New energy lithium iron phosphate battery positive electrode material fluidization repair roasting regeneration method
By combining porous precursors with fluidized bed calcination, the problems of incomplete impurity removal, incomplete crystal repair, and uneven carbon coating in the recycling of lithium iron phosphate cathode materials have been solved, and high-performance lithium iron phosphate materials have been prepared, which are suitable for the regeneration of new energy batteries.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NORTHEASTERN UNIV CHINA
- Filing Date
- 2026-01-16
- Publication Date
- 2026-04-10
AI Technical Summary
In existing lithium iron phosphate cathode material recycling technologies, impurity removal is incomplete, crystal repair is incomplete, and carbon coating is uneven, resulting in poor material purity and conductivity. Furthermore, traditional processes are complex and costly, making it difficult to achieve efficient regeneration.
A method combining porous precursor construction and fluidized bed calcination is adopted. Porous microsphere precursors are formed by spray granulation, and combined with fluidized bed high-temperature regeneration calcination, efficient impurity removal, iron valence state control and uniform carbon coating are achieved to form a continuous conductive network.
High-performance lithium iron phosphate materials were prepared, exhibiting high initial discharge specific capacity, good cycle performance, high tap density, excellent processing performance, and a green and efficient process with minimal wastewater generation.
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Figure CN121839969A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of resource utilization technology for waste lithium-ion batteries, specifically to a fluidized bed remediation and calcination regeneration method for positive electrode materials of new energy lithium iron phosphate batteries. Background Technology
[0002] With the explosive growth of the new energy vehicle industry, a large number of lithium iron phosphate power batteries are about to reach the end of their service life. From an environmental and resource perspective, the efficient recycling of valuable materials is crucial.
[0003] Currently, the main methods for recycling lithium iron phosphate cathode materials are hydrometallurgy and direct regeneration. Hydrometallurgy is complex, costly, and generates large amounts of waste liquid; while traditional direct regeneration technology typically uses simple solid-state sintering, which is insufficient to completely remove residual binders and conductive agents from the electrode sheets, affecting the purity of the recycled material; solid-state reaction has low mass transfer efficiency, resulting in incomplete crystal repair; and Fe... 2+ Lithium iron phosphate (LFP) batteries are easily oxidized, and their uneven carbon coating results in poor electrical conductivity. Therefore, developing a regeneration technology capable of deep impurity removal and efficient crystal structure repair and uniform carbon coating is crucial for promoting the industrialization of lithium iron phosphate battery recycling. Summary of the Invention
[0004] This invention aims to address the shortcomings of existing direct regeneration technologies by providing a solid-phase remediation and regeneration method for lithium iron phosphate that combines porous precursor construction with fluidized bed calcination. Through innovative process design, this method effectively solves key technical challenges such as impurity removal, iron valence state control, crystal regeneration, and carbon coating uniformity, ultimately yielding high-performance regenerated lithium iron phosphate materials.
[0005] To achieve the above objectives, this invention provides a fluidized bed repair, calcination, and regeneration method for positive electrode materials of new energy lithium iron phosphate batteries, comprising the following steps:
[0006] First, the cathode sheets obtained from the discharge, dismantling, and stripping of waste lithium iron phosphate batteries are crushed and sieved to obtain lithium iron phosphate cathode powder. Then, the lithium iron phosphate cathode powder is calcined to obtain a purified product mainly composed of FePO4 and defective LiFePO4. The purified product is then wet-milled to obtain a slurry. The slurry is granulated and dried to obtain porous spherical precursor particles, which are then subjected to fluidized bed high-temperature regeneration calcination to obtain recycled material. The recycled material is then washed and dried to obtain a high-performance new energy lithium iron phosphate battery cathode material.
[0007] Furthermore, the lithium iron phosphate cathode powder is calcined in an air atmosphere at a temperature range of 650℃ to 750℃ for 0.5 to 1.5 hours. This process aims to completely decompose and oxidize the residual electrolyte, polyvinylidene fluoride binder, and conductive carbon black, and other organic impurities to obtain a purified product mainly composed of FePO4 and defective LiFePO4.
[0008] Furthermore, the wet grinding process of the impurity-removed product is as follows: 0.5% to 2% by mass of lithium carbonate or lithium hydroxide is added to the impurity-removed product as a supplementary lithium source, and 8% to 15% by mass of glucose, sucrose, or citric acid is added as a reducing agent and carbon source organic matter to obtain a mixture; then 30% to 40% by mass of deionized water or ethanol is added as a dispersion medium and the mixture is placed in a stirred mill for wet grinding for 4 to 6 hours to obtain a slurry with uniform particle size and good dispersion.
[0009] Furthermore, the process of granulating and drying the slurry using a spray drying device is as follows: the slurry is granulated using a spray drying device; the inlet air temperature of the spray dryer is controlled at 180℃~220℃, the outlet air temperature is controlled at 80℃~110℃, and the atomization pressure is controlled at 0.1MPa~0.5MPa.
[0010] Furthermore, the porous spherical precursor particles have a particle size of -10 micrometers to -50 micrometers and a content of over 90%.
[0011] Furthermore, the fluidized high-temperature regeneration calcination process is as follows: under the protection of an inert atmosphere such as nitrogen or argon, the temperature is increased to 750℃~850℃ at a heating rate of 50℃ / min~90℃ / min, and then calcined at this temperature for 1.5 hours~2.5 hours.
[0012] Furthermore, the recycled material is washed with water to remove soluble lithium salt byproducts generated during the high-temperature reaction.
[0013] Furthermore, the cathode material of the new energy lithium iron phosphate battery was tested in an installation test. At a 0.1C rate, the initial discharge specific capacity of the regenerated lithium iron phosphate cathode material was higher than 150mAh / g, and the capacity retention rate was higher than 80% after 700 cycles at a 1C rate.
[0014] Compared with traditional technologies, the beneficial effects and innovations of this invention are as follows:
[0015] 1. Unique Synergistic Process of "Porous Precursor + Fluidized Bed Calcination": The core innovation of this invention lies in combining the porous microsphere precursor formed by spray granulation with fluidized bed high-temperature regeneration calcination. The porous structure greatly increases the reaction interface, while fluidization ensures uniform heating of each particle and a uniform reaction atmosphere. The synergistic effect of the two completely overcomes the shortcomings of low mass transfer efficiency and incomplete reaction in traditional solid-state methods.
[0016] 2. Highly efficient iron reduction and crystal repair: The fluidized bed gas flow can rapidly remove gaseous products such as water vapor generated during the reaction, promoting the reduction reaction in the forward direction and ensuring the preservation of Fe. 3+ To Fe 2+ The reduction is more complete and thorough. The porous structure is Li + and Fe 2+ The diffusion provides a convenient channel, making the recrystallization of LiFePO4 more complete and reducing crystal defects.
[0017] 3. Uniform carbon coating: The organic carbon source decomposes simultaneously inside and on the surface of the microspheres. The uniform thermal and atmospheric fields brought about by fluidization enable the decomposed carbon to be uniformly deposited on the surface of the newly grown LiFePO4 grains, forming a continuous and dense conductive carbon coating, which significantly improves the electronic conductivity of the recycled material.
[0018] 4. Excellent product performance and improved physical properties: The new energy lithium iron phosphate battery cathode material prepared by this invention not only has a high initial discharge specific capacity (up to 155 mAh / g or more, 0.1C rate) and good cycle performance, but also has higher tap density and better processing performance due to its spherical morphology and suitable particle size distribution, and can be directly used in the preparation of new batteries.
[0019] 5. Green and efficient process: The entire process mainly uses physical methods and high-temperature reactions, avoiding the use of large amounts of acids and alkalis, and generating less wastewater. It is an environmentally friendly and efficient regeneration technology. Attached Figure Description
[0020] Figure 1 This is a process flow diagram of the lithium iron phosphate fluidized bed remediation roasting and regeneration method described in this invention. Detailed Implementation
[0021] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.
[0022] This invention provides a fluidized bed repair and calcination regeneration method for positive electrode materials of new energy lithium iron phosphate batteries, such as... Figure 1 As shown, it includes the following steps:
[0023] Step 1, Impurity Removal and Roasting: The positive electrode sheets obtained from the discharge, disassembly, and peeling of waste lithium iron phosphate batteries are crushed and sieved to obtain lithium iron phosphate positive electrode powder; the powder is roasted in air at a temperature range of 650℃~750℃ for 0.5h~1.5h; this process aims to completely decompose and oxidize to remove residual electrolyte, polyvinylidene fluoride binder, conductive carbon black and other organic impurities, to obtain a purified product mainly composed of FePO4 and defective LiFePO4;
[0024] Step 2, Ingredient Preparation and Wet Fine Grinding: Add 0.5%~2% by mass of lithium carbonate or lithium hydroxide as a supplementary lithium source to the impurity-removed product, and add 8%~15% by mass of glucose, sucrose or citric acid as a reducing agent and carbon source to obtain a mixture; then add 30%~40% by mass of deionized water or ethanol or other dispersion media and place them together in a stirred mill (such as using zirconium oxide or alumina mill media) for wet grinding for 4h~6h to obtain a slurry with uniform particle size and good dispersion.
[0025] Step 3, Spray Granulation and Drying: The slurry is granulated using a spray drying device. The inlet air temperature is controlled at 180℃~220℃, the outlet air temperature at 80℃~110℃, and the atomization pressure at 0.1MPa~0.5MPa. Through this process, the slurry is transformed into spherical precursor particles with a porous microsphere structure. The spherical precursor particles have a particle size of -10 micrometers to -50 micrometers and a content of over 90%. The porous structure of the spherical precursor particles provides a large specific surface area and abundant reaction channels for subsequent reduction and regeneration reactions.
[0026] Step 4: Fluidized High-Temperature Regeneration Calcination: The spherical precursor particles are placed in a fluidized bed calcination furnace and heated to 750℃~850℃ at a heating rate of 50℃ / min~90℃ / min under the protection of an inert atmosphere such as nitrogen and argon. The temperature is then maintained at this level for 1.5 hours~2.5 hours. During this process, fluidization ensures that each precursor microsphere is in full and uniform contact with the high-temperature protective gas, achieving efficient gas-solid phase heat and mass transfer. The porous structure ensures that the reducing gas (generated by the decomposition of organic carbon sources) can penetrate deep into the particles, reducing Fe... 3+ Completely reduced to Fe 2+ This process promotes the regeneration, repair, and growth of LiFePO4 crystals. Meanwhile, the decomposed carbon can uniformly coat the surface of the newly grown LiFePO4 crystals, forming an excellent conductive network.
[0027] Step 5, Water washing and drying process: The recycled material is washed with water to remove the soluble lithium salt byproducts generated in the high-temperature reaction, and then dried to obtain high-performance new energy lithium iron phosphate battery cathode material.
[0028] The obtained new energy lithium iron phosphate battery cathode material was tested in an installation test. At a 0.1C rate, its initial discharge specific capacity was higher than 150mAh / g, and its capacity retention rate was higher than 80% after 700 cycles at a 1C rate.
[0029] Example 1
[0030] The positive electrode powder recovered from the lithium iron phosphate power battery pack of retired electric vehicles of a company in Guangdong Province is mainly composed of LiFePO4 and contains about 5 wt% carbon black and PVDF.
[0031] A fluidized bed repair and calcination regeneration method for positive electrode materials of new energy lithium iron phosphate batteries includes the following steps:
[0032] 1. Impurity Removal and Calcination: The powder is placed in a suspension calcination furnace and heated to 700℃ in an air atmosphere. It is then calcined at this temperature for 1.25 hours to obtain the purified product. After natural cooling, the powder is removed and turns grayish-white, indicating that organic impurities have been removed.
[0033] II. Ingredients and wet fine grinding: Add 1.2 wt% lithium carbonate powder, 9.5 wt% sucrose, and 40 wt% deionized water to the purified product and grind them together in a vertical stirred mill for 5.5 hours to obtain a slurry with moderate viscosity and good flowability.
[0034] 3. Spray granulation and drying: The slurry is fed into the spray device, the inlet air temperature is controlled at 200℃, the outlet air temperature is 95℃, and the atomization pressure is 0.15Mpa, to obtain spherical precursor particles with a porous microsphere structure and a particle size of -15 micrometers (95%).
[0035] IV. Fluidized High-Temperature Regeneration Calcination: Spherical precursor particles are loaded into a fluidized bed reactor, nitrogen is introduced, the temperature is raised to 800℃ at 65℃ / min, and calcined at this temperature for 2 hours to obtain recycled material;
[0036] V. Washing and Drying Process: The recycled material is washed three times with deionized water at 60°C and then dried to obtain the final recycled lithium iron phosphate product.
[0037] VI. Performance Testing: Using this recycled cathode material for on-machine testing, its initial discharge specific capacity reached 156.5 mAh / g at 0.1C rate, and the capacity retention rate was 81.2% after 700 cycles at 1C rate.
[0038] Example 2
[0039] The positive electrode powder was recovered from the lithium iron phosphate power battery pack of a retired electric vehicle from a company in Anhui.
[0040] A fluidized bed repair and calcination regeneration method for positive electrode materials of new energy lithium iron phosphate batteries includes the following steps:
[0041] 1. Impurity Removal and Calcination: The powder is placed in a suspension calcination furnace and heated to 750°C in air atmosphere. It is then calcined at this temperature for 1.5 hours to obtain the purified product. After natural cooling, the powder is removed and turns grayish-white, indicating that organic impurities have been removed.
[0042] II. Ingredients and wet fine grinding: Add 1.9 wt% lithium carbonate powder, 15 wt% sucrose, and 35 wt% deionized water to the purified product and grind them together in a vertical stirred mill for 6 hours to obtain a slurry with moderate viscosity and good flowability.
[0043] III. Spray granulation and drying: The slurry is fed into the spray device, the inlet air temperature is controlled at 220℃, the outlet air temperature is controlled at 110℃, and the atomization pressure is 0.45Mpa, to obtain spherical precursor particles with a porous microsphere structure and a particle size of -20 micrometers (95%).
[0044] IV. Fluidized High-Temperature Regeneration Calcination: Spherical precursor particles are loaded into a fluidized bed reactor, nitrogen is introduced, the temperature is raised to 850℃ at 90℃ / min, and calcined at this temperature for 2.5h to obtain recycled material;
[0045] V. Washing and Drying Process: The recycled material is washed three times with deionized water at 60°C and then dried to obtain the final recycled lithium iron phosphate product.
[0046] VI. Performance Testing: Using this recycled cathode material for on-machine testing, its initial discharge specific capacity reached 160.1 mAh / g at 0.1C rate, and the capacity retention rate was 81.2% after 700 cycles at 1C rate.
[0047] Example 3
[0048] The positive electrode powder was recovered from the lithium iron phosphate power battery pack of a retired electric vehicle in Tianjin.
[0049] A fluidized bed repair and calcination regeneration method for positive electrode materials of new energy lithium iron phosphate batteries includes the following steps:
[0050] 1. Impurity Removal and Calcination: The powder is placed in a suspension calcination furnace and heated to 650°C in air atmosphere. It is then calcined at this temperature for 0.8 hours to obtain the purified product. After natural cooling, the powder is removed and turns grayish-white, indicating that organic impurities have been removed.
[0051] II. Ingredients and wet fine grinding: Add 0.6 wt% lithium carbonate powder, 8.5 wt% sucrose, and 38 wt% deionized water to the purified product and grind them together in a vertical stirred mill for 4 hours to obtain a slurry with moderate viscosity and good flowability.
[0052] III. Spray granulation and drying: The slurry is fed into the spray device, the inlet air temperature is controlled at 180℃, the outlet air temperature is controlled at 80℃, and the atomization pressure is 0.15Mpa, to obtain spherical precursor particles with a porous microsphere structure and a particle size of -30 micrometers at 92%.
[0053] IV. Fluidized High-Temperature Regeneration Calcination: Spherical precursor particles are loaded into a fluidized bed reactor, nitrogen is introduced, the temperature is raised to 750℃ at 55℃ / min, and calcined at this temperature for 2 hours to obtain recycled material.
[0054] V. Washing and Drying Process: The recycled material is washed three times with deionized water at 60°C and then dried to obtain the final recycled lithium iron phosphate product.
[0055] VI. Performance Testing: Using this recycled cathode material for on-machine testing, its initial discharge specific capacity reached 158.4 mAh / g at 0.1C rate, and the capacity retention rate was 82.1% after 700 cycles at 1C rate.
[0056] Comparative Example 1
[0057] The same powder as in Example 3 was used for the test. The difference between the test steps of this comparative example and Example 3 is that this comparative example does not perform fluidized high-temperature regeneration calcination, but uses a traditional muffle furnace for calcination at a temperature of 750°C for 5 hours.
[0058] When this recycled cathode material was used for on-machine testing, its initial discharge specific capacity was only 122.4 mAh / g at 0.1C rate, and its capacity retention rate was 70.1% after 700 cycles at 1C rate.
Claims
1. A fluidized bed repair, calcination, and regeneration method for positive electrode materials of new energy lithium iron phosphate batteries, characterized in that, Includes the following steps: First, the cathode sheets obtained from the discharge, dismantling, and stripping of waste lithium iron phosphate batteries are crushed and sieved to obtain lithium iron phosphate cathode powder. Then, the lithium iron phosphate cathode powder is calcined to obtain a purified product mainly composed of FePO4 and defective LiFePO4. The purified product is then wet-milled to obtain a slurry. The slurry is granulated and dried to obtain porous spherical precursor particles, which are then subjected to fluidized bed high-temperature regeneration calcination to obtain recycled material. The recycled material is then washed and dried to obtain a high-performance new energy lithium iron phosphate battery cathode material.
2. The method for fluidized bed repair, calcination, and regeneration of positive electrode materials for new energy lithium iron phosphate batteries according to claim 1, characterized in that, The calcination process of the lithium iron phosphate cathode powder is as follows: calcination is carried out in an air atmosphere at a temperature range of 650℃~750℃ for 0.5~1.5h. This process aims to completely decompose and oxidize to remove residual electrolyte, polyvinylidene fluoride binder, and conductive carbon black and other organic impurities, to obtain a purified product mainly composed of FePO4 and defective LiFePO4.
3. The method for fluidized bed repair, calcination, and regeneration of positive electrode materials for new energy lithium iron phosphate batteries according to claim 1, characterized in that, The process of wet grinding the impurity-removed product is as follows: 0.5% to 2% by mass of lithium carbonate or lithium hydroxide is added to the impurity-removed product as a supplementary lithium source, and 8% to 15% by mass of glucose, sucrose, or citric acid is added as a reducing agent and carbon source organic matter to obtain a mixture; then 30% to 40% by mass of deionized water or ethanol is added as a dispersion medium and the mixture is placed in a stirred mill for wet grinding for 4 to 6 hours to obtain a slurry with uniform particle size and good dispersion.
4. The method for fluidized bed repair, calcination, and regeneration of positive electrode material for new energy lithium iron phosphate batteries according to claim 1, characterized in that, The process of granulating and drying the slurry through a spray drying device is as follows: the slurry is granulated through the spray drying device; the inlet air temperature of the spray drying is controlled at 180℃~220℃, the outlet air temperature is controlled at 80℃~110℃, and the atomization pressure is controlled at 0.1MPa~0.5MPa.
5. The method for fluidized bed repair, calcination, and regeneration of positive electrode material for new energy lithium iron phosphate batteries according to claim 1, characterized in that, The porous spherical precursor particles have a particle size of -10 micrometers to -50 micrometers and a content of over 90%.
6. The method for fluidized bed repair, calcination, and regeneration of positive electrode materials for new energy lithium iron phosphate batteries according to claim 1, characterized in that, The fluidized high-temperature regeneration calcination process is as follows: under the protection of an inert atmosphere such as nitrogen or argon, the temperature is increased to 750℃~850℃ at a heating rate of 50℃ / min~90℃ / min, and then calcined at this temperature for 1.5 hours~2.5 hours.
7. The method for fluidized bed repair, calcination, and regeneration of positive electrode material for new energy lithium iron phosphate batteries according to claim 1, characterized in that, The recycled material is washed with water to remove soluble lithium salt byproducts generated during the high-temperature reaction.
8. The method for fluidized bed repair, calcination, and regeneration of positive electrode material for new energy lithium iron phosphate batteries according to claim 1, characterized in that, The cathode material of the new energy lithium iron phosphate battery was tested in an installation test. At a 0.1C rate, the initial discharge specific capacity of the regenerated lithium iron phosphate cathode material was higher than 150mAh / g, and the capacity retention rate was higher than 80% after 700 cycles at a 1C rate.