A dry ice assisted lithium ion battery electrode strip method

Abstract

The application discloses a dry ice assisted lithium ion battery pole piece stripping method and relates to the field of waste battery recycling. The separation method comprises the following steps: cutting the lithium battery pole piece, then mixing the pole piece with dry ice in a certain proportion and ball milling to make the electrode material fall off from the current collector to obtain a mixture; screening the mixture to obtain the current collector and the electrode material powder respectively; collecting carbon dioxide to prepare dry ice for recycling; the application is carried out at normal temperature, the low temperature and hardness characteristics of the dry ice are utilized to promote the electrode material on the electrode piece to be quickly stripped and crushed from the current collector, carbon dioxide is collected to prepare dry ice to form a closed loop, the method has the advantages of simple process, energy saving and environmental protection and the like, and is favorable for improving the production capacity of the production line.

Description

Technical Field

[0001] This invention relates to the field of lithium battery recycling and reuse, specifically to a dry ice-assisted method for stripping lithium-ion battery electrodes. Background Technology

[0002] Effective technological recycling of spent lithium batteries is crucial. Separating the electrode active materials from the current collector is critical during the recycling process. Currently, electrode material separation mainly includes mechanical separation, thermal treatment, organic solvent dissolution, and alkaline dissolution. Mechanical separation results in low purity and low added value; thermal treatment generates waste gas that pollutes the environment; organic solvents are costly and toxic, causing environmental pollution; and alkaline dissolution involves the current collector entering an alkaline solution, requiring large amounts of acid solution for subsequent processing, leading to environmental pollution.

[0003] Chinese invention CN115608755A discloses a method for separating the positive electrode material and current collector in waste lithium iron phosphate batteries, including: low-temperature pyrolysis of the positive electrode sheet obtained from dismantling the waste lithium iron phosphate battery, which degrades the binder between the positive electrode material and the current collector to reduce the adhesion. The pyrolysis process generally suffers from high energy consumption and generates fluorine-containing waste gas from the decomposition of organic matter such as binders, resulting in high environmental costs. Chinese invention CN112551597A discloses a comprehensive recycling method for the positive and negative electrodes of waste NCM ternary batteries, including crushing the battery to remove the separator and battery casing, pre-cooling at (150–270) K, and performing two-stage ball milling at (70–130) K to achieve the detachment of the positive and negative electrode materials from the current collector. This method is carried out at an operating temperature of (70–130) K, which not only has high energy consumption but also poses a significant challenge to the electrical control system of the equipment due to the extreme low temperature.

[0004] This invention proposes a method for separating the positive electrode material and the current collector in waste lithium batteries. This method can effectively separate the positive electrode material and the current collector without the need for organic solvents, high-temperature calcination, or alkaline or acid leaching. The entire process is simple, requires little equipment, and has high recycling efficiency, achieving the goal of low-cost and harmless disposal. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention discloses a dry ice-assisted method for peeling off lithium-ion battery electrodes. This invention is carried out at room temperature, utilizing the low temperature and hardness characteristics of dry ice to rapidly peel and pulverize the electrode material on the electrode sheet from the current collector. At the same time, carbon dioxide is collected to prepare dry ice to form a closed loop. It has the advantages of simple process, energy saving and environmental protection, and strong feasibility, which is conducive to improving the production capacity of the production line.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A dry ice-assisted method for peeling off lithium-ion battery electrodes includes the following steps:

[0008] (1) Cut the lithium battery electrode into small pieces;

[0009] (2) Mix the shredded material with dry ice in the specified proportions;

[0010] (3) Ball milling: the electrode material powder falls off the current collector and is crushed to obtain a mixture of current collector and electrode material.

[0011] (4) The mixture is sieved to obtain current collector and electrode material powder respectively;

[0012] (5) Collect carbon dioxide to prepare dry ice for recycling.

[0013] Furthermore, the electrode material is one or more of NCM ternary, lithium cobalt oxide, lithium manganese oxide, lithium-rich manganese-based, and lithium iron phosphate.

[0014] Furthermore, the lithium battery electrode sheet is coated on the current collector with ternary, lithium iron phosphate, graphite, silicon carbide, etc., forming a sheet-like material that serves as the electrode of the lithium battery.

[0015] Furthermore, the dry ice is a solid white carbon dioxide crystal.

[0016] Furthermore, the lithium battery electrode sheet is shredded by one or more of shearing, jaw crushing, and hammer crushing.

[0017] Further, the sheared material and dry ice are mixed in a specific ratio. The mass ratio of the material to dry ice is 3:1 to 3:90. For example, the mass ratio of the material to dry ice is 3:1, 3:5, 3:10, 3:15, 3:20, 3:25, 3:30, 3:35, 3:40, 3:45, 3:50, 3:55, 3:60, 3:65, 3:70, 3:75, 3:80, 3:85, or 3:90.

[0018] Furthermore, the ball milling process employs a vibrating ball mill, and the ball mill jars used include stainless steel ball mill jars, corundum ball mill jars, and agate ball mill jars. The ball milling speed is 600–1800 r / min (for example, ball milling speeds of 600 r / min, 700 r / min, 800 r / min, 900 r / min, 1000 r / min, 1100 r / min, 1200 r / min, 1300 r / min, 1400 r / min, 1500 r / min, and 1600 r / min). / min, 1700r / min or 1800r / min), and ball milling time is 1 to 100 min (for example, ball milling time is 1 min, 2 min, 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, 65 min, 70 min, 75 min, 80 min, 85 min, 90 min, 95 min or 100 min).

[0019] Furthermore, the dry ice used in the separation process sublimates into carbon dioxide and is collected to be made into dry ice again, forming a closed loop.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] 1. This method is carried out at room temperature. Unlike the extreme low temperature of liquid nitrogen, which poses a great challenge to electrical equipment, dry ice has lower requirements for equipment operating temperature, thus reducing equipment costs.

[0022] 2. Dry ice is a solid with a slow sublimation rate and a long service life; it has high hardness and plays an auxiliary role in grinding.

[0023] 3. The carbon dioxide gas generated during the process is collected and reprocessed into dry ice using a dry ice generator, thus realizing the recycling of dry ice and achieving a closed-loop system. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the process flow of a dry ice-assisted lithium-ion battery electrode stripping method according to Embodiment 1 of the present invention.

[0025] Figure 2 This is a field emission scanning electron microscope (FESEM) image of the ternary cathode material powder of Example 1 of the present invention. Detailed Implementation

[0026] The present invention will now be described in detail through specific embodiments.

[0027] like Figure 1 As shown, a dry ice-assisted method for peeling off lithium-ion battery electrodes includes the following steps:

[0028] (1) Cut the positive electrode sheet of the lithium battery into a certain size;

[0029] (2) Mix the shredded material with dry ice in the specified proportions;

[0030] (3) After ball milling for a certain period of time, the electrode material powder falls off the current collector, resulting in a mixture of current collector aluminum foil and electrode material;

[0031] (4) The mixture is sieved to obtain current collector aluminum foil and electrode material powder respectively;

[0032] (5) Collect carbon dioxide to prepare dry ice for recycling.

[0033] Example 1

[0034] (1) The lithium battery ternary cathode sheet is cut into small pieces with a length of 0.5cm and a width of 0.5cm using a shearing machine.

[0035] (2) Mix 2g of positive electrode sheet and 12g of dry ice in a stainless steel ball milling jar, and use a high-energy three-dimensional oscillating ball mill (MSK-SFM-3-I) from Kejing to ball mill. Set the ball mill speed to 1200r / min and the ball milling time to 3min.

[0036] (3) The ball-milled material is sieved through a vibrating screen with a mesh size of 400 mesh and a vibrating sieve duration of 5 minutes to obtain ternary cathode material and aluminum foil. Figure 2 This is an FESEM image of the ternary cathode material powder obtained in Example 1 of the present invention.

[0037] (4) Collect the generated carbon dioxide and pass it into a dry ice maker to generate dry ice for recycling.

[0038] Example 2

[0039] (1) The lithium cobalt oxide positive electrode sheet of the lithium battery is processed into small pieces with a length of 1cm and a width of 1cm using a hammer crusher.

[0040] (2) Mix 2g of positive electrode sheet and 12g of dry ice in a stainless steel ball milling jar, and use a high-energy three-dimensional oscillating ball mill (MSK-SFM-3-I) from Kejing to ball mill. Set the ball mill speed to 1200r / min and the ball milling time to 3min.

[0041] (3) The ball-milled material is sieved through a vibrating screen with a mesh size of 300 mesh and a vibrating sieve duration of 10 min to obtain lithium cobalt oxide cathode material and aluminum foil.

[0042] (4) Collect the generated carbon dioxide and pass it into a dry ice maker to generate dry ice for recycling.

[0043] Example 3

[0044] (1) The lithium iron phosphate positive electrode sheet of the lithium battery is processed into small pieces with a length of 1cm and a width of 1cm using a jaw crusher.

[0045] (2) Mix 2g of positive electrode sheet and 12g of dry ice in a stainless steel ball milling jar, and use a high-energy three-dimensional oscillating ball mill (MSK-SFM-3-I) from Kejing to ball mill. Set the ball mill speed to 1200r / min and the ball milling time to 4min.

[0046] (3) The ball-milled material is sieved through a vibrating screen with a mesh size of 400 mesh and a vibrating sieve duration of 5 minutes to obtain lithium iron phosphate cathode material and aluminum foil.

[0047] (4) Collect the generated carbon dioxide and pass it into a dry ice maker to generate dry ice for recycling.

[0048] Comparative Example 1

[0049] The difference between this comparative example and Example 1 is that dry ice in step (2) is replaced with liquid nitrogen, and the ball mill in step (2) is replaced with a Miqi liquid nitrogen planetary ball mill (YD-XQM). Other steps and parameters remain unchanged.

[0050] Comparative Example 2

[0051] The difference between this comparative example and Example 1 is that dry ice in step (2) is replaced with liquid nitrogen, the ball mill in step (2) is replaced with a Miqi liquid nitrogen planetary ball mill (YD-XQM), the ball milling time is changed to 15 min, and other steps and parameters remain unchanged.

[0052] As shown in Table 1, high recovery rate and purity of cathode materials can be achieved in a short time by using dry ice grinding in conjunction with Kejing's high-energy three-dimensional oscillating ball mill (MSK-SFM-3-I).

[0053] Table 1. Recovery rate and purity of cathode materials in the examples and comparative examples.

[0054]

[0055] The above description is a further detailed explanation of the present invention in conjunction with specific preferred embodiments. It should not be considered that the specific embodiments of the present invention are limited to this. For those skilled in the art, several simple deductions or substitutions can be made without departing from the present invention, and all of these should be considered to fall within the scope of protection of the present invention as defined by the submitted claims.

Claims

1. A dry ice-assisted method for peeling off lithium-ion battery electrodes, characterized in that, Includes the following steps: (1) Cut the lithium battery electrodes into small pieces; (2) The shredded material and dry ice are mixed in a certain proportion; wherein the mass ratio of the material to the dry ice is 3:1 to 3:90; (3) Ball milling, the electrode material powder falls off the current collector, and a mixture of current collector and electrode material is obtained; (4) The mixture is sieved to obtain current collector and electrode material powder respectively; (5) Collect carbon dioxide to prepare dry ice for recycling.

2. The dry ice-assisted method for peeling off lithium-ion battery electrodes according to claim 1, characterized in that: The lithium battery electrode sheet is formed by coating a current collector with ternary, lithium iron phosphate, lithium cobalt oxide, graphite or silicon carbon electrode materials to form a sheet-like material, which serves as the electrode of the lithium battery.

3. The dry ice-assisted method for peeling off lithium-ion battery electrodes according to claim 1, characterized in that: The electrode material is one or more of NCM, lithium cobalt oxide, lithium manganese oxide, lithium-rich manganese-based material, and lithium iron phosphate.

4. The dry ice-assisted method for peeling off lithium-ion battery electrodes according to claim 1, characterized in that: The dry ice is a solid white carbon dioxide crystal.

5. A dry ice-assisted method for peeling off lithium-ion battery electrodes according to claim 1, characterized in that: The lithium battery electrode sheets are shredded by one or more of shearing, jaw crushing, and hammer crushing.

6. The dry ice-assisted method for peeling off lithium-ion battery electrodes according to claim 1, characterized in that: The ball milling process employs a vibrating ball mill, and the ball mill jar used in the ball mill includes one or more of stainless steel ball mill jars, corundum ball mill jars, and agate ball mill jars. The ball milling speed is 600~1800 r / min, and the ball milling time is 1~100 min.

7. The dry ice-assisted method for peeling off lithium-ion battery electrodes according to claim 1, characterized in that: The aforementioned sieving method is a way to separate mixtures of different particle sizes into various particle size grades using a perforated sieve surface.

8. The dry ice-assisted method for peeling off lithium-ion battery electrodes according to claim 1, characterized in that: The dry ice used in the stripping process sublimates into carbon dioxide and is then collected and made into dry ice again, forming a closed loop.

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