A method for extracting effective components in pericarp and recovering Li in positive electrode material of waste lithium battery through synergistic wet mechanical activation

Abstract

The application discloses a method for extracting effective components in peels, synergistically wet-mechanical activation and recycling Li in positive electrode materials of waste lithium batteries. The method uses cheap and easily available ethanol aqueous solution as an extracting agent, extracts effective components in peel waste by using an ultrasonic method, strengthens the extraction rate of organic acids, total phenols, total flavonoids and other antioxidant components in the peels by using a microwave method, and co-ball-mills the positive electrode battery powder and the peel extracting solution by using a wet-mechanical activation method to recycle Li elements. The ethanol aqueous solution used in the application is non-toxic and environment-friendly, the ultrasonic-microwave extraction synergistically wet-mechanical activation realizes efficient recycling of Li in the positive electrode materials of the waste lithium ion batteries. The recycling method is green, environment-friendly, economic, efficient and simple in process, and meets the requirements of industrial application of the recycling industry of the positive electrode materials of the waste lithium ion batteries.

Description

Technical Field

[0001] This invention belongs to the field of electronic waste resource utilization technology, and relates to a method for extracting effective components from fruit peels and synergistically recovering Li from waste lithium battery cathode materials using wet mechanical activation. Background Technology

[0002] In recent years, lithium-ion batteries have rapidly captured a significant share of the battery market due to their advantages such as high specific capacity, excellent rate performance, and long cycle life, resulting in explosive growth. However, the widespread use of lithium-ion batteries has led to the generation of a large number of waste lithium-ion batteries. These waste lithium-ion batteries contain various valuable metals such as Li, Ni, Co, and Mn. The large-scale production of lithium-ion batteries is gradually depleting these metal resources, which seriously affects the sustainable development of the lithium-ion battery industry.

[0003] Currently, commonly used methods for recycling cathode materials from spent lithium-ion batteries include pyrometallurgical and hydrometallurgical processes. Hydrometallurgical recycling includes acid leaching, ammonia leaching, biological methods, and eutectic solvent methods. Pyrometallurgical recycling is a relatively mature process due to its simple operation, short process, and large processing capacity; however, it suffers from drawbacks such as high energy consumption and the generation of secondary pollutants. Compared to pyrometallurgical processes, hydrometallurgical recycling is more widely used, offers higher recovery rates and purity, and has lower equipment investment costs.

[0004] Eutectic solvents (DESs) possess high thermal stability, non-flammability, designability, and the ability to dissolve organic and inorganic compounds, and are increasingly being used in wet recycling processes for spent lithium-ion batteries. The patent "A Method for Recovering Valuable Metals from Cathode Materials of Waste Lithium-ion Batteries" (Xiang Xu et al., CN115369250A) discloses a eutectic solvent system for recovering cathode materials. This system involves mixing choline chloride with one or more of L-ascorbic acid, benzenesulfonic acid, citric acid, and glycolic acid, along with additives. The additives are one or more of glycine, alanine, and cysteine. The battery powder from the spent lithium-ion battery cathode material is mixed with the eutectic solvent system, and valuable metals are extracted stepwise using the leachate. This method uses additives that increase experimental costs. The recovery of metals from the leachate through chemical precipitation by adding precipitating reagents or multi-step solvent extraction leads to complex separation steps and the introduction of impurities. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to propose a method for the efficient recovery of Li from waste lithium-ion battery cathode materials by extracting effective components from fruit peels and synergistically employing wet mechanical activation. This invention avoids the use of acids, alkalis, and other harmful reagents, consumes little energy during the process, and is environmentally friendly, economical, efficient, and simple in process, meeting the requirements for industrial application in the waste lithium-ion battery cathode material recycling industry.

[0006] This invention fully utilizes the extraction of effective components from fruit peels using an ethanol-water solution. Waste lithium-ion battery cathode materials are then co-activated with the extract via wet mechanical processing, followed by solid-liquid separation to obtain a leachate and filter residue. This method enables the efficient recovery of valuable metal Li from lithium-ion battery cathode materials. The technical solution of this invention is described in detail below.

[0007] A method for extracting effective components from fruit peels and synergistically recovering Li from waste lithium battery cathode materials via wet mechanical activation involves first using an ethanol-water solution as an extractant to extract antioxidant components, including organic acids, total phenols, and total flavonoids, from the fruit peel waste. Then, the cathode battery powder and the fruit peel extract are wet mechanically activated in a ball mill. After ball milling, the leachate and filter residue are recovered. The specific steps are as follows:

[0008] (1) Dry, crush and sieve the fruit peel waste to obtain fruit peel powder A; weigh fruit peel powder A and ethanol aqueous solution and place them in a lidded conical flask, and use an ultrasonic cleaner to extract the extract to obtain extract B; wherein, the fruit peel waste is one or more of lychee peel, mango peel, apple peel and kiwi peel.

[0009] (2) Place extract B in a microwave instrument for microwave extraction for a period of time, and filter to obtain peel extract C;

[0010] (3) The fruit peel extract C was used as a leaching agent and waste lithium battery cathode powder was subjected to wet mechanical activation leaching in a planetary ball mill. After leaching, solid-liquid treatment was performed to obtain Li-rich material. + The metal salt leaching solution D contains aluminum powder, phosphorus iron slag, etc. For the metal leaching solution D, Li element can be purified and separated by methods such as precipitation, organic solvent extraction, ion exchange separation, electrochemical reduction, co-precipitation of separation and synthesis, and high-temperature calcination solid-phase recovery.

[0011] In this invention, in step (1), the fruit peel waste is passed through a 60-mesh sieve, the volume concentration of the ethanol aqueous solution is 30-70%, and the solid-liquid ratio of fruit peel powder A to the ethanol aqueous solution is 1:10-1:100 g / ml; preferably, the volume concentration of the ethanol aqueous solution is 50-70%, and the solid-liquid ratio of fruit peel powder A to the ethanol aqueous solution is 1:25-1:50 g / ml.

[0012] In this invention, in step (1), the ultrasonic power is 300-600W, the ultrasonic temperature is 30-70℃, and the ultrasonic time is 20-60min; preferably, the ultrasonic temperature is 50-70℃ and the ultrasonic time is 40-50min.

[0013] In this invention, in step (2), the microwave power is 500-800W, the microwave temperature is the same as the ultrasonic temperature set in step (1), and the microwave time is 3-7min; preferably, the microwave power is 500-600℃ and the microwave time is 3-5min.

[0014] In this invention, in step (3), the planetary ball mill speed is 300-700 rpm, the mechanical activation time is 30 min of ball milling, 15 min interval, and 4-8 cycles; preferably, the speed is 500-700 rpm.

[0015] In this invention, in step (3), the waste lithium battery cathode powder is one or more of lithium iron phosphate and lithium manganese oxide; the solid-liquid ratio of the waste lithium battery cathode powder to the extraction liquid C is 1:10-1:50 g / ml; preferably, 1:30-1:50 g / ml.

[0016] In summary, this invention utilizes an ethanol-water solution as the extractant and employs an ultrasound-microwave assisted method to extract natural products from fruit peels. Microwave-assisted extraction is a newly developed method for extracting phytochemicals in recent years. The oscillation and stirring effects of ultrasound effectively compensate for the uneven heat and mass transfer of microwaves. The excellent thermal effect of microwaves effectively compensates for the insufficient heat generation of ultrasound. Microwaves have stronger penetrating power than ultrasound, allowing for simultaneous, uniform, and rapid heating of the reactants both internally and externally. This results in short extraction time and high efficiency. Based on the different microwave absorption capabilities of substances with different structures, selective extraction of target components can be achieved, ensuring the full extraction of antioxidant components from the fruit peel. Furthermore, the fruit peel extract of this invention is fully contacted with the cathode material battery powder in a planetary ball mill. The mechanical activation mechanism leads to grain refinement and lattice deformation, increasing internal energy and reactivity. Simultaneously, the hydroxyl radicals in the fruit peel extract enhance the hydrophilicity and interfacial reactivity of the cathode material battery powder, significantly improving the leaching efficiency of metals such as Li from the solution. The mechanical force of this invention induces the reactants to react under relatively mild conditions, achieving effective metal extraction.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] (1) The extraction agent used in this method is an aqueous ethanol solution, which is environmentally friendly and inexpensive; the fruit peel used is waste material from the fruit processing process. The entire recycling process is green and environmentally friendly, simple in process, and does not generate secondary pollution, and has significant economic, environmental and social benefits.

[0019] (2) Fruit peel and residue byproducts account for 40% to 50% of the total product during fruit processing. These byproducts are rich in organic acids, cellulose, reducing sugars, and other natural antioxidants. This method uses fruit peel waste extract as a leaching agent for waste lithium battery cathode powder, providing technical support for better energy and resource utilization of fruit peel waste.

[0020] (3) In this invention, the antioxidant components in the peel can scavenge free radicals and inhibit, eliminate or slow down oxidation reactions; at the same time, through its own reducing ability, it donates electrons and improves the solubility of the extract.

[0021] (4) In this invention, the fruit peel is extracted based on the combined ultrasonic-microwave technology. Based on the heating and strong penetrating power of microwaves, the extraction time is shorter and the efficiency is higher.

[0022] (5) This method is simple in process, and the ultrasonic-microwave-mechanical activation process is low in energy consumption and environmentally friendly. It also realizes the efficient recycling of waste lithium battery cathode materials, which has good environmental and economic benefits. Attached Figure Description

[0023] Figure 1 The cathode material of waste lithium batteries obtained by dismantling according to the present invention.

[0024] Figure 2 The image shows the XRD patterns of the cathode material battery powder at different ball milling speeds in Example 1 of this invention.

[0025] Figure 3 This is a diagram showing the average particle size of the cathode material at different ball milling speeds in Example 1 of the present invention.

[0026] Figure 4 The image shows the FT-IR images of litchi peel powder (LP) and leaching residue in Example 2 of this invention. Detailed Implementation

[0027] The present invention will be further described below with reference to the embodiments and accompanying drawings, but the present invention is not limited to the following embodiments. Example 1

[0028] (1) Chop the waste apple peels and place them in an electric constant temperature drying oven, dry them at 60°C, crush them and pass them through a 60-mesh sieve to obtain fruit peel powder A.

[0029] (2) Weigh 1g of fruit peel powder A and place it in a 50ml capped conical flask. Add 50vol% ethanol aqueous solution. The solid-liquid ratio of fruit peel powder A to ethanol aqueous solution is 1:30g / ml.

[0030] (3) Place the conical flask into the ultrasonic device, set the ultrasonic power to 500W, maintain the ultrasonic water bath at 60℃, and extract for 40 minutes to obtain fruit peel extract B.

[0031] (4) Place the conical flask in a microwave oven with a power of 600W and maintain the solution temperature at 60℃. Microwave extract for 5 minutes to obtain peel extract C. The extract contains antioxidant components including cellulose, reducing sugars, organic acids, total phenols, and total flavonoids. Antioxidants can scavenge free radicals and inhibit, eliminate, or slow down oxidation reactions; at the same time, they donate electrons through their own reducing power, thereby increasing the solubility of the extract.

[0032] (5) Pour the fruit peel extract C into a ball mill jar, add 1g of positive electrode material battery powder (the positive electrode material is lithium iron phosphate), and the solid-liquid ratio of the battery powder to the fruit peel extract C is also 1:30g / ml. The planetary ball mill is rotated at 500rpm and the ball milling time is 3 hours (30min ball milling, 15min interval, 6 cycles) to obtain Li-rich... + The metal salt leaching solution D and the leaching residue E contain aluminum powder, phosphorus iron slag, etc.

[0033] Upon testing, in this embodiment, the Li in the leachate was found to be... + The leaching rate was 93.57%, Fe 2+ The leaching rate is controlled below 5%, and Li metal can be recovered through separation and purification processes. Using fruit peel extract as the wet ball milling medium, the cathode material battery powder reacts with the extract C to transform into new products. During the reaction, due to mechanical forces, lattice distortion and lattice dislocation occur in the battery powder crystal lattice. Figure 2 The images show the XRD patterns of the positive electrode battery powder in Example 1 at different ball milling speeds. Figure 3 This graph shows the particle size variation of cathode battery powder at different ball milling speeds. At a given ball milling speed, the particle size decreases, resulting in better dispersibility. Mechanical activation applies mechanical energy to condensed matter such as solids and liquids through shearing, friction, impact, and extrusion, inducing changes in their structure and physicochemical properties, thereby triggering a chemical reaction. Unlike ordinary thermochemical reactions, mechanochemical reactions are driven by mechanical energy rather than thermal energy, allowing the reaction to proceed under relatively mild conditions. Example 2

[0034] (1) Chop the waste lychee peel and place it in an electric constant temperature drying oven, dry it at 60°C, crush it and pass it through a 60-mesh sieve to obtain fruit peel powder A.

[0035] (2) Weigh 1g of fruit peel powder A into a 50ml capped conical flask, add 60vol% ethanol aqueous solution, the solid-liquid ratio of fruit peel powder A to ethanol aqueous solution is 1:30g / ml.

[0036] (3) Place the conical flask into the ultrasonic device, set the ultrasonic power to 500W, maintain the ultrasonic water bath at 60℃, and extract with ultrasound for 40 minutes to obtain fruit peel extract B.

[0037] (4) Place the conical flask in a microwave device with a microwave power of 600W and keep the solution temperature at 60℃. Microwave extract for 3 minutes to obtain fruit peel extract C.

[0038] (5) Add 1g of positive electrode material battery powder (the positive electrode material is lithium manganese oxide) to the ball mill jar, and measure 50ml of fruit peel extract C into the ball mill jar. The solid-liquid ratio of battery powder to fruit peel extract C is also 1:50g / ml. The planetary ball mill is rotated at 500rpm and the ball milling time is 3 hours (30min ball milling, 15min interval, 6 cycles) to obtain leachate D and leachate residue E.

[0039] According to the test results, in this embodiment, the leaching rate of Li was 95.31% and the leaching rate of Mn was 97.26%. Figure 4 The images show the FT-IR spectra of the fruit peel waste (LPW) and leaching residue used in Example 2. As the ball milling speed increases, the particle size of the cathode material battery powder decreases, making it easier for it to react with the active ingredients in the fruit peel extract. Powder defects expand, and more and more disordered atoms appear in the ball mill jar. The disruption of the original chemical stability leads to atomic or ion exchange between the solid and liquid phases until a new system equilibrium is reached, thereby forming new compounds and achieving the recovery of the cathode material.

[0040] Comparative Example 1

[0041] Other conditions were the same as in Example 1, with wet mechanical activation of the positive electrode material battery powder directly using an ethanol-water solution in a ball mill jar. Li + The leaching rate was 28.53%. Ethanol is a small-molecule alcohol with reducing properties. Under acidic conditions, it can be partially or completely oxidized by strong oxidizing agents to produce acetic acid or carbon dioxide. The fruit peel extract contains natural organic acid components, and reducing sugars can also be decomposed into small-molecule organic acids; in addition to providing antioxidant components as leaching reducing agents, the fruit peel also provides organic acids as leaching agents.

[0042] Comparative Example 2

[0043] Under the same conditions as in Example 1, the fruit peel powder A and the positive electrode material battery powder were co-extracted in an ethanol-water solution. The ultrasonic-microwave co-extraction solution was then poured into a ball mill jar for wet mechanical activation. The addition of the positive electrode material battery powder may interfere with the extraction of the effective components in the fruit peel. Although the leaching of the positive electrode material has already been carried out in the extraction stage, the residual fruit peel residue encapsulates the positive electrode active material during the ball milling stage, slowing down the leaching of valuable metals. At this point, the leaching rate of metallic Li was 67.78%.

[0044] Comparative Example 3

[0045] Under the same conditions as in Example 2, ultrasonic extraction was followed by filtration to obtain extract B. Extract B was then directly used to perform wet mechanical activation with the positive electrode material battery powder. At this point, the leaching rates of Li and Mn were 78.43% and 81.22%, respectively. This is because under microwave action, the ethanol solvent molecules rotate to an excited state, and the energy released when the solvent molecules return to their ground state is transferred to the target components in the peel, accelerating their thermal motion and thus increasing the extraction rate several times over. Simultaneously, it reduces the dissolution of other impurities, further ensuring the quality of the peel extract.

[0046] Comparative analysis shows that this invention utilizes ethanol ultrasonic-microwave assisted extraction of effective components from fruit peel, improving the extraction efficiency of organic acids and antioxidants. It also utilizes wet mechanical activation to achieve efficient recovery of Li from waste lithium battery cathode materials. The entire process is simple, environmentally friendly, and has strong industrial applicability.

Claims

1. A method for extracting effective components from fruit peels and synergistically recovering Li from waste lithium battery cathode materials using wet mechanical activation, characterized in that, The process first uses an ethanol-water solution as an extractant to extract antioxidant components, including organic acids, total phenols, and total flavonoids, from the fruit peel waste. Then, the positive electrode battery powder and the fruit peel extract are wet-mechanically activated in a ball mill. After ball milling, the leachate and filter residue are recovered. The specific steps are as follows: (1) Dry, crush and sieve the fruit peel waste to obtain fruit peel powder A; weigh fruit peel powder A and ethanol aqueous solution and place them in a lidded conical flask, and use an ultrasonic cleaner to extract the extract to obtain extract B; wherein, the fruit peel waste is one or more of lychee peel, mango peel, apple peel and kiwi peel. (2) Place extract B in a microwave instrument for microwave extraction for a period of time, and filter to obtain peel extract C; (3) The fruit peel extract C was used as a leaching agent and waste lithium battery cathode powder was subjected to wet mechanical activation leaching in a planetary ball mill. After leaching, solid and liquid were separated to obtain Li-rich material. + The metal salt leaching solution D and the leaching residue E containing aluminum powder and ferrophosphate slag; wherein: In step (1), the fruit peel waste is passed through a 60-mesh sieve, the volume concentration of the ethanol aqueous solution is 30-70%, and the solid-liquid ratio of fruit peel powder A to ethanol aqueous solution is 1:10-1:100 g / ml. In step (1), the ultrasonic power is 300-600W, the ultrasonic temperature is 30-70℃, and the ultrasonic time is 20-60min; In step (2), the microwave power is 500-800W, the microwave temperature is the same as the ultrasonic temperature in step (1), and the microwave time is 3-7min.

2. The method as described in claim 1, characterized in that: In step (3), the planetary ball mill speed is 300-700 rpm, the mechanical activation time is 30 min of ball milling, 15 min interval, and 4-8 cycles.

3. The method as described in claim 1, characterized in that: In step (3), the waste lithium battery cathode powder is one or more of lithium iron phosphate and lithium manganese oxide; the solid-liquid ratio of the waste lithium battery cathode powder to the extraction liquid C is 1:10-1:50 g / ml.

4. The method as described in claim 1, characterized in that, In step (3), the leachate D is further treated by any one or more of the following methods: precipitation, organic solvent extraction, ion exchange separation, electrochemical reduction, co-precipitation of separation and synthesis, or high-temperature calcination solid phase recovery, to achieve purification and separation of Li element.

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