Ion extraction method and system based on redox electrolyte concentration ratio and application of ion extraction method and system

Abstract

The invention discloses an ion extraction method and system based on the redox electrolyte concentration ratio and application of the ion extraction method and system, and belongs to the field of resource recycling and seawater desalination.The extraction method comprises the steps that a battery electrode material, conductive carbon black and PVDF are mixed and evenly ground, and finally a first electrode is prepared; prussian blue, conductive carbon black and PVDF are mixed and uniformly ground, a second electrode is finally prepared, and a first mixed solution and a second mixed solution are prepared; and assembling the first electrode serving as a positive current collector material, the second electrode serving as a negative current collector material, the first mixed solution serving as a hot chamber electrolyte, the second mixed solution serving as a cold chamber electrolyte and an ion exchange membrane to form the ion extraction battery device. According to the invention, energy-saving water treatment can be realized.

Description

Technical Field

[0001] The present invention relates to the fields of resource recovery and seawater desalination, and in particular to an ion extraction method and system based on redox electrolyte concentration ratio and applications thereof. Background Art

[0002] The non-renewable nature of traditional fossil fuels (such as oil and coal) and their environmental impact (greenhouse gas emissions and air pollution) have prompted the global search for clean, sustainable energy solutions. Energy storage technology is crucial to promoting the development of renewable energy and electric vehicles. Lithium-ion batteries (LIBs) are widely used due to their high energy density, long cycle life, and low cost. By 2026, the global capacity of LIBs for hybrid and battery-only electric vehicles is expected to reach 440 GWh. However, lithium-ion batteries have a lifespan of only 3-5 years. The increasing raw material consumption in battery production is driving the prices of metals such as cobalt, lithium, and nickel on the international market. The concentrations of the major metals (Co, Li, Cu, Al, Fe, and Ni) in used lithium-ion batteries represent a significant proportion of waste, with some even exceeding their abundance in natural ores. To address environmental sustainability and safety risks, recycling used batteries not only alleviates resource constraints but also offers significant economic benefits while reducing environmental pollution.

[0003] Furthermore, the continued growth of the global population and rapid social development have exacerbated the global water crisis. Humanity's demand for usable water is increasing, and many regions are facing a severe shortage of freshwater resources. Seawater dominates the Earth's existing water resources, accounting for 97.5% of the world's water volume. To address the shortage of freshwater resources and the difficulty in meeting growing water demand, desalination is considered an effective solution to freshwater supply problems. However, the main technical challenge is how to cost-effectively remove various ions from aqueous solutions.

[0004] To date, the most widely used desalination methods include reverse osmosis (RO), distillation, electrodialysis, and capacitance. However, each of these methods presents various challenges that need to be addressed. Reverse osmosis (RO) desalination technology is difficult to implement on a large scale due to its high energy consumption (> 3 W h L⁻¹) and high cost (> 0.53 $ m⁻³). Capacitive deionization (CDI), redox flow deionization (RFD), and electrodialysis require a continuous energy supply, limiting their application in areas with limited electricity resources.

[0005] Currently, nature possesses an abundance of unused low-temperature heat (<100°C) from solar energy, geothermal energy, and industrial waste heat, yet this heat is often neglected and abandoned. Therefore, recycling this heat could help alleviate the severe global energy and environmental crises. Among the numerous technologies utilizing low-temperature thermal energy, thermal batteries have demonstrated significant advantages. Existing thermal battery systems are primarily classified into two types: solid and liquid. The Seebeck coefficient (Se) is a key parameter for determining thermoelectric conversion performance. Liquid thermal batteries have attracted considerable attention due to their Se values, which are one to two orders of magnitude higher than those of solid-state batteries. Despite this, the Se values of existing liquid thermal batteries remain relatively low, and their thermoelectric conversion efficiency falls far short of meeting the requirements for large-scale commercial applications. Current mainstream optimization strategies include adjusting the solvent composition and manipulating the redox electrolyte concentration ratio through the introduction of additives. While the former can increase the Se value, it results in a decrease in output current density, limiting the overall system power output. While the latter, while enhancing the Se value, also increases power density, it suffers from the limitation of insufficient precision in controlling the concentration ratio, hindering the full realization of thermoelectric performance. Therefore, there is an urgent need to develop an aqueous thermal battery system that can accurately control the concentration ratio of redox electrolytes in order to achieve efficient thermal energy conversion and energy-saving water treatment. Summary of the Invention

[0006] One of the purposes of the present invention is to provide an ion extraction method based on redox electrolyte concentration ratio to solve the problems of excessive energy consumption, heavy pollution and high cost in the prior art of waste battery recycling and seawater desalination.

[0007] The present invention is achieved through the following technical solution: an ion extraction method based on redox electrolyte concentration ratio, comprising the following steps: S100, mixing and uniformly grinding a battery electrode material, conductive carbon black and PVDF to prepare a first mixture, using NMP to dissolve the first mixture to prepare a first paste mixture, uniformly coating the first paste mixture on the surface of a hydrophobic, breathable conductive carrier, and vacuum drying to prepare a first electrode; S200, mixing and uniformly grinding Prussian blue, conductive carbon black and PVDF to prepare a second mixture, using NMP to dissolve the second mixture to prepare a second paste mixture, uniformly coating the second paste mixture with a binder on the surface of a hydrophobic, breathable conductive carrier, and vacuum drying to prepare a second electrode, and uniformly coating the second paste mixture with a binder on the bottom of a culture dish and vacuum drying to prepare Prussian blue particles; S300, mixing K4[Fe (CN)6]·3H2O, add it to deionized water and stir, stir until evenly, add the first paste mixture in S100, stir until evenly and filter to obtain a first mixed solution; S400, add [Fe(CN)6] and sodium chloride to deionized water and stir, stir until evenly, add the Prussian blue particles in S200, stir until evenly and filter to obtain a second mixed solution; S500, use the first electrode as the positive electrode current collector material, the second electrode as the negative electrode current collector material, the first mixed solution as the hot chamber electrolyte, and the second mixed solution as the cold chamber electrolyte; S600, assemble the positive electrode current collector material, the negative electrode current collector material, the hot chamber electrolyte, the cold chamber electrolyte and the ion exchange membrane into an ion extraction battery device, after the positive and negative electrodes of the battery device are connected, due to the different potentials of the redox reactions occurring at the two ends, a potential difference is generated, which powers the device and drives the ion extraction reaction.

[0008] Furthermore, the first mixture is prepared by uniformly mixing the battery electrode material, conductive carbon black and PVDF in a mass ratio of 8:1:1 and then grinding for 30 minutes.

[0009] Furthermore, the battery electrode materials include: LixMyPO4, LixTiyMzO12, LixMnyMzO4 and at least one of the above three materials modified, coated and doped, wherein M = at least one of Ni, Co, Mn, Al, Fe, Zr, Cu, Zn, Cr, and V elements.

[0010] Furthermore, the binder is a combination of one or more of nafion solution, polyvinylidene fluoride, hydroxymethyl cellulose, polytetrafluoroethylene, styrene-butadiene rubber emulsion, polyacrylic acid, polyacrylate and polyacrylonitrile.

[0011] Furthermore, the conductive carbon black is one or more combinations of graphite black, acetylene black, Cabot black, by-product carbon black, furnace black, carbon nanotubes and Ketjen black.

[0012] Furthermore, the cold chamber electrolyte includes: an auxiliary conductive additive for improving the conductive performance, the auxiliary conductive additive is: a combination of one or more of NaCl, NaF, Na2SO4, KCl, LiCl, LiF, Li2SO4, and KCl, and the added concentration of the auxiliary conductive additive in the electrolyte is relatively independently 1g / L to 36g / L.

[0013] Furthermore, the ion exchange membrane includes: an anion exchange membrane and a cation exchange membrane. The ion exchange membrane is placed between the positive and negative electrode electrolyte solutions and the salt solution to be treated for isolation; the lower anion / cation exchange membranes are placed alternately.

[0014] Furthermore, the cation exchange membrane includes a cation exchange membrane containing -COOH (carboxyl group), a cation exchange membrane containing -SO3H (sulfonic acid group), a fast ion conductor film, a sodium ion exchange membrane, a lithium ion exchange membrane, a potassium ion exchange membrane, a calcium ion exchange membrane, and a magnesium ion exchange membrane; preferably, one of the cation exchange membrane containing -SO3H (sulfonic acid group) and the lithium ion exchange membrane.

[0015] Furthermore, the anion exchange membrane includes an anion exchange membrane containing -NH2 (amino group), an anion exchange membrane containing -N(CH3)3OH (quaternary ammonium group), a chloride ion exchange membrane, a sulfate ion exchange membrane, and a nitrate ion exchange membrane; preferably, an ion exchange membrane containing -N(CH3)3OH (quaternary ammonium group) and a chloride ion exchange membrane.

[0016] Furthermore, the fast ion conductor film includes one of oxides, sulfides, two-dimensional materials, polymer composites, organic plastic crystals and inorganic ion exchange membranes. For example, garnet type (such as LLZO, ), perovskite type (such as LLTO, ), NASICON type (such as LATP, ), Argentatite type (such as )、LGPS type( ).

[0017] On the other hand, the present invention provides an ion extraction system based on the redox electrolyte concentration ratio, the ion extraction system includes a recovery unit and a desalination unit, wherein: the desalination unit is composed of a fluid battery based on a liquid flow structure, which includes the positive electrode current collector material, the negative electrode current collector material, the hot chamber electrolyte and the cold chamber electrolyte as described above in sequence, and the different solutions are divided into different chambers by ion exchange membranes to achieve different functions. The chambers are divided into single salt chambers, double salt chambers or multi-salt chambers, and each chamber in the chamber is separated alternately by anion and cation exchange membranes, and the structure is similar to "||hot end chamber||polysalt chamber||desalination chamber||cold end chamber||"; the solutions in each chamber are pumped by a circulation pump The ion extraction system is operated in a cycle, and the ion extraction system as a whole uses temperature-controllable hot water and cold water to heat and cool the hot end and cold end of the chamber system respectively to generate a temperature difference; the electrolyte in the cold and hot chamber storage tanks is the cold chamber electrolyte as described above, the electrolyte in the hot chamber storage tank is the hot chamber electrolyte as described above, and the activated substance in the cold chamber is Prussian blue; the recovery unit is separated from the hot chamber by a cation exchange membrane and from the desalination chamber by an anion exchange membrane, the redox electrolyte active material in the hot chamber storage tank directly contacts and reacts with the battery electrode material to be recovered, and releases the ions to be recovered, and then under the action of the internal potential, the ions to be recovered are enriched in the polysalt chamber through the cation exchange membrane.

[0018] On the other hand, the present invention also provides an application of an ion extraction method based on a redox electrolyte concentration ratio. The ion extraction method and system described above include the following applications: (1) application in industrial wastewater treatment; (2) application in domestic water purification; (3) application in thermoelectric conversion storage; (4) application in seawater desalination; and (5) application in waste battery recycling.

[0019] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0020] The present invention has developed a technology for enhancing ion extraction, electrode material recovery, and seawater desalination in a thermoelectrochemical flow battery by regulating the redox electrolyte concentration ratio. By precisely regulating the ion concentration ratio of the redox pair in the hot chamber and the cold chamber, the Se and output voltage of the aqueous thermal battery are maximized. At the same time, the thermal battery system is designed as a three-membrane four-chamber structure, and the internal electric field generated by the device is used to achieve dynamic internal charge balance, thereby simultaneously completing the desalination of seawater, the recycling of waste batteries, and the output of electrical energy. This technology provides a new solution to the problem of freshwater resource shortages in power-deficient areas. The present invention has the characteristics of low cost, high energy efficiency, and environmental friendliness. Its significantly improved output performance makes seawater desalination treatment valuable for industrial application, and has expansion potential in the fields of industrial wastewater treatment, domestic water purification, and thermoelectric conversion storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0022] Figure 1 This is a schematic diagram of the system provided in Example 1 of the present invention.

[0023] Figure 2 This is a cyclic voltammetry curve of the lithium iron phosphate electrode provided in Example 3 of the present invention.

[0024] Figure 3 This is a cyclic voltammogram of Prussian blue and the redox couple Fe(CN)64- / 3- provided in Example 3 of the present invention.

[0025] Figure 4 This is a short-circuit discharge current curve diagram under different temperature differences provided by Example 3 of the present invention.

[0026] Figure 5 This is a UV-visible absorption spectrum of the unreacted K4Fe(CN)6 solution provided in Example 3 of the present invention and the solution in the hot chamber liquid storage tank after reacting at a temperature difference of 50K for 10 hours.

[0027] Figure 6 UV-visible absorption spectra of the K3Fe(CN)6 solution before the reaction provided in Example 3 of the present invention and the K3Fe(CN)6 solution taken out after running at a temperature difference of 50 K for ten hours.

[0028] Figure 7 The open circuit voltage and Se diagram under different temperature differences provided by Example 3 of the present invention.

[0029] Figure 8 This is a curve diagram of current density versus voltage at different temperature differences provided by Example 3 of the present invention.

[0030] Figure 9 This is a schematic diagram of the device for desalination application of the thermal battery system of the present invention.

[0031] Figure 10 This is a graph showing real-time changes in output current density and seawater conductivity during seawater desalination by the thermal battery system provided in Example 3 of the present invention. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0033] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art to which this invention pertains. Although preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of this invention. All references mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related thereto. In the event of a conflict with any incorporated reference, the present specification controls. As used herein, the terms "including," "comprising," "having," "containing," and the like are open-ended, meaning to include, but not be limited to, the terms "a," "an," and "an" include plural references unless the context clearly indicates otherwise. It should be noted that the terms "first," "second," and the like are used solely for convenience of description and distinction and are not to be construed as indicating or implying relative importance. As used herein, the term "about" refers to a range of ±20% of the value that follows it. In some embodiments, the term "about" refers to a range of ±10% of the value that follows it. In some embodiments, the term "about" refers to a range of ±5% of the value that follows it.

[0034] Example 1

[0035] In this embodiment, a system is provided for achieving enhanced ion extraction, electrode material recovery, and seawater desalination in a thermoelectrochemical flow battery by regulating the redox electrolyte concentration ratio. Figure 1 Schematic diagram of the system in this embodiment is shown. The system includes:

[0036] Recovery unit and desalination unit.

[0037] The desalination unit is a flow battery based on a liquid flow structure, which includes a hot-end current collector, a hot-end electrolyte, a salt solution to be treated, a cold-end electrolyte, and a cold-end current collector. Different solutions are divided into different chambers by ion exchange membranes to achieve different functions. The chambers are divided into single-salt chambers, double-salt chambers, or multi-salt chambers according to different usage scenarios. Each chamber in the chamber is separated alternately by anion and cation exchange membranes. The chamber used in this experiment is a three-membrane four-chamber system with a structure similar to "||hot-end chamber||polysalt chamber||desalination chamber||cold-end chamber||";

[0038] The solutions in each chamber are circulated by a circulating pump. The system uses temperature-controlled hot and cold water to heat and cool the hot and cold ends of the chamber system, respectively, to create a temperature difference. The electrolyte in the hot and cold chamber reservoirs is composed of redox electrolyte active materials and an activating substance to maintain its purity. The activating substance in the hot chamber reservoir is the electrode material to be recycled, while the activating substance in the cold chamber is Prussian blue.

[0039] The recovery unit is separated from the hot chamber by a cation exchange membrane and from the desalination chamber by an anion exchange membrane. That is, the redox electrolyte active material in the hot chamber storage tank directly contacts and reacts with the battery electrode material to be recovered, releasing the ions to be recovered. Subsequently, under the action of the internal potential, the ions to be recovered are enriched in the polysalt chamber through the cation exchange membrane.

[0040] The redox electrolyte active material in the electrolyte of the cold and hot chamber storage tanks is at least one liquid electrolyte material with redox function, such as K3[Fe(CN)6] / K4[Fe(CN)6], Na3[Fe(CN)6] / Na4[Fe(CN)6], Li3[Fe(CN)6] / Li4[Fe(CN)6], FeCl3 / FeCl2 solution, Fe2(SO4)3 / FeSO4, Fe(NO3)3 / Fe(NO3)2, Zn / ZnCl2 solution, Zn / ZnSO4, Zn / Zn(NO3)2, Zn / Zn(CH3COO)2, TEMPO solution, VCl3 / VCl2 solution, I- / I3- solution, BTMAP-Fc solution, FcNCL or FcN2Br2 solution, with a set amount of substance ratio.

[0041] The activated material in the hot chamber liquid storage tank is formed by mixing the electrode material to be recycled, conductive carbon black and a binder and coating them on a hydrophobic and breathable conductive carrier; the electrode material to be recycled includes LixMyPO4, LixTiyMzO12, LixMnyMzO4 and at least one of the above three materials modified, coated and doped, wherein M = at least one of Ni, Co, Mn, Al, Fe, Zr, Cu, Zn, Cr, and V elements.

[0042] The activated material in the cold chamber liquid storage tank is formed by coating a mixture of Prussian blue, conductive carbon black and a binder on a hydrophobic and breathable conductive carrier.

[0043] The hydrophobic, breathable conductive carrier comprises one of hydrophobic carbon cloth and carbon paper; the binder comprises one of Nafion solution, polyvinylidene fluoride, hydroxymethyl cellulose, polytetrafluoroethylene, styrene-butadiene rubber latex, polyacrylic acid, polyacrylate, and polyacrylonitrile; and the conductive carbon black comprises one of graphite black, acetylene black, Cabot black, by-product carbon black, furnace black, carbon nanotubes, and Ketjen black. The coating ratio of the hot chamber activation material is as follows: when PVDF is used as the binder, the weight ratio of the electrode material, conductive carbon black, and binder is generally 6:2:2, 7:2:1, 8:1:1, or 9:0.5:0.5; when Nafion solution is used as the binder, the basic mixing ratio is 4mg:50μl, with a mass of 5mg of electrode material.

[0044] The hot end electrolyte is an aqueous solution of active substances, redox electrolyte materials, and auxiliary conductive additives. The type of auxiliary conductive additive is determined by the target ions of the desalination-recovery system, and generally ensures ion consistency with the solution to be treated in the adjacent chamber. If a cation exchange membrane is between the two, cation suppression is maintained; if an anion exchange membrane is between the two, anion consistency is maintained. The concentration of the redox electrolyte material in the electrolyte is preferably 30-80mM;

[0045] The cold-end electrolyte is an aqueous solution of active substances, redox electrolyte materials, and auxiliary conductive additives. The type of auxiliary conductive additive is determined by the target ions of the desalination-recovery system and generally ensures ion consistency with the solution to be treated in the adjacent chamber. If a cation exchange membrane is between the two, the cations are kept consistent; if an anion exchange membrane is between the two, the anions are kept consistent. The concentration of the redox electrolyte material in the electrolyte is preferably 30-80 mM.

[0046] The auxiliary conductive additive in the hot and cold chamber electrolytes is used to improve the solution's conductivity. It can be at least one of NaCl, NaF, Na2SO4, KCl, LiCl, LiF, Li2SO4, and KCl. The type of auxiliary conductive additive is determined by the target ions of the desalination and recovery system, and is generally used to ensure ionic consistency with the treated solution in the adjacent chamber. The concentration of the auxiliary conductive additive in the electrolyte is independently between 1g / L and 36g / L.

[0047] The salt solution to be treated includes one of LiCl solution, NaCl solution, NaF solution, Na2SO4 solution, KCl solution, LiF solution, Li2SO4 solution, CH3COOLi solution, CH3COONa solution, domestic sewage, industrial wastewater, seawater, and a solution containing heavy metal ions. The salt solution to be treated can also be placed in a single salt channel, a double salt channel, or a multi-salt channel as required, with the salt channels separated by ion exchange membranes. The general structure is similar to alternating "desalting / enrichment", such as "desalting / enrichment" or "desalting / enrichment / desalting" or "enrichment / desalting / enrichment" or "desalting / enrichment / desalting / enrichment", and so on.

[0048] The concentration of the salt solution to be treated is relatively independently 200 mg / L to 50 g / L, preferably 500 mg / L to 25 g / L, more preferably 3 to 10 g / L;

[0049] The current collector includes at least one of carbon cloth, hydrophobic carbon cloth, and an isotropic conductive carrier.

[0050] The ion exchange membrane includes an anion exchange membrane and a cation exchange membrane. The ion exchange membrane is placed between the positive and negative electrode electrolyte solutions and the salt solution to be treated for isolation. Generally, the anion / cation exchange membranes are placed alternately.

[0051] The cation exchange membrane includes a cation exchange membrane containing -COOH (carboxyl group), a cation exchange membrane containing -SO3H (sulfonic acid group), a fast ion conductor film, a sodium ion exchange membrane, a lithium ion exchange membrane, a potassium ion exchange membrane, a calcium ion exchange membrane, and a magnesium ion exchange membrane; preferably, one of the cation exchange membrane containing -SO3H (sulfonic acid group) and the lithium ion exchange membrane.

[0052] The anion exchange membrane includes an anion exchange membrane containing -NH2 (amino group), an anion exchange membrane containing -N(CH3)3OH (quaternary ammonium group), a chloride ion exchange membrane, a sulfate ion exchange membrane, and a nitrate ion exchange membrane; preferably, an ion exchange membrane containing -N(CH3)3OH (quaternary ammonium group) and a chloride ion exchange membrane.

[0053] The fast ion conductor film includes one of oxides, sulfides, two-dimensional materials, polymer composites, organic plastic crystals and inorganic ion exchange membranes. For example, garnet type (such as LLZO, ), perovskite type (such as LLTO, ), NASICON type (such as LATP, ), Argentatite type (such as )、LGPS type( ). Fast ion conductor films have stronger ion permeability, and only a single ion can pass through the membrane.

[0054] In this embodiment, the potential energy of the electrochemical reaction occurring at the positive and negative electrodes is different to form a voltage, so that the ions are driven by the internal electric field and the selective action of the ion exchange membrane to respectively achieve desalination, enrichment of target elements and production of additional products. The recovery part extracts the target elements in the recovered battery electrode material into the solution through the redox reaction between the redox electrolyte active material and the recovered battery electrode material. It is only necessary to continuously replace the recovered battery electrode material so that the redox electrolyte active material is always in a regenerated state, and then the ion extraction part can be carried out all the time. It is effective to add the battery electrode material to be recovered at any time period. The method of recycling battery electrode material, ion extraction and electrochemical desalination described in this embodiment can be applied to the fields of battery electrode material recovery, seawater desalination, and harmless treatment of toxic ions. The seawater desalination includes seawater desalination, and the toxic ions include heavy metal ions.

[0055] The working mechanism of the system disclosed in this embodiment is:

[0056] The reaction occurring at the positive electrode (hot chamber) is: RM-ne-=RMn+

[0057] The reaction at the negative electrode (cold chamber) is: RM+ne-=RMn-

[0058] Hot (positive) chamber reservoir: RMn++LiM=RMn-+M+Li+

[0059] Cold (negative) chamber reservoir: XNa++XRMn-+N=XRMn++NaxN

[0060] Wherein RM is the redox electrolyte active material used above, RMn+ is the corresponding oxidation state; RMn- is the corresponding reduction state; LiM is the positive electrode active material; and N is the active material used for the negative electrode.

[0061] The RMn- ions in the hot chamber are oxidized to RMn+ by heat, releasing electrons into the external circuit. The RMn+ ions in the cold chamber capture electrons and are reduced to RMn-. The hot chamber solution is pumped into the hot chamber reservoir by a peristaltic pump. Because the redox potential of LiM is lower than that of RMn+ / -, the activated species LiM reduces RMn+ to RMn−, itself oxidized to M, and releases lithium ions. The cold chamber solution is pumped into the cold chamber reservoir by a peristaltic pump. Because the redox potential of the activated species N is higher than that of RMn+ / -, the activated species N oxidizes RMn- to RMn+ and itself transforms into NaxN, maintaining the purity of the electrolyte. The activation species maintains the optimal redox couple concentration ratio in both the hot and cold chambers. Due to the temperature difference in the hot and cold chambers, the electrolyte undergoes oxidation and reduction reactions, respectively, generating an internal electric field within the chamber, directed from the hot chamber electrode to the cold chamber electrode. Under the action of the internal electric field, cations in the hot chamber pass through the cation exchange membrane into the salt-accumulating chamber, while anions in the desalination chamber pass through the anion exchange membrane into the salt-accumulating chamber. Finally, cations in the desalination chamber pass through the cation exchange membrane into the cold chamber. This achieves charge balance within each chamber, extracting ions from the salt liquid to be processed in the desalination chamber and the electrode material to be recovered. This system not only does not consume electricity during ion extraction, but actually provides external power.

[0062] Example 2

[0063] In this embodiment, a method for achieving enhanced ion extraction, electrode material recovery, and seawater desalination in a thermoelectrochemical flow battery by regulating the redox electrolyte concentration ratio is provided, comprising the following steps:

[0064] (1) Preparation of hot chamber active material: The battery electrode material to be recycled, carbon black, and PVDF were mixed in a certain mass ratio, uniformly ground for 30 minutes, and then dissolved in NMP to form a paste. A portion of the paste mixture was evenly coated on the surface of a hydrophobic, breathable conductive carrier and then vacuum dried at 60°C for 12 hours to prepare the hot end electrode.

[0065] (2) Preparation of cold chamber active material: The electrode material, carbon black, and PVDF were mixed in a certain mass ratio, uniformly ground for 30 minutes, and then dissolved in NMP to form a paste. A portion of the paste mixture was evenly coated on the surface of a hydrophobic, breathable conductive support and then vacuum dried at 60°C for 12 hours to prepare the cold end electrode.

[0066] (3) Prepare positive and negative electrode electrolytes: Dissolve the redox electrolyte active materials at a certain concentration ratio in a solution containing a corresponding auxiliary conductive agent, stir, and ultrasonicate, and add the active materials corresponding to steps (1) and (2) into the corresponding electrolyte to obtain positive and negative electrode electrolytes.

[0067] (4) Assembling the salt solution to be treated, the positive and negative electrolytes, the positive and negative current collecting electrode materials, and the ion exchange membrane into an ion extraction battery device;

[0068] (4) After the positive and negative electrodes are connected, the redox reactions at both ends have different potentials, which generates a potential difference, powering the device and driving the ion extraction reaction.

[0069] The ultrasonic treatment in step (1) is carried out at 40 to 100 kHz for 0.5 to 1.5 hours.

[0070] This embodiment adopts energy level matching and ion extraction technology, using the redox reaction between the thermosensitive redox electrolyte active material in the electrolyte and the battery electrode material to be recycled to directly extract the target ions from the waste battery; then uses electrodialysis coupling technology and air-liquid flow battery technology to integrate into a multifunctional device to achieve the purpose of target ion enrichment and seawater desalination.

[0071] Example 3

[0072] This embodiment discloses a device that utilizes a method for regulating the redox electrolyte concentration ratio to achieve enhanced ion extraction, electrode material recovery, and seawater desalination in a thermoelectrochemical flow battery. The device for recovering LiFePO4 and continuously desalinating the water includes the following operations:

[0073] (1) Preparation of current collector electrode

[0074] Use scissors to cut out circular hydrophobic carbon cloth with a diameter of 3.5 cm as the positive and negative electrode current collectors.

[0075] (2) Preparation of active substances in hot and cold chambers:

[0076] 1) Preparation of hot chamber active material: 5g of lithium iron phosphate, carbon black and PVDF were mixed in a mass ratio of 8:1:1, ground evenly for 30min and dissolved in NMP to form a paste. A portion of the paste was evenly coated on a graphite paper (1 × 1 cm −2 ) surface, then vacuum-dried at 60°C for 12 hours to prepare a lithium iron phosphate electrode. The remaining paste mixture was evenly coated on the bottom of a culture dish and vacuum-dried at 60°C for 12 hours. The dried mixture was then separated into lithium iron phosphate particles using a key.

[0077] 2) Preparation of cold chamber active material: 6.83 g of Prussian blue, carbon black, and PVDF were mixed in a mass ratio of 8:1:1, ground evenly for 30 min, and dissolved in NMP to form a paste. A portion of the paste mixture was evenly coated on a graphite paper (1 × 1 cm −2 ) surface, then vacuum-dried at 60°C for 12 hours to prepare a Prussian blue electrode. The remaining paste mixture was evenly coated on the bottom of a Petri dish and vacuum-dried at 60°C for 12 hours. The dried mixture was then separated into Prussian blue particles using a key.

[0078] (3) Preparation of electrolyte:

[0079] 3) Preparation of the hot chamber electrolyte: Weigh 1.68956 g of K₄[Fe(CN)₆]·3H₂O and add it to 20 ml of deionized water. After stirring for 30 minutes, add the lithium iron phosphate active material prepared in step 1. The resulting filtrate is a mixed solution with a concentration of 20 mM Fe₄[Fe(CN)₆], which serves as the hot chamber electrolyte.

[0080] 4) Preparation of cold chamber electrolyte: Weigh 1.31696 g of K₃[Fe(CN)₆] and 0.5 g of sodium chloride and add them to 20 ml of deionized water. After stirring for 30 minutes, add the Prussian blue active substance prepared in step 2. The resulting filtrate is a mixed solution of 20 mM K₃[Fe(CN)₆] and 5000 ppm of sodium chloride, which serves as the cold chamber electrolyte.

[0081] 5) Preparation of polysalt cavity electrolyte

[0082] The electrolyte of the polysalt chamber is 20 ml of deionized water; after stirring for 30 minutes, it is used as the electrolyte of the polysalt chamber;

[0083] (4) Preparation of salt solution to be treated

[0084] 6) Prepare a 5 g / L salt solution of 99% pure NaCl as the salt solution to be treated in the desalination chamber;

[0085] (5) Device preparation

[0086] 7) The circular carbon cloth prepared in (1) is used as the positive and negative current collector material, the 50 ml cylindrical container is used as the liquid storage tank of the hot and cold chambers, the hot chamber electrolyte obtained in step 3), the cold chamber electrolyte obtained in step 4, the salt solution to be treated obtained in step 5), an anion exchange membrane (diameter 3 cm), two cation exchange membranes (diameter 3 cm), 6 acrylic outer plates (10 cm × 10 cm × 1 cm), five of which have cavities (diameter 2.5 cm) according to Figure 9 The schematic structure is assembled into a four-channel desalination and lithium battery device; the device is fixed with studs and nuts, and each chamber is circulated using a small peristaltic pump;

[0087] The redox reaction formula of each part in this embodiment is:

[0088] Hot chamber: [Fe(CN)6] 4— e - = [Fe(CN)6] 3-

[0089] Cold chamber: [Fe(CN)6] 3- +e - = [Fe(CN)6] 4-

[0090] Hot chamber liquid reservoir: [Fe(CN)6] 3- +LiFePO4 = [Fe(CN)6] 4- +FePO4+Li +

[0091] Cold chamber reservoir:

[0092] 4Na + +4Fe(CN)6 4- +Fe4[Fe(CN)6]3→4Fe[(CN)]6 3- +Na4Fe4[Fe(CN)6]3

[0093] Figure 2 The cyclic voltammetry curves of the lithium iron phosphate electrode in this embodiment are shown when it is tested in K4Fe(CN)6 and K3Fe(CN)6 electrolytes in the voltage range of -0.1-0.6 V and a scan rate of 0.5 mV s-1. The CV test results show that lithium iron phosphate can reduce K3Fe(CN)6.

[0094] Figure 3The cyclic voltammetry curves obtained by testing the Prussian blue electrode in this embodiment in K4Fe(CN)6 and K3Fe(CN)6 electrolytes in the voltage range of -0.1-0.6 V and a scan rate of 0.5 mV s-1 are shown. The CV test results show that Prussian blue can oxidize K4Fe(CN)6.

[0095] Figure 4 The short-circuit discharge current curves under different temperature difference conditions in this embodiment are shown, indicating that after the activation material is added, the concentration ratio of Fe(CN)63- to Fe(CN)64- in the hot chamber and the cold chamber remains stable.

[0096] Figure 5 The UV-visible absorption spectra of the unreacted K4Fe(CN)6 solution in this embodiment and the solution in the hot chamber liquid storage tank after reacting for 10 hours at a temperature difference of 50K are shown. The test results show that the K4Fe(CN)6 solution in the hot chamber liquid storage tank remains pure under the action of lithium iron phosphate.

[0097] Figure 6 The UV-visible absorption spectra of the unreacted K3Fe(CN)6 solution in this example and the solution in the cold chamber reservoir after reacting at a temperature difference of 50K for 10 hours are shown. The test results show that the K3Fe(CN)6 solution in the cold chamber reservoir remains pure under the action of Prussian blue.

[0098] Figure 7 The open circuit voltage and Se of the thermal battery system in this embodiment at different temperature differences are shown. When the electrolyte concentration of the thermoelectric system is 0.2:0||0:0.2, the open circuit potential of the device increases from 217 mV at a temperature difference of 0 K to 355 mV at a temperature difference of 60 K, and the fitted Se value is 2.31 mV K-1.

[0099] Figure 8 The graph shows the current density versus voltage curve of the thermal battery system in this embodiment at different temperature differences, and the maximum power density increases from 0.90 W m-2 at a temperature difference of 0 K to 2.93 W m-2 at a temperature difference of 60 K.

[0100] Figure 10 A graph showing real-time changes in output current density and seawater conductivity during seawater desalination by the thermal battery system in this embodiment is shown.

[0101] The data above demonstrates that the addition of LiFePO₄ and Prussian blue activators effectively controls the purity of the redox electrolyte in the hot and cold chamber electrolytes, while simultaneously enriching and extracting the lithium from the LiFePO₄. Simultaneously, the conductivity of the seawater in the desalination chamber continues to decrease. Therefore, as long as the activating materials are continuously renewed during the reaction, the desalination reaction can be driven forward, allowing for the continuous recovery of lithium from waste battery materials.

[0102] Example 4

[0103] A device for achieving enhanced ion extraction, electrode material recovery, and seawater desalination in a thermoelectrochemical flow battery by regulating the redox electrolyte concentration ratio, wherein the device for recovering LiFePO4 and continuously desalinating the battery comprises the following operations:

[0104] (1) Preparation of current collector electrode

[0105] Use scissors to cut out circular hydrophobic carbon cloth with a diameter of 3.5 cm as the positive and negative electrode current collectors.

[0106] (2) Preparation of active substances in hot and cold chambers:

[0107] 1) Preparation of the hot chamber active material: 5g of lithium iron phosphate, carbon black, and PVDF were mixed in a mass ratio of 8:1:1, ground evenly for 30 minutes, and dissolved in NMP to form a paste. A portion of the paste was evenly coated on the surface of graphite paper (1 × 1 cm²) and then vacuum-dried at 60°C for 12 hours to prepare the lithium iron phosphate electrode. The remaining paste was evenly coated on the bottom of a culture dish and vacuum-dried at 60°C for 12 hours. The dried mixture was then separated into lithium iron phosphate particles using a key.

[0108] 2) Preparation of the cold chamber active material: 6.83 g of Prussian blue, carbon black, and PVDF were mixed in a mass ratio of 8:1:1, ground uniformly for 30 minutes, and dissolved in NMP to form a paste. A portion of the paste was evenly coated on the surface of graphite paper (1 × 1 cm²) and then vacuum-dried at 60°C for 12 hours to prepare a Prussian blue electrode. The remaining paste was evenly coated on the bottom of a petri dish and vacuum-dried at 60°C for 12 hours. The dried mixture was then separated into Prussian blue particles using a key.

[0109] (3) Preparation of electrolyte:

[0110] 3) Preparation of hot chamber electrolyte: Weigh 1.26717g K4[Fe(CN)6]·3H2O and 0.32924g K3[Fe(CN)6] and add them to 20ml deionized water. After stirring for 30 minutes, add the lithium iron phosphate active material prepared in step 1. The filtrate prepared is a mixed solution with a concentration of 15mM Fe4[Fe(CN)6] and 5mM K3[Fe(CN)6], which is used as the hot chamber electrolyte.

[0111] 4) Preparation of cold chamber electrolyte: Weigh 0.98772g K3[Fe(CN)6], 0.42239g K4[Fe(CN)6]·3H2O, and 0.5g sodium chloride and add them to 20ml deionized water. After stirring for 30 minutes, add the filtrate prepared from the Prussian blue active substance prepared in step 2 to form a mixed solution with a concentration of 15mM K3[Fe(CN)6], 5mM K4[Fe(CN)6], and 5000ppm sodium chloride. This mixture is used as the cold chamber electrolyte.

[0112] The concentration of electrolyte in the cold and hot chamber reservoirs is simply expressed as 0.15:0.05||0.05:0.15.

[0113] 5) Preparation of polysalt cavity electrolyte

[0114] The electrolyte of the polysalt chamber is 20 ml of deionized water; after stirring for 30 minutes, it is used as the electrolyte of the polysalt chamber;

[0115] (4) Preparation of salt solution to be treated

[0116] 6) Prepare a 5 g / L salt solution of 99% pure NaCl as the salt solution to be treated in the desalination chamber;

[0117] (5) Device preparation

[0118] 7) The circular carbon cloth prepared in (1) is used as the positive and negative current collector material, the 50 ml cylindrical container is used as the liquid storage tank of the hot and cold chambers, the hot chamber electrolyte obtained in step 3), the cold chamber electrolyte obtained in step 4, the salt solution to be treated obtained in step 5), an anion exchange membrane (diameter 3 cm), two cation exchange membranes (diameter 3 cm), 6 acrylic outer plates (10 cm × 10 cm × 1 cm), five of which have cavities (diameter 2.5 cm) according to Figure 9 The schematic structure is assembled into a four-channel desalination and lithium battery extraction device; the device is fixed with studs and nuts, and each chamber is circulated using a small peristaltic pump.

[0119] Example 5

[0120] A method for achieving enhanced ion extraction, electrode material recovery, and seawater desalination in a thermoelectrochemical flow battery by regulating the redox electrolyte concentration ratio, wherein the device for recovering LiFePO4 and continuously desalinating the water comprises the following operations:

[0121] (1) Preparation of current collector electrode

[0122] Use scissors to cut out circular hydrophobic carbon cloth with a diameter of 3.5 cm as the positive and negative electrode current collectors.

[0123] (2) Preparation of active substances in hot and cold chambers:

[0124] 1) Preparation of the hot chamber active material: 5g of lithium iron phosphate, carbon black, and PVDF were mixed in a mass ratio of 8:1:1, ground evenly for 30 minutes, and dissolved in NMP to form a paste. A portion of the paste was evenly coated on the surface of graphite paper (1 × 1 cm²) and then vacuum-dried at 60°C for 12 hours to prepare the lithium iron phosphate electrode. The remaining paste was evenly coated on the bottom of a culture dish and vacuum-dried at 60°C for 12 hours. The dried mixture was then separated into lithium iron phosphate particles using a key.

[0125] 2) Preparation of the cold chamber active material: 6.83 g of Prussian blue, carbon black, and PVDF were mixed in a mass ratio of 8:1:1, ground uniformly for 30 minutes, and dissolved in NMP to form a paste. A portion of the paste was evenly coated on the surface of graphite paper (1 × 1 cm²) and then vacuum-dried at 60°C for 12 hours to prepare a Prussian blue electrode. The remaining paste was evenly coated on the bottom of a petri dish and vacuum-dried at 60°C for 12 hours. The dried mixture was then separated into Prussian blue particles using a key.

[0126] (3) Preparation of electrolyte:

[0127] 3) Preparation of hot chamber electrolyte: Weigh 0.84478g K4[Fe(CN)6]·3H2O and 0.65848g K3[Fe(CN)6] and add them to 20ml deionized water. After stirring for 30 minutes, add the lithium iron phosphate active material prepared in step 1. The filtrate prepared is a mixed solution with a concentration of 10mM Fe4[Fe(CN)6] and 10mM K3[Fe(CN)6], which is used as the hot chamber electrolyte.

[0128] 4) Preparation of cold chamber electrolyte: Weigh 0.84478g K₄[Fe(CN)₆]·3H₂O, 0.65848g K₃[Fe(CN)₆], and 0.5g sodium chloride and add them to 20ml of deionized water. After stirring for 30 minutes, add the Prussian blue active substance prepared in step 1. The resulting filtrate is a mixed solution of 10mM K₃[Fe(CN)₆], 10mM K₄[Fe(CN)₆], and 5000ppm sodium chloride. This is used as the cold chamber electrolyte.

[0129] The concentration of electrolyte in the cold and hot chamber reservoirs is simply expressed as 0.1:0.1||0.1:0.1.

[0130] 5) Preparation of polysalt cavity electrolyte

[0131] The electrolyte of the polysalt chamber is 20 ml of deionized water; after stirring for 30 minutes, it is used as the electrolyte of the polysalt chamber;

[0132] (4) Preparation of salt solution to be treated

[0133] 6) Prepare a 5 g / L salt solution of 99% pure NaCl as the salt solution to be treated in the desalination chamber;

[0134] (5) Device preparation

[0135] 7) The circular carbon cloth prepared in (1) is used as the positive and negative current collector material, the 50 ml cylindrical container is used as the liquid storage tank of the hot and cold chambers, the hot chamber electrolyte obtained in step 3), the cold chamber electrolyte obtained in step 4, the salt solution to be treated obtained in step 5), an anion exchange membrane (diameter 3 cm), two cation exchange membranes (diameter 3 cm), 6 acrylic outer plates (10 cm × 10 cm × 1 cm), five of which have cavities (diameter 2.5 cm) according to Figure 9 The schematic structure is assembled into a four-channel desalination and lithium battery extraction device; the device is fixed with studs and nuts, and each chamber is circulated using a small peristaltic pump.

[0136] Example 6

[0137] A method for achieving enhanced ion extraction, electrode material recovery and seawater desalination in a thermoelectrochemical flow battery by regulating the redox electrolyte concentration ratio, which recovers lithium titanate and its doped Li x Ti y M z O 12 (M is one of the elements Ni, Co, Mn, Al, Fe, Zr, Cu, Zn, Cr, V) and the continuous desalination device includes the following operations:

[0138] (1) Preparation of current collector electrode

[0139] Use scissors to cut out circular hydrophobic carbon cloth with a diameter of 3.5 cm as the positive and negative electrode current collectors.

[0140] (2) Preparation of active substances in hot and cold chambers:

[0141] 1) Preparation of hot chamber active material: 5g of lithium titanate and its doped Li x Ti y M z O 12 (M is one of the elements Ni, Co, Mn, Al, Fe, Zr, Cu, Zn, Cr, V), 50 μl nafion solution, and 1000 μl isopropanol were poured into a cleaned 1 ml test tube; after ultrasonicating the test tube mixture for half an hour, the slurry was evenly coated on the hydrophobic carbon cloth; the hydrophobic carbon cloth coated with the slurry was placed in a 60 ° C oven, taken out after 8 hours, and cut out pieces with a diameter of (1 × 1 cm) with scissors. −2 ) Circular hydrophobic carbon cloth is used as the activation material in the hot chamber.

[0142] 2) Preparation of cold chamber active material: 6.83 g of Prussian blue, 50 μl of Nafion solution, and 1000 μl of isopropanol were poured into a cleaned 1 ml test tube. After ultrasonicating the mixture in the test tube for half an hour, the slurry was evenly coated on the hydrophobic carbon cloth. The hydrophobic carbon cloth coated with the slurry was placed in a 60°C oven for 8 hours and then cut into pieces with a diameter of (1 × 1 cm) using scissors. −2 ) Circular hydrophobic carbon cloth is used as the cold chamber activation material.

[0143] (3) Preparation of electrolyte:

[0144] 3) Preparation of hot chamber electrolyte: Weigh 40 mM TEMPO and add it to 20 ml of deionized water. After stirring for 30 minutes, add the lithium titanate active material prepared in step 1. The prepared mixed solution is used as the hot chamber electrolyte.

[0145] 4) Preparation of cold chamber electrolyte: Add 0.65848 g of K₃[Fe(CN)₆]₆ to 20 ml of deionized water; stir for 30 minutes, then add the Prussian blue active substance prepared in step 2. The resulting filtrate is a 20 mM K₃[Fe(CN)₆]₆ solution, which serves as the cold chamber electrolyte.

[0146] 5) Preparation of polysalt cavity electrolyte

[0147] The electrolyte of the polysalt chamber is 20 ml of deionized water; after stirring for 30 minutes, it is used as the electrolyte of the polysalt chamber;

[0148] (4) Preparation of salt solution to be treated

[0149] 6) NaF with a purity of 99% is prepared into a salt solution with a concentration of 3 g / L, which is used as the salt solution to be treated in the desalination chamber;

[0150] (5) Device preparation

[0151] 7) The circular carbon cloth prepared in (1) is used as the positive and negative current collector material, the 50 ml cylindrical container is used as the liquid storage tank of the hot and cold chambers, the hot chamber electrolyte obtained in step 3), the cold chamber electrolyte obtained in step 4, the salt solution to be treated obtained in step 5), an anion exchange membrane (diameter 3 cm), two cation exchange membranes (diameter 3 cm), 6 acrylic outer plates (10 cm × 10 cm × 1 cm), five of which have cavities (diameter 2.5 cm) according to Figure 9 The schematic structure is assembled into a four-channel desalination and lithium battery device; the device is fixed with studs and nuts, and each chamber is circulated using a small peristaltic pump;

[0152] The redox reaction formula of each part in this embodiment is:

[0153] Thermal chamber: XEMPO-Xe - =XTEMPO +

[0154] Cold chamber: 4TEMPO + +4e - = 4TEMPO

[0155] Hot Chamber Reservoir:

[0156] XTEMPO + +Li4Ti5O 12 = XTEMPO+Li 4-x Ti5O 12 +XLi +

[0157] Cold chamber reservoir:

[0158] 4Na + +4TEMPO+Fe4[Fe(CN)6]3 = 4TEMPO + +Na4Fe4[Fe(CN)6]3.

[0159] After the device in Example 6 was assembled, an electrochemical performance test was performed. The conductivity of the solution was tested using a conductivity meter to obtain the removal effects of enriched Li and Na, as shown in Table 1.

[0160] Table 1. Electrochemical performance test table of Example 6

[0161] Salt-rich cavity Desalination chamber Initial conductivity (mS / cm) 0.05 5.74 Conductivity after 1.5h (mS / cm) 4.56 1

[0162] Example 7

[0163] A method for achieving enhanced ion extraction, electrode material recovery, and seawater desalination in a thermoelectrochemical flow battery by regulating the redox electrolyte concentration ratio. The device for recovering lithium manganese oxide and its doped LixMnyMzO4 (M is one of the elements Ni, Co, Mn, Al, Fe, Zr, Cu, Zn, Cr, and V) and continuously desalting comprises the following operations:

[0164] (1) Preparation of current collector electrode

[0165] Use scissors to cut out carbon paper with a diameter of 3.5 cm as the positive and negative electrode current collectors.

[0166] (2) Preparation of active substances in hot and cold chambers:

[0167] 1) Preparation of the hot chamber active material: 5g of lithium manganese oxide (LMO) and its doped LixMnyMzO4 (M is one of the following elements: Ni, Co, Mn, Al, Fe, Zr, Cu, Zn, Cr, or V), carbon black, and PTFE were mixed in a mass ratio of 8:1:1. The mixture was uniformly ground for 30 minutes and then dissolved in NMP to form a paste. A portion of the paste was evenly coated on a piece of carbon paper (1 × 1 cm²) and then vacuum-dried at 60°C for 12 hours to prepare the LMO electrode.

[0168] 2) Preparation of the cold chamber active material: 6.83 g of Prussian blue, carbon black, and PTFE were mixed in a mass ratio of 8:1:1, ground evenly for 30 minutes, and dissolved in NMP to form a paste. A portion of the paste was evenly coated on the surface of a piece of carbon paper (1 × 1 cm²) and then vacuum-dried at 60°C for 12 hours to prepare a Prussian blue electrode. The remaining paste was evenly coated on the bottom of a petri dish and vacuum-dried at 60°C for 12 hours. The dried mixture was then separated into Prussian blue particles using a key.

[0169] (3) Preparation of electrolyte:

[0170] 3) Preparation of hot chamber electrolyte: 1-ethyl-3-methylimidazolium iodide and I2 were dissolved in 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide and added to 20 ml of deionized water. After stirring for 30 minutes, the lithium titanate active material prepared in step 1 was added. The prepared mixed solution was used as the hot chamber electrolyte.

[0171] 4) Preparation of cold chamber electrolyte: Dissolve 1-ethyl-3-methylimidazolium iodide and I2 in 1-ethyl-3-methylimidazole bis(trifluoromethanesulfonyl)imide and 0.5g sodium chloride, and add to 20ml of deionized water. After stirring for 30 minutes, add the Prussian blue active substance prepared in step 2. This serves as the cold chamber electrolyte.

[0172] 5) Preparation of polysalt cavity electrolyte

[0173] The electrolyte of the polysalt chamber is 20 ml of deionized water; after stirring for 30 minutes, it is used as the electrolyte of the polysalt chamber;

[0174] (4) Preparation of salt solution to be treated

[0175] 6) Prepare a 6 g / L salt solution of 99% pure NaCl as the salt solution to be treated in the desalination chamber;

[0176] (5) Device preparation

[0177] 7) The circular carbon cloth prepared in (1) is used as the positive and negative current collector material, a 50 ml cylindrical container is used as the liquid storage tank of the hot and cold chambers, the hot chamber electrolyte obtained in step 3), the cold chamber electrolyte obtained in step 4), the salt solution to be treated obtained in step 5), a piece of anion exchange membrane (3 cm in diameter), a piece of Na1+xZr2Si2-xPxO12 fast sodium ion conductor film (3 cm in diameter) are placed between the desalination chamber and the cold chamber, and a piece of The fast lithium ion conductor film is placed between the polysalt chamber and the hot chamber. Six acrylic outer plates (10cm×10cm×1cm) are placed, and five of them have cavities (2.5cm in diameter). Figure 9 The schematic structure is assembled into a four-channel desalination and lithium battery extraction device; the device is fixed with studs and nuts, and each chamber is circulated using a small peristaltic pump.

[0178] After the device in this embodiment was assembled, the electrochemical performance test was carried out. The conductivity of the solution was tested using a conductivity meter to obtain the removal effect of enriched Li and Na. The results are shown in Table 2 below:

[0179] Table 2. Electrochemical performance test table of Example 7

[0180] Salt-rich cavity Desalination chamber Initial conductivity (mS / cm) 0.05 10.87 Conductivity after 3 hours (mS / cm) 8.64 1

[0181] Comparing the results of Examples 3, 4 and 5, it can be seen that by regulating the surroundings of the hot electrode and the cold electrode and The concentration ratio of Fe(CN)63− to Fe(CN)64− around the hot electrode and cold electrode was adjusted to the optimal state, that is, the hot electrode was surrounded by a pure K4Fe(CN)6 solution and the cold electrode was surrounded by a pure K3Fe(CN)6 solution, as in Example 1, achieving the maximum improvement in Se, open-circuit voltage, and maximum output power of the designed thermal battery system.

[0182] The data obtained in Example 6 show that the ionic conductivity of the NaF solution in the desalination chamber decreases, indicating that the NaF concentration is decreasing, thereby achieving seawater desalination.

[0183] The data obtained in Example 7 show that the ionic conductivity of the NaCl solution to be treated in the desalination chamber decreases, indicating that the concentration of NaCl is decreasing. The Na+ and Cl- therein pass through the fast sodium ion conductor film and the anion exchange membrane, respectively, into the hot chamber and the polysalt chamber, while the conductivity of the LiCl solution in the polysalt chamber increases. This indicates that the solution in the polysalt chamber accepts Li+ from the hot chamber and Cl- from the desalination chamber, increasing the LiCl concentration and enriching lithium in the polysalt chamber, thereby recovering the Li element from the waste battery material. This achieves the recovery of lithium ions from waste batteries and the desalination of seawater.

[0184] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An ion extraction method based on redox electrolyte concentration ratio, characterized in that: The ion extraction method comprises: S100, mixing and uniformly grinding the battery electrode material, conductive carbon black and PVDF to prepare a first mixture, Dissolve the first mixture using NMP to prepare a first paste-like mixture, Uniformly coating the first paste mixture on the surface of a hydrophobic and breathable conductive support, and vacuum drying the mixture to prepare a first electrode; S200, mixing Prussian blue, conductive carbon black and PVDF and uniformly grinding them to prepare a second mixture, The second mixture is dissolved in NMP to prepare a second paste mixture. The second paste mixture is mixed with a binder and evenly coated on the surface of the hydrophobic and breathable conductive carrier, and vacuum dried to prepare a second electrode. The second paste mixture mixed with the binder is evenly coated on the bottom of a culture dish and vacuum dried to prepare Prussian blue particles; S300, adding K4[Fe(CN)6]·3H2O to deionized water and stirring, adding the first paste mixture in S100 after stirring evenly, stirring evenly and filtering to obtain a first mixed solution; S400, adding [Fe(CN)6] and sodium chloride to deionized water, stirring, stirring evenly, adding the Prussian blue particles in S200, stirring evenly and filtering to obtain a second mixed solution; S500, using the first electrode as a positive electrode current collector material, and using the second electrode as a negative electrode current collector material, using the first mixed solution as a hot chamber electrolyte and the second mixed solution as a cold chamber electrolyte; S600: Assemble the positive electrode current collector material, the negative electrode current collector material, the hot chamber electrolyte, the cold chamber electrolyte and the ion exchange membrane into an ion extraction battery device. After the positive and negative electrodes of the battery device are connected, a potential difference is generated due to the different potentials of the redox reactions occurring at both ends, which powers the device and drives the ion extraction reaction.

2. The ion extraction method based on redox electrolyte concentration ratio according to claim 1, characterized in that: The first mixture is prepared by uniformly mixing the battery electrode material, conductive carbon black and PVDF in a mass ratio of 8:1:1 and then grinding for 30 minutes.

3. The ion extraction method based on redox electrolyte concentration ratio according to claim 1, characterized in that: The battery electrode materials include: LixMyPO4, LixTiyMzO12, LixMnyMzO4 and at least one of the above three materials modified, coated and doped. Wherein M = at least one of Ni, Co, Mn, Al, Fe, Zr, Cu, Zn, Cr, and V.

4. The ion extraction method based on redox electrolyte concentration ratio according to claim 1, characterized in that: The binder is a combination of one or more of nafion solution, polyvinylidene fluoride, hydroxymethyl cellulose, polytetrafluoroethylene, styrene-butadiene rubber emulsion, polyacrylic acid, polyacrylate and polyacrylonitrile.

5. The ion extraction method based on redox electrolyte concentration ratio according to claim 1, characterized in that: The conductive carbon black is one or more combinations of graphite black, acetylene black, Cabot black, by-product carbon black, furnace black, carbon nanotubes and Ketjen black.

6. The ion extraction method based on redox electrolyte concentration ratio according to claim 1, characterized in that: The cold chamber electrolyte includes: an auxiliary conductive additive for improving the conductive performance, the auxiliary conductive additive is: A combination of one or more of NaCl, NaF, Na2SO4, KCl, LiCl, LiF, Li2SO4, KCl, The addition concentration of the auxiliary conductive additive in the electrolyte is relatively independent and ranges from 1 g / L to 36 g / L.

7. The ion extraction method based on redox electrolyte concentration ratio according to claim 1, characterized in that: The ion exchange membrane includes: an anion exchange membrane and a cation exchange membrane. The ion exchange membrane is placed between the positive and negative electrode electrolyte solutions and the salt solution to be treated for isolation. The lower anion / cation exchange membranes are placed alternately.

8. An ion extraction system based on redox electrolyte concentration ratio, characterized in that: The ion extraction system includes a recovery unit and a desalination unit, wherein: The desalination unit is composed of a flow battery based on a liquid flow structure. The electrolyte comprises, in sequence, a positive electrode current collector material, a negative electrode current collector material, a hot chamber electrolyte, and a cold chamber electrolyte according to any one of claims 1 to 7, Different solutions are divided into different chambers by ion exchange membranes to achieve different functions. The chamber is divided into a single salt chamber, a double salt chamber or a multi-salt chamber. Each chamber in the chamber is separated alternately by anion and cation exchange membranes, and the solutions in each chamber are circulated by a circulation pump. The ion extraction system as a whole uses temperature-controlled hot water and cold water to heat and cool the hot end and cold end of the chamber system respectively to generate a temperature difference; The electrolyte in the cold and hot chamber liquid storage tanks is the cold chamber electrolyte according to any one of claims 1 to 7, the electrolyte in the hot chamber liquid storage tank is the hot chamber electrolyte according to any one of claims 1 to 7, and the activating substance in the cold chamber is Prussian blue; The recovery unit is separated from the hot chamber by a cation exchange membrane and from the desalination chamber by an anion exchange membrane. The redox electrolyte active material in the hot chamber storage tank directly contacts and reacts with the battery electrode material to be recovered, releasing the ions to be recovered. Subsequently, under the action of the internal potential, the ions to be recovered are enriched in the polysalt chamber through the cation exchange membrane.

9. An application of an ion extraction method based on redox electrolyte concentration ratio, characterized in that: The ion extraction method includes the following applications: (1) Application in industrial wastewater treatment; (2) Application in domestic water purification; (3) Application in thermoelectric conversion and storage; (4) Application in seawater desalination; (5) Application in recycling of waste batteries.

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