New process for intercalation of alkali metals in materials based on transition element(s)

Abstract

The invention relates to a process for the solid-state alkalinisation of a salt that comprises at least one transition metal and is deficient in an alkali metal, this process being characterised in that it comprises the following steps: a) mixing, in solid form, the salt that is deficient in (or does not comprise) an alkali metal with the corresponding alkali metal iodide, this iodide also being in solid form, to obtain a solid mixture; b) reacting the solid mixture to obtain molecular iodine and a salt of the alkali-metal-enriched transition metal; and, optionally, c) separating the molecular iodine from the solid mixture.

Description

Description Title of the invention: New process for intercalating alkalis into materials based on transition element(s) Field of invention

[0001] The invention relates to a method for intercalating or inserting alkalis into transition element-based materials, enabling synthesis or recycling of materials used in cells and batteries using alkali elements such as sodium, lithium and potassium (solid-state alkalization). Prior art

[0002] The transition to electric mobility is currently one of the most important elements in reducing carbon emissions worldwide. The disposal, recovery, and recycling of alkaline batteries and accumulators at the end of their useful life are becoming increasingly pressing issues. Indeed, the production of lithium batteries, known as lithium cells, or lithium-ion accumulators, is constantly increasing, and as a result, in the coming years, the number of accumulators reaching the end of their service life and requiring disposal will increase. Therefore, proper recycling of these batteries is essential. Such recycling involves methods for reintroducing alkali elements into electrode materials, particularly the materials used in devices that exchange these alkali ions (especially Li, K, and Na ions).

[0003] Different lithiation routes for alkaline electrode materials are known: i) Heat treatment which is carried out after adding to the delithiated phase (FePCU) a source of lithium (U2CO3) and a reducing agent (C) at 700 °C / 10 h under an argon atmosphere. 1 2 This is not a direct lithiation of FePCU but a complement to the synthesis of the material at high temperature, because in this case it is the chemical reaction of U2CO3 on the reduction products of FePC by carbon. ii) Electrochemical lithiation via the pre-lithiation of graphite 3 . This method requires a controlled atmosphere and is an expensive process, difficult to apply on a large scale. iii) chemical lithiation where lithium iodide (LiI) is dissolved in organic solvents (acetonitrile, ethanol, cyclohexane, DMSO, ...) and then brought into contact with an end-of-life cathode material comprising FePCU and LiFePO ' 56This method has slow kinetics (~20 h) and the use of large quantities of solvents that are not very compatible with the requirements of an environmentally friendly process. It is also known to perform the sodiation of NasN^PCU^Fs to form Na4V2(PO4)2Fs by mechanical grinding using metallic Na as a reducing agent. 7 The use of Na metal requires special and expensive safety precautions (argon / dry room).

[0004] There is therefore a need for a simple to implement, inexpensive, and / or environmentally friendly process, allowing the synthesis and / or reintroduction of alkali ions into compounds comprising transition elements, in particular compounds intended and / or used in electrochemistry for the manufacture of electrodes. Description of the invention

[0005] An object of the invention is therefore a process for the solid-state alkalization of a compound, in particular a salt, comprising at least one transition metal, said compound being deficient in an alkali, this process being characterized in that it comprises the following steps: a) mixing, in solid form, said salt deficient in an alkali (or not comprising it) with the corresponding alkali metal iodide, the latter also being in solid form, to obtain a solid mixture; b) reacting said solid mixture to obtain molecular iodine and a salt of said transition metal enriched in said alkali metal; and, optionally c) separating the molecular iodine from said solid mixture, wherein said transition metal salt enriched in said alkali metal is preferably chosen as having, in the solid state, and under normal conditions of pressure and temperature, an average potential relative to lithium (Li + / Li) of more than 3V. Particularly advantageously, this method makes it possible either to produce an alkali salt of a transition metal from a salt which is completely devoid of it, or to increase the quantity of said alkali in a salt of a transition metal already containing it. Thus, by "solid state alkalization", it describes both the synthesis of an alkali salt and the increase in the alkali content of a salt already containing it in part. The method of the invention can therefore be a method for synthesizing an alkali salt but can also be a method for regenerating, recycling and / or inserting alkali ions into a material comprising a transition metal. The term "salt" is used in its modern sense to denote an ionic solid, corresponding to a reticular assembly of ions of different charges. It is not limited by properties such as solubility, appearance, and flammability formerly associated with the term. The term "deficient" refers not only to compounds that are not saturated in a given alkali, but also to compounds that do not contain it. Similarly, the term "enriched" refers not only to compounds that are saturated in a given alkali, but also to compounds that contain a greater amount of it than the starting compound. The expression "solid-state alkalization process" thus describes the synthesis of an alkali salt or the increase in the amount of alkali in a compound already containing it. The process according to the invention allows the increase in the amount of at least one alkali. It can also allow the introduction of different alkalis. The term "alkali" designates both the element and the corresponding ions. Among the alkalis (lithium, sodium, potassium, rubidium, cesium and francium), lithium, sodium and / or potassium are preferred and more particularly lithium. Thus, the process according to the invention preferably relates to a lithiation, sodiation and / or potassiation process. A "transition metal" is a chemical element whose atoms have an incomplete d electron subshell, or which can form cations whose d electron subshell is incomplete. As is customary, this definition also includes a group 12 element, such as zinc, cadmium and mercury. Preferably, the transition metal is selected from the group consisting of the first series (titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn)), the second series (zirconium (Zr), niobium (Nb), molybdenum (Mo), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag) and cadmium (Cd)) and the third series (hafnium (Hf), tantalum (Ta), tungsten (W), rhenium (Re), osmium (Os), iridium (Ir), platinum (Pt), gold (Au) and mercury (Hg)).More preferably, the transition metal is chosen from the group consisting of manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), and a combination thereof. The salt comprising at least one transition metal, said salt being deficient and / or enriched in an alkali, may obviously comprise more than one transition metal and / or at least one other metal, in particular an alkaline earth metal such as for example calcium, magnesium and / or beryllium. The average potential can be estimated based on the standard potential of the redox couple contained in the material, these standard potentials are available in the form of tables in the literature which allow the determination of the potentials. For example: https: / / www.lachimie.fr / solutions / oxidoreduction / table-potentiel-standard.php. 2. The average potentials of solid materials can be determined more precisely by measuring them using simple electrochemical techniques such as cyclic voltammetry (CV) or a dx / dV derivative curve of a galvanostatic curve, where x corresponds to the amount of alkali. These techniques, known to those skilled in the art, are explained in Example 20. The use of alkali iodide is advantageous because the by-product of the reaction is easily recoverable in the form of molecular iodine and iodide or triodide ion l3'. The process according to the invention therefore makes it possible to alkalize and / or realkalize many types of salts. The salt comprising at least one transition metal, said salt being enriched in alkali, is preferably a compound used for the manufacture of electrodes in the field of batteries, accumulators and batteries. An electrochemically active salt is particularly preferred. Thus, the salt obtained may advantageously comprise an olivine-type salt, to which the salt (LiFePCU) belongs in particular. The olivine-type salt has the general formula XYTO4, where T is one (or more) tetravalent cation (in particular Si, P, As), X at least one alkali metal cation and Y at least one non-alkali metal cation as described above. Y may advantageously be chosen from the group consisting of Fe 2+ , Mn 2+ , Co 2+ , Neither 2+ , Mg 2+ , That 2+ and their mixtures. X can advantageously be Li + , N / A + and their mixtures. The salt obtained can also advantageously comprise a salt from the LiNMC / NMC family (LiNi x Mn y Co z 02, where x + y + z = 1) where these metals are replaced completely or partially by other metals, such as those described above. Advantageously, these metals are chosen from the group consisting of the elements Al, Fe, V, Cr, Nb, Mo and their mixtures. Li can advantageously be replaced in whole or in part by sodium. Thus, the salt can have the formula AM1 x M2 y M3 z O2, where x + y + z = 1 where A is an alkali, preferably Li and / or Na and where M1, M2 and M3 are each a non-alkali metal, preferably selected from the group consisting of the metal ions Co 3+ , Neither 3+ , Mn 3+ , Al 3+ , Fe 3+ , V 3+ , Cr 3+ , Nb 3+ , Mo 3+ . The salt alkalized according to the process according to the invention can also advantageously be doped with at least one element which can be a metal as described above or a rare earth, such as Ce. The doping of a compound consists of introducing, into its matrix, elements in very low concentration which can replace other atoms. The dopant(s) can replace a very small part (for example less than 5%, preferably less than 1%) of the sites occupied by other elements of the compound, in particular by the alkali and / or alkaline earth element(s) (for example Ca). This alkalized salt can preferably be: - a lithium compound, and in particular a compound of formula UC0O2 (LCO), LiFePCU (LFP), LiMn2O4 (LMO), LiMn x Fe y PO4 (LMFP) - e.g. LiMno,6eFeo,34P04, LiNi x Mn y Co z 02 (NMC) - for example LiNi0.33Mn0.33Coo.3302 (NMC1 11 ) and LiNi0.6Mn0.2Coo.202 (NMC622); - a sodium compound, in particular NaFePCU or Na2Fe(SO4)2,4H2O; or - a potassium compound such as K2Fe(SO4)2.2H2O; where x, x', y, y' and z are independently of each other non-null real numbers and less than 1. Preferably x' + y' = 1 and / or x + y + z = 1. The transition metal, as well as the alkali, when present, is generally in cationic form in the salt. The salt comprising at least one transition metal and being deficient and / or enriched in an alkali, comprises one or more anions. This is advantageously chosen from the group consisting of oxides, sulfates, phosphates and hexacyanoferrates. The compound comprising at least one transition metal, said compound being deficient in an alkali may be totally or substantially free of this alkali or any alkali. For example, it may be selected from the group consisting of FePCU, Fe2(SO4)s, FesCU, LLC0O2, Mn2C>4, Li e Neither xMn y Co z 02. The compound may also be doped with at least one other element which may advantageously also be a transition metal, for example FePCU doped with Mn. The salt comprising at least one transition metal, said salt being deficient in an alkali, may comprise this alkali but not be saturated with it. Also this salt may have a saturated empirical formula, or the indices are not necessarily whole numbers and are lower, in particular for the anionic part, than the whole numbers of the corresponding empirical formula. Preferably, this salt is a partially or totally de-alkalized salt due to its use in an electrochemical device. Preferably, the salt comprising a transition metal and being deficient (or depleted) in at least one transition metal, corresponds to a salt enriched with the alkali-enriched salts described above with the exception of a lower relative quantity of alkali. Steps a) and b) of the process according to the invention are advantageously carried out in the solid state. Alternatively, or additionally, these steps a) and b) are carried out without solvent, in a medium which is not a liquid medium, and / or where the transition metal salt is not dissolved. According to one aspect of the invention, the solid mixture reacts by simple contact and steps a) and b) are concomitant. According to an advantageous variant of the invention, the mixing can be carried out by grinding, which involves a reduction in the size of the particles. This grinding can be carried out by impact, by crushing, by attrition, by shearing and / or by a combination of one or more of these actions. The process according to the invention may also advantageously comprise a heating step which may be carried out during or subsequently to step a) and / or b) and / or under normal pressure conditions, i.e. at atmospheric pressure. Preferably, this heating step is carried out at a temperature below 150°C, more preferably below 100°C. Indeed, although slight heating may sometimes be advantageous, the process according to the invention may be carried out at room temperature and in the vast majority of cases with little or no addition of thermal energy. For example, this addition may be due to the use of a grinding step. Thus, step a) and / or b) may be carried out without heating, at room temperature and / or even at low temperature. According to a particular embodiment, step b) is carried out in the solid state and / or at a temperature less than or equal to 150°C, preferably less than or equal to 100°C, more preferably without heating and / or sintering. According to one embodiment, steps a) and b) are concomitant and the salt comprising at least one transition metal and being partially or totally deficient in an alkali, reacts with the corresponding alkali iodide by contacting, said contacting being carried out without a heating step and preferably in the presence of air. Surprisingly, the inventors have demonstrated that the reaction between said alkali-deficient salt and the corresponding alkali iodide, by contact without a heating step, allowed complete, rapid and more ecological realkalization than the usual processes which necessarily include a heating step. According to one embodiment of the invention, said mixture is made with a corresponding alkali-deficient salt / alkali iodide molar ratio of less than or equal to 1. According to a preferred aspect of the invention, steps a) and / or b) are carried out in the presence of air or under an inert atmosphere (for example under argon). In particular, the method according to the invention can be carried out simply in the presence of ambient air, and advantageously in an uncontrolled atmosphere. Preferably, the method according to the invention is carried out without heating, or a dedicated external heating source, with the possible exclusion of step c) where an external heat input can be carried out to extract the molecular iodine from the mixture. The method according to the invention advantageously comprises a step for separating the iodine, and in particular the molecular iodine and / or the triiodide ion, from the reaction mixture. This step may comprise washing the mixture with a solvent or a mixture of solvents, preferably an organic solvent which may be an alcohol (e.g. ethanol). This solvent may also comprise the alkali iodide used in solution. This washing may optionally be followed by a step of drying the reacted and washed mixture. Alternatively, a molecular iodine sublimation step can be used. This step can be carried out by heating the reaction mixture after the solid-state alkalization reaction has been carried out. The heating temperature can advantageously be around 100°C because the iodine evaporates well below its melting point (113°C) and passes directly into the gaseous state. This heating is preferably carried out in an inert atmosphere, for example under a flow of Ar / N2 gas. This heating can also be carried out under vacuum. It is therefore possible, according to a variant of the process according to the invention, to implement a solid-state alkalization process without the use of solvent and / or liquid, which is particularly advantageous from an energy and environmental point of view. The method according to the invention may be particularly suitable for the solid-state alkalization of a salt comprising a transition metal and being deficient in an alkali which has been part of an electrochemical device such as an electrode. It is therefore possible, thanks to the method according to the invention, to realkalize constituent materials of ion batteries (e.g. lithium, sodium, and potassium), in a particularly simple and economical manner. Furthermore, according to a particularly advantageous aspect, it is possible to realkalize a salt comprising a transition metal and being deficient in an alkali while this salt is mixed with at least one other component. Advantageously, this other component is a conductive agent and / or a binder. The conductive agent may be chosen from the group consisting of graphite, carbon black, fibers and / or carbon nanotubes. The binder may be PVDF (Polyvinylidene Fluoride) and / or PTFE (Polytetrafluoroethylene). Preferably, the mixture is in the form of a powder, in particular a micrometric or nanometric powder. Thus, another object of the invention is a method for recycling an electrochemically active material (or a mixture of materials) used in particular in an accumulator using alkaline ions for charge transfer and comprising the steps described above. The material is preferably a material constituting a cathode. The material can advantageously be recycled directly, that is to say without steps of separation and isolation of the salt to be recycled. Another preferred aspect of the invention is the possibility of preserving the morphology and / or the crystalline structure of the alkaline salt particles comprising a transition metal. Thus it may be possible to preserve the structure of a salt such as olivine NaFePCU which cannot be obtained by conventional direct synthesis. The transformation of the salt may therefore be topotactic in nature and the transition from one crystalline structure to the other may be done without there being a notable upheaval and does not require considerable energy. Thus it may be possible to preserve the structure of a salt such as olivine NaFePCU which cannot be obtained by conventional direct synthesis. Brief description of the figures

[0006] The invention will be better understood on reading the following description, given solely by way of example and with reference to the appended drawings in which:

[0007] [Fig. 1] is a diffractogram obtained by X-ray Diffraction (XRD) of the powders a.) commercial LiFePC, b.) FePC prepared by chemical delithiation of LiFePCU and c.) LiFePC obtained by chemical lithiation of FePCU without solvent at room temperature according to a variant of the process of the invention described in Example 1.

[0008] [Fig. 2] shows a powder obtained according to Example 1 and which is heated to 100°C under vacuum / under an inert Ar / N2 atmosphere to sublimate the iodine.

[0009] [Fig. 3] shows the DRX diffractograms of the powders of a.) LiFePC cathode at the end of its life and b.) relithiated according to a process according to the invention, as well as an image obtained by scanning electron microscopy of c.) the LiFePC cathode powder at the end of its life and d.) the LiFePC cathode relithiated according to the process of Example 2.

[0010] [Fig. 4] shows the galvanostatic charge / discharge curves at C / 10 vs. Li + / Li° of the LiFePC cathode powder a.) at the end of its life and b.) relithiated using the process according to example 2.

[0011] [Fig. 5] DRX powder diffractograms of a.) FePC obtained by chemical delithiation of LiFePC and b.) LiFePCU obtained by chemical lithiation of FePCU under argon at 100 °C according to example 3.

[0012] [Fig. 6] represents the DRX diffractograms of the powders of a.) FePCU obtained by chemical delithiation of LiFePCU and b.) LiFePCU obtained by chemical lithiation of FePCU under argon at 80 °C according to example 4.

[0013] [Fig. 7] represents the DRX diffractograms of the powders of a.) FePCU prepared by chemical delithiation of commercial LiFePCU and b.) LiFePCU obtained by chemical lithiation of FePCU by mechanical grinding according to Example 5.

[0014] [Fig. 8] shows the XRD diffractograms of powders of a.) commercial LMFP, b.) chemically delithiated LMFP and c.) chemically lithiated LMFP without solvent at room temperature, as well as the charge-discharge curves in galvanostatic mode vs. Li + / Li° at C / 20 of the powder d.) delithiated LMFP and e.) relithiated LMFP of example 6.

[0015] [Fig. 9] shows the XRD diffractograms of powders of a.) commercial NMC11 1, b.) chemically delithiated NMC1 11 and c.) chemically lithiated NMC11 1 without solvent at room temperature. As well as the charge-discharge curves in galvanostatic mode vs. Li + / Li° at C / 20 of the powder d.) delithiated NMC111 and e). relithiated NMC111 of example 7.

[0016] [Fig. 10] shows the XRD diffractograms of powders of a.) commercial NMC622, b. chemically delithiated NMC622 and c.) chemically lithiated NMC622 without solvent at room temperature; as well as the charge-discharge curves in galvanostatic mode vs. Li + / Li° at C / 20 of the powders d.) delithiated NMC622 and e.) relithiated NMC622 of example 8.

[0017] [Fig. 11] shows the XRD powder diffractograms of a.) commercial LMO, b.) chemically delithiated LMO and c.) solvent-free chemically lithiated LMO at room temperature; as well as the charge-discharge curves in galvanostatic mode vs. Li + / Li° at C / 20 of the powders of d.) delithiated LMO and e.) relithiated LMO according to example 9.

[0018] [Fig. 12] shows the XRD diffractograms of powders a.) commercial LCO, b.) chemically delithiated LCO and c.) chemically lithiated LCO without solvent at room temperature; as well as the charge-discharge curves in galvanostatic mode vs. Li + / Li° at C / 20 of d.) delithiated LCO and e.) relithiated LCO according to example 10.

[0019] [Fig. 13] shows the DRX diffractograms of the powders of a.) Fe2(SO4)3(H2O)7.25, and b.) K2Fe(SO4)2.2H2O potash as well as c.) its refinement using the FullProf optimization program httDs: / / www.ill.eu / sites / fullDrof / DhD / downloads.html, according to Example 11.

[0020] [Fig. 14] shows the DRX diffractograms of the powders of a.) delithiated FePCM, and b.) sodiated NaFePC obtained by chemical sodiation and c.) DRX refinement of the NaFePC phase according to Example 12.

[0021] [Fig. 15] shows the DRX diffractograms of the powders a.) Fe2(SO4)3(H2O)?,25 and b.) Na2Fe(SC>4)2,4H2O sodium-containing according to Example 13.

[0022] [Fig. 16] represents the DRX diffractogram of the FePC>4.2H2O and Lil mixture prepared in air at room temperature according to comparative example 14.

[0023] [Fig. 17] represents the DRX diffractogram of the FePC>4.2H2O and Nal mixture prepared in air at room temperature according to comparative example 15.

[0024] [Fig. 18] represents the DRX diffractogram of the FePC>4.2H2O and Kl mixture prepared in air at room temperature according to comparative example 16.

[0025] [Fig. 19] represents the DRX diffractogram a.) of the commercial FeOOH powder and b.) the powder recovered after mixing FeOOH and Lil in air at room temperature according to comparative example 17.

[0026] [Fig. 20] represents the DRX diffractogram a.) of the commercial FeOOH powder and b.) of the powder recovered after mixing FeOOH and Nal in air at 100 °C according to comparative example 18.

[0027] [Fig. 21] represents the DRX diffractogram of a.) commercial FeOOH powder and b.) the powder recovered after mixing FeOOH and Kl in air at 100 °C according to comparative example 19.

[0028] [Fig. 22] shows the Cyclic Voltammetry of LFP vs. Li + / Li° of example 20. Detailed description EXAMPLE 1: Lithiation of FePO4 for the production of LIFePC in air at room temperature

[0029] 1 g of FePO4 powder obtained by total chemical delithiation of commercial LiFePO4 using Fe 3+in solution was mixed manually in a mortar with -880 mg of lithium iodide Lil (Acros Organics, 99%) with a molar ratio of 1 for -10 minutes at room temperature / air. The powder obtained was washed with a solution of concentration 2.6 10 -1 mol / L of Lil in ethanol and then dried at 60 °C. The recovered powder was characterized by XRD (Fig. 1).

[0030] Fig. 1 shows the DRX diffractograms of the starting commercial LiFePO4 (Fig. 1 a), the FePO4 obtained by delithiation of LiFePO4 (Fig. 1 b) and the powder recovered after lithiation by LiI (Fig. 1 c). The latter, Fig. 1 c.), shows the total disappearance of the diffraction peaks of the FePC phase and the presence of a single LiFePCU phase with the following lattice parameters: a = 10.317(1 ) Â, b = 5.996(1 ) Â, c = 4.702(1 ) Â and V = 290.83(2) Â3. This result confirms the total lithiation of the FePÛ4 phase in LiFePCU.

[0031] XRD diffractograms were recorded using the Bruker D8 Diffractometer equipped with a Cu Ko source (A Ka1 = 1.54056 Å and A Ka2 = 1.54439 Å). Another method of separating k / LiFePO4

[0032] Alternatively, the iodine I2 formed after the lithiation reaction can be removed by a process other than washing the iodide ions with alcohol, for example ethanol. It can be carried out by heating, which causes the iodine to sublimate in the form of gas. This heating is preferably carried out in an inert atmosphere, for example under a flow of Ar / N2 gas, or in a vacuum, at a temperature of 100 °C. Figure 2 shows a powder obtained according to Example 1 and which has been heated to 100 °C in a vacuum. The iodine is released in the form of a purple vapor, which allows the recovery of I2 in the form of gray crystals. EXAMPLE 2: Regeneration of a LiFePCU cathode at the end of its life in air at room temperature

[0033] The method according to the invention can allow regeneration by direct recycling. In this example, a LiFePCU cathode from a used 2.3 Ah commercial battery (LiFePO graphite, 26650 cylindrical cell) was used for chemical lithiation. The LiFePCU cathode powder was recovered and characterized by XRD (Fig. 3a), indicating the presence of two olivine phases, LiFePCU triphylite (a = 10.317(1 ) Â, b = 5.996(1 ) Â, c = 4.702(1) Â) and FePCU heterosite (a = 9.851(1 ) Â, b = 5.810(1 ) Â, c = 4.772(1 ) Â). The electrochemical properties of the recovered LiFePCU cathode were evaluated versus lithium in galvanostatic mode at C / 10 (Fig. 4a). The first discharge corresponds to the reduction of the FePCU phase. These results show that there is a lack of lithium in the cathode.

[0034] The used LiFePC cathode was regenerated using the process detailed above (Example 1) with a LiI / FePCU molar ratio of 1 for the 30% of FePC present in the cathode. The result of the XRD analysis (Fig. 3b) confirms the total lithiation of the LiFePCU cathode by showing the total disappearance of the characteristic peaks of the FePCU phase as well as the presence of a single LiFePCU phase.

[0035] The electrochemical performances of the regenerated LiFePCU cathode were also tested under the same conditions (Fig. 4b) indicating the good electrochemical signature of LiFePCU as well as a potential of 3.44 V. The absence of the FePCU reduction plateau during the first discharge confirms the complete lithiation of the FePCU phase present in the starting mixture. The material records a reversible capacity of approximately 168 mAh / g stable during dozens of cycles.

[0036] This process for regenerating a used LiFePC cathode preserves the electrode formulation (LiFePC, conductive carbon and polymer binder), the carbon coating as well as the particle morphology (Fig. 3c-d). This paves the way for more sustainable recycling of Li-ion batteries. In addition, the process can be carried out without the addition of solvent or additional heat treatment, which is certainly very useful for the recycling of end-of-life battery stocks in the coming years. EXAMPLE 3: Lithiation of FePO4 for the production of LiFePC under argon at 100 °C

[0037] 1 g of FePC>4 powder obtained by total chemical delithiation of commercial LiFePC using Fe 3+ in solution was mixed manually in a mortar with -880 mg lithium iodide Lil (Acros Organics, 99%) with a molar ratio of 1 for -10 minutes under argon, the mixture was heated at 100 °C for 12 hours under argon.

[0038] Fig. 5 shows the DRX diffractogram of FePÛ4 obtained by chemical delithiation of LiFePO4 (Fig. 5a) and that of the powder recovered after chemical lithiation (Fig. 5b), indicating the total disappearance of the peaks of the FePÛ4 phase in favor of the LiFePO4 phase with the appearance of the by-product I2. This result confirms the total lithiation under argon of the FePC phase in LiFePC>4.

[0039] Note: The by-product I2 formed during the reaction can be removed by washing with a solution of concentration > 2.6 10 -1 mol / L of Lil in ethanol then dried at 60°C.

[0040] Or by sublimation under vacuum or under a flow of Ar / N2 gas or under vacuum at >100 °C. EXAMPLE 4: Lithiation of FePO4 for the production of LiFePC at 80 °C

[0041] 1 g of FePO4 powder obtained by total chemical delithiation of commercial LiFePO4 using Fe 3+in solution was mixed manually in a mortar with -880 mg of lithium iodide Lil (Acros Organics, 99%) with a molar ratio of 1 for -10 minutes under argon, the mixture was heated at 80 °C for 72 hours under argon.

[0042] Fig. 6 shows the DRX diffractograms of FePO4 obtained by chemical delithiation of LiFePO4 (Fig. 6a) and that of the powder recovered after chemical lithiation (Fig. 6b), indicating the total disappearance of the peaks of the FePO4 phase in favor of the LiFePO4 phase. This result confirms the total lithiation of the FePO4 phase into LiFePO4.

[0043] Note: The by-product I2 formed during the reaction can be removed by washing with a solution of concentration > 2.6 10' 1 mol / L of Lil in ethanol then dried at 60°C or by sublimation under vacuum or under a flow of Ar / N2 gas or under vacuum at >100°C. Example 5: Lithiation of FePÛ4 under controlled atmosphere by mechanical grinding

[0044] 1 g of FePCU powder obtained by total chemical delithiation of commercial LiFePC using Fe 3+ in solution was mixed with -880 mg of lithium iodide Lil (Acros Organics, 99%) with a molar ratio of 1 by mechanical grinding using a mill Spex™ Mixer Mill 8000M type ball (sold by Fisher Scientific SAS, Boulevard Sébastien Brant - F67403 lllkirch) for -10 minutes under argon.

[0045] Fig. 7 shows the XRD of FePC obtained by chemical delithiation of LiFePC (Fig. 7a) and that of the powder recovered after chemical lithiation assisted by mechanical grinding (Fig. 7b), indicating the total disappearance of the peaks of the FePC phase in favor of the LiFePC phase. This result confirms the total lithiation of the FePCU phase into LiFePCU.

[0046] Note: The by-product I2 formed during the reaction can be removed by washing with a solution of concentration > 2.6 10 -1mol / L of Lil in ethanol then dried at 60°C or by sublimation under vacuum or under a flow of Ar / N2 gas or under vacuum at >100°C. EXAMPLE 6: LiMn0.66Feo,34P04 (LMFP) / in air at room temperature

[0047] The powder of the commercial material LiMn0,66Feo,34P04 (Fig. 8a) was partially chemically oxidized by mixing -241 mg NO2BF4 in 40 mL of acetonitrile at room temperature (Fig. 8b), the XRD result shows a shift of the initial peaks characteristic of LiMno,66Feo,34PC>4 and this indicates that the latter has indeed been delithiated (a = 10.160(1 ) Â, b = 5.987(1 ) Â, c = 4.794(1 ) Â and V = 291 ,59(2) Â 3 ). The electrochemical properties of delithiated LiMn0.66Feo.34P04 were evaluated versus Li + / Li° in galvanostatic mode at C / 20 (Fig. 8d). The first discharge corresponds to the reduction of the delithiated phase. These results show that there is a lack of lithium in this material up to 0.63 Li which indicates that the chemically delithiated phase may correspond to Li o ,37Mn o ,66Feo,34 PO4.

[0048] In order to chemically lithiate this delithiated material (Li o ,37Mn o ,66FeO,34 PO4), 0.6 g of this powder was mixed in a mortar with -500 mg of lithium iodide Lil (Acros Organics, 99%) with a molar ratio of 1 (relative to the missing 0.63 Li) for -10 minutes at room temperature / air. The resulting powder was washed with a solution of 1.5 10 -1mol / L of LiI in ethanol and then dried at 60 °C. The recovered powder was characterized by XRD (Fig. 8c), indicating the presence of a single phase LiMno,6eFeO,34P04 which is similar to the starting commercial material (a = 6.045(1 ) Â, b = 10.80(1 ) Â, c = 4.743(1 ) Â and V = 297.58(2) Â 3 ).

[0049] The electrochemical performances of the regenerated LiMn0,66Feo,34P04 were also measured under the same conditions (Fig. 8e) and confirm the electrochemical signature of LiMno,66Feo,34PC>4 with the total disappearance of the Mn"' and Fe'" reduction plateaus in the first discharge. These results confirm the total relithiation of the material. EXAMPLE 7: LiNi0.33Mn0, 33600, 3302 (NMC111) / in air at room temperature

[0050] The powder of the commercial material LiNi0.33Mn0.33Coo.3302 (Fig. 9a) was partially chemically oxidized by - 415 mg NO2BF4 in 40 mL of acetonitrile at room temperature (Fig. 9b), the XRD result shows a shift of the initial peaks characteristic of NMC11 1 and this indicates that the latter has indeed been delithiated. The electrochemical properties of the delithiated NMC1 11 have were evaluated versus Li7Li° in galvanostatic mode at C / 20 (Fig. 9d). The first discharge corresponds to the reduction of the delithiated phase. These results show a lack of lithium in this material up to 0.37 Li which indicates that the chemically delithiated phase may correspond to Lio,63Ni0,33Mn0,33Coo,3302.

[0051] For the chemical relithiation of this delithiated material, 0.6 g of the powder io,63Ni0,33Mn0,33Coo,3302Li was manually mixed in a mortar with -860 mg of lithium iodide Lil (Acros Organics, 99%) with a molar ratio of 1 (with respect to the missing 0.37 Li) for -10 minutes at room temperature / air. The resulting powder was washed with a solution of concentration 2.57 10' 1 mol / L of Lil in ethanol then dried at 60°C.

[0052] The recovered powder was characterized by XRD in a cell with a beryllium Be window under argon (Fig. 9c), and the presence of a single phase LiNio,33Mno,33Coo,3302 was confirmed. The electrochemical performances of the regenerated NMC11 1 were also tested under the same conditions (Fig. 9e) indicating the expected electrochemical signature for NMC1 11 as well as a very low capacity recorded at the first discharge < 2%. These results confirm the total lithiation of the material. EXAMPLE 8: LiNio,6Mn0,2Coo.202 (NMC622) / in air at room temperature

[0053] The powder of the commercial material LiNio,6Mno,2Coo,202 (Fig. 10a) was partially chemically oxidized by - 411 mg NO2BF4 in 40 mL of acetonitrile at room temperature (Fig. 10b), the XRD result shows a shift of the initial peaks characteristic of NMC622, indicating a change of lattice parameters in accordance with the delithiation. The electrochemical properties of the delithiated NMC11 1 were evaluated versus Li + / Li° in galvanostatic mode at C / 20 (Fig. 10d). The first discharge corresponds to the reduction of the delithiated phase. These results show that there is a lack of lithium in this material up to 0.3 Li which indicates that the chemically delithiated phase may correspond to Lio,7Ni0,6Mn0,2Coo,202.

[0054] For the chemical relithiation of this delithiated material, 0.6 g of the powder LiO,7Nio,6Mno,2Coo,202 was manually mixed in a mortar with -847 mg of lithium iodide LiI (Acros Organics, 99%) with a molar ratio of 1 (relative to the missing 0.3 Li) for -10 minutes at room temperature / air. The resulting powder was washed with a solution of concentration 2.53 10' 1 mol / L of Lil in ethanol then dried at 60°C.

[0055] The recovered powder was characterized by XRD (Fig. 10c), indicating the presence of a single LiNio,eMno,2Coo,202 phase whose lattice parameters correspond to the commercial material. The electrochemical performances of the regenerated NMC622 were also measured under the same conditions (Fig. 10e) indicating the expected electrochemical signature for NMC622 as well as a very low capacity recorded at the first discharge < 5%. These results confirm the total lithiation of the material. EXAMPLE 9: LiMn2Ü4 (LMO) / in air at room temperature

[0056] The powder of the commercial material LiMn2O4 (Fig. 11 a) was partially chemically oxidized by 220 mg NO2BF4 in 40 mL of acetonitrile at room temperature (Fig. 11b), the XRD result shows a shift of the initial peaks characteristic of LMO and this indicates that the latter has been delithiated. The electrochemical properties of the delithiated LMO were evaluated versus Li + / Li° in galvanostatic mode at C / 20 (Fig. 1 1d). The first discharge corresponds to the reduction of the delithiated phase. These results show that there is a lack of lithium in this material of up to 0.1 Li.

[0057] For the chemical relithiation of this delithiated material, 0.6 g of the powder Li0.9Mn2O4 was manually mixed in a mortar with -445 mg of lithium iodide Lil (Acros Organics, 99%) with a molar ratio of 1 (relative to the missing 0.1 Li) for -10 minutes at room temperature / air. The resulting powder was washed with a solution of concentration 1.33 10 -1 mol / L of Lil in ethanol then dried at 60°C.

[0058] The recovered powder was characterized by XRD in a cell with a beryllium Be window under argon (Fig. 11c), indicating the presence of a single LiMn2O4 phase that completely matches the commercial material. The electrochemical performances of the regenerated LMO were also tested under the same conditions (Fig. 11e) indicating the good electrochemical signature of the LMO as well as a very low capacity recorded at the first discharge < 1%. These results confirm the total lithiation of the material. EXAMPLE 10: LiCoO2(LCO) / in air at room temperature

[0059] The powder of the commercial material LiCoO2 (Fig. 12a) was partially chemically oxidized by 407 mg NO2BF4 in 40 mL of acetonitrile at room temperature (Fig. 12b), the DRX result shows a shift of the initial peaks characteristic of LCO and this indicates that the latter has been delithiated. The electrochemical properties of the delithiated LCO were evaluated versus Li + / Li° in galvanostatic mode at C / 20 (Fig. 12d). The first discharge corresponds to the reduction of the delithiated phase. These results show that there is a lack of lithium in this material of up to 0.25 Li.

[0060] For the chemical relithiation of this delithiated material, 0.6 g of the powder U0.75C0O2 was mixed in a mortar with -835 mg of lithium iodide Lil (Acros Organics, 99%) with a molar ratio of 1 (relative to the missing 0.25 Li) for -10 minutes at room temperature / air. The resulting powder was washed with a solution of concentration 2.5.10 -1 mol / L of Lil in ethanol then dried at 60°C.

[0061] The recovered powder was characterized by XRD (Fig. 12c), indicating the presence of a single LiMn2O4 phase that completely corresponds to the commercial material. The electrochemical performances of the regenerated LCO were also tested under the same conditions (Fig. 12e) indicating the good electrochemical signature of the LCO as well as a very low capacity recorded at first discharge < 3%. These results confirm the total lithiation of the material. EXAMPLE 11: Potassiation of hydrated Fe2(SO4)3 to form K2Fe(SO4)2.2H2O in air at room temperature

[0062] Commercial hydrated iron III sulfate powder was used as the starting material for chemical potassiation (Fig. 13a). 1 g of Fe2(SO4)3(H2O)7.25 powder (JCPDS file No. 01-071-1634 Kornelite on EVA (DIFFRAC.EVA software for indexing diffractograms obtained by the X-ray diffraction method) was manually mixed in a mortar with potassium iodide Kl (Acros Organics, 99%) in excess for ~10 minutes under air. The resulting powder was washed with a 1 M concentration of Kl in ethanol and then dried at 60 °C.

[0063] The recovered powder was characterized by XRD (Fig. 13b), indicating the presence of the K2Fe(SO4)2.2H2O phase with the following lattice parameters: a = 7.307(1 ) Â, b = 10.810(1 ) Â, c = 6.533(1 ) Â (Fig. 13c). EXAMPLE 12: Sodiation of FePC for the production of olivine NaFePC under argon at 300 °C

[0064] Olivine FePÛ4 obtained by chemical delithiation of commercial LiFePO4 by Fe 3+ in water was used as the starting material for chemical sodiation (Fig. 14a). 1 g of the FePC powder was manually mixed in a mortar with -994 mg of sodium iodide Nal (Acros Organics, 99%) with a molar ratio of 1, and then the mixture was heated at 300 °C for 5 hours under argon. The resulting powder was washed with a solution of concentration 2.65 10" 1 mol / L of Nal in ethanol then dried at 60°C.

[0065] The recovered powder was characterized by XRD (Fig. 14b), indicating the total disappearance of the FePO4 phase peaks and the presence of a single NaFePÛ4 divine phase with the following lattice parameters: a = 10.390(1 ) Â, b = 6.216(1 ) Â, c = 4.942(1 ) Â (Fig. 14c). This result confirms the total reduction of Fe'" to Fe" accompanied by the insertion of sodium into the FePC structure. EXAMPLE 13: Sodiation of hydrated Fe2(SO4)3 to form Na2Fe(SO4)2,4H2O in air at room temperature

[0066] Commercial hydrated iron III sulfate powder was used as the starting material for chemical sodiation (Fig. 15a). 1 g of Fe2(SO4)3(H2O)7.25 powder (JCPDS sheet No. 01-071-1634 Kornelite) was manually mixed in a mortar with sodium iodide NaI (Acros Organics, 99%) for -10 minutes in air. The resulting powder was washed with a 1 M NaI solution in ethanol and then dried at 60 °C.

[0067] The recovered powder was characterized by XRD (Fig. 15b), indicating the presence of a single Na2Fe(SC>4)2,4H2O phase. Examples of materials where the developed process cannot be applied (potential < 3 V / Li + / Li°) Comparative EXAMPLE 14: Lithiation test of FePO4-2H2O in air at room temperature

[0068] 0.4 g of commercial amorphous FePO4.2H2O powder (Sigma Aldrich) was manually mixed in a mortar with -286 mg of lithium iodide Lil (Acros Organics, 99%) with a molar ratio of 1 to air at room temperature.

[0069] Figure 16 shows the DRX diffractogram of the powder recovered after chemical lithiation, indicating the presence of peaks of the UI.3H2O phase resulting from the hydration of the starting Lil and an amorphous compound which may correspond to the starting FePO4.2H2O. This result shows that the lithiation reaction did not take place (FePO4.2H2O was not chemically lithiated). Comparative EXAMPLE 15: Sodiation test of FePO4-2H2O in air at room temperature

[0070] 0.4 g of commercial amorphous FePO4.2H2O powder (Sigma Aldrich) was mixed in a mortar with -321 mg of sodium iodide Nal (Acros Organics, 99%) with a molar ratio of 1 to air at room temperature.

[0071] Figure 17 shows the DRX diffractogram of the powder recovered after chemical lithiation, indicating the presence of the peaks of the Nal and Nal.2H2O phase resulting from the hydration of the starting Nal and a diffuse (amorphous) peak which may correspond to the starting FePO4.2H2O. This result shows that the sodiation reaction did not take place (FePO4.2H2O was not chemically sodiated). Comparative EXAMPLE 16: Potassiation test of FePO4.2H2O in air at room temperature

[0072] 04 g of commercial amorphous FePO4.2H2O powder (Sigma Aldrich) was manually mixed in a mortar with -355 mg of potassium iodide Kl (Acros Organics, 99%) with a molar ratio of 1 under air at room temperature.

[0073] Figure 18 shows the DRX diffractogram of the powder recovered after chemical lithiation, indicating the presence of the peaks of the initial Kl phase and an amorphous one which may correspond to the initial FePO4.2H2O. This result shows that the potassiation reaction did not take place (FePO4.2H2O was not chemically potassicated). Comparative EXAMPLE 17: FeOOH lithiation test in air at room temperature

[0074] 0.4 g of commercial FeOOH powder was manually mixed in a mortar with -602 mg of lithium iodide Lil (Acros Organics, 99%) with a molar ratio of 1 to air at room temperature.

[0075] Figure 19 shows the XRD diffractogram of the commercial FeOOH powder (Fig. 19a) as well as the powder recovered after chemical lithiation (Fig. 19b), indicating the presence of the peaks of the starting compounds FeOOH and UI.3H2O resulting from the hydration of starting Lil. This result shows that the lithiation reaction did not take place (FeOOH was not chemically lithiated). Comparative EXAMPLE 18: FeOOH sodiation test in air at 100°C

[0076] 0.4 g of commercial FeOOH powder was manually mixed in a mortar with -675 mg sodium iodide Nal (Acros Organics, 99%) with a molar ratio of 1 in air at 100 °C for 12 h.

[0077] Figure 20 shows the XRD diffractogram of the commercial FeOOH powder (Fig. 20a) as well as the powder recovered after chemical sodiation (Fig. 20b), indicating the presence of the peaks of the starting compounds namely FeOOH, NaI and NaI.2H2O resulting from the hydration of starting NaI. This result shows that the sodiation reaction did not take place (FeOOH was not chemically sodiated). Comparative EXAMPLE 19: FeOOH potassiation test in air at 100°C

[0078] 0.4 g of commercial FeOOH powder was manually mixed in a mortar with -747 mg potassium iodide Kl (Acros Organics, 99%) with a molar ratio of 1 in air at 100 °C for 12 h.

[0079] Figure 21 shows the XRD diffractogram of the commercial FeOOH powder (Fig. 21 a) as well as the powder recovered after chemical sodiation (Fig. 21 b), indicating the presence of the peaks of the starting compounds namely FeOOH and Kl. This result shows that the potassiation reaction did not take place (FeOOH was not chemically potassicated). EXAMPLE 20 of measurement of the average potential of (LiFePO4) vs Li + / Li°

[0080] To carry out this measurement by CV on a potentiostat, an electrochemical cell, consisting of a working electrode containing the active material to be analyzed, a reference electrode as well as a counter electrode and an electrolyte, is used. The variation of the current l(mA) as a function of the potential (V) is measured by scanning the potential with scanning speeds given in (mV / s). The curve obtained during this CV generally presents, when the material is active, an oxidation peak (oxidation potential noted Eox) and a reduction peak (reduction potential noted Ered), which allow the determination of the average potential of the material E = Ered + (Eox - Ered) / 2.

[0081] In the case of the LFP cathode material (LiFePC), the potential measurement was performed versus lithium (which is both the anode and the reference) using two methods; after preparation of the electrochemical cells (in a glove box under argon) each containing approximately 10 mg of LFP / C active material / carbon powder as cathode. The two electrodes are separated by two glass fiber separators soaked in LP30 electrolyte, which is a molar solution of LiPFe in a mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC) with a mass ratio of 1 / 1.

[0082] According to a first method (CV), the measurements were carried out at 25 °C, using a VMP potentiostat, measuring the current I (mA) as a function of the potential (V) with a scanning speed of 0.1 mV / s between 2.1 V and 4.2 V. The curve obtained shows an oxidation peak around "'3.64 V / Li + / Li° and a reduction peak at ~3.24 V / Li + / Li° which indicates an average LFP potential of 3.44 V / Li + / Li°. (Figure 22).

[0083] According to a second method, a potential / composition curve (E(V)= f(x)) in galvanostatic mode (Fig 4), which is the measurement of the variation of the potential as a function of the composition under a constant current with a C / 10 regime (one mole of electron exchanged in 10 hours) in the potential window 2.1 V - 4.2 V.

[0084] The derivative of x with respect to the potential (dx / dV) led to a curve similar to a CV curve (Fig. 2b). On the latter, an oxidation peak can be observed around ~3.45 V / Li + / Li° and a reduction peak at ~3.40 V / Li + / Li° which indicates an average LFP potential of 3.44 V / Li + / Li°. References

[0001] 1B. Chen, M. Liu, S. Cao, G. Chen, X. Guo, X. Wang, Regeneration and performance of LiFePO4 with Li2CO3 and FePO4 as raw materials recovered from spent LiFePO4 batteries, Mater. Chem. Phys. 279 (2022). https: / / doi.Org / 10.1016 / j.matchemphys.2022.125750 2 J. Zhang, J. Hu, Y. Liu, Q. Jing, C. Yang, Y. Chen, C. Wang, Sustainable and Facile Method for the Selective Recovery of Lithium from Cathode Scrap of Spent LiFePO4 Batteries, ACS Sustain. Chem. Eng. 7 (2019) 5626-5631. https: / / doi.org / 10.1021 / acssuschemeng.9b00404 3 T. Wang, X. Yu, M. Fan, Q. Meng, Y. Xiao, Y.-X. Yin, H. Li, Y.-G. Guo, Direct regeneration of spent LiFePO 4 via a graphite prelithiation strategy, Chem. Commun. 56 (2020) 245-248. https: / / doi. org / 10. 1039 / C9CC08155K 4M.J. Ganter, B.J. Land!, C. W. Babbitt, A. Anctil, G. Gaustad, Cathode refunctionalization as a lithium ion battery recycling alternative, J. Power Sources. 256 (2014) 274-280. https : / / doi. org / 10.1016 / j.jpowsour.2014.01.078

Claims

Demands

1. A process for the solid-state alkalinization of a salt comprising at least one transition metal and being partially or totally deficient in an alkali metal, said process being characterized in that it comprises the following steps: a) mixing, in solid form, said alkali-deficient (or alkali-free) salt with the corresponding alkali iodide, also in solid form, to obtain a solid mixture; b) reacting said solid mixture to obtain molecular iodine and an alkali-enriched salt of said transition metal; and, optionally, c) separating the molecular iodine from said solid mixture, wherein said alkali-enriched transition metal salt is chosen to have, in the solid state and under normal conditions of pressure and temperature, an average potential with respect to lithium (Li₂O₅). + / Li°) of more than 3V.

2. The method according to claim 1, wherein a heating step is carried out during or subsequent to step a) and / or b), preferably this heating step is carried out at a temperature below 150°C, more preferably below 100°C.

3. The method according to claim 1 or 2, wherein steps a) and / or b) are carried out under ambient air or under an inert atmosphere.

4. The process according to claim 1, wherein steps a) and / or b) are carried out without heating and / or at room temperature, and wherein, preferably, the process is carried out without heating excluding step c).

5. The method according to claim 1 or 4, wherein steps a) and / or b) are carried out in the presence of air.

6. The process according to any one of claims 1 to 5, wherein said salt comprising at least one alkali and one transition metal, is an electrochemically active compound such as: - that an olivine-type salt having the general formula XYTCU, where T is at least one tetravalent cation (in particular Si, P, As), X is at least one alkali cation and Y is at least one non-alkaline metallic cation; or - a compound with formula AM1 x M2yM3zO2, where x + y + z = 1, where A is an alkali metal, preferably Li and / or Na, and where M1, M2, and M3 are each a non-alkali metal, preferably chosen from the group consisting of the metal ions Co 3+ , Neither 3+ , Mn 3+ 2, Al 3+ Fe 3+ , V 3+ , Cr 3+ , Nb 3+ , Mo 3+ .

7. The method according to any one of claims 1 to 6, wherein said compound comprising a transition metal and being deficient in an alkali has been part of an electrode and / or is in mixture with another component such as a conductive agent, for example graphite, carbon black, fibers and / or carbon nanotubes, and / or a binder, for example polyvinylidene fluoride and / or polytetrafluoroethylene.

8. The process according to any one of claims 1 to 7, wherein the separation step c) is carried out by washing said mixture with an organic solvent such as alcohol, for example ethanol, this washing optionally being followed by a drying step.

9. The process according to any one of claims 1 to 7, wherein the separation step c) is carried out by heating said mixture under conditions permitting the sublimation of molecular iodine, preferably either under an inert atmosphere, for example under a flow of Ar / N2 gas, or under vacuum.

10. A recycling process for an electrochemically active material used in batteries using alkali ions for charge transfer and comprising the steps described in the process according to claims 1 to 9.

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