Recycling and anode recovery of all-solid-state batteries (ASSB)

Abstract

1. A method for recirculating all solid-state batteries (ASSBs), the method comprising: receiving a recirculation stream of the ASSBs including an electrolyte mixed with at least one charge material; introducing a passivation material to neutralize undesired reactions or discharge of the charge material from cells defining the recirculation stream; agitating the cells in the recirculation stream in the presence of the passivation material to liberate the charge material and electrolyte stored therein; and recovering the charge material and electrolyte from the agitated cells, wherein the passivation material combines with the agitated cells to produce useful products, thereby recirculating the ASSBs.

Description

[Technical Field]

[0001] Related Applications This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 215,410, filed June 25, 2021, entitled "Recycling all solid-state batteries (ASSBS)," by inventors Eric Gratz and Yan Wang, the contents of which are incorporated herein by reference in their entirety. [Background technology]

[0002] background All-solid-state batteries (ASSBs) are expected to represent a growing industry alternative to lithium-ion batteries (LIBs). However, the recycling aspect of ASSBs is underexplored, and supply / demand forecasting is critical as they will ultimately result in ever-increasing amounts of discarded LIBs, particularly from the automotive sector. The current state of LIB recycling is insufficient, and the introduction of lithium-metal anode and solid-state electrolyte chemistry in ASSBs poses yet another challenge. Therefore, the viability of recycling and waste treatment should play a leading role in the development of ASSBs toward commercialization. Summary of the Invention [Problem to be solved by the invention]

[0003] Therefore, there is a need for new methods for safely disposing of ASSB, treating the waste, recovering critical materials needed for ASSB, and recycling ASSB in a cost-effective and economically viable manner for the sustainable use of resources.

[0004] overview Since their commercialization in the early 1990s, lithium-ion batteries (LIBs) have become an integral part of society. The electrochemical activity of lithium, combined with its low atomic mass and size, allows for significant energy and power density advantages compared to other comparable battery chemistries. Seeking better electrochemical performance, lifetime, and safety for more demanding applications, a significant portion of future LIBs is expected to be composed of all-solid-state batteries (ASSBs). ASSBs contain solid-state electrolytes (SSEs) rather than traditional non-aqueous liquid electrolytes. ASSBs demonstrate significant advantages over current LIBs: the mechanical integrity of SSEs can hinder dendritic growth to varying degrees, enabling the feasibility of energy-dense lithium metal anodes. SSE chemistries generally offer superior thermal and electrochemical stability compared to LIBs with non-aqueous electrolytes, enabling a wider voltage range. Therefore, SSEs offer increased cell energy density and increased battery pack-specific volumetric energy density by reducing the required amount of thermal management and cell support / enclosure infrastructure at the battery pack level, which can account for as much as 20% of the cost of electric vehicle (EV) battery packs.

[0005] LIBs are widely used for portable electronics and continue to be used in conjunction with alternative energy generation to develop new applications such as electric vehicles, e-bikes, and grid storage. The addition of these new markets, along with the continued growth of existing markets, is expected to exponentially increase the demand for lithium and other materials critical to LIB manufacturing. Along with the challenge of how industry can handle the necessary manufacturing, there is also the potential for increased waste when LIBs reach their end-of-life cycle and are discarded. The current situation is unsustainable due to limited natural supplies of key materials such as lithium and cobalt, and current end-of-life treatments lack an economically viable large-scale recycling system for discarded LIBs. Recently adopted LIB recycling methods typically focus on material recovery of metals in the cathode, with varying degrees of efficiency and significant irrecoverable losses of electrolyte and lithium. With the required improvements in recovery rates, these processes are not yet economically viable and may generate significant amounts of waste or greenhouse gas emissions. The lack of future prospects for recycling, both in terms of infrastructure and legislation, has led to only about 5% of potential LIBs being recycled in the USA. This is in stark contrast to lead-acid batteries, which are currently recycled and recovered at much higher rates—almost 99%. Therefore, developing an economically viable and efficient system for recycling next-generation LIBs is an urgent priority. Because ASSBs are still in development and not yet mass-produced, there is a significant opportunity to proactively plan and develop recycling processes for sustainable systems. [Means for solving the problem]

[0006] Embodiments of the invention described herein provide a method for recycling all-solid-state batteries (ASSBs), the method comprising receiving a recycle stream of the ASSBs including an electrolyte mixed with at least one charge material; introducing a passivation material to neutralize undesired reaction or discharge of the charge material from the cells defining the recycle stream; agitating the cells in the recycle stream in the presence of the passivation material to liberate the charge material and electrolyte stored therein; and recovering the charge material and electrolyte from the agitated cells, wherein the passivation material combines with the agitated cells to produce useful products, thereby recycling the ASSBs.

[0007] In a method embodiment, the battery includes a metal-based anode, a cathode, and a solid-state electrolyte (SSE). In a method embodiment, the metal anode is reactive in a non-inert environment. In a method embodiment, the passivating material mitigates detrimental reactions with the metal anode and participates in beneficial reactions to produce beneficial products. In a method embodiment, the solid-state electrolyte is lithium metal.

[0008]

[0010] Method embodiments further include sorting the ASSB recycle stream based on the type of solid electrolyte prior to introduction. In method embodiments, the passivation material is at least one selected from a reducing gas and an inert gas. In method embodiments, the reducing gas is at least one selected from carbon dioxide, air, nitrogen, and hydrogen sulfide. In method embodiments, the inert gas contains at least one of helium, argon, neon, xenon, krypton, and radon.

[0009] In method embodiments, the passivation material contains air and argon. In method embodiments, the percentage of reducing gas in the passivation material is at least 99%, or at least 95%, or at least 90%, or at least 85%, or at least 80%, or at least 75%, or at least 70%. In method embodiments, the percentage of inert gas in the passivation material is at least 1%, or at least 5%, or at least 10%, or at least 15%, or at least 20%, or at least 25%, or at least 30%.

[0010] The method embodiment further includes sieving the charged material and the beneficial product after stirring. The method embodiment further includes washing the beneficial product with water after sieving to dissolve the beneficial product and purify the beneficial product. In the method embodiment, the ASSB is in at least one form selected from a stack, a bag, a folded pouch, and a cylindrical roll. In the method embodiment, the resulting beneficial product is at least one selected from a lithium carbonate precursor, lithium nitride, lithium hydroxide, lithium carbonate, lithium oxalate, hydrogen, and lithium sulfide.

[0011] In method embodiments, the cells in the recycle stream have an NMC (nickel, manganese, cobalt)-based chemistry for the cathode material. Method embodiments further include drilling the ASSB and injecting a passivation material prior to agitation. In method embodiments, agitation further includes at least one of chopping, hammering, and pulverizing. Method embodiments further include separating the NMC and current collector by at least one method selected from eddy current and froth flotation. [Brief explanation of the drawings]

[0012] BRIEF DESCRIPTION OF THE DRAWINGS [Figure 1A]Figure 1A is a series of schematic diagrams illustrating the structure of conventional batteries and ASSBs. Figure 1A is a schematic diagram showing the structure of a conventional liquid electrolyte LIB containing a porous graphite or silicon anode composite, a liquid electrolyte and a porous separator layer, and a porous cathode composite. [Figure 1B]

[0023] Figure 1B is a series of schematic diagrams illustrating the structure of a conventional battery and an ASSB: Figure 1B is a schematic diagram showing the structure of an ASSB with a dense graphite and Li metal anode, a dense solid electrolyte layer, and a dense cathode and electrolyte composite; [Figure 2A] A series of diagrams illustrating different recycling methods, the processes required, and the challenges associated with each process for applying those steps to ASSB. Figure 2A is a diagram showing the steps of a mechanical separation method. [Figure 2B]

[0023] Figure 2B is a series of diagrams illustrating different recycling methods, the processes required, and the challenges associated with each process for applying those steps for ASSB. Figure 2B is a diagram showing the steps of a pyrometallurgical process. [Figure 2C]

[0023] Figure 2C is a series of diagrams illustrating different recycling methods, the processes required, and the challenges associated with each process for applying those steps for ASSB. Figure 2C is a diagram showing the steps of a hydrometallurgical process. [Figure 2D] A series of diagrams illustrating different recycle methods, the processes required, and the challenges associated with each process for applying those steps to ASSB. Figure 2D is a diagram showing the steps for the direct recycle method with hydrothermal recycle. [Figure 2E] A series of diagrams illustrating different recycling methods, the processes required, and the challenges associated with each step in applying those steps for ASSB. Figure 2E is a diagram showing the steps for the direct recycling method by dissolution or precipitation. [Figure 3] 1 is a process flow diagram of an ASSB recycle system utilizing hydrometallurgy and direct recycle methods. DETAILED DESCRIPTION OF THE INVENTION

[0013] Detailed Description of the Invention The methods and method embodiments described herein demonstrate a novel direct recycling process for recycling ASSBs. Recently introduced recycling processes for conventional LIBs are discussed with respect to their feasibility for different ASSB systems. The recycling process for all-solid-state batteries (ASSBs) receives the recycling stream of batteries having a solid-state electrolyte (SSE), such as a ceramic electrolyte. In some embodiments, physical agitation is performed in the presence of a passivating material, which is selected to neutralize adverse reactions from the charge material and promote reactions that produce beneficial products and contribute to the recycled value.

[0014] Chemical properties of SSE and comparison with conventional LIBs "Solid-state electrolytes" and "solid-state ionics" were first conceptualized in the 1960s with β-alumina (Na2O·11Al2O3) in Na-S batteries. For lithium-ion chemistry, LiI compounds have found application in slow-dren thin-film microbatteries. However, limitations regarding power density, processing, and cost have prevented their use in wider applications, and solid electrolytes have largely been ruled out due to the superior electrochemical performance of liquid electrolyte-based systems utilizing LiPF6 salts dissolved in organic solvents. Nevertheless, recent developments in solid electrolytes, with oxide-, sulfide-, and polymer-based chemistries, have led to renewed interest in this field and show promise in various forms for the realization of commercial ASSBs.

[0015] Oxide-based SSEs, first developed in the 1970s, can exist as glassy / amorphous or crystalline forms. Glass-ceramic oxide compounds are generally Li2O-MO, which has a disordered structure of network-modifying oxides of Li2O and network-forming oxides such as SiO2, B2O3, P2O5, and GeO2. x (M = Si, B, P, Ge, etc.) x PO y N z(LiPON) is a glass-ceramic thin film SSE that has enhanced chemical stability against water and lithium metal along with a wider voltage range. However, the ionic conductivity of glass-ceramic / amorphous oxides remains very low, with room temperature conductivities of 10 -6 ~10 -9 Recent interest in oxide SSEs has focused on garnet- and perovskite-type crystalline SSEs, ranging from LiM2(PO4)3-type LISICON to garnet-type LLZO and perovskite-type LLTO. These materials have a conductivity of about 10 -3 Although oxide-based SSEs show much higher promise with ionic conductivities of 500 S / cm and improved electrochemical and thermal stability, certain chemistries utilize rare elements such as Ge or expensive processing techniques. Furthermore, oxide-based SSEs may suffer further from poor long-term cycling stability due to mechanical brittleness or chemical incompatibility with other battery components, which in turn requires a separate interfacial layer between the electrolyte / electrode components.

[0016] Sulfide-based SSEs, including the Li2S-SiS2 system, were first developed in the 1980s. The observed high ionic conductivity was attributed to the weaker bond strength between sulfur and lithium, which allowed for more free-moving lithium ions. Sulfide-type solid electrolytes can also be classified as glassy or crystalline, including Li6PS5X (X = Cl, Br, or I) argyrodite, Li2S-PS5 thio-LISICON, and Li 11-x M 2-x P 1+x S 12 Li-PS-based chemistries, such as (M = Ge, Sn, and Si) compounds, are also available. Crystalline thio-LISICONs, of course, exhibit high conductivity comparable to that of liquid electrolytes, making them particularly important for research and development. Sulfide-based SSEs also allow for excellent and viable cathode / electrolyte contact due to their mechanical flexibility, in contrast to the relative hardness and brittleness of oxide-based SSEs. However, limitations surround the chemical instability of this SSE chemistry in ambient environments, raising potential durability and safety concerns in the manufacturing or recycling environments.

[0017] Polymer and polymer / composite SSEs tend to be nonvolatile and have excellent mechanical flexibility, processability, and compatibility with lithium metal. These SSEs typically require a polymer host with a lithium salt, such as LiTFSI, as a solid solvent. Lithium ions migrate along or between polymer chains from one coordination site to a new site or jump from one chain to another under the effect of an electric field. While several types of polymer hosts are available, polyethylene oxide (PEO) is the most widely used among other types of polymer-based SSEs due to its maturity and excellent electrochemical performance. Polymer composites utilize the same polymer SSEs but with ceramic fillers such as LiAlO2, Al2O3, and SiO2 to improve ionic conductivity by lowering the glass transition temperature. Unfortunately, limitations in thermal stability, chemical compatibility with energy-high-density positive electrodes, and lower oxidation voltages can severely limit polymer-based SSEs for use in typical LIB cathode / anode pairs. While recent developments may continue to show promise for polymer-based SSEs, there is a greater trend towards the development of sulfide- and oxide-based SSEs.

[0018] ASSB structure and manufacturing The difference in cell structure between ASSBs and conventional LIBs is illustrated in Figure 1. In ASSBs, the SSE acts as both a liquid electrolyte and a polymer separator in the form of a dense layer, and furthermore, the SSE material must be thoroughly mixed within each electrode (except in the case of the lithium metal anode) to provide an ionically conductive network and ensure good contact with the active material. For oxide-based SSEs, the active electrode and SSE material are mixed and co-sintered to ensure good contact. For sulfide- and polymer-based SSEs, contact is achieved by cold pressing due to the advantageous mechanical flexibility of these materials.

[0019] In addition to different structures and chemistries, in some embodiments, ASSBs may also require different manufacturing processes compared to conventional LIBs. In conventional LIB assembly, anode and cathode films can be fabricated and wound together with a separator layer in a roll-to-roll process, followed by infiltration with a liquid electrolyte. Repeated cell formation cycles / conditioning are required to create stable solid electrolyte interphase layers on the anode and cathode. However, roll-to-roll processes are not particularly suitable for ASSBs because a dense SSE layer must remain between the electrode layers, which can result in cracks or voids in conventional roll-to-roll processes.

[0020] Therefore, ASSBs are typically manufactured by cutting and stacking single sheets to create a cell stack. In some embodiments, bipolar plates are used, with the cathode material coated on one side of the current collector and the anode material coated on the other side. This form factor allows for higher energy densities and limits the form factor to prismatic and pouch cells. Because lithium metal has significant adhesive properties that preclude conventional cutting techniques, ASSBs utilizing lithium metal anodes require the use of laser cutting methods.

[0021] [Table 1]

[0022] The components of conventional LIBs and ASSBs, as well as the material costs of conventional LIBs, are listed in Table 1. The material cost of the liquid electrolyte in conventional LIBs is significantly higher than the other major components on a per-weight basis, and is just as expensive as some anode and cathode materials (although their actual weight fraction in the cell is much smaller). For ASSBs, the material cost of the SSE can be even higher, for example, the sulfide-based Li7P3S 11 The cost is approximately $50 / kg for 1000 kJ / kg. This cost can be even higher if processing and handling costs are factored in when manufacturing the electrolyte and incorporating it into the cell manufacturing.

[0023] SSEs typically reach their end-of-life due to a degradation mechanism attributed to the solid electrolyte / electrode interface. Various mechanisms can occur, including the formation of a space charge layer, interdiffusion of elements, and electrochemical bombardment at the active material / electrolyte interface. Cracks and voids can form in the SSE layer due to cathode-related volume changes during repeated electrochemical cycling, reducing the ionic conductivity of the cell. Furthermore, SSEs cannot completely mitigate the phenomenon of Li dendrite formation, which can grow along grain boundaries and cause internal short circuits.

[0024] Possible challenges of recycling ASSBs versus conventional LIBs Due to the significant differences in the chemical properties and structure of ASSBs compared to conventional LIBs, there are unique aspects that must be taken into consideration when recycling ASSBs. One of the main challenges is the separation of SSEs from other cell components. In conventional LIBs, the liquid electrolyte can be easily washed away after cell disassembly by using solvents such as N-methyl-2-pyrrolidone. While some studies have demonstrated recovery using supercritical CO2 as a solvent, the separated liquid electrolyte in conventional LIB recycling is typically not recovered and is an irrecoverable loss. Due to the useful value of the materials shown in Table 1, a recycling system for ASSBs should be able to recover and regenerate SSEs in a practical manner. However, the homogeneous mixture and solid nature of SSEs precludes viable cleaning methods for oxide-based chemistries in which the SSEs and cathode active material are co-sintered. On the other hand, sulfide-based and polymer-based SSEs present possible solvent-based separation methods. An effective recycling process must also consider handling ASSB feedstocks, which can contain different types of SSEs and cathodes, and be able to separate and regenerate the materials in an appropriate manner.

[0025] While lithium metal anodes enable higher cell energy densities, these anodes can pose some recycling challenges when a single cell within a module has an internal short circuit and the module is discarded with a significant amount of residual lithium metal. Lithium metal is known to be sticky, which can create problems with mechanical separation methods such as shredding, crushing, or sieving. Furthermore, the reactivity of lithium metal poses significant safety hazards, particularly in solution-based processes or other non-ideal environments where lithium can undergo rapid exothermic reactions. Even conventional LIBs that do not utilize lithium metal anodes have previously posed safety risks due to their inherent reactivity. Over the past decade, several accidents have occurred due to the storage of significant amounts of LIB waste. Because there may be even more reactive materials in discarded ASSBs, this safety issue must be accounted for when designing a recycling process.

[0026] Additionally, the chemical nature of SSEs themselves may pose stability or safety issues, requiring special processes or environments to handle the SSEs. In particular, for sulfide-based SSEs, they are unstable in the presence of water / humid atmospheres and readily hydrolyze, generating toxic H2S gas as a by-product, posing significant safety hazards to human health. Oxide-based SSEs are much more stable at ambient conditions and can be handled with low health risks. However, they are susceptible to Li / H reactions, which can occur from reactions between lattice lithium and H2O and CO2 in the air. + They may still be subject to some level of degradation upon exposure to water due to exchange and the formation of various Li salts on the surface. Also, while PEO polymer-based SSEs present a low level of risk, PEO is highly hygroscopic and can readily absorb water. These issues are accentuated during processes such as cell isolation and solution-based processing, and are discussed in the next section.

[0027] Current type of recirculation method Modern LIB recycling methods typically utilize a combination of mechanical separation, pyrometallurgy, and hydrometallurgy processes to subdivide battery components into different forms that are used to resynthesize new materials. Hydrometallurgy and pyrometallurgy chemically break down materials into other usable forms. Due to the more complex compositions, chemistries, form factors, and potentially more valuable metals in ASSB systems, these traditional recycling processes are suitable, but additional challenges must be taken into account. A list of each recycling process step and the challenges associated with ASSB recycling is shown in Figures 2A-2E.

[0028] Mechanical separation of battery packs and modules is often necessary to prepare feedstock for other recycling processes. The primary objective of this process is to separate the major components using a combination of disassembly, shredding, crushing, and sieving. Cell disassembly is not widely utilized for large-scale processing, particularly in EV and hybrid battery packs, due to a lack of size and shape standards, which are eliminated in favor of simpler shredding and sieving processes. Current collectors and most of the cell-casing material are removed due to physical differences with the electrode / electrolyte materials, such as density, size, and malleability. Additionally, moderate heat treatments and organic solvent washing steps are often used to remove organic binders and / or electrolytes. The mechanical separation process results in a mixture of cathode and anode powders, often referred to as "black mass," which is then further separated and processed using hydrometallurgy or direct recycling techniques.

[0029] While common with conventional LIB recycling, ASSB systems pose additional challenges to these conventional processes. Along with the aforementioned issues with ASSBs with Li metal anodes, the flexibility of sulfide- and polymer-based SSEs can also present difficulties in separating the black mass from the current collector or passing it through a mesh filter. Furthermore, while the cathode and anode are typically composed of micron-sized particles held together by a binder, electrodes utilizing oxide-based SSEs require a sintered contact between the two electrodes, as well as a dense sintered layer. Therefore, in addition to exacerbating tool damage during the chopping / crushing process due to the hardness of these ceramic powders, physically separating the cathode material from the SSE material is impractical.

[0030] The pyrometallurgical process involves using high-temperature furnaces to refine metal oxides from spent LIBs into alloys of Co, Cu, Fe, and Ni derived from the combination of cathodes, cell casings, and current collectors. A significant advantage of ASSB recycling is that entire battery packs and modules can be used directly as feedstock, so no sorting or pre-processing steps are required. Worker safety and reactivity issues are minimal, as the high furnace temperatures of this process eliminate potential hazards and the use of chimneys to funnel gases from the working environment. Commercialization of this technology lies in the simplicity and thoroughness of the science; Umicore and other companies are successfully recycling high-value metals using pyrometallurgy.

[0031] However, the high melting temperatures required for this technology incur significant energy costs. While oxidation of carbon additives, graphite anodes, and other materials can provide a significant portion of the energy for the process, it also results in the irrecoverable loss of these components and the generation of significant amounts of CO2. Furthermore, Mn, Li, and Al are typically oxidized during melting and removed as part of the slag, further reducing potential recovery rates. Polymer-based and sulfide-based SSEs are burned off or become part of the slag and cannot be recovered in this manner, and sulfide-based SSEs sometimes produce toxic gases as by-products that must be purified before release into the atmosphere. For oxide-based SSEs, valuable metals such as La, Zr, Ti, and Ge become part of the molten alloy or slag, making them difficult to separate for cathode and SSE fabrication. It is also not an optimized recycling system, as significant energy is used to recover the alloy, which must then be subdivided and synthesized into battery components by methods such as hydrometallurgy and chemical precipitation processes, which require additional energy, time, and material input costs. Finally, this method typically has a rather low recovery rate, and although it can usually be made economically viable by focusing on recovering valuable metals such as cobalt, this is not sustainable as next generation cathodes aim to reduce the cobalt portion.

[0032] Hydrometallurgy is a wet-chemistry-based method that involves chemically decomposing metal compounds and dissolving them in solution through acid-base leaching, purifying, and concentrating various valuable metals contained in the solution, and finally precipitating the desired materials using appropriate counteranions such as carbonate, oxalate, or hydroxide. It offers high recovery rates (>90%) for most LIB components, regenerating high-purity materials, and the potential for handling different cathode chemistries, with low energy costs and gas emissions. To increase the reaction rate of acid-base leaching, discarded LIBs are typically mechanically separated and sieved to remove cell casing and current collector materials. The resulting black mass is then heated to burn off residual organic solvents and binders, and subsequently dispersed in a solution such as sulfuric acid and hydrogen peroxide, where the cathode material is dissolved while the more chemically stable carbonaceous material is separated as a cake and can be separately harvested and regenerated. This process is less mature than pyrometallurgy, and there have been continuous improvements through modifications of leaching agents, extraction processes, and regeneration methods. A significant advantage of hydrometallurgical recycle is that the process of adjusting the pH and adjusting the complexing and precipitating agents results in high purity LiNi x Mn y Co z The advantage is that it is possible to selectively co-precipitate O2 (NMC) compounds and SSE materials with the appropriate morphology, and precipitation of the desired composition can be achieved through a combination of inductively coupled plasma (ICP) measurements and the addition of selected transition metal salts to modify the reactor solution to the targeted composition, allowing for feedstocks that are effectively tolerant to different NMC or oxide-based SSE chemistries.

[0033] Hydrometallurgical processes can recycle most LIB components to regenerate high-purity materials with high recovery rates, low energy costs, and CO2 emissions. However, the process is complex and expensive, especially considering the input costs of materials and the significant amount of hazardous waste solution generated. Furthermore, hydrometallurgical methods may not be suitable for certain ASSB systems. Highly reactive Li metal can react violently in the leach solution if not pretreated beforehand. Furthermore, sulfide-based SSEs cannot be dispersed in water due to their instability and the generation of toxic H2S gas. While polymer-based SSEs can have some solubility in aqueous acid solutions, even small concentrations can significantly alter the viscosity of the reactor solution, potentially adversely affecting the co-precipitation process, making an effective form of recovery / separation of PEO and LiTFSI from solution unlikely.

[0034] Oxide-based SSEs and transition metal oxide cathodes are similar in chemistry, allowing for the selective precipitation of NMC or SSE compounds through careful selection of counteranions and reactor conditions. It has been demonstrated that nickel, cobalt, and manganese can be successfully separated in sulfate solutions through careful adjustment of temperature, pH, and the use of specific extractants such as Na-Cyanex-272 and Na-D2EHPA. Further fine-tuning of reactor conditions and the use of specialized extractants (e.g., Cyanex-572, designed for rare earth elements) could likely enable the selective separation and precipitation of SSE-related compounds from cathode-related compounds as well as from any metal oxide coating formulations commonly used to suppress electrolyte / cathode reactions. Furthermore, metal hydroxides of commonly used elements for oxide-based SSEs, such as lanthanum, zirconium, and titanium, can selectively separate and precipitate nickel, manganese, and cobalt. sp K several orders of magnitude lower than the value spvalues are shown. This significant difference in solubility can also be exploited for the selective precipitation of SSE materials from cathode materials, although chelating and extracting agents may still be required to obtain the desired morphology. While hydrometallurgy has significant advantages when recycling conventional cathode and anodic compounds, the chemical nature of SSE and the complexity of the combined cathode / SSE mixture are significant obstacles to the recycling of ASSB.

[0035] The direct recycling process for ASSB involves regenerating or recycling materials without the need to chemically decompose and resynthesize battery components. Therefore, an ideal direct recycling system would incur lower energy costs than conventional recycling by avoiding material and / or high energy inputs to decompose and release stored energy in NMC or SSE compounds. The direct recycling method, when taking into account both material input and processing, would incur much less energy costs than hydrometallurgical and pyrometallurgical methods, approximately 5 MJ / kg, respectively. cathode and approximately 0.6 kg CO2eq / kg cathode Existing research using the EverBatt model of LiCoO2 has demonstrated that the hydrometallurgical and pyrometallurgical processes require only a small amount of energy while producing greenhouse gas emissions of about 2.3 and 2.5 kg, respectively. CO2eq / kg cathode While generating approximately 31 and 19 MJ / kg cathode From an economic standpoint, the development of direct recycle processes may be important to achieve economic viability.

[0036] Direct recycling can therefore have the advantages of low energy costs combined with environmental friendliness. Aged or degraded materials can be regenerated to their original state, and depending on the process, a relatively easy and simple process can be achieved to convert the received material into components ready for new electrode fabrication. The main step in direct recycling involves a relithiation process in which the lithium-depleted cathode material reacts with a lithium source to restore its original stoichiometry, followed by, or in conjunction with, a heat treatment to restore the surface structure and morphology. Because conventional liquid electrolytes are typically washed away before cathode regeneration, the addition of SSEs can add complexity to this process.

[0037] In hydrothermal regeneration, depleted cathode material such as NMC, LCO, or LMO is dispersed in an aqueous solution of a lithium salt such as LiOH or Li2SO4, sealed in a chemically inert container such as Teflon, and heated to 100-200°C for several hours. This is usually followed by washing, filtration, and a brief heat treatment step to restore the surface properties. This method allows for the regeneration of cathode powders at different levels of lithium depletion, a significant advantage over traditional solid-state regeneration, where the chemical composition of each batch must be analyzed to determine the amount of additional lithium salt required. Furthermore, Li 1+x Al x Ti 2-x Certain solid electrolytes, such as (PO4), have been successfully synthesized using hydrothermal methods. While there has been very little research utilizing hydrothermal methods for solid electrolytes, regeneration by this method is possible due to the similarity in chemistry and proof-of-concept for oxide-based cathodes. In particular, this may be particularly advantageous from a processing standpoint, where well-mixed or co-sintered cathode-electrolyte powders do not require complete separation for regeneration. A subsequent heat treatment step can function both as a surface recovery step and to reestablish sintered contact between the cathode and electrolyte particles.

[0038] PS4 3-Sulfide-based SSEs utilizing thiophosphates are readily solvated in polar solvents. The dissolution / precipitation method can then be used as an effective recycling method for sulfide-based ASSBs. Using inexpensive and safe solvents such as ethanol or acetonitrile, sulfide-based SSEs can be dissolved and filtered from the rest of the cell components. These solvents are nonreactive with conventional cathodes and anodes, and the dissolution process occurs without chemical decomposition of the SSEs, which are well dissolved and recrystallized into crystalline form for reuse in ASSBs. The insoluble cathode and anode powders can be processed and regenerated separately, while the polar solvent solution allows for recovery of the SSEs by evaporation and collection of the low-vapor-pressure solvent. This is typically followed by a moderate heat treatment of the precipitated SSE material to increase particle size and thereby improve conductivity, before being reprocessed into high-density SSE films or used in electrode fabrication. Overall, this low-energy-intensive process can produce very little waste while having a high recovery rate.

[0039] Certain polymer-based SSEs may also find application in recycling and recovery using dissolution / precipitation methods. PEO is a well-studied material and is soluble in several polar solvents, such as water and acetonitrile. This is a significant advantage in the production of polymer-based SSEs, but it can also enable an effective method for separating PEO-based SSEs from the rest of the cell components or black mass. Commonly used lithium salts, such as LiTFSI, are also soluble in water, potentially enabling a safe and cost-effective method for SSE recycling. Additionally, several studies have demonstrated complete solubility and dissolution of PEO in the monomer within 30 minutes of water immersion without the need for agitation. The monomer and Li salt can then be returned to the SSE / polymer network by removal of water under heat.

[0040] ASSB recirculation design and requirements In the process flow diagram shown in Figure 3, the inventors envision an embodiment of a method for recycling ASSBs, taking into account cell pack configurations, safety requirements, and the processability of different ASSB systems. In an initial step, cell packs are separated based on their internal chemistry, inspected for integrity, and then fully discharged to restore any electrical work and minimize the amount of residual lithium or other reactive components. In situations where this is not feasible, cell pack disassembly occurs in a dry, carbon dioxide-rich environment (<4% oxygen) and utilizes an automated process for shredding and / or crushing the cell packs. Workers are protected from exposure to hazardous conditions, and the reactivity of the disassembled cell components is suppressed by the absence of moisture, preventing the formation of H2S gas from sulfide-based SSEs while converting residual lithium metal to stable lithium carbonate compounds by reaction with CO2. Subsequent sieving allows for the separation of outer cell pack components and / or current collectors, which are recycled or disposed of using conventional methods.

[0041] The resulting anode, cathode, and SSE powders are then dispersed and thoroughly washed in a polar solvent, such as ethanol, to first dissolve the sulfide-based SSE, followed by filtration to separate the insoluble components from the solution. The solution is collected and evaporated to recrystallize the sulfide-based SSE material, which is then heat-treated to refine its microstructure and reintroduced into new ASSB production. To isolate the potential PEO-based polymer SSE, an additional washing step is performed using water or a water / alcohol mixture above 50°C due to the viscosity of the PEO solution. This solution ideally contains PEO monomer and Li salt (LiTFSI), which is converted to SSE by heating and solvent removal. Hydrothermal or hydrometallurgical methods are used to separate and process the insoluble components.

[0042] For the hydrothermal regeneration process, it may be appropriate to first separate any graphite or carbon black from the solid mixture using a form of gravity separation. The remaining cathode-SSE solids are then dispersed in an aqueous solution. Any residual lithium carbonate from the preceding lithium-metal reaction is also soluble and contributes to the aqueous lithium salt solution required for hydrothermal regeneration; pH measurements can be used to determine the lithium concentration in the solution and lithium salts can be added to achieve the desired consistency. After hydrothermal regeneration, the powder batch is measured for chemical composition, and additional cathode or SSE powder is added to achieve the desired cathode / electrolyte ratio. The powder batch is then co-sintered to restore surface morphology and form cathode / SSE particle contacts, prior to incorporation into a new ASSB fabrication.

[0043] If the feedstock is known to contain cathode or oxide-based SSEs of various compositions, a hydrometallurgical process may be appropriate. The solids mixture is dispersed in an acid leach solution, and the inert graphite and carbon black are separated as a filter cake. ICP analysis and additional transition metal salts are required to achieve the target NMC and SSE compositions in solution. These steps are followed by a carefully controlled process to separately precipitate and collect NMC precursor compounds using selective counteranions, chelating agents, and extractants, followed by precipitation and collection of SSE compounds and potential coating formulations. The NMC and SSE materials are separately lithiated / heat treated using solid-state methods and incorporated into new ASSB production.

[0044] In a method embodiment, a recycling process for an all-solid-state battery (ASSB) accepts a recycled stream from a battery having a solid-state electrolyte (SSE), such as a ceramic electrolyte, and physical agitation is performed in the presence of a passivating material selected to neutralize deleterious reactions from the charge material and promote reactions that produce beneficial products and contribute to the recycled value.

[0045] Embodiments of the methods described herein are based, in part, on the observation that solid electrolytes are more popular than traditional liquid electrolytes due to their safety in avoiding uncontrolled discharge that can lead to undetected fires. Unfortunately, traditional methods suffer from the drawback that SSE charging materials are often used with metal anodes, such as lithium metal or silicon metal, which can be volatile when decomposed in an oxygen atmosphere. Thus, the present configurations substantially overcome the drawbacks of traditional methods by providing a passivating material that not only prevents harmful atmospheric reactions of the lithium metal anode material, but also produces beneficial products from reaction with the liberated lithium metal anode material.

[0046] The difference in cell structure between ASSBs and conventional lithium-ion batteries is illustrated in Figures 1A and 1B, where, instead of a liquid electrolyte and a polymer separator, the SSE, in the form of a dense layer, acts as both. Furthermore, to provide an ionically conductive network (except in the case of a lithium metal anode), the SSE material must be thoroughly mixed within each electrode to ensure intimate contact with the active material. For oxide-based SSEs, this typically requires mixing and co-sintering of the active electrode and SSE material. For sulfide- and polymer-based SSEs, this contact is achieved by cold pressing due to the advantageous mechanical flexibility of these materials.

[0047] As illustrated in Figure 1B, the solid electrolyte material is mixed with the charge material to form a dense aggregate of high-purity electrolyte rather than a dispersed layer of separator material as in Figure 1A. Any residual charge remaining within the ASSB cell can be suddenly dissipated when the conductive current collectors are simultaneously physically disassembled. The passivation material neutralizes and influences this electrochemical reaction to define beneficial products.

[0048] In embodiments described herein, a method for recycling solid-state batteries includes receiving a recycle stream of secondary batteries comprising a solid electrolyte (SSE) mixed with a charge material, as illustrated in FIG. 1B. The recycle process introduces a passivating substance, such as a gaseous environment, to neutralize unwanted reaction or discharge of the charge material from the batteries defining the recycle stream. Therefore, because the state of the batteries entering the recycle stream is unknown, the ASSB does not need to be manually discharged before recycling. A mechanical process agitates the batteries in the recycle stream to liberate the charge material and electrolyte stored therein. The mechanical process includes various physical manipulations, such as physically shredding, hammering, or pulverizing the battery container, current collectors, and charge material. Further processing includes separating the nickel, manganese, and cobalt (NMC) from the current collectors by at least one of eddy current and froth flotation, resulting in a granular or powdery substance defining the charge material and solid electrolyte.

[0049] The recycling process involves recovering the charge material and electrolyte from the agitated battery, allowing the passivating material to combine with the agitated battery to produce useful products. In contrast, conventional liquid electrolytes are often dissolved and lost through leaching of the charge material, along with significant lithium.

[0050] In some embodiments, the battery includes a metal anode, where the metal anode is reactive in a non-inert environment, and the passivating material mitigates harmful reactions with the anode metal and participates in beneficial reactions to produce output products. The output products are present and change based on gas reactions with the anode material in the charging material. Silicon metal and lithium metal are often used as anode charging materials; however, lithium metal has improved storage capacity and is more reactive in uncontrolled (oxygenated) atmospheres. In some embodiments, the lithium metal is coated with a conductive polymer.

[0051] In some embodiments, the solid electrolyte is an organic electrolyte or a polymer gel electrolyte (adhesive polymer electrolyte), an aqueous electrolyte, or a ceramic electrolyte.

[0052] In some embodiments, the passivating material comprises CO, resulting in a lithium carbonate precursor comprising LiC0, which upon heating produces lithium carbonate. In another embodiment, the passivating material is hydrogen sulfide, resulting in valuable products such as hydrogen and LiS. In some embodiments, the passivating material contains a suitable inert gas such that the valuable product is lithium hydroxide.

[0053] In some embodiments, the cells in the recycle stream have an NMC (nickel, manganese, cobalt) based chemistry for the cathode material. However, other suitable battery chemistries can be used in other embodiments of the method. The passivation material is selected based on the charge material, particularly the anode metallic charge material, used in conjunction with the SSE. In some embodiments, the passivation material is a mixture of a reducing gas and an inert gas. In other embodiments, the passivation material is a fire-extinguishing gas.

[0054] In some embodiments of the method, the ASSB is drilled in a CO2-rich environment, thereby passivating the highly reactive lithium metal, making the ASSB safe for mechanical degradation, for example, in a hammer mill, shear shredder, roll crusher, or similar equipment. The passivation reaction is as follows: Li+CO2=Li2C2O4 Li2C2O4 + high T = Li2CO3 + CO In an alternative embodiment, instead of drilling the ASSB in a CO2-rich environment, CO2 gas is injected directly into the cell. In some embodiments of the method, the module or pouch or pack is shredded directly in the presence of CO2 gas. In some embodiments, the CO2-rich environment contains argon or another inert gas. In some embodiments, the pressure of the passivation material is maintained at ambient pressure or 1 atm. In some embodiments, the passivation material is a shielding gas.

[0055] In some embodiments, the ASSB is drilled in an HS-rich environment to obtain lithium sulfide. The reaction is Li + HS = LiS + H. In an alternative embodiment, HS gas is injected directly into the ASSB. In other embodiments, the module or pack is shredded in the presence of HS gas. In some embodiments, the battery, including cells, modules, and packs, is cooled below 0°C and shredded in an inert atmosphere, for example, in the presence of helium, argon, neon, xenon, krypton, radon, CO, or HS.

[0056] In some embodiments, the shredding equipment, such as a hammer mill, shear shredder, roll crusher, etc., is maintained at or below 0° C. during shredding.

[0057] The battery is sheared, shredded, or roll-crushed to separate the NMC cathode material and foil from the ceramic separator and lithium metal or compound. In an alternative embodiment, the NMC and aluminum are separated from the anode material by eddy currents. In an alternative embodiment, the NMC and aluminum are separated from the anode material by froth flotation.

[0058] The shredded material (black mass) is sieved in an inert atmosphere or in the presence of mineral oil, allowing for the recovery of lithium metal. Upon sieving, the black mass contains the cathode powder, salt from the metal-based anode, and solid electrolyte material. The solid electrolyte material, e.g., sulfide, polymer, etc., is selectively dissolved in a suitable solvent to obtain the cathode material. In some embodiments, lithium-based anode compounds, e.g., lithium hydroxide, lithium carbonate, lithium sulfide, lithium sulfate, etc., are washed with cold water to dissolve the lithium ions. The lithium solution is then filtered, purified, and crystallized as a lithium salt. The solid electrolyte material is subjected to a hydrometallurgical process to recover the salt, precursor, or cathode material. If the solid electrolyte material, e.g., oxide, is not soluble, both the solid electrolyte and the cathode material are leached in an acidic solution.

[0059] Dissolved cathode materials with or without solid electrolytes can be separated based on different solubilities, pH, etc. to remove the solid electrolyte elements in the leaching solution, resulting in a solution containing Ni, Mn, Co, Li, and / or Na ions. The purified solution can be subjected to solvent extraction to separate the different elements or adjust the ratios of the different elements before directly synthesizing NMC precursors. In some embodiments, the lithium recovered by the recycling methods described herein is at least 80%.

[0060] Some of the embodiments described herein were published in Matter (2020) “Recycling for All Solid-State Lithium-Ion Batteries,” co-authors Luqman Azhari, Sungyool Bong, Xiaotu Ma, and Yan Wang.

[0061] The invention described herein is the most practical method. However, it is understood that deviations may be made within the scope of the invention and that improvements will occur to those skilled in the art. In that regard, the optimum dimensional relationships for the parts of the invention to encompass variations in size, material, shape, form, function, steps, and methods of operation, assembly, and use will be apparent to those skilled in the art in light of the above description, and it should be understood that all equivalent relationships to those illustrated in the drawings and described herein are intended to be encompassed by the present invention.

[0062] Accordingly, the foregoing is considered as illustrative only of the principles of the invention. Moreover, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described; therefore, all suitable modifications and equivalents may be used with the present invention and be included within the scope of the invention. Such equivalents are within the scope of the invention and the claims. The contents of all references cited in this application, including issued patents and published patent applications, are hereby incorporated by reference.

[0063] The present invention is now fully described and is further defined by the claims that follow.

Claims

1. 1. A method for recycling an all solid state battery (ASSB), the method comprising: receiving a recycle stream of spent ASSB including an electrolyte mixed with at least one charge material; introducing a passivation material to neutralize electrochemical reaction or discharge of the charged material from the cells defining the recirculation stream; agitating the batteries in the recycle stream in the presence of the passivating material to liberate the charge material and electrolyte stored therein; and recovering the charge material and the electrolyte from the agitated battery, wherein the passivating material combines with the agitated charge material or electrolyte to form a useful product, thereby recycling the ASSB.

2. 10. The method of claim 1, wherein the battery comprises a metal-based anode, a cathode, and a solid-state electrolyte (SSE).

3. The method of claim 2 wherein the metallic anode is reactive in a non-inert environment.

4. 3. The method of claim 2, wherein the passivation material mitigates deleterious reactions with the metallic anode and is an input to a beneficial reaction to produce the beneficial product.

5. The method of claim 2 , wherein the solid electrolyte comprises lithium metal.

6. 10. The method of claim 1, further comprising sorting the recycle stream of ASSB based on solid electrolyte type prior to introduction.

7. The method of claim 1 , wherein the passivating material is at least one selected from a reducing gas and an inert gas.

8. 8. The method of claim 7, wherein the reducing gas is at least one selected from carbon dioxide, air, nitrogen, and hydrogen sulfide.

9. The method of claim 7 , wherein the inert gas comprises at least one of helium, argon, neon, xenon, krypton, and radon.

10. The method of claim 7 , wherein the passivation material comprises air and argon.

11. 9. The method of claim 8, wherein the percentage of the reducing gas in the passivating material is at least 99%, or at least 95%, or at least 90%, or at least 85%, or at least 80%, or at least 75%, or at least 70%.

12. 8. The method of claim 7, wherein the percentage of the inert gas in the passivating material is at least 1%, or at least 5%, or at least 10%, or at least 15%, or at least 20%, or at least 25%, or at least 30%.

13. 10. The method of claim 1, further comprising sieving the charged material and beneficial product after stirring.

14. 14. The method of claim 13, further comprising, after sieving, washing the beneficial product with water to dissolve the beneficial product and purify the beneficial product.

15. 10. The method of claim 1, wherein the ASSB is in at least one form selected from a stack, a bag, a fold-over pouch, and a cylindrical roll.

16. 10. The method of claim 1, wherein the valuable product obtained is at least one selected from lithium carbonate precursor, lithium nitride, lithium hydroxide, lithium carbonate, lithium oxalate, hydrogen, and lithium sulfide.

17. 10. The method of claim 1, wherein the cells in the recycle stream have an NMC (nickel, manganese, cobalt) based chemistry for the cathode material.

18. 10. The method of claim 1, further comprising drilling the ASSB and injecting the passivating material prior to agitating.

19. The method of claim 1 , wherein the agitating further comprises at least one of chopping, hammering, and pulverizing.

20. 18. The method of claim 17, further comprising separating the NMC and current collector by at least one method selected from eddy current and froth floating.

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