Method for separating active material layer and current collector of positive pole piece

Abstract

The invention discloses a method for separating an active material layer and a current collector of a positive pole piece, belongs to the technical field of lithium ion battery recovery, and solves the problem that the separation effect of an active material and a current collector cannot be efficient and environment-friendly at the same time in the prior art. The method comprises the following steps: crushing and cleaning a to-be-treated positive pole piece, introducing high-heat wet steam, separating a current collector and an active substance layer, and respectively collecting the current collector and the active substance layer; and collecting the treated wet steam. According to the method provided by the invention, environmental pollution and resource waste are effectively avoided, and energy consumption is effectively reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium ion battery recycling, and more particularly to a method for separating an active material layer and a current collector of a positive electrode sheet. BACKGROUND

[0002] For discharged batteries, the method of "mechanical crushing + physical separation" is usually selected in current industrial production to effectively extract various components, but the quality of the products obtained in this process is poor and the impurity content is high, which poses a major challenge to the subsequent recycling process. Artificial disassembly followed by accurate separation is a common means to solve this problem. In the process of accurate separation, efficient separation of the active material layer and the current collector of the battery electrode sheet is a key step to avoid the introduction of aluminum impurities. The two are tightly combined through the binder, and if the separation method is improper, aluminum impurities will be introduced in the subsequent regeneration process, affecting the performance of the regenerated material.

[0003] Currently, the methods for separating the active material layer and the current collector in lithium ion battery electrode sheets mainly include heat treatment, electrolysis, and soaking. The binder used in the battery electrode sheet is mostly organic polymer, such as polyvinylidene fluoride and carboxymethyl cellulose. By reducing or increasing the temperature, the binding force of the molecular chain in the binder can be changed, and the adhesion between the positive electrode material and the current collector can be weakened. The patent with publication number CN116315214A cuts the positive electrode sheet and the negative electrode sheet of the waste lithium battery, mixes them, and then performs heat treatment in a muffle furnace. The obtained heat treatment product is peeled off to obtain black powder waste, copper foil and / or aluminum foil; however, the process of heat treatment to decompose the binder is prone to produce HF, which causes corrosion to the equipment and pollutes the air, and the energy consumption is also high. The patent with publication number CN104485492B places the electrode sheet of the waste lithium ion battery between the two poles of an electrolytic cell, and electrolyzes with a periodically varying current until the electrode material falls off from the surface of the current collector. Then, the current collector and the electrode material are taken out of the electrolytic cell, and the separated current collector and electrode material are obtained; however, this method requires additional power supply, and the energy consumption is high. The soaking method includes soaking in organic solvents or strong acid and strong base solutions. In the soaking process, means such as ultrasound and gas production are used to speed up the separation speed of the current collector and the active material layer. The patent with publication number CN113571791A mixes the electrode sheet with an organic acid solution, uses H +The patent with the publication number CN115020854A soaks the electrode sheet in an acid or organic solution, and introduces gas into the solution, thereby accelerating the separation of the electrode material layer and the current collector through the disturbance of the gas. Dissolving aluminum with strong acid and strong base will produce acid and alkali waste liquid, and strong acid can not only dissolve aluminum but also dissolve positive electrode material, which will damage the positive electrode material and make the recycling process more complex. After the adhesive is dissolved by the organic solvent, the solution becomes viscous, and organic matter will be left on the surface of the electrode particles after solid-liquid separation, which increases the difficulty of separation. Moreover, the high cost and environmental unfriendliness of organic solvents also limit their widespread application.

[0004] Therefore, an efficient separation method of active material and current collector is urgently needed to improve the separation efficiency while effectively avoiding the environmental pollution caused by adhesive thermal decomposition, organic solvent, strong acid and strong base, and reducing the energy consumption in the separation process, which is a problem that needs to be solved urgently. SUMMARY

[0005] The present application provides a separation method of active material layer and current collector of positive electrode sheet to solve the problem that the separation effect of active material and current collector in the prior art cannot be both efficient and environmentally friendly.

[0006] The present application provides a separation method of active material layer and current collector of positive electrode sheet, comprising the following steps: crushing and cleaning the to-be-processed positive electrode sheet, introducing high-temperature and high-humidity steam, separating and processing the current collector and the active material layer, and collecting them respectively; and collecting the processed steam.

[0007] As a possible implementation manner, the to-be-processed positive electrode sheet is from a scrapped lithium iron phosphate battery or from the offcut in the process of producing lithium iron phosphate positive electrode sheet; and / or, the cleaning comprises the steps of soaking in an organic solvent and then drying; and / or, the collected processed steam is collected by condensation.

[0008] As a possible implementation manner, the organic solvent is any one of propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, dimethyl ether of ethylene glycol and tetrahydrofuran.

[0009] As a possible implementation manner, the soaking time is 1-72h; and / or, the drying temperature is 60-160℃, and the time is 1-72h; and / or, the coolant for condensation collection is any one of water, air, calcium chloride solution, liquid ammonia and ethylene glycol.

[0010] As a possible implementation manner, the principle of the crushing is that the area after the crushing is less than 12 cm*12 cm. The proper crushing is beneficial to increase the contact area of the high-temperature and wet steam with the positive electrode tab, accelerate the proceeding of the separation process, and effectively improve the separation efficiency.

[0011] As a possible implementation manner, the high-temperature and wet steam is any one of water vapor, tail gas generated in an industrial nitric acid production process, tail gas generated in a coal gas desulfurization process, and tail gas generated in a coal-fired power plant. The water vapor has high temperature, is humid, and is weakly alkaline; the industrial nitric acid production mainly adopts an ammonia oxidation method, and the generated tail gas mainly comprises water vapor and a small amount of NO x , and the whole presents weak acidity; no matter whether the iron oxide desulfurization technology or the activated carbon desulfurization technology is used, the tail gas generated in the coal gas desulfurization process mainly comprises water vapor and a small amount of sulfur-containing gas; and the tail gas generated in the coal-fired power plant mainly comprises CO2, SO2 and water vapor. Therefore, the selection standard of the gas is high temperature, humidity, and no other impurities damaging the active material.

[0012] As a possible implementation manner, the mass ratio of the amount of the high-temperature and wet steam to the mass of the positive electrode tab to be treated is 2-120:1; and / or, the flow rate of the high-temperature and wet steam is 0.01-10 kg / min.

[0013] Compared with the prior art, the present application has the following beneficial effects:

[0014] The present application uses water vapor, tail gas generated in an industrial nitric acid production process, tail gas generated in a coal gas desulfurization process, tail gas generated in a coal-fired power plant, and the like as the separation medium, and recovers the tail gas after the treatment, realizes the functional reuse of the waste gas, effectively avoids the pollution of the environment and the waste of resources; and the present application does not need the supply of external energy, and can effectively reduce the energy consumption compared with the electrolysis method and the heat treatment method.

[0015] The separation method provided by the present application has simple operation steps and good separation effect, and the smooth current collector can be obtained after the separation, which is convenient for the recycling and reuse of the current collector; and the separation medium used in the separation method provided by the present application will not damage the active material layer. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0017] Figure 1The SEM diagram of the separated lithium iron phosphate positive electrode material provided by the embodiment of the present application.

[0018] Figure 2 The XRD diagram of the separated lithium iron phosphate positive electrode material provided by the embodiment of the present application. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0020] To solve the problem that the separation effect of the active material and the current collector cannot be both efficient and environmentally friendly in the prior art, the embodiment of the present application provides a separation experiment of an active material layer and a current collector of a positive electrode sheet.

[0021] It can be known that the recovery rate of aluminum is greater than 97.7% by using the separation method provided by the present application; the waste gas is functionally utilized, external energy supply is not needed, environmental pollution and resource waste are effectively avoided, and energy consumption is effectively reduced.

[0022] The technical solutions of the present application will be further described below with reference to specific embodiments.

[0023] Embodiment 1

[0024] The embodiment provides a separation experiment of an active material layer and a current collector of a positive electrode sheet.

[0025] The scrapped lithium iron phosphate battery is manually disassembled to obtain the failed positive electrode sheet. The electrode sheet is cleaned in a dimethyl carbonate (DMC) solution for 3 times to remove the residual electrolyte on the surface of the electrode sheet, and is dried in a 110℃ air drying oven for 12h to obtain the dried positive electrode sheet. The electrode sheet is crushed to below 10cm*10cm and is put into a tubular furnace for a separation experiment. In the experiment, water vapor is selected as the separation medium, is introduced into the tubular furnace at a flow rate of 0.02-0.05kg / min (calculated according to the feeding rate of 1kg / min), and is continuously introduced for 5h. After the treatment is completed, the water vapor is condensed into water by a condenser. The treated electrode sheet is taken out, and the active material layer is easily peeled from the surface of the aluminum foil. The recovery rate of aluminum in the failed positive electrode sheet reaches 97.7%.

[0026] The separated lithium iron phosphate positive electrode material is scanned by an electron microscope to obtain the SEM diagram as shown in FIG. 1. Figure 1The SEM diagram shown in the figure shows that the lithium iron phosphate positive electrode material obtained by separation presents a polycrystalline morphology, and the secondary particles are complete, indicating that the treatment method of the present application will not destroy the original morphology of the active material.

[0027] The XRD diagram shown in the figure shows that the XRD curve of the lithium iron phosphate positive electrode material obtained by separation has diffraction peaks consistent with typical LiFePO4 diffraction peak positions (PDF #83-2092), and no impurity phase, indicating that the treatment method of the present application will not destroy the crystal structure of the active material and will not introduce impurity phases. Figure 2

[0028] Example 2

[0029] This embodiment provides a separation experiment of the active material layer and the current collector of the positive electrode sheet.

[0030] The failed positive electrode sheet is obtained by manually disassembling the scrapped lithium iron phosphate battery, and the positive electrode sheet is washed 3 times in N-methyl pyrrolidone (NMP) solution to remove the residual electrolyte on the surface of the positive electrode sheet. The dried positive electrode sheet is obtained by drying in a 120°C air drying oven for 10h, and the positive electrode sheet is crushed to below 5cm*5cm and put into a tube furnace for separation experiment. In this experiment, a mixed gas of water vapor and nitrogen oxide (simulating the tail gas generated in the industrial production of nitric acid) is selected as the separation medium, and is introduced into the tube furnace at a flow rate of 0.1-0.2kg / min (based on the feeding of 1kg / min) for 10h. After the treatment is completed, the mixed gas is condensed by a condenser, and the treated positive electrode sheet is taken out. The active material layer is easily peeled off from the surface of the aluminum foil, and the recovery rate of aluminum in the failed positive electrode sheet reaches 98.5%.

[0031] Example 3

[0032] This embodiment provides a separation experiment of the active material layer and the current collector of the positive electrode sheet.

[0033] The failed positive electrode sheet is obtained by manually disassembling the scrapped lithium iron phosphate battery, and the positive electrode sheet is washed 3 times in N-methyl pyrrolidone (NMP) solution to remove the residual electrolyte on the surface of the positive electrode sheet. The dried positive electrode sheet is obtained by drying in a 120°C air drying oven for 10h, and the positive electrode sheet is crushed to below 5cm*5cm and put into a tube furnace for separation experiment. In this experiment, a mixed gas of water vapor and nitrogen oxide (simulating the tail gas generated in the industrial production of nitric acid) is selected as the separation medium, and is introduced into the tube furnace at a flow rate of 0.1-0.2kg / min (based on the feeding of 1kg / min) for 10h. After the treatment is completed, the mixed gas is condensed by a condenser, and the treated positive electrode sheet is taken out. The active material layer is easily peeled off from the surface of the aluminum foil, and the recovery rate of aluminum in the failed positive electrode sheet reaches 98.5%.

[0031] Example 3

[0032] This embodiment provides a separation experiment of the active material layer and the current collector of the positive electrode sheet.

[0033] The failed positive electrode sheet is obtained by manually disassembling the scrapped lithium iron phosphate battery, and the positive electrode sheet is washed 3 times in N-methyl pyrrolidone (NMP) solution to remove the residual electrolyte on the surface of the positive electrode sheet. The dried positive electrode sheet is obtained by drying in a 120°C air drying oven for 10h, and the positive electrode sheet is crushed to below 5cm*5cm and put into a tube furnace for separation experiment. In this experiment, a mixed gas of water vapor and nitrogen oxide (simulating the tail gas generated in the industrial production of nitric acid) is selected as the separation medium, and is introduced into the tube furnace at a flow rate of 0.1-0.2kg / min (based on the feeding of 1kg / min) for 10h. After the treatment is completed, the mixed gas is condensed by a condenser, and the treated positive electrode sheet is taken out. The active material layer is easily peeled off from the surface of the aluminum foil, and the recovery rate of aluminum in the failed positive electrode sheet reaches 98.5%.

[0034] Example 4

[0035] This example provides a separation experiment of the active material layer and the current collector of a positive electrode tab.

[0036] The scrap material in the production of lithium iron phosphate tab is crushed to below 4 cm x 4 cm and placed in a tube furnace for a separation experiment. Water vapor is selected as the separation medium in this experiment, which is introduced into the tube furnace at a flow rate of 0.07-0.09 kg / min (based on 1 kg / min of feed), and the continuous introduction time is 20 h. After the treatment is completed, the water vapor is condensed into water by a condenser. The treated tab is taken out, and the active material layer is easily peeled off from the surface of the aluminum foil. The recovery rate of aluminum in the failed positive electrode tab reaches 99.1%.

[0037] Example 5

[0038] This example provides a separation experiment of the active material layer and the current collector of a positive electrode tab.

[0039] The failed positive electrode tab is obtained by manually disassembling the scrapped lithium iron phosphate battery. The tab is washed in a methyl ethyl carbonate (EMC) solution for 3 times to remove the residual electrolyte on the surface of the tab. The tab is dried in a 80°C air drying oven for 16 h to obtain a dried positive electrode tab. The tab is crushed to below 7 cm x 7 cm and placed in a tube furnace for a separation experiment. A mixed gas of water vapor and sulfur-containing gas (simulating the tail gas generated in the coal gas desulfurization and coal-fired power plant) is selected as the separation medium in this experiment, which is introduced into the tube furnace at a flow rate of 2-2.5 kg / min (based on 1 kg / min of feed), and the continuous introduction time is 2 h. After the treatment is completed, the mixed gas is condensed by a condenser. The treated tab is taken out, and the active material layer is easily peeled off from the surface of the aluminum foil. The recovery rate of aluminum in the failed positive electrode tab reaches 98.2%.

[0040] Example 6

[0041] This example provides a separation experiment of the active material layer and the current collector of a positive electrode tab.

[0042] The failed positive electrode tab is obtained by manually disassembling the scrapped lithium iron phosphate battery. The tab is crushed to below 6 cm x 6 cm and placed in a tube furnace for a separation experiment. A mixed gas of water vapor and nitrogen oxide (simulating the tail gas generated in the industrial nitric acid production process) is selected as the separation medium in this experiment, which is introduced into the tube furnace at a flow rate of 0.5-0.7 kg / min (based on 1 kg / min of feed), and the continuous introduction time is 15 h. After the treatment is completed, the mixed gas is condensed by a condenser. The treated tab is taken out, and the active material layer is easily peeled off from the surface of the aluminum foil. The recovery rate of aluminum in the failed positive electrode tab reaches 98.9%.

[0043] Example 7

[0044] The present embodiment provides a separation experiment of the active material layer and the current collector of the positive electrode tab.

[0045] The scraps in the production of lithium iron phosphate electrode tab are crushed to below 2cm x 2cm and put into a tube furnace for separation experiment. In the experiment, the mixed gas of water vapor and sulfur-containing gas (simulating coal gas desulfurization and tail gas produced by coal-fired power plants) is selected as the separation medium, which is introduced into the tube furnace at a flow rate of 1.1-1.3kg / min (based on 1kg / min of feeding), and the continuous introduction time is 24h. After the treatment is completed, the mixed gas is condensed by a condenser, and the treated electrode tab is taken out. The active material layer is easily peeled off from the surface of the aluminum foil, and the recovery rate of aluminum in the failed positive electrode tab reaches 99.3%.

[0046] Although the preferred embodiments of the present application have been described, those skilled in the art who, once aware of the basic inventive concept, can make additional changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0047] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application also intends to include these modifications and variations.

Claims

1. A method for separating the active material layer and the current collector of a positive electrode sheet, characterized in that, Includes the following steps: The positive electrode sheet to be processed is broken and cleaned, and high-temperature wet steam is introduced to separate the current collector and the active material layer and collect them separately. Collect the treated wet vapor.

2. The method according to claim 1, characterized in that, The positive electrode sheet to be processed comes from scrapped lithium iron phosphate batteries or from scrap materials generated during the production of lithium iron phosphate positive electrode sheets; And / or, the cleaning includes the steps of: immersing in an organic solvent followed by drying; And / or, the water vapor collected after treatment is collected by condensation.

3. The method according to claim 2, characterized in that, The organic solvent is any one of propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, ethylene glycol dimethyl ether, and tetrahydrofuran.

4. The method according to claim 2, characterized in that, The soaking time is 1–72 hours; And / or, the drying temperature is 60–160°C and the duration is 1–72 h; And / or, the coolant collected by condensation is any one of water, air, calcium chloride solution, liquid ammonia, and ethylene glycol.

5. The method according to claim 1, characterized in that, The principle of crushing is that the area after crushing is less than 12cm × 12cm.

6. The method according to claim 1, characterized in that, The high-temperature wet steam can be any one of the following: water vapor, tail gas generated during the industrial production of nitric acid, tail gas generated during the desulfurization of coal gas, or tail gas generated by a coal-fired power plant.

7. The method according to claim 1, characterized in that, The ratio of the amount of high-temperature humid steam to the mass of the positive electrode sheet to be treated is 2 to 120:1; And / or, the flow rate of the hot, humid steam is 0.01 to 10 kg / min.

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