A device and method for electrochemically recycling lithium and regenerating acid from waste lithium iron phosphate-based lithium-ion batteries

Abstract

This invention provides an electrochemical cascade recovery device and method for lithium and acid regeneration from waste lithium iron phosphate (LFP) based lithium-ion batteries. The device includes: a base; a turntable rotatably connected to the top of the base, with a first gear fixedly connected to the outer surface of the turntable; an electrolytic cell and a concentration cell mounted on the top of the turntable; a filter assembly mounted at the bottom of the electrolytic cell for solid-liquid separation of materials after reaction within the electrolytic cell; and a mounting frame mounted on one side of the base, with a driving component mounted on the frame. The device and method for electrochemical cascade recovery of lithium and acid from waste LFP based lithium-ion batteries provided by this invention integrate multiple functions and can achieve multiple state changes through the cooperation of an automatic push rod and a driving component, improving ease of use and facilitating continuous production.

Description

Technical Field

[0001] This invention relates to the field of waste lithium battery extraction, and more particularly to an electrochemical cascade recovery device and method for lithium and acid regeneration from waste lithium iron phosphate-based lithium-ion batteries. Background Technology

[0002] With the widespread adoption of electric vehicles, the demand for lithium-ion batteries has increased dramatically. Lithium iron phosphate (LiFePO4) has become the preferred cathode material for lithium-ion batteries in electric vehicles due to its low cost, high safety, and long cycle life. However, with the large-scale use of LiFePO4-based lithium-ion batteries, the recycling of used batteries has become an increasingly prominent issue.

[0003] Currently, the main methods for recovering lithium from spent lithium batteries include pyrometallurgy and hydrometallurgy. Pyrometallurgy is energy-intensive and has a very low lithium recovery rate. Hydrometallurgy involves a series of steps, each consuming a significant amount of chemical reagents and generating substantial waste. For lithium iron phosphate materials that contain only lithium, the economic value of recycling is limited.

[0004] In recent years, some studies have attempted to recover lithium using electrochemical methods. However, current electrochemical technologies are still in the laboratory stage and have not yet been industrialized. Furthermore, the comprehensive recovery of lithium from waste lithium batteries currently on the market involves a large number of processing devices, including reaction devices and electrolysis devices. This not only increases costs but also requires a larger floor space. Moreover, the devices cannot be used in conjunction with each other, which delays processing time and makes it impossible to guarantee the continuous operation of the process.

[0005] Therefore, it is necessary to provide an electrochemical cascade recovery device and method for lithium and acid regeneration from waste lithium iron phosphate-based lithium-ion batteries to solve the above-mentioned technical problems. Summary of the Invention

[0006] This invention provides an electrochemical cascade recovery device and method for lithium and acid regeneration from waste lithium iron phosphate-based lithium-ion batteries. It solves the problems that having more equipment not only increases costs but also requires a larger footprint, and the devices cannot be used in conjunction, which delays processing time and makes it impossible to ensure continuous processing.

[0007] To solve the above-mentioned technical problems, the electrochemical cascade recycling device for lithium and acid regeneration of waste lithium iron phosphate-based lithium-ion batteries provided by the present invention includes: a base;

[0008] A turntable is rotatably connected to the top of the base. A first gear is fixedly connected to the outer surface of the turntable. An electrolytic cell and a concentration cell are installed on the top of the turntable. A filter assembly is installed at the bottom of the electrolytic cell. The filter assembly is used for solid-liquid separation after the material inside the electrolytic cell has reacted.

[0009] Mounting bracket, which is mounted on one side of the base, has a driving component mounted on it. The output shaft of the driving component is fixedly connected to a rotating rod, an auxiliary rod is fixedly connected to the rotating rod, and an arc-shaped toothed plate is fixedly connected to the auxiliary rod.

[0010] A connecting frame is rotatably connected to a rotating rod, a sliding plate is slidably connected to the connecting frame, a locking structure is provided between the sliding plate and the rotating rod, and an electrolysis assembly is installed on the sliding plate;

[0011] A pushing component is mounted on the connecting frame. After the material reaction inside the electrolytic cell is completed, the pushing component is used to move linearly to open the filter component.

[0012] An automatic push rod is mounted on the connecting frame and is fixedly connected to the sliding plate;

[0013] A cleaning assembly is mounted on the mounting bracket and is used for cleaning the electrolysis assembly after use.

[0014] A positioning pin is installed on the electrolysis component, and a positioning sleeve adapted to the positioning pin is installed on the cleaning component.

[0015] During cleaning, the positioning pin is inserted into the positioning sleeve to fix the electrolysis component and the cleaning component.

[0016] Preferably, the filter assembly includes a housing, a filter plate, a discharge trough, a groove, a sealing plate, a through hole, and a first elastic element. The housing is mounted on the turntable, the filter plate is detachably connected to the interior of the housing, the discharge trough is installed between the electrolytic cell and the housing, the groove is formed on one side of the inner wall of the discharge trough, the sealing plate is slidably connected to the interior of the groove, one side of the sealing plate penetrates the discharge trough and extends to the left side of the discharge trough, the through hole is formed on the sealing plate and is located outside the discharge trough, and the first elastic element is installed between the sealing plate and the side wall of the groove.

[0017] Preferably, the locking structure includes a vertical rod, a U-shaped clamp, and a locking block. The top end of the vertical rod is fixedly connected to the sliding plate, and the bottom end of the vertical rod passes through the connecting frame and extends to the bottom of the connecting frame. The U-shaped clamp is fixedly connected to the bottom end of the vertical rod, and the locking block is fixedly connected to the outer surface of the rotating rod. When the U-shaped clamp is clamped outside the locking block, the connecting frame and the rotating rod are locked to achieve relative stillness.

[0018] Preferably, the electrolysis assembly includes a support frame, a power supply device, and two electrode plates. The support frame is mounted on the sliding plate, the power supply device is mounted on the support frame, and both electrode plates are mounted on the support frame. The power supply device is electrically connected to the electrode plates, and the two electrode plates are lithium titanium phosphate electrode and bismuth electrode, respectively.

[0019] Preferably, the pushing assembly includes a cylinder, a first sealing piston, a first pushing rod, a second sealing piston, and a second pushing rod. The cylinder is mounted on the connecting frame. The first sealing piston is slidably connected to the inside of the cylinder. The first pushing rod is fixedly connected to the first sealing piston. The second sealing piston is slidably connected to the inside of the cylinder. The second pushing rod is fixedly connected to the second sealing piston. The second pushing rod is located on the left side of the sealing plate.

[0020] Preferably, the cleaning assembly includes a cleaning tank, a sliding rod, a sliding sleeve, a cleaning frame, a second elastic element, a transmission structure, a water supply pipe, and a drain pipe. The cleaning tank is fixedly connected to the mounting frame, the sliding rod is fixedly connected to the inside of the cleaning tank, the sliding sleeve is slidably connected to the outer surface of the sliding rod, the cleaning frame is installed on the sliding sleeve, the second elastic element is sleeved on the sliding rod, and the water supply pipe and drain pipe are both connected through the cleaning tank. The water supply pipe is connected to the cleaning frame.

[0021] Preferably, the transmission structure includes a mounting shaft, a second gear, a third gear, and a spur gear plate. The mounting shaft is connected through the cleaning tank. The second gear and the third gear are both fixedly connected to the mounting shaft. The spur gear plate is fixedly connected to the sliding sleeve. The third gear meshes with the spur gear plate.

[0022] This invention also provides a method for electrochemical cascade recovery of lithium and acid regeneration from spent lithium iron phosphate-based lithium-ion batteries, based on the aforementioned electrochemical cascade recovery of lithium and acid regeneration device for spent lithium iron phosphate-based lithium-ion batteries, comprising the following steps:

[0023] S1. Lithium iron phosphate powder is placed in an electrolytic cell containing phosphoric acid and hydrogen peroxide, the pH is adjusted, chemical leaching is carried out, and then filtered through a filter assembly to obtain insoluble FePO4 and lithium dihydrogen phosphate solution.

[0024] S2. Preparation of orthorhombic NASICON-type lithium titanium phosphate electrode and bismuth electrode;

[0025] S3. Pour the lithium dihydrogen phosphate solution obtained in S1 back into the electrolytic cell, equip it with an orthorhombic NASICON-type lithium titanium phosphate electrode and a bismuth electrode as the cathode and anode respectively, connect the power supply, and enter the electrolytic cell to selectively extract Li. + and PO4 3- , obtain storage Li+ Lithium titanium phosphate electrode and PO4 storage 3- Bismuth electrode;

[0026] S4, store Li + Lithium titanium phosphate electrode and PO4 storage 3- The bismuth electrode was removed, rinsed with deionized water using a cleaning assembly, and transferred to a concentration tank containing lithium chloride solution for storage. + Lithium titanium phosphate electrode and PO4 storage 3- Bismuth electrodes, serving as the anode and cathode respectively, are connected to a power supply and introduced into a concentration tank to release Li. + and PO4 3- To obtain Li + PO4 3- Cl - Solution;

[0027] S5, containing Li + PO4 3- Cl - The solution was concentrated and the pH was adjusted to obtain lithium phosphate precipitate.

[0028] Preferably, the preparation of the orthorhombic NASICON-type lithium titanium phosphate electrode in step S2 includes the following steps:

[0029] S21. Tetrabutyl titanate, ethanol, and lithium acetate are mixed and stirred to obtain a mixed solution;

[0030] S22. Add phosphoric acid and carbon to the mixed solution, stir, and dry to obtain a solid powder;

[0031] S23. Heating the solid powder at a certain temperature yields lithium titanium phosphate composite powder;

[0032] S24. Mix and grind lithium titanium phosphate composite powder and conductive carbon black to obtain a mixture;

[0033] S25. Mix the mixture, polytetrafluoroethylene, and water to obtain a slurry;

[0034] S26. Knead, roll, press, dry, and slice the slurry to obtain an orthorhombic NASICON type lithium titanium phosphate electrode.

[0035] Preferably, the preparation of the bismuth electrode in step S2 includes the following steps:

[0036] S27. Mix bismuth trioxide and graphite powder, grind, and ball mill to obtain a mixture;

[0037] S28. Mix the mixture, polytetrafluoroethylene, and water to obtain a slurry;

[0038] S29. Knead, roll, press, dry, and slice the slurry to obtain a bismuth electrode.

[0039] Compared with related technologies, the electrochemical cascade recovery device and method for lithium and acid regeneration from waste lithium iron phosphate-based lithium-ion batteries provided by this invention have the following beneficial effects:

[0040] This invention provides an electrochemical cascade recovery device and method for lithium and acid regeneration from waste lithium iron phosphate-based lithium-ion batteries. The device utilizes an automatic pusher to retract, which controls the opening of a filter assembly for filtration. The extension of the pusher transitions the device from a filtration state to an electrolysis state. The rotation of the drive assembly moves the electrolysis assembly above the cleaning assembly for easier cleaning. During this transfer, an arc-shaped toothed plate rotates the turntable half a revolution, swapping the positions of the electrolytic cell and the concentration cell, preparing for subsequent operations and improving ease of use. The extension of the automatic pusher allows the electrolysis assembly to enter the cleaning assembly for cleaning, and the engagement of the arc-shaped toothed plate with the transmission structure enables the cleaning frame to thoroughly clean the electrolysis assembly. This multi-functional device allows for multiple state transitions through the coordination of the automatic pusher and drive assembly, enhancing usability and facilitating continuous production. Attached Figure Description

[0041] Figure 1 A schematic diagram of the structure of the first embodiment of the electrochemical cascade recovery of lithium and acid regeneration device and method for waste lithium iron phosphate-based lithium-ion batteries provided by the present invention;

[0042] Figure 2 for Figure 1 The bottom view of the locking structure shown;

[0043] Figure 3 for Figure 1 A cross-sectional schematic diagram of the filter assembly shown;

[0044] Figure 4 for Figure 3 The enlarged schematic diagram of part A shown below;

[0045] Figure 5 for Figure 1 A cross-sectional schematic diagram of the cleaning assembly shown;

[0046] Figure 6 for Figure 5 The enlarged schematic diagram of section B is shown below;

[0047] Figure 7 An initial state diagram of the electrochemical cascade recovery and acid regeneration device for waste lithium iron phosphate-based lithium-ion batteries provided by the present invention;

[0048] Figure 8This is a motion diagram of the automatic push rod, where, Figure 8 (a) is a schematic diagram of the state after the automatic push rod has retracted. Figure 8 (b) is a schematic diagram of the automatic push rod after it has been extended;

[0049] Figure 9 This is a motion state diagram of the driving component, where, Figure 9 (a) is a schematic diagram of the state after the driving component has rotated half a revolution. Figure 9 (b) is a state diagram showing the interaction between the drive unit and the automatic push rod unit;

[0050] Figure 10 This is a schematic flowchart of a second embodiment of the electrochemical cascade recovery of lithium and acid from waste lithium iron phosphate-based lithium-ion batteries and the regeneration device and method provided by the present invention.

[0051] Numbering on the map:

[0052] 1. Base, 2. Turntable, 3. First gear, 4. Electrolytic cell, 5. Concentration cell;

[0053] 6. Filter assembly; 61. Housing; 62. Filter plate; 63. Discharge chute; 64. Groove; 65. Sealing plate; 66. Through hole; 67. First elastic element.

[0054] 7. Mounting bracket; 8. Driving component; 9. Rotating rod; 10. Auxiliary rod; 11. Arc-shaped toothed plate; 12. Connecting bracket; 13. Sliding plate;

[0055] 14. Locking structure; 141. Vertical rod; 142. U-shaped clamp; 143. Snap-fit ​​block;

[0056] 15. Electrolysis assembly; 151. Support frame; 152. Power supply unit; 153. Electrode plate;

[0057] 16. Pushing assembly; 161. Cylinder; 162. First sealing piston; 163. First push rod; 164. Second sealing piston; 165. Second push rod;

[0058] 17. Automatic push rod mechanism;

[0059] 18. Cleaning assembly; 181. Cleaning tank; 182. Slide rod; 183. Slide sleeve; 184. Cleaning frame; 185. Second elastic element; 186. Transmission structure; 1861. Mounting shaft; 1862. Second gear; 1863. Third gear; 1864. Straight gear plate; 187. Water supply pipe; 188. Drain pipe.

[0060] 19. Positioning pin; 20. Positioning sleeve. Detailed Implementation

[0061] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0062] First Embodiment

[0063] Please refer to the following: Figures 1-9 ,in, Figure 1 A schematic diagram of the structure of the first embodiment of the electrochemical cascade recovery of lithium and acid regeneration device and method for waste lithium iron phosphate-based lithium-ion batteries provided by the present invention; Figure 2 for Figure 1 The bottom view of the locking structure shown; Figure 3 for Figure 1 A cross-sectional schematic diagram of the filter assembly shown; Figure 4 for Figure 3 The enlarged schematic diagram of part A shown below; Figure 5 for Figure 1 A cross-sectional schematic diagram of the cleaning assembly shown; Figure 6 for Figure 5 The enlarged schematic diagram of section B is shown below; Figure 7 An initial state diagram of the electrochemical cascade recovery and acid regeneration device for waste lithium iron phosphate-based lithium-ion batteries provided by the present invention; Figure 8 This is a motion diagram of the automatic push rod, where, Figure 8 (a) is a schematic diagram of the state after the automatic push rod has retracted. Figure 8 (b) is a schematic diagram of the automatic push rod after it has been extended; Figure 9 This is a motion state diagram of the driving component, where, Figure 9 (a) is a schematic diagram of the state after the driving component has rotated half a revolution. Figure 9 (b) is a state diagram showing the interaction between the drive unit and the automatic push rod unit.

[0064] This invention provides an electrochemical cascade recycling device for lithium and acid regeneration from waste lithium iron phosphate-based lithium-ion batteries, comprising: a base 1;

[0065] Turntable 2 is rotatably connected to the top of the base 1. A first gear 3 is fixedly connected to the outer surface of the turntable 2. An electrolytic cell 4 and a concentration cell 5 are installed on the top of the turntable 2. A filter assembly 6 is installed at the bottom of the electrolytic cell 4. The filter assembly 6 is used for solid-liquid separation after the material inside the electrolytic cell 4 has reacted.

[0066] Mounting bracket 7 is mounted on one side of the base 1. A driving component 8 is mounted on the mounting bracket 7. A rotating rod 9 is fixedly connected to the output shaft of the driving component 8. An auxiliary rod 10 is fixedly connected to the rotating rod 9. An arc-shaped toothed plate 11 is fixedly connected to the auxiliary rod 10.

[0067] A connecting frame 12 is rotatably connected to a rotating rod 9. A sliding plate 13 is slidably connected to the connecting frame 12. A locking structure 14 is provided between the sliding plate 13 and the rotating rod 9. An electrolysis assembly 15 is installed on the sliding plate 13.

[0068] A pushing component 16 is mounted on the connecting frame 12. After the material reaction inside the electrolytic cell 4 is completed, the pushing component 16 is used to move linearly to open the filter component 6.

[0069] Automatic push rod 17 is mounted on the connecting frame 12 and is fixedly connected to the sliding plate 13;

[0070] A cleaning assembly 18 is mounted on the mounting bracket 7 and is used for cleaning the electrolysis assembly 15 after use.

[0071] Positioning pin 19 is installed on the electrolysis component 15, and a positioning sleeve 20 adapted to the positioning pin 19 is installed on the cleaning component 18.

[0072] During cleaning, the positioning pin 19 is inserted into the positioning sleeve 20 to fix the electrolysis component 15 and the cleaning component 18.

[0073] In this embodiment, the driving component 8 includes, but is not limited to, a servo motor, an engine, a hydraulic motor, etc., as long as it can provide a driving force for the rotation of the rotating rod 9.

[0074] In this embodiment, the automatic push rod 17 includes, but is not limited to, electric telescopic rods, cylinders, hydraulic cylinders, linear motors, etc., as long as it can drive the sliding plate 13 to move linearly in the vertical direction.

[0075] Please refer to the following: Figure 1 The arc-shaped toothed plate 11 is in mesh with the first gear 3. After the arc-shaped toothed plate 11 has finished rolling on the first gear 3, it will drive the first gear 3 to rotate half a turn.

[0076] In this embodiment, both the electrolytic cell 4 and the concentration cell 5 adopt existing mature technologies and should include all other structures that realize their related functions, which will not be described in detail here.

[0077] In one embodiment, positioning sleeves 20 are also provided on the front and rear sides of the electrolytic cell 4 and the concentration cell 5, which can cooperate with and fix the electrolytic component 15 when it moves down, thereby improving the stability of the turntable 2.

[0078] Please refer to the following: Figure 3The filter assembly 6 includes a housing 61, a filter plate 62, a discharge trough 63, a groove 64, a sealing plate 65, a through hole 66, and a first elastic element 67. The housing 61 is mounted on the turntable 2. The filter plate 62 is detachably connected to the interior of the housing 61. The discharge trough 63 is installed between the electrolytic cell 4 and the housing 61. The groove 64 is formed on one side of the inner wall of the discharge trough 63. The sealing plate 65 is slidably connected to the interior of the groove 64. One side of the sealing plate 65 penetrates the discharge trough 63 and extends to the left side of the discharge trough 63. The through hole 66 is formed on the sealing plate 65 and is located outside the discharge trough 63. The first elastic element 67 is installed between the sealing plate 65 and the side wall of the groove 64.

[0079] In this embodiment, the first elastic element 67 includes, but is not limited to, springs, elastic strips, or arc-shaped spring sheets, etc., as long as it can provide elastic force to the sealing plate 65;

[0080] In this embodiment, the front of the housing 61 is also provided with a door that can be opened, for discharging the filter residue generated by the filter plate 62, and for disassembling and replacing the filter plate 62.

[0081] Preferably, the back of the housing 61 is also provided with a filtrate outlet, and the filtrate outlet can be connected to a suction pump device and a conduit to the electrolytic cell 4 to facilitate the transfer of filtrate to the electrolytic cell 4;

[0082] Please refer to it again. Figure 3 When the sealing plate 65 is pushed to move to the right, it will squeeze the first elastic element 67, and the through hole 66 will move to the right and enter the discharge trough 63. When the through hole 66 is connected to the flow channel of the discharge trough 63, the material inside the electrolytic cell 4 will be discharged from the discharge trough 63 to the filter plate 62 for solid-liquid separation.

[0083] Similarly, when the force pushing the sealing plate 65 is removed, the first elastic element 67 will spring back to its original position, causing the sealing plate 65 to move to the left and drive the through hole 66 out of the discharge trough 63, thereby sealing the discharge trough 63 with the sealing plate 65.

[0084] Please refer to the following: Figure 2 The locking structure 14 includes a vertical rod 141, a U-shaped clamping block 142, and a locking block 143. The top end of the vertical rod 141 is fixedly connected to the sliding plate 13, and the bottom end of the vertical rod 141 passes through the connecting frame 12 and extends to the bottom of the connecting frame 12. The U-shaped clamping block 142 is fixedly connected to the bottom end of the vertical rod 141, and the locking block 143 is fixedly connected to the outer surface of the rotating rod 9. When the U-shaped clamping block 142 is clamped outside the locking block 143, the connecting frame 12 and the rotating rod 9 are locked to achieve relative stillness.

[0085] Preferably, the internal groove of the U-shaped clamping block 142 is rectangular, the shape of the snap-fit ​​block 143 is rectangular, and the U-shaped clamping block 142 and the snap-fit ​​block 143 are adapted to each other.

[0086] Please refer to it again. Figure 2 When the automatic push rod 17 is in the initial position, the U-shaped clamp 142 is locked outside the clamping block 143, which can restrict the rotation of the clamping block 143, thereby ensuring the limiting and fixing between the connecting frame 12 and the rotating rod 9. When the driving member 8 drives the rotating rod 9 to rotate, it can drive the connecting frame 12 to rotate, thereby driving the electrolysis component 15 to be switched to the position of the cleaning component 18.

[0087] Please refer to the following: Figure 9 (b) When the automatic push rod 17 is in the extended position, the sliding plate 13 moves downward, which will drive the electrolysis component 15 to move downward into the cleaning component 18. At this time, the positioning pin 19 and the positioning sleeve 20 are inserted to fix the electrolysis component 15 and the cleaning component 18, thereby indirectly fixing the cleaning component and the connecting frame 12. After the sliding plate 13 moves downward, it will drive the vertical rod 141 to move downward, thereby separating the U-shaped clamp 142 from the snap-fit ​​block 143. At this time, the rotating rod 9 is unrestricted and can be driven to rotate independently by the driving component 8, thereby indirectly driving the arc-shaped toothed plate 11 to drive the cleaning component to move for comprehensive cleaning.

[0088] Please refer to the following: Figure 2 The electrolysis assembly 15 includes a support frame 151, a power supply device 152, and two electrode plates 153. The support frame 151 is mounted on the sliding plate 13, the power supply device 152 is mounted on the support frame 151, and both electrode plates 153 are mounted on the support frame 151. The power supply device 152 is electrically connected to the electrode plates 153, and the two electrode plates 153 are lithium titanium phosphate electrode and bismuth electrode, respectively.

[0089] In this embodiment, the support frame 151 is used to support the power supply device 152 and the electrode plate 153. The power supply device 152 is an existing storage battery and an external battery technology, which will not be described in detail here.

[0090] Please refer to it again. Figure 3The pushing assembly 16 includes a cylinder 161, a first sealing piston 162, a first pushing rod 163, a second sealing piston 164, and a second pushing rod 165. The cylinder 161 is mounted on the connecting frame 12. The first sealing piston 162 is slidably connected to the inside of the cylinder 161. The first pushing rod 163 is fixedly connected to the first sealing piston 162. The second sealing piston 164 is slidably connected to the inside of the cylinder 161. The second pushing rod 165 is fixedly connected to the second sealing piston 164. The second pushing rod 165 is located on the left side of the sealing plate 65.

[0091] In this embodiment, both the first sealing piston 162 and the second sealing piston 164 have sufficient sealing performance to ensure the internal sealing of the cylinder 161.

[0092] In use, when the automatic push rod 17 retracts, it causes the sliding plate 13 to move upward, thereby contacting the first push rod 163 and causing the first push rod 163 to move upward, which in turn causes the first sealing piston 162 to move upward. This causes the second sealing piston 164 to move to the right through air pressure, which in turn causes the second push rod 165 to move to the right, thereby pushing the sealing plate 65 to control the opening and closing of the discharge chute 63.

[0093] Preferably, the air pressure inside the cylinder 161 is much greater than the elastic force of the first elastic element 67.

[0094] Please refer to the following: Figure 5 and Figure 6 The cleaning assembly 18 includes a cleaning tank 181, a sliding rod 182, a sliding sleeve 183, a cleaning frame 184, a second elastic element 185, a transmission structure 186, a water supply pipe 187, and a drain pipe 188. The cleaning tank 181 is fixedly connected to the mounting bracket 7. The sliding rod 182 is fixedly connected to the inside of the cleaning tank 181. The sliding sleeve 183 is slidably connected to the outer surface of the sliding rod 182. The cleaning frame 184 is mounted on the sliding sleeve 183. The second elastic element 185 is sleeved on the sliding rod 182. The water supply pipe 187 and the drain pipe 188 are both connected through the cleaning tank 181. The water supply pipe 187 is connected to the cleaning frame 184.

[0095] Water supply pipe 187 is used to supply water to the cleaning rack 184, and drain pipe 188 is used to drain the water after cleaning.

[0096] In this embodiment, the second elastic element 185 includes, but is not limited to, springs, elastic strips, or arc-shaped spring sheets, etc., as long as it can provide elastic force to the sliding sleeve 183.

[0097] In this embodiment, the water supply pipe 187 is connected to the external suction pump and the water source through a conduit.

[0098] Please refer to the following: Figure 5 The cleaning rack 184 is mountain-shaped and has multiple spray holes. The two electrode plates 153 can move to two sections of the cleaning rack 184 to achieve comprehensive cleaning of the two electrode plates 153.

[0099] In use, the two electrode plates 153 move to the two sections of the cleaning rack 184, and the power of the drive component 8 is transmitted through the transmission structure 186, which drives the sliding sleeve 183 to reciprocate, and in turn drives the cleaning rack 184 to reciprocate to clean the electrode plates 153 back and forth.

[0100] In this embodiment, the second elastic element 185 facilitates the springback reset of the cleaning rack 184 when it moves to the right.

[0101] Please refer to it again. Figure 5 and Figure 6 The transmission structure 186 includes a mounting shaft 1861, a second gear 1862, a third gear 1863, and a spur gear plate 1864. The mounting shaft 1861 is connected through the cleaning tank 181. The second gear 1862 and the third gear 1863 are both fixedly connected to the mounting shaft 1861. The spur gear plate 1864 is fixedly connected to the sliding sleeve 183. The third gear 1863 meshes with the spur gear plate 1864.

[0102] In this embodiment, a sealing element is provided at the point where the mounting shaft 1861 passes through the cleaning groove 181 to meet the sealing requirements.

[0103] In use, when the arc-shaped toothed plate 11 meshes with the second gear 1862, the drive component 8 rotates by a preset angle, which can control the arc-shaped toothed plate 11 to move by a preset angle, so that it can roll on the surface of the second gear 1862. When the arc-shaped toothed plate 11 swings back and forth, it will drive the second gear 1862 to rotate back and forth, which in turn causes the mounting shaft 1861 to rotate back and forth, indirectly driving the third gear 1863 to rotate back and forth, which can drive the straight toothed plate 1864 to reciprocate.

[0104] The working principle of the electrochemical cascade recovery device and method for lithium and acid regeneration from spent lithium iron phosphate-based lithium-ion batteries provided by this invention is as follows:

[0105] Please refer to the following: Figure 8 (a) Lithium iron phosphate powder is placed in an electrolytic cell 4 containing phosphoric acid and hydrogen peroxide for chemical leaching. Then, the automatic push rod 17 retracts, causing the push assembly 16 to push the sealing plate 65 to move, thereby opening the filter assembly 6 for filtration to obtain insoluble FePO4 and lithium dihydrogen phosphate solution.

[0106] Please refer to the following: Figure 8 (b) The lithium dihydrogen phosphate solution is poured back into the electrolytic cell 4. The extension of the automatic push rod 17 causes the sliding plate 13 to move downwards, thereby moving the support frame 151 downwards. This allows the two electrode plates 153 to enter the electrolytic cell 4 for electrolysis, selectively extracting Li. + and PO4 3- , obtain storage Li + Lithium titanium phosphate electrode and PO4 storage 3- After the bismuth electrode is electrolyzed, the automatic push rod 17 resets, causing the electrode plate 153 to move upward and then reset.

[0107] Please refer to the following: Figure 9 (a) By rotating the drive unit 8, the rotating rod 9 can rotate half a turn, thereby driving the connecting frame 12 to rotate half a turn, and then causing the electrolysis assembly 15 to move circumferentially above the cleaning tank 181. During this process, the auxiliary rod 10 will rotate with the rotating rod 9, thereby causing the arc-shaped toothed plate 11 to drive the first gear 3 to rotate half a turn, thereby causing the turntable 2 to rotate half a turn, driving the electrolysis tank 4 and the concentration tank 5 to exchange positions, and the arc-shaped toothed plate 11 will mesh with the transmission structure 186.

[0108] Please refer to the following: Figure 9 (b) The extension of the automatic push rod 17 will drive the sliding plate 13 to move downward, thereby moving the two electrode plates 153 into the cleaning tank 181 and fixing them by inserting the positioning pin 19 into the positioning sleeve 20. When the automatic push rod 17 extends, it will drive the locking component 14 to unlock. At this time, the drive component 8 will rotate at a preset angle and drive the transmission structure 186 to rotate through the arc toothed plate 11, thereby indirectly causing the cleaning rack 184 to reciprocate to thoroughly clean the electrode plates 153.

[0109] After cleaning, the automatic push rod 17 extends, causing the electrode plate 153 to reset. Then, the drive unit 8 rotates, causing the electrode plate 153 to move counterclockwise to the top of the concentration tank 5. The automatic push rod 17 then drives the electrode plate 153 into the concentration tank 5, releasing Li. + and PO4 3- To obtain Li + PO4 3- Cl - The solution, finally containing Li + PO4 3- Cl - The solution was concentrated to obtain lithium phosphate precipitate.

[0110] Compared with related technologies, the electrochemical cascade recovery device and method for lithium and acid regeneration from waste lithium iron phosphate-based lithium-ion batteries provided by this invention have the following beneficial effects:

[0111] This invention utilizes the retraction of the automatic push rod 17 to control the opening of the filter assembly 6 for filtration via the push component 16. The extension of the automatic push rod 17 then transitions the device from a filtration state to an electrolysis state. In conjunction with the rotation of the drive component 8, the electrolysis assembly 15 is moved above the cleaning assembly 18 for easy cleaning. During this transfer, the arc-shaped toothed plate 11 rotates the turntable 2 half a turn, thus swapping the positions of the electrolysis tank 4 and the concentration tank 5, preparing for subsequent work and improving ease of use. The extension of the automatic push rod 17 allows the electrolysis assembly 15 to enter the cleaning assembly 18 for cleaning, and the engagement of the arc-shaped toothed plate 11 with the transmission structure 186 enables the cleaning frame 184 to thoroughly clean the electrolysis assembly 15. This multi-functional device, through the cooperation of the automatic push rod 17 and the drive component 8, enables multiple state transitions, improving usability and facilitating continuous production.

[0112] Second Embodiment

[0113] This invention also provides a method for electrochemical cascade recovery of lithium and acid regeneration from spent lithium iron phosphate-based lithium-ion batteries, based on the aforementioned electrochemical cascade recovery of lithium and acid regeneration device for spent lithium iron phosphate-based lithium-ion batteries, comprising the following steps:

[0114] S1. Place 70g of lithium iron phosphate powder into an electrolytic cell 4 containing 0.5M phosphoric acid and 1M hydrogen peroxide, adjust the pH to 3.5, carry out chemical leaching, and then filter through the filter assembly 6 to obtain insoluble FePO4 and lithium dihydrogen phosphate solution.

[0115] This method is still applicable even if the lithium iron phosphate powder contains carbon and binders, and it does not affect the purity of the product; the phosphoric acid can also be replaced by other acids (such as sulfuric acid, nitric acid, etc.), and this method is still applicable.

[0116] S2. Preparation of orthorhombic NASICON-type lithium titanium phosphate electrode and bismuth electrode;

[0117] S3. Pour the lithium dihydrogen phosphate solution obtained in S1 back into electrolytic cell 4. Equip the cell with a 1cm×1cm orthorhombic NASICON-type lithium titanium phosphate electrode and a 1cm×1cm bismuth electrode as the cathode and anode, respectively. Connect the power supply and place the cell into electrolytic cell 4. Apply a current density of 105mA / g to selectively extract Li. + and PO4 3- , obtain storage Li + Lithium titanium phosphate electrode and PO4 storage 3- Bismuth electrode;

[0118] S4, store Li + Lithium titanium phosphate electrode and PO4 storage 3-The bismuth electrode was removed, rinsed with deionized water using cleaning assembly 18, and transferred to concentration tank 5 containing 1M lithium chloride solution for storage. + Lithium titanium phosphate electrode and PO4 storage 3- Bismuth electrodes, serving as anode and cathode respectively, are connected to a power supply and introduced into concentration tank 5. A current density of 200 mA / g is applied to release Li. + and PO4 3- To obtain Li + PO4 3- Cl - Solution;

[0119] S5, containing Li + PO4 3- Cl - The solution was concentrated and the pH was adjusted to obtain lithium phosphate precipitate.

[0120] In this embodiment, steps S4 and S5 involve recovering lithium in the form of lithium phosphate, but lithium can also be recovered in the form of lithium hydroxide or lithium carbonate, and the Li is stored. + Lithium titanium phosphate and platinum electrodes (for the hydrogen evolution reaction) serve as the anode and cathode, respectively. A cation exchange membrane divides the electrolyzer into an anode chamber and a cathode chamber. Li is released from the anode. + OH is generated at the cathode - The solution is concentrated and evaporated to obtain lithium hydroxide precipitate, or a concentrated lithium hydroxide solution is used to capture carbon dioxide on-site to obtain lithium carbonate, while PO4 is stored. 3- Bismuth and platinum electrodes (performing the oxygen evolution reaction) serve as the cathode and anode, respectively, with PO4 released at the cathode. 3- H is generated at the anode + The phosphoric acid is concentrated to obtain regenerated phosphoric acid, which can be used in the chemical leaching step of lithium iron phosphate powder; the carbon dioxide is Li. + The remaining solid after extraction is calcined under aerobic conditions, during which all carbonaceous substances are converted.

[0121] The preparation of the orthorhombic NASICON-type lithium titanium phosphate electrode in step S2 includes the following steps:

[0122] S21. Mix and stir 0.6M tetrabutyl titanate, 99.5% ethanol and 0.36M lithium acetate to obtain a mixed solution;

[0123] S22. Add 0.54M phosphoric acid and 0.5g carbon to the mixed solution, stir, and dry to obtain a solid powder;

[0124] S23. The solid powder was calcined at 750℃ for 7h under an argon atmosphere with a heating rate of 2.5℃ / min to obtain lithium titanium phosphate composite powder.

[0125] S24. Mix and grind lithium titanium phosphate composite powder and conductive carbon black at a mass ratio of 4:1 to obtain a mixture;

[0126] S25. Mix the mixture and polytetrafluoroethylene with water at a mass ratio of 3:1 to obtain a slurry;

[0127] S26. Knead, roll, press, dry, and slice the slurry to obtain an orthorhombic NASICON type lithium titanium phosphate electrode.

[0128] The preparation of the bismuth electrode in S2 includes the following steps:

[0129] S27. Mix bismuth trioxide and graphite powder at a mass ratio of 2.5:1, grind, and ball mill to obtain a mixture;

[0130] S28. Mix the mixture and polytetrafluoroethylene with water at a mass ratio of 1:6 to obtain a slurry;

[0131] S29. Knead, roll, press, dry, and slice the slurry to obtain a bismuth electrode.

[0132] Compared with related technologies, the electrochemical cascade recovery device and method for lithium and acid regeneration from waste lithium iron phosphate-based lithium-ion batteries provided by this invention have the following beneficial effects:

[0133] The electrochemical extraction process mainly involves Ti 4+ Restored to Ti 3+ To store Li + oxidize Bi to Bi 3+ To store PO4 3- The electrochemical recovery process mainly involves Ti 3+ Oxidation to Ti 4+ Release Li + Bi 3+ Reduced to Bi to release PO4 3- ;

[0134] The electrochemical recycling process does not require high-temperature treatment and has low energy consumption. The acid regeneration step reduces the consumption of chemical reagents and the generation of waste liquid. The orthorhombic NASICON-type lithium titanium phosphate electrode and bismuth electrode can be recycled.

[0135] This method offers more lithium recovery options, and the consumed acid can be regenerated through electrochemical reactions, thus achieving resource recycling.

[0136] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A device for electrochemical cascade recovery of lithium and acid from waste lithium iron phosphate-based lithium-ion batteries, characterized in that, include: Base; A turntable is rotatably connected to the top of the base. A first gear is fixedly connected to the outer surface of the turntable. An electrolytic cell and a concentration cell are installed on the top of the turntable. A filter assembly is installed at the bottom of the electrolytic cell. The filter assembly is used for solid-liquid separation of materials after reaction inside the electrolytic cell. The filter assembly includes a housing, a filter plate, a discharge trough, a groove, a sealing plate, a through hole, and a first elastic element. The housing is installed on the turntable. The filter plate is detachably connected to the inside of the housing. The discharge trough is installed between the electrolytic cell and the housing. The groove is opened on one side of the inner wall of the discharge trough. The sealing plate is slidably connected to the inside of the groove. One side of the sealing plate penetrates the discharge trough and extends to the left side of the discharge trough. The through hole is opened on the sealing plate and is located outside the discharge trough. The first elastic element is installed between the sealing plate and the side wall of the groove. Mounting bracket, which is mounted on one side of the base, has a driving component mounted on it. The output shaft of the driving component is fixedly connected to a rotating rod, an auxiliary rod is fixedly connected to the rotating rod, and an arc-shaped toothed plate is fixedly connected to the auxiliary rod. A connecting frame is rotatably connected to a rotating rod. A sliding plate is slidably connected to the connecting frame. A locking structure is provided between the sliding plate and the rotating rod. The locking structure includes a vertical rod, a U-shaped clamp, and a locking block. The top end of the vertical rod is fixedly connected to the sliding plate, and the bottom end of the vertical rod passes through the connecting frame and extends to the bottom of the connecting frame. The U-shaped clamp is fixedly connected to the bottom end of the vertical rod, and the locking block is fixedly connected to the outer surface of the rotating rod. When the U-shaped clamp is clamped outside the locking block, the connecting frame and the rotating rod are locked to achieve relative stillness. An electrolysis assembly is installed on the sliding plate. A pushing component is mounted on the connecting frame. After the material reaction inside the electrolytic cell is completed, the pushing component is used to move linearly to open the filter component. An automatic push rod is mounted on the connecting frame and is fixedly connected to the sliding plate; A cleaning assembly is mounted on the mounting bracket and is used for cleaning the electrolysis assembly after use. A positioning pin is installed on the electrolysis component, and a positioning sleeve adapted to the positioning pin is installed on the cleaning component. During cleaning, the positioning pin is inserted into the positioning sleeve to fix the electrolysis component and the cleaning component.

2. The electrochemical cascade recovery and acid regeneration device for spent lithium iron phosphate-based lithium-ion batteries according to claim 1, characterized in that, The electrolysis assembly includes a support frame, a power supply device, and two electrode plates. The support frame is mounted on the sliding plate, the power supply device is mounted on the support frame, and both electrode plates are mounted on the support frame. The power supply device is electrically connected to the electrode plates, and the two electrode plates are lithium titanium phosphate electrode and bismuth electrode, respectively.

3. The electrochemical cascade recovery and acid regeneration device for spent lithium iron phosphate-based lithium-ion batteries according to claim 1, characterized in that, The pushing assembly includes a cylinder, a first sealing piston, a first pushing rod, a second sealing piston, and a second pushing rod. The cylinder is mounted on the connecting frame. The first sealing piston is slidably connected to the inside of the cylinder. The first pushing rod is fixedly connected to the first sealing piston. The second sealing piston is slidably connected to the inside of the cylinder. The second pushing rod is fixedly connected to the second sealing piston. The second pushing rod is located on the left side of the sealing plate.

4. The electrochemical cascade recovery and acid regeneration device for spent lithium iron phosphate-based lithium-ion batteries according to claim 1, characterized in that, The cleaning assembly includes a cleaning tank, a sliding rod, a sliding sleeve, a cleaning frame, a second elastic element, a transmission structure, a water supply pipe, and a drain pipe. The cleaning tank is fixedly connected to the mounting frame, the sliding rod is fixedly connected to the inside of the cleaning tank, the sliding sleeve is slidably connected to the outer surface of the sliding rod, the cleaning frame is installed on the sliding sleeve, the second elastic element is sleeved on the sliding rod, and the water supply pipe and drain pipe are both connected through the cleaning tank. The water supply pipe is connected to the cleaning frame.

5. The electrochemical cascade recovery and acid regeneration device for spent lithium iron phosphate-based lithium-ion batteries according to claim 4, characterized in that, The transmission structure includes a mounting shaft, a second gear, a third gear, and a spur gear plate. The mounting shaft is connected through the cleaning tank. The second gear and the third gear are both fixedly connected to the mounting shaft. The spur gear plate is fixedly connected to the sliding sleeve. The third gear meshes with the spur gear plate.

6. A method for electrochemical cascade recovery of lithium and acid regeneration from spent lithium iron phosphate-based lithium-ion batteries, based on the electrochemical cascade recovery of lithium and acid regeneration device for spent lithium iron phosphate-based lithium-ion batteries as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Lithium iron phosphate powder is placed in an electrolytic cell containing phosphoric acid and hydrogen peroxide, the pH is adjusted, chemical leaching is carried out, and then filtered through a filter assembly to obtain insoluble FePO4 and lithium dihydrogen phosphate solution. S2. Preparation of orthorhombic NASICON-type lithium titanium phosphate electrode and bismuth electrode; S3, pour the lithium dihydrogen phosphate solution obtained in S1 back into the electrolytic cell, equip the NASICON-type lithium titanium phosphate electrode of orthorhombic system and the bismuth electrode as the cathode and the anode respectively, connect the power supply device into the electrolytic cell, and selectively extract Li + and PO4 3- , to obtain the lithium titanium phosphate electrode storing Li + and the bismuth electrode storing PO4 3- ; S4, store Li + Lithium titanium phosphate electrode and PO4 storage 3- The bismuth electrode was removed, rinsed with deionized water using a cleaning assembly, and transferred to a concentration tank containing lithium chloride solution for storage. + Lithium titanium phosphate electrode and PO4 storage 3- Bismuth electrodes, serving as the anode and cathode respectively, are connected to a power supply and introduced into a concentration tank to release Li. + and PO4 3- To obtain Li + PO4 3- Cl - Solution; S5, containing Li + PO4 3- Cl - The solution was concentrated and the pH was adjusted to obtain lithium phosphate precipitate.

7. The electrochemical cascade recovery method for lithium and acid regeneration from spent lithium iron phosphate-based lithium-ion batteries according to claim 6, characterized in that, The preparation of the orthorhombic NASICON-type lithium titanium phosphate electrode in step S2 includes the following steps: S21. Tetrabutyl titanate, ethanol, and lithium acetate are mixed and stirred to obtain a mixed solution; S22. Add phosphoric acid and carbon to the mixed solution, stir, and dry to obtain a solid powder; S23. Heating the solid powder at a certain temperature yields lithium titanium phosphate composite powder; S24. Mix and grind lithium titanium phosphate composite powder and conductive carbon black to obtain a mixture; S25. Mix the mixture, polytetrafluoroethylene, and water to obtain a slurry; S26. Knead, roll, press, dry, and slice the slurry to obtain an orthorhombic NASICON type lithium titanium phosphate electrode.

8. The electrochemical cascade recovery method for lithium and acid regeneration from spent lithium iron phosphate-based lithium-ion batteries according to claim 6, characterized in that, The preparation of the bismuth electrode in S2 includes the following steps: S27. Mix bismuth trioxide and graphite powder, grind, and ball mill to obtain a mixture; S28. Mix the mixture, polytetrafluoroethylene, and water to obtain a slurry; S29. Knead, roll, press, dry, and slice the slurry to obtain a bismuth electrode.

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