Recovery of water-tolerant conductive salts from spent organic electrolytes in energy storage devices

Abstract

The present invention concerns a method for the separation of salts and organic components from a soft material of an energy storage or conversion device, which involves addition of water into the soft material, addition of an organic phase, separation of the organic phase from the aqueous phase, removal of water to achieve a desired salt concentration and recovery of one or more organic components from organic phase. The invention further concerns the use of salts and / or organic components received by the method of the invention.

Description

[0001] Recovery of water-tolerant conductive salts from spent organic electrolytes in energy storage devices

[0002] Field of the Invention

[0003] This invention is related to a water-based recovery method of water-tolerant conductive salts in spent organic electrolytes. This method is designed to be applied to the spent organic electrolytes extracted from energy storage devices, including supercapacitors, rechargeable metal-ion batteries, metal-ion hybrid devices and redox-flow batteries. This method should be independent of the type of energy storage devices and their life cycle. This method is of great importance and interest, since these devices are experiencing exponential growth in global demand to tackle the modern challenges of the sustainable energy transition.11!

[0004] Background of the Invention

[0005] In general, an electrolyte for energy storage devices is comprised of one or more conductive salts, a mixture of solvents and several additives. The state-of-the-art electrolyte for metal-ion batteries consists of a metal-ion (e.g., Li+, Na+, K+, Zn+2) conducting salt dissolved in a mixture of organic solvents in different volume ratios (Fig. 1). The aforementioned metal cations in the conductive salt are mostly coupled with fluorinated anions (Fig. 2). Among them, it is possible to classify conductive salts according to the tolerance of the anion towards hydrolysis in presence of water. The most commonly used anion is hexafluorophosphate (PFsj, which rapidly hydrolyzes, posing safety hazards due to the generation of corrosive fluorine-containing compounds (e.g., hydrofluoric acid).® Imide-based anions show a remarkable inertness and compatibility with water and therefore have been proposed as potential replacements for conventional hexafluorophosphate-based salts.® These salts also offer high thermal stability, conductivity and transfer number. However, their high cost and complex production processes have limited their large-scale applications.®

[0006] One approach to tackle this issue is to recover and reuse the spent electrolytes from energy storage devices. The recovery method should be straightforward to handle, and have a low economic and environmental impact, such as a water-based extraction process. To the best of our knowledge, the electrolyte recovery is often overlooked in the literature and main approaches focus on water hydrolysable conductive salts. In addition, the recovery of the conventional LiPFs through hydrometallurgical processes is hindered by its sensitiveness to water, which forces the use of strictly anhydrous reagents.® In this regard, the electrolyte recovery has been previously disclosed in several patent publications. CN106025420A and CN102496752B focus in the recovery of the hexafluorophosphate-based salt through the use of hydrogen fluoride and additional organic solvents (e.g., acetonitrile, carbonate-based solvents).161On the other hand, FR3024287A1 and CN111498878A, showed the requirement of additional chemicals (e.g., acids and alkalis) besides water for the recovery of the lithium contained in the lithium salt.171In these four previous cases, the lithium salt was modified in the extraction process, avoiding its direct reuse. Also, they require use of several chemicals, and the release of hazardous fluorine-containing compounds cannot be avoided due to the high sensitivity of LiPFe salt towards reacting with water.

[0007] US7,198,865B2 and US11, 777,15662 involve the use of supercritical fluid combined or not with the assistance of organic solvents (e.g., carbonate-based solvents) for the recovery of the electrolyte.181In these cases, complex instrumentation is required. In summary, previously published processes do not deal with the direct extraction of conductive salt from an energy storage device using a simple and sustainable aqueous-based procedure.

[0008] There is therefore a need for a simple method for the separation of salts and organic components from a soft material of an energy storage or conversion device without the mentioned problems. The method should work without modifying the salt, hazardous compounds or complex instrumentation.

[0009] Summary of the Invention

[0010] This document teaches a method for the separation of salts and organic components from a soft material of an energy storage or conversion device, which involves the following steps: a. Addition of water into the soft material; b. Addition of an organic phase; c. Separation of the organic phase from the aqueous phase; d. Removing of water to achieve a desired salt concentration; e. Recovery of one or more organic components from organic phase. In a preferred embodiment, the soft material is filtered in case of insoluble solid residues or treated chemically or physically to remove any possible hosting material or matrix in which is contained such as for example but not limited to polymeric frameworks or ceramic coatings.

[0011] The method can involve a repeated extraction of the organic phase until the salt is removed from the organic phase and the obtained aqueous fractions are recombined.

[0012] In one aspect of the invention the pure salt can be extracted.

[0013] The method works with soft material which is extracted from an electrolyte, preferably from a spent electrolyte, more preferably collected from exhausted energy storage or conversion devices.

[0014] In another aspect of the invention the salt Is a conductive salt, preferably with one or more water-tolerant anions such as for example but not limited to: bis(trifluoromethyllsulfonyl)imide, (TFSI-); bis(fluorosulfonyl)imide, (FSI-);

[0015] (fluorosulfonyl)(trifluoromethylsulfonyl)imide, (FTFSI-); difluorophosphate (DFP-); bis(oxalato)borate (BOB-); difluoro(oxalato)borate (DFOB-); sulfate; phosphate; carbonate, chloride; nitrate; acetate; formate; citrate; oxalate; tartrate; malate; lactate; succinate; sulfonate; phosphonate; benzoate; phthalate; borate; thiosulfate; permanganate; chromate; dichromate; silicate; hydrosulfide.

[0016] In another aspect of the invention the salt is a conductive salt, preferably with one or more cations such as for example but not limited to: alkali-ion (e.g. Li+, Na+, K+), alkaline-earth-ion (e.g. Ca2+, Ba2+, Mg+2), transition-metal-ion (e.g. Zn2+, AI+3, Fe+2, Fe3, Mn+2, Co+2, Ag+, V+5), ammonium, tetraalkylammonium (e.g. tetramethylammonium, tetraethylammonium, N,N-butyl-methyl-pyrrolidinium), imidazolium (e.g. ethylmethylimidazolium, butylmethylimidazolium).

[0017] In another aspect of the invention the soft material contains one or more aprotic polar organic solvents belonging to the family of nitriles, dinitriles, methoxynitriles, carbonates, esters, dioxolanes, sulfoxides, sulfones, sultones, amides, pyrrolidones, oxazolidinones, imidazolidones, nitroalkyls, phosphoesters and ureas such as but not limited to: acetonitrile, proprionitrile, butyronitrile, glutaronitrile, 2-methyl glutaronitrile, adiponitrile, methoxyacetonitrile, methoxyproprionitrile, methyl 3-cyanopropionate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate, 2,3-butylene carbonate, t -butylene carbonate, pentylene carbonate, ethyl acetate, methyl acetate, y-butyrolactone, y-valerolactone, 6-valerolactone, cyrene, dimethyl sulfoxide, dimethyl sulfone, ethyl methyl sulfone, methyl isopropyl sulfone, ethyl isopropyl sulfone, ethyl isobutyl sulfone, isopropyl isobutyl sulfone, isopropyl sec-butyl sulfone, butyl isobutyl sulfone, sulfolane, 3-methyl sulfolane, 1,3-propanesultone, 1,4- butanesultone, N,N-dimethyl formamide, N,N-dimethyl acetamide, N- methylpyrrolidone, N- methyl oxazolidinone, N,N-dimethyl imidazolidinone, nitromethane, nitroethane, trimethylphosphate, tetramethylurea.

[0018] The method can also be used when the organic phase contains one or more aprotic apolar organic solvents belonging to the family of aliphatic, aromatic, ester, ether solvents, for example but not limited to: petroleum ether (bp 40-60, 60-80, 80-100), n-hexane, n-heptane, n-octane, isooctane ciclohexane, methyl cyclohexane, benzene, toluene, xylene, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, 2-ethylhexyl acetate, methyl propionate, methyl butyrate, methyl valerate, methyl hexanoate, methyl nonanoate, methyl laurate, methyl myristeate, 2-ethylhexyl nonanoate, diethyl ether, methyl tert-butyl ether, cyclopentyl methyl ether, diphenyl ether.

[0019] Furthermore salts and / or organic components received by this method can be re-used in an energy storage or conversion device.

[0020] This document presents the application of a recovery method for spent electrolytes from energy storage devices. This method is based on a liquid-liquid extraction procedure. The main objective is to effectively recover components in spent electrolytes (e.g., conducting salt, solvent and eventually additive) for their reuse. Several relevant terms are defined as follows:

[0021] - Soft material, comprising liquids, colloids, polymers, foams, gels, granular materials, liquid crystals.

[0022] Electrolyte, is a solution consisting of one or more water-tolerant conducting salts (e.g., imide-based salts), one or more organic solvents and one or more additives.

[0023] - Pristine electrolytes, refer to the electrolytes that are freshly prepared and ready for use in energy storage devices, or those that have not yet been electrochemically used.

[0024] - Spent electrolytes, refer to the electrolytes that have been used in energy storage devices until the device reaches a certain life-cycle threshold (e.g. charge retention < 80 %). Liquid-liquid extraction, is the method used to separate different components in a mixture based on their different solubilities in two immiscible liquid phases.

[0025] - Immiscible liquid phases, in this method consist in a) an aqueous phase; b) an organic phase, composed of a mixture of selected organic solvents in a specific volume ratio.

[0026] When selecting organic solvents and their volume ratio as the organic phase, certain requirements need to be considered:

[0027] - Solubility, the organic components of the spent electrolyte should be soluble in the organic phase.

[0028] - Hydrophobicity, the components of the organic phase should not be miscible with the aqueous phase.

[0029] - Boiling point, the organic solvents of the organic phase should have similar boiling points, which differ from the boiling points of the organic components in the spent electrolyte. These aspects improve the recovery of both the organic phase and the organic components of the spent electrolyte.

[0030] Utilizing this developed recovery procedure, the water-tolerant conducting salt is recovered in the aqueous phase, while the remaining organic components (electrolyte solvent and additive) are recovered in the organic phase. The conducting salt, organic solvent and additive are further purified from their respective aqueous and organic phases through reduced-pressure distillation. The conductive salt, recovered from the spent electrolyte in the aqueous phase, can be directly reused in energy storage devices without the need for further purification steps, and achieving performances superimposable to devices tested with conductive salt obtained from the recovery process applied to pristine electrolyte. This result is uncommon for recovered spent electrolytes, whose performances are typically not satisfying if compared to pristine electrolytes. This is mainly due to the degradation of the conductive salt during the recovery process.

[0031] Description of the Figures

[0032] Fig. 1 Shows the chemical structure of some of the state-of-the-art typical dipolar aprotic solvents used in energy storage devices: ethylene carbonate, EC; dimethyl carbonate, DMC; ethyl methyl carbonate, EMC; diethyl carbonate, DEC; propylene carbonate, PC; gamma- butyrolactone, GBL; gamma-valerolactone, GVL; 1,3-dioxolane, DOL.

[0033] Fig. 2 Shows chemical structures of some of the state-of-the-art typical salts used in energy storage devices. Anion labelling: hexafluorophosphate, PFs~; bis(trifluoromethylsulfonyl)imide, TFSI’; bis(fluorosulfonyl)imide, FSI”; fluorotrifluoromethylsulfonyl imide, FTFSI*.

[0034] Fig. 3 Schematically represents the aqueous-organic phase extraction procedure followed.

[0035] Fig. 4 Shows the LiTFSI extraction yield in the aqueous phase after each extraction step. The calculation was performed both by TGA and NMR analysis.

[0036] Fig. 5 Compares the electrochemical performance of the recovered aqueous LiTFSI from pristine and spent electrolytes when employed as the electrolytes for a symmetrical electrochemical double layer capacitor in a voltage range from 0.0 to 1.0 V. The recovered aqueous LiTFSI from pristine electrolyte is denoted as "pristine", while that from spent electrolyte is named "spent". Showing the cyclic voltammetry curves of the devices using the "pristine" (Fig. 5a) and the "spent" (Fig. 5b) recovered electrolytes.

[0037] Fig. 6 Compares the electrochemical performance of the recovered aqueous LiTFSI from pristine and spent electrolytes when employed as the electrolytes for a symmetrical electrochemical double layer capacitor in a voltage range from 0.0 to 1.0 V. Showing the values of capacitance retention along long-term cycling for 150,000 cycles at 5 A g’1(Fig. 6a) and when holding the upper potential limit 400 h in steps of 10 h and cycling at 1 A g-1(Fig. 6b) for both "pristine" and "spent" recovered electrolytes.

[0038] Detailed Description of the Invention

[0039] The extraction process related to the invention will now be described based on the scheme depicted in Fig. 3. Despite the performances of recovered conductive salts are typically non- satisfactory if compared to pristine electrolytes, our extraction process provided a recovered conductive salt with superimposable performances compared to pristine ones. The process is designed to be applied to spent electrolytes containing water-tolerant conductive salts, like imide-based salts. This process should be independent of the type of energy storage devices and their life cycle. The separation process takes advantage of the use of a tailored organic phase with two or more organic solvents, in different proportions, that need to be unmixable with water-diluted spent electrolyte, and still solubilize organic components of the electrolyte. Hereinafter, the specific steps of the process will be discussed. For Example, the organic phase may comprise two or more organic solvents having boiling points (at atmospheric pressure) within a temperature range of ±20 °C, preferably within ±15 °C, more preferably within ±10 °C, and most preferably within ±5 °C of each other. This similarity in boiling points facilitates their efficient recovery through distillation as a single fraction, minimizing the need for complex separation techniques and preserving the volumetric ratio of the original organic phase.

[0040] First, a volume of spent electrolyte is collected and diluted in water by the addition of 0.5 - 2 equivalent volumes, more preferably in the range of 0.9 - 1.1 equivalents. In the case of the formation of insoluble precipitates, they are preliminarily removed by filtration. Previous treatments would also be required in the case that the soft material is encapsulated inside of a host material. Then, 20-30 equivalent volumes (respect to diluted electrolyte) of the organic phase are added to the aqueous phase and thoroughly mixed. The phases are left to settle until the complete separation of the two liquid phases. In this step, all the organic components and part of the conductive salt of the spent electrolyte are extracted in the organic phase. The first aqueous phase (Rwp) is then recovered, and a comparable volume of fresh water is added to the organic phase, preferably 1 - 2 equivalent volumes. Then, the mixing and settling steps are repeated to extract the residual content of conductive salt from the organic phase in fresh aqueous phases. This process is repeated as few times as possible to guarantee the complete extraction of the conductive salt (95 - 99 wt%), without extracting organic compound(s) from the spent electrolyte. The total number of repeated extraction steps should be in any case not more than five.

[0041] The aqueous phases are recollected and distilled under vacuum and temperature until fully evaporating the water to obtain the pure salt or until reaching the desired volume of water for the production of an aqueous solution with desired salt concentration.

[0042] Also, the residual organic phase is distilled under vacuum and temperature to obtain two fractions:

[0043] - Distillation tail, containing the organic solvents derived from the spent electrolyte;

[0044] - Distillate, containing the organic solvents used to build up the organic phase.

[0045] Overall recovery yield of organic solvent(s) derived from the spent electrolyte (distillation tail) are comprised between 70 - 90%, while the recovery of the solvents from the organic phase (distillate) is comprised between 90 - 100%. Examples

[0046] Example 1. Preparation of pristine electrolyte with water-tolerant conductive salt.

[0047] An electrolyte consisting of 1 M lithium bis(trifluoromethylsulfonyl)imide (LiTFSI, Solvionic) as the conducting salt, gamma-valerolactone (GVL, Sigma Aldrich) as the solvent and 2 wt% vinylene carbonate (VC, Thermo Scientific Chemicals) as the additive was prepared in an argon- filled glovebox (Labmaster Pro MBraun). Before preparing the electrolyte, GVL was dried over molecular sieves 3 A (Sigma Aldrich) and the water content confirmed to be below 20 ppm by Karl Fischer Titration (Metler Toledo instrument). The so-prepared electrolyte is hereinafter defined as pristine electrolyte A.

[0048] Example 2. Cycling protocol to get spent electrolyte

[0049] To obtain the spent electrolyte A, the pristine electrolyte A was subject to electrochemical protocol using X-type[9]Swagelok cells with a half-cell configuration: graphite electrodes (GE) vs. metallic lithium. GEs were prepared using graphite powder (TIMREX SFG 6, TIMCAL), carbon black Super P C65 (C-NERGY, Imerys), and sodium carboxymethylcellulose (CRT 2000 GA, Walocel) keeping a 90:5:5 mass ratio. An ink was produced from these components by the addition of water and mixing with a ball-miller. The as-obtained slurry was cast onto copper foil and dried overnight under ambient conditions. Electrodes with 12 mm in diameter were punched out from the cast and further dried overnight under vacuum at 65 °C. The electrode mass loading was adjusted through the wet thickness of the coater. The graphite electrode active masses were in the range from 1.1 to 1.7 mg cm'2.

[0050] X-type Swagelok cells were then assembled in a half-cell configuration using the as-prepared GE as the working electrodes and an oversized metallic lithium disc serving simultaneously as the reference and counter electrodes. During the cell assembly, a volume of 2 mL of pristine electrolyte A was employed. The cells were galvanostatically cycled in MPG-2 (Biologic) potentiostat between 0.005 - 2.0 V vs. Li+ / Li, starting with the first cycle at 0.05 C, followed by 5 cycles at 0.1 C and 200 cycles at 1 C (current density of 1 C according to theoretical capacity of graphite, 372 mA g'1). The long-term cycling at 1 C served to emulate the conventional operation conditions that led to the ageing of the device, aiming to realistically age the electrolyte to obtain the spent electrolytes. The so-obtained spent electrolyte A was extracted from the cell in an argon-filled glovebox. Example 3. Extraction protocol

[0051] For the extraction procedure, the organic solvents cyclohexane (Riedel-de Haen) and ethyl acetate (Sigma Aldrich) were selected as the organic phase in a 50:50 volume ratio. Distilled water was used as the aqueous phase. in the extraction procedure, 1 mL of spent electrolyte A, 1 mL of distilled water and 50 mL of the organic phase (ethyl acetate and cyclohexane in 50:50 vol%) were mixed in a separating funnel. The two immiscible liquid phases {aqueous and organic phase) were settled until complete separation was observed. The resulting aqueous phase was collected in a vial. Following, 2 mL of distilled water were added to the organic phase remaining in the separating funnel. After thorough mixing and settling for 30 minutes, the aqueous phase was collected, and the extraction was repeated. This step was repeated three times. The yield of LiTFSI recovered in the aqueous phase after each extraction was measured using thermogravimetric analysis (TGA, Perkin Elemer) with a sample volume of 12 pL. As a result, a diluted LiTFSI aqueous solution and an organic phase containing GVL solvent and VC additive were obtained. These phases were subjected to reduced-pressure distillation in a rotary evaporator (Buchi Rotavapor R-215). Excess water was successfully removed from the LiTFSI aqueous solution until reaching a LiTFSI concentration comprised between 1.5 and 1.8 M (final volume 0.65 - 0.55 mL), while GVL and VC additive were separated from the organic phase (ethyl acetate and cyclohexane) achieving 78 wt% of recovery. Thanks to the comparable boiling points of the used organic solvents, the collected organic distillate (93 wt% respect to the total used mass) mixture can be directly reused since its molar composition is preserved. Fig. 3 depicts the steps described above for the extraction procedure. A similar extraction procedure was carried out using pristine electrolyte A. The process has been also replicated using deuterium oxide as the aqueous phase. This allowed to double-check the LiTFSI extraction yield also by19F nuclear magnetic resonance (NMR, Bruker) in each aqueous phase. Fig. 4 shows the LiTFSI extraction yields obtained by TGA and NMR analysis, and in both cases, an overall yield >99 wt% was obtained.

[0052] Example 4. Testing the recovered concentrated aqueous phase.

[0053] The concentrated aqueous phase was directly tested as an electrolyte in a symmetric electric double-layer capacitor (EDLC). Two recovered samples were compared: (1) the recovered concentrated aqueous phase from pristine electrolyte A, denoted as pristine;

[0054] (2) the recovered concentrated aqueous phase from spent electrolyte A, denoted as spent.

[0055] Activated carbon (AC) electrodes were prepared using brewery's spent grain activated carbon (AC-BSG), carbon black Super P C65 (C-NERGY, Imerys), and sodium carboxymethylcellulose NaCMC (CRT 2000 GA, Walocel) in a 90:5:5 mass ratio using water as a dispersant and mixing all components with a ball-miller. The as-prepared water-based ink was cast on pre-etched (one minute at 60 °C in 5% w / v KOHaqbath at 60 °C) aluminum foil and dried overnight under ambient conditions. Electrodes with 12 mm in diameter were punched out from the cast and dried overnight under vacuum at 65 °C. The electrode mass loading was adjusted through the wet thickness of the coater. The AC-BSG electrodes active masses were in the range from 0.6 to 0.8 mg cm’2.

[0056] Two electrode Swagelok cells were assembled in a full-cell symmetric configuration using two AC-BSG electrodes with similar masses. A glass-fiber (Whatman GF / D) was used as the separator emedded in 120 pL of the pristine or spent recovered electrolytes. The electrochemical performance of the cell was evaluated in the voltage range of 0.0 to 1.0 V through cyclic voltammetry (CV) at different scan rates, followed by galvanostatic charge / discharge at various current densities. The long-term stability of the cells was assessed through galvanostatic charge / discharge at 5 A g’1for 140,000 cycles and a floating test for a total of 400 hours. In the floating test, the cell was held at the potential upper limit (1.0 V) for 10 hours. Each potential hold was followed by 10 galvanostatic charge / discharge cycles at 1 A g1.

[0057] Fig. 5a-b compares the CV profiles of the EDLCs using the recovered aqueous LiTFSI from pristine (Fig. 5a) and spent (Fig. 5b) electrolytes. Both demonstrate comparable rectangular- shaped CV profiles, characteristic of capacitive behavior in EDLCs. This indicates that the LiTFSI is no significantly affected by the extraction process neither for the pristine nor for the spent ones, and can be directly reutilized in energy storage applications, like in this case, for aqueous EDLC devices. Long-term cycling (Fig. 6a) and floating test (Fig. 6b) further prove the stability of the recovered electrolytes (both pristine and spent). Despite a slightly lower retention is measured from the long-term cycling and floating for the spent sample. The results are quite comparable. Specifically, more than 80% of the initial capacitance is retained for both samples after 140000 charge / discharge cycles at 5 A g’1(Fig. 6a), Similarly, both electrolytes retain more than 80% of their initial capacitance after 400 h of floating at 1.0 V (Fig. 6b). It is also worth remarking that coulombic efficiency values of nearly 100% are retained during the stability measurements regardless of whether the spent or pristine recovered electrolyte was employed. Also, the galvanostatic curve of the spent electrolyte seems not to be considerably distorted after the stability measurements (inset Fig. 6a and 6b). These results confirm that the spent recovered electrolyte displays promising electrochemical behavior similar to its pristine counterpart and that the aqueous-based extraction procedure is reliable. In summary, the recycled conductive salts obtained from both pristine and spent electrolytes showed intact functionality and high performance when used in electrolytes for other energy storage devices.

[0058] References

[0059] [1] a) D. Bresser, A. Moretti, A. Varzi, S. Passerini, in Encyclopedia of Electrochemistry: Batteries, Vol. 1 (Eds: D. Bresser, A. Moretti, A. Varzi, S. Passerini), Wiley-VCH, Weinheim, Germany 2020; b) S. V. Venkatesan, A. Nandy, K. Karan, S. R. tarter, V. Thangadurai, Electrochem. Energy Rev. 2022, 5.

[0060] [2] S. F. Lux, J. Chevalier, I. T. Lucas, R. Kostecki, ECS Electrochem. Lett. 2013, 2, A121.

[0061] [3] 0. V. Bushkova, T. V. Yaroslavtseva, Y. A. Dobrovolsky, Russ. J. Electrochem. 2017, 53, 677.

[0062] [4] T. F. Burton, R. Jommongkol, Y. Zhu, S. Deebansok, K. Chitbankluai, J. Deng, 0. Fontaine, Curr. Opin. Electrochem. 2022, 35, 101070.

[0063] [5] B. Niu, Z. Xu, J. Xiao, Y. Qin, Chem. Rev. 2023, 123, 8718.

[0064] [6] a) L. Zhou, H. Liu, X. Ye, X. Guo, D. Liu, H. Zhang, Chinese Patent CN102496752B, 2013; b) J. Hu, C. Wang, L. Cao, Chinese Patent CN106025420A, 2016.

[0065] [7] a) D. Jiang, Chinese Patent CN111498878A, 2020; b) E. Billy, R. Laucournet, France Patent FR3024287A1, 2016.

[0066] [8] a) S. E. Sloop, United States Patent US7198865B2, 2007; b) A. L. Lipson, United States

[0067] Patent US11777156B2, 2023.

[0068] [9] R. Kost, F. A. Kreth, A. Balducci, ChemElectroChem 2024, 11.

Claims

1. Claims1. A method for the separation of salts and organic components from a soft material of an energy storage or conversion device, which involves the following steps: a) Addition of water into the soft material; b) Addition of an organic phase; c) Separation of the organic phase from the aqueous phase; d) Removing of water to achieve a desired salt concentration; e) Recovery of one or more organic components from organic phase.2 The method of claim 1, wherein the soft material is filtered in case of insoluble solid residues or treated chemically or physically to remove any possible hosting material or matrix in which is contained such as for example but not limited to polymeric frameworks or ceramic coatings.3 The method of claim 1 or 2, wherein a repeated extraction of the organic phase until the salt is removed from the organic phase and the obtained aqueous fractions are recombined.4 The method of any of the above claims, wherein the pure salt is extracted.5 The method of any of the above claims, wherein the soft material is extracted from an electrolyte, preferably from a spent electrolyte, more preferably collected from exhausted energy storage or conversion devices.6 The method of any of the above claims, wherein the salt is a conductive salt, preferably with one or more water-tolerant anions such as for example but not limited to: bis(trifluoromethyllsulfonyl)imide, (TFSI'); bis(fluorosulfonyl)imide, (FST);(fluorosulfonyl)(trifluoromethylsulfonyl)imide, (FTFSI ); difluorophosphate (DFP ); bis(oxalato)borate (BOB j; difluoro(oxalato)borate (DFOBj; sulfate; phosphate; carbonate, chloride; nitrate; acetate; formate; citrate; oxalate; tartrate; malate; lactate; succinate; sulfonate; phosphonate; benzoate; phthalate; borate; thiosulfate; permanganate; chromate; dichromate; silicate; hydrosulfide.7 The method of any of the above claims, wherein the salt is a conductive salt, preferably with one or more cations such as for example but not limited to: alkali-ion such as Li+, Na+, K+,alkaline-earth-ion such as Ca2+, Ba2+, Mg+2, transition-metal-ion such as Zn2+, Al+3, Fe+2, Fe3, Mn+2, Co+2, Ag+, V+5, ammonium, tetraalkylammonium such as tetramethylammonium, tetraethylammonium, N,N-butyl-methyl-pyrrolidinium, imidazolium such as ethylmethylimidazolium, butylmethylimidazolium.

8. The method of any of the above claims, wherein the soft material contains one or more aprotic polar organic solvents belonging to the family of nitriles, dinitriles, methoxynitriles, carbonates, esters, dioxolanes, sulfoxides, sulfones, sultones, amides, pyrrolidones, oxazolidinones, imidazolidones, nitroalkyls, phosphoesters and ureas such as but not limited to: acetonitrile, proprionitrile, butyronitrile, glutaronitrile, 2-methyl glutaronitrile, adiponitrile, methoxyacetonitrile, methoxyproprionitrile, methyl 3-cyanopropionate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate, 2,3-butylene carbonate, t -butylene carbonate, pentylene carbonate, ethyl acetate, methyl acetate, y-butyrolactone, y-valerolactone, 5-valerolactone, cyrene, dimethyl sulfoxide, dimethyl sulfone, ethyl methyl sulfone, methyl isopropyl sulfone, ethyl isopropyl sulfone, ethyl isobutyl sulfone, isopropyl isobutyl sulfone, isopropyl sec-butyl sulfone, butyl isobutyl sulfone, sulfolane, 3-methyl sulfolane, 1,3-propanesultone, 1,4-butanesultone, N,N-dimethyl formamide, N N-dimethyl acetamide, N- methylpyrrolidone, N-methyl oxazolidinone, N,N-dimethyl imidazolidinone, nitromethane, nitroethane, trimethylphosphate, tetramethylurea.9 The method of any of the above claims, wherein the organic phase contains one or more aprotic apolar organic solvents belonging to the family of aliphatic, aromatic, ester, ether solvents, for example but not limited to: petroleum ether, such as with boiling ranges 40-60, 60-80, 80-100, n-hexane, n-heptane, n-octane, isooctane ciclohexane, methyl cyclohexane, benzene, toluene, xylene, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, 2-ethylhexyl acetate, methyl propionate, methyl butyrate, methyl valerate, methyl hexanoate, methyl nonanoate, methyl laurate, methyl myristeate, 2-ethylhexyl nonanoate, diethyl ether, methyl tert-butyl ether, cyclopentyl methyl ether, diphenyl ether.10 Use of salts and / or organic components received by a method of any of the above claims in an energy storage or conversion device.

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