Method and apparatus for lithium iron phosphate and lithium manganese iron phosphate battery recycling

Abstract

A method for recycling spent or scrap lithium iron phosphate (LFP) or lithium manganese iron phosphate (LMFP) battery materials includes selectively leaching a black mass with an acid and optionally an oxidizing agent to form a. mixture of leachate and a first filter cake, selectively removing titanium, copper and aluminum from the leachate to form a filtrate comprising ferrous ions, oxidizing the filtrate including ferrous ions at a temperature ranging from 20 °C to 100 °C to form a crude iron phosphate and a lithium- rich solution, purifying the crude iron phosphate at a temperature ranging from about 20°C to about 100 °C to form a battery grade iron phosphate, and processing a lithium rich solution to form battery grade lithium carbonate. The black mass includes the spent or scrap LFP or LMFP battery materials.

Description

METHOD AND APPARATUS FOR LITHIUM IRON PHOSPHATE AND LITHIUM MANGANESE IRON PHOSPHATE BATTERY RECYCLING BACKGROUND

[0001] A lithium iron phosphate (LiFePO4) (LFP) battery comprises several essential components: the cathode, anode, electrolyte, separator, and current collectors. The cathode acts as the positive electrode and is composed of LFP material. The anode serves as the negative electrode and is mainly made of carbon or graphite. The electrolyte plays a crucial role in facilitating the movement of lithium ions between the cathode and anode. It commonly consists of a lithium salt, such as LiPF6, dissolved in an organic solvent like ethylene carbonate or diethyl carbonate. The separator, made of a microporous material, such as polyethylene or polypropylene, physically separates the cathode and anode to prevent direct contact and short circuits while allowing the efficient flow of lithium ions. Current collectors, constructed from metals, such as aluminum or copper, aid in the conduction of electrons within the battery and establish connections to the external circuit.

[0002] In an LFP battery, the components work together to store and release electrical energy through the movement of lithium ions. During the charging process of an LFP battery, an external power source applies voltage to the battery terminals, creating a potential difference. This potential difference prompts lithium ions to move from the cathode to the anode. At the cathode, iron atoms in the LFP structure undergo oxidation, releasing electrons into the cathode material. These released electrons contribute to the flow of electric current within the battery. Simultaneously, the lithium ions travel through the electrolyte and intercalate into the anode material, where they can be stored between its layers. During the discharge process, when a load or device is connected to the battery, the stored energy is released, initiating the movement of lithium ions from the anode back to the cathode through the electrolyte. As the lithium ions approach the cathode, the iron atoms within the LFP structure undergo a reduction process, accepting the electrons provided by the external circuit. This flow of electrons through the external circuit generates an electric current that can be utilized to power various devices.

[0003] LFP batteries have found numerous applications in various industries. For example, LiFePO4 batteries are widely used in electric vehicles, especially in medium-and-low range vehicles due to their longer lifetime, lower cost, and better environmental performance. Furthermore, LFP batteries can be utilized in energy storage systems, where they help to store excess electricity generated from renewable energy sources including solar or wind.

[0004] Nickel-Manganese-Cobalt (NMC) batteries, Manganese Spinel (NCA) batteries, and LFP batteries are the top three lithium-ion battery (LIB) chemistry types in market demand, as of 2018, accounting for 37.4%, 28.7%, and 24.9%, respectively. Cobalt-free LFP batteries are now preferable to other batteries due to their reduced battery raw material cost. In addition, LFP has surpassed other types of batteries to become the most dominant lithium-ion battery in the market. The increasing usage of LFP batteries leads to a large majority of waste traction batteries. According to one forecast, a cumulative global return flow of about 1 million metric ton waste traction batteries will enter the recycling market by 2025. In addition, about three-quarters of the waste batteries are LFP batteries.

[0005] In the past, there has been a limited emphasis on the recycling of LFP batteries due to their low content of high-value metals. However, with the growing expectation of increasing return flows of LFP batteries, it has become essential to prioritize recycling. Within the last decade, many processes have been developed for the recycling of waste lithium-ion batteries. From an economic point of view, cobalt, nickel, and copper are the major metals recycled from waste traction batteries due to their high values. It is worth mentioning that lithium recycling from LFP batteries has been gaining more attention due to its rising value from approximate 4,000 - 6,000 US$ / mt Li2CO3between 2007 and 2015 to about 15,000 US$ / mt Li2CO3 since November 2016.

[0006] The recycling of waste LFP batteries has been carried out with two traditional methods, including pyrometallurgy (recycling at high temperatures) and hydrometallurgy (recycling at relatively low temperature in aqueous solutions). It was reported that the LFP recycled at 700 °C for 3 h realized high crystallinity and acceptable electrochemical properties. Though direct pyrometallurgical regeneration is a reliable method of recovering lithium from LFP batteries, high energy consumption and the toxic off-gassing at high temperatures made pyrometallurgy not be regarded as an environmentally safe and cost-efficient approach for LFP recovery. In hydrometallurgy methods, two main techniques are utilized for metal recovery from LFP batteries: selective recovery and non-selective recovery.

[0007] The selective recovery process is known as a one-step recovery process. During selective recycling of lithium and in-situ preparation of FePO4 (FP), acid leaching, alkaline leaching or bioleaching may be used to selectively recycle lithium from LFP batteries. Li2CO3 and FePO4 may be recovered from the leachate and the leaching residue by adding Na2CO3and H2O2, respectively.

[0008] Li and FePO4 can be leached from solids into solution simultaneously during the non-selective recovery process. Subsequently, battery-grade Li compounds and FePO4 can be produced from the solution through hydrometallurgical methods. While the non- selective method requires more chemicals than the selective method, this drawback can be mitigated by generating additional profits from the production of battery-grade FePO4. However, both methods face challenges in controlling the composition and producing battery-grade products. Many current practices focus on recovering lithium while leaving FePO4 in the slag as waste, which is not a sustainable solution for a closed-loop economy.

[0009] Lithium manganese iron phosphate (LMFP) is an advanced type of lithium-ion battery material, combining the benefits of LFP with manganese doping to enhance performance characteristics. LMFP is gaining attention in various applications, particularly in electric vehicles (EVs) and renewable energy storage systems, due to its superior properties, such as high energy density, improved thermal stability, enhanced cycle life, better rate capacity, and cost effectiveness. The development and commercialization of LMFP technology are expected to grow, driven by the increasing demand for high- performance, safe, and cost-effective energy storage solutions. Unfortunately, the recycling of LMFP batteries is not as developed as that for more common types.

[0010] There remains a significant need to overcome the challenges of controlling the composition, produce battery-grade products, reduce the cost, increase the overall efficiency, and increase the adaptability of the method to recycle LFP and LMFP batteries.

[0011] This present invention addresses these, and other problems associated with the prior art. SUMMARY

[0012] This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.

[0013] In one aspect, embodiments described herein relate to a method for recycling spent or scrap lithium iron phosphate (LFP) or lithium manganese iron phosphate (LMFP) battery materials including: selectively leaching a black mass with an acid and optionally an oxidizing agent, to form a mixture of leachate and a first filter cake, wherein the black mass includes the spent or scrap LFP or LMFP battery materials; selectively removing titanium, copper and aluminum from the leachate to form a filtrate including ferrous ions; oxidizing the filtrate including ferrous ions at a temperature ranging from 20 °C to 100 °C to form a crude iron phosphate and a lithium-rich solution; purifying the crude iron phosphate at a temperature ranging from about 20°C to about 100 °C to form a battery grade iron phosphate; and processing a lithium rich solution to form battery grade lithium carbonate.

[0014] In one or more embodiments, the selectively removing copper from the leachate includes: adding iron powder to the leachate at a temperature ranging from 20 °C to 100 °C; extracting copper from the leachate with a solvent; or adsorbing cooper from the leachate.

[0015] In one or more embodiments, the iron powder is added in an amount of 10-50% theoretical excess.

[0016] In one or more embodiments, the selectively removing aluminum includes: adding complexing agents to the leachate; or performing selective ion exchange with the leachate, wherein the complexing agents include alkali metal compounds, fluoride compounds capable of complexing with aluminum, or mixtures thereof.

[0017] In one or more embodiments, the fluoride compounds are selected from the group consisting of sodium fluoride, potassium fluoride, ammonium fluoride, lithium fluoride, and combinations thereof.

[0018] In one or more embodiments, the adding of complexing agents is performed at a pH ranging from 1 to 3.

[0019] In one or more embodiments, the oxidizing the filtrate includes: treating the filtrate including ferrous ions with an oxidizing agent and optionally an alkali earth metal to form a slurry; separating the slurry to isolate the crude iron phosphate; and rinsing the crude iron phosphate.

[0020] In one or more embodiments, the oxidizing the filtrate is performed for a time period ranging from 1 min to 100 hours.

[0021] In one or more embodiments, the treating the crude iron phosphate includes at least one of the following steps to form a slurry: mixing the crude iron phosphate with a solution including 0.1 wt% to 50 wt% acid; treating the crude iron phosphate with a surfactant; or repeatedly washing the crude iron phosphate with a rinsing solution.

[0022] In one or more embodiments, the techniques described herein relate to a method, further including, filtering and drying the slurry to provide the battery grade iron phosphate.

[0023] In one or more embodiments, the mixing the crude iron phosphate with the acid solution includes mixing from 0.1% to 50 wt% acid solution at a temperature ranging from 20 °C to 100 °C, for a period of time ranging from 1 hour to 24 hours.

[0024] In one or more embodiments, the surfactant is selected from the group consisting of of polyethylene glycol, triethanolamine, stearic acid, polysorbate, and combinations thereof.

[0025] In one or more embodiments, the rinsing solution includes deionized water, hydrogen peroxide, a dilute acid solution, or combinations thereof.

[0026] In one or more embodiments, the selectively leaching the black mass includes: filtering the mixture to isolate the first filter cake and to collect a lithium-rich solution; andtreating the first filter cake with the acid to form a solution including iron and phosphate as the leachate.

[0027] In one or more embodiments, the processing the lithium filtrate includes: removing contaminants from the lithium-rich solution; extracting lithium from the lithium-rich solution to form lithium in a treated solution; and precipitating crude lithium carbonate from the lithium in the treated solution.

[0028] In one or more embodiments, the removing contaminants includes: adjusting a pH of the lithium-rich solution to a range of 3 to 14 at a temperature ranging from about 10°C to about 100°C, for a time period ranging from 1 min to 24 hours.

[0029] In one or more embodiments, the extracting lithium from the lithium-rich solution includes extracting lithium with a solvent to form the lithium in the treated solution.

[0030] In one or more embodiments, the precipitating crude lithium carbonate includes: performing mechanical vapor recompression on the lithium in the treated solution; adding a solution saturated with CO2to the treated solution to form a lithium bicarbonate solution; and precipitating the battery grade lithium carbonate from the lithium bicarbonate solution.

[0031] Other aspects and advantages of the claimed subject matter will be apparent from the following description and the appended claims. BRIEF DESCRIPTION OF DRAWINGS

[0032] FIG.1 is one of the two process flow diagrams of recycling lithium iron phosphate (LFP) and lithium manganese iron phosphate (LMFP) batteries in accordance with embodiments disclosed herein.

[0033] FIG. 2 is another process flow diagram of recycling lithium iron phosphate (LFP) and lithium manganese iron phosphate (LMFP) batteries in accordance with embodiments disclosed herein.

[0034] FIG. 3 shows the SEM image of the FePO4product produced using this invented method.

[0035] FIG.4 shows the pictures of the typical Li2CO3and FePO4products produced using this invented method.DETAILED DESCRIPTION

[0036] The disclosure is not limited to particular embodiments described, and as such may, of course, vary. The terminology used herein serves the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present disclosure will be limited only by the appended claims.

[0037] As those having ordinary skill in the art will appreciate, different persons may refer to the same feature by different names. This document does not intend to distinguish between features that differ in name but not function. The figures are not necessarily drawn to scale. Certain features here may be shown in somewhat schematic form and some details may not be shown in the interest of clarity and conciseness.

[0038] Those having ordinary skill in the art will appreciate that the following description has broad application, and the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to suggest that the scope of the disclosure, including the claims, is limited to that embodiment.

[0039] Where a range of values is provided, each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range, is encompassed within the disclosure. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges and are also encompassed within the disclosure, subject to any specifically excluded limit in the stated range. 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.

[0040] Embodiments of the present disclosure will employ, unless otherwise indicated, techniques of organic chemistry, inorganic chemistry, biology, and the like, which are within the skill of the art. Such techniques are explained fully in the literature.

[0041] 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 to perform the methods and use the compositions and compounds disclosed and claimed herein. Effects have been made toensure accuracy with respect to numbers (e.g., amounts, temperatures, etc.), but some errors and deviations should be accounted for.

[0042] It should be noted that ratios, concentrations, amounts, and other numerical data may be expressed herein in a range format. 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 values 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 concentration range of “about 0.1 percent to 0.5 percent” should be interpreted to include not only the explicitly recited concentration of about 0.1 percent to about 0.5 percent but also include individual concentrations (e.g., 1 percent, 2 percent, 3 percent, and 4 percent) and the sub- ranges (e.g., 0.5 percent, 1.1 percent, 2.2 percent, 3.3 percent, and 4.4 percent) within the indicated range. The term “about” can include traditional rounding according to significant figures of the numerical value. In addition, the phrase “about ‘x’ to ‘y’” includes “about ‘x’ to ‘about y’”.

[0043] Furthermore, the terms “about”, “approximate”, “at or about”, and “substantially” as used herein 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 to 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 circumstance, the value that provides equivalent results or effects cannot be reasonable determined. In such cases, it is generally understood, as used herein, that “about” and “at or about” mean the nominal value indicated 10% variations 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.

[0044] Before the embodiments of the present disclosure are described in detail, it is to be understood that, unless otherwise indicated, the present disclosure is not limited to particular materials, reagents, reaction materials, manufacturing processes, dimensions, frequency ranges, applications, or the like, as such can vary. It is also to be understood that the terminology used herein is for purposes of describing particular embodiments only and is not intended to be limiting. It is also possible in the present disclosure that steps can be executed in different sequence, where this is logically possible. It is also possible that the embodiments of the present disclosure can be applied to additional embodiments involving measurements beyond the examples described herein, which are not intended to be limiting. It is furthermore possible that the embodiments of the present disclosure can be combined or integrated with other measurement techniques beyond the examples described herein, which are not intended to be limiting.

[0045] It should be noted that, 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 support” includes a plurality of supports. In this specification and in the claims that follow, reference will be made to a number of terms that shall be defined to have the following meanings unless a contrary intention is apparent.

[0046] In the following discussion and in the claims, the terms “such as”, “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to...”.

[0047] Embodiments disclosed herein are directed to a method and apparatus of several innovative technologies to produce battery-grade lithium (Li) compounds and iron phosphate (FP) at high recovery efficiencies from lithium iron phosphate (LFP) and lithium manganese iron phosphate (LMFP) batteries. LFP and / or LMFP black mass that contains cathode and anode materials is produced from batteries. The black mass is then subjected to leaching to dissolve lithium, iron, and phosphate, resulting in a leachate that contains the valuable cathode components and some contaminant species (primarily copper and aluminum). Aluminum is removed from the leachate in a de-Al step through a novel method. After de-Al, a crude FePO4 precipitate is obtained from the leachate byprecipitation followed by rinsing to improve its purity, while lithium is retained in the leachate and subjected to subsequent purification steps. The crystallinity of the crude FePO4 is enhanced and its physical properties (e.g., size, morphology, sphericity) are adjusted in the aging step, resulting in battery-grade FePO4 that can be used to make new lithium iron phosphate and lithium manganese iron phosphate batteries.

[0048] Referring to FIG.1 and FIG.2, two process flow diagrams 100, 200 in accordance with embodiments disclosed herein are shown. The method and apparatus disclosed herein for lithium iron phosphate (LFP) battery and lithium manganese iron phosphate (LMFP) battery recycling applies to both spent and scrap LFP and LMFP batteries 102 & 202. The batteries may be discharged before conducting the methods described herein. A material that is normally referred to as black mass (BM) and contains mainly the cathode and anode materials may be produced by a crushing, shredding and separation or other methods 102 & 202.

[0049] Recycled batteries may come in the form of black mass already. In this case, the step of crushing, shredding and sieving 102 & 202 may not be necessary.

[0050] The LFP and / or LMFP black mass 102 & 202 may be subjected to acid leaching 104 & 204 & 206 to dissolve lithium, iron, and phosphate. The resulting slurries after acid leaching may be subjected to solid / liquid (S / L) separation and rinsing multiple cycles during these processes 104 & 204 & 206. Any S / L separation method, such as filter press, may be used for this purpose. The liquid after the separation may be referred to as filtrate, leachate, or solution in the following discussion and the claims. The solid after the separation may be referred to as filter cake, leaching residual, precipitates, or simply solid, as discussed in the following discussion and in the claims.

[0051] In one or more embodiments, and as shown in FIG.1, the LFP and / or LMFP black mass is subjected to one-step leaching 104 by reacting with an acid, leading to a solution rich in lithium, iron, as well as phosphate and contaminants. In other embodiments, and as shown in FIG. 2, the LFP and / or LMFP black mass is subjected to staged leaching to achieve selective dissolution. In the first stage 204, the LFP and / or LMFP black mass is reacted with an acid and an oxidizing agent to selectively dissolve lithium, leading to a solution rich in lithium plus some contaminants. The contaminants according to one ormore embodiments, include but are not limited to aluminum, iron, copper, zinc, calcium, magnesium, titanium, etc. In the second stage 206, the solid residue of the first stage is reacted with an acid to dissolve iron and phosphate, leading to a solution rich in iron and phosphate plus some contaminants.

[0052] In one or more embodiments, the leaching reaction occurs in an acid solution, such as H2SO4, HCl, HNO3 or H3PO4. In some embodiments, the reaction occurs under conditions of a solid to liquid ratio of about 1:2 to about 1:10 and a temperature of about 20 °C to 100 °C. In some embodiments, the acid leaching 204 requires the addition of an oxidizing agent, which includes, but is not limited to, hydrogen peroxide, oxygen, ozone or combinations thereof.

[0053] After solid / liquid separation, the filtrate, leachate, or solution, which contains dissolved valuable components and some contaminant species (primarily aluminum), is collected and will be further processed to remove titanium, copper and aluminum. While the figures shown de-Ti followed by de-Cu and de-Al, these removal steps may be performed in a different order.

[0054] The filtrates obtained from processes 104 and 206 may be subjected to de-Ti process 105 and 207 to eliminate Ti. To achieve efficient removal, the pH of the filtrates may be raised / adjusted to a pH ranging from 1 to 3, such as from a lower limit of any one of 1.0, 1.2, or 1.4 to an upper limit of any one of 2, 2.2, 2.5, 2.8 or 3, where any lower limit may be paired with any mathematically compatible upper limit. The pH may be adjusted by adding a carbonate base such as sodium carbonate. The reaction for titanium removal may occur for at least 1 hour and up to 12 hours, and at a temperature ranging from about 20 °C to about 60 °C.

[0055] The filtrates obtained from processes 105 and 207 are first subjected to de-Cu processes 106 & 208 to eliminate Cu. Various methods can be used in this step. In one or more embodiments, this can be achieved by adding iron powder, serving as a reducing agent, to reduce copper ions into copper metal. In other embodiments, other methods, such as solvent extraction or adsorption, can be used to selectively remove Cu from the leachate. To achieve efficient removal, the pH of the filtrates for de-Cu may be raised / adjusted to a pH ranging from 1 to 3, such as from a lower limit of any one of 1.0, 1.3, 1.5 or 2 to anupper limit of any one of 2.2, 2.5, 2.8 or 3, where any lower limit may be paired with any mathematically compatible upper limit. In one or more embodiments, the de-Cu step using iron powder occurs at a temperature ranging from about 20 °C to about 100 °C. In such embodiments, the dosage of iron powder is expected to be 10-50% extra of theoretical amount. As a non-limiting example, iron powder may be added into the leaching solution at a reaction temperature of 50 °C. The suspension may be continuously stirred during the reaction, while the dosage of iron powder is maintained at a stoichiometric ratio to Cu ranging from 1:1 to 10:1.

[0056] Embodiments disclosed herein are directed to a method to remove aluminum 108 & 210 as shown in FIG. 1 and FIG. 2 from the leachates (i.e., de-Al the leachates). The leachates may be conditioned by adjusting their pH to precipitate aluminum. The pH of the leachate may be adjusted by adding bases complexing agents to precipitate aluminum. To achieve efficient removal, the pH of the filtrates for de-Al may be raised / adjusted to a pH ranging from 1 to 3, such as from a lower limit of any one of 1.0, 1.2 or 1.4 to an upper limit of any one of 1.5, 1.7, 1.9 or 2, where any lower limit may be paired with any mathematically compatible upper limit. The resulting slurries may be then filtered or use other methods to separate the precipitates and the liquid. After solid / liquid separation, the filtrates are collected and will be processed next, while the filter cake mainly contains aluminum precipitates. The de-Al efficiency of the process may be determined by several factors, such as reaction temperature, leachate pH, complexing agent types and dosage, complexing reaction conditions, and rinsing.

[0057] The complexing agents may be a mixture of alkali metal compounds and fluoride compounds. Alkali metal compounds provide metal ions to complexes, while fluoride ions selectively complex with aluminum. In one or more embodiments, the alkali metal compounds that may be used in this application include but are not limited to sodium hydroxide, sodium carbonate, sodium sulfate, potassium hydroxide, potassium carbonate, potassium sulfate, ammonia, and iron powder. In a further aspect, the fluoride compounds that may be used include but are not limited to sodium fluoride, potassium fluoride, ammonium fluoride and lithium fluoride. A variety of complexing agents may be obtained by mixing one or multiple alkali metal compounds and fluoride compounds. In addition,alkali metals introduced in previous steps of the process may also participate in the complexation reaction as reactants. The de-Al can also be conducted by using the selective ion exchange method. Embodiments disclosed here are direct to a method for pH adjustment per the needs of de-Ti 105 & 207, de-Cu 106 & 208 and de-Al 108 & 210. The pH adjustments can also be achieved by adding common alkalis, such as sodium hydroxide, potassium hydroxide, and sodium carbonate.

[0058] After de-Al 108 & 210, the filtrates are further processed by a FePO4 (FP) precipitation step 110 & 212 and a filtration process to produce crude FP products, which will be disclosed further next.

[0059] Embodiments disclosed here are directed to a process for crude FP production from the filtrate (leachate) obtained from the de-Al step. Ferrous ions present in the solution may be first oxidized with an oxidizing agent, which may be any agent able to oxidize ferrous ions, including but not limited to hydrogen peroxide and ozone. Further, the pH of the solution may be raised by adding compounds of alkali earth metals, such as sodium hydroxide, sodium carbonate, among others. The temperature of the reaction ranges from about 20 °C to about 100 °C, and the reaction time is about 1 min to about 100 hours. The operating conditions, such as temperature, pH, and duration, may be controlled to optimize the FePO4precipitation performance.

[0060] The resulting slurry is then subjected to a solid / liquid separation process, such as filtration, resulting in a filter cake containing crude FP 112 & 214 and a lithium-rich solution or filtrate 114. The filtrate 220 is separated from the slurry by filtration by the step of 204. The filtrate 114 and the filtrate 220 are fed to the lithium recovery and purification step, which will be discussed further below. At the same time, the filter-cake or FP precipitates may be rinsed to minimize the loss of lithium. The rinsing solution may be reused to reduce water consumption and increase lithium recovery. The crude FP 112 & 214 may be further processed to obtain battery-grade FP, which will be discussed further next.

[0061] Embodiments disclosed herein are directed to a FP aging and refinery method 116 & 216 for producing battery-grade FP 118 & 218 through impurity removal, crystallinity enhancement, and physical property adjustment of the crude FP precipitates 112 & 214.The crude FP 112 & 214 may be mixed with an acid solution of an appropriate concentration. The resulting slurry may be continuously stirred to ensure the precipitate particles are uniformly dispersed in the solution. In one or more embodiments, the acid concentration of the solution ranges from about 0.1% to about 50%. In some embodiments, the liquid medium includes, but is not limited to, H2SO4, HCl, HNO3 or H3PO4, or combinations thereof. In one or more embodiments, the temperature of the reaction is about 20 °C to about 100 °C, and the reaction time is about 1 hour to 24 hours. In one or more embodiments, surfactants, such as polyethylene glycol, triethanolamine, stearic acid, polysorbate, and Tween®, can be added to regulate the physical properties of the particles. In one or more embodiments, the iron phosphate may be washed multiple times using an appropriate solution, examples of which include, but are not limited to, deionized water, hydrogen peroxide, and a dilute acid solution such as H2SO4, HCl, HNO3, H3PO4, or combinations thereof.

[0062] During the aging and refinery processes 116 & 216, the crude FP precipitates are redissolved and entrained contaminants are released. In the meantime, FP precipitates with higher crystallinity may be formed due to the re-precipitation of the redissolved iron and phosphate followed by crystallization. It is worth mentioning that precipitation and aging steps can be merged into one step. After FP aging, solid / liquid separation may be performed on the slurry by filtration. The precipitates or filter-cake may be rinsed and filtered multiple times in the rinsing and separation process for further purification. Advantageously, the rinsing solution may be re-used in previous steps to reduce water consumption. Water in the filter-cake from the filtration process may be removed by drying to produce battery-grade FP 118 & 218.

[0063] The lithium-rich solutions 114 & 220 may be further processed and purified by removing contaminants through precipitation, filtration, and a purification process 120 & 222. In one aspect, the pH adjusting agent used in this step includes, but is not limited to, NaOH, Na2CO3, KOH, K2CO3, LiOH, Li2CO3, CaO, Ca(OH)2, and CaCO3. In another aspect, the pH is adjusted in the range of about 3.0 to about 14.0. In a further aspect, the pH adjustment is conducted at the temperature range of about 10 °C to about 100 °C for a time of about 1 minute to about 24 hours. Those having ordinary skills in the art willappreciate that the chemicals listed herein are examples and the contaminants may be removed using other chemicals not listed herein.

[0064] After contaminants removal 120 & 222, lithium-rich solutions may be further subjected to lithium extraction 122 & 224 to further concentrate and purify lithium. Solvent extraction may be used to achieve the objective.

[0065] After lithium extraction 122 & 224, lithium in the treated solutions may be precipitated through mechanical vapor recompression (MVR) evaporation and carbonate precipitation, resulting in a crude lithium carbonate product 124 & 226. MVR can significantly reduce the amount of energy needed to drive the evaporation process. This can lead to considerable energy and cost savings, making it an attractive method for high- efficiency evaporation.

[0066] During the crude lithium carbonate refinery 124 & 226, lithium carbonate in the crude product may be redissolved and refined in a solution saturated with CO2in the form of lithium bicarbonate, while any contaminant precipitates in the crude lithium carbonate product remain undissolved and may be removed by filtration. Lithium bicarbonate in the solution may be converted to lithium carbonate precipitates by eliminating CO2 from the solution. After solid / liquid separation, high-purity battery-grade lithium carbonate 120 may be produced from the lithium bicarbonate solution by removing CO2 from the solution by, for example, heating or depressurization.

[0067] The embodiments described above may be relied on for the following: A method for lithium iron phosphate battery (LFP) and lithium manganese iron phosphate (LMFP) battery recycling, the method including: discharging, dismantling, crushing / shredding, sieving / sorting, and thermally treating LFP and LMFP batteries or the scraps generated during the LFP and LMFP battery manufacturing process, leading to a material that contains cathode and anode materials along with some contaminants; dissolving the material to obtain a solution containing lithium, iron, phosphate, and contaminants; removing contaminants from the solution, resulting in a second solution; precipitating iron phosphate from the second solution, leading to a crude iron phosphate product and a third solution rich in lithium; modifying the crude iron phosphate product to obtain a battery- grade iron phosphate product; further removing remaining contaminants from the thirdsolution, leading to a fourth solution rich in lithium with minimal impurities; concentrating and further purifying the fourth solution to obtain battery-grade lithium carbonate.

[0068] The method may further include dissolving the material in two steps to obtain a solution containing lithium, iron, phosphate, plus contaminants, respectively. The material may be dissolved in water with certain a solid to liquid ratio, with the addition of an acid. The solid to liquid ratio may range from about 1:2 to about 1:10. The acid used is H2SO4, HCl, HNO3 or H3PO4. The reaction temperature may be in the range of about 20 °C to 100 °C. The contaminant removal from the solution may consist of de-Cu and de-Al steps. The reaction temperatures may range from about 20 C to about 80 C.

[0069] The Cu may be removed by adding reducing agents like iron powder into the solution with about 10-50% extra of theoretical amount. The Cu can also be removed by other methods, such as solvent extraction. The Al may be removed by adding the de-Al agents, including but not limited to the combination of sodium fluoride, potassium fluoride, ammonium fluoride and lithium fluoride or one of the fluorides. To ensure an efficient and complete Al removal, pH should be adjusted to the range of about 0.1 to about 5.0 by using a pH adjusting agent. The pH adjusting agent includes but not limited to NaOH, Na2CO3, KOH, K2CO3, LiOH, Li2CO3, ammonia, and Fe powder.

[0070] The Al may be removed by other methods, such as solvent extraction and adsorption. The crude iron phosphate may be obtained with an addition of an oxidizing agent with or without a base. The oxidizing agent may include, but is not limited to, hydrogen peroxide and ozone, the base includes but is not limited to sodium hydroxide, sodium carbonate, potassium hydroxide, and potassium carbonate. The temperature of the reaction is about 20 C to about 100 C, and the reaction time is about 1 min to about 100 hours.

[0071] The modification of the crude iron phosphate may involve treating the crude iron phosphate in a liquid medium. The liquid medium may include but is not limited to an acid solution with a concentration of about 0.1% to about 50%. The acid may be H2SO4, HCl, HNO3 or H3PO4, or combination of two or a few of the above acid mentioned. The temperature of the reaction is about 20 C to about 100 C, and the reaction time is about 1 hour to about 24 hours. The surfactants, such as polyethylene glycol, triethanolamine,stearic acid, and Tween, may be added to regulate the physical properties of the particles. The iron phosphate may be washed multiple times using an appropriate solution, including but is not limited to deionized water, hydrogen peroxide, and a dilute acid solution, such as H2SO4, HCl, HNO3 or H3PO4, or combination of two or a few of the above acid mentioned.

[0072] The battery-grade iron phosphate product may be directly obtained without modification by using surfactants or aging. The third solution may be purified by adjusting the pH. The pH adjusting agent includes but is not limited to NaOH, Na2CO3, KOH, K2CO3, CaO, Ca(OH)2, CaCO3. The pH may be adjusted to the range of about 3.0 to about 14.0. The pH adjusting may be conducted at the temperature range of about 10 °C to about 100 °C for a time of about 1 minute to about 24 hours. After purification, filtration may follow.

[0073] In another aspect, embodiments disclosed herein relate to a method for lithium iron phosphate battery recycling, the method including: discharging, dismantling, crushing / shredding, sieving / sorting, and thermally treating lithium iron phosphate (LFP) and lithium manganese iron phosphate (LMFP) batteries or the scraps generated during the LFP and LMFP battery manufacturing process, leading to a material that contains cathode and anode materials along with some contaminants; selectively dissolving the part of material to obtain a lithium containing solution with some contaminants, removing contaminants from the solution, resulting in a second lithium solution; dissolve the unleached solid to form the third solution, purifying the third solution to form the fourth solution, precipitating iron phosphate from the fourth solution, leading to a crude iron phosphate product; modifying the crude iron phosphate product to obtain a battery-grade iron phosphate product; further removing remaining contaminants from the second solution, leading to a fifth solution rich in lithium with minimal impurities; concentrating and further purifying the fifth solution to obtain battery-grade lithium carbonate.

[0074] The material may be dissolved in water with a certain solid to liquid ratio, with the addition of an acid and in the presence of an oxidizing agent. The solid to liquid ratio ranges from about 1:2 to about 1:10. The acid used may be H2SO4, HCl, HNO3or H3PO4. The oxidizing agent used may include, but is not limited to one of hydrogen peroxide, oxygen,and ozone or the combination of them. The first solution can be purified using a single approach or a combination of different approaches. The first solution may be purified by adjusting the pH. The pH adjusting agent may include but is not limited to NaOH, Na2CO3, KOH, K2CO3, CaO, Ca(OH)2, CaCO3. The pH may be adjusted to the range of about 3.0 to about 14.0. The pH adjusting may be conducted at the temperature range of about 10 °C to about 100 °C for a time of about 1 minute to about 24 hours. After purification, filtration may follow.

[0075] The unleached solid may be dissolved to form a third solution in water with a certain solid to liquid ratio, with the addition of an acid. The solid to liquid ratio ranges from about 1:2 to about 1:10. The acid used may be H2SO4, HCl, HNO3or H3PO4. The contaminant removal from the third solution may consist of de-Cu and de-Al steps. The reaction temperature ranges from about 20 C to about 80 C. The Cu may be removed by adding reducing agents like iron powder into the solution with about 10-50% extra of theoretical amount. The Cu may also be removed by other methods, such as solvent extraction.

[0076] The Al may be removed by adding the de-Al agents, including but not limited to the combination of sodium fluoride, potassium fluoride, ammonium fluoride and lithium fluoride or one of the fluorides. To ensure an efficient and complete Al removal, pH may be adjusted to the range of 0.1-5.0 by using the pH adjusting agent. The pH adjusting agent includes but is not limited to NaOH, Na2CO3, KOH, K2CO3, LiOH, Li2CO3, ammonia, and Fe powder. The Al may be removed by other methods, such as solvent extraction and adsorption. The crude iron phosphate product may be produced from the fourth solution following steps described in the previous embodiment. The crude iron phosphate product can be modified following steps described in the previous embodiment.

[0077] Example 1 – Impurity Removal

[0078] The leachate that was obtained by dissolving the raw material with a sulfuric acid solution contained 7760 mg / L of Al and 2000 mg / L of Cu. The leachate was first subjected to the de-Cu step by adding Fe powder. After that, the leachate was transferred to a reactor for de-Al. The temperature of the leachate was maintained at about 20 °C to about 70 °C. The pH of the leachate was raised to about 1 to about 2 by adding the material generatedfrom spent lithium-ion iron phosphate batteries by crushing, shredding, and sorting. The resulting suspension was filtered using a filter press. The resulting filtrate is then subjected to pH raise to about 2.0 to about 3.0 by adding calcium oxide. After reacting for about 15 min to about 30 min, a filtration aid was added, and the suspension was filtered using a filter press. The filtrate contained only 9 mg / L of Al, which is much lower than the original leachate, indicating the efficiency of the de-Al step.

[0079] Example 2 – Battery-grade FePO4Production

[0080] The leachate, after undergoing de-Cu and de-Al treatments, was first oxidized by purging the solution with ozone for a period of 10 minutes. Following oxidization, the leachate was heated to around 90 °C, and the pH of the solution was raised to around 2. The leachate was left to stand for four hours. Iron phosphate was formed during the standing process. Subsequently, the resulting suspension was filtered, leading to a filter cake and a filtrate. The filter cake was transferred to a container, and a certain volume of an acid solution was added. The mixture was agitated for 1 hour using an overhead stirrer. Afterwards, the suspension was filtered using a press filter. The resulting filter cake was rinsed two more times following exactly the same procedure as the first time. Following the first 3 washing, the FePO4 precipitation was washed three more times using deionized water and following the same procedure as the acid washing. The chemical compositions of the resulting FePO4product are shown in Table 1. The quality of the product reached battery grade. Additionally, as shown in FIG. 3, the product has high sphericity. The appearance of the FePO4product is shown in FIG.4.

[0081] Example 3 – Non-selective method recycling

[0082] 250 grams of black mass obtained from spent lithium-ion iron phosphate batteries was mixed with 1 liter of deionized water. Afterwards, sulfuric acid was added to drop the pH to about 0.2, followed by stabilizing at this pH for 2 hours at approximately 70 C. After the reaction, the suspension was filtered using a vacuum filter, leading to a filter cake and leachate. Subsequently, about 125 grams of black mass was added to the leachate to bring the pH to about 0.8 at approximately 70 C. The suspension was filtered using a vacuum filter. The resulting leachate contained 14,000 mg / L Li, 112,000 mg / L Fe, 65,000 mg / L P, 1,000 mg / L Al, 800 mg / L Cu, and other contaminants. The leachate was subjectedto impurity removal and FePO4 preparation steps following the procedures described in Examples 1 and 2. After these steps, in addition to lithium, the leachate still contained 2,000 mg / L Fe, 2,000 mg / L P, and some minor contaminants. To avoid being carried to the final lithium carbonate product, these species were eliminated by enhancing the pH of the leachate to about 12 by adding sodium hydroxide. The dominant species in the leachate after the pH raise were primarily 6,000 mg / L Li and 30,000 mg / L Na. To separate Li from Na, the leachate was fed to a solvent extraction system, consisting of 1 stage of acid regeneration, 1 stage of saponification, 4 stages of extraction, 3 stages of acid scrubbing, and 2 stages of water scrubbing. The organic phase loaded with high-purity lithium was further processed to generate a battery-grade lithium carbonate. The appearance of the lithium carbonate product is shown in FIG.4. The elemental composition of the product is shown in Table 4. As can be seen, the product meets battery grade.

[0083] Example 4 – Selective leaching recycling method

[0084] 250 grams of black mass obtained from spent lithium-ion iron phosphate batteries was mixed with 1 liter of deionized water. Afterward, 200 mL of hydrogen peroxide was added to the suspension, and the reaction lasted approximately 1 hour. Subsequently, sulfuric acid was added to the slurry to reduce the pH to about 1.2. The slurry was then filtered using a vacuum filter, leading to a filtrate rich in Li and some other species (e.g., 2,000 mg / L Fe, 2,000 mg / L P). The pH of the filtrate was raised to about 12 by adding sodium hydroxide to remove the undesired species. The dominant species in the leachate after the pH rise were primarily 10,000 mg / L Li and 40,000 mg / L Na. To separate Li from Na, the leachate was fed to a solvent extraction system, consisting of 1 stage of acid regeneration, 1 stage of saponification, 4 stages of extraction, 3 stages of acid scrubbing, and 2 stages of water scrubbing. The organic phase loaded with high-purity lithium was further processed to generate a battery-grade lithium carbonate. The filter cake was mixed with 1 liter of deionized water and added sulfuric acid to reduce the pH to about 0.2. The resulting slurry was filtered using a vacuum filter to obtain a filtrate containing primarily Fe (30,00mg / L) and P (17,000 mg / L), as well as some contaminants. The filtrate was processed following the procedures described in Example 1 to remove impurities.Afterward, the filtrate was further processed following the procedures described in Example 2 to generate battery-grade iron phosphate. Table 1. Chemical compositions of the FePO4- 2H2O product produced using the disclosed technologyTable 2. Chemical compositions of the Li2CO3 product produced using the disclosed technology.

[0085] Although only a few example embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the example embodiments without materially departing from this invention. Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. Thus, although a nail and a screwmay not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures. It is the express intention of the applicant not to invoke 35 U.S.C. § 112 (f) for any limitations of any of the claims herein, except for those in which the claim expressly uses the words ‘means for’ together with an associated function.

Claims

CLAIMS What is claimed is:

1. A method for recycling spent or scrap lithium iron phosphate (LFP) or lithium manganese iron phosphate (LMFP) battery materials comprising: selectively leaching a black mass with an acid and optionally an oxidizing agent, to form a mixture of leachate and a first filter cake, wherein the black mass comprises the spent or scrap LFP or LMFP battery materials; selectively removing titanium, copper and aluminum from the leachate to form a filtrate comprising ferrous ions; oxidizing the filtrate comprising ferrous ions at a temperature ranging from 20 °C to 100 °C to form a crude iron phosphate and a lithium-rich solution; purifying the crude iron phosphate at a temperature ranging from about 20°C to about 100 °C to form a battery grade iron phosphate; and processing a lithium rich solution to form battery grade lithium carbonate.

2. The method of claim 1, wherein the selectively removing copper from the leachate comprises: adding iron powder to the leachate at a temperature ranging from 20 °C to 100 °C; extracting copper from the leachate with a solvent; or adsorbing cooper from the leachate.

3. The method of claim 2, wherein the iron powder is added in an amount of 10-50% theoretical excess.

4. The method of any one of claims 1 to 3, wherein the selectively removing aluminum comprises: adding complexing agents to the leachate; or performing selective ion exchange with the leachate, wherein the complexing agents comprise alkali metal compounds, fluoride compounds capable of complexing with aluminum, or mixtures thereof.

5. The method of claim 4, wherein the fluoride compounds are selected from the group consisting of sodium fluoride, potassium fluoride, ammonium fluoride, lithium fluoride, and combinations thereof.

6. The method of claim 4 or 5, wherein the adding of complexing agents is performed at a pH ranging from 1 to 3.

7. The method of any one of claim 1 to 6, wherein the oxidizing the filtrate comprises: treating the filtrate comprising ferrous ions with an oxidizing agent and optionally an alkali earth metal to form a slurry; separating the slurry to isolate the crude iron phosphate; and rinsing the crude iron phosphate.

8. The method of any one of claims 1 to 7, wherein the oxidizing the filtrate is performed for a time period ranging from 1 min to 100 hours.

9. The method of any one of claims 1 to 8, wherein the purifying the crude iron phosphate comprises at least one of the following steps to form a slurry: mixing the crude iron phosphate with a solution comprising 0.1 wt% to 50 wt% acid; treating the crude iron phosphate with a surfactant; or repeatedly washing the crude iron phosphate with a rinsing solution.

10. The method of claim 9, further comprising, filtering and drying the slurry to provide the battery grade iron phosphate.

11. The method of claim 9 or 10, wherein the mixing the crude iron phosphate with the acid solution comprises mixing from 0.1% to 50 wt% acid solution at a temperature ranging from 20 °C to 100 °C, for a period of time ranging from 1 hour to 24 hours.

12. The method of claim 9, wherein the surfactant is selected from the group consisting of of polyethylene glycol, triethanolamine, stearic acid, polysorbate, and combinations thereof.

13. The method of claim 9, wherein the rinsing solution comprises deionized water, hydrogen peroxide, a dilute acid solution, or combinations thereof.

14. The method of any one of claim 1 to 13, wherein the selectively leaching the black mass comprises: filtering the mixture to isolate the first filter cake and to collect a lithium-rich solution; and treating the first filter cake with the acid to form a solution comprising iron and phosphate as the leachate.

15. The method of any one of claim 1 to 14, wherein the processing the lithium filtrate comprises: removing contaminants from the lithium-rich solution; extracting lithium from the lithium-rich solution to form lithium in a treated solution; and precipitating crude lithium carbonate from the lithium in the treated solution.

16. The method of claim 15, wherein the removing contaminants comprises: adjusting a pH of the lithium-rich solution to a range of 3 to 14 at a temperature ranging from about 10°C to about 100°C, for a time period ranging from 1 min to 24 hours.

17. The method of claim 15, wherein the extracting lithium from the lithium-rich solution comprises extracting lithium with a solvent to form the lithium in the treated solution.

18. The method of claim 15, wherein the precipitating crude lithium carbonate comprises: performing mechanical vapor recompression on the lithium in the treated solution; adding a solution saturated with CO2to the treated solution to form a lithium bicarbonate solution; and precipitating the battery grade lithium carbonate from the lithium bicarbonate solution.

Images