Method for crushing and pyrolyzing waste lithium iron phosphate battery

Abstract

The invention discloses a method for crushing and pyrolyzing a waste lithium iron phosphate battery. The method comprises the following steps: cutting a shell to separate a shell core, crushing and drying a battery core, sorting to remove a diaphragm and a negative electrode, pyrolyzing and depowdering and the like. Organic gas is purified and condensed to recycle electrolyte, and organic waste gas is purified and discharged. The metal shell can be prevented from being mixed with crushed materials, and impurities are reduced; lithium iron phosphate powder obtained through separation can be directly used for regeneration, and the problem that products of an existing wet method / co-pyrolysis process cannot be directly regenerated is solved; the electrolyte is synchronously condensed and recycled in multiple links, organic waste gas is reduced, the fluorine treatment cost is reduced, emission of three wastes is effectively reduced, the resource utilization rate and the environmental protection property are obviously improved, the recycling purity of the positive electrode powder reaches 99.2-99.8 wt%, and the recycling rate reaches 98% or above. The method is suitable for resource recovery of waste lithium iron phosphate batteries.

Description

Technical Field

[0001] This invention belongs to the field of environmental protection technology and relates to a method for treating waste lithium batteries, and more particularly to a method for treating waste lithium iron phosphate batteries. Background Technology

[0002] With the rapid development of the new energy vehicle industry, lithium iron phosphate batteries, as a type of power battery with high safety performance and low cost, are widely used in electric vehicles, energy storage systems, and other fields. However, lithium iron phosphate batteries have a limited lifespan, and the generation of a large number of waste batteries in the future will become a major challenge for environmental protection and resource recycling. Existing waste lithium iron phosphate battery recycling technologies mainly include hydrometallurgy, pyrometallurgy, and direct regeneration. Among them, hydrometallurgy involves processes such as acid leaching and precipitation. Although the recovery rate is relatively high, it generates a large amount of wastewater and waste residue, causing serious environmental pollution and high energy consumption. Pyrometallurgy separates metals through high-temperature smelting, but it is prone to causing the combustion of organic matter, producing harmful gases such as fluorides and dioxins. The processing cost is high and the recycling efficiency is low. Although direct regeneration is environmentally friendly, traditional crushing and pyrolysis processes often cannot meet the raw material requirements for direct regeneration. The purity of the cathode powder is low, the recovery rate is insufficient, and improper treatment of organic waste gas during pyrolysis can cause secondary pollution. To address these issues, a highly efficient and environmentally friendly crushing and pyrolysis method is needed to fully separate organic matter, electrolyte, separator, and positive and negative electrode materials from waste lithium iron phosphate batteries, and to improve the purity and efficiency of positive electrode powder recycling.

[0003] Chinese patent document CN109193064A, published on January 11, 2019, discloses a method for sorting and recycling valuable components from waste power lithium batteries. This method involves crushing the waste power lithium batteries as a whole, volatilizing and recovering organic solvents, screening and air-classifying the separators, and pyrolyzing the positive and negative electrode sheets and powders to separate aluminum and copper foils. This method is designed for wet recycling; the crushing of the casing, connectors, and other components along with the battery cell introduces a large amount of metallic impurities. Furthermore, the joint pyrolysis of the positive and negative electrode sheets fails to separate the positive and negative electrode powders, making the final product unsuitable for direct recycling.

[0004] Chinese patent document CN119839002A, published on April 18, 2025, discloses a method for crushing and sorting waste lithium batteries. The method involves removing the battery casing using laser cutting, removing the electrolyte using a low-temperature plasma treatment device, feeding the battery cells into crushing equipment, then screening and sorting them, and finally entering a hydrometallurgical process. However, this method, which involves subsequent hydrometallurgical processing, cannot separate the positive and negative electrode powders.

[0005] There are significant technical bottlenecks in existing methods for processing waste lithium batteries, including the inability to accurately identify and efficiently separate positive and negative electrode active materials, avoid the mixing of non-target components, and construct high-purity recycling pathways that meet the needs of direct regeneration. Summary of the Invention

[0006] To overcome the existing technical difficulties, this invention provides a method for crushing and pyrolyzing waste lithium iron phosphate batteries. This method can fully separate the organic and inorganic components in waste lithium iron phosphate batteries, especially effectively separating lithium iron phosphate cathode powder, and the processing is green and environmentally friendly.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for crushing and pyrolyzing waste lithium iron phosphate batteries includes the following steps: (1) Cut the outer shell of the waste lithium iron phosphate battery and separate the core to obtain the battery cell and aluminum and steel shells; (2) The de-shelled battery cell is crushed and dried to obtain dry sheet battery material and organic gas; (3) The dried sheet battery material is sorted to remove the separator and negative electrode sheet to obtain the positive electrode sheet material; (4) The positive electrode material is pyrolyzed and then de-powdered to obtain lithium iron phosphate positive electrode powder and organic waste gas; The organic gas is purified and then condensed to obtain an electrolyte, and the organic waste gas is purified and then discharged as exhaust gas.

[0008] Further, in step (1), when cutting the outer shell and separating the core, the outer shell is cut while keeping the internal core intact in a sealed and inert gas protected environment, the core is taken out intact, the outer shell is collected separately, and the electrolyte volatilized during the process is collected, purified and condensed.

[0009] Furthermore, in step (2), the dried sheet battery material is obtained in irregularly shaped fragments, with the longest size of the fragments ≤15 cm and the shortest size ≥1 cm.

[0010] Furthermore, in step (2), the drying temperature is 80~250℃, the drying time is 0.2~3h, and the drying method can be evaporation.

[0011] Furthermore, in step (2), the mixed black powder formed by the positive electrode powder and the negative electrode powder that naturally fall off during the crushing and drying process is collected separately by a dust removal device; the dust removal device can be a bag filter or a cyclone dust collector, etc.

[0012] Furthermore, in step (2), the electrolyte volatilized during the crushing process and the electrolyte evaporated during the evaporation process are collected, purified, and condensed for electrolyte recovery.

[0013] Furthermore, in step (3), the method for removing the diaphragm and negative electrode sheet is one or a combination of magnetic separation, wind separation, gravity separation, and color separation.

[0014] Furthermore, in step (4), the pyrolysis environment is a sealed environment protected by an inert gas, the pyrolysis temperature is 400~600℃, and the pyrolysis time is 0.2~2h.

[0015] Furthermore, in step (4), powder removal is carried out by one or more combinations of hammer crushing, friction decomposition, wind separation, gravity separation, and screen screening.

[0016] In the above context, the sealed and inert gas protected environment refers to a sealed atmosphere such as nitrogen or argon.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention separates the outer shell, electrolyte, separator, and binder by first removing the shell and then crushing them, thus avoiding the mixing of the metal shell into the crushed material and reducing impurities. Multi-stage sorting enriches the positive electrode material, providing high-purity raw materials for subsequent pyrolysis. Separating the negative electrode before pyrolysis avoids mixing of positive and negative electrode powders, and the resulting lithium iron phosphate powder can be directly used for regeneration, solving the problem that the products of existing wet / co-pyrolysis processes cannot be directly regenerated. The electrolyte is simultaneously condensed and recovered in multiple stages such as cutting, crushing, and drying, reducing organic waste gas and fluorine treatment costs. The diaphragm separates and reduces pyrolysis waste gas and tar, reducing energy consumption and emissions of waste gas, wastewater, and solid waste. Compared with traditional methods, it is greener and more environmentally friendly, and significantly improves resource utilization and environmental protection. Attached Figure Description

[0018] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0019] Example 1 The waste lithium iron phosphate battery crushing and pyrolysis method provided in this embodiment is used to process square aluminum-cased lithium iron phosphate batteries. The method involves crushing and drying to remove the electrolyte, air classification to remove the separator, color classification to remove the negative electrode, obtaining the positive electrode sheet, and finally pyrolysis and powder removal. The specific steps are as follows: Step (1): In a sealed environment with nitrogen protection, cut the outer shell of the waste lithium iron phosphate square aluminum-cased battery, keeping the internal cells intact, separate the core and the casing to obtain the cells and aluminum casing. Step (2): In a sealed environment with nitrogen protection, the battery cell obtained in step (1) is crushed and dried, and the size of the crushed fragments is controlled to be between 5 and 10 cm. The drying temperature is controlled to be 190℃ and the drying time is 1 hour to remove the electrolyte from the fragments. The organic gas obtained during the drying process is purified and then condensed to obtain the recovered electrolyte. Step (3): The dried battery material obtained in step (2) is first separated by wind sorting to remove the separator, and then separated by color sorting to remove the negative electrode sheet to obtain the positive electrode sheet material; Step (4): The positive electrode material obtained in step (3) is pyrolyzed and then de-powdered. The pyrolysis environment is sealed and protected by nitrogen. The pyrolysis temperature is controlled at 450℃ and the pyrolysis time is 1h. The organic waste gas obtained during the pyrolysis process is purified and then discharged. The de-powdering method is to crush the material with a hammer crusher and then screen it through a screen with a mesh size of 200 mesh.

[0020] In this embodiment, the purity of the lithium iron phosphate cathode powder recovered by this method is 99.5 wt%, the recovery rate of the lithium iron phosphate cathode powder is 98%, the recovery rate of aluminum foil in the current collector is 98%, and the purity of the recovered aluminum foil is 99.5 wt%.

[0021] Example 2 This embodiment of the waste lithium iron phosphate battery crushing and pyrolysis method is used to process square steel-cased lithium iron phosphate batteries. The process involves crushing and drying to remove the electrolyte, gravity sorting to remove the separator, color sorting to remove the negative electrode, obtaining the positive electrode sheet, and finally pyrolysis and powder removal. The specific steps are as follows: Step (1): In a sealed environment with nitrogen protection, cut the outer shell of the waste lithium iron phosphate square steel-cased battery, keeping the internal cells intact, separate the core and the casing to obtain the cells and aluminum casing. Step (2): In a sealed environment with nitrogen protection, the battery cell obtained in step (1) is crushed and dried, and the size of the crushed fragments is controlled to be between 4 and 8 cm; the drying temperature is controlled to be 180℃ and the drying time is 1 hour to remove the electrolyte from the fragments; the organic gas obtained during the drying process is purified and then condensed to obtain the recovered electrolyte. Step (3): The dried battery material obtained in step (3) is first separated by gravity to remove the separator, and then the negative electrode sheet is removed by color sorting to obtain the positive electrode sheet material; Step (4): The positive electrode material obtained in step (4) is pyrolyzed and then de-powdered. The pyrolysis environment is sealed and protected by nitrogen. The pyrolysis temperature is controlled at 420℃ and the pyrolysis time is 1h. The organic waste gas obtained in the pyrolysis process is purified and then discharged. The de-powdering method is to crush the material with a friction decomposition machine and then screen it through a sieve with a sieve size of 200 mesh.

[0022] In this embodiment, the purity of the lithium iron phosphate cathode powder recovered by this method is 99.8 wt%, the recovery rate of the lithium iron phosphate cathode powder is 98.5%, the recovery rate of the aluminum foil in the current collector is 98.5%, and the purity of the recovered aluminum foil is 99.8 wt%.

[0023] Example 3 This embodiment describes a method for crushing and pyrolyzing waste lithium iron phosphate batteries. The process involves processing square aluminum-cased lithium iron phosphate batteries by crushing and drying to remove the electrolyte, gravity sorting to remove the separator, color sorting to remove the negative electrode, obtaining the positive electrode sheet, and finally pyrolyzing and removing powder. The specific steps are as follows: Step (1): In a sealed environment with nitrogen protection, cut the outer shell of the waste lithium iron phosphate square steel-cased battery, keeping the internal cells intact, separate the core and the casing to obtain the cells and aluminum casing. Step (2): In a sealed environment with nitrogen protection, the battery cell obtained in step (1) is crushed and dried, and the size of the crushed fragments is controlled to be between 6 and 12 cm; the drying temperature is controlled to be 160℃ and the drying time is 1.5 h to remove the electrolyte from the fragments; the organic gas obtained during the drying process is purified and then condensed to obtain the recovered electrolyte. Step (3): The dry battery material obtained in step (2) is first separated by gravity to remove the separator, and then the negative electrode sheet is removed by color sorting to obtain the positive electrode sheet material; Step (4): The positive electrode material obtained in step (3) is pyrolyzed and then de-powdered. The pyrolysis environment is sealed and protected by nitrogen. The pyrolysis temperature is controlled at 400℃ and the pyrolysis time is 1.5h. The organic waste gas obtained during the pyrolysis process is purified and then discharged. The de-powdering method is to crush the material with a friction decomposition machine and then screen it through a sieve with a sieve size of 150 mesh.

[0024] In this embodiment, the purity of the lithium iron phosphate cathode powder recovered by this method is 99.2 wt%, the recovery rate of the lithium iron phosphate cathode powder is 98%, the recovery rate of aluminum foil in the current collector is 98%, and the purity of the recovered aluminum foil is 99.2 wt%.

[0025] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalents or substitutions are all included within the scope defined by the claims of the present invention.

Claims

1. A method for crushing and pyrolyzing waste lithium iron phosphate batteries, characterized in that, Includes the following steps: (1) Cut the outer shell of the waste lithium iron phosphate battery and separate the core to obtain the battery cell and aluminum and steel shells; (2) The de-shelled battery cell is crushed and dried to obtain dry sheet battery material and organic gas; (3) The dried sheet battery material is sorted to remove the separator and negative electrode sheet to obtain the positive electrode sheet material; (4) The positive electrode material is pyrolyzed and then de-powdered to obtain lithium iron phosphate positive electrode powder and organic waste gas; The organic gas is purified and then condensed to obtain an electrolyte, and the organic waste gas is purified and then discharged as exhaust gas.

2. The method for crushing and pyrolyzing waste lithium iron phosphate batteries according to claim 1, characterized in that, In step (1), the outer shell is cut and the core is separated in a sealed and inert gas protected environment. The outer shell is cut while keeping the internal core intact. The core is taken out intact, the outer shell is collected separately, and the electrolyte that evaporates during the process is collected, purified and condensed.

3. The method for crushing and pyrolyzing waste lithium iron phosphate batteries according to claim 1, characterized in that: In step (2), the dried sheet battery material is obtained in irregularly shaped fragments, with the longest size of the fragments ≤15 cm and the shortest size ≥1 cm.

4. The method for crushing and pyrolyzing waste lithium iron phosphate batteries according to claim 1, characterized in that: In step (2), the drying temperature is 80~250℃, the drying time is 0.2~3h, and the drying method is evaporation.

5. The method for crushing and pyrolyzing waste lithium iron phosphate batteries according to claim 1, characterized in that: In step (2), the mixed black powder formed by the positive electrode powder and the negative electrode powder that naturally fall off during the crushing and drying process is collected separately by a dust removal device.

6. The method for crushing and pyrolyzing waste lithium iron phosphate batteries according to claim 1, characterized in that: In step (2), the electrolyte that volatilizes during the crushing process and the electrolyte that evaporates during the drying process are collected, purified, and condensed for electrolyte recovery.

7. The method for crushing and pyrolyzing waste lithium iron phosphate batteries according to claim 1, characterized in that: In step (3), the method for removing the diaphragm and negative electrode sheet is one or a combination of magnetic separation, wind separation, gravity separation, and color separation.

8. The method for crushing and pyrolyzing waste lithium iron phosphate batteries according to claim 1, characterized in that, In step (4), the pyrolysis environment is a sealed environment protected by inert gas, the pyrolysis temperature is 400~600℃, and the pyrolysis time is 0.2~2h.

9. The method for crushing and pyrolyzing waste lithium iron phosphate batteries according to claim 1, characterized in that, In step (4), powder removal is carried out by one or more combinations of hammer crushing, friction decomposition, air separation, gravity separation, and screen screening.

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