Method for electrochemical deintercalation of lithium and applications

Abstract

The present disclosure relates to a method and application of electrochemical deintercalation lithium extraction, the method comprising the following steps: (1) constructing a lithium extraction electrolytic cell; (2) powering the electrolytic cell for lithium extraction, during the lithium extraction process, periodically increasing the voltage and applying ultrasonic waves to the electrolytic cell, completing the electrochemical deintercalation lithium extraction. By periodically increasing the voltage, a slight water electrolysis reaction occurs on the electrode plate during lithium extraction, generating micro-nano bubbles inside the electrode, which, combined with ultrasonic waves, can cause ultrasonic cavitation in the brine inside the electrode, disturbing the brine, promoting the flow of the brine, and unblocking the internal mass transfer channels blocked by impurities.

Description

Technical Field

[0001] This disclosure pertains to the field of lithium extraction technology from salt lakes, such as a method and application of electrochemical deintercalation and extraction of lithium. Background Technology

[0002] With economic development, lithium-ion batteries have attracted significant attention as a key component of clean energy initiatives. Lithium resources, considered a vital strategic and economic resource and hailed as the "energy metal of the 21st century," have seen a surge in global demand due to the rapid development of lithium-ion batteries, making lithium resource development a global focus. Approximately 80% of the world's lithium resources are stored in salt lake brines, but the low lithium concentration in these brines presents a significant challenge in extraction.

[0003] Currently, commonly used methods for lithium extraction from salt lakes include evaporation precipitation, electrodialysis, nanofiltration, ion exchange, and electrochemical adsorption. Among these, adsorption is a relatively effective method due to the characteristics of salt lake brine. However, the preparation of ion adsorbents is difficult, desorption requires acidic conditions, the production process is difficult to be continuous, and the lithium extraction efficiency is relatively low.

[0004] The electrochemical method for lithium extraction from salt lakes has attracted widespread attention from researchers due to its energy-saving, environmentally friendly, and simple operation characteristics.

[0005] CN 105600807A discloses a method for electrochemically extracting lithium salts from high magnesium-to-lithium ratio brine. In a LiCl solution, a LiMn2O4 working electrode and a titanium mesh counter electrode are connected to the positive and negative terminals of a power source for charging, which can extract lithium ions from LiMn2O4 to form a lithium ion sieve. Discharging the above electrode system in a high magnesium-to-lithium ratio brine can selectively embed lithium ions into the lithium ion sieve. The charge-discharge cycle is used to achieve electrochemical extraction of lithium salts.

[0006] CN 112645362A discloses a method for directly preparing lithium carbonate from chloride-type lithium-containing brine via electrochemical extraction. Using chloride-type lithium-containing brine as the electrolyte, a galvanic cell is constructed with a lithium-ion sieve electrode and a chloride-ion trapping electrode as the positive and negative electrodes, respectively. Discharging the galvanic cell embeds lithium ions from the brine into the lithium-ion sieve. Using a lithium salt recovery solution as the electrolyte, an electrolytic cell is constructed with the lithium-ion sieve electrode and an inert electrode as the anode and cathode, respectively. Charging the electrolytic cell extracts lithium ions into the lithium salt recovery solution. However, the brine has a complex composition, and impurities and foreign ions in the brine can enter the electrode interior, clogging the mass transfer channels and affecting the lithium extraction efficiency.

[0007] Therefore, it is urgent to address the problem of impurities in the brine entering the electrode and blocking the mass transfer channels in related technologies. Summary of the Invention

[0008] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of the claims.

[0009] In view of the problems existing in the related technologies, this disclosure provides an electrochemical lithium extraction and extraction method and application. The method involves periodically increasing the voltage. While extracting lithium, the voltage change causes a slight water electrolysis reaction on the electrode, which generates micro-nano-scale bubbles inside the electrode. Combined with the ultrasonic action, the brine inside the electrode can be ultrasonically cavitated, disturbing the brine, promoting the flow of the brine, and clearing the internal mass transfer channels blocked by impurity phases.

[0010] To achieve this objective, the present disclosure adopts the following technical solution:

[0011] In a first aspect, this disclosure provides an electrochemical lithium extraction / deintercalation method, the method comprising the following steps:

[0012] (1) Constructing an electrolytic cell for lithium extraction;

[0013] (2) Power is supplied to the electrolytic cell to extract lithium. During the lithium extraction process, the voltage is periodically increased and ultrasound is applied to the electrolytic cell to complete the electrochemical deintercalation and extraction of lithium.

[0014] In this disclosure, the voltage is periodically increased. While lithium extraction is being carried out, the voltage change causes a slight water electrolysis reaction on the electrode, which generates micro-nano-scale bubbles inside the electrode. Combined with the ultrasonic action, the brine inside the electrode is ultrasonically cavitated, disturbing the brine, promoting the flow of the brine, and clearing the internal mass transfer channels blocked by impurities.

[0015] In one embodiment, the lithium extraction electrolytic cell in step (1) includes a cathode, an anode, an extraction solution, and a recovery solution.

[0016] In one embodiment, a monovalent cation exchange membrane is used in the electrolytic cell of step (1) to separate the extract from the anode and the recovery from the cathode.

[0017] In one embodiment, the extract is brine from a salt lake.

[0018] In one embodiment, the recovered liquid comprises an aqueous solution of KCl and / or an aqueous solution of NaCl.

[0019] In one embodiment, the concentration of the recovered liquid is 0.05 to 0.1 mol / L, for example, it can be 0.05 mol / L, 0.06 mol / L, 0.07 mol / L, 0.08 mol / L, 0.09 mol / L or 0.1 mol / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0020] In one embodiment, the cathode comprises a lithium-rich electrode, wherein the lithium-rich electrode comprises a lithium extraction active material.

[0021] In one embodiment, the lithium-rich electrode is prepared by mixing lithium-extraction active material, conductive agent and binder to obtain a slurry, coating the obtained slurry on the surface of a current collector, and drying it to obtain the lithium-rich electrode.

[0022] In one embodiment, the lithium extraction active material includes any one or a combination of at least two of lithium manganese oxide, lithium iron phosphate, lithium manganese iron phosphate, or lithium titanate. Typical but non-limiting combinations include combinations of lithium manganese oxide and lithium iron phosphate, combinations of lithium iron phosphate and lithium manganese iron phosphate, combinations of lithium manganese iron phosphate and lithium titanate, combinations of lithium manganese oxide and lithium manganese iron phosphate, and combinations of lithium iron phosphate and lithium titanate.

[0023] In one embodiment, the mass ratio of the lithium-extracting active material, the conductive agent, and the binder is 90:5:5 to 70:15:15, for example, it can be 90:5:5, 85:7:8, 80:10:10, 75:12:13, or 70:15:15, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0024] The conductive agent is a conventional conductive agent, for example, it may be conductive acetylene black and / or conductive carbon black.

[0025] The adhesive is a conventional adhesive, for example, it may be PTFE and / or PVDF.

[0026] The current collector is a conventional current collector, which can be, for example, aluminum foil, carbon cloth, titanium mesh or carbon paper.

[0027] In one embodiment, the areal density of the coating is 5–25 mg / cm³. 2 For example, it could be 5mg / cm 2 10mg / cm 2 15mg / cm 2 20mg / cm 2 Or 25mg / cm 2 However, this does not limit the listed values; other unlisted values ​​within the range are also applicable.

[0028] In one embodiment, the drying temperature is 50 to 70°C, for example, 50°C, 55°C, 60°C, 65°C or 70°C, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0029] In one embodiment, the drying time is 8 to 12 hours, for example, 8 hours, 9 hours, 10 hours, 11 hours or 12 hours, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0030] In one embodiment, the anode is a lithium-poor electrode.

[0031] In this disclosure, a lithium-poor electrode refers to an electrode in which some lithium ions have been extracted and inserted, compared to a lithium-rich electrode. The lithium content in a lithium-poor electrode is lower than that in a lithium-rich electrode.

[0032] In one embodiment, the method for preparing the lithium-poor electrode includes: constructing an electrolytic cell using the lithium-rich electrode as the cathode and a silver chloride electrode as the anode, and applying a constant voltage to the electrolytic cell to remove lithium, wherein the lithium-rich electrode after lithium removal is the lithium-poor electrode.

[0033] In one embodiment, the electrolyte in the electrolytic cell comprises an aqueous solution of KCl and / or an aqueous solution of NaCl.

[0034] In one embodiment, the concentration of the electrolyte is 0.05 to 0.1 mol / L, for example, it can be 0.05 mol / L, 0.06 mol / L, 0.07 mol / L, 0.08 mol / L, 0.09 mol / L or 0.1 mol / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0035] In one embodiment, the constant voltage is 0.3 to 1.3V, for example, it can be 0.3V, 0.5V, 0.7V, 1V or 1.3V, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0036] In one embodiment, the constant voltage energization to a current below 0.3mA can be, for example, 0.3mA, 0.2mA, 0.1mA, 0.05mA, or 0.01mA, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0037] In one embodiment, the energizing in step (2) is a constant voltage energizing, with a voltage of 0.3 to 1.3V, for example, 0.3V, 0.5V, 0.7V, 1V or 1.3V, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0038] In one embodiment, the premise for periodically increasing the voltage in step (2) is that during the lithium extraction process, the current drops to below 0.3mA, for example, it can be 0.3mA, 0.2mA, 0.1mA, 0.05mA or 0.01mA, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0039] In one embodiment, step (2) involves increasing the voltage to 1.3 to 1.8V, for example, 1.3V, 1.4V, 1.5V, 1.6V, 1.7V, or 1.8V, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0040] Increasing the voltage too high can easily introduce impurities, while increasing it too low will result in low microbubble generation efficiency.

[0041] In one embodiment, the voltage increase time in step (2) is 1 to 5 minutes, for example, it can be 1 minute, 2 minutes, 3 minutes, 4 minutes or 5 minutes, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0042] In one embodiment, the frequency of the ultrasound applied in step (2) is 20 to 40 Hz, for example, it can be 20 Hz, 25 Hz, 30 Hz, 35 Hz or 40 Hz, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0043] Applying ultrasound at too high a frequency will damage the electrodes, while applying it at too low a frequency will not achieve the desired ultrasonic cavitation effect.

[0044] In one embodiment, the number of periods is ≥1, for example, it can be 1, 3, 5, 10 or 20, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0045] In one embodiment, when the voltage is increased and ultrasound is applied to the electrolytic cell, the current no longer changes, i.e., the power supply is stopped.

[0046] In one embodiment, after the lithium extraction by energizing in step (2) is completed, the positions of the cathode and anode are exchanged, and the operation steps of step (2) are repeated.

[0047] In one embodiment, the repeated steps are: energizing the electrolytic cell to extract lithium, during which the voltage is periodically increased and ultrasound is applied to the electrolytic cell.

[0048] In one embodiment, the number of repetitions is ≥1, for example, it can be 1, 3, 5, 10 or 20, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0049] In one embodiment, after completing step (2), the method further includes collecting the recovered liquid and determining the concentration of lithium ions in the recovered liquid.

[0050] As an optional technical solution to the method described in the first aspect of this disclosure, the method includes:

[0051] (1) A slurry is prepared by mixing lithium-extracting active material, conductive agent, and binder in a mass ratio of 90:5:5 to 70:15:15. The slurry is then coated onto the surface of the current collector, with a coating surface density of 5 to 25 mg / cm³. 2 After drying at 50–70°C for 8–12 hours, the lithium-rich electrode is obtained.

[0052] (2) Using the lithium-rich electrode described in step (1) as the cathode and the silver chloride electrode as the anode, and the electrolyte including KCl aqueous solution and / or NaCl aqueous solution with a concentration of 0.05-0.1 mol / L, an electrolytic cell is constructed. The electrolytic cell is subjected to a constant voltage of 0.3-1.3V for delithiation. The current is stopped when it drops below 0.3 mA. The lithium-rich electrode after the termination is the obtained lithium-poor electrode.

[0053] (3) Using the lithium-rich electrode obtained in step (1) as the cathode and the lithium-poor electrode obtained in step (2) as the anode, a monovalent cation membrane separates the extract from the anode and the recovery from the cathode. The extract is brine from a salt lake, and the recovery is a 0.05-0.1 mol / L KCl aqueous solution and / or NaCl aqueous solution to construct an electrolytic cell for lithium extraction.

[0054] (4) Apply a constant voltage of 0.3 to 1.3V to the electrolytic cell for lithium extraction in step (3) to extract lithium. During the lithium extraction process, after the current drops below 0.3mA, increase the voltage to 1.3 to 1.8V and apply 20 to 40Hz ultrasound to the electrolytic cell for 1 to 5 minutes. After the treatment, continue to extract lithium at a constant voltage of 0.3 to 1.3V. When the current drops to 0.3mA, repeat the above treatment until the current does not change and then stop applying the power.

[0055] (5) Exchange the positions of the anode and cathode, repeat the operation of step (4) ≥ 1 time, and then collect the recovery liquid to complete the electrochemical deintercalation and extraction of lithium.

[0056] Secondly, this disclosure provides an application of the method according to the first aspect, the method being used for lithium extraction from brine.

[0057] Based on the above technical solutions, the beneficial effects of this disclosure are as follows:

[0058] In this disclosure, the voltage is periodically increased. While lithium extraction is being carried out, the voltage change causes a slight water electrolysis reaction on the electrode, which generates micro-nano-scale bubbles inside the electrode. Combined with the ultrasonic action, the brine inside the electrode is ultrasonically cavitated, disturbing the brine, promoting the flow of the brine, and clearing the internal mass transfer channels blocked by impurities.

[0059] After reading and understanding the accompanying diagrams and detailed descriptions, the other aspects can be understood. Attached Figure Description

[0060] The accompanying drawings are used to provide a further understanding of the technical solutions in this paper and form part of the specification. They are used together with the embodiments of this application to explain the technical solutions in this paper and do not constitute a limitation on the technical solutions in this paper.

[0061] Figure 1 This is a mechanism diagram of the electrochemical lithium extraction / deintercalation method. Detailed Implementation

[0062] The technical solution of this disclosure will be further described below with reference to the accompanying drawings and specific embodiments. However, the examples below are merely simplified examples of this disclosure and do not represent or limit the scope of protection of this disclosure. The scope of protection of this disclosure is determined by the claims.

[0063] Example 1

[0064] This embodiment provides a method for electrochemical lithium extraction / deintercalation, the method comprising:

[0065] (1) Lithium manganese oxide, conductive acetylene black, and PVDF were mixed in a mass ratio of 80:10:10 to obtain a slurry. The slurry was then coated onto the surface of the current collector, with a coating surface density of 15 mg / cm³. 2 After drying at 60°C for 10 hours, the lithium-rich electrode was obtained.

[0066] (2) Using the lithium-rich electrode described in step (1) as the cathode and the silver chloride electrode as the anode, and the electrolyte including a KCl aqueous solution with a concentration of 0.08 mol / L, an electrolytic cell is constructed. The electrolytic cell is subjected to a constant voltage of 0.8V for delithiation. The current is reduced to below 0.3 mA and then the process ends. The lithium-rich electrode after the process ends is the obtained lithium-poor electrode.

[0067] (3) Using the lithium-rich electrode obtained in step (1) as the cathode and the lithium-poor electrode obtained in step (2) as the anode, a monovalent cation membrane separates the extraction solution of the anode and the recovery solution of the cathode. The extraction solution is brine from a salt lake, and the recovery solution is a 0.08 mol / L KCl aqueous solution. An electrolytic cell for lithium extraction is constructed.

[0068] (4) Apply a constant voltage of 0.8V to the electrolytic cell for lithium extraction in step (3) to extract lithium. During the lithium extraction process, after the current drops below 0.3mA, increase the voltage to 1.5V and apply 30Hz ultrasound to the electrolytic cell for 2 minutes. After the treatment, continue to extract lithium at a constant voltage of 0.8V. When the current drops to 0.3mA, repeat the above treatment until the current does not change and then stop applying the power.

[0069] (5) Exchange the positions of the anode and cathode, repeat step (4) 3 times, and then collect the recovery liquid to complete the electrochemical deintercalation and extraction of lithium.

[0070] Example 2

[0071] This embodiment provides a method for electrochemical lithium extraction / deintercalation, the method comprising:

[0072] (1) Lithium titanate, conductive carbon black, and PVDF were mixed in a mass ratio of 90:5:5 to obtain a slurry. The slurry was then coated onto the surface of the current collector, with a coating areal density of 5 mg / cm³. 2 After drying at 70°C for 8 hours, the lithium-rich electrode was obtained.

[0073] (2) Using the lithium-rich electrode described in step (1) as the cathode and the silver chloride electrode as the anode, and the electrolyte including a NaCl aqueous solution with a concentration of 0.05 mol / L, an electrolytic cell is constructed. The electrolytic cell is subjected to a constant voltage of 0.3V for delithiation. The current is reduced to below 0.3 mA and then the process ends. The lithium-rich electrode after the process ends is the obtained lithium-poor electrode.

[0074] (3) Using the lithium-rich electrode obtained in step (1) as the cathode and the lithium-poor electrode obtained in step (2) as the anode, a monovalent cation membrane separates the extraction solution of the anode and the recovery solution of the cathode. The extraction solution is brine from a salt lake, and the recovery solution is a 0.05 mol / L NaCl aqueous solution. An electrolytic cell for lithium extraction is constructed.

[0075] (4) Apply a constant voltage of 0.3V to the electrolytic cell for lithium extraction in step (3) to extract lithium. During the lithium extraction process, after the current drops below 0.3mA, increase the voltage to 1.3V and apply 20Hz ultrasound to the electrolytic cell for 15 minutes. After the treatment, continue to extract lithium at a constant voltage of 0.3V. When the current drops to 0.3mA, repeat the above treatment until the current does not change and then stop applying the power.

[0076] (5) Exchange the positions of the anode and cathode, repeat step (4) once, and then collect the recovery liquid to complete the electrochemical deintercalation and extraction of lithium.

[0077] Example 3

[0078] This embodiment provides a method for electrochemical lithium extraction / deintercalation, the method comprising:

[0079] (1) A slurry was prepared by mixing lithium manganese iron phosphate, conductive acetylene black, and PVDF in a mass ratio of 70:15:15. The slurry was then coated onto the surface of the current collector, with a coating areal density of 25 mg / cm³. 2 After drying at 70°C for 8 hours, the lithium-rich electrode was obtained.

[0080] (2) Using the lithium-rich electrode described in step (1) as the cathode and the silver chloride electrode as the anode, and the electrolyte including a KCl aqueous solution with a concentration of 0.1 mol / L, an electrolytic cell is constructed. The electrolytic cell is subjected to a constant voltage of 1.5V for delithiation. The current is reduced to below 0.3 mA and then the process ends. The lithium-rich electrode after the process ends is the obtained lithium-poor electrode.

[0081] (3) Using the lithium-rich electrode obtained in step (1) as the cathode and the lithium-poor electrode obtained in step (2) as the anode, a monovalent cation membrane separates the extraction solution of the anode and the recovery solution of the cathode. The extraction solution is salt lake brine and the recovery solution is 0.1 mol / L KCl aqueous solution to construct an electrolytic cell for lithium extraction.

[0082] (4) Apply a constant voltage of 1.3V to the electrolytic cell for lithium extraction in step (3) to extract lithium. During the lithium extraction process, after the current drops below 0.3mA, increase the voltage to 1.8V and apply 40Hz ultrasound to the electrolytic cell for 1 minute. After the treatment, continue to extract lithium at a constant voltage of 1.3V. When the current drops to 0.3mA, repeat the above treatment until the current does not change and then stop applying the power.

[0083] (5) Exchange the positions of the anode and cathode, repeat step (4) twice, and then collect the recovery liquid to complete the electrochemical deintercalation and extraction of lithium.

[0084] Example 4

[0085] This embodiment provides an electrochemical lithium extraction method, which differs from Embodiment 1 in that the voltage is increased to 2V in step (4).

[0086] Example 5

[0087] This embodiment provides an electrochemical lithium extraction method, which differs from Embodiment 1 in that the voltage is increased to 1.25V in step (4).

[0088] Example 6

[0089] This embodiment provides an electrochemical deintercalation and extraction method for lithium, which differs from Embodiment 1 in that the frequency of the ultrasound applied in step (4) is 50 Hz.

[0090] Example 7

[0091] This embodiment provides an electrochemical deintercalation and extraction method for lithium, which differs from Embodiment 1 in that the frequency of the ultrasound applied in step (4) is 10 Hz.

[0092] Example 8

[0093] This embodiment provides an electrochemical lithium extraction method, which differs from Embodiment 1 in that the lithium-poor state electrode in step (3) is replaced with a silver chloride electrode.

[0094] Comparative Example 1

[0095] This comparative example provides an electrochemical deintercalation and extraction method for lithium, which differs from Example 1 in that: in step (4), when the current is below 0.3mA, the voltage is not changed, and only ultrasonic treatment is applied.

[0096] Comparative Example 2

[0097] This comparative example provides an electrochemical method for lithium extraction and deintercalation, which differs from Example 1 in that: in step (4), when the current is below 0.3mA, only the voltage is changed and no ultrasonic treatment is applied.

[0098] Comparative Example 3

[0099] This comparative example provides an electrochemical method for lithium extraction and deintercalation, which differs from Example 1 in that: in step (4), the voltage is not changed and ultrasonic treatment is not applied when the current is below 0.3mA.

[0100] The concentration of lithium ions in the recovered liquid obtained by the above method was tested by ICP, and the test results are shown in Table 1.

[0101] Table 1

[0102]

[0103]

[0104] Combination Figure 1 The mechanism shown in this disclosure involves periodically increasing the voltage. While extracting lithium, the voltage change causes a slight water electrolysis reaction on the electrode, resulting in micro-nano-scale bubbles inside the electrode. Combined with the ultrasonic action, this causes ultrasonic cavitation in the brine inside the electrode, disturbing the brine, promoting its flow, and clearing internal mass transfer channels blocked by impurities.

Claims

1. A method for electrochemical deintercalation lithium extraction, the method comprising the following steps: (1) constructing a lithium extraction electrolytic cell with a lithium-rich electrode as a cathode, a lithium-poor electrode as an anode, and a monovalent cation membrane separating the extract solution of the anode and the recovery solution of the cathode, wherein the extract solution is a salt lake brine, and the recovery solution is a 0.05-0.1 mol / L aqueous solution of KCl and / or NaCl; (2) applying a constant voltage of 0.3-1.3 V to the lithium extraction electrolytic cell to extract lithium, during the lithium extraction, when the current decreases to below 0.3 mA, increasing the voltage to 1.3-1.8 V and applying 20-40 Hz ultrasound to the electrolytic cell for 1-5 min, and then extracting lithium at a constant voltage of 0.3-1.3 V, repeating the above treatment when the current is below 0.3 mA until the current does not change, stopping the power supply, and completing the electrochemical deintercalation lithium extraction.

2. The method of electrochemical delithiation lithium extraction of claim 1, wherein, The lithium-rich electrode comprises lithium extraction active material.

3. The method of electrochemical delithiation for lithium extraction of claim 2, wherein, The lithium extraction active material comprises any one or a combination of at least two of lithium manganate, lithium iron phosphate, lithium manganese iron phosphate, or lithium titanate.

4. The method of electrochemical delithiation lithium extraction of claim 1, wherein, The preparation method of the lithium-rich electrode comprises mixing lithium extraction active material, a conductive agent, and a binder to obtain a slurry, coating the obtained slurry on the surface of a current collector, and drying to obtain the lithium-rich electrode.

5. The method of electrochemical delithiation for lithium extraction of claim 4, wherein, The mass ratio of the lithium extraction active material, the conductive agent, and the binder is 90:5:5-70:15:

15.

6. The method of electrochemical delithiation lithium extraction of claim 4, wherein, The coated face density is 5 to 25 mg / cm 2 .

7. The method of electrochemical delithiation lithium extraction of claim 4, wherein, The drying temperature is 50-70 ℃.

8. The method of electrochemical delithiation lithium extraction of claim 4, wherein, The drying time is 8-12 h.

9. The method of electrochemical delithiation lithium extraction of claim 1, wherein, The preparation method of the lithium-poor electrode comprises constructing an electrolytic cell with the lithium-rich electrode as a cathode and a silver chloride electrode as an anode, applying a constant voltage to the electrolytic cell to deintercalate lithium, and using the lithium-rich electrode after deintercalation lithium as the lithium-poor electrode.

10. The method of electrochemical delithiation for lithium extraction of claim 9, wherein, The electrolyte in the electrolytic cell comprises an aqueous solution of KCl and / or NaCl.

11. The method of electrochemical delithiation lithium extraction of claim 10, wherein, The concentration of the electrolyte is 0.05-0.1 mol / L.

12. The method of electrochemical delithiation lithium extraction of claim 9, wherein, The voltage of the constant voltage power supply is 0.3-1.3 V.

13. The method of electrochemical delithiation lithium extraction of claim 9, wherein, The current of the constant voltage power supply is below 0.3 mA.

14. The method of electrochemical delithiation for lithium extraction of claim 1, wherein, After the power supply for lithium extraction in step (2) is completed, the positions of the cathode and the anode are exchanged, and the operation steps of step (2) are repeated.

15. The method of electrochemical delithiation for lithium extraction of claim 14, wherein, The number of repetitions is ≥1.

16. The method of electrochemical delithiation for lithium extraction of claim 1, wherein, After step (2) is completed, the recovery solution is collected, and the concentration of lithium ions in the recovery solution is determined.

17. The method of electrochemical delithiation for lithium extraction of claim 1, wherein, The method comprises: (1) mixing lithium extraction active material, conductive agent and binder in a mass ratio of 90:5:5 to 70:15:15 to obtain a slurry, coating the obtained slurry on the surface of a current collector, and the face density of the coating is 5 to 25 mg / cm 2 , and after drying at 50 to 70 °C for 8 to 12 h, a lithium-rich electrode is obtained; (2) constructing an electrolytic cell with the lithium-rich electrode in step (1) as a cathode and a silver chloride electrode as an anode, and an electrolyte comprising an aqueous solution of KCl and / or NaCl with a concentration of 0.05-0.1 mol / L, applying a constant voltage of 0.3-1.3 V to the electrolytic cell to deintercalate lithium, and ending when the current is below 0.3 mA, and using the lithium-rich electrode after the ending as a lithium-poor electrode; (3) constructing a lithium extraction electrolytic cell with the lithium-rich electrode in step (1) as a cathode, the lithium-poor electrode in step (2) as an anode, and a monovalent cation membrane separating the extract solution of the anode and the recovery solution of the cathode, wherein the extract solution is a salt lake brine, and the recovery solution is a 0.05-0.1 mol / L aqueous solution of KCl and / or NaCl. (4) applying a constant voltage of 0.3-1.3 V to the lithium-extracting electrolytic cell of step (3) to extract lithium, during the lithium extraction, when the current decreases to below 0.3 mA, the voltage is increased to 1.3-1.8 V and ultrasound of 20-40 Hz is applied to the electrolytic cell for 1-5 min, then the lithium extraction is performed again under a constant voltage of 0.3-1.3 V, when the current decreases to below 0.3 mA, the above treatment is repeated until the current does not change, and the power supply is stopped; (5) exchanging the positions of the anode and the cathode, repeating the operation of step (4) for ≥1 times, and collecting the recovery liquid, to complete the electrochemical deintercalation lithium extraction.

18. Use of the method according to any one of claims 1 to 17, wherein The method is used for lithium extraction from brine.

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