Method for separation, segregation and recovery of constituent materials from electrochemical cells - Patents.com

Abstract

A method for separating and recovering multiple materials from an electrochemical cell by dissolution in multiple solvents, separation of the dissolved components, and recovery of the multiple materials.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 134,326, filed January 6, 2021, which is incorporated by reference in its entirety. Technical Field

[0002] Various embodiments described herein relate to the field of primary and secondary electrochemical cells, electrodes and electrode materials, electrolytes, electrolyte compositions, and methods of making, using and reprocessing the same. [Background technology]

[0003] The ever-increasing number and diversity of mobile devices, the evolution of hybrid / electric vehicles, and the growth of Internet-of-Things devices are driving the need for battery technologies with improved reliability, capacity (Ah), thermal properties, lifetime, and rechargeability. Currently, lithium solid-state battery technology offers potential improvements in safety, packaging efficiency, and enables novel high-energy chemistries. With the expanding use of solid-state battery technology, regeneration and recycling processes for the constituent materials are becoming increasingly important.

[0004] Due to the growing public demand for rechargeable batteries, the cost of battery raw materials such as lithium, nickel and cobalt continues to rise. One possible way to keep costs down is to recycle the materials contained in used batteries by carrying out acidic or alkaline digestion of these batteries, as described in U.S. Pat. No. 9,023,130 and Japanese Patent No. 5,577,926. This type of battery recycling only works safely for rechargeable batteries that contain liquid electrolytes, because the liquid electrolyte can be separated from the solid components of the battery, which provides access to the nickel- and cobalt-containing layers of the battery.

[0005] However, in solid-state batteries, especially those containing sulfide solid electrolytes, removal of the electrolyte material can be dangerous and more complicated. In solid-state batteries, the solid electrolyte material may be present in the form of a fine powder mixed with nickel and cobalt-containing materials. If the sulfide solid electrolyte material is not removed from the cathode layer before known recycling techniques are attempted, harmful H2S gas will be generated when the sulfide solid electrolyte material is exposed to water or acid. Summary of the Invention [Problem to be solved by the invention]

[0006] To further complicate things, in solid-state batteries, the negative electrode (anode), electrolyte, and positive electrode (cathode) layers are stacked together at high pressure, limiting direct access to the positive electrode active materials, including nickel and cobalt. Without direct access to the positive electrode layer, it is not safe to recycle sulfide solid-state batteries using currently known recycling techniques. In this disclosure, we describe a novel and safe recycling technique for used batteries that is compatible with sulfide solid-state batteries. The technique uses targeted solvents to gently disassemble the battery into its components for the recovery of multiple materials. [Means for solving the problem]

[0007] The present application relates to a method for separating and recovering multiple materials from an electrochemical cell, comprising: (a) adding a solvent to an electrochemical cell located within a vessel; (b) providing energy to the electrochemical cell and a solvent within the container to promote dissolution of the first plurality of materials in the electrochemical cell; (c) separating the solvent and the dissolved first plurality of materials from the remaining materials of the electrochemical cell; and (d) recovering the dissolved first material; wherein optionally (a), (b), (c) and (d) are repeated using one or more of the same or different solvents or mixtures thereof.

[0008] In one embodiment, the plurality of materials includes electrode metals, solid electrolytes, active materials, binders, conductive additives, and derivatives thereof.

[0009] In another embodiment, the plurality of materials includes lithium metal, a sulfide-based solid electrolyte, a positive electrode active material, a binder, a carbon-based additive, aluminum metal, and derivatives thereof.

[0010] In another embodiment, the method further comprises washing the remaining material of the electrochemical cell with an additional solvent to remove the remaining material.

[0011] In another embodiment, the method further comprises separation comprising density segregation.

[0012] In another embodiment, the method further comprises adding a complexing agent to the electrochemical cell and the solvent within the container.

[0013] In another embodiment, the complexing agent is selected from P2S5, elemental sulfur, P4S8, P4S9, Sb2S5, and mixtures thereof.

[0014] In another embodiment, the dissolved materials include a P2S5-Li2S complex.

[0015] In another embodiment, the solvent comprises a hydrocarbon solvent.

[0016] In another embodiment, the solvent comprises a xylene-based solvent.

[0017] In another embodiment, steps (a), (b), (c) and (d) are repeated using a polar solvent.

[0018] In another embodiment, steps (a), (b), (c) and (d) are repeated using a nitrile solvent.

[0019] In another embodiment, the nitrile solvent comprises acetonitrile, propionitrile, butyronitrile, isobutyronitrile, or a mixture thereof.

[0020] In another embodiment, the supply of energy comprises physically agitating the electrochemical cell and solvent within the vessel or applying heat to the electrochemical cell and solvent within the vessel.

[0021] In another embodiment, the present disclosure provides a method for recycling an electrochemical cell containing lithium metal, comprising: (a) immersing an electrochemical cell in one or more solvents, optionally with stirring or heat, whereby binder and / or polymeric components of the electrochemical cell are solubilized in the solvent; (b) removing the solvent along with the solubilized binder and / or polymeric components of the electrochemical cell; (c) adding a different solvent to the electrochemical cell and immersing the electrochemical cell, optionally with stirring or heat, whereby additional binder and / or polymer components of the solid electrolyte are solubilized in the different solvent to liberate lithium metal from the electrochemical cell and form a mixture having a lithium metal dispersion; (d) adding a complexing agent to the lithium metal dispersion to complex with the free lithium metal to form a precipitate; (e) filtering the precipitate to recover the lithium metal complex; and optionally wherein (a), (b), (c), (d) and / or (e) are repeated using one or more of the same or different solvents or mixtures thereof.

[0022] In another embodiment of the above recycling method, the (a) solvent comprises a hydrocarbon solvent.

[0023] In another embodiment of the above recycling method, the different solvent in (c) comprises a polar solvent or a nitrile solvent.

[0024] In another embodiment of the recycling method, the complexing agent in (d) is elemental sulfur, P4S3, P4S4, P4S5, P4S6, P4S7, P4S8, P4S9, P4S 10 (P2S5), Sb2S3, and Sb2S5, or mixtures thereof.

[0025] In another embodiment of the above recycling method, the hydrocarbon solvent comprises xylene, toluene, benzene, hexane, heptane, octane, isoparaffinic hydrocarbons, aprotic hydrocarbons, or mixtures thereof.

[0026] In another embodiment of the above recycling method, the different solvents include ethers, esters, nitriles, alcohols, thiols, ketones, or mixtures thereof.

[0027] The present disclosure will be understood by reference to the following detailed description in conjunction with the drawings, which are briefly described below. It should be noted that certain elements in the drawings may not be drawn to scale. [Brief description of the drawings]

[0028] [Figure 1] FIG. 1 is a simplified schematic diagram of the layer structure of an electrochemical cell containing a solid electrolyte.

[0029] [Diagram 2] FIG. 2 is a flow chart of a process for dissolving, separating, segregating, and recovering components of an electrochemical cell, including a solid electrolyte.

[0030] [Diagram 3] 3A-3D are a set of schematic pictorial diagrams illustrating various steps of the process of FIG.

[0031] [Figure 4] FIG. 4 is a photograph showing an example of material resulting from use of this method where the electrochemical cell was disassembled, the binder removed, an ethereal solvent added, and P2S5 added. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS In the following description, specific details are provided to provide a thorough understanding of various embodiments of the present invention. However, upon reading and understanding the specification, claims, and drawings, one skilled in the art will understand that some embodiments of the present invention may be practiced without following some of the specific details described herein. Moreover, in order to avoid obscuring the present invention, some well-known methods, processes, devices, and systems utilized in the various embodiments described herein are not disclosed in detail.

[0033] 1 is a simplified schematic diagram of a layer structure of an exemplary electrochemical cell 100 including a solid electrolyte. The cell 100 includes multiple layers, including, but not limited to, a negative electrode (anode) layer 110, an electrolyte layer 120, a positive electrode (cathode) layer 130, and a current collector layer 140. The negative electrode layer 110 may be formed from a foil of lithium metal or a lithium alloy, which may include one or more of metallic sodium (Na) or metallic potassium (K). In one embodiment, the lithium metal foil may include one or more of alkaline earth metals, such as magnesium (Mg) and calcium (Ca). In another embodiment, the lithium foil may include aluminum (Al), indium (In), silver (Ag), gold (Au), or zinc (Zn).

[0034] In a further embodiment, the lithium may be deposited on a metal foil that functions as a current collector generally similar to current collector layer 140, and the metal foil may include one or more of copper (Cu), aluminum (Al), nickel (Ni), titanium (Ti), stainless steel, magnesium (Mg), iron (Fe), zinc (Zn), indium (In), germanium (Ge), silver (Ag), platinum (Pt), or gold (Au). In one embodiment, the anode layer 110 is made of silicon (Si), tin (Sn), germanium (Ge), graphite, Li4Ti5O 12In some embodiments, anode layer 110 may further include one or more conductive carbon materials, such as carbon fiber, graphite, graphene, carbon black, conductive carbon, amorphous carbon, VGCF, and carbon nanotubes. In some embodiments, the anode layer 110 may further comprise one or more solid electrolytes, such as Li2S-P2S5, Li2S-P2S5-LiI, Li2S-P2S5-GeS2, Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-P2S5-LiI-LiBr, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-S-SiS2-LiCl, Li2S-S-SiS2-B2S3-LiI, Li2S-S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (where m and n are positive numbers, and Z is Ge, Zn, or Ga), Li2S-GeS2, Li2S-S-SiS2-Li3PO4, and Li2S-S-SiS2-Li x MO y (wherein x and y are positive numbers, and M is P, Si, Ge, B, Al, Ga, or In), etc.

[0035] In another embodiment, the solid electrolyte is Li3PS4, Li4P2S6, Li7P3S 11 , Li 10 GeP2S 12 , Li 10 SnP2S 12 In further embodiments, the solid electrolyte can be one or more of Li6PS5Cl, Li6PS5Br, Li6PS5I, or a compound of formula Li 7-y P.S. 6-y X y(Here, "X" represents at least one halogen element and / or pseudohalogen, 0 < y < 2.0, the halogen can be one or more of F, Cl, Br, I, and the pseudohalogen can be one or more of N, NH, NH2, NO, NO2, BF4, BH4, AlH4, CN, and SCN.) can be one or more of those represented thereby. In yet another embodiment, the solid electrolyte is of the formula Li 8-y-z P2S 9-y-z X y W z(Here, "X" and "W" represent at least one halogen element and / or pseudohalogen, where 0 < y < 1 and 0 < z < 1. ) is represented, and the halogen can be one or more of F, Cl, Br, and I, and the pseudohalogen can be one or more of N, NH, NH2, NO, NO2, BF4, BH4, AlH4, CN, and SCN. The negative electrode layer 110 may further contain one or more of binders or polymers such as fluororesins containing, for example, vinylidene fluoride (VdF), hexafluoropropylene (HFP), tetrafluoroethylene (TFE), and their derivatives as structural units. Specific examples thereof include homopolymers such as polyvinylidene fluoride (PVdF), polyhexafluoropropylene (PHFP), and polytetrafluoroethylene (PTFE), and binary copolymers such as copolymers of VdF and HFP such as poly(vinylidene fluoride - hexafluoropropylene) copolymer (PVdF - HFP). In another embodiment, the polymer or binder can be one or more of thermoplastic elastomers such as styrene - butadiene rubber (SBR), styrene - butadiene - styrene copolymer (SBS), styrene - isoprene block copolymer (SIS), styrene - ethylene - butylene - styrene (SEBS), polyacrylonitrile (PAN), nitrile - butadiene rubber (NBR), polybutadiene, polyisoprene, poly(meth)acrylate - nitrile - butadiene rubber (PMMA - NBR), etc. (however, not limited thereto). In a further embodiment, the polymer or binder can be one or more of acrylic resins such as poly(methyl (meth)acrylate), poly(ethyl (meth)acrylate), poly(isopropyl (meth)acrylate), poly(isobutyl (meth)acrylate), poly(butyl (meth)acrylate), etc. (however, not limited thereto). In yet another embodiment, the polymer or binder can be one or more of polycondensation polymers such as polyurea, polyamide paper, polyimide, polyester, etc. (however, not limited thereto).In yet another embodiment, the polymer or binder can be one or more nitrile rubbers, such as, but not limited to, acrylonitrile-butadiene rubber (ABR), polystyrene nitrile-butadiene rubber (PS-NBR), and mixtures thereof.

[0036] The electrolyte layer 120 may be one or more sulfur-based solid electrolytes, including one or more combinations of materials, such as Li2S-P2S5, Li2S-P2S5-LiI, Li2S-P2S5-GeS2, Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-P2S5-LiI-LiBr, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-S-SiS2-LiCl, Li2S-S-SiS2-B2S3-LiI, Li2S-S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (where m and n are positive numbers, and Z is Ge, Zn, or Ga), Li2S-GeS2, Li2S-S-SiS2-Li3PO4, and Li2S-S-SiS2-Li x MO y (wherein x and y are positive numbers, and M is P, Si, Ge, B, Al, Ga, or In.) In some embodiments, one or more of the solid electrolyte materials may include Li3PS4, Li4P2S6, Li7P3S 11 , Li 10 GeP2S 12 , Li 10 SnP2S 12 In one embodiment, one or more of the solid electrolyte materials can be Li6PS5Cl, Li6PS5Br, Li6PS5I, or a compound of the formula Li 7-y P.S. 6-y X y(Here, "X" represents at least one halogen element and / or pseudohalogen, 0 < y < 2.0, the halogen can be one or more of F, Cl, Br, I, and the pseudohalogen can be one or more of N, NH, NH2, NO, NO2, BF4, BH4, AlH4, CN, and SCN.) can be represented by. In another embodiment, one or more of the solid electrolyte materials are of the formula Li 8-y-z P2S 9-y-z X y W z(Here, "X" and "W" represent at least one halogen element and / or pseudohalogen, where 0 < y < 1 and 0 < z < 1. The halogen can be one or more of F, Cl, Br, and I, and the pseudohalogen can be one or more of N, NH, NH2, NO, NO2, BF4, BH4, AlH4, CN, and SCN.) can be represented by. The electrolyte layer 120 can further contain materials such as a binder and a polymer. The binder and the polymer can be one or more of fluororesins containing vinylidene fluoride (VdF), hexafluoropropylene (HFP), tetrafluoroethylene (TFE), and their derivatives as structural units, but are not limited thereto. Specific examples thereof include homopolymers such as polyvinylidene fluoride (PVdF), polyhexafluoropropylene (PHFP), and polytetrafluoroethylene (PTFE), and binary copolymers such as a copolymer of VdF and HFP, such as poly(vinylidene fluoride - hexafluoropropylene) copolymer (PVdF - HFP). In another embodiment, the polymer or binder can be one or more of thermoplastic elastomers such as styrene - butadiene rubber (SBR), styrene - butadiene - styrene copolymer (SBS), styrene - isoprene block copolymer (SIS), styrene - ethylene - butylene - styrene (SEBS), polyacrylonitrile (PAN), nitrile - butadiene rubber (NBR), polybutadiene, polyisoprene, poly(meth)acrylate nitrile - butadiene rubber (PMNIA - NBR), etc. (however, not limited thereto). In a further embodiment, the polymer or binder can be one or more of acrylic resins such as polymethyl(meth)acrylate, polyethyl(meth)acrylate, polyisopropyl(meth)acrylate, polyisobutyl(meth)acrylate, polybutyl(meth)acrylate, etc. (however, not limited thereto). In yet another embodiment, the polymer or binder can be one or more of polycondensation polymers such as polyurea, polyamide paper, polyimide, polyester, etc. (however, not limited thereto).In yet another embodiment, the polymer or binder can be one or more of nitrile rubbers, for example, acrylonitrile-butadiene rubber (ABR), polystyrene nitrile-butadiene rubber (PS-NBR), and mixtures thereof (but not limited thereto) can be used.

[0037] The positive electrode layer 130 can include a positive electrode active material, for example, Li(Ni a Co b Mn c )O2 (0 < a < 1, 0 < b < 1, 0 < c < 1, a + b + c = 1) which can be represented as nickel-manganese-cobalt (“NMC”), or, for example, NMC 111 (LiNi 0.33 Mn 0.33 Co 0.33 O2), NMC 433 (LiNi 0.4 Mn 0.3 Co 0.3 O2), NMC 532 (LiNi 0.5 Mn 0.3 Co 0.2 O2), NMC 622 (LiNi 0.6 Mn 0.2 Co 0.2 O2), NMC 811 (LiNi 0.8 Mn 0.1 Co 0.1 O2), or a combination thereof. In another embodiment, the positive electrode active material is a coated or uncoated metal oxide, for example, V2O5, V6O 13 , MoO3, LiCoO2, LiNiO2, LiMnO2, LiMn2O4, LiNi 1-y Co y O2, LiCo 1-y Mn y O2, LiNi 1-y Mn y O2 (0 < y < I), Li(Ni a Co b Mn c )O4 (0 < a < 2, 0 < b < 2, 0 < c < 2, a + b + c = 2), LiMn 2-z Ni z O4, LiMn 2-z Co zO4(0 < z < 2), LiCoPO4, LiFePO4, CuO, Li(Ni a Co b Al c )O2(0 < a < 1, 0 < b < 1, 0 < c < 1, a + b + c = 1), or one or more of combinations thereof (but not limited thereto). In yet another embodiment, the positive electrode active material may include a coated or uncoated sulfide, for example, titanium sulfide (TiS2), molybdenum sulfide (MoS2), iron sulfide (FeS, FeS2), copper sulfide (CuS), and nickel sulfide (Ni3S2), or one or more of combinations thereof (but not limited thereto). The positive electrode layer 130 may further include one or more conductive carbon materials, such as carbon fiber, graphite, graphene, carbon black, conductive carbon, amorphous carbon, VGCF, and carbon nanotubes. The positive electrode layer 130 may further include one or more solid electrolytes, and the solid electrolyte is a combination of one or more materials, for example, Li2S - P2S5, Li2S - P2S5 - LiI, Li2S - P2S5 - GeS2, Li2S - P2S5 - Li2O, Li2S - P2S5 - Li2O - LiI, Li2S - P2S5 - LiI - LiBr, Li2S - SiS2, Li2S - SiS2 - LiI, Li2S - SiS2 - LiBr, Li2S - S - SiS2 - LiCl, Li2S - S - SiS2 - B2S3 - LiI, Li2S - S - SiS2 - P2S5 - LiI, Li2S - B2S3, Li2S - P2S5 - Z m S n (where m and n are positive numbers, and Z is Ge, Zn, or Ga), Li2S - GeS2, Li2S - S - SiS2 - Li3PO4, and Li2S - S - SiS2 - Li x MO y (where x and y are positive numbers, and M is P, Si, Ge, B, Al, Ga, or In), etc. In another embodiment, the solid electrolyte is Li3PS4, Li4P2S6, Li7P3S 11 , Li 10 GeP2S 12 , Li 10 SnP2S 12One or more of them may be used. In a further embodiment, the solid electrolyte is Li6PS5Cl, Li6PS5Br, Li6PS5I, or of the formula Li 7-y PS 6-y X y (wherein "X" represents at least one halogen element and / or pseudohalogen, 0 < y < 2.0, the halogen can be one or more of F, Cl, Br, I, and the pseudohalogen can be one or more of N, NH, NH2, NO, NO2, BF4, BH4, AlH4, CN, and SCN). One or more of them can be used. In yet another embodiment, the solid electrolyte is of the formula Li 8-y-z P2S 9-y-z X y W z(Here, "X" and "W" represent at least one halogen element and / or pseudohalogen, where 0 < y < 1 and 0 < z < 1. ) is represented, and the halogen can be one or more of F, Cl, Br, and I, and the pseudohalogen can be one of N, NH, NH2, NO, NO2, BF4, BH4, AlH4, CN, and SCN. The positive electrode layer 130 may further contain one or more of a binder or polymer, for example, a fluororesin containing vinylidene fluoride (VdF), hexafluoropropylene (HFP), tetrafluoroethylene (TFE), and derivatives thereof as structural units. Specific examples thereof include homopolymers such as polyvinylidene fluoride (PVdF), polyhexafluoropropylene (PHFP), and polytetrafluoroethylene (PTFE), and binary copolymers such as a copolymer of VdF and HFP, such as poly(vinylidene fluoride - hexafluoropropylene) copolymer (PVdF - HFP). In another embodiment, the polymer or binder can be one or more of thermoplastic elastomers such as styrene - butadiene rubber (SBR), styrene - butadiene - styrene copolymer (SBS), styrene - isoprene block copolymer (SIS), styrene - ethylene - butylene - styrene (SEBS), polyacrylonitrile (PAN), nitrile - butadiene rubber (NBR), polybutadiene, polyisoprene, poly(meth)acrylate nitrile - butadiene rubber (PMMA - NBR), etc. (however, not limited thereto). In a further embodiment, the polymer or binder can be one or more of acrylic resins such as polymethyl(meth)acrylate, polyethyl(meth)acrylate, polyisopropyl(meth)acrylate, polyisobutyl(meth)acrylate, polybutyl(meth)acrylate, etc. (however, not limited thereto). In yet another embodiment, the polymer or binder can be one or more of polycondensation polymers such as polyurea, polyamide paper, polyimide, polyester, etc. (however, not limited thereto).In yet another embodiment, the polymer or binder can be one or more nitrile rubbers, such as, but not limited to, acrylonitrile-butadiene rubber (ABR), polystyrene nitrile-butadiene rubber (PS-NBR), and mixtures thereof.

[0038] The current collector layer 140 can include one or more of aluminum (Al), nickel (Ni), titanium (Ti), stainless steel, magnesium (Mg), iron (Fe), zinc (Zn), indium (In), germanium (Ge), silver (Ag), platinum (Pt), and gold (Au).

[0039] FIG. 2 is a process flow diagram for dissolving, separating, segregating, and recovering the constituent materials of an electrochemical cell, including a solid electrolyte. Process 200 begins with a preparation step 210, which may include discharging or discharging the cell, cleaning or rinsing the surfaces of the cell's enclosure, e.g., pouch, or dismantling or removing the cell's enclosure. Optional equipment preparation may also be performed. Process 200 is preferably performed under inert conditions, such as a dry nitrogen or argon atmosphere, to minimize chemical interactions with the outside world. Additionally, when using certain materials and solvents, high humidity conditions and high oxygen levels may affect or impede process 200.

[0040] After the initial preparation, the process 200 proceeds to step 220, where an electrochemical cell, such as cell 100 of Figure 1, is combined with a first solvent. The first solvent can be one or more hydrocarbon solvents, such as xylene, toluene, benzene, hexane, heptane, octane, isoparaffinic hydrocarbons, aprotic hydrocarbons, or blends of any of the foregoing. The first solvent should be selected such that the binders and polymers included in the layers of the electrochemical cell are soluble in the first solvent.

[0041] The temperature of the cell and the first solvent can be in the range of -120°C to 450°C, and more typically, the temperature can be in the range of above the freezing point of the solvent used to above the boiling point of the solvent used. When a temperature above the boiling point of the solvent is used, the system in which the process is taking place may be sealed and pressurized. The entire cell may be placed in the solvent to reduce degradation of the various components of the cell being processed. Alternatively, the cell may be at least partially disassembled or fragmented to facilitate processing. In another embodiment, a cell sealed in a pouch or other container may be opened or removed before combining with the first solvent. The volume ratio of the first solvent to the cell is not critical, but should be sufficient to support the desired dissolution. Generally, the first solvent is selected to dissolve the binders and polymers in the cell, such as in the anode layer 110, the electrolyte layer 120, and the cathode layer 130. The dissolution of these binders and polymers separates the laminated layers of the cell and disperses the individual particles contained in each layer.

[0042] In step 230, energy is applied to the solvent and cells to promote dissolution. Energy can be applied thermally by applying heat or radiation, or mechanically by stirring, tumbling, grinding, mixing, or otherwise agitating. After proper dissolution, the dissolved material and solvent can be separated from the remaining solid material during step 240. The dissolved polymer and binder can be removed in solution with the solvent by various means, including but not limited to, one or more of filtration, centrifugation, or decanting. The solid material remaining after separation of the dissolved components may be further washed with fresh solvent to further remove dissolved materials such as polymer and binder. The solvent used for washing can also be removed by one or more of filtration, centrifugation, and decanting.

[0043] In another embodiment, a solvent can be used that is capable of dissolving the binder and polymer used, but is also inert to other components of the electrochemical cell. Such a solvent allows the polymer and binder to be dissolved and separated from the different layers without adversely reacting with other materials of the cell. A solvent with these properties can be one or more of toluene, xylene, benzene, heptane, or octane. In contrast, the use of one or more solvents that can dissolve the binder, but are reactive with other components of the electrochemical cell, can lead to irreversible degradation of the valuables contained in the electrochemical cell. Solvents such as acetone or water can dissolve the binder and polymer, but can react with the lithium metal anode and solid electrolyte materials, producing undesirable or harmful by-products such as hydrogen or H2S gas.

[0044] The use of a first solvent to dissolve the binder and polymer gently breaks down the layers in the cell without the need for mechanical force, as in shredding, cutting or grinding the cell. This avoids detrimental interactions between the lithium metal and the metal shredded or ground components, and avoids the disintegration of the soft lithium metal. Furthermore, by avoiding one or more shredding or grinding processes, the existing particle size is suitable for reclamation, and the structural integrity of the NMC particles and other components that may be reduced under additional mechanical stress that would complicate reuse is preserved.

[0045] In step 250, the remaining solid material is combined with a second solvent. In some embodiments, the second solvent can be an ether, such as one or more of tetrahydrofuran ("THF"), diethyl ether, dibutyl ether, and dioxane. In another embodiment, the second solvent can be an ester, such as one or more of methyl acetate, ethyl acetate, propyl acetate, and amyl acetate. In yet another embodiment, the second solvent can be a nitrile, such as one or more of acetonitrile, propionitrile, butyronitrile, isobutyronitrile, pyridine, and pyrrolidine. In a further embodiment, the second solvent can be an alcohol, such as one or more of methanol, ethanol, propanol, isopropyl alcohol, or tert-butyl alcohol. In another embodiment, the second solvent can be one or more of a thiol or a ketone, and may include other polar solvents.

[0046] The temperature of the material and second solvent can be in the range of -120°C to 450°C, or more commonly in the range of from above the freezing point of the solvent used to above the boiling point of the solvent used. If a temperature above the boiling point of the solvent is used, the system in which the process is taking place may be sealed and pressurized. The ratio of the volume of the solvent to the volume of the material is not critical, but should be sufficient to support the desired dissolution. During step 260, energy can be applied to the solvent and material to promote dissolution. Energy can be applied thermally, by applying heat or radiation, or mechanically, by stirring, mixing, or otherwise agitating.

[0047] Combining a second solvent, such as THF, with the remaining solid material facilitates dissolution and particle size reduction of the electrolyte material typically included in one or more layers of the cell, such as both the electrolyte layer 120 and the cathode layer 130 of FIG. 1. For example, THF facilitates separation of the lithium metal layer 110 and the solid electrolyte layer 120, which may be strongly attached together. Additionally, THF can form THF-lithium complexes at the surface of the lithium metal, protecting the lithium metal from the surrounding environment (e.g., exposure to air and moisture) that may generate large amounts of heat or even ignite the solvent in which the lithium metal is contained.

[0048] To provide further useful reactions, additional compounds may be added, such as elemental sulfur, P4S3, P4S4, P4S5, P4S6, P4S7, P4S8, P4S9, P4S 10 One or more of (P2S5), Sb2S3, and Sb2S5 may be added to the solution as a complexing agent. The complexing agent may be added in an amount of 0.1% to 200% of the total mass of the solid electrolyte material contained in the electrochemical cell. In some embodiments, the complexing agent may be 10% to 150% of the total mass of the solid electrolyte material contained in the electrochemical cell. In other embodiments, the complexing agent may be 40% to 130% of the total mass of the solid electrolyte material contained in the electrochemical cell. In further embodiments, the complexing agent may be 50% to 120% of the total mass of the solid electrolyte material contained in the electrochemical cell. For example, P2S5, when present in THF, can react with the remaining solid electrolyte material and aid in dissolution by the following reaction: Response 1: [ka]

[0049] This reaction at least partially decomposes the electrolyte material to form a (P2S5-Li2S) complex that is soluble in THF. The (P2S5-Li2S) complex may be one or more of the Li2P2S6 or LiPS3 compounds. Additionally, LiBr, which is commonly used in solid electrolytes, is soluble in THF and dissolves to form a solution of (P2S5-Li2S) in THF.

[0050] The solids remaining in solution may include Li3PS4 or similar materials and Li2S. The additional P2S5 assists in further decomposition and dissolution of these remaining solids by the following reaction: Response 2: [ka] Reaction 3: [ka]

[0051] By adding sufficient P2S5 to a THF-based solution in combination with an electrolyte material such as Li6PS5Br, the solid electrolyte material can be converted into one or more materials that are sufficiently soluble, for example, as shown in Reaction 4 below. Reaction 4: [ka]

[0052] Specifically, in reaction 2, P2S5 is added in an amount of 123% of the total mass of the solid electrolyte material Li3PS4. In reaction 4, P2S5 is added in an amount of 142% of the total mass of the solid electrolyte material Li6PS5Br. When all the electrolyte materials are dissolved in the reaction solvent, the (P2S5-Li2S) complex may separate into two or more parts with different densities, which aids in segregation of the disparate components of the cell based on density. The densest layer (settled toward the bottom of the solution) may include the metal components of the current collector layer (e.g., current collector layer 140 in FIG. 1) and the active material of the positive electrode layer 130, such as NMC particles. In some embodiments, the densest layer may also include the negative electrode active material from the negative electrode layer 110, where the negative electrode active material can be, but is not limited to, one or more of a silicon-containing material, a graphite-containing material, or a tin-containing material, the densest (P2S5-Li2S) complex. The intermediate density layer (settled above the previous layers) may include components such as carbon-based additives (carbon, graphite, vapor grown carbon fiber ("VGCF")) and less dense (P2S5-Li2S) complexes. The lowest density layer (floating near the top of the solution) may be a low density material such as lithium metal.

[0053] Following proper dissolution, during step 270, the dissolved materials and solvent can be separated from the remaining solid materials with the aid of filtration or centrifugation. The solid materials remaining after separation can be further washed with fresh solvent to further remove dissolved materials. The lowest density component, for example lithium metal, can be skimmed from the top of the solution and collected for reprocessing. The intermediate density (P2S5-Li2S) complexes with carbon-based additives can then be isolated. The carbon-based additives can be filtered from the isolated portion of the solution, washed, stored, and reused. The highest density (P2S5-Li2S) complexes, which may contain NMC, and the current collector material can then be passed through a filter small enough to remove the current collector material but large enough to pass the NMC material. The resulting NMC material-containing mixture can be passed through a filter again to isolate the NMC material, which can then be washed, stored, and reprocessed.

[0054] The recovered lithium may be, for example, recycled, reprocessed into lithium foil, or converted into lithium precursors such as Li2S or Li3N. The process 200 ends at step 280.

[0055] In an alternative process where the order of action of the first and second solvents is reversed, xylene or other suitable first solvent may be applied last to dissolve the polymer and / or binder material. After appropriate removal of the lithium foil and dissolution of the solid electrolyte, the remaining materials include the carbon-based additive, NMC, current collector, and binder. Addition of xylene then dissolves the binder, allowing separation of the various components. In a further alternative, the binder may remain in the final NMC / carbon composite, and an acid may be used to dissolve the NMC. In this further alternative, the NMC may be filtered from the binder and carbon. The binder and carbon mixture may then be heated in an inert environment, whereupon the binder may be carbonized.

[0056] In other cell structures where the anode material is not lithium, but e.g. silicon or graphite, a solvent such as propanol can be used to dissolve the electrolyte material instead of using THF. Dissolving a solid electrolyte in propanol may not cause separation due to density differences as strongly as THF. As a result, the difficulty of separating the carbon-based additive from the NMC and anode active material increases. To overcome this challenge, a high density solvent may be added so that the carbon-based additive floats and the denser NMC and other metal components settle to the bottom of the solution.

[0057] To vary the presence of the (P2S5-Li2S) complex in THF used to separate materials by density difference, another process step may be used. The (P2S5-Li2S) complex in THF can be removed from the process and a high-density solvent, such as a fluorinated hydrocarbon (e.g., hexafluorobenzene and perfluorodecalin), etc., can be added to separate the carbon-based additive from NMC. Further, elemental sulfur can be used with or instead of P2S5 to assist in dissolving and removing the solid electrolyte or to adjust the density of the (P2S5-Li2S) complex in THF. Li2S and elemental sulfur in THF form lithium polysulfides (Li2S x , 1 < X ≦ 8). Similar to P2S5 or lithium polysulfides forming additional density regions in solution, the addition of sulfur can cause decomposition of the solid electrolyte. Further adjustment of P2S5 may be carried out to fully dissolve the solid electrolyte in the solution.

[0058] 3A-3D are a set of schematic pictorial diagrams illustrating various steps of the process of FIG. 2. FIG. 3A shows process step 220 where the monolithic cell is combined with a first solvent, and FIG. 3B shows process step 230 where the various components of the cell are decomposed to form a heterogeneous solution of liquid and solid components, e.g., a heterogeneous solution of fully dissolved binder and solid particles of solid electrolyte, cathode active material, and carbon-based additive. FIG. 3C shows the combination of the various solid components remaining after the process step associated with FIG. 3B with a second solvent. FIG. 3D shows the separation and density segregation of further dissolved components of the original cell. In this example, three density partitions are shown, but it should be understood that more or less partitions may occur depending on the original structure and composition of the processed cell. The partitions shown in FIG. 3D can be associated, for example, with an electrochemical cell having a lithium metal anode, a sulfide-based solid electrolyte, an NMC-based cathode, and an aluminum current collector being processed according to process 200. The lowest density layer, indicated by the segregated open circles, can be associated with, for example, lithium metal originating from the anode, such as that of Figure 1. The intermediate density layers, indicated by the partially filled circles, can be associated with, for example, (P2S5-Li2S) complexes and various carbon-based additives resulting from the action of reactive solvents on the solid electrolyte from materials originating from layers such as layer 120 of Figure 1. The highest density layers, indicated by the filled circles, can be associated with, for example, (P2S5-Li2S) complexes, NMC materials, and metals resulting from the action of reactive solvents on the solid electrolyte from materials originating from layers such as layers 130 and 140 of Figure 1. EXAMPLES

[0059] Construction of the positive electrode layer

[0060] The cathode layer was constructed using NMC cathode active material, Li2S-P2S5-containing solid electrolyte, carbon-based conductive additive, and polymer. These components were mixed in a solvent capable of dissolving the polymer to form a cathode composite, which was then placed on an aluminum foil current collector. The cathode composite layer was dried and compressed to form a compact cathode layer.

[0061] Construction of solid electrolyte layer

[0062] The solid electrolyte layer was constructed by mixing the Li2S-P2S5-containing solid electrolyte with a polymer in a solvent that the polymer can dissolve in. The mixture was applied to a support and the solvent was removed. The layer was compressed to form a compact solid electrolyte layer.

[0063] Construction of an electrochemical cell

[0064] An electrochemical cell was constructed containing a lithium metal foil anode layer, a solid electrolyte layer, and a cathode layer by removing the support material from the solid electrolyte layer and placing one side of the solid electrolyte layer on the surface of the cathode layer opposite the current collector layer. A layer of lithium metal foil was then placed on the solid electrolyte layer opposite the cathode layer. The stack was then laminated to ensure uniform contact between all layers.

[0065] Disassembly of electrochemical cells

[0066] The electrochemical cells were then cut into strips 0.25 inches (6.35 mm) wide. These strips were then placed into 32 ounce (946 ml) glass jars.

[0067] Polymer Removal

[0068] Sixteen ounces (473 ml) of xylene was added to the glass jar containing the electrochemical cell strips. The glass jar containing the electrochemical cell strips was then shaken by hand for two minutes. Within two minutes, the xylene-soluble polymer dissolved and the layers in the strips began to separate. As the polymer continued to dissolve, the individual particles contained in the cathode and solid electrolyte layers dispersed in the xylene. The xylene containing the polymer was then removed by filtering through a metal mesh whose pores were small enough to capture the smallest of the newly liberated particles. The solids were then returned to the 32 ounce (946 ml) jar and 16 ounces of xylene was added again. The jar was then shaken for one minute to ensure that all of the binder was dissolved. The xylene containing the polymer was filtered through a metal mesh whose pores were small enough to capture the smallest of the newly liberated particles.

[0069] Removal of lithium metal anode active material

[0070] The contents of the 32 oz bottle were then transferred to a 50 ml glass vial. 25 ml of tetrahydrofuran (THF) was added to the 50 ml vial containing the remaining materials. The 50 ml vial containing this mixture was shaken by hand for 2 minutes. During this time, the solid electrolyte contained in the cathode layer and the solid electrolyte layer began to decompose and dissolve in the THF to form (Li2S-P2S5) complexes. This dissolution process breaks the interface between the solid electrolyte layer and the lithium foil layer, freeing the two layers from each other. The mixture was then allowed to settle, allowing lithium metal, the least dense of all the materials, to float to the top. An amount of P2S5 equivalent to 125% of the total mass of the solid electrolyte materials used in the electrochemical cell was added to the THF mixture in the 50 ml vial. The vial containing all the materials was then shaken by hand for 30 minutes. During this time, the P2S5 further decomposed the solid electrolyte to form more (Li2S-P2S5) complexes in the THF. After 30 minutes, the mixture was allowed to settle, allowing the remaining lithium metal to float to the top of the THF mixture, as shown in FIG. 4. The 50 ml vial containing all the remaining material 400 shows that multiple layers of different densities were formed. At the top is the lowest density layer 410, which contains lithium metal. Below that is the first intermediate layer 420, which contains the lowest density (Li2S-P2S5) complex and the lowest density particles of the carbon-based additive material. Then there is the second intermediate layer 430, which contains the higher density (Li2S-P2S5) complex and most of the conductive additive. At the bottom is the highest density layer 440, which contains the NMC active cathode material, the aluminum current collector, and the heaviest portion of the (Li2S-P2S5) complex. Once all the lithium had risen to the top, a portion of the lowest density layer, which contains lithium metal, was removed by passing it through a metal mesh that was small enough to capture the lithium, but large enough to allow other smaller particulates to easily pass through the mesh. The lithium pieces were then washed with THF to remove any residual (Li2S-P2S5) complex.

[0071] Removal of conductive additives

[0072] The first intermediate density layer 420, containing the lightest conductive additive particles, and the second intermediate layer 430, containing the remaining conductive additive, were decanted from the 50 ml glass vial using a pipette. The decanted layers were then passed through a filter with a pore size small enough to capture the conductive additive particles. The filtered (Li2S-P2S5) complex in THF was returned to the 50 ml vial and the conductive additive was washed with 20 ml of THF to remove the remaining (Li2S-P2S5) complex.

[0073] Removal of the current collector layer

[0074] The remaining contents of the vial were passed through a coarse metal mesh to remove the strip of current collector layer, which was washed with THF and the material that passed through the metal mesh filter was returned to the 50 ml vial.

[0075] Removal of positive electrode active material

[0076] The remaining contents of the vial were passed through a fine mesh filter with pores small enough to capture the NMC active cathode material. After filtering the NMC active cathode material from the THF solution, the NMC active cathode material was washed with 20 ml of THF to remove any remaining (Li2S-P2S5) complex. The THF solution was returned to the 50 ml vial. The remaining contents of this vial were only the (Li2S-P2S5) complex in THF.

[0077] Summary of Results

[0078] As shown by the contents of the 50 ml glass vial 400 in FIG. 4, it is possible to separate the multiple components contained in the stacked electrochemical cell by using a specific solvent, such as xylene, to remove the binder or polymer contained in the individual layers. A specific solvent, such as THF, is then used to decompose the portion of the solid electrolyte contained in the positive electrode layer, the solid electrolyte layer, and, in some applications, the negative electrode layer. Once the binder, polymer, and solid electrolyte materials have been completely or partially removed from the individual layers of the electrochemical cell, the remaining materials are decomposed into their respective powders or foils. When a complexing agent, such as elemental sulfur or P2S5, is added to the mixture of the electrochemical cell components and THF, the complexing agent can further decompose the solid electrolyte and form multiple separate liquid layers with densities that can be adjusted to separate the various materials contained in the electrochemical cell. Once separated, the layers can be easily removed by decanting and filtering.

[0079] The features described above and in the following claims may be combined in various ways without departing from the scope of the present specification. It should therefore be noted that the matters contained in the above description or shown in the accompanying drawings should be interpreted as illustrative and not limiting. The above-described embodiments should not be considered as limiting the scope of the present invention, but as examples of the present invention. In addition to the above-described embodiments of the invention, other embodiments of such invention will be found to exist upon review of the detailed description and the accompanying drawings. Thus, many combinations, changes, variations and modifications of the embodiments of the invention described above that are not expressly set forth in this disclosure are nonetheless within the scope of such invention. The following claims are intended to cover the general and specific features described in this disclosure, as well as all statements regarding the scope of the present method and system that may be said to fall therebetween as a matter of language.

Claims

1. 1. A method for separating and recovering materials from an electrochemical cell, comprising: (a) adding a solvent to the electrochemical cell located within a vessel; (b) providing energy to the electrochemical cell and the solvent within the vessel to promote dissolution of a first plurality of materials in the electrochemical cell; (c) separating the solvent and dissolved first plurality of materials from the remaining materials of the electrochemical cell; and (d) recovering the dissolved first plurality of materials; and optionally (a), (b), (c) and (d) are repeated using one or more of the same or different solvents or mixtures thereof.

2. The method of claim 1 , wherein the plurality of materials includes an electrode metal, a solid electrolyte, an active material, a binder, a conductive additive, and derivatives thereof.

3. 2. The method of claim 1, wherein the plurality of materials includes lithium metal, a sulfide-based solid electrolyte, a positive electrode active material, a binder, a carbon-based additive, aluminum metal, and derivatives thereof.

4. 10. The method of claim 1, further comprising washing the remaining material of the electrochemical cell with an additional solvent to remove said remaining material.

5. The method of claim 1 , wherein the separating step comprises density segregation.

6. The method of claim 1 , further comprising adding a complexing agent to the electrochemical cell and to the solvent within the vessel.

7. The complexing agent is P ２ S ５ , elemental sulfur, P ４ S ８ , P ４ S ９ , Sb ２ S ５ and mixtures thereof.

8. One of the dissolved materials is P ２ S ５ -Li ２ The method of claim 1 comprising an S complex.

9. The method of claim 1 , wherein the solvent comprises a hydrocarbon solvent.

10. The method of claim 1 , wherein the solvent comprises a xylene-based solvent.

11. 10. The method of claim 1, wherein steps (a), (b), (c) and (d) are repeated using a polar solvent.

12. 10. The method of claim 1, wherein steps (a), (b), (c) and (d) are repeated using a nitrile solvent.

13. 13. The method of claim 12, wherein the nitrile solvent comprises acetonitrile, propionitrile, butyronitrile, isobutyronitrile or a mixture thereof.

14. 10. The method of claim 1, wherein providing energy comprises physically agitating the electrochemical cell and the solvent in the vessel or applying heat to the electrochemical cell and the solvent in the vessel.

15. 1. A method for recycling an electrochemical cell containing lithium metal, comprising: (a) immersing the electrochemical cell in one or more solvents, optionally with agitation or heat, to solubilize binder and / or polymeric components of the electrochemical cell in the solvent; (b) removing the solvent along with the solubilized binder and / or polymeric components of the electrochemical cell; (c) adding a different solvent to the electrochemical cell and immersing the electrochemical cell, optionally with stirring or heat, to solubilize additional binder and / or polymer components of the solid electrolyte in the different solvent and liberate the lithium metal in the electrochemical cell to form a mixture having a lithium metal dispersion; (d) adding a complexing agent to the lithium metal dispersion to form a complex with the liberated lithium metal to form a precipitate; (e) filtering the precipitate to recover the lithium metal complex; and optionally (a), (b), (c), (d) and / or (e) are repeated using one or more of the same or different solvents or mixtures thereof.

16. 16. The method of claim 15, wherein the solvent in (a) comprises a hydrocarbon solvent.

17. 16. The method of claim 15, wherein the different solvent in (c) comprises a polar solvent or a nitrile solvent.

18. (d) The complexing agent is elemental sulfur, P ４ S ３ , P ４ S ４ , P ４ S ５ , P ４ S ６ , P ４ S ７ , P ４ S ８ , P ４ S ９ , P ４ S １０ (P ２ S ５ ), Sb ２ S ３ and Sb ２ S ５ or a mixture thereof.

19. 17. The method of claim 16, wherein the hydrocarbon solvent comprises xylene, toluene, benzene, hexane, heptane, octane, isoparaffinic hydrocarbons, aprotic hydrocarbons, or mixtures thereof.

20. 18. The method of claim 17, wherein the different solvents comprise ethers, esters, nitriles, alcohols, thiols, ketones, or mixtures thereof.

21. The method of claim 1, further comprising removing the container from the electrochemical cell prior to adding the solvent to the electrochemical cell.

22. The method of claim 15, further comprising removing a container from the electrochemical cell prior to immersing the electrochemical cell in one or more solvents.

23. The method of claim 1, further comprising at least one of disassembling or fragmenting the electrochemical cell prior to adding the solvent to the electrochemical cell located within the container.

24. The method of claim 15, further comprising at least one of disassembling or fragmenting the electrochemical cell prior to immersing the electrochemical cell in one or more solvents.

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