Collector foil, bipolar storage battery, and material recovery method for bipolar storage battery

Abstract

The present invention addresses the problem of easily separating a positive electrode foil and a negative electrode foil when recovering a material. [Solution] A method for recovering a material for a bipolar storage battery, the method comprising: a disassembly step in which a bipolar storage battery is disassembled and a bipolar electrode is separated from constituent members; a foaming step for increasing the thickness of the adhesive layer by heating the separated bipolar electrode and foaming the resin foaming agent contained in the adhesive layer of the collector foil forming the bipolar electrode; and a separation step for separating the positive electrode foil and the negative electrode foil, which are adhered to each other via the adhesive layer, in the collector foil in a state in which the resin foaming agent foams to increase the thickness of the adhesive layer.

Description

Technical Field

[0001] This invention relates to current collector foil, bipolar batteries, and a method for recycling materials from bipolar batteries. Background Technology

[0002] Patent Document 1 discloses a method for recovering materials from a bipolar battery, which involves applying external force to the bipolar electrodes obtained by disassembling the battery pack using a tool to mechanically remove the substrate and adhesive, thereby separating the current collector of the positive electrode from the current collector of the negative electrode.

[0003] Prior art literature

[0004] Patent Document 1: Japanese Patent Application Publication No. 2022-147473 Summary of the Invention

[0005] The problem that the invention aims to solve

[0006] However, in the structure described in Patent Document 1, since the substrate and adhesive are removed mechanically using tools, it is difficult to remove them completely, and a post-processing step is required to remove the residue, so there is room for improvement.

[0007] The present invention was made in view of the above circumstances, and its object is to provide a current collector foil, a bipolar battery, and a material recycling method for a bipolar battery that can easily separate the positive and negative electrode foils during material recycling.

[0008] Methods for solving problems

[0009] The present invention relates to a current collector foil formed by bonding a positive electrode foil and a negative electrode foil together via an adhesive layer containing a conductive material, characterized in that the adhesive layer contains a resin foaming agent.

[0010] According to this technology, since the adhesive layer of the bonding foil contains a resin foaming agent, the positive and negative foils can be easily separated by foaming the resin foaming agent when recycling the constituent materials of the collecting foil.

[0011] In addition, the resin foaming agent may include at least one of a variety of chemical foaming agents.

[0012] According to this technology, the resin foaming agent of the adhesive layer can be composed of a chemical foaming agent.

[0013] In addition, the resin foaming agent may include at least one of a chemical foaming agent and a thermally expandable microcapsule.

[0014] According to this technology, the resin foaming agent of the adhesive layer can be composed of thermally expandable microcapsules.

[0015] In addition, the adhesive layer may contain the resin foaming agent in a proportion of 10 to 50%.

[0016] According to this technology, the resin foaming agent in its pre-foaming state is mixed in a proportion that does not impede the electronic conductivity between the positive and negative electrode foils.

[0017] Alternatively, the adhesive layer can be configured to include an olefin resin, an epoxy resin, and a metal plating resin, wherein the olefin resin is a resin with a melting point lower than the foaming start temperature of the resin foaming agent.

[0018] According to this technology, since the olefin resin contained in the adhesive layer is a thermoplastic resin, it can soften when the resin foaming agent foams, and the resin foaming agent expands by forming a film.

[0019] The bipolar battery of the present invention is a bipolar battery having a current-collecting foil formed by bonding a positive electrode foil and a negative electrode foil together via an adhesive layer containing a conductive material, characterized in that the adhesive layer contains a resin foaming agent.

[0020] According to this technology, since the adhesive layer of the bonding foil in the bipolar battery contains a resin foaming agent, the positive and negative foils can be easily separated by foaming the resin foaming agent when recycling the constituent materials of the bipolar battery.

[0021] Alternatively, the positive electrode foil can be configured as aluminum foil and the negative electrode foil as copper foil.

[0022] Based on this technology, aluminum foil and copper foil can be easily separated from the foamed state of the resin foaming agent in the adhesive layer.

[0023] The present invention relates to a method for recycling materials from a bipolar battery, characterized in that it includes a disassembly step, a foaming step, and a separation step. In the disassembly step, the bipolar battery is disassembled, and the bipolar electrodes are separated from the constituent components. In the foaming step, the separated bipolar electrodes are heated to foam the resin foaming agent contained in the adhesive layer of the current collector foil forming the bipolar electrodes, thereby increasing the thickness of the adhesive layer. In the separation step, with the adhesive layer increased in thickness due to the foaming of the resin foaming agent, the positive and negative electrode foils bonded together in the current collector foil via the adhesive layer are separated.

[0024] According to this technology, the positive and negative electrode foils can be easily separated by foaming the resin foaming agent contained in the adhesive layer of the current collector foil.

[0025] Alternatively, the adhesive layer may be configured to include an olefin resin, an epoxy resin, and a metal plating resin, wherein the olefin resin is a resin with a melting point lower than the foaming start temperature of the resin foaming agent, and the foaming process includes heating the bipolar electrode to a temperature higher than the foaming start temperature of the resin foaming agent.

[0026] According to this technology, since the olefin resin contained in the adhesive layer is a thermoplastic resin, the olefin resin softens and forms a film during the foaming process, thereby enabling the resin foaming agent to expand.

[0027] The effects of the invention

[0028] In this invention, the positive electrode foil and the negative electrode foil can be easily separated during material recycling. Attached Figure Description

[0029] Figure 1 This is a schematic diagram illustrating the current collector foil in the embodiment.

[0030] Figure 2 It is a diagram used to illustrate the state of the resin foaming agent contained in the adhesive layer before foaming and the state of the adhesive layer becoming thicker due to the foaming of the resin foaming agent.

[0031] Figure 3 This is a flowchart illustrating a material recycling method for bipolar batteries.

[0032] Figure 4 This diagram illustrates the process after the resin foaming agent of the adhesive layer has foamed. Detailed Implementation

[0033] The following provides a detailed description of the current-collecting foil, the bipolar battery, and the method for recycling materials from the bipolar battery according to embodiments of the present invention. However, the present invention is not limited to the embodiments described below.

[0034] Figure 1 This is a schematic diagram illustrating the current-collecting foil in the embodiment. The current-collecting foil 1 includes an aluminum foil 2, a copper foil 3, an adhesive layer 4, and carbon coatings 5 ​​and 6.

[0035] The current collector foil 1 is a bonded foil formed by bonding an aluminum foil 2 (as the positive electrode foil) and a copper foil 3 (as the negative electrode foil) together via an adhesive layer 4. One surface of each of the aluminum foil 2 and copper foil 3 is covered with carbon coatings 5 ​​and 6. The current collector foil 1, as the bonded foil, constitutes a bipolar electrode. The bipolar electrode containing the current collector foil 1 is a component constituting a bipolar battery. A bipolar battery has multiple bipolar electrodes containing the current collector foil 1. A bipolar battery containing the current collector foil 1 is a bipolar lithium-ion battery. A bipolar lithium-ion battery containing the current collector foil 1 is mounted in an electric vehicle. The electric vehicle is a battery electric vehicle (BEV) or a plug-in hybrid electric vehicle (PHEV).

[0036] Aluminum foil 2 is the positive electrode substrate. A positive electrode agent is disposed on one surface of aluminum foil 2 through a carbon coating 5.

[0037] Copper foil 3 is the negative electrode substrate. A negative electrode agent is disposed on one surface of copper foil 3 through a carbon coating 6.

[0038] Adhesive layer 4 is a resin layer that bonds aluminum foil 2 and copper foil 3 together. In addition to olefin resin, epoxy resin, and a metal-plated resin to ensure conductivity, adhesive layer 4 also contains a resin foaming agent. Among the olefin resin, epoxy resin, metal-plated resin, and resin foaming agent constituting adhesive layer 4, the olefin resin is selected with a melting point lower than the foaming initiation temperature of the resin foaming agent. This increases the fluidity of adhesive layer 4 and promotes foaming.

[0039] The resin foaming agent of adhesive layer 4 uses one of a variety of chemical foaming agents or a mixture of a variety of agents, and selects a substance that can foam in the target temperature range.

[0040] Examples of chemical foaming agents include azodicarbonamide (ADCA), dinitrospentamethylenetetramine (DPT), 4,4'-oxobis(benzenesulfonylhydrazine) (OBSH), and sodium bicarbonate (sodium bicarbonate).

[0041] Alternatively, the resin foaming agent of adhesive layer 4 can use thermally expandable microcapsules instead of chemical foaming agents, or it can contain both chemical foaming agents and thermally expandable microcapsules. The resin foaming agent can consist only of chemical foaming agents, only of thermally expandable microcapsules, or both. In the case where the resin foaming agent contains a chemical foaming agent, the resin foaming agent of adhesive layer 4 contains at least one of several chemical foaming agents (ADCA, DPT, OBSH, sodium bicarbonate).

[0042] Furthermore, the adhesive layer 4 contains a resin foaming agent in a proportion of 10% to 50%. The adhesive layer 4 contains the resin foaming agent in its pre-foaming state in a proportion that does not impede the electronic conductivity between the aluminum foil 2 and the copper foil 3. The proportion that does not impede the electronic conductivity between the aluminum foil 2 and the copper foil 3 refers to the case where the proportion of the resin foaming agent mixed in the adhesive layer 4 is 10% to 50%.

[0043] The resin foaming agent has two functions: increasing the thickness of the adhesive layer 4 during foaming and decreasing the density of the adhesive layer 4 during foaming. Utilizing this function, physical peeling such as scraping can be performed during material recycling, or peeling can be achieved through carbonization and gasification of the resin portion caused by roasting and combustion.

[0044] like Figure 2As shown, in an unconstrained environment, the adhesive layer 4 of the current collector foil 1 becomes thinner before the resin foaming agent foams, and thicker after the resin foaming agent foams. During recycling, by heating the current collector foil 1 at a lower temperature, the resin foaming agent of the adhesive layer 4 foams, forming gaps between the aluminum foil 2 and the copper foil 3. Therefore, in an unconstrained environment during recycling, by heating the current collector foil 1 to a specified temperature or higher to foam the resin foaming agent of the adhesive layer 4, the aluminum foil 2 and the copper foil 3 can be easily separated from the bonding foil. That is, with more gaps created between the aluminum foil 2 and the copper foil 3 due to the foaming of the resin foaming agent in the adhesive layer 4, gas diffusion during mechanical peeling and baking becomes easier.

[0045] In a bipolar battery containing a current collector foil 1 configured in this way, under the constrained state of the battery pack (a state in which a high voltage is applied between the electrodes), even if the resin foaming agent in the adhesive layer 4 foams, the volume of the adhesive layer 4 will not increase, and a sufficient peeling effect cannot be obtained. Therefore, in order to maximize the foaming effect of the resin foaming agent, it is preferable to heat the current collector foil 1 to cause the resin foaming agent in the adhesive layer 4 to foam while the battery module is disassembled into bipolar electrodes.

[0046] Furthermore, since the olefin resin contained in the adhesive layer 4 is a thermoplastic resin, it can soften and form a film during the foaming of the resin foaming agent, thereby causing the resin foaming agent to expand. As a result, sufficient gaps are formed between the aluminum foil 2 and the copper foil 3 through the foaming of the resin foaming agent, so that both mechanical peeling such as scraping and high-temperature baking (below 600°C) can be carried out in a shorter time and at a lower cost compared to the past.

[0047] Figure 3 This is a flowchart illustrating a material recycling method for bipolar batteries. The material recycling method for bipolar batteries includes: a harmless treatment process (step S1), a battery pack disassembly process (step S2), a battery module disassembly process (step S3), an electrolyte recycling process (step S4), an additive recycling process (step S5), and a foil peeling process (step S6).

[0048] The decontamination process involves discharging the battery pack to make it safe for disposal (step S1). The decontamination process includes a discharge process. The battery pack is a bipolar lithium-ion battery having bipolar electrodes including current collector foil 1.

[0049] The battery pack disassembly process is the process of disassembling the battery pack and separating the battery modules from its constituent components (step S2). The battery pack contains multiple battery modules, and each battery module contains bipolar electrodes.

[0050] The battery module disassembly process involves disassembling the battery module and removing the resin from its four sides to allow it to be separated into individual bipolar electrodes (step S3). In this disassembly process, for battery modules that are formed into a four-sided shape, the resin from the four sides, such as the sealing material, is removed.

[0051] The electrolyte recovery process is a process of recovering the electrolyte that fills the space between the bipolar electrodes by means of heating, depressurization and drying before the heat treatment of the bipolar electrodes (step S4).

[0052] The flux recovery process is a process of removing and recovering the positive and negative fluxes coated on the bipolar electrodes from the current collector foil 1 (step S5). The positive flux is coated on the surface of the carbon coating 5 on the positive electrode side. The negative flux is coated on the surface of the carbon coating 6 on the negative electrode side.

[0053] The peeling process of the bonding foil involves heating the current collector foil 1 to increase the thickness of the adhesive layer 4 and reduce its density, thereby separating the aluminum foil 2 and the copper foil 3 (step S6). This peeling process includes a foaming process and a separation process. The foaming process involves heating the bipolar electrode to foam the resin foaming agent contained in the adhesive layer 4 of the current collector foil 1 that forms the bipolar electrode, thereby increasing the thickness of the adhesive layer 4. The separation process involves separating the aluminum foil 2 and the copper foil 3 bonded together by the adhesive layer 4 in the current collector foil 1 while the adhesive layer 4 is thickened due to the foaming of the resin foaming agent.

[0054] The foaming process includes a step of heating the current collector foil 1 to bring the resin foaming agent of the adhesive layer 4 to a temperature higher than the foaming start temperature (heat treatment). The heat treatment of the current collector foil 1 can be any of atmosphere heat treatment, contact heating, or induction heating.

[0055] In the separation process, the bonding foil is separated into aluminum foil 2 and copper foil 3. Examples of methods for separating the electrode foil include physical peeling using equipment and separating the aluminum foil 2 and copper foil 3 by baking. Figure 4 As shown, in the separation process, the current collector foil 1 in the foamed state of the adhesive layer 4 is baked in a furnace 200 at a temperature below 600°C. After this heat treatment, the aluminum foil 2 and copper foil 3 are separated by hand. The baking is carried out in the furnace 200 at a temperature of 350-600°C for a period of less than a few minutes.

[0056] By recycling the positive electrode compound, negative electrode compound, aluminum foil 2, and copper foil 3, the recycling of the two electrode compounds and the substrate of the bipolar electrode is completed.

[0057] As explained above, according to the embodiment, by foaming the resin foaming agent of the adhesive layer 4, a sufficient gap is formed between the aluminum foil 2 and the copper foil 3. Therefore, even if mechanical peeling is performed by scraper or the process is performed by high-temperature baking, recycling can be achieved in a shorter time and at a lower cost compared to the past.

[0058] Furthermore, in the material recycling method for bipolar batteries, the order of the electrolyte recovery step (step S5) and the foil stripping step (step S6) is not critical. A recycling method can be adopted where the stripping step is performed after the electrolyte recovery step, followed by the electrolyte recovery step.

[0059] Furthermore, in the current collector foil 1, the combination of metal foils constituting the positive and negative electrode foils is not limited to aluminum foil 2 and copper foil 3. The metal foil contained in the current collector foil 1 can be lead foil. That is, the bipolar battery containing the current collector foil 1 is not limited to a bipolar lithium-ion battery, but can also be a bipolar lead-acid battery or a bipolar nickel-metal hydride battery.

[0060] Additionally, carbon coatings 5 ​​and 6 are not mandatory. For example, a positive electrode paste can be coated onto the surface of aluminum foil 2 to form a positive electrode flux layer. Similarly, a negative electrode paste can be coated onto the surface of copper foil 3 to form a negative electrode flux layer.

[0061] Explanation of reference numerals in the attached figures

[0062] 1 collector foil

[0063] 2. Aluminum foil (positive electrode foil)

[0064] 3. Copper foil (negative electrode foil)

[0065] 4. Adhesive layer

[0066] 5, 6 carbon coating

Claims

1. A current-collecting foil, comprising a positive electrode foil and a negative electrode foil bonded together via an adhesive layer containing a conductive material, characterized in that, The adhesive layer contains a resin foaming agent.

2. The current collector foil according to claim 1, characterized in that, The resin foaming agent includes at least one of a variety of chemical foaming agents.

3. The current collector foil according to claim 1, characterized in that, The resin foaming agent comprises at least one of a chemical foaming agent and a thermally expandable microcapsule.

4. The current collector foil according to any one of claims 1 to 3, characterized in that, The adhesive layer contains the resin foaming agent in a proportion of 10% to 50%.

5. The current collector foil according to claim 4, characterized in that, The adhesive layer comprises olefin resin, epoxy resin, and metal plating resin. The olefin-based resin is a resin whose melting point is lower than the foaming start temperature of the resin foaming agent.

6. A bipolar rechargeable battery comprising a current-collecting foil formed by bonding a positive electrode foil and a negative electrode foil together via an adhesive layer containing a conductive material, characterized in that, The adhesive layer contains a resin foaming agent.

7. The bipolar storage battery according to claim 6, characterized in that, The resin foaming agent includes at least one of a variety of chemical foaming agents.

8. The bipolar storage battery according to claim 6, characterized in that, The resin foaming agent comprises at least one of a chemical foaming agent and a thermally expandable microcapsule.

9. The bipolar storage battery according to any one of claims 6 to 8, characterized in that, The adhesive layer contains the resin foaming agent in a proportion of 10% to 50%.

10. The bipolar storage battery according to claim 9, characterized in that, The adhesive layer comprises olefin resin, epoxy resin, and metal plating resin. The olefin-based resin is a resin whose melting point is lower than the foaming start temperature of the resin foaming agent.

11. The bipolar storage battery according to claim 10, characterized in that, The positive electrode foil is aluminum foil. The negative electrode foil is a copper foil.

12. A method for recycling materials from a bipolar storage battery, characterized in that, It includes disintegration, foaming, and separation processes. In the disassembly process, the bipolar battery is disassembled, and the bipolar electrodes are separated from the constituent components. In the foaming process, the separated bipolar electrodes are heated, causing the resin foaming agent contained in the adhesive layer of the current collector foil forming the bipolar electrodes to foam, thereby increasing the thickness of the adhesive layer. In the separation process, with the adhesive layer thickened by the foaming of the resin foaming agent, the positive and negative electrode foils bonded together by the adhesive layer in the current collector foil are separated.

13. The material recycling method for a bipolar storage battery according to claim 12, characterized in that, The adhesive layer comprises olefin resin, epoxy resin, and metal plating resin. The olefin-based resin is a resin whose melting point is lower than the foaming start temperature of the resin foaming agent. The foaming process includes heating the bipolar electrode to a temperature higher than the foaming initiation temperature of the resin foaming agent.

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