Separation method for electrode material composition and metal substrate in lithium-ion battery

Abstract

contains both a chelating agent and a pH-adjusting agent, which are distinct substances. This method offers benefits such as energy efficiency and environmental sustainability while preserving the integrity of the electrode material composition, ensuring no damage occurs during the separation process.

Description

[Technical Field]

[0001] This invention relates to a lithium-ion battery, and more particularly to a method for separating electrode material components from a metal substrate in a lithium-ion battery. [Previous Technology]

[0002] With technological advancements and increased environmental awareness, lithium-ion batteries have become an indispensable source of electricity in daily life, widely used in mobile phones, laptops, tablets, electric vehicles, and other consumer products. However, while lithium-ion batteries bring convenience and improve quality of life, the number of discarded lithium-ion batteries is also increasing daily, causing significant negative impacts on the environment. Furthermore, the large-scale mining of raw materials such as lithium, cobalt, or nickel used in the production of lithium-ion batteries will lead to resource depletion. Therefore, how to effectively recycle materials from lithium-ion batteries, achieve material recycling, and reduce environmental impact has become a crucial issue for those skilled in the art.

[0003] Current methods for separating and recovering electrode materials from metal substrates in lithium-ion battery electrodes include Method 1, Method 2, and Method 3. In Method 1, the lithium-ion battery electrode is placed in an organic solvent and subjected to ultrasonic vibration to separate the electrode material from the metal substrate. However, Method 1 is time-consuming. In Method 2, the lithium-ion battery electrode undergoes thermal decomposition to separate the electrode material from the metal substrate. However, Method 2 is energy-intensive and releases toxic substances such as carbon dioxide (CO2) or volatile organic compounds. In Method 3, the lithium-ion battery electrode is immersed at room temperature in a buffer solution with a pH of 4 to 7 (e.g., citrate buffer solution, phosphate buffer solution, or acetate buffer solution) for 1 to 30 minutes to separate the electrode material from the metal substrate. However, although method three can separate the electrode material from the metal substrate, the buffer solution will dissolve the metal in the electrode material, resulting in the loss of the electrode material's composition or potentially destroying the electrode material's morphology.

[0004] In view of the above, how to develop an energy-saving and environmentally friendly method for separating electrode materials from metal substrates without causing damage to the composition or morphology of the electrode materials is a problem that urgently needs to be overcome in this field. [Summary of the Invention]

[0005] Therefore, the object of the present invention is to provide a method for separating the electrode material components of a lithium-ion battery from the metal substrate.

[0006] Therefore, the method for separating the electrode material components of a lithium-ion battery from the metal substrate of the present invention includes the following steps: immersing the electrode of the lithium-ion battery in a chelating solution with a temperature range of 20°C to 30°C for at least 40 minutes. The electrode of the lithium-ion battery includes a metal substrate and electrode material components disposed on the metal substrate. The pH value of the chelating solution is between 6 and 9, and includes a chelating agent and a pH adjusting agent. The chelating agent and the pH adjusting agent are different components.

[0007] The advantages of the present invention are: through the chelating solution, the method for separating the electrode material components of the lithium-ion battery from the metal substrate has the advantages of energy saving and environmental friendliness, while also preserving the original physical state [e.g., morphology] or chemical state of the electrode material components without causing damage to the electrode material components, thus enabling recycling.

Implementation Method

[0008] The present invention provides a method for separating electrode material components from a metal substrate in a lithium-ion battery, comprising the following steps: immersing the electrode of the lithium-ion battery in a chelating solution at a temperature range of 20°C to 30°C for at least 40 minutes. The electrode of the lithium-ion battery includes a metal substrate and electrode material components disposed on the metal substrate. The pH value of the chelating solution is between 6 and 9, and includes a chelating agent and a pH adjusting agent. The chelating agent and the pH adjusting agent are different components.

[0009] The present invention will now be described in detail.

[0010] In some embodiments, the soaking time is from 40 minutes to 240 minutes. In some embodiments, the soaking time is from 40 minutes to 90 minutes.

[0011] <Electrode>

[0012] The metal substrate is used to carry the conductor of the electrode material component and is a current collector in the lithium-ion battery, such as a metal foil or a metal alloy foil. The metal foil is, for example, but not limited to, copper foil or aluminum foil.

[0013] The electrode material composition includes, for example but not limited to, an anode material composition including an anode active material or a cathode material composition including a cathode active material.

[0014] The anode active material is, for example, but not limited to, conductive carbon material. The conductive carbon material is, for example, but not limited to, graphite, graphene, or carbon black. The anode material composition also includes at least one additive, and the additive is, for example, but not limited to, aluminum oxide, copper oxide, binder, lithium titanate, or silicon-based material. The aluminum oxide is, for example, but not limited to, alumina (Al2O3). The copper oxide is, for example, but not limited to, copper oxide (CuO). The silicon-based material is, for example, but not limited to, silicon oxide (SiOx) or lithium silicide material. The lithium silicide material includes, for example, lithium silicide having a fully lithiated phase of Li3.75Si, lithium silicide having a fully lithiated phase of Li₁₂Si₇, or lithium silicide having a fully lithiated phase of Li₁₅Si₄.

[0015] The cathode active material includes, but is not limited to, lithium-based oxides comprising, for example, lithium and at least one metal. The metal includes, for example, but is not limited to, iron, cobalt, manganese, or nickel. The lithium-based oxide includes, for example, but is not limited to, lithium iron phosphate (LiFePO4), lithium cobalt oxide (LiCoO2), lithium cobalt oxide (LiCoO2), lithium manganese oxide (LiMn2O4), lithium nickel oxide (LiNiO2), lithium nickel manganese cobalt oxide, or lithium manganese iron phosphate (LMFP). The cathode material composition also includes at least one additive, and the additive is selected from aluminum oxide or copper oxide. The aluminum oxide includes, for example, but is not limited to, aluminum oxide (Al2O3). The copper oxide includes, for example, but is not limited to, copper oxide (CuO).

[0016] <chelation solution>

[0017] The chelating solution of the present invention is not a buffer solution, and the chelating agent can react with metal ions derived from the electrode material composition to form a functional layer, such as a passivation layer or an intermediate layer, between the surface of the metal substrate and the electrode material composition. Through this functional layer, the electrode material composition is peeled off from the metal substrate, and the pH adjuster is used to give the chelating solution the desired pH value, so that under such pH conditions, the separation method of the present invention has the advantage of being environmentally friendly, while reducing damage to the composition or form of the electrode material composition.

[0018] [chelating agent]

[0019] The chelating agent can be used alone or in combination, and the chelating agent is, for example, but not limited to, carboxylate-based chelating agents, hydroxyl-based chelating agents, nitrogen-based chelating agents, phosphonate-based chelating agents, sulfur-based chelating agents, organometallic chelating agents, polymeric chelating agents, chelating surfactants, or macrocyclic chelating agents.

[0020] This carboxylic acid chelating agent can be used alone or in combination, and the carboxylic acid chelating agent is, for example, but not limited to, citric acid, citric acid salt, oxalic acid, oxalic acid salt, tartaric acid, tartaric acid salt, lactic acid, lactic acid salt, malic acid, malic acid salt, succinic acid, succinic acid salt, gluconic acid, or gluconic acid salt. The citrate is, for example, but not limited to, sodium citrate. The oxalic acid salt is, for example, but not limited to, sodium oxalate, potassium oxalate, or iron(II) oxalate. The tartrate salt includes, but is not limited to, sodium tartrate or potassium sodium tartrate. The lactate salt includes, but is not limited to, sodium lactate, calcium lactate, or magnesium lactate. The malic acid salt includes, but is not limited to, potassium malate, magnesium malate, zinc malate, or sodium malate. The succinic acid salt includes, but is not limited to, calcium succinate, sodium succinate, or potassium succinate. This gluconate salt includes, but is not limited to, sodium gluconate, calcium gluconate, ferrous gluconate, or magnesium gluconate.

[0021] The hydroxyl chelating agent can be used alone or in combination, and the hydroxyl chelating agent is, for example, but not limited to, mannitol, sorbitol or glucose.

[0022] The nitrogen-based chelating agent can be used alone or in combination, and the nitrogen-based chelating agent is, for example, but not limited to, ethylenediaminetetraacetic acid, ethylenediaminetetraacetic acid salt, diethylenetriamine pentaacetic acid, ethylenediamine, diethylenetriamine, triethylenetetramine, or nitrilotriacetic acid. The ethylenediaminetetraacetic acid salt includes, but is not limited to, disodium EDTA, tetrasodium EDTA, ferric sodium EDTA, or zinc disodium EDTA.

[0023] The phosphate ester chelating agent can be used alone or in combination, and the phosphate ester chelating agent is, for example, but not limited to, amino tris-methylene phosphonic acid, ethylenediamine tetra-methylene phosphonic acid, 1-hydroxyethane-1,1-diphosphonic acid, hexamethylenediamine tetra(methylenephosphonic acid) or phytic acid, etc.

[0024] The sulfur-based chelating agent can be used alone or in combination with other agents, and the sulfur-based chelating agent is, for example but not limited to, dimercaprol, glutathione, thioglycolic acid or cysteine.

[0025] The organometallic chelating agent can be used alone or in combination, and the organometallic chelating agent is, for example, but not limited to, ferrocene-based materials containing a chelating group or cyclopentadiene. The chelating group is, for example, but not limited to -COOH, -OH or -NH2.

[0026] This polymeric chelating agent can be used alone or in combination with other agents, and the polymeric chelating agent is, for example, but not limited to, chitosan-based materials, polyacrylic acid, or polyethyleneimine. The chitosan-based materials are, for example, but not limited to, carboxymethyl chitosan, hydroxypropyl chitosan, or n-succinyl chitosan.

[0027] This chelating surfactant can be used alone or in combination with other surfactants, and the chelating surfactant is, for example, but not limited to, sodium lauryl sulfate or alkyl polyglucoside. The alkyl polyglucoside is, for example, but not limited to, decyl glucoside, lauryl glucoside, caprylyl / capryl glucoside, or myristyl glucoside.

[0028] The macrocyclic chelating agent can be used alone or in combination, and the macrocyclic chelating agent is, for example, but not limited to, crown ether chelating agents. The crown ether chelating agent is, for example, but not limited to, 18-crown-6 or 15-crown-5.

[0029] [pH adjusting agent]

[0030] The pH adjuster can be used alone or in combination with other pH adjusters, and the pH adjuster is, for example, but not limited to, inorganic acid, organic acid, inorganic base, organic amine base, ammonium-based compound or metal oxide.

[0031] The inorganic acid can be used alone or in combination, and the inorganic acid is, for example, but not limited to, boric acid, hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, hydrofluoric acid or perchloric acid.

[0032] The organic acid can be used alone or in combination, and the organic acid is, for example, but not limited to, acetic acid, citric acid, formic acid, lactic acid, malic acid, tartaric acid, oxalic acid, benzoic acid, or gluconic acid.

[0033] The inorganic base can be used alone or in combination with other bases, and the inorganic base is, for example, but not limited to, sodium hydroxide, potassium hydroxide, calcium hydroxide, ammonia, magnesium hydroxide, lithium hydroxide, barium hydroxide, cesium hydroxide, or sodium borate.

[0034] The organic amine base can be used alone or in combination with other organic amine bases, and the organic amine base is, for example, but not limited to, triethanolamine, diethanolamine, ethanolamine, pyridine, aniline or imidazole.

[0035] The ammonium compound can be used alone or in combination, and the ammonium compound is, for example, but not limited to, ammonium hydroxide, ammonium bicarbonate or ammonium chloride.

[0036] The metal oxide can be used alone or in combination, and the metal oxide is, for example, but not limited to, zinc oxide, aluminum oxide or manganese oxide.

[0037] The method for separating the electrode material and the metal substrate of the lithium-ion battery of the present invention further includes a filtration process and a sorting process. In the filtration process, the liquid and solid components of the mixture obtained after soaking are separated to obtain a filtrate and a filter material including the metal substrate and the electrode material. This filtration process is performed, for example, but not limited to, using a porous filter element. The porous filter element is, for example, but not limited to, a filter membrane. In the sorting process, the metal substrate and the electrode material are sorted from the filter material to independently obtain the metal substrate and the electrode material separately.

[0038] The present invention will be further described with reference to the following embodiments, but it should be understood that the embodiments are only for illustrative purposes and should not be construed as limiting the implementation of the present invention.

[0039] Example 1

[0040] Step (a): Boric acid and sodium citrate are mixed to form a chelate solution with a pH of 6, wherein the concentration of sodium citrate in the chelate solution is 0.2M.

[0041] Step (b): Immerse the electrode of the lithium-ion battery in the chelation solution at 25°C for 240 minutes to obtain a mixture, wherein the electrode of the lithium-ion battery includes a copper foil and a cathode material composition disposed on the copper foil, and the cathode material composition includes lithium iron phosphate (LiFePO4), aluminum oxide (Al2O3) and copper oxide (CuO).

[0042] Step (c): Filter the mixture to obtain liquid filtrate and solid filtrate. Sort the solid filtrate to obtain the copper foil and the cathode material components independently.

[0043] Example 2

[0044] Step (a): Boric acid and sodium citrate are mixed to form a chelate solution with a pH of 7, wherein the concentration of sodium citrate in the chelate solution is 0.2M.

[0045] Step (b): Immerse the electrode of the lithium-ion battery in the chelation solution at 25°C for 240 minutes to obtain a resultant mixture. The electrode of the lithium-ion battery includes a copper foil and a cathode material composition disposed on the copper foil. The cathode material composition includes lithium iron phosphate (LiFePO4), aluminum oxide (Al2O3), and copper oxide (CuO).

[0046] Step (c): Filter the mixture to obtain liquid filtrate and solid filtrate. Sort the solid filtrate to obtain the copper foil and the cathode material components.

[0047] Example 3

[0048] Step (a): Acetic acid and sodium citrate are mixed to form a chelate solution with a pH of 7, wherein the concentration of sodium citrate in the chelate solution is 0.2M.

[0049] Step (b): Immerse the electrode of the lithium-ion battery in the chelation solution at 25°C for 240 minutes to obtain a resultant mixture. The electrode of the lithium-ion battery includes a copper foil and a cathode material composition disposed on the copper foil. The cathode material composition includes lithium iron phosphate (LiFePO4), aluminum oxide (Al2O3), and copper oxide (CuO).

[0050] Step (c): Filter the mixture to obtain liquid filtrate and solid filtrate. Sort the solid filtrate to obtain the copper foil and the cathode material components.

[0051] Comparative Example 1

[0052] Step (a): Citric acid and sodium citrate are mixed to form a buffer solution with a pH of 6, wherein the concentration of sodium citrate in the buffer solution is 0.2M.

[0053] Step (b): Immerse the electrode of the lithium-ion battery in the buffer solution at 25°C for 240 minutes to obtain a mixture, wherein the electrode of the lithium-ion battery includes a copper foil and a cathode material composition disposed on the copper foil, and the cathode material composition includes lithium iron phosphate (LiFePO4), aluminum oxide (Al2O3) and copper oxide (CuO).

[0054] Step (c): Filter the mixture to obtain liquid filtrate and solid filtrate. Sort the solid filtrate to obtain the copper foil and the cathode material components.

[0055] Comparative Example 2

[0056] Step (a): Citric acid and sodium citrate are mixed to form a buffer solution with a pH of 7, wherein the concentration of sodium citrate in the buffer solution is 0.2M.

[0057] Step (b): Immerse the electrode of the lithium-ion battery in the buffer solution at 25°C for 240 minutes to obtain a resultant mixture. The electrode of the lithium-ion battery includes a copper foil and a cathode material component disposed on the copper foil. The cathode material component includes lithium iron phosphate (LiFePO4), aluminum oxide (Al2O3), and copper oxide (CuO).

[0058] Step (c): Filter the mixture to obtain liquid filtrate and solid filtrate. Sort the solid filtrate to obtain the copper foil and the cathode material components.

[0059] Comparative Example 3

[0060] Step (a): Acetic acid and citric acid are mixed to form a chelate solution with a pH of 2, wherein the concentration of citric acid in the chelate solution is 0.1M.

[0061] Step (b): Immerse the electrode of the lithium-ion battery in the chelation solution at 25°C for 240 minutes to obtain a mixture, wherein the electrode of the lithium-ion battery includes a copper foil and a cathode material composition disposed on the copper foil, and the cathode material composition includes lithium iron phosphate (LiFePO4), aluminum oxide (Al2O3) and copper oxide (CuO).

[0062] Step (c): Filter the mixture to obtain liquid filtrate and solid filtrate. Sort the solid filtrate to obtain the copper foil and the cathode material components.

[0063] Evaluation Items

[0064] Measurement of electrode material composition loss (unit: wt%): The filtrates of Examples 1 to 3 and Comparative Examples 1 to 3 were analyzed using an inductively coupled plasma device.

[0065] Crystal structure analysis: The electrode material composition of the electrode in step (b) and the electrode material composition of the filter in step (c) of Example 1 were analyzed using an X-ray diffractometer, and the results are shown in Figure 2.

[0066] Appearance and morphology analysis: The electrode material composition of the electrode in step (b) and the electrode material composition of the filter in step (c) of Example 1 were photographed using a scanning electron microscope, and the results are shown in Figures 3 to 4 in sequence.

[0067] Referring to Figure 1, Figure 1 is a photograph of the appearance of the filter material in step (c) of Example 1. As can be seen from the photograph, the method for separating the electrode material components of the lithium-ion battery of the present invention from the metal substrate can indeed effectively separate the electrode material components from the metal substrate.

[0068] Referring to Figure 2, the upper curve in Figure 2 represents the electrode material components in the filter material in step (c) of Example 1, while the lower curve represents the electrode material components in step (a) of Example 1. As can be seen from Figure 2, the curves of the electrode material components in the filter material are consistent with the curves of the electrode material components of the electrode. This indicates that the electrode material components are identical in crystalline structure before and after immersion. Based on this, the separation method of the electrode material components and the metal substrate of the lithium-ion battery of the present invention does not damage the electrode material components, but preserves the original state of the electrode material components.

[0069] Referring to Figures 3 and 4, Figure 3 shows the morphology of the electrode material components in step (a) of Example 1, and Figure 4 shows the morphology of the electrode material components in the filter in step (c) of Example 1. As can be seen from Figures 3 and 4, the morphology of the electrode material components in the filter is largely consistent with that of the electrode material components of the electrode. This indicates that the electrode material components are the same in appearance before and after immersion. Based on this, the separation method of the electrode material components of the lithium-ion battery of the present invention does not damage the electrode material components and preserves the original state of the electrode material components.

[0070] Table 1 Example Comparative example 1 2 3 1 2 3 Chelating solution Chelating agents Sodium citrate Sodium citrate Sodium citrate -- -- Citric acid pH adjuster Boric acid Boric acid acetic acid acetic acid pH 6 7 7 2 Buffer solution Element -- -- -- Citric acid and sodium citrate -- pH 6 7 filtrate Aluminum (wt%) 0.36 0.58 0.36 0.67 0.83 1.85 Copper (wt%) 0.55 0.47 2.06 0.67 0.74 2.17 Lithium (wt%) 0.18 0.20 0.23 0.39 0.26 1.16 Iron (wt%) 1.65 1.52 3.04 2.39 1.57 13.07 Phosphorus (wt%) 2.92 2.64 6.94 5.32 4.03 13.24

[0071] As can be seen from the experimental data in Table 1, the contents of aluminum, copper, lithium, iron and phosphorus in the filtrates of Examples 1 to 2 are all lower than those in the filtrates of Comparative Examples 1 to 3. This indicates that the separation method of the electrode material components and the metal substrate of the lithium-ion battery of the present invention does not cause the lithium metal oxide in the electrode material components to dissolve from the electrode material components, thereby causing the loss of the components of the electrode material components.

[0072] In summary, through this chelating solution, the method for separating the electrode material components and the metal substrate of the lithium-ion battery of the present invention has the advantages of energy saving, environmental friendliness, and preservation of the original state (e.g., morphology or composition) of the electrode material components, thus effectively achieving the purpose of the present invention.

[0073] However, the above description is only an embodiment of the present invention and should not be construed as limiting the scope of the present invention. Any simple equivalent changes and modifications made in accordance with the scope of the patent application and the contents of the patent specification of the present invention shall still fall within the scope of the patent of the present invention. [Simplified Explanation of the Diagram]

[0074] Other features and effects of the present invention will be clearly presented in the embodiments with reference to the drawings, wherein: Figure 1 is a photograph of the appearance of the electrode material components and the metal substrate of the filter in step (c) of Example 1 of the method for separating the electrode material components and the metal substrate of the lithium-ion battery of the present invention; Figure 2 is a crystal structure diagram of the electrode material components of the electrode in step (a) of Example 1 of the method for separating the electrode material components and the metal substrate of the lithium-ion battery of the present invention and the electrode material of the filter in step (c); Figure 3 is a morphological diagram of the appearance of the electrode material components of the electrode in step (a) of Example 1 of the method for separating the electrode material components and the metal substrate of the lithium-ion battery of the present invention; and Figure 4 is a morphological diagram of the appearance of the electrode material components of the filter in step (c) of Example 1 of the method for separating the electrode material components and the metal substrate of the lithium-ion battery of the present invention.

Claims

1. A method for separating electrode material components from a metal substrate in a lithium-ion battery, comprising the following steps: immersing the lithium-ion battery electrode in a chelating solution with a temperature range of 20°C to 30°C for at least 40 minutes, wherein... The electrode of the lithium-ion battery includes a metal substrate and electrode material components disposed on the metal substrate. The chelating solution has a pH of 6 to 9 and includes a chelating agent and a pH adjuster, which are different components.

2. The method for separating the electrode material components from the metal substrate of a lithium-ion battery as described in claim 1, wherein, The soaking time is 40 to 240 minutes.

3. The method for separating the electrode material components from the metal substrate of a lithium-ion battery as described in claim 1, wherein, The chelating agent is selected from carboxylic acid chelating agents, hydroxyl chelating agents, nitrogen chelating agents, phosphate ester chelating agents, sulfur chelating agents, organometallic chelating agents, polymeric chelating agents, chelating surfactants, macrocyclic chelating agents, or any combination thereof.

4. The method for separating the electrode material components from the metal substrate of a lithium-ion battery as described in claim 3, wherein, The carboxylic acid chelating agent is selected from citric acid, citrate, oxalic acid, oxalate, tartaric acid, tartrate, lactic acid, lactate, malic acid, malate, succinic acid, succinate, gluconic acid, gluconate, or any combination thereof.

5. The method for separating the electrode material components from the metal substrate of a lithium-ion battery as described in claim 1, wherein, The pH adjuster is selected from inorganic acids, organic acids, inorganic bases, organic amine bases, ammonium compounds, metal oxides, or any combination thereof.

6. The method for separating the electrode material components from the metal substrate of a lithium-ion battery as described in claim 5, wherein, The inorganic acid is selected from boric acid, hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, hydrofluoric acid, perchloric acid, or any combination thereof.

7. The method for separating the electrode material components from the metal substrate of a lithium-ion battery as described in claim 5, wherein, The organic acid is selected from acetic acid, citric acid, formic acid, lactic acid, malic acid, tartaric acid, oxalic acid, benzoic acid, gluconic acid, or any combination thereof.

8. The method for separating the electrode material components from the metal substrate of a lithium-ion battery as described in claim 1, wherein, The electrode material composition is a cathode material composition including a cathode active material, and the cathode active material is a lithium-based oxide including lithium and at least one metal.

9. The method for separating the electrode material components from the metal substrate of a lithium-ion battery as described in claim 8, wherein, The metal in this lithium oxide is selected from iron, cobalt, manganese, or nickel.

10. A method for separating electrode material components from a metal substrate in a lithium-ion battery as described in claim 1, wherein, The electrode material composition includes an anode active material, and the anode active material is a conductive carbon material.

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