A method and application of targeted redox-driven electrochemical desalination, ion extraction, and electrode material recycling

Abstract

The application belongs to the field of new energy materials and electrochemical desalination technology, and discloses a method and application of targeted oxidation-reduction driven electrochemical desalination, ion extraction and electrode material recovery. Oxidation-reduction electrochemical reaction is generated by a liquid flow electrode, so that positive and negative ions in a salt solution are captured and desalted by being constrained by an electric field and passing through a corresponding ion exchange membrane. At the same time, the electrolyte loses active substances due to participating in the desalination reaction, and then acts as a "catalyst" in the recovery step and reacts with the electrode material. In the process of repairing or recycling the electrode material, the desalination activity is restored. The liquid flow electrolyte can be continuously regenerated and supplemented, and long-term continuous desalination and electrode material recovery can be realized. The method is suitable for factory scale production, and can be applied to industrial wastewater treatment, domestic water purification, energy conversion and storage, and other fields requiring electric energy.

Description

Technical Field

[0001] This invention belongs to the fields of novel energy materials technology and electrochemical desalination technology, and specifically relates to a method and application of targeted redox-driven electrochemical desalination, ion extraction, and electrode material recovery. Background Technology

[0002] Lithium-ion batteries (LIBs) have been widely used due to their advantages of high energy density, long cycle life, and low cost. It is projected that by 2024, the demand for LIBs in the automotive industry will reach $221 billion, and by 2026, the annual global energy capacity of LIBs for hybrid and battery electric vehicles is expected to reach 440 GWh. The lifespan of lithium-ion batteries is approximately 3-5 years. Statistics show that in 2020 alone, the number and weight of discarded LIBs in China exceeded 25 billion units and 500,000 tons. Proper disposal of discarded batteries is crucial for environmental sustainability and safety. Currently, due to the imbalance between supply and demand in battery production, the prices of metals such as cobalt, lithium, and nickel in the international market are rising year by year. The enrichment levels of various major metals (Co, Li, Cu, Al, Fe, Ni) in discarded lithium-ion batteries are considerable, some even exceeding their abundance in natural ores. Therefore, recycling discarded batteries can not only alleviate resource shortages but also bring significant economic benefits while reducing environmental pollution.

[0003] Furthermore, with global climate change, fluctuating precipitation distribution, population growth, and further urbanization, human demand for usable water is increasing daily, making water scarcity a prominent global issue. In 1995, the Middle East was the most water-scarce region globally. However, by 2025, this area has expanded further, with water extraction rates increasing by more than ten percentage points. A report published by the World Resources Institute in August 2015 indicated that Middle Eastern countries will face water depletion by 2040. The Middle East and North Africa suffer economic losses of up to $21 billion annually due to insufficient water and sanitation facilities. Therefore, developing energy-efficient, environmentally friendly, and sustainable water purification technologies is particularly urgent.

[0004] Faced with the energy and freshwater crisis, current recycling and desalination technologies suffer from high energy consumption and unsustainability. The energy and chemicals (acids, oxidizing agents) consumed in pyrometallurgical and hydrometallurgical recycling processes lead to significant greenhouse gas emissions and secondary waste, causing additional environmental problems. Furthermore, much of the value of the cathode is lost in these destructive recycling processes. Especially for lithium-ion batteries that do not contain expensive metals (e.g., LiFePO4), the economic value of their recycled elements is insufficient to offset the high costs of pyrometallurgical and hydrometallurgical recycling processes. Therefore, a gentler and more efficient method that significantly reduces energy costs and waste generation is needed. Reverse osmosis membranes and distillation are the most mature desalination technologies. However, they are energy-intensive and expensive. Reverse osmosis requires high water pressure to drive the desalination process, and its regeneration process is expensive and generates secondary pollution; distillation requires significant thermal energy. Therefore, it is necessary to propose a new flow battery recycling-desalination method that combines electrode material recycling with seawater desalination to address these issues. Summary of the Invention

[0005] In order to overcome the shortcomings and deficiencies of the prior art, the primary objective of this invention is to provide a system for targeted redox-driven electrochemical desalination, ion extraction, and electrode material recovery.

[0006] Another objective of this invention is to provide a targeted redox-driven electrochemical desalination, ion extraction, and electrode material recovery method. A redox electrochemical reaction occurs through a liquid flow electrode, causing positive and negative ions in the salt solution to be trapped by an electric field and pass through their corresponding ion exchange membranes, thus being captured and desalinated. Simultaneously, substances in the electrolyte that have lost their activity due to the desalination reaction act as new redox mediators, reacting with the electrode materials as "catalysts" in the recovery process. During the repair or recycling of the electrode materials, they regain their desalination activity. This allows the liquid flow electrolyte to be continuously regenerated and replenished, enabling long-term continuous desalination and electrode material recovery. This is of great significance for addressing the current problems of excessive energy consumption, heavy pollution, and high costs in waste battery recycling and seawater desalination. Therefore, providing a gentle, environmentally friendly, and low-energy-consumption technology for the direct recovery of electrode materials and continuous seawater desalination is crucial.

[0007] The objective of this invention is achieved through the following solution:

[0008] A system for targeted redox-driven electrochemical desalination, ion extraction, and electrode material recovery includes a recovery unit and a desalination unit, wherein:

[0009] The recycling unit is a storage tank containing the battery electrode material to be recycled and a filter membrane; the filter membrane divides the storage tank into upper and lower layers, with the battery electrode material to be recycled placed in the upper layer; the filter membrane allows liquid to pass through but traps solid particles, thus achieving solid-liquid separation in the recycling unit.

[0010] The desalination unit is a fluid battery based on a liquid flow structure, consisting of a positive electrode current collector, a positive electrode electrolyte, a brine solution to be treated, a negative electrode electrolyte, and a negative electrode current collector. Different solutions are separated into different chambers by ion exchange membranes to achieve different functions. The general structure is similar to "||positive electrode electrolyte||brine solution to be treated||negative electrode electrolyte||". The solutions in each chamber are circulated by a circulation pump.

[0011] The recovery unit is connected to the negative electrode electrolyte of the desalination unit via a circulation pump and pipelines, forming a circulation system. That is, the negative electrode electrolyte is pumped out from the desalination unit, enters the upper layer of the recovery unit, and directly contacts and reacts with the electrode material of the battery to be recovered. Then it is filtered through a filter membrane and enters the lower layer of the recovery unit, where it achieves solid-liquid separation with the electrode material of the battery to be recovered. Finally, it flows back to the negative electrode electrolyte of the desalination unit.

[0012] The battery electrode materials to be recycled include LiFePO4, LiCoO2, LiNiO2, and LiNi. 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.8 Co 0.1 Al 0.1 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.6 Co 0.2 Al 0.2 O2, LiNi 0.5 Co 0.3 Mn 0.2 O2, LiN i0.5 Co 0.3 Al 0.2 O2, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiNi 1 / 3 Co 1 / 3 Al 1 / 3O2, Na3MnTi(PO4)3, Na3V2(PO4)3, LiTMO2, LiTMPO4, NaTMO2, NaTMPO4, and at least one of the modified materials derived from the above 17 materials, wherein TM = at least one of Ni, Co, Mn, Ti, Al, Fe, Zr, Cu, Zn, Cr, V, and the modified materials are characterized by bulk doping or surface doping or surface coating of small amounts of elements (F, Si, Ti, Zr, Al, N, S, P, V, etc.) (C, Al2O3, LiAlO2, Li3PO4, Co3O4, ZrO, Mg2TiO4, etc.); the electrode material is the main raw material for recovering the target element and is a key material for promoting the continuous operation of this invention.

[0013] The filter membrane is at least one of glass fiber membrane, filter paper, nylon filter membrane, polytetrafluoroethylene filter membrane, mixed cellulose filter membrane, polyethersulfone filter membrane, polypropylene filter membrane, and polyvinylidene fluoride filter membrane; the filter membrane has a particle size cutoff of 0.1 to 50 μm, preferably ≤0.4 μm.

[0014] The positive electrode current collector is formed by coating a mixture of catalyst, conductive carbon black, and binder onto a hydrophobic and breathable conductive carrier; wherein the hydrophobic and breathable conductive carrier includes one of the following: hydrophobic carbon cloth, foamed metal coated with a hydrophobic agent (such as polyethylene, polytetrafluoroethylene, etc.); the catalyst includes one of the following: Ir / C, Pt / C, Ru / C, other noble metal catalysts (palladium, rhodium, silver, gold, etc.), non-noble metal catalysts (such as nickel-based, cobalt-based, iron-based, etc.), and non-metallic catalysts (such as carbon-based, nitrogen-based, etc.); the binder is Nafion solution, polyvinylidene fluoride (PVDF) The catalyst comprises one of PVDF, hydroxymethyl cellulose (CMC), polytetrafluoroethylene, styrene-butadiene rubber latex, polyacrylic acid, polyacrylate, and polyacrylonitrile; the conductive carbon black is one of graphite black, acetylene black, Cabot black, carbon nanotubes, and Ketjen black; the coating ratio of the catalyst, conductive carbon black, and binder is as follows: if commercially available carbon-coated catalysts such as Ir / C, Pt / C, and Ru / C are used, no additional conductive carbon black is required. When using Nafion solution as a binder, the basic mixing ratio is 5 mg: 50 μl. The actual mixing ratio can be scaled up or down as needed. If other non-carbon-based catalysts are used, the mass mixing ratio of catalyst, conductive carbon black, and binder is generally 6:2:2, 7:2:1, 8:1:1, or 9:0.5:0.5; if a carbon-based catalyst is used, the amount originally added as conductive carbon black is replaced by the catalyst.

[0015] The positive electrode electrolyte is an aqueous solution of the positive electrode active material and auxiliary conductive additives, wherein the positive electrode active material is pure oxygen or air. The type of auxiliary conductive additive is determined by the target of the desalination-recovery system, and generally maintains ionic consistency with the brine to be treated in the adjacent chamber. If the two are separated by anion exchange membranes, anion consistency is maintained; if separated by cation exchange membranes, cation consistency is maintained.

[0016] The negative electrode electrolyte is a mixed aqueous solution of a negative electrode active material and an auxiliary conductive additive, wherein the negative electrode active material is a material with redox activity, including but not limited to [Fe(CN)6]. 3- [Fe(CN)6] 4- , FeCl3, FeCl2, ZnCl2, TEMPO, VCl3, VCl2, I - Solution, I 3- The active material comprises at least one of the following: a solution, BTMAP-Fc, FcNCl, or FcN2Br2, which possesses redox function; the concentration of the negative electrode active material in the negative electrode electrolyte is ≥10 mM. The type of auxiliary conductive additive is determined by the target of the desalination-recovery system, and generally maintains ionic consistency with the brine to be treated in the adjacent chamber. If the two are separated by anion exchange membranes, anion consistency is maintained; if separated by cation exchange membranes, cation consistency is maintained.

[0017] The auxiliary conductive additives in both the negative and positive electrode electrolytes are relatively independently selected from at least one of NaCl, NaF, Na₂SO₄, KCl, LiCl, LiF, Li₂SO₄, and KCl, used to improve the conductivity of the solution. For ion consistency, the type of auxiliary conductive agent can be determined based on the types of anions or cations exchanged between the electrolyte and the solutions in adjacent chambers. The concentration of the auxiliary conductive agent in both the positive and negative electrode electrolytes is relatively independently between 1 g / L and 36 g / L.

[0018] Preferably, when the electrode material of the battery to be recycled is LiFePO4, the negative electrode active material is at least one of Li4Fe(CN)6, BTMAP-Fc, FcNCl, and FcN2Br2, and the concentration of the negative electrode active material in the negative electrode electrolyte is 30-80 mM.

[0019] Preferably, when the electrode material of the battery to be recycled is LiCoO2, the negative electrode active material is TEMPO, and the concentration of the negative electrode active material in the negative electrode electrolyte is 10-60 mM.

[0020] Preferably, when the electrode material of the battery to be recycled is LiNiO2 or LiNi 0.8 Co 0.1 Mn0.1 O2, LiNi 0.8 Co 0.1 Al 0.1 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.6 Co 0.2 Al 0.2 O2, LiNi 0.5 Co 0.3 Mn 0.2 O2, LiN i0.5 Co 0.3 Al 0.2 O2, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiNi 1 / 3 Co 1 / 3 Al 1 / 3 When O2, LiTMO2 or LiTMPO4 is used, the negative electrode active material is I. - / I3 - The concentration of the negative electrode active material in the negative electrode electrolyte is 20–100 mM.

[0021] Preferably, when the electrode material of the battery to be recycled is Na3MnTi(PO4)3 (Na3V2(PO4)3, NaTMO2 and NaTMPO4 (TM is a combination of transition metal elements, such as a unit, binary or multi-component combination of Ni, Co, Mn, Ti, Al, Fe, Zr, Cu, Zn, Cr, V), the negative electrode active material is Na4Fe(CN)6, and the concentration of the negative electrode active material in the negative electrode electrolyte is 30-80 mM;

[0022] The salt solution to be treated can be of two or more types, depending on the requirements. That is, the salt solution to be treated can be placed in a single salt channel, a double salt channel, or a multi-salt channel, with the salt channels separated by an ion exchange membrane. The general structure is similar to "||positive electrolyte||salt solution to be treated 1||salt solution to be treated 2||negative electrolyte||" or "||positive electrolyte||salt solution to be treated 1||salt solution to be treated 2||salt solution to be treated 3||negative electrolyte||" or "||positive electrolyte||salt solution to be treated 1||salt solution to be treated 2||……||salt solution to be treated n||negative electrolyte||", where n represents the number of salt channels. When there are two or more salt channels, the desalination unit processes the salt channels in alternating "desalination / enrichment" cycles, such as "desalination / enrichment" or "desalination / enrichment / desalination" or "enrichment / desalination / enrichment" or "desalination / enrichment / desalination / enrichment," and so on. The system diagrams for single and dual salt channels are shown below. Figure 1 and Figure 2 As shown.

[0023] Each salt channel contains a relatively independent salt solution selected from one of the following: LiCl solution, NaCl solution, NaF solution, Na2SO4 solution, KCl solution, LiF solution, Li2SO4 solution, CH3COOLi solution, CH3COONa solution, domestic sewage, industrial wastewater, seawater, or a solution containing heavy metal ions. These salt solutions can be rationally combined according to different desalination or collection purposes.

[0024] Preferably, the salt solutions to be treated in each salt channel are relatively independent of either LiCl solution or NaCl solution.

[0025] The concentration of the salt solution to be treated is relatively independent, ranging from 200 mg / L to 50 g / L, preferably from 500 mg / L to 25 g / L, and more preferably from 3 to 10 g / L;

[0026] The negative electrode current collector includes at least one of the following conductive carriers with a large specific surface area: carbon cloth, hydrophobic carbon cloth, graphite paper, zinc sheet, aluminum foil, copper foil, and foamed metal.

[0027] The ion exchange membrane includes at least one of anion exchange membrane (AEM) and cation exchange membrane (CEM). The ion exchange membrane is placed between the electrolyte and the salt solution to be treated or between different salt solutions to be treated, for the purpose of ion exchange and isolation. Generally, anion / cation exchange membranes are placed alternately.

[0028] The anion exchange membrane includes one of the following: 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, one of the following: an ion exchange membrane containing -N(CH3)3OH (quaternary ammonium group) and a chloride ion exchange membrane.

[0029] The cation exchange membrane includes one of the following: a cation exchange membrane containing -SO3H (sulfonic acid group), a cation exchange membrane containing -COOH (carboxyl group), a fast ion conductor membrane, 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 following: a cation exchange membrane containing -SO3H (sulfonic acid group) and a lithium ion exchange membrane.

[0030] The fast ion conductor thin films include Si-OC, Si-OC-Al, Si-CN, Si-ON, Si-OCN, Si-C, Si-N systems, as well as Li 1+x Al x Ge 2-x( PO4)3(LAGP) and Li1+x Al x Ti 2-x (PO4)3(LATP), Li7La3Zr2O 12 (LLZO), LiGeP2S 12 (LGPS), Na 1+x Zr2Si 2-x P x O 12 One type of isofast ion-conducting thin film, wherein 0 ≤ x ≤ 2; preferably Li 1+x Al x Ti 2-x (PO4)3 and Na 1+x Zr2Si 2-x P x O 12 One type of thin film in the system. Fast ion conductor thin films have stronger ion-selective permeability, allowing only a single type of ion to pass through the film. They are generally advantageous when the penetrating ions are lithium ions or sodium ions.

[0031] A method for targeted redox-driven electrochemical desalination, ion extraction, and electrode material recovery includes the following steps:

[0032] (1) Preparation of positive and negative electrode electrolytes: Dissolve the positive and negative electrode active materials in solutions with corresponding auxiliary conductive agents, stir, and sonicate to obtain positive and negative electrode electrolytes;

[0033] (2) Assemble the salt solution to be treated, positive and negative electrode electrolytes, positive and negative current collecting electrode materials, and ion exchange membrane into a desalination battery device.

[0034] (3) After the positive and negative electrodes are connected, a potential difference is generated due to the different potentials of the redox reactions occurring at the two ends, which powers the desalination process and drives the desalination reaction; the reaction occurring at the positive electrode is: O 2(g) +2H₂O + 4e - =4OH - The reaction occurring at the negative electrode is: RM-ne - =RM n+ Where RM represents the reduced state of the aforementioned negative electrode active material, RM n+ The corresponding oxidation state;

[0035] (4) The negative electrode electrolyte in the desalination unit is pumped out and reacts directly with the electrode material to be treated in the recovery unit. After passing through a filter membrane, the solution and the electrode material to be treated are separated and flowed back to the desalination unit to drive the continuous desalination reaction. The reaction of this recovery process is: RM n+ +S=RM+S n+ Where S is the aforementioned cathode material to be recycled, S n+ Its corresponding oxidation state.

[0036] The ultrasound in step (1) is performed at 40-100 kHz for 0.5-1.5 hours.

[0037] In step (4), the electrode material to be processed is preferably prepared into powder or granules before being added to the recycling unit so that it can react fully.

[0038] This invention employs energy level matching and ion extraction technology, utilizing the redox reaction between the electrolyte and electrode materials to directly extract target ions from waste batteries; then, it integrates electrodialysis coupling technology and air-liquid flow battery technology into a multifunctional device to achieve the purpose of target ion enrichment and seawater desalination, while also promoting the recycling of some reactants within the device.

[0039] This invention utilizes the difference in potential energy between the positive and negative electrodes to create a voltage, enabling ions to achieve desalination, enrichment of target elements, and production of byproducts under the drive of an internal electric field and the selective action of an ion exchange membrane. The recycling section uses electrolytes that have lost their desalination activity due to participation in peroxidation reactions as a redox medium, participating in the recycling of waste electrode materials in a catalyst-like manner. Through redox reactions with the recycled battery electrode materials, the target elements in the recycled battery electrode materials are extracted into the solution and simultaneously reduced to a desalination-active state. By continuously replacing the recycled battery electrode materials, keeping the desalination-active substances in a regenerated state, the desalination process can continue indefinitely. Whether the recycled battery electrode materials are added at the beginning or during the process, it is effective.

[0040] The method for recycling battery electrode materials, ion extraction, and electrochemical desalination described in this invention can be applied to the fields of battery electrode material recycling, seawater desalination, and harmless treatment of toxic ions. The seawater desalination includes seawater desalination, and the toxic ions include heavy metal ions.

[0041] The working mechanism of this invention is as follows:

[0042] During the desalination process, oxygen in the air undergoes a catalytic reaction at the positive electrode: O 2(g) +2H₂O + 4e - =4OH - Simultaneously, an oxidation reaction occurs at the negative electrode: RM-ne - =RM n+ RM represents the reduced state of the aforementioned negative electrode active material, which transforms into the corresponding oxidized state RM after losing electrons. n+Due to the difference in potential during the electrochemical reaction at the positive and negative electrodes, a potential difference is generated. Driven by this potential difference and the selective permeability of the ion exchange membrane, the salt solution to be treated in the middle of the desalination unit will achieve desalination or enrichment and purification. In the negative electrode solution where the desalination reaction has occurred, RM and RM... n+ Coexistence, driven by the circulating pump, enters the recovery unit, RM n+ Spontaneous reaction with S: RM n+ +S=RM+S n+ Where S is the aforementioned cathode material to be recycled, S n+ This corresponds to its oxidation state. This allows ions to be extracted from the positive electrode material to be recycled, while simultaneously reactivating the negative electrode active material RM. Since the positive electrode active material is air, combined with the recycling of the negative electrode active material, the desalination unit can operate continuously, thus achieving integrated desalination and battery electrode material recycling.

[0043] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0044] This invention utilizes a targeted redox method to selectively extract elements of high economic value from battery electrode materials, achieving high purity while preserving the integrity of the remaining structure and allowing for other applications. The raw materials used are readily available, have low requirements, are low-cost, and environmentally friendly. During the recycling process, it significantly reduces greenhouse gas emissions and secondary pollution, further reducing battery pollution and offering the advantage of sustainable utilization.

[0045] The electrochemical continuous desalination process in this invention is simple and convenient, and has practical application value in seawater desalination. It helps humans obtain usable freshwater resources. This method is suitable for large-scale production in factories and can be applied in industrial wastewater treatment, domestic water purification, energy conversion and storage, and other fields that require electrical energy. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the three-channel device for recycling battery electrode materials and electrochemical desalination in this invention;

[0047] Figure 2 This is a schematic diagram of the four-channel electrochemical desalination device for recycling battery electrode materials in this invention;

[0048] Figure 3 LiFePO4 and [Fe(CN)6] were selected. 4- A schematic diagram of a four-channel electrochemical desalination device for recovering battery electrode materials and negative electrode active materials.

[0049] Figure 4 Example 1 was performed without the addition of LiFePO4, i.e., Fe(CN)6. 4- Voltage-discharge time variation curve of the device when / LiFePO4=1:0;

[0050] Figure 5 In Example 1 Figure 4 Conductivity-time curves of LiCl solution in chamber II and NaCl solution in chamber III under the corresponding conditions;

[0051] Figure 6 In Example 1, when the amount of LiFePO4 added was Fe(CN)6] 4- The voltage-discharge time variation curve of the device when / LiFePO4=1:1;

[0052] Figure 7 This is a voltage-discharge time curve of the device in Example 1 when LiFePO4 is added midway through the discharge;

[0053] Figure 8 In Example 1 Figure 7 Concentration-time curves of LiCl solution in chamber II and NaCl solution in chamber III under the corresponding conditions;

[0054] Figure 9 The images show the XRD patterns of LiFePO4 powder before and after the reaction in Example 1.

[0055] Figure 10 In Example 2, when the amount of LiFePO4 added was Fe(CN)6] 4- The voltage-discharge time variation curve of the device when / LiFePO4=1:0.5;

[0056] Figure 11 The corresponding conductivity-time curves are shown for the LiCl solution in chamber II and the NaCl solution in chamber III in Example 2.

[0057] Figure 12 This is a voltage-discharge time curve of the device in Example 3 when the amount of LiFePO4 added is Fc / LiFePO4 = 1:1;

[0058] Figure 13 The diagram shows the conductivity-time curve of the NaCl solution in chamber II in Example 3. Detailed Implementation

[0059] The present invention will be further described in detail below with reference to embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0060] Unless otherwise specified, all reagents used in the examples are commercially available.

[0061] Example 1

[0062] A method for targeted redox-driven electrochemical desalination, ion extraction, and electrode material recovery, wherein the apparatus for recovering LiFePO4 and continuously desalting includes the following operations:

[0063] (I) Preparation of positive and negative electrode current collectors:

[0064] 1) Take 5 mg of Ir / C powder, 50 μl of Nafion solution and 1000 μl of isopropanol in a ratio of 5 mg: 50 μl: 1000 μl, and pour them into a 1 ml test tube.

[0065] 2) After sonicating the mixture in the test tube for half an hour, evenly coat the slurry onto the hydrophobic carbon cloth;

[0066] 3) Place the hydrophobic carbon cloth coated with slurry into a 60℃ oven and take it out after 8 hours. Cut out a circular hydrophobic carbon cloth with a diameter of 3.5cm as the positive electrode.

[0067] 4) Cut out a circular piece of ordinary carbon cloth with a diameter of 3.5cm using scissors to serve as the negative electrode;

[0068] (II) Preparation of electrolyte:

[0069] 5) Weigh 0.85923g Fe4[Fe(CN)6], 0.50352g LiOH·H2O, and 0.5g lithium chloride, and dissolve them together in 100mL of deionized water; after stirring for 4h, filter out the reddish-brown precipitate Fe(OH)3, and the remaining filtrate is a mixed solution of 30mM Li4[Fe(CN)6] and 5000ppm LiCl, which is used as the negative electrode electrolyte;

[0070] 6) Take 25 ml of negative electrode electrolyte as the flowing liquid in chamber I;

[0071] 7) Prepare 100 mL of 5 g / L salt solution using 99% pure NaCl;

[0072] 8) Take 25 ml of the NaCl solution prepared in step 7) and circulate it in chamber IV. Oxygen from the air dissolves spontaneously in the liquid in chamber IV through the hydrophobic carbon cloth. The dissolved oxygen and the NaCl liquid together form the positive electrode electrolyte;

[0073] (III) Preparation of NaCl and LiCl solutions to be treated:

[0074] 9) Prepare 100 mL of anhydrous LiCl solution with a concentration of 5 g / L, and take 15 mL of the solution as the salt solution to be treated 1 flowing in chamber II;

[0075] 10) Take 15 ml of the NaCl solution prepared in step 7) as the flowable salt solution 2 in chamber III;

[0076] (IV) Device Preparation:

[0077] 11) The two circular carbon cloths obtained in (I) are used as the positive and negative current collecting electrode materials, the negative electrode electrolyte obtained in step 6), the positive electrode electrolyte obtained in step 8), the salt solution to be treated in step 9), the salt solution to be treated in step 10), one anion exchange membrane (4 cm in diameter), two cation exchange membranes (4 cm in diameter), and six acrylic outer plates (10 cm × 10 cm × 1 cm), of which five acrylic plates have cavities (3.5 cm in diameter). Figure 2 and Figure 3 The schematic structure is assembled into a four-channel desalination battery device; the device is fixed with studs and nuts, and chambers I, II, III and IV are circulated by a small peristaltic pump;

[0078] 12) A 50ml cylindrical container serves as the storage tank for the recovery unit, divided into upper and lower sections by a glass fiber diaphragm. LiFePO4 powder is placed in the upper layer so that it can react with the pumped electrolyte, but after filtration, it will not flow back to the desalination unit with the solution.

[0079] After assembling the device in Example 1, different amounts of Fe(CN)6 were added to the recovery unit. 4- The amount of LiFePO4 in the / LiFePO4 molar ratio.

[0080] The redox reaction formulas for each part in Example 1 are as follows:

[0081] Positive electrode in desalination process: O 2(g) +2H₂O + 4e - +4Na + =4NaOH

[0082] Negative electrode: 4Li4Fe(CN)6-4e -= 4Li3Fe(CN)6 + 4Li +

[0083] The recovery process is as follows: 4Li3Fe(CN)6 + 4LiFePO4 = 4Li4Fe(CN)6 + 4FePO4

[0084] Figure 4 [Fe(CN)6] 4- Voltage variation trend and discharge duration of the device when / LiFePO4=1:0; Figure 5 for Figure 4 The conductivity changes of the LiCl solution in chamber II and the NaCl solution in chamber III under the given conditions are as follows: the change in the solution in chamber II is a process of LiCl enrichment, and the change in the solution in chamber III is a process of desalination.

[0085] Figure 6 [Fe(CN)6] 4- Voltage variation trend and discharge duration of the device when / LiFePO4=1:1;

[0086] Figure 7 The voltage change trend and discharge duration of the device when LiFePO4 is added midway through the desalting reaction, 140 min after the start of the reaction; Figure 8 for Figure 7 The concentration changes of LiCl solution in chamber II and NaCl solution in chamber III under the specified conditions were observed. After 954 minutes of desalination, the concentration of NaCl solution in chamber III was below 500 ppm, meeting the standard for fresh water.

[0087] Figure 9 The images show the XRD patterns of LiFePO4 powder before and after the reaction. The presence of FePO4 after the reaction indicates that the lithium element has been extracted.

[0088] Based on the data above, as the amount of LiFePO4 added increases, the desalination reaction time can be extended, while lithium in LiFePO4 is enriched and extracted in the form of LiCl solution. Furthermore, adding LiFePO4 midway through the reaction has the same effect; therefore, as long as LiFePO4 is continuously renewed through reaction with the redox electrolyte, the desalination reaction can be sustained, and lithium in the electrode material can be continuously recovered in the form of LiCl.

[0089] Example 2

[0090] A method for targeted redox-driven electrochemical desalination, ion extraction, and electrode material recovery, comprising an apparatus for recovering LiFePO4 and continuously desalting, including the following operations:

[0091] (I) Preparation of positive and negative current collector electrode materials:

[0092] 1) Take 5 mg of Pt / C powder, 50 μl of Nafion solution and 1000 μl of isopropanol in a ratio of 5 mg: 50 μl: 1000 μl, and pour them into a 1 ml test tube.

[0093] 2) After sonicating the mixture in the test tube for half an hour, evenly coat the slurry onto the hydrophobic carbon cloth;

[0094] 3) Place the hydrophobic carbon cloth coated with slurry into a 60℃ oven and take it out after 8 hours. Cut out a circular hydrophobic carbon cloth with a diameter of 3.5cm as the positive electrode.

[0095] 4) Cut out a circular piece of ordinary carbon cloth with a diameter of 3.5cm using scissors to serve as the negative electrode;

[0096] (II) Preparation of electrolyte:

[0097] 5) Weigh 1.43205g Fe4[Fe(CN)6], 0.8392g LiOH·H2O, and 0.5g lithium fluoride, and dissolve them together in 100mL of deionized water. After stirring for 4 hours, filter out the reddish-brown precipitate Fe(OH)3. The remaining filtrate is a mixed solution of 50mM Li4[Fe(CN)6] and 5000ppm LiF, which is used as the negative electrode electrolyte.

[0098] 6) Take 25 ml of negative electrode electrolyte as the flowing liquid in chamber I;

[0099] 7) Prepare a 100 mL salt solution with a concentration of 5 g / L using 99% pure NaF;

[0100] 8) Take 25 ml of the NaF solution prepared in step 7) and circulate it in chamber IV. Oxygen from the air dissolves spontaneously in the liquid in chamber IV through the hydrophobic carbon cloth. The dissolved oxygen and the NaF liquid together form the positive electrode electrolyte;

[0101] (III) Preparation of NaF and LiF solutions to be treated:

[0102] 9) Prepare 100 mL of LiF (99% purity) with a concentration of 5 g / L, and take 15 mL of the solution as the salt solution to be treated 1 flowing in chamber II;

[0103] 10) Take 15 ml of the NaF solution prepared in step 7) to simulate sewage, and use it as the salt solution 2 to be treated flowing in chamber III;

[0104] (IV) Device Preparation:

[0105] 11) The two circular carbon cloths obtained in (I) are used as the positive and negative current collecting electrode materials, the negative electrode electrolyte obtained in step 6), the positive electrode electrolyte obtained in step 8), the salt solution to be treated in step 9), the salt solution to be treated in step 10), one anion exchange membrane (4 cm in diameter), two cation exchange membranes (4 cm in diameter), and six acrylic outer plates (10 cm × 10 cm × 1 cm), of which five acrylic plates have cavities (3.5 cm in diameter). Figure 2 The schematic structure is assembled into a four-channel desalination battery device; the device is fixed with studs and nuts, and chambers I, II, III and IV are circulated by a small peristaltic pump;

[0106] 12) A 50ml cylindrical container serves as the storage tank for the recovery unit, divided into upper and lower sections by a glass fiber diaphragm. LiFePO4 powder is placed in the upper section. This allows the LiFePO4 to react with the pumped electrolyte, but after filtration, it will not flow back into the desalination unit with the solution.

[0107] After assembling the device in Example 2, Fe(CN)6 was added in a molar ratio of […]. 4- The ratio of LiFePO4 to LiFePO4 is 1:0.5.

[0108] The redox reaction formulas for each part in Example 2 are as follows:

[0109] Positive electrode in desalination process: O 2(g) +2H₂O + 4e - +4Na + =4NaOH

[0110] Negative electrode: 4Li4Fe(CN)6-4e - = 4Li3Fe(CN)6 + 4Li +

[0111] The recovery process is as follows: 4Li3Fe(CN)6 + 4LiFePO4 = 4Li4Fe(CN)6 + 4FePO4

[0112] Figure 10 [Fe(CN)6] 4- Voltage variation trend and discharge duration of the device when / LiFePO4=1:0.5; Figure 11 The conductivity changes are shown for the LiF solution in chamber II and the NaF solution in chamber III. It can be seen that as the concentration increases, the discharge time, the enrichment degree of LiF, and the concentration of F in the simulated wastewater increase to a certain extent. - Further purification.

[0113] Example 3

[0114] A method for targeted redox-driven electrochemical desalination, ion extraction, and electrode material recovery, comprising an apparatus for recovering LiFePO4 and continuously desalting, including the following operations:

[0115] (I) Preparation of positive and negative current collector electrode materials:

[0116] 1) Take 5 mg of Ru / C powder, 50 μl of Nafion solution and 1000 μl of isopropanol in a ratio of 5 mg: 50 μl: 1000 μl, and pour them into a 1 ml test tube.

[0117] 2) After sonicating the mixture in the test tube for half an hour, evenly coat the slurry onto the hydrophobic carbon cloth;

[0118] 3) Place the hydrophobic carbon cloth coated with slurry into a 60℃ oven and take it out after 8 hours. Cut out a circular hydrophobic carbon cloth with a diameter of 3.5cm as the positive electrode.

[0119] 4) Cut out a circular piece of ordinary carbon cloth with a diameter of 3.5cm using scissors to serve as the negative electrode;

[0120] (II) Preparation of electrolyte:

[0121] 5) Select one of the three negative electrode active materials, BTMAP-Fc, FcNCl, or FcN2Br2, and prepare 100 ml of a 30 mM solution, adding 0.5 g of lithium chloride as an auxiliary conductive additive. Use this mixed solution as the negative electrode electrolyte. The synthesis method of FcNCl or FcN2Br2 is referenced in [Hu B, Debruler C, Rhodes Z, et al. Long-Cycling Aqueous Organic Redox Flow Battery (AORFB) towards Sustainable and Safe Energy Storage[J]. Journal of the American Chemical Society, 2017, 139(3): 1207-14.];

[0122] 6) Take 25 ml of negative electrode electrolyte as the flowing liquid in chamber I;

[0123] 7) Prepare 100 mL of 5 g / L salt solution using 99% pure NaCl;

[0124] 8) Take 25 ml of the NaCl solution prepared in step 7) and circulate it in chamber IV. Oxygen from the air dissolves spontaneously in the liquid in chamber IV through the hydrophobic carbon cloth. The dissolved oxygen and the NaCl liquid together form the positive electrode electrolyte;

[0125] (III) Preparation of NaCl and LiCl solutions to be treated:

[0126] 9) Prepare 100 mL of anhydrous LiCl solution with a concentration of 5 g / L, and take 15 mL of the solution as the salt solution to be treated 1 flowing in chamber II;

[0127] 10) Take 15 ml of the NaCl solution prepared in step 7) as the flowable salt solution 2 in chamber III;

[0128] (IV) Device Preparation:

[0129] 11) The two circular carbon cloths obtained in (I) are used as the positive and negative current collecting electrode materials, the negative electrode electrolyte obtained in step 6), the positive electrode electrolyte obtained in step 8), the salt solution to be treated in step 9), the salt solution to be treated in step 10), one anion exchange membrane (4 cm in diameter), two cation exchange membranes (4 cm in diameter), and six acrylic outer plates (10 cm × 10 cm × 1 cm), of which five acrylic plates have cavities (3.5 cm in diameter). Figure 2 The schematic structure is assembled into a four-channel desalination battery device; the device is fixed with studs and nuts, and chambers I, II, III and IV are circulated by a small peristaltic pump;

[0130] 11) A 50ml cylindrical container serves as the storage tank for the recovery unit, divided into upper and lower sections by a glass fiber diaphragm. LiFePO4 powder is placed in the upper section. This allows the LiFePO4 to react with the pumped electrolyte, but after filtration, it will not flow back into the desalination unit with the solution.

[0131] After assembling the device in Example 3, LiFePO4 with a molar ratio of Fc / LiFePO4 = 1:1 was added.

[0132] The redox reaction formulas for each part in Example 3 are as follows:

[0133] Positive electrode in desalination process: O 2(g) +2H₂O + 4e - +4Na + =4NaOH

[0134] Negative electrode: 4Fc-4e - =4Fc +

[0135] Recycling process 4Fc + +4LiFePO4=4Fc+4FePO4+4Li +

[0136] Figure 12The voltage variation trend and discharge duration of the device when Fc / LiFePO4 = 1:1; Figure 13 The figures show the conductivity changes of the LiCl solution in chamber II and the NaCl solution in chamber III, respectively. It can be seen that the trend of the salt solution changes is consistent with that in Example 1, but the discharge time is slightly shorter, and the reaction efficiency of Fc with LiFePO4 may be slightly lower than that in Example 1.

[0137] Example 4

[0138] A method for targeted redox-driven electrochemical desalination, ion extraction, and electrode material recovery, wherein the apparatus for recovering LiCoO2 and continuously desalting includes the following operations:

[0139] (I) Preparation of positive and negative current collector electrode materials:

[0140] 1) Take 5 mg of Ir / C powder, 50 μl of Nafion solution and 1000 μl of isopropanol in a ratio of 5 mg: 50 μl: 1000 μl, and pour them into a 1 ml test tube.

[0141] 2) After sonicating the mixture in the test tube for half an hour, evenly coat the slurry onto the hydrophobic carbon cloth;

[0142] 3) Place the hydrophobic carbon cloth coated with slurry into a 60℃ oven and take it out after 8 hours. Cut out a circular hydrophobic carbon cloth with a diameter of 3.5cm as the positive electrode.

[0143] 4) Cut out a circular piece of ordinary carbon cloth with a diameter of 3.5cm using scissors to serve as the negative electrode;

[0144] (II) Preparation of the TEMPO mixed electrolyte solution:

[0145] 5) Prepare a 100ml mixed solution of 40mM TEMPO and 5g / L LiCl as the negative electrode electrolyte by mixing lithium chloride and TEMPO powder.

[0146] 6) Take 25 ml of negative electrode electrolyte as the flowing liquid in chamber I;

[0147] 7) Prepare 100 mL of 5 g / L salt solution using 99% pure NaCl;

[0148] 8) Take 25 ml of the NaCl solution prepared in step 7) and circulate it in chamber IV. Oxygen from the air dissolves spontaneously in the liquid in chamber IV through the hydrophobic carbon cloth. The dissolved oxygen and the NaCl liquid together serve as the positive electrode electrolyte;

[0149] (III) Preparation of NaCl and LiCl solutions to be treated:

[0150] 9) Prepare 100 mL of anhydrous LiCl solution with a concentration of 5 g / L, and take 15 mL of the solution as the salt solution to be treated 1 flowing in chamber II;

[0151] 10) Take 15 ml of the NaCl solution prepared in step 7) as the flowable salt solution 2 in chamber III;

[0152] (IV) Device Preparation:

[0153] 11) The two circular carbon cloths obtained in (I) are used as the positive and negative current collecting electrode materials, the negative electrode electrolyte obtained in step 6), the positive electrode electrolyte obtained in step 8), the salt solution to be treated in step 9), the salt solution to be treated in step 10), one anion exchange membrane (4 cm in diameter), two cation exchange membranes (4 cm in diameter), and six acrylic outer plates (10 cm × 10 cm × 1 cm), of which five acrylic plates have cavities (3.5 cm in diameter). Figure 2 The schematic structure is assembled into a four-channel desalination battery device; the device is fixed with studs and nuts, and chambers I, II, III and IV are circulated by a small peristaltic pump;

[0154] 11) A 50ml cylindrical container serves as the storage tank for the recovery unit, divided into upper and lower sections by a glass fiber diaphragm. LiCoO2 powder is placed in the upper section. This allows the LiCoO2 to react with the pumped electrolyte, but after filtration, it does not flow back to the desalination unit with the solution.

[0155] After assembling the device in Example 4, LiCoO2 with a molar ratio of TEMPO / LiCoO2 = 1:1 was added.

[0156] The redox reaction formulas for each part in Example 4 are as follows:

[0157] Positive electrode in desalination process: O 2(g) +2H₂O + 4e - +4Na + =4NaOH

[0158] Negative electrode: 4TEMPO-4e - =4TENPO +

[0159] 4TEMPO recycling process + +4LiCoO2=4TEMPO+4CoO2+4Li +

[0160] After assembling the device in Example 4, its electrochemical performance was tested. The conductivity of the solution was measured using a conductivity meter to obtain the removal efficiency of enriched LiCl and NaCl. The results are shown in Table 1 below:

[0161] Table 1. Removal effect of enriched LiCl and NaCl in Example 4

[0162]

[0163] The data obtained above show that the conductivity of the NaCl solution in chamber III decreases, while the conductivity of the LiCl solution in chamber II increases. This indicates that the solution in chamber II accepts LiCl from the negative electrode electrolyte in chamber I. + Cl in the solution of chamber III - This process increases the LiCl concentration, enriching lithium in chamber II and thus recovering lithium from LiCoO2 waste batteries. Meanwhile, the anions and cations in chamber III gradually move to chambers II and IV, causing the NaCl concentration to decrease and achieving the effect of saline desalination.

[0164] Example 5

[0165] A method for targeted redox-driven electrochemical desalination, ion extraction, and electrode material recovery, for the recovery of LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.8 Co 0.1 Al 0.1 O2, LiNiO2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.6 Co 0.2 Al 0.2 O2, LiNi 0.5 Co 0.3 Mn 0.2 O2, LiN i0.5 Co 0.3 Al 0.2 O2, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiNi 1 / 3 Co 1 / 3 Al 1 / 3 The device for continuous desalination of O2, LiTMO2, and LiTMPO4 (TM represents a combination of transition metal elements with Ni as the main component, such as Ni, Co, Mn, Ti, Al, Fe, Zr, Cu, Zn, Cr, and V, in binary or multi-component combinations) includes the following operations:

[0166] (I) Preparation of positive and negative current collector electrode materials:

[0167] 1) Take 5 mg of Ir / C powder, 50 μl of Nafion solution and 1000 μl of isopropanol in a ratio of 5 mg: 50 μl: 1000 μl, and pour them into a 1 ml test tube.

[0168] 2) After sonicating the mixture in the test tube for half an hour, evenly coat the slurry onto the hydrophobic carbon cloth;

[0169] 3) Place the hydrophobic carbon cloth coated with slurry into a 60℃ oven and take it out after 8 hours. Cut out a circular hydrophobic carbon cloth with a diameter of 3.5cm as the positive electrode.

[0170] 4) Cut out a circular piece of ordinary carbon cloth with a diameter of 3.5cm using scissors to serve as the negative electrode;

[0171] (II) Electrolyte I - / I3 - Preparation of mixed solutions:

[0172] 5) Dissolve 1-ethyl-3-methylimidazolium iodide and I2 in 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide to prepare I2 with a concentration of 60 mM. - / I3 - As a negative electrode electrolyte;

[0173] 6) Take 25 ml of negative electrode electrolyte as the flowing liquid in chamber I;

[0174] 7) Prepare 100 mL of 5 g / L salt solution using 99% pure NaCl;

[0175] 8) Take 25 ml of the NaCl solution prepared in step 7) and circulate it in chamber IV. Oxygen from the air dissolves spontaneously in the liquid in chamber IV through the hydrophobic carbon cloth. The dissolved oxygen and the NaCl liquid together form the positive electrode electrolyte;

[0176] (III) Preparation of NaCl and LiCl solutions to be treated:

[0177] 9) Prepare 100 mL of anhydrous LiCl solution with a concentration of 5 g / L, and take 15 mL of the solution as the salt solution to be treated 1 flowing in chamber II;

[0178] 10) Take 15 ml of the NaCl solution prepared in step 7) as the flowable salt solution 2 in chamber III;

[0179] (IV) Device Preparation:

[0180] 11) The two circular carbon cloths obtained in (I) are used as the positive and negative current collecting electrode materials, the negative electrode electrolyte obtained in step 6), the positive electrode electrolyte obtained in step 8), the salt solution to be treated in step 9), the salt solution to be treated in step 10), one anion exchange membrane (4 cm in diameter), two cation exchange membranes (4 cm in diameter), and six acrylic outer plates (10 cm × 10 cm × 1 cm), of which five acrylic plates have cavities (3.5 cm in diameter). Figure 2 The schematic structure is assembled into a four-channel desalination battery device; the device is fixed with studs and nuts, and chambers I, II, III and IV are circulated by a small peristaltic pump;

[0181] 11) A 50ml cylindrical container serves as the storage tank for the recovery unit, divided into upper and lower parts by a glass fiber diaphragm. LiNi 0.8 Co 0.1 Mn 0.1 O2 powder is placed in the upper layer. This allows LiNi to... 0.8 Co 0.1 Mn 0.1 O2 can react with the pumped electrolyte, but after filtration, it will not flow back into the desalination unit with the solution. This is because LiNi... 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.8 Co 0.1 Al 0.1 O2, LiNiO2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.6 Co 0.2 Al 0.2 O2, LiNi 0.5 Co 0.3 Mn 0.2 O2, LiN i0.5 Co 0.3 Al 0.2 O2, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiNi 1 / 3 Co 1 / 3 Al 1 / 3 O2, LiTMO2, and LiTMPO4 (TM represents a combination of transition metal elements with Ni as the main component, such as Ni, Co, Mn, Ti, Al, Fe, Zr, Cu, Zn, Cr, and V in single, binary, or multi-component combinations) are all battery electrode materials whose redox elements are predominantly Ni. Therefore, in the case of I3 - The chemical potentials are similar, so LiNi is chosen. 0.8 Co0.1 Mn 0.1 O2 is used as a representative of recycling.

[0182] After assembling the device in Example 5, add the following ingredients at a molar ratio of...

[0183] I3 - / LiNi 0.8 Co 0.1 Mn 0.1 LiNi with O2 = 1:1 0.8 Co 0.1 Mn 0.1 O2 amount.

[0184] The redox reaction equations for each part in Example 5 are as follows:

[0185] Positive electrode in desalination process: O 2(g) +2H₂O + 4e - +4Na + =4NaOH

[0186] Negative electrode: 6I - -4e - =2I3 -

[0187] Recycling process 2I3 - +4LiNi 0.8 Co 0.1 Mn 0.1 O2 = 6I - +4Ni 0.8 Co 0.1 Mn 0.1 O2+4Li +

[0188] After assembling the device in Example 5, its electrochemical performance was tested. The conductivity of the solution was measured using a conductivity meter to obtain the removal efficiency of enriched LiCl and NaCl. The results are shown in Table 2 below:

[0189] Table 2 shows the removal effect of enriched LiCl and NaCl in Example 5.

[0190]

[0191] The data obtained above show that the conductivity of the NaCl solution in chamber III decreases, while the conductivity of the LiCl solution in chamber II increases. This indicates that the solution in chamber II accepts LiCl from the negative electrode electrolyte in chamber I. + Cl in the solution of chamber III -This process increases the LiCl concentration, enriching lithium in chamber II and thus recovering lithium from LiCoO2 waste batteries. Meanwhile, the anions and cations in chamber III gradually move to chambers II and IV, causing the conductivity of NaCl to decrease and achieving the effect of saline desalination.

[0192] Example 6

[0193] A method for targeted redox-driven electrochemical desalination, ion extraction, and electrode material recovery, comprising the following operations: A device for recovering Na3MnTi(PO4)3, Na3V2(PO4)3, NaTMO2, and NaTMPO4 (TM being a combination of transition metal elements, such as single, binary, or multi-component combinations of Ni, Co, Mn, Ti, Al, Fe, Zr, Cu, Zn, Cr, and V) and continuously desalting.

[0194] (I) Preparation of positive and negative current collector electrode materials:

[0195] 1) Take 5 mg of Ir / C powder, 50 μl of Nafion solution and 1000 μl of isopropanol in a ratio of 5 mg: 50 μl: 1000 μl, and pour them into a 1 ml test tube.

[0196] 2) After sonicating the mixture in the test tube for half an hour, evenly coat the slurry onto the hydrophobic carbon cloth;

[0197] 3) Place the hydrophobic carbon cloth coated with slurry into a 60℃ oven and take it out after 8 hours. Cut out a circular hydrophobic carbon cloth with a diameter of 3.5cm as the positive electrode.

[0198] 4) Cut out a circular piece of ordinary carbon cloth with a diameter of 3.5cm using scissors to serve as the negative electrode;

[0199] (II) Preparation of electrolyte:

[0200] 5) Weigh 1.82346g of sodium ferrocyanide and 0.5g of sodium chloride, dissolve them together in 100mL of deionized water to prepare a 60mM Na4Fe(CN)6 mixed solution, sonicate and put it into a 100mL beaker.

[0201] 6) Take 25 ml of negative electrode electrolyte as the flowing liquid in chamber I;

[0202] 7) Prepare 100 mL of 5 g / L salt solution using 99% pure NaCl;

[0203] 8) Take 25 ml of the NaCl solution prepared in step 7) and circulate it in chamber IV. Oxygen from the air dissolves spontaneously in the liquid in chamber IV through the hydrophobic carbon cloth. The dissolved oxygen and the NaCl liquid together form the positive electrode electrolyte;

[0204] (III) Preparation of NaCl solution to be treated:

[0205] 9) Take 15 ml of the NaCl solution prepared in step 7) as the flowing salt solution to be treated 1 in chamber II;

[0206] (IV) Device Preparation:

[0207] 10) The two circular carbon cloths obtained in (I) are used as the positive and negative current collecting electrode materials, the negative electrode electrolyte obtained in step 6), the positive electrode electrolyte obtained in step 8), the salt solution to be treated in step 9), a piece of anion exchange membrane (4 cm in diameter), and a piece of Na 1+x Zr2Si 2-x P x O 12 A fast sodium ion conductor film (4cm in diameter), consisting of 6 acrylic outer plates (10cm×10cm×1cm), five of which have cavities (3.5cm in diameter). Figure 1 The schematic structure is assembled into a three-channel desalination battery device; the device is fixed with studs and nuts, and chambers I, II and III are respectively circulated by a small peristaltic pump;

[0208] 11) A 50ml cylindrical container serves as the storage tank for the recovery unit, divided into upper and lower sections by a glass fiber diaphragm. Na3MnTi(PO4)3 powder is placed in the upper layer. This allows Na3MnTi(PO4)3 to react with the pumped electrolyte, but after filtration, it will not flow back to the desalination unit with the solution.

[0209] The redox reaction formulas for each part in Example 6 are as follows:

[0210] Positive electrode in desalination process: O 2(g) +2H₂O + 4e - +4Na + =4NaOH

[0211] Negative electrode: 4Na4Fe(CN)6–4e - = 4Na3Fe(CN)6 + 4Na +

[0212] Recycling process

[0213] x Na3Fe(CN)6+Na3MnTi(PO4)3=x Na4Fe(CN)6+Na 3-x MnTi(PO4)3 (0≤x≤3)

[0214] After assembling the device in Example 6, its electrochemical performance was tested. The conductivity of the solution was measured using a conductivity meter to obtain the NaCl removal effect. The results are shown in Table 3 below:

[0215] Table 3 shows the NaCl removal effect in Example 6.

[0216]

[0217]

[0218] The data obtained above show that the ionic conductivity of the NaCl solution in chamber II decreases, indicating that the concentration of NaCl is decreasing, and the Na+ content is decreasing. + Cl - It passes through the fast sodium ion conductor membrane and the anion exchange membrane respectively into chamber I and chamber III to achieve the function of saline water desalination.

[0219] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A system for targeted redox-driven electrochemical desalination, ion extraction, and electrode material recovery, characterized in that... It includes a recovery unit and a desalination unit, wherein: The recycling unit is a storage tank containing the battery electrode material to be recycled and a filter membrane; the filter membrane divides the storage tank into upper and lower layers, with the battery electrode material to be recycled placed in the upper layer; The desalination unit is a fluid battery based on a liquid flow structure, which includes a positive electrode current collector, a positive electrode electrolyte, a brine solution to be treated, a negative electrode electrolyte, and a negative electrode current collector. Different solutions are separated into different chambers by ion exchange membranes to achieve different functions. The solutions in each chamber are circulated by a circulation pump. The recovery unit is connected to the negative electrode electrolyte of the desalination unit through a circulation pump and pipeline to form a circulation. That is, the negative electrode electrolyte is pumped out from the desalination unit, enters the upper layer of the recovery unit, and directly contacts and reacts with the electrode material of the battery to be recovered. Then it is filtered through a filter membrane and enters the lower layer of the recovery unit, where it achieves solid-liquid separation with the electrode material of the battery to be recovered. Finally, it flows back to the negative electrode electrolyte of the desalination unit. The positive electrode electrolyte is an aqueous solution of positive electrode active material and auxiliary conductive additives, wherein the positive electrode active material is pure oxygen or air; The negative electrode electrolyte is a mixed aqueous solution of a negative electrode active material and an auxiliary conductive additive, wherein the negative electrode active material is a material with redox activity, including [Fe(CN)6]. 3- [Fe(CN)6] 4- TEMPO, I - Solution, I3 - At least one of the following: solution, BTMAP-Fc, FcNCl, or FcN2Br2; The battery electrode materials to be recycled include LiFePO4, LiCoO2, LiNiO2, and LiNi. 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.8 Co 0.1 Al 0.1 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.6 Co 0.2 Al 0.2 O2, LiNi 0.5 Co 0.3 Mn 0.2 O2, LiN i0.5 Co 0.3 Al 0.2 O2, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiNi 1 / 3 Co 1 / 3 Al 1 / 3 At least one of O2, Na3MnTi(PO4)3, and Na3V2(PO4)3.

2. The system for targeted redox-driven electrochemical desalination, ion extraction, and electrode material recovery according to claim 1, characterized in that: The positive electrode current collector is formed by coating a mixture of catalyst, conductive carbon black, and binder onto a hydrophobic and breathable conductive carrier; wherein the hydrophobic and breathable conductive carrier includes one of hydrophobic carbon cloth and foamed metal coated with a hydrophobic agent; the catalyst includes one of Ir / C, Pt / C, Ru / C, other noble metal catalysts, non-noble metal catalysts, and non-metallic catalysts; the binder is one of Nafion solution, polyvinylidene fluoride, hydroxymethyl cellulose, polytetrafluoroethylene, styrene-butadiene rubber latex, polyacrylic acid, polyacrylate, and polyacrylonitrile. The negative electrode current collector includes at least one of carbon cloth, hydrophobic carbon cloth, graphite paper, zinc sheet, aluminum foil, copper foil, and foamed metal; The ion exchange membrane includes at least one of anion exchange membrane and cation exchange membrane.

3. The system for targeted redox-driven electrochemical desalination, ion extraction, and electrode material recovery according to claim 1, characterized in that: The positive electrode electrolyte is an aqueous solution of positive electrode active material and auxiliary conductive additive. The auxiliary conductive additive maintains ionic consistency with the salt solution to be treated in the adjacent chamber. If the two are separated by an anion exchange membrane, they maintain anion consistency; if they are separated by a cation exchange membrane, they maintain cation consistency.

4. The system for targeted redox-driven electrochemical desalination, ion extraction, and electrode material recovery according to claim 1, characterized in that: The negative electrode electrolyte is a mixed aqueous solution of negative electrode active material and auxiliary conductive additive. The auxiliary conductive additive maintains ionic consistency with the salt solution to be treated in the adjacent chamber. If the two are separated by an anion exchange membrane, they maintain anion consistency; if they are separated by a cation exchange membrane, they maintain cation consistency.

5. The system for targeted redox-driven electrochemical desalination, ion extraction, and electrode material recovery according to claim 3 or 4, characterized in that: The auxiliary conductive additives in the negative electrode electrolyte and the positive electrode electrolyte are each relatively independently selected from at least one of NaCl, NaF, Na2SO4, KCl, LiCl, LiF, Li2SO4, and KCl.

6. The system for targeted redox-driven electrochemical desalination, ion extraction, and electrode material recovery according to claim 1, characterized in that: The salt solution to be treated can be one, two or more, that is, the salt solution to be treated is placed in a single salt channel, a double salt channel or a multi-salt channel, and the salt channels are separated by an ion exchange membrane. The salt solutions to be treated in each salt channel are relatively independent and consist of one of the following: LiCl solution, NaCl solution, NaF solution, Na2SO4 solution, KCl solution, LiF solution, Li2SO4 solution, CH3COOLi solution, CH3COONa solution, or seawater.

7. The system for targeted redox-driven electrochemical desalination, ion extraction, and electrode material recovery according to claim 6, characterized in that: The salt solutions to be treated in each of the aforementioned salt channels are relatively independent and are either LiCl solution or NaCl solution.

8. The system for targeted redox-driven electrochemical desalination, ion extraction, and electrode material recovery according to claim 6, characterized in that: The concentrations of the salt solutions to be treated are all relatively independent, ranging from 200 mg / L to 50 g / L.

9. The system for targeted redox-driven electrochemical desalination, ion extraction, and electrode material recovery according to claim 6, characterized in that: The concentrations of the salt solutions to be treated are all relatively independent, ranging from 500 mg / L to 25 g / L.

10. The system for targeted redox-driven electrochemical desalination, ion extraction, and electrode material recovery according to claim 6, characterized in that: The concentrations of the salt solutions to be treated are all relatively independent, ranging from 3 to 10 g / L.

11. A method for targeted redox-driven electrochemical desalination, ion extraction, and electrode material recovery, characterized in that... The process, performed using the system described in claim 1, specifically includes the following steps: (1) Preparation of positive and negative electrode electrolytes: Dissolve the positive and negative electrode active materials in solutions with corresponding auxiliary conductive agents, stir, and sonicate to obtain positive and negative electrode electrolytes; (2) Assemble the salt solution to be treated, positive and negative electrode electrolytes, positive and negative current collecting electrode materials, and ion exchange membrane into a desalination battery device; (3) After the positive and negative electrodes are connected, a potential difference is generated due to the different potentials of the redox reactions occurring at the two ends, which powers the desalination process and drives the desalination reaction; the reaction occurring at the positive electrode is: O 2(g) + 2 H2O + 4 e - = 4 OH - The reaction occurring at the negative electrode is: RM - ne - = RM n+ Where RM represents the reduced state of the aforementioned negative electrode active material, RM n+ The corresponding oxidation state; (4) The negative electrode electrolyte in the desalination unit is pumped out and reacted directly with the electrode material to be treated in the recovery unit. After passing through a filter membrane, the solution and the electrode material to be treated are separated and flowed back to the desalination unit to promote the continuous desalination reaction. The reaction of this recovery process is: RM n+ + S = RM + S n+ Where S is the aforementioned cathode material to be recycled, S n+ Its corresponding oxidation state.

12. The system of targeted redox-driven electrochemical desalination, ion extraction, and electrode material recovery as described in any one of claims 1-10 is used in the fields of battery electrode material recovery, seawater desalination, and harmless treatment of toxic ions.

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