A method for lithium extraction by electrochemical deintercalation

Abstract

The present disclosure provides a method for lithium extraction by electrochemical deintercalation, belonging to the technical field of electrochemical deintercalation lithium extraction. The method comprises: adding a lithium extraction solution containing Li + and Mg 2+ into the cathode chamber of an electrochemical deintercalation lithium extraction device, and the Mg(OH)2 in the lithium extraction solution reaches a near-saturated concentration; the electrochemical deintercalation lithium extraction device further comprises an anode chamber, and an anion exchange membrane is arranged between the anode chamber and the cathode chamber; the cathode chamber has a cathode containing lithium ion sieves in a lithium-lean state, and the anode chamber has an anode containing lithium ion sieves in a lithium-intercalated state; electricity is supplied and the voltage is kept unchanged, so that the lithium ion sieves in the lithium-lean state adsorb Li + ; the electricity supply is stopped, the positions of the anode and the cathode are exchanged, the electricity supply is continued and the voltage is kept unchanged, so that the lithium ion sieves in the lithium-intercalated state desorb Li + to obtain a lithium-rich solution.

Description

Technical Field

[0001] This disclosure relates to the field of electrochemical deintercalation and lithium extraction technology, and more specifically, to an electrochemical deintercalation and lithium extraction method. Background Technology

[0002] Lithium metal, due to its unique properties, has been widely used in various fields such as new energy, aerospace, and military industry. Lithium-ion batteries, as the most widely used new energy battery, are extensively used in mobile devices, electric vehicles, and energy storage. However, the uneven distribution of lithium resources and the difficulty of mining them limit the development of new energy batteries. Salt lake brines contain relatively abundant lithium resources; therefore, extracting lithium from salt lake brines has become a research hotspot.

[0003] Currently, the main processes used for lithium extraction from salt lakes include precipitation, adsorption, solvent extraction, electrochemical deintercalation / intercalation, and membrane separation. Among these, using manganese-based adsorbents to extract lithium from brine is a common method, but this method requires acidic aqueous solutions for desorption, resulting in high consumption of acid and alkali reagents and a complex process. Electrochemical deintercalation / intercalation has attracted researchers' attention due to its ease of operation, high efficiency, and environmental friendliness. However, during electrochemical lithium extraction, coexisting cations, especially magnesium ions, can significantly interfere with lithium extraction. Therefore, ensuring lithium extraction efficiency while avoiding cation repulsion effects has become a major challenge in electrochemical lithium extraction.

[0004] In view of this, this disclosure is hereby made. Summary of the Invention

[0005] The purpose of this disclosure is to provide an electrochemical deintercalation method for lithium extraction, which can effectively avoid or reduce the cation repulsion effect that occurs during the lithium extraction process and improve the lithium extraction efficiency.

[0006] This disclosure can be implemented as follows:

[0007] This disclosure provides an electrochemical deintercalation method for lithium extraction, comprising the following steps:

[0008] S1: The lithium solution to be extracted is added to the cathode chamber of the electrochemical lithium extraction device. The lithium solution to be extracted also contains Li. + and Mg 2+ Furthermore, the Mg(OH)2 concentration in the lithium extraction solution reaches near-saturation.

[0009] The electrochemical lithium extraction and extraction device also includes an anode chamber, with an anion exchange membrane between the anode chamber and the cathode chamber; the cathode chamber contains a cathode with a lithium-poor state lithium sieve, and the anode chamber contains an anode with a lithium-intercalated state lithium sieve;

[0010] S2: Apply electricity and maintain a constant voltage to induce a reduction reaction in the lithium-poor lithium-ion sieve, adsorbing Li from the lithium extraction solution. + ;

[0011] S3: Stop energizing, swap the positions of the anode and cathode, continue energizing and maintain the same voltage as in S2, causing the lithium-ion intercalated sieve to undergo an oxidation reaction to desorb Li. + After returning to a lithium-poor state, the desorbed lithium ions are used to form a lithium-rich solution in the anode chamber.

[0012] In an optional embodiment, Mg in the lithium extraction solution 2+ The concentration is 10 mmol / L-100 mmol / L, C Mg 2+ ×(C OH - ) 2 =1.60×10 -11 Up to 1.78×10 -11 .

[0013] In an optional embodiment, a recovery solution is added to the anode chamber to provide anions to form a lithium-rich solution together with the desorbed lithium ions.

[0014] In an optional embodiment, the recovered liquid includes at least one of a sulfate salt solution and a chloride salt solution.

[0015] In an optional embodiment, the chloride salt solution includes at least one of KCl solution and NaCl solution; and / or, the sulfate salt solution includes at least one of K2SO4 solution and Na2SO4 solution.

[0016] In an optional embodiment, the concentration of cations in the recovered solution is 0.2 mol / L to 1 mol / L.

[0017] In an optional implementation, in S3, after the lithium-depleted lithium-ion sieve changes from a lithium-depleted state to a lithium-rich state, the power supply is stopped and the positions of the anode and cathode are swapped.

[0018] In an optional implementation, the voltage in both S2 and S3 is 0.5V-1.0V. In S3, the power supply is stopped when the current drops to 0.2mA.

[0019] In an optional implementation, S2 and S3 are repeated 2-5 times.

[0020] In an optional embodiment, the lithium solution to be extracted is obtained by the following method.

[0021] The pH value of the lithium-containing solution is adjusted using a regulator to reduce the Mg content in the lithium-containing solution. 2+Mg(OH)2 is formed and reaches a near-saturation concentration to obtain the lithium extraction solution.

[0022] In an optional embodiment, the lithium-containing solution includes at least one of brine, seawater, waste battery leachate, lithium precipitation mother liquor, and lithium extraction leachate from ore.

[0023] In an optional embodiment, the regulator is one that can provide OH. - Soluble substances.

[0024] In an optional embodiment, the regulator includes at least one of sodium hydroxide, potassium hydroxide, and ammonia.

[0025] In an optional embodiment, in addition to adding the regulator, a flocculant is also added to the lithium-containing liquid.

[0026] In an optional embodiment, the flocculant includes at least one of starch, polyacrylamide, sodium polyacrylate, and sodium carboxymethyl cellulose.

[0027] In an optional embodiment, the amount of flocculant added to the lithium-containing liquid is 0.1 mg / L-5 mg / L.

[0028] In an optional embodiment, the lithium-ion screen includes at least one of lithium manganese phosphate, lithium titanate, lithium manganese oxide, lithium iron phosphate, and lithium manganese iron phosphate.

[0029] In an optional embodiment, the cathode is a first conductive current collector, which is loaded with a lithium-depleted lithium-ion sieve; and / or, the anode is a second conductive current collector, which is loaded with a lithium-intercalated lithium-ion sieve.

[0030] In an optional embodiment, the first conductive current collector includes at least one of titanium mesh, graphite plate, carbon cloth, carbon paper, aluminum foil, and copper foil; and / or, the second conductive current collector includes at least one of titanium mesh, graphite plate, carbon cloth, carbon paper, aluminum foil, and copper foil.

[0031] In an optional embodiment, a lithium-depleted lithium-ion sieve is coated onto the surface of a first conductive current collector; and / or, a lithium-intercalated lithium-ion sieve is coated onto the surface of a second conductive current collector.

[0032] This disclosure involves adjusting the Mg(OH)₂ concentration in the lithium extraction solution to near saturation before the electrochemical deintercalation process. This allows the Mg near the electrode to be reduced during the electrochemical deintercalation process. 2+ Enrichment, forming localized low supersaturation (when magnesium ions accumulate near the electrode, reaching a localized K0). sp >Magnesium hydroxide K spThis process causes the small magnesium hydroxide crystals formed on the electrode due to cation enrichment to dissolve and fuse with the magnesium hydroxide crystals in the solution, forming large magnesium hydroxide crystals that then settle. This avoids or prevents a very small amount of magnesium ions from being adsorbed onto the lithium-depleted lithium ion sieve, thus effectively avoiding the cation repulsion effect.

[0033] In S2, a reduction reaction is initiated in the lithium-poor lithium-ion sieve by connecting a power source, converting its high-valence metal ions into low-valence metal ions. Simultaneously, the Li in the lithium-extracting solution... + It is adsorbed onto the lithium-poor lithium-ion sieve. Because the Mg(OH)₂ concentration in the lithium extraction solution reaches near-saturation, it can form large magnesium hydroxide crystals and settle during the electrochemical deintercalation process, thereby increasing the Mg content near the electrode. 2+ Reduce concentration to avoid Mg 2+ For Li + It produces a cation repulsion effect.

[0034] In S3, the lithium-ion sieve in the lithium-intercalated state undergoes an oxidation reaction by connecting a power source, converting the corresponding low-valence metal ions into high-valence metal ions. Simultaneously, Li... + It is extracted and precipitated into the recovery solution. Because Li + Anions cannot pass through the anion exchange membrane, but anions on the lithium-to-lime solution side are attracted and can pass through the anion exchange membrane and enter the recovery solution. Therefore, Li + It can then be enriched in the recovery liquid.

[0035] The electrochemical deintercalation and intercalation lithium extraction method provided in this disclosure is simple to operate, can effectively avoid or reduce the cation repulsion effect that occurs during the lithium extraction process, improve lithium extraction efficiency, reduce costs, and is conducive to improving economic benefits. Attached Figure Description

[0036] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this disclosure and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a flowchart of the electrochemical deintercalation and extraction lithium extraction method disclosed herein. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions in the embodiments of this disclosure will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0039] The following is a detailed description of the electrochemical deintercalation and extraction method for lithium extraction provided in this disclosure.

[0040] This disclosure proposes an electrochemical deintercalation / intercalation method for lithium extraction. Please refer to [reference needed]. Figure 1 This includes the following steps:

[0041] S1: The lithium solution to be extracted is added to the cathode chamber of the electrochemical lithium extraction device. The lithium solution to be extracted also contains Li. + and Mg 2+ Furthermore, the Mg(OH)2 concentration in the lithium extraction solution reaches near saturation.

[0042] Mg in the above lithium solution 2+ The concentration can be, for example, between 10 mmol / L and 100 mmol / L, such as 10 mmol / L, 20 mmol / L, 30 mmol / L, 40 mmol / L, 50 mmol / L, 60 mmol / L, 70 mmol / L, 80 mmol / L, 90 mmol / L, or 100 mmol / L, or any other value within the range of 10 mmol / L to 100 mmol / L. That is, the method provided in this disclosure, compared to other Mg... 2+ The concentration range is more suitable for Mg 2+ The concentration ranges from 10 mmol / L to 100 mmol / L to demonstrate a more pronounced effect in avoiding cation repulsion.

[0043] Furthermore, in some other embodiments, Mg in the lithium solution to be extracted 2+ The concentration can be less than 10 mmol / L or greater than 100 mmol / L, but the Mg in the lithium extraction solution... 2+ The concentration of Mg is less than 10 mmol / L, and its cation repulsion effect is not significant; the Mg in the lithium extraction solution 2+ Concentrations greater than 100 mmol / L may increase processing difficulty and cost.

[0044] In this disclosure, the near-saturation concentration of Mg(OH)2 in the lithium extraction solution can be understood as the concentration of C in the lithium extraction solution being near saturation. Mg 2+ ×(C OH - ) 2 =1.60×10-11 Up to 1.78×10 -11 , where C OH - Corresponding to pH value, it can be directly measured using pH value measuring instruments, etc.

[0045] It should be noted that by adjusting the Mg(OH)₂ concentration in the lithium extraction solution to near saturation before the electrochemical deintercalation process, the Mg near the electrode can be reduced during the electrochemical deintercalation process. 2+ Enrichment, forming localized low supersaturation (when magnesium ions accumulate near the electrode, reaching a localized K0). sp >Magnesium hydroxide K sp This process causes the small magnesium hydroxide crystals formed on the electrode due to cation enrichment to dissolve and fuse with the magnesium hydroxide crystals in the solution, forming large magnesium hydroxide crystals that then settle. This avoids or prevents a very small amount of magnesium ions from being adsorbed onto the lithium-depleted lithium ion sieve, thus effectively avoiding the cation repulsion effect.

[0046] In some embodiments, the lithium extraction solution can be obtained by adjusting the pH value of the lithium-containing solution using a regulator to reduce the Mg content in the lithium-containing solution. 2+ Mg(OH)2 is formed and reaches a near-saturation concentration to obtain the lithium extraction solution.

[0047] For reference, the aforementioned lithium-containing solution may include at least one of brine, seawater, waste battery leachate, lithium precipitation mother liquor, and lithium extraction ore leachate.

[0048] The pH value of the lithium-containing solution is adjusted by a regulator (during this process, the pH value can be measured using a pH measuring instrument, thereby obtaining the corresponding C). OH - ), so that its corresponding C OH - Able to satisfy C Mg 2+ ×(C OH - ) 2 =1.60×10 -11 Up to 1.78×10 -11 .

[0049] For reference, the above-mentioned regulator is one that can provide OH - Soluble substances, such as at least one of sodium hydroxide, potassium hydroxide and ammonia water.

[0050] In some alternative embodiments, in addition to adding the regulator, a flocculant is also added to the lithium-containing liquid to further promote the sedimentation of magnesium hydroxide.

[0051] For reference, the flocculant may include at least one of starch, polyacrylamide, sodium polyacrylate, and sodium carboxymethyl cellulose. The amount of flocculant added to the lithium-containing solution may be 0.1 mg / L-5 mg / L, such as 0.1 mg / L, 0.5 mg / L, 1 mg / L, 1.5 mg / L, 2 mg / L, 2.5 mg / L, 3 mg / L, 3.5 mg / L, 4 mg / L, 4.5 mg / L, or 5 mg / L, or any other value within the range of 0.1 mg / L-5 mg / L.

[0052] If the amount of flocculant added is less than 0.1 mg / L, its effect on promoting the sedimentation of magnesium hydroxide is not obvious; if the amount of flocculant added exceeds 5 mg / L, it increases the cost and does not improve the lithium extraction efficiency.

[0053] In this paper, the electrochemical lithium extraction device is an electrolytic cell or electrolytic vessel. In addition to the cathode chamber mentioned above, it also includes an anode chamber. An anion exchange membrane is provided between the anode chamber and the cathode chamber (to allow only anions to be exchanged). The cathode chamber has a cathode (as the negative electrode) containing lithium-poor lithium ions, and the anode chamber has an anode (as the positive electrode) containing lithium-intercalated lithium ions.

[0054] In this document, the anion exchange membrane may, by way of example, include a benzyl anion exchange membrane, a polyester anion exchange membrane, a polypropylene anion exchange membrane, or a fluorocarbon-based anion exchange membrane, etc.

[0055] Lithium-ion sieves may, by way of example, include at least one of lithium manganese phosphate, lithium titanate, lithium manganese oxide, lithium iron phosphate, and lithium manganese iron phosphate.

[0056] The cathode is a first conductive current collector, which is loaded with a lithium-depleted lithium-ion sieve; the anode is a second conductive current collector, which is loaded with a lithium-intercalated lithium-ion sieve.

[0057] The first conductive current collector may include, for example, at least one of titanium mesh, graphite plate, carbon cloth, carbon paper, aluminum foil, and copper foil. Similarly, the second conductive current collector may also include, for example, at least one of titanium mesh, graphite plate, carbon cloth, carbon paper, aluminum foil, and copper foil.

[0058] In some embodiments, a lithium-depleted lithium-ion sieve can be coated onto the surface of a first conductive current collector. Similarly, a lithium-intercalated lithium-ion sieve can be coated onto the surface of a second conductive current collector.

[0059] In other embodiments, the lithium-ion sieve can be combined with the electrode in any other feasible manner.

[0060] In this paper, a recovery solution is also added to the anode chamber. The recovery solution is used to provide anions (such as Cl-). - or SO42- It forms a lithium-rich solution together with the desorbed lithium ions.

[0061] For reference, the recovered solution may include at least one of sulfate salt solution and chloride salt solution. The chloride salt solution may include at least one of KCl solution and NaCl solution. - It can combine with desorbed lithium ions to form a lithium-rich solution containing LiCl. The sulfate solution may include at least one of K₂SO₄ solution and Na₂SO₄ solution, SO₄²⁻ 2- It can combine with the desorbed lithium ions to form a lithium-rich solution containing Li2SO4.

[0062] In some embodiments, the concentration of cations in the recovered solution can be 0.2 mol / L to 1 mol / L, such as 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.8 mol / L, or 1 mol / L, or any other value within the range of 0.2 mol / L to 1 mol / L.

[0063] If the concentration of cations in the recovered solution is below 0.2 mol / L, it will allow them to react with Li. + Insufficient cathode atoms affect Li + The extraction rate; if the concentration of cations in the recovered solution is higher than 1 mol / L, it will easily increase the difficulty of subsequent impurity removal.

[0064] It should be noted that the structure and working principle of the electrochemical lithium extraction device not described in further detail in this disclosure can be referred to existing related technologies (such as CN107201452B, etc.), and will not be elaborated further here.

[0065] S2: Apply electricity and maintain a constant voltage to induce a reduction reaction in the lithium-poor lithium-ion sieve, adsorbing Li from the lithium extraction solution. + .

[0066] In the above process, the voltage can be 0.5V-1.0V, such as being constant at 0.5V, 0.6V, 0.7V, 0.8V, 0.9V or 1.0V, or any other value within the range of 0.5V-1.0V.

[0067] When the voltage is less than 0.5V, the lithium extraction rate is too slow and the lithium extraction efficiency is low; when the voltage is greater than 1.0V, side reactions such as water electrolysis will occur.

[0068] In S2, by connecting a power source (such as a DC power source), the lithium-poor lithium-ion sieve undergoes a reduction reaction, and the Fe it contains... 3+ or Mn 4+ High-valence metal ions are converted to Fe 2+ or Mn3+ Low-valence metal ions, and at the same time, Li in the lithium solution to be extracted. + It is adsorbed onto the lithium-poor lithium-ion sieve. Because the Mg(OH)₂ concentration in the lithium extraction solution reaches near-saturation, it can form large magnesium hydroxide crystals and settle during the electrochemical deintercalation process, thereby increasing the Mg content near the electrode. 2+ Reduce concentration to avoid Mg 2+ For Li + It produces a cation repulsion effect.

[0069] S3: Stop energizing, swap the positions of the anode and cathode, continue energizing and maintain the same voltage as in S2, causing the lithium-ion intercalated sieve to undergo an oxidation reaction to desorb Li. + After returning to a lithium-poor state, the desorbed lithium ions are used to form a lithium-rich solution in the anode chamber.

[0070] In S3, by connecting a power source (such as a DC power source), the lithium-ion sieve in the lithium-intercalated state undergoes an oxidation reaction, and the corresponding Fe... 2+ or Mn 3+ When low-valence metal ions are converted to Fe 3+ or Mn 4+ High-valence metal ions, at the same time, Li + It is extracted and precipitated into the recovery solution. Because Li + Anions (such as Cl-) cannot pass through the anion exchange membrane, while the anions on the side of the lithium extraction solution are... - (e.g.) are attracted and can pass through the anion exchange membrane and enter the recovery solution, therefore Li + It can then be enriched in the recovery liquid in the form of LiCl and other substances.

[0071] In some embodiments, once the lithium-depleted lithium-ion sieve changes from a lithium-depleted state to a lithium-rich state, the power supply can be stopped and the positions of the anode and cathode can be interchanged. Based on the voltage and ion concentration in the lithium extraction solution discussed herein, in some specific embodiments, the power supply can be stopped when the current is as low as 0.2 mA. Under this current condition, the lithium-depleted lithium-ion sieve discussed herein essentially achieves the transformation from a lithium-depleted state to a lithium-rich state.

[0072] In some implementations, the entire electrochemical lithium extraction process (S2 and S3) can be repeated 2-5 times, such as 2, 3, 4, or 5 times. Alternatively, it is possible to perform the process only once or more than 5 times. Repeating S2 and S3 2-5 times can achieve higher lithium-ion extraction efficiency.

[0073] The features and performance of this disclosure will be further described in detail below with reference to embodiments.

[0074] Example 1

[0075] This embodiment provides a method for extracting lithium through electrochemical deintercalation, which includes the following steps:

[0076] S1: Determination of Mg in lithium-containing brine 2+ The concentration (50 mmol / L) of the brine solution was adjusted to pH 9.27 using an ammonia solution, so that the Mg(OH)₂ reached a near-saturation concentration (C). Mg2+ ×(C OH -) 2 =1.7×10 -11 The lithium solution to be extracted was obtained.

[0077] The electrochemical lithium extraction and extraction device (electrolyte) used in this embodiment includes a cathode chamber and an anode chamber. An anion exchange membrane (polypropylene anion exchange membrane) is provided between the anode chamber and the cathode chamber to separate the cathode chamber and the anode chamber. The cathode chamber has an aluminum foil as the cathode, which is coated with a lithium-poor lithium ion sieve (lithium iron phosphate). The anode chamber has an aluminum foil as the anode, which is coated with a lithium-intercalated lithium ion sieve (lithium iron phosphate).

[0078] The lithium extraction solution, with Mg(OH)₂ reaching near-saturation concentration, was added to the cathode chamber, and the recovery solution (sodium chloride aqueous solution, containing Na₂) was added to the anode chamber. + (Concentration is 1 mol / L).

[0079] S2: Apply direct current and maintain a constant voltage of 0.7V to extract lithium, causing the lithium-poor lithium ion sieve to undergo a reduction reaction and adsorb Li from the lithium extraction solution. + The reaction stops when the current drops to 0.2mA.

[0080] S3: Reverse the cathode and anode, continue energizing and maintain the same voltage as in S2, causing the lithium-ion intercalated sieve to undergo an oxidation reaction to desorb Li. + After returning to a lithium-poor state, the desorbed lithium ions are enriched in the anode chamber.

[0081] S4: Repeat the above steps S2 and S3 three times to obtain a lithium-rich solution.

[0082] The lithium ion concentration in the final lithium-rich solution was measured to be 13.52 mmol / L.

[0083] Example 2

[0084] The only difference between this embodiment and Embodiment 1 is that 0.5 mg / L of flocculant (polyacrylamide) is added simultaneously with the addition of ammonia to the brine.

[0085] The final lithium-rich liquid obtained in this embodiment has a lithium ion concentration of 13.68 mmol / L.

[0086] Example 3

[0087] The only difference between this embodiment and Example 1 is that the Mg content in the lithium-containing solution (brine) is higher. 2+ The concentration was 10 mmol / L, and ammonia was added to bring Mg(OH)2 to a near-saturation concentration (C). Mg2+ ×(C OH -) 2 =1.65×10 -11 The lithium solution to be extracted was obtained.

[0088] The final lithium-rich liquid obtained in this embodiment has a lithium ion concentration of 13.47 mmol / L.

[0089] Example 4

[0090] The only difference between this embodiment and Example 1 is that the Mg content in the lithium-containing solution (brine) is higher. 2+ The concentration was 100 mmol / L, and ammonia was added to bring Mg(OH)2 to a near-saturation concentration (C). Mg2+ ×(C OH -) 2 =1.75×10 -11 The lithium solution to be extracted was obtained.

[0091] The final lithium-rich liquid obtained in this embodiment has a lithium ion concentration of 13.51 mmol / L.

[0092] Example 5

[0093] The only difference between this embodiment and Embodiment 1 is that the regulator is NaOH solution.

[0094] The final lithium-rich liquid obtained in this embodiment has a lithium ion concentration of 13.52 mmol / L.

[0095] Example 6

[0096] The only difference between this embodiment and Embodiment 1 is that the regulator is a KOH solution.

[0097] The final lithium-rich liquid obtained in this embodiment has a lithium ion concentration of 13.51 mmol / L.

[0098] Example 7

[0099] The only difference between this embodiment and Embodiment 1 is that the lithium-ion sieves loaded on both the cathode and anode are lithium manganese phosphate.

[0100] The final lithium-rich liquid obtained in this embodiment has a lithium ion concentration of 13.36 mmol / L.

[0101] Example 8

[0102] The only difference between this embodiment and Embodiment 1 is that the lithium-ion sieves loaded on both the cathode and anode are lithium titanate.

[0103] The final lithium-rich liquid obtained in this embodiment has a lithium ion concentration of 13.17 mmol / L.

[0104] Example 9

[0105] The only difference between this embodiment and Embodiment 1 is that the lithium-ion sieves loaded on both the cathode and anode are lithium manganese oxide.

[0106] The final lithium-rich liquid obtained in this embodiment has a lithium ion concentration of 13.28 mmol / L.

[0107] Example 10

[0108] The only difference between this embodiment and Embodiment 1 is that the lithium-ion sieves loaded on both the cathode and anode are lithium manganese iron phosphate.

[0109] The final lithium-rich liquid obtained in this embodiment has a lithium ion concentration of 13.27 mmol / L.

[0110] Example 11

[0111] The only difference between this embodiment and Embodiment 1 is that both the first and second conductive current collectors are titanium mesh. The final lithium-rich liquid obtained in this embodiment has a lithium ion concentration of 13.46 mmol / L.

[0112] Example 12

[0113] The only difference between this embodiment and Embodiment 1 is that both the first and second conductive current collectors are graphite plates.

[0114] The final lithium-rich liquid obtained in this embodiment has a lithium ion concentration of 13.42 mmol / L.

[0115] Example 13

[0116] The only difference between this embodiment and Embodiment 1 is that both the first and second conductive current collectors are carbon cloth.

[0117] The final lithium-rich liquid obtained in this embodiment has a lithium ion concentration of 13.38 mmol / L.

[0118] Example 14

[0119] The only difference between this embodiment and Embodiment 1 is that the recovered solution is a KCl aqueous solution, and the K in the KCl aqueous solution is... + The concentration is 0.2 mol / L.

[0120] The final lithium-rich liquid obtained in this embodiment has a lithium ion concentration of 13.41 mmol / L.

[0121] Example 15

[0122] The only difference between this embodiment and Embodiment 1 is that the recovered liquid is an aqueous solution of Na2SO4, and the Na in the aqueous solution of Na2SO4 is... + The concentration is 0.5 mol / L.

[0123] The final lithium-rich liquid obtained in this embodiment has a lithium ion concentration of 13.42 mmol / L.

[0124] Example 16

[0125] The only difference between this embodiment and Embodiment 1 is that the recovered liquid is an aqueous solution of K2SO4.

[0126] The final lithium-rich liquid obtained in this embodiment has a lithium ion concentration of 13.39 mmol / L.

[0127] Example 17

[0128] The only difference between this embodiment and Embodiment 2 is that the flocculant is starch.

[0129] The final lithium-rich liquid obtained in this embodiment has a lithium ion concentration of 13.63 mmol / L.

[0130] Example 18

[0131] The only difference between this embodiment and Embodiment 2 is that the flocculant is sodium polyacrylate.

[0132] The final lithium-rich liquid obtained in this embodiment has a lithium ion concentration of 13.61 mmol / L.

[0133] Example 19

[0134] The only difference between this embodiment and Embodiment 2 is that the flocculant is sodium carboxymethyl cellulose.

[0135] The final lithium-rich liquid obtained in this embodiment has a lithium ion concentration of 13.64 mmol / L.

[0136] Example 20

[0137] The only difference between this embodiment and Embodiment 2 is that the amount of flocculant added to the lithium-containing liquid is 0.1 mg / L.

[0138] The final lithium-rich solution obtained in this embodiment has a lithium ion concentration of 13.54 mmol / L.

[0139] Example 21

[0140] The only difference between this embodiment and Embodiment 2 is that the amount of flocculant added to the lithium-containing liquid is 5 mg / L.

[0141] The final lithium-rich solution obtained in this embodiment has a lithium ion concentration of 13.59 mmol / L.

[0142] Example 22

[0143] The only difference between this embodiment and Embodiment 2 is that the voltage is constant at 0.5V.

[0144] The final lithium-rich solution obtained in this embodiment has a lithium ion concentration of 13.38 mmol / L.

[0145] Example 23

[0146] The only difference between this embodiment and Embodiment 2 is that the voltage is constant at 1.0V.

[0147] The final lithium-rich solution obtained in this embodiment has a lithium ion concentration of 13.56 mmol / L.

[0148] Comparative Example 1

[0149] The difference between this comparative example and Example 1 is that the pH value of the lithium-containing solution was not adjusted before the electrochemical deintercalation treatment, and the lithium-containing solution (Mg(OH)2 not reaching near saturation concentration) was directly used as the lithium extraction solution for electrochemical deintercalation treatment.

[0150] The final lithium-rich liquid obtained in this comparative example had a lithium ion concentration of 10.49 mmol / L.

[0151] Comparative Example 2

[0152] The difference between this comparative example and Example 2 is that no regulator was added to the lithium-containing liquid during the preparation of the lithium extraction solution; only a flocculant was added.

[0153] The final lithium-rich liquid obtained in this comparative example had a lithium ion concentration of 9.11 mmol / L.

[0154] Comparative Example 3

[0155] The difference between this comparative example and Example 2 is that the amount of flocculant added to the lithium-containing liquid is 0.05 mg / L.

[0156] The final lithium-rich liquid obtained in this comparative example had a lithium ion concentration of 11.38 mmol / L.

[0157] In summary, the electrochemical deintercalation and intercalation lithium extraction method provided in this disclosure is simple to operate, can effectively avoid or reduce the cation repulsion effect that occurs during the lithium extraction process, improve lithium extraction efficiency, reduce costs, and is conducive to improving economic benefits.

[0158] The above are merely preferred embodiments of this disclosure and are not intended to limit this disclosure. Various modifications and variations can be made to this disclosure by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the scope of protection of this disclosure.

[0159] Industrial applicability

[0160] The electrochemical deintercalation and intercalation lithium extraction method provided in this disclosure is simple to operate, can effectively avoid or reduce the cation repulsion effect that occurs during the lithium extraction process, improve lithium extraction efficiency, reduce costs, and is conducive to improving economic benefits.

Claims

1. A method of electrochemically deintercalating lithium extraction, characterized by, The method comprises the following steps: S1: adding a solution to be lithium-extracted into a cathode chamber of an electrochemical deintercalation lithium-extraction device, the solution to be lithium-extracted containing Li + and Mg 2+ at the same time, and Mg(OH)2 in the solution to be lithium-extracted reaching a near-saturation concentration; The electrochemical lithium extraction device further comprises an anode chamber, and an anion exchange membrane is arranged between the cathode chamber and the anode chamber; the cathode chamber is provided with a cathode containing lithium ion sieve in a lithium-depleted state, and the anode chamber is provided with an anode containing lithium ion sieve in a lithium-intercalated state; S2: power on and keep the voltage unchanged, so that the lithium ion sieve in lithium-lean state occurs reduction reaction to adsorb Li in the solution to be extracted + ; S3: stop the power supply, exchange the positions of the anode and the cathode, continue the power supply and keep the same voltage as in S2, and make the lithium ion sieve in the lithium intercalation state undergo an oxidation reaction to desorb Li + After the lithium-poor state is recovered, the desorbed lithium ions are used to form a lithium-rich solution in the anode chamber.

2. The method of claim 1, wherein, The concentration of Mg in the solution to be used for extracting lithium 2+ is 10 mmol / L-100 mmol / L, =1.60×10 -11 to 1.78×10 -11 .

3. The method for lithium extraction according to claim 1 or 2, characterized in that, The anode chamber is provided with a recovery solution, and the recovery solution is used to provide anions to form a lithium-rich solution together with the desorbed lithium ions.

4. The method of claim 3, wherein the lithium is extracted by the step of, The recovery solution comprises at least one of a sulfate salt solution and a chloride salt solution.

5. The lithium extraction method according to claim 4, characterized in that, The chloride salt solution comprises at least one of a KCl solution and a NaCl solution; and / or, the sulfate salt solution comprises at least one of a K2SO4 solution and a Na2SO4 solution.

6. The method of claim 4 or 5, wherein the lithium is extracted by the step of, The concentration of the cations in the recovery solution is 0.2 mol / L-1 mol / L.

7. The lithium extraction method according to claim 1, characterized in that, In S3, when the lithium ion sieve in the lithium-depleted state changes to a lithium-rich state, the power supply is stopped, and the positions of the anode and the cathode are exchanged.

8. The lithium extraction method according to claim 7, characterized in that, The voltage in S2 and S3 is 0.5 V-1.0 V, and in S3, the power supply is stopped when the current is as low as 0.2 mA.

9. The method of claim 1, wherein, S2 and S3 are repeated 2-5 times as a whole.

10. The method of claim 1, wherein, The solution to be extracted is obtained by the following method: The pH value of the lithium-containing solution is adjusted by using an adjusting agent, so that Mg 2+ Mg(OH)2 is formed and a near-saturation concentration is reached, obtaining a solution to be treated for lithium.

11. The method of claim 10, wherein, The lithium-containing solution comprises at least one of brine, seawater, waste battery leaching solution, lithium precipitation mother liquor and ore lithium extraction leaching solution.

12. The method of claim 10, wherein, The modulator is a soluble substance that can provide OH - groups.

13. The method of claim 12, wherein, The adjusting agent comprises at least one of sodium hydroxide, potassium hydroxide and ammonia water.

14. The method of claim 10, wherein, The adjusting agent is added, and at the same time, a flocculating agent is added to the lithium-containing solution.

15. The method of claim 14, wherein, The flocculating agent comprises at least one of starch, polyacrylamide, polyacrylic acid sodium salt and carboxymethyl cellulose sodium salt.

16. The method of claim 14 or 15, wherein, The amount of the flocculating agent added to the lithium-containing solution is 0.1 mg / L-5 mg / L.

17. The method of claim 1, wherein, The lithium ion sieve comprises at least one of lithium manganese phosphate, lithium titanate, lithium manganate, lithium iron phosphate and lithium manganese iron phosphate.

18. The method of claim 1, wherein, The cathode is a first conductive current collector, and the first conductive current collector is loaded with lithium ion sieve in a lithium-depleted state; and / or, the anode is a second conductive current collector, and the second conductive current collector is loaded with lithium ion sieve in a lithium-intercalated state.

19. The method of claim 18, wherein, The first conductive current collector comprises at least one of titanium mesh, graphite plate, carbon cloth, carbon paper, aluminum foil and copper foil; and / or, the second conductive current collector comprises at least one of titanium mesh, graphite plate, carbon cloth, carbon paper, aluminum foil and copper foil.

20. The method of claim 19, wherein, The lithium ion sieve in the lithium-depleted state is loaded on the surface of the first conductive current collector by coating; and / or, the lithium ion sieve in the lithium-intercalated state is loaded on the surface of the second conductive current collector by coating.

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