Methods for recovery of critical materials from battery waste

Abstract

In one aspect, the disclosure relates to a method for recovering critical materials, comprising: combining a sample of black mass and a loading solvent, thereby forming a first mixture; heating the first mixture at a pressure of about 150 psi to about 600 psi, thereby forming a treated mixture comprising a solid residue and an aqueous solution; and separating the solid residue from the aqueous solution; wherein the sample of black mass comprises at least one critical material; wherein the loading solvent comprises at least one leaching agent and at least one reducing agent, wherein the reducing agent comprises a biomass feedstock; and wherein the treated mixture comprises at least one critical material. This abstract is intended as a scanning tool for purposes of searching in the particular art and is not intended to be limiting of the present disclosure.

Description

ATTORNEY DOCKET NO.222204-2800 METHODS FOR RECOVERY OF CRITICAL MATERIALS FROM BATTERY WASTE CROSS REFERENCE TO RELATED APPLICATIONS

[0001] Application claims the benefit of and priority to U.S. Provisional Application No. 63 / 687,414 filed on August 27, 2024, which is incorporated herein by reference in its entirety. BACKGROUND

[0002] Lithium-ion batteries (LIBs) have been widely used in electronic products due to their advantages of large capacity, long cycle life, high safety, and environmental. Spent LIBs contain critical materials such as lithium, nickel, cobalt, and manganese. Materials such as these pose an environmental hazard if discarded arbitrarily. In addition, these metals are nonferrous metal resources that are worth recovering from both economic and environmental perspectives. Current methods to recycle spent LIBs include pyrometallurgy, biometallurgy, and hydrometallurgy. Hydrometallurgy is considered an effective way to recycle spent LIBs due to its lower energy consumption compared to pyrometallurgy and the absence of a requirement to consider microbial growth kinetics, which is a factor in biometallurgy.

[0003] Conventional hydrometallurgy utilizes a combination of strong inorganic acids, such as H2SO4, HCl, and HNO3, along with reductants (e.g., H2O2) to effectively extract metals from spent LIBs. However, even though the use of H2O2demonstrates the potential for the efficient recovery of valuable elements, its inherent instability and relatively high cost necessitate the exploration of other reductants. Many alternative inorganic reductants, such as sulfur- containing and nitrogen-containing reductants, generate toxic by-products during the extraction process. Organic reductants, while more environmentally friendly than inorganic reductants, are typically less efficient at extracting metals from spent batteries. Despite advances in LIB recycling capabilities, there remains a scarcity of recycling strategies that are cost-effective, environmentally sustainable, and efficient. These needs and other needs are satisfied by the present disclosure. SUMMARY

[0004] In accordance with the purpose(s) of the disclosure, as embodied and broadly described herein, the disclosure, in one aspect, relates to a method for recovering critical materials, comprising: combining a sample of black mass and a loading solvent, thereby forming a first mixture; heating the first mixture at a pressure of about 150 psi to about 600 psi, thereby forming a treated mixture comprising a solid residue and an aqueous solution; and separating the solid residue from the aqueous solution; wherein the sample of black mass comprises at least on critical material; wherein the loading solvent comprises at least one leaching agent and at least one reducing agent, wherein the reducing agent comprises a biomass feedstock; and wherein the treated mixture comprises at least one critical material.

[0005] Other systems, methods, features, and advantages of the present disclosure will beATTORNEY DOCKET NO.222204-2800 or become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present disclosure, and be protected by the accompanying claims. In addition, all optional and preferred features and modifications of the described aspects are usable in all aspects of the disclosure taught herein. Furthermore, the individual features of the dependent claims, as well as all optional and preferred features and modifications of the described aspects are combinable and interchangeable with one another. BRIEF DESCRIPTION OF THE FIGURES

[0006] Many aspects of the present disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.

[0007] FIGS. 1A-1E show representative plots demonstrating the effect that variations in grass leaves dosage (FIG.1A), temperature (FIG.1B), H2SO4concentration (FIG.1C), solid concentration (FIG.1D), and reaction time (FIG.1E) have on the leaching efficiency of various metals from NCM black mass.

[0008] FIGS.2A-2B show representative SEM images of grass leaves before (FIG.2A) and after (FIG.2B) microwave-assisted leaching.

[0009] FIGS.3A-3I show representative plots demonstrating the effect of temperature and time on the leaching efficiencies of Li, Mn, Co, and Ni at 120 °C (FIG.3A), 140 °C (FIG.3B), 160 °C (FIG. 3C), and 180 °C (FIG. 3D) from NCM black mass in a microwave-assisted leaching process, with kinetic fitting results (FIGS.3E-3H), and fitting curves for the Arrhenius equation (FIGS.3I-3L).

[0010] FIG.4A shows representative XRD patterns for NCM black mass, grass leaves, and leaching residue treated under a 180 ºC microwave-assisted leaching process.

[0011] FIG.4B shows representative UV-Vis spectra of leachates at various temperatures.

[0012] FIG.4C shows representative FTIR spectra of leachates at various temperatures.

[0013] FIG. 4D shows representative FTIR spectra of grass leaves before and after microwave-assisted leaching.

[0014] FIGS.5A-5K show representative SEM images of NCM black mass (FIGS.5A-5B) and corresponding EDS mappings (FIGS.5C-5G) and EDS analyses (FIGS.5H-5K).

[0015] FIGS.6A-5H show a representative SEM image of leaching residue treated under a 120 ºC microwave-assisted leaching process (FIG.6A) and corresponding EDS mappings (FIGS.6B-6F) and EDS analyses (FIGS.6G-6H).

[0016] FIGS.7A-7D show a representative SEM image of leaching residue treated under aATTORNEY DOCKET NO.222204-2800 180 ºC microwave-assisted leaching process (FIG.6A) and corresponding EDS mappings (FIGS.7B-7C) and EDS analysis (FIGS.7D).

[0017] FIGS.8A-8D show representative XPS spectra for NCM black mass and leaching residue treated under 120 ºC microwave-assisted leaching process for a survey scan (FIG. 8A), Mn 2p (FIG.8B), Co 2p (FIG.8C), and Ni 2p (FIG.8D).

[0018] Additional advantages of the disclosure will be set forth in part in the description which follows, and in part will be obvious from the description, or can be learned by practice of the disclosure. The advantages of the disclosure will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure, as claimed. DETAILED DESCRIPTION

[0019] Many modifications and other aspects disclosed herein will come to mind to one skilled in the art to which the disclosed compositions and methods pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the disclosures are not to be limited to the specific aspects disclosed and that modifications and other aspects are intended to be included within the scope of the appended claims. The skilled artisan will recognize many variants and adaptations of the aspects described herein. These variants and adaptations are intended to be included in the teachings of this disclosure and to be encompassed by the claims herein.

[0020] Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

[0021] As will be apparent to those of skill in the art upon reading this disclosure, each of the individual aspects described and illustrated herein has discrete components and features which may be readily separated from or combined with the features of any of the other several aspects without departing from the scope or spirit of the present disclosure.

[0022] Any recited method can be carried out in the order of events recited or in any other order that is logically possible. That is, unless otherwise expressly stated, it is in no way intended that any method or aspect set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not specifically state in the claims or descriptions that the steps are to be limited to a specific order, it is no way intended that an order be inferred, in any respect. This holds for any possible non-express basis for interpretation, including matters of logic with respect to arrangement of steps or operational flow, plain meaning derived from grammatical organization or punctuation, or the number or type of aspects described in the specification.

[0023] All publications mentioned herein are incorporated herein by reference to disclose and describe the methods and / or materials in connection with which the publications are cited.ATTORNEY DOCKET NO.222204-2800 The publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present disclosure is not entitled to antedate such publication by virtue of prior disclosure. Further, the dates of publication provided herein can be different from the actual publication dates, which can require independent confirmation.

[0024] While aspects of the present disclosure can be described and claimed in a particular statutory class, such as the system statutory class, this is for convenience only and one of skill in the art will understand that each aspect of the present disclosure can be described and claimed in any statutory class.

[0025] It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the disclosed compositions and methods belong. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the specification and relevant art and should not be interpreted in an idealized or overly formal sense unless expressly defined herein.

[0026] Prior to describing the various aspects of the present disclosure, the following definitions are provided and should be used unless otherwise indicated. Additional terms may be defined elsewhere in the present disclosure. A. DEFINITIONS

[0027] As used herein, “comprising” is to be interpreted as specifying the presence of the stated features, integers, steps, or components as referred to, but does not preclude the presence or addition of one or more features, integers, steps, or components, or groups thereof. Moreover, each of the terms “by”, “comprising,” “comprises”, “comprised of,” “including,” “includes,” “included,” “involving,” “involves,” “involved,” and “such as” are used in their open, non-limiting sense and may be used interchangeably. Further, the term “comprising” is intended to include examples and aspects encompassed by the terms “consisting essentially of” and “consisting of.” Similarly, the term “consisting essentially of” is intended to include examples encompassed by the term “consisting of.

[0028] As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items. Expressions such as “at least one of,” when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list.

[0029] As used herein, nomenclature for compounds, including organic compounds, can be given using common names, IUPAC, IUBMB, or CAS recommendations for nomenclature. When one or more stereochemical features are present, Cahn-Ingold-Prelog rules forATTORNEY DOCKET NO.222204-2800 stereochemistry can be employed to designate stereochemical priority, E / Z specification, and the like. One of skill in the art can readily ascertain the structure of a compound if given a name, either by systemic reduction of the compound structure using naming conventions, or by commercially available software, such as CHEMDRAWTM(Cambridgesoft Corporation, U.S.A.).

[0030] Reference to "a" chemical compound refers to one or more molecules of the chemical compound rather than being limited to a single molecule of the chemical compound. Furthermore, the one or more molecules may or may not be identical, so long as they fall under the category of the chemical compound. Thus, for example, "a" chemical compound is interpreted to include one or more molecules of the chemical, where the molecules may or may not be identical (e.g., different isotopic ratios, enantiomers, and the like).

[0031] As used in the specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a reducing sugar,” “a leaching agent” or “a metal,” includes, but is not limited to, two or more such reducing sugars, leaching agents, or metals, and the like.

[0032] It should be noted that ratios, concentrations, amounts, and other numerical data can be expressed herein in a range format. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. It is also understood that there are a number of values disclosed herein, and that each value is also herein disclosed as “about” that particular value in addition to the value itself. For example, if the value “10” is disclosed, then “about 10” is also disclosed. Ranges can be expressed herein as from “about” one particular value, and / or to “about” another particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms a further aspect. For example, if the value “about 10” is disclosed, then “10” is also disclosed.

[0033] When a range is expressed, a further aspect includes from the one particular value and / or to the other particular value. For example, where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the disclosure, e.g. the phrase “x to y” includes the range from ‘x’ to ‘y’ as well as the range greater than ‘x’ and less than ‘y’. The range can also be expressed as an upper limit, e.g. ‘about x, y, z, or less’ and should be interpreted to include the specific ranges of ‘about x’, ‘about y’, and ‘about z’ as well as the ranges of ‘less than x’, less than y’, and ‘less than z’. Likewise, the phrase ‘about x, y, z, or greater’ should be interpreted to include the specific ranges of ‘about x’, ‘about y’, and ‘about z’ as well as the ranges of ‘greater than x’, greater than y’, and ‘greater than z’. In addition, the phrase “about ‘x’ to ‘y’”, where ‘x’ and ‘y’ are numerical values, includes “about ‘x’ to about ‘y’”.

[0034] It is to be understood that such a range format is used for convenience and brevity, and thus, should be interpreted in a flexible manner to include not only the numerical valuesATTORNEY DOCKET NO.222204-2800 explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. To illustrate, a numerical range of “about 0.1% to 5%” should be interpreted to include not only the explicitly recited values of about 0.1% to about 5%, but also include individual values (e.g., about 1%, about 2%, about 3%, and about 4%) and the sub-ranges (e.g., about 0.5% to about 1.1%; about 5% to about 2.4%; about 0.5% to about 3.2%, and about 0.5% to about 4.4%, and other possible sub-ranges) within the indicated range.

[0035] As used herein, the terms “about,” “approximate,” “at or about,” and “substantially” mean that the amount or value in question can be the exact value or a value that provides equivalent results or effects as recited in the claims or taught herein. That is, it is understood that amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but may be approximate and / or larger or smaller, as desired, reflecting tolerances, conversion factors, rounding off, measurement error and the like, and other factors known to those of skill in the art such that equivalent results or effects are obtained. In some circumstances, the value that provides equivalent results or effects cannot be reasonably determined. In such cases, it is generally understood, as used herein, that “about” and “at or about” mean the nominal value indicated ±10% variation unless otherwise indicated or inferred. In general, an amount, size, formulation, parameter or other quantity or characteristic is “about,” “approximate,” or “at or about” whether or not expressly stated to be such. It is understood that where “about,” “approximate,” or “at or about” is used before a quantitative value, the parameter also includes the specific quantitative value itself, unless specifically stated otherwise.

[0036] The term “alkyl” as used herein is a branched or unbranched saturated hydrocarbon group of 1 to 24 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s- butyl, t-butyl, n-pentyl, isopentyl, s-pentyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, tetradecyl, hexadecyl, eicosyl, tetracosyl, and the like. The alkyl group can be cyclic or acyclic. The alkyl group can be branched or unbranched. The alkyl group can also be substituted or unsubstituted. For example, the alkyl group can be substituted with one or more groups including, but not limited to, alkyl, cycloalkyl, alkoxy, amino, ether, halide, hydroxy, nitro, silyl, sulfo-oxo, or thiol, as described herein. A “lower alkyl” group is an alkyl group containing from one to six (e.g., from one to four) carbon atoms. The term alkyl group can also be a C1 alkyl, C1-C2 alkyl, C1-C3 alkyl, C1-C4 alkyl, C1-C5 alkyl, C1-C6 alkyl, C1-C7 alkyl, C1-C8 alkyl, C1- C9 alkyl, C1-C10 alkyl, and the like up to and including a C1-C24 alkyl. When “alkyl” is used in one instance and a specific term such as “hydroxyalkyl” is used in another, it is not meant to imply that the term “alkyl” does not also refer to specific terms such as “hydroxyalkyl” and the like.

[0037] The term “alkenyl” as used herein is a hydrocarbon group of from 2 to 24 carbon atoms with a structural formula containing at least one carbon-carbon double bond.ATTORNEY DOCKET NO.222204-2800 Asymmetric structures such as (A1A2)C=C(A3A4) are intended to include both the E and Z isomers. This can be presumed in structural formulae herein wherein an asymmetric alkene is present, or it can be explicitly indicated by the bond symbol C=C. The alkenyl group can be substituted with one or more groups including, but not limited to, alkyl, cycloalkyl, alkoxy, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl, aryl, heteroaryl, aldehyde, amino, carboxylic acid, ester, ether, halide, hydroxy, ketone, azide, nitro, silyl, sulfo-oxo, or thiol, as described herein.

[0038] As used herein, the term “phenolic acid” refers to a compound containing a phenol group substituted with a carboxyl group having the formula ─C(O)(OH) or ─A1C(O)(OH). A1can be an alkyl or alkenyl group as described herein. Examples of phenolic acids include, but are not limited to, protocatechuic acid, vanillic acid, p-coumaric acid, chlorogenic acid (5- caffeoylquinic acid), 4-hydroxybenzaldehyde, 3,4-hydroxybenzoic acid, cinnamic acid, gallic acid, isorhamnetin, quercetin, p-hydroxybenzoic acid, vanillic acid, caffeic acid, p-coumaric acid, ferulic acid, syringic acid, and sinapinic acid.

[0039] As used herein, the term “phenol group” refers to a phenyl group substituted with at least one hydroxyl group. The phenol group can be further substituted with one or more groups including, but not limited to, alkyl, cycloalkyl, alkoxy, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl, aryl, heteroaryl, aldehyde, amino, carboxylic acid, ester, ether, halide, hydroxy, ketone, azide, nitro, silyl, sulfo-oxo, or thiol, as described herein.

[0040] As used herein, the terms “optional” or “optionally” means that the subsequently described event or circumstance can or cannot occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.

[0041] As used herein, “black mass” refers to the concentrated, dark-colored residue obtained after the mechanical and chemical processing or treatment of spent batteries such as LIBs. Mechanical and chemical processing can include the discharge, disassembly, calcination, peeling processes, and any combination thereof of spent batteries. Black mass can comprise a mixture of metals and compounds.

[0042] The term “critical material”, as used herein, refer to any non-fuel mineral, element, substance, or material that is determined to have a high risk of supply chain disruption and serves an essential function in one or more energy technologies, including technologies that produce, transmit, store, and conserve energy. Critical materials for energy include aluminum, cobalt, copper, dysprosium, electrical steel, fluorine, gallium, iridium, lithium, magnesium, natural graphite, neodymium, nickel, platinum, praseodymium, silicon, silicon carbide and terbium. Critical materials can also refer to critical minerals.

[0043] The term “critical mineral”, as used herein, is a subset of critical materials, including any mineral, element, substance, or material designated as critical by the Secretary of the Interior, acting through the director of the U.S. Geological Survey. Critical minerals include, but are not limited to, aluminum, cobalt, lithium, manganese, nickel, titanium, vanadium, and zinc.ATTORNEY DOCKET NO.222204-2800

[0044] As used herein, the term “biomass” or “biomass feedstock” refers to any organic material that is obtained from plant or animal sources. Sources of biomass include, but are not limited to, wood and wood processing waste (e.g., firewood, wood pellets, wood chips, lumber and furniture mill sawdust and waste, black liquor from pulp and paper mills); agricultural crops and waste materials (e.g., corn, soybeans, sugar cane, switchgrass, woody plants, algae, crop and food processing residues); and biogenic materials in municipal solid waste (e.g., paper products, cotton products, wool products, food wastes, yard wastes, wood wastes). B. ABBREVIATIONS

[0045] EDS energy-dispersive X-ray spectroscopy

[0046] FTIR Fourier transform infrared spectroscopy

[0047] LIBs lithium-ion batteries

[0048] NCM LiNixCoyMnzO2

[0049] SEM scanning electron microscope

[0050] XPS X-ray photoelectron spectroscopy

[0051] XRD X-ray diffraction C. INTRODUCTION

[0052] Management and sustainable recycling of spent batteries, such as LIBs, is important from economic and environmental standpoints. Three major methods, pyrometallurgy, biometallurgy, and hydrometallurgy, are applied to recover valuable metals from spent batteries. Compared to pyrometallurgy and biometallurgy, the hydrometallurgical process has lower energy consumption, more straightforward operation, and higher recovery / leaching efficiency. Conventional hydrometallurgy extensively utilizes a combination of strong inorganic acids, such as H2SO4, HCl, and HNO3, along with reductants (e.g., H2O2) to extract metals from spent batteries. While conventional hydrometallurgy methods are efficient at extracting metals, the methods and materials used can result in high operational costs and safety concerns, especially at larger scales. Alternatively, organic acids, antibiotic bacteria residues, and biomass wastes can be used as environmentally friendly and bioavailable reductants for efficient recovery of metals from spent batteries. However, these materials often do not achieve leaching efficiencies on par with inorganic reductants.

[0053] In one aspect, the disclosure relates to methods for the recovery of critical materials from spent batteries. The method can comprise combining a sample of black mass and a loading solvent, thereby forming a first mixture; heating the first mixture at a pressure above standard pressure (i.e., 1 atm), thereby forming a treated mixture comprising a solid residue and an aqueous solution; and separating the solid residue from the aqueous solution. The methods disclosed herein can be characterized by requiring less leaching agent (e.g., acid) in order to recover critical materials, a reduced heating time, and an enhanced recoveryATTORNEY DOCKET NO.222204-2800 efficiency compared to other hydrometallurgy methods using organic or biomass reducing agents and leaching agents. For the methods disclosed herein, the recovery or leaching efficiency of critical materials from the black mass of spent batteries can range from about 85% to about 99%, about 90% to about 99%, or about 95% to about 99%. In a further aspect, the methods disclosed herein can comprise heating the first mixture by exposing it to microwave radiation. D. METHOD FOR RECOVERING CRITICAL MATERIALS

[0054] In one aspect, the disclosure relates to a method comprising combining a sample of black mass (comprising at least one critical material) and a loading solvent, thereby forming a first mixture; heating the first mixture at a pressure of about 150 psi to about 600 psi, thereby forming a treated mixture comprising a solid residue and an aqueous solution; and separating the solid residue from the aqueous solution; wherein the loading solvent comprises at least one leaching agent and at least one reducing agent, wherein the reducing agent comprises a biomass feedstock; and wherein the treated mixture comprises at least one critical material. In a further aspect, the black mass and the loading solvent can be combined and stirred (e.g., via mechanical stirring). In a further aspect, the critical material present in the black mass can be lithium, manganese, cobalt, nickel, iron, copper, or any combination thereof. In another aspect, the critical material present in the treated mixture can be lithium, manganese, cobalt, nickel, or any combination thereof. In one aspect, the aqueous solution of the treated mixture can contain the majority of the critical material(s) present in the treated mixture. In a further aspect, the aqueous solution can comprise from about 85% to about 99%, about 90% to about 99%, about 95% to about 99%, 90% to 99%, 93% to 99%, 95% to 99%, or 97% to 99% of the at least one critical material present in the treated mixture.

[0055] The sample of black mass can be obtained from LIB waste. For example, in one aspect, the sample of black mass can comprise NCM black mass. Spent batteries can undergo various mechanical and chemical processing in order to form black mass. For example, a spent battery can be fully discharged. A spent battery can also undergo mechanical processing such as shredding or crushing to break the battery down into smaller pieces. During the process, some valuable materials, such as copper and aluminum foils, can be separated from the remaining black mass. After preparing the sample of black mass, the black mass can be combined with a loading solvent to form a first mixture. The concentration of the sample of black mass in the first mixture can be from about 5 g / L to about 200 g / L, about 5 g / L to about 200 g / L, about 10 g / L to about 200 g / L, about 10 g / L to about 150 g / L, about 10 g / L to about 100 g / L, about 10 g / L to about 50 g / L, about 10 g / L to about 40 g / L, about 10 g / L to about 30 g / L, about 10 g / L to about 20 g / L, about 20 g / L to about 40 g / L, or about 20 g / L to about 30 g / L. In a further aspect, when the method comprises stirring the sample of black mass and the loading solvent, the concentration of the sample of black mass in the first mixtureATTORNEY DOCKET NO.222204-2800 can be from about 5 g / L to about 200 g / L, about 5 g / L to about 200 g / L, about 10 g / L to about 200 g / L, about 10 g / L to about 150 g / L, or about 10 g / L to about 100 g / L. In another further aspect, when the method does not comprise stirring the sample of black mass and the loading solvent, the concentration of the sample of black mass in the first mixture can be from about 10 g / L to about 50 g / L, about 10 g / L to about 40 g / L, about 10 g / L to about 30 g / L, about 10 g / L to about 20 g / L, about 20 g / L to about 40 g / L, or about 20 g / L to about 30 g / L.

[0056] In one aspect, the loading solvent can include at least one leaching agent and at least one reducing agent. The reducing agent can include, for example, a biomass feedstock (e.g., agricultural crops and waste materials and food wastes). The biomass feedstock can include biomass from any source including, for example, wood and wood processing waste (e.g., wood pellets, wood chips, lumber and furniture mill sawdust and waste); agricultural crops and waste materials (e.g., switchgrass, algae, crop and food processing residues); biogenic materials in municipal solid waste (e.g., food wastes, yard wastes, wood wastes); animal- based materials; and any combination thereof. In one aspect, the biomass feedstock can include agricultural or yard wastes, such as grass leaves, and / or food wastes (e.g., fruit peel waste). The biomass feedstock can undergo pretreatment prior to its use in the disclosed methods. For example, the biomass feedstock can be ground to reduce the particle size or an average particle size of the biomass feedstock. In one aspect, the particle size or average particle size of the biomass feedstock can be less than 300 µm. The concentration of the biomass feedstock in the first mixture can be from about 0.1 g / g to about 1.0 g / g, about 0.1 g / g to about 0.8 g / g, about 0.3 g / g to about 1.0 g / g, about 0.3 g / g to about 0.8 g / g, about 0.5 g / g to about 1.0 g / g, or about 0.5 g / g to about 0.8 g / g, wherein the concentration is measured as grams of biomass feedstock per grams of black mass.

[0057] The leaching agent can be an acid, such as a mineral acid (inorganic acid), an organic acid, or any combination thereof. In a further aspect, the leaching agent can be an acid selected from hydrochloric acid, nitric acid, sulfuric acid, citric acid, ascorbic acid, malic acid, tartaric acid, malonic acid, maleic acid, fumaric acid, and any combination thereof, and the like. In one aspect, the concentration of acid in the first mixture can be from about 0.05 mol / L to about 0.50 mol / L, about 0.05 mol / L to about 0.40 mol / L, about 0.05 mol / L to about 0.30 mol / L, about 0.05 mol / L to about 0.20 mol / L, about 0.10 mol / L to about 0.40 mol / L, about 0.10 mol / L to about 0.30 mol / L, about 0.10 mol / L to about 0.20 mol / L, about 0.15 mol / L to about 0.40 mol / L, about 0.15 mol / L to about 0.30 mol / L, or about 0.15 mol / L to about 0.20 mol / L. In another aspect, the concentration of acid in the first mixture can be such that the pH of the first mixture is from about 1 to about 6, about 1 to about 5, about 1 to about 4, about 1 to about 3, or about 1 to about 2.

[0058] In one aspect, the black mass and loading solvent can be combined together in a reaction vessel. The reaction vessel can be a pressurized reaction vessel, allowing for the loading solvent and black mass to mix under an elevated pressure. The reaction vessel canATTORNEY DOCKET NO.222204-2800 be heated by a variety of methods, such as using internal pipe coils or an external jacket in combination with a heated fluid. In another aspect, the first mixture can be heated using microwave irradiation. In another aspect, when the first mixture is to be heated by exposure to microwave radiation, the reaction vessel can be a microwave reactor. In a further aspect, when heating the first mixture by microwave irradiation, the microwave power used can be from about 500 Watts to about 1000 Watts, about 700 Watts to about 1000 Watts, or about 800 Watts to about 900 Watts. The first mixture can be heated to a reaction temperature of about 100 °C to about 200 °C, about 120 °C to about 200 °C, about 140 °C to about 200 °C, about 160 °C to about 200 °C, or about 180 °C to about 200 °C. In another aspect, the first mixture can be heated at a rate of about 10 °C / min to about 50 °C / min, about 10 °C / min to about 30 °C / min, about 15 °C / min to about 30 °C / min, or about 10 °C / min to about 15 °C / min until the reaction temperature is reached. The first mixture can be heated for about 10 minutes to about 60 minutes, about 10 minutes to about 45 minutes, about 10 minutes to about 30 minutes, about 15 minutes to about 60 minutes, about 15 minutes to about 45 minutes, about 15 minutes to about 30 minutes, about 20 minutes to about 60 minutes, about 20 minutes to about 45 minutes, or about 20 minutes to about 30 minutes. The first mixture can be heated at a pressure of about 150 psi to about 600 psi, about 150 psi to about 300 psi, or about 300 psi to about 600 psi.

[0059] In one aspect, heating the first mixture forms a treated mixture comprising a solid residue and an aqueous solution. The solid residue and aqueous solution can be separated by methods such as filtering or centrifugation. For example, the treated mixture can be centrifuged for at least about 5 minutes at about 5000 rpm. The treated mixture can further comprise a reducing compound, such as a sugar, a phenolic acid, or a combination thereof. The sugar can include a monosaccharide, a disaccharide, or any combination thereof. In a further aspect, the sugar can include glucose, fructose, sucrose, or any combination thereof. The phenolic acid can include compounds such as protocatechuic acid, vanillic acid, p- coumaric acid, chlorogenic acid (5-caffeoylquinic acid), 4-hydroxybenzaldehyde, 3,4- hydroxybenzoic acid, cinnamic acid, gallic acid, isorhamnetin, quercetin, p-hydroxybenzoic acid, vanillic acid, caffeic acid, p-coumaric acid, ferulic acid, syringic acid, sinapinic acid, or any combination thereof. In another aspect, the treated mixture can include molasses. E. ASPECTS

[0060] The following listing of exemplary aspects supports and is supported by the disclosure provided herein.

[0061] Aspect 1. A method comprising combining a sample of black mass and a loading solvent, thereby forming a first mixture; heating the first mixture at a pressure of about 150 psi to about 600 psi, thereby forming a treated mixture comprising a solid residue and an aqueous solution; and separating the solid residue from the aqueous solution; wherein the sample ofATTORNEY DOCKET NO.222204-2800 black mass comprises at least one critical material; wherein the loading solvent comprises at least one leaching agent and at least one reducing agent, wherein the reducing agent comprises a biomass feedstock ; and wherein the treated mixture comprises at least one critical material.

[0062] Aspect 2. The method of aspect 1, wherein heating the first mixture comprises exposing the first mixture to microwave radiation.

[0063] Aspect 3. The method of aspect 2, wherein the first mixture is exposed to microwave radiation at a power of about 500 Watts to about 1000 Watts.

[0064] Aspect 4. The method of aspect 2, wherein the first mixture is exposed to microwave radiation at a power of about 700 Watts to about 1000 Watts.

[0065] Aspect 5. The method of aspect 2, wherein the first mixture is exposed to microwave radiation at a power of about 800 Watts to about 900 Watts.

[0066] Aspect 6. The method of any one of aspects 1-5, wherein combining the sample of black mass and the loading solvent further comprises stirring.

[0067] Aspect 7. The method of any one of aspects 1-5, wherein the sample of black mass is lithium-ion battery black mass.

[0068] Aspect 8. The method of any one of aspects 1-7, wherein the treated mixture further comprises a reducing compound selected from a sugar, a phenolic acid, and any combination thereof.

[0069] Aspect 9. The method of aspect 8, wherein the sugar is selected from a monosaccharide, a disaccharide, and a combination thereof.

[0070] Aspect 10. The method of aspect 8 or aspect 9, wherein the sugar is selected from glucose, fructose, sucrose, and any combination thereof.

[0071] Aspect 11. The method of aspect 8, wherein the phenolic acid is selected from protocatechuic acid, vanillic acid, p-coumaric acid, chlorogenic acid (5-caffeoylquinic acid), 4- hydroxybenzaldehyde, 3,4-hydroxybenzoic acid, cinnamic acid, gallic acid, isorhamnetin, quercetin, p-hydroxybenzoic acid, vanillic acid, caffeic acid, p-coumaric acid, ferulic acid, syringic acid, sinapinic acid, and any combination thereof.

[0072] Aspect 12. The method of any one of aspects 1-7, wherein the treated mixture further comprises molasses.

[0073] Aspect 13. The method of any one of aspects 1-12, wherein the first mixture is heated to a reaction temperature of about 100 °C to about 200 °C.

[0074] Aspect 14. The method of any one of aspects 1-12, wherein the first mixture is heated to a reaction temperature of about 160 °C to about 200 °C.

[0075] Aspect 15. The method of any one of aspects 1-12, wherein the first mixture is heated to a reaction temperature of about 180 °C to about 200 °C.

[0076] Aspect 16. The method of any one of aspects 1-15, wherein the first mixture is heated at a rate of about 10 °C / min to about 50 °C / min until the reaction temperature is reached.ATTORNEY DOCKET NO.222204-2800

[0077] Aspect 17. The method of any one of aspects 1-15, wherein the first mixture is heated at a rate of about 10 °C / min to about 30 °C / min until the reaction temperature is reached.

[0078] Aspect 18. The method of any one of aspects 1-17, wherein the first mixture is heated for about 10 minutes to about 60 minutes.

[0079] Aspect 19. The method of any one of aspects 1-17, wherein the first mixture is heated for about 15 minutes to about 45 minutes.

[0080] Aspect 20. The method of any one of aspects 1-17, wherein the first mixture is heated for about 20 minutes to about 30 minutes.

[0081] Aspect 21. The method of any one of aspects 1-20, wherein the first mixture is heated at a pressure of about 150 psi to about 300 psi.

[0082] Aspect 22. The method of any one of aspects 1-21, wherein the leaching agent comprises an acid.

[0083] Aspect 23. The method of aspect 22, wherein the acid is selected from a mineral acid, an organic acid, and a combination thereof.

[0084] Aspect 24. The method of aspect 22, wherein the acid is selected from hydrochloric acid, nitric acid, sulfuric acid, citric acid, ascorbic acid, malic acid, tartaric acid, malonic acid, maleic acid, fumaric acid, and any combination thereof.

[0085] Aspect 25. The method of aspect 22, wherein the acid comprises sulfuric acid.

[0086] Aspect 26. The method of any one of aspects 22-25, wherein a concentration of the acid in the first mixture is such that the pH of the first mixture is from about 1 to about 6.

[0087] Aspect 27. The method of any one of aspects 22-25, wherein a concentration of the acid in the first mixture is such that the pH of the first mixture is from about 1 to about 4.

[0088] Aspect 28. The method of any one of aspects 22-25, wherein a concentration of the acid in the first mixture is such that the pH of the first mixture is from about 1 to about 2.

[0089] Aspect 29. The method of any one of aspects 22-25, wherein a concentration of the acid in the first mixture is from about 0.05 mol / L to about 0.50 mol / L.

[0090] Aspect 30. The method of any one of aspects 22-25, wherein a concentration of the acid in the first mixture is from about 0.05 mol / L to about 0.30 mol / L.

[0091] Aspect 31. The method of any one of aspects 22-25, wherein a concentration of the acid in the first mixture is from about 0.15 mol / L to about 0.20 mol / L.

[0092] Aspect 32. The method of any one of aspects 1-31, wherein a concentration of the sample of black mass in the first mixture is from about 10 g / L to about 200 g / L.

[0093] Aspect 33. The method of any one of aspects 1-31, wherein a concentration of the sample of black mass in the first mixture is from about 10 g / L to about 100 g / L.

[0094] Aspect 34. The method of any one of aspects 1-31, wherein a concentration of the sample of black mass in the first mixture is from about 10 g / L to about 30 g / L.

[0095] Aspect 35. The method of any one of aspects 1-34, wherein a concentration of the biomass feedstock in the first mixture is from about 0.1 g biomass feedstock / g black mass toATTORNEY DOCKET NO.222204-2800 about 1.0 g biomass feedstock / g black mass.

[0096] Aspect 36. The method of any one of aspects 1-34, wherein a concentration of the biomass feedstock in the first mixture is from about 0.3 g / g to about 0.8 g / g.

[0097] Aspect 37. The method of any one of aspects 1-34, wherein a concentration of the biomass feedstock in the first mixture is from about 0.5 g / g to about 0.8 g / g.

[0098] Aspect 38. The method of any one of aspects 1-37, wherein the biomass feedstock comprises grass leaves, food wastes, or a combination thereof.

[0099] Aspect 39. The method of any one of aspects 1-38, wherein the biomass feedstock comprises particles with an average particle size of less than about 300 µm.

[0100] Aspect 40. The method of any one of aspects 1-39, wherein the sample of black mass comprises at least one critical material selected from lithium, manganese, cobalt, nickel, iron, copper, and any combination thereof.

[0101] Aspect 41. The method of any one of aspects 1-40, wherein the treated mixture comprises at least one critical material selected from lithium, manganese, cobalt, nickel, and any combination thereof.

[0102] Aspect 42. The method of any one of aspects 1-41, wherein the aqueous solution comprises from about 85% to about 99% of the at least one critical material present in the treated mixture.

[0103] Aspect 43. The method of any one of aspects 1-41, wherein the aqueous solution comprises from about 90% to about 99% of the at least one critical material present in the treated mixture.

[0104] Aspect 44. The method of any one of aspects 1-41, wherein the aqueous solution comprises from about 95% to about 99% of the at least one critical material present in the treated mixture.

[0105] Aspect 45. The method of any one of aspects 1-44, wherein the solid residue is separated from the aqueous solution by centrifugation.

[0106] From the foregoing, it will be seen that aspects herein are well adapted to attain all the ends and objects hereinabove set forth together with other advantages which are obvious and which are inherent to the structure.

[0107] While specific elements and steps are discussed in connection to one another, it is understood that any element and / or step provided herein is contemplated as being combinable with any other elements and / or steps regardless of explicit provision of the same while still being within the scope provided herein.

[0108] It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

[0109] Since many possible aspects may be made without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawingsATTORNEY DOCKET NO.222204-2800 and detailed description is to be interpreted as illustrative and not in a limiting sense.

[0110] It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only, and is not intended to be limiting. The skilled artisan will recognize many variants and adaptations of the aspects described herein. These variants and adaptations are intended to be included in the teachings of this disclosure and to be encompassed by the claims herein.

[0111] Now having described the aspects of the present disclosure, in general, the following Examples describe some additional aspects of the present disclosure. While aspects of the present disclosure are described in connection with the following examples and the corresponding text and figures, there is no intent to limit aspects of the present disclosure to this description. On the contrary, the intent is to cover all alternatives, modifications, and equivalents included within the spirit and scope of the present disclosure. F. EXAMPLES

[0112] The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how the compounds, compositions, articles, devices and / or methods claimed herein are made and evaluated, and are intended to be purely exemplary of the disclosure and are not intended to limit the scope of what the inventors regard as their disclosure. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperature, etc.), but some errors and deviations should be accounted for. Unless indicated otherwise, parts are parts by weight, temperature is in ^C or is at ambient temperature, and pressure is at or near atmospheric. 1. LIB RECYCLING USING WASTE BIOMASS AS A REDUCTANT

[0113] Current methods to recycle spent NCM batteries include pyrometallurgy, biometallurgy, and hydrometallurgy. The advantages and disadvantages of the three methods are listed in Table 1. Hydrometallurgy was considered an effective way to recycle spent NCM batteries due to its lower energy consumption compared to pyrometallurgy and the absence of a requirement to consider microbial growth kinetics, which is a critical factor in biometallurgy.ATTORNEY DOCKET NO.222204-2800 Table 1. Advantages and disadvantages of spent NCM recycling methods (Su et al.2022; Wu et al.2020). Pyrometallurgy Biometallurgy Hydrometallurgy Low energy Low energy Low requirements consumption, high consumption, high for raw materials, a metal recovery metal recovery Advantages short operation efficiency, and less efficiency, high process, and less environmental and product purity, and liquid waste. health impacts. easy operation. Energy-intensive, Long microbial culture high production cycle, rigorous growing cost, high- Toxic gas Disadvantages environment temperature risk, generation. requirements, and slow and heavy air production process. pollution.

[0114] In this example (Example 1), microwave-assisted leaching was employed for spent NCM recycling owing to its advantages of decreased solvent (acid) usage, reduced heating time, and enhanced recovery yields (Lie and Liu 2021). In addition, grass leaves that have been widely used for the sustainable production of bioenergy in biorefineries were proposed as a new biomass-reducing agent (Bedoić et al. 2019). The effect of reductant dosage, temperature, H2SO4concentration, solid concentration, and reaction time was systematically investigated, as well as the microwave-assisted leaching behavior of valuable elements, including Li, Mn, Co, and Ni, were analyzed by kinetic studies. Studies concerning the performance of organic reductants in the recovery of metals from the NCM black mass are shown in Table 2.

[0115] It is observed that the majority of organic reductants listed in Table 2 do not achieve leaching efficiencies of valuable elements to exceed 99%, which not only results in the consumption of excess reducing agents but also contributes to the loss of valuable metals. Lei et al. and Gu et al. obtained over 99% recovery of valuable elements with high acid consumption and hard operating conditions that exerted a negative influence on the environment. Table 2. Selected works on the performance of organic reductants in the recovery of metals from the NCM black mass. Sample Conditions Leaching agent Reductant Leaching Efficiency Ref. LiNixCoyMn1-x-yO290 ºC, 120 16% glucose 99.54% Li, (Lei et al. min, and 12 3 mol / L H2SO4dosage 99.84% Ni, 2023)ATTORNEY DOCKET NO.222204-2800 mL / g liquid- 99.58% Co, solid ratio. and 99.1% Mn. 80 ºC, 30 0.3g / g Around 95% LiNi1 / 3Co1 / 3Mn1 / 3O2min, and 20 0.3 mol / L DL- (Sidiq et al. g / L solid- malic acid glucose of Li, Mn, 2022) dosage Co, and Ni. liquid ratio. 99.98% Li, 65 ºC, 60 1 g / g 99.94% Ni, min, and (Gu, Gu, et LiNiCoMnO 2 mol / L H SO glutathione 99.97% Co,x y z 2 2 410:1 liquid- al.2023) dosage and 99.91% solid ratio. Mn. 90 ºC, 120 About 1 g / g waste min, and 20 99.9% of Li, (Su et al. LiNiCoMnO 3 mol / L H SO arecax y z 2 2 4 mL / g liquid- Ni, Co, and 2022) powder solid ratio. Mn. 80.5% Li,min, and 20 85% Mn, (Okonkwo et LiNi Co Mn O methanesulfonic sugar-based0.5 0.2 0.3 2mL / g liquid- 88% Ni, and al.2024) acid reductants solid ratio. 88% Co.

[0116] Materials and Reagents. Black mass from spent NCM batteries was provided by a battery recycling company in the USA. Pretreatment of spent NCM batteries, encompassing discharge, disassembly, calcination, as well as peeling processes, resulted in the obtainment of the NCM black mass. Table 3 shows the main elemental concentrations of the NCM black mass analyzed after being dissolved in aqua regia (V :V = 1:3). Grass leaves utilized inHNO3 HClthis study were cultivated and harvested following a methodology detailed in (Li, Ji, and Zhang 2024). The grass leaves were dried, subsequently ground to a particle size of less than 297 µm, and preserved as feedstock for the following experiments. The chemical reagent of sulfuric acid (H SO , 93 wt.% to 98 wt.% concentration, trace metal grade) is of analytical2 4grade and produced by Thermo Fisher Scientific, USA. All aqueous solutions used in the study are prepared with deionized water (resistivity ≥ 18.2 MΩ^cm). Table 3. Elemental concentrations (mg / g) of the NCM black mass. Li Mn Co Ni Fe Cu 33.7 84.4 83.8 120.1 14.7 15.6

[0117] Experiments. All leaching experiments were carried out in a microwave reactor (Multiwave GO Plus, Anton Paar GmbH, Austria). Grass leaves, 10 mL of acid solution, and 0.2 g of the NCM black mass were added to a reaction vessel. The heating rate wasATTORNEY DOCKET NO.222204-2800 maintained at 10 ºC / min. After a specific reaction time, the leaching residue and leachate were separated by centrifugation at 5000 rpm for 5 min. The leaching residue was washed with deionized water as well as dried at 80 ºC for 24 h (Li and Zhang 2024). Each experiment was conducted in triplicate, and the mean outcomes were reported. Variability in the experimental data was denoted by error bars accompanying the results.

[0118] Analysis and Characterization. Elemental concentration analysis in solutions was conducted by an inductively coupled plasma emission mass spectrometer (ICP-MS, Thermo Electron iCAP-RQ, Thermo Scientific, USA). The crystal structures of solid samples were characterized by X-ray diffraction (XRD D8 ADVANCE, Bruker, Germany). The morphology and compositions of materials were carried out on a scanning electron microscope (SEM, JSM-IT500, JEOL LTD, Japan) equipped with energy-dispersive X-ray spectroscopy (EDS). The surface chemistry of samples was detected by X-ray photoelectron spectroscopy (XPS, PHI Quantera SXM-03, Ulvac PHI, Japan). Qualitative analysis of components as well as functional groups and chemical bonds contained in the substances were determined by Ultraviolet-visible spectrometer (Cary 5000 UV-Vis-NIR, Agilent, United States) and Fourier Transform Infrared Spectroscopy (FTIR, Micolet Nexus 670, Thermo Fisher Scientific Company, United States). Methods and detailed parameters used in characterizations are detailed in this Example.

[0119] Analytical Methods. For XRD analysis, an X-ray tube was operated at 40 kV and 40 mA. Data acquisition covered a 2θ range from 10° to 70°, with a scanning velocity of 2° per minute. Peak analysis was conducted using MDI Jade 6.0 software, referencing the PDF-2 database provided by the International Center for Diffraction Data (ICDD). For the SEM analysis, the samples were spread on carbon tapes and sputtered with palladium / platinum (10 nm thickness) with the use of a sputter coater (208HR, Cressington Scientific Instrument, England, UK) to increase their electron conductivity. The elemental composition of the region was analyzed using EDS mapping and point mode at the accelerating voltage of 15 kV. For the XPS analysis, a scanning monochromatic X-ray source (Al-Kα=1486.7 eV) was equipped with PHI Quantera SXM. The sample was mounted on non-conductive adhesive tape and placed in the instrument for analysis. The results were analyzed by PHI Multipak V9.0 software and XPSPEAK41. For the ultraviolet-visible spectrometer (UV-Vis-NIR) analysis, the wavelength was in the range of 200 nm to 800 nm. For the FTIR analysis, the wavelength was in the range from 4000 m-1to 500 cm-1.

[0120] Reductive Microwave-assisted Leaching. The effect of various parameters, including grass leaves dosage, temperature, H2SO4concentration, solid concentration, and reaction time on the leaching efficiencies of Li, Mn, Co, and Ni from the NCM black mass during microwave-assisted leaching was investigated, and the results are presented in FIGS. 1A-1E.

[0121] Effect of grass leaves dosage. FIG.1A explores the effect of grass leaves dosageATTORNEY DOCKET NO.222204-2800 on the leaching efficiency of valuable metals from the NCM black mass under the condition of 0.2 mol / L H2SO4, temperature of 120 ºC, reaction time of 30 min, and solid concentration of 20 g / L. The experimental results demonstrated that H2SO4exhibited superior efficacy in the leaching of Li and Ni.90.5% of Li and 74.8% of Ni were leached without the addition of grass leaves. Nonetheless, the leaching efficiency of Mn and Co proved to be suboptimal in the absence of grass leaves during microwave-assisted leaching. With the increase in grass leaves dosage from 0 g / g to 0.75 g / g, the leaching efficiency of Mn and Co enhanced gradually from 42.7% and 51.0% to 62.9% to 66.0%, respectively, demonstrating that the addition of grass leaves effectively facilitated the leaching of Mn and Co from the NCM black mass. The leaching efficiency of Li and Ni increased slightly from 90.5% and 74.8% to 99.4% and 95.4%, respectively with increasing the grass leaves dosage from 0 g / g to 0.75 g / g. The layered structure of the NCM black mass was destructed following the reductive leaching of Mn and Co, thus leading to the enhancement of Li and Ni. The leaching efficiency of valuable metals decreased when the grass leaves dosage was over 0.75 g / g. As shown in FIGS. 2A-2B, compared to raw grass leaves (FIG.2A), pores (red rectangles in FIG.2B) were formed on the surface of the leaching residue obtained after microwave-assisted leaching process (Li et al. 2024). Excessive grass leaves with porous structures may absorb some metal ions, resulting in a decrease in leaching efficiency (Yan et al. 2021). In addition, the excessive addition of grass leaves elevated the resistance of particle mobility and decreased the solid- liquid contact area, which also impedes the leaching efficiency of metals (Su et al. 2022). Therefore, 0.75 g / g was selected as the tested grass leaves dosage.

[0122] Effect of temperature. Temperature plays a role in the leaching efficiency of metals. Most leaching reactions are endothermic, indicating that increased temperatures tend to promote reaction rates (Lei et al.2023). The effect of temperature on the leaching efficiency of valuable metals from the NCM black mass during the microwave-assisted leaching process was studied using 0.2 mol / L H2SO4as the leaching agent and 0.75 g / g grass leaves dosage as the reducing agent with a fixed solid concentration of 20 g / L for 30 min. As can be seen from FIG. 1B, the leaching efficiency of valuable metals enhances with the increase in temperature. When increasing the reaction temperature from 120 ºC to 180 ºC, the leaching efficiency of Mn, Co, and Ni enhanced from 58.1%, 58.5%, and 90.3%, respectively, to 99.7%, 99.5%, and 99.7%, respectively. High temperatures provided by microwaves supply additional energy for reaction molecules, resulting in heightened activation and the acceleration of chemical reaction rates (Li et al.2023; Lie and Liu 2021). Nearly 100% of Li was leached at 120 ºC, and further temperature increases exerted a negligible influence on the leaching efficiency of Li, mainly attributed to the lamellar structure of the NCM black mass and the distinct distribution patterns of valuable metals (Mn, Co, and Ni) relative to Li in the cathode materials, which facilitate the easy leaching of Li (Li et al. 2017). In order to maximize the leaching efficiency of valuable elements from the NCM black mass, the temperature wasATTORNEY DOCKET NO.222204-2800 maintained at 180 ºC.

[0123] Effect of H2SO4concentration. Variations in the pH values of solutions, prompted by changes in acid concentration, exert a substantial influence on the dissolution of metals during the leaching process (Li and Zhang 2024). The effect of H2SO4 concentration on metal recovery was studied, and the results are shown in FIG.1C. The experiments were conducted with 0.2 mol / L H2SO4and 0.75 g / g grass leaves dosage, maintaining a solid concentration of 20 g / L at 180 ºC for a duration of 30 min. The leaching efficiency of Li, Mn, Co, and Ni increased to 99.6%, 99.8%, 99.4%, and 99.4%, respectively, with increasing H2SO4concentration to 0.2 mol / L. However, further enhancement in H2SO4concentration exerted a negligible influence on the leaching efficiency of valuable elements. As can also be seen from FIG. 1C, pH values of the leaching solution decreased gradually from 5.56 to 0.93 as an increase in H2SO4from 0.05 mol / L to 0.5 mol / L. Increasing the concentration of H2SO4leads to a decrease in the pH of the leaching solution, consequently enhancing its acidity. The increased acidity significantly enhances the dissolution of valuable metals from the NCM black mass, yielding higher leaching efficiencies (Chu, Lie, and Liu 2021). However, a constant level of valuable element leaching efficiency was observed as a further increase of H2SO4concentration from 0.2 mol / L to 0.5 mol / L, attributing to the achievement of the equilibrium point of H+dissociation in this reaction system. Considering the low acid consumption and high leaching efficiency of valuable elements from the NCM black mass achieved in the microwave-assisted leaching process, H2SO4concentration was established at 0.2 mol / L for subsequent experiments.

[0124] Effect of solid concentration. Solid concentration plays a role in the leaching process, as it correlates with the stoichiometric ratio of the reactants, exerting a direct influence on the equilibrium state of the reaction (Antonijević and Bogdanović 2004; Chen et al.2020). As shown in FIG.1D, when increasing solid concentration from 10 g / L to 20 g / L, no significant alternation was found in the leaching efficiency of valuable elements. Nonetheless, as the solid concentration increased from 20 g / L to 40 g / L, the leaching efficiency of Mn, Co, and Ni decreased sharply from 98.5%, 99.7%, and 99.4%, respectively, to 39.9%, 27.8%, and 20.4%, respectively. Decreasing solid concentration enhances the solid-liquid contact area and decreases the viscosity of the solution, consequently accelerating the ion transmission rate and augmenting the leaching efficiency of valuable elements (Xie et al. 2022). Nearly 100% of Li was also leached at a high solid concentration of 40 g / L. Compared to other experimental factors, Li leaching is primarily influenced by acid conditions (Zhuang et al. 2019).0.2 mol / L H2SO4resulted in the destruction of the layered metal oxide structure in the NCM black mass, thus releasing Li+. The test solid concentration used was 20 g / L.

[0125] Effect of reaction time. Extending reaction time is evidently advantageous for enhancing the leaching efficiency of valuable metals, as a prolonged duration facilitates more complete reactions. FIG.1E displays the effect of reaction time on the leaching efficiency withATTORNEY DOCKET NO.222204-2800 0.2 mol / L H2SO4and 0.75 g / g grass leaves dosage, fixing a solid concentration of 20 g / L at 180 ºC. When the remaining conditions, including grass leaves dosage, temperature, H2SO4concentration, and solid concentration, were optimized, the change of reaction time had a minor influence on the leaching efficiency of valuable elements from the NCM black mass during microwave-assisted leaching. The leaching efficiency of Mn, Co, and Ni enhanced slightly from 81.8%, 77.3%, and 90.4%, respectively, to 99.4%, 99.7%, and 99.6%, respectively, with the increase in the reaction time from 5 min to 60 min, and almost 100% of Li was leached at 5 min. Considering maximizing the leaching efficiencies of Li, Mn, Co, and Ni from the NCM black mass, 30 min was chosen as the tested reaction time.

[0126] During the microwave-assisted leaching process, water under high pressure and temperature conditions exhibits enhanced molecular movement, diffusivity, and mass transfer, all of which contribute to the improved extraction of valuable elements (Damilos et al.2019). In the process of conventional leaching, about 99.9% of Li, Mn, Co, and Ni were recovered from the NCM black mass using 3 mol / L H2SO4at 100 ºC for 240 min (Su et al. 2022). In addition, other research using waste biomass as the reductant did not achieve over 99% of the leaching efficiency of Li, Mn, Co, and Ni. For comparison, the heating step in the microwave-assisted leaching was notably rapid, enabling completion within a brief duration of 30 min. A low acid consumption and almost 100% leaching efficiencies of valuable elements from spent NCM were obtained by employing microwave heating for the leaching process.

[0127] In conclusion, the leaching conditions to be tested were as follows: grass leaves dosage of 0.75 g / g, temperature of 180 ºC, H2SO4concentration of 0.2 mol / L, solid concentration of 20 g / L, and reaction time of 30 min. Nearly 100% leaching efficiency of Li, Mn, Co, and Ni was achieved from the NCM black mass in the process of microwave-assisted leaching under these conditions.

[0128] Kinetics Analysis. The leaching kinetics was investigated at different times (5-60 min) and temperatures (120-180 ºC) using 0.2 mol / L H2SO4and 0.75 g / g grass leaves dosage with a fixed solid concentration of 20 g / L in microwave-assisted leaching. Four kinetic models, including surface chemical control shrinking core model (Eq. (1)), diffusion control shrinking core model (Eq. (2)), logarithmic rate law model (Eq. (3)), and Avrami model (Eq. (4)), were employed to correlate with the leaching data. భ 1െ ^1 െ ^^^య ൌ ^^^^^ Eq. (1)1 ଶ మ െ ଷ^^ െ ^1 െ ^^^య ൌ ^^ଶ^^ Eq. (2)^^^^ଶ (3)(4)where X is the leaching efficiency of metals, k1, k2, k3, and k4are reaction constants (min-1), and t represents the reaction time (min). In the Avrami model equation, n indicates the orderATTORNEY DOCKET NO.222204-2800 of the reaction.

[0129] As indicated in FIGS.3A-3D, alternations of temperature and reaction time influence the leaching efficiency of Li, Mn, Co, and Ni from the NCM black mass in microwave-assisted leaching. High temperatures and extended reaction time gave rise to increased leaching efficiency of valuable elements. The leaching results of Li, Mn, Co, and Ni were subjected to linear fitting using four kinetic models (Eq (1)-Eq (4))., respectively, and the fitted results are shown in Table 4. Referring to the fitting parameters (R2), surface chemical control shrinking core model demonstrated superior linear relationships for Li, Mn, Co, and Ni than the other three models evaluated (displayed in FIGS.3E-3H), indicating that surface chemical reaction process was the dominant mechanism in the microwave-assisted leaching of Li, Mn, Co, and Ni from the NCM black mass. Table 4. Fitting parameters (R2) of different models for Li, Mn, Co, and Ni at different leaching temperatures. Temp. R2(Li) R2(Mn) R2(Co) R2(Ni) 3 2 1 7 3 3 1 1 1 2 9 6 4 2 7 9 [01 sed to calcuae e ac va on energy requre or e reac on q. . ^^^^^^ ൌ െாೌோ்^ ^^^^^^ Eq. (5)ATTORNEY DOCKET NO.222204-2800 where k is the reaction constant (min-1), Eais the activation energy (kJ / mol), R indicates the ideal gas constant (8.314 J / K / mol), T represents absolute temperature (K), and A shows the preexponential factor.

[0131] FIGS. 3I-3L illustrate the Arrhenius plots of lnK vs. T-1 using different reaction constants. The activation energies of Li, Mn, Co, and Ni were 18.85 kJ / mol, 51.78 kJ / mol, 56.26 kJ / mol, and 35.39 kJ / mol, respectively. Compared to Mn and Co, relatively low activation energies required for Li and Ni indicated fast leaching rates, which was consistent with the results of single-factor experiments (Faraji, Alizadeh, and Rashchi 2020). The leaching of valuable elements (Li, Mn, Co, and Ni) from the NCM black mass in the process of microwave-assisted leaching was governed by surface chemical reaction, signifying that the effect of temperature and reducing agent concentration were pronounced (Wang et al. 2022).

[0132] Characterization of Products Derived from the Microwave-assisted Leaching Process. FIG.4A depicts XRD patterns of the NCM black mass, grass leaves, and leaching residue obtained at 180 ºC. The XRD pattern of the NCM black mass exhibited characteristic peaks consistent with typical NCM battery materials (marked with gray diamond symbols). After microwave-assisted leaching at 180 ºC, there was a significant reduction in the peak intensities of the NCM black mass due to the dissolution of valuable metals, with the exception of those observed in the green regions. Peaks in the green areas correlated with graphite in anode materials of the NCM black mass, and the intensity of these peaks significantly increased after the microwave-assisted leaching process. The diffraction peak in the purple area represented the native cellulose in the grass leaves (P. Chen, Shrotri, and Fukuoka 2019). The crystallization intensity of cellulose reduced after leaching. Li and Zhang found that amorphous hemicellulose and crystalline cellulose presented in the grass leaves were decomposed during the microwave-assisted leaching process, leading to the formation of amorphous products (Li and Zhang 2024). These results indicated that during microwave- assisted leaching, valuable elements were effectively leached from the NCM black mass at 180 ºC.

[0133] FIG.4B shows the UV-Vis spectra of leachates achieved at different temperatures. A pronounced peak at 287 nm was observed, corresponding to Me(II)-L, where Me represents metals such as Ni, Co, and Mn, and L is the ligands H2SO4and grass leaves. The peak at 287 nm enhanced with an increase in temperatures from 120 ºC to 180 ºC, indicating that stronger chelating agents were produced from grass leaves to form stable complexes with valuable elements in the process of microwave-assisted leaching (Yan et al.2021).

[0134] FIG. 4C illustrates the alternations in functional groups of leachates obtained at different temperatures. The wide peak at 3295.8 cm-1represents the O-H stretching vibration in the hydrogen bond. The O-H peak shape of the leachate achieved at 120 ºC was blunt and wide due to the association of the hydrogen bond between molecules. However, the O-H peakATTORNEY DOCKET NO.222204-2800 value decreased gradually with increasing reaction temperature, indicating that poly-hydroxyl groups were oxidized into other groups (Su et al. 2022). When increasing the temperature from 120 ºC to 180 ºC, poly-hydroxyl groups in grass leaves were oxidized, showing a reducing capacity of grass leaves.1639.2 cm-1is the C=O peak of hydrogen bonding. The value of the C=O peak in the leachate obtained at 180 ºC was obviously lower compared to those achieved at the temperatures of 120 ºC, 140 ºC, and 160 ºC, indicating that the destruction of the intramedullary hydrogen bond occurred during the microwave-assisted leaching at 180 ºC (Yan et al.2021).

[0135] The FTIR spectra of grass leaves and leaching residue obtained after microwave- assisted leaching at 180 ºC are shown in FIG.4D. The bands identified at 3344.0 cm-1, 3309.3 cm-1, and 2919.7 cm-1corresponded to the adsorption of O-H in the grass leaves. Reductions in the O-H peak values after microwave-assisted leaching were observed, demonstrating that poly-hydroxyl groups were oxidized to other groups. This finding was consistent with the results presented in FIG.4C. Two obvious peaks, 1635.3 cm-1and 1629.6 cm-1, corresponded to the C=C stretching vibration. Peak values at 1033.7 cm-1and 1037.5 cm-1are the stretching vibrations of C-N contained in aliphatic amine. Significant changes were observed in the characteristic peaks of C=C and C-N in the oxidation reaction zone, demonstrating the reducibility of grass leaves in the process of microwave-assisted leaching (Gu, Xia, et al. 2023).

[0136] SEM characterization was conducted on the NCM black mass and leaching residues achieved at 120 ºC and 180 ºC, respectively, to evaluate their morphological and surface characteristics (Li et al.2023). FIG.5A depicts the micrograph of the NCM black mass, where pronounced particle agglomeration is observed, a typical morphological structure of the NCM black mass (Liu et al.2019). EDS-mapping data in FIGS.5C-5G depict the enrichment of C, O, as well as valuable elements, including Mn, Co, and Ni, in the NCM black mass. SEM image with high magnification of FIG.5A is shown in FIG.5B, and element distributions of the NCM black mass are depicted in FIGS. 5H-5K using EDS analysis for Points 1, 2, 3, and 4, respectively. This result further verified that Mn, Co, and Ni were presented in the NCM black mass. FIGS. 6A-6H show the particle morphology and element distribution of the leaching residue produced at 120 ºC. The leaching residue exhibits irregular shapes with heterogeneous diameters (FIG. 6A). The EDS mapping analysis in FIGS. 6B-6F and EDS point analysis in FIGS.6G-6H reveal that small contents of Mn, Co, and Ni were still present in the leaching residue. Correspondingly, as illustrated in FIG.3B, the leaching efficiency of Mn, Co, and Ni was 58.1%, 58.5%, and 90.3%, respectively, which was consistent with the results from SEM-EDS analysis. After microwave-assisted leaching at 180 ºC, nearly 100% of valuable elements were dissolved from the NCM black mass. The EDS analysis of FIG.7D indicates only two major elements, C and O, are presented in the leaching residue achieved at 180 ºC. In general, SEM characterizations provide insights into the structural and elementalATTORNEY DOCKET NO.222204-2800 alternations in the NCM black mass before and after microwave-assisted leaching at varying temperatures. Temperature appeared to be one factor that influenced the leaching efficiency of valuable elements from the NCM black mass during microwave-assisted leaching.

[0137] XPS analysis was applied to investigate the surface elemental compositions and chemical states of the NCM black mass before and after microwave-assisted leaching at 120º. FIG.8A shows the presence of Mn, Co, and Ni on the surface of the NCM black mass and leaching residue obtained at 120 ºC. As can be seen from FIG. 8B, the main peaks of Mn 2p3 / 2 at 640.3 eV and 643.3 eV correspond to Mn4+and Mn2+, respectively (Ilton et al.2016). After being treated at 120 ºC, the content of Mn4+decreased and Mn2+content enhanced in the leaching residue, indicating that Mn4+was effectively reduced Mn2+. Peaks of Co 2p / 3 / 2 in FIG.8C depict that the NCM black mass contained both Co3+and Co2+at 778.9 eV and 781.1 eV, respectively, with a satellite peak at 785.6 eV (Wang et al.2022). Peaks of Co 2p3 / 2 of leaching residue obtained at 120 ºC revealed that more Co2+was detected at 781.1 eV peak, which demonstrated that Co3+was reduced to Co2+. FIG.8D illustrates the Ni 2p3 / 2 orbit of the NCM black mass and leaching residue obtained at 120 ºC only present one peak at 853.8 eV, which corresponds to Ni2+(Zhu et al. 2021). The peak of Ni2+remained constant in the form before and after microwave-assisted leaching, suggesting that Ni predominantly persists as Ni2+regardless of the leaching process. Therefore, Ni mainly existed in Ni2+in the NCM black mass was easier to be leached than Co and Mn with an increase in reaction temperature (FIG.1B).

[0138] Based on the above characterizations of products derived from the microwave- assisted leaching process, it was found grass leaves functioned as an effective reducing agent in recovering valuable elements from the NCM black mass. In addition, during microwave- assisted leaching process, in addition to reducing agents, grass leaves had the potential to be decomposed into chelating agents and organic acids with an increase in temperature, which also promoted spent NCM battery recycling. G. REFERENCES

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[0177] It will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the scope or spirit of the disclosure. Other aspects of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosure being indicated by the following claims.

Claims

ATTORNEY DOCKET NO.222204-2800 CLAIMS What is claimed is:

1. A method comprising: combining a sample of black mass and a loading solvent, thereby forming a first mixture; heating the first mixture at a pressure of about 150 psi to about 600 psi, thereby forming a treated mixture comprising a solid residue and an aqueous solution; and separating the solid residue from the aqueous solution; wherein the sample of black mass comprises at least on critical material; wherein the loading solvent comprises at least one leaching agent and at least one reducing agent, wherein the reducing agent comprises a biomass feedstock; and wherein the treated mixture comprises at least one critical material.

2. The method of claim 1, wherein heating the first mixture comprises exposing the first mixture to microwave radiation.

3. The method of claim 2, wherein the first mixture is exposed to microwave radiation at a power of about 500 Watts to about 1000 Watts.

4. The method of claim 2, wherein the first mixture is exposed to microwave radiation at a power of about 700 Watts to about 1000 Watts.

5. The method of claim 2, wherein the first mixture is exposed to microwave radiation at a power of about 800 Watts to about 900 Watts.

6. The method of any one of claims 1-5, wherein combining the sample of black mass and the loading solvent further comprises stirring.

7. The method of any one of claims 1-5, wherein the sample of black mass is lithium-ion battery black mass.

8. The method of any one of claims 1-7, wherein the treated mixture further comprises a reducing compound selected from a sugar, a phenolic acid, and any combination thereof.

9. The method of claim 8, wherein the sugar is selected from a monosaccharide, a disaccharide, and a combination thereof.

10. The method of claim 8 or claim 9, wherein the sugar is selected from glucose, fructose, sucrose, and any combination thereof.

11. The method of claim 8, wherein the phenolic acid is selected from protocatechuic acid, vanillic acid, p-coumaric acid, chlorogenic acid (5-caffeoylquinic acid), 4- hydroxybenzaldehyde, 3,4-hydroxybenzoic acid, cinnamic acid, gallic acid, isorhamnetin, quercetin, p-hydroxybenzoic acid, vanillic acid, caffeic acid, p-coumaric acid, ferulic acid, syringic acid, sinapinic acid, and any combination thereof.

12. The method of any one of claims 1-7, wherein the treated mixture further comprisesATTORNEY DOCKET NO.222204-2800 molasses.

13. The method of any one of claims 1-12, wherein the first mixture is heated to a reaction temperature of about 100 °C to about 200 °C.

14. The method of any one of claims 1-12, wherein the first mixture is heated to a reaction temperature of about 160 °C to about 200 °C.

15. The method of any one of claims 1-12, wherein the first mixture is heated to a reaction temperature of about 180 °C to about 200 °C.

16. The method of any one of claims 1-15, wherein the first mixture is heated at a rate of about 10 °C / min to about 50 °C / min until the reaction temperature is reached.

17. The method of any one of claims 1-15, wherein the first mixture is heated at a rate of about 10 °C / min to about 30 °C / min until the reaction temperature is reached.

18. The method of any one of claims 1-17, wherein the first mixture is heated for about 10 minutes to about 60 minutes.

19. The method of any one of claims 1-17, wherein the first mixture is heated for about 15 minutes to about 45 minutes.

20. The method of any one of claims 1-17, wherein the first mixture is heated for about 20 minutes to about 30 minutes.

21. The method of any one of claims 1-20, wherein the first mixture is heated at a pressure of about 150 psi to about 300 psi.

22. The method of any one of claims 1-21, wherein the leaching agent comprises an acid.

23. The method of claim 22, wherein the acid is selected from a mineral acid, an organic acid, and a combination thereof.

24. The method of claim 22, wherein the acid is selected from hydrochloric acid, nitric acid, sulfuric acid, citric acid, ascorbic acid, malic acid, tartaric acid, malonic acid, maleic acid, fumaric acid, and any combination thereof.

25. The method of claim 22, wherein the acid comprises sulfuric acid.

26. The method of any one of claims 22-25, wherein a concentration of the acid in the first mixture is such that the pH of the first mixture is from about 1 to about 6.

27. The method of any one of claims 22-25, wherein a concentration of the acid in the first mixture is such that the pH of the first mixture is from about 1 to about 4.

28. The method of any one of claims 22-25, wherein a concentration of the acid in the first mixture is such that the pH of the first mixture is from about 1 to about 2.

29. The method of any one of claims 22-25, wherein a concentration of the acid in the first mixture is from about 0.05 mol / L to about 0.50 mol / L.

30. The method of any one of claims 22-25, wherein a concentration of the acid in the first mixture is from about 0.05 mol / L to about 0.30 mol / L.

31. The method of any one of claims 22-25, wherein a concentration of the acid in the firstATTORNEY DOCKET NO.222204-2800 mixture is from about 0.15 mol / L to about 0.20 mol / L.

32. The method of any one of claims 1-31, wherein a concentration of the sample of black mass in the first mixture is from about 10 g / L to about 200 g / L.

33. The method of any one of claims 1-31, wherein a concentration of the sample of black mass in the first mixture is from about 10 g / L to about 100 g / L.

34. The method of any one of claims 1-31, wherein a concentration of the sample of black mass in the first mixture is from about 10 g / L to about 30 g / L.

35. The method of any one of claims 1-34, wherein a concentration of the biomass feedstock in the first mixture is from about 0.1 g biomass feedstock / g black mass to about 1.0 g biomass feedstock / g black mass.

36. The method of any one of claims 1-34, wherein a concentration of the biomass feedstock in the first mixture is from about 0.3 g / g to about 0.8 g / g.

37. The method of any one of claims 1-34, wherein a concentration of the biomass feedstock in the first mixture is from about 0.5 g / g to about 0.8 g / g.

38. The method of any one of claims 1-37, wherein the biomass feedstock comprises grass leaves, food wastes, or a combination thereof.

39. The method of any one of claims 1-38, wherein the biomass feedstock comprises particles with an average particle size of less than about 300 µm.

40. The method of any one of claims 1-39, wherein the sample of black mass comprises at least one critical material selected from lithium, manganese, cobalt, nickel, iron, copper, and any combination thereof.

41. The method of any one of claims 1-40, wherein the treated mixture comprises at least one critical material selected from lithium, manganese, cobalt, nickel, and any combination thereof.

42. The method of any one of claims 1-41, wherein the aqueous solution comprises from about 85% to about 99% of the at least one critical material present in the treated mixture.

43. The method of any one of claims 1-41, wherein the aqueous solution comprises from about 90% to about 99% of the at least one critical material present in the treated mixture.

44. The method of any one of claims 1-41, wherein the aqueous solution comprises from about 95% to about 99% of the at least one critical material present in the treated mixture.

45. The method of any one of claims 1-44, wherein the solid residue is separated from the aqueous solution by centrifugation.

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