A solar evaporator based on a metal-oxo acid cluster shield layer and a lithium enrichment method thereof

Abstract

The application discloses a solar evaporator based on a metal oxyacid salt cluster shielding layer and a lithium enrichment method thereof. The solar evaporator comprises: a photo-thermal evaporation layer for absorbing solar radiation or simulated solar radiation and generating a local photo-thermal field and water evaporation flux at a liquid-gas interface; a capillary liquid supply heat insulation support layer for transporting lithium-containing high-salinity water in a lithium-containing high-salinity water supply area to the photo-thermal evaporation layer; a lithium-containing high-salinity water supply area for storing or continuously inputting lithium-containing high-salinity water; a metal oxyacid salt cluster shielding layer arranged on a liquid phase mass transfer path of the lithium-containing high-salinity water from the lithium-containing high-salinity water supply area to the photo-thermal evaporation layer or from the photo-thermal evaporation layer to a lithium enrichment / lithium precipitation collection area, for intercepting multivalent interfering metal cations in the lithium-containing high-salinity water and allowing Li + to migrate with the liquid phase; and a lithium enrichment / lithium precipitation collection area for collecting lithium-containing concentrated liquid or converting the lithium-containing concentrated liquid into lithium salt. The application can shield multivalent interfering metal cations to achieve efficient lithium enrichment.

Description

Technical Field

[0001] This invention belongs to the field of resource utilization technology for saline waste liquid, specifically a solar evaporator based on a metal oxometalate cluster shielding layer and its lithium enrichment method. Background Technology

[0002] Lithium resources are a crucial foundation for power batteries, energy storage batteries, and new energy materials systems. Salt lake brines, geothermal brines, concentrated seawater, and some industrial lithium-containing wastewater contain considerable lithium resources. However, these systems are typically accompanied by magnesium oxides. 2 + Ca 2+ 、Sr 2+ Ba 2+ Fe 2+ Mn 2+ Al 3+ and Fe 3+ High concentrations of polyvalent interfering metal cations, including those with high charge density and strong hydration and oxygen coordination capabilities, can easily lead to problems such as adsorption site competition, membrane fouling, inorganic scaling, extraction system contamination, consumption of lithium precipitation reagents, and decreased lithium salt purity during lithium extraction.

[0003] Existing methods for controlling multivalent metal interference in high-salt lithium-containing saline solutions include lime-soda ash precipitation, carbonate or hydroxide precipitation, ion exchange resins, membrane separation, solvent extraction, and inorganic adsorption. However, precipitation methods require large amounts of reagents and generate saline solid waste, and may also result in lithium loss due to co-precipitation or entrainment. Membrane separation technology is susceptible to concentration polarization and scaling in high-salt, high-hardness systems. Organic ion exchange materials tend to exhibit decreased selectivity and durability in strong salt environments. Some inorganic adsorption materials suffer from unclear structures and limitations in their ability to control Li-containing compounds. + The problem of co-adsorption being obvious or difficult to match with subsequent lithium extraction units.

[0004] Solar-powered interfacial evaporation utilizes solar energy as a heat source to form a localized high-temperature interface on the surface of porous photothermal materials, achieving water evaporation and brine concentration in a low-energy-consumption manner. For lithium-containing high-salt brine, solar evaporation can reduce external heat energy consumption and promote the relative enrichment of lithium. However, in high-magnesium, high-calcium, and high-salt environments, the photothermal layer and liquid supply channels of traditional solar evaporators are easily blocked by Mg(OH)2, CaCO3, CaSO4, or other scale, leading to a decrease in evaporation rate, failure of mass transfer channels, and loss of lithium during scaling or multi-salt co-precipitation. Therefore, existing conventional photothermal evaporation structures are difficult to stably achieve lithium enrichment in complex brine.

[0005] Metal oxoate clusters possess a well-defined metal-oxygen framework, terminal oxygen, bridging oxygen, hydroxyl oxygen sites, and a tunable counterion environment. Their multi-point oxygen coordination, charge compensation, and counterion exchange effects on divalent or trivalent metal cations are known coordination chemistry principles. However, current technologies typically use them as basic coordination materials, catalytic materials, or inorganic functional materials. In order to simultaneously address the problems of multivalent ion interference in high-salinity brine, scaling failure of solar evaporators, and insufficient lithium enrichment efficiency, we are exploring the use of metal oxoate clusters in the construction of solar evaporators. This approach is expected to preferentially shield multivalent interfering metal cations and achieve lithium enrichment, lithium precipitation, or lithium salt collection. Summary of the Invention

[0006] The purpose of this invention is to provide a solar evaporator based on a metal oxoate cluster shielding layer and a lithium enrichment method thereof, which can preferentially shield multivalent interfering metal cations to achieve efficient lithium enrichment.

[0007] This invention is achieved through the following technical solution: A solar evaporator based on a metal oxoate cluster shielding layer includes a photothermal evaporation layer, a capillary liquid supply and thermal insulation support layer, a lithium-containing high-salt water supply zone, a metal oxoate cluster shielding layer, and a lithium enrichment / lithium deposition collection zone. The photothermal evaporation layer absorbs or simulates solar irradiance and generates a localized photothermal field and water evaporation flux at the liquid-gas interface. The capillary liquid supply and thermal insulation support layer transports lithium-containing high-salt water from the lithium-containing high-salt water supply zone to the photothermal evaporation layer. The lithium-containing high-salt water supply zone stores or continuously supplies lithium-containing high-salt water. The metal oxoate cluster shielding layer is positioned along the liquid-phase mass transfer path from the lithium-containing high-salt water supply zone into the photothermal evaporation layer or from the photothermal evaporation layer into the lithium enrichment / lithium deposition collection zone, and is used to intercept multivalent interfering metal cations in the lithium-containing high-salt water while allowing Li... + With continuous liquid phase migration; the lithium enrichment / precipitation collection zone is used to collect lithium-containing concentrate produced by shielding and interfacial evaporation concentration, or to convert lithium in the lithium-containing concentrate into lithium salt crystals, lithium salt precipitates or lithium-containing complex salts through continued evaporation, cooling crystallization and addition of lithium precipitation agent.

[0008] Further, the photothermal evaporation layer is a carbon-based photothermal material, a conductive polymer photothermal material, a metal nanomaterial, a semiconductor photothermal material, MXene, a ferrous metal oxide, a plasmonic material, or a biomass carbonization material loaded on the liquid-outflow side of the metal oxophosphate cluster shielding layer, wherein: the carbon-based photothermal material is at least one of carbon black, graphene, graphene oxide reduction products, carbon nanotubes, graphite powder, and porous carbon; the conductive polymer photothermal material is at least one of polypyrrole, polyaniline, polydopamine, polythiophene, and polyethylenedioxythiophene; the metal nanomaterial is at least one of gold nanoparticles, silver nanoparticles, copper nanoparticles, nickel nanoparticles, aluminum nanoparticles, and alloy nanoparticles; the semiconductor photothermal material is at least one of copper sulfide, molybdenum sulfide, tungsten sulfide, molybdenum disulfide, tungsten diselenide, titanium oxide, zinc oxide, copper oxide, and cuprous oxide; and the MXene is Ti3C2T x Ti2CT x Nb2CT x V2CT x and Mo2TiC2T x At least one of them, wherein T x The surface end groups include -O, -OH, and -F; the ferrous metal oxide is at least one of iron(II,III) oxide, ferrous oxide, copper oxide, cuprous oxide, manganese oxide, cobalt oxide, nickel oxide, and titanium oxide; the plasmon material is at least one of gold nanorods, gold nanoshells, silver nanowires, silver nanocubes, copper sulfide nanoparticles, and aluminum nanostructures; the biomass carbonization material is at least one of carbonized wood, carbonized cotton cloth, carbonized cellulose paper, carbonized bamboo, carbonized sponge, carbonized straw, and carbonized coconut shell.

[0009] Furthermore, the capillary liquid supply thermal insulation support layer is at least one of the following: cellulose paper, cotton cloth, wood, sponge, aerogel, foam plastic, porous ceramic, polyurethane foam, polyvinylidene fluoride membrane, polyacrylonitrile membrane, nylon membrane, glass fiber membrane, and nonwoven fabric, which have continuous hydrophilic capillary channels and thermal insulation pore structures.

[0010] Furthermore, the metal oxoate cluster shielding layer is a material layer containing metal oxoate clusters, and the metal oxoate clusters are fixed to the inner wall of the pores of the capillary liquid supply heat insulation support layer, the interlayer interface between the capillary liquid supply heat insulation support layer and the photothermal evaporation layer, the liquid inlet side surface of the photothermal evaporation layer, and the liquid inlet interface of the lithium enrichment / lithium deposition collection area. The metal oxophosphate cluster comprises a metal-oxygen cluster framework, oxygen-rich coordination sites, and an exchangeable counterion microenvironment, wherein: the oxygen-rich coordination sites are distributed on the metal-oxygen cluster framework, including terminal oxygen sites, bridging oxygen sites, hydroxyl oxygen sites, and deprotonated oxygen sites; the exchangeable counterion microenvironment includes Li + Na +K + NH4 + At least one of the quaternary ammonium salt cations.

[0011] Furthermore, the metal oxoate clusters are niobium-containing oxygen clusters, tantalum-containing oxygen clusters, tungsten-containing oxygen clusters, molybdenum-containing oxygen clusters, vanadium-containing oxygen clusters, titanium-containing oxygen clusters, zirconium-containing oxygen clusters, or complex metal oxoate clusters.

[0012] Furthermore, the polyniobium-oxygen cluster is prepared by the following method: Step 1, according to niobium element and OH - With a molar ratio of 1:(20~90), take niobium source and alkali source, and then take deionized water according to the ratio of niobium source to deionized water of 0.1 g:(5~30 mL). Then mix the source, alkali source and deionized water to form a reaction solution containing niobium oxygen coordination units. The niobium source is at least one of niobium pentoxide, niobic acid, and alkali metal niobate, wherein: the niobic acid is metaniobic acid or orthoniobic acid; the alkali metal niobate is at least one of sodium metaniobate, potassium metaniobate, sodium orthoniobate, potassium orthoniobate, sodium hexaniobate, and potassium hexaniobate; The alkaline source is potassium hydroxide, sodium hydroxide, or lithium hydroxide; Step 2: Transfer the reaction solution to the reaction vessel and seal it. At a temperature of 160~220℃, perform a hydrothermal reaction for 48~120h to allow the niobium-containing oxygen coordination units to condense, rearrange, and multinucleate. After the reaction is completed, allow it to cool naturally to room temperature, stand, and collect the liquid-phase precursor containing niobium oxyacid acid salt clusters. Step 3: Add alcohol antisolvent to the liquid precursor containing niobium oxoate clusters according to the volume ratio of alcohol antisolvent to niobium oxoate clusters (1~5):1 to induce the precipitation of niobium oxoate clusters. After washing with alcohol / water mixture, dry to obtain multi-niobium oxoate clusters. The alcohol antisolvent is at least one of methanol, anhydrous ethanol and isopropanol; The alcohol / water mixture is prepared by mixing alcohol and deionized water at a volume ratio of (0.5~2):1, wherein the alcohol is anhydrous methanol, anhydrous ethanol, or isopropanol.

[0013] Furthermore, the lithium-containing high-salt water supply area is used to contain or continuously supply lithium-containing high-salt water, which contains Li. + Salt lake brine, geothermal brine, underground brine, oil and gas field brine, concentrated seawater, lithium-containing mineral leachate, lithium battery recovery salt waste liquid, or lithium-containing industrial high-salt wastewater containing monovalent coexisting cations and polyvalent interfering metal cations. The monovalent coexisting cation includes Na. + K + and NH 4+ ; The multivalent interfering metal cations include Mg 2+ Ca 2+ 、Sr 2+ Ba 2+ Fe 2+ Mn 2+ Co 2+ Ni 2+ Zn 2+ Al 3+ Fe 3+ Cr 3+ La 3+ Ce 3+ Pr 3+ and Nd 3+ .

[0014] A method for lithium enrichment in a solar evaporator based on a metal oxoate cluster shielding layer includes the following steps: S1. Inject lithium-containing high-salt water into the lithium-containing high-salt water supply area and make the lithium-containing high-salt water contact the supply side of the capillary supply heat insulation support layer, so that the evaporation side of the photothermal evaporation layer is exposed to the environment and receives solar radiation or simulated solar radiation. S2. Under solar irradiation or simulated solar irradiation, the photothermal evaporation layer converts light energy into interfacial heat energy, forming a localized hot zone on the evaporation side and driving water to migrate and evaporate from the liquid supply side of the photothermal evaporation layer to the evaporation side along continuous hydrophilic capillary channels. This establishes an evaporation-induced continuous replenishment flux, a localized ion concentration zone generated by water removal, and temperature and concentration gradients distributed along the mass transfer path inside the evaporator. S3. Under the combined effects of continuous replenishment flux, local ion concentration zone, and temperature and concentration gradients, valence-interfering metal cations in lithium-containing high-salt water are preferentially retained at the oxygen-rich ion-regulated interface through multi-point oxygen coordination, charge compensation, counter-ion exchange, and ion association. + It remains in the liquid phase and migrates with the concentrate from the metal oxoate cluster shielding layer to the photothermal evaporation layer and the lithium enrichment / lithium deposition collection area; S4, containing Li + The liquid phase continues to evaporate and concentrate in the photothermal evaporation layer, and Li + Under the influence of lateral liquid flow, evaporation concentration gradient and circulating liquid supply, it migrates to the lithium enrichment / lithium precipitation collection area; S5. Directly collect the lithium-containing concentrate temporarily stored in the lithium enrichment / lithium precipitation collection area, or convert the lithium in the lithium-containing concentrate into lithium salt crystals, lithium salt precipitates or lithium-containing complex salts by continuing evaporation, cooling crystallization and adding lithium precipitation agent. Then collect the lithium salt crystals, lithium salt precipitates and lithium-containing complex salts. At the same time, collect the fresh water obtained by condensing the water vapor on the evaporation side of the photothermal evaporation layer.

[0015] Furthermore, the evaporation methods of S1 to S5 are intermittent liquid supply evaporation, continuous liquid supply evaporation, circulating concentration evaporation, multi-stage series evaporation, or natural sunlight evaporation.

[0016] Furthermore, step S5 also includes: when the metal oxoate cluster shielding layer reaches the preset multivalent interfering metal cation loading, or when the evaporator flux drops to the preset value, the metal oxoate cluster shielding layer is brought into contact with the regeneration liquid to desorb the retained multivalent interfering metal cations. The regenerated solution is at least one of alkaline eluent, salt solution, complexing agent solution, and deionized water.

[0017] The present invention has the following beneficial technical effects: 1) This invention uses metal oxoate cluster materials as a shielding interface for multivalent interfering metal ions in a solar evaporator, thereby integrating an oxygen-rich coordination interface, a negatively charged cluster framework, and an exchangeable counterion environment into the interfacial solar evaporation mass transfer pathway. Utilizing the high charge density, strong hydration and oxygen coordination tendency of multivalent interfering metal ions, as well as a more significant charge matching relationship with the negatively charged cluster framework, they preferentially bind to terminal oxygen, bridging oxygen, hydroxyl oxygen, or deprotonated oxygen sites in the metal oxoate clusters. Based on the differences in the monovalent charge, hydration characteristics, effective radius, and coordination behavior of Li+, Li... + Compared to multivalent interfering metal ions, it exhibits a higher tendency for liquid-phase retention and migration; therefore, a solar evaporator constructed based on it can be used for low-energy evaporation concentration and lithium enrichment processes in lithium-containing high-salt water, including Li... + Na + K + Under conditions where monovalent ions, including Mg, coexist in large quantities, it can preferentially retain Mg. 2+ Ca 2+ and Fe 3+ The shielding layer of this invention effectively distinguishes between multivalent interfering metal cations and lithium ions by including multivalent interfering metal cations. In other words, the selectivity of the shielding layer for multivalent interfering metal cations comes from the synergistic effect of multidentate coordination, charge matching and counterion compensation between multivalent interfering metal cations and oxygen-rich sites of metal oxoacid clusters, rather than simple non-selective salt adsorption or ordinary precipitation to remove impurities. This realizes the device-based and process-coupled lithium extraction for complex high-salt brine, and achieves efficient lithium enrichment.

[0018] 2) This invention fixes metal oxophosphate clusters to the inner wall of the pores of the capillary liquid supply insulation support layer, the interlayer interface between the capillary liquid supply insulation support layer and the photothermal evaporation layer, the liquid inlet side surface of the photothermal evaporation layer, and the liquid inlet interface of the lithium enrichment / lithium deposition collection area. This allows multivalent interfering metal cations to be preferentially regulated before entering the high-concentration evaporation interface, thereby inhibiting the deposition of contaminants, including Mg(OH)2, CaCO3, CaSO4, and iron- and aluminum-containing deposits, in the photothermal layer and capillary liquid supply pores. This effectively overcomes the problems of evaporation rate decay, mass transfer channel blockage, and interface contamination.

[0019] 3) This invention utilizes the synergistic effect of interfacial selectivity and the continuous replenishment, local concentration, and lateral migration processes caused by solar evaporation to transform Li... + It mainly remains in the continuous liquid phase and migrates towards the lithium enrichment / precipitation collection zone along the evaporation and concentration gradient, without strongly adsorbing Li. + The primary objective is to reduce lithium loss due to co-precipitation, entrainment, or adsorption during the impurity removal process, and to improve the concentration of Li in the liquid phase. + Relative to Mg 2+ Ca 2+ The ratio of other multivalent interfering metal ions was used to achieve a continuous coupling of multivalent interfering metal ion shielding, interfacial solar evaporation, relative lithium enrichment, and lithium salt precipitation or lithium collection.

[0020] 4) The metal elements in the metal oxoate clusters of the present invention include almost all elements capable of forming stable metal oxoate clusters or polymetallic oxo cluster frameworks, exhibiting very wide material compatibility; moreover, the shielded interfering metal cations are not limited to Mg. 2+ and Ca 2+ It may also include Co 2+ Ni 2+ Cu 2+ Zn 2+ Fe 3+ Al 3+ It contains various divalent or trivalent metal ions, including rare earth ions, and has excellent process applicability.

[0021] 5) This invention can be integrated with lithium extraction from salt lakes, lithium extraction from geothermal brine, concentrated seawater resource utilization, lithium battery recovery liquid treatment, membrane lithium extraction, electrochemical lithium extraction, adsorption lithium extraction, solvent extraction lithium extraction, and carbonate or phosphate lithium precipitation processes. By constructing a multivalent interference ion shielding step, it can effectively reduce the hardness of the feed liquid and the load of multivalent metal impurities, thereby improving the selectivity, stability, and recovery efficiency of the lithium extraction process. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the process for synthesizing the polyniobium oxoate cluster shielding material of the present invention; Figure 2 The morphology and elemental distribution characterization of the multi-niobium oxoate cluster shielding material synthesized in this invention are shown in the figure. Figure 3 This is a schematic diagram of the process for preparing a solar evaporator based on a polyniobium oxychloride cluster shielding material according to the present invention; Figure 4 The multi-niobium oxoate cluster shielding material synthesized in this invention is used in different Mg... 2+ / Li + Mg in a simulated salt lake system 2+ Shielding and Li + Retain the test result image; Figure 5 The multi-niobium oxoate cluster shielding material synthesized in this invention is based on Na + / Mg 2+ Mg in a competitive system 2+ Shielding and Na + Retain the test result image; Figure 6 The multi-niobium oxoate cluster shielding material synthesized in this invention is in K + / Mg 2+ Mg in a competitive system 2+ Shielding and K + Retain the test result image; Figure 7 The multi-niobium oxoate cluster shielding material synthesized in this invention is based on Ca 2+ / Li + Ca in a competitive system 2+ Shielding and Li + Retain the test result image; Figure 8 This is a schematic diagram of the structure of the solar evaporator of the present invention. Detailed Implementation

[0023] The present invention will be further described in detail below with reference to specific embodiments. This is an explanation of the present invention and not a limitation thereof.

[0024] like Figure 8As shown, a solar evaporator based on a metal oxoate cluster shielding layer includes a photothermal evaporation layer, a capillary liquid supply and thermal insulation support layer, a lithium-containing high-salt water supply zone, a metal oxoate cluster shielding layer (i.e., a POM cluster shielding layer), and a lithium enrichment / lithium deposition collection zone. The photothermal evaporation layer absorbs or simulates solar irradiation and generates a localized photothermal field and water evaporation flux at the liquid-gas interface. The capillary liquid supply and thermal insulation support layer transports the lithium-containing high-salt water from the lithium-containing high-salt water supply zone to the photothermal evaporation layer and effectively reduces heat transfer losses. The lithium-containing high-salt water supply zone stores or continuously inputs lithium-containing high-salt water. The metal oxoate cluster shielding layer is positioned on the liquid-phase mass transfer path from the lithium-containing high-salt water supply zone into the photothermal evaporation layer or from the photothermal evaporation layer into the lithium enrichment / lithium deposition collection zone, used to intercept multivalent interfering metal cations in the lithium-containing high-salt water and allow Li... + With continuous liquid phase migration; the lithium enrichment / precipitation collection zone is used to collect lithium-containing concentrate produced by shielding and interfacial evaporation concentration, or to convert lithium in the lithium-containing concentrate into lithium salt crystals, lithium salt precipitates or lithium-containing complex salts through continued evaporation, cooling crystallization and addition of lithium precipitation agent.

[0025] The photothermal evaporation layer is a carbon-based photothermal material, a conductive polymer photothermal material, a metal nanomaterial, a semiconductor photothermal material, MXene, a ferrous metal oxide, a plasmonic material, or a biomass carbonization material, wherein: 1) the carbon-based photothermal material is at least one of carbon black, graphene, graphene oxide reduction products (i.e., reduced graphene oxide), carbon nanotubes, graphite powder, and porous carbon; 2) the conductive polymer photothermal material is at least one of polypyrrole, polyaniline, polydopamine, polythiophene, and polyethylenedioxythiophene; 3) the metal nanomaterial is at least one of gold nanoparticles, silver nanoparticles, copper nanoparticles, nickel nanoparticles, aluminum nanoparticles, and alloy nanoparticles; 4) the semiconductor photothermal material is at least one of copper sulfide, molybdenum sulfide, tungsten sulfide, molybdenum disulfide, tungsten diselenide, titanium oxide, zinc oxide, copper oxide, and cuprous oxide; 5) the MXene is Ti3C2T x Ti2CT x Nb2CT x V2CT x and Mo2TiC2T x At least one of them, wherein T x6) The surface end groups include -O, -OH and -F; 7) The black metal oxide is at least one of iron(II,III) oxide, ferrous oxide, copper oxide, cuprous oxide, manganese oxide, cobalt oxide, nickel oxide and titanium oxide; 8) The plasmon material is at least one of gold nanorods, gold nanoshells, silver nanowires, silver nanocubes, copper sulfide nanoparticles and aluminum nanostructures; 9) The biomass carbonization material is at least one of carbonized wood, carbonized cotton cloth, carbonized cellulose paper, carbonized bamboo, carbonized sponge, carbonized straw and carbonized coconut shell.

[0026] The capillary liquid supply and heat insulation support layer is at least one of cellulose paper, cotton cloth, wood, sponge, aerogel, foam plastic, porous ceramic, polyurethane foam, polyvinylidene fluoride membrane, polyacrylonitrile membrane, nylon membrane, glass fiber membrane and non-woven fabric, which has continuous hydrophilic capillary channels and heat insulation pore structure. The hydrophilic capillary channels include vertical liquid supply channels and lateral liquid supply channels, and the heat insulation pore structure is a hierarchical channel.

[0027] The metal oxoate cluster shielding layer is a material layer containing metal oxoate clusters, with a thickness of 0.1 μm to 5 mm and a metal oxoate cluster loading of 0.01 to 500 mg / cm³. 2 The metal oxophosphate cluster shielding layer can form a selective oxygen-rich ion-regulating interface between lithium-containing high-salt water and the photothermal evaporation layer. Through multi-point oxygen coordination, ion association, counter-ion exchange, or charge compensation, it retains multivalent interfering metal cations near the interface, thereby reducing the number of multivalent interfering ions entering the photothermal evaporation layer and overcoming the problem of scaling by multivalent interfering ions in the photothermal evaporation layer. Simultaneously, it allows water molecules and Li... + Some monovalent coexisting cations pass through the metal oxometalate cluster shielding layer, thereby maintaining the migration ability of lithium in the liquid phase and reducing lithium loss caused by co-precipitation, membrane fouling, adsorption site competition or extraction system instability.

[0028] The metal oxoate clusters are fixed to the inner wall of the capillary liquid supply insulation support layer, the interlayer interface between the capillary liquid supply insulation support layer and the photothermal evaporation layer, the liquid inlet side surface of the photothermal evaporation layer, and the liquid inlet interface of the lithium enrichment / lithium deposition collection area by means of coating, impregnation, in-situ crystallization, filtration deposition, gel composite, particle filling, and fiber loading. Specifically: 1) The coating process involves dispersing or dissolving the metal oxoate clusters in water, an alcohol / water mixture, or a dispersion medium containing a binder to form a coating liquid or slurry. This coating liquid or slurry is then fixed to the capillary liquid supply insulation support layer, the liquid inlet side surface of the photothermal evaporation layer, and the interlayer interface between the capillary liquid supply insulation support layer and the photothermal evaporation layer by means of scraping, spraying, dripping, brushing, rolling, or slot coating. The interlayer interface between the layers is then dried, cured, or cross-linked to form a continuous or semi-continuous metal oxoate cluster shielding layer; 2) The impregnation process is as follows: the porous fixed carrier, one side surface of the capillary liquid supply heat insulation support layer, the fiber network, or the liquid inlet side of the photothermal evaporation layer are immersed in a solution or dispersion containing metal oxoate clusters, so that the metal oxoate clusters enter the pores of the porous fixed carrier, the capillary liquid supply heat insulation support layer, the fiber network, and the photothermal evaporation layer and adhere to the pore walls under the action of capillary wetting, electrostatic adsorption, hydrogen bonding, coordination anchoring, counterion exchange, or polymer bonding. After removal, the surface free liquid is removed and dried to obtain a layer loaded on one side surface of the porous fixed carrier and the capillary liquid supply heat insulation support layer. 1) A metal oxoate cluster shielding layer on the liquid inlet side of the fiber network and photothermal evaporation layer; 2) The in-situ crystallization process is as follows: the precursor containing metal oxoate clusters enters the porous support, and by adjusting the pH, temperature, ionic strength, counterion type, solvent type, or adding an alcohol antisolvent, the metal oxoate clusters are induced to nucleate, grow, or precipitate in situ on the pore walls, fiber surface, or interface region, thereby forming an in-situ crystallization layer combined with the support, i.e., the metal oxoate cluster shielding layer; 3) The filtration deposition process is as follows: a dispersion containing metal oxoate cluster particles, nanosheets, microcrystals, or their composites is placed on one side of a porous membrane, porous support layer, or fiber substrate, and under negative pressure, pressure difference, or vacuum filtration, the dispersion is deposited. The liquid phase passes through the substrate, causing the metal oxoate clusters to be trapped, accumulated, and deposited on the substrate surface or pore inlet area. After washing, compaction, drying, or bonding and fixing, a filtration deposition film layer is formed, namely the metal oxoate cluster shielding layer; 5) The gel composite process is as follows: the metal oxoate clusters are added to a gel precursor solution containing monomers, polymers, crosslinking agents, natural polymers or inorganic sols, and the metal oxoate clusters are confined in the gel network through free radical polymerization, ionic crosslinking, hydrogen bond crosslinking, freeze-thaw crosslinking, sol-gel reaction or photo / thermal curing. The resulting gel network is then loaded onto the liquid supply path, interlayer interface or liquid inlet side of the evaporation layer to form an aqueous phase permeable gel composite metal oxoate cluster shielding layer;6) The particle filling process is as follows: Metal oxoate cluster particles, cluster-loaded particles, or cluster composite microparticles are filled into the pores, interlayer cavities, liquid channels, or removable packing boxes of the capillary liquid supply insulation support layer. Particle loss is prevented by a porous limiting layer, fiber skeleton, binder, gel phase, or compression structure, thereby forming a liquid-permeable and regenerable particle-filled shielding layer, i.e., a metal oxoate cluster shielding layer. 7) The fiber loading process is as follows: Metal oxoate clusters are loaded onto the surface of natural fibers, polymer fibers, inorganic fibers, carbon fibers, cellulose fibers, glass fibers, or nonwoven fibers through dip coating, spraying, layer-by-layer assembly, electrostatic adsorption, coordination anchoring, in-situ growth, or bonding fixation. The fibers loaded with metal oxoate clusters serve as a metal oxoate cluster shielding layer with continuous capillary liquid supply capability and multivalent ion shielding capability.

[0029] The metal oxophosphate cluster comprises a metal-oxygen (MO) cluster framework, oxygen-rich coordination sites, and an exchangeable counterion microenvironment, wherein: the oxygen-rich coordination sites are distributed on the metal-oxygen (MO) cluster framework, including terminal oxygen sites, bridging oxygen sites, hydroxyl oxygen sites, and deprotonated oxygen sites; the exchangeable counterion microenvironment includes Li + Na + K + NH4 + At least one of the quaternary ammonium salt cations.

[0030] The cluster metal (M) in the metal oxoate cluster includes at least one of Nb, Ta, W, Mo, V, Ti, and Zr. Correspondingly, the metal oxoate cluster is a niobium-containing oxygen cluster, a tantalum-containing oxygen cluster (synthetic method can be found in Polyoxometalates, 2023, 2: 9140023.), a tungsten-containing oxygen cluster (synthetic method can be found in Chem. Soc. Rev., 2012, 41, 7497-7536), a molybdenum-containing oxygen cluster (synthetic method can be found in Bioact. Mater. 2026, 59, 662–677), a vanadium-containing oxygen cluster (synthetic method can be found in Inorg. Chem. Front., 2025, 12, 7845-7854), a titanium-containing oxygen cluster (synthetic method can be found in ACSNano 2025, 19, 41, 36749–36757), or a zirconium-containing oxygen cluster (synthetic method can be found in J. Am. Chem.). Soc., 2024, 146(16): 11400-11410) or complex metal oxoate clusters (synthetic methods can be found in Sci. Adv. 2023, 9, eadi6595).

[0031] This invention forms a metal oxoate cluster shielding material with a cluster framework, oxygen-rich coordination interface, and exchangeable counterion microenvironment through a continuous process of "strong base activation—hydrothermal polynuclearization—liquid phase separation—antisolvent crystallization—low-temperature washing". The specific process is as follows: a metal source, an alkali source, and water are mixed, and the metal source is hydroxylated, dissolved, and metal-oxygen coordination units are generated in a strongly alkaline aqueous phase to obtain a reaction solution containing metal-oxygen coordination units. The reaction solution is placed in a closed hydrothermal system to cause the metal-oxygen coordination units to condense, rearrange, and polynuclearize, forming a liquid-phase precursor containing metal oxoate clusters. An alcohol antisolvent is added to the precursor to cause the metal oxoate clusters to nucleate and precipitate from the liquid phase. The precursor is then washed and dried with a low-temperature alcohol / water mixture to obtain the metal oxoate cluster shielding material.

[0032] The metal oxoate cluster shielding layer is a multi-niobium oxide cluster shielding layer, and its preparation process is described in [reference needed]. Figure 1 The details are as follows: Step 1, according to niobium element and OH - With a molar ratio of 1:(20~90), take niobium source and alkali source, and then take deionized water according to the ratio of niobium source to deionized water of 0.1 g:(5~30 mL). Then mix the niobium source, alkali source and deionized water to form a reaction solution containing niobium oxygen coordination units. The niobium source is niobium pentoxide, niobic acid, or alkali metal niobate, wherein: the niobic acid is metaniobic acid or orthoniobic acid; the alkali metal niobate is at least one of sodium metaniobate, potassium metaniobate, sodium orthoniobate, potassium orthoniobate, sodium hexaniobate, and potassium hexaniobate, or it may be at least one of the hydrates of the above alkali metal niobates; The alkaline source is potassium hydroxide, sodium hydroxide, or lithium hydroxide; Step 2: Transfer the reaction solution to the reaction vessel and seal it. At a temperature of 160~220℃, perform a hydrothermal reaction for 48~120h to allow the niobium-containing oxygen coordination units to condense, rearrange, and multinucleate. After the reaction is completed, allow it to cool naturally to room temperature, stand, and collect the liquid-phase precursor containing niobium oxyacid acid salt clusters. Step 3: Add alcohol antisolvent to the liquid precursor containing niobium oxoate clusters according to the volume ratio of alcohol antisolvent to niobium oxoate clusters (1~5):1 to induce the precipitation of niobium oxoate clusters. After washing with alcohol / water mixture, dry to obtain multi-niobium oxoate clusters. The alcohol antisolvent is at least one of methanol, anhydrous ethanol and isopropanol; Step 4: Fix the multi-niobium oxide clusters onto a porous carrier, fiber network, or gel network to obtain a multi-niobium oxide cluster shielding layer.

[0033] Preferably, in step 1, niobium and OH - Molar ratio 1:(40~70).

[0034] Preferably, in step 1, the ratio of niobium source to deionized water is 0.1 g: (8 ~ 15 mL).

[0035] Preferably, in step 2, the hydrothermal reaction temperature is 190~210℃ and the reaction time is 72~108 h.

[0036] Preferably, in step 3, the volume ratio of the alcohol antisolvent to the liquid precursor containing niobium oxoate clusters is (2~4):1.

[0037] Preferably, in step 3, the alcohol / water mixture is prepared by mixing alcohol and deionized water at a volume ratio of (0.5~2):1, wherein the alcohol is anhydrous methanol or anhydrous ethanol. The polyniobium-oxygen cluster possesses a niobium-oxygen framework, terminal oxygen sites, bridging oxygen coordination sites, and an alkali metal counterion microenvironment, enabling it to thrive in high-salt water phases, especially for Mg... 2+ Ca 2+ It exhibits rapid binding and preferential interception capabilities, while reducing Li + Na + and K + Co-removal of monovalent ions.

[0038] The lithium enrichment / precipitation collection zone is located on the side or around the metal oxoate cluster shielding layer or in an external liquid phase circulation unit. It is used to collect the lithium-containing concentrate after interfacial evaporation and concentration. The lithium-containing concentrate enters the lithium enrichment / precipitation collection zone under the action of capillary force, gravity, concentration gradient, liquid level difference or external circulation driving force. The lithium enrichment / precipitation collection zone temporarily stores the lithium-containing concentrate. Through continued evaporation, cooling crystallization and the addition of lithium precipitation agent, the lithium in the lithium-containing concentrate is converted into lithium salt crystals, lithium salt precipitates or lithium-containing complex salts, thereby achieving lithium enrichment. This couples the lithium-containing liquid phase migration path after the multivalent interfering metal cation shielding with the lithium enrichment or precipitation collection path.

[0039] Preferably, the lithium precipitation agent is at least one selected from carbonate, bicarbonate, phosphate, hydroxide and oxalate.

[0040] The lithium-containing high-salinity brine supply area is used for storing or continuously supplying lithium-containing high-salinity brine, which may be salt lake brine, geothermal brine, underground brine, oil and gas field brine, concentrated seawater, lithium-containing mineral leachate, lithium battery recovery saline wastewater, or lithium-containing industrial high-salinity wastewater, containing Li. + Monovalent coexisting cations and multivalent interfering metal cations, wherein: monovalent coexisting cations include Na + K + and NH 4+ Multivalent interfering metal cations include divalent and trivalent metal cations, namely Mg... 2 + Ca 2+、Sr 2+ Ba 2+ Fe 2+ Mn 2+ Co 2+ Ni 2+ Zn 2+ Al 3+ Fe 3+ Cr 3+ La 3+ Ce 3+ Pr 3+ and Nd 3+ Typically, the total salt concentration of lithium-containing high-salinity brine is 1 g / L to saturation salinity, Mg 2+ / Li + The molar ratio is 10~1500, Ca 2+ / Li + The molar ratio is 0.5~50.

[0041] The lithium-containing high-salt water supply area is a static storage area, or it can be connected to a circulating pump, a liquid guide tank, an external storage tank, or a continuous feeding system to achieve dynamic replenishment.

[0042] A method for lithium enrichment in a solar evaporator based on a metal oxoate cluster shielding layer includes the following steps: S1. Inject lithium-containing high-salt water into the lithium-containing high-salt water supply area and make the lithium-containing high-salt water contact the supply side of the capillary supply heat insulation support layer, so that the evaporation side of the photothermal evaporation layer is exposed to the environment and receives solar radiation or simulated solar radiation. S2. Under solar irradiation or simulated solar irradiation, the photothermal evaporation layer converts light energy into interfacial heat energy, forming a localized hot zone on the evaporation side and driving water to migrate and evaporate from the liquid supply side of the photothermal evaporation layer to the evaporation side along continuous hydrophilic capillary channels. This establishes an evaporation-induced continuous replenishment flux, a localized ion concentration zone generated by water removal, and temperature and concentration gradients distributed along the mass transfer path inside the evaporator. S3. Under the combined effects of continuous replenishment flux, local ion concentration zone, and temperature and concentration gradients, valence-interfering metal cations in lithium-containing high-salt water are preferentially retained at the oxygen-rich ion-controlled interface through multi-point oxygen coordination, charge compensation, counter-ion exchange, and ion association. This reduces the proportion entering the photothermal evaporation layer and capillary supply insulation support layer, thereby inhibiting inorganic scaling, pore blockage, photothermal layer contamination, and lithium entrainment loss. + Remaining in the liquid phase, as the concentrate migrates from the metal oxoate cluster shielding layer to the photothermal evaporation layer and the lithium enrichment / precipitation collection zone, the molar ratio of multivalent interfering metal cations to lithium ions entering the evaporation and concentration zone is reduced. S4, containing Li + The liquid phase continues to evaporate and concentrate in the photothermal evaporation layer, and Li+ Under the influence of lateral liquid flow, evaporation concentration gradient and circulating liquid supply, it migrates to the lithium enrichment / lithium precipitation collection area; S5. Directly collect the lithium-containing concentrate temporarily stored in the lithium enrichment / lithium precipitation collection area, or convert the lithium in the lithium-containing concentrate into lithium salt crystals, lithium salt precipitates (such as lithium carbonate, lithium phosphate, lithium hydroxide hydrate) or lithium-containing complex salts by continuing evaporation, cooling crystallization and adding lithium precipitation agents. Then collect the lithium salt crystals, lithium salt precipitates and lithium-containing complex salts. At the same time, collect the fresh water obtained by condensing the water vapor on the evaporation side of the photothermal evaporation layer.

[0043] Preferably, the intensity of the solar irradiance or simulated solar irradiance is 0.2 ~ 2.0 kW / m². 2 This keeps the temperature on the evaporation side of the photothermal evaporation layer between 25 and 90°C.

[0044] Preferably, the evaporation methods of S1 to S5 are intermittent liquid supply evaporation, continuous liquid supply evaporation, cyclic concentration evaporation, multi-stage series evaporation, or natural sunlight evaporation.

[0045] Preferably, the metal oxophosphate cluster shielding layer is effective against Mg. 2+ The capture rate is no less than 98%, for Ca 2+ The capture rate is no less than 96% for Li + The retention rate is no less than 96%.

[0046] Preferably, step S5 further includes: when the metal oxoate cluster shielding layer reaches a preset multivalent interfering metal cation loading, or when the evaporator flux drops to a preset value, contacting the metal oxoate cluster shielding layer with the regeneration liquid to desorb the retained multivalent interfering metal cations, and then rinsing the metal oxoate cluster shielding layer for continued use in the solar evaporator.

[0047] The regenerated solution is at least one of an alkaline eluent, a salt solution, a complexing agent solution, and deionized water, wherein: the alkaline eluent includes potassium hydroxide solution and sodium hydroxide solution; the complexing agent solution includes citrate solution and ethylenediaminetetraacetic acid solution.

[0048] Preferably, in step S5, the lithium enrichment / precipitation collection zone is directly subjected to further evaporation, pH adjustment, cooling crystallization, and addition of a lithium precipitation agent, or the lithium-containing concentrate is input into adsorption lithium extraction, ion sieve lithium extraction, membrane separation lithium extraction, electrochemical lithium extraction, solvent extraction lithium extraction, lithium precipitation, and evaporation crystallization processes, so that lithium is precipitated in the form of separable lithium salts or lithium-containing solid phases.

[0049] Example 1 Step 1: Preparation of multi-niobium oxygen clusters Step 1.1, according to niobium element and OH -With a molar ratio of 1:26.5, weigh 0.80 g of niobium pentoxide and 8.96 g of potassium hydroxide, add them to a 100 mL polytetrafluoroethylene-lined reaction vessel, add 80 mL of deionized water, and stir for 5 min at room temperature to allow niobium pentoxide to gradually form niobium-containing oxygen coordination units that can participate in hydrothermal condensation in the strongly alkaline aqueous phase, thus obtaining a reaction solution containing niobium-containing oxygen coordination units. Step 1.2: Transfer the reaction solution to the reaction vessel and seal it. Perform a hydrothermal reaction at 200 °C for 96 h. After the reaction is complete, allow it to cool naturally to room temperature, let it stand, and collect the supernatant containing niobium oxyacid clusters. Step 1.3: Add methanol three times its volume to the supernatant and stir for 30 min to allow the dissolved niobium-containing metal oxoate clusters to precipitate from the liquid phase, yielding a white solid; Step 1.4: Mix methanol and water at a volume ratio of 1:1 to obtain a methanol / deionized water mixture. Wash the white solid three times with the methanol / deionized water mixture, and then dry it at low temperature for 3 hours to obtain niobium-oxygen clusters. Step 2: Fabrication of a solar evaporator based on multiple niobium-oxygen clusters Step 2.1: Take hydrophilic cellulose paper as the capillary liquid supply insulation support layer, clean and dry it, then disperse the niobium-oxygen clusters in deionized water to obtain a niobium-oxygen cluster dispersion. Immerse the capillary liquid supply insulation support layer in the niobium-oxygen cluster dispersion, allowing the niobium-oxygen clusters to be loaded onto the surface of the capillary liquid supply insulation support layer. After drying, a 10 μm thick niobium-oxygen cluster shielding layer is formed on the surface of the capillary liquid supply insulation support layer, with a niobium-oxygen cluster loading of 0.1 mg / cm³. 2 ; Step 2.2: Coat the surface of the multi-niobium oxygen cluster shielding layer with a composite slurry of carbon black and polyvinyl alcohol to form a photothermal evaporation layer with high solar absorptivity and water flux, thus obtaining the solar evaporator body; Step 2.3: The capillary liquid supply insulation support layer side is brought into contact with the lithium-containing high-salt water inside the lithium-containing high-salt water supply area. A lithium enrichment / lithium precipitation collection area connected to it is set on the side of the solar evaporator body, resulting in... Figure 3 The partitioned solar evaporator shown.

[0050] Example 2 Step 1: Preparation of multi-niobium oxygen clusters Step 1.1, according to niobium element and OH -With a molar ratio of 1:20, weigh 0.80 g of niobic acid (HNbO3) and 6.33 g of potassium hydroxide, add them to a 100 mL polytetrafluoroethylene-lined reaction vessel, add 40 mL of deionized water, and stir for 5 min at room temperature to allow niobium pentoxide to gradually form niobium-containing oxygen coordination units that can participate in hydrothermal condensation in the strongly alkaline aqueous phase, thus obtaining a reaction solution containing niobium-containing oxygen coordination units; Step 1.2: Transfer the reaction solution to the reaction vessel and seal it. Perform a hydrothermal reaction at 160°C for 120 h. After the reaction is complete, allow it to cool naturally to room temperature, let it stand, and collect the supernatant containing niobium oxyacid clusters. Step 1.3: Add an equal volume of methanol to the supernatant and stir for 30 min to allow the dissolved niobium-containing metal oxoate clusters to precipitate from the liquid phase, yielding a white solid; Step 1.4: Mix methanol and water at a volume ratio of 0.5:1 to obtain a methanol / deionized water mixture. Wash the white solid three times with the methanol / deionized water mixture, and then dry it at low temperature for 3 hours to obtain niobium-oxygen clusters. Step 2: Fabrication of a solar evaporator based on multiple niobium-oxygen clusters Step 2.1: Take hydrophilic wood veneers as the capillary liquid supply insulation support layer, clean and dry them, then disperse the niobium-oxygen clusters in a mixed solution of equal volumes of methanol and deionized water to obtain a niobium-oxygen cluster dispersion. Then, through vacuum filtration, the niobium-oxygen clusters are deposited on the surface of the capillary liquid supply insulation support layer. After drying, a 500 μm thick niobium-oxygen cluster shielding layer is formed on the surface of the capillary liquid supply insulation support layer, with a niobium-oxygen cluster loading of 50 mg / cm³. 2 ; Step 2.2: Coat the graphene / carbon nanotube dispersion onto the surface of the niobium-oxygen cluster shielding layer to form a photothermal evaporation layer with high solar absorptivity and water flux, thus obtaining the solar evaporator body; Step 2.3: The capillary liquid supply insulation support layer side is brought into contact with the lithium-containing high-salt water inside the lithium-containing high-salt water supply area. A lithium enrichment / lithium precipitation collection area connected to it is set on the side of the solar evaporator body, resulting in... Figure 3 The partitioned solar evaporator shown.

[0051] Example 3 Step 1: Preparation of multi-niobium oxygen clusters Step 1.1, according to niobium element and OH -With a molar ratio of 1:90, weigh 0.80 g of anhydrous sodium metaniobate (NaNbO3) and 17.57 g of sodium hydroxide, add them to a 300 mL polytetrafluoroethylene-lined reaction vessel, then add 240 mL of deionized water, and stir for 5 min at room temperature to allow niobium pentoxide to gradually form niobium-containing oxygen coordination units that can participate in hydrothermal condensation in the strongly alkaline aqueous phase, thus obtaining a reaction solution containing niobium-containing oxygen coordination units; Step 1.2: Transfer the reaction solution to the reaction vessel and seal it. Perform a hydrothermal reaction at 220°C for 48 hours. After the reaction is complete, allow it to cool naturally to room temperature, let it stand, and collect the supernatant containing niobium oxyacid clusters. Step 1.3: Add 5 times the volume of methanol to the supernatant and stir for 30 min to allow the dissolved niobium-containing metal oxoate clusters to precipitate from the liquid phase, resulting in a white solid. Step 1.4: Mix methanol and water at a volume ratio of 2:1 to obtain a methanol / deionized water mixture. Wash the white solid three times with the methanol / deionized water mixture, and then dry it at low temperature for 3 hours to obtain niobium-oxygen clusters. Step 2: Fabrication of a solar evaporator based on multiple niobium-oxygen clusters Step 2.1: Use polyurethane foam as the capillary liquid supply insulation support layer, clean and dry it, then disperse multi-niobium oxygen clusters in a mixed solution of equal volumes of methanol and deionized water to obtain a multi-niobium oxygen cluster dispersion. Then, by spraying, deposit the multi-niobium oxygen clusters onto the surface of the capillary liquid supply insulation support layer. After drying, a multi-niobium oxygen cluster shielding layer with a thickness of 1 mm is formed on the surface of the capillary liquid supply insulation support layer, and the multi-niobium oxygen cluster loading is 100 mg / cm³. 2 ; Step 2.2: Load iron oxide onto the surface of the multi-niobium oxygen cluster shielding layer to form a photothermal evaporation layer with high solar absorptivity and water flux, thus obtaining the solar evaporator body; Step 2.3: The capillary liquid supply insulation support layer side is brought into contact with the lithium-containing high-salt water inside the lithium-containing high-salt water supply area. A lithium enrichment / lithium precipitation collection area connected to it is set on the side of the solar evaporator body, resulting in... Figure 3 The partitioned solar evaporator shown.

[0052] Example 4 Step 1: Preparation of multi-niobium oxygen clusters Step 1.1, according to niobium element and OH -With a molar ratio of 1:40, weigh 0.80 g of anhydrous potassium metaniobate (KNbO3) and 4.26 g of anhydrous lithium hydroxide, add them to a 100 mL polytetrafluoroethylene-lined reaction vessel, then add 64 mL of deionized water, and stir for 5 min at room temperature to allow niobium pentoxide to gradually form niobium-containing oxygen coordination units that can participate in hydrothermal condensation in the strongly alkaline aqueous phase, thus obtaining a reaction solution containing niobium-containing oxygen coordination units; Step 1.2: Transfer the reaction solution to the reaction vessel and seal it. Perform a hydrothermal reaction at 190°C for 108 h. After the reaction is complete, allow it to cool naturally to room temperature, let it stand, and collect the supernatant containing niobium oxoate clusters. Step 1.3: Add methanol twice its volume to the supernatant and stir for 30 min to allow the dissolved niobium-containing metal oxoate clusters to precipitate from the liquid phase, yielding a white solid; Step 1.4: Mix methanol and water at a volume ratio of 1.5:1 to obtain a methanol / deionized water mixture. Wash the white solid three times with the methanol / deionized water mixture, and then dry it at low temperature for 3 hours to obtain niobium-oxygen clusters. Step 2: Fabrication of a solar evaporator based on multiple niobium-oxygen clusters Step 2.1: Take a sponge as the capillary liquid supply insulation support layer, clean and dry it, then disperse the multi-niobium oxygen clusters in a mixed solution of equal volumes of methanol and deionized water to obtain a multi-niobium oxygen cluster dispersion. Then, by scraping, the multi-niobium oxygen clusters are deposited on the surface of the capillary liquid supply insulation support layer. After drying, a multi-niobium oxygen cluster shielding layer with a thickness of 200 μm is formed on the surface of the capillary liquid supply insulation support layer, and the multi-niobium oxygen cluster loading is 25 mg / cm³. 2 ; Step 2.2, Ti3C2T x Loaded onto the surface of a multi-niobium oxygen cluster shielding layer, a photothermal evaporation layer with high solar absorptivity and water flux is formed, thus obtaining the main body of the solar evaporator; Step 2.3: The capillary liquid supply insulation support layer side is brought into contact with the lithium-containing high-salt water inside the lithium-containing high-salt water supply area. A lithium enrichment / lithium precipitation collection area connected to it is set on the side of the solar evaporator body, resulting in... Figure 3 The partitioned solar evaporator shown.

[0053] Example 5 Step 1: Preparation of multi-niobium oxygen clusters Step 1.1, according to niobium element and OH -With a molar ratio of 1:55, weigh 0.80 g of niobic acid (H3NbO4) and 15.44 g of potassium hydroxide, add them to a 150 mL polytetrafluoroethylene-lined reaction vessel, then add 96 mL of deionized water, and stir for 5 min at room temperature to allow niobium pentoxide to gradually form niobium-containing oxygen coordination units that can participate in hydrothermal condensation in the strongly alkaline aqueous phase, thus obtaining a reaction solution containing niobium-containing oxygen coordination units; Step 1.2: Transfer the reaction solution to the reaction vessel and seal it. Perform a hydrothermal reaction at 210°C for 72 h. After the reaction is complete, allow it to cool naturally to room temperature, let it stand, and collect the supernatant containing niobium oxyacid clusters. Step 1.3: Add 4 times the volume of methanol to the supernatant and stir for 30 min to precipitate the dissolved niobium-containing metal oxoate clusters from the liquid phase, resulting in a white solid; Step 1.4: Mix isopropanol and water at a volume ratio of 1.5:1 to obtain an isopropanol / deionized water mixture. Wash the white solid three times with the isopropanol / deionized water mixture, and then dry it at low temperature for 3 hours to obtain a polyniobium oxygen cluster. Step 2: Fabrication of a solar evaporator based on multiple niobium-oxygen clusters Step 2.1: Take a polyvinylidene fluoride (PVDF) membrane as the capillary liquid supply insulation support layer, clean and dry it, then disperse the multi-niobium oxygen clusters in a mixed solution of equal volumes of methanol and deionized water to obtain a multi-niobium oxygen cluster dispersion. Then, by spraying, the multi-niobium oxygen clusters are deposited on the surface of the capillary liquid supply insulation support layer. After drying, a multi-niobium oxygen cluster shielding layer with a thickness of 750 μm is formed on the surface of the capillary liquid supply insulation support layer, and the multi-niobium oxygen cluster loading is 75 mg / cm³. 2 ; Step 2.2: Load copper sulfide onto the surface of the multi-niobium oxygen cluster shielding layer to form a photothermal evaporation layer with high solar absorptivity and water flux, thus obtaining the solar evaporator body; Step 2.3: The capillary liquid supply insulation support layer side is brought into contact with the lithium-containing high-salt water inside the lithium-containing high-salt water supply area. A lithium enrichment / lithium precipitation collection area connected to it is set on the side of the solar evaporator body, resulting in... Figure 3 The partitioned solar evaporator shown.

[0054] Example 6 Step 1: Preparation of multi-niobium oxygen clusters Step 1.1, according to niobium element and OH - With a molar ratio of 1:70, weigh out 0.80 g of anhydrous sodium hexaniobate (Na8Nb6O). 19Add 12.85 g of sodium hydroxide to a 200 mL polytetrafluoroethylene-lined reaction vessel, then add 120 mL of deionized water. Stir for 5 min at room temperature to allow niobium pentoxide to gradually form niobium-containing oxygen coordination units that can participate in hydrothermal condensation in the strongly alkaline aqueous phase, thus obtaining a reaction solution containing niobium-containing oxygen coordination units. Step 1.2: Transfer the reaction solution to the reaction vessel and seal it. Perform a hydrothermal reaction at 180°C for 84 hours. After the reaction is complete, allow it to cool naturally to room temperature, let it stand, and collect the supernatant containing niobium oxyacid clusters. Step 1.3: Add methanol three times its volume to the supernatant and stir for 30 min to allow the dissolved niobium-containing metal oxoate clusters to precipitate from the liquid phase, yielding a white solid; Step 1.4: Mix anhydrous ethanol and water at a volume ratio of 0.5:1 to obtain an ethanol / deionized water mixture. Wash the white solid three times with the ethanol / deionized water mixture, and then dry it at low temperature for 3 hours to obtain niobium-oxygen clusters. Step 2: Fabrication of a solar evaporator based on multiple niobium-oxygen clusters Step 2.1: Take foam plastic as the capillary liquid supply insulation support layer, clean and dry it, then disperse the multi-niobium oxygen clusters in a mixed solution of equal volumes of anhydrous ethanol and deionized water to obtain a multi-niobium oxygen cluster dispersion. Then, by spraying, the multi-niobium oxygen clusters are deposited on the surface of the capillary liquid supply insulation support layer. After drying, a multi-niobium oxygen cluster shielding layer with a thickness of 800 μm is formed on the surface of the capillary liquid supply insulation support layer, and the multi-niobium oxygen cluster loading is 80 mg / cm³. 2 ; Step 2.2: Fix carbonized wood onto the surface of the niobium-oxygen cluster shielding layer to form a photothermal evaporation layer with high solar absorptivity and water flux, thus obtaining the solar evaporator body; Step 2.3: The capillary liquid supply insulation support layer side is brought into contact with the lithium-containing high-salt water inside the lithium-containing high-salt water supply area. A lithium enrichment / lithium precipitation collection area connected to it is set on the side of the solar evaporator body, resulting in... Figure 3 The partitioned solar evaporator shown.

[0055] Figure 2The microstructure of the multi-niobium oxo-acid clusters prepared in Example 1 is shown. It can be seen that they exhibit regular or semi-regular micron-sized crystal morphologies. The crystal particles have obvious facets, tips, and layered growth textures, indicating that under strong alkaline hydrothermal conditions, niobium-oxygen coordination units can condense and form highly crystalline multi-niobium oxo-acid clusters. The material contains plate-like, spindle-shaped, or polyhedral crystal particles of different sizes, with the crystal scale mainly in the micron range. Clear step-like or layered textures can be observed on the surface of larger crystal particles, indicating that this material is not an amorphous precipitate but a multi-niobium oxo-acid cluster shielding crystal material with crystal face development characteristics. Furthermore, the elemental distribution diagram shows that Nb, O, and K elements are uniformly spatially distributed within the crystal region. Nb and O constitute the shielding framework of the multi-niobium oxo-acid clusters, while K element is distributed in the material structure as a counterion or interlayer equilibrium ion. Therefore, Example 1, using a strong alkaline hydrothermal reaction combined with methanol antisolvent precipitation, can effectively obtain a material with clear morphology, uniform elemental distribution, and multi-niobium oxo-acid cluster shielding structure characteristics, which is crucial for subsequent applications including Ca²⁺. + and Mg² + The selective binding of multivalent interfering ions, including those present, provides a structural basis.

[0056] To further illustrate the lithium enrichment method of the solar evaporator prepared in Examples 1 to 6 of the present invention, a simulated salt lake brine is now used as a high-lithium-containing brine to briefly describe the lithium enrichment method of the solar evaporator: Lithium-containing brine is prepared... + Na + K + and Mg 2+ and Ca 2+ Simulated salt lake brine, including lithium-containing high-salinity brine, is added to the lithium-containing high-salinity brine supply zone. Under simulated sunlight or natural sunlight, the photothermal evaporation layer absorbs light energy and generates a local evaporation interface on its upper surface. The lithium-containing high-salinity brine is transported upward along the supply layer under capillary action. The terminal oxygen, bridging oxygen, hydroxyl oxygen, and deprotonated oxygen sites in the niobium-oxygen cluster shielding layer interact with Mg... 2+ Ca 2+ Multivalent metal cations undergo multi-point oxygen coordination, charge compensation, ion association, and counterion replacement, causing them to preferentially reside in the shielding layer. This reduces the deposition of scale, including Mg(OH)₂, CaCO₃, and CaSO₄, in the photothermal evaporation layer and the liquid supply channels. As water continues to evaporate, Li… + It mainly remains in the liquid phase and migrates to the lithium enrichment / precipitation collection area to obtain lithium enrichment solution. It can continue to evaporate until the lithium enrichment solution reaches supersaturation, or a lithium precipitation agent can be added to the lithium enrichment solution to precipitate and collect lithium ions in the solid phase form of lithium carbonate, lithium phosphate or lithium complex salt.

[0057] To verify the lithium-ion enrichment effect of the multi-niobium oxygen clusters prepared in this invention, the following tests were conducted: 1) Lithium ion enrichment in a high Mg2+ / Li+ simulated salt lake system: The multi-niobium oxygen cluster shielding material prepared in Example 1 was mixed with different Mg... 2+ / Li + In a simulated lithium-containing brine solution with a molar ratio, a contact reaction was carried out at room temperature, and the Mg content in the solution was measured from 1 min to 24 h. 2+ With Li + Concentration changes were simulated in high magnesium-to-lithium ratio systems corresponding to East Taijinaier Salt Lake, West Taijinaier Salt Lake, Yiliping Salt Lake, and Qarhan Salt Lake. Experimental results are as follows: Figure 4 As shown, it can be seen that in Mg 2+ / Li + In different simulated salt lake systems with molar ratios increasing from 37 to 1500, the niobium-oxygen cluster shielding material in Example 1 all exhibited resistance to Mg. 2+ Its rapid and efficient capture capability, while also targeting Li + They exhibited a lower propensity to consume, specifically: Figure 4 (a) shows the simulated system of Dongtaijinaier Salt Lake, where Mg 2+ The capture rate is greater than 99.71%, Li + The retention rate is greater than 98.01%; Figure 4 (b) shows the simulated system of the West Taijinaier Salt Lake, where Mg 2+ The capture rate was greater than 99.26% within 5 minutes and greater than 99.93% after 24 hours. + The retention rate was greater than 98.01%; in the Yiliping Salt Lake simulation system, Mg 2+ The capture rate is greater than 99.78%, Li + The retention rate is greater than 98.24%; Figure 4 (c) shows the simulated system of Yiliping Salt Lake, Mg 2+ The capture rate is still greater than 99.78%, Li + The retention rate is greater than 98.24%; Figure 4 (d) shows the simulated system of the Qarhan Salt Lake, even if Mg 2+ / Li + The molar ratio is as high as 1500, Mg 2+ The capture rate remained greater than 99.69% within 5 minutes and greater than 99.85% after 24 hours. + The retention rate is greater than 98.68%; specifically, from Figure 4 It can be seen that Mg 2+ The concentration decreased rapidly and approached the low detection value shortly after the material was added, while Li + The concentration remained basically stable, indicating that the niobium-oxygen cluster shielding material effectively protected Mg. 2+The bonding process exhibits rapid kinetics and can be carried out at extremely high Mg levels. 2+ Background and low Li + Effectively avoid Li under certain concentration conditions + Co-adsorption indicates that multi-niobium oxygen cluster shielding materials are suitable for use in high magnesium-to-lithium ratio salt lake brines containing Mg. 2+ It is a preferred removal and pretreatment for lithium resource enrichment, and is especially suitable for reducing the magnesium-lithium ratio in brine and improving the selectivity and efficiency of subsequent lithium extraction processes.

[0058] 2) Na + and K + Mg in a competitive system 2+ Selectivity test: The niobium-oxygen cluster shielding material obtained in Example 1 was added to Na... + / Mg 2+ The molar ratios are 0.1, 1, 5, and 10, and K... + / Mg 2+ In the competing systems with molar ratios of 0.01, 0.1, 1, and 5, the experimental results are as follows: Figure 5 and Figure 6 As shown: Depend on Figure 5 It can be seen that in Na + With Mg 2+ In coexisting systems, multi-niobium oxygen cluster shielding materials for Mg 2+ It still maintains a significant preferential binding capacity when Na + / Mg 2+ When the molar ratio varies from 0.1 to 10, Mg 2+ The capture rate was greater than 98.13% within 5 minutes and greater than 99.04% after 24 hours; meanwhile, Na + The retention rate was still greater than 96.34% after 24 hours, and, in different Na... + / Mg 2+ In a competitive system, within 5 minutes, Mg² + The capture rates were greater than 98.41%, 98.63%, 98.61%, and 98.13%, respectively, and increased to greater than 99.81%, 99.04%, 99.69%, and 99.66% within 4 hours, while Na... + The retention rates were greater than 97.77%, 97.96%, 96.34%, and 96.48%, respectively, indicating that Na... + As a monovalent cation with high content in salt lake brine and seawater, it did not significantly inhibit the shielding effect of niobium-oxygen cluster shielding materials on Mg. 2+ Prioritize combination; Depend on Figure 6 It can be seen that in K + With Mg 2+In coexisting systems, niobium-containing metal oxoate cluster shielding materials also exhibit resistance to Mg. 2+ Its high selective capture capability. In K + / Mg 2+ In the molar ratio range of 0.01 to 5, Mg 2+ The capture rate was greater than 99.12%, K + The retention rates were all greater than 97.33%. Specifically, different K values... + / Mg 2+ In a competitive system, Mg 2+ The capture rates were greater than 99.24%, 99.12%, 99.88%, and 99.83%, respectively. + The retention rates were greater than 97.33%, 99.39%, 99.27%, and 98.62%, respectively; these results indicate that even at K... + Under conditions of significant concentration changes, niobium-containing metal oxoate cluster shielding materials can still preferentially bind Mg. 2+ And for K + Intake was relatively weak; In summary, through Figure 5 and Figure 6 The results show that niobium-oxygen cluster shielding materials are effective against Mg. 2+ The selectivity does not simply depend on the amount of Mg in the solution. 2+ The relative concentration is not determined by the concentration of Mg²⁺, but rather originates from oxygen-rich sites on the material surface or within the framework. + The stronger coordination between them is because: compared to Na + and K + Monovalent cations, Mg 2+ With higher charge density and stronger hard acid characteristics, it is easier to form stable bonds with terminal oxygen, bridging oxygen, or deprotonated oxygen sites in the niobium-containing oxometalate cluster shielding framework. Therefore, niobium-containing oxometalate cluster shielding materials can achieve Mg2+ bonding in complex salt water systems. 2+ with Na + K + It effectively distinguishes between different types of magnesium ions and is suitable for the selective removal of magnesium ions in high-salt environments.

[0059] 3) Ca 2+ / Li + Lithium-ion enrichment in a competitive system: using the multi-niobium oxygen cluster shielding material from Example 1 for Ca 2+ / Li + Competitive system, Ca 2+ / Li + The molar ratios were set to 0.5, 1, 10, and 50, respectively, and the Ca was tested. 2+ Capture rate and Li + Retention rate, results as follows Figure 7 As shown, in different Ca 2+ / Li+ Under the specified molar ratio conditions, all niobium-oxygen cluster shielding materials can rapidly trap Ca. 2+ At the same time, Li + It is mainly retained in the solution, specifically: when Ca 2+ / Li + When the molar ratio is 0.5 and 1, Ca 2+ The capture rates within 5 minutes were greater than 99.38% and 99.14%, respectively, and the capture rates within 24 hours were greater than 99.91% and 99.63%, respectively. + The retention rates within 24 hours were greater than 98.78% and 99.27%, respectively; when Ca 2+ / Li + When the molar ratio is increased to 10 and 50, Ca 2+ The capture rates within 5 minutes were greater than 96.20% and 97.35%, respectively, and the capture rates within 24 hours were greater than 99.32% and 99.72%, respectively. + The retention rates within 24 hours were greater than 96.15% and 98.10%, respectively; furthermore, by Figure 5 It can be seen that Ca 2+ The concentration decreased rapidly upon contact with the niobium-oxygen cluster shielding material, while Li + The concentration remained at a relatively high level even after prolonged contact, indicating that the material can withstand Ca... 2+ / Li + Achieving Ca² in a competitive system + Preferred combination with Li + The effective retention of is due to: [the relationship with Mg] 2+ Similarly, Ca 2+ As a divalent hard acid cation, Li can interact strongly with oxygen-rich coordination sites in the multi-niobium cluster shielding framework. + Due to their higher degree of hydration, different effective ionic radii and coordination behaviors, they are less likely to bind significantly on the surface of shielding materials.

[0060] comprehensive Figures 4-7 The results show that the multi-niobium oxygen cluster shielding material prepared in this invention can effectively shield Mg in different salt lake simulation systems and various competing cation systems. 2+ and Ca 2+ It exhibits rapid, stable, and highly selective binding capabilities, especially in Mg. 2+ / Li + In a simulated Qarhan Salt Lake system with a molar ratio as high as 1500, the material can still achieve a Mg content greater than 99.85%. 2+ Capture rate, and maintain Li > 98.68% + Retention rate; in Ca 2+ / Li +In systems with molar ratios ranging from 0.5 to 50, the material's effect on Ca... 2+ The 24-hour capture rate was greater than 99.32%, Li + The retention rate remained above 96.15%, indicating that the multi-niobium oxygen cluster shielding material can be used not only in high magnesium-to-lithium ratio salt water with Mg content 2+ The selective removal of Ca can also be used in calcium-lithium systems. 2+ The preferential capture of Ca²⁺ is achieved through the preferential coordination between the niobium-oxygen cluster shielding material framework and the divalent metal cations. + / Mg 2+ With Li + Na + K + This method effectively distinguishes between different types of cations, thereby efficiently removing divalent metal cations, including calcium and magnesium, reducing interference from divalent ions, and has good application potential for promoting the enrichment of lithium resources in high-salinity brines.

[0061] In this invention, lithium enrichment refers to the reduction of Li in the liquid phase after shielding treatment and solar evaporation. + Compared to including Mg 2 + Ca 2+ Fe 3+ The molar ratio of multivalent interfering metal cations is increased, or lithium-containing concentrates, lithium salt crystals, lithium salt precipitates, or lithium-containing complex salts are obtained in the lithium enrichment / lithium precipitation collection zone.

[0062] In this invention, the metal oxoate cluster shielding layer refers to a functional interface formed by the metal oxoate cluster material in a lithium-containing high-salt water system through selective coordination, ion association, counter-ion exchange, or charge compensation with multivalent interfering metal cations. This functional interface can preferentially weaken or remove the adverse effects caused by competition, scaling, membrane fouling, adsorption site occupation, and precipitant consumption of multivalent metal ions on the subsequent lithium extraction process. Unlike traditional precipitation methods, lime-soda ash methods, membrane methods, or ordinary inorganic adsorbents, this invention utilizes the highly enriched terminal oxygen, bridging oxygen, hydroxyl oxygen, or demineralized oxygen in the metal oxoate clusters. The metal oxometalate cluster material, through its oxygen-rich coordination sites and the negative charge and exchangeable counterion environment carried by the cluster framework, achieves preferential recognition and shielding of multivalent hard acid metal cations. Simultaneously, due to the significant differences in lithium ion hydration characteristics, effective radius, monovalent charge, and coordination behavior compared to the aforementioned multivalent metal ions, lithium ions are less likely to be retained by the shielding layer, thus maintaining a high retention rate in the treatment solution. In other words, this invention uses metal oxometalate cluster materials as a selective shielding medium for multivalent interfering metal ions in lithium-containing high-salt water systems. Through oxygen-rich coordination interfaces and a counterion-regulated environment, the metal oxometalate cluster material preferentially interacts with Mg... 2+ Ca 2+ 、Sr 2+ Ba2+ Fe 2+ Mn 2+ Al 3+ Fe 3+ It reacts with one or more rare earth metal cations, and has an effect on Li + Na + K + The binding or co-removal effect of monovalent metal ions is relatively weak. Through the aforementioned selective shielding effect, the concentration of polyvalent interfering ions in lithium-containing high-salt water is significantly reduced, and lithium ions mainly remain in the liquid phase, thus reducing the concentration of Li in the liquid phase. + Relative to Mg² + Ca² + The proportion of other multivalent interfering metal ions is increased, thereby achieving lithium ion enrichment.

Claims

1. A solar evaporator based on a metal oxophosphate cluster shielding layer, characterized in that, The system comprises a photothermal evaporation layer, a capillary liquid supply and thermal insulation support layer, a lithium-containing high-salt water supply zone, a metal oxoate cluster shielding layer, and a lithium enrichment / lithium deposition collection zone. Specifically: the photothermal evaporation layer absorbs or simulates solar radiation and generates a localized photothermal field and water evaporation flux at the liquid-gas interface; the capillary liquid supply and thermal insulation support layer transports the lithium-containing high-salt water from the lithium-containing high-salt water supply zone to the photothermal evaporation layer; the lithium-containing high-salt water supply zone stores or continuously inputs lithium-containing high-salt water; and the metal oxoate cluster shielding layer is positioned along the liquid-phase mass transfer path from the lithium-containing high-salt water supply zone into the photothermal evaporation layer or from the photothermal evaporation layer into the lithium enrichment / lithium deposition collection zone, used to intercept multivalent interfering metal cations in the lithium-containing high-salt water and allow Li... + With continuous liquid phase migration; the lithium enrichment / precipitation collection zone is used to collect lithium-containing concentrate produced by shielding and interfacial evaporation concentration, or to convert lithium in the lithium-containing concentrate into lithium salt crystals, lithium salt precipitates or lithium-containing complex salts through continued evaporation, cooling crystallization and addition of lithium precipitation agent.

2. The solar evaporator based on a metal oxophosphate cluster shielding layer according to claim 1, characterized in that, The photothermal evaporation layer is a carbon-based photothermal material, conductive polymer photothermal material, metal nanomaterial, semiconductor photothermal material, MXene, ferrous metal oxide, plasmon material, or biomass carbonization material loaded on the liquid-outflow side of the metal oxophosphate cluster shielding layer. Specifically: the carbon-based photothermal material is at least one of carbon black, graphene, graphene oxide reduction products, carbon nanotubes, graphite powder, and porous carbon; the conductive polymer photothermal material is at least one of polypyrrole, polyaniline, polydopamine, polythiophene, and polyethylenedioxythiophene; the metal nanomaterial is at least one of gold nanoparticles, silver nanoparticles, copper nanoparticles, nickel nanoparticles, aluminum nanoparticles, and alloy nanoparticles; the semiconductor photothermal material is at least one of copper sulfide, molybdenum sulfide, tungsten sulfide, molybdenum disulfide, tungsten diselenide, titanium oxide, zinc oxide, copper oxide, and cuprous oxide; and the MXene is Ti3C2T. x Ti2CT x Nb2CT x V2CT x and Mo2TiC2T x At least one of them, wherein T x The surface end groups include -O, -OH, and -F; the ferrous metal oxide is at least one of iron(II,III) oxide, ferrous oxide, copper oxide, cuprous oxide, manganese oxide, cobalt oxide, nickel oxide, and titanium oxide; the plasmon material is at least one of gold nanorods, gold nanoshells, silver nanowires, silver nanocubes, copper sulfide nanoparticles, and aluminum nanostructures; the biomass carbonization material is at least one of carbonized wood, carbonized cotton cloth, carbonized cellulose paper, carbonized bamboo, carbonized sponge, carbonized straw, and carbonized coconut shell.

3. The solar evaporator based on a metal oxophosphate cluster shielding layer according to claim 1, characterized in that, The capillary liquid supply and heat insulation support layer is at least one of the following: cellulose paper, cotton cloth, wood, sponge, aerogel, foam plastic, porous ceramic, polyurethane foam, polyvinylidene fluoride membrane, polyacrylonitrile membrane, nylon membrane, glass fiber membrane and non-woven fabric, which have continuous hydrophilic capillary channels and heat insulation pore structure.

4. The solar evaporator based on a metal oxophosphate cluster shielding layer according to claim 1, characterized in that, The metal oxoate cluster shielding layer is a material layer containing metal oxoate clusters, and the metal oxoate clusters are fixed to the inner wall of the pores of the capillary liquid supply heat insulation support layer, the interlayer interface between the capillary liquid supply heat insulation support layer and the photothermal evaporation layer, the liquid inlet side surface of the photothermal evaporation layer, and the liquid inlet interface of the lithium enrichment / lithium deposition collection area. The metal oxophosphate cluster comprises a metal-oxygen cluster framework, oxygen-rich coordination sites, and an exchangeable counterion microenvironment, wherein: the oxygen-rich coordination sites are distributed on the metal-oxygen cluster framework, including terminal oxygen sites, bridging oxygen sites, hydroxyl oxygen sites, and deprotonated oxygen sites; the exchangeable counterion microenvironment includes Li + Na + K + NH4 + At least one of the quaternary ammonium salt cations.

5. The solar evaporator based on a metal oxoate cluster shielding layer according to claim 4, characterized in that, The metal oxoate clusters are niobium-oxygen clusters, tantalum-oxygen clusters, tungsten-oxygen clusters, molybdenum-oxygen clusters, vanadium-oxygen clusters, titanium-containing oxygen clusters, zirconium-containing oxygen clusters, or complex metal oxoate clusters.

6. The solar evaporator based on a metal oxoate cluster shielding layer according to claim 5, characterized in that, The niobium-oxygen clusters were prepared by the following method: Step 1: According to niobium element and OH - With a molar ratio of 1:(20~90), take niobium source and alkali source, and then take deionized water according to the ratio of niobium source to deionized water of 0.1 g:(5~30 mL). Then mix the source, alkali source and deionized water to form a reaction solution containing niobium oxygen coordination units. The niobium source is at least one of niobium pentoxide, niobic acid, and alkali metal niobate, wherein: the niobic acid is metaniobic acid or orthoniobic acid; the alkali metal niobate is at least one of sodium metaniobate, potassium metaniobate, sodium orthoniobate, potassium orthoniobate, sodium hexaniobate, and potassium hexaniobate; The alkaline source is potassium hydroxide, sodium hydroxide, or lithium hydroxide; Step 2: Transfer the reaction solution to the reaction vessel and seal it. Perform a hydrothermal reaction at 160~220℃ for 48~120 h to allow the niobium-containing oxygen coordination units to condense, rearrange, and multinucleate. After the reaction is complete, allow it to cool naturally to room temperature, stand, and collect the liquid-phase precursor containing niobium oxyacid acid clusters. Step 3: Add alcohol antisolvent to the liquid precursor containing niobium oxoate clusters according to the volume ratio of alcohol antisolvent to niobium oxoate clusters (1~5):1 to induce the precipitation of niobium oxoate clusters. After washing with alcohol / water mixture, dry to obtain multi-niobium oxoate clusters. The alcohol antisolvent is at least one of methanol, anhydrous ethanol and isopropanol; The alcohol / water mixture is prepared by mixing alcohol and deionized water in a volume ratio of (0.5~2):1, wherein the alcohol is anhydrous methanol, anhydrous ethanol or isopropanol.

7. The solar evaporator based on a metal oxophosphate cluster shielding layer according to claim 1, characterized in that, The lithium-containing high-salt water supply area is used to contain or continuously supply lithium-containing high-salt water, which contains Li. + Salt lake brine, geothermal brine, underground brine, oil and gas field brine, concentrated seawater, lithium-containing mineral leachate, lithium battery recovery salt waste liquid, or lithium-containing industrial high-salt wastewater containing monovalent coexisting cations and polyvalent interfering metal cations. The monovalent coexisting cation includes Na. + K + and NH 4+ ; The multivalent interfering metal cations include Mg 2+ Ca 2+ 、Sr 2+ Ba 2+ Fe 2+ Mn 2+ Co 2+ Ni 2+ Zn 2+ Al 3+ Fe 3+ Cr 3+ La 3+ Ce 3+ Pr 3+ and Nd 3+ .

8. A method for lithium enrichment in a solar evaporator based on a metal oxoate cluster shielding layer as described in any one of claims 1 to 7, characterized in that, The steps include the following: S1. Inject lithium-containing high-salt water into the lithium-containing high-salt water supply area and make the lithium-containing high-salt water contact the supply side of the capillary supply heat insulation support layer, so that the evaporation side of the photothermal evaporation layer is exposed to the environment and receives solar radiation or simulated solar radiation. S2. Under solar irradiation or simulated solar irradiation, the photothermal evaporation layer converts light energy into interfacial heat energy, forming a localized hot zone on the evaporation side and driving water to migrate and evaporate from the liquid supply side of the photothermal evaporation layer to the evaporation side along continuous hydrophilic capillary channels. This establishes an evaporation-induced continuous replenishment flux, a localized ion concentration zone generated by water removal, and temperature and concentration gradients distributed along the mass transfer path inside the evaporator. S3. Under the combined effects of continuous replenishment flux, local ion concentration zone, and temperature and concentration gradients, valence-interfering metal cations in lithium-containing high-salt water are preferentially retained at the oxygen-rich ion-regulated interface through multi-point oxygen coordination, charge compensation, counter-ion exchange, and ion association. + It remains in the liquid phase and migrates with the concentrate from the metal oxoate cluster shielding layer to the photothermal evaporation layer and the lithium enrichment / lithium deposition collection area; S4, containing Li + The liquid phase continues to evaporate and concentrate in the photothermal evaporation layer, and Li + Under the influence of lateral liquid flow, evaporation concentration gradient and circulating liquid supply, it migrates to the lithium enrichment / lithium precipitation collection area; S5. Directly collect the lithium-containing concentrate temporarily stored in the lithium enrichment / lithium precipitation collection area, or convert the lithium in the lithium-containing concentrate into lithium salt crystals, lithium salt precipitates or lithium-containing complex salts by continuing evaporation, cooling crystallization and adding lithium precipitation agent, and then collect the lithium salt crystals, lithium salt precipitates and lithium-containing complex salts; at the same time, collect the fresh water obtained by condensing the water vapor on the evaporation side of the photothermal evaporation layer.

9. The lithium enrichment method for a solar evaporator based on a metal oxoate cluster shielding layer according to claim 8, characterized in that, The evaporation methods of S1 to S5 are intermittent liquid supply evaporation, continuous liquid supply evaporation, circulating concentration evaporation, multi-stage series evaporation, or natural sunlight evaporation.

10. The lithium enrichment method for a solar evaporator based on a metal oxoate cluster shielding layer according to claim 8, characterized in that, Step S5 further includes: when the metal oxoate cluster shielding layer reaches the preset multivalent interfering metal cation loading, or when the evaporator flux drops to the preset value, the metal oxoate cluster shielding layer is brought into contact with the regeneration liquid to desorb the retained multivalent interfering metal cations. The regenerated solution is at least one of alkaline eluent, salt solution, complexing agent solution, and deionized water.

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