Flowing electrode electrochemical device and lithium ion extraction method

Abstract

The invention relates to a flowing electrode electrochemical device. The flowing electrode electrochemical device comprises two power supplies as well as a first cathode unit, an anode unit and a second cathode unit which are arranged in sequence, a cathode electrolyte flows in the first cathode unit, a mixed solution of the anode electrolyte and a lithium-containing solution flows in the anode unit, the cathode electrolyte flows in the second cathode unit, the first cathode unit and the anode unit are separated by an anionic membrane, and the anode unit and the second cathode unit are separated by a cationic membrane; the anodes of the two power supplies are connected with the anode unit, and the cathodes of the two power supplies are connected with the first cathode unit and the second cathode unit respectively. According to the invention, a lithium-containing solution to be treated is introduced into the anode unit, lithium ions are adsorbed and desorbed into the solution under the action of an electric field, and the lithium ions are promoted to migrate to the second cathode unit and be concentrated under the blocking of the anionic membrane and the driving of the electric field, so that the extraction, concentration and recovery of lithium are realized.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium ion extraction, and particularly to a flow electrode electrochemical device and a lithium ion extraction method. Background Art

[0003] As a new type of electrochemical treatment technology, flow electrode electrochemical technology uses the electric field effect to effectively remove dissolved ions in water through the adsorption and desorption functions of electrodes, and recovers ions with low energy consumption and high efficiency. Traditional flow electrode electrochemical devices usually adopt a single electrode chamber design, mainly for water treatment and general ion removal. However, in the process of lithium resource extraction and concentration, how to efficiently and accurately extract and concentrate lithium ions using a flow electrode electrochemical device still faces technical bottlenecks. Existing technologies usually fail to fully consider the process optimization of lithium ion extraction and concentration, especially the regulation of the adsorption and desorption mechanisms of lithium ions under different electric field intensities, which limits the efficiency and concentration effect of lithium recovery. Summary of the Invention

[0004] Based on this, the purpose of the present invention is to provide a flow electrode electrochemical device and a lithium ion extraction method, which solve the problems of energy consumption and environmental pollution existing in traditional lithium recovery methods, and also provide a more green, economical and efficient recovery method for the recovery of low-concentration lithium solutions.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions: The present invention first provides a flow electrode electrochemical device, which includes two power supplies and a first cathode unit, an anode unit, and a second cathode unit arranged in sequence; cathode electrolyte flows in the first cathode unit, a mixed solution of anode electrolyte and lithium-containing solution flows in the anode unit, and cathode electrolyte flows in the second cathode unit. The first cathode unit and the anode unit are separated by an anion exchange membrane, and the anode unit and the second cathode unit are separated by a cation exchange membrane; the positive electrodes of the two power supplies are both connected to the anode unit, and the negative electrodes of the two power supplies are respectively connected to the first cathode unit and the second cathode unit.

[0006] As a further improvement of the above solution of the present invention, the first cathode unit includes a first end plate and a first current collector sealed and connected in sequence. The first current collector has a first flow channel and cathode electrolyte flows in the first flow channel. The first current collector is connected to the negative electrode of one of the power supplies; a first gasket and a second gasket are respectively arranged between the first current collector and the first end plate and the anion exchange membrane. A window is arranged in the area of the second gasket corresponding to the first flow channel; And / or, the anode unit includes a second current collector, the second current collector has a second flow channel, and a mixed solution of anodic electrolyte and lithium-containing solution flows in the second flow channel. The second current collector is connected to the positive electrodes of two power supplies. A third gasket and a fourth gasket are respectively arranged between the second current collector and the anion exchange membrane and the cation exchange membrane. Windows are arranged in the regions of the third gasket and the fourth gasket corresponding to the second flow channel. And / or, the second cathode unit includes a third current collector and a second end plate which are hermetically connected in sequence. The third current collector has a third flow channel, and cathodic electrolyte flows in the third flow channel. The third current collector is connected to the negative electrode of another power supply. A fifth gasket and a sixth gasket are respectively arranged between the third current collector and the cation exchange membrane and the second end plate. A window is arranged in the region of the fifth gasket corresponding to the third flow channel.

[0007] As a further improvement of the above solution of the present invention, the first flow channel, the second flow channel and / or the third flow channel are distributed in a serpentine shape.

[0008] As a further improvement of the above solution of the present invention, flow holes one are formed in the first end plate, the first gasket and the first current collector, and a plurality of flow holes one are coaxially communicated to form a first liquid inlet flow channel, and the first liquid inlet flow channel is communicated with one end of the first flow channel; flow holes two are formed in the first current collector, the second gasket, the anion exchange membrane, the third gasket, the second current collector, the fourth gasket, the cation exchange membrane, the fifth gasket, the third current collector, the sixth gasket and the second end plate, and a plurality of flow holes two are coaxially communicated to form a first liquid outlet flow channel, and the first liquid outlet flow channel is communicated with the other end of the first flow channel.

[0009] As a further improvement of the above solution of the present invention, flow holes three are formed in the first end plate, the first gasket, the first current collector, the second gasket, the anion exchange membrane, the third gasket and the second current collector, and a plurality of flow holes three are coaxially communicated to form a second liquid inlet flow channel, and the second liquid inlet flow channel is communicated with one end of the second flow channel; flow holes four are formed in the second current collector, the fourth gasket, the cation exchange membrane, the fifth gasket, the third current collector, the sixth gasket and the second end plate, and a plurality of flow holes four are coaxially communicated to form a second liquid outlet flow channel, and the second liquid outlet flow channel is communicated with the other end of the second flow channel.

[0010] As a further improvement of the above solution of the present invention, flow holes five are formed in the first end plate, the first gasket, the first current collector, the second gasket, the anion exchange membrane, the third gasket, the second current collector, the fourth gasket, the cation exchange membrane, the fifth gasket and the third current collector, and a plurality of flow holes five are coaxially communicated to form a third liquid inlet flow channel, and the third liquid inlet flow channel is communicated with one end of the third flow channel; flow holes six are formed in the third current collector, the sixth gasket and the second end plate, and a plurality of flow holes six are coaxially communicated to form a third liquid outlet flow channel, and the third liquid outlet flow channel is communicated with the other end of the third flow channel.

[0011] As a further improvement of the above solution of the present invention, the catholyte is at least one of an aqueous solution containing activated carbon, an aqueous sodium salt solution, an aqueous iron salt solution, an aqueous potassium salt solution, and an aqueous lithium salt solution. Preferably, the concentration of the catholyte is 0.1-5 mol / L.

[0012] As a further improvement of the above solution of the present invention, the anolyte is a conductive salt water mixture.

[0013] As a further improvement of the above solution of the present invention, the flow electrode electrochemical device further includes a first cathode cell, an anode cell, a second cathode cell, a first circulation member, a second circulation member, and a third circulation member. The first circulation member is used to realize the circulating flow of the catholyte between the first cathode unit and the first cathode cell. The second circulation member is used to realize the circulating flow of the mixture of the anolyte and the lithium-containing solution between the anode unit and the anode cell. The third circulation member is used to realize the circulating flow of the catholyte between the second cathode unit and the second cathode cell.

[0014] The present invention also provides a lithium ion extraction method, which uses the flow electrode electrochemical device as described above, and includes the following steps: Circulate a mixture of a lithium-containing solution and an anolyte into the second flow channel; Circulate the catholyte into the first flow channel and the third flow channel respectively; Connect the positive electrodes of the two power supplies to the second current collector, and connect the negative electrodes of the two power supplies to the first current collector and the third current collector respectively; After the electrolysis is completed, collect the solution in the second flow channel and detect the lithium ion content a of the solution; collect the solution in the third flow channel, detect the concentrated lithium ion content b; calculate the lithium extraction rate according to a and b.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The electrochemical device provided by the present invention has an anode unit and two cathode units. The lithium-containing solution to be treated is introduced into the anode unit. Under the action of an electric field, lithium ions are adsorbed and desorbed into the solution. Under the barrier of the anion exchange membrane and the drive of the electric field, the lithium ions are promoted to migrate to the second cathode unit and concentrated, realizing the extraction, concentration, and recovery of lithium. The present invention has operational flexibility, reduces the complexity and operation difficulty of the equipment, and at the same time reduces the floor area and investment cost of the equipment. Description of the Drawings

[0016] Figure 1 It is a schematic structural diagram of a flow electrode electrochemical device provided by the present invention.

[0017] Reference numerals: 1, first end plate; 2, first current collector; 3, anion exchange membrane; 4, second current collector; 5, cation exchange membrane; 6, third current collector; 7, second end plate; 8, first gasket; 9, second gasket; 10, third gasket; 11, fourth gasket; 12, fifth gasket; 13, sixth gasket; 14, first flow hole; 15, second flow hole; 16, third flow hole; 17, fourth flow hole; 18, fifth flow hole; 19, sixth flow hole. Detailed implementation manners

[0018] For ease of understanding of the present invention, the present invention will be described more comprehensively below in conjunction with specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present invention more thorough and comprehensive.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0020] Embodiment 1 Combined with Figure 1 , this embodiment provides a flow-through electrode electrochemical device, which includes two power supplies, a first cathode unit, an anode unit, and a second cathode unit. The first cathode unit and the anode unit are separated by the anion exchange membrane 3, and the anode unit and the second cathode unit are separated by the cation exchange membrane 5; the first cathode unit includes the first end plate 1 and the first current collector 2, the anode unit includes the second current collector 4, and the second cathode unit includes the third current collector 6 and the second end plate 7 that are sequentially and hermetically connected, and may further include a first cathode cell, an anode cell, a second cathode cell, a first circulation member, a second circulation member, and a third circulation member.

[0021] The first end plate 1, the first current collector 2, the anion exchange membrane 3, the second current collector 4, the cation exchange membrane 5, the third current collector 6, and the second end plate 7 are sequentially arranged and closely attached. A plurality of bolts are respectively passed through the first end plate 1, the first current collector 2, the anion exchange membrane 3, the second current collector 4, the cation exchange membrane 5, the third current collector 6, and the second end plate 7, and a plurality of nuts are respectively used to connect with the plurality of bolts to complete the assembly. To further ensure the sealing performance, a first gasket 8 and a second gasket 9 are respectively arranged between the first current collector 2 and the first end plate 1 and the anion exchange membrane 3; a third gasket 10 and a fourth gasket 11 are respectively arranged between the second current collector 4 and the anion exchange membrane 3 and the cation exchange membrane 5; a fifth gasket 12 and a sixth gasket 13 are respectively arranged between the third current collector 6 and the cation and the second end plate 7.

[0022] The first collector 2 is provided with a first flow channel distributed in a serpentine shape, and the second gasket 9 is provided with a window in the area corresponding to the first flow channel. The first end plate 1, the first gasket 8, and the first collector 2 are all provided with a first through hole 14, and a plurality of first through holes 14 are coaxially connected to form a first liquid inlet channel, and the first liquid inlet channel is connected to one end of the first flow channel; the first collector 2, the second gasket 9, the anion exchange membrane 3, the third gasket 10, the second collector 4, the fourth gasket 11, the cation exchange membrane 5, the fifth gasket 12, the third collector 6, the sixth gasket 13, and the second end plate 7 are all provided with a second through hole 15, and a plurality of second through holes 15 are coaxially connected to form a first liquid outlet channel, and the first liquid outlet channel is connected to the other end of the first flow channel.

[0023] The second collector 4 is provided with a second flow channel distributed in a serpentine shape, and the third gasket 10 and the fourth gasket 11 are both provided with windows in the areas corresponding to the second flow channel. The first end plate 1, the first gasket 8, the first collector 2, the second gasket 9, the anion exchange membrane 3, the third gasket 10, and the second collector 4 are all provided with a third through hole 16, and a plurality of third through holes 16 are coaxially connected to form a second liquid inlet channel, and the second liquid inlet channel is connected to one end of the second flow channel; the second collector 4, the fourth gasket 11, the cation exchange membrane 5, the fifth gasket 12, the third collector 6, the sixth gasket 13, and the second end plate 7 are all provided with a fourth through hole 17, and a plurality of fourth through holes 17 are coaxially connected to form a second liquid outlet channel, and the second liquid outlet channel is connected to the other end of the second flow channel.

[0024] The third collector 6 is provided with a third flow channel distributed in a serpentine shape, and the fifth gasket 12 is provided with a window in the area corresponding to the third flow channel. The first end plate 1, the first gasket 8, the first collector 2, the second gasket 9, the anion exchange membrane 3, the third gasket 10, the second collector 4, the fourth gasket 11, the cation exchange membrane 5, the fifth gasket 12, and the third collector 6 are all provided with a fifth through hole 18, and a plurality of fifth through holes 18 are coaxially connected to form a third liquid inlet channel, and the third liquid inlet channel is connected to one end of the third flow channel; the third collector 6, the sixth gasket 13, and the second end plate 7 are all provided with a sixth through hole, and a plurality of sixth through holes are coaxially connected to form a third liquid outlet channel, and the third liquid outlet channel is connected to the other end of the third flow channel.

[0025] In this embodiment, the first collector 2, the second collector 4, and the third collector 6 are all made of ruthenium-plated titanium plates. The positive electrodes of two 400 mA power supplies are both connected to the second collector 4, and the negative electrodes of the two 400 mA power supplies are respectively connected to the first collector 2 and the third collector 6.

[0026] The first cathode cell is filled with a cathode electrolyte, and the first circulation component is used to realize the circulating flow of the cathode electrolyte between the first flow channel and the first cathode cell. The first circulation component can be a peristaltic pump, and the cathode electrolyte is at least one of an aqueous solution containing activated carbon, an aqueous sodium salt solution, an aqueous iron salt solution, an aqueous potassium salt solution, and an aqueous lithium salt solution. In this embodiment, the cathode electrolyte in the first flow channel is a 0.2M hydrochloric acid solution, and the flow rate is adjusted to 50 mL / min.

[0027] The anode cell is filled with a mixture of an anode electrolyte and a lithium-containing solution, and the second circulation component is used to realize the circulating flow of the mixture of the anode electrolyte and the lithium-containing solution between the second flow channel and the anode cell. The second circulation component can be a peristaltic pump, and the anode electrolyte is a conductive salt water mixture. In this embodiment, the anode electrolyte is a 0.1M sodium chloride solution, and the lithium-containing solution is prepared by mixing lithium iron phosphate powder material peeled from a waste lithium iron phosphate battery with deionized water at a ratio of 1 g:100 mL. The flow rate of the mixture of the anode electrolyte and the lithium-containing solution is adjusted to 50 mL / min.

[0028] The second cathode cell is filled with a cathode electrolyte, and the third circulation component is used to realize the circulating flow of the cathode electrolyte between the third flow channel and the second cathode cell. The third circulation component can be a peristaltic pump, and the cathode electrolyte is at least one of an aqueous solution containing activated carbon, an aqueous sodium salt solution, an aqueous iron salt solution, an aqueous potassium salt solution, and an aqueous lithium salt solution. In this embodiment, the cathode electrolyte in the third flow channel is a 1M potassium hydroxide solution, and the flow rate is adjusted to 50 mL / min.

[0029] In this embodiment, through the above structural settings, the positive clamp of a 400 mA power supply is clamped on the second current collector 4, and the negative clamp is clamped on the first current collector 2. The reaction in the interval between the first current collector 2 and the second current collector 4 is for lithium deintercalation, which can be defined as the lithium extraction chamber; when the positive clamp of another 400 mA power supply is also clamped on the second current collector 4, and the negative clamp is clamped on the third current collector 6, the reaction in the interval between the second current collector 4 and the third current collector 6 is for concentrating the deintercalated lithium, which can be defined as the lithium concentration chamber; after constant current charging (400 mA) for 1 h, the solution in the anode unit is collected to detect the lithium ion content a of the solution, and at the same time, the solution in the second cathode unit is collected to detect the concentrated lithium ion content b; the sum of a and b is the Li content deintercalated in the entire electrolysis experiment, and then the lithium deintercalation rate can be calculated. It is analyzed that the lithium extraction efficiency reaches more than 85%.

[0030] Example 2 This embodiment adopts the same implementation method as Embodiment 1. The difference from Embodiment 1 is that in this embodiment, the first current collector 2, the second current collector 4, and the third current collector 6 all adopt graphite plates; an activated carbon conductive brine solution (9% activated carbon, 1% Ketjen black, and the balance is Na2SO4 solution with a concentration of 0.05M) flows in the first flow channel; a mixed solution of 1M lithium chloride solution and a lithium-containing solution flows in the second flow channel, and the lithium-containing solution is prepared from lithium iron phosphate powder material peeled from a waste lithium iron phosphate battery and deionized water in a ratio of 1g:100mL; a 0.5M sodium chloride solution flows in the third flow channel.

[0031] With the above structural settings in this embodiment, the positive electrode of a 2V power supply is clamped between the second current collector 4, and the negative electrode is clamped between the first current collector 2; the positive electrode of a 3V power supply is clamped between the second current collector 4, and the negative electrode is clamped between the third current collector 6; after constant voltage charging for 1h, the solution in the anode unit is collected to detect the lithium ion content a of the solution, and at the same time, the solution in the second cathode unit is collected to detect the concentrated lithium ion content b; the sum of a and b is the Li content released in the entire electrolysis experiment, and then the lithium extraction rate can be calculated. It is analyzed that the lithium extraction efficiency reaches more than 90%.

[0032] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0033] The above-described embodiments only represent several implementation modes of the present invention. Their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent should be subject to the appended claims.

Claims

1. A flow electrode electrochemical device, characterized in that, It includes two power supplies, and a first cathode unit, an anode unit, and a second cathode unit arranged in sequence; cathode electrolyte flows in the first cathode unit, a mixed solution of anode electrolyte and lithium-containing solution flows in the anode unit, and cathode electrolyte flows in the second cathode unit. The first cathode unit and the anode unit are separated by an anion exchange membrane, and the anode unit and the second cathode unit are separated by a cation exchange membrane; the positive electrodes of the two power supplies are both connected to the anode unit, and the negative electrodes of the two power supplies are respectively connected to the first cathode unit and the second cathode unit.

2. The flow electrode electrochemical device according to claim 1, wherein, The first cathode unit includes a first end plate and a first current collector that are hermetically connected in sequence. The first current collector has a first flow channel and cathode electrolyte flows in the first flow channel. The first current collector is connected to the negative electrode of one of the power supplies; a first gasket and a second gasket are respectively arranged between the first current collector and the first end plate and the anion exchange membrane, and a window is arranged in the area of the second gasket corresponding to the first flow channel. And / or, the anode unit includes a second current collector. The second current collector has a second flow channel and a mixed solution of anode electrolyte and lithium-containing solution flows in the second flow channel. The second current collector is connected to the positive electrodes of the two power supplies. A third gasket and a fourth gasket are respectively arranged between the second current collector and the anion exchange membrane and the cation exchange membrane, and windows are arranged in the areas of the third gasket and the fourth gasket corresponding to the second flow channel. And / or, the second cathode unit includes a third current collector and a second end plate that are hermetically connected in sequence. The third current collector has a third flow channel and cathode electrolyte flows in the third flow channel. The third current collector is connected to the negative electrode of the other power supply; a fifth gasket and a sixth gasket are respectively arranged between the third current collector and the cation exchange membrane and the second end plate, and a window is arranged in the area of the fifth gasket corresponding to the third flow channel.

3. The flow electrode electrochemical device according to claim 2, wherein, The first flow channel, the second flow channel, and / or the third flow channel are distributed in a serpentine shape.

4. The flow electrode electrochemical device according to claim 2, wherein Flow holes one are provided on the first end plate, the first gasket, and the first current collector, and a plurality of flow holes one are coaxially connected to form a first liquid inlet flow channel, and the first liquid inlet flow channel is connected to one end of the first flow channel; flow holes two are provided on the first current collector, the second gasket, the anion exchange membrane, the third gasket, the second current collector, the fourth gasket, the cation exchange membrane, the fifth gasket, the third current collector, the sixth gasket, and the second end plate, and a plurality of flow holes two are coaxially connected to form a first liquid outlet flow channel, and the first liquid outlet flow channel is connected to the other end of the first flow channel.

5. The flow electrode electrochemical device according to claim 2, wherein Flow holes three are provided on the first end plate, the first gasket, the first current collector, the second gasket, the anion exchange membrane, the third gasket, and the second current collector, and a plurality of flow holes three are coaxially connected to form a second liquid inlet flow channel, and the second liquid inlet flow channel is connected to one end of the second flow channel; flow holes four are provided on the second current collector, the fourth gasket, the cation exchange membrane, the fifth gasket, the third current collector, the sixth gasket, and the second end plate, and a plurality of flow holes four are coaxially connected to form a second liquid outlet flow channel, and the second liquid outlet flow channel is connected to the other end of the second flow channel.

6. The flow electrode electrochemical device according to claim 2, wherein A first end plate, a first gasket, a first current collector, a second gasket, an anion exchange membrane, a third gasket, a second current collector, a fourth gasket, a cation exchange membrane, a fifth gasket, and a third current collector are each provided with a fifth flow hole, and a plurality of the fifth flow holes are coaxially connected to form a third inlet flow channel, and the third inlet flow channel is connected to one end of the third flow channel; the third current collector, a sixth gasket, and a second end plate are each provided with a sixth flow hole, and a plurality of the sixth flow holes are coaxially connected to form a third outlet flow channel, and the third outlet flow channel is connected to the other end of the third flow channel.

7. The flow electrode electrochemical device according to claim 1, wherein The cathode electrolyte is at least one of an aqueous solution containing activated carbon, an aqueous sodium salt solution, an aqueous iron salt solution, an aqueous potassium salt solution, and an aqueous lithium salt solution.

8. The flow electrode electrochemical device according to claim 1, wherein, The anode electrolyte is a conductive saline mixture.

9. The flow electrode electrochemical device according to claim 1, characterized in that, The flow-through electrode electrochemical device further includes a first cathode cell, an anode cell, a second cathode cell, a first circulation member, a second circulation member, and a third circulation member. The first circulation member is used to circulate the cathode electrolyte between the first cathode unit and the first cathode cell. The second circulation member is used to circulate the mixture of the anode electrolyte and the lithium-containing solution between the anode unit and the anode cell. The third circulation member is used to circulate the cathode electrolyte between the second cathode unit and the second cathode cell.

10. A lithium-ion extraction method, characterized in that, It uses the flow-through electrode electrochemical device according to any one of claims 1-9, and includes the following steps: Circulating a mixture of a lithium-containing solution and an anode electrolyte into the second flow channel; Circulating the cathode electrolyte into the first flow channel and the third flow channel respectively; Connecting the positive electrodes of two power supplies to the second current collector, and connecting the negative electrodes of the two power supplies to the first current collector and the third current collector respectively; After the electrolysis is completed, collecting the solution in the second flow channel to detect the lithium ion content a of the solution; collecting the solution in the third flow channel, detecting the concentrated lithium ion content b; and calculating the lithium extraction rate according to a and b.

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