Copolymer, working electrode, and electrochemical device and method for selective recovery of lithium

Abstract

A method for selectively recovering lithium includes positioning a working electrode in a treatment solution comprising lithium ions, where the working electrode includes a film comprising a copolymer on an electrically conductive substrate. The copolymer comprises redox monomers each including a redox-active moiety, and adsorbent monomers each including a lithium-selective ligand. The working electrode is electrochemically activated such that the treatment solution penetrates the copolymer. After the electrochemical activation, the working electrode is exposed to an open circuit potential, and lithium ions from the treatment solution are selectively bound to the lithium-selective ligands. After a time sufficient to achieve a desired uptake of lithium ions by the lithium-selective ligands, the treatment solution is replaced with a collection solution, and a desorption potential is applied to the working electrode. As a result, the redox-active moieties undergo oxidation and bound lithium ions are released from the lithium-selective ligands into the collection solution.

Description

COPOLYMER, WORKING ELECTRODE, AND ELECTROCHEMICAL DEVICE AND METHOD FOR SELECTIVE RECOVERY OF LITHIUMRELATED APPLICATION

[0001] The present patent document claims the benefit of priority under 35 U.S.C.119(e) to U.S. Provisional Patent Application No. 63 / 682,439, which was filed on August 13, 2024, and is hereby incorporated by reference in its entirety.FEDERALLY FUNDED RESEARCH OR DEVELOPMENT

[0002] This invention was made with government support under DE-SC0021409 awarded by the Department of Energy. The government has certain rights in the invention.TECHNICAL FIELD

[0003] This disclosure is related generally to metal ion recovery and more particularly to a copolymer, device and method for selective recovery of lithium ions.BACKGROUND

[0004] Lithium-ion batteries (LIB) have revolutionized the energy storage landscape, powering applications ranging from portable electronics to electric vehicles. With the rapidly increasing demand for the LIB, the importance of lithium continues to grow. Lithium is regarded as a critical element today because of its unique electrochemical properties, including the highest electrochemical potential of all metals, low density, and high energy storage capacity. Moreover, lithium has been used in the production of glass, ceramics, and even pharmaceuticals, highlighting its broad industrial significance.However, the widespread use of LIBs and lithium in various industries presents significant environmental and economic challenges due to the finite nature of lithium resources and the potential environmental hazards associated with improper disposal of spent batteries. Consequently, efficient recovery and recycling of lithium are increasingly vital for sustainable development and energy security.

[0005] Conventional lithium recovery methods from spent LIBs primarily include pyrometallurgy and hydrometallurgy. Pyrometallurgy involves high-temperaturetreatment of spent batteries to smelt and recover lithium in I^CCh form. At temperatures up to 1600°C, battery materials undergo calcination and react with lithium to form Li2COs. In the pyrometallurgy process, it is challenging to effectively recover lithium because lithium tends to remain in the slag phase. Besides, the use of high temperatures and large amounts of chemicals (HC1) to dissolve and separate IJ2CO3 requires substantial energy and chemical inputs. In the case of hydrometallurgy, metals are leached using leaching agents, such as inorganic, organic acids, and alkaline solutions. The hydrometallurgy method can achieve high lithium purity and recovery rate, yet it is associated with several separation processes such as precipitation, solvent extraction, or selective adsorption. In many of these processes, the separation of transition metals such as nickel, cobalt, and manganese is prioritized over lithium recovery. As a result, lithium recovery often becomes the final step, leading to inevitable lithium losses and challenging separations due to the presence of a mixture of charged species. In particular, incomplete decomposition of binders, such as PVDF, generates various inorganic and organic fluorinated compounds, further complicating lithium separation during spent LIB recycling. Therefore, developing selective and environmentally friendly lithium recovery methodologies would be beneficial, not only to achieve a circular economy but also to address the environmental and energy challenges associated with conventional LIB recycling.SUMMARY

[0006] This disclosure describes a copolymer, a working electrode, an electrochemical device and a method for selective lithium recovery.

[0007] The copolymer comprises a redox monomer including a redox-active moiety, and an adsorbent monomer including a lithium- selective ligand.

[0008] The working electrode includes a film comprising a copolymer on an electrically conductive substrate, the copolymer comprising a redox monomer including a redox-active moiety, and an adsorbent monomer including a lithium- selective ligand.

[0009] The electrochemical device comprises a working electrode including a film comprising a copolymer on an electrically conductive substrate, the copolymer comprising a redox monomer including a redox-active moiety, and an adsorbentmonomer including a lithium-selective ligand; a counter electrode spaced apart from the working electrode; a power supply configured for electrical connection to the working electrode and the counter electrode; and a cell configured to hold a treatment solution comprising lithium ions in contact with the working and counter electrodes.

[0010] The method for selectively recovering lithium includes positioning a working electrode in a treatment solution comprising lithium ions, where the working electrode includes a film comprising a copolymer on an electrically conductive substrate. The copolymer comprises redox monomers each including a redox-active moiety, and adsorbent monomers each including a lithium- selective ligand. The working electrode is electrochemically activated such that the treatment solution penetrates the copolymer. After the electrochemical activation, the working electrode is exposed to an open circuit potential, and lithium ions from the treatment solution are selectively bound to the lithium- selective ligands. After a time sufficient to achieve a desired uptake of lithium ions by the lithium-selective ligands, the treatment solution is replaced with a collection solution, and a desorption potential is applied to the working electrode. As a result, the redox-active moieties undergo oxidation and bound lithium ions are released from the lithium- selective ligands into the collection solution.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG. 1 A provides a schematic of electrochemically-regenerative lithium recovery, including: (i) electrochemical activation to enhance solvent interaction on a copolymer film including a redox-active moiety and a lithium-selective ligand, (ii) lithium capture on the lithium-selective ligand (e.g., crown ether moiety) at the opencircuit potential, and (iii) lithium release upon the oxidation of the redox-active moiety (e.g., ferrocenylpropyl methacrylamide (FPMAm) moiety).

[0012] FIG. IB is a schematic illustrating the functionality of a homopolymer, in this example 12-crown-4 ether methacrylate (12C4MA) (top); a copolymer, in this example P(FPMAm-co-12C4MA) (middle); and a terpolymer, in this example P(FPMAm-co- 12C4MA-co-GMA) (bottom).

[0013] FIG. 2 A illustrates synthesis of P(FPMAm-co-12C4MA).

[0014] FIG. 2B shows a cyclic voltammogram plot for P(FPMAm-co-12C4MA).

[0015] FIG. 2C shows a high-resolution scanning electron microscope (SEM) image (left) and energy dispersive spectrometry (EDS) mapping of the electrode surface for P(FPM Am-co- 12C4M A) .

[0016] FIG. 2D illustrates synthesis of P(FPMAm-co-12C4MA-co-GMA).

[0017] FIG. 2E shows a cyclic voltammogram plot for P(FPMAm-co-12C4MA-co- GMA.

[0018] FIG. 2F shows a high-resolution SEM image (left) and EDS mapping of the electrode surface for P(FPMAm-co-12C4MA-co-GMA).

[0019] FIG. 3A shows lithium uptake for P(FPMAm), P(12C4MA), and P(FPMAm- co-12C4MA), and P(FPMAm-co-12C4MA-co-GMA).

[0020] FIGS. 3B and 3C show results from an investigation of the effect of the electrochemical activation on the lithium uptake and hydrophilicity of the electrode surface, including Li uptake kinetics and contact angle measurements, respectively, for pristine P(FPMAm-co-12C4MA) and for P(FPMAm-co- 12C4MA) after electrochemical activation.

[0021] FIGS. 3D and 3E show results from an investigation of the effect of the electrochemical activation on the lithium uptake and hydrophilicity of the electrode surface, including Li uptake kinetics and contact angle measurements, respectively, for pristine P(FPMAm-co-12C4MA-co-GMA) and for P(FPMAm-co-12C4MA-co-GMA) after electrochemical activation.

[0022] FIG. 4A shows desorption performance with varied oxidation potential of P(FPMAm-co-12C4MA) and P(FPMAm-co-12C4MA-co-GMA).

[0023] FIGS. 4B and 4C show time-of-flight secondary ion mass spectrometry (TOF- SIMS) and x-ray photoelectron spectroscopy (XPS) analyses, respectively, of the P(FPMAm-co-12C4MA) electrodes: pristine, after adsorption, and after desorption.

[0024] FIG. 4D shows a comparison of desorption performance across crown ether homo-, co-, and terpolymers.

[0025] FIG. 4E shows lithium uptake performance of the copolymer and terpolymer with various organic solvents.

[0026] FIG. 4E shows polymer leaching in acetonitrile and NMP.

[0027] FIG. 5A shows pretreatment steps of lithium battery recycling: complete discharging in 10% (w / v) NaCl for 2 days, dismantling to separate cathode, anode, and separator, NMP leaching at 100 °C overnight, filtration.

[0028] FIGS. 5B and 5C show Li recovery from lithium nickel manganese cobalt (NMC) spent battery solutions and from lithium iron phosphate (LFP) spent battery solutions, respectively.DETAILED DESCRIPTION OF THE DRAWINGS

[0029] Described in this disclosure is a novel copolymer and working electrode designed for the selective recovery of lithium from aqueous or organic fluids (e.g., leachate from spent lithium-ion batteries, brine, seawater, etc.). Also described is an electrochemical device and an electrochemical method of selectively recovering lithium based on the newly developed copolymer and working electrode. The copolymer includes a redox-active moiety and a lithium-selective ligand, a novel polymer design that allows for selective adsorption of lithium ions (as illustrated in FIG. 1A (ii)) followed by controlled release of the lithium, induced by electrochemical oxidation of the redox-active moiety (as illustrated in FIG. 1 A (iii)). The term “copolymer” is used since the polymer includes at least two different monomer species to provide the dual functionality of redox activity and lithium adsorption. This copolymer design provides multiple advantages for implementing an electrochemical separation platform, including reuse of the copolymer following electrochemical regeneration. At the molecular level, the redox activity and lithium adsorption can be modulated by altering the monomer ratios or changing the monomer moieties. From a practical perspective, the copolymer can be readily fabricated into a heterogeneous electrode, facilitating the efficient transfer of adsorbed target species from the initial solution to fresh media. In addition, electrochemistry can be used to improve lithium uptake kinetics of the copolymer prior to lithium adsorption. As discussed below, an electrochemical activation step (illustrated in FIG. 1 A (i)) may facilitate the infiltration of molecules and ionic species from the treatment solution into the copolymer film, enhancing the mass transfer of lithium during the adsorption step.

[0030] The copolymer for selective lithium recovery comprises a redox monomer including a redox-active moiety, and an adsorbent monomer including a lithium- selectiveligand. The redox monomer and the redox-active moiety may comprise a metallocene, such as a ferrocene (Fe CsHs ) or cobaltocene (Co CsHs ), or a nitroxide. The redoxactive moiety may undergo electrochemical oxidation and reduction in response to an oxidizing (positive) and a reducing (negative) electric potential, respectively. In examples discussed below, the redox monomer may comprise ferrocenylpropylmethacrylamide (FPMAm), 2-(methacryloyloxy)ethyl ferrocene carboxylate (FcMA), vinyl ferrocene (VP), ferrocenyl methyl methacrylate (FMMA), 2-(methacrylolyoxy)ethyl cobaltoceniumcarboxylate hexafluorophosphate (MAECoPFe), and / or TEMPO methacrylate. The lithium- selective ligand may comprise a lithium binding site allowing for selective adsorption of lithium ions. For example, the adsorbent monomer and the lithium- selective ligand may comprise a crown ether (CH CH O),,, an aza-crown ether (CH2CH2NH)n, a benzocrown ether, or a cryptand. In some examples, the crown either may comprise 12-crown-4 or 9-crown-3. The adsorbent monomer may, in some examples, comprise 12-crown-4 ether methacrylate (12C4MA) or 9-crown-3 ether methacrylate (9C3MA). An exemplary copolymer discussed in the examples below is P(FPMAm-co-12C4MA). Tested alongside this copolymer are the homopolymers P(FPMAm) and P(12C4MA). As discussed below, the homopolymer P(12C4MA) does not exhibit electrochemical responsiveness, and the homopolymer P(FPMAm) does not exhibit a strong lithium interaction due to the absence of a lithium binding site. Therefore, copolymerization of FPMAm (or another redox monomer) with 12C4MA (or another adsorbent monomer) is believed to be essential to enable strong lithium adsorption along with the capacity for electrochemical activation and regeneration of the copolymer. Other suitable copolymers may include P(FPMAm-co-9C3MA), P(VF-co-12C4MA), P(FcMA- co-12C4MA), P(TMA-co-12C4MA), P(VF-co-9C3MA), P(FcMA-co-9C3MA), and P(TMA-co-9C3MA).

[0031] Depending on the treatment solution from which lithium is recovered, that is, whether the solution is aqueous or organic, crosslinking of the copolymer may be beneficial or necessary to prevent polymer dissolution during the adsorption and desorption processes. Two approaches may be used for cross-linking. In one example, a crosslinker may be introduced during the synthesis of the copolymer and / or working electrode. In another example, a crosslinking monomer may be incorporated into thecopolymer. In the examples described below, the crosslinking monomer comprises glycidyl methacrylate (GM A). Other suitable crosslinking monomers may include (meth)acrylate and (meth)acrylamide monomers with epoxide, hydroxide, amine, carboxylic acid, isocyanate, carbonyl, aceto acetyl, aziridine, carbodiimide, acetal, azlactone, methylol amine, azetidine, alkene, alkine, azide, malimide, benzophenone, or isonitrile moieties, such as hydroxyethyl methacrylate, benzophenone methacrylate, allyl methacrylate, N- (methoxy methyl acetate)acrylamide, 2-(methacryloyloxy)ethyl acetoacetate, acrylic acid, or N-methylolacrylamide. When the crosslinker is incorporated into the copolymer as a monomer, the copolymer may be referred to as a terpolymer. In the examples below, the terpolymer P(FPMAm-co-12C4MA-co-GMA) is produced. Other suitable terpolymers may include P(FPMAm-co-9C3MA-co-GMA), P(VF-co- 12C4M A-co-GMA), P(FcMA-co- 12C4MA-co-GM A), P(TMA-co- 12C4M A- co-GMA), P(VF-co-9C3MA-co-GMA), P(FcMA-co-9C3MA-co-GMA), and P(TMA-co- 9C3MA-co-GMA).

[0032] The mole percentages of the different monomers may be tailored to control redox activity or lithium adsorption. Broadly speaking, a mole percentage of the redox monomer may be in a range from 30% to 70% and / or a mole percentage of the adsorbent monomer may be in a range from 30% to 70%. When a crosslinking monomer is utilized, a mole percentage of the crosslinking monomer may be in the range from greater than 0 to 15%, e.g., from 1% to 15%. The copolymer may be synthesized using radical polymerization, which statistically distributes the different monomers. The distribution of the monomers after polymerization may influence the behavior of the copolymer, which in turn may affect the desired mole percentages. For example, if some of the lithiumselective ligands are too distant from the redox active moieties to experience sufficient electrostatic repulsion for lithium release, then the mole percentage of the redox monomer may need to be increased. Similarly, when a crosslinking monomer is incorporated into the polymer chain, the lithium-selective ligands may be effectively pushed farther apart from the redox active moieties, making it more difficult to release bound lithium via electrostatic repulsion; also, the strong interconnection of polymer chains achieved by crosslinking may impede electron transfer between the electrode substrate and the redoxactive moiety, resulting in weaker electrostatic repulsion. In this situation, increasing themole fraction of the redox monomer within the copolymer may be used to increase electrostatic repulsion, thereby enabling more complete lithium release during desorption. Accordingly, the mole percentage of the redox monomer may be at least about 40%, at least about 50%, or at least about 60%. Similarly, the mole percentage of the adsorbent monomer may be no more than about 60%, no more than about 50%, or no more than about 40%.

[0033] As indicated above, in use the copolymer may be part of a working electrode that includes an electrically conductive substrate. In the examples below, the substrate comprises carbon (e.g., carbon paper), but other electrically conductive materials, such as metals that are chemically inert within the treatment and collection solutions, may also or alternatively be used. The copolymer may be part or all of a film deposited on the substrate. The film may have a thickness in range from approximately a few tens of nanometers to several hundred micrometers. Advantageously, the film may have a non- planar morphology so as to have a large surface area. To enhance both electrical conductivity and copolymer surface area, carbon nanotubes may be incorporated on the substrate and / or mixed with the copolymer.

[0034] The working electrode may be part of an electrochemical device that further includes a counter electrode spaced apart from the working electrode, a power supply configured for electrical connection to the working electrode and the counter electrode, and a cell configured to contain the treatment solution that includes lithium ions. In use, the treatment solution is in contact with the working and counter electrodes. As indicated above, the treatment solution may be an aqueous or organic liquid, such as leachate from spent lithium-ion batteries that may contain an organic solvent, brine, or seawater.

[0035] An electrochemical method for selectively recovering lithium is now described. The method includes positioning a working electrode in a treatment solution comprising lithium ions (e.g., the leachate, brine, or seawater described above), where the working electrode includes the novel copolymer on an electrically conductive substrate. The process may be a batch or continuous process. As described above, the copolymer includes redox monomers and adsorbent monomers, where each redox monomer comprises a redox-active moiety, and each adsorbent monomer comprises a lithiumselective ligand. The copolymer and electrically conductive substrate employed in theelectrochemical method may have any of the characteristics described above or elsewhere in this disclosure. As illustrated in FIG. 1 A (i), the working electrode is electrochemically activated, e.g., using cyclic voltammetry (CV), so that the treatment solution penetrates the copolymer, reducing the mass transfer barrier by creating more interfaces between the copolymer and the treatment solution. More generally speaking, electrochemically activating the working electrode may entail alternately applying a positive potential and a negative potential to the working electrode. After the electrochemical activation, the working electrode is exposed to an open circuit potential while remaining in the treatment solution. Consequently, lithium ions from the treatment solution are selectively bound to the lithium-selective ligands, as illustrated in FIG. IB (ii). After a time duration sufficient to achieve a desired uptake of lithium ions by the lithium- selective ligands, the treatment solution is replaced with a collection solution, and a desorption potential is applied to the working electrode. The desorption potential is usually a positive potential in a range from 0.4 to 1.2 V. Upon exposure to the desorption potential, the redox-active moieties undergo oxidation, which generates an electrostatic repulsive force that leads to a release of bound lithium ions into the collection solution, as illustrated FIG. 1A (hi). Preferably, at least 60% or at least 70% and up to 100% of the bound lithium ions are released. After the release of the bound lithium ions, the working electrode may be reused one or more times with a new treatment solution.

[0036] As indicated above, the working electrode is exposed to the open circuit potential for a time duration sufficient to achieve the desired uptake of lithium ions. The time duration may be in a range from 60 seconds to 60 minutes, or more typically from 10 minutes to 30 minutes. The uptake of lithium ions by the lithium- selective ligands may depend in part on the composition of the copolymer e.g., adsorbent monomer species and mole percentage) and / or the treatment solution, and is much improved with electrochemical activation prior to adsorption, as discussed below. In some examples, the uptake of lithium ions may reach up to 0.8 molLi / molActivesite, where the moln represents moles of the bound lithium ions, and the molActivesite represents moles of the adsorbent monomer. At a minimum, the uptake of lithium ions may be at least 0.1 molLi / molActivesite, or at least 0.2 molij / molActivesite. Due to the selectivity of the adsorbent monomer, there isadvantageously no uptake (or no measurable uptake) of metal cations other than the lithium ions.EXAMPLES

[0037] Two redox-active crown ether polymers, P(FPMAm-co-12C4MA) and P(FPMAm-co-12C4MA-co-GMA) were designed to investigate electrochemical reversibility and stability, along with the lithium uptake performance, and the behavior was compared with the homopolymers of each moiety, P(FPMAm) and P(12C4MA). In the terpolymer design, glycidyl methacrylate (GMA) acts as a crosslinker between polymer chains, providing additional stability in a heterogeneous platform. Lithium uptake performance and its kinetics were evaluated for the synthesized copolymer and terpolymer, as well as control homopolymers, P(FPMAm) and P(12C4MA). To gain a comprehensive understanding of the binding mechanisms, various physicochemical and electrochemical properties were investigated using techniques such as scanning microscopy, contact angle measurements, X-ray photoelectron spectroscopy, and time-of- flight secondary ion mass spectrometry. Then lithium uptake was further tested in several organic solvents, including acetonitrile (MeCN), dimethyl carbonate (DMC), propylene carbonate (PC), and N-methyl-2-pyrrolidone (NMP), to assess polymer stability under potential scenarios such as direct lithium recovery from battery electrolytes and lithium recovery from battery leachates. Finally, selective lithium recovery from spent LIB leachates was performed to provide insights into practical applications.Synthesis of redox-active crown ether polymers and their heterogeneous electrode design

[0038] Redox-active crown ether polymers were synthesized in both copolymer and terpolymer designs as depicted in FIGS. 2A and 2D. Prior to polymer synthesis, ferrocenylpropylmethacrylamide (FPMAm) and 12-crown ether-4 methacrylate (12C4MA) were synthesized according to established literature methods. The redoxactive moiety, FPMAm, was then copolymerized with 12C4MA via radical copolymerization to produce the copolymer, P(FPMAm-co-12C4MA) (FIG. 2A). Additionally, GMA was incorporated into the polymer design to synthesize the terpolymer P(FPMAm-co-12C4MA-co-GMA) (FIG. 2D). The copolymer and terpolymer ratios were calculated usingNMR (500 MHz, CDCL), revealing that P(FPMAm-co-12C4MA) and P(FPMAm-co-12C4MA-co-GMA) contained 54 mol% and 45 mol% 12C4MA, respectively (Figures 2a and d).

[0039] Since the primary focus for lithium recovery in these experiments is in organic solvents, cross-linking was essential to prevent polymer dissolution during the adsorption and desorption processes. Two approaches were employed for the cross-linking process: (i) introducing a cross-linker during the electrode synthesis process and (ii) incorporating a cross-linker (GMA) within the polymer chain. To prepare a heterogeneous electrode of P(FPMAm-co-12C4MA), 4 mg of the polymer were dissolved in 1 mL of chloroform and mixed with carbon nanotubes (CNTs) at a mass ratio of 1:1 with 15 wt% of 1,3- benzenedisulfonyl azide. For P(FPMAm-co-12C4MA-co-GMA), 8 mg of the polymer dissolved in 1 mL of chloroform was mixed with 3.9 mg of CNTs and 0.1 mg of primary amine functionalized CNTs to promote ring-opening of the epoxide on GMA. The mixture was drop-cast onto a carbon paper substrate and dried at 140°C for P(FPMAm- co-12C4MA) and 120°C for P(FPMAm-co-12C4MA-co-GMA) to cross-link the polymers.

[0040] The synthesized polymer electrodes were then characterized for their electrochemical reversibility via cyclic voltammograms (CVs) (FIGS. 2B and 2E). Both PfFPM Am-c< - 12C4M A) and P(FPMAm-co-12C4MA-co-GMA) revealed a single oxidation and reduction peak of FPMAm at 0.111 V and 0.118 V vs Ag / AgNOa, respectively. Scanning electron microscope (SEM) images confirmed the coverage of the carbon paper with our redox-active crown ether polymers (FIGS. 2C and 2F). Additionally, energy dispersive spectrometry (EDS) mapping demonstrated the uniform distribution of ferrocene on the electrode substrate, along with CNTs (carbon mapping on EDS).Investigation of lithium uptake performance and importance of electrochemical activation.

[0041] To investigate the lithium uptake performance, open circuit potential (OCP) uptake experiments were conducted on the homopolymers P(FPMAm) and P(12C4MA), copolymer P(FPMAm-co-12C4MA), and terpolymer P(FPMAm-co-12C4MA-co-GMA) (FIG. 3 A). At OCP, P(12C4MA) captured lithium with an uptake value of 0.23 molLi / molcrE, while P(FPMAm) showed negligible lithium uptake of 0.068molLi / molppMAm. This comparison indicates that the primary binding site for lithium resides on 12C4MA rather than FPM Am. Both P(FPMAm-co-12C4MA) and P(FPMAm- co-12C4MA-co-GMA) showed similar uptake values with P(12C4MA), with the values of 0.29 and 0.21 molLi / molcrE, respectively, at OCP adsorption (denoted as pristine in FIG. 3 A).

[0042] Prior to the OCP adsorption, the CV was conducted as an electrochemical activation step to facilitate lithium-ion mobility within the film. The oxidation of ferrocene during the CV sweep was expected to increase the solvophilicity of the polymer and induce film swelling, thereby enhancing ion mobility within the polymer and at the polymer-electrolyte interface (FIG. 1 A). This enhanced accessibility was anticipated to promote lithium capture by the crown ether moiety and improve overall uptake kinetics. The result showed that the initial electrochemical activation step significantly enhanced lithium uptake in both copolymer and terpolymer by 2-fold (0.62 and 0.56 molLi / molcrE, respectively) (FIG. 3A). Li+uptake kinetics showed that electrochemical activation improved adsorption rates, increasing rate constants (k) by 3-fold for P(FPM Am-co- 12C4MA) and 2-fold for P(FPMAm-co-12C4MA-co-GMA) (FIGS. 3B and 3D and Table 1). The kinetic results suggest that electrochemical activation improves mass transport and lithium uptake with 12C4MA. Electrochemical activation via CV can be expected to enhance the film wettability of the redox-active polymer film, subsequently enhancing the lithium capture onto the crown ether moiety and its uptake kinetics.

[0043] To assess the wettability of the polymer film during the electrochemical activation, changes in contact angle and film thickness were analyzed by measuring contact angles and ellipsometry for pristine and electrochemically activated co- and terpolymers (FIGS. 3C and 3E). Contact angle measurements were performed using water as a standardized probe, with the setup optimized for accurate detection of wettability changes. The pristine electrode surfaces of P(FPMAm-co-12C4MA) and P(FPMAm-co- 12C4MA-co-GMA) were relatively solvophobic, exhibiting water contact angles of 58.8° and 48.7°, respectively (top of FIGS. 2C and 2E). Upon the electrochemical activation, the films became more solvophilic, with contact angles decreasing by 59% and 63% for copolymer and terpolymer electrodes, respectively (bottom of FIGS. 2C and 2E). This wettability increase is driven by the oxidation of ferrocene, which enhances thesolvophilicity of the polymer film. Although contact angle measurements in water may not represent the absolute behavior of the polymer in organic electrolytes, they offer comparative insight into surface solvophilicity and film swelling. Additionally, changes in polymer film thickness observed through complementary ellipsometry measurements provide further evidence of solvent penetration and film swelling behavior. The ellipsometry result indicates that after electrochemical activation of P(FPMAm-co- 12C4MA), the film thickness increased from the pristine film thickness of 45 nm to 67 nm, a 48% expansion. Following adsorption, the film further expanded to 72 nm; however, most of the swelling occurred during CV activation, underscoring the critical role of electrochemical activation in enhancing accessibility of the polymer to ions. This electrochemical activation process is hypothesized to improve mass transfer within the polymer films and possibly at the polymer-solvent interface, facilitating lithium-ion transport within the polymer film during OCP uptake.Table 1. Summary of Li uptake kinetic tests: maximum uptake values (qe) and binding constant (k) for electrochemical activation and pristine electrodes of P(FPMAm-co- 12C4MA) and P(FPMAm-co-12C4MA-co-GMA). qekPolymer (molLi / molCrE) (molCrE / molLi / min) fhein0.59 1.24P(FPMAm-co-12C4MA) activation Pristine 0.39 0.389Echem n SA 1 SAP(FPMAm-co-12C4MA- activation0 56 1 56co-GMA) Pristine 0.24 0.785Desorption performance and solvent compatibility ofP(FPMAm-co-12C4MA)

[0044] Desorption tests were carried out for P(FPMAm-co-12C4MA) and P(FPMAm- co-12C4MA-co-GMA) at potentials ranging from OCP to 1.2 V vs. Ag / AgNOa (FIG.4A). Lithium regeneration for the copolymer increased from 16% at OCP to 73% at 1.2 V, with the terpolymer following a similar trend but reaching 66% at 1.2 V. The lower desorption in the terpolymer was likely due to GM A- induced spacing between 12C4MAand FPMAm, as well as the opened epoxide in GMA serving as an additional binding site, restricting lithium release through electrostatic repulsion. A sharp increase in regeneration from 20% to 69% was observed between 0.4 V and 0.8 V, suggesting that ferrocene oxidation, often operated at 0.6-0.8 V vs. Ag / AgCl or Ag / AgNOa, generated the electrostatic repulsive force that promoted lithium release. At 1.0 V, lithium desorption from P(FPMAm-co-12C4MA) and P(FPMAm-co-12C4MA-co-GMA) showed an 8.7-fold enhancement compared to P(12C4MA), which exhibited minimal release (<5.4%) (FIG. 4D), confirming that desorption is primarily driven by electrostatic repulsion from oxidized ferrocene. To further improve electrochemical regeneration performance, future studies can further optimize the copolymer composition of FPMAm, 12C4MA, and GMA, including exploring the spatial distribution of 12C4MA and FPMAm.

[0045] Lithium adsorption onto the polymer electrode and the redox state of ferrocene were further analyzed using time-of-flight secondary ion mass spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS), respectively (FIGS. 4B and 4C). ToF-SIMS analysis revealed distinct lithium isotopic peaks at 6.015 and 7.016 m / z on the electrode surface after adsorption, whereas nearly all adsorbed lithium was removed after desorption (FIG. 4B). XPS analysis showed a distinct Fe(II) peak in the pristine electrode, while electrochemical activation and OCP adsorption led to subtle ferrocene oxidation, as indicated by the presence of a Fe(III) peak alongside Fe(II) (FIG. 4C). After the regeneration step, a distinct Fe(III) peak was observed with no detectable Fe(II) signal, confirming complete oxidation of ferrocene. Overall, ToF-SIMS and XPS confirmed the reversible electrochemical binding and release of lithium.

[0046] Beyond the proof-of-concept studies in acetonitrile (MeCN), lithium uptake was further examined in dimethyl carbonate (DMC), propylene carbonate (PC), an ethylene carbonate-based electrolyte (EC / DMC, 1:1 v / v), and N-methyl-2-pyrrolidone (NMP) (FIG. 4E), all of them are directly relevant to LIB systems. DMC and PC are common battery electrolytes, EC / DMC is a widely adopted formulation in LIB technologies, and NMP is frequently employed as a leaching solvent in LIB recycling processes. Uptake varied from 0.025 to 0.81 molLi / molcrE, with the highest values in DMC (0.81 and 0.70 molLi / molcrE for co- and terpolymers, respectively), followed byMeCN, PC, and NMP. The superior lithium uptake in DMC can be attributed to the linear carbonate structure of the solvent, which enhances lithium-ion mobility compared to the cyclic carbonate solvent PC. Additionally, the lower dielectric permittivity of DMC (s = 3.1 at 25°C) weakens lithium solvation, typically coordinating with two DMC molecules per Li+, compared to PC (s = 64.92 at 25°C), which forms a more extensive solvation shell with over five PC molecules per Li+. This weaker solvation in DMC reduces the desolvation energy barrier, facilitating lithium transport and adsorption. Furthermore, the mixed solvent systems, EC / DMC, facilitate the Li+transport while moderating lithium solvation, thus providing favorable conditions for lithium insertion into the crown ether cavity. The EC-based system showed notable lithium uptake values of 0.82 molLi / molcrE for P(FPMAm-co-CrE) and 0.85 molLi / molcrE for P(FPMAm-co-CrE-co-GMA) (FIG. 4E). The results suggest that this platform may be applicable to direct battery recycling processes, where mixed carbonate electrolytes are commonly used.

[0047] A distinct difference in lithium adsorption was observed between the copolymer and terpolymer in NMP, where P(FPMAm-co-12C4MA) exhibited negligible Li uptake (0.025 moli / molcri), while P(FPMAm-co-12C4MA-co-GMA) achieved 0.32 molLi / molcrE (FIG. 4E). This difference arises from the instability of the P(FPM Am-co- 12C4MA) film in NMP, with over 80 wt% of the polymer leaching into the solution during adsorption (FIG. 4F), whereas the terpolymer remained stable, losing only 4.0 wt% in MeCN and NMP. This comparison highlights the structural advantage of the terpolymer, where crosslinking within the polymer network enhances stability (FIG. IB), enabling it to withstand a wider range of solvents as a heterogeneous platform. The results suggest the copolymer is suited for lithium capture in LIB electrolytes and organic solvents such as MeCN, while the robustness of the terpolymer extends its applicability to LIB recycling in solvents such as NMP.Capability of lithium adsorption from spent LIBs

[0048] By incorporating a redox-active moiety and a lithium-selective ligand into a copolymer design, lithium recovery has been achieved from various organic solvents as discussed above, particularly in NMP, which is frequently used for battery leaching. To offer insights into the practical application of P(FPMAm-co-12C4MA-co-GMA) in the LIB recycling process, lithium recovery experiments were conducted on spent LIBs,including both lithium nickel manganese cobalt (NMC) and lithium iron phosphate (LFP) batteries (FIGS. 5A-5C). Cathode, anode, and separator leachates were obtained through the pretreatment step illustrated in FIG. 5A. Both NMC and LFP batteries were fully discharged in a NaCl solution for two days before being dismantled to separate the cathode, anode, and separator materials. Each component was then dissolved in NMP solvent at 100°C overnight to leach lithium, along with fluorinated binders and carbon materials. The leachates were subsequently prepared by filtering out the insoluble residues using centrifugation and vacuum filtration. The final metal composition of the leachate solutions for each battery component is summarized in Table 2.

[0049] Lithium was successfully adsorbed in real spent battery solutions, exhibiting average uptake values of 0.558, 0.277, and 0.152 molLi / moli2C4MA in cathode, anode, and separators, respectively (FIGS. 5B and 5C). Notably, no metal uptake or release was detected, indicating a highly selective uptake of lithium. This selectivity is primarily attributed to the smaller cavity size of the crown ether, which is more compatible with lithium ions compared to other transition metals and degraded binders. The selectivity of crown ether ligands is predominantly influenced by the size compatibility between the target cations and the cavity size. The 12-crown-4 ether has demonstrated the strongest lithium complexation due to its optimal cavity size to ion radius ratio, surpassing that of any other alkali, alkaline-earth, and transition metals. Consequently, our system can selectively recover lithium in the presence of various cationic species in leachates, showcasing its exceptional effectiveness in practical lithium recovery applications.Beyond battery recycling, we envision that our copolymer design, featuring a redoxactive moiety and lithium-selective ligand, can be extended to selectively recover lithium from brine or seawater. Additionally, this approach can be adapted for the selective recovery of various cation species using different ligand materials, including crown ethers and cryptands.Table 2. Summary of Li and metal contents in NMP leachate of cathode, anode, and separator materials for both NMC and LFP batteries.Conclusions

[0050] Highly selective and reversible lithium recovery in various organic solvents has been demonstrated in the preceding examples through the incorporation of a redoxactive moiety (FPM Am) with lithium- selective ligand, 12-crown ether-4 moiety (12C4MA). The pre-activation step using cyclic voltammetry significantly enhances the mass transfer of lithium within the film during OCP adsorption, resulting in a 2-fold increase in lithium uptake for P(FPMAm-co-12C4MA) and a 2.6-fold increase for P(FPMAm-co-12C4MA-co-GMA) compared to the uptake values without the activation step. Upon the oxidation of ferrocene, bound lithium on the 12C4MA was released up to 77% for P(FPMAm-co-12C4MA) and 66% P(FPMAm-co- 12C4MA-co-GMA). The electrochemical regeneration strategy described in this disclosure effectively overcomes the challenges associated with releasing lithium from the crown ether. To assess the potential of this polymer design for industrial applications, lithium recovery from both NMC and LFP spent batteries was demonstrated, highlighting the promising selective recovery of lithium from cathodes, anodes, and separators. Owing to the cavity size of 12C4 moiety, lithium was selectively captured in the battery leachates, where several charged organic species and metal contents were dissolved in the solution. Overall, incorporating non-redox- active selective ligands with a redox-active moiety offers a versatile strategy not only to enhance the uptake of target species by improving mass transfer at the solvent-polymer interfaces but also to effectively release the target species by leveraging electrostatic repulsive forces. This copolymer strategy can serve as a stepping stone toward the electrification of selective adsorbents, offering environmentally friendly release and accelerated uptake of target substances.

[0051] This disclosure also includes the following aspects:

[0052] A first aspect relates to a copolymer for selective lithium recovery, the copolymer comprising: a redox monomer including a redox-active moiety; and an adsorbent monomer including a lithium- selective ligand.

[0053] A second aspect relates to the copolymer of the preceding aspect, wherein the redox monomer and the redox-active moiety comprise ferrocene, cobaltocene, or nitroxide.

[0054] A third aspect relates to the copolymer of any preceding aspect, wherein the redox monomer comprises ferrocenylpropylmethacrylamide (FPMAm), ferrocenylpropylmethacrylamide (FPMAm), 2-(methacryloyloxy)ethyl ferrocene carboxylate (FcMA), vinyl ferrocene (VP), ferrocenyl methyl methacrylate (FMMA), 2- (methacrylolyoxy)ethyl cobaltoceniumcarboxylate hexafluorophosphate (MAECoPFe), and / or TEMPO methacrylate.

[0055] A fourth aspect relates to the copolymer of any preceding aspect, wherein the adsorbent monomer and the lithium- selective ligand comprise a crown ether (CH CH O),,, an aza-crown ether (CH2CH2NH )„, a benzocrown ether, or a cryptand.

[0056] A fifth aspect relates to the copolymer of any preceding aspect, wherein the crown either comprises 12-crown-4 or 9-crown-3.

[0057] A sixth aspect relates to the copolymer of any preceding aspect, wherein the adsorbent monomer comprises 12-crown-4 ether methacrylate (12C4MA) or 9-crown-3 ether methacrylate (9C3MA).

[0058] A seventh aspect relates to the copolymer of any preceding aspect being crosslinked.

[0059] An eighth aspect relates to the copolymer of any preceding aspect comprising a crosslinking monomer.

[0060] A ninth aspect relates to the copolymer of any preceding aspect, wherein the crosslinking monomer comprises glycidyl methacrylate (GMA).

[0061] A tenth aspect relates to the copolymer of any preceding aspect being a terpolymer.

[0062] An eleventh aspect relates to the copolymer of any preceding aspect comprising P(FPMAm-co-12C4MA) or P(FPMAm-co-12C4MA-co-GMA).

[0063] A twelfth aspect relates to the copolymer of any preceding aspect, wherein a mole percentage of the redox monomer is in a range from 30% to 70%.

[0064] A thirteenth aspect relates to the copolymer of any preceding aspect, wherein a mole percentage of the adsorbent monomer is in a range from 30% to 70%.

[0065] A fourteenth aspect relates to the copolymer of any preceding aspect, wherein a mole percentage of the crosslinking monomer is in a range from 1% to 15%.

[0066] A fifteenth aspect relates to a working electrode for selective lithium recovery, the working electrode comprising: a film comprising the copolymer of any preceding aspect on an electrically conductive substrate.

[0067] A sixteenth aspect relates to the working electrode of the preceding aspect, wherein the electrically conductive substrate comprises carbon.

[0068] A seventeenth aspect relates to the working electrode of any preceding aspect, wherein carbon nanotubes are incorporated on the electrically conductive substrate and / or mixed with the copolymer.

[0069] An eighteenth aspect relates to the working electrode of any preceding aspect, wherein the film is configured with a non-planar morphology so as to have an increased surface area compared to a planar film.

[0070] A nineteenth aspect relates to an electrochemical device comprising: a working electrode including a film comprising a copolymer on an electrically conductive substrate, the copolymer comprising: a redox monomer including a redox-active moiety; and an adsorbent monomer including a lithium- selective ligand; a counter electrode spaced apart from the working electrode; a power supply configured for electrical connection to the working electrode and the counter electrode; and a cell configured to hold a treatment solution comprising lithium ions in contact with the working and counter electrodes.

[0071] A twentieth aspect relates to the electrochemical device of the preceding aspect, wherein the redox monomer and the redox-active moiety comprise ferrocene, cobaltocene, or nitroxide.

[0072] A twenty-first aspect relates to the electrochemical device of any preceding aspect, wherein the redox monomer comprises ferrocenylpropylmethacrylamide (FPMAm), ferrocenylpropylmethacrylamide (FPMAm), 2-(methacryloyloxy)ethyl ferrocene carboxylate (FcMA), vinyl ferrocene (VP), ferrocenyl methyl methacrylate(FMMA), 2-(methacrylolyoxy)ethyl cobaltoceniumcarboxylate hexafluorophosphate (MAECoPFe), and / or TEMPO methacrylate.

[0073] A twenty-second aspect relates to the electrochemical device of any preceding aspect, wherein the adsorbent monomer and the lithium-selective ligand comprise a crown ether (CH2CH2O)n, an aza-crown ether tCH CH NH )„, a benzocrown ether, or a cryptand.

[0074] A twenty-third aspect relates to the electrochemical device of the preceding aspect, wherein the crown either comprises 12-crown-4 or 9-crown-3.

[0075] A twenty-fourth aspect relates to the electrochemical device of any preceding aspect, wherein the adsorbent monomer comprises 12-crown-4 ether methacrylate (12C4MA) or 9-crown-3 ether methacrylate (9C3MA).

[0076] A twenty-fifth aspect relates to the electrochemical device of any preceding aspect, wherein the copolymer is crosslinked.

[0077] A twenty-sixth aspect relates to the electrochemical device of any preceding aspect, wherein the copolymer comprises a crosslinking monomer.

[0078] A twenty-seventh aspect relates to the electrochemical device of the preceding aspect, wherein the crosslinking monomer comprises glycidyl methacrylate (GMA).

[0079] A twenty-eighth aspect relates to the electrochemical device of any preceding aspect, wherein the copolymer is a terpolymer.

[0080] A twenty-ninth aspect relates to the electrochemical device of any preceding aspect, wherein the copolymer comprises any redox active moiety polymerized with lithium selective ligands, such as P(FPMAm-co-12C4MA), P(FPMAm-co-12C4MA-co- GMA), P(FPMAm-co-9C3MA), P(VF-co-12C4MA), P(FcMA-co-12C4MA), P(TMA- co-12C4MA), P(VF-co-9C3MA), P(FcMA-co-9C3MA), P(TMA-co-9C3MA), (FPMAm- co-9C3M A-co-GMA), P(VF-co- 12C4MA-co-GM A), P(FcMA-co- 12C4MA-co-GMA), P(TMA-co-12C4MA-co-GMA), P(VF-co-9C3MA-co-GMA), P(FcMA-co-9C3MA-co- GMA), and P(TMA-co-9C3MA-co-GMA).

[0081] A thirtieth aspect relates to the electrochemical device of any preceding aspect, wherein a mole percentage of the redox monomer is in a range from 30% to 70%.

[0082] A thirty-first aspect relates to the electrochemical device of any preceding aspect, wherein a mole percentage of the adsorbent monomer is in a range from 30% to 70%.

[0083] A thirty- second aspect relates to the electrochemical device of any preceding aspect, wherein a mole percentage of a crosslinking monomer is in a range from 1% to 15%.

[0084] A thirty-third aspect relates to the electrochemical device of any preceding aspect, wherein the electrically conductive substrate of the working electrode comprises carbon.

[0085] A thirty-fourth aspect relates to the electrochemical device of the preceding aspect, wherein carbon nanotubes are incorporated on the electrically conductive substrate and / or mixed with the copolymer.

[0086] A thirty-fifth aspect relates to a method for selectively recovering lithium, the method comprising: positioning a working electrode in a treatment solution comprising lithium ions, the working electrode including a film comprising a copolymer on an electrically conductive substrate, the copolymer comprising: redox monomers each including a redox-active moiety; and adsorbent monomers each including a lithiumselective ligand; electrochemically activating the working electrode, whereby the treatment solution penetrates the copolymer; after the electrochemical activation, exposing the working electrode to an open circuit potential, whereby lithium ions from the treatment solution are selectively bound to the lithium-selective ligands; after a time sufficient to achieve a desired uptake of lithium ions from the treatment solution by the lithium- selective ligands, replacing the treatment solution with a collection solution; and applying a desorption potential to the working electrode, whereby the redox-active moieties undergo oxidation and bound lithium ions are released into the collection solution from the lithium- selective ligands.

[0087] A thirty- sixth aspect relates to the method of the preceding aspect, wherein the treatment solution comprises leachate from spent lithium-ion batteries, brine or seawater.

[0088] A thirty- seventh aspect relates to the method of any preceding aspect, wherein the collection solution comprises an electrically conductive aqueous or organic liquid.

[0089] A thirty-eighth aspect relates to the method of any preceding aspect, wherein electrochemically activating the working electrode comprises carrying out cyclic voltammetry.

[0090] A thirty-ninth aspect relates to the method of any preceding aspect, wherein electrochemically activating the working electrode comprises alternately applying a positive potential and a negative potential to the working electrode.

[0091] A fortieth aspect relates to the method of any preceding aspect, wherein the time sufficient to achieve the desired uptake of lithium ions is in a range from 60 seconds to 60 minutes.

[0092] A forty-first aspect relates to the method of any preceding aspect, wherein the time is in the range from 10 minutes to 30 minutes.

[0093] A forty-second aspect relates to the method of any preceding aspect, wherein the desired uptake of lithium ions is at least 0.1 molLi / molActivesite and / or at most about 0.8 molLi / molActivesite, where the moln represents moles of the bound lithium ions, and the molActivesite represents moles of the adsorbent monomer.

[0094] A forty-third aspect relates to the method of any preceding aspect, wherein there is no uptake of metal cations other than the lithium ions.

[0095] A forty-fourth aspect relates to the method of any preceding aspect, wherein upon applying the desorption potential to the working electrode, at least 60% or at least 70% of the bound lithium ions are released.

[0096] A forty-fifth relates to the method of any preceding aspect, wherein the desorption potential is a positive potential in a range from 0.4 to 1.2 V.

[0097] A forty-sixth aspect relates to the method of any preceding aspect, wherein, after release of the bound lithium ions, the working electrode is reused one or more times with a new treatment solution.

[0098] A forty-seventh aspect relates to the method of any preceding aspect, wherein the redox monomer and the redox-active moiety comprise ferrocene, cobaltocene, or nitroxide.

[0099] A forty-eighth aspect relates to the method of any preceding aspect, wherein the redox monomer comprises ferrocenylpropylmethacrylamide (FPM Am), ferrocenylpropylmethacrylamide (FPMAm), 2-(methacryloyloxy)ethyl ferrocenecarboxylate (FcMA), vinyl ferrocene (VP), ferrocenyl methyl methacrylate (FMMA), 2- (methacrylolyoxy)ethyl cobaltoceniumcarboxylate hexafluorophosphate (MAECoPFe), and / or TEMPO methacrylate.

[0100] A forty-ninth aspect relates to the method of any preceding aspect, wherein the adsorbent monomer and the lithium- selective ligand comprise a crown ether (CH CH O),,, an aza-crown ether (CH2CH2NH )„, a benzocrown ether, or a cryptand

[0101] To clarify the use of and to hereby provide notice to the public, the phrases "at least one of , , ... and <N>" or "at least one of , , ... <N>, or combinations thereof" or ", , ... and / or <N>" are defined by the Applicant in the broadest sense, superseding any other implied definitions hereinbefore or hereinafter unless expressly asserted by the Applicant to the contrary, to mean one or more elements selected from the group comprising A, B, ... and N. In other words, the phrases mean any combination of one or more of the elements A, B, ... or N including any one element alone or the one element in combination with one or more of the other elements which may also include, in combination, additional elements not listed. Unless otherwise indicated or the context suggests otherwise, as used herein, "a" or "an" means "at least one" or "one or more."

[0102] While various embodiments have been described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible. Accordingly, the embodiments described herein are examples, not the only possible embodiments and implementations.

Claims

CLAIMS1. A copolymer for selective lithium recovery, the copolymer comprising: a redox monomer including a redox- active moiety; and an adsorbent monomer including a lithium- selective ligand.

2. The copolymer of claim 1, wherein the redox monomer and the redoxactive moiety comprise ferrocene, cobaltocene, or nitroxide.

3. The copolymer of claim 1, wherein the redox monomer comprises ferrocenylpropylmethacrylamide (FPMAm), ferrocenylpropylmethacrylamide (FPMAm), 2-(methacryloyloxy)ethyl ferrocene carboxylate (FcMA), vinyl ferrocene (VP), ferrocenyl methyl methacrylate (FMMA), 2-(methacrylolyoxy)ethyl cobaltoceniumcarboxylate hexafluorophosphate (MAECoPFe), and / or TEMPO methacrylate.

4. The copolymer of claim 1, wherein the adsorbent monomer and the lithium- selective ligand comprise a crown ether (ClLCtLO),,, an aza-crown ether (CH2CH2NH)n, a benzocrown ether, or a cryptand.

5. The copolymer of claim 4, wherein the crown either comprises 12-crown-4 or 9-crown-3.

6. The copolymer of claim 1, wherein the adsorbent monomer comprises 12- crown-4 ether methacrylate (12C4MA) or 9-crown-3 ether methacrylate (9C3MA).

7. The copolymer of claim 1 being crosslinked.

8. The copolymer of claim 1 comprising a crosslinking monomer.

9. The copolymer of claim 1, wherein the crosslinking monomer comprises glycidyl methacrylate (GM A).

10. The copolymer of claim 1 being a terpolymer.

11. The copolymer of claim 1 comprising P(FPMAm-co-12C4MA), P(FPMAm-co-12C4MA-co-GMA), P(FPMAm-co-9C3MA), P(VF-co-12C4MA), P(FcMA-co-12C4MA), P(TMA-co-12C4MA), P(VF-co-9C3MA), P(FcMA-co-9C3MA), P(TMA-co-9C3MA), (FPMAm-co-9C3MA-co-GMA), P(VF-co-12C4MA-co-GMA), P(FcM A-co- 12C4MA-co-GM A), P(TM -co- 12C4M A-co-GMA), P( VF-co-9C3MA-co- GMA), P(FcMA-co-9C3MA-co-GMA), and P(TMA-co-9C3MA-co-GMA).

12. The copolymer of claim 1, wherein a mole percentage of the redox monomer is in a range from 30% to 70%.

13. The copolymer of claim 1, wherein a mole percentage of the adsorbent monomer is in a range from 30% to 70%.

14. The copolymer of claim 1, wherein a mole percentage of the crosslinking monomer is in a range from 1% to 15%.

15. A working electrode for selective lithium recovery, the working electrode comprising: a film comprising the copolymer of claim 1 on an electrically conductive substrate.

16. The working electrode of claim 15, wherein the electrically conductive substrate comprises carbon.

17. The working electrode of claim 15, wherein carbon nanotubes are incorporated on the electrically conductive substrate and / or mixed with the copolymer.

18. The working electrode of claim 15, wherein the film is configured with a non-planar morphology so as to have an increased surface area compared to a planar film.

19. An electrochemical device comprising: a working electrode including a film comprising a copolymer on an electrically conductive substrate, the copolymer comprising: a redox monomer including a redox- active moiety; and an adsorbent monomer including a lithium- selective ligand; a counter electrode spaced apart from the working electrode; a power supply configured for electrical connection to the working electrode and the counter electrode; and a cell configured to hold a treatment solution comprising lithium ions in contact with the working and counter electrodes.

20. The electrochemical device of claim 19, wherein the redox monomer and the redox-active moiety comprise ferrocene, cobaltocene, or nitroxide.

21. The electrochemical device of claim 19, wherein the redox monomer comprises ferrocenylpropylmethacrylamide (FPM Am), ferrocenylpropylmethacrylamide (FPMAm), 2- (methacryloyloxy )ethyl ferrocene carboxylate (FcMA), vinyl ferrocene (VP), ferrocenyl methyl methacrylate (FMMA), 2-(methacrylolyoxy)ethyl cobaltoceniumcarboxylate hexafluorophosphate (MAECoPFe), and / or TEMPO methacrylate.

22. The electrochemical device of claim 19, wherein the adsorbent monomer and the lithium-selective ligand comprise a crown ether (CH CH O),,, an aza-crown ether (CH2CH2NH)n, a benzocrown ether, or a cryptand.

23. The electrochemical device of claim 22, wherein the crown either comprises 12-crown-4 or 9-crown-3.

24. The electrochemical device of claim 19, wherein the adsorbent monomer comprises 12-crown-4 ether methacrylate (12C4MA) or 9-crown-3 ether methacrylate (9C3MA).

25. The electrochemical device of claim 19, wherein the copolymer is crosslinked.

26. The electrochemical device of claim 19, wherein the copolymer comprises a crosslinking monomer.

27. The electrochemical device of claim 26, wherein the crosslinking monomer comprises glycidyl methacrylate (GM A).

28. The electrochemical device of claim 19, wherein the copolymer is a terpolymer.

29. The electrochemical device of claim 19, wherein the copolymer comprises P(FPMAm-co-12C4MA) or P(FPMAm-co-12C4MA-co-GMA), P(FPMAm-co-9C3MA), P(VF-co-12C4MA), P(FcMA-co-12C4MA), P(TMA-co-12C4MA), P(VF-co-9C3MA), P(FcMA-co-9C3MA), P(TMA-co-9C3MA), (FPMAm-co-9C3MA-co-GMA), P(VF-co-12C4MA-co-GM A), P(FcMA-co- 12C4MA-co-GM A), P(TMA-co- 12C4MA-co-GMA), P(VF-co-9C3MA-co-GMA), P(FcMA-co-9C3MA-co-GMA), and P(TMA-co-9C3MA- co-GMA).

30. The electrochemical device of claim 19, wherein a mole percentage of the redox monomer is in a range from 30% to 70%.

31. The electrochemical device of claim 19, wherein a mole percentage of the adsorbent monomer is in a range from 30% to 70%.

32. The electrochemical device of claim 19, wherein a mole percentage of a crosslinking monomer is in a range from 1% to 15%.

33. The electrochemical device of claim 19, wherein the electrically conductive substrate of the working electrode comprises carbon.

34. The electrochemical device of claim 33, wherein carbon nanotubes are incorporated on the electrically conductive substrate and / or mixed with the copolymer.

35. A method for selectively recovering lithium, the method comprising: positioning a working electrode in a treatment solution comprising lithium ions, the working electrode including a film comprising a copolymer on an electrically conductive substrate, the copolymer comprising: redox monomers each including a redox-active moiety; and adsorbent monomers each including a lithium- selective ligand; electrochemically activating the working electrode, whereby the treatment solution penetrates the copolymer; after the electrochemical activation, exposing the working electrode to an open circuit potential, whereby lithium ions from the treatment solution are selectively bound to the lithium- selective ligands; after a time sufficient to achieve a desired uptake of lithium ions from the treatment solution by the lithium- selective ligands, replacing the treatment solution with a collection solution; and applying a desorption potential to the working electrode, whereby the redox-active moieties undergo oxidation and bound lithium ions are released into the collection solution from the lithium- selective ligands.

36. The method of claim 35, wherein the treatment solution comprises leachate from spent lithium-ion batteries, brine or seawater.

37. The method of claim 35, wherein the collection solution comprises an electrically conductive aqueous or organic liquid.

38. The method of claim 35, wherein electrochemically activating the working electrode comprises carrying out cyclic voltammetry.

39. The method of claim 35, wherein electrochemically activating the working electrode comprises alternately applying a positive potential and a negative potential to the working electrode.

40. The method of claim 35, wherein the time sufficient to achieve the desired uptake of lithium ions is in a range from 60 seconds to 60 minutes.

41. The method of claim 35, wherein the time is in the range from 10 minutes to 30 minutes.

42. The method of claim 35, wherein the desired uptake of lithium ions is at least 0.1 molLi / molActivesite and / or at most about 0.8 molij / molActivesite, where the moln represents moles of the bound lithium ions, and the molActivesite represents moles of the adsorbent monomer.

43. The method of claim 35, wherein there is no uptake of metal cations other than the lithium ions.

44. The method of claim 35, wherein upon applying the desorption potential to the working electrode, at least 60% or at least 70% of the bound lithium ions are released.

45. The method of claim 35, wherein the desorption potential is a positive potential in a range from 0.4 to 1.2 V.

46. The method of claim 35, wherein, after release of the bound lithium ions, the working electrode is reused one or more times with a new treatment solution.

47. The method of claim 35, wherein the redox monomer and the redox-active moiety comprise ferrocene, cobaltocene, or nitroxide.

48. The method of claim 35, wherein the redox monomer comprises ferrocenylpropylmethacrylamide (FPMAm), ferrocenylpropylmethacrylamide (FPMAm), 2-(methacryloyloxy)ethyl ferrocene carboxylate (FcMA), vinyl ferrocene (VP), ferrocenyl methyl methacrylate (FMMA), 2-(methacrylolyoxy)ethyl cobaltoceniumcarboxylate hexafluorophosphate (MAECoPFe), and / or TEMPO methacrylate.

49. The method of claim 35, wherein the adsorbent monomer and the lithiumselective ligand comprise a crown ether (CH CH O),,, an aza-crown ether (CH CH NH),,, a benzocrown ether, or a cryptand.

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