Discharging method for preventing electrolyte in cylindrical waste battery from leaking

Abstract

The invention provides a discharging method for preventing electrolyte in a cylindrical waste battery from leaking. The discharging method comprises the following steps: (1) heating a wrapping material to obtain a liquid-phase wrapping material; (2) coating the liquid wrapping material at the joint of the metal sheet at the positive pole lug of the cylindrical waste battery and the battery shell and the joint of the metal sheet at the negative pole lug of the cylindrical waste battery and the battery shell, standing and cooling; and (3) soaking the waste battery coated with the wrapping material into a discharge solution for discharging, taking out the waste battery, drying the surface of the waste battery, then testing the discharge voltage, and after determining that the waste battery is completely discharged, removing the wrapping material on the waste battery, and screening and recycling the waste battery. According to the discharge method provided by the invention, excellent properties of coating materials such as paraffin and the like are fully utilized, pollution of electrolyte seepage to the discharge solution in the discharge process is effectively prevented, and meanwhile, subsequent pollution control is also reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of battery recycling, and in particular to a discharge method for preventing leakage of electrolyte inside cylindrical waste batteries. Background Art

[0002] With the advancement of technology and living standards, electronic products have become an integral part of our lives. Portable cylindrical batteries are the most common energy storage devices. While these batteries bring convenience, they contain large amounts of toxic electrolytes and positive and negative metals, which can cause irreversible damage to various organisms if they enter soil and water. Therefore, the efficient and effective disposal and recycling of waste batteries is a major challenge facing society.

[0003] Battery discharge is an essential step in the recycling of waste batteries. Incompletely discharged batteries can easily cause serious production accidents during disassembly. Currently, the method for discharging waste batteries is typically to immerse them in a saline solution. However, during the discharge process, the discharge solution can easily corrode the positive and negative electrodes, causing electrolyte loss. Improper post-processing of electrolyte leakage can have serious environmental impacts and hinder subsequent electrolyte storage. Summary of the Invention

[0004] In order to solve the above-mentioned problems, the object of the present invention is to provide a method for discharging waste batteries that can effectively prevent the contamination of the discharge solution by electrolyte leakage during the discharge process, while reducing subsequent pollution control.

[0005] In order to achieve the purpose of the present invention, the present invention adopts the following technical solutions:

[0006] The present invention provides a discharge method for preventing leakage of electrolyte inside cylindrical waste batteries, comprising:

[0007] (1) heating the wrapping material to obtain a liquid phase wrapping material;

[0008] (2) coating the liquid coating material on the connection between the metal sheet at the positive electrode tab and the battery shell, and on the connection between the metal sheet at the negative electrode tab and the battery shell of the cylindrical waste battery, and allowing to cool;

[0009] (3) Immerse the waste battery coated with the wrapping material in a discharge solution for discharge, take out the waste battery, dry its surface, and then test the discharge voltage. After confirming that the waste battery is completely discharged, remove the wrapping material on the waste battery and screen and recycle the waste battery.

[0010] In some embodiments, the wrapping material in step (1) is selected from natural paraffin, polyethylene or polypropylene;

[0011] Preferably natural paraffin wax.

[0012] In some embodiments, the temperature for heating the wrapping material is controlled at 70 - 150°C.

[0013] Preferably, a water bath heating method is adopted.

[0014] In some embodiments, in step (2), the waste battery is selected from retired batteries that have reached the end of their service life and have no obvious damage on the appearance.

[0015] In some embodiments, the coating thickness of the liquid wrapping material is not less than 2 mm, preferably 0.3 - 0.5 cm.

[0016] In some embodiments, in step (2), an air cooling method or natural cooling is adopted to cool the liquid wrapping material to 20 - 30°C.

[0017] Preferably, the wind speed is controlled at 0.5 - 4 m / s during the cooling process.

[0018] In some embodiments, in step (3), the temperature for discharging and soaking the waste battery coated with the wrapping material is 20 - 40°C, and the discharging time is not less than 60 min.

[0019] In some embodiments, the discharging solution is selected from salt solutions, preferably an aqueous sodium chloride solution.

[0020] In some embodiments, the surface of the taken - out waste battery is dried by wiping or hot - air drying.

[0021] Preferably, the temperature for hot - air drying is 80 - 120°C, and the time is 30 - 40 min.

[0022] In some embodiments, the wrapping material on the waste battery is removed by heating.

[0023] Preferably, the heating temperature is above 70°C.

[0024] The technical solution provided by the present invention has the following beneficial effects:

[0025] The discharging method provided by the present invention coats the wrapping material at the connection between the metal sheet and the battery case at the ear. By making full use of the excellent properties of coating materials such as paraffin wax, on the basis of ensuring the full discharge of the waste battery, it effectively prevents the electrolyte from seeping out during the discharging process and polluting the discharging solution, and at the same time reduces the subsequent pollution control. Specific embodiments

[0026] The following details the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only for explaining and illustrating the present invention, and are not used to limit the present invention.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The term "and / or" as used herein may include any and all combinations of one or more of the related listed items.

[0028] The present invention provides a discharging method for preventing internal electrolyte leakage of cylindrical waste batteries, comprising:

[0029] (1) Heating the wrapping material to obtain a liquid-phase wrapping material;

[0030] (2) Coating the liquid wrapping material at the connection between the metal sheet at the positive electrode tab of the cylindrical waste battery and the battery housing and at the connection between the metal sheet at the negative electrode tab and the battery housing, and allowing it to stand and cool;

[0031] (3) Immersing the waste battery coated with the wrapping material in a discharging solution for discharging, taking out the waste battery, drying its surface, testing the discharging voltage, and after confirming that the waste battery is completely discharged, removing the wrapping material on the waste battery and screening and recycling the waste battery.

[0032] The wrapping material selected in step (1) of the method of the present invention may be natural paraffin, polyethylene or polypropylene; materials such as paraffin have the advantages of low melting point, insulation, stable chemical properties, low price, etc., and can be used as the coating material at the connection between the metal at the electrode tab of the waste battery and the housing, and precisely isolate the positive and negative electrode gaps from the contact with the discharging salt solution by using materials such as paraffin, so that the electrolyte in the waste battery does not leak during the discharging process.

[0033] In some specific embodiments, the solid wrapping material paraffin is placed in a beaker and heated in a water bath to liquid paraffin, and the paraffin is evenly applied to the connections between the metal sheet at the positive electrode tab of the battery and the battery housing and between the metal sheet at the negative electrode tab and the battery housing by using a dropper, and allowed to stand for a period of time to cool and solidify the paraffin.

[0034] In some preferred embodiments, the wrapping material is natural paraffin.

[0035] The temperature for heating the wrapping material in the method of the present invention is controlled at 70 - 150 °C; preferably, the wrapping material can be heated by means of water bath heating.

[0036] In step (2) of the method of the present invention, the waste battery is selected from retired cylindrical batteries that have reached the end of their service life and have no obvious damage on the appearance. The waste batteries in the present invention include but are not limited to 18650 model batteries.

[0037] In some specific embodiments, the thickness of the liquid wrapping material coated at the connection between the metal sheet at the tab and the battery housing is not less than 2 mm; preferably, the coating thickness is between 0.3 and 0.5 cm, for example, 0.3 cm, 0.4 cm.

[0038] In step (2) of the method of the present invention, the liquid wrapping material is cooled to between 20 and 30 °C by an air-cooling method so that the coating material solidifies at the connection between the metal sheet at the tab and the battery housing; preferably, the air velocity of the cold air is controlled to be 0.5 to 4 m / s during the cooling process, for example, 1 m / s, 2 m / s, 3 m / s.

[0039] In step (3) of the method of the present invention, the waste battery coated with the wrapping material is immersed in the discharge solution for discharging. Specifically, the temperature of the battery immersion is 20 to 40 °C, for example, 25 °C, 30 °C, 35 °C; the discharging time is not less than 60 min, preferably 90 to 120 min, for example, 100 min, 110 min.

[0040] In some specific embodiments, the discharge solution in the method of the present invention is selected from salt solutions, such as aqueous sodium chloride solution, aqueous potassium chloride solution; preferably, it is aqueous sodium chloride solution, and the specific concentration can be 4 to 8 mol / L.

[0041] In the discharging method of the present invention, after discharging is completed, the waste battery is taken out of the discharge solution, and the residual discharge solution on the surface of the waste battery is wiped dry or dried by hot air, preferably by hot air drying; specifically, the temperature of the hot air drying is 80 to 120 °C, for example, 90 °C, 100 °C, 110 °C, and the time is 30 to 40 min, for example, 35 min.

[0042] In some specific embodiments, a voltmeter is used to measure the remaining voltage of each waste battery. The voltage of the waste battery is measured at least three times, the voltmeter readings are recorded, and the average value of the readings is taken; when the remaining voltage shows between 0 and 0.1 V, it is considered that the battery is fully discharged.

[0043] The discharging method of the present invention uses a heating method to remove the wrapping material coated on the waste battery. Specifically, the wrapping material can be melted by heating to be removed, and the melted wrapping material can be reused; more specifically, the heating temperature can be above 70 °C, preferably 70 to 100 °C, for example, 80 °C, 85 °C, 90 °C.

[0044] The following further illustrates the solution of the present invention through specific examples, but it should not be understood that the present invention is only limited thereto.

[0045] Where specific experimental steps or conditions are not specified in the examples, the operations or conditions of the corresponding conventional experimental steps in this technical field can be followed. For reagents without indicating the manufacturer, they are all conventional reagents available in this field.

[0046] The following examples use the following method to test the content of fluoride ions (F - ) in the discharge solution: Inductively coupled plasma mass spectrometry (ICP-MS) is a commonly used technique for detecting the content of fluoride ions in water bodies.

[0047] Example 1

[0048] (1) Melt paraffin into a liquid under the condition of water bath heating at 80 °C.

[0049] (2) Select used Nanfu waste batteries, and use a dropper to evenly coat 0.4 cm of liquid paraffin at the joints of the metal sheets and the battery housings at the positive and negative electrode tabs of the battery, and control the wind speed at 1.5 m / s for air cooling until the paraffin solidifies.

[0050] (3) Immerse the waste battery coated with paraffin (battery voltage 1.02 V) into 200 mL of 6 mol / L potassium chloride aqueous solution for discharging, and the discharging reaction occurs at room temperature for 48 h. After discharging, take out the waste battery and dry its surface with hot air at 80 °C, and test the voltage after discharging to be 0 V.

[0051] Remove the paraffin material on the above waste battery and screen and recycle the waste battery.

[0052] Example 2

[0053] (1) Melt paraffin into a liquid under the condition of water bath heating at 85 °C.

[0054] (2) Select used Nanfu waste batteries, and use a dropper to evenly coat 0.4 cm of liquid paraffin at the joints of the metal sheets and the battery housings at the positive and negative electrode tabs of the battery, and control the wind speed at 1.5 m / s for air cooling until the paraffin solidifies.

[0055] (3) Immerse the waste battery coated with paraffin (battery voltage 1.21 V) into 200 mL of 4 mol / L sodium chloride aqueous solution for discharging, and the discharging reaction occurs at room temperature for 40 h. After discharging, take out the waste battery and dry its surface with hot air at 80 °C, and test the voltage after discharging to be 0 V.

[0056] Remove the paraffin material on the above waste battery and screen and recycle the waste battery.

[0057] Example 3

[0058] (1) Melt the paraffin into a liquid under the condition of heating in a water bath at 80 °C;

[0059] (2) Select the used columnar waste battery disassembled from an electric vehicle, and evenly coat 0.4 cm of liquid paraffin at the joints of the metal sheet at the positive electrode tab and the battery case, and the metal sheet at the negative electrode tab and the battery case with a dropper. Control the wind speed at 1.5 m / s and cool it by air cooling until the paraffin solidifies;

[0060] (3) Immerse the waste battery coated with paraffin (battery voltage 0.72 V) into 200 mL of 6 mol / L sodium chloride aqueous solution for discharging. The discharging reaction occurs at room temperature for 30 h. After the discharging is completed, take out the waste battery and dry its surface with hot air at 80 °C. The voltage after discharging is measured to be 0.1 V.

[0061] Remove the paraffin material on the above waste battery and screen and recycle the waste battery.

[0062] Example 4

[0063] (1) Melt the polyethylene into a liquid under the condition of heating in a water bath at 100 °C;

[0064] (2) Select the used NANFU waste battery, and evenly coat 0.4 cm of liquid polyethylene at the joints of the metal sheet at the positive electrode tab and the battery case, and the metal sheet at the negative electrode tab and the battery case with a dropper. Control the wind speed at 1.5 m / s and cool it by air cooling until the surface of the polyethylene solidifies;

[0065] (3) Immerse the waste battery coated with polyethylene (battery voltage 0.75 V) into 200 mL of 4 mol / L sodium chloride aqueous solution for discharging. The discharging reaction occurs at room temperature for 40 h. After the discharging is completed, take out the waste battery and dry its surface with hot air at 80 °C. The voltage after discharging is measured to be 0.1 V.

[0066] Remove the polyethylene material on the above waste battery and screen and recycle the waste battery.

[0067] Example 5

[0068] (1) Melt the polypropylene into a liquid under the condition of heating at 160 °C;

[0069] (2) Select the used NANFU waste battery, and evenly coat 0.4 cm of liquid polypropylene at the joints of the metal sheet at the positive electrode tab and the battery case, and the metal sheet at the negative electrode tab and the battery case with a dropper. Control the wind speed at 1.5 m / s and cool it by air cooling until the polypropylene solidifies;

[0070] (3) A waste battery coated with polypropylene (battery voltage 1.15 V) was immersed in 200 mL of a 4 mol / L sodium chloride aqueous solution and discharged. The discharge reaction was allowed to proceed at room temperature for 40 h. After the discharge, the waste battery was removed and its surface was dried with hot air at 80°C. The post-discharge voltage was tested to be 0.1 V.

[0071] The polypropylene material on the waste batteries is removed and the waste batteries are screened and recycled.

[0072] Comparative Example 1

[0073] Discharging was performed according to the method of Example 2, except that paraffin was not coated on the connection between the metal sheet at the tab and the battery casing, and the voltage of the waste battery before discharge was 0.98V.

[0074] Comparative Example 2

[0075] Discharging was performed according to the method of Example 2, except that water was used as the discharging solution, and the voltage of the waste battery before discharge was 1.21V, and the voltage of the battery after discharge was 1.21V.

[0076] Comparative Example 3

[0077] Discharging was performed according to the method of Example 2, except that in step (2), the outer wall of the waste battery was completely coated with liquid paraffin, and the voltage of the waste battery before discharge was 0.73 V, and the voltage of the waste battery after discharge was 0.73 V.

[0078] Comparative Example 4

[0079] (1) Melt the paraffin into liquid in a water bath at 85°C;

[0080] (2) Select used Nanfu waste batteries and use a rubber-tipped dropper to evenly apply 0.4 cm of liquid paraffin on the connection between the metal sheet at the positive electrode tab and the battery shell, and the metal sheet at the negative electrode tab and the battery shell. Control the wind speed to 1.5 m / s and cool it in an air-cooling manner until the paraffin solidifies.

[0081] (3) A waste battery coated with paraffin (battery voltage 0.58 V) was immersed in 200 mL of a 4 mol / L sodium chloride aqueous solution and discharged. The discharge reaction was carried out at 60°C for 40 h. After the discharge, the waste battery was removed and its surface was dried with hot air at 80°C. The post-discharge voltage was 0 V.

[0082] The paraffin material on the waste batteries is removed and the waste batteries are screened and recycled.

[0083] The discharge solution in the above example was tested, and the test results are as follows:

[0084]

[0085] As can be seen from the data in the above table, the discharging method provided by the present invention can effectively prevent the pollution of the discharging solution caused by the leakage of the electrolyte during the discharging process while ensuring the complete discharging of the waste battery, and minimizes the subsequent pollution control.

Claims

1. A discharging method for preventing internal electrolyte leakage of cylindrical waste batteries, characterized in that, Including: (1) Heating the wrapping material to obtain a liquid-phase wrapping material; (2) Coating the liquid wrapping material at the connection between the metal sheet at the positive electrode tab of the cylindrical waste battery and the battery case and at the connection between the metal sheet at the negative electrode tab and the battery case, and allowing it to stand and cool; (3) Immersing the waste battery coated with the wrapping material in a discharge solution for discharging, taking out the waste battery, drying its surface, testing the discharge voltage, and after confirming that the waste battery is completely discharged, removing the wrapping material on the waste battery and screening and recycling the waste battery.

2. The discharging method according to claim 1, wherein In step (1), the wrapping material is selected from natural paraffin, polyethylene or polypropylene; Preferably natural paraffin.

3. The discharging method according to claim 2, wherein The temperature for heating the wrapping material is controlled at 70 - 150 °C; Preferably, a water bath heating method is adopted.

4. The discharging method according to any one of claims 1 to 3, characterized in that, In step (2), the waste battery is selected from retired batteries that have reached the end of their service life and have no obvious damage on the appearance.

5. The discharging method according to claim 4, wherein The coating thickness of the liquid wrapping material is not less than 2 mm, preferably 0.3 - 0.5 cm.

6. The discharging method according to claim 5, characterized in that, In step (2), the liquid wrapping material is cooled to 20 - 30 °C by an air-cooling method; Preferably, the wind speed is controlled at 0.5 - 4 m / s during the cooling process.

7. The discharging method according to any one of claims 1 to 6, characterized in that In step (3), the discharging immersion temperature of the waste battery coated with the wrapping material is 20 - 40 °C, and the discharging time is not less than 60 min.

8. The discharge method according to claim 7, characterized in that The discharge solution is selected from salt solutions, preferably an aqueous sodium chloride solution.

9. The discharging method according to claim 8, wherein The surface of the taken-out waste battery is dried by wiping or hot air drying; Preferably, the temperature of hot air drying is 80 - 120 °C, and the time is 30 - 40 min.

10. The discharging method according to claim 9, characterized in that, The wrapping material on the waste battery is removed by heating; Preferably, the heating temperature is above 70 °C.

Images