Stripping agent for battery pole piece and stripping method of stripping agent

Abstract

The invention discloses a stripping agent for a battery pole piece and a stripping method of the stripping agent, and belongs to the technical field of battery recycling. The stripping agents are phosphonic acid and derivatives thereof, the stripping liquid prepared from the stripping agents of phosphonic acid and derivatives thereof with specific structures is used for auxiliary stripping of battery pole pieces, soaking treatment is carried out on the battery pole pieces with uniform sizes obtained by crushing and grading, and then the mixture is screened to obtain aluminum foil and a positive electrode material. By utilizing the acidity and coordination of phosphonic acid and derivatives thereof, the positive electrode material is quickly stripped from the aluminum foil, and meanwhile, metal leaching is inhibited. The method can directly recover the high-purity aluminum foil and the positive electrode material, is beneficial to subsequent regeneration, and has the advantages of simple process, low cost, high recovery efficiency and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of battery recycling and reuse, and specifically relates to a stripping agent for battery pole pieces and a stripping method thereof. Background Art

[0002] The battery is a high-performance, high-safety, low-pollution energy storage device, which is widely used in new energy vehicles, 3C products, energy storage systems and other fields. The battery life is generally 5 to 10 years. With the continuous growth of the power battery and energy storage battery market, a large number of batteries will face retirement. In particular, lithium-ion batteries contain a variety of metal elements with high market value and strategic significance, such as cobalt, nickel, manganese, aluminum, copper, etc. At the same time, if the organic and fluorine-containing toxic and hazardous substances in the battery are not properly handled, it will cause serious harm to the environment. At present, battery recycling technology generally adopts direct crushing, which causes the electrode material to mix with the current collector, significantly increasing the cost of subsequent processing and causing pollution. Pre-separation of battery pole pieces is expected to reduce the cost of subsequent processing, while obtaining high-purity electrode materials and current collector products.

[0003] The battery pole piece adheres the electrode material and conductive carbon to the current collector through a binder. Organic solvents such as N-methyl-2-pyrrolidone (NMP) and Cyrene can dissolve polyvinylidene fluoride (PVDF) adhesive. For example, patent document CN102412430B provides a chemical separation method for aluminum foil in the positive electrode sheet of waste lithium-ion batteries. Ultrasonic vibration treatment is used to make the surface of the positive electrode sheet loose, and then two mixed organic solvents (N, N-dimethylacetamide and N-methylpyrrolidone) are used for heat treatment to obtain aluminum foil. However, due to limited solubility, a large amount of solvent is usually required, and effective separation can only be achieved under conditions such as heating and mechanical stirring. In addition, the aluminum foil obtained by peeling also carries a large amount of organic solvent, which is troublesome to handle later, and will produce a large amount of organic waste liquid and organic waste gas. In addition, organic solvents are usually expensive, and the materials obtained are mostly mixed materials, which has a high cost for peeling battery poles.

[0004] In order to solve the problem of post-processing difficulties of organic solvents, the prior art mostly adopts the method of alkaline solution stripping. For example, patent document CN115395122A discloses a low eutectic solvent composed of choline chloride, xylitol and deionized water. Its rich hydrogen bonds inactivate the binder and promote the rapid separation of the positive electrode material and the aluminum foil. However, the high viscosity of the low eutectic solvent may still cause solvent residue and cause separation difficulties. The positive electrode material is recovered by alkaline solution stripping. The reaction is violent and hydrogen is produced. The aluminum foil is usually corroded and a lot of wastewater is produced, and the aluminum foil cannot be effectively recovered. Patent document CN106505271A mentions that the positive electrode material is stripped by heating and keeping warm in an inert gas environment or air in steps, and then soaking in a sodium hydroxide solution. The processing time is long, and the heating and insulation require energy consumption, which will also increase the equipment cost.

[0005] Therefore, the use of acidic stripping agents to recover positive electrode materials is further selected. For example, patents CN106997972A and CN107275707A introduce an acidic stripping method to recover positive electrode materials, but the acidic stripping method has high requirements for equipment, and the positive electrode active material has a large loss due to reaction during the stripping process. Acidic stripping agents mostly use strong acids such as sulfuric acid and hydrochloric acid as stripping agents. When they are used to strip positive electrode materials, the positive electrode active material will easily react during the stripping process to produce a large loss, and thus the recovery rate of the positive electrode material is low.

[0006] In the existing stripping technology, the purity of the recycled aluminum foil and positive electrode material is low, the separation efficiency is relatively low, and there is almost no method that can separately recover the positive electrode active material and the complete aluminum foil. Therefore, it is necessary to provide a stripping agent for battery electrodes and its auxiliary stripping method to solve the above problems. Summary of the invention

[0007] One of the purposes of the present invention is to provide a stripping agent for a battery pole piece, so as to solve the problem that the positive electrode material on the battery pole piece is stripped from the aluminum foil at a slow rate and metal leaching is serious; A second object of the present invention is to provide a method for stripping battery pole pieces to solve the problem of low separation efficiency in the battery pole piece recycling process.

[0008] In a first aspect, a stripping agent for a battery electrode sheet is provided, wherein the stripping agent comprises at least one of the following structural formulas: Formula (I): ; Wherein, R1 and R2 are independently selected from hydroxyl (-OH), halogen (-X, X = F, Cl, Br, I), C1~C10 substituted or unsubstituted alkyl, C2~C10 substituted or unsubstituted unsaturated hydrocarbon group; Formula (II): ; Wherein, at least one of R3 and R4 is selected from C1-C10 substituted or unsubstituted alkyl, C2-C10 substituted or unsubstituted unsaturated hydrocarbon, hydrogen (-H), and R3 and R4 are not hydrogen (-H) at the same time; Formula (III): ; wherein m is any integer of 2≤m≤10; R5 and R6 are each independently selected from C1~C10 substituted or unsubstituted alkyl, halogen (-X, X=F, Cl, Br, I), hydroxyl (-OH), carboxyl (-COOH), nitrogen-containing group, alkoxy (-OR9, R9 is alkyl), aryl, hydrogen (-H).

[0009] As a further embodiment of the present invention, the structural formula of the nitrogen-containing group is -NR7R8, wherein R7 and R8 are independently selected from hydrogen, alkyl and oxygen.

[0010] As a further embodiment of the present invention, the C1-C10 alkyl group is an alkyl group having 1 to 10 carbon atoms, and the alkyl group may be an alkyl group having a straight chain structure, or a cyclic alkyl group, or an alkyl group having a branched chain structure; specifically, the C1-C10 alkyl group includes but is not limited to: , , , , , , , , .

[0011] As a further embodiment of the present invention, the C2-C10 unsaturated hydrocarbon group is an unsaturated hydrocarbon group having 2 to 10 carbon atoms, and the unsaturated hydrocarbon group may be an alkenyl group or a phenyl group having a cyclic structure, or an alkenyl group or a chain alkynyl group having a straight-chain structure, or an alkenyl group or an alkynyl group having a branched structure; specifically, the C2-C10 unsaturated hydrocarbon group includes but is not limited to , , , , , , , , , .

[0012] As a further embodiment of the present invention, the substituted C1-C10 alkyl and substituted C2-C10 unsaturated hydrocarbon groups are specifically alkyl or unsaturated hydrocarbon groups in which one or more hydrogen atoms are replaced by other atoms or groups (referred to as substituents), and the substituents include halogen (-X, X=F, Cl, Br, I), hydroxyl (-OH), carboxyl (-COOH), amino (-NH2), nitro (-NO2), alkoxy (-OR) or aryl; for example, a methyl group may be replaced by a chlorine atom to form a chloromethyl group (-CH2Cl), or by a carboxyl group to form a hydroxymethyl group (-CH2-COOH); The unsubstituted C1-C10 alkyl group and the unsubstituted C2-C10 unsaturated hydrocarbon group specifically refer to an alkyl group or an unsaturated hydrocarbon group in which no hydrogen atom is replaced by other atoms or groups.

[0013] In one embodiment, the stripping agent of the optional structure of formula (I) includes but is not limited to: (aminomethylphosphonic acid), (3-phosphonopropionic acid), (Ethephon), (p-phenylphosphonic acid), (octylphosphonic acid), ((1H,1H,2H,2H-perfluorodecyl)phosphonic acid), (fosetyl diethyl ether), (Tolylphosphonic acid), (2-phosphonobutane-1,2,4-tricarboxylic acid).

[0014] In one embodiment, the stripping agent of the optional formula (II) structure includes but is not limited to: (dibenzyl phosphonate), (ethanolamine phosphonate), (glycerylphosphonate), (Naphthyl phosphonate), (bis(2-ethylhexyl)phosphonate).

[0015] In one embodiment, the stripping agent of the optional formula (III) includes but is not limited to: (1,2-vinyl diphosphonic acid), (1,4-butanediphosphonic acid), (1,5-pentanediphosphonic acid), (1,6-hexamethylenediphosphonic acid), (1,10-decyl diphosphonic acid), (hydroxyethylidene diphosphonic acid), (alendronate), (diphosphonopropionic acid).

[0016] In a second aspect, a method for stripping a battery electrode sheet, using the stripping agent described in the first aspect, comprises the following steps: Step 1, breaking the positive electrode sheet of the battery to obtain positive electrode sheet fragments of uniform size; Step 2: Using water as a solvent, a stripping agent solution is prepared, and the positive electrode sheet fragments are immersed in the stripping agent solution for soaking treatment; Step 3: Filter and screen to obtain aluminum foil and positive electrode material.

[0017] As a further embodiment of the present invention, the battery pole piece is a pole piece formed by coating a lithium ion or sodium ion battery positive electrode material on an aluminum foil; further, the positive electrode material includes lithium nickel cobalt manganese oxide, lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, layered transition metal oxides, polyanion compounds or Prussian blue compounds.

[0018] As a further embodiment of the present invention, the concentration of the stripping agent solution is 1 to 100 wt %.

[0019] As a further embodiment of the present invention, the pH of the stripping agent solution is 0.5 to 7.0.

[0020] As a further solution of the present invention, the solid-liquid ratio of the positive electrode sheet fragments to the stripping agent solution is 1 g: 2 to 100 mL.

[0021] As a further embodiment of the present invention, the screening method is one or more of color sorting, density separation, magnetic separation, and vibration screening.

[0022] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention provides a stripping agent for assisting in the stripping of battery pole pieces. The stripping agent is phosphonic acid and its derivatives. The phosphonic acid and its derivative stripping agent with a specific structure utilizes its weak acidity to loosen the interface between the aluminum foil and the adhesive in the battery pole piece, causing the bonding effect to fail, thereby achieving rapid and effective separation of the aluminum foil and the electrode material. In addition, the stripping agent provided by the present invention can form a stable coordination compound on the surface of the electrode material and the aluminum foil, thereby effectively inhibiting the leaching of the metal.

[0023] 2. The present invention also provides a method for stripping battery pole pieces by using phosphonic acid and its derivative stripping agents. The method can achieve complete separation of positive electrode materials and aluminum foil. The aluminum foil and positive electrode materials have high purity, which is conducive to subsequent further recycling and treatment. The process flow is short, the separation medium can be recycled, the cost is low, the separation efficiency is high, energy saving and environmental protection are achieved, and the method has promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described below in conjunction with the accompanying drawings.

[0025] Figure 1 It is a process flow diagram of a battery pole piece stripping method of the present invention; Figure 2 1 is a morphological characterization diagram of the Ni55 ternary positive electrode material and the aluminum foil after stripping in Example 1 of the present invention, wherein (a) is a scanning electron microscope (SEM) image of the Ni55 ternary positive electrode material after stripping; (b) is an optical electron microscope image of the aluminum foil; Figure 3 1 is a diagram of element and functional group detection of the aluminum foil after peeling in Example 1 of the present invention, wherein (a) and (b) are X-ray photoelectron spectra of the aluminum foil after peeling; and (c) is a Fourier transform infrared spectrum of the aluminum foil after peeling. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Please refer to the process flow diagram of the battery pole sheet peeling method of the following embodiments and comparative examples. Figure 1 .

[0028] Example 1

[0029] A method for stripping a battery electrode using 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA) As a stripping agent, the following steps are included: Step 1: Use a shearing machine to cut the Ni55 ternary positive electrode sheet of the lithium-ion battery into uniform pieces with a length of 0.5 cm and a width of 0.5 cm; Step 2: Prepare a 2-phosphonobutane-1,2,4-tricarboxylic acid solution with a mass concentration of 10wt% and a pH value of 0.74 as a stripping agent solution, immerse 0.25g of Ni55 ternary positive electrode sheet fragments in 5mL of the stripping agent solution, and stir at a speed of 200rpm at room temperature (25-30°C) until the positive electrode material and the aluminum foil are completely separated; Step 3: After filtering, the product is sieved through a vibrating screen with a mesh size of 10 and a vibration sieving time of 3 minutes to obtain aluminum foil and a Ni55 ternary positive electrode material for a lithium-ion battery.

[0030] The stripped solution was digested with aqua regia, and the elements in the solution were quantitatively analyzed using inductively coupled plasma optical emission spectrometry (ICP-OES, iCAP PRO).

[0031] The morphology of the Ni55 ternary cathode material and aluminum foil obtained after stripping was characterized, such as Figure 2 As shown, (a) is a scanning electron microscope (SEM) image of the Ni55 ternary cathode material after stripping and (b) is an optical electron microscope image of the aluminum foil. Figure 2 It can be seen that the surface of the positive electrode material and the aluminum foil is delicate and smooth, indicating that the phosphonic acid derivative stripping agent quickly chelates and passivates on the surface of the metal material after stripping it, achieving high-purity recovery of the material.

[0032] The peeled aluminum foil is tested for elements and functional groups, such as Figure 3 As shown, (a) and (b) are X-ray photoelectron spectra of the peeled aluminum foil, and (c) is the Fourier transform infrared spectra of the peeled aluminum foil (Separated Al foil, black line in the figure) and the fresh aluminum foil (Fresh Al foil, gray line in the figure). Figure 3 It can be seen that the phosphonic acid derivative stripping agent and the hydroxyl group on the surface of the aluminum foil remove two H2O through the POH group to form Al-OP combination, and then P=O and the hydroxyl group on the surface of the aluminum foil are bonded in H + Under the action of , a H2O is removed, and finally a stable trident structure is formed. The phosphonic acid derivative realizes rapid passivation self-assembly on the surface of aluminum foil, and the binding force of the structure formed is very strong.

[0033] Example 2

[0034] A method for stripping a battery electrode sheet is different from Example 1 in that a 2-phosphonobutane-1,2,4-tricarboxylic acid solution with a mass concentration of 3wt% is used as a stripping agent solution, and the other steps and parameters remain the same.

[0035] Example 3

[0036] A method for stripping a battery electrode sheet is different from Example 1 in that a 2-phosphonobutane-1,2,4-tricarboxylic acid solution with a mass concentration of 5wt% is used as a stripping agent solution, and the other steps and parameters remain the same.

[0037] Example 4

[0038] A method for stripping a battery electrode sheet is different from Example 1 in that a 2-phosphonobutane-1,2,4-tricarboxylic acid solution with a mass concentration of 20wt% is used as a stripping agent solution, and the other steps and parameters remain the same.

[0039] Example 5

[0040] A method for stripping a battery electrode sheet is different from Example 1 in that a 2-phosphonobutane-1,2,4-tricarboxylic acid solution with a mass concentration of 30wt% is used as a stripping agent solution, and the other steps and parameters remain the same.

[0041] In Examples 1 to 5, the separation time and metal leaching rate of the Ni55 ternary positive electrode sheet were tested by using 2-phosphonobutane-1,2,4-tricarboxylic acid solution of different concentrations as the stripping agent solution. The test results are shown in Table 1: Table 1

[0042] It can be seen from Table 1 that under the same pH conditions, when different concentrations of 2-phosphonobutane-1,2,4-tricarboxylic acid solution are used as the stripping agent solution, the leaching rate of Al is less than 4%.

[0043] Example 6

[0044] A method for stripping a battery electrode sheet is different from Example 1 in that a 2-phosphonobutane-1,2,4-tricarboxylic acid solution with a mass concentration of 10wt% and a pH of 0.50 is configured as a stripping agent solution, and the remaining steps and parameters remain the same.

[0045] Example 7

[0046] A method for stripping a battery electrode sheet is different from Example 1 in that a 2-phosphonobutane-1,2,4-tricarboxylic acid solution with a mass concentration of 10wt% and a pH of 1.5 is configured as a stripping agent solution, and the remaining steps and parameters remain the same.

[0047] Example 8

[0048] A method for stripping a battery electrode sheet is different from Example 1 in that a 2-phosphonobutane-1,2,4-tricarboxylic acid solution with a mass concentration of 10wt% and a pH of 3 is configured as a stripping agent solution, and the remaining steps and parameters remain the same.

[0049] Example 9

[0050] A method for stripping a battery electrode sheet is different from Example 1 in that a 2-phosphonobutane-1,2,4-tricarboxylic acid solution with a mass concentration of 10wt% and a pH of 4 is configured as a stripping agent solution, and the remaining steps and parameters remain the same.

[0051] Example 10

[0052] A method for stripping a battery electrode sheet is different from Example 1 in that a 2-phosphonobutane-1,2,4-tricarboxylic acid solution with a mass concentration of 10wt% and a pH of 5 is configured as a stripping agent solution, and the remaining steps and parameters remain the same.

[0053] In Example 6 to Example 10, 10 wt% mass concentration of 2-phosphonobutane-1,2,4-tricarboxylic acid solution with different pH values ​​was used as a stripping agent solution to strip the Ni55 ternary positive electrode sheet. The test results of separation time and metal leaching rate are shown in Table 2: Table 2

[0054] At a determined concentration of the phosphonic acid derivative solution, concentrated hydrochloric acid or sodium hydroxide is used to adjust the pH; as can be seen from Table 2, when a 10 wt% mass concentration of 2-phosphonobutane-1,2,4-tricarboxylic acid solution with a pH of 0.74 is used as the stripping agent solution, the leaching rate of Al is relatively low, only 3.19%.

[0055] Embodiment 11

[0056] A method for stripping a battery pole piece using 2-phosphonobutane-1,2,4-tricarboxylic acid As a stripping agent, the following steps are included: Step 1: Use a shearing machine to cut the NCM811 lithium-ion battery ternary positive electrode sheet into uniform pieces with a length of 0.5 cm and a width of 0.5 cm; Step 2: Prepare a 3wt% 2-phosphonobutane-1,2,4-tricarboxylic acid solution with a pH value of 0.74 as a stripping agent solution, immerse 0.25g of NCM811 ternary cathode sheet fragments in 5mL of the stripping agent solution, and stir at 200rpm at room temperature until the cathode material is completely separated from the aluminum foil; Step 3: After filtering, the product is sieved through a vibrating screen with a mesh size of 10 and a vibration sieving time of 3 minutes to obtain aluminum foil and lithium-ion battery NCM811 ternary positive electrode material.

[0057] Example 12

[0058] A method for stripping a battery electrode, which differs from Example 11 in that a 2-phosphonobutane-1,2,4-tricarboxylic acid solution with a mass concentration of 5wt% is used as a stripping agent solution, and the remaining steps and parameters remain the same.

[0059] Example 13

[0060] A method for stripping a battery electrode, which differs from Example 11 in that a 2-phosphonobutane-1,2,4-tricarboxylic acid solution with a mass concentration of 7wt% is used as a stripping agent solution, and the remaining steps and parameters remain the same.

[0061] Embodiment 14

[0062] A method for stripping a battery electrode, which differs from Example 11 in that a 2-phosphonobutane-1,2,4-tricarboxylic acid solution with a mass concentration of 10wt% is used as a stripping agent solution, and the other steps and parameters remain the same.

[0063] Embodiment 15

[0064] A method for stripping a battery electrode, which differs from Example 11 in that a 2-phosphonobutane-1,2,4-tricarboxylic acid solution with a mass concentration of 20wt% is used as a stripping agent solution, and the other steps and parameters remain the same.

[0065] Example 16

[0066] A method for stripping a battery electrode, which differs from Example 11 in that a 2-phosphonobutane-1,2,4-tricarboxylic acid solution with a mass concentration of 30wt% is used as a stripping agent solution, and the remaining steps and parameters remain the same.

[0067] Embodiment 17

[0068] A method for stripping a battery electrode, which differs from Example 11 in that a 2-phosphonobutane-1,2,4-tricarboxylic acid solution with a mass concentration of 40wt% is used as a stripping agent solution, and the remaining steps and parameters remain the same.

[0069] In Examples 11 to 17, the separation time and metal leaching rate of NCM811 ternary positive electrode sheets were tested by using 2-phosphonobutane-1,2,4-tricarboxylic acid solutions of different concentrations as stripping agent solutions. The test results are shown in Table 3: Table 3

[0070] It can be seen from Table 3 that when a 2-phosphonobutane-1,2,4-tricarboxylic acid solution with a mass concentration of 20wt% is used as the stripping agent solution, the stripping time for stripping the NCM811 ternary cathode sheet is the shortest, and the stripping of Ni, Co, Mn and Al is achieved in 2.5min, and the leaching rate is also relatively low.

[0071] Embodiment 18

[0072] A method for stripping a battery pole piece using 1,2-vinyl diphosphonic acid As a stripping agent, a 1,2-vinyl diphosphonic acid solution with a mass concentration of 10 wt % and a pH of 0.74 was prepared as a stripping agent solution for auxiliary stripping, and the remaining steps and parameters were consistent with those in Example 1.

[0073] Embodiment 19

[0074] A method for stripping a battery pole piece using 3-phosphonopropionic acid As a stripping agent, a 3-phosphonopropionic acid solution with a mass concentration of 10 wt % and a pH of 0.74 was prepared as a stripping agent solution for auxiliary stripping, and the remaining steps and parameters were consistent with those in Example 1.

[0075] Embodiment 20

[0076] A method for stripping a battery pole piece using diethylphosphonic acid As a stripping agent, a diethylphosphonic acid solution with a mass concentration of 10 wt % and a pH of 0.74 was prepared as a stripping agent solution for auxiliary stripping, and the remaining steps and parameters were consistent with those in Example 1.

[0077] Embodiment 21

[0078] A method for stripping a battery pole piece using glycerol phosphonate As a stripping agent, a glycerol phosphonate solution with a mass concentration of 10 wt % and a pH of 0.74 was prepared as a stripping agent solution for auxiliary stripping, and the remaining steps and parameters were consistent with those in Example 1.

[0079] Embodiment 22

[0080] A method for stripping a battery pole piece using di(2-ethylhexyl)phosphonate As a stripping agent, a di(2-ethylhexyl)phosphonate solution with a mass concentration of 10 wt % and a pH of 0.74 was prepared as a stripping agent solution for auxiliary stripping, and the remaining steps and parameters were consistent with those in Example 1.

[0081] Embodiment 23

[0082] A method for stripping a battery pole piece using hydroxyethylidene diphosphonic acid As a stripping agent, a 10 wt % hydroxyethylidene diphosphonic acid solution with a pH of 0.74 was prepared as a stripping agent solution for auxiliary stripping, and the remaining steps and parameters were consistent with those in Example 1.

[0083] Comparative Example 1

[0084] A method for stripping a battery electrode sheet is different from that of Example 1 in that a stripping agent solution is prepared by dissolving dimethylacetamide in a dimethyl carbonate solution to obtain a dimethylacetamide organic solution with a mass concentration of 10 wt %, and the remaining steps and parameters remain the same.

[0085] Comparative Example 2

[0086] A method for stripping a battery electrode, which differs from Example 1 in that the stripping agent solution is a mixed solution with a mass concentration of 10wt% and a pH of 0.74 obtained by configuring oxalic acid and potassium dihydrogen phosphate in a weight ratio of 3:2, and the other steps and parameters remain the same.

[0087] Comparative Example 3

[0088] A method for stripping a battery electrode sheet is different from that of Example 1 in that a stripping agent solution uses a hydrochloric acid solution with a mass concentration of 10wt% and a pH of 0.74, and other steps and parameters remain the same.

[0089] Comparative Example 4

[0090] A method for stripping a battery electrode sheet is different from that of Example 1 in that a stripping agent solution uses a phosphoric acid solution with a mass concentration of 10wt% and a pH of 0.74, and other steps and parameters remain the same.

[0091] Comparative Example 5

[0092] A method for stripping a battery electrode sheet is different from that of Example 1 in that the stripping agent solution uses an oxalic acid solution with a mass concentration of 10wt% and a pH of 0.74, and the other steps and parameters remain the same.

[0093] The separation time and metal leaching rate test results of Examples 18 to 23 and Comparative Examples 1 to 5 using phosphonic acid derivatives of different structures and inorganic acids as stripping agents for stripping Ni55 ternary positive electrode sheets are shown in Table 4: Table 4

[0094] As can be seen from Table 4, the present invention uses phosphonic acid and its derivatives as stripping agents to assist in stripping the positive electrode sheet of the battery, which has excellent stripping performance. This is attributed to the coordination effect of phosphonic acid and its derivatives with metal ions, forming a passivation layer on the surface of the aluminum foil, causing the bonding effect to fail, prompting the positive electrode material to be quickly stripped from the aluminum foil, while inhibiting metal leaching.

[0095] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0096] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A stripping agent for a battery electrode, characterized in that: The stripping agent comprises at least one of the following structural formulas: Formula (I): ; Wherein, R1 and R2 are independently selected from hydroxyl, halogen, C1-C10 substituted or unsubstituted alkyl, C2-C10 substituted or unsubstituted unsaturated hydrocarbon group; Formula (II): ; wherein at least one of R3 and R4 is selected from C1-C10 substituted or unsubstituted alkyl, C2-C10 substituted or unsubstituted unsaturated hydrocarbon, hydrogen, and R3 and R4 are not hydrogen at the same time; Formula (III): , wherein m is any integer of 2≤m≤10; R5 and R6 are each independently selected from C1~C10 substituted or unsubstituted alkyl, halogen, hydroxyl, carboxyl, nitrogen-containing group, alkoxy, aryl, and hydrogen.

2. A stripping agent for a battery electrode according to claim 1, characterized in that: The C1-C10 alkyl group is an alkyl group having 1 to 10 carbon atoms, and the alkyl group includes an alkyl group having a straight-chain structure, a cyclic alkyl group, and an alkyl group having a branched structure.

3. The stripping agent for battery pole pieces according to claim 1, characterized in that: The C2-C10 unsaturated hydrocarbon group is an unsaturated hydrocarbon group having 2 to 10 carbon atoms, and the unsaturated hydrocarbon group includes alkenyl and phenyl groups having a cyclic structure, alkenyl and chain alkynyl groups having a straight-chain structure, and alkenyl and alkynyl groups having a branched structure.

4. The stripping agent for battery pole pieces according to claim 1, characterized in that: The structural formula of the nitrogen-containing group is -NR7R8, wherein R7 and R8 are independently selected from hydrogen, alkyl and oxygen.

5. A method for stripping a battery electrode, characterized in that: Using the stripping agent according to any one of claims 1 to 4 comprises the following steps: Step 1, breaking the positive electrode sheet of the battery to obtain positive electrode sheet fragments of uniform size; Step 2: prepare a stripping agent solution, and immerse the positive electrode sheet fragments in the stripping agent solution for soaking treatment; Step 3: Filter and screen to obtain aluminum foil and positive electrode material.

6. A battery electrode stripping method according to claim 5, characterized in that: The battery pole piece is a pole piece formed by coating a lithium ion or sodium ion battery positive electrode material on aluminum foil.

7. A battery pole sheet stripping method according to claim 5, characterized in that: The concentration of the stripping agent solution is 1 to 100 wt %.

8. A battery electrode stripping method according to claim 5, characterized in that: The pH of the stripping agent solution is 0.5 to 7.

0.

9. A battery pole sheet stripping method according to claim 5, characterized in that: The solid-to-liquid ratio of the positive electrode fragments to the stripping agent solution is 1 g: 2 to 100 mL.

10. A battery electrode stripping method according to claim 5, characterized in that: The screening method is one or more of color sorting, density separation, magnetic separation, and vibration screening.

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