Method for Removing Electrolyte from Used Lithium-Ion Batteries and Disposing of Them Safely
A simple, environmentally friendly method using physical processes effectively recovers valuable components from used lithium-ion batteries by shredding, heating, and filtration, addressing the complexity and environmental risks of existing methods.
Patent Information
- Application Number
- JP2024565105
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-05-05
- Filing Date
- 2023-05-05
- Publication Date
- 2025-07-01
AI Technical Summary
Existing methods for removing and disposing of electrolytes from used lithium-ion batteries are complex, require sophisticated equipment, and pose environmental risks due to the use of harsh chemicals, failing to provide a simple, environmentally friendly, and commercially viable solution.
A method involving physical processes such as shredding in water, heating, stirring, precipitation, and filtration is employed to remove electrolytes, utilizing water and precipitants like lime and trisodium phosphate to recover valuable components like lithium phosphate and trisodium phosphate crystals.
Achieves high recovery rates of 99.7% for fluorine, 63.4% for lithium, and 75.5% for phosphorus, with minimal environmental impact, ensuring safe disposal and resource recovery.
Smart Images
Figure 2025520016000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to removing and disposing of electrolytes from used lithium-ion batteries. More specifically, the present invention relates to an environmentally friendly method for removing electrolytes from all types of used lithium-ion batteries in a commercially feasible manner and disposing of them safely.
Background Art
[0002] Lithium-ion batteries (LIBs) are widely used worldwide as important energy storage and conversion devices for powering portable electronic devices and electric vehicles due to their high voltage, high energy density, high specific energy, small size, good capacity retention, low self-discharge rate, zero memory effect, wide operating temperature range, and long life cycle. Therefore, LIBs are applied to a wide range of uses such as notebook computers, video cameras, mobile phones, electric vehicles, and other portable electronic devices and biometric devices.
[0003] Batteries have a lifespan, which is not very long. Currently, the average lifespan of LIBs ranges from 1 to 3 years depending on the technology used. Used LIBs are classified as non-environmentally compliant or non-environmentally friendly waste. If the battery contains toxic and flammable elements and compounds, improper disposal can pose a danger to the environment and cause serious problems.
[0004] It is predicted that the amount of discarded LIBs will increase in the coming years with the market expansion and productivity improvement of LIBs. As the pressure on the environmental impact of solid waste disposal increases and the need for disposal of corresponding hazardous metals grows, the recovery of used lithium-ion batteries (LIBs) has attracted worldwide attention in recent years. In this regard, many efforts have been made in the past few decades, and several new, interesting, and unique methods for recycling cathodes, anodes, and electrolytes have been developed.
[0005] Recycling may be a promising strategy in the future because of the high demand for valuable products and is beneficial both economically and environmentally. Recycling has several advantages, such as reducing environmental toxicity caused by the production of raw materials and reducing the extraction of natural resources.
[0006] The main issue regarding the improper treatment of waste from used LIBs is the disposal of electrolytes. Since electrolytes are one of the main components of LIBs, they cannot be ignored. However, electrolytes containing various lithium salts and volatile organic compounds have an adverse impact on human health and the environment. Therefore, it is also important to focus on research related to the extraction of electrolytes to prevent the serious threats posed by the toxicity, flammability, volatility, and harmful compounds of electrolytes. In recent years, researchers have paid a lot of attention to the recycling of electrolytes. Multiple researchers have adopted various techniques for the recycling of electrolytes, apart from solvent extraction, which is considered the first and most efficient method for recovering electrolytes.
[0007] International Publication No. WO2014 / 155784 discloses a method for treating a fluorine-containing electrolyte solution, which includes a vaporization step of heating the electrolyte solution containing a fluorine compound under reduced pressure to vaporize the volatile components of the electrolyte solution, a fluorine fixation step of reacting the fluorine component contained in the vaporized gas with calcium to fix it as calcium fluoride, and recovering the organic solvent component.
[0008] Japanese Patent No. 3257774 discloses a method for treating an organic electrolyte solution containing lithium hexafluorophosphate, and relates to a technique for industrially recycling the lithium hexafluorophosphate compound separated as hexafluorophosphate and lithium fluoride by using a solution containing primary, secondary, and tertiary alcohols and a reagent such as potassium fluoride or ammonium fluoride.
[0009] International Publication No. 2015 / 046218 discloses a method for treating a fluorine-containing electrolytic solution, which includes adding water to the fluorine-containing electrolytic solution, heating to vaporize volatile components, a vaporization step of recovering the gas generated by vaporization, and reacting fluorine contained in the gas or the condensate of the gas with calcium to fix it as calcium fluoride and recovering an organic solvent component.
[0010] Over the years, several other methods for removing and disposing of electrolytes have been reported, but none of the methods reported in those documents disclose methods that are easy to operate, do not use sophisticated equipment, and do not use harsh chemicals.
[0011] Therefore, there is a need for an approach to solve the state-of-the-art problem of providing a simple process for removing and safely disposing of electrolytes in a commercially viable manner without polluting / damaging the environment. The present invention is an attempt in that direction.
SUMMARY OF THE INVENTION
PROBLEMS TO BE SOLVED BY THE INVENTION
[0012] The main object of the present invention is to provide a method for removing and safely disposing of electrolytes from used lithium-ion batteries.
[0013] Another object of the present invention is to provide a method for removing and safely disposing of electrolytes from all types of used lithium-ion batteries in a commercially viable manner.
[0014] Yet another object of the present invention is to provide a method that is easy to operate and easy to scale up.
[0015] Yet another object of the present invention is to provide a method that does not require the use of sophisticated equipment.
[0016] Yet another object of the present invention is to provide a method that is simple, clean, green, and environmentally friendly.
Means for Solving the Problem
[0017] The present invention relates to a method for safely disposing of used lithium-ion batteries by removing electrolytes through physical processes such as heating, stirring, precipitation, and filtration.
[0018] In one embodiment, the present invention provides a method for removing electrolytes from used lithium-ion batteries and safely disposing of them, the method comprising the following steps: (a) A step of removing highly soluble electrolytes from used lithium-ion batteries, the removal being carried out while shredding in the presence of water to obtain an electrolyte solution; (b) A step of heating the electrolyte solution obtained in step (a) together with a precipitant suitable for fluoride precipitation in a sealed reactor at 100 rpm while stirring within a temperature range of 70 to 90 °C for a predetermined time to obtain a first slurry; (c) A step of filtering the first slurry obtained in step (b) and separately collecting both the precipitate mass (cake) and the filtrate to analyze metal ions; (d) A step of analyzing the filtrate collected in step (c) to determine the concentrations of fluoride ions, lithium, and phosphorus; (e) A step of treating the analyzed filtrate in step (d) with activated carbon and then stirring at 90 to 100 °C for 3 to 4 hours together with trisodium phosphate (20% w / v), which is another precipitant, to obtain a second slurry; (f) A step of filtering the second slurry obtained in step (e) and separately collecting the lithium phosphate precipitate cake and the filtrate; (g) A step of washing and drying the lithium phosphate precipitate cake obtained in step (f) with warm water to obtain pure lithium phosphate; (h) A step of evaporating and crystallizing the filtrate obtained in step (f) to recover condensed water and trisodium phosphate crystals for reuse.
[0019] The present invention relates to an environmentally friendly method for removing electrolytes from all types of used lithium-ion batteries in a commercially feasible manner and safely disposing of them.
[0020] The above objects and advantages of the present invention will become apparent from the following brief description of the drawings, the detailed description of the present invention, and the appended claims.
[0021] A method for removing electrolytes from used lithium-ion batteries and disposing of them safely can be understood by referring to the following drawings.
Brief Description of the Drawings
[0022]
Figure 1
Embodiments for Carrying Out the Invention
[0023] The present invention will be described below with reference to the accompanying drawings showing preferred embodiments of the present invention. However, the present invention can be implemented in many different forms and should not be construed as being limited to the embodiments described herein. Rather, the embodiments are provided so that this disclosure will be thorough and will fully convey the scope of the present invention to those skilled in the art.
[0024] The present invention will be described below with reference to the detailed description. The detailed description shows some, but not all, of the embodiments of the present invention. In fact, the present invention can be implemented in many different forms and should not be construed as being limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure meets the legal requirements to which it is applicable. Throughout, like numbers refer to like elements. The present invention is fully described herein using non-limiting embodiments and exemplary experiments.
[0025] The present invention relates to a method for removing electrolytes from used lithium-ion batteries and disposing of them safely by physical processes such as heating, stirring, precipitation, and filtration.
[0026] In a preferred embodiment, the present invention provides a method for removing an electrolyte from a used lithium-ion battery and disposing of it safely, the method comprising the following steps: (a) A step of removing a highly soluble electrolyte from a used lithium-ion battery, the removal being carried out while cutting it into pieces in the presence of water to obtain an electrolytic solution; (b) A step of heating the electrolytic solution of step (a) in a sealed reactor at 100 rpm while stirring with a precipitant suitable for fluoride precipitation in a temperature range of 70 to 90 °C for a predetermined time to obtain a first slurry; (c) A step of filtering the first slurry obtained in step (b) and separately collecting both the precipitate mass (cake) and the filtrate to analyze metal ions; (d) A step of analyzing the filtrate collected in step (c) to determine the concentrations of fluoride ions, lithium, and phosphorus; (e) A step of treating the analyzed filtrate of step (d) with activated carbon and then stirring it at 90 to 100 °C for 3 to 4 hours with trisodium phosphate (20% w / v) to obtain a second slurry; (f) A step of filtering the second slurry of step (e) and separately collecting the precipitate cake of lithium phosphate and the filtrate; (g) A step of washing and drying the precipitate cake of lithium phosphate of step (f) with warm water to obtain pure lithium phosphate; (h) A step of evaporating and crystallizing the filtrate of step (f) to recover and reuse the condensed water and trisodium phosphate crystals.
[0027] Furthermore, the precipitate mass of step (c) is dried overnight in a temperature range of 60 to 90 °C, and the dried precipitate mass is analyzed to determine the fluoride precipitation efficiency.
[0028] Here, the electrolyte in step (a) is lithium hexafluorophosphate (LiPF6), the predetermined time in step (b) is 3 to 5 hours, and the appropriate precipitant in step (b) is 50% w / v lime. To maintain a high temperature, a sealed fiber-reinforced plastic (FRP) reactor is used. The analyzed filtrate in step (d) has a lithium concentration of 2.23 g / L and a phosphorus concentration of 11.88 g / L, and contains only 18 ppm of fluoride ions. The condensed water and trisodium phosphate crystals recovered in step (h) are reused in this method.
[0029] The precipitation efficiency of fluoride in step (i) is 99.4%. The lithium phosphate precipitation cake in step (g) has a precipitation efficiency of 58.2% for Li and 66.8% for P.
[0030] The method of the present invention recovers 99.7% of fluorine (F), 63.4% of lithium (Li), and 75.5% of phosphorus (P) from the lithium hexafluorophosphate electrolyte of used lithium-ion batteries.
[0031] Figure 1 shows the process flow of waste electrolyte treatment, which shows a method of removing electrolytes from waste electrolytes of used lithium-ion batteries according to an embodiment of the present invention for safe disposal.
Example
[0032] [Example 1] Elemental analysis The elemental analysis of metals in the electrolyte was carried out using a microwave plasma atomic emission spectrometer (MP-AES), and the fluoride concentration in the solution was analyzed using ORION Dual Star (equipped with a fluoride electrode) at room temperature, i.e., 25°C. The analysis results show that P in the original solution is 98 g / L, Li is 11.5 g / L, and F is 46 g / L.
[0033] As shown in Table 1, lime was added to the electrolyte at a temperature of 25 °C in different stoichiometric ratios. The slurry was mixed for 2 hours while stirring at 400 rpm. Finally, the slurry was filtered using a Buchner funnel to separate the cake (precipitate mass) and the filtrate, and the filtrate was analyzed.
[0034] [Table 1]
[0035] [Example 2] Effect of Heat Treatment The effect of heat treatment on the release of fluoride ions from the electrolyte was investigated by changing the solution temperature to 90 °C for 5 hours. Temperature plays an important role in releasing fluoride ions from the LiPF6 compound, and an increase in the concentration of fluoride ions in the electrolyte was observed and analyzed by a fluoride electrode. The analysis results are summarized in Table 2, indicating a significant difference in fluoride ion concentration between the solution before and after heating.
[0036] [Table 2]
[0037] [Example 3] Precipitation Behavior 1.0 L of the original electrolyte was heated at 88 (±2) °C for 5 hours to completely release fluoride ions from the LiPF6 compound into the aqueous phase. After heat treatment, the final solution was cooled to room temperature and analyzed. The concentrations were found to be P = 110 g / L, Li = 12.1 g / L, and F = 132 g / L. Then, four times the stoichiometric requirement of lime was added to the solution at room temperature for 3 hours. Finally, the slurry was filtered and both the filtrate and the precipitate were analyzed. Details are as shown in Table 3. Approximately 99.4% of fluoride, 58.2% of Li, and 66.8% of P also co-precipitated, but 18 ppm of F, 2.23 g / L of Li, and 11.88 g / L of P remained in the filtrate. Thus, the filtrate can be safely disposed of or further used to recover valuable lithium and phosphorus.
[0038] [Table 3]
[0039] [Example 4] Experiment
[0040] <Batch 1> In Batch 1, 200 ml of waste electrolyte was stirred with 150 ml of lime slurry (50% w / v) at 70 °C for 3 hours. The slurry was cooled and filtered. The filtrate (230 ml) and the cake (140 g) were collected. Filtrate 1 (230 ml) was passed through a carbon column containing 100 g of activated carbon (iodine value > 900 mg / kg) and then further collected for lithium recovery. Lithium recovery was carried out by stirring the liquid with 100 ml of sodium phosphate solution (20% w / v) at 90 °C for 3 hours. The slurry was filtered, the cake was washed with warm water and then dried to obtain pure lithium phosphate (12 g). The analysis of the samples, namely the waste electrolyte, Filtrate 1, the cake, and lithium phosphate, was performed for Li, P, and Ca using MP-AES (microwave plasma atomic emission spectrometer), and F was measured using an ion-selective electrode and is shown in Table 4.
[0041]
Table 4
[0042] <Batch 2> In Batch 2, 2 L of spent electrolyte was stirred with 1.48 L of lime slurry (50% w / v) at 70 °C for 3 hours. The slurry was cooled and filtered. The filtrate (2.21 L) and the cake (1.38 kg) were collected. Filtrate 1 (2.21 L) was passed through a carbon column containing 1 kg of activated carbon (iodine value > 900 mg / kg) and then further collected for lithium recovery. Lithium recovery was carried out by stirring the liquid with 1 L of sodium phosphate solution (20% w / v) at 90 °C for 3 hours. The slurry was filtered, and the cake was washed with warm water and then dried to obtain pure lithium phosphate (118 g). The analysis of the samples, namely the spent electrolyte, Filtrate 1, the cake, and lithium phosphate, was performed for Li, P, and Ca using MP-AES (microwave plasma atomic emission spectrometer), and F was measured using an ion-selective electrode and is shown in Table 5.
[0043]
Table 5
[0044] Therefore, the present invention provides a method for removing electrolytes from all types of used lithium-ion batteries in a commercially feasible manner for safe disposal. The environmentally friendly method of the present invention achieves high recovery rates of 99.7%, 63.4%, and 75.5% for fluorine (F), lithium (Li), and phosphorus (P), respectively.
[0045] Many modifications and other embodiments of the invention described herein will come to mind to those skilled in the art to which this invention pertains, benefiting from the teachings presented in the foregoing description and the related drawings. Accordingly, it is to be understood that the invention is not to be limited to the specific embodiments disclosed, but that modifications and other embodiments are intended to be included within the scope of the appended claims. Specific terms are used herein, but they are used in a general descriptive sense only and not for purposes of limitation.
Claims
1. A method for safely disposing of a used lithium-ion battery by removing the electrolyte therefrom, the method comprising the following steps: (a) A step of removing a highly soluble electrolyte from a used lithium-ion battery, the removal being carried out while shredding in the presence of water to obtain an electrolytic solution; (b) A step of heating the electrolytic solution obtained in step (a) in a sealed reactor at a temperature range of 70 to 90 °C for a predetermined time while stirring at 100 rpm together with a precipitant suitable for fluoride precipitation to obtain a first slurry; (c) A step of filtering the first slurry obtained in step (b) and separately collecting both the precipitate mass (cake) and the filtrate to analyze metal ions; (d) A step of analyzing the filtrate collected in step (c) to determine the concentrations of fluoride ions, lithium, and phosphorus; (e) A step of treating the analyzed filtrate of step (d) with activated carbon and then stirring at 90 to 100 °C for 3 to 4 hours together with trisodium phosphate (20% w / v), which is another precipitant, to obtain a second slurry; (f) A step of filtering the second slurry of step (e) and separately collecting the lithium phosphate precipitate cake and the filtrate; (g) A step of washing and drying the lithium phosphate precipitate cake of step (f) with warm water to obtain pure lithium phosphate; (h) A step of evaporating and crystallizing the filtrate of step (f) to recover and reuse the condensed water and trisodium phosphate crystals.
2. A method for removing an electrolyte from a used lithium-ion battery according to claim 1, wherein the electrolyte in step (a) is lithium hexafluorophosphate (LiPF ６ 6), and disposing of it safely.
3. The method for safely disposing of a used lithium-ion battery by removing the electrolyte therefrom according to Claim 1, wherein the predetermined time in step (b) is 3 to 5 hours.
4. The method for safely disposing of a used lithium-ion battery by removing the electrolyte therefrom according to Claim 1, wherein the suitable precipitant in step (b) is 50% w / v lime.
5. The method for safely disposing of a used lithium-ion battery by removing the electrolyte therefrom according to Claim 1, wherein the analyzed filtrate of step (d) has a lithium concentration of 2.23 g / L and a phosphorus concentration of 11.88 g / L, and contains only 18 ppm of fluoride ions.
6. The method for safely disposing of a used lithium-ion battery by removing the electrolyte therefrom according to Claim 1, wherein the lithium phosphate precipitate cake in step (g) has a precipitation efficiency of 58.2% for Li and 66.8% for P.
7. The method for removing electrolyte from a used lithium-ion battery according to claim 1 and safely disposing of it, wherein the condensed water and trisodium phosphate crystals recovered in step (h) are reused.
8. The method for removing electrolyte from a used lithium-ion battery according to claim 1 and safely disposing of it, which recovers 99.7% of fluorine (F), 63.4% of lithium (Li), and 75.5% of phosphorus (P).