Process for disassembling electrochemical components or elements

Abstract

Method for disassembling electrochemical components or elements The present invention relates to a method for disassembling a stack to be disassembled, the stack to be disassembled comprising at least a first layer and at least a second layer, at least one or the other of the first layer or the second layer being an electrochemically active layer, the method comprising a step of laser shock peening a first face of an assembly, the assembly comprising at least the stack to be disassembled and the first face of the assembly being oriented towards the laser source, and the stack to be disassembled having a first face oriented towards the laser source and a second face opposite the first face, the second face of the stack to be disassembled being at least partially free or being in contact with a soft support having a hardness less than or equal to 80 Shore A. Figure for abstract: None

Description

Title of the invention: Method for disassembling electrochemical components or elements

[0001] The present invention relates to a method for disassembling electrochemical components or elements using a laser shock hammering technique.

[0002] One of the biggest challenges facing the battery industry today is battery recycling, as many technical and technological barriers are slowing down the development of effective methods.

[0003] The first step in any recycling process is the isolation of each component of the recycled object. However, existing batteries have different types of design (format, chemistry, technology), which require specific approaches.

[0004] Currently, liquid electrolyte batteries are mainly disassembled (unscrewed and / or unsoldered), emptied of their electrolyte and each component is sorted: the positive electrodes, the negative electrodes and finally the metal parts. The development of new technologies such as solid electrolyte and / or bipolar electrochemical elements induce new manufacturing processes such as compaction, co-lamination, densification or bonding between materials of different natures, these processes being incompatible with the existing end-of-life recovery processes of the battery. These new processes therefore have the disadvantage of making it impossible to disassemble the electrochemical element (or electrochemical cell) by conventional methods.

[0005] There is also a "blast furnace" type melting process for traditional Li-Ion type electrochemical elements which allows the recovery of the different metals in liquid phase (pyrometallurgy). Finally, there are certain chemical recycling methods (hydrometallurgy, for example)

[0006] Laser shock peening (LSP) is an industrial process used to densify the surface of metallic materials, such as stainless steel or titanium, for example. It consists of hammering a sacrificial layer applied to the surface to be densified, so as to create a plasma that will generate a high-pressure wave capable of densifying the material on the surface before dissipating into the depths of the material. This technology can reach a pressure of up to 20 GPa, making it a very powerful process.

[0007] However, this process is a priori not very suitable for the field of lithium battery recycling for several reasons:

[0008] - the presence of water in the laser hammering process, used as a medium confinement to contain the plasma generated by the laser, totally incompatible with the vast majority of electrochemistries used for the manufacture of electrochemical elements, but also unusable in the "dry rooms" where electrochemical elements are produced.

[0009] - the very nature of the electrode which by definition is thin, flexible, porous, com compressible and above all fragile, the opposite of the properties of materials currently treated by this process.

[0010] For example, CN 116689951 proposes a method for disassembling a battery using a laser, in which the battery is immersed in water. The laser generates a plasma in the immersion water, which will generate a pulsed cavitation phenomenon that will generate a shock wave that will allow the battery to be disassembled. In this method, the water acts as a confinement medium, which directs the shock wave towards the battery, but, as mentioned above, the presence of water is totally incompatible with the objective of recovering the battery materials for recycling, in particular the active materials, except for certain specific active materials such as, for example, carbons or graphites.

[0011] There is therefore a need for a method for separating electrochemically active components or elements, such as the components or elements of a battery, in particular components or elements that are compacted, co-laminated, molded or bonded. In particular, there is a need for a method for recycling battery component or element materials, for example by reusing them in new battery components or elements. In particular, there is a need for such methods to be applicable to all types of batteries. There is also a need for a battery disassembly method that limits contact with certain substances that may present risks to health or the environment.

[0012] The invention therefore relates to a method for disassembling a stack to be disassembled, the stack to be disassembled comprising at least a first layer and at least a second layer, at least one or the other of the first layer or the second layer being an electrochemically active layer, the method comprising a step of laser shock peening (LSP) of a first face of an assembly, the assembly comprising at least the stack to be disassembled and the first face of the assembly being oriented towards the laser source, and the stack to be disassembled having a first face oriented towards the laser source and a second face opposite the first face, the second face of the stack to be disassembled being at least partially free or being in contact with a soft support having a hardness less than or equal to 80 Shore A.

[0013] The Shore hardness according to the invention is expressed relative to the Shore A scale. The hardness of the support can be measured according to the ASTM D2240 (2021) standard. Examples of such supports are foams and polymeric materials, for example thermoplastic elastomers (such as polyester urethanes and polyether urethanes) and rubbers.

[0014] Typically, the first face and the second face of the stack to be disassembled are opposite each other, are parallel to each other and are parallel to the greatest length of the stack to be disassembled.

[0015] In the present description, the expression "face of a layer oriented towards an object" gives an indication of the orientation of said face relative to said object, but does not necessarily imply that the face is in contact with the object. This also does not imply that this face cannot be partially or totally covered by another layer.

[0016] When the second face of the stack to be disassembled is at least partially free, the second face of the stack to be disassembled is thus at least partially uncovered. The second face of the stack to be disassembled is advantageously directed towards and adjacent to a vacant space. The second face of the stack to be disassembled is therefore free of support entirely in contact with its second face.

[0017] Thus, preferably, the assembly is free of support entirely in contact with the second face of the stack to be disassembled.

[0018] The term "support" used here refers to a material acting as an anvil on which, if present, the second face of the stack to be disassembled would be entirely deposited. Generally, the support is a material of high hardness. As an example of a support, mention may in particular be made of a layer of glass or a layer of titanium, in particular with a thickness greater than 1 mm.

[0019] The absence of a support fully in contact with the second face of the stack to be disassembled can be advantageous, for example when the stack to be disassembled requires a high power to be disassembled.

[0020] Alternatively, the second face of the stack to be disassembled is in contact with a soft support having a hardness less than or equal to 80 Shore A, preferably less than or equal to 60 Shore A, preferably less than or equal to 40 Shore A, preferably less than or equal to 20 Shore A, preferably between 5 and 80 Shore A.

[0021] The presence of a soft support can be advantageous, for example when the stack to be disassembled does not require very high power. The inventors have discovered that such a method makes it possible to easily sort the different layers of a used battery, and in particular to disassemble these different layers without degrade the materials of said layers, which allows them to be recycled into new electrochemical elements. In addition, this process offers the advantage of being very versatile. It allows, among other things, the disassembly of many stacks of different natures. Examples include:

[0022] - bilayer materials, which are co-laminated and cannot be disassembled mechanically;

[0023] - the dissociation of a layer of active material and a current collector film, very difficult according to other existing methods;

[0024] - generally speaking, electrodes of all kinds, which are increasingly complexes with more and more strongly coupled layers (e.g., coated separator, ceramic coating, etc.).

[0025] Furthermore, the inventors have discovered that the fact that the second face of the stack to be disassembled, which is opposite the laser source, is at least partially free, allows the disassembly of the layers of the stack to be disassembled. The absence, at least partial, of covering of the second face of the stack to be disassembled (in particular the fact that it is partially not in contact with a solid or a liquid), allows the compression pressure wave generated by the plasma to become a displacement wave. Thus, the layer of the stack (and of the assembly) furthest from the laser source is separated from the rest of the stack (and therefore from the rest of the assembly).

[0026] Furthermore, this method is a method that does not require direct contact with the stack to be disassembled, which significantly reduces the potential risks associated with exposure to certain substances that may present risks to health or the environment.

[0027] During the method according to the invention, the laser shock hammering step is a laser shock hammering step of the first surface of the assembly oriented towards the laser source. This step advantageously causes the formation of a plasma in one of the layers of the assembly.

[0028] Furthermore, preferably, the assembly is not immersed in water during the implementation of the method according to the invention. Indeed, as mentioned above, the presence of water is totally incompatible with the active materials included in the first layer or the second layer of the stack to be disassembled. In particular, the lithium present in the positive, and possibly negative, electrodes of lithium batteries is incompatible with water. As a result, it is impossible to implement the method according to the invention in water with a view to recycling the materials present in the different layers of the stack to be disassembled.

[0029] Preferably, the assembly comprises:

[0030] - the stack to be disassembled, and

[0031] - at least one layer of sacrificial material deposited on said first face of the stack to be disassembled, and / or

[0032] - at least one layer of confinement material deposited either on said at least a layer of sacrificial material, either on the first face of the stack to be disassembled if the assembly does not include a layer of sacrificial material.

[0033] Thus, the method according to the invention preferably comprises a step of preparing the assembly, this step of preparing the assembly comprising:

[0034] - a sub-step of depositing at least one layer of sacrificial material on the first face of the stack to be disassembled, and / or

[0035] - a sub-step of depositing at least one layer of confinement material, or on the layer of sacrificial material, or on the first face of the stack to be disassembled if the assembly does not include a layer of sacrificial material.

[0036] The assembly preparation step is prior to the laser shock hammering step.

[0037] The layer of sacrificial material is also understood as a sheet. Thus, the layer of sacrificial material comprises or is made of a material capable of forming a plasma under the action of a laser beam, preferably a metal sheet or a layer of paint. The thickness of the layer of sacrificial material is preferably between 0.01 mm and 5 mm, preferably between 0.1 and 1 mm.

[0038] Preferably, the sacrificial material is metallic or black paint. Thus, the layer of sacrificial material comprises or is made of a metal or a metal alloy. In particular, the layer of sacrificial material may be or comprise aluminum, copper, an aluminum / thermoplastic material co-laminated film.

[0039] The implementation of the method according to the invention implies that a layer of the assembly plays the role of sacrificial layer. This sacrificial layer is the layer on the surface of which, or within which, a plasma will be generated under the action of the laser, said plasma making it possible to generate a wave which will propagate within the assembly and disassemble one or more layers. This sacrificial layer may be in the form of a layer of sacrificial material as defined above and deposited on the stack to be disassembled, or else be directly one of the layers of the stack to be disassembled. This is why the presence of a layer of sacrificial material (additional to the stack to be disassembled) is a specific embodiment of the method of the invention, but is not necessarily necessary.Using one of the layers of the stack to be disassembled as a sacrificial layer makes it possible to avoid the need to deposit an (additional) layer of sacrificial material, thus notably reducing costs, but has the disadvantage of sacrificing the layer of the stack which, by playing this role, cannot be recovered.

[0040] According to one embodiment, the confinement material is chosen from among the translucent materials, preferably transparent, anhydrous, solid or liquid, preferably solid, typically used in LSP processes. Examples include glass, such as tempered glass, particularly K7 type, or polymeric materials, particularly translucent oils, gels and tape.

[0041] According to the invention, the containment material is different from water.

[0042] Typically, the layer of containment material may be an adhesive tape, such as that sold under the name Coroplast ®, typically with a thickness between 0.1 and 2 mm, preferably between 0.5 and 1.5 mm, or a glass plate, in particular of the K7 type, typically with a thickness of between 2 mm and 10 mm.

[0043] Preferably, the containment material is an adhesive tape.

[0044] The confinement material is preferably translucent, advantageously transparent, at the wavelength of the incident laser beam. This allows the passage of the incident laser beam, while exerting mechanical pressure on the sacrificial layer to contain the expansion of the generated plasma.

[0045] The confinement material therefore preferably allows a laser power of at least 1 GW / cm2 to pass through the surface arranged below the layer of confinement material.

[0046] The presence of a layer of confinement material is advantageous in that it makes it possible to orient the mechanical shock wave generated by the plasma towards the stack rather than towards the surface oriented towards the laser source, which maximizes its power. It is not, however, necessary since its absence only means that the shock wave generated by the plasma is dissipated in all directions, and therefore has limited power, which may however be sufficient depending on the nature of the stack to be disassembled.

[0047] According to an advantageous embodiment, the assembly further comprises a layer of protective material. The layer of protective material is located between the first face of the stack to be disassembled, and the layer of sacrificial material. According to this embodiment, it is therefore the layer of protective material which is deposited on the first face of the stack to be disassembled, and the layer of sacrificial material is deposited on the layer of protective material.

[0048] The presence of at least one layer of protective material is optional and its presence depends on the nature of the stack to be disassembled, as well as the energy density of the laser. When present, said protective material may be chosen from metals and metal alloys, and more particularly copper, titanium, or stainless steel. The optional layer of protective metallic material may in particular be a metal foil, with a thickness typically between 5 μm and 200 μm.

[0049] The protective material layer forms a pressure base inside assembly and allows you to choose the profile and amplitude of this pressure wave. By extension, it is possible to choose the "power" of the delamination and which layers will be separated.

[0050] The layers of sacrificial material, containment material and protective material, if present, can be applied by any method known per se, for example by lamination, or by manual application.

[0051] Preferably, each of the layers of the stack to be disassembled has a thickness less than or equal to 5 mm, preferably less than or equal to 3 mm, preferably less than or equal to 1 mm, preferably between 1 μm and 5 mm.

[0052] Thus, it is possible that the total thickness of the stack to be disassembled is greater than 5 mm. In this case, the disassembly of the different layers of this stack can be carried out by repeating the disassembly process several times, to gradually disassemble the different layers or subsets of layers having a thickness less than or equal to 5 mm.

[0053] The assembly is generally maintained under pressure during the implementation of the disassembly process. Maintaining pressure ensures satisfactory contact between the different layers, in particular so that the shock wave is transmitted to the last layer of the stack to be disassembled.

[0054] It can for example be carried out by maintaining said assembly in a tool.

[0055] The stack to be disassembled can of course comprise more than two layers, and can therefore comprise additional layers of the first layer and the second layer.

[0056] In order to completely disassemble a stack to be disassembled, it may be necessary to repeat the laser shock hammering step several times at different locations in the assembly.

[0057] It may, alternatively or in addition, be necessary to disassemble in several stages the different layers of the stack to be disassembled, that is to say to implement the laser shock hammering stage on different successive assemblies.

[0058] The method according to the invention may therefore comprise a first step of laser shock hammering of a first assembly comprising the stack to be disassembled. Depending on the number of layers and the thickness of each layer of the stack to be disassembled, this first step of laser shock hammering makes it possible to obtain either a monolayer and a first sub-stack to be disassembled, or a first sub-stack to be disassembled and a second sub-stack to be disassembled (each sub-stack comprising at least two layers). Thus, each sub-stack may in turn be disassembled by a second step of laser shock hammering of a sub-assembly comprising said sub-stack to be disassembled. The sub- assemblies may comprise a layer of containment material, a layer of sacrificial material and optionally a layer of protective material, as described above. The second laser shock peening step(s) may therefore advantageously be preceded by a step of preparing the sub-assembly(ies), this step being as detailed above.

[0059] These steps can be repeated until the different layers of the stack to be disassembled are all separated from each other.

[0060] The stack to be disassembled is preferably a stack of compacted, co-laminated, molded or glued layers.

[0061] According to a first embodiment, the stack to be disassembled is an electrode.

[0062] The electrode can be positive or negative.

[0063] The positive electrode comprises a current collector, at least one of the faces of which is coated with a layer of a composition of positive active materials. By "composition of active materials" is meant a composition comprising one or more active materials and optionally one or more binders, and / or solid electrolyte particles and / or one or more electronically conductive materials.

[0064] The positive current collector is a solid or perforated metal strip which may be made of aluminum or an aluminum alloy or steel or stainless steel. Its thickness may be in the range of 6 to 30 μm or 5 to 20 μm or 10 to 15 μm, preferably 10 to 15 μm.

[0065] The positive active material may be any positive active material known in lithium element technology. It may be a lithiated oxide of at least one transition metal, an active material of the LVPF type or a lithiated phosphate of at least one transition metal.

[0066] The lithiated oxide of at least one transition metal may be chosen from:

[0067] i) a lithium oxide of nickel, manganese and cobalt of formula Liw(NixMnyCozMt)O2(NMC) where 0.9 <w<l,l ; 0<x ; 0<y ; 0<z ; 0<t ; M étant choisi dans le groupe constitué de Al, B, Mg, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Y, Zr, Nb, W, Mo, S, Sr, Ce, Ta, Ga, Nd, Pr, La et des mélanges de ceux-ci ;

[0068] ii) a lithium oxide of nickel, cobalt and aluminum of formula Liw(NixCoyAlzMt)O2(NCA) where 0.9 <w<l,l ; 0<x ; 0<y ; 0<z ; 0<t ; M étant choisi dans le groupe constitué de Al, B, Mg, Si, Ca, Ti, V, Cr, Mn, Fe, Cu, Zn, Y, Zr, Nb, W, Mo, S, Sr, Ce, Ta, Ga, Nd, Pr, La et des mélanges de ceux-ci ; iii) a compound of formula Lii+xMi.xO2.yFy with a cubic crystal structure where 0 <x<0,5 et 0<y<l et M représente un élément choisi dans le groupe constitué de Na, K, Mg, Ca, B, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Y, Zr, Nb, Mo, Ru, Ag, Sn, Sb, Ta, W, Bi, La, Pr, Eu, Nd et Sm et des mélanges de ceux-ci ;

[0069] iv) a lithium oxide of nickel and manganese (NMX) of formula Lia(Nii_x y_zMnxCoyMz)O2 with 0.9 <a<l,l ; 0,60<l-x-y-z<0,80 ; 0<x ; 0<y<0,02 ; 0<z ; et M étant choisi dans le groupe consistant en Al, B, Mg, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Y, Zr, Nb, W, Mo, S, Sr, Ce, Ga, Ta, Nd, Pr, La et des mélanges de ceux-ci ;

[0070] v) a lithium oxide of nickel and manganese of formula Liw(NixMnyCozMt)O2 where 1.1 <w<1,6 ; 0<x ; 0,50<y<0,80 ; 0<z<0,02 ; 0<t ; M étant choisi dans le groupe constitué de Al, B, Mg, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Y, Zr, Nb, W, Mo, S, Sr, Ce, Ta, Ga, Nd, Pr, La et des mélanges de ceux-ci.

[0071] vi) a lithium oxide of nickel and manganese of formula LixMn2 y_zM'yM"zO4_ô where M' and M" are selected from the group consisting of B, Mg, Al, Si, Ca, Ti, V, Cr, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb and Mo; M' and M" being different from each other, and 1 <x<1,4 ; 0<y<0,6 ; 0<z<0,2 ; 0<ô<l,

[0072] and mixtures of different compounds of categories i) to vi).

[0073] LVPF type active materials correspond to the formula Lii+xVi yMyPO4Fzwith 0 <x<0,15, 0<y<0,5, 0.8<z<l,2, et M est choisi parmi le groupe consistant en Ti, Al, Mg, Mn, Fe, Co, Y, Cr, Cu, Ni et Zr.

[0074] The lithium phosphate of at least one transition metal can be chosen from: a) a lithium iron phosphate of formula LixFei yMyP04 (LFP), where 0.8 <x<l,2 ; 0<y<0,6 et M est choisi dans le groupe consistant en Al, B, Mg, K, Si, Ca, Ti, V, Cr, Co, Cu, Mn, Ni, Zn, Y, Zr, Nb, W, Pb, Mo, S et des mélanges de ceux-ci ;

[0075] b) a lithium manganese phosphate of formula LixMni yMyP04 (LMP), where 0.8 <x<l,2 ; 0<y<0,6 et M est choisi dans le groupe consistant en Al, B, Mg, K, Si, Ca, Ti, V, Cr, Co, Cu, Fe, Ni, Zn, Y, Zr, Nb, W, Pb, Mo, S et des mélanges de ceux-ci ;

[0076] c) a lithium manganese and iron phosphate of formula: LixMni y zFeyMzPO4 (LMFP) where 0.8 <x<l,2 ; 0,5<l-y-z<l; 0<y+z<0,5 ; 0<y<0,50 et 0<z<0,2 et M est choisi dans le groupe constitué de Al, B, Mg, K, Si, Ca, Ti, V, Cr, Co, Cu, Ni, Zn, Y, Zr, Nb, W, Pb, Mo, S et des mélanges de ceux-ci ;

[0077] d) and mixtures of different compounds of categories a) to c).

[0078] The term “positive electrode” designates the electrode functioning as a cathode when the accumulator is discharging, and the electrode functioning as an anode when the accumulator is charging.

[0079] The negative electrode comprises a current collector at least one of whose faces is coated with a layer of a negative active material composition comprising an electrode active material, and / or one or more binders and / or an electronically conductive material. The current collector is prepared in a conventional manner. The negative electrode active material is not particularly limited. It may be selected from the following groups and mixtures thereof:

[0080] - Metallic lithium or a metallic lithium alloy

[0081] - Graphite

[0082] - Silicon

[0083] - Anode-free type

[0084] - a titanium and niobium oxide of the TNO type

[0085] - a lithiated titanium oxide or a titanium oxide capable of being lithiated, of the LTO type.

[0086] Examples of lithiated titanium oxides are spinel Li4Ti50i2, Li2TiO3jla ram-sdellite Li2Ti3O7,LiTi2O4, LixTi2O4, with 0 <x<2 et Li2Na2Ti60i4.

[0087] A preferred LTO compound has the formula L^ aMaTi5 bM'bO4, for example Li4Ti50i2 which is also written Li4 / 3Ti5 / 3O4.

[0088] The term “negative electrode” designates the electrode functioning as an anode when the accumulator is discharging, and the electrode functioning as a cathode when the accumulator is charging.

[0089] According to another embodiment, the stack to be disassembled is an electrochemical element, preferably an all-solid-state battery electrochemical element.

[0090] An electrochemical element is understood to mean an element comprising a positive electrode / electrolyte / negative electrode stack configured to store the electrical energy produced by a chemical reaction and restore it in the form of an electric current.

[0091] The positive and negative electrodes are as defined above.

[0092] The electrolyte is in particular a solid, inorganic, polymeric or hybrid electrolyte.

[0093] In all-solid-state batteries, the electrolyte is solid.

[0094] Among the inorganic solid electrolytes, we can distinguish: electrolytes based on metal oxides such as LISICON, NASICON, perovskites and Garnet type electrolytes; electrolytes based on sulfides, such as materials that can be synthesized from at least one of the precursors Li2S and P2S5, or thio-phosphates of the Lii0GeP2Si2 type and its derivatives; electrolytes based on nitrides, such as lithium nitride or LiPON.

[0095] Among the solid polymer electrolytes, we can distinguish those based on polyethylene glycol, polyacrylonitrile, polyvinyl chloride, polyvinylidene fluoride, polymethyl methacrylate; and those based on lithium salts (LiPF6, LiAsF6, LiSbF6, ...) dissolved in polyethylene glycol.

[0096] Hybrid solid electrolytes include, for example, non-lithiated salts (such as oxides, MOFs, graphene) in polymers such as listed above for polymer solid electrolytes, or a mixture of these polymers with an inorganic solid electrolyte material such as those detailed above.

[0097] Typically, the stack to be disassembled is a lithium-ion electrochemical element.

[0098] The stack to be disassembled can also be a stack of a positive electrode or negative, and a solid electrolyte, as defined above.

[0099] The laser parameters generally depend on the stack to be disassembled.

[0100] According to one embodiment, the laser is a pulsed laser. Preferably, the laser is a pulsed laser having a ratio [energy / (impact diameter)] of between 0.1 and 5 J / mm2.

[0101] The diameter of the impact is related to the diameter of the laser beam. Typically, the diameter of the beam can be adapted according to the ratio defined above. The diameter of the beam is related to the energy density per unit area of ​​a laser beam. The larger the diameter of the beam, the lower the energy density of a beam of constant power or energy will be.

[0102] Parameters such as wavelength, laser pulse energy, number of laser treatments for a given surface, etc. can generally be adapted by the operator:

[0103] The wavelength of a laser describes the spatial frequency of the emitted light. The optimal wavelength generally depends on the components to be treated.

[0104] The energy of the laser pulse (measured in Joules, J) is directly proportional to the average power and inversely proportional to the repetition rate of the laser: it therefore corresponds to: Pulse energy = Average power / Repetition rate

[0105] The repetition rate of a pulsed laser, or pulse repetition frequency, describes the number of pulses emitted each second.

[0106] The laser pulse duration, or pulse width, is generally defined as the full width at half-maximum (or FWHM) of the laser's optical power as a function of time.

[0107] The laser typically has a pulse duration of less than 1 microsecond (ps), typically between 1 picosecond and 500 nanoseconds (ns). Generally, the pulse duration may be between 1 and 500 ns.

[0108] The emitter of the laser pulses is not limited in itself. It may in particular be an Nd:YAG laser system or a doped glass, Yb fiber, diode-based laser system.

[0109] It is understood that one or more LSP treatments can be carried out on the same stack to be disassembled, as many as necessary, depending in particular on the nature of the stack to be disassembled.

[0110] The invention also relates to a recycled material from a layer of a stack to be disassembled, said layer being obtained by the disassembly method according to the invention.

[0111] Indeed, once the layers of the stack to be disassembled are separated from each other, the material of each layer can be easily recovered and recycled. In particular, it can be reused for the manufacture of a new layer of a new electrochemical element. This layer can be a layer of an electrode (positive or negative) or an electrolyte layer.

[0112] The present invention therefore also relates to an electrochemical element, comprising such a recycled material.

[0113] The electrochemical element can be of several types or formats. Indeed, the electrochemical bundle is inserted into a container, and the container of the electrochemical element can be of parallelepiped, cylindrical or even pouch format.

[0114] According to another object, the present invention also relates to an electrochemical module comprising the assembly of at least two electrochemical elements, each element being electrically connected to one or more other element(s).

[0115] The term "module" therefore designates the set of several electrochemical elements, this set being able to be in series and / or in parallel.

[0116] According to another object, the invention also relates to a battery or "accumulator" comprising one or more recycled modules according to the invention. The term "battery" therefore designates the set of one or more modules according to the invention.

[0117] Finally, the present invention also relates to the use of laser shock hammering for disassembling a stack to be disassembled, the stack to be disassembled comprising at least a first layer and at least a second layer, and at least one of the first layer and the second layer is an electrochemically active layer.

[0118] The invention will be described more precisely, in an illustrative manner, with reference to the figures and examples given below. Figures

[0119] [Fig. 1] [Fig. 1] is a diagram representing the principle of applying laser shock hammering to an assembly according to the method of the invention, in which the second face of the stack to be disassembled, opposite the laser source, is at least partially free.

[0120] [Fig.2] [Fig.2] is a diagram showing a comparative device in which the assembly is entirely placed on a rigid support (Shore hardness strictly greater than 80 Shore A).

[0121] [Fig.3] [Fig.3] represents a scanning electron microscopy image (SEM) of a positive electrode after disassembly according to the method of the invention.

[0122] [Fig.4] [Fig.4] represents a scanning electron microscopy image (SEM) of a negative electrode after disassembly according to the method of the invention.

[0123] As illustrated in [Fig.l], an assembly (10) as defined according to the invention comprises a stack to be disassembled (20). The stack to be disassembled comprises a first layer (22) and a second layer (24). In this embodiment embodiment, the stack to be disassembled is an electrode comprising a current collector (24) and a layer of electrochemically active material (22). The stack to be disassembled has a first face (25) oriented towards the laser source (30) and a second face (27) opposite the first face (25). According to the invention, the second face (27) of the stack to be disassembled is at least partially free, therefore at least partially uncovered. It is thus directed towards and adjacent to a vacant space. In particular, it is not completely in contact with a support, as is the case in [Fig. 2] detailed below.

[0124] In the particular embodiment of [Fig.l], the assembly further comprises a layer of sacrificial material (40) on the first face (25) of the stack to be disassembled, and a layer of confinement material (50) on the layer of sacrificial material (40).

[0125] To implement the disassembly method, a laser beam is applied which passes through the layer of confinement material (50) and hammers the layer of sacrificial material (40) at the point of impact, so as to generate a plasma (60).

[0126] The plasma forms on the surface of the layer of sacrificial material (40), and within it if this layer is very thin. The expansion of the plasma causes a compression wave, which preferably moves in the depth of the stack to be disassembled thanks to the presence of the confinement layer (50), causing in its passage the disassembly of the first layer (22) (preferably the layer of the stack to be disassembled furthest from the laser source).

[0127] [Fig. 2] shows a device implementing a comparative method. Compared to [Fig. 1], the only difference is the presence of a support (70) in total contact with the second face (27) of the stack to be disassembled. The second face (27) of the stack to be disassembled is therefore completely in contact with this support (70). In this case, when a laser beam hammers the layer of sacrificial material (40) at the point of impact, the shock wave created by the generated plasma causes the densification of the first layer (22) and the second layer (24), instead of disassembling them. The result of this method is therefore contrary to the aim sought by the present invention. This is due to the presence of an "anvil" (rigid support with Shore hardness strictly greater than 80 Shore A), because the shock wave is thus transmitted by mechanical contact between the last layer of the stack and the anvil without displacement (or displacement wave).The anvil being the last solid in the stack (therefore the free surface) it is this which is supposed to deform (displacement wave) unless the material chosen is sufficiently rigid to resist the incident wave.

[0128] EXAMPLES

[0129] Example 1: Disassembly of a positive electrode

[0130] The test was carried out with a positive electrode comprising a stack of a electrode layer (100) comprising a mixture of LFP (LiFePO4) and NCA (Nickel, Cobalt, Aluminum), a binder and an electronically conductive material, 200 pm thick, and an aluminum foil (120) 15 pm thick.

[0131] On the current collector was deposited a sacrificial layer (140) of aluminum 100 or 200 pm thick, and a layer of confinement material (Scotch Coroplast® 9010 SPT 1 mm thick, not visible in [Fig.3] because removed before analysis) to form an assembly.

[0132] Two laser hammerings at two different locations of the assembly were carried out with the following parameters: Energy = 0.13 J; Spot diameter = 1 mm. In this test, the second face of the electrode to be disassembled (190) is not completely in contact with a support.

[0133] The photo in [Fig.3] shows a cross-sectional view of these two shots. It is very clearly seen that the electrode layer has disassembled from the current collector, thus allowing these two layers to be separated without deterioration.

[0134] Example 2: Disassembly of a negative electrode

[0135] The test was carried out with a negative electrode comprising a stack of two electrode layers comprising a mixture of hard carbon (a carbon which cannot be transformed into graphite (non-graphitizable), even if it is brought to a temperature exceeding 2500°C, generally having a disordered, non-crystalline structure), a binder and an electronically conductive material, 355 μm thick, arranged on either side of an aluminum foil (220) coated with carbon 15 μm thick.

[0136] A 200 μm thick sacrificial layer of aluminum and a layer of confinement material (Scotch Coroplast® 9010 SPT 1 mm thick, not visible in [Fig.4] as it was removed before analysis) were deposited on the current collector to form an assembly.

[0137] Laser hammering at one location of the assembly was carried out with the following parameters: Energy = 1.39 J; Spot diameter = 2.38 mm. In this test, the second face of the electrode to be disassembled (280) is deposited on a support (290) with a hardness less than or equal to 80 Shore A.

[0138] The photo in [Fig.4] shows a cross-sectional view of this shot. The electrode layer has disassembled from the current collector, thus allowing a portion of an active layer to be separated from the current collector.

Claims

Claims

1. A method of disassembling a stack to be disassembled, the stack to be disassembled comprising at least a first layer and at least a second layer, at least one of the first layer or the second layer being an electrochemically active layer, the method comprising a step of laser shock peening a first face of an assembly, the assembly comprising at least the stack to be disassembled and the first face of the assembly being oriented towards the laser source, and the stack to be disassembled having a first face oriented towards the laser source and a second face opposite the first face, the second face of the stack to be disassembled being at least partially free or being in contact with a soft support having a hardness less than or equal to 80 Shore A.

2. The method of claim 1, wherein the assembly is free of support entirely in contact with the second face of the stack to be disassembled.

3. Method according to claim 1, in which the second face of the stack to be disassembled is in contact with a soft support having a hardness less than or equal to 60 Shore A, preferably less than or equal to 40 Shore A.

4. Method according to any one of the preceding claims, in which the assembly comprises: - the stack to be disassembled, and - at least one layer of sacrificial material deposited on said first face of the stack to be disassembled, and / or - at least one layer of confinement material deposited either on said at least one layer of sacrificial material, or on the first face of the stack to be disassembled if the assembly does not comprise a layer of sacrificial material.

5. Method according to any one of the preceding claims, comprising a step of preparing the assembly, comprising: - a sub-step of depositing at least one layer of sacrificial material on the first face of the stack to be disassembled, and / or - a sub-step of depositing at least one layer of confinement material, either on said at least one layer of sacrificial material, or on the first face of the stack to be disassembled if the assembly does not include a layer of sacrificial material.

6. A method according to claim 4 or 5, wherein the layer of sacrificial material comprises or consists of a material capable of forming a plasma under the action of a laser beam, preferably is a metal foil or a layer of paint.

7. A method according to any one of claims 4 to 6, wherein the containment material is an adhesive tape.

8. Method according to any one of the preceding claims, in which each of the layers of the stack to be disassembled has a thickness less than or equal to 5 mm, preferably less than or equal to 3 mm, preferably less than or equal to 1 mm, preferably between 1 μm and 5 mm.

9. A method according to any preceding claim, wherein the stack to be disassembled is an electrode.

10. A method according to any preceding claim, wherein the stack to be disassembled is an electrochemical cell, preferably an all-solid-state battery electrochemical cell.

11. A method according to any preceding claim, wherein the laser is a pulsed laser having an [energy / (impact diameter)] ratio of between 0.1 and 5 J / mm2.

12. Recycled material from a layer of a stack to be disassembled, obtained by the disassembly method according to any one of claims 1 to 11.

13. An electrochemical element comprising a recycled material according to claim 12.

14. Use of laser shock peening for disassembling a stack to be disassembled, the stack to be disassembled comprising at least a first layer and at least a second layer, and at least one of the first layer and the second layer is an electrochemically active layer.

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