Electrochemical lithium electrolysis device and electrochemical lithium electrolysis method for anode black powder of waste LFP battery

Abstract

The invention relates to an electrochemical lithium electrolysis device and an electrochemical lithium electrolysis method for positive electrode black powder of a waste LFP battery. The electrochemical lithium electrolysis device comprises an anode unit, a cathode unit, an ionic membrane, an anode tank, a cathode tank, a circulating part I, a circulating part II and a power supply, an anode channel and a cathode channel are arranged on the sides, facing the ionic membrane, of the anode unit and the cathode unit respectively; a mixture of anolyte and waste LFP battery positive electrode black powder is arranged in the anode tank, and the first circulating part is used for achieving circulation of the mixture between the anode tank and the anode channel; a cathode electrolyte is arranged in the cathode tank, and the circulating part II is used for realizing the circulation of the cathode electrolyte between the cathode tank and the cathode channel. The anolyte and the catholyte can directionally flow, Li < + > released by the LFP powder is promoted to be diffused into the electrolytes, the reaction with the highest efficiency is achieved, the LFP can be subjected to subsequent chemical oxidation, the oxidation process of the LFP is accelerated, and therefore more efficient lithium leaching is driven.

Description

Technical Field

[0001] The invention relates to the technical field of recycling black powder from positive electrodes of waste LFP batteries, and in particular to an electrochemical lithium decomposition device and a method for electrochemical lithium decomposition of black powder from positive electrodes of waste LFP batteries. Background Art

[0002] my country's new energy vehicle sales have been increasing since 2015, and have maintained a rapid growth trend since then. Combined with the current average service life of automotive power batteries, which is about 5-8 years, it can be inferred that the new energy vehicle power batteries promoted in the early stage of China have gradually entered the scrap period. With the vigorous promotion of new energy vehicles in recent years, sales have achieved rapid growth. It is expected that power batteries will usher in a large-scale retirement wave in the next 2-3 years, and the demand for recycling retired power batteries has become increasingly urgent. LFP batteries have gradually occupied half of the electric vehicle market share in recent years due to their excellent safety and excellent stability. Only by doing a good job in the recycling of power batteries can the development of the new energy vehicle industry truly return from "green to green".

[0003] Lithium is the most valuable element in LFP batteries, and its current production capacity cannot meet the rapidly growing lithium demand. Waste LFP batteries contain toxic electrolytes, heavy metals, organic chemicals and plastics, which will cause serious environmental problems if not properly handled.

[0004] In the traditional waste LFP battery recycling process, most of them rely on acid / alkali leaching, which seriously damages the crystal structure of iron phosphate, is accompanied by a high iron dissolution rate, and has a high recycling cost. At present, there are also methods for using electrochemical devices to de-lithiate waste LFP. For example, the patent with publication number CN116479448A discloses a recycling device and method for waste lithium iron phosphate battery positive electrode materials. However, this method requires the introduction of oxygen and heating during the reaction process. The solid-liquid-gas three-phase reaction is very cumbersome, and the cost of continuous oxygen introduction is high. Summary of the invention

[0005] Based on this, the purpose of the present invention is to provide an electrochemical lithium decomposition device and an electrochemical lithium decomposition method for the positive electrode black powder of waste LFP batteries, wherein the anolyte and the cathode electrolyte can flow in a directional manner, thereby promoting the diffusion of Li+ released by the LFP powder into the electrolyte to achieve its most efficient reaction, and the active free radicals generated in situ at the cathode enter the anode cell through the ion membrane and maintain a higher oxidation potential than that of the LFP, thereby enabling the LFP to undergo subsequent chemical oxidation, accelerating the oxidation process of the LFP, and thereby driving more efficient lithium leaching.

[0006] To achieve the above object, the present invention adopts the following technical solutions: The present invention first provides an electrochemical lithium dissolution device, which comprises an anode unit, a cathode unit, an ion membrane, an anode pool, a cathode pool, a circulation component one, a circulation component two and a power source; the anode unit and the cathode unit are respectively sealed and arranged on both sides of the ion membrane, and the anode unit and the cathode unit are respectively provided with an anode channel and a cathode channel on one side facing the ion membrane; a mixture of an anode electrolyte and positive electrode black powder of waste LFP batteries is arranged in the anode pool, and the circulation component one is used to realize the circulation of the mixture between the anode pool and the anode channel; a cathode electrolyte is arranged in the cathode pool, and the circulation component two is used to realize the circulation of the cathode electrolyte between the cathode pool and the cathode channel; the power source is electrically connected to the anode unit and the cathode unit.

[0007] As a further improvement of the above scheme of the present invention, the anode unit includes an anode insulating end plate, an anode current collector plate and an anode electrolytic cell which are arranged in sequence; the anode insulating end plate is provided with inlet one and outlet one; inlet two and outlet two are provided on the anode current collector plate and inlet two and outlet two are connected with inlet one and outlet one respectively; an anode channel is provided on the side of the anode electrolytic cell facing the ion membrane and the anode channel is connected with inlet two and outlet two, a seal one is provided between the anode electrolytic cell and the ion membrane, and the seal one is opened in the area corresponding to the anode channel.

[0008] As a further improvement of the above scheme of the present invention, the anode current collector plate adopts a ruthenium-plated titanium plate; and / or, an anode insulating sheet is arranged between the anode current collector plate and the anode insulating end plate, and an inlet three and an outlet three are opened on the anode insulating sheet, and the two ends of inlet three are respectively connected to inlet one and inlet two, and the two ends of outlet three are respectively connected to outlet one and outlet two.

[0009] As a further improvement of the above scheme of the present invention, the cathode unit includes a cathode insulating end plate, a cathode current collector plate and a cathode electrolytic cell which are arranged in sequence; an inlet four and an outlet four are opened on the cathode insulating end plate; an inlet five and an outlet five are opened on the cathode current collector plate and the inlet five and the outlet five are connected with the inlet four and the outlet four respectively; a cathode channel is opened on the side of the cathode electrolytic cell facing the ion membrane and the cathode channel is connected with the inlet five and the outlet five, and a seal two is arranged between the cathode electrolytic cell and the ion membrane, and the seal two is opened in the area corresponding to the cathode channel.

[0010] As a further improvement of the above scheme of the present invention, the cathode current collector plate adopts a ruthenium-plated titanium plate; and / or, a cathode insulating sheet is arranged between the cathode current collector plate and the cathode insulating end plate, and an inlet six and an outlet six are opened on the cathode insulating sheet, and the two ends of the inlet six are respectively connected to the inlet four and the inlet five, and the two ends of the outlet six are respectively connected to the outlet four and the outlet five.

[0011] As a further improvement of the above solution of the present invention, the anode channel and the cathode channel are both distributed in a serpentine shape; and / or the ion membrane is a cation exchange membrane.

[0012] As a further improvement of the above scheme of the present invention, the anolyte is a NaCl solution with a concentration of 0.1-0.5 mol / L; and / or the catholyte is a NaCl solution or a NaCl solution and concentrated hydrochloric acid, wherein the concentration of the NaCl solution is 0.1-0.5 mol / L, and the volume ratio of concentrated hydrochloric acid to NaCl solution is 4%.

[0013] As a further improvement of the above solution of the present invention, the circulation member 1 includes two peristaltic pumps 1 and 2, the inlet of the peristaltic pump 1 is connected to the anode pool through a pipeline and the outlet thereof is connected to the anode channel through a pipeline, the inlet of the peristaltic pump 2 is connected to the anode channel through a pipeline and the outlet thereof is connected to the anode pool through a pipeline; And / or, the circulation component 2 includes a peristaltic pump 3 and a peristaltic pump 4, the inlet of the peristaltic pump 3 is connected to the cathode pool through a pipeline and the outlet thereof is connected to the cathode channel through a pipeline, the inlet of the peristaltic pump 4 is connected to the cathode channel through a pipeline and the outlet thereof is connected to the cathode pool through a pipeline.

[0014] The present invention also provides a method for electrochemical lithium decomposition of waste LFP battery positive electrode black powder, which uses the electrochemical lithium decomposition device as described above and includes the following steps: S1. Add the recycled waste LFP battery positive electrode black powder to the anode tank, and then add the anolyte to the anode tank; S2. adding catholyte to the cathode cell; S3. Start cycle one and cycle two, and simultaneously connect the anode unit and cathode unit to a power source for electrolysis; S4. After the electrolysis is completed, the mixture in the anode tank is separated into solid and liquid to obtain Li + The filtrate and residue FePO4.

[0015] As a further improvement of the above scheme of the present invention, in step S1, the mass volume ratio of the waste LFP battery positive electrode black powder and the anolyte is 10-30g:1L, and the anolyte is a NaCl solution with a concentration of 0.1-0.5mol / L; And / or, in step S2, the cathode electrolyte is a NaCl solution or a NaCl solution and concentrated hydrochloric acid, wherein the concentration of the NaCl solution is 0.1-0.5 mol / L, and the volume ratio of the concentrated hydrochloric acid to the NaCl solution is 4%; And / or, in step S3, the power supply of the power supply is 1-4V.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The electrochemical lithium dissolution device of the present invention is provided with a circulation part 1 and a circulation part 2, so that the anolyte and the cathode electrolyte can flow in a directional manner, thereby promoting the release of Li from the LFP powder. +The cathode reacts by diffusing into the electrolyte to achieve the highest efficiency. The active free radicals generated in situ at the cathode enter the anode cell through the ion membrane and maintain a higher oxidation potential than that of LFP, enabling subsequent chemical oxidation of LFP and accelerating the oxidation process of LFP, thereby driving more efficient lithium leaching. The electrolysis method is used to promote the recycling of the medium and guide the continuous oxidation of the waste LFP without destroying the iron phosphate crystal form. The anode electrolyte uses a neutral solution, so there is no damage to the crystal structure of the waste LFP. The only concentrated hydrochloric acid solution used is used in small amounts, saving costs and being environmentally friendly.

[0017] The entire process of electrochemical lithium decomposition of the present invention does not require a large amount of immersion in strong acids and alkalis, has low cost, no secondary pollution, and will not destroy the crystal structure of iron phosphate, so it is more conducive to subsequent recovery and regeneration. At the same time, the electrochemical lithium decomposition device provided by the present invention has a simple structure and is easy to scale up. Due to its flow circulation characteristics, it has continuous productivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic structural diagram of an electrochemical lithium dissolution device proposed in Example 1 of the present invention; Figure 2 for Figure 1 The front view of the middle anode electrolytic cell; Figure 3 for Figure 1 A front view of the middle cathode electrolytic cell; Figure 4 This is a SEM image of the iron phosphate solid material obtained in Experimental Example 2; Figure 5 This is the XRD pattern of the iron phosphate solid material obtained in Experimental Example 2.

[0019] Figure numerals: 1, anode cell; 2, anode insulating end plate; 3, anode insulating sheet; 4, anode current collector plate; 5, anode electrolytic cell; 5-1, anode channel; 6, seal one; 7, ion membrane; 8, seal two; 9, cathode electrolytic cell; 9-1 cathode channel; 10, cathode current collector plate; 11, cathode insulating sheet; 12, cathode insulating end plate; 13, cathode cell; 14, peristaltic pump one; 15, peristaltic pump two; 16, peristaltic pump three; 17, peristaltic pump four. DETAILED DESCRIPTION

[0020] For ease of understanding of the present invention, the present invention will be described more fully 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, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly understood.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. 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.

[0022] Example 1 Reference Figure 1 This embodiment provides an electrochemical lithium dissolution device, which includes an anode unit, a cathode unit, an ion membrane 7, an anode pool 1, a cathode pool 13, a circulation component 1, a circulation component 2 and a power supply (not shown).

[0023] The anode unit includes an anode insulating end plate 2, an anode current collector plate 4 and an anode electrolytic cell 5 arranged in sequence. The anode insulating end plate 2 is provided with an inlet 1 and an outlet 1 at the diagonal positions at the upper and lower ends. In this embodiment, the anode insulating end plate 2 adopts an acrylic plate of 8cm×10cm×2.5cm. Of course, in other embodiments, the anode insulating end plate 2 can also be other insulating materials and other shapes. A plurality of screw holes 1 are provided in the circumferential direction of the edge of the anode insulating end plate 2. The anode current collector plate 4 is provided with an inlet 2 and an outlet 2 at the diagonal positions at the upper and lower ends. In this embodiment, the anode current collector plate 4 adopts a ruthenium-plated titanium plate of 6cm×8cm×0.5cm, and a 6cm×8cm anode insulating sheet 3 is provided between the anode current collector plate 4 and the anode insulating end plate 2. The anode insulating sheet 3 is provided with an inlet 3 and an outlet 3 at the diagonal positions at the upper and lower ends, respectively. The two ends of the inlet 3 are coaxially connected with the inlet 1 and the inlet 2, respectively, and the two ends of the outlet 3 are coaxially connected with the outlet 1 and the outlet 2, respectively. In this embodiment, the anode insulating sheet 3 is made of PVC. Of course, in other embodiments, the anode current collector plate 4 can also be made of other conductive materials. An anode channel 5-1 is provided on one side of the anode electrolyzer 5 away from the anode current collector plate 4. In this embodiment, the anode channel is distributed in a serpentine shape and the upper and lower ends of the anode channel are connected to the second inlet and the second outlet respectively.

[0024] The cathode unit includes a cathode insulating end plate 12, a cathode current collector plate 10 and a cathode electrolytic cell 9 arranged in sequence. The cathode insulating end plate 12 is provided with inlet four and outlet four at diagonal positions at the upper and lower ends. In this embodiment, the cathode insulating end plate 12 adopts an acrylic plate of 8cm×10cm×2.5cm. Of course, in other embodiments, the cathode insulating end plate 12 can also be other insulating materials and other shapes. A plurality of screw holes 2 are provided in the circumferential direction of the edge of the cathode insulating end plate 12. Inlet five and outlet five are provided at diagonal positions at the upper and lower ends of the cathode current collector plate 10. In this embodiment, the cathode current collector plate 10 adopts a ruthenium-plated titanium plate of 6cm×8cm×0.5cm, and a 6cm×8cm cathode insulating sheet 11 is provided between the cathode current collector plate 10 and the cathode insulating end plate 12. Inlet six and outlet six are provided at diagonal positions at the upper and lower ends of the cathode insulating sheet 11, and the two ends of the inlet six are coaxially connected with the inlet four and the inlet five, respectively, and the two ends of the outlet six are coaxially connected with the outlet four and the outlet five, respectively. In this embodiment, the cathode insulating sheet 11 is made of PVC. Of course, in other embodiments, the cathode current collector plate 10 can also be made of other conductive materials. A cathode channel 9-1 is provided on one side of the cathode electrolytic cell 9 away from the cathode current collector plate 10. In this embodiment, the cathode channel is distributed in a serpentine shape and the upper and lower ends of the cathode channel are connected to the inlet 5 and the outlet 5.

[0025] The ion membrane 7 is arranged between the anode electrolyzer 5 and the cathode electrolyzer 9. The ion membrane 7 adopts a 2cm×4cm single-layer cation exchange membrane. A 6cm×8cm seal 1 6 is arranged between the ion membrane 7 and the anode electrolyzer 5, and the seal 1 6 is opened in the area corresponding to the anode channel. A 6cm×8cm seal 2 8 is arranged between the ion membrane 7 and the cathode electrolyzer 9, and the seal 2 8 is opened in the area corresponding to the cathode channel. In this embodiment, the seal 1 6 and the seal 2 8 are both made of PVC.

[0026] In this embodiment, in order to achieve the sealing between the anode unit, the cathode unit, and the ion membrane 7, the multiple screw holes 1 of the anode insulating end plate 2 are respectively arranged in correspondence with the multiple screw holes 2 of the cathode insulating end plate 12, and the multiple bolts are respectively passed through the multiple screw holes 1 and then respectively passed through the multiple screw holes 2 in sequence, and multiple nuts are used to be connected with the multiple bolts respectively, so as to tightly fix the anode unit, the cathode unit, and the ion membrane 7 together.

[0027] A mixture of anolyte and black powder of the positive electrode of waste LFP batteries is provided in the anode pool 1. In this embodiment, the anode pool 1 can directly adopt a conventional beaker, and the anode pool 1 is placed on a magnetic stirrer. In the anode pool 1, the mass volume ratio of the black powder of the positive electrode of the waste LFP battery and the anolyte is 10-30g:1L, wherein the anolyte is a NaCl solution with a concentration of 0.1-0.5mol / L, and the liquid volume in the anode pool 1 is not less than 100mL.

[0028] A cathode electrolyte is provided in the cathode pool 13. In the present embodiment, the cathode pool 13 can directly adopt a conventional beaker, and the cathode pool 13 is placed on a magnetic stirrer. In the present embodiment, the cathode electrolyte is a mixture of a NaCl solution and concentrated hydrochloric acid, and the concentration of the NaCl solution is 0.1-0.5 mol / L. In the cathode electrolyte, the volume ratio of concentrated hydrochloric acid to NaCl solution is 4%, and the liquid volume in the cathode pool 13 is not less than 100 mL. Since concentrated hydrochloric acid is volatile, in the present embodiment, in order to make the most efficient use of concentrated hydrochloric acid during the electrolysis process, concentrated hydrochloric acid is added to the cathode pool 13 in batches, and the interval between two adjacent times is 10 min.

[0029] The circulation part 1 is used to realize the circulation of the mixture of the anode electrolyte and the positive electrode black powder of the waste LFP battery between the anode pool 1 and the anode channel. In this embodiment, the circulation part 1 includes two peristaltic pumps 14 and 15, the inlet of the peristaltic pump 14 is connected to the anode pool 1 through a hose and its outlet is connected to the inlet 1 through a hose, and the inlet of the peristaltic pump 2 15 is connected to the outlet 1 through a hose and its outlet is connected to the anode pool 1 through a hose.

[0030] The circulation part 2 is used to realize the circulation of the cathode electrolyte between the cathode pool 13 and the cathode channel. In this embodiment, the circulation part 2 includes a peristaltic pump 3 16 and a peristaltic pump 4 17, the inlet of the peristaltic pump 3 16 is connected to the cathode pool 13 through a hose and its outlet is connected to the inlet 4 through a hose, and the inlet of the peristaltic pump 4 17 is connected to the outlet 4 through a hose and its outlet is connected to the cathode pool 13 through a hose.

[0031] The power source is electrically connected to the anode current collector plate 4 and the cathode current collector plate 10 through a wire. In this embodiment, the power source has a voltage of 0-3V.

[0032] The above structure of the electrochemical lithium decomposition device of this embodiment is carried out according to the following steps when electrochemical lithium decomposition is performed on the positive electrode black powder of the waste LFP battery: S1. Add the recycled waste LFP battery positive electrode black powder (grind the recycled waste LFP positive electrode sheet into powder, roast it at 400-700℃ for 1-3h to remove the carbon black therein to obtain the waste LFP battery positive electrode black powder) into the anode pool 1, and then add NaCl solution (concentration of 0.1-0.5mol / L) into the anode pool 1. Keep the magnetic stirrer under the anode pool 1 in a stirring state, and the stirring speed of the magnetic stirrer is 300r / min~500r / min.

[0033] S2. Add NaCl solution (concentration of 0.1-0.5 mol / L) into the cathode pool 13, and keep the magnetic stirrer under the cathode pool 13 in a stirring state at a stirring speed of 300 r / min~500 r / min.

[0034] S3. Start peristaltic pump 1 and peristaltic pump 2, the mixture in anode cell 1 enters into anode channel along inlet 1, inlet 3 and inlet 2, flows downward in anode channel and flows back into anode cell along outlet 2, outlet 3 and outlet 1; start peristaltic pump 3 and peristaltic pump 4 at the same time, the NaCl solution in cathode cell 13 enters into cathode channel along inlet 4, inlet 5 and inlet 6, flows downward in cathode channel and flows back into cathode cell along outlet 6, outlet 5 and outlet 4; connect anode current collector plate and cathode current collector plate to power source and perform electrolysis at room temperature, after the start of electrolysis, add concentrated hydrochloric acid to cathode cell every 10 minutes (the volume of concentrated hydrochloric acid added in a single time accounts for 1% of the volume of NaCl solution in cathode cell), add four times in total, and the electrolysis time is 1-2h.

[0035] S4. After the electrolysis is completed, the mixture in the anode cell 1 is separated into solid and liquid to obtain a Li-containing + The filtrate and residue FePO4.

[0036] When electrolysis begins, oxidation reaction occurs at the anode, and Fe 2+ Oxidized to Fe 3+ , which leads to Li + The LFP is released, and a reduction reaction occurs in the cathode pool 13, and the active hydrogen radicals enter the anode pool 1 through the cation exchange membrane, thereby accelerating the oxidation process of LFP.

[0037] The reaction equation in the anode cell 1 of this embodiment is as follows: LiFePO4+2H + →Li + +FePO4+H2↑ 2Cl⁻-2e⁻→Cl2↑ The reaction equation in the cathode pool 13 of this embodiment is as follows: 2H2O+2e⁻=H2↑+2OH⁻ The present invention can decompose lithium without destroying the crystal structure of iron phosphate, and has continuous production due to its flow cycle characteristics. The electrochemical waste LFP delithiation method provided by the present invention does not require a large amount of strong acid and alkali immersion during the entire process, has low cost, no secondary pollution, and will not destroy the crystal structure of iron phosphate, so it is more conducive to subsequent recycling and regeneration. At the same time, the electrochemical lithium decomposition device provided by the present invention has a simple structure and is easy to scale up.

[0038] Example 2 This embodiment provides an electrochemical lithium solution device, which differs from Embodiment 1 in that: in this embodiment, the ion membrane is an anion exchange membrane; the cathode electrolyte is a NaCl solution with a concentration of 0.1-0.5 mol / L.

[0039] The reaction equation in the anode cell 1 of this embodiment is as follows: LiFePO4+2H + →Li + +FePO4+H2↑ 2Cl⁻-2e⁻→Cl2↑ The reaction equation in the cathode pool 13 of this embodiment is as follows: 2H2O+2e⁻=H2↑+2OH⁻ When electrolysis begins, oxidation reaction occurs at the anode, and Fe 2+ Oxidized to Fe 3+ , which leads to Li + A reduction reaction occurs in the cathode pool 13, and active chlorine free radicals and active hydroxyl free radicals enter the anode pool 1 through the anion exchange membrane, and combine with the active chlorine free radicals generated in the anode pool 1, thereby accelerating the oxidation process of LFP.

[0040] Next, the electrochemical lithium dissolution device of the present invention is further described in conjunction with specific embodiments.

[0041] Experimental Example 1 The electrochemical lithium decomposition device of Example 1 is used to electrochemically decompose the recycled waste LFP battery positive electrode black powder into lithium, and the specific steps are as follows: Add 2g of recycled waste LFP battery positive electrode black powder to the anode pool 1, and then add 200ml of NaCl solution (concentration of 0.1mol / L), and keep the magnetic stirrer under the anode pool 1 in a stirring state at a stirring speed of 500r / min; add 200ml of NaCl solution (concentration of 0.1mol / L) to the cathode pool 13, and keep the magnetic stirrer under the cathode pool 13 in a stirring state at a stirring speed of 500r / min; (3) start peristaltic pump 14, peristaltic pump 2 15, peristaltic pump 3 16, peristaltic pump 4 17, connect the anode current collector plate 4 and the cathode current collector plate 10 to the positive and negative electrodes of a 3V constant voltage power supply respectively, discharge at room temperature, and the electrolysis time is 1 hour; after the electrolysis starts, add concentrated hydrochloric acid to the cathode pool 13 every 10 minutes, for a total of four times, adding 2ml each time; (4) After the reaction is completed, the mixture in the anode cell 1 is separated into solid and liquid, and filtered and sorted by vacuum filtration to obtain Li-containing + The filtrate and the solid ferric phosphate residue are dried in an oven at 70° C. for 5 h, and then ground and collected. At the same time, the liquid in the cathode pool 13 is collected.

[0042] In this embodiment, the metal ion content in the collected filtrate and the liquid in the cathode pool 13 was measured by inductively coupled plasma optical emission spectrometry (ICP-OES), and the lithium content was 99.11%, and the iron content was 0.43%. The lithium decomposition rate of this embodiment reached 99.11%.

[0043] Experimental Example 2 The electrochemical lithium decomposition device of Example 2 is used to electrochemically decompose the recycled waste LFP battery positive electrode black powder into lithium, and the specific steps are as follows: Add 2g of recycled waste LFP battery positive electrode black powder to the anode pool, and then add 200ml of NaCl solution (concentration of 0.5mol / L), and keep the magnetic stirrer under the anode pool 1 in a stirring state at a stirring speed of 300r / min; add 200ml of NaCl solution (concentration of 0.5mol / L) to the cathode pool, and keep the magnetic stirrer under the cathode pool in a stirring state at a stirring speed of 300r / min; (3) start peristaltic pump 14, peristaltic pump 2 15, peristaltic pump 3 16, peristaltic pump 4 17, connect the anode current collector plate 4 and the cathode current collector plate 10 to the positive and negative electrodes of a 3V constant voltage power supply, respectively, and discharge at room temperature for 1 hour; (4) After the reaction is completed, the mixture in the anode cell 1 is separated into solid and liquid, and filtered and sorted by vacuum filtration to obtain Li-containing + The filtrate and the solid iron phosphate residue were dried in an oven at 70°C for 5 hours and then ground and collected.

[0044] In this embodiment, the metal ion content in the collected filtrate was measured by inductively coupled plasma optical emission spectrometry (ICP-OES), and the lithium content was 99.99%, and the iron content was 0.087%. The lithium decomposition rate of this embodiment reached 99.99%.

[0045] Figure 4 This is the SEM image of the iron phosphate solid material obtained in this example. Figure 4 It can be seen that the crystal structure of iron phosphate is full and uniform.

[0046] Figure 5 The XRD pattern of the iron phosphate solid material obtained in this example is as follows: Figure 5 It can be seen that there is no difference between the iron phosphate and the standard iron phosphate card spectrum, indicating that the iron phosphate is not destroyed after the lithium iron phosphate is separated.

[0047] Experimental Example 3 The electrochemical lithium decomposition device of Example 1 is used to electrochemically decompose the recycled waste LFP battery positive electrode black powder into lithium, and the specific steps are as follows: Add 1g of recycled waste LFP battery positive electrode black powder to the anode pool 1, and then add 100ml of NaCl solution (concentration of 0.3mol / L), and keep the magnetic stirrer under the anode pool 1 in a stirring state at a stirring speed of 400r / min; add 100ml of NaCl solution (concentration of 0.3mol / L) to the cathode pool 13, and keep the magnetic stirrer under the cathode pool 13 in a stirring state at a stirring speed of 400r / min; (3) start peristaltic pump 14, peristaltic pump 2 15, peristaltic pump 3 16, peristaltic pump 4 17, connect the anode current collector plate 4 and the cathode current collector plate 10 to the positive and negative electrodes of a 3V constant voltage power supply, respectively, discharge at room temperature, and the electrolysis time is 1 hour; after the electrolysis starts, add concentrated hydrochloric acid to the cathode pool 13 every 10 minutes, for a total of four times, adding 1ml each time; (4) After the reaction is completed, the mixture in the anode cell 1 is separated into solid and liquid, and filtered and sorted by vacuum filtration to obtain Li-containing + The filtrate and the solid ferric phosphate residue are dried in an oven at 70° C. for 5 h, and then ground and collected. At the same time, the liquid in the cathode pool 13 is collected.

[0048] In this embodiment, the metal ion content in the collected filtrate and the liquid in the cathode pool 13 was measured using an inductively coupled plasma optical emission spectrometer (ICP-OES). The lithium content was 97.44%, and the iron content was 0.05%. The lithium decomposition rate of this embodiment reached 97.44%.

[0049] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0050] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. An electrochemical lithium decomposition device, characterized in that: It includes an anode unit, a cathode unit, an ion membrane, an anode pool, a cathode pool, a circulation part 1, a circulation part 2 and a power supply; the anode unit and the cathode unit are respectively sealed and arranged on both sides of the ion membrane, and the anode unit and the cathode unit are respectively provided with an anode channel and a cathode channel on the side facing the ion membrane; a mixture of an anode electrolyte and anode black powder of a waste LFP battery is arranged in the anode pool, and the circulation part 1 is used to realize the circulation of the mixture between the anode pool and the anode channel; The cathode cell is provided with cathode electrolyte, and the circulation part 2 is used to realize the circulation of the cathode electrolyte between the cathode cell and the cathode channel; The power supply is electrically connected to the anode unit and the cathode unit.

2. The electrochemical lithium dissolution device according to claim 1, characterized in that: The anode unit comprises an anode insulating end plate, an anode current collector plate and an anode electrolytic cell which are arranged in sequence; an inlet 1 and an outlet 1 are provided on the anode insulating end plate; an inlet 2 and an outlet 2 are provided on the anode current collector plate and the inlet 2 and the outlet 2 are connected with the inlet 1 and the outlet 1 respectively; an anode channel is provided on the side of the anode electrolytic cell facing the ion membrane and the anode channel is connected with the inlet 2 and the outlet 2; a seal 1 is provided between the anode electrolytic cell and the ion membrane, and the seal 1 is opened in the area corresponding to the anode channel.

3. The electrochemical lithium dissolution device according to claim 2, characterized in that: The anode current collector plate is a ruthenium-plated titanium plate; and / or, an anode insulating sheet is arranged between the anode current collector plate and the anode insulating end plate, and an inlet three and an outlet three are opened on the anode insulating sheet, and the two ends of the inlet three are respectively connected to the inlet one and the inlet two, and the two ends of the outlet three are respectively connected to the outlet one and the outlet two.

4. The electrochemical lithium dissolution device according to claim 1, characterized in that: The cathode unit includes a cathode insulating end plate, a cathode current collector plate and a cathode electrolytic cell which are arranged in sequence; an inlet four and an outlet four are opened on the cathode insulating end plate; an inlet five and an outlet five are opened on the cathode current collector plate and the inlet five and the outlet five are connected with the inlet four and the outlet four respectively; a cathode channel is opened on the side of the cathode electrolytic cell facing the ion membrane and the cathode channel is connected with the inlet five and the outlet five, a seal two is arranged between the cathode electrolytic cell and the ion membrane, and the seal two is opened in the area corresponding to the cathode channel.

5. The electrochemical lithium dissolution device according to claim 4, characterized in that: The cathode current collector plate is a ruthenium-plated titanium plate; and / or a cathode insulating sheet is arranged between the cathode current collector plate and the cathode insulating end plate, and an inlet six and an outlet six are opened on the cathode insulating sheet, the two ends of the inlet six are connected to the inlet four and the inlet five respectively, and the two ends of the outlet six are connected to the outlet four and the outlet five respectively.

6. The electrochemical lithium dissolution device according to claim 1, characterized in that: The anode channel and the cathode channel are both distributed in a serpentine shape; and / or, the ion membrane is a cation exchange membrane or an anion exchange membrane.

7. The electrochemical lithium dissolution device according to claim 1, characterized in that: The anolyte is a NaCl solution with a concentration of 0.1-0.5 mol / L; and / or the catholyte is a NaCl solution or a NaCl solution and concentrated hydrochloric acid, wherein the concentration of the NaCl solution is 0.1-0.5 mol / L, and the volume ratio of the concentrated hydrochloric acid to the NaCl solution is 4%.

8. The electrochemical lithium dissolution device according to claim 1, characterized in that: The circulation part 1 includes two peristaltic pumps 1 and 2, the inlet of the peristaltic pump 1 is connected to the anode pool through a pipeline and the outlet thereof is connected to the anode channel through a pipeline, the inlet of the peristaltic pump 2 is connected to the anode channel through a pipeline and the outlet thereof is connected to the anode pool through a pipeline; And / or, the circulation component 2 includes a peristaltic pump 3 and a peristaltic pump 4, the inlet of the peristaltic pump 3 is connected to the cathode pool through a pipeline and the outlet thereof is connected to the cathode channel through a pipeline, the inlet of the peristaltic pump 4 is connected to the cathode channel through a pipeline and the outlet thereof is connected to the cathode pool through a pipeline.

9. A method for electrochemical lithium decomposition of waste LFP battery positive electrode black powder, characterized in that: The electrochemical lithium dissolution device according to any one of claims 1 to 8 is used, which comprises the following steps: S1. Add the recycled waste LFP battery positive electrode black powder to the anode tank, and then add the anolyte to the anode tank; S2. adding catholyte to the cathode cell; S3. Start cycle one and cycle two, and simultaneously connect the anode unit and cathode unit to a power source for electrolysis; S4. After the electrolysis is completed, the mixture in the anode tank is separated into solid and liquid to obtain Li + The filtrate and residue FePO4.

10. The method for electrochemical lithium decomposition of waste LFP battery positive electrode black powder according to claim 9, characterized in that: In step S1, the mass volume ratio of the waste LFP battery positive electrode black powder and the anolyte is 10-30 g:1 L, and the anolyte is a NaCl solution with a concentration of 0.1-0.5 mol / L; And / or, in step S2, the cathode electrolyte is a NaCl solution or a NaCl solution and concentrated hydrochloric acid, wherein the concentration of the NaCl solution is 0.1-0.5 mol / L, and the volume ratio of the concentrated hydrochloric acid to the NaCl solution is 4%; And / or, in step S3, the power supply of the power supply is 1-4V.

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