Discharge method of waste lithium ion battery

Abstract

The application discloses a kind of waste lithium ion battery discharging methods, belong to lithium ion battery recycling field.The discharging method includes the following steps:S1.waste lithium ion battery is pretreated;S2.waste lithium ion battery after pretreatment is immersed in water;S3.waste lithium ion battery is taken out from water when battery negative pole is not completely reacted, and self-heating drying is carried out using the remaining battery energy, and completely discharged lithium ion battery is obtained.Compared with traditional brine discharge, the application has high discharging efficiency, complete discharge, small aluminum loss, fully utilizes battery energy for self-heating drying, and saves cost.The application is simple to operate, has low requirement for equipment, and is suitable for large-scale industrial production.

Description

Technical Field

[0001] This invention relates to a method for discharging waste lithium-ion batteries, belonging to the field of lithium-ion battery recycling. Background Technology

[0002] Lithium-ion batteries boast advantages such as high energy density, long lifespan, high safety, and low environmental pollution. They are widely used in 3C products, energy storage, and electric vehicles, especially in recent years with the rapid development of the new energy vehicle and energy storage industries, leading to an explosive growth in demand for lithium-ion batteries.

[0003] Lithium-ion batteries have a life cycle, and improper disposal of retired lithium-ion batteries will lead to serious environmental problems and resource shortages. Therefore, the recycling and reuse of retired lithium-ion batteries is of great significance for the effective use of resources, environmental protection, and reduction of lithium-ion battery costs.

[0004] Discharging spent lithium-ion batteries is a crucial step in lithium-ion battery recycling and is fundamental to ensuring their safe recycling and reuse. Although on-charge crushing has been extensively studied, on the one hand, the technology itself is not yet mature; on the other hand, as lithium-ion batteries develop towards higher energy density and their charge capacity gradually increases, on-charge crushing still poses significant safety hazards.

[0005] Discharging spent lithium batteries mainly includes two methods: chemical discharge and physical discharge. Traditional chemical discharge is highly adaptable but has low discharge efficiency and a long discharge cycle. During discharge, electrochemical reactions occur, corroding battery materials, reducing material recycling rates, and generating large amounts of wastewater and exhaust gas, polluting the environment and increasing recycling costs. Physical discharge includes charge / discharge machine discharge and load discharge. Charge / discharge machine discharge requires expensive equipment, resulting in high investment costs. Load discharge is uncontrollable, poses safety risks, and cannot be scaled up for mass production. Furthermore, physical discharge is not suitable for all battery types, such as tabless pouch batteries. Therefore, large-scale production requires combining chemical discharge with physical discharge. Summary of the Invention

[0006] To address the shortcomings of existing discharge technologies, the present invention aims to provide a method for discharging spent lithium-ion batteries. The discharge method provided by this invention features high discharge efficiency, thorough discharge, low aluminum loss, full utilization of battery energy, and reduced drying costs, making it suitable for large-scale industrial production.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A method for discharging spent lithium-ion batteries includes the following steps:

[0009] S1. Pre-treatment of waste lithium-ion batteries;

[0010] S2. Immerse the pre-treated waste lithium-ion batteries in water;

[0011] S3. Before the negative electrode of the battery has fully reacted, the waste lithium-ion battery is removed from the water and dried by self-heating using the remaining battery energy to obtain a fully discharged lithium-ion battery.

[0012] The discharge principle of this invention is that water reacts with the lithium negative electrode of the battery, destroying the battery structure and achieving discharge. The chemical reaction equation is as follows:

[0013] 2Li + 2H₂O = 2LiOH + H₂↑

[0014] Preferably, the waste lithium-ion batteries in step S1 include pouch batteries and aluminum-cased batteries.

[0015] Preferably, the method for pre-treating waste lithium-ion batteries in step S1 is as follows: when the waste lithium-ion battery is a pouch battery, the pouch battery is cut open along the direction of the battery tabs; when the waste lithium-ion battery is an aluminum-cased battery, the explosion-proof valve of the aluminum-cased battery is destroyed.

[0016] Preferably, when cutting open the pouch battery, the cutting length is 1 / 2 to 2 / 3 of the pouch battery length.

[0017] Preferably, the water used to soak the waste batteries in step S2 is tap water or purified water.

[0018] Preferably, the mass ratio of water to waste battery in step S2 is 4:1 to 3:1.

[0019] Preferably, in step S2, the immersion depth of the waste battery is greater than 20cm.

[0020] Preferably, in step S3, the discharge reaction time is controlled to be 0.5-3 hours, and then the waste lithium-ion battery is removed.

[0021] Preferably, in step S3, the self-heating drying time is 5-24 hours.

[0022] The drying principle of this invention is as follows: Controlling the discharge time, the battery is removed before the negative electrode has fully reacted. After removal, the negative electrode continues to react with water, releasing heat. This heat is used to evaporate the water inside the battery, fully utilizing the battery's energy for self-heating drying. The water content of the waste lithium-ion batteries after drying in step S3 is less than 5%.

[0023] The beneficial effects of this invention are:

[0024] (1) High discharge efficiency and thorough discharge. Traditional salt water discharge soft-pack batteries cannot be discharged after the tabs are corroded, and the discharge is incomplete. (2) Low aluminum loss, which can improve the recycling rate of waste batteries. (3) Combined with the self-heating drying designed in this invention, that is, controlling the discharge time, the battery is taken out before the negative electrode of the battery has completely reacted. After taking it out, the negative electrode of the battery continues to react with water and releases heat. This heat is used to evaporate the water in the battery, making full use of the battery energy for self-heating drying and saving drying costs. (4) This invention is simple to operate, has low equipment requirements, and is suitable for large-scale industrial production. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments will be briefly described below.

[0026] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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.

[0028] like Figure 1 As shown, the present invention provides a method for discharging waste lithium-ion batteries, comprising the following steps:

[0029] S1. Pre-treatment of waste lithium-ion batteries;

[0030] When the used lithium-ion battery is a pouch battery, cut it open, making the cut along the tabless side, and cut a length of 1 / 2 to 2 / 3 of the battery length; when the used lithium-ion battery is an aluminum-cased battery, break the explosion-proof valve of the aluminum-cased battery.

[0031] S2. Immerse the pre-treated waste lithium-ion batteries in water;

[0032] The water used to soak the used batteries is tap water or pure water, and the mass ratio of water to used batteries is 4:1 to 3:1. The immersion depth of the used batteries is greater than 20cm.

[0033] S3. When the negative electrode of the battery has not fully reacted, the discharge reaction time is usually controlled to be 0.5-3h. Then, the waste lithium-ion battery is taken out of the water and self-heated and dried using the remaining battery energy. The self-heating drying time is 5-24h to obtain a fully discharged lithium-ion battery.

[0034] The present invention will be further described in detail below through specific embodiments.

[0035] Example 1

[0036] A method for discharging used soft-pack lithium-ion batteries, using 32Ah soft-pack ternary lithium batteries with a pre-discharge voltage of 4.15V, is described below:

[0037] (1) Cut the soft-pack battery along the tab side with a blade, and cut the length of the cut to 1 / 2 of the battery length.

[0038] (2) Immerse the cut-open soft-pack battery in pure water with a water-to-battery mass ratio of 3:1 and a battery immersion depth of 30cm to discharge it.

[0039] (3) After discharging for 3 hours, remove the battery that is not fully discharged from the pure water. The negative electrode of the battery continues to react with the water and release heat. After 12 hours, use the heat generated by the reaction between the negative electrode of the battery and the water to evaporate the water in the battery.

[0040] The same method was used to discharge 10 groups of soft-pack batteries, and the voltage after discharge was measured with a multimeter. The moisture content of the batteries was measured by drying them at 120℃ and normal pressure. The test data are shown in Table 1.

[0041] Table 1. Voltage and moisture content of pouch cells before and after discharge and after self-heating drying

[0042]

[0043] As can be seen from Table 1, the discharge method of the present invention for discharging soft-pack batteries has high discharge efficiency, the voltage after discharge is 0, the discharge is complete, and the battery is retrieved before the negative electrode has fully reacted, making full use of the battery energy for self-heating drying, so that the moisture content of the battery after discharge is less than 5%, saving drying costs.

[0044] Example 2

[0045] A method for discharging a waste aluminum-cased lithium-ion battery, using a 50Ah aluminum-cased ternary lithium battery with a pre-discharge voltage of 4.07V, is described below:

[0046] (1) Use a flathead screwdriver to destroy the explosion-proof valve of the aluminum-cased battery;

[0047] (2) Immerse the aluminum-cased battery after the explosion-proof valve is damaged into tap water. The mass ratio of water to battery is 3:1, and the battery is immersed to a depth of 30cm.

[0048] (3) After discharging for 0.5 hours, remove the battery that is not fully discharged from the water. The negative electrode of the battery continues to react with the water and release heat. After 18 hours, use the heat generated by the reaction between the negative electrode of the battery and the water to evaporate the water inside the battery.

[0049] Ten groups of aluminum-cased batteries were discharged using the same method. The voltage after discharge was measured using a multimeter. The batteries were dried at 120°C under normal pressure to measure moisture content. The test data are shown in Table 2.

[0050] Table 2 Voltage of aluminum-cased batteries before and after discharge and moisture content after self-heating drying

[0051]

[0052] As shown in Table 2, the discharge method of this invention for aluminum-cased batteries exhibits high discharge efficiency, with the voltage approaching zero after discharge, ensuring complete discharge. Furthermore, the batteries are retrieved before the negative electrode has fully reacted, allowing for efficient self-heating drying using the battery's energy. This results in a post-discharge moisture content of less than 5%, saving on drying costs. No corrosion is observed on the battery surface, aluminum loss is minimal, and the recycling rate of used batteries can be improved.

[0053] Comparative Example 1

[0054] Five sets of 32Ah soft-pack ternary lithium batteries (with a voltage of 4.15V before discharge) were soaked in pure water for 3 hours, then removed from the water and left for 12 hours. The residual voltage was measured to be 3.5-4.1V. This indicates that the present invention, which pre-treats the batteries by cutting them open before immersing them in water, can significantly improve the discharge efficiency and make the discharge more complete.

[0055] Comparative Example 2

[0056] Five sets of 32Ah soft-pack ternary lithium batteries (with a voltage of 4.15V before discharge) were taken, pretreated, and then immersed in pure water for 24 hours. After soaking, they were taken out and left for another 12 hours. The water content was found to be more than 5%. This shows that by controlling the soaking time and using the remaining battery energy for self-heating drying, the present invention can significantly reduce the water content of the battery after discharge, thereby saving subsequent drying costs.

[0057] It should be noted that all the above embodiments belong to the same inventive concept, and the descriptions of each embodiment have different focuses. Where the description in a particular embodiment is not detailed, please refer to the description in other embodiments.

[0058] The embodiments described above are merely illustrative of implementation methods of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for discharging spent lithium-ion batteries, characterized in that, Includes the following steps: S1. Pre-treatment of waste lithium-ion batteries; the waste lithium-ion batteries include pouch batteries and aluminum-cased batteries; The method for pre-processing the waste lithium-ion batteries is as follows: when the waste lithium-ion batteries are pouch batteries, the pouch batteries are cut open along the direction of the battery tabs, and the length of the cut is 1 / 2 to 2 / 3 of the length of the pouch batteries. When the waste lithium-ion battery is an aluminum-cased battery, the explosion-proof valve of the aluminum-cased battery is damaged; S2. Immerse the pretreated waste lithium-ion batteries in water; S3. Control the discharge reaction time to 0.5-3h, remove the waste lithium-ion battery from the water, and use the remaining battery energy for self-heating drying to obtain a fully discharged lithium-ion battery; the self-heating drying time is 5-24h, and the water content of the waste lithium-ion battery is less than 5% after drying.

2. The method for discharging spent lithium-ion batteries according to claim 1, characterized in that, The water used to soak the waste lithium-ion batteries in step S2 is tap water or purified water.

3. The method for discharging spent lithium-ion batteries according to claim 1, characterized in that, The mass ratio of water to waste lithium-ion batteries in step S2 is 4:1 to 3:

1.

4. The method for discharging spent lithium-ion batteries according to claim 1, characterized in that, The immersion depth of the waste lithium-ion battery in step S2 is greater than 20cm.

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