CN115418675A - Electrochemical lithium extraction method - Google Patents

Electrochemical lithium extraction method Download PDF

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CN115418675A
CN115418675A CN202210884182.8A CN202210884182A CN115418675A CN 115418675 A CN115418675 A CN 115418675A CN 202210884182 A CN202210884182 A CN 202210884182A CN 115418675 A CN115418675 A CN 115418675A
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lithium
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赵晓昱
郑莉晓
曹汝鸽
王彦飞
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Tianjin University of Science and Technology
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Abstract

The invention relates to an electrochemical lithium extraction method, which applies pulse electric field control for a certain time in lithium-containing raw material liquid of an electrochemical lithium extraction electrode system. The lithium extraction electrochemical system has the advantages of obvious lithium extraction cycle stability, long-acting selectivity, low unit lithium extraction energy consumption and the like under the optimal process parameters of the pulse-reverse pulse electric field combined mode.

Description

Electrochemical lithium extraction method
Technical Field
The invention belongs to the technical field of electrochemical lithium extraction, and particularly relates to an electrochemical lithium extraction method.
Background
The extraction and recovery method of the salt lake brine lithium resource comprises an electrodialysis method, an evaporation crystallization method, a solvent extraction method, a precipitation method, an ion exchange method and an adsorption method. Among them, the adsorption method is widely used because of its low cost and high efficiency. However, acid washing is required during the exchange adsorption process to generate secondary waste. In addition, the permeability and solubility of the adsorbent are poor, which severely limits its industrial application. The solvent extraction method has high selectivity, high yield, simple and convenient operation and easy industrial amplification, and is an ideal separation method for extracting lithium from the salt lake with high magnesium-lithium ratio. However, this method uses a large amount of organic solvent, resulting in environmental pollution and corrosion of equipment. The traditional lithium extraction method has the defects of high cost, high energy consumption, low separation efficiency and the like. Electrochemical technology is considered to be a promising technology for recovering lithium from salt lake brine and seawater.
Chinese patent CN112645362A discloses a method for directly preparing lithium carbonate by electrochemically extracting lithium from chloride type lithium-containing brine. Chloride type lithium-containing brine is used as electrolyte, a lithium ion sieve electrode and a chloride ion capturing electrode are respectively used as a positive electrode and a negative electrode to form a primary battery, and the primary battery discharges to embed lithium ions in the brine into a lithium ion sieve. Chinese patent CN109440132A also discloses a continuous electrochemical lithium extraction system. The method takes Polyaniline (PANI) as the negative electrode of a lithium extraction battery system and has high Li content + Selective lambda-MnO 2 The material is used as a battery anode, and the extraction of lithium is realized through a two-step flow system. First, a lithium-containing solution is flowed through the system, during discharge, anions are inserted into PANI, and Li + Is high in Li + Selective lambda-MnO 2 And (4) electrode capture. After the discharge is finished, the recovery liquid is added for charging, anions are removed from the negative PANI, and Li + Is released from the positive electrode. Repeated circulation can realize the purpose of separating lithium ions from other cations in the lithium-containing solution and enriching the lithium ions in the recovery solution. The method is an electrochemical lithium extraction method with high efficiency, low consumption, high selectivity, simple process, easy control and no pollution. Chinese patent CN110643831A discloses a diaphragm-free continuous electrochemical lithium extraction system and a lithium extraction method thereof. The system mainly comprises an electrolytic bath, a washing tank, a power supply, a series of lithium absorbing and removing electrodes and an electronic balance electrode. The electrolytic tank is divided into a raw material tank and a recovery tank which are sequentially alternated by a series of clapboards, and the raw material tank and the recovery tank are connected in series through connecting pipes. And introducing a lithium raw material to be extracted and a recovery liquid into the raw material pool and the recovery pool respectively, and realizing the separation of lithium from the raw material and the enrichment in the recovery liquid by switching the electrodes between the raw material pool and the recovery pool. Two significant features of this system are high selectivity to lithium ions and very low energy consumption compared to other cations. Patent CN108560019A is directed at continuity of lithium extraction operationThe device comprises a cavity, wherein the cavity is formed by enclosing two conductive current collectors and side plates which are arranged in parallel at intervals, and a lithium-containing solution inlet, a recovery solution inlet, a lithium removal solution outlet and a lithium-enriched recovery solution outlet are formed in the side wall of a solution flowing cavity. On the premise of improving cation selectivity, a double-electric-layer capacitor electrode represented by two-dimensional long-range ordered materials such as activated carbon, graphene and polypyrrole is adopted as a negative electrode to replace a rocking chair type battery negative electrode, and the rocking chair type battery negative electrode has the characteristics of high cycle stability, no need of repeatedly taking out and immersing the electrode, only need of switching in and out fluid, high operation continuity and the like. Patent CN109487081B discloses a lithium extraction unit using a flow electrode, an expansion device and a continuous operation method for the electrode form and the operation mode; the method solves the problems of complicated operation of switching electrodes or switching fluid in the regeneration process of the fixed electrode, uneven distribution of mass transfer and electric field in the large-scale amplification process and the like; by adopting a standard size module system, the yield amplification can be flexibly realized through the simple number extension of the standard modules, and the amplification effect does not exist.
The above scheme is based on element doping, structure and form of the lithium extraction electrode material; the operation mode and other angles are designed and optimized, and the electric field control adopts a pure constant current or constant voltage mode. This mode is difficult to overcome the low selectivity of lithium ion intercalation caused by high concentration of sodium ions when faced with a system of low lithium to sodium ratio. The conventional electrochemical lithium extraction process needs to be carried out by sodium evaporation, potassium evaporation, lithium enrichment and other steps before the whole process of extracting lithium from brine, and the lithium loss in the steps is large, so that the overall lithium recovery rate is low, therefore, the preposition of the lithium extraction process is beneficial to the high-efficiency utilization of lithium resources in a salt lake, and the Li/Na concentration ratio of the original brine of the salt lake, which is faced by the preposition of the lithium extraction process, is between 0.0016 and 0.06. The Li/Na concentration ratio in seawater is more between 1.69 x 10 -5 To 5.3X 10 -5 In the meantime. Therefore, the lithium-sodium selectivity problem is faced in the direct electrochemical lithium extraction process from seawater and salt lake raw brine, because when the Li/Na ratio is low to a certain extent, sodium intercalation into the cathode material is thermodynamically favored rather than lowThe lithium intercalation in the concentration, therefore, in the solution with low Li/Na ratio, the defects of high energy consumption and low selectivity lithium extraction cause the application of the field of electrochemical lithium extraction to be limited to a certain extent.
Disclosure of Invention
The invention aims to solve the problems of high energy consumption, low selectivity and low recovery rate of lithium extraction in the process of extracting lithium from a low Li/Na concentration ratio system, such as seawater and salt lake raw brine in the conventional electrochemical brine lithium extraction technology, and provides a control mode and combination optimization of a pulse electric field from the perspective of optimization of intercalation and deintercalation dynamics, so that the advantages of intercalation dynamics of lithium ions relative to sodium ions are improved, and the lithium extraction selectivity is improved. Meanwhile, the diffusion efficiency of lithium ions in an electrode bulk phase is increased, lithium intercalation sites are fully utilized, and the lithium extraction capacity is increased.
The technical scheme for realizing the purpose of the invention is as follows:
an electrochemical lithium extraction method is characterized in that a pulse electric field control is applied to a lithium-containing raw material liquid for a certain time. Compared with the constant current, the distribution of the lithium ions on the electrode space scale and the time scale in the lithium extraction process can be effectively optimized, more lithium intercalation sites are fully utilized, the concentration polarization effect is reduced, and the advantages of lithium ion intercalation and diffusion kinetics to sodium ions are increased.
The pulse control includes, but is not limited to, the following modes:
the first method comprises the following steps: only the positive pulse is applied for 1 to 50 seconds. Preferably 10 to 30 seconds.
And the second method comprises the following steps: positive pulse and static pause, wherein the positive pulse time is 1 to 50s, and the static pause time is 1 to 20s. Preferably, the forward pulse time is 10 to 30s, and the dead time is 2 to 10s.
Further preferably, the forward pulse and the rest period are 10s and 2s (P10 r 2), respectively; the positive pulse and the rest period are respectively 12s and 2s (P12 r 2); the forward pulse and rest periods are 10s and 10s (P10 r 10), respectively;
and the third is that: the forward pulse + static pause + reverse pulse, the forward pulse time is 1-50 s, the static pause time is 1-20 s, and the reverse pulse time is 1-15 s. Preferably, the forward pulse time is 10-30 s, the dead time is 2-10 s, and the reverse pulse time is 1-5 s.
Fourthly, positive pulse + rest + reverse pulse + rest, wherein the positive pulse time is 1 to 40s, the rest time is 1 to 20s, the reverse pulse time is 1 to 15s, and the rest time is 1 to 20s. Preferably, the forward pulse time is 5-15 s, the dead time is 1-10 s, the reverse pulse time is 2-25 s, and the dead time is 2-15 s.
Further preferably, the forward pulse and the dead time period are respectively 12s and 2s, and the reverse pulse and the dead time period with the same amplitude are both 2s (P12R 2R 2); the forward pulse and the static dwell period are respectively 10s and 2s, and the reverse pulse and the static dwell period with the same amplitude are both 5s (P10R 2R 5); the positive pulse and the dead time period are both 10s, and the same-amplitude negative pulse and the dead time period are both 10s (P10R 10R 10).
But also any other electric field combination pattern of different time distribution combinations controlled by current and voltage as easily imaginable by practitioners in the art according to the scheme.
Further, the lithium intercalation and deintercalation active material may employ LiMn 2 O 4 (LMO) or LiFePO 4 LFP or LiFePO 4 /MXene or LiNi 0.6 Co 0.2 Mn 0.2 O 2 /MXene or LiMn 2 O 4 /MXene or LiFePO 4 /rGO or LiFePO 4 The/carbon nano tube or the lithium iron manganese phosphate LMFP or any other materials can be used as a lithium intercalation material or a lithium intercalation composite material.
Further, the negative electrode is activated carbon, silver sheets, bismuth sheets or a lithium-removing state corresponding to the lithium-insertion-removal active material.
Further, the lithium-containing raw material liquid comprises a lithium-containing solution system such as seawater, salt lake raw brine, oil field brine, underground brine and the like.
One embodiment of the method of the present invention comprises the steps of:
(1) And applying positive pulse electric field control for a certain time to the lithium-containing raw material liquid of the two electrode systems consisting of the inserted and removed lithium active material// AC, wherein ions in the solution move towards the opposite direction under the action of the electric field, lithium ions move towards the positive electrode and are inserted into the crystal lattice of the positive electrode active electrode material, and chloride ions move towards the negative electrode and are adsorbed on the negative electrode. Or in a two-electrode system consisting of the lithium intercalation active material/the lithium removal active material, the two electrodes are respectively placed in the recovery liquid and the lithium-containing raw material liquid, a pulse electric field control is applied for a certain time, lithium ions in the lithium-containing raw material liquid move to the lithium removal electrode and are intercalated, and the lithium ions in the lithium intercalation electrode are removed and move to the recovery liquid.
(2) The system is subjected to static rest of an electric field for a certain time, and the short static rest time inserted in the lithium intercalation process can provide more time for further diffusing the lithium ions gathered on the surface of the electrode to a bulk phase, so that the lithium ions are more uniformly distributed in the electrode, and the utilization rate of lithium intercalation sites of the active material can be improved; meanwhile, the lithium insertion resistance on the surface of the electrode is effectively reduced.
(3) The reverse pulse electric field control of a certain time is applied to the system, ions in the solution move in opposite directions due to the action of the reverse electric field, so that concentration polarization caused by slow diffusion speed is favorably eliminated, and meanwhile, the reverse pulse can help sodium to be removed from the electrode, so that the proportion of lithium ions inserted into the electrode body phase is favorably improved, and the structural stability and the lithium ion selectivity of the electrode material are further improved.
(4) And (3) applying an electric field rest for a certain time to the system, wherein the rest after the back pulse provides time for sodium ions removed from the electrode interface to diffuse into the solution, and the apparent lithium ion concentration of the electrode interface in the next positive pulse lithium intercalation process is increased, so that the improvement of the lithium intercalation selectivity is facilitated.
(5) After lithium is extracted under the pulse-rest-reverse pulse-rest combined electric field, the lithium-deficient lithium-containing raw material liquid after lithium extraction is discharged, collected and waited to be discharged or recycled for reuse. And switching the fluid source to be deionized water, inputting the deionized water into the electrolytic cell to flush the electrode assembly, and then discharging the flushing liquid.
(6) For a lithium-embedded active material/negative electrode system, after lithium is extracted, a fluid is switched into a recovery liquid for lithium removal, the positive electrode and the negative electrode of a power supply connected with the two electrodes are exchanged, a pulse combined electric field is applied to the system in the lithium removal stage, and lithium ions and chloride ions release ions from the electrodes to move to the recovery liquid under the control of the pulse electric field.
Or, for the lithium intercalation active material/lithium deintercalation active material system, after lithium extraction, the lithium intercalation and deintercalation states and the positions of the lithium intercalation and deintercalation states in the recovery solution and the lithium-containing raw material solution are interchanged, the positive electrode and the negative electrode of the power supply connected with the two electrodes are also interchanged, a pulse combined electric field is applied, lithium ions in the lithium intercalation state are released into the recovery solution to further enrich the lithium ions, and the lithium ions in the lithium-containing raw material solution are diffused and intercalated into the lithium deintercalation state to be further extracted.
(7) The system is subjected to static rest of an electric field for a certain time, and the short static rest time is inserted in the lithium removal process, so that the volume of the active material can be effectively reduced and the rapid collapse of the active material in the ion removal process of the electrode can be effectively reduced, and further the local pressure of the electrode can be reduced.
(8) The system is controlled by applying a reverse pulse electric field for a certain time, and the addition of the reverse pulse provides more uniform concentration for ion diffusion in the lithium removal process of the system, so that concentration polarization is effectively eliminated.
(9) And (3) performing electric field rest for a certain time on the system, and redistributing all lithium sodium particles in the electrode in the period of time without electric field control in the electrode lattice so as to improve the structural stability of the active material.
(10) Under the control of the pulse-rest-reverse pulse-rest combined electric field, lithium ions are enriched in the recovery liquid.
(11) And (3) performing the step (1) to step (10) in a circulating reciprocating mode, wherein the raw material solution and the recovery solution introduced in the process can be recycled, or can be mixed with fresh lithium-containing raw material solution and then enter a lithium extraction system, and the concentration of lithium ions in the recovery solution is gradually increased along with the circulation times. Until the concentration of lithium ion in the original halogen is reduced to a certain value or the original halogen is mixed with fresh original halogen to reach a steady state (comprehensively judged by factors such as energy consumption, operation, economy and the like).
The invention has the advantages and beneficial effects that:
the lithium extraction electrochemical system has the advantages of obvious lithium extraction cycle stability, long-acting selectivity, low unit lithium extraction energy consumption and the like under the optimal process parameters of a pulse-reverse pulse electric field mode. Pulse charging including dwell time and discharge time is beneficial to eliminating concentration polarization caused by slow diffusion rate, reducing charge time, improving utilization rate of active materials, and obtaining longer cycle life. The same strategy is expected to improve the diffusion kinetic advantages of lithium ions relative to sodium ions in the lithium extraction process and the actual utilization rate of active sites, so that the ion selectivity, the actual lithium extraction capacity and the cycling stability are improved. Through electric field combination optimization, the energy utilization rate in the Atacama real brine can be as low as 2.2Wh/mol Li, the purity retention rate of lithium ions in the receiving solution is as high as 96.55 percent after 15 cycles of circulation, the lithium-sodium separation coefficient can reach 1020 percent, the high-efficiency separation of lithium resources can be realized, and the high selectivity of lithium ions in the solution with low lithium-sodium ratio provides feasibility for directly extracting lithium from seawater; the method provides possibility for the preposition of the lithium extraction process of the salt lake brine, and is expected to greatly reduce the lithium loss rate of the lithium extraction of the salt lake brine.
Drawings
Fig. 1 is an XRD pattern of the MXene composite LMO electrode material prepared in example 1.
FIG. 2 is a microstructure of LMO and LMO/MXene prepared in example 1, where a is LMO and b is LMO/MXene.
FIG. 3 is a graph of potential/current versus time under a constant current CC electric field.
FIG. 4 is a graph of potential/current versus time for a P10r2 electric field.
FIG. 5 is a graph of potential/current versus time for a P10r10 electric field.
FIG. 6 is a graph of potential/current versus time for a P12R2R2 electric field.
FIG. 7 is a graph of cyclic voltammetry tests of MXene/LMO in simulated brine containing lithium and simulated brine containing no lithium.
Detailed Description
Example 1:
an electrochemical lithium extraction method sets electrochemical parameters as positive pulse and rest period both being 10s (P10 r 10), and uses Atacama simulated bittern (21.6 mM Li) + ，39.5mM Mg 2+ ，330.06mM Na + ，47.3mM K + And 0.8mM Ca 2+ ) And (3) taking a 10mM LiCl solution as a recovery solution, adopting LMO/MXene as an intercalation and deintercalation lithium cathode material and active carbon as a counter electrode, and performing cyclic lithium extraction for 15 circles to obtain the lithium extraction purity of 0.94 and the unit energy consumption of 2.79Wh/mol.
The preparation method of the LMO/MXene comprises the following steps: the method comprises the following steps:
step one, synthesizing LiMn by adopting solid-phase reaction 2 O 4 (LMO). Mixing Li 2 CO 3 And MnO 2 Mixing Li and Mn according to the molar ratio of 1/1, heating in a muffle furnace at the temperature rise rate of 5 ℃/min at 550 ℃ for 6h, and cooling to room temperature to obtain LMO.
Step two, synthesizing Ti by adopting a solvothermal method 3 C 2 -MXene. Mixing LiF and hydrochloric acid with the concentration of 12mol/L in the molar ratio of 1/1 uniformly, and then mixing Ti 3 AlC 2 The solution was slowly added in portions while stirring, followed by stirring at a constant temperature of 40 ℃ for 24 hours. Adding deionized water into the reaction product, centrifuging at 3500rpm for 10min until the ph of the supernatant is =6/7, collecting the solid at the bottom of the centrifuge tube, dissolving the solid in the deionized water, performing ultrasonic treatment for 2 hours under the conditions of argon atmosphere and ice bath, finally centrifuging, collecting the upper-layer dark green liquid, and performing freeze drying to obtain a product, namely Ti 3 C 2 -MXene.
Step three, preparing the LMO/MXene composite material through the electrostatic self-assembly process, adding LMO particles into aqueous solution (1.2 mg/mL) in a glass bottle filled with CTAB under continuous stirring for 30min, and then dropwise adding the solution into a beaker filled with layered Ti 3 C 2 MXene suspension, stirring for 30 minutes. Subsequently, washing with deionized water until residual CTAB is removed, and vacuum drying at 70 ℃ to obtain the LMO/MXene composite material.
Table 1 shows different electric field modes applied to LMO/MXene, LMO and LiFePO 4 /MXene、LiFePO 4 、LiNi 0.6 Co 0.2 Mn 0.2 O 2 Electrode materials in Atacama simulated brine (21.6 mM Li) + ，39.5mM Mg 2+ ，33.06mM Na + ，47.3mM K + And 0.8mM Ca 2+ ) The lithium extraction purity and the energy consumption in the process.
TABLE 1
Figure BDA0003761945170000061
Example 2:
the difference from example 1 is that: setting electrochemical parameters of a forward pulse and a quiescent period as 10s and 2s (P10 r 2) respectively at an electrochemical workstation, and carrying out cycle lithium extraction for 15 circles to obtain the lithium extraction purity of 0.903 and the unit energy consumption of 3.378Wh/mol.
Example 3:
the difference from example 1 is that: setting electrochemical parameters of a forward pulse and a rest period as 12s and 2s respectively and setting the same-amplitude reverse pulse and the rest period as 2s (P12R 2R 2) in an electrochemical workstation, and circularly extracting lithium for 15 circles to obtain the lithium extraction purity of 0.972 and the unit energy consumption of 2.159Wh/mol
Example 4:
the difference from example 3 is that the positive electrode material is LMO. The lithium extraction purity was 0.921 and the unit energy consumption was 2.972Wh/mol.
Example 5:
the difference from example 3 is that: the anode material is LiFePO 4 The lithium extraction purity of the/MXene material is 0.932, and the unit energy consumption is 2.921Wh/mol.
LiFePO 4 The preparation method of the/MXene composite material comprises the following steps:
step one, synthesizing lithium iron phosphate LiFePO by adopting a high-temperature solid phase method 4 . With iron oxalate FeC 2 O 4 Diammonium hydrogen phosphate (NH) 4 ) 2 HPO 4 ) And lithium carbonate Li 2 CO is used as a raw material, is fully and uniformly mixed according to the stoichiometric ratio, is subjected to low-temperature pre-decomposition in an inert atmosphere, is roasted at high temperature, and is ground and crushed to prepare the catalyst.
Step two, ti is synthesized by adopting a solvothermal method 3 C 2 -MXene. Mixing LiF and hydrochloric acid with the concentration of 12mol/L uniformly according to the molar ratio of 1/1, and then mixing Ti 3 AlC 2 The solution was slowly added in portions while stirring, followed by stirring at a constant temperature of 40 ℃ for 24 hours. Adding deionized water into the reaction product, centrifuging at 3500rpm for 10min until the pH of the supernatant is =6/7, collecting the solid at the bottom of the centrifuge tube, dissolving the solid in the deionized water, performing ultrasonic treatment for 2 hours under the conditions of argon atmosphere and ice bath, finally centrifuging, collecting the upper layer dark green liquid, and performing freeze drying to obtain a product, namely Ti 3 C 2 -MXene.
Step three, self-assembly through static electricityProcess for preparing LiFePO 4 /MXene composite material prepared by mixing LiFePO 4 The particles were added to an aqueous solution (1.2 mg/mL) in a glass flask containing CTAB with continuous stirring for 30min, and then the above solution was added dropwise to a beaker containing the layered Ti 3 C 2 MXene suspension, stirring for 30 minutes. Subsequently, washing with deionized water to remove residual CTAB, and vacuum drying at 70 ℃ to obtain LiFePO 4 the/MXene composite material.
Example 6:
the differences from example 5 are: the anode material is LiFePO 4 A material. The purity of the obtained lithium is 0.911, and the unit energy consumption is 3.022Wh/mol.
Example 7:
the differences from example 6 are: the positive electrode material is LiNi 0.6 Co 0.2 Mn 0.2 O 2 The obtained lithium extraction purity is 0.952, and the unit energy consumption is 2.443Wh/mol.
LiNi 0.6 Co 0.2 Mn 0.2 O 2 The preparation method of the material comprises the following steps:
LiNi synthesis by solvothermal method 0.6 Co 0.2 Mn 0.2 O 2 : weighing a certain amount of Ni (CH) according to the proportion of Ni to Co to Mn =6 3 COO) 2 ·4H 2 O、Co(CH 3 COO) 2 ·4H 2 O、Mn(CH 3 COO) 2 ·4H 2 Dissolving O, weighing appropriate amount of NaOH, dissolving to obtain a precipitant, and adding concentrated NH 3 ·H 2 And diluting O to a certain concentration to be used as a complexing agent, respectively and continuously pumping metal cation solution at a certain speed, and after the reaction is completed, filtering, washing and drying to obtain a precursor product. Mixing the precursor product with LiOH. H 2 And uniformly mixing O according to the proportion of 1 0.6 Co 0.2 Mn 0.2 O 2 。
Comparative example 1:
the difference from example 4 is that: the electric field mode is set to (constant current (CC)) at the electrochemical workstation, the lithium extraction purity is 0.845, and the unit energy consumption is 4.971Wh/mol.
Comparative example 2:
the difference from example 1 is that: the electric field mode was set at the electrochemical workstation (constant current (CC), resulting in a lithium extraction purity of 0.881 and a specific energy consumption of 4.410Wh/mol.
Comparative example 3:
the differences from example 6 are: and setting an electric field mode (constant current (CC)) in the electrochemical workstation, and circularly extracting lithium for 15 circles to obtain the lithium extraction purity of 0.853 and the unit energy consumption of 5.124Wh/mol.
TABLE 2 LMO/MXene electrode materials prepared in example 1, P12R2R2 electric field mode in Atacama simulated brine (21.6 mM Li) + ，39.5mM Mg 2+ ，330.6mM Na + ，47.3mM K + And 0.8mM Ca 2+ ) And (5) carrying out intermediate circulation for 15 circles to extract the lithium purity and consume energy.
TABLE 2
Number of turns 1st 5th 10th 15th
Purity of 0.972 0.963 0.954 0.938
Energy consumption (Wh/mol) 2.2 4.5 5.8 8.7
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. The electrochemical lithium extracting method is characterized in that pulse electric field control is applied for a certain time in lithium-containing raw material liquid of an electrochemical lithium extracting electrode system.
2. The electrochemical lithium extraction method according to claim 1, comprising the following specific steps: applying pulse electric field control for a certain time to a lithium-containing raw material solution to control two electrode systems consisting of the lithium-embedded active material// the negative electrode, so that lithium ions move to the positive electrode, are embedded into the crystal lattice of the positive electrode lithium-embedded active material, and chloride ions move to the negative electrode direction and are adsorbed onto the negative electrode;
or in a two-electrode system consisting of the lithium intercalation active material/lithium deintercalation active material, the two electrodes are respectively placed in the recovery solution and the lithium-containing raw material solution, a pulse electric field control is applied for a certain time, lithium ions in the lithium-containing raw material solution move to the lithium deintercalation active material electrode and are intercalated, and the lithium ions in the lithium intercalation active material electrode are deintercalated and move to the recovery solution.
3. An electrochemical lithium extraction method according to claim 2, characterized in that after the positive pulse, a certain rest time is applied to the system.
4. An electrochemical lithium extraction method according to claim 3, characterized in that the system is subjected to reverse pulse electric field control for a certain time after rest.
5. An electrochemical lithium extraction method according to claim 4, characterized in that the system is subjected to a rest time after the reverse pulse.
6. The electrochemical lithium extraction method of any one of claims 1 to 5, wherein for a two-electrode system consisting of lithium intercalation active material// negative electrode, after lithium extraction, the fluid is switched to be the recovery liquid for lithium removal, the positive electrode and the negative electrode of the power supply connected with the two electrodes are exchanged, a pulse combined electric field is applied to the system in the lithium removal stage, and lithium ions and chloride ions are released from the electrodes under the control of the pulse electric field and move to the recovery liquid;
or, for a two-electrode system consisting of the lithium intercalation active material/lithium deintercalation active material, after lithium extraction, the lithium intercalation and deintercalation states and the positions of the lithium intercalation and deintercalation active material in the recovery solution and the lithium-containing raw material solution are exchanged, the positive electrode and the negative electrode of the power supply connected with the two electrodes are also exchanged, a pulse combined electric field is applied, lithium ions in the lithium intercalation state are released into the recovery solution to further enrich the lithium ions, and the lithium ions in the lithium-containing raw material solution are diffused and intercalated into the lithium deintercalation state to be further extracted.
7. An electrochemical lithium extraction method according to claim 6, characterized in that the lithium removal stage is carried out after the positive pulse electric field for a certain time of static rest of the electric field.
8. An electrochemical lithium extraction method according to claim 7, characterized in that the lithium removal stage is controlled by applying a reverse pulse electric field to the system for a certain time after a rest period.
9. An electrochemical lithium extraction method according to claim 8, characterized in that the delithiation stage is carried out after the reverse pulse for a certain time of field rest.
10. The electrochemical lithium extraction method of claim 1, wherein the lithium intercalation/deintercalation active material is one or more of LiMn2O4, liFePO4/MXene, liNi0.6Co0.2Mn0.2O2/MXene, liMn2O4/MXene, liFePO4/rGO, liFePO 4/carbon nanotube, and LiFePO 4/carbon nanotube; the negative electrode is active carbon, silver sheet, bismuth sheet or lithium-removed state corresponding to the lithium-insertion-removal active material.
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Publication number Priority date Publication date Assignee Title
CN115772609A (en) * 2023-02-13 2023-03-10 石家庄嘉硕电子技术有限公司 Electrochemical lithium extraction method and electrochemical lithium extraction system

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115772609A (en) * 2023-02-13 2023-03-10 石家庄嘉硕电子技术有限公司 Electrochemical lithium extraction method and electrochemical lithium extraction system

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