Lithium extraction from brines and black mass by phase changing materials and membranes

Abstract

Disclosed herein is a composite material membrane, comprising a plurality of MXene particles, and a polysaccharide, wherein the MXene particles have a first and second surface and the polysaccharide is distributed on the first and second surface of the MXene particles. Also disclosed herein are a device for extracting an ion from a solution, a method of manufacturing the composite material membrane, a method of extracting an ion from a solution, and use of the composite material membrane.

Description

[0001] LITHIUM EXTRACTION FROM BRINES AND BLACK MASS BY PHASE CHANGING MATERIALS AND MEMBRANES

[0002] Field of Invention

[0003] The present invention generally relates to composite material membranes, and more particularly relates to composite material membranes and materials for ion extraction.

[0004] Background

[0005] The listing or discussion of a prior-published document in this specification should not necessarily be taken as an acknowledgement that the document is part of the state of the art or is common general knowledge.

[0006] Lithium (Li) has emerged as a critical element in the global transition towards renewable energy and the electrification of transportation. Only the electric vehicles (EV) market, particularly in China, Europe, and the United States, is poised for exponential growth, with analysts projecting an annual demand for mobility storage between 1 .5 to 3.0 terawatt-hours (TWh) by 2030, a fourfold increase from 2020, with a predominant focus on light-duty EVs in the short term. Traditional methods such as hard rock mining pose environmental and economic challenges, making Li extraction from brines and its recovery from black mass a sustainable alternative.

[0007] The largest source of Li is natural brines. However, a mere 30% of direct Li extraction investigations have been conducted utilizing authentic brine. Alternatively, the extraction of Li from black mass, a mixture abundant in lithium-ion battery materials, represents a nascent frontier in technological advancement, encompassing sustainability efforts.

[0008] However, in complex mixtures like natural brines and black mass, the challenge lies in Li+separating from the other ions present in significantly higher concentrations. In natural brines, K+, Na+, Mg2+, and Li+are major components. Similarly, in black mass, Li extraction is difficult due to the predominance of Co2+and Ni2+. Current extraction technologies, including membrane filtration, ion exchange chromatography, solvent extraction, and advanced electrochemical methods, which selectively target specific ions based on properties like size, charge, or chemical affinity, have not achieved sufficient efficiency. Even cutting-edge ion selective materials such as polymers (polyamide, polysulfone, polyether ether ketone), metal- organic frameworks (MOFs), graphene oxide (GO), and zeolitic imidazolate frameworks (ZIFs) face challenges related to the trade-off between selectivity and permeability.

[0009] Therefore, to overcome at least one of the aforementioned problems, there exists a need for new phase changing materials and membranes for lithium extraction from brines and black mass.

[0010] Summary of Invention

[0011] Aspects and embodiments of the invention are provided in the following numbered clauses.

[0012] 1 . A composite material membrane, comprising: a plurality of MXene particles; and a polysaccharide, wherein the MXene particles have a first and second surface and the polysaccharide is distributed on the first and second surface of the MXene particles.

[0013] 2. The composite material membrane according to Clause 1 , wherein a mass ratio of the the polysaccharide to the plurality of MXene particles is from 0:1 to 5:1 , such as from 0.5:1 to 5:1 , such as about 0.5:1 .

[0014] 3. The composite material membrane according to Clause 1 , wherein the polysaccharide is present in an amount of from 15 wt% to 70 wt%, such as about 18.7 wt%, such as about 26.0 wt%, such as about 32.9 wt%, such as about 38.2 wt%, such as about 65.8 wt% of a total weight of the composite material membrane.

[0015] 4. The composite material membrane according to any one of the preceding clauses, wherein the composite material membrane has a Li+extraction efficiency of greater than or equal to 90%, such as greater than or equal to about 95%, such as greater than or equal to about 98%.

[0016] 5. The composite material membrane according to any one of the preceding clauses, wherein the composite material membrane has an absorption of Li+of from about 7 mg / g to about 10 mg / g, such as about 8.3 mg / g in a salt solution. 6. The composite material membrane according to any one of the preceding clauses, wherein the composite material membrane has a thickness of from 5 pm to 45 pm, such as from 13 pm to 40 pm.

[0017] 7. The composite material membrane according to any one of the preceding clauses, wherein the composite material membrane has an electrical resistance of from 100 Q to 50 MQ, such as about 110 Q.

[0018] 8. The composite material membrane according to any one of the preceding clauses, wherein the composite material membrane has an electrical resistance of from about 1.2 kQ to about 0.1 kQ, such as from about 1.1 kQ to about 0.2 kQ over a temperature change from 20 °C to 70 °C.

[0019] 9. The composite material membrane according to any one of the preceding clauses, wherein the composite material membrane demonstrates resistive hysteresis.

[0020] 10. The composite material membrane according to any one of the preceding clauses, wherein the polysaccharide is a non-ionic polysaccharide.

[0021] 11 . The composite material membrane according to any one of the preceding clauses, wherein the polysaccharide is selected from the group consisting of hydroxypropyl cellulose, carboxymethyl cellulose, methyl cellulose, and ethyl cellulose, optionally wherein the polysaccharide is hydroxypropyl cellulose.

[0022] 12. The composite material membrane according to any one of the preceding clauses, wherein the composite material membrane demonstrates a temperature induced hydrophilic- hydrophobic transition.

[0023] 13. The composite material membrane according to any one of the preceding clauses, wherein the composite material membrane is a free-standing membrane.

[0024] 14. The composite material membrane according to any one of the preceding clauses, wherein the composite material membrane is a multi-layered membrane.

[0025] 15. The composite material membrane according to any one of the preceding clauses, wherein the composite material membrane comprises at least a portion of the plurality of polysaccharides disposed between MXene layers. 16. The composite material membrane according to any one of the preceding clauses, wherein the composite material membrane comprises electrical connectors for connecting the membrane to a power source, optionally wherein the electrical connectors comprise electrically conductive wires.

[0026] 17. The composite material membrane according to any one of the preceding clauses, wherein the composite material membrane has a Young’s modulus of from 2 GPa to 8 GPa, such as about 7 GPa.

[0027] 18. The composite material membrane according to any one of the preceding clauses, wherein the plurality of MXene particles comprise Ti3C2Tx, optionally wherein T represents surface terminations selected from one or more of the group consisting of -OH, -O, -F, -Cl, and - S, and x ranges from 0.5 to 2.0.

[0028] 19. A device for extracting an ion from a solution, the device comprising:

[0029] (a) a composite material membrane according to any one of Clauses 1 to 18,

[0030] (b) one or both of i) a power supply in electrical contact with the composite material membrane, and ii) a heater for altering the temperature of the composite material membrane, and

[0031] (c) a supply for providing the solution containing the ion for extraction and contacting the solution with the composite material membrane, optionally wherein the device further includes a controller configured to control one or both of the power supply and the heater.

[0032] 20. The device according to Clause 19, further comprising a plurality of electrical contacts, such as in the form of wires.

[0033] 21 . The device according to Clause 18 or Clause 19, further comprising laminating layers, such as paper lamination layers, on one or more surfaces of the composite material membrane.

[0034] 22. A method of manufacturing a composite material membrane, the method comprising:

[0035] (a) providing a first dispersion comprising MXene particles and a second dispersion comprising a polysaccharide, to form a mixture; and

[0036] (b) vacuuming drying the mixture for a period of time to form a composite material membrane, wherein the composite material membrane comprises: a plurality of MXene particles; and the polysaccharide, wherein the MXene particles have a first and second surface and the polysaccharide is distributed on the first and second surface of the MXene particles.

[0037] 23. The method according to Clause 22, wherein the period of time is from 5 minutes to 24 hours, such as about 5 minutes, such as about 24 hours.

[0038] 24. A method of extracting an ion from a solution, the method including:

[0039] (a) contacting the solution with a membrane or device according to any of Clauses 1 to 21 for a period of time such that at least a proportion of the ion is extracted from the solution; and

[0040] (b) altering the temperature of the membrane to effect a change in the affinity of the membrane for the ion.

[0041] 25. Use of a composite material membrane according to any one of Clauses 1 to 18, device according to any one of Clauses 19 to 21 , or method according to any one of Clauses 22 to 24 in one or more of Li+, K+, Na+, Mg2+, Ni2+, Fe3+, Al3+and Co2+extraction.

[0042] 26. The use of a composite material membrane according to Clause 25 in Li+extraction.

[0043] Drawings

[0044] Fig. 1 depicts characterization of MXene / hydroxypropyl cellulose (HPC) composite membranes, a, Scanning electron microscopy (SEM) images of 0.01 mg mL-1pure MXene / fW dispersion, scale bar: 2 pm. b, SEM images of 0.1 mg mL1MHo sdispersion, scale bar: 5 pm. c-d, Atomic force microscopy (AFM) height image and profile (inset) of monolayer MXene flakes (c) and MH05flakes (d), scale bar: 300 nm. e, Membrane resistance and thickness versus the mass ratio of HPC to MXene. Inset: cross-section SEM images of freestanding MXene and MH0.5 membranes, scale bar: 10 pm. f, X-Ray diffraction (XRD) patterns of MXene and MH05 membranes. Inset: a sketch of HPC incapsulated in MXene nanolayers, g, Stress-strain curves of MXene and MH0.5 membranes. Inset: a flexible and free-standing MHO.5 membrane, scale bar: 1 cm.

[0045] Fig. 2 depicts TGA curves of MXene, HPC, and MXene / HPC composite membranes. Heating rate: 10 °C min-1, in a nitrogen atmosphere. The composites have 18.7, 26, 32.9, 38.2, and 65.8 wt% of HPC. According to the composition the composites are assigned as MH0.5, MH1, MH1 5, MH2, MH5, respectively.

[0046] Fig. 3 depicts XRD patterns of MXene and MXene / HPC membranes. Inset: Interlayer distances calculated from the first and second peaks in XRD spectra as a function of the HPC to MXene mass ratio.

[0047] Fig. 4 depicts a, stress-strain curves of MXene and MXene / HPC membranes, b, Young’s modulus of pure MXene, MXene / HPC membranes as a function of the mass ratio of HPC to MXene.

[0048] Fig. 5 depicts a schematic diagram showing the measurement of membrane resistance underwater.

[0049] Fig. 6 depicts thermo-responsive properties of MXene / HPC composite membrane, a-b, Resistance change of pristine MXene (a) and MH05membrane (b) in heating up and cooling down processes in deionised (Dl)-water. Inset in (a): degradation of a pristine MXene membrane after a heating-cooling cycle, c, Resistance variation of MH0.5 membrane in water after multiple heat-cool cycles, d, Cyclic dynamic quartz crystal microbalance (dQCM) curves of MHO5 membrane during temperature switches between 25 °C and 60 °C. Inset: a photograph of the MH05membrane coated on an Au Q-Sense chip, scale bar: 5 mm.

[0050] Fig. 7 depicts a schematic representation of the fabrication of a MXene / HPC device for electrical control, and a photograph depicting the device prepared using the MH05membrane.

[0051] Fig. 8 depicts electrothermal ionic-responsive properties of MXene / HPC composite membrane, a-b, Thermal images of the MH05 membrane in water with 0 A (a) and 0.1 A (b), scale bar: 1 cm. c-d, Optical polarizing image of the MH05membrane in water with 0 A (c) and 0.1 A (d), scale bar: 500 pm. e, Mass change of MH0.5 membrane during temperature switches between 25 °C and 60 °C measured by dQCM, in single-ion salt solutions, with concentration of 0.1 M.

[0052] Fig. 9 depicts resistance of the MH05 membrane when placed in water over time.

[0053] Fig. 10 depicts ion concentration inside membrane (a), and resistance variation (b) versus ionic hydration radius (RH) during a 6-hour permeation process. Single salt feed solutions of 0.1 M KCI, NaCI, LiCI and MgCI2were used. Fig. 11 depicts a sketch of dual cells for electro-controlled osmosis ion / water permeation measurements. One cell is filled with salt solutions as the feed, and the other cell is filled with 2.5 M sucrose as the permeate. The MH0.5 membrane is inserted and fixed between them.

[0054] Fig. 12 depicts electrothermal lithium extraction from brines and lithium-ion battery black mass a, Concentration of cations in MH05membrane after 6 hours of absorption (denoted as 0 A) and after 0.1 A current applied, in a mixed salt solution with Atacama brine molar ratio, b, Photographs and composition of lithium-ion battery black mass powder and solution, c, Ion extraction efficiency before and after applying current.

[0055] Fig. 13 depicts extraction efficiency of cations in a 4-cation-mixed system, with different Na+concentrations. The concentration of the other ions is 0.025 M.

[0056] Description

[0057] It has been surprisingly found that a composite material membrane formed from MXenes and hydroxypropyl cellulose (HPC) consistently exhibits high Li+extraction capabilities from simulated natural lake brine, with extraction efficiencies exceeding 90%. Furthermore, the membrane extracts 98% of Li+, achieving efficient Li extraction from the black mass from different sources.

[0058] Thus, in a first aspect of the invention, there is provided a composite material membrane, comprising: a plurality of MXene particles; and a polysaccharide, wherein the MXene particles have a first and second surface and the polysaccharide is distributed on the first and second surface of the MXene particles.

[0059] In embodiments herein, the word “comprising” may be interpreted as requiring the features mentioned, but not limiting the presence of other features. Alternatively, the word “comprising” may also relate to the situation where only the components / features listed are intended to be present (e.g. the word “comprising” may be replaced by the phrases “consists of” or “consists essentially of”). It is explicitly contemplated that both the broader and narrower interpretations can be applied to all aspects and embodiments of the present invention. In other words, the word “comprising” and synonyms thereof may be replaced by the phrase “consisting of’ or the phrase “consists essentially of’ or synonyms thereof and vice versa. The phrase, “consists essentially of’ and its pseudonyms may be interpreted herein to refer to a material where minor impurities may be present. For example, the material may be greater than or equal to 90% pure, such as greater than 95% pure, such as greater than 97% pure, such as greater than 99% pure, such as greater than 99.9% pure, such as greater than 99.99% pure, such as greater than 99.999% pure, such as 100% pure.

[0060] As used herein, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a composition” includes mixtures of two or more such compositions, reference to “an oxygen carrier” includes mixtures of two or more such oxygen carriers, reference to “the catalyst” includes mixtures of two or more such catalysts, and the like.

[0061] Without wishing to be bound by theory, it is believed that the hydrophilic nature of HPC networks facilitates ion intercalation into Ti3C2Txnanochannels, and selectivity is achieved through selective ion release, triggered by the temperature-induced switch of HPC from hydrophilic to hydrophobic, driven by differences in ion hydration energy. It is also believed that the MXene layers facilitate electrothermal coupling, while phase transitions in HPC modulate ionic selectivity based on hydration energy.

[0062] MXenes are two-dimensional compounds that consist of atomically thin layers of transition metal carbides, nitrides or carbonitrides. In embodiments of the invention that may be mentioned herein, the plurality of MXenes may be Ti3C2Tx, where T represents Al.

[0063] Any suitable mass ratio of the polysaccharide to the plurality of MXene particles may be used herein. In certain embodiments of the invention that may be mentioned herein, a mass ratio of the polysaccharide to the plurality of MXene particles may be from 0:1 to 5:1 , such as from 0.5:1 to 5:1 , such as about 0.5:1 .

[0064] For the avoidance of doubt, it is explicitly contemplated that where a number of numerical ranges related to the same feature are cited herein, that the end points for each range are intended to be combined in any order to provide further contemplated (and implicitly disclosed) ranges.

[0065] Any suitable amount of polysaccharide may be used. In certain embodiments of the invention that may be mentioned herein, the polysaccharide may be present in an amount of from 15 wt% to 70 wt%, such as about 18.7 wt%, such as about 26.0 wt%, such as about 32.9 wt%, such as about 38.2 wt%, such as about 65.8 wt% of a total weight of the composite material membrane.

[0066] As will be appreciated, the composite material membrane disclosed herein may be used to extract Li+, K+, Na+, Mg2+, Ni2+, Fe3+, Al3+and Co2+. In certain embodiments of the invention that may be mentioned herein, the composite material membrane may have a Li+extraction efficiency of greater than or equal to 90%, such as greater than or equal to about 95%, such as greater than or equal to about 98%.

[0067] In certain embodiments of the invention that may be mentioned herein, the composite material membrane may have an absorption of Li+of from about 7 mg / g to about 10 mg / g, such as about 8.3 mg / g in a salt solution.

[0068] The composite material membrane may have any suitable thickness. In certain embodiments of the invention that may be mentioned herein, the composite material membrane may have a thickness of from 5 pm to 45 pm, such as from 13 pm to 40 pm.

[0069] In certain embodiments of the invention that may be mentioned herein, the composite material membrane may have an electrical resistance of from 100 Q to 50 MQ, such as about 110 Q.

[0070] In certain embodiments of the invention that may be mentioned herein, the composite material membrane may have an electrical resistance of from about 1.2 kQ to about 0.1 kQ, such as from about 1.1 k£) to about 0.2 k£) over a temperature change from 20 °C to 70 °C.

[0071] Details of the electrical resistance measurement technique are provided in the examples section below.

[0072] In certain embodiments of the invention that may be mentioned herein, the composite material membrane may demonstrate resistive hysteresis.

[0073] Any suitable polysaccharide may be used. In certain embodiments of the invention that may be mentioned herein, the polysaccharide may be a non-ionic polysaccharide. For example, the polysaccharide may be hydroxypropyl cellulose.

[0074] In certain embodiments of the invention that may be mentioned herein, the composite material membrane may demonstrate a temperature induced hydrophilic-hydrophobic transition. In certain embodiments of the invention that may be mentioned herein, the composite material membrane may be a free-standing membrane.

[0075] In certain embodiments of the invention that may be mentioned herein, the composite material membrane may be a multi-layered membrane.

[0076] In certain embodiments of the invention that may be mentioned herein, the composite material membrane may comprise at least a portion of the plurality of polysaccharides disposed between MXene layers.

[0077] In certain embodiments of the invention that may be mentioned herein, the composite material membrane may comprise electrical connectors for connecting the membrane to a power source. In such embodiments, the electrical connectors may comprise electrically conductive wires.

[0078] In certain embodiments of the invention that may be mentioned herein, the composite material membrane may have a Young’s modulus of from 2 GPa to 8 GPa, such as about 7 GPa.

[0079] In a second aspect of the invention, there is provided a device for extracting an ion from a solution, the device comprising:

[0080] (a) a composite material membrane according to the first aspect of the invention;

[0081] (b) one or both of i) a power supply in electrical contact with the composite material membrane, and ii) a heater for altering the temperature of the composite material membrane; and

[0082] (c) a supply for providing the solution containing the ion for extraction and contacting the solution with the composite material membrane, optionally wherein the device further includes a controller configured to control one or both of the power supply and the heater.

[0083] In certain embodiments of the invention that may be mentioned herein, the device may further comprise a plurality of electrical contacts, such as in the form of wires.

[0084] In certain embodiments of the invention that may be mentioned herein, the device may further comprise laminating layers, such as paper lamination layers, on one or more surfaces of the composite material membrane. An exemplary embodiment is depicted in Fig. 7. As shown in Fig. 7, the composite material membrane 710, connected with copper wires 720, is sealed between two laminating papers 730 by thermal press sealing, with apertures 740 for water / ion permeation.

[0085] In a third aspect of the invention, there is provided a method of manufacturing a composite material membrane, the method comprising:

[0086] (a) providing a first dispersion comprising MXene particles and a second dispersion comprising a polysaccharide, to form a mixture; and

[0087] (b) vacuuming drying the mixture for a period of time to form a composite material membrane, wherein the composite material membrane comprises: a plurality of MXene particles; and the polysaccharide, wherein the MXene particles have a first and second surface and the polysaccharide is distributed on the first and second surface of the MXene particles.

[0088] In certain embodiments of the invention that may be mentioned herein, the period of time may be from 5 minutes to 24 hours, such as about 5 minutes, such as about 24 hours.

[0089] Specific details of the method of manufacturing a composite material membrane are provided in the examples section below.

[0090] In a fourth aspect of the invention, there is provided a method of extracting an ion from a solution, the method including:

[0091] (a) contacting the solution with a membrane or device according to the first and second aspects of the invention for a period of time such that at least a proportion of the ion is extracted from the solution; and

[0092] (b) altering the temperature of the membrane to effect a change in the affinity of the membrane for the ion.

[0093] Specific details of the method of extracting an ion from a solution are provided in the examples section below.

[0094] In a fifth aspect of the invention, there is provided a use of a composite material membrane according to the first aspect of the invention, device according to the second aspect of the invention, or method according to the third aspect of the invention in one or more of Li+, K+, Na+, Mg2+, Ni2+, Fe3+, Al3+and Co2+extraction. Without wishing to be bound by theory, one or more of Li+, K+, Na+, Mg2+, Ni2+, Fe3+, Al3+and Co2+may be extracted from brines and black mass.

[0095] In certain embodiments of the invention that may be mentioned herein, the use of a composite material membrane may be in Li+extraction.

[0096] Advantages of the present invention may include the following, which may or may not be described elsewhere herein.

[0097] The present invention relates to a novel two-dimensional (2D) composite material membrane with integrated electrothermal regulation capabilities, demonstrated through the self-assembly of MXene (Ti3C2Tx) and hydroxypropyl cellulose (HPC). The MXene / HPC composite membrane disclosed herein demonstrates dual responsiveness to heat and electricity, exhibiting distinct Li+selectivity in its multilayers. The MXene layers facilitate electrothermal coupling, while temperature-induced hydrophilic-hydrophobic phase transitions in HPC act as a water / ionic valve, governing ionic selectivity based on their hydration energy. As demonstrated in the following non-limiting examples, the MXene / HPC composite membrane disclosed herein consistently exhibits high Li+extraction capabilities from simulated Atacama brine, with extraction efficiencies exceeding 90%. Furthermore, the membrane extracts 98% of Li ions, achieving efficient Li extraction from the black mass from different sources.

[0098] Without wishing to be bound by theory, the present invention may be upscaled and adapted to industrial usage accordingly. Further, the composite material membrane is a versatile material as it may be assembled by a variety of suitable phase changing 2D materials and polymers.

[0099] Further aspects and embodiments of the invention will now be discussed by reference to the following non-limiting examples.

[0100] Examples

[0101] Materials

[0102] TisAICs MAX (powder, Laizhou Kai Kai Ceramic Materials Co., Ltd), lithium fluoride (powder, 300 mesh, Sigma-Aldrich), hydroxypropyl cellulose (HPC, Mw ~ 100 000, powder, 20 mesh particle size, Sigma-Aldrich), polyethersulfon membrane filter (PES, 0.03 pm, 47 mm, Sterlitech Corporation, USA), Hydrochloric acid (ACS reagent, 37%, Sigma-Aldrich), Anodise 47™ filter (pore size - 0.02 pm, diameter 47 mm, Whatman, USA). All materials were received and used without further purification.

[0103] Characterization methods

[0104] Scanning electron microscopy (SEM) images were obtained by a ZEISS Sigma 300 FE SEM system. AFM measurements were conducted by AFM Bruker EQB001 . TGA was performed by TA Instrument Discovery TGA1 - 0247 under nitrogen at a heating rate of 10 °C min"1. X- Ray diffraction (XRD) was carried out on Bruker D8 ADVANCE with a Cu Ka tube radiation source (1 .5418 A) in a step of 0.021 per second from 21 to 201 . The membrane thickness was measured by an Alpha-Step IQ Surface Profiler (KLA Tencor). The mechanical properties were measured using a Dynamic Mechanical Analyser (DMA 850, TA Instruments). The concentration of cations permeate through the membranes and the concentration of cations adsorbed by the membrane was measured by a Perkin Elmer Avio 500 Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES). Quartz-Crystal Microbalance (QCM) measurements were performed by the QSense Explorer System (QE 401 Electronic Unit, QCP 101 Chamber Platform, QFM 401 Flow Module). A 5 MHz Au electrode was used with the pump speed of 50 uL min"1. The apparent temperatures of samples were measured by a RS Component, FLIR E5 Thermal Imaging Camera.

[0105] Example 1. Ti3C2TxMXene nanosheet synthesis

[0106] 3.0 g of LiF was added to 9.0 M HCI solution. After the dissolution of LiF, 1 .0 g of TisAIC2 MAX powder was added into the HF-containing solution, and then the mixture was kept at 35 °C for 24 hours. Afterwards, the solid residue was washed with 2 M HCI for three times (centrifuged at 7,000 r.p.m. with 10 minutes). Then, the solid residue was further washed with deionized water several times until the pH value increased to ca. 7.0 (centrifuged at 10,000 r.p.m. for 10 minutes). Subsequently, the washed residue was added into deionized water, ultrasonicated for 20 minutes under N2atmosphere, and centrifuged at 3,000 r.p.m. for 20 minutes. The supernatant was collected as the Ti3C2Tx MXene dispersion.

[0107] Example 2. Preparation of MXene / HPC composite membranes

[0108] The MXene dispersion synthesized in Example 1 was first diluted to 1 mg mL1by de-ionized water. Then, HPC (1 mg mL1) dispersion was mixed with MXene dispersion at different mass ratios, and the colloids were then mixed for 10 minutes by a shaker (rotation speed - 500 rpm, Vortex Mixer, USA). MXene / HPC composite membranes were prepared by vacuum filtration of the aforesaid mixture through two types of membrane filters: Anodise™ 47 and polyethersulfone membrane. Vacuum filtration was maintained for 24 hours, and the obtained membrane was then dried overnight in a dry cabinet at room temperature.

[0109] Example 3. Characterisation of MXene / HPC composite membranes

[0110] 2D composite membranes were prepared using a self-assembly method involving MXene flakes and HPC macromolecules, as detailed in Example 2. Aqueous Ti3C2Txdispersion was synthesized through selective etching (Alhabeb, M. etal., Chem. Mater. 2017, 29, 7633-7644), producing MXene flakes with a mean size of 0.9 pm (Fig. 1a). An aqueous HPC solution was then combined with the MXene dispersion in various mass ratios. Such process leads to the self-assembly of the MXene nanoflakes with HPC molecules, forming composite building blocks. Atomic force microscopy (AFM) images show HPC molecules distributed on the flake surfaces (Figs. 1c-d). Aligning the flakes via vacuum filtration results in the formation of multilayered membranes (Figs. 1 b, e-insert).

[0111] We maintained the MXene concentration at 10 mg and varied the HPC concentration to achieve free-standing MXene / HPC membranes with thicknesses ranging from 13 pm to 40 pm, depending on the HPC content (Fig. 1 e). Thermogravimetric analysis (TGA) determined the HPC concentration in the membranes (Fig. 2). As shown in Fig. 1 e, adding HPC to MXene membrane significantly increases its resistance, from approximately 3 Q for an 8 pm pristine MXene membrane to 110 Q for MH05 and 50 MQ for MH5. Thus, the optimal composition was MH05, with the lowest HPC concentration allowed by self-assembly. X-ray diffraction (XRD) patterns (Figs. 1f and 3) show that the membranes have two peaks corresponding to interlayer distances of 1 .22 nm and 2.36 nm, indicating HPC encapsulation between MXene layers, compared to a broad distribution of 1 .35 to 1 .55 nm in pure MXene membranes. Furthermore, the pristine MXene membrane is fragile and brittle, while the composite membranes exhibit a Young's modulus of up to 7 GPa (Figs. 1 g and 4).

[0112] Example 4. Thermal responsiveness of MXene / HPC composite membranes

[0113] We verified the thermal responsiveness by assessing the resistance of the composite film at various temperatures using a multimeter in water (see schematic in Fig. 5).

[0114] Preparation of MXene / HPC thin film for QCM

[0115] MXene (10 mL, 0.01 mg mb1) dispersion was mixed with HPC dispersion (0.5 mL, 0.1 mg mL- 1), and the colloids were then mixed for 10 minutes by a shaker (rotation speed - 500 rpm, Vortex Mixer, USA). MXene / HPC thin film were prepared by vacuum filtration of the aforesaid mixture through Anodise™ 47 membrane filter. Vacuum filtration was maintained for 5 minutes, and the obtained film was then dried overnight in a dry cabinet at room temperature for 30 minutes. For comparison, a pristine MXene membrane can be easily prepared by vacuum filtrating 10 mL MXene dispersion (0.01 mg mL'1) through the filter.

[0116] Results and discussion

[0117] We heated pristine MXene and MXene / HPC membranes from room temperature (RT, ~25 °C) to 70 °C, then cooled back to RT, recording resistance every 5 °C (Figs. 6a-c). The resistance of the MHO 5 composite membrane increased approximately 2.5-fold within seconds of immersion in water and showed high stability, with reversible changes in resistance during heating and cooling cycles (Fig. 6b). This stability persisted over 10 consecutive heatingcooling cycles (Fig. 6c). In contrast, pristine MXene's resistance irreversibly increased threefold upon heating due to water molecule entry disrupting its interlayer conductive structure, and it degraded in water at elevated temperatures (Fig. 6a).

[0118] Notably, during the heating and cooling process, two significant steps of resistance change were observed near the low critical solution temperature (LCST) of HPC. Upon heating above 55 °C, resistance sharply declined due to the LCST transition from hydrophilic to hydrophobic, expelling water molecules and decreasing resistance. Conversely, during cooling, the transition at 40 °C reverted HPC to a hydrophilic state, increasing water uptake and, therefore, resistance. This dynamic temperature-responsive behavior in the composite membrane's resistance, due to water absorption, can be measured by the vibration frequency change of a dynamic quartz crystal microbalance (dQCM) chip, as shown in Fig. 6d. The mass change caused by water absorption is directly proportional to the reduction in vibration frequency. Between 25 °C and 60 °C, the MH05composite membrane underwent reversible temperature- induced water uptake and release over several cycles.

[0119] Example 5. Electrothermal ionic-responsive properties of MXene / HPC composite membrane

[0120] For practical applications, electrothermal coupling of stimuli can be achieved via Joule heating. The MHO.5 membrane, connected with copper wires, was sealed between two laminating papers by thermal press sealing, with apertures for water / ion permeation (Fig. 7). As shown in Fig. 7, the MXene / HPC device 700 includes a MH05 membrane 710 connected with copper wires 720, laminating papers 730 with apertures 740, and PES filters 750. The membrane was submerged in water and used an infrared thermal camera to monitor its temperature upon current application, while a sourcemeter recorded resistance changes. Results and discussion

[0121] Applying a 0.1 A current rapidly increased the temperature to 60 °C within 2 seconds (Figs. 8a-b). This caused an initial sharp decline in resistance, which then stabilized (Fig. 9). Polarized optical microscope images showed changes in the membrane's optical properties due to the alignment of HPC molecules at LCST (Figs. 8c-d).

[0122] Example 6. Electrothermal properties of the MXene / HPC composite membranes for cation absorption and release

[0123] To test the electrothermal properties of the membranes for cation absorption and release, we measured ion permeation and adsorption and assessed the impact of different ions on membrane resistance (Fig. 10). The MXene / HPC membrane was placed between dual cells, one containing a 0.1 M salt solution and the other a 2.5 M sucrose solution, to create osmotic pressure facilitating ion flow. Ion concentrations were quantified using inductively coupled plasma-optical emission spectrometer (ICP-OES). After 6 hours, Li+concentration inside the membrane was higher than other ions, despite lower permeability. Furthermore, Li+uptake increased membrane resistance by 20 times, while Na+, K+, and Mg2+increased it less than fivefold. Dynamic ion / water uptake and release were measured using the dQCM technique in 0.1 M single-ion solutions (as described in Example 4 for water), cycling temperatures between 25 °C and 60 °C (Fig. 8e). The composite membrane showed higher uptake of Li+ / water, likely due to Li+high hydration energy and large hydration shell (Mahler, J. & Persson, I., Inorg. Chem. 2012, 51, 425-438), which increased water content and membrane resistance. Other ions traversed the membrane more easily with less impact on resistance. Such electrothermally controlled ionic / water valve function of the membranes allows for ion uptake in power-off states and selective release in power-on states. This function can be adjusted for Li extraction from sustainable resources.

[0124] Example 7. Electrothermal lithium extraction from brines and lithium-ion battery black mass

[0125] A novel approach to extract Li+from simulated Atacama brine and black mass from Li-ion batteries provided by VGM Sustainability Solutions, SG3R, Pte, Ltd, is disclosed herein. Cheat — ionic concentration inside membrane after 0.1 A current applied

[0126] The same for Selectivity (Li+ / Na+) and Selectivity (Li+ / K+).

[0127] Extraction efficiency: E =CheMx 100%;

[0128] Cabsorb — ionic concentration inside membrane after 6 hours of absorption

[0129] Results and discussion

[0130] For Li+extraction from brines, we set up an experiment similar to the ion permeation setup depicted in Fig. 11 . The MXene / HPC membrane was fixed between dual cells, with simulated brine solution on one side and 2.5 M sucrose on the other. We evaluated the membrane's Li+extraction efficiency by monitoring ion concentrations before and after Joule heating. After immersing the MH0.5 membrane in simulated Atacama brine for 6 hours, we observed different absorption affinities for the mixture of 0.15M Na+, 0.04M K+, 0.025M Li+, and 0.04M Mg2+(Fig. 12a). Na+had the highest absorption due to its high concentration, but significant Li+absorption (8.3 mg / g) was also noted despite its lower concentration. Joule heating with a 0.1 A current released water molecules and cations, but a substantial proportion of Li+remained within the membrane. To benchmark, we determined the selectivity of Li+over Na+, K+, and Mg2+cations and compared various materials for Li+extraction from simulated brine (Table 1 ). The MXene / HPC membrane exhibits high Li+selectivity, especially towards Mg2+(selectivity around 80), as well as Na+and K+. This one-step Li+separation from Mg2+, K+, and Na+is a significant advancement in Li extraction technology. The membrane disclosed herein consistently demonstrated outstanding Li+extraction capabilities, with efficiencies exceeding 90% (Fig. 13), making it versatile for various Li-rich salt lakes worldwide.

[0131] Table 1. Comparison of Li+extraction behaviours for membranes.

[0132] In addition to extracting Li+ from salt lakes, we also targeted Li+ extraction from Li-ion battery black mass provided by VGM Sustainability Solutions, SG3R, Pte, Ltd. The black mass, initially a black powder, was dissolved using a mixture of concentrated hydrochloric acid and nitric acid in a 3:1 ratio, stirred at 40 °C for 72 hours (Fig. 12b, left photograph). ICP analysis of the dissolved solution showed cobalt concentrations over three times higher than lithium ions. We then used the ion permeation setup with the MXene / HPC membrane between dual cells containing the black mass solution and 2.5 M sucrose. Initially, extraction efficiency for each ion was below 15% (Fig. 12c). However, applying a 0.1 A current induced rapid heating, releasing all absorbed ions except Li+. The absorption-release ratio indicated that 98% of Li ions were retained by the membrane, demonstrating efficient Li ion extraction.

[0133] General discussion

[0134] In the present disclosure, a novel membrane technology for Li extraction that is based on the MXene / cellulose phase-changing composite with electro-thermo-chemical response is disclosed. The design strategy disclosed herein combines electroactive MXenes and thermosensitive HPC. MXenes (Ti3C2Tx) lamellar membranes form 2D nanochannels with electrical and ionic conductivity, but pristine MXene membranes have poor mechanical strength and degrade in aqueous environment. HPC, a non-ionic polysaccharide, exhibits a temperature-induced transition from hydrophilic to hydrophobic state at 45 °C, forming stable phase-changing membranes even in salt water. Unlike traditional filtration or separation methods that struggle to distinguish between ions of similar sizes or charges, our technology leverages the hydrophilic nature of HPC networks to facilitate ion intercalation into Ti3C2Txnanochannels. Selectivity is achieved through selective ion release, triggered by the temperature-induced switch of HPC from hydrophilic to hydrophobic, driven by differences in ion hydration energy.

[0135] In conclusion, global demand for Li, driven by the rise of renewable energy and electric vehicles, necessitates innovative extraction techniques. Traditional methods face challenges both environmentally and economically, underscoring the urgency for sustainable alternatives. In response to this need, a two-dimensional composite membrane has been developed herein. This membrane, composed of MXene and HPC, integrates electrothermal regulation capabilities, representing a significant advancement in Li extraction technology. The MXene / HPC composite membrane exhibits dual responsiveness to heat and electricity, enabling precise control over its Li ion selectivity. Without wishing to be bound by theory, the MXene layers facilitate electrothermal coupling, while phase transitions in HPC modulate ionic selectivity based on hydration energy. The composite material membrane disclosed herein consistently demonstrates outstanding Li ion extraction capabilities from simulated Atacama brine, consistently achieving extraction efficiencies exceeding 90%. Moreover, it excels in extracting lithium ions from black mass provided by VGM Sustainability Solutions, SG3R, Pte, Ltd., with an impressive extraction rate of 98%. The development of this composite material membrane holds significant implications for the sustainable extraction of Li.

Claims

Claims1 . A composite material membrane, comprising: a plurality of MXene particles; and a polysaccharide, wherein the MXene particles have a first and second surface and the polysaccharide is distributed on the first and second surface of the MXene particles.

2. The composite material membrane according to Claim 1 , wherein a mass ratio of the the polysaccharide to the plurality of MXene particles is from 0:1 to 5:1 , such as from 0.5:1 to 5:1 , such as about 0.5:1 .

3. The composite material membrane according to Claim 1 , wherein the polysaccharide is present in an amount of from 15 wt% to 70 wt%, such as about 18.7 wt%, such as about 26.0 wt%, such as about 32.9 wt%, such as about 38.2 wt%, such as about 65.8 wt% of a total weight of the composite material membrane.

4. The composite material membrane according to any one of the preceding claims, wherein the composite material membrane has a Li+extraction efficiency of greater than or equal to 90%, such as greater than or equal to about 95%, such as greater than or equal to about 98%.

5. The composite material membrane according to any one of the preceding claims, wherein the composite material membrane has an absorption of Li+of from about 7 mg / g to about 10 mg / g, such as about 8.3 mg / g in a salt solution.

6. The composite material membrane according to any one of the preceding claims, wherein the composite material membrane has a thickness of from 5 pm to 45 pm, such as from 13 pm to 40 pm.

7. The composite material membrane according to any one of the preceding claims, wherein the composite material membrane has an electrical resistance of from 100 Q to 50 MQ, such as about 110 Q.

8. The composite material membrane according to any one of the preceding claims, wherein the composite material membrane has an electrical resistance of from about 1.2 k£)to about 0.1 kQ, such as from about 1.1 kO to about 0.2 kQ over a temperature change from20 °C to 70 °C.

9. The composite material membrane according to any one of the preceding claims, wherein the composite material membrane demonstrates resistive hysteresis.

10. The composite material membrane according to any one of the preceding claims, wherein the polysaccharide is a non-ionic polysaccharide.

11. The composite material membrane according to any one of the preceding claims, wherein the polysaccharide is selected from the group consisting of hydroxypropyl cellulose, carboxymethyl cellulose, methyl cellulose, and ethyl cellulose, optionally wherein the polysaccharide is hydroxypropyl cellulose.

12. The composite material membrane according to any one of the preceding claims, wherein the composite material membrane demonstrates a temperature induced hydrophilic- hydrophobic transition.

13. The composite material membrane according to any one of the preceding claims, wherein the composite material membrane is a free-standing membrane.

14. The composite material membrane according to any one of the preceding claims, wherein the composite material membrane is a multi-layered membrane.

15. The composite material membrane according to any one of the preceding claims, wherein the composite material membrane comprises at least a portion of the plurality of polysaccharides disposed between MXene layers.

16. The composite material membrane according to any one of the preceding claims, wherein the composite material membrane comprises electrical connectors for connecting the membrane to a power source, optionally wherein the electrical connectors comprise electrically conductive wires.

17. The composite material membrane according to any one of the preceding claims, wherein the composite material membrane has a Young’s modulus of from 2 GPa to 8 GPa, such as about 7 GPa.

18. The composite material membrane according to any one of the preceding claims, wherein the plurality of MXene particles comprise Ti3C2Tx, wherein T represents surface terminations selected from one or more of the group consisting of -OH, -O, -F, -Cl, and -S, and x ranges from 0.5 to 2.0.

19. A device for extracting an ion from a solution, the device comprising:(a) a composite material membrane according to any one of Claims 1 to 18,(b) one or both of i) a power supply in electrical contact with the composite material membrane, and ii) a heater for altering the temperature of the composite material membrane, and(c) a supply for providing the solution containing the ion for extraction and contacting the solution with the composite material membrane, optionally wherein the device further includes a controller configured to control one or both of the power supply and the heater.

20. The device according to Claim 19, further comprising a plurality of electrical contacts, such as in the form of wires.

21. The device according to Claim 18 or Claim 19, further comprising laminating layers, such as paper lamination layers, on one or more surfaces of the composite material membrane.

22. A method of manufacturing a composite material membrane, the method comprising:(a) providing a first dispersion comprising MXene particles and a second dispersion comprising a polysaccharide, to form a mixture; and(b) vacuuming drying the mixture for a period of time to form a composite material membrane, wherein the composite material membrane comprises: a plurality of MXene particles; and the polysaccharide, wherein the MXene particles have a first and second surface and the polysaccharide is distributed on the first and second surface of the MXene particles.

23. The method according to Claim 22, wherein the period of time is from 5 minutes to 24 hours, such as about 5 minutes, such as about 24 hours.

24. A method of extracting an ion from a solution, the method including:(a) contacting the solution with a membrane or device according to any of Claims 1 to 21 for a period of time such that at least a proportion of the ion is extracted from the solution; and(b) altering the temperature of the membrane to effect a change in the affinity of the membrane for the ion.

25. Use of a composite material membrane according to any one of Claims 1 to 18, device according to any one of Claims 19 to 21 , or method according to any one of Claims 22 to 24 in one or more of Li+, K+, Na+, Mg2+, Ni2+, Fe3+, Al3+and Co2+extraction.

26. The use of a composite material membrane according to Claim 25 in Li+extraction.

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