Lithium extraction system and lithium extraction method

Abstract

A lithium extraction system and a lithium extraction method. The lithium extraction system comprises a lithium extraction device and a capacitor device (1). The lithium extraction device comprises an electrolytic cell (4) and a partition plate (6); the partition plate (6) partitions the electrolytic cell (4) into a cathode chamber (5) and an anode chamber (7); a cathode (3) is provided in the cathode chamber (5) and is an electrode made of an electrode material capable of adsorbing lithium; an anode (8) is provided in the anode chamber (7) and is an electrode made of an electrode material capable of intercalating lithium; the anode chamber (7) is communicated with a negative electrode of the capacitor device (1) by means of a pipe (2), and the cathode chamber (5) is communicated with a positive electrode of the capacitor device (1) by means of a pipe (2); and an electrolyte is provided in the capacitor device (1). The lithium extraction method is performed by using the lithium extraction system and comprises the following steps: S1: introducing an anode electrolyte into an anode chamber (7) of a lithium extraction device, and at the same time, introducing a cathode electrolyte into a cathode chamber (5), wherein the cathode electrolyte contains lithium ions; and disconnecting power after the capacitor device (1) is charged; and S2: electrifying the lithium extraction device to perform lithium extraction.

Description

A lithium extraction system and a lithium extraction method Technical Field

[0001] The present invention relates to the field of extractive metallurgy, and in particular to a lithium extraction system and method. Background Art

[0002] Lithium is a vital metal resource widely used in lithium batteries. The rapid development of new energy has led to a dramatic increase in market demand for lithium resources, necessitating the effective development of lithium metal, lithium salts, and other products. Lithium resources are primarily found in ores, salt lakes, and seawater, particularly salt lakes. However, the high magnesium-to-lithium ratio in salt lakes makes separation difficult, resulting in only 8% of the total lithium extraction rate from salt lakes.

[0003] To develop lithium resources in salt lakes, currently developed lithium extraction technologies include salt pan drying, adsorption, solvent extraction, electrodialysis, membrane separation, and electrochemical methods. Among these, electrochemical methods are environmentally friendly, have low production costs, good lithium selectivity, and are well-adapted to brine, making them the future direction of lithium extraction from salt lakes.

[0004] At present, anion membranes are used to separate the cathode and anode tanks during electrochemical lithium extraction. The anion membranes are used to balance the anions and cations in the lithium extraction device, allowing the electrochemical lithium extraction device to operate normally. However, the following problems exist when using anion membranes: (1) Although the anion membrane is theoretically permeable only to anions and not cations, in actual use, osmosis can cause some cations in the cathode chamber, such as sodium ions, magnesium ions, and other impurity cations, to diffuse into the anode chamber, thereby increasing the content of impurity ions in the lithium-rich solution in the anode chamber. Therefore, the cost of impurity removal needs to be increased during the lithium extraction process. (2) The anion membrane itself is very fragile, and the installation process needs to be carefully controlled to avoid mixing of the cathode liquid and the anode liquid due to membrane damage.

[0005] Summary of the Invention

[0006] In order to overcome the problems existing in the above-mentioned prior art, one of the purposes of this article is to provide a lithium extraction system, which does not use an anion membrane and can avoid a series of problems caused by the use of anion membrane.

[0007] The second purpose of this article is to provide a lithium extraction method.

[0008] The third purpose of this article is to provide a lithium-rich solution.

[0009] The fourth purpose of this article is to provide a lithium-ion battery.

[0010] The fifth purpose of this article is to provide an application of a lithium-rich solution in the field of lithium-ion batteries.

[0011] In order to achieve the above objectives, the technical solutions adopted in this paper are:

[0012] The first aspect of this invention provides a lithium extraction system, comprising a lithium extraction device and a capacitor device; the lithium extraction device comprises an electrolytic cell and a separator, the separator dividing the electrolytic cell into a cathode chamber and an anode chamber; a cathode is provided in the cathode chamber, and the cathode has an electrode material capable of adsorbing lithium as an electrode; an anode is provided in the anode chamber, and the anode has an electrode material capable of embedding lithium as an electrode; the anode chamber of the lithium extraction device is connected to the negative electrode of the capacitor device via a pipeline; the cathode chamber of the lithium extraction device is connected to the positive electrode of the capacitor device via a pipeline; and an electrolyte is provided in the capacitor device.

[0013] One of the technical solutions for the lithium extraction device in this article has at least the following technical effects: Compared with the lithium extraction system using anion membranes, the lithium extraction system in this article does not use anion membranes, which can avoid the diffusion of some cations such as sodium ions, magnesium ions and other impurities in the cathode chamber into the anode chamber when using anion membranes, thereby causing the problem of more cationic impurities in the extracted lithium-rich solution, thereby reducing the subsequent cost of removing impurities from the extracted lithium-rich solution. In addition, the capacitor device adsorbs the anions and cations inside it to the electrodes on both sides under the action of the electric field. After the capacitor device is powered off, during the lithium extraction process of the lithium extraction device, the anions and cations adsorbed by the electrodes on both sides can be replenished to the anolyte in the anode chamber and the cathode electrolyte in the cathode chamber, so that the anions and cations in the anode chamber and the cathode chamber of the lithium extraction device reach a state of equilibrium, so that the lithium extraction system can still smoothly extract lithium without using anion membranes.

[0014] When the lithium extraction device is working to extract lithium, the lithium ions in the cathode electrolyte are embedded in the cathode, and the anode in the anode chamber releases lithium into the anode electrolyte under the action of the external potential, thereby achieving simultaneous extraction and release of lithium, and higher lithium extraction efficiency. Moreover, when the cathode is fully embedded with lithium ions and becomes a lithium-intercalated electrode, if the lithium-intercalated electrode is used as an anode, the embedded lithium can be released back into the anode electrolyte. Therefore, the cathode after lithium intercalation can be reused as an anode. After the lithium ions in the anode are fully released into the anode electrolyte, if the anode after the lithium ions are released is used as a cathode, lithium ions can still be re-intercalated. Therefore, the anode after the lithium ions are released can be reused as a cathode.

[0015] In some embodiments herein, the capacitor device is connected to a power source, and the capacitor device is charged by the power source.

[0016] In some embodiments herein, the capacitance of the capacitor device is 1125-1200 mF.

[0017] In some embodiments herein, the rated voltage of the capacitor device is 160-180V.

[0018] In some embodiments herein, the capacitor device is a liquid capacitor.

[0019] In some embodiments herein, the anode chamber of the lithium extraction device is connected to the negative electrode of the capacitor device via two pipes; the cathode chamber of the lithium extraction device is connected to the positive electrode of the capacitor device via two pipes, thereby forming two ion circuits.

[0020] In some embodiments herein, an electrolyte is provided in the pipes connecting the lithium extraction device and the capacitor device. Filling the pipes with the electrolyte allows the anions and cations inside the capacitor device to form a connected ion circuit with the cathode electrolyte and anode electrolyte in the lithium extraction device. After the capacitor device is powered off, it is connected to the powered lithium extraction device via the pipe. The electrolyte in the capacitor device and the anions and cations in the cathode chamber and anode chamber of the lithium extraction device move relative to each other, and the anions and cations on both sides of the capacitor device are replenished into the anode electrolyte and cathode electrolyte in the lithium extraction device, so that the anions and cations in the cathode and anode chambers of the lithium extraction system reach a balanced state.

[0021] In some embodiments of the present invention, the pipe connecting the lithium extraction device and the capacitor device is made of epoxy resin or natural rubber, and is made of an insulating and corrosion-resistant material.

[0022] In some embodiments of the present invention, the electrode material capable of adsorbing lithium is selected from at least one of iron phosphate and MnO2.

[0023] In some embodiments of the present invention, the lithium-intercalated electrode material is selected from at least one of lithium iron phosphate, LiMn2O4, and lithium titanate.

[0024] In some embodiments herein, both the cathode and the anode are connected to a power source.

[0025] In some embodiments herein, the anode chamber of the lithium extraction device is filled with an anolyte; in some embodiments herein, the anolyte is water or a sodium chloride solution; in some embodiments herein, the anolyte is water. When water is used as the anolyte, the anode releases the lithium embedded in the anode into the water during the lithium extraction process, thereby making the anolyte a lithium-rich solution. When water is used as the anolyte, impurity cations are not introduced into the lithium-rich solution, greatly reducing the cost of subsequent impurity removal of the lithium-rich solution.

[0026] In some embodiments herein, the cathode chamber of the lithium extraction device is filled with a catholyte; in some embodiments herein, the catholyte is a lithium-containing solution; in some embodiments herein, the catholyte is salt lake brine. The catholyte only needs to contain lithium ions, and the lithium ions in the catholyte are intercalated into the cathode, making the cathode a lithium-intercalating electrode.

[0027] In some embodiments herein, the electrolyte is selected from at least one of sodium chloride, sodium fluoride, sodium nitrate, and potassium chloride. In some embodiments herein, the electrolyte is sodium chloride. During the charging process of the capacitor device, the electrolyte ionizes into anions and cations that are adsorbed onto the electrodes on both sides. When the lithium extraction device is operating, the capacitor device can be powered off and its internal anions and cations can be replenished into the lithium extraction device through a pipeline, allowing the lithium extraction device to continue operating even without the anion membrane.

[0028] A second aspect of the present invention provides a lithium extraction method, which is performed using the lithium extraction system provided in the first aspect of the present invention, and comprises the following steps:

[0029] S1: Filling the anode chamber of the lithium extraction device with an anolyte and simultaneously filling the cathode chamber with a catholyte, wherein the catholyte contains lithium ions; charging the capacitor device and then disconnecting the power supply;

[0030] S2: Powering on the lithium extraction device to extract lithium.

[0031] One of the technical solutions for the lithium extraction method in this article has at least the following technical effects: the lithium extraction method in this article combines a capacitor device to provide anions and cations to balance the anions and cations in the lithium extraction process, so that the method can normally extract lithium without using an anion membrane, and the membraneless lithium extraction method can effectively avoid the use of anion membranes, reducing costs. At the same time, it can also avoid the diffusion of impurity cations through the anion membrane into the lithium-rich solution after lithium extraction, which can greatly reduce the difficulty of subsequent processing and purification processes. Driven by the external potential, the lithium ions in the cathode electrolyte are embedded in the cathode, and the lithium ions in the anode enter the anode electrolyte, realizing the simultaneous extraction and release of lithium, and the higher lithium extraction efficiency.

[0032] In some embodiments herein, the lithium extraction method further includes performing step S3 after step S2; step S3 comprises draining the cathode chamber of the cathode after lithium extraction and refilling the cathode chamber with the cathode electrolyte, swapping the cathode and anode in the lithium extraction device, and then energizing the lithium extraction device to extract lithium. Step S3 enables the method to continuously and efficiently extract lithium.

[0033] In some embodiments of the present invention, the lithium extraction method further includes performing step S3 after step S2; step S3 is: discharging the cathode electrolyte after lithium extraction in the cathode chamber and filling it with the anode electrolyte, discharging the anode electrolyte after lithium release in the anode chamber and filling it with the cathode electrolyte, and then energizing the lithium extraction device to extract lithium.

[0034] In some embodiments of the present invention, the number of cycles of step S3 is no less than two.

[0035] In some embodiments herein, the operating voltage in step S2 is 0.8-1.2V.

[0036] In some embodiments of the present invention, the operating current in step S2 is 0.005-0.02A.

[0037] In some embodiments herein, the cathode electrolyte is salt lake brine.

[0038] In some embodiments herein, the anolyte is selected from at least one of water and sodium chloride solution.

[0039] The third aspect of the present invention provides a lithium-rich solution obtained by extraction using the method provided in the second aspect of the present invention. The lithium-rich solution contains very few cationic impurities, thereby reducing the cost of subsequent purification.

[0040] The fourth aspect of this invention provides a lithium-ion battery prepared from the lithium-rich solution described in the third aspect of this invention.

[0041] The fifth aspect of this article provides the application of the lithium-rich solution provided in the third aspect of this article in the field of lithium-ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] FIG1 is a schematic structural diagram of a lithium extraction system in an embodiment of this invention.

[0043] Reference numerals:

[0044] Capacitor device 1; pipeline 2; cathode 3; electrolytic cell 4; cathode chamber 5; separator 6; anode chamber 7; anode 8. DETAILED DESCRIPTION

[0045] The specific implementation of this invention is further described in detail below with reference to the accompanying drawings and examples, but the implementation and protection of this invention are not limited thereto. It should be noted that if there are any processes not specifically described below, they can be implemented or understood by those skilled in the art with reference to the prior art. The reagents or instruments used without indicating the manufacturer are all conventional products that can be purchased commercially.

[0046] In some embodiments herein, a lithium extraction system includes a lithium extraction device and a capacitor device 1; the lithium extraction device includes an electrolytic cell 4 and a separator 6, the separator 6 dividing the electrolytic cell 4 into a cathode chamber 5 and an anode chamber 7; a cathode 3 is provided in the cathode chamber 5, and the cathode 3 is made of an electrode material that can absorb lithium; an anode 8 is provided in the anode chamber 7, and the anode 8 is made of an electrode material that can intercalate lithium; the anode chamber 7 of the lithium extraction device is connected to the negative electrode of the capacitor device 1 via a pipe 2; the cathode chamber 5 of the lithium extraction device is connected to the positive electrode of the capacitor device 1 via a pipe 2. An electrolyte is provided in the capacitor device 1. After charging is completed, the electrolyte in the capacitor 1 separates into anions and cations. In some embodiments, the capacitor device 1 is a liquid capacitor; in some embodiments, the electrolyte in the liquid capacitor is selected from one of sodium chloride, sodium fluoride, sodium nitrate, potassium chloride, etc. In some embodiments, the electrolyte in the liquid capacitor is sodium chloride.

[0047] In some embodiments herein, the capacitor device 1 is connected to a power source, and the capacitor device 1 is charged by the power source. When the capacitor device 1 is fully charged, the power source is cut off.

[0048] In some embodiments, the capacity of capacitor device 1 is 1125-1200 mF, and the rated voltage of capacitor device 1 is 160-180 V; in some embodiments, the capacity of capacitor device 1 is 1125 mF, and the rated voltage of capacitor device 1 is 180 V; in some embodiments, the capacity of capacitor device 1 is 1200 mF, and the rated voltage of capacitor device 1 is 160 V. When the operating voltage of the lithium extraction device is 0.8-1.2 V and the operating current is 0.005-0.02 A, a full charge of capacitor device 1 can provide the lithium extraction device with approximately 5 hours of operation. When the anions and cations at the electrodes on both sides of capacitor device 1 are completely released, lithium extraction is suspended, and then the capacitor device 1 is charged and the power is turned off, and then the lithium extraction device resumes operation to extract lithium.

[0049] In some embodiments, the anode chamber 7 of the lithium extraction device is connected to the negative electrode of the capacitor device 1 via two pipes 2; the cathode chamber 5 of the lithium extraction device is connected to the positive electrode of the capacitor device 1 via two pipes 2. The pipes 2 form two ion circuits between the lithium extraction device and the capacitor device 1. In some embodiments herein, the pipes 2 connecting the lithium extraction device and the capacitor device 1 are made of epoxy resin or natural rubber. The pipes 2 are made of an insulating and corrosion-resistant material. In some embodiments, the pipes 2 connecting the lithium extraction device and the capacitor device 1 are both filled with electrolyte.

[0050] In some embodiments, the electrode material capable of adsorbing lithium is selected from at least one of iron phosphate and MnO2. In some embodiments, the electrode material capable of adsorbing lithium is iron phosphate. In some embodiments, the electrode material for inserting lithium is selected from at least one of lithium iron phosphate, LiMn2O4, and lithium titanate. In some embodiments, the electrode material for inserting lithium is lithium iron phosphate. In some embodiments, the cathode 3 and the anode 8 are both connected to a power source. When the cathode 3 is an electrode capable of adsorbing lithium and the anode 8 is a lithium inserting electrode, when the lithium extraction device is working to extract lithium, the lithium ions in the cathode electrolyte are inserted into the cathode 3, and the anode 8 in the anode chamber 7 releases lithium into the anode electrolyte under the action of the external potential, thereby achieving simultaneous extraction and release of lithium, and achieving higher lithium extraction efficiency. In addition, when lithium ions are fully embedded in the cathode 3 to become a lithium-embedded electrode, if the lithium-embedded electrode is used as the anode 8, the embedded lithium can be released back into the anode electrolyte. Therefore, the cathode 3 after lithium embedding can be recovered and reused as the anode 8; after the lithium ions in the anode 8 are fully released into the anode electrolyte, if the anode 8 after the lithium ions are released is used as the cathode 3, lithium ions can still be re-embedded. Therefore, the anode 8 after the lithium ions are released can be recovered and reused as the cathode 3.

[0051] In some embodiments, the anode chamber 7 of the lithium extraction apparatus is filled with an anolyte; in some embodiments, the anolyte is water or a sodium chloride solution; in some embodiments, the anolyte is water. In some embodiments, the cathode chamber 5 of the lithium extraction apparatus is filled with a catholyte; in some embodiments, the catholyte is a lithium-containing solution; in some embodiments, the catholyte is salt lake brine.

[0052] In some embodiments herein, a lithium extraction method is performed using the above-mentioned lithium extraction system, and the lithium extraction method includes the following steps:

[0053] S1: Filling the anode chamber 7 of the lithium extraction device with an anolyte and simultaneously filling the cathode chamber 5 with a catholyte containing lithium ions; charging the capacitor device 1 and then disconnecting the power supply;

[0054] S2: The lithium extraction device is powered on to extract lithium. Driven by the external potential, the lithium ions in the cathode electrolyte are embedded in the cathode 3, and the lithium ions in the anode 8 enter the anode electrolyte, so that lithium extraction and release are carried out simultaneously, and the lithium extraction efficiency is higher.

[0055] In some embodiments, the lithium extraction method further includes step S3, which is located after step S2; step S3 is: discharging the cathode electrolyte after lithium extraction in the cathode chamber 5 and refilling it with cathode electrolyte, while swapping the positions of the cathode 3 and the anode 8 in the lithium extraction device, and then powering on the lithium extraction device to extract lithium.

[0056] In some embodiments, the lithium extraction method further includes performing step S3 after step S2; step S3 is: discharging the cathode electrolyte after lithium extraction in the cathode chamber 5 and filling it with the anode electrolyte, discharging the anode electrolyte after lithium release in the anode chamber 7 and filling it with the cathode electrolyte, and then energizing the lithium extraction device to extract lithium.

[0057] In some embodiments, the number of cycles of step S3 is no less than two. Using step S3 can make the method continuously and efficiently extract lithium.

[0058] In some embodiments, the operating voltage in step S2 is 0.8-1.2 V. In some embodiments, the operating current in step S2 is 0.005-0.02 A.

[0059] The following is a further detailed description of the specific implementation of this article in conjunction with specific embodiments:

[0060] Examples 1-2 and Comparative Example 1 all use salt lake brine as the cathode electrolyte. The composition of cations in the salt lake brine is shown in Table 1 below.

[0061] Table 1 Cation composition of salt lake brine used in Examples 1-2 and Comparative Example 1

[0062] As shown in Table 1, Li + The concentration of ions is 0.28g / L, Mg + The concentration of ions is 22.36 g / L, Na + The concentration of Mg ions is 57.3 g / L. + ions and Na + The concentration of ions is higher than that of Li + If the conventional electrochemical lithium extraction method containing anion membrane is used, the Mg content in salt lake brine is high. + ions and Na + Impurity cations such as ions will diffuse into the anode chamber 7, thereby increasing the content of impurity cations in the lithium-rich solution in the anode chamber 7 and increasing the cost of impurity removal. However, Examples 1 and 2 both use an electrochemical lithium extraction method without an anion membrane, and the impurity content of the extracted lithium-rich solution is low, and the lithium extraction efficiency is high.

[0063] Example 1

[0064] The lithium extraction method in this example includes the following steps:

[0065] (1) Constructing a lithium extraction device: the cathode chamber 5 uses an iron phosphate electrode material as an electrode and 1L of salt lake brine as a cathode electrolyte; the anode chamber 7 uses a lithium iron phosphate electrode material as an electrode and pure water as an anode electrolyte, and the cathode chamber 5 and the anode chamber 7 are separated by a separator 6 to complete the construction of the lithium extraction device;

[0066] (2) Add a capacitor device 1 with a capacity of 1125mF and a rated voltage of 180V next to the lithium extraction device, add sodium chloride solution to the capacitor device 1, charge the capacitor, and turn off the power after it is fully charged;

[0067] (3) Use two water-filled capillaries to connect the positive electrode of the fully charged capacitor device 1 to the cathode electrolyte of the lithium extraction device, and connect the negative electrode of the capacitor device 1 to the anode electrolyte of the lithium extraction device; when the capacitor device 1 and the lithium extraction device are connected, the water in the capillaries also becomes electrolyte, so the solution in the capillaries is actually electrolyte.

[0068] (4) Powering on the lithium extraction device so that the lithium extraction device starts working at a voltage of 0.8 V and an average current of 0.01 A;

[0069] (5) The lithium extraction device works to extract lithium. After lithium extraction, the solution in the anode chamber 7 is a lithium-rich solution.

[0070] The total charge of the capacitor device 1 after it is fully charged is: Q = CU = 1.125F × 180V = 202.5C

[0071] The average charge consumed per hour by the lithium extraction device is 0.01A×3600s=36C

[0072] The amount of charge stored in the capacitor device 1 used in this example after being fully charged is sufficient to support the lithium extraction device to operate for 5.625 hours.

[0073] Example 2

[0074] The lithium extraction method in this example includes the following steps:

[0075] (1) Constructing a lithium extraction device, wherein the cathode chamber 5 uses an iron phosphate electrode material as an electrode and 1L of salt lake brine as a cathode electrolyte; the anode chamber 7 uses a lithium iron phosphate electrode material as an electrode and pure water as an anode electrolyte, and the cathode chamber 5 and the anode chamber 7 are separated by a separator 6 to complete the construction of the lithium extraction device;

[0076] (2) Add a capacitor device 1 with a capacity of 1200mF and a rated voltage of 160V next to the lithium extraction device, add sodium chloride solution to the capacitor device 1, charge the capacitor, and turn off the power after it is fully charged;

[0077] (3) Use two water-filled capillaries to connect the positive electrode of the fully charged capacitor device 1 to the cathode electrolyte of the lithium extraction device, and connect the negative electrode of the capacitor device 1 to the anode electrolyte of the lithium extraction device, forming two circuits;

[0078] (4) Power on the lithium extraction device and start working at a voltage of 1.2V;

[0079] (5) The lithium extraction device works to extract lithium. After lithium extraction, the solution in the anode chamber 7 is a lithium-rich solution.

[0080] The average current of the lithium extraction device during the entire working process in this example is 0.01A;

[0081] The total charge of the capacitor device 1 after it is fully charged is Q = CU = 1.2F × 160V = 192C;

[0082] The average charge consumed per hour by the lithium extraction device is 0.01A×3600s=36C

[0083] The amount of charge stored in the capacitor device 1 after being fully charged can support the lithium extraction device to work for 5.33 hours.

[0084] Example 3

[0085] The lithium extraction method in this example is different from the lithium extraction method in Example 1 in that: this example also includes step (6), and step (6) specifically is: the salt lake brine after lithium extraction in the cathode chamber 5 is discharged and refilled with new salt lake brine, and at the same time, the positions of the anode 8 after lithium release and the cathode 3 after lithium adsorption in the lithium extraction device are exchanged, that is: the anode 8 after lithium release is inserted into the cathode chamber 5 as the cathode 3, and the cathode 3 after lithium insertion is inserted into the anode chamber 7 as the anode 8, and then the lithium extraction device is powered on, so that the lithium extraction device starts working at a voltage of 0.8V and an average current of 0.01A to extract lithium.

[0086] Example 4

[0087] As shown in Figure 1, the lithium extraction system in this example includes a lithium extraction device and a capacitor device 1. The lithium extraction device includes an electrolytic cell 4 and a partition 6. The partition 6 is arranged in the electrolytic cell 4, and the partition 6 divides the electrolytic cell 4 into an anode chamber 7 and a cathode chamber 5. The anode chamber 7 is filled with an anolyte, which is pure water. A lithium iron phosphate electrode is inserted into the anolyte, and the lithium iron phosphate electrode is connected to a power supply through a wire; the cathode chamber 5 is filled with a cathode electrolyte, which is salt lake brine. A ferric phosphate electrode is inserted into the cathode electrolyte, and the ferric phosphate electrode is connected to a power supply through a wire; the negative electrode of the capacitor device 1 is connected to the anolyte of the lithium extraction device through two water-filled capillaries; the positive electrode of the capacitor device 1 is connected to the cathode electrolyte of the lithium extraction device through two water-filled capillaries.

[0088] The working principle of the lithium extraction device in this example is as follows: after the capacitor device 1 is charged and powered off, the sodium chloride solution in the capacitor device 1 will be ionized into chloride ions and sodium ions. When the lithium extraction device is powered on, the lithium iron phosphate electrode in the lithium extraction device releases lithium ions into the water, realizing the release of lithium ions, and the anolyte becomes a lithium-rich solution; at the same time, the lithium ions in the salt lake brine are embedded in the iron phosphate electrode, realizing the separation of lithium ions from the salt lake brine. Lithium extraction and lithium release are carried out simultaneously, which can greatly improve the efficiency of lithium extraction. After all the lithium ions in the salt lake brine are extracted, the salt lake brine after lithium extraction in the cathode chamber 5 is discharged, and new salt lake brine is added to the cathode chamber 5. Then, the positions of the original anode 8 and the original cathode 3 are swapped, and the lithium extraction operation can be continued after the lithium extraction device is powered on.

[0089] Example 5

[0090] The lithium-ion battery in this example is prepared using the lithium-rich solution extracted using the method in Example 1 as a lithium source. The lithium-ion battery in this example also includes a positive electrode, a negative electrode, and an electrolyte.

[0091] Comparative Example 1

[0092] The difference between this example and Example 1 is that the capacitor device 1 is not provided in this example, and an anion membrane is used in the lithium extraction device in this example. The specific lithium extraction method in this example is as follows:

[0093] (1) Constructing a lithium extraction device: the cathode chamber 5 uses an iron phosphate electrode material as an electrode and 1L of salt lake brine as a cathode electrolyte; the anode chamber 7 uses a lithium iron phosphate electrode material as an electrode and pure water as an anode electrolyte; and the cathode chamber 5 and the anode chamber 7 are separated by an anion membrane to complete the construction of the lithium extraction device;

[0094] (2) The lithium extraction device is powered on and starts to extract lithium at a voltage of 0.8V.

[0095] The average current of the lithium extraction device in this example during the entire working process is 0.01A.

[0096] Lithium extraction effect test:

[0097] The cation concentrations in the lithium-rich solutions in the anode chamber 7 of Examples 1 and 2 and Comparative Example 1 were tested respectively. The specific test results are shown in Table 2.

[0098] Table 2 Cation concentration of the lithium-rich solution in the anode chamber 7 in Examples 1-2 and Comparative Example 1 (unit: g / L)

[0099] As shown in Table 2, the Mg in the lithium-rich solution extracted by the method in Examples 1 and 2 is +The content of K in the lithium-rich solution extracted by the method in Examples 1 and 2 is 0.02-0.03 g / L, which is 93-96% lower than that in Comparative Example 1. + The content of Na ions was 0.01 g / L, which was reduced by 88.9% compared with Comparative Example 1. The Na + The ion content is 0.05-0.06 g / L, which is 94-95% lower than that of Comparative Example 1. This further shows that compared with the solution using an anion membrane, the embodiment of this invention not using an anion membrane can greatly reduce the content of cationic impurities in the lithium-rich solution.

[0100] The embodiments of this invention are described in detail above, but this invention is not limited to the above embodiments. In addition, the embodiments of this invention and the features in the embodiments can be combined with each other in the absence of conflict.

Claims

1. A lithium extraction system, characterized in that: It comprises a lithium extraction device and a capacitor device; the lithium extraction device comprises an electrolytic cell and a partition, the partition divides the electrolytic cell into a cathode chamber and an anode chamber; a cathode is arranged in the cathode chamber, and the cathode has an electrode material capable of absorbing lithium as an electrode; an anode is arranged in the anode chamber, and the anode has an electrode material capable of embedding lithium as an electrode; the anode chamber of the lithium extraction device is connected to the negative electrode of the capacitor device through a pipeline; the cathode chamber of the lithium extraction device is connected to the positive electrode of the capacitor device through a pipeline; and an electrolyte is arranged in the capacitor device.

2. The lithium extraction system according to claim 1, characterized in that: The capacity of the capacitor device is 1125-1200mF; and / or the rated voltage of the capacitor device is 160-180V.

3. The lithium extraction system according to claim 1, characterized in that: The anode chamber of the lithium extraction device is connected to the negative electrode of the capacitor device through two pipes; the cathode chamber of the lithium extraction device is connected to the positive electrode of the capacitor device through two pipes.

4. The lithium extraction system according to claim 1 or 3, characterized in that: The pipelines connecting the lithium extraction device and the capacitor device are both provided with electrolyte.

5. The lithium extraction system according to claim 1, characterized in that: The electrode material capable of absorbing lithium is selected from at least one of iron phosphate and MnO2.

6. The lithium extraction system according to claim 1, characterized in that: The lithium-embedded electrode material is selected from at least one of lithium iron phosphate, LiMn2O4, and lithium titanate.

7. The lithium extraction system according to claim 1, characterized in that: The electrolyte is selected from at least one of sodium chloride, sodium fluoride, sodium nitrate and potassium chloride.

8. A lithium extraction method, characterized in that: The lithium extraction method is carried out using the lithium extraction system according to any one of claims 1 to 7, and the lithium extraction method comprises the following steps: S1: Filling the anode chamber of the lithium extraction device with an anolyte, and simultaneously filling the cathode chamber with a cathode electrolyte, wherein the cathode electrolyte contains lithium ions; charging the capacitor device and then disconnecting the power supply; S2: Power on the lithium extraction device to extract lithium.

9. The lithium extraction method according to claim 8, characterized in that: The lithium extraction method also includes the step of performing step S3 after step S2; step S3 is: discharging the cathode electrolyte after lithium extraction in the cathode chamber and filling it with cathode electrolyte, while exchanging the positions of the cathode and anode in the lithium extraction device, and then energizing the lithium extraction device to extract lithium.

10. The lithium extraction method according to claim 8, characterized in that: The lithium extraction method also includes the step of performing step S3 after step S2; step S3 is: discharging the cathode electrolyte after lithium extraction in the cathode chamber and filling it with the anode electrolyte, discharging the anode electrolyte after lithium is released in the anode chamber and filling it with the cathode electrolyte, and then energizing the lithium extraction device to extract lithium.

11. The lithium extraction method according to claim 9 or 10, characterized in that: The number of cycles of step S3 is no less than two.

12. The lithium extraction method according to claim 8, characterized in that: The operating voltage in step S2 is 0.8-1.2V.

13. The lithium extraction method according to claim 8, characterized in that: The working current in step S2 is 0.005-0.02A.

14. The lithium extraction method according to claim 8, characterized in that: The cathode electrolyte is salt lake brine.

15. The lithium extraction method according to claim 8, characterized in that: The anolyte is selected from at least one of water and sodium chloride solution.

16. A lithium-rich solution, characterized in that: The method is used to extract the product according to any one of claims 8 to 15.

17. A lithium ion battery, characterized in that: Prepared from the lithium-rich solution according to claim 16.

18. Use of the lithium-rich solution according to claim 16 in the field of lithium-ion batteries.

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