature increase for the lithium-ion battery are observed.

[0183] (Example 2: Opening of the module in a choline chloride and ethylene glycol medium and discharging in a choline chloride and ethylene glycol medium) The Li-ion module with NMC chemistry has a module capacity of 125 Ah and a module voltage of 16.6 V, with each cell of the module being charged to 100% (initial voltage of 3.7 V). The module is in an uncontrolled atmosphere (ambient air) and is subjected to a crushing-type cutting performed using a resinoid grinding wheel containing Al2O3 abrasive. The cutting solution (first solution 100) is a mixture of choline chloride and ethylene glycol in a 1:3 molar ratio, with the addition of an iron chloride-based electrochemical shuttle. This solution is sprayed onto the cutting zone at a flow rate of 10 L / min. The cutting operation with the grinding wheel results in a 500 μm thick, approximately 5 cm thick cut. 2 The cutting operation is carried out for 5 minutes, then cutting is stopped and the spraying of the liquid is stopped.

[0184] Figure 4 shows that the module voltage gradually decreases during the cutting phase and during the stoppage of spraying (marked the waiting phase under air). The stopping phase was intentionally extended to 15 minutes to clarify the temperature changes under air over a long period of time. Measurements of the module temperature show a sufficiently low exotherm to allow processing without explosion or fire in ambient atmosphere (under air) after spraying of the discharge solution has stopped.

[0185] After 15 minutes in air, the module is immersed in a second solution 200 formed by mixing choline chloride and ethylene glycol in a 1:3 molar ratio and adding an iron chloride-based electrochemical shuttle. The viscosity of the mixture is approximately 40 cP. The entire process is carried out at room temperature and atmospheric pressure without recirculating or thermally conditioning the liquid (conditions that would degrade it). The module is then discharged in the discharge solution until each cell reaches a 0% state of charge (a voltage of less than 1 V per cell).

[0186] This technique not only allows the cell to be opened without explosion, but also stabilizes it under atmospheric pressure for transport under air, after which it can be discharged using a discharge fluid. [Explanation of symbols]

[0187] 10 Electrochemical Generator 20 Cutting Elements 30 Spraying means 40 Grate or sieve 50 Tank 50 equipment 100 First Solution 200 Second Solution

Claims

1. A method for opening and discharging an electrochemical generator (10) comprising a negative electrode containing lithium or sodium and a positive electrode optionally containing lithium or sodium, comprising the following successive steps: - opening the electrochemical generator (10) using a cutting element (20), preferably a cutting element (20) having an electrical resistance greater than 100 mΩ, said opening being carried out while spraying the electrochemical generator (10) with a first solution (100); and - discharging the electrochemical generator by immersing it in a second solution (200); Including, said first solution (100) is one of the following solutions a) to d): a) a solution of deionized water; b) a solution comprising an ionic liquid; c) a solution comprising a deep eutectic solvent, and d) A solution containing an organic solvent is selected from one of said second solution (200) is one of the following solutions e) to g): e) a solution comprising an ionic liquid and an optional electrochemical shuttle; f) a solution comprising a deep eutectic solvent and an optional electrochemical shuttle; and g) A solution containing an organic solvent and an electrochemical shuttle. selected from one of method.

2. The method of claim 1, wherein the first solution (100) further comprises an electrochemical shuttle.

3. 3. The method according to claim 1 or 2, characterized in that the second solution (200) is identical to the first solution (100).

4. 3. The method of claim 1 or 2, characterized in that the first solution (100) comprises water and the second solution (200) comprises a deep eutectic solvent and an optional electrochemical shuttle.

5. 3. The method of claim 1 or 2, characterized in that the first solution (100) comprises an organic solvent, preferably a solution of a glycol, for example polyethylene glycol or propylene glycol, and the second solution (200) comprises a deep eutectic solvent, preferably a deep eutectic solvent mixed with an electrochemical shuttle.

6. 3. The method of claim 1 or 2, characterized in that the first solution (100) comprises a first deep eutectic solvent, optionally mixed with an electrochemical shuttle, and the second solution (200) comprises a second deep eutectic solvent, preferably mixed with an electrochemical shuttle, the first eutectic solvent being the same as or different from the second eutectic solvent.

7. 7. The method according to claim 1, wherein the steps of the method are carried out under air.

8. 8. A method according to any one of claims 1 to 7, characterized in that the cutting element (20) is a grinder disc or a cutting wire.

9. 9. The method according to claim 1, wherein between the opening step and the discharging step, the generator is moved from a first opening zone to a second discharging zone, said moving being preferably carried out under air.

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