Recovery of Critical Elements from Expired Lithium-Ion Batteries Using Supported Membrane Solvent Extraction

Abstract

Single- and multi-stage systems and methods are provided for recovering critical elements in substantially pure form from lithium-ion batteries. The systems and methods involve supported membrane solvent extraction using an immobilized organic phase within the pores of a permeable hollow fiber. The permeable hollow fiber is contacted on one side with a feed solution and on the other side with a strip solution, providing simultaneous extraction and stripping of elements from dissolved lithium-ion positive electrode material while excluding other elements from the feed solution. The single- and multi-stage systems and methods are capable of selectively recovering cobalt, manganese, nickel, lithium, aluminum, and other elements from spent battery positive electrodes and are not limited by equilibrium constraints compared to conventional solvent extraction processes.

Description

[Technical field]

[0001] This invention was made with Government support under Contract No. DE-AC05-00 OR 22725 awarded by the U.S. Department of Energy. The Government retains certain rights in this invention.

[0002] FIELD OF THE PRESENT APPLICATION The present invention relates to the recovery of key elements in their pure form from expired lithium ion batteries, and more particularly to the recovery and separation of cobalt, nickel, manganese, lithium and / or other elements using supported membrane solvent extraction. [Background technology]

[0003] In recent years, lithium-ion batteries have attracted much attention worldwide due to their wide use in portable electronic devices and electric vehicles. Lithium-ion batteries are smaller and lighter, have no memory effect, and provide more energy per unit volume than traditional nickel-cadmium (Ni-Cd) or nickel-metal hydride (NiMH) batteries.

[0004] Cobalt is considered a critical material and is used in significant and growing quantities in lithium-ion batteries. Currently, the world's above-ground cobalt resources are estimated at approximately 25 million tonnes. The most abundant source of cobalt is mainly located within the Democratic Republic of Congo. Cobalt mining takes place within the country, and the country currently supplies 54% of the world's cobalt demand, while China, Russia, and Australia each contribute approximately 5% of the global cobalt demand. Thirty percent of the current cobalt supply is consumed by the lithium-ion battery industry. Lithium-ion batteries are therefore considered an important secondary resource for the extraction and recovery of cobalt. Furthermore, the presence of metal contaminants in waste generated from used lithium-ion batteries may have adverse environmental effects.

[0005] Conventional solvent extraction methods have been used commercially to recover cobalt from primary, secondary and expired battery cathode materials. However, conventional methods have limitations such as large solvent inventories, emulsion formation and multi-step operations including stripping and scrubbing. Non-dispersive solvent extraction methods using supported liquid membranes with known extractants such as Cyanex 272 and Cyanex 301 have been proposed for the separation of cobalt in the presence of nickel and manganese. Swain et al. (Chemical Engineering Journal, 2015. 271, p. 61-70) investigated the separation of cobalt by hollow fiber and flat sheet supported liquid membrane solvent extraction using Cyanex 272 as the extractant. The feed solutions used in this work were salts of cobalt and lithium such as cobalt sulfate and lithium sulfate dissolved in sulfuric acid. However, the chemistry of cobalt in lithium-ion batteries is much more complicated than divalent cobalt salts. Summary of the Invention [Problem to be solved by the invention]

[0006] Thus, there remains a need for improved methods and systems for recovering cobalt and other elements from lithium-ion batteries using supported liquid membrane solvent extraction. In particular, the LiCoO 2 and LiNiCoMnO 2 There remains a need for improved methods and systems for selectively recovering constituent elements in substantially pure form from (nickel-manganese-cobalt or NMC) positive electrodes. [Means for solving the problem]

[0007] A method and system are provided for recovering elements in substantially pure form from lithium ion batteries. The method and system include supported membrane solvent extraction using an immobilized organic phase within the pores of a permeable hollow fiber to selectively extract elements from a feed solution having a controlled pH. The permeable hollow fiber is in contact with an aqueous feed solution on one side and a strip solution on another side, providing simultaneous extraction and stripping of elements from the dissolved lithium ion positive electrode material while excluding other elements from the feed solution.

[0008] In one embodiment, the method includes wetting the pores of a plurality of hollow fibers with an organic phase having a cationic liquid extractant and an organic solvent. The method then includes moving an aqueous feed solution along one side of the hollow fibers, the aqueous feed solution containing dissolved cobalt-containing battery material, such as LiCoO. 2 or LiNiCoMnO 2 The method includes simultaneously moving a strip solution along the other side of the hollow fibers, and the aqueous feed solution is pressurized ( Approximately 13.7895kPa( About 2 psig ) ) in which an ionic liquid extractant in the pores of multiple hollow fibers continuously extracts Co(II) from an aqueous feed solution for recovery by a strip solution.

[0009] In another embodiment, the system includes a membrane module, a feed reservoir, and a strip reservoir. The membrane module includes a plurality of hollow fibers, the pores of which are wetted (pre-impregnated) with the organic phase to be immobilized. The feed reservoir and the strip reservoir contain an aqueous feed solution and a strip solution, respectively, which are continuously recirculated through the membrane module. The aqueous feed solution is directed along the lumen side of the hollow fibers, and the strip solution is directed along the shell side of the hollow fibers, optionally in a transverse flow direction. In another embodiment, the aqueous feed solution is directed along the shell side of the hollow fibers, and the strip solution is directed along the lumen side of the hollow fibers. The aqueous feed solution includes a cobalt-containing battery material and is pressurized relative to the strip solution. The organic phase within the pores of the hollow fibers contains an organic solvent and a cation extractant, such as Cyanex 272 or Cyanex 301, selected to continuously extract cobalt (e.g., Co(II)) from the aqueous feed solution for recovery by the strip solution.

[0010] The method and system of the present invention can facilitate the simultaneous extraction and stripping of cobalt and other elements from lithium-ion cathode materials using an immobilized organic phase within the pores of hollow fibers. For example, the multi-stage system described in this disclosure can selectively recover cobalt, manganese, nickel, and lithium from the cathodes of spent batteries. The system and method described in this disclosure is not limited by equilibrium constraints compared to conventional solvent extraction processes. A non-dispersive solvent extraction method using a supported liquid membrane with a cation extractant has been demonstrated by the inventors in laboratory examples to recover key elements in substantially pure form, including pretreatment of the cathode and anode prior to supported membrane solvent extraction.

[0011] These and other features of the present invention will become apparent from the following description of the invention when considered in light of the accompanying drawings and the appended claims. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is an illustration of a membrane module in accordance with the systems and methods of the present invention.

[0013] [Diagram 2] FIG. 2 is an illustration of a single stage system including the membrane module of FIG.

[0014] [Diagram 3] FIG. 3 is an illustration of a two-stage system including the membrane module of FIG.

[0015] [Figure 4] FIG. 4 is an illustration of a three-stage system including a pretreatment process and a membrane solvent extraction process, including the membrane module of FIG.

[0016] [Diagram 5] FIG. 5 is an illustration of a three-stage system including the membrane module of FIG.

[0017] [Figures 6A-6E] Figures 6(a)-6(e) illustrate the recovery of Co from LiCoO2 for Example 1. Figure 6(a) shows the concentration of the feed solution, Figure 6(b) shows the concentration of the strip solution, Figure 6(c) shows the purity (%) of Co in the feed and strip, Figure 6(d) shows the Co recovery over time, and Figure 6(e) shows the Co extraction over time.

[0018] [Figure 7A-7E] Figures 7(a)-7(e) illustrate the recovery of Co from LiCoO2 for Example 2 at higher initial Co concentrations than depicted in Figures 6(a)-6(f). Figure 7(a) shows the feed solution concentrations, Figure 7(b) shows the strip solution concentrations, Figure 7(c) shows the % purity of Co in the feed and strip, Figure 7(d) shows the Co recovery over time, and Figure 7(e) shows the Co extraction over time.

[0019] [Figure 8A-8B] Figures 8(a)-8(b) illustrate the first stage recovery of Co from NMC for Example 3. Figure 8(a) shows the concentrations of the feed solution and Figure 8(b) shows the concentrations of the strip solution. [Fig. 8C-8E] Figures 8(c)-8(e) illustrate the first stage recovery of Co from NMC for Example 3. Figure 8(c) shows the purity (%) of Co in the feed and strip, Figure 8(d) shows the Co recovery over time, and Figure 8(e) shows the Co extraction over time.

[0020] [Figure 9A-9B] Figures 9(a)-9(b) illustrate the second stage recovery of Co from NMC for Example 3. Figure 9(a) shows the concentrations of the feed solution and Figure 9(b) shows the concentrations of the strip solution. [Fig. 9C-9E] Figures 9(c)-9(e) illustrate the second stage Co recovery from NMC for Example 3. Figure 9(c) shows the % Co purity in the feed and strip, Figure 9(d) shows the Co extraction rate, and Figure 9(e) shows the Co extraction rate over time.

[0021] [Figure 10A-10E] Figures 10(a)-10(e) illustrate the first stage separation of Co and Mn from Ni and Li for Example 4. Figure 10(a) shows the concentration of the strip solution over time, Figure 10(b) shows the concentration of the feed solution over time, Figure 10(c) shows the purity (%) of Co in the feed and strip solutions over time, Figure 10(d) shows the Co recovery over time, and Figure 10(e) shows the Co extraction over time.

[0022] [Figures 11A-11E]Figures 11(a)-11(e) illustrate the second stage separation of Co from Mn for Example 4. Figure 11(a) shows the concentration of the strip solution over time, Figure 11(b) shows the concentration of the feed solution over time, Figure 11(c) shows the purity (%) of Co in the feed and strip solutions over time, Figure 11(d) shows the Co recovery over time, and Figure 11(e) shows the Co extraction over time.

[0023] [Fig. 12A-12E] Figures 12(a)-12(e) illustrate the third stage separation of Ni from Li for Example 4. Figure 12(a) shows the concentration of the strip solution over time, Figure 12(b) shows the concentration of the feed solution over time, Figure 12(c) shows the purity (%) of Ni in the feed and strip solutions over time, Figure 12(d) shows the Ni recovery over time, and Figure 12(e) shows the Ni extraction over time.

[0024] [Figure 13] FIG. 13 includes a scanning electron microscopy (SEM) image of the cobalt oxide separated from the cathode material in Example 4.

[0025] [Figure 14] FIG. 14 includes an energy dispersive X-ray spectroscopy (EDS) of the cobalt oxide separated from the cathode material in Example 4.

[0026] [Figure 15] FIG. 15 includes an X-ray diffraction (XRD) of the cobalt oxide separated from the cathode material in Example 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] The invention contemplated and disclosed in this disclosure includes a method and system for the recovery of constituent elements from lithium ion batteries by membrane assisted solvent extraction. In general, the method includes the following steps for single-stage or multi-stage extraction of one or more constituent elements: a) providing a membrane module including a plurality of porous hollow fibers; b) wetting the plurality of porous hollow fibers with an organic phase including a cation extractant and an organic solvent; c) applying a continuous flow rate of an acidic aqueous feed solution at a predetermined pH along the lumen side or shell side of the plurality of porous hollow fibers; and d) applying a continuous flow rate of an acidic strip solution at a predetermined pH along the other of the lumen side or shell side of the plurality of porous hollow fibers. The step of wetting the plurality of porous hollow fibers (step (b)) is performed prior to the steps of applying a flow rate of the feed solution and a flow rate of the strip solution (steps (c) and (d)). The steps of applying a flow rate of the feed solution and a flow rate of the strip solution are generally performed simultaneously. These steps are described below with respect to single stage separation (Part I) and multi-stage separation (Part II).

[0028] I. Single stage separation Providing a membrane module generally involves providing a plurality of hollow or tubular fibers extending between opposing tube sheets. By way of example, a membrane module containing fiber bundles is shown in FIG. 1 and generally designated 10. Membrane module 10 includes an outer casing 12 that includes a feed input port 14, a feed output port 16, a strip input port 18, and a strip output port 20. A suitable membrane module has a membrane module area of ​​1.4 m 2Examples of suitable membrane modules include hydrophobic polypropylene membrane modules (MicroModule® from Membrana GmbH or MiniModule® from Membrana-Charlotte, LLC). A plurality of hollow fibers 22 are inserted at their opposite ends into first and second tube sheets 24, 26 such that the plurality of hollow fibers 22 extend in a common direction. Each fiber 22 includes a lumen side 28 and a shell side 30. Although the lumen side 28 is illustrated in FIG. 1 as being exposed to the feed solution, in other embodiments, the lumen side 28 is exposed to the strip solution. Similarly, although the shell side 30 is illustrated in FIG. 1 as being exposed to the strip solution, in other embodiments, the shell side 30 is exposed to the feed solution. As used in this disclosure, "lumen side" includes the interior surface that defines a channel that extends longitudinally through the length of the hollow fiber, and "shell side" includes the exterior surface of the fiber, with the lumen side and shell side separated from each other by the thickness of the membrane sidewall. The side in contact with the feed solution defines the "feed interface" and the side in contact with the strip solution defines the "strip interface." The lumen side is the feed interface in some embodiments and the strip interface in other embodiments. Similarly, the shell side is the strip interface in some embodiments and the feed interface in other embodiments.

[0029] The hollow fibers 22 are porous to retain the organic phase therein and are formed of a material that can withstand the acidic conditions of the feed and strip solutions. The hollow fibers 22 may be formed of a hydrophobic material that helps prevent wetting of the fibers by the aqueous feed solution and can also prevent migration of the organic phase into the strip solution. Hydrophobic materials include, for example, polypropylene, polyethylene, polyvinylidene fluoride, polyetheretherketone, polysulfone, or polyethersulfone. The pore size is determined so that the organic phase containing the extractant is able to penetrate the fiber at a higher pressure than the strip side of the fiber. Approximately 13.7895kPa ( Approximately 2psi ) A high pressure, optionally higher than the pressure of the strip solution 34.4738kPa( 5 psi )The hollow fibers are selected so that they are not displaced by contact with the pressurized feed solution at less than high pressure. In some embodiments, the hollow fibers comprise an average pore size of less than 0.1 microns, while in other embodiments, the average pore size is between 0.01 microns and 0.1 microns. The hollow fibers comprise an average inner diameter of between 0.1 mm and 1.0 mm, and optionally between 0.2 mm and 0.3 mm. The hollow fibers comprise an average outer diameter of between 0.1 mm and 1.0 mm, and optionally between 0.6 mm and 0.7 mm. The hollow fibers have an average sidewall thickness of between 0.01 mm and 0.1 mm, and optionally between 0.02 mm and 0.03 mm.

[0030] Wetting the plurality of porous fibers with an organic phase generally involves directing the organic phase through the feed input port 14 for a predetermined period of time (e.g., 1 hour) to saturate the fibers with the organic phase. The flow of the organic phase is stopped after a sufficient period of time to obtain an immobilized organic phase within the pores of the plurality of fibers. After wetting, distilled water is circulated through both input ports 14, 18 to flush excess organic phase from the membrane module 10. The immobilized organic phase includes a cation extractant (described below) and an organic solvent. The organic solvent includes synthetic isoparaffinic hydrocarbon solvents, such as Isopar-L (Exxon Mobile Corporation). In other embodiments, other immobilized organic phases can be used if desired. Optionally, the immobilized organic phase includes tributyl phosphate (TBP), although TBP is not required and in some embodiments, the immobilized organic phase does not include TBP. This is because TBP is conventionally used in solvent extraction processes to prevent the formation of a third phase, which is the separation of the organic phase into two liquids as observed in the form of an emulsion. The third phase is generally due to the limited solubility of the extractant in the organic diluent and the high acid strength used in the feed and stripping solutions. There is no formation of a third phase in the present membrane solvent extraction process because the amount of organic phase embedded in each pore of the hollow fiber membrane is very small. Furthermore, a dilute acid solution is used in the membrane solvent extraction process, which prevents emulsion formation. Therefore, it is not necessary to include TBP in the organic phase, and in many embodiments, TBP is not used.

[0031] The extractant, when used in accordance with the systems and methods described herein, can be selected to recover certain elements while excluding other elements. For example, the extractant can include bis(2,4,4-trimethylpentyl)phosphinic acid (Cyanex 272, Cytec Inc.) or methylpentylphosphinodithioic acid (Cyanex 301, Cytec Inc.). The extractant can include Cyanex 272 to extract Co and Mn from a feed solution having a pH between 4.0 and 6.0, and optionally between 5.0 and 6.0, while excluding Ni and Li. Also by way of example, the extractant can include Cyanex 272 to extract Co from a feed solution having a pH between 5.0 and 6.0, and more specifically about 5.9, while substantially excluding Li. Also by way of example, the extractant can include Cyanex 272 to extract Ni from a feed solution having a pH between 6.0 and 7.5, and more specifically between 6.0 and 6.5, while substantially excluding Li. Also by way of example, the extractant can include Cyanex 301 for extracting Co from a feed solution having a pH of 1.5 or less while substantially excluding Mn. Also by way of example, the extractant can include Cyanex 301 for extracting Co and Ni from a feed solution having a pH of 1.0 to 3.0 while substantially excluding Li. High extraction rates are maintained by controlling the drop in pH of the feed solution through the addition of an acetate buffer, e.g., sodium acetate, during the extraction process. As used in this disclosure, "substantially excluding" means that the elemental molarity (moles per liter of solution) of the receiving solution is less than 1% of the elemental molarity (moles per liter of solution) of the donating solution after 1 hour of membrane solvent extraction, unless otherwise stated.

[0032] Directing a continuous flow of an acidic aqueous feed solution along the lumen side or shell side of the plurality of porous hollow fibers includes directing the acidic aqueous feed solution through a feed input port 14. The acidic aqueous feed solution is a solution of dissolved positive electrode material, such as LiCoO2, from spent lithium ion batteries. 2 Positive electrode material and LiNiCoMnO 2 The feed solution includes a (NMC) cathode material. The feed solution has a pH selected based on the extractant. For Cyanex 272, the feed solution can have a pH between 5.5 and 6.0, which includes up to 5% by volume of H as a reducing agent to convert Co(III) to Co(II), which is more soluble than Co(III). 2 O 2 Including 0.2 to 4M H 2 SO 4 This can be achieved by dissolving the cathode material in a 0.1% aqueous solution. In the case of Cyanex 301, the feed solution can have a pH of 1.2-3.0, which contains up to 5% by volume of H2O as a reducing agent to convert Co(III) to Co(II). 2 O 2 Including 0.2 to 4M H 2 SO 4 This can be accomplished by dissolving the cathode material in the membrane solvent. The addition of an acetate buffer, e.g., sodium acetate, maintains a high extraction rate by setting the initial pH of the feed solution, which is adjusted during membrane solvent extraction to be within a predefined range by intermittent addition of a buffer, e.g., sodium acetate, and / or a base, e.g., ammonium hydroxide. The feed solution can alternatively be added with HNO at the desired molar concentration. 3 The feed solution may include a cathode material dissolved in HCl or HCl. The feed solution may be directed through the module 10 along the lumen side 28 of each fiber of the plurality of porous hollow fibers 22 shown in Figure 1. Alternatively, the feed solution may be directed through the module 10 along the shell side 30 of each fiber of the plurality of fibers 22.

[0033] Directing a continuous flow of an acidic aqueous strip solution along the lumen side or shell side of the plurality of permeable fibers for back extraction includes directing the strip solution through a strip input port. The strip solution is adapted to strip Co(II) or other constituent elements that have diffused from the feed interface to the strip interface. The strip solution may, for example, contain H(II) at a higher molar concentration than in the feed solution. 2 SO 4 , HNO 3 , or HCl. That is, a concentration gradient, and therefore a chemical potential gradient, is generally formed between the feed solution and the strip solution. The strip solution is directed through the module 10 along the shell side 30 of each fiber of the plurality of fibers 22 shown in FIG. 1 above, optionally in a direction generally transverse to the flow of the feed solution within the fibers 22. Alternatively, the strip solution can be directed through the interior of the hollow fibers 22 to contact the lumen side 28 thereof.

[0034] To further illustrate the circulation of the feed and strip solutions, FIG. 2 shows a system for membrane assisted solvent extraction, generally designated 40. System 40 includes a feed reservoir 42, a strip reservoir 44, a membrane module 10, a feed line 46, a feed return line 48, a strip line 50, and a strip return line 52. The feed solution is contained within the feed reservoir 42 and is kept under constant agitation by a mechanical stirrer to ensure uniform concentration. The feed line 46 includes a pump 54, e.g., a peristaltic pump, to ensure that the feed line pressure is slightly higher than the strip line pressure. In some applications, the feed is 13.7895kPa( 2 psig ) Hereinafter, optionally, 34.4738kPa( 5 psig )The feed line 50 may be pressurized to less than 100 psi, while the strip may be maintained at atmospheric pressure. The strip line 50 similarly includes a pump 56, a peristaltic pump, to ensure a continuous flow of strip solution through the module 10. The feed solution and strip solution are in continuous recirculation. However, in other embodiments, the feed line and / or strip line form an open circuit.

[0035] The method may also include filtering, drying and / or annealing the strip solution to recover high purity cobalt. For example, the strip solution may be precipitated with oxalic acid or ammonium hydroxide, then filtered, dried at room temperature and annealed. An optional annealing profile may include 750° C. for 2 hours. The steps of filtering, drying and annealing the strip solution are optional, but can be substituted or modified as desired depending on the intended use of the recovered cobalt. The strip solution may alternatively be recycled through the supported membrane solvent extraction module 10 or a second supported membrane solvent extraction module.

[0036] II. Multi-stage separation A two-stage system for cobalt recovery is shown in FIG. 3 and generally designated 60. In this system, a first stage recovery of Co and Mn is performed by using a first membrane module 10, and a second stage recovery of Co is performed by a second membrane module 10'. The first stage recovery includes a first feed reservoir 62, a first membrane module 10, a feed pump 64, a strip pump 66, and a first strip reservoir 66. The second stage recovery includes a second feed reservoir 70, a second membrane module 10', a feed pump 72, a strip pump 74, and a second strip reservoir 76. The first membrane module 10 includes a first immobilized organic phase, e.g., hollow fibers pre-impregnated with Cyanex 272, adapted to recover Co and Mn from dissolved NMC cathode material. The second membrane module 10' includes a second immobilized organic phase adapted to recover Co from a second feed solution. The second feed solution contains Co and Mn from the first strip solution. More specifically, the first membrane module 10 contains an immobilized organic phase comprising Cyanex 272 in Isopar-L, while the second membrane module 10' contains an immobilized organic phase comprising Cyanex 301 in Isopar-L. In this embodiment, the pH of the first feed solution is 5.5-6.0, and the pH of the second feed solution is optionally adjusted with ammonium hydroxide to approximately 2.0.

[0037] A three-stage method for the recovery and separation of Li, Ni, Co, and Mn from spent cathode material is shown in FIG. 4 and includes a pretreatment process 100 and a multi-stage membrane solvent extraction process 102. The spent cathode material 104 in this embodiment includes an active material and an aluminum support. The active material typically contains Li, Ni, Co, and Mn in fine powder form. The fine powder is combined with a polyvinylidene fluoride (PVDF) binder and a carbon additive. The cathode material is then compacted onto an Al support before being incorporated into a lithium-ion battery. Although not shown, the method can also be used to recover copper (Cu) from battery anodes that typically include active material on a copper support. Additionally, Cu and Al present in the cathode material can also be separated and recovered using supported membrane solvent extraction with extractants such as ACORGA M5640 and Cyanex 801.

[0038] The cathode sheet is first subjected to heat treatment 106, acid dissolution 108 and vacuum filtration 110 to remove the PVDF binder and carbon additive. The cathode sheet is heated in an inert atmosphere to a temperature above 500° C. to decompose the PVDF, allowing easy removal of the cathode material from the Al support. In addition, the carbon black present in the cathode material to increase the conductivity of the oxide cathode undergoes a redox reaction at approximately 550° C. This causes partial reduction of the transition metals present in the cathode powder, thereby reducing the H required during acid dissolution 108. 2 O 2 The amount of Al is reduced. Since the melting point of Al is about 650°C, the heat treatment 106 includes a temperature range of 550°C to 650°C (the expression "above and below" as used in this disclosure includes both upper and lower limits). More specifically, the cathode sheet is heated to 570°C in a nitrogen atmosphere by gradually increasing the temperature at a rate of 10°C / min, kept at 570°C for 25 minutes, and the temperature is gradually decreased to room temperature. The cathode sheet is then washed with water to separate the Al support from the cathode powder. After acid dissolution of the cathode powder, the carbon additive present in the cathode material is removed using vacuum filtration 110.

[0039] The multi-stage recovery membrane solvent extraction process 102 is illustrated in Figure 5 and includes a first stage separation of Co and Mn from Li and Ni, a second stage separation of Co from Mn, and a third stage separation of Ni from Li. The first stage separation includes a first feed reservoir 112, a first membrane module 114, and a first strip reservoir 116. The first feed reservoir 112 contains a feed solution, which contains a reducing agent, e.g., up to 5% by volume H 2 O 2 Strong acids, including H 2 SO 4 The feed solution includes the cathode material 104 from the pretreatment process 100 dissolved in the feed solution. The feed solution is stabilized at a pH between 4.0 and 6.0 and includes an acetate buffer, such as a sodium acetate buffer solution. The first membrane module 114 includes hollow fibers pre-impregnated with a first immobilized organic phase including a cation extractant, such as 1M Cyanex 272, and an organic solvent, such as Isopar-L. The organic phase may include 33% by volume Cyanex 272, 5% by volume TBP, and a remaining amount of Isopar-L, although TBP can be omitted without affecting the first stage separation and recovery. For back extraction, the first strip reservoir 116 contains a strong acid, such as 0.75M H2SO4, which is continuously moved through the first membrane module 114. 2 SO 4 H from the strip solution + As a result of ion transfer, the pH of the feed solution decreases, which is countered by the intermittent addition of a buffer, such as sodium acetate, and / or a base, such as ammonium hydroxide, to adjust the pH of the feed solution to between 4.0 and 6.0, and optionally to 5.5. The concentrations of Co and Mn increase over time in the strip solution, with negligible transfer of Li and Ni.

[0040] The second stage separation includes a second feed reservoir 118, a second membrane module 120, and a second strip reservoir 122. The second feed reservoir 118 contains a second feed solution containing a concentration of Co and Mn recovered from the first strip reservoir 116. The second membrane module 120 contains a second immobilized organic phase adapted to recover Co from the second feed solution while substantially excluding Mn. The feed solution is stabilized to a pH of 1.5 or less, e.g., 1.2, by adding a buffer, e.g., sodium acetate, and / or a base, e.g., ammonium hydroxide. The second membrane module 120 contains hollow fibers pre-impregnated with a second immobilized organic phase containing a cation extractant, e.g., 1M Cyanex 301, and an organic solvent, e.g., Isopar-L. The second strip reservoir 122 contains a strong acid, e.g., 1M H, that is continuously transferred through the second membrane module 120 to back-extract Co from the organic phase. 2 SO 4 The Co concentration in the strip solution increases with time, and the migration of Mn is negligible.

[0041] The third stage separation includes a third feed reservoir 124, a third membrane module 126, and a third strip reservoir 130. The third feed reservoir 124 contains a third feed solution containing a concentration of Li and Ni recovered from the first feed reservoir 112. The third membrane module 126 contains a third immobilized organic phase adapted to recover Ni from the first feed solution while substantially excluding Li. The feed solution is stabilized at a pH of 6.0-6.5 by adding a buffer, e.g., sodium acetate, and / or a base, e.g., ammonium hydroxide. The third membrane module 126 contains hollow fibers pre-impregnated with a third immobilized organic phase containing a cation extractant, e.g., 1M Cyanex 272, and an organic solvent, e.g., Isopar-L. The third strip reservoir 130 contains a strong acid, e.g., 0.75M H2SO4, which is continuously transferred through the third membrane module 126 to back-extract Ni from the organic phase. 2 SO 4The Ni concentration in the strip solution increases with time, and the migration of Li is negligible.

[0042] Thus, the methods and systems provide for the recovery and separation of substantially pure cobalt, manganese, nickel and lithium as part of a continuous and scalable recovery process. The methods and systems can overcome removal limitations imposed by equilibrium effects and can recover key elements in extremely pure form as demonstrated by the following examples, which are intended to be non-limiting. EXAMPLES

[0043] Example 1 In one embodiment, 750 mL of 0.2 M H 2 SO 4 10g LiCoO 2 Prepare an aqueous feed solution by dissolving 100% H (Li = 663.86 ppm; Co = 5826.06 ppm) in 100% H 2 O 2 was used as the reducing agent. 250 mL of 3 M sodium acetate buffer solution at pH 5.2 was used to stabilize the pH of the feed solution and reduce the LiCoO 2 The final feed solution concentration was 10 g / L. The organic phase was 33% by volume (1M) Cyanex 272, 5% by volume tributyl phosphate (TBP), and the remaining amount was Isopar-L. The strip solution was 1 L of 0.75 M NaCl. 2 SO 4 The initial pH of the feed was adjusted to 5.02 using ammonium hydroxide. The separation performance of Co is shown in Figures 6(a)-6(e). The Co content of the strip solution increased over time and a Co recovery of 92% was achieved while keeping the passage of Li into the strip solution to a minimum (see Figure 6(b)). Co with a purity of 99.6 wt% was recovered from membrane solvent extraction using Cyanex 272 as the extractant in the organic phase contained in the porous membrane support (see Figure 6(d)). H from the strip solution was removed using 100% Co. +As a result of the ion transfer, the pH of the feed solution decreased from 5.02 to 4.66. The extraction rate of Co decreased over time with decreasing Co concentration in the feed solution (see Figures 6(a), 6(c) and 6(e)).

[0044] Example 2 In another embodiment, the feed solution contains a higher initial concentration of LiCoO 2 In particular, the feed solution contained 0.5MH 2 SO 4 and 2.5% by volume H 2 O 2 and 20,000 ppm LiCoO dissolved in 2 (Li=1486.25ppm; Co=11532.325ppm). The strip solution contained 0.75MH 2 SO 4 The feed solution contained 250 mL of sodium acetate buffer for pH stabilization. The initial pH of the feed solution was adjusted to 5.5. To prevent the decrease in extraction rate with decreasing pH during the experiment, ammonium hydroxide was intermittently added to the feed solution to maintain the pH in the range of 5.5-6.0. The separation performance of Co is shown in Figures 7(a)-7(e). The Co concentration increased in the strip solution, with negligible Li migration, and a Co recovery of 91% was achieved (see Figures 7(b) and 7(d)). Co with a purity of 99.5 wt% was recovered from the membrane solvent extraction using Cyanex 272 as the extractant in the organic phase (see Figure 7(c)).

[0045] Example 3 In this example, a two-stage membrane solvent extraction process was used to separate and recover Co from NMC. In the first stage (module 1 in Figure 3), Cyanex 272 was used to separate Co and Mn because it favors the selective extraction of Co and Mn in the pH range of 5.5-6.0. In the second stage (module 2 in Figure 3), Cyanex 301 was used to separate Co and Mn at feed pH values ​​below 2.

[0046] NMC with a Ni:Co:Mn ratio of 1:1:1 was used as the raw material for the membrane solvent extraction process. 750 mL of 0.5 M H 2 SO 4 The experiment was carried out using 20 g of NMC (Li = 1402.89 ppm; Co = 3698.89 ppm; Mn = 3626.08 ppm; Ni = 3630.82 ppm) dissolved in 2% by volume of H as the reducing agent. 2 O 2 Using insoluble Co 3+ Soluble Co 2+ The pH of the feed solution was stabilized with 250 mL of 3M sodium acetate buffer solution at pH 5.2 to give a final feed solution concentration of 20 g / L of NMC cathode material. The extractant used in the first stage was 1M Cyanex 272 in Isopar L. The strip solution used was 1 L of 0.75 M NaCl. 2 SO 4 The initial pH of the feed solution was adjusted to 5.5 using ammonium hydroxide. The Co and Mn content in the strip solution increased over time and a Co recovery of 92% was achieved while maintaining minimal passage of Ni and no passage (complete rejection) of Li into the strip solution (see Figure 8(b)). To prevent a decrease in extraction rate over time with decreasing pH, ammonium hydroxide was added intermittently to the feed solution to maintain a pH range of 5.0-5.5. The separation and recovery of Co in the first stage is shown in Figures 8(a)-8(e).

[0047] For further purification of Co, a second stage of separation was carried out using the final strip solution obtained in the first stage as the feed solution for the second stage. The pH of the feed solution for the second stage was adjusted to 1.34 with ammonium hydroxide. The extractant used in this stage was 1M Cyanex 301 in Isopar-L. The strip solution used was 1L of 1M H 2 SO 4Cyanex 301 selectively extracts both Co and Ni with minimal co-extraction of Mn at feed pH values ​​below 2. However, the Ni concentration in the feed solution prepared from the strip solution was negligible. Therefore, a second stage was used to separate and recover Co from the Co and Mn solution. The Co content in the strip increased over time and a Co recovery of 54% was achieved in 2 hours while keeping the passage of Mn into the strip solution to a minimum. Co with a purity of 99.12% was recovered from membrane solvent extraction using Cyanex 301 as the extractant in the organic phase contained in the membrane support. The feed pH value was reduced to 1.04 during the experiment, but this change in pH value did not affect the extraction rate of Co. The separation performance of Co in this second stage is shown in Figures 9(a)-9(b).

[0048] Example 4 In this example, a three-stage membrane solvent extraction process was used to recover substantially pure Ni, Li, Co, and Mn from used Chevrolet Volt lithium-ion batteries. Approximately 60 gm of cathode powder mixed with partially oxidized carbon black was obtained using heat treatment. 750 mL of 4M H 2 SO 4 The first stage feed solution was prepared by dissolving 40 g of the cathode material in 100% CO. Vacuum filtration was used to separate the undissolved carbon black from the feed solution. 2% by volume of H 2 O 2 The partially reduced Co(III) was converted to the soluble Co(II) valence state using the carbon additive present in the cathode material. 2 SO 4 The pH of the feed solution was stabilized using 250 mL of 3 M sodium acetate buffer solution at pH 5.6. A feed solution concentration of approximately 30 g / L of spent cathode material was obtained. The feed solution was dissolved in 4 M H 2 SO 4 , 2% by volume H 2 O 2The feed solution contained 1 L of 30,000 ppm of used cathode in 250 mL of 3 M sodium acetate buffer solution. The initial composition of the feed solution contained Li (1005.0 ppm), Co (3663.9 ppm), Ni (4363.7 ppm), and Mn (9721.2 ppm), with no detected Al. The cation extractant contained 1 M Cyanex 272 in Isopar-L. The strip solution contained 1 L of 0.75 M NaCl in 250 mL of 3 M NaCl. 2 SO 4 The initial pH of the feed solution was adjusted to 4.9 with ammonium hydroxide. To prevent a decrease in extraction rate over time with decreasing pH, ammonium hydroxide was added intermittently to the feed solution to maintain a pH range of 4.5 to 5.0 throughout the run. Within this feed pH range, Cyanex 272 extracted both Co and Mn while preventing co-extraction of Ni and Li. The Co and Mn content in the strip solution increased over time and a Co recovery of 98.4% was achieved while preventing the passage of Ni and Li into the strip solution. The separation and recovery of Co in the first stage is shown in Figure 10(a)-10(e).

[0049] For further purification of Co from Mn, a second stage separation was carried out using the final strip solution from the first stage separation as the feed solution. The pH of the feed solution was adjusted to 1.2 using ammonium hydroxide. The composition of the feed solution for the second stage included Co (2853.6 ppm) and Mn (7844.3), with no detectable Li or Ni. The decrease in the concentration of Co and Mn was due to the addition of ammonium hydroxide to the feed solution for pH adjustment. The extractant used in this stage was 1 M Cyanex 301 in Isopar-L (50% v / v). The area of ​​the membrane module was 1.4 m 2 The strip solution used was 1L of 1M H 2 SO 4Cyanex 301 selectively extracts both Co and Ni with minimal co-extraction of Mn at feed pH below 1.5. However, the concentration of Ni in the feed solution prepared from the first stage strip solution was near zero, indicating that there was no extraction of Ni by the organic phase. Therefore, a second stage was used to separate and recover Co from both the Co and Mn solutions. The Co content in the strip increased over time and a cumulative recovery of Co of 94.3% was achieved in 4 hours while preventing the passage of Mn into the strip solution. 100% pure Co was recovered from membrane solvent extraction using Cyanex as the extractant in the organic phase contained in the membrane pores. The feed pH decreased to 1.13 during this experiment. However, the extraction rate of Co was not affected by this change in pH. The separation performance of the second stage is shown in Figure 11(a)-Figure 11(e).

[0050] The third stage separation was carried out using the same feed solution remaining after the first stage to separate Ni and Li present in the feed solution of the first stage. The pH of the feed solution for the third stage was adjusted to 6.3 using ammonium hydroxide. The composition of the feed solution included Li (744.5 ppm) and Ni (3467.1 ppm) with no detectable Co, Mn or Al. The decrease in the concentration of Ni and Li was due to the addition of ammonium hydroxide to the feed solution for pH adjustment. The extractant used in this stage was 1 M Cyanex 272 in Isopar-L (50% v / v). The strip solution was 1 L of 0.75 M NaCl. 2 SO 4 The membrane module area was 1.4 m 2Cyanex 272 selectively extracts Ni with minimal co-extraction of Li in the feed pH range of 6.0 to <6.5. The Ni content in the strip solution increases over time and a cumulative recovery of Ni of 89.7% was achieved in 6 h with minimal migration of Li into the strip solution. Ni with a purity of 96.1% was recovered from membrane solvent extraction using Cyanex 272 as the extractant in the organic phase contained in the membrane pores. Feed pH values ​​were maintained in the range of 6.0 to 6.5 during the test runs. The separation performance of the third stage is shown in Figure 12(a) to Figure 12(e).

[0051] The recovered cobalt was precipitated using oxalic acid and annealed at 760 °C. The cobalt oxide was then characterized using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). 3 O 4 The SEM image of the powder is shown. 3 O 4 The powder contains rod-shaped particles with sizes of 20-40 μm. 3 O 4 The EDS spectrum of Co is shown in Figure 14. 3 O 4 Only characteristic peaks for cobalt were observed in the EDS spectrum. No peaks for any other constituent elements of the positive electrode material were observed other than cobalt, strongly suggesting that the cobalt separated from the other constituent elements (Li, Ni, Mn) of the positive electrode material is in a pure form. Finally, Figure 15 shows the Co separated from the positive electrode material. 3 O 4 Includes X-ray diffraction (XRD).

[0052] The above description is of the current embodiment of the present invention. Various modifications and changes may be made without departing from the spirit and broader aspects of the present invention as defined in the appended claims, which shall be interpreted in accordance with the principles of patent law, including the doctrine of equivalents. Any reference to an element in the singular, for example, using articles such as "a," "an," "the," or "said," should not be construed as limiting the element to the singular. Some of the embodiments of the invention related to the present invention are given below. [Embodiment 1] 1. A method for recovering cobalt from a lithium ion battery, comprising the steps of: dissolving Co and Li containing battery materials in an acid to form a feed solution containing Co(II) and Li(I); providing a membrane module comprising a plurality of hollow fibers, the plurality of hollow fibers comprising a porous sidewall defining a lumen side spaced from a shell side; wetting the porous sidewalls of the plurality of hollow fibers with an organic phase comprising a cation extractant and an organic solvent; performing a membrane solvent extraction by translating the feed solution along one of the lumen side or the shell side of the plurality of hollow fibers and simultaneously translating a strip solution having a pH lower than a pH of the aqueous feed solution along the other of the lumen side or the shell side of the plurality of hollow fibers; maintaining the pH of the feed solution within a predetermined range by intermittently introducing a buffer or base to the feed solution during membrane solvent extraction; Including, wherein wetting the porous side walls of the plurality of hollow fibers with the organic phase occurs prior to transferring the feed solution and transferring the strip solution, and the cation extractant within the porous side walls continuously extracts Co(II) from the aqueous feed solution for recovery by the strip solution while substantially excluding Li(I). [Embodiment 2] 2. The method of embodiment 1, wherein the feed solution has a positive pressure difference with respect to the strip solution of between 1 psi and 5 psi. [Embodiment 3] 2. The method of embodiment 1, wherein the feed solution and the strip solution move in continuous recirculation through the membrane module for at least 30 minutes. [Embodiment 4] 2. The method of claim 1, further comprising separating the battery material from the positive electrode of the spent battery, wherein separating the battery material from the positive electrode of the spent battery comprises subjecting the positive electrode of the spent battery to heat treatment, acid dissolution and vacuum filtration. [Embodiment 5] 2. The method of claim 1, wherein the organic phase contained within the porous side walls of the plurality of hollow fibers is substantially free of tributyl phosphate. [Embodiment 6] 1. A multi-stage recovery system comprising: a first feed reservoir containing a first feed solution containing dissolved battery materials including concentrations of Li, Ni, Co, and Mn; a first membrane module including a first plurality of hollow fibers each having a porous sidewall pre-wetted with a first organic phase, the first membrane module receiving the first feed solution in continuous recirculation through the first membrane module; a first strip reservoir in fluid communication with the first membrane module and containing a first strip solution having Co and Mn extracted from the first feed solution; a second feed reservoir containing a second feed solution containing concentrations of Co and Mn recovered from the first strip reservoir; a second membrane module including a second plurality of hollow fibers each having a porous sidewall pre-wetted with a second organic phase, the second membrane module receiving the second feed solution in a continuous recycle through the second membrane module; a second strip reservoir in fluid communication with the second membrane module and containing a second strip solution having Co and Mn extracted from the second feed solution; Including, A multi-stage recovery system, wherein the first membrane module selectively recovers Co and Mn from the first feed solution while rejecting Li and Ni, and the second membrane module selectively recovers Co from the second feed solution while rejecting Mn. [Embodiment 7] moreover, a third feed reservoir containing a third feed solution containing concentrations of Li and Ni recovered from the first feed reservoir; a third membrane module including a third plurality of hollow fibers each having a porous sidewall pre-wetted with a third organic phase, the third membrane module receiving the third feed solution in continuous recirculation therethrough; a third strip reservoir in fluid communication with the third membrane module and containing a third strip solution having Ni extracted from the second feed solution; Including, the third membrane module selectively recovers Ni from the first feed solution while rejecting Li; 7. The system of embodiment 6. [Embodiment 8] 7. The system of embodiment 6, wherein the pH of the first feed solution is between 4 and 6, and the first organic phase comprises a cation extractant and an organic solvent. [Embodiment 9] 7. The system of embodiment 6, wherein the pH of the second feed solution is 1.5 or less, and the second organic phase comprises a cation extractant and an organic solvent. [Embodiment 10] 8. The system of embodiment 7, wherein the pH of the third feed solution is between 6 and 7.5, and the third organic phase comprises a cation extractant and an organic solvent. [Embodiment 11] 1. A method for recycling battery materials, comprising: dissolving battery materials containing Co, Mn, Li and Ni in an acid to form a first feed solution, and adjusting the pH of the first feed solution to be 4 or more and 6 or less; providing a first membrane module including a first plurality of hollow fibers, each of the first plurality of hollow fibers having a lumen side and a shell side; wetting the first plurality of hollow fibers with a first organic phase comprising a first cation extractant; after wetting the first hollow fibers, moving the aqueous feed solution along one of the lumen side or the shell side of the plurality of hollow fibers and simultaneously moving a strip solution along the other of the lumen side or the shell side of the plurality of hollow fibers; Including, The process wherein the first cation extractant continuously removes Co and Mn from the aqueous feed solution as a first stage membrane solvent extraction while substantially excluding Li and Ni, and the strip solution continuously back extracts Co and Mn from the first organic phase. [Embodiment 12] 12. The method of embodiment 11, wherein adjusting the pH of the first feed solution comprises intermittently adding a buffer or base to maintain the pH at 4 or more and 6 or less. [Embodiment 13] 12. The method of embodiment 11, wherein the first feed solution has a positive pressure difference with respect to the first strip solution of between 1 psi and 5 psi. [Embodiment 14] 12. The method of embodiment 11, wherein moving the first feed solution and moving the first strip solution comprises continuously recirculating the first feed solution and the first strip solution through the first membrane module for at least one hour. [Embodiment 15] 12. The method of embodiment 11, further comprising performing a second stage membrane solvent extraction of the first strip solution as a second feed solution to recover Co while substantially excluding Mn, and adjusting the pH of the second feed solution to ≦1.5. [Embodiment 16] The second stage membrane solvent extraction comprises: providing a second membrane module comprising a second plurality of hollow fibers, the second plurality of hollow fibers having a lumen side and a shell side; wetting the second plurality of hollow fibers with a second organic phase comprising a second cation extractant; translating the second feed solution along one of the lumen side or the shell side of the second plurality of hollow fibers and simultaneously translating a second strip solution along the other of the lumen side or the shell side of the second plurality of hollow fibers; Including, the second cation extractant continuously extracts Co from the second feed solution while substantially excluding Mn, and the third strip solution continuously back extracts Co from the second organic phase. 16. The method of embodiment 15. [Embodiment 17] 16. The method of embodiment 15, further comprising performing a third stage membrane solvent extraction of said first solution as a third feed solution to recover Mn while substantially excluding Ni, and adjusting the pH of said third feed solution to be 6.0 or higher and 6.5 or lower. [Embodiment 18] The third stage membrane solvent extraction comprises: providing a third membrane module comprising a third plurality of hollow fibers, the third plurality of hollow fibers having a lumen side and a shell side; wetting the third plurality of hollow fibers with a third organic phase comprising a third cation extractant; moving the third feed solution along one of the lumen side or the shell side of the third plurality of hollow fibers and simultaneously moving a third strip solution along the other of the lumen side or the shell side of the third plurality of hollow fibers; Including, 18. The method of embodiment 17, wherein the third cation extractant continuously extracts Ni from the third feed solution while substantially excluding Li, and the third strip solution continuously back-extracts Ni from the third organic phase. [Embodiment 19] 12. The method of embodiment 11, wherein the first plurality of hollow fibers is formed from a porous hydrophobic material. [Embodiment 20] 12. The method of claim 11, further comprising separating the battery material from a positive electrode of a spent battery, wherein separating the battery material from a positive electrode of a spent battery comprises subjecting the positive electrode of a spent battery to heat treatment, acid dissolution and vacuum filtration.

Claims

1. 1. A method for recovering cobalt from a lithium ion battery, comprising the steps of: dissolving battery materials containing Co, Mn, Ni and Li in an acid to form a feed solution comprising Co, Mn, Ni and Li; providing a membrane module comprising a plurality of hollow fibers, the plurality of hollow fibers comprising a porous sidewall defining a lumen side spaced from a shell side; wetting the porous sidewalls of the plurality of hollow fibers with an organic phase comprising a cation extractant and an organic solvent, wherein the organic phase does not comprise tributyl phosphate; performing membrane solvent extraction by translating the feed solution along one of the lumen side or the shell side of the plurality of hollow fibers and simultaneously translating a strip solution having a pH lower than a pH of the aqueous feed solution along the other of the lumen side or the shell side of the plurality of hollow fibers; maintaining the pH of the feed solution within a predetermined range of 4.0 to 6.0 by intermittently introducing a buffer or base to the feed solution during membrane solvent extraction; Including, wherein wetting the porous side walls of the plurality of hollow fibers with the organic phase occurs prior to passing the feed solution and passing the strip solution, and the cation extractant within the porous side walls continuously extracts Co and Mn from the aqueous feed solution for recovery by the strip solution while substantially excluding Li and Ni.

2. 2. The method of claim 1, wherein the feed solution has a positive pressure differential with respect to the strip solution of between 1 psi and 5 psi.

3. 10. The method of claim 1, wherein the feed solution and the strip solution move in continuous recirculation through the membrane module for at least 30 minutes.

4. 10. The method of claim 1, further comprising separating the battery material from a positive electrode of the spent battery, and wherein separating the battery material from a positive electrode of the spent battery comprises subjecting the positive electrode of the spent battery to heat treatment, acid dissolution and vacuum filtration.

5. 1. A multi-stage recovery system comprising: a first feed reservoir containing a first feed solution containing dissolved battery materials including concentrations of Li, Ni, Co, and Mn; a first membrane module including a first plurality of hollow fibers each having a porous sidewall pre-wetted with a first organic phase, the first membrane module receiving the first feed solution in continuous recirculation therethrough; a first strip reservoir in fluid communication with the first membrane module and containing a first strip solution having Co and Mn extracted from the first feed solution; a second feed reservoir containing a second feed solution containing concentrations of Co and Mn recovered from the first strip reservoir; a second membrane module including a second plurality of hollow fibers each having a porous sidewall pre-wetted with a second organic phase, the second membrane module receiving the second feed solution in a continuous recycle through the second membrane module; a second strip reservoir in fluid communication with the second membrane module and containing a second strip solution having Co and Mn extracted from the second feed solution; Including, A multi-stage recovery system, wherein the first membrane module selectively recovers Co and Mn from the first feed solution while rejecting Li and Ni, and the second membrane module selectively recovers Co from the second feed solution while rejecting Mn.

6. moreover, a third feed reservoir containing a third feed solution containing concentrations of Li and Ni recovered from the first feed reservoir; a third membrane module including a third plurality of hollow fibers each having a porous sidewall pre-wetted with a third organic phase, the third membrane module receiving the third feed solution in continuous recirculation therethrough; a third strip reservoir in fluid communication with the third membrane module and containing a third strip solution having Ni extracted from the second feed solution; Including, the third membrane module selectively recovers Ni from the first feed solution while rejecting Li; The system of claim 5.

7. 6. The system of claim 5, wherein the pH of the first feed solution is between 4 and 6, and the first organic phase comprises a cation extractant and an organic solvent.

8. 6. The system of claim 5, wherein the pH of the second feed solution is less than or equal to 1.5 and the second organic phase comprises a cation extractant and an organic solvent.

9. 7. The system of claim 6, wherein the third feed solution has a pH of 6 to 7.5 and the third organic phase comprises a cation extractant and an organic solvent.

10. 1. A method for recycling battery materials, comprising: dissolving battery materials containing Co, Mn, Li and Ni in an acid to form a first feed solution, and adjusting the pH of the first feed solution to a value between 4 and 6; providing a first membrane module including a first plurality of hollow fibers, each of the first plurality of hollow fibers having a lumen side and a shell side; wetting the first plurality of hollow fibers with a first organic phase comprising a first cation extractant and free of tributyl phosphate; after wetting the first hollow fibers, moving the aqueous feed solution along one of the lumen side or the shell side of the plurality of hollow fibers and simultaneously moving a strip solution along the other of the lumen side or the shell side of the plurality of hollow fibers; Including, The process of claim 1, wherein the first cation extractant continuously removes Co and Mn from the aqueous feed solution as a first stage membrane solvent extraction while substantially excluding Li and Ni, and the strip solution continuously back extracts Co and Mn from the first organic phase.

11. 11. The method of claim 10, wherein adjusting the pH of the first feed solution comprises intermittently adding a buffer or base to maintain the pH at 4 or more and 6 or less.

12. 11. The method of claim 10, wherein the first feed solution has a positive pressure differential with respect to the first strip solution of between 1 psi and 5 psi.

13. 11. The method of claim 10, wherein moving the first feed solution and moving the first strip solution comprises continuously recirculating the first feed solution and the first strip solution through the first membrane module for at least one hour.

14. 11. The method of claim 10, further comprising: performing a second stage membrane solvent extraction of the first strip solution as a second feed solution to recover Co while substantially excluding Mn; and adjusting the pH of the second feed solution to ≦1.

5.

15. The second stage membrane solvent extraction comprises: providing a second membrane module comprising a second plurality of hollow fibers, the second plurality of hollow fibers having a lumen side and a shell side; wetting the second plurality of hollow fibers with a second organic phase comprising a second cation extractant; moving the second feed solution along one of the lumen side or the shell side of the second plurality of hollow fibers and simultaneously moving a second strip solution along the other of the lumen side or the shell side of the second plurality of hollow fibers; Including, the second cation extractant continuously extracts Co from the second feed solution while substantially excluding Mn, and the second strip solution continuously back extracts Co from the second organic phase; The method of claim 14.

16. 15. The method of claim 14, further comprising: performing a third stage membrane solvent extraction of the first feed solution as a third feed solution to recover Ni while substantially excluding Li; and adjusting the pH of the third feed solution to be 6.0 or more and 6.5 or less.

17. The third stage membrane solvent extraction comprises: providing a third membrane module comprising a third plurality of hollow fibers, the third plurality of hollow fibers having a lumen side and a shell side; wetting the third plurality of hollow fibers with a third organic phase comprising a third cation extractant; moving the third feed solution along one of the lumen side or the shell side of the third plurality of hollow fibers and simultaneously moving a third strip solution along the other of the lumen side or the shell side of the third plurality of hollow fibers; Including, 17. The method of claim 16, wherein the third cation extractant continuously extracts Ni from the third feed solution while substantially excluding Li, and the third strip solution continuously back extracts Ni from the third organic phase.

18. The method of claim 10 , wherein the first plurality of hollow fibers is formed from a porous hydrophobic material.

19. 11. The method of claim 10, further comprising separating the battery material from a positive electrode of a spent battery, wherein separating the battery material from a positive electrode of a spent battery comprises subjecting the positive electrode of a spent battery to heat treatment, acid dissolution and vacuum filtration.

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