A device and method for extracting a group (i) metal from a spent battery

Abstract

There is provided a device for extracting a Group (I) metal from a spent battery, the device comprising: an anode comprising material from the spent battery, wherein the material comprises the Group (I) metal; a cathode; a first electrolyte; a second electrolyte; and an ion-selective membrane, selectively permeable to ions of the Group (I) metal. There is also provided a method of extracting a Group (I) metal from a spent battery, the method comprising: contacting an anode with a first electrolyte, the anode comprising material from the spent battery, wherein the material comprises the Group (I) metal; contacting a cathode with a second electrolyte; and applying an electrical potential between the anode and the cathode to obtain the Group (I) metal at the cathode, wherein the first electrolyte and the second electrolyte are separated with an ion-selective membrane, selectively permeable to ions of the Group (I) metal.

Description

[0001] A DEVICE AND METHOD FOR EXTRACTING A GROUP (I) METAL FROM A SPENT BATTERY

[0002] Technical Field

[0003] The present invention relates to a device and method for extracting a Group (I) metal

[0004] 5 from a spent battery.

[0005] Background

[0006] Demand for energy storage is on an increasing trend, with lithium-ion batteries (LIBs) accelerating the growth in demand due to adoption of portable electronics and electronic vehicles. Lithium reserve on land is limited and geographically uneven, and production involves mining from salt-lake brines and ores, followed by separation / purification through chemical treatment, which is slow and inefficient and requires heavy use of fresh water and waste treatment. With scarcity of raw lithium, there is interest in recycling of LIBs to obtain lithium metal.

[0007] However, current recycling methods for LIBs involve pyrometallurgy and / or

[0008] 15 hydrometallurgy in metal extraction, which produce secondary waste which pollutes the environment. Direct recycling methods are highly dependent on charging state and composition of batteries, and thus not easily adaptable across all LIBs.

[0009] There is therefore a need for an improved device and method for extracting a Group (I) metal from a spent battery.

[0010] 20 Summary of the invention

[0011] The present invention seeks to address these problems, and / or provides an improved device and method for extracting a Group (I) metal from a spent battery.

[0012] According to a first aspect, there is provided a device for extracting a Group (I) metal from a spent battery, the device comprising: an anode comprising material from the spent battery, wherein the material comprises the Group (I) metal; a cathode; a first electrolyte; a second electrolyte; and

[0013] 30 an ion-selective membrane, selectively permeable to ions of the Group (I) metal. The material from the spent battery may comprise any suitable material. For example, the material may comprise compounds with general formula NaTMC and KTMO2 (where TM represents a transition metal), lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, lithium nickel manganese cobalt oxide, lithium, sodium, potassium, nickel, cobalt, manganese, or compounds and mixtures thereof.

[0014] According to a particular aspect, the Group (I) metal may comprise lithium, sodium, potassium, or mixtures and combinations thereof.

[0015] The cathode may comprise any suitable material. For example, the cathode may comprise a transition metal. The transition metal may comprise any suitable transition metal. For example, the transition metal may comprise copper, titanium, molybdenum, or a combination thereof. The cathode may further comprise a polymer coating on a surface of the transition metal.

[0016] According to a particular aspect, the first electrolyte and the second electrolyte may be different. The first electrolyte may comprise an aqueous solution. The second electrolyte may comprise a non-aqueous solution.

[0017] According to a particular aspect, the ion-selective membrane may comprise a compound with a NASICON crystal structure. The ion-selective membrane may be stable in the first electrolyte and the second electrolyte.

[0018] According to a second aspect, there is provided a method of extracting a Group (I) metal from a spent battery, the method comprising: contacting an anode with a first electrolyte, the anode comprising material from the spent battery, wherein the material comprises the Group (I) metal; contacting a cathode with a second electrolyte; and applying an electrical potential between the anode and the cathode to obtain the Group (I) metal at the cathode, wherein the first electrolyte and the second electrolyte are separated with an ion- selective membrane, selectively permeable to ions of the Group (I) metal.

[0019] The electrical potential may be 0.1-3.0 V. The method may be carried out under an inert atmosphere.

[0020] According to a particular aspect, the method may further comprise pre-treating the ion- selective membrane. The pre-treating may comprise passivation of a surface of the ion- selective membrane.

[0021] Brief Description of the Drawings

[0022] In order that the invention may be fully understood and readily put into practical effect there shall now be described by way of non-limitative example only exemplary embodiments, the description being with reference to the accompanying illustrative drawings. In the drawings:

[0023] Figure 1 shows a set-up and results of an initial proof-of-concept; Figure 1 (a) shows a schematic representation of a device for extracting lithium via electrolysis; Figure 1(b) shows electrochemical stability window of water at different pHs and operating windows of various LIB electrode materials; Figure 1 (c) shows the stability of a H-type cell based on the lithium superionic conductor-type lithium-ion selective membrane; Figure 1(d) shows XRD pattern of pure copper foil and copper foil with lithium deposit; Figure 1(e) shows an enlarged XRD pattern showing that lithium has completely reacted into lithium carbonate in air;

[0024] Figures 2(a) and (b) show high-resolution powder XRD and Rietveld refinement results of (a) spent LiFePO4 (including graphite) and (b) spent FePO4 after lithium extraction (including graphite); Figure 2(c) shows a schematic of a LiFePC crystalline structure transformed after lithium extraction; Figure 2(d) shows Li extraction profile based on roll-to-roll setups under the voltage drive; Figure 2(e) shows Operando XRD response from the spent LIFePC electrode and the corresponding Li selectivity during the charging process;

[0025] Figure 3 shows the applicability of the device and method in extracting lithium from various commercially available spent LIBs; Figures 3(a) and 3(b) show the charge curve and Operando XRD response from spent NCM811 , respectively; Figures 3(c) and 3(d) show the charge curve and Operando XRD response from spent LOO, respectively; Figures 3(e) and 3(f) show the charge curve and Operando XRD response from spent LMO, respectively; Figure 4 shows TOF-SIMS sputtering profile of (a) spent LFP, (b) spent NCM811 , (c) spent LCO, and (d) spent LMO electrode, before and after lithium extraction;

[0026] Figure 5 shows the effect of different organic solvents for lithium electrodeposition, with SEM images of 0.1 mAh cm2of lithium electrodeposited on copper without a PDADMA coating (scale bars are 3 pm), using (a) dimethyl carbonate, (b) N,N- dimethylformamide, (c) propylene carbonate, (d) acetonitrile;

[0027] Figure 6 shows the effect of current densities for lithium electrodeposition, with SEM images of different current densities from 0.2 to 1.6 mA cm-2(scale bars are 20 pm), using (a) 0.2 mA, (b), 0.4 mA, (c) 0.8 mA, (d) 1.6 mA;

[0028] Figure 7 shows high-resolution XPS spectra of lithium thin film on a copper substrate in Li 1s regions showing depth profile at an etching rate of 10 nm min1(thickness of the etched layer is shown on the right side);

[0029] Figure 8(a) shows high-resolution XPS spectra of lithium thin films on a copper substrate in (a) C 1s, (b) O 1s, (c) F 1s, and (d) S 2p regions showing depth profile at etching rate of 10 nm min1(thickness of the etched layer is shown on the right side);

[0030] Figure 9 shows depth etching XPS results of atomic concentrations as a function of sputter time and etched layer thickness of Li 1s, F 1s, O 1s, C 1s, and S 2p;

[0031] Figure 10 shows voltage profiles of symmetric Li thin film | Li thin film cell with planar Cu foil as a current collector;

[0032] Figure 11(a) shows cyclic voltammetry curves of electrodeposited lithium thin film- LiFePC>4 battery scanned at a rate of 0.1 mV s’1; Figure 11(b) shows charge and discharge curves of lithium thin film-LiFePO4 battery at different numbers of cycles; Figure 11 (c) shows long-term cycling performance of lithium thin film-LiFePC battery at the current density of 1C; Figure 11(d) shows cyclic voltammetry curves of electrodeposited lithium thin film-NCM811 battery scanned at a rate of 0.1 mV s1; Figure 11(e) shows charge and discharge curves of lithium thin film-NCM811 battery at different numbers of cycles; Figure 11 (f) shows long-term cycling performance of lithium thin film-NCM811 battery at the current density of 1 C; and Figure 12 shows cyclic voltammetry curves of regenerated lithium metal batteries scanned at a rate of 0.1 mVs-1; Figure 12(a) shows free anode Li-LIFePC battery showing no capacity and no open circuit voltage in comparison with electrodeposited Li thin film-LiFePC cell; Figure 12(b) shows electrodeposited Li thin film-LiFePCU cell having open circuit voltage and reversible redox process; Figures 12(c) and (d) show electrodeposited Li thin film-NCM811 cell capable of working on larger electrochemical voltage of 2.6-4.5 V compared to traditional voltage window of 3.0-4.3 V.

[0033] Detailed Description

[0034] As explained above, there is a need for an improved device and method for extracting a Group (I) metal from a spent battery.

[0035] In general terms, the present invention provides a device for extracting a Group (I) metal from a spent battery. In particular, the device allows for a quick and simple way to extract high-purity Group (I) metal from spent batteries, due to the high ion selectivity of the membrane, which allows only ions of the Group (I) metal through the membrane to be deposited on the cathode, blocking other impurity metal cations and even H+ions. The device further eliminates the need for costly and energy-intensive separation and refinement of the recovered Group (I) metals. The cathode may also be easily replaced at any desired time after deposition of Group (I) metals, and the first and second electrolytes may be re-used in repeated processes, which reduces the amount of secondary waste. Additionally, the device may be used across various spent battery types without being specific to any charging state or composition of batteries.

[0036] In the present disclosure, the use of the singular includes the plural unless specifically stated otherwise. It should be noted that, as used in the specification and the appended claims, the singular forms “a”, “an” and “the” include plural referents unless the context clearly dictates otherwise. Further, the use of the term “including”, “comprising”, and “having” as well as other forms, such as “include”, “comprise”, “have” are not considered limiting.

[0037] According to a first aspect, there is provided a device for extracting a Group (I) metal from a spent battery, the device comprising: an anode comprising material from the spent battery, wherein the material comprises the Group (I) metal; a cathode; a first electrolyte; a second electrolyte; and an ion-selective membrane, selectively permeable to ions of the Group (I) metal.

[0038] In the present disclosure, references to the term metal may be defined to encompass all such products, such as metals, semi-metals, alloys, intermetal lies. Metal may also be considered, where appropriate, to include partially reduced products.

[0039] In the present disclosure, references to the term anode may be defined to be the anode in the device for Group (I) metal extraction, and not the negative electrode in a conventional battery. Thus, the anode may correspond to the positive electrode of the spent battery. The anode may be any suitable anode. For example, the anode may comprise, but is not limited to, lithium iron phosphate (LFP).

[0040] The material from the spent battery comprised in the anode may be any suitable material. The material may be coated on a surface of the anode. The material may comprise, but is not limited to, compounds with general formula NaTMO2 and KTMO2 (where TM represents a transition metal), lithium iron phosphate (LFP), lithium cobalt oxide (LCO), lithium manganese oxide (LMO), lithium nickel manganese cobalt oxide (NCM), lithium, sodium, potassium, nickel, cobalt, manganese, or compounds and mixtures thereof.

[0041] The device may extract any metal from a spent battery. For example, the device may extract a Group (I) metal, nickel, cobalt, Ni-Co alloys, or mixtures and combinations thereof. In particular, the device may extract a Group (I) metal. According to a particular aspect, the Group (I) metal may comprise lithium, sodium, potassium, or mixtures and combinations thereof.

[0042] The cathode may be any suitable cathode. The cathode may comprise any suitable metal that is chemically stable and inert against the Group (I) metals, to act as a current collector. The cathode may comprise ternary materials and / or the corresponding high-entropy oxides, to serve as a positive electrode for metal extraction. For example, the cathode may comprise a transition metal. For example, the cathode may comprise, but is not limited to, copper, titanium, molybdenum, aluminium, or a combination thereof. The cathode may further comprise a polymer coating on a surface of the transition metal. The polymer coating may comprise any suitable polymer such that dendrite growth during the deposition of Group (I) metals is inhibited. The polymer coating may comprise a high charge density cationic polymer. For example, the polymer coating may comprise, but is not limited to, polydiallyldimethylammonium chloride.

[0043] The first and second electrolyte may be any suitable electrolyte. According to a particular aspect, the first electrolyte and the second electrolyte may have the same or different composition from each other. According to a particular embodiment, the first electrolyte and the second electrolyte may be different from each other.

[0044] According to a particular embodiment, the first electrolyte may comprise an aqueous solution. The aqueous solution may comprise a lithium salt. In particular, the aqueous solution may comprise lithium sulphate, lithium chloride, or mixtures and combinations thereof.

[0045] According to a particular embodiment, the second electrolyte may comprise a nonaqueous solution. The non-aqueous solution may comprise a lithium salt in an organic solvent. In particular, the non-aqueous solution may comprise lithium perchlorate, lithium bis(trifluoromethane)sulfonimide (LITFSI), lithium hexafluorophosphate, or mixtures and combinations thereof. The organic solvent may be propylene carbonate, dimethyl carbonate, N,N-dimethylformamide, acetonitrile, dimethoxyethane, 1 ,3- dioxolane, or mixtures and combinations thereof.

[0046] The ion-selective membrane may be any suitable membrane which is selectively permeable to ions of the Group (I) metal. The ion-selective membrane may be selectively permeable only to ions of the Group (I) metal and no other ions, and may have chemical and electrochemical stability in electrolytes. According to a particular aspect, the ion-selective membrane may comprise a compound with a NASICON crystal structure. For the purposes of the present disclosure, references to a NASICON crystal structure refer to a network of general formula AIB2(DO4)3 where A is a monovalent cation, B is either a single or combination of tri, tetra and penta valent ions, and D is phosphorous (P) or silicon (Si). The compound may be any suitable compound, with a general formula of XM2(PO4)3, where X may be a Group (I) metal, and M may be titanium, germanium, zirconium, hafnium, tin, or with a general formula Xi+xZr2SixP3-xOi2, where X may be a Group (I) metal, and 0 < x < 3.

[0047] The ion-selective membrane may be stable in the first electrolyte and the second electrolyte. In particular, the ion-selective membrane may have chemical and electrochemical stability in the first electrolyte and the second electrolyte, thereby ensuring efficiency of extraction of the Group (I) metal.

[0048] According to a second aspect, there is provided a method of extracting a Group (I) metal from a spent battery, the method comprising: contacting an anode with a first electrolyte, the anode comprising material from the spent battery, wherein the material comprises the Group (I) metal; contacting a cathode with a second electrolyte; and applying an electrical potential between the anode and the cathode to obtain the Group (I) metal at the cathode, wherein the first electrolyte and the second electrolyte are separated with an ion- selective membrane, selectively permeable to ions of the Group (I) metal.

[0049] The applying an electrical potential between the anode and the cathode may be by any suitable means. For example, the electrical potential may be applied by, but not limited to, a DC power supply, or an AC power supply. The applying an electrical potential may be under any suitable current density based on electrode sizes. For example, with a 2 cm x 2 cm electrode, the applying an electrical potential may be under a current density of 0.2 to 1.6 mA cm-2. The applying results in a provision of a polarization field and a driving force for moving Group (I) metal ions dissolved from the material from the spent battery at the anode to the cathode, facilitating reduction of the Group (I) metal ion at the cathode.

[0050] The applying may be for a suitable period of time. For example, the applying may be for 1-10 hours. In particular, the applying may be for 2-9, 3-8, 4-7, 5-6 hours. Even more in particular, the applying may be for 3-6 hours.

[0051] The electrical potential may be any suitable electrical potential that does not exceed the decomposition voltage of water at the anode. According to a particular aspect, the electrical potential may be 0.1-3.0 V. In particular, the electrical potential may be 0.2- 2.8 V, 0.4-2.6 V, 0.6-2.4 V, 0.8-2.2 V, 1.0-2.0 V, 1.2-1 .8 V, 1.4-1.6 V.

[0052] The method may be carried out under an inert atmosphere. For example, the inert atmosphere may comprise, but is not limited to, argon.

[0053] According to a particular aspect, the method may further comprise pre-treating the ion- selective membrane. The pre-treating may comprise any suitable pre-treating steps to ensure that the membrane does not react with the first electrolyte and the second electrolyte. For example, the pre-treating may comprise passivation of a surface of the ion-selective membrane. The passivation may comprise, but is not limited to, forming a coating, oxidising.

[0054] Having now generally described the invention, the same will be more readily understood through reference to the following example which is provided by way of illustration, and is not intended to be limiting.

[0055] Example

[0056] Materials and methods

[0057] An electrolysis device was fabricated with three components: (1) an anode chamber (including material roll from the positive electrode of a spent battery); (2) a lithium-ion selective membrane, and (3) a cathode chamber (including fresh copper foil roll or copper foil coated with a thin layer of polymer). A schematic diagram of the device is shown in Figure 1(a). The electrolytes used were 0.5 M LiCIO4-propylene carbonate (PC) solution or 0.5 M lithium bis(trifluoromethane)sulfonimide (LiTFSI) dissolved in 1 ,3-dioxolane / 1 ,2-dimethoxyethane (DOL / DME, 1:1 by volume) without any additives as a background electrolyte in the cathode chamber, and 0.5 M Li2SO4 aqueous solution as another background electrolyte in the anode chamber, separated by a Lii+xAlyGe2.y(PO4)3 (LAGP) solid-state electrolyte membrane.

[0058] During electrolysis, the device was charged under constant external current. An electric field was applied, and at the anode, the cathode material of spent batteries released lithium ions and lost electrons. Li+in the cathode material of spent batteries then moved from the anode chamber toward the lithium-ion-selective solid-state electrolyte membrane. As the membrane is lithium-ion-selective, only lithium ions were transported to the cathode chamber, while other cations (such as H+) were blocked and remained in the anode compartment. Meanwhile, on the cathode side, lithium ions gained electrons and were reduced to metallic lithium on the copper foil. The electrochemical reactions that occurred on the electrode can be described as follows:

[0059] Anode: — (1)

[0060] LiMO2- Li++ e- + MO2(M = Ni, Co, Mn) — (2)

[0061] Cathode: Li+ + e- -* Li (s) — (3)

[0062] For initial proof of concept, a spent black mass electrode was fabricated simulating an extracted electrode. A common electrode coating was prepared on a smooth graphite paper surface by slurry coating, and thereafter, a thin lithium metal film was deposited on a copper foil by electrolysis extraction. Through this circuit loop, Li ions will be continuously extracted from the spent cathode roll into the copper foil roll at a speed controlled by the applied current.

[0063] Results and discussion

[0064] Figure 1(b) shows the electrochemical stability window of water at different pHs and operating windows of various lithium-ion battery (LIB) electrode materials. The majority of the charging electrochemical platform falls well into a stable electrochemical window of water. During electrolysis, the charging voltage of the entire device cannot exceed the decomposition voltage of water in the anode chamber.

[0065] The stability of LAGP against aqueous solution and non-aqueous electrolyte was verified before device deployment, as the stability of LAGP in aqueous solutions directly affects the lithium recovery efficiency of spent LIBs. In particular, both the bulk and interfacial stability of LAGP when contacted with aqueous solutions (0.5 M U2SO4) and non-aqueous electrolyte (0.5 M UCIO4 / PC) were monitored by electrochemical impedance spectroscopy (EIS) using a H-type cell design. Initially, the LA.GP had some interactions with both solutions before and after lithium extraction, as seen by the variation of interfacial resistance in Figure 1(d). Additionally, the LAGP interface was stabilized after exposure to non-aqueous electrolytes and in aqueous electrolytes owing to the passivation of LAGP. Figure 1(d) and Figure 1(e) show the X-ray diffraction (XRD) patterns of pure copper foil and copper foil deposited with lithium after being left in the air for one month. In Figure 1(d), mainly the peak of the metal copper foil can be seen. When 15-40° was enlarged in Figure 1(e), lithium was completely reacted into lithium carbonate, which corresponds to XRD standard card U2CO3 phase (FDF#22-1141), which confirmed the successful extraction of lithium from the pristine LiFePC>4 electrode under the imposed current. The scanning electron microscope (SEM) and energy-dispersive spectroscopy (EDS) elements mapping of the LAGP membrane also indicated that the LAGP is stable against aqueous solution and organic electrolyte during the process of Li extraction.

[0066] Lithium extraction from I F 18650 battery

[0067] For further proof of concept, a commercial LIFePO4 battery (IFR18650) was pre-treated through discharging and dismantling to obtain LiFePC powder and used for lithium extraction. A 16 mg LIFePC electrode which had 12.8 mg LIFePC>4 material was loaded into the anode compartment. The setup was charged at a current of 0.1 mA cm'2until the voltage increased to 3.0 V. During the lithium extraction process, the lithium iron phosphate containing graphite before and after lithium extraction was subjected to XRD Rietveld refinement analysis (Figure 2(a) and Figure 2(b)). The analysis results found that although the graphite peak was very strong, the changes in the lithium iron phosphate peak were still clearly visible. The analysis of Highscore Plus software and Vesta software, as shown in Figure 2(c), shows the changes in the lattice structure during the lithium extraction process. The specific lattice parameters are listed in Table 1.

[0068]

[0069] Table 1 : Rietveld refinement results of spent LiFeFCh and spent FeP04 (including graphite) after lithium extraction using the HighScore Plus software

[0070] In order to eliminate the influence of graphite, the pure lithium iron phosphate electrodes without current collectors were prepared for Operando XRD testing. Driven by an external electric field as shown in Figure 2(d), Li extraction was demonstrated by applying a constant current density of 0.1 mA cm-2. As shown in Figure 2(e), the transformation process of the specific crystal planes was investigated during the charging process. The results show the disappearance of the crystal planes of lithium iron phosphate (002) (102), (112), (113), (313) and (400), After charging was completed, only the iron phosphate peaks (210), (211), (121), (103) and (113) remained, which demonstrates that spent batteries cathode material LiFePC experienced a significant structural change and transformed to FePC after lithium extraction process. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) characterization was conducted for the LiFePCU electrode before and after Li extraction, which further verified the lithium de-intercalation in lithium iron phosphate electrodes after extraction processing.

[0071] Lithium extraction from other commercially available batteries

[0072] To validate the universal applicability of the lithium extraction system, the structural changes of cathode materials for other spent Li batteries (containing NCM811 , LCO, and LMO cathodes) were investigated through similar Operando XRD characterization during the extracting lithium process. The Operando XRD results presented in Figure 3 provide corroboration for the electrochemical lithium extraction behaviours observed in the spent cathode materials. Specifically, for the spent NCM811 electrode in Figure 3(a) and (b), the change of phase composition was monitored during the charging process, which is divided into two stages: (1) peaks for LiNi0.8Co0.1Mn0.1O2 at 18.6°, 36.5°, and 64.8° (28) gradually disappeared, demonstrating that lithium extraction and original crystal structural restoration mainly occurred in this stage; and (2) NCM811 crystal structure gradually stabilized and no more peak shifts were observed after the lithium extraction process.

[0073] For the spent delithiation Lii.xCoO2 electrode in Figure 3(c) and (d), XRD patterns exhibited no clear differences compared to pristine LCO electrodes in the beginning of the process. A slight shift of the (003) plane to lower 28 angles was observed in the delithiated electrode due to a lower Li / Co atomic ratio. Additionally, element intensity variations in the LCO electrode before and after lithium extraction were detected, validating the feasibility and practicality of the spent LCO batteries system. Also, for spent LMO batteries in Figures 3(e) and (f), similar results showed that during the initial charging process, lithium ions were slowly extracted, and then, at the critical charging potential, the crystal lattice of the entire positive electrode would undergo a significant change. In total, all these results demonstrate that this strategy is capable of tackling multiple LIB chemistries, including lithium iron phosphate, lithium cobalt (Hi) oxide, lithium manganese oxide, and the increasingly relevant lithium nickel manganese cobalt oxide.

[0074] TOF-SIMS three-dimensional images and sputter profiles were also conducted to visually illustrate the lithium content and elemental distributions from various spent lithium battery cathodes during the lithium extraction process. As shown in Figure 5, the TOF-SIMS spectra were collected over time from the ejected secondary ions sputtered by Ar ions. After sputtering, a relatively uniform distribution of secondary ions of Li+and Fe2+species was observed on the surface of the pristine LFP electrode, while for the LFP electrode after Li extraction, the signal of Li+species was reduced and Fe2+species remained almost unchanged. Furthermore, the three-dimensional visualization of TOF-SIMS demonstrated that the signals of Ni2+, Co2+, and Mn2+ions in the electrode after lithium extraction remained nearly unchanged, while the signal of Li+diminished with sputtering time. This observation confirmed the uniform and homogeneous nature of lithium extraction from the NCM811 electrode. Moreover, the TOF-SIMS three-dimensional images in the spent LCO electrode and LMO electrode were also consistent with LFP and NCM811 results, which also demonstrated that the lithium extraction from these spent electrodes is uniform and homogeneous.

[0075] The total sputtering curves and the sputtering curves of each element distribution are shown in Figure 4(a)-(d). The results indicate that the downward shift of the entire curve is mainly caused by changes in lithium extraction. The successful deintercalation from various spent batteries cathode exhibits excellent Li recovery performances based on the examples of the method.

[0076] The electrodeposition of lithium metal is a critical process in the lithium extraction from spent lithium batteries due to the high reactivity of the lithium metal. The high reactivity of the lithium metal causes short cycling lifetimes and dendrite growth in lithium-ion batteries that can pose a serious safety issue. During the whole electrolysis process in the device, the cathode chamber must maintain an inert Ar environment to prevent rapid reactions between lithium metal and air. First, during the electrochemical deposition process, the copper foil cathode became metallic gray and no gas evolution was observed on either electrode. After electrolysis, the copper foil cathode was rapidly transferred to deionized water. Gas was generated immediately, and the colour of metallic grey simultaneously faded. The pH value of the water increased after immersion of the copper foil.

[0077] To optimize the electrochemical deposition of lithium metal, different organic solvents and current densities were investigated to highlight the synergistic effect of the solvation environment of ions and interfacial tailoring on selectivity. The initial experiment used copper to investigate solely the effect of the solvation environment of ions.

[0078] Organic solvents

[0079] As shown in Figures 5(a)-(d), the lithium morphology indicated that the solvents used in the cathode chamber also resulted in significantly different morphologies formed on the surface of copper foil, due to differences in the desolvation process of lithium. By observing the early stages of lithium metal deposition, the morphology of the lithium particles was strongly influenced by the chemistry of the polymer coating owing to polymer dielectric constant and surface energy as two key descriptors of the lithium deposit size, as shown in Table 2.

[0080] Table 2: Physical properties of organic solvents. All data points were obtained at room temperature

[0081] Current density

[0082] The current density was varied from 0.2 to 1.6 mA mAh cm2, at 0.2 mA, 0.4 mA, 0.8 mA, and 1.6 mA. As shown in Figures 6(a)-(d), when adding polymer-coated copper foil surface as the current density increases, the lithium cluster particles formed on the surface of the copper foil became larger. The Li deposits formed uniform particles with a high density and uniformity across the electrode. This indicates that the thin polymer coating affected the nucleation processes but did not provide a sufficiently uniform coating to influence the overall deposition coverage.

[0083] Purity of extracted lithium and applications

[0084] The purity and application value of the electrodeposited lithium metal thin films were evaluated. The deposition of relatively thick layers of highly crystalline Li metal was further confirmed through X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and the regenerated lithium metal batteries performance.

[0085] XPS was used to determine the composition of the solid-electrolyte interphase (SEI) layer and estimate its thickness for lithium metal battery electrode materials. High- resolution XPS spectra were acquired for lithium metal thin films. Freshly deposited lithium samples were promptly transferred from inert atmospheres (Ar) to the XPS chamber to minimize exposure to air. Initially, XPS measurements were performed on pristine samples to ascertain their initial surface composition. Subsequently, Ar+ sputtering was conducted in successive intervals to obtain depth profile information of the film, starting from the surface (0 nm) and progressing down to a depth of 200 nm. Non-sputtered, depth XPS profiling shows uniform distribution of Li° from surface to the bulk, which is determined by the characteristics of lithium metal revealing the presence of Li as the main element, as illustrated in Figure 7. The alteration in peak shift predominantly arose from the impact of residual organic solvents and electrolytes (or their decomposition products). To acquire supplementary information about the non- metal contents, and to determine the composition of residue, and estimate the SEI layer thickness, high-resolution XPS spectra of four impurities C 1s, O 1s, F 1s, and S 2p were recorded (Figure 8). Peak deconvolution of the first scan in these regions shows that lithiated products of residual and decomposed organic electrolyte salts (LiF, LiOH, LiNxOy, and LixSOy, etc ). After the Ar+ sputtering of the topmost 10 nm of the film, the localization of these elements to the film surface gradually disappeared, suggesting that high-energy Ar+sputtering beams induced the decomposition reaction of residue. Figure 9 shows that fluorine was the predominant impurity in the electrolytically deposited lithium film under H2O / O2-free conditions. Observing two distinct crystalline structures of Li and LiF, and the consistent presence of LiF throughout the sample suggests the formation of pure lithium metal encapsulated by a thin layer of LiF. This layer is anticipated to serve as a barrier, inhibiting lithium dendrite growth and maintaining parallel alignment of the lithium metal. In applications involving energy storage, the lithium metal with LiF could potentially enhance Li-ion conductivity and act protectively by preventing the formation of SEI layers due to exposure to organic electrolytes, thereby mitigating dendrite growth during the electrodeposition process.

[0086] AFM 3D topographic mapping revealed that the pure Cu foil had the bumpiest and most cracked surface, with an average surface roughness (Ra) of 187 nm. The surface of electrodeposited lithium thin film had a more compact and denser surface, with the lowest Ra of 44.9 nm. The practical thickness of electrodeposited lithium metal films measured from cross-sectional SEM images was 13.9 or 97.7 pm.

[0087] The lifetime of lithium metal batteries depends largely upon critical parameters associated with Li-electrolyte interfacial reactions. In practical cell configurations characterized by high cathode loading and thin lithium film deposition, accelerated deterioration primarily arises from the formation of substantial and porous SEI layers on the lithium metal surface. This phenomenon induces concurrent depletion of both electrolyte components and lithium metal itself. Consequently, the structural integrity of the lithium metal is compromised, leading to mechanical pulverization and consequent swelling of the cell. These deleterious effects not only curtail the cycling stability of the anode but also amplify concerns pertaining to overall battery safety. Therefore, even with abundant electrolytes, the cycle life of a lithium metal battery may be reduced to less than 30 cycles when the Li foil thickness is limited to 50 pm. To achieve long-term cycling lifetime of lithium metal batteries, the thickness of lithium metal films was larger than 100 pm.

[0088] The electrochemical behaviour of Li plating / stripping and the cycling stability were examined by using a symmetric cell with Li metal thin films on the planar Cu foil (Figure 10). A hollow spacer was used to substitute for the Celgard separator to allow possible internal short circuits. During Li plating / stripping at 0.5 mA cm2, after cycling for 325 hours, no sign of a short circuit was observed, indicating retarded growth of dendritic Li on an electrodeposited lithium metal surface.

[0089] To demonstrate the application potential of lithium metal thin films as lithium metal battery anode, full cells were assembled by using electrodeposited lithium films as anode and commercial LiFePC and LiNi0.8Mn01Co01O2 as cathode. The cyclic voltammetry curves are shown in Figures 11 (a)-(f). Both type cells showed an excellent reversible redox process at a scan rate of 0.1 mV s1. Both cells demonstrated good electrochemical cycling performance at a current density of 1C.

[0090] To compare against the anode-free lithium metal battery, pure Cu foil as anode and LiFePO4 as cathode was assembled with abundant electrolyte. As shown in Figure 12, the anode-free cell indicated no open circuit voltage and poor reversible process. Additionally, when high voltage electrolyte was used, the lithium metal thin films- NCM811 cell worked on 2.6-4.5 V. These results indicate the feasibility of employing the electrodeposited lithium metal thin films as lithium metal battery anode for practical applications. Whilst the foregoing description has described exemplary embodiments, it will be understood by those skilled in the technology concerned that many variations may be made without departing from the present invention.

Claims

1. Claims1. A device for extracting a Group (I) metal from a spent battery, the device comprising: an anode comprising material from the spent battery, wherein the material comprises the Group (I) metal; a cathode; a first electrolyte; a second electrolyte; and an ion-selective membrane, selectively permeable to ions of the Group (I) metal.

2. The device according to claim 1 or 2, wherein the material comprises compounds with general formula NaTMO2 and KTMO2 (where TM represents a transition metal), lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, lithium nickel manganese cobalt oxide, lithium, sodium, potassium, nickel, cobalt, manganese, or compounds and mixtures thereof.

3. The device according to claim 1 or 2, wherein the Group (I) metal comprises lithium, sodium, potassium, or mixtures and combinations thereof.

4. The device according to any preceding claim, wherein the cathode comprises a transition metal.

5. The device according to claim 4, wherein the transition metal comprises copper, titanium, molybdenum, or a combination thereof.

6. The device according to claim 4 or 5, wherein the cathode further comprises a polymer coating on a surface of the transition metal.

7. The device according to any preceding claim, wherein the first electrolyte and the second electrolyte are different.

8. The device according to any preceding claim, wherein the first electrolyte comprises an aqueous solution.

9. The device according to any preceding claim, wherein the second electrolyte comprises a non-aqueous solution.

10. The device according to any preceding claim, wherein the ion-selective membrane comprises a compound with a NASICON crystal structure.

11. The device according to any preceding claim, wherein the ion-selective membrane is stable in the first electrolyte and the second electrolyte.

12. A method of extracting a Group (I) metal from a spent battery, the method comprising: contacting an anode with a first electrolyte, the anode comprising material from the spent battery, wherein the material comprises the Group (I) metal; contacting a cathode with a second electrolyte; and applying an electrical potential between the anode and the cathode to obtain the Group (I) metal at the cathode, wherein the first electrolyte and the second electrolyte are separated with an ion- selective membrane, selectively permeable to ions of the Group (I) metal.

13. The method according to claim 12, wherein the electrical potential is 0.1-3.0 V.

14. The method according to claim 12 or 13, wherein the method is carried out under an inert atmosphere.

15. The method according to any of claims 12 to 14, further comprising pre-treating the ion-selective membrane.

16. The method according to claim 15, wherein the pre-treating comprises passivation of a surface of the ion-selective membrane.

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