Method for separating and recycling positive electrode active material of retired lithium ion battery

Abstract

The invention discloses a method for separating and recycling a positive electrode active material of a retired lithium ion battery, belongs to the technical field of battery recycling, and aims to solve the problems of high calcination temperature, high energy consumption, low active substance recycling rate, easiness in aluminum foil corrosion, secondary pollution and the like in the prior art. The method comprises the following steps: calcining a retired lithium iron phosphate positive pole piece containing residual electrolyte in a nitrogen / argon atmosphere at 300-550 DEG C for 5 minutes to 6 hours, and soaking the retired lithium iron phosphate positive pole piece in deionized water at 50-100 DEG C for 0.5-24 hours, so as to realize efficient stripping of an active substance and an aluminum foil current collector. The method is low in calcination temperature, low in energy consumption, simple in process, green and free of waste liquid pollution, the recovery rate of active substances is nearly 100%, the separated aluminum foil is free of residues and corrosion and can be directly recycled, and the method is suitable for large-scale green recovery of the positive pole piece of the retired lithium ion battery and has good economic and environmental benefits.

Description

Technical Field

[0001] This invention relates to environmental protection technology, and in particular to a method for separating and recycling positive electrode active materials from retired lithium-ion batteries. Background Technology

[0002] Industry forecasts predict that by 2030, the global volume of retired lithium-ion batteries will exceed 20 million tons, containing significant amounts of high-value metals (such as lithium, cobalt, and nickel) and carbon materials. As core components of batteries (accounting for over 30% of battery mass), the efficient recycling of positive and negative electrode sheets is crucial for resource recycling. Recycling methods for electrode materials from retired lithium-ion batteries include high-value metal extraction and direct repair and regeneration. The former uses hydrometallurgical or pyrometallurgical techniques to convert high-value metals into metals, metal alloys, or metal salts, while the latter uses physicochemical methods to repair the crystal structure of the electrode materials and restore their electrochemical performance. However, both of these recycling methods face the challenge of separating the active material from the current collector.

[0003] The recovered lithium-ion battery positive electrode sheet includes active components, conductive agents, binders, aluminum foil current collectors, and residual electrolyte. The binder ensures close contact between the active material and the current collector. The aluminum foil current collector is thin and flexible, making it difficult to achieve efficient separation of the two using traditional physical methods. As a result, the recovery rate of active material is low, and the aluminum content in the black powder is high.

[0004] Patent document CN121565978A discloses a method for separating and recycling the positive and negative electrode materials of waste lithium iron phosphate electrolyte cells. After calcination at high temperature (400–650°C) for a certain time (1.5–3 hours) under inert gas (including nitrogen, argon, or helium) protection, the active material can be separated from the aluminum current collector by vibration sieving. The highest recovery rate of the positive electrode material is 99.32%. Patent document CN105489960A discloses a method for separating lithium battery current collectors and active materials. The recycled electrode sheets are immersed in deionized water at 75–85°C, with the addition of anionic surfactants and hydrochloric acid. After maintaining the temperature and stirring for 4–6 hours, the current collector and active material can be separated. The highest recovery rate of the positive electrode material is 89.9%.

[0005] However, existing technologies suffer from problems such as high energy consumption or low recovery rate of cathode materials, and the difficulty in separating active materials from current collectors has not been completely solved. Summary of the Invention

[0006] This invention addresses the problems of existing technologies for separating positive electrode active materials from retired lithium-ion batteries, such as high calcination temperature, high energy consumption, low recovery rate of active materials, easy corrosion and damage of aluminum foil, and waste liquid pollution. It provides a method for separating and recycling positive electrode active materials from retired lithium-ion batteries, achieving low-temperature, low-energy, high-efficiency, and green separation, ensuring nearly 100% recovery of active materials, while protecting the aluminum foil from damage and corrosion.

[0007] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows.

[0008] A method for separating and recycling positive electrode active materials from retired lithium-ion batteries includes the following steps: Take a retired lithium-ion battery positive electrode sheet containing a small amount of residual electrolyte and place it in a calcination device under an inert atmosphere for calcination treatment. The calcined positive electrode sheet is transferred to deionized water and soaked at a constant temperature until the active material and aluminum foil current collector automatically separate. Collect the stripped active material and intact aluminum foil to complete the separation and recycling.

[0009] The positive electrode sheet has lithium iron phosphate as its active material component, polyvinylidene fluoride (PVDF) as its binder, and aluminum foil as its current collector.

[0010] The calcination atmosphere is one or a mixture of two inert gases, namely nitrogen and argon.

[0011] The calcination temperature is 300-550℃, preferably 300℃; the calcination time is 5 min-6 h, preferably 30 min.

[0012] The soaking temperature is 50-100℃, and the soaking time is 0.5-24h, preferably 12h. The soaking temperature and soaking time are negatively correlated; the higher the temperature, the shorter the required soaking time.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. High separation efficiency and nearly 100% recovery rate: The coupled calcination and soaking processes achieve complete separation of active materials from aluminum foil, with an active material recovery rate of nearly 100% and no aluminum impurities contaminating the recovered black powder.

[0014] 2. Low temperature and low consumption, energy saving and emission reduction: The calcination temperature is as low as 300℃, which is far lower than the traditional high temperature calcination process, significantly reducing equipment energy consumption and heat loss, and greatly reducing industrial operation costs.

[0015] 3. The aluminum foil remains intact: After separation, the aluminum foil surface has no active substance residue, no chemical corrosion, and no physical damage, and can be directly recycled and reused, improving the overall recycling efficiency.

[0016] 4. Green and environmentally friendly, with no secondary pollution: The entire process uses an inert atmosphere and pure water immersion, without adding strong acids, strong alkalis, or toxic surfactants, and there is no emission of acidic waste liquid or harmful waste gas, making it environmentally friendly.

[0017] 5. Simple process and easy to industrialize: The process flow is short, the equipment is highly versatile, the operating conditions are mild, and there is no need for complex screening and reaction equipment, making it suitable for large-scale recycling and processing of retired lithium batteries. Attached Figure Description

[0018] Figure 1 The electrode sheets were separated after calcination at 550℃ for 30 minutes in a nitrogen atmosphere.

[0019] Figure 2 The electrode sheets were separated after calcination at 380℃ for 30 minutes in a nitrogen atmosphere.

[0020] Figure 3 The electrode was separated after calcination at 300℃ for 30 minutes in a nitrogen atmosphere. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] A method for separating and recycling positive electrode active materials from retired lithium-ion batteries, comprising the following steps: S1. Take a retired lithium iron phosphate positive electrode sheet containing residual electrolyte (active material: lithium iron phosphate, binder: PVDF, current collector: aluminum foil). S2. Place the positive electrode sheet into a tube furnace, introduce nitrogen as a protective atmosphere, heat to 300℃, and calcine at a constant temperature for 30 minutes. S3. Remove the calcined electrode sheet and soak it in deionized water at 50℃ for 12 hours. S4. The active material is completely and automatically detached, while the aluminum foil remains intact. The active material and aluminum foil are collected.

[0023] Tests showed that the active material recovery rate was 99.9%, and there was no residue or corrosion on the aluminum foil surface.

[0024] Example 2 A method for separating and recycling positive electrode active materials from retired lithium-ion batteries, comprising the following steps: S1. Take the retired lithium iron phosphate positive electrode sheet, place it in a tube furnace, introduce argon atmosphere, heat to 380℃, and calcine at a constant temperature for 30 minutes. S2. After calcination, the electrode sheet is soaked in 90℃ deionized water for 24 hours; S3. Complete the separation and collect the active material and aluminum foil.

[0025] The test results showed that the active material recovery rate was 99.8%, and the aluminum foil was undamaged and uncorroded.

[0026] Example 3 A method for separating and recycling positive electrode active materials from retired lithium-ion batteries, comprising the following steps: S1. Take the retired lithium iron phosphate positive electrode sheet and calcine it at 550℃ for 5 minutes under a nitrogen atmosphere; S2. Soak the calcined electrode sheet in 100℃ deionized water for 0.5h; S3. Complete the separation and collect the active material and aluminum foil.

[0027] Tests showed that the active material recovery rate was 99.7%, and the aluminum foil remained intact.

[0028] Comparative Example 1 The process disclosed in publication number CN 121565978A is adopted: calcination at 600℃ for 2 hours under an inert atmosphere, followed by separation by vibrating sieve.

[0029] Results: The recovery rate of active material was 99.32%, but the calcination temperature was high, the energy consumption was high, and the aluminum foil was prone to softening and deformation.

[0030] Comparative Example 2 The process disclosed in publication number CN 105489960A is as follows: soaking and stirring in water at 75-85℃ with anionic surfactant and hydrochloric acid for 5 hours.

[0031] Results: The recovery rate of active materials was only 89.9%, the acidic waste liquid polluted the environment, and the aluminum foil showed slight corrosion.

[0032] The above description represents the preferred embodiment of the present invention. It should be noted that, for those skilled in the art, various modifications and improvements can be made without departing from the principles and core ideas of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A method for separating and recycling positive electrode active materials from retired lithium-ion batteries, comprising the following steps: S1. Take a retired lithium-ion battery positive electrode sheet containing a small amount of residual electrolyte and place it in a calcination device under an inert atmosphere for calcination treatment; S2. Transfer the calcined positive electrode sheet to deionized water and soak it at a constant temperature until the active material and aluminum foil current collector automatically separate. S3. Collect the stripped active material and intact aluminum foil to complete the separation and recycling.

2. The method for separating and recycling the positive electrode active material of retired lithium-ion batteries according to claim 1, characterized in that, in, The positive electrode sheet has lithium iron phosphate as its active material component, polyvinylidene fluoride (PVDF) as its binder, and aluminum foil as its current collector.

3. The method for separating and recycling the positive electrode active material of retired lithium-ion batteries according to claim 2, characterized in that, The calcination atmosphere is one or a mixture of two inert gases, namely nitrogen and argon.

4. A method for separating and recycling positive electrode active materials of retired lithium-ion batteries according to any one of claims 1-3, characterized in that, The calcination temperature is 300–550℃, and the calcination time is 5 min–6 h.

5. The method for separating and recycling the positive electrode active material of retired lithium-ion batteries according to claim 4, characterized in that, The soaking temperature is 50-100℃, and the soaking time is 0.5-24h.

6. The method for separating and recycling the positive electrode active material of retired lithium-ion batteries according to claim 5, characterized in that, Soaking temperature and soaking time are negatively correlated; the higher the temperature, the shorter the required soaking time.

7. The method for separating and recycling the positive electrode active material of retired lithium-ion batteries according to claim 6, characterized in that, The calcination temperature was 300℃, the calcination time was 30 min, the soaking temperature was 50℃, and the soaking time was 12 h.

8. The method for separating and recycling positive electrode active materials of retired lithium-ion batteries according to claim 6, characterized in that, The calcination temperature was 380℃, the calcination time was 30 min, the soaking temperature was 100℃, and the soaking time was 0.5 h.

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