Positive electrode plate and method for manufacturing electrode material

Abstract

The present invention provides a positive electrode plate, and a method for manufacturing an electrode material. A method for recycling a positive electrode plate and a positive electrode material provided with the positive electrode plate is provided. The positive electrode plate disclosed herein includes a current collector foil, and a positive electrode mixture layer including a positive electrode active material, and a water-soluble adhesive layer including a water-soluble adhesive and a conductive material is present between the current collector foil and the positive electrode mixture layer.

Description

Technical Field

[0001] This disclosure relates to a positive electrode plate and a method for manufacturing electrode materials. Background Technology

[0002] In recent years, due to environmental concerns, the reprocessing (recycling) of valuable metals such as Li, Ni, and Co from the positive electrode active materials of secondary batteries has been developing. In the reprocessing of valuable metals from positive electrode active materials, the current collector foil is peeled off from the positive electrode composite layer, and the valuable metals are recovered from the positive electrode composite layer. However, typical positive electrode composite layers contain binders such as polyvinylidene fluoride (PVdF), making peeling from the current collector foil difficult. Therefore, a scheme has been proposed to dissolve the binder in a solvent during the peeling of the current collector foil from the positive electrode composite layer (e.g., Patent Document 1).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 10-255862 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] However, the solvents that dissolve the adhesives in the positive electrode composite layer have a high environmental impact and are difficult to dispose of. Furthermore, if the solvent does not sufficiently impregnate the composite layer, poor peeling can occur, leading to a reduced recovery rate of the positive electrode composite.

[0008] This disclosure was made in view of the above-mentioned circumstances, and its purpose is to provide a technique for easily peeling the current collector foil from the positive electrode composite layer using solvents with low environmental impact.

[0009] Methods for solving problems

[0010] The positive electrode plate disclosed herein includes: a current collector foil, and a positive electrode composite layer applied to the current collector foil, wherein a water-soluble adhesive layer comprising a water-soluble adhesive and a conductive material is present between the current collector foil and the positive electrode composite layer.

[0011] The positive electrode plate described above has a water-soluble adhesive layer between the current collector foil and the positive electrode composite layer. This water-soluble adhesive layer contains a water-soluble binder, thus allowing it to be easily dissolved by aqueous solvents. Furthermore, if the water-soluble adhesive layer dissolves, it becomes the starting point for peeling off the current collector foil and the positive electrode composite layer. Therefore, this positive electrode plate can use an aqueous solvent as the solvent for peeling. As described above, according to the positive electrode plate disclosed herein, the current collector foil and the positive electrode composite layer can be easily peeled off using solvents with low environmental impact. Attached Figure Description

[0012] Figure 1 A cross-sectional view of a positive electrode plate according to one embodiment is shown schematically.

[0013] Figure 2 The figure is used to schematically illustrate a method for manufacturing an electrode material according to one embodiment.

[0014] Figure 3 This diagram schematically illustrates one embodiment of the stripping process in a method for manufacturing an electrode material according to an embodiment.

[0015] Figure 4 This diagram schematically illustrates one embodiment of the recycling process in a method for manufacturing electrode materials according to an embodiment. Detailed Implementation

[0016] Several embodiments of the technology disclosed herein will be described below with reference to the accompanying drawings. In the following drawings, components and parts that perform the same function are labeled with the same reference numerals. Furthermore, the dimensional relationships (length, width, thickness, etc.) in the drawings do not reflect actual dimensional relationships. It should be noted that matters necessary for implementing the technology disclosed herein, other than those specifically mentioned in this specification (e.g., general configuration and manufacturing methods of energy storage devices not characteristic of this disclosure), can be grasped by those skilled in the art based on prior art. The technology disclosed herein can be implemented based on the content disclosed in this specification and common technical knowledge in the field. Furthermore, the following description is not intended to limit this disclosure to the following forms.

[0017] In this specification, the notation "A~B" indicating a range means "above A and below B". It also includes the meanings of "above A" and "below B". Furthermore, in this specification, the term "energy storage device" refers to a device capable of charging and discharging. Energy storage devices include primary batteries, secondary batteries (such as non-aqueous electrolyte secondary batteries like lithium-ion batteries and nickel-metal hydride batteries), and capacitors (physical batteries) such as double-layer capacitors.

[0018] 1. Positive electrode plate

[0019] like Figure 1 As shown, the positive electrode plate 22 includes a current collector foil 22c and a positive electrode composite layer 22a applied to the current collector foil 22c. Furthermore, a water-soluble adhesive layer 22b comprising a water-soluble adhesive 24 and a conductive material 25 is present between the current collector foil 22c and the positive electrode composite layer 22a. According to this positive electrode plate 22, the current collector foil 22c and the positive electrode composite layer 22a can be easily peeled off using solvents with low environmental impact. This will be described in detail below.

[0020] (1) Current collector foil

[0021] The current collector foil 22c is a strip-shaped conductive component. The current collector foil 22c can be made of conductive metals such as aluminum, aluminum alloy, nickel, or stainless steel. A preferred example of the current collector foil 22c is aluminum foil.

[0022] Furthermore, there is no particular limitation on the average thickness of the current collector foil 22c. For example, 2 μm to 30 μm is preferred, 2 μm to 20 μm is more preferred, and 5 μm to 15 μm is even more preferred.

[0023] (2) Positive electrode composite layer

[0024] The positive electrode composite layer 22a is a thin layer applied to the current collector foil 22c. The positive electrode composite layer 22a can be formed on one side or both sides of the current collector foil 22c. The positive electrode composite layer 22a contains a positive electrode active material 23. The positive electrode active material 23 is a material capable of reversibly absorbing and releasing charge carriers. This positive electrode active material 23 contains at least one valuable metal of Li, Ni, Co, and Mn. Examples of positive electrode active materials 23 include LiCoO2, LiNiO2, LiFeO2, and LiNiO2. 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (NCM), LiNi 0.5 Mn 1.5 O4, LiNi 0.8 Co 0.15 Al 0.05 O2 (NCA), LiCrMO4, LiMn2O4, LiFePO4 (LFP), etc. Furthermore, these positive electrode active materials 23 can be used individually or in combination of two or more.

[0025] The positive electrode composite layer 22a preferably contains a water-insoluble adhesive. In this specification, a water-insoluble adhesive refers to an adhesive with a solubility of 3.0 / 100g or less in water at 23°C and 1 atmosphere. This suppresses the peeling of the current collector foil 22c from the positive electrode composite layer 22a. On the other hand, the positive electrode composite layer 22a containing a water-insoluble adhesive is difficult to peel from the current collector foil 22c, thus becoming a major cause of reduced efficiency in the remanufacturing of valuable metals. However, according to the technology disclosed herein, since the water-soluble adhesive layer 22b (described later) serves as the starting point for peeling, the positive electrode composite layer 22a containing the water-insoluble adhesive can be easily peeled off. Examples of water-insoluble adhesives include polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), and styrene-butadiene rubber (SBR).

[0026] The positive electrode composite layer 22a may contain any component other than the positive electrode active material 23 and a non-water-soluble binder. Examples of such components include conductive material 25. For example, carbon materials such as acetylene black (AB) can be used as conductive material 25. Examples of conductive material 25 include carbon black such as acetylene black (AB), carbon nanotubes such as single-layer carbon nanotubes (SWCNTs), double-layer carbon nanotubes (DWCNTs), and multi-layer carbon nanotubes (MWCNTs), and carbon fibers. Among these, acetylene black or carbon nanotubes are preferred.

[0027] Furthermore, the composition of the positive electrode composite layer 22a can be appropriately changed according to the type of secondary battery being applied. For example, when the total solid content of the positive electrode composite layer 22a is set to 100% by mass, the positive electrode active material 23 can account for approximately 80% by mass or more, typically 90% by mass or more, for example, 95% by mass or more. On the other hand, from the viewpoint of sufficiently ensuring the content of other components (non-water-soluble binder, conductive material 25, etc.), the content of the positive electrode active material 23 is preferably 99.8% by mass or less, preferably 99.5% by mass or less, preferably 99% by mass or less, and preferably 98% by mass or less.

[0028] (3) Water-soluble adhesive layer

[0029] The water-soluble adhesive layer 22b is a layer existing between the current collector foil 22c and the positive electrode composite layer 22a. This water-soluble adhesive layer 22b comprises a water-soluble adhesive 24 and a conductive material 25. The water-soluble adhesive layer 22b uses the water-soluble adhesive 24 to bond the current collector foil 22c to the positive electrode composite layer 22a. Furthermore, since the water-soluble adhesive layer 22b contains the conductive material 25, a conductive path can be formed between the current collector foil 22c and the positive electrode composite layer 22a. This water-soluble adhesive layer 22b is easily dissolved by supplying an aqueous solvent. Therefore, the water-soluble adhesive layer 22b becomes the starting point for peeling, thus allowing the current collector foil 22c to be easily peeled from the positive electrode composite layer 22a. Therefore, the positive electrode plate 22 according to this embodiment can easily peel the current collector foil 22c from the positive electrode composite layer 22a even when using a solvent with low environmental impact. The following is a detailed description of the water-soluble adhesive layer 22b.

[0030] In this specification, a water-soluble adhesive refers to an adhesive with a solubility of 17.0 / 100g or more in water at 23°C and 1 atmosphere. The water-soluble adhesive 24 is preferably, for example, a polyacrylamide-based adhesive. The polyacrylamide-based adhesive disclosed herein refers to a water-soluble polymer containing 50% by mass or more of repeating units derived from (meth)acrylamide relative to 100 parts by mass of all repeating units. This water-soluble polymer may contain repeating units derived from (meth)acrylamide, in addition to repeating units derived from ...

[0031] Examples of polyacrylamide-based water-soluble adhesives include polyacrylamide, polymethacrylamide, poly(N-isopropylacrylamide), poly(N,N-dimethylacrylamide), poly(N,N-dimethylmethacrylamide), poly(N,N-diethylacrylamide), poly(N,N-diethylmethacrylamide), poly(N,N-dimethylaminopropylacrylamide), poly(N,N-dimethylaminopropylmethacrylamide), poly(N-hydroxymethylacrylamide), poly(N-hydroxymethylmethacrylamide), and poly(diacetone acrylate). Polyacrylamide (PA) is a water-soluble adhesive that can be used alone or in combination with other PAs, such as poly(maleamide), poly(acryloylamino tert-butylsulfonic acid), poly(acryloylmorpholine), poly(N-phenylacrylamide), poly(N-phenylmethylacrylamide), poly(N-ethyl-o-crotonyltoluidine), poly(N-(4-hydroxyphenyl)acrylamide), poly(N-(4-hydroxyphenyl)methylacrylamide), poly(dimethylaminopropyl(meth)acrylamide), poly(dimethylaminopropyl(meth)acrylamide) methyl quaternary salt chloride), and poly(N-(3-dimethylaminopropyl)methylacrylamide).

[0032] Furthermore, the water-soluble adhesive 24 can be any material that can be used as an adhesive and has high water solubility, and is not limited to the polyacrylamide-based water-soluble adhesives mentioned above. For example, it can be polyacrylic acid-based, polyvinyl alcohol-based, polyvinylpyrrolidone-based, polyvinyl alcohol-based, or polyethylene oxide-based adhesives.

[0033] The content of water-soluble adhesive 24 in the water-soluble adhesive layer 22b is preferably 10% by mass or more, more preferably 20% by mass or more, and particularly preferably 40% by mass or more, when the total solid content of the water-soluble adhesive layer 22b is set to 100% by mass. This allows for suitable bonding of the current collector foil 22c to the positive electrode composite layer 22a. On the other hand, by increasing the amount of water-soluble adhesive added, the amount of conductive material 25 (described later) can potentially be relatively reduced. Therefore, the content of water-soluble adhesive 24 in the water-soluble adhesive layer 22b is preferably 90% by mass or less, particularly preferably 80% by mass or less, and particularly preferably 50% by mass or less.

[0034] As described above, the water-soluble adhesive layer 22b contains a conductive material 25 in addition to the water-soluble adhesive 24. This ensures the conductivity between the current collector foil 22c and the positive electrode composite layer 22a. Furthermore, regarding the conductive material 25 of the water-soluble adhesive layer 22b, conventionally known conductive materials that can be used in the positive electrode composite layer 22a can be used without particular limitation. That is, examples of the conductive material 25 for the water-soluble adhesive layer 22b include carbon black such as acetylene black (AB), carbon nanotubes such as single-layer carbon nanotubes (SWCNT), double-layer carbon nanotubes (DWCNT), and multi-layer carbon nanotubes (MWCNT), and carbon fibers. Moreover, the conductive material 25 of the water-soluble adhesive layer 22b can be the same as or different from the conductive material of the positive electrode composite layer 22a.

[0035] When the total solid content of the water-soluble adhesive layer 22b is set to 100% by mass, the amount of conductive material 25 added is preferably 10% by mass or more, more preferably 20% by mass or more, and particularly preferably 50% by mass or more. This allows for optimal performance in areas such as output. On the other hand, if the amount of conductive material 25 added to the water-soluble adhesive layer 22b is increased, the amount of water-soluble adhesive 24 added may be relatively reduced. Therefore, the amount of conductive material 25 added to the water-soluble adhesive layer 22b is preferably 90% by mass or less, more preferably 80% by mass or less, and particularly preferably 60% by mass or less.

[0036] Furthermore, the water-soluble adhesive layer 22b may not be formed on the entire surface of the current collector foil 22c. When the entire surface area of ​​the current collector foil 22c is set to 100%, the coating area of ​​the water-soluble adhesive layer 22b can be 60% or more. Even in this case, the effects of the technology disclosed herein can be fully utilized. Furthermore, from the viewpoint of more preferably utilizing the effects of the technology disclosed herein, the coating area of ​​the water-soluble adhesive layer 22b is preferably 70% or more, more preferably 85% or more, and particularly preferably 90% or more. On the other hand, there is no particular upper limit on the coating area of ​​the water-soluble adhesive layer 22b, and it can be the entire surface of the current collector foil 22c (100%).

[0037] The thickness of the water-soluble adhesive layer 22b is preferably 0.5 μm or more, more preferably 0.7 μm or more, and particularly preferably 1 μm or more. This ensures the strength of the water-soluble adhesive layer 22b, effectively bonding the current collector foil 22c to the positive electrode composite layer 22a. On the other hand, the thickness of the water-soluble adhesive layer 22b is preferably 3 μm or less, more preferably 2.5 μm or less, and particularly preferably 2 μm or less. As the water-soluble adhesive layer 22b becomes thinner, dissolution due to water supply becomes easier, thus facilitating the peeling of the current collector foil 22c from the positive electrode composite layer 22a.

[0038] 2. Manufacturing method of electrode material

[0039] Secondly, a method for reproducing electrode materials using the technology disclosed herein (hereinafter referred to as the "electrode material manufacturing method") will be described. For example... Figure 2 As shown, the method for manufacturing the electrode material according to this embodiment includes: a preparation step S10 for preparing the positive electrode plate 22 configured as described above; a peeling step S20 for peeling the positive electrode composite layer 22a by supplying water to the positive electrode plate 22, starting from the water-soluble adhesive layer 22b; and a recycling step S30 for recovering the electrode material from the positive electrode composite layer 22a. Each step will be described below.

[0040] (1) Preparation process S10

[0041] In preparation step S10, a positive electrode plate 22 is prepared as the object of electrode material recycling. The positive electrode plate 22 prepared here is the positive electrode plate with the above-described structure. To avoid repetition, a detailed description of the structure of the positive electrode plate 22 is omitted. Furthermore, there are no particular limitations on the means of preparing the positive electrode plate 22. The positive electrode plate 22 can be a product from the disassembly and recycling of a used secondary battery, or it can be a defective product or process waste discarded during the manufacturing of a secondary battery.

[0042] (2) Stripping process S20

[0043] In the peeling process S20, the positive electrode composite layer 22a is peeled off from the current collector foil 22c. As described above, in the positive electrode plate 22 according to this embodiment, the current collector foil 22c and the positive electrode composite layer 22a are bonded together by a water-soluble adhesive layer 22b. Therefore, if the water-soluble adhesive layer 22b is dissolved in an aqueous solvent, the positive electrode composite layer 22a can be easily peeled off starting from this water-soluble adhesive layer 22b.

[0044] Furthermore, the stripping process S20, such as Figure 3 As shown, the preferred process includes a crushing step S21, a water immersion step S22, and a sorting step S23. This allows for efficient peeling of the positive electrode composite layer 22a from the current collector foil 22c.

[0045] (2-1) Crushing process S21

[0046] Specifically, the crushing step S21 crushes the positive electrode plate 22 recovered in the preparation step S10. This improves the immersion efficiency in the subsequent immersion step S22. Furthermore, there are no particular limitations on the method of crushing the positive electrode plate 22, and conventionally known crushing methods can be used.

[0047] (2-2) Soaking process S22

[0048] In the immersion step S22, the broken positive electrode plate 22 is immersed in an aqueous solvent. As a result, the water-soluble adhesive layer 22b dissolves, allowing the positive electrode composite layer 22a to be easily peeled off from the current collector foil 22c. Furthermore, the "aqueous solvent" used in this step refers to a liquid medium with water as its main component. Examples of such aqueous media include distilled water, ion-exchanged water, pure water, and ultrapure water. Moreover, the aqueous medium may contain components other than water, as long as it does not significantly hinder the effect of the disclosed technology (li leaching from the positive electrode active material). For example, a mixture of water and an organic solvent soluble in that water (such as ethanol or other alcohols) can also be used as the aqueous medium. Furthermore, considering the dissolution efficiency for the water-soluble adhesive layer 22b, it is preferable that the content of organic solvent in the aqueous medium is low. For example, the content of organic solvent relative to the total weight (100wt%) of the aqueous medium is preferably 8.0wt% or less, more preferably 2.0wt% or less, even more preferably 0.1wt% or less, and particularly preferably 0.05wt% or less.

[0049] Furthermore, in this process, it is preferable to stir the positive electrode plate 22 and the aqueous solvent. This improves the peeling efficiency of the positive electrode composite layer 22a. There are no particular limitations on the stirring method; conventionally known stirring methods can be used. Moreover, the stirring speed is preferably 500 to 2000 rpm. This further improves the peeling efficiency. Additionally, the temperature of the aqueous solvent used in the stirring is preferably below 100 degrees Celsius (preferably 20°C to 40°C).

[0050] (2-3) Sorting process S23

[0051] In the sorting step S23, the aqueous solvent from the soaking step S22 is passed through a sieve with a mesh size of a specified size. The mesh size of the sieve in this step is set to allow the separated positive electrode composite layer 22a to pass through while capturing the current collector foil 22c. This allows for easy separation of the current collector foil 22c and the positive electrode composite layer 22a. Furthermore, the specific mesh size of the sieve is preferably adjusted appropriately based on the conditions of the crushing step S21 and the stirring step described above.

[0052] (3) Recycling process S30

[0053] The recycling step S30 recovers the electrode material from the positive electrode composite layer 22a. There are no particular limitations on the specific recycling method used in this step; conventionally known recycling methods can be used without restriction. For example, the recycling step S30 is preferably as follows: Figure 4 As shown, it includes a dehydration process S31 and a firing process S32.

[0054] (3-1) Dehydration process S31

[0055] In the dewatering step S31, the positive electrode composite layer 22a recovered in the stripping step S20 is dewatered. This removes the water-soluble binder components, thereby suppressing the generation of carbon dioxide from the water-soluble binder and reducing energy consumption during firing. Furthermore, there are no particular limitations on the specific method used in this step, and conventionally known dewatering methods can be used without restriction. For example, a filter press can be used as this dewatering method.

[0056] (3-2) Firing process S32

[0057] In the firing process S32, the dehydrated positive electrode composite layer 22a is fired. This removes binders, conductive materials, moisture, etc., from the positive electrode composite layer 22a. As a result, electrode materials (valuable metals such as Li, Ni, Co, and Mn) can be recycled from the positive electrode plate 22. Furthermore, the firing temperature and firing time are preferably adjusted appropriately according to the composition of the positive electrode composite layer 22a. For example, the firing temperature is preferably 400–600°C. Additionally, the firing time is preferably 24–48 hours.

[0058] Furthermore, the sintered electrode material sometimes contains impurities such as Al, Al₂O₃, and Al(OH)O. These impurities are approximately 700 μm in size. On the other hand, the size of the valuable metals after sintering is approximately 150 μm. Therefore, it is preferable to pass the electrode material through a sieve with a mesh size of approximately 300 μm. This allows for the recovery (reproduction) of valuable metals with higher purity.

[0059] Evaluation

[0060] 1. Experimental Example

[0061] The following describes test examples related to the technology disclosed herein, but it is not intended to limit the technology disclosed herein to these test examples.

[0062] Examples 1-9

[0063] [Making the positive electrode plate]

[0064] Here, firstly, a water-soluble adhesive layer forming paste is prepared. Specifically, a water-soluble adhesive layer forming paste is prepared by mixing a water-soluble adhesive (polyacrylamide), a conductive material (acetylene black), and an aqueous medium (pure water). It should be noted that in Examples 1 to 9, the compositions of the water-soluble adhesive and the conductive material are different as shown in Table 1.

[0065] Secondly, a paste for forming the positive electrode composite layer was formed. This paste was prepared by mixing lithium nickel cobalt manganese composite oxide (NCM) as the positive electrode active material, polyvinylidene fluoride (PVdF) as the binder, acetylene black (AB) as the conductive material, and N-methyl-2-pyrrolidone (NMP). It should be noted that the mixing ratio of the positive electrode active material, binder, and conductive material was set to 97.5:1.5:1.

[0066] Next, a water-soluble adhesive layer forming paste is applied to the current collector foil (aluminum foil, 12 μm). The paste is then dried to form a 120 μm thick water-soluble adhesive layer on the surface of the current collector foil. Next, a positive electrode composite layer forming paste is applied to the surface of the water-soluble adhesive layer to achieve a thickness of 120 μm. The positive electrode composite layer is then dried to form the positive electrode composite layer. Finally, the positive electrode plate is obtained by pressing and processing to the specified dimensions.

[0067] (2) Comparative Example 1

[0068] In Comparative Example 1, a positive electrode plate was fabricated under the same conditions as in Examples 1 to 9, except that no water-soluble adhesive was added to the layer between the current collector foil and the positive electrode composite layer.

[0069] (3) Comparative Example 2

[0070] In Comparative Example 2, a positive electrode plate was fabricated under the same conditions as in Examples 1 to 9, except that no conductive material was added to the layer between the current collector foil and the positive electrode composite layer.

[0071] (4) Comparative Example 3

[0072] In Comparative Example 3, a positive electrode plate was fabricated under the same conditions as Examples 1-9 and Comparative Examples 1-2, except that no intermediate layer was formed between the current collector foil and the positive electrode composite layer.

[0073] 2. Evaluation Test

[0074] (1) Peel strength test

[0075] In this experiment, a peel strength test was performed on the positive electrode composite layer of the fabricated positive electrode plate. Specifically, a 90-degree peel strength test was performed according to JIS C6481 (1996). Then, the peel strength of Comparative Example 3 was set to 100%, and the peel strength ratios of each example were calculated. The results are shown in Table 1.

[0076] (2) Normal temperature output test

[0077] Secondly, using the fabricated positive electrode plate, an experimental lithium-ion secondary battery was constructed. For the negative electrode plate, a product was used to impart a negative electrode composite layer to the surface of a copper current collector foil. Furthermore, the negative electrode composite layer used a product that mixed a negative electrode active material layer (graphite) and a binder (CMC, SBR) in a 98:1:1 ratio. Additionally, for the electrolyte, a product that mixed EC, DMC, and EMC in a 30:30:40 ratio was used.

[0078] Then, after charging the test battery to 50% SOC, it was discharged at 150A for 10 seconds at 25°C, and the discharge resistance was measured. Then, the room temperature output of Comparative Example 3 was set to 100%, and the ratio of room temperature output for each example was calculated.

[0079] (3) Recovery rate of valuable metals

[0080] In this experiment, valuable metals were recovered following the steps described in "2. Method for Manufacturing Electrode Materials" above. Furthermore, the crushing process was set such that the long side of the crushed positive electrode foil was less than 20 mm. The immersion process was set such that the immersion time was 30 minutes, the temperature was 25°C, and the rpm was 50 rpm. For the dehydration process, suction filtration was performed at a pressure of 0.5 kPa. The calcination process was set such that the temperature was 500°C and the calcination time was 1 hour. The recovery rate of valuable metals was measured based on the calcined electrode material. This "recovery rate of valuable metals" was determined based on ICP analysis.

[0081] Table 1

[0082]

[0083] The results above confirm that Examples 1-9 all achieved high levels of peel strength ratio, room temperature output ratio, and recovery rate after washing. This demonstrates that by using a water-soluble adhesive layer containing water-soluble binder and conductive material between the current collector foil and the positive electrode composite layer, a positive electrode plate with easily recoverable valuable metals can be achieved without significantly reducing battery performance.

[0084] The above-described specific embodiments are merely illustrative and do not limit the scope of the claims. The technology described in the claims includes technical solutions that have undergone various modifications and alterations to the embodiments described above.

[0085] As described above, the disclosures set forth in the following items are included in this specification.

[0086] Item 1:

[0087] A positive electrode plate includes: a current collector foil and a positive electrode composite layer applied to the current collector foil, wherein a water-soluble adhesive layer comprising a water-soluble adhesive and a conductive material is present between the current collector foil and the positive electrode composite layer.

[0088] Item 2:

[0089] According to the positive electrode plate of item 1, the water-soluble adhesive is polyacrylamide-based.

[0090] Item 3:

[0091] According to item 1 or 2, the positive electrode plate contains 20 to 70 wt% of the water-soluble binder.

[0092] Item 4:

[0093] The positive electrode plate according to any one of items 1 to 3, wherein the conductive material is acetylene black or carbon nanotubes.

[0094] Item 5:

[0095] The positive electrode plate according to any one of claims 1 to 4, wherein the thickness of the water-soluble adhesive layer is 0.5 to 3 μm.

[0096] Item 6:

[0097] The positive electrode plate according to any one of claims 1 to 5, wherein the positive electrode composite layer comprises a non-water-soluble adhesive.

[0098] Item 7:

[0099] A method for manufacturing an electrode material, comprising: a step of preparing a positive electrode plate according to any one of claims 1 to 6; a step of peeling off the positive electrode composite layer starting from the water-soluble adhesive layer by supplying water to the positive electrode plate; and a step of recovering the electrode material from the positive electrode composite layer.

[0100] Explanation of reference numerals in the attached figures

[0101] 22 Positive electrode plate

[0102] 22a Positive electrode composite layer

[0103] 22b Water-soluble adhesive layer

[0104] 22c current collector foil

[0105] 23 Positive electrode active material

[0106] 24 Water-soluble adhesives

[0107] 25. Conductive materials

[0108] 26 Adhesives

[0109] 27 Water

Claims

1. A positive electrode plate, comprising: The current collector foil and the positive electrode composite layer applied to the current collector foil, wherein a water-soluble adhesive layer comprising a water-soluble adhesive and a conductive material exists between the current collector foil and the positive electrode composite layer.

2. The positive electrode plate according to claim 1, wherein, The water-soluble adhesive is polyacrylamide-based.

3. The positive electrode plate according to claim 1, wherein, The water-soluble adhesive is present in a concentration of 20–70 wt%.

4. The positive electrode plate according to claim 1, wherein, The conductive material is acetylene black or carbon nanotubes.

5. The positive electrode plate according to claim 1, wherein, The thickness of the water-soluble adhesive layer is 0.5–3 μm.

6. The positive electrode plate according to any one of claims 1 to 5, wherein, The positive electrode composite layer contains a non-water-soluble adhesive.

7. A method for manufacturing electrode materials, comprising: A process for preparing a positive electrode plate according to any one of claims 1 to 6; a process for peeling off the positive electrode composite layer starting from the water-soluble adhesive layer by supplying an aqueous solvent to the positive electrode plate; and a process for recovering electrode material from the positive electrode composite layer.

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