A separation material for separating a current collector and an active material of a waste lithium battery, a preparation method and applications

Abstract

The present application relates to the technical field of lithium battery recycling, and particularly relates to a separation material for separating current collectors and active materials of waste lithium batteries, a preparation method and application. The separation material for separating current collectors and active materials of waste lithium batteries is a mixture of any two or three of organic acid, organic alcohol and fatty acid ester. The preparation method of the separation material for separating current collectors and active materials of waste lithium batteries is also provided. The separation material is applied to the separation of current collectors and active materials of lithium iron phosphate waste lithium ion batteries, lithium nickel manganese oxide waste lithium ion batteries and lithium cobalt oxide waste lithium ion batteries. The organic acid, organic alcohol and fatty acid ester of the present application contain a large number of hydrogen atoms which can combine and react with fluorine atoms in PVDF, so that the PVDF is inactivated, thereby enabling the current collector and the active material to be peeled off and separated. The metal in the active material has a low dissolution rate or leaching rate in the separation material, which simplifies the process and improves the recovery rate of the active material.

Description

Technical Field

[0001] This invention relates to the field of lithium battery recycling technology, and in particular to a separation material, preparation method and application for separating current collectors and active materials from waste lithium batteries. Background Technology

[0002] When lithium-ion batteries reach the end-of-life standard, they need to be disposed of. Improper disposal will not only pollute the environment but also waste a large amount of economically valuable metal resources.

[0003] Currently, the current collector and active material in lithium-ion batteries are typically bonded together by the binder PVDF. Due to the strong bonding ability of PVDF, separating the current collector and active material is difficult. The common industrial method for separating the current collector and active material is calcination, but calcination has problems such as the release of toxic gases like hydrogen fluoride and fluorides, equipment corrosion, and high energy consumption.

[0004] Solvent-based separation of current collectors and active materials has the advantages of low energy consumption and high material recovery rate, and is attracting increasing attention from researchers, especially organic solvents, which are mild and environmentally friendly. However, commonly used current current collectors and active materials are highly polar solvents, such as N-methylpyrrolidone, N,N-dimethylacetamide, and N,N-dimethylformamide. These solvents are all solvents that are capable of dissolving, which requires the solvent to come into full contact with the binder and dissolve the binder, thereby separating the current collector from the active material. This process generates a large amount of organic waste liquid.

[0005] Therefore, it is necessary to provide a separation material for separating the current collector and active material of waste lithium batteries to solve at least one of the above-mentioned technical problems. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a separation material, preparation method, and application for separating current collectors and active materials from spent lithium-ion batteries. The separation material of this invention contains a large number of hydrogen atoms in its organic acids, organic alcohols, and fatty acid esters, which can combine with fluorine atoms in PVDF, deactivating the PVDF and thus enabling the current collector and active material to be separated. Simultaneously, the separation material of this invention does not dissolve the metal elements in the active material, simplifying the process and improving the recovery rate of the active material.

[0007] The technical solution of the present invention to solve the above-mentioned technical problems is as follows:

[0008] To achieve the above objective, this invention provides a separating material for separating current collectors and active materials from waste lithium batteries. This material is a mixture composed of any two or three of the following: organic acid, organic alcohol, and fatty acid ester. The molar ratio of the organic acid to the organic alcohol is 1:(6-100), or the molar ratio of the organic alcohol to the fatty acid ester is 1:(2-40), or the molar ratio of the organic acid to the fatty acid ester is 1:(5-20), or the molar ratio of the organic acid, the organic alcohol, and the fatty acid ester is 1:(5-10):(5-40).

[0009] The beneficial effects of this invention are: the organic acids, organic alcohols and fatty acid esters of this invention contain a large number of hydrogen atoms that can combine with fluorine atoms in PVDF, thereby deactivating PVDF, which allows the current collector and active material to be separated and separated, thus improving the recovery rate of the active material.

[0010] Based on the above technical solution, the present invention can be further improved as follows.

[0011] Furthermore, the organic acid is any one or a mixture of two or more aliphatic monocarboxylic acid compounds, aliphatic dicarboxylic acid compounds, and aliphatic polycarboxylic acid compounds. Specifically, the aliphatic monocarboxylic acid compounds are any one or a mixture of two or more aliphatic monocarboxylic acid compounds with 2 to 20 carbon atoms; the aliphatic dicarboxylic acid compounds are any one or a mixture of two or more aliphatic dicarboxylic acid compounds with 2 to 20 carbon atoms; and the aliphatic polycarboxylic acid compounds are any one or a mixture of two or more aliphatic polycarboxylic acid compounds with 2 to 20 carbon atoms. Preferably, the organic acid is selected from any one or a mixture of two or more formic acid, acetic acid, oxalic acid, propionic acid, malonic acid, valeric acid, glutaric acid, citric acid, tartaric acid, malic acid, ascorbic acid, lauric acid, caprylic acid, and stearic acid.

[0012] The beneficial effect of adopting the above-mentioned further scheme is that the above-mentioned organic acid can provide a large number of free hydrogen atoms, which can better combine with fluorine atoms in PVDF and promote the deactivation of PVDF.

[0013] Furthermore, the organic alcohol is any one or a mixture of two or more of monohydric fatty alcohols, dihydric fatty alcohols, and polyhydric fatty alcohols, wherein the monohydric fatty alcohol is any one or a mixture of two or more of monohydric fatty alcohols having 1 to 6 carbon atoms, the dihydric fatty alcohol is any one or a mixture of two or more of dihydric fatty alcohols having 1 to 6 carbon atoms, and the polyhydric fatty alcohol is any one or a mixture of two or more of polyhydric fatty alcohols having 1 to 6 carbon atoms; wherein the organic alcohol is preferably selected from any one or a mixture of two or more of methanol, ethanol, ethylene glycol, n-propanol, and isopropanol.

[0014] The beneficial effects of adopting the above-mentioned further scheme are: organic alcohols can provide a large number of hydrogen atoms, which can better combine with fluorine atoms in PVDF, thus deactivating the adhesion of coarse-sheared PVDF.

[0015] Furthermore, the fatty acid ester is any one or a mixture of two or more fatty acid esters having 1 to 18 carbon atoms; wherein, the fatty acid ester is preferably any one or more of methyl linoleate, methyl hexadecanoate and ethyl citrate.

[0016] The beneficial effect of adopting the above-mentioned further scheme is that fatty acid esters can provide a large number of hydrogen atoms, which promotes the deactivation of PFDF.

[0017] To achieve the above objective, this invention also provides a method for preparing the separation material for separating the current collector and active material of waste lithium batteries, comprising the following steps:

[0018] Weigh out any two or three of the organic acid, organic alcohol and fatty acid ester, and mix them by stirring to obtain the product; wherein the molar ratio of the organic acid to the organic alcohol is 1:(6-100), or the molar ratio of the organic alcohol to the fatty acid ester is 1:(2-40), or the molar ratio of the organic acid to the fatty acid ester is 1:(5-20), or the molar ratio of the organic acid, the organic alcohol and the fatty acid ester is 1:(5-10):(5-40).

[0019] The advantages of using the above scheme are that the preparation process is simple and convenient.

[0020] Furthermore, the mixing temperature is 25–180°C, and the mixing time is 0.5–3 hours.

[0021] The beneficial effect of adopting the above-mentioned further scheme is that, at the above-mentioned temperature and mixing time, it is conducive to mixing and the mixing is more uniform.

[0022] To achieve the above objectives, this invention provides an application of the separation material for separating current collectors and active materials from waste lithium batteries in the separation of current collectors and active materials from waste lithium batteries.

[0023] The above-described application, the method for separating the current collector and active material of waste lithium batteries, includes the following steps:

[0024] (1) Take waste lithium-ion batteries, discharge the cells, and then shear, crush and screen them to obtain electrode plates.

[0025] (2) Place the electrode sheet in the reaction vessel, and then add the separation material for separating the current collector and active material of the waste lithium battery as described in any one of claims 1-4 into the reaction vessel until the electrode sheet is submerged, and the current collector and active material are separated.

[0026] (3) The current collector and active material are collected separately after sieving and filtration using a sieve and rinsing, thus completing the separation.

[0027] The beneficial effects of adopting the above scheme are: after the waste lithium-ion batteries are crushed, they can be directly mixed with the separation materials, which can better separate the active materials and current collectors, and the recovery rate of active materials is high.

[0028] Furthermore, in step 1, the waste lithium-ion battery is any one or more of lithium iron phosphate waste lithium-ion batteries, nickel cobalt manganese waste lithium-ion batteries, and lithium cobalt oxide waste lithium-ion batteries, and the current collector and active material are bonded together using PVDF.

[0029] The beneficial effect of adopting the above-mentioned further solution is that the separation material of the present invention can quickly separate the active material and current collector of waste lithium iron phosphate lithium-ion batteries, waste lithium nickel cobalt manganese oxide lithium-ion batteries and waste lithium cobalt oxide lithium-ion batteries.

[0030] Furthermore, the stripping method is any one or more of mechanical stirring, mechanical vibration, and ultrasonic vibration; the stripping temperature is 25-180℃, and the time is 10-120 min; the solid-liquid ratio of the broken battery cell to the separation material of the waste lithium battery current collector and active material is 10-100 g / L.

[0031] The beneficial effects of adopting the above-mentioned further scheme are: increasing the rinsing effect by adopting the above method can increase the contact between the separation material and PVDF, which is conducive to accelerating the deactivation of PVDF and achieving good peeling effect; under the above-mentioned temperature, time and solid-liquid ratio conditions, the peeling effect between the current collector and the active material is good. Attached Figure Description

[0032] Figure 1 This is an effect diagram of the current collector aluminum foil, copper foil and active material collected after the first peeling treatment in Embodiment 1 of the present invention;

[0033] Figure 2 This is a scanning electron microscope (SEM) image of the active material after the first stripping treatment of the lithium nickel cobalt manganese oxide electrode sheet in Example 1 of the present invention.

[0034] Figure 3 This is a scanning electron microscope (SEM) image of the surface of the current collector aluminum foil after the first peeling treatment of the lithium nickel cobalt manganese oxide electrode sheet in Example 1 of the present invention.

[0035] Figure 4 This is a statistical chart showing the complete stripping time of the lithium nickel cobalt manganese oxide electrode sheet during the recycling process of the separation material in Example 1 of the present invention.

[0036] Figure 5The graph shows the leaching rate test of the waste liquid after the first stripping treatment and the statistical graph of the leaching rate of the waste liquid after the fifth cycle stripping treatment in Example 1 of the present invention.

[0037] Figure 6 This is a statistical chart showing the complete peeling time of the lithium nickel cobalt manganese oxide electrode sheet under the separation material recycling process in Example 5 of the present invention.

[0038] Figure 7 This is a graph showing the leaching rate test of the waste liquid after the first stripping treatment and the statistical chart of the leaching rate of the waste liquid after the fifth cycle stripping treatment in Example 5 of the present invention. Detailed Implementation

[0039] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0040] Example 1

[0041] This embodiment provides a separation material for separating the current collector and active material of waste lithium batteries. The separation material is composed of ethylene glycol and oxalic acid mixed in a molar ratio of 5:1.

[0042] The electrodes of the waste lithium-ion batteries are lithium nickel cobalt manganese oxide electrodes. The electrodes are broken into 10mm×10mm pieces and put into a reaction vessel. Then, the separation material mentioned above is added. The solid-liquid ratio of the electrodes to the separation material is 60g / L. The mixture is soaked at 100℃ and then mechanically shaken. After 15 minutes, the current collector and active material are completely separated. The mixture is then screened, filtered, and the active material, current collector aluminum foil, copper foil, and waste liquid are collected.

[0043] The waste liquid was then recycled to process four batches of the same lithium nickel cobalt manganese oxide electrode sheets, and the separated material was used for stripping treatment a total of five times.

[0044] The leaching rate of active metals in the waste liquid was tested using inductively coupled plasma atomic emission spectrometry. The initial leaching rate results were as follows: lithium 3.92%; nickel 1.43%; cobalt 1.37%; manganese 1.45%; aluminum 1.64%.

[0045] After five cycles, the leaching rate test results are as follows: lithium 2.82%; nickel 1.24%; cobalt 1.16%; manganese 1.23%; aluminum 1.13%.

[0046] Figure 1 This is an image showing the effect of collecting the current collector aluminum foil, copper foil, and active material after the first peeling process in this embodiment. Figure 1 From top to bottom, the components are current collector aluminum foil, copper foil, and active material.

[0047] The microstructure was tested using scanning electron microscopy. Figure 2This is a scanning electron microscope image of the surface of the active material after the first peeling treatment in this embodiment; Figure 3 This is a scanning electron microscope (SEM) image of the surface of the current collector aluminum foil after the first peeling treatment in this embodiment.

[0048] Figure 4 This is a statistical chart showing the complete stripping time of the lithium nickel cobalt manganese oxide electrode sheet during the recycling of the separation material in this embodiment.

[0049] Figure 5 This is a graph showing the leaching rate test of the waste liquid after the first stripping treatment and the statistical chart of the leaching rate of the waste liquid after the fifth cycle of stripping treatment in this embodiment.

[0050] Example 2

[0051] This embodiment provides a separation material for separating the current collector and active material of waste lithium batteries. The separation material is composed of acetic acid and ethyl acetate mixed in a molar ratio of 20:1.

[0052] The electrodes of the waste lithium-ion batteries are lithium iron phosphate electrodes. The electrodes are broken into 20mm×20mm pieces and put into a reaction vessel. Then, the separation material mentioned above is added. The solid-liquid ratio of the electrode to the separation material is 60g / L. The mixture is soaked at 100℃ for 80min and then mechanically shaken. After 80min, the current collector and active material are completely separated. The mixture is then screened, filtered, and the active material, current collector aluminum foil, copper foil, and waste liquid are collected.

[0053] The leaching rate of active metals in the waste liquid was tested using inductively coupled plasma atomic emission spectrometry. The leaching rate results are as follows: lithium 3.22%; nickel 1.03%; cobalt 1.41%; manganese 1.39%; aluminum 1.01%.

[0054] Example 3

[0055] This embodiment provides a separating material for separating current collectors and active materials from waste lithium batteries. The separating material is composed of ethanol and methyl linoleate mixed in a molar ratio of 40:1.

[0056] The electrodes of the waste lithium-ion batteries are lithium nickel cobalt manganese oxide electrodes. The electrodes are crushed into 20mm×20mm pieces and put into a reaction vessel. Then, the separation material mentioned above is added. The solid-liquid ratio of the electrode to the separation material is 10g / L. The mixture is stirred at 180℃. After 90 minutes, the current collector and active material are completely separated. The mixture is then screened, filtered, and the active material, current collector aluminum foil, copper foil, and waste liquid are collected.

[0057] The leaching rate of active metals in the waste liquid was tested using inductively coupled plasma atomic emission spectrometry (ICP-AES). The leaching rate results are as follows: lithium 4.95%; nickel 0.83%; cobalt 0.89%; manganese 0.94%; aluminum 0.75%.

[0058] Example 4

[0059] This embodiment provides a separation material for separating the current collector and active material of waste lithium batteries. The separation material is composed of ethanol and citric acid mixed in a molar ratio of 40:1.

[0060] The electrodes of the waste lithium-ion batteries are lithium nickel cobalt manganese oxide electrodes. The electrodes are broken into 20mm×20mm pieces and put into a reaction vessel. Then, the separation material mentioned above is added. The solid-liquid ratio of the electrodes to the separation material is 30g / L. The mixture is stirred at 60℃. After 10 minutes, the current collector and active material are completely separated. The mixture is then screened, filtered, and the active material, current collector aluminum foil, copper foil, and waste liquid are collected.

[0061] The leaching rate of active metals in the waste liquid was tested using inductively coupled plasma atomic emission spectrometry. The leaching rate results were: lithium 5.2%; nickel 8.5%; cobalt 7.8%; manganese 8.3%; aluminum 4.3%.

[0062] Example 5

[0063] This embodiment provides a separation material for separating the current collector and active material of waste lithium batteries. The separation material is composed of ethanol and malonic acid mixed in a molar ratio of 10:1.

[0064] The electrodes of the waste lithium-ion batteries are lithium nickel cobalt manganese oxide electrodes. The electrodes are broken into 20mm×20mm pieces and put into a reaction vessel. Then, the separation material mentioned above is added. The solid-liquid ratio of the electrodes to the separation material is 20g / L. The mixture is soaked at 45℃ and ultrasonically separated after 8 minutes. The current collector and active material are completely separated. The mixture is then screened, filtered, and the active material, current collector aluminum foil, copper foil, and waste liquid are collected.

[0065] The waste liquid was then recycled to process four batches of the same lithium nickel cobalt manganese oxide electrode sheets, and the separated material was used for stripping treatment a total of five times.

[0066] The leaching rate of active metals in the waste liquid was tested using inductively coupled plasma atomic emission spectrometry (ICP-AES). The initial leaching rate results were: lithium 2.4%; nickel 0.2%; cobalt 0.2%; manganese 0.3%; aluminum 0.2%. After five cycles of recycling, the leaching rate results were as follows: lithium 2.0%; nickel 0.5%; cobalt 0.6%; aluminum 0.7%.

[0067] Figure 6 This is a statistical chart showing the complete stripping time of the lithium nickel cobalt manganese oxide electrode sheet during the recycling process of the separated materials in this embodiment.

[0068] Figure 7 This is a graph showing the leaching rate test of the waste liquid after the first stripping treatment and the statistical chart of the leaching rate of the waste liquid after the fifth cycle of stripping treatment in this embodiment.

[0069] The results show that the separation materials obtained in Examples 1-5 can all be used to separate the current collector and active material of waste lithium batteries. At the same time, the above separation materials have little corrosive effect on the surface of the current collector and active material, and the performance of the obtained current collector and active material is good. The hydrogen atoms provided by the separation material of the present invention can combine and react with the fluorine atoms in PVDF, thereby deactivating PVDF and enabling the current collector and active material to be peeled off and separated. The separation materials of Examples 1-5 all have a complete peeling time of less than 100 min for the current collector and active material, which shows that the separation material of the present invention can improve the separation efficiency of the current collector and active material.

[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A separation material for separating current collectors and active materials from waste lithium batteries, characterized in that, The separating material is a mixture of organic acids and fatty acid esters, wherein the molar ratio of the organic acids to the fatty acid esters is 1:(5-20); Alternatively, the separating material may be a mixture of organic alcohols and fatty acid esters, wherein the molar ratio of the organic alcohols to the fatty acid esters is 1:(2-40); Alternatively, the separating material may be a mixture of organic acids, fatty acid esters, and organic alcohols, wherein the molar ratio of the organic acids, the organic alcohols, and the fatty acid esters is 1:(5-10):(5-40); The fatty acid ester is selected from any one or more of methyl linoleate, methyl hexadecanoate and ethyl citrate; The electrode adhesive of the waste lithium battery is PVDF.

2. The separation material for separating the current collector and active material of waste lithium batteries according to claim 1, characterized in that, The organic acid is any one or a mixture of two or more aliphatic monocarboxylic acid compounds, aliphatic dicarboxylic acid compounds, and aliphatic polycarboxylic acid compounds. Specifically, the aliphatic monocarboxylic acid compounds are any one or a mixture of two or more aliphatic monocarboxylic acid compounds with 2 to 20 carbon atoms; the aliphatic dicarboxylic acid compounds are any one or a mixture of two or more aliphatic dicarboxylic acid compounds with 2 to 20 carbon atoms; and the aliphatic polycarboxylic acid compounds are any one or a mixture of two or more aliphatic polycarboxylic acid compounds with 2 to 20 carbon atoms.

3. The separation material for separating the current collector and active material of waste lithium batteries according to claim 1, characterized in that, The organic alcohol is any one or a mixture of two or more of monohydric fatty alcohols, dihydric fatty alcohols, and polyhydric fatty alcohols, wherein the monohydric fatty alcohol is any one or a mixture of two or more of monohydric fatty alcohols having 1 to 6 carbon atoms, the dihydric fatty alcohol is any one or a mixture of two or more of dihydric fatty alcohols having 1 to 6 carbon atoms, and the polyhydric fatty alcohol is any one or a mixture of two or more of polyhydric fatty alcohols having 1 to 6 carbon atoms.

4. The method for preparing the separation material for separating the current collector and active material of waste lithium batteries according to any one of claims 1 to 3, characterized in that, Includes the following steps: Weigh out any one or two of the organic acids and organic alcohols, and mix them with the fatty acid ester to obtain the product; wherein the molar ratio of the organic alcohol to the fatty acid ester is 1:(2-40), or the molar ratio of the organic acid to the fatty acid ester is 1:(5-20), or the molar ratio of the organic acid, the organic alcohol and the fatty acid ester is 1:(5-10):(5-40).

5. The preparation method according to claim 4, characterized in that, The mixing temperature is 25–180°C, and the time is 0.5–3 hours.

6. The application of the separating material for separating waste lithium battery current collectors and active materials as described in any one of claims 1 to 3 in the separation of waste battery current collectors and active materials.

7. The application according to claim 6, characterized in that, The method for separating the current collector and active material from waste lithium batteries includes the following steps: (1) Take waste lithium-ion batteries, discharge the cells, and then shear, crush and screen them to obtain electrode plates. (2) Place the electrode sheet in the reaction vessel, and then add the separation material for separating the current collector and active material of the waste lithium battery as described in any one of claims 1-4 into the reaction vessel until the electrode sheet is submerged, and the current collector and active material are separated. (3) The material is screened and filtered, and after rinsing, the current collector, active material, copper foil and separation material are collected respectively, thus completing the separation.

8. The application according to claim 7, characterized in that, In step 1, the waste lithium-ion battery is any one or more of the following: lithium iron phosphate waste lithium-ion battery, nickel cobalt manganese oxide waste lithium-ion battery, and cobalt oxide waste lithium-ion battery.

9. The application according to claim 7, characterized in that, In step 2, the stripping method is any one or more of mechanical stirring, mechanical vibration, and ultrasonic vibration; the stripping temperature is 25-180℃, and the time is 10-120 min; the solid-liquid ratio of the electrode sheet to the separation material of the waste lithium battery current collector and active material is 10-100 g / L.

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