Use of lithium ferrocyanide, anolyte, and method for extracting lithium from salt lake brine by means of electrical de-intercalation

Abstract

The present disclosure belongs to the technical field of lithium extraction from brine, and particularly relates to the use of lithium ferrocyanide, an anolyte, and a method for extracting lithium from salt lake brine by means of electrical de-intercalation. The method comprises extracting lithium from salt lake brine by means of electrical de-intercalation by using a salt lake brine electrical de-intercalation lithium extraction device. The salt lake brine electrical de-intercalation lithium extraction device comprises an electrolytic bath, an anion exchange membrane, an anode and a cathode, wherein the anion exchange membrane is arranged in the electrolytic bath to vertically divide the electrolytic bath into a cathode chamber and an anode chamber; the anode is arranged in the anode chamber; and the cathode is arranged in the cathode chamber. A voltage is applied to the cathode and the anode, so as to carry out lithium extraction by means of electrical de-intercalation, and an anolyte is added into the anode chamber during the process of lithium extraction by means of electrical de-intercalation. In the present disclosure, by means of adding lithium ferrocyanide into an anode chamber as an anolyte, the intercalation amount of a cathode ion sieve can be guaranteed, such that the lithium de-intercalation capacity of the cathode and the anode is more matched, and the lithium extraction efficiency is improved.

Description

Application of lithium ferrocyanide, anolyte and salt lake brine electro-deintercalation and lithium extraction method Technical Field

[0001] The present disclosure relates to the technical field of lithium extraction from brine, and in particular to the application of lithium ferrocyanide, an anolyte, and a method for extracting lithium by electro-deintercalation from salt lake brine. Background Art

[0002] The extraction and recovery methods of lithium resources from salt lake brine include electrodialysis, evaporation crystallization, solvent extraction, precipitation, ion exchange and adsorption. Among them, the adsorption method has lower cost and higher efficiency. However, acid washing is required to produce secondary waste during the exchange and adsorption process, and the permeability and solubility of the adsorbent are poor, which seriously limits its industrial application. The solvent extraction method has high yield, simple operation, and is easy to scale up industrially, but this method uses a large amount of organic solvents, which can easily lead to environmental pollution and equipment corrosion. Traditional lithium extraction methods have the disadvantages of high cost, high energy consumption, and low separation efficiency. Electrodeintercalation is a new research direction for lithium extraction from salt lakes and is a green and efficient lithium extraction technology from salt lakes.

[0003] Electrochemical lithium extraction was developed based on the working principle of lithium iron phosphate batteries. The specific application idea is to utilize the reverse working principle of aqueous lithium battery deintercalation. In essence, the lithium ions in the solution are intercalated into the cathode material for subsequent processing. The cathode material of the lithium battery with a "memory effect" on lithium ions is used as the electrode material, salt lake brine is used as the cathode electrolyte, and the magnesium-free supporting electrolyte is used as the anolyte, thus forming an electrochemical deintercalation system of "lithium-rich adsorption material | supporting electrolyte | anion membrane | brine | lithium-deficient adsorption material". During the electrolysis process, the cathode obtains electrons to undergo a reduction reaction, causing the lithium ions in the salt lake brine to be intercalated into the cathode material, thereby achieving separation. Through subsequent processing and separation operations, the effect of efficient lithium extraction is finally achieved.

[0004] CN102382984B discloses a method for electrolithiation and lithium extraction using a "rocking chair" electrode system (LiFePO4 / FePO4): the electrolytic cell is divided into two compartments by an anion selective exchange membrane: the LiFePO4 electrode is placed in a recovery solution (0.5 mol / L NaCl), and the FePO4 is placed in a raw material solution (lithium-containing brine). Under the electric field, the LiFePO4 anode undergoes an oxidation reaction (lithium removal) and the cathode undergoes a reduction reaction (lithium insertion). In this process, the anions (Cl - ) will cross the middle anion exchange membrane and migrate into the recovery liquid.

[0005] For an ideal lithium extraction reaction, the cathode will also embed a lithium ion while the anode releases a lithium ion. However, in the actual reaction process, the cathode lithium embedding process is affected by the viscosity of the brine and the lithium ion concentration in the solution, resulting in the cathode lithium embedding process being slower than the anode lithium removal process, leading to a mismatch between the lithium removal and lithium embedding capacities of the cathode and anode. In particular, when the operating voltage is increased, the difference in the rate of lithium removal and embedding of the cathode and anode increases. When using the LiFePO4-FePO4 system for lithium extraction, because the two electrodes need to constantly exchange the electrode polarity, this determines that the electrode materials coated on the cathode and anode need to be as consistent as possible, and therefore it is impossible to design the capacity matching of the cathode and anode by improving the electrodes. CN115818801A discloses a method for using the Pb-FePO4 system for lithium extraction by electro-deintercalation. FePO4 is used as the cathode and Pb as the anode to adsorb lithium in the brine, and then the brine is replaced to remove lithium ions. This can make the capacity matching of the lithium removal and embedding of the cathode and anode more matched, but the lithium extraction process needs to be divided into two steps of lithium embedding and deintercalation, which complicates the lithium extraction process and affects the efficiency of lithium extraction.

[0006] In view of this, the present disclosure is proposed.

[0007] Summary of the Invention

[0008] The purpose of the present disclosure includes providing the use of lithium ferrocyanide in preparing an anolyte for lithium electro-deintercalation and extraction from salt lake brine.

[0009] The purpose of the present disclosure includes providing the use of lithium ferrocyanide in preparing an anolyte for reducing the difference in lithium deintercalation rates between the cathode and the anode in the electro-deintercalation of lithium from lake brine.

[0010] The present disclosure also aims to provide an anolyte for lithium electrolysis and deintercalation from salt lake brine.

[0011] The present disclosure also aims to provide a method for extracting lithium from salt lake brine by electro-deintercalation.

[0012] The present invention also aims to provide a method for recovering salt lake brine.

[0013] In order to achieve at least one of the above-mentioned objectives of the present disclosure, the following technical solutions may be adopted:

[0014] In a first aspect, the present disclosure provides the use of lithium ferrocyanide in preparing an anolyte for lithium electro-deintercalation and extraction from salt lake brine.

[0015] In a second aspect, the present disclosure provides the use of lithium ferrocyanide in the preparation of an anolyte for reducing the difference in lithium deintercalation rates between the cathode and the anode in the electro-deintercalation of lithium from lake brine.

[0016] In some embodiments of the present disclosure, the lithium ferrocyanide is added to the anode chamber of a salt lake brine electro-deintercalation lithium extraction system.

[0017] In some embodiments of the present disclosure, the concentration of the lithium ferrocyanide in the anolyte is 0.05-1 mol / L.

[0018] In some embodiments of the present disclosure, the concentration of the lithium ferrocyanide in the anolyte is 0.2-0.5 mol / L.

[0019] In some embodiments of the present disclosure, the anolyte further comprises a supporting electrolyte.

[0020] In some embodiments of the present disclosure, the supporting electrolyte includes lithium chloride.

[0021] In some embodiments of the present disclosure, the concentration of lithium chloride in the anolyte is 40-60 mmol / L.

[0022] In a third aspect, the present disclosure provides an anolyte for lithium electrolysis and deintercalation from salt lake brine, the components of which include lithium ferrocyanide.

[0023] In some embodiments of the present disclosure, the concentration of the lithium ferrocyanide in the anolyte is 0.05-1 mol / L.

[0024] In some embodiments of the present disclosure, the components further include a supporting electrolyte.

[0025] In some embodiments of the present disclosure, the supporting electrolyte includes lithium chloride.

[0026] In some embodiments of the present disclosure, the concentration of lithium chloride in the anolyte is 40-60 mmol / L.

[0027] In a fourth aspect, the present disclosure provides a method for extracting lithium from salt lake brine by electro-deintercalation, comprising:

[0028] A salt lake brine electro-deintercalation and lithium extraction device is used to electro-deintercalate and extract lithium from salt lake brine. The salt lake brine electro-deintercalation and lithium extraction device comprises an electrolytic cell, an anion exchange membrane, an anode and a cathode. The anion exchange membrane is placed in the electrolytic cell to vertically divide the electrolytic cell into a cathode chamber and an anode chamber. The anode is placed in the anode chamber, and the cathode is placed in the cathode chamber.

[0029] A voltage is applied to the cathode and the anode to perform electro-deintercalation and lithium extraction. During the electro-deintercalation and lithium extraction process, the anode chamber is filled with the anode electrolyte for electro-deintercalation and lithium extraction of salt lake brine according to any of the aforementioned embodiments.

[0030] In some embodiments of the present disclosure, the lithium ferrocyanide is added to the anode chamber before or during the process of lithium electro-deintercalation.

[0031] In some embodiments of the present disclosure, the voltage applied to the cathode and the anode is 0.4-0.8V.

[0032] In some embodiments of the present disclosure, the time for the lithium electrolysis is 2-6 hours.

[0033] In some embodiments of the present disclosure, after the lithium electro-deintercalation is completed, the positions of the cathode and the anode are swapped, voltage is applied, and the above steps are repeated until lithium is enriched from the cathode chamber to the anode chamber to form a lithium-rich solution.

[0034] In some embodiments of the present disclosure, the concentration of lithium in the lithium-rich solution is 3.5-4.1 g / L.

[0035] In some embodiments of the present disclosure, the salt lake brine includes lithium-containing brine.

[0036] In some embodiments of the present disclosure, the salt lake brine includes one or more of sulfate brine, chloride brine and carbonate brine.

[0037] In some embodiments of the present disclosure, the cathode comprises FePO4, Li 1-x Mn2O4、Li 1-x Ni 1 / 3 Co 1 / 3 Mn 1 / 3 O2 and Li 7-x Ti5O 12 At least one of .

[0038] In some embodiments of the present disclosure, the anode comprises LiFePO4, LiMn2O4, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 and Li7Ti5O 12 At least one of .

[0039] In a fifth aspect, the present disclosure provides a method for resource recovery of salt lake brine, which includes the method for electro-deintercalation and lithium extraction of salt lake brine as described in any of the above embodiments.

[0040] Compared with the prior art, the advantages of the present invention include:

[0041] Since the lithium extraction reaction is carried out using the LiFePO4-FePO4 electrode system in the "rocking chair" type electrochemical lithium extraction system, the lithium de-lithiation rate of LiFePO4 is significantly faster than the lithium insertion rate of FePO4. The greater the difference in the lithium de-insertion rate of the cathode and anode, the greater the mismatch between the lithium insertion and de-lithiation capacity, especially when processing low-concentration lithium-containing solutions. The present disclosure provides a new application of lithium ferrocyanide, by adding lithium ferrocyanide Li4Fe(CN)6 as the anolyte into the anode chamber, as the electrical de-insertion time increases, the Li4Fe(CN)6 in the anode chamber undergoes an oxidation reaction when the power is on, and Fe(CN6) 4- →Fe(CN6) 3- , resulting in a reduction in the amount of lithium ions released from the anode, ensuring that the cathode FePO4 can fully embed lithium, fully ensuring the adsorption capacity of the electrode, reducing the capacity mismatch problem, and improving the lithium recovery rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0043] FIG1 is a diagram showing the working principle of the method for extracting lithium from salt lake brine by electro-deintercalation provided in the present disclosure. DETAILED DESCRIPTION

[0044] The embodiments of the present disclosure will be described in detail below with reference to the examples. However, those skilled in the art will appreciate that the following examples are intended only to illustrate the present disclosure and should not be construed as limiting the scope of the present disclosure. Where specific conditions are not specified in the examples, the experiments were performed under conventional conditions or the conditions recommended by the manufacturer. Where the manufacturer of the reagents or instruments is not specified, all are commercially available conventional products.

[0045] The endpoints of the ranges and any values ​​disclosed in this disclosure are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed herein.

[0046] In a first aspect, the present disclosure provides a new application of lithium ferrocyanide. Specifically, the present disclosure provides an application of lithium ferrocyanide in preparing an anolyte for lithium electro-deintercalation and extraction from salt lake brine.

[0047] In the present disclosure, lithium ferrocyanide was purchased from the market, and the manufacturer was Hunan Hanrun Materials Development Co., Ltd. The present disclosure found that when lithium ferrocyanide is added to the anode chamber as the anode electrolyte in the electro-deintercalation and lithium extraction of lake brine, it can undergo an oxidation reaction during the electro-deintercalation process to reduce the amount of lithium ions released from the anode, thereby reducing the difference in lithium deintercalation rates between the cathode and the anode, and at the same time reducing the capacity difference between lithium deintercalation and lithium insertion.

[0048] In the present disclosure, lithium ferrocyanide is dissolved in the solution in the anode chamber to form a lithium ferrocyanide solution. The concentration of lithium ferrocyanide in the anolyte is 0.05-1 mol / L, optionally, the concentration of lithium ferrocyanide in the anolyte is 0.2-0.5 mol / L. In certain embodiments, the concentration of lithium ferrocyanide in the anolyte can be, for example, any one of 0.05 mol / L, 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, or a range between any two of them.

[0049] In this regard, the present application also provides an anolyte for lithium electro-deintercalation from salt lake brine, the components of which include lithium ferrocyanide. The concentration of lithium ferrocyanide in the anolyte is 0.05-1 mol / L. In some embodiments, the concentration of lithium ferrocyanide in the anolyte can be, for example, any one of 0.05 mol / L, 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, or a range value between any two of them.

[0050] In certain embodiments, the components further include a supporting electrolyte, the supporting electrolyte includes lithium chloride, and the concentration of lithium chloride in the anolyte is 40-60 mmol / L.

[0051] Corresponding to the above application, the present disclosure further provides a method for extracting lithium from salt lake brine by electro-deintercalation, which comprises the following steps:

[0052] S1. Formation of electrode system.

[0053] The anode and cathode are selected to form an electrode system, and the electrolytic cell is vertically divided into a cathode chamber and an anode chamber using an anion exchange membrane.

[0054] The present disclosure can be applied to a variety of electrode systems, including but not limited to LiFePO4 / FePO4, LiMn2O4 / Li 1-x Mn2O4、LiNi 1 / 3 Co1 / 3 Mn 1 / 3 O2 / Li 1-x Ni 1 / 3 Co 1 / 3 Mn 1 / 3 O2、Li7Ti5O 12 / Li 7-x Ti5O 12 Etc. Specifically, the cathode includes FePO4, Li 1-x Mn2O4、Li 1-x Ni 1 / 3 Co 1 / 3 Mn 1 / 3 O2 and Li 7-x Ti5O 12 At least one of, wherein x represents a lithium-deficient state. The anode includes LiFePO4, LiMn2O4, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 and Li7Ti5O 12 In the present disclosure, the anion exchange membrane is a monovalent selective anion exchange membrane, which is commercially available from Suzhou Shengernuo Technology Co., Ltd.

[0055] S2. Adding the solution.

[0056] Salt lake brine to be extracted with lithium is added to the cathode chamber, and supporting electrolyte and lithium ferrocyanide are added to the anode chamber. The lithium ferrocyanide can be added to the anode chamber before or during the start of the electro-deintercalation and lithium extraction.

[0057] The salt lake brine can be any lithium-containing salt lake brine, mainly targeting brine with a high magnesium-lithium ratio. Salt lake brine includes but is not limited to one or more of sulfate brine, chloride brine and carbonate brine. In some embodiments of the present disclosure, the composition of the salt lake brine includes 0.21-0.47g / L Li + 、69.3g / L Na + 、111.20g / L Mg 2+ 、6.43g / LK + , 2.99g / L Ca 2+ 、8.24g / L SO4 2- .

[0058] The supporting electrolyte includes lithium chloride, and the concentration of lithium chloride is 40-60 mmol / L.

[0059] The concentration of the lithium ferrocyanide solution is 0.05-1 mol / L. In some embodiments, the concentration of the lithium ferrocyanide solution can be, for example, any one of 0.05 mol / L, 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, or a range between any two of them.

[0060] S3. Electrodeintercalation and lithium extraction.

[0061] Applying a voltage to the cathode and anode to perform lithium electrolysis and deintercalation. The applied voltage is 0.4-0.8V and the time for lithium electrolysis and deintercalation is 2-6 hours.

[0062] In certain embodiments, the applied voltage may be, for example, any one of 0.4 V, 0.5 V, 0.6 V, 0.7 V, and 0.8 V, or a range between any two thereof. The time for lithium electrolysis and deintercalation is any one of 2 h, 3 h, 4 h, 5 h, and 6 h, or a range between any two thereof.

[0063] S4. Exchange electrode positions.

[0064] After the lithium extraction is completed, the positions of the cathode and anode are swapped, voltage is applied, and the above steps are repeated until lithium is enriched from the cathode chamber to the anode chamber to form a lithium-rich solution with a lithium concentration of 3.5-4.1 g / L.

[0065] Please refer to Figure 1. The lithium extraction process involved in the present disclosure mainly includes: under the action of the electric field, the LiFePO4 anode releases lithium ions into the anolyte (lithium ferrocyanide + supporting electrolyte) to form FePO4, and at the same time, the FePO4 cathode absorbs lithium ions in the lithium-containing brine to form LiFePO4; the anode and cathode are exchanged and the above process is repeated to enrich the lithium in the salt lake brine from the cathode chamber to the anode chamber. In the present disclosure, by adding lithium ferrocyanide to the anode chamber, as the electrical deintercalation time increases, the Li4Fe(CN)6 in the anode chamber undergoes an oxidation reaction when the power is turned on, and Fe(CN6) 4- →Fe(CN6) 3- , resulting in a reduction in the amount of lithium ions released from the anode, ensuring that the cathode FePO4 can fully embed lithium, fully ensuring the adsorption capacity of the electrode, reducing the capacity mismatch problem, and improving the lithium recovery rate.

[0066] The present disclosure provides a method for recovering salt lake brine resources, which includes the above-mentioned salt lake brine electro-deintercalation and lithium extraction method.

[0067] The features and performance of the present disclosure are further described in detail below with reference to the embodiments.

[0068] Example 1

[0069] This embodiment provides a method for extracting lithium from salt lake brine by electro-deintercalation, which comprises the following steps:

[0070] (1) LiFePO4 is used as the anode, and FePO4 after delithiation of LiFePO4 is used as the cathode. The anode and cathode are separated into cathode chamber and anode chamber by a monovalent selective anion exchange membrane.

[0071] (2) The cathode chamber is injected with salt lake brine to be extracted with lithium, and Li4Fe(CN)6 and supporting electrolyte (lithium chloride) are added to the anode chamber. The Li4Fe(CN)6 solution and lithium chloride are used together as the anode electrolyte.

[0072] The composition of brine is: 0.47g / L Li + 、69.3g / L Na + 、111.20g / L Mg 2+ 、6.43g / LK + , 2.99g / L Ca 2+ 、8.24g / L SO4 2- .

[0073] The concentration of Li4Fe(CN)6 in the anolyte is 0.3 mol / L, and the concentration of lithium chloride is 50 mmol / L.

[0074] (3) A voltage of 0.6 V was applied across the cathode and anode, and the electrical deintercalation time was 4 h.

[0075] (4) At the end of the reaction, after the two electrodes have completed their corresponding insertion / extraction processes, the two electrodes are swapped and the above process is repeated once. The reaction is stopped when the current drops to 0.3 mA, and lithium is enriched from the cathode chamber to the anode chamber to form a lithium-rich solution.

[0076] Example 2

[0077] This embodiment provides a method for extracting lithium from salt lake brine by electro-deintercalation, which comprises the following steps:

[0078] (1) LiFePO4 is used as the anode, and FePO4 after delithiation of LiFePO4 is used as the cathode. The anode and cathode are separated into cathode chamber and anode chamber by a monovalent selective anion exchange membrane.

[0079] (2) The cathode chamber is injected with salt lake brine to be extracted with lithium, and Li4Fe(CN)6 and supporting electrolyte (lithium chloride) are added to the anode chamber. The Li4Fe(CN)6 solution and lithium chloride are used together as the anode electrolyte.

[0080] The composition of brine is: 0.47g / L Li +、69.3g / L Na + 、111.20g / L Mg 2+ 、6.43g / LK + , 2.99g / L Ca 2+ 、8.24g / L SO4 2- .

[0081] The concentration of Li4Fe(CN)6 in the anolyte is 0.5 mol / L, and the concentration of lithium chloride is 50 mmol / L.

[0082] (3) A voltage of 0.4 V was applied across the cathode and anode, and the electrical deintercalation time was 6 h.

[0083] (4) At the end of the reaction, after the two electrodes have completed their corresponding insertion / extraction processes, the two electrodes are swapped and the above process is repeated once. The reaction is stopped when the current drops to 0.3 mA, and lithium is enriched from the cathode chamber to the anode chamber to form a lithium-rich solution.

[0084] Example 3:

[0085] This embodiment provides a method for extracting lithium from salt lake brine by electro-deintercalation, which comprises the following steps:

[0086] (1) LiFePO4 is used as the anode, and FePO4 after delithiation of LiFePO4 is used as the cathode. The anode and cathode are separated into cathode chamber and anode chamber by a monovalent selective anion exchange membrane.

[0087] (2) The cathode chamber is injected with salt lake brine to be extracted with lithium, and Li4Fe(CN)6 and supporting electrolyte (lithium chloride) are added to the anode chamber. The Li4Fe(CN)6 solution and lithium chloride are used together as the anode electrolyte.

[0088] The composition of brine is: 0.47g / L Li + 、69.3g / L Na + 、111.20g / L Mg 2+ 、6.43g / LK + , 2.99g / L Ca 2+ 、8.24g / L SO4 2- .

[0089] The concentration of Li4Fe(CN)6 in the anolyte is 0.05 mol / L, and the concentration of lithium chloride is 50 mmol / L.

[0090] (3) A voltage of 0.8 V was applied across the cathode and anode, and the electrical deintercalation time was 2 h.

[0091] (4) At the end of the reaction, after the two electrodes have completed their corresponding insertion / extraction processes, the two electrodes are swapped and the above process is repeated once. The reaction is stopped when the current drops to 0.3 mA, and lithium is enriched from the cathode chamber to the anode chamber to form a lithium-rich solution.

[0092] Example 4:

[0093] This embodiment provides a method for extracting lithium from salt lake brine by electro-deintercalation, which comprises the following steps:

[0094] (1) LiFePO4 is used as the anode, and FePO4 after delithiation of LiFePO4 is used as the cathode. The anode and cathode are separated into cathode chamber and anode chamber by a monovalent selective anion exchange membrane.

[0095] (2) The cathode chamber is injected with salt lake brine to be extracted with lithium, and the anode chamber is added with lithium chloride solution as the anode electrolyte.

[0096] The composition of brine is: 0.47g / L Li + 、69.3g / L Na + 、111.20g / L Mg 2+ 、6.43g / LK + , 2.99g / L Ca 2+ 、8.24g / L SO4 2- .

[0097] The concentration of lithium chloride in the anolyte was 50 mmol / L.

[0098] (3) A voltage of 0.8 V was applied across the cathode and anode. After the electro-deintercalation reaction had proceeded for 3 h, Li4Fe(CN)6 was added to the anode chamber solution. The concentration of Li4Fe(CN)6 in the anode electrolyte was 0.35 mol / L, and electrolysis was continued for 1 h.

[0099] (4) At the end of the reaction, after the two electrodes have completed their corresponding insertion / extraction processes, the two electrodes are swapped and the above process is repeated once. The reaction is stopped when the current drops to 0.3 mA, and lithium is enriched from the cathode chamber to the anode chamber to form a lithium-rich solution.

[0100] Example 5

[0101] The difference between this embodiment and embodiment 1 is that the voltage applied for electrical deintercalation in step (3) is 0.4 V, and the other steps are the same as those in embodiment 1.

[0102] Example 6

[0103] The difference between this embodiment and embodiment 1 is that the voltage applied for electrical deintercalation in step (3) is 0.8 V, and the other steps are the same as those in embodiment 1.

[0104] Example 7

[0105] The difference between this embodiment and embodiment 1 is that the concentration of Li4Fe(CN)6 in step (3) is 0.1 mol / L, and the other steps are the same as those in embodiment 1.

[0106] Example 8

[0107] The difference between this embodiment and embodiment 1 is that the concentration of Li4Fe(CN)6 in step (3) is 0.2 mol / L, and the other steps are the same as those in embodiment 1.

[0108] Example 9

[0109] The difference between this embodiment and embodiment 1 is that the concentration of Li4Fe(CN)6 in step (3) is 0.4 mol / L, and the other steps are the same as those in embodiment 1.

[0110] Example 10

[0111] The difference between this embodiment and embodiment 1 is that the concentration of Li4Fe(CN)6 in step (3) is 0.5 mol / L, and the other steps are the same as those in embodiment 1.

[0112] Example 11

[0113] The difference between this embodiment and embodiment 1 is that the concentration of Li4Fe(CN)6 in step (3) is 0.6 mol / L, and the other steps are the same as those in embodiment 1.

[0114] Example 12

[0115] The difference between this embodiment and embodiment 1 is that the concentration of Li4Fe(CN)6 in step (3) is 0.8 mol / L, and the other steps are the same as those in embodiment 1.

[0116] Example 13

[0117] The difference between this embodiment and embodiment 1 is that the concentration of Li4Fe(CN)6 in step (3) is 1 mol / L, and the other steps are the same as those in embodiment 1.

[0118] Example 14

[0119] The difference between this embodiment and embodiment 1 is that the concentration of lithium chloride in step (3) is 40 mol / L, and the other steps are the same as those in embodiment 1.

[0120] Example 15

[0121] The difference between this embodiment and embodiment 1 is that the concentration of lithium chloride in step (3) is 60 mol / L, and the other steps are the same as those in embodiment 1.

[0122] Example 16

[0123] The difference between this embodiment and embodiment 1 is that in step (1), LiMn2O4 is the anode, Li 1-x Mn2O4 is used as the cathode, and the other steps are the same as those in Example 1.

[0124] Example 17

[0125] The difference between this embodiment and embodiment 1 is that the composition of the brine in step (2) is: 0.47g / L Li + 、69.3g / L Na + 、111.20g / L Mg 2+ 、6.43g / LK + , 2.99g / L Ca 2+ 、8.24g / L SO4 2- .

[0126] Comparative Example 1

[0127] This comparative example is basically the same as Example 1, except that, in step (3) of this comparative example, Li4Fe(CN)6 is not added to the anode chamber, and only lithium chloride solution (the concentration of lithium chloride is 50 mmol / L) is added. The other steps are the same as Example 1.

[0128] Comparative Example 2

[0129] This comparative example is basically the same as Example 1, except that, in step (3) of this comparative example, only Li4Fe(CN)6 is added to the anode chamber, wherein the concentration of Li4Fe(CN)6 is 0.3 mol / L, and no lithium chloride solution is added. The other steps are the same as Example 1.

[0130] Comparative Example 3

[0131] This comparative example is basically the same as Example 1, except that in step (3) of this comparative example, the concentration of Li4Fe(CN)6 added to the anode chamber is 0.01 mol / L.

[0132] Comparative Example 4

[0133] This comparative example is basically the same as Example 1, except that in step (3) of this comparative example, the concentration of Li4Fe(CN)6 added to the anode chamber is 1.5 mol / L.

[0134] Comparative Example 5

[0135] The difference between this embodiment and embodiment 1 is that the voltage applied for electrical deintercalation in step (3) is 0.2 V, and the other steps are the same as those in embodiment 1.

[0136] Comparative Example 6

[0137] The difference between this embodiment and embodiment 1 is that the voltage applied for electrical deintercalation in step (3) is 1.0 V, and the other steps are the same as those in embodiment 1.

[0138] Comparative Example 7

[0139] This comparative example is basically the same as Example 1, except that in step (3) of this comparative example, Li4Fe(CN)6 is added to the anode chamber instead of potassium sulfate.

[0140] Performance testing:

[0141] The main indicators of lithium extraction obtained after lithium extraction experiments on the electrodes obtained in the examples and comparative examples are shown in the following table.

[0142] Wherein, the calculation method of lithium recovery rate is (C0-C e ) / C0×100%. C0 is the initial brine lithium ion concentration, measured in g / L; C e It is the lithium ion concentration of brine after electrolysis, and the unit of measurement is g / L.

[0143] The concentration of the obtained lithium-rich solution is calculated by direct detection.

[0144] The calculation method of electrode adsorption capacity is adsorption capacity q = V (C0-C e ) / m. V is the volume of brine, with a unit volume of 1L; C0 is the initial lithium ion concentration of brine, with a unit of g / L; C e is the lithium ion concentration of brine after electrolysis, and the unit of measurement is g / L; m is the mass of the electrode material, and the unit weight is 1g.

[0145] From Example 1, Examples 5-6 and Comparative Examples 5 and 6, it can be found that when the voltage is too large or too small, the adsorption capacity of the electrode is reduced. This is because the voltage is too small, the lithium extraction efficiency of the electrode is too low, and the voltage is too large, which leads to the adsorption of Fe(CN6). 3- Oxidation has a strong inhibitory effect on lithium extraction.

[0146] It can be seen from Example 1, Examples 7-13 and Comparative Examples 3-4 that when the concentration of Li4Fe(CN)6 is controlled at 0.2-0.5 mol / L, it is more conducive to increasing the adsorption capacity of the electrode.

[0147] It can be seen from Example 1 and Examples 14-15 that when the concentration of lithium chloride is within the range disclosed herein, the lithium extraction indicators are not much different.

[0148] It can be seen from Example 1 and Examples 16-17 that the method provided by the present disclosure is applicable to a variety of electrode systems and a variety of brines.

[0149] It can be seen from Example 1 and Comparative Example 1 that adding Li4Fe(CN)6 to the recovery liquid can significantly increase the adsorption capacity of the electrode, thereby increasing the concentration of lithium in the recovery liquid and improving the lithium recovery rate. This shows that adding Li4Fe(CN)6 to the anode can ensure the embedding amount of the cathode ion sieve, thereby making the capacity of the anode and cathode lithium deintercalation more matched and improving the lithium extraction efficiency.

[0150] It can be seen from Example 1 and Comparative Example 2 that when only Li4Fe(CN)6 is used as the anolyte, the ionization equilibrium constant of Li4Fe(CN)6 alone is not high, resulting in a lithium extraction index significantly lower than that in Example 1. In the embodiment, using Li4Fe(CN)6 and a supporting electrolyte together as the anolyte can improve the conductivity of the solution, thereby increasing the lithium extraction efficiency.

[0151] It can be seen from Example 1 and Comparative Example 7 that when other reagents are selected to replace Li4Fe(CN)6, the effect is significantly worse than that of Example 1.

[0152] In summary, in the "rocking chair" type electrochemical lithium extraction system, the lithium extraction reaction is carried out using the LiFePO4-FePO4 electrode system. The lithium de-lithiation rate of LiFePO4 is significantly faster than the lithium insertion rate of FePO4. The greater the difference in the lithium de-insertion rate of the cathode and anode, the greater the mismatch between the lithium insertion and de-lithiation capacity. This is particularly prominent when processing low-concentration lithium-containing solutions. The present disclosure provides a new application of lithium ferrocyanide. By adding lithium ferrocyanide Li4Fe(CN)6 as the anolyte into the anode chamber, as the electrical de-insertion time increases, the Li4Fe(CN)6 in the anode chamber undergoes an oxidation reaction when powered on, and Fe(CN6) 4- →Fe(CN6) 3- , resulting in a reduction in the amount of lithium ions released from the anode, ensuring that the cathode FePO4 can fully embed lithium, fully ensuring the adsorption capacity of the electrode, reducing the capacity mismatch problem, and improving the lithium recovery rate.

[0153] The above describes in detail the optional embodiments of the present disclosure, but the present disclosure is not limited thereto. Within the technical concept of the present disclosure, various simple variations of the technical solution of the present disclosure can be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as the contents disclosed by the present disclosure and fall within the scope of protection of the present disclosure. Industrial Applicability

[0154] Since the lithium extraction reaction is carried out using the LiFePO4-FePO4 electrode system in the "rocking chair" type electrochemical lithium extraction system, the lithium de-lithiation rate of LiFePO4 is significantly faster than the lithium insertion rate of FePO4. The greater the difference in the lithium de-insertion rate of the cathode and anode, the greater the mismatch between the lithium insertion and de-lithiation capacity, especially when processing low-concentration lithium-containing solutions. The present disclosure provides a new application of lithium ferrocyanide, by adding lithium ferrocyanide Li4Fe(CN)6 as the anolyte into the anode chamber, as the electrical de-insertion time increases, the Li4Fe(CN)6 in the anode chamber undergoes an oxidation reaction when the power is on, and Fe(CN6) 4- →Fe(CN6) 3- , resulting in a reduction in the amount of lithium ions released from the anode, ensuring that the cathode FePO4 can fully embed lithium, fully ensuring the adsorption capacity of the electrode, reducing the capacity mismatch problem, and improving the lithium recovery rate.

Claims

1. Application of lithium ferrocyanate in the preparation of anolyte for lithium electrolysis and extraction from salt lake brine.

2. The application of lithium ferrocyanate in the preparation of an anolyte for reducing the difference in lithium deintercalation rates between the cathode and anode in the electro-deintercalation of lithium from lake brine.

3. The use according to claim 1 or 2, characterized in that: The lithium ferrocyanide is added into the anode chamber of the salt lake brine electro-deintercalation lithium extraction system.

4. The use according to claim 1 or 2, characterized in that: The concentration of the lithium ferrocyanate in the anolyte is 0.05-1 mol / L.

5. The use according to claim 1 or 2, characterized in that: The concentration of the lithium ferrocyanate in the anolyte is 0.2-0.5 mol / L.

6. The use according to claim 1 or 2, characterized in that: The anolyte also includes a supporting electrolyte.

7. The use according to claim 6, characterized in that: The supporting electrolyte includes lithium chloride.

8. The use according to claim 7, characterized in that: The concentration of the lithium chloride in the anolyte is 40-60 mmol / L.

9. An anolyte for lithium extraction from salt lake brine, characterized in that: Its components include lithium ferrocyanate.

10. The anolyte for lithium extraction from salt lake brine according to claim 9, characterized in that: The concentration of the lithium ferrocyanate in the anolyte is 0.05-1 mol / L.

11. The anolyte for lithium extraction from salt lake brine according to any one of claims 9 to 10, characterized in that: The components also include a supporting electrolyte.

12. The anolyte for lithium extraction from salt lake brine according to claim 11, characterized in that: The supporting electrolyte includes lithium chloride.

13. The anolyte for lithium extraction from salt lake brine according to claim 12, characterized in that: The concentration of the lithium chloride in the anolyte is 40-60 mmol / L.

14. A method for extracting lithium from salt lake brine by electro-deintercalation, characterized in that: It includes: The salt lake brine is subjected to electro-deintercalation and lithium extraction by using a salt lake brine electro-deintercalation and lithium extraction device, the salt lake brine electro-deintercalation and lithium extraction device comprising an electrolytic cell, an anion exchange membrane, an anode and a cathode, the anion exchange membrane is placed in the electrolytic cell to vertically divide the electrolytic cell into a cathode chamber and an anode chamber, the anode is placed in the anode chamber, and the cathode is placed in the cathode chamber; A voltage is applied to the cathode and the anode to perform electro-deintercalation and lithium extraction. During the electro-deintercalation and lithium extraction process, the anode chamber is filled with an anode electrolyte for electro-deintercalation and lithium extraction from salt lake brine as described in any one of claims 9 to 13.

15. The method for extracting lithium from salt lake brine by electro-deintercalation according to claim 14, characterized in that: The lithium ferrocyanate is added into the anode chamber before or during the process of lithium electrolysis and deintercalation.

16. The method for extracting lithium from salt lake brine by electro-deintercalation according to any one of claims 14 to 15, characterized in that: The voltage applied to the cathode and the anode is 0.4-0.8V.

17. The method for extracting lithium from salt lake brine by electro-deintercalation according to any one of claims 14 to 16, characterized in that: The time for the lithium extraction by electro-deintercalation is 2-6 hours.

18. The method for extracting lithium from salt lake brine by electro-deintercalation according to any one of claims 14 to 17, characterized in that: After the lithium extraction is completed, the cathode and the anode are swapped, a voltage is applied, and the above steps are repeated until lithium is enriched from the cathode chamber to the anode chamber to form a lithium-rich solution.

19. The method for extracting lithium from salt lake brine by electro-deintercalation according to claim 18, characterized in that: The concentration of lithium in the lithium-rich solution is 3.5-4.1 g / L.

20. The method for extracting lithium from salt lake brine by electro-deintercalation according to any one of claims 14 to 19, characterized in that: The salt lake brine includes lithium-containing brine.

21. The method for extracting lithium from salt lake brine by electro-deintercalation according to any one of claims 14 to 20, characterized in that: The salt lake brine includes one or more of sulfate brine, chloride brine and carbonate brine.

22. The method for extracting lithium from salt lake brine by electro-deintercalation according to any one of claims 14 to 21, characterized in that: The cathode includes FePO4, Li 1-x Mn2O4、Li 1-x Ni 1 / 3 Co 1 / 3 Mn 1 / 3 O2 and Li 7-x Ti5O 12 At least one of .

23. The method for extracting lithium from salt lake brine by electro-deintercalation according to any one of claims 14 to 22, characterized in that: The anode includes LiFePO4, LiMn2O4, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 and Li7Ti5O 12 At least one of .

24. A method for recovering lithium from salt lake brine, characterized in that: It includes the method for extracting lithium from salt lake brine by electro-deintercalation according to any one of claims 14 to 23.

Images