Electrode recycling method and battery manufacturing method

Abstract

To provide an electrode recycling method capable of improving the electrode recycling rate, and a battery manufacturing method utilizing this electrode recycling method.SOLUTION: A method for recycling an electrode according to an embodiment includes a step S1 of obtaining a heat-treated product by heat-treating a target electrode including a first current collector and an active material-containing layer supported on the first current collector and including an active material, a binder, and a conductor, at a temperature lower than the melting point of the first current collector to decompose the binder, a step S2 of separating the first current collector from the heat-treated product to obtain a mixture including the active material and the conductor, and a step S3 of manufacturing an electrode using the mixture.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The embodiments relate to a method for recycling electrodes and a method for manufacturing batteries. [Background technology]

[0002] The development of secondary batteries having electrodes containing niobium-containing oxide or niobium-titanium-containing oxide is underway. There is a demand for increasing the recycling rate in the manufacturing process of secondary batteries, thereby reducing manufacturing costs. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-92417 [Patent Document 2] JP 2000-348782 A [Patent Document 3] Special Publication No. 2022-545753 Summary of the Invention [Problem to be solved by the invention]

[0004] The problem to be solved is to provide an electrode recycling method capable of improving the electrode recycling rate, and a battery manufacturing method utilizing this electrode recycling method. [Means for solving the problem]

[0005] According to the embodiment, the method includes the steps of: heat-treating a target electrode including a first current collector and an active material-containing layer supported on the first current collector and including an active material, a binder, and a conductor, at a temperature lower than the melting point of the first current collector to decompose the binder, thereby obtaining a heat-treated product; obtaining a mixture containing an active material and a conductor by separating the first current collector from the heat-treated product; manufacturing an electrode using the mixture; A method for recycling electrodes is provided, comprising:

[0006] According to the embodiment, there is also provided a method for producing a battery, in which a battery is produced using an electrode recycled by the method of the above embodiment. [Brief description of the drawings]

[0007] [Figure 1] 4 is a flowchart showing an example of the flow of a method according to the first embodiment. [Diagram 2] 4 is a flowchart showing an example of the flow of an electrode manufacturing method according to the first embodiment. [Diagram 3] FIG. 4 is a plan view showing an example of a target electrode. [Figure 4] 4 is a cross-sectional view taken along line IV-IV of the electrode shown in FIG. 3. [Diagram 5] 4 is a cross-sectional view taken along line VV of the electrode shown in FIG. 3. [Figure 6] FIG. 1 shows an example of a measurement result by evolved gas analysis-mass spectrometry (EGA-MS). [Figure 7] FIG. 1 shows an example of the measurement results obtained by pyrolysis-gas chromatography-mass spectrometry (Pyro-GC-MS). [Figure 8] 10 is a flowchart showing an example of the flow of a method according to the second embodiment. [Figure 9] FIG. 2 is a partially cutaway perspective view showing an example of a battery manufactured by a method according to an embodiment. [Figure 10] FIG. 10 is an enlarged cross-sectional view of part A in FIG. [Figure 11] 6 is a flowchart showing another example of the flow of the method according to the first embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] (First embodiment) According to the first embodiment, a method for recycling an electrode is provided. The method for recycling an electrode according to the first embodiment will be described below with reference to the drawings. In the first embodiment, a new electrode is manufactured using a target electrode. The target electrode includes a first current collector and an active material-containing layer that is supported (or formed) on the first current collector and contains an active material, a binder, and a conductor. The target electrode does not retain an electrolyte. The target electrode is, for example, an electrode that is discarded and may be generated in the manufacturing process of an electrode or a battery. The target electrode is also called a waste material or a discarded electrode. An example of a target electrode is an electrode that is out of specification and may be generated in the manufacturing process of an electrode or a battery. Another example of a target electrode is an electrode that has been stored unused. Another example of a target electrode is a fragment of an electrode, such as a cut piece generated by cutting. When the target electrode is a discarded electrode generated in the manufacturing process, the composition of the active material-containing layer is usually known. In addition, since the target electrode is unused, for example, has not been charged or discharged, the active material is hardly deteriorated. Therefore, by using the active material and conductor separated from the target electrode, it is possible to easily regenerate an electrode having an active material-containing layer having the same composition as the active material-containing layer of the target electrode.

[0009] 1 and 2 are flow charts showing a method according to the first embodiment. An electrode recycling method I, which is one example of the method according to the first embodiment, includes, for example, steps S1 to S3 shown in Fig. 1. Each step will be described below. <Process S1> The binder is thermally decomposed from the target electrode by heat treatment to obtain a heat-treated product.

[0010] An example of the target electrode is shown in Figs. 3 to 5. In Figs. 3 to 5, the long side direction of the target electrode 1 is the y-axis direction. The short side direction of the target electrode 1 is the x-axis direction. The thickness direction of the target electrode 1 is the z-axis direction. The target electrode 1 includes a first current collector 2 and an active material-containing layer 3 containing an active material, a binder, and a conductor. The first current collector 2 is, for example, a conductive sheet-like material. A surface parallel to the xy plane of the sheet-like material has a quadrangle shape. In the case of Fig. 3, it is a rectangle. In Figs. 3 to 5, the active material-containing layer 3 is supported on two surfaces parallel to the xy plane of the first current collector 2, but is not limited thereto. For example, the active material-containing layer 3 may be supported on only one surface parallel to the xy plane of the first current collector 2. In Figs. 3 to 5, the active material-containing layer 3 is supported on both sides of the first current collector 2 except for both ends in the short side direction, but is not limited thereto. The active material-containing layer 3 may be supported on both surfaces of the first current collector 2 except for one end portion in the short side direction, or may be supported on the entire surfaces of the first current collector 2. The portion of the first current collector 2 on which the active material-containing layer 3 is not supported may function as a current collecting tab.

[0011] When the target electrode 1 is heat-treated at a temperature lower than the melting point of the first current collector, the first current collector is heat-treated but not melted, and can maintain almost its original properties (e.g., shape) before the heat treatment. As a result, it becomes easy to separate the heat-treated first current collector from the entire heat-treated product. One example of the heat treatment is firing. For firing, a furnace or the like can be used as a heat treatment means. Therefore, firing allows the heat treatment to be performed in a simple manner. The first current collector may be conductive. The composition of the first current collector may vary depending on the type of active material. The first current collector may be formed of a conductive material that is electrochemically stable at a potential at which lithium (Li) is inserted and removed. An example of the first current collector includes at least one selected from the group consisting of copper, nickel, stainless steel, aluminum, and an aluminum alloy. The first current collector may include at least one of aluminum and an aluminum alloy. The melting point of the first current collector including at least one of aluminum and an aluminum alloy may be around 660°C. The temperature below the melting point of the first current collector may be set to, for example, 660°C or less, preferably less than 660°C. The thickness of the first current collector may vary depending on the type and size of the battery, but is, for example, 5 μm to 20 μm. The conductor is not particularly limited, but may include a carbon material. When a conductor containing a carbon material is used, the decomposition (thermal decomposition) of the conductor can be suppressed by setting the heat treatment temperature to 660° C. or less. By suppressing the loss of the conductor, the conductive path between the active materials in the regenerated electrode can be maintained. Examples of carbon materials include carbon fiber (e.g., vapor grown carbon fiber (VGCF)), carbon nanotubes, carbon black such as acetylene black, graphite, etc. One of these may be used as the conductor, or two or more may be combined and used as the conductor. The conductor may exist independently of the active material, or may be supported on the surface of the active material particles. A conductor containing carbon nanotubes is likely to be entangled with the surface of the active material particles. Also, a conductor containing carbon black such as acetylene black is likely to adhere to the surface of the active material particles. A conductor containing at least one of carbon nanotubes and carbon black can increase the contact area with the active material particles. Therefore, it is easy to maintain the conductive path between the active material particles in a good condition even in the regenerated electrode.

[0012] The heat treatment temperature can be 20°C or more lower than the melting point of the first current collector. This can further suppress melting of the first current collector. Also, loss of the conductor due to heat can be suppressed. The heat treatment temperature can be, for example, 640°C or less, more preferably less than 640°C.

[0013] The decomposition of the binder is, for example, thermal decomposition. The decomposition (thermal decomposition) of the binder may occur in at least a part of the binder contained in the target electrode. This is because the binding strength between the active material or the conductor and the first current collector can be reduced by decomposing a part of the binder. This makes it easier to separate the active material and the conductor from the first current collector. In order to promote the decomposition reaction of the binder, the lower limit of the heat treatment temperature can be set to the decomposition temperature of the binder or higher. Here, when there are multiple types of binders, it is desirable to set the maximum decomposition temperature (the higher one in the case of two types) as the lower limit of the heat treatment temperature. The decomposition temperature of the binder will be described in detail later. The binder is not particularly limited, but may include an organic substance. The binder is desirably a hydrophilic binder that is water-soluble or can be dispersed in water, such as an emulsion. The hydrophilic binder may be an organic hydrophilic binder. Examples of organic hydrophilic binders include polyacrylic acid compounds, styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), and salts of CMC. One of these may be used as the binder, or two or more of them may be used in combination as the binder.

[0014] The heat treatment temperature can be, for example, 400° C. or higher and 660° C. or lower. By setting the heat treatment temperature at 400° C. or higher, the decomposition reaction of the binder can be promoted. Furthermore, by setting the heat treatment temperature at 660° C. or lower, melting of the first current collector can be suppressed. Furthermore, loss of the conductor can be suppressed.

[0015] The atmosphere in which the heat treatment is performed is not particularly limited. The oxygen concentration, moisture content, and the like of the atmosphere can be set within any range. One example of the atmosphere is air.

[0016] The time for which the heat treatment is performed is adjusted according to the heat treatment temperature, the composition of the target electrode, and the like. For example, the temperature and time of the heat treatment may be set so that the organic components contained in the target electrode are reduced by the heat treatment by an amount equivalent to 10% to 90% of the weight of the organic components. The target electrode does not retain an electrolyte. Examples of the organic components include a carbon material as a conductor and an organic substance as a binder. By setting the weight of the organic components reduced by the heat treatment to 10% or more of the total weight of the organic components, the amount of decomposition of the binder is sufficient, and the first current collector can be easily separated from the active material and the conductor. By setting the weight of the organic components reduced by the heat treatment to 90% or less of the total weight of the organic components, the loss of the conductor due to the heat treatment can be suppressed.

[0017] The active material contained in the target electrode is not particularly limited. The active material may be either a positive electrode active material or a negative electrode active material. The type of active material contained in the electrode may be one or more types. The active material may be in the form of particles.

[0018] The active material is, for example, lithium ion (Li + ) is capable of absorbing and releasing. An example of the active material is an active material that does not substantially contain Li. An active material that does not substantially contain Li is, for example, an active material that does not contain Li, or an active material that does not contain Li during synthesis but contains lithium ions (Li + Examples of such active materials include active materials in which Li remains due to an irreversible reaction that occurs during the absorption / release reaction of Li or during charge / discharge reactions. Active materials that do not substantially contain Li can suppress the reaction that produces lithium carbonate (Li2CO3) by reacting with moisture in the atmosphere, for example. Therefore, it is possible to suppress the deterioration of the active material when the target electrode is heat-treated in air.

[0019] Examples of active materials include Si, carbonaceous materials, and oxides. Each material can absorb and release lithium ions. Each material may be an active material that does not substantially contain Li.

[0020] Examples of carbonaceous materials include graphite, carbon fiber, coke, and non-graphitizable carbon.

[0021] Examples of the oxide include titanium-containing oxides and niobium-containing oxides. Examples of the titanium-containing oxide include lithium titanium oxide, monoclinic titanium dioxide (TiO2(B)), anatase titanium dioxide, rutile titanium dioxide, hollandite titanium composite oxide, and orthorhombic titanium composite oxide. Examples of the niobium-containing oxide include niobium oxide, niobium titanium-containing oxide, niobium tungsten-containing oxide, and niobium titanium molybdenum-containing oxide.

[0022] Niobium-containing oxides may have lower electronic conductivity than carbonaceous materials. By adding a conductor to the mixture obtained in step S2 together with the active material containing the niobium-containing oxide, it becomes easier to maintain contact between the active material and the conductor in the regenerated electrode. Therefore, an electrode with good electronic conductivity can be regenerated.

[0023] Examples of niobium oxides include Nb2O5.

[0024] Examples of the niobium titanium-containing oxide include monoclinic niobium titanium-containing oxide and substituted niobium titanium composite oxide in which at least a part of Nb and / or Ti is substituted with a different element. Examples of the substituted element include Na, K, Ca, Co, Ni, Si, P, V, Cr, Mo, Ta, Zr, Mn, Fe, Mg, B, Pb, and Al. The substituted niobium titanium composite oxide may contain one type of substituted element or may contain two or more types of substituted elements.

[0025] Monoclinic niobium titanium oxides have the characteristics of having a highly stable crystal structure, excellent resistance to water, acid and alkali, and high density. Examples of monoclinic niobium titanium oxides include Nb2TiO7, Nb2Ti2O9, and Nb 10 Ti2O 29 , Nb 14 TiO 37 , Nb 24 TiO 62 Examples of monoclinic niobium titanium oxides include Li x Ti 1-y M1 y Nb 2-z M2 z O 7+δ Here, M1 is at least one selected from the group consisting of Zr, Si, and Sn. M2 is at least one selected from the group consisting of V, Ta, and Bi. The subscripts in the composition formula are 0≦x≦5, 0≦y<1, 0≦z<2, and -0.3≦δ≦0.3. Another example of a monoclinic niobium titanium oxide is Li x Nb2TiO7(0≦x≦5) is one example. x The density of Nb2TiO7 (0≦x≦5) is 4.34g / cm 3 It is.

[0026] Another example of a monoclinic niobium titanium oxide is Li x Ti 1-y M3 y+z Nb 2-z O 7-δ Here, M3 is at least one selected from Mg, Fe, Ni, Co, W, Ta, and Mo. The subscripts in the composition formula are 0≦x≦5, 0≦y<1, 0≦z<2, and -0.3≦δ≦0.3.

[0027] Examples of niobium tungsten-containing oxides include Nb 14 W3O 44 , Nb 16 W5O 55 ,Nb 18 W8O 69 etc.

[0028] Examples of niobium titanium molybdenum-containing oxides include those having the general formula Li a Ti b Nb 2-2d Mo c+2d O 2b+5+3c (wherein the subscripts a, b, c, and d are preferably within the ranges of 0≦a≦b+4+3c, 0.3≦b≦1.6, 0.3≦c<1.6, and 0≦d<0.4, respectively), and a tetragonal titanium-niobium-molybdenum composite oxide represented by the general formula Li a M b NbMo c O d where M is one or more selected from the group consisting of Ti, V, Ta, Fe, Co, Mn, Ni, Bi, Sb, As, P, Cr, W, B, Na, K, Mg, Al, Ca, Y, and Si, and includes composite oxides in which 0≦a≦b+2+3c, 0≦b≦1.4, 0≦c≦0.5, and 2.33≦d / (1+b+c)≦2.50 are satisfied.

[0029] The niobium titanium-containing oxide may contain unavoidable impurities. Examples of the unavoidable impurities include K, Na, Si, and P. <Process S2> The first current collector is separated from the heat-treated product to obtain a mixture containing the active material and the conductor.

[0030] In the heat-treated product obtained in step S1, at least a part of the binder has disappeared due to decomposition. Furthermore, although the first current collector has been heat-treated, melting is suppressed, and it is not a molten product. The conductor and active material have been heat-treated. Furthermore, at least a part of the active material is in contact with the conductor. In the heat-treated product, the bonding strength of the conductor and active material to the first current collector is reduced, and therefore the first current collector can be easily separated from the conductor and active material.

[0031] The separation can be performed by peeling, picking up, sucking, centrifuging, sieving, or the like, of the heat-treated first current collector from the heat-treated product. The heat-treated product may be crushed or subjected to ultrasonic vibration before separation, but this is not necessary. The heat-treated first current collector can be easily separated from the heat-treated product without crushing or subjecting the heat-treated product to ultrasonic vibration. This makes it possible to avoid damage such as impact to the active material and the conductor. In addition, the heat-treated first current collector is not broken down by crushing, and can be kept at approximately its original size, making it easy to remove the heat-treated first current collector. <Process S3> A mixture containing an active material and a conductor is used to manufacture an electrode.

[0032] The active material and the conductor are subjected to a heat treatment at a temperature lower than the melting point of the first current collector, so that the influence of the heat treatment can be reduced. Since the mixture contains the active material and the conductor, the conductive path between the active materials is easily maintained in the electrode manufactured using the mixture, so that the deterioration of the active material can be suppressed and the battery performance can be improved.

[0033] When the conductor contains a carbon material, the carbon material content of the mixture can be 0.1% by mass or more and 10% by mass or less. By making the carbon material content of the mixture 0.1% by mass or more, an electrode with a good conductive path between active materials can be obtained. Also, by making the carbon material content of the mixture 10% by mass or less, an electrode with a practical capacity can be obtained.

[0034] The mixture is allowed to contain a binder as long as it does not interfere with the separation in step S2.

[0035] The electrode can be manufactured, for example, by a method including steps S11 to S15 illustrated in Fig. 2. Steps S11 to S15 will be described below. <Process S11> A slurry is prepared using the mixture containing the active material and the conductor obtained by step S2. The amount of the active material and the conductor is almost the same as the initial value even after step S2. Therefore, the amount of the active material and the conductor in the mixture can be estimated based on the composition of the active material-containing layer of the target electrode. A binder and a solvent are added to the mixture containing the active material and the conductor so as to obtain a target composition. If necessary, an active material and / or a conductor may be added. After the addition, the mixture is mixed to prepare a slurry. An example of the solvent is water. The composition of the slurry may be the same as the composition of the active material-containing layer of the target electrode, or may be different. For example, the type of binder in the slurry may be different from the type of binder contained in the target electrode.

[0036] Alternatively, the slurry may be prepared by measuring the amounts of active material and conductor in the mixture, adding the active material, conductor, binder and solvent to the mixture based on the measured amounts, and mixing them.

[0037] Before preparing the slurry, the mixture containing the active material and the conductor may be pulverized, which allows the particle size of the mixture to be set within a desired range. <Process S12> The slurry is applied to a second current collector.

[0038] Coating is performed on at least a portion of the second current collector. For example, the slurry can be coated on one or both main surfaces of the second current collector. The main surface of the second current collector is, for example, a surface that defines the thickness of the second current collector or a surface that intersects with the thickness direction of the second current collector.

[0039] The second current collector may be the first current collector separated from the target electrode, may be an unused current collector, or may be a current collector different from the first current collector. <Process S13> The applied slurry is dried. This forms an active material-containing layer on the second current collector. The active material, conductor, and binder in the active material-containing layer may be mixed in proportions of 68% by mass to 96% by mass, 2% by mass to 30% by mass, and 2% by mass to 30% by mass, respectively, for example. <Process S14> The second current collector carrying the active material-containing layer is pressed to obtain an electrode. The electrode may be cut as shown in step S15 to obtain a desired shape or size. The active material and the conductor are mixed once during the production of the target electrode, so the surface properties (hydrophilicity, hydrophobicity, etc.) are stably maintained. Therefore, the newly produced electrode has high adhesion between the active material-containing layer and the second current collector, and has excellent charge / discharge efficiency. <Process S15> The electrode is cut to set a desired shape or size. If the electrode after pressing has the desired shape or size, step S15 can be omitted.

[0040] The manufactured electrode may have a structure similar to that of the target electrode, the details of which are as described with reference to Figs.

[0041] Instead of steps S11 to S15, the following method may be performed. To a mixture containing an active material and a conductor, an active material, a conductor, and a binder are added so as to obtain a target composition, and then these are mixed. Next, the resulting mixture is formed into a pellet. After that, the pellet may be placed on a current collector to obtain an electrode.

[0042] The following describes a method for measuring the decomposition temperature of the binder, thermogravimetry, a method for measuring the content of the conductor in the mixture, and a method for confirming the positive and negative electrode active materials.

[0043] First, when the electrode to be measured (positive electrode or negative electrode) is incorporated in a battery, the electrode to be measured is removed from the battery as follows. First, the battery containing the electrode is disassembled in a glove box filled with argon. The electrode to be measured is removed from the disassembled battery. This electrode is washed with an appropriate solvent. For example, methyl ethyl carbonate can be used as the solvent used for washing. The washed electrode is vacuum dried. In this way, the electrode to be measured is obtained. <Method for measuring the decomposition temperature of the binder> The decomposition temperature of the binder is measured, for example, by evolved gas analysis (Evolved Gas Analysis-Mass Spectrometry: EGA-MS). Evolved gas analysis measures the temperature profile of gas evolved from a sample. Detection is performed by mass spectrometry (MS). Approximately 1 mg of the active material-containing layer (electrode mixture) of the measurement electrode taken out by the above method is weighed into a sample cup for EGA-MS analysis. The measurement is performed, for example, at a temperature rise rate of 10°C / min. Details of the measurement conditions are described below. The pyrolyzer is heated to 40°C for 4 min, and then heated to 600°C at a rate of 10°C / min. The sample weight is about 1 mg. For GC (Gas Chromatography), the inlet temperature is 300°C and the column is Ultra Alloy DTM 2.5m 0.15mm id. The temperature is held at 300°C. The split ratio is 1:50. The He flow rate is 1.0mL / min. For MS, the mass range is 10-600m / z. The ionization method is EI (EI stands for Electron Impact or Electron Ionization). An example of the measurement results is shown in FIG. 6. The horizontal axis in FIG. 6 is temperature. The vertical axis is the intensity (arbitrary unit) of the obtained mass ions. In the case of FIG. 6, there is a peak in the range of 350°C to 450°C. Therefore, it can be said that the decomposition temperature of the binder is about 350°C to 450°C. In the case of FIG. 6, the temperature at which the peak has the maximum intensity is about 420°C. By setting the heat treatment temperature (e.g., the firing temperature) in step S1 to the temperature at which the peak has the maximum intensity (e.g., about 420°C), the decomposition of the binder can be promoted. Therefore, it becomes possible to almost completely eliminate the binder. <Qualitative analysis of binder> The organic components contained in the target electrode can be identified by pyrolysis-gas chromatography-mass spectrometry (Pyro-GC-MS). Pyrolysis-gas chromatography-mass spectrometry is a flash pyrolysis method in which a sample is thermally decomposed at a set pyrolysis temperature, and the flash pyrolyzed material is analyzed by gas chromatography-mass spectrometry (GC-MS). The analysis conditions are described below. Approximately 1 mg of the active material-containing layer (electrode mixture) of the measurement electrode is weighed out into a sample cup for EGA-MS analysis. <Pyrolyzer> The heating temperature is 400 to 700°C. The sample amount is approximately 1 mg. <gc> The inlet temperature is set to 300°C. The column used is UA-5 (HT / MS) 30 m, 0.25 mm id. The temperature is kept at 40° C. for 2 minutes, and then increased to 320° C. at a rate of 10° C. / min. The split ratio is 1:50. The He flow rate is 1.0 mL / min. The mass range is 10 to 600 m / z. The ionization method is EI (EI stands for Electron Impact or Electron Ionization). <Thermogravimetry: Method for measuring the amount of conductor in a mixture>

[0044] The relationship between the heat treatment temperature and the weight loss of the organic components when the target electrode is subjected to heat treatment, and the content of the conductor in the mixture can be measured, for example, by thermogravimetry (TG). The measurement conditions for thermogravimetry are as follows: Air is used at a flow rate of 100 mL / min as the gas flow rate. The temperature is raised from 40°C to 900°C at a heating rate of 10°C / min. An example of the measurement results of thermogravimetry is shown in FIG. 7. The horizontal axis of FIG. 7 indicates the time (minutes) corresponding to the heat treatment temperature. The vertical axis indicates weight (mg). First, the active material-containing layer of the target electrode is heated from 40°C to about 900°C, and the weight of the entire organic components is obtained from the weight when all the organic materials contained in the target electrode are decomposed. The weight of the entire organic components obtained is regarded as the weight of the carbon material as a conductor. In addition, the active material-containing layer of the target electrode is held at 40°C for the first 5 minutes as shown in FIG. 7. Next, the temperature is increased from 40°C to 450°C at a rate of 10°C / min. The time required for the temperature increase is 47 minutes. Next, when the electrode is held at 450°C for 33 minutes, weight loss is observed as shown in Figure 7. The weight loss from 47 minutes to 80 minutes is about 0.05 mg. When the total amount of organic components is 0.5 mg, the weight loss of the organic components due to the heat treatment at 450°C accounts for 10% of the total weight. Therefore, by subjecting the target electrode to heat treatment at 450°C for 33 minutes, an amount equivalent to 10% by weight of the organic components contained in the target electrode can be eliminated by decomposition. The measurement target described with reference to Fig. 7 is a target electrode. By measuring the weight loss when the mixture obtained in step S2, instead of the target electrode, is heated to 900°C under the above-mentioned conditions, the weight of the carbon material as a conductor contained in the mixture can be obtained. The content of the conductor in the mixture is calculated from the obtained weight and the weight of the entire mixture. <Positive electrode active material> The crystal structure and elemental composition of the positive electrode active material can be confirmed by powder X-ray diffraction (XRD) measurement and inductively coupled plasma (ICP) optical emission spectrometry. <Negative electrode active material> The crystal structure and elemental composition of the negative electrode active material can be confirmed by powder X-ray diffraction (XRD) measurement and inductively coupled plasma (ICP) optical emission spectrometry. <XRD measurement method> The powder X-ray diffraction measurement of the positive electrode active material and the negative electrode active material can be performed as follows, for example. First, if necessary, the active material is pulverized to prepare a sample with an average particle size of less than about 5 μm. The average particle size can be determined by the laser diffraction method. The obtained sample is filled into a holder portion with a depth of 0.2 mm formed on a glass sample plate. Then, another glass plate is pressed from the outside to flatten the surface of the filled sample. Care is taken to fill the sample in an appropriate amount so that there are no cracks, voids, unevenness, etc. in the filled sample. Also, pay attention to pressing the glass plate with sufficient pressure. Then, the glass plate filled with the sample is installed in a powder X-ray diffractometer, and an XRD pattern is obtained using Cu-Kα rays. The measurement of the average particle size by the laser diffraction method is performed, for example, by the following method. The measurement of the average particle size is performed using a laser diffraction type particle size distribution measuring device (Shimadzu SALD-300 manufactured by Shimadzu Corporation or a device having an equivalent function). After adding about 0.1 g of the sample, a surfactant, and 1 to 2 mL of distilled water to a beaker and stirring well, this is poured into a stirring water tank, the light intensity distribution is measured 64 times at 2-second intervals, and the average particle size obtained from the obtained particle size distribution data is obtained. Whether or not the mixture obtained in step S2 contains a conductor can be confirmed, for example, by the following method. First, the mixture is pulverized to prepare a sample having an average particle size of less than about 5 μm. The average particle size can be determined by a laser diffraction method. The conditions for the laser diffraction method are as described above. An XRD pattern is obtained for the obtained sample under the conditions described above.

[0045] According to the above-described first embodiment of the electrode recycling method, the method includes a step of obtaining a heat-treated product by heat-treating a target electrode including a first current collector and an active material-containing layer including an active material, a binder, and a conductor at a temperature lower than the melting point of the first current collector to decompose the binder, a step of obtaining a mixture including an active material and a conductor by separating the first current collector from the heat-treated product, and a step of manufacturing an electrode using the mixture. According to the method of the embodiment, since the binder of the target electrode can be reduced by decomposition, the first current collector can be easily separated from the heat-treated product without crushing the obtained heat-treated product. In addition, since the mixture obtained by separation contains a conductor, in an electrode newly manufactured using the mixture, it is easy to form a conductive path between the active materials, so that the deterioration of the active material can be suppressed and the performance of the electrode can be improved. Furthermore, by using an electrode discarded in the manufacturing process as the target electrode, the recycling rate in the manufacturing process can be increased. Moreover, according to the first embodiment, it is possible to provide an electrode recycling method II comprising the steps described below. This electrode recycling method II will be described with reference to Fig. 11. The electrode recycling method II comprises steps S1 to S3 in the electrode recycling method I described with reference to Fig. 1. The electrode recycling method II comprises the following steps after step S2. A step of measuring the content of the conductor in the mixture obtained in step S2 (hereinafter referred to as step S2A). A step of determining the composition of the electrode to be manufactured based on the content of the conductor (hereinafter referred to as step S2B). In the electrode recycling method II, after step S2B, a step (referred to as step S3A) of manufacturing an electrode having the determined composition using the mixture is carried out as step S3. Next, steps S2A, S2B, and S3A will be described in detail. <Process S2A> The conductor content of the mixture obtained in step S2 is measured. The method for measuring the content of the conductor in the mixture is as described above. When a niobium-containing oxide is used as the active material, the niobium-containing oxide has higher thermal stability than a conductor containing a carbon material. In other words, the conductor is more affected by the heat treatment than the active material. The amount of change in composition due to the heat treatment can be determined by measuring the content of the conductor in the mixture and comparing the measured value with the composition of the active material-containing layer of the electrode to be recycled. The mixture may contain a binder as long as the binder does not interfere with the separation in step S2. <Process S2B> The composition of the electrode to be manufactured, specifically the composition of the active material-containing layer of the electrode to be manufactured, is determined based on the content of the conductor in the mixture. An example of the determination method is described below. The content of the conductor in the mixture is compared with the content (initial content) of the conductor in the active material-containing layer of the electrode to be recycled. If the result of the comparison is that, for example, the content of the conductor in the mixture is approximately equal to the initial content, the amount of the active material can also be considered to be approximately equal to the initial value. Based on the comparison result, the composition of the active material-containing layer of the electrode to be manufactured is determined. In the subsequent step S11 of preparing a slurry, other components other than the active material and the conductor (e.g., a binder), and at least one of the active material and the conductor, if necessary, are added to the mixture so as to obtain the determined composition. In the determined composition, the carbon material content of the mixture is desirably 0.1% by mass or more and 10% by mass or less. By setting the carbon material content of the mixture to 0.1% by mass or more and 10% by mass or less, it is possible to improve the conductive paths between the active materials while ensuring a practical capacity. <Process S3A> An electrode having the determined composition is fabricated using the mixture. The electrode can be manufactured, for example, by a method including steps S11 to S15 described with reference to Fig. 2. In step S11, a slurry is prepared using a mixture containing an active material and a conductor so as to have the composition determined in step S2B. The electrode recycling method II described above includes a step of measuring the conductor content of the mixture and a step of determining the composition of the electrode to be manufactured based on the conductor content. As a result, the variation in the composition of the manufactured electrodes can be reduced, and the stability of the quality of the recycled electrodes can be guaranteed. Second embodiment The second embodiment is a method for manufacturing a battery using the electrode manufactured in the first embodiment. The second embodiment includes manufacturing an electrode by the method of the first embodiment, manufacturing an electrode group including the manufactured electrode as a negative electrode, housing the electrode group in an exterior member, holding an electrolyte in the electrode group housed in the exterior member, and sealing the exterior member. The electrode group can include a positive electrode in addition to the negative electrode. The electrode group may also include a separator.

[0046] FIG. 8 is a flow chart showing an example of the flow of the manufacturing method of the battery of the second embodiment. First, a waste electrode 11 is prepared as the target electrode 1. The waste electrode 11 is, for example, an electrode that does not meet the specifications, an electrode that has been stored unused, or a fragment of an electrode such as a cut piece generated by cutting. The waste electrode 11 may also be an electrode taken out from a waste battery 12 that is not filled with electrolyte and may be generated during the manufacturing process of a battery. The waste battery 12 is a battery in which necessary components such as electrodes are stored in a container, but electrolyte has not been poured due to reasons such as being out of specifications. An example of a method of taking out the waste electrode 11 from a battery will be described later. In either case, the waste electrode 11 does not retain electrolyte. The composition of the active material-containing layer of the waste electrode 11 is known. In addition, since the waste electrode 11 has not been charged or discharged, the active material has hardly deteriorated. Therefore, by using the active material and conductor separated from the waste electrode 11, an electrode having an active material-containing layer having the same composition as the active material-containing layer of the waste electrode 11 can be easily regenerated.

[0047] A mixture containing an active material and a conductor is obtained from the waste electrode 11 through steps S1 and S2. Details of steps S1 and S2 are as described in the first embodiment. After steps S1 and S2, steps S2A and S2B may be performed. Details of steps S2A and S2B are as described in the first embodiment.

[0048] Next, the electrode is produced according to step S3 or step S3 A. The electrode is produced in steps S3 and S3 A ​​according to steps S11 to S15, for example.

[0049] First, dispersion is performed in step S11, that is, a slurry is prepared using the mixture. Details of step S11 are as described in the first embodiment.

[0050] Next, the steps S12 to S15 of coating, drying, pressing and cutting are carried out in this order to manufacture an electrode. The details of steps S12 to S15 are as described in the first embodiment.

[0051] Next, in an assembly process S21, an electrode group including the produced electrode as a negative electrode is produced, and then the electrode group is housed in an exterior member. The electrode group is produced, for example, by disposing a separator between a positive electrode and a negative electrode. The shape of the electrode group is not particularly limited, and may be, for example, a stack of a positive electrode, a separator, and a negative electrode, a flat or cylindrically wound positive electrode, a zigzag bent positive electrode, a separator, and a negative electrode, or the like.

[0052] Subsequently, in a liquid injection step S22, the electrolyte is held in the electrode group housed in the exterior member, and then the exterior member is sealed.

[0053] Thereafter, as a processing step S23 for commercialization, initial charging, aging, etc. are performed to obtain a battery.

[0054] Examples of the positive electrode, separator, electrolyte, and exterior member used in the above steps will be described below. <Positive Electrode> The positive electrode includes a positive electrode current collector and a positive electrode active material-containing layer carried on one side (one main surface) or both sides of the current collector and containing a positive electrode active material. The positive electrode active material-containing layer contains a positive electrode active material. The positive electrode active material-containing layer may contain a binder, a conductor, or both.

[0055] Examples of the positive electrode active material include Li x M y O2 (0 < x ≤ 1, 0 < y ≤ 1, M is, for example, Mn), Li x M 2y O4 (0 < x ≤ 1, 0 < y ≤ 1, M is, for example, Mn), lithium phosphate oxide having an olivine structure (for example, Li x M y PO4 (M is at least one element selected from Mn, Ni, Co, and Fe, 0 < x ≤ 1.1, 0.8 ≤ y ≤ 1.1), Li x FePO4 (0 < x ≤ 1.1), Li x Fe 1-y Mn y PO4 (0 < x ≤ 1.1, 0 ≤ y ≤ 1), Li x CoPO4 (0 < x ≤ 1.1), Li x MnPO4 (0 < x ≤ 1.1)), lithium nickel cobalt composite oxide (for example, LixNi 1-a Co a O2, 0 < x ≤ 1, 0 < a ≤ 1), lithium cobalt composite oxide (for example, Li x CoO2, 0 < x ≤ 1), lithium nickel manganese cobalt composite oxide (for example, Li x Ni 1-a-b Mn a Co b O2, 0 < x ≤ 1, 0 < 1 - a - b < 1, 0 < a < 1, 0 < b < 1), lithium manganese cobalt composite oxide (for example, Li x Mn 1-a Co a O2, 0 < x ≤ 1, 0 < a < 1), spinel-type lithium manganese nickel composite oxide (for example, Li x Mn 2-a Ni a O4, 0 < x ≤ 1, 0 < a < 2), fluorinated iron sulfate having a talc-like structure (for example, Li x M y SO4F (0 < x ≤ 1, 0 < y ≤ 1, M is at least one of Fe or Mn), Li x Fe 1-a Mn a SO4F (0 < x ≤ 1, 0 < a ≤ 1), etc. are included. The type of the positive electrode active material can be one type or two or more types.

[0056] The positive electrode active material-containing layer may contain a conductor. Examples of the conductor include acetylene black, carbon black, graphite, etc. The type of the conductor can be one type or two or more types.

[0057] The positive electrode active material-containing layer may contain a binder. Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluorine-based rubber, acrylic-based materials, etc. The type of the binder can be one type or two or more types.

[0058] The positive electrode current collector may contain at least one of aluminum or an aluminum alloy. For the positive electrode current collector, for example, an aluminum foil or an aluminum alloy foil is used.

[0059] The mixing ratio of the positive electrode active material, the conductor, and the binder is preferably in the range of 80 - 95% by mass of the positive electrode active material, 3 - 19% by mass of the conductor, and 1 - 7% by mass of the binder. The positive electrode is produced, for example, by suspending the positive electrode active material, the conductor, and the binder in an appropriate solvent, coating this suspension on the positive electrode current collector, drying, and pressing. Alternatively, the positive electrode may be produced by the following method. First, the active material, the conductor, and the binder are mixed to obtain a mixture. Next, this mixture is formed into pellets. Then, by arranging these pellets on the current collector, an electrode can be obtained. <Separator> For the separator, for example, a porous film, a synthetic resin non-woven fabric, a solid electrolyte layer, etc. can be used. <Electrolyte> The electrolyte may be, for example, an aqueous electrolyte or a non-aqueous electrolyte. The non-aqueous electrolyte may be, for example, a non-aqueous electrolyte prepared by dissolving an electrolyte salt such as a lithium salt in an organic solvent. The aqueous electrolyte may be, for example, an aqueous electrolyte prepared by dissolving an electrolyte salt such as a lithium salt in an aqueous solvent. Examples of the electrolyte salt include lithium salts such as lithium perchlorate (LiClO4), lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium hexafluoroarsenic (LiAsF6), lithium trifluoromethanesulfonate (LiCF3SO3), and lithium bistrifluoromethylsulfonylimide (LiN(CF3SO2)2). <Exterior materials> As the exterior member, for example, a container made of a laminate film or a metal container can be used. The shape of the exterior member is not particularly limited. The shape of the exterior member may be, for example, flat (thin), rectangular, cylindrical, coin, or button. The exterior member can be appropriately selected depending on the battery dimensions and the application of the battery.

[0060] The battery manufactured according to the embodiment is not particularly limited. Examples of the battery include a battery with an aqueous electrolyte and a battery with a non-aqueous electrolyte. The battery may be a single battery (single cell), a battery pack, or a battery pack.

[0061] The battery manufactured by the method of the embodiment may be used as a battery pack or may be incorporated into a battery pack. The battery according to the embodiment is preferably used in applications requiring excellent cycle performance when a large current is drawn. Specifically, the battery is used as a power source for digital cameras, or as a vehicle battery for, for example, two- to four-wheeled hybrid electric vehicles, two- to four-wheeled electric vehicles, power-assisted bicycles, or railroad vehicles (e.g., trains), or as a stationary battery. In particular, the battery is preferably used as an on-board battery mounted on a vehicle.

[0062] An example of a battery (secondary battery) will be described with reference to Figs. 9 and 10. Fig. 9 is a partially cutaway perspective view showing a nonaqueous electrolyte secondary battery, which is an example of a battery. Fig. 10 is an enlarged cross-sectional view of part A of the nonaqueous electrolyte secondary battery shown in Fig. 9. As shown in Fig. 9, the nonaqueous electrolyte battery 20 includes a bottomed rectangular cylindrical metal container 21, a flat electrode group 22, a metal sealing plate 23, a negative electrode terminal 24, and a positive electrode terminal 25. The flat electrode group 22 is accommodated in the metal container 21.

[0063] The flat electrode group 22 includes a negative electrode 26, a positive electrode 27, and a separator 28. The electrode group 22 has a structure in which the negative electrode 26 and the positive electrode 27 are spirally wound with the separator 28 interposed therebetween to form a flat shape. Although a wound electrode group is described here, the electrode group may be a laminated electrode group in which a plurality of negative electrodes 26, separators 28, and positive electrodes 27 are laminated. As shown in FIG. 10, the negative electrode 26 includes a negative electrode current collector 26a and a negative electrode active material-containing layer 26b supported on the negative electrode current collector 26a. As shown in FIG. 10, the positive electrode 27 includes a positive electrode current collector 27a and a positive electrode active material-containing layer 27b supported on the positive electrode current collector 27a. An electrolyte (not shown) is held in the electrode group 22. The opening of the metallic container 21 is sealed with a metallic sealing plate 23. The metallic container 21 and the sealing plate 23 constitute an exterior member.

[0064] As shown in Fig. 9, a negative electrode terminal 24 is provided on the metal sealing plate 23. A negative electrode current collector tab 29 is electrically connected to the negative electrode terminal 24. The negative electrode current collector tab 29 is electrically connected to a negative electrode current collector 26a of the negative electrode 26. In addition, a positive electrode terminal 25 is fixed to the metal sealing plate 23 via an insulating member 30. A positive electrode current collector tab 31 is electrically connected to the positive electrode terminal 25. The positive electrode current collector tab 31 is electrically connected to a positive electrode current collector 27a of the positive electrode 27.

[0065] Here, an example of a method for removing electrodes from the non-injected waste battery 12 will be described. The non-injected waste battery 12 is, for example, a non-standard battery that may occur before the injection step S22 in battery manufacturing. First, the exterior member is separated from the non-injected waste battery 12. Next, the positive electrode and the negative electrode contained in the battery from which the exterior member has been removed are separated. Each step will be described in detail below. <Exterior separation> The non-electrolyte-injected waste battery 12 is disassembled to separate the exterior member. The exterior separation may be performed using an exterior separation device.

[0066] The exterior separation device may be housed in the chamber together with the positive and negative electrode separation device. The interior of the chamber is preferably a low-oxygen atmosphere such as a nitrogen atmosphere. This makes it possible to prevent the electrolyte and the like from coming into contact with air when the battery is disassembled, thereby making the work safer. The exterior separation device is used to open the exterior member of the battery by cutting it, for example, and to take out the electrode group inside the exterior member to the outside. For example, a cutter, a cutting machine, a cutter, or the like can be used as the exterior separation device. The electrode group is taken out of the battery by separating the exterior. Next, the positive electrode and the negative electrode contained in the electrode group are separated. <Positive and negative electrode separation> The positive and negative electrodes included in the electrode group are separated. The positive and negative electrodes may be separated using a positive / negative electrode separator.

[0067] The positive and negative electrode separation device is for separating the electrode group into a positive electrode, a separator, and a negative electrode. The electrode group is obtained as a stack body in which a positive electrode and a negative electrode are stacked with a separator between them, such as a positive electrode, a separator, a negative electrode, a separator, and a positive electrode, or as a wound body in which a positive electrode, a separator, and a negative electrode are wound. For example, in the case of an electrode group using a continuous separator, a device having a mechanism for winding the separator is used as the positive and negative electrode separation device. In this way, the positive electrode and the negative electrode can be separated on the front and back sides of the separator. By separating the positive and negative electrodes in advance in this way, the components constituting the positive and negative electrodes do not mix with each other, and can be effectively recycled. The separation device may be divided into an exterior separation device and a positive and negative electrode separation device as described above, but it may also be a device that has both the functions of exterior separation and positive and negative electrode separation.

[0068] The electrode (eg, negative electrode) separated from the non-electrolyte-filled waste battery 12 by the above-described exterior separation and positive / negative electrode separation is subjected to a recycling process according to a method including steps S1 to S3.

[0069] According to the second embodiment, since a battery is manufactured using the electrodes regenerated by the method of the first embodiment, it becomes possible to manufacture batteries with a high recycling rate. In addition, the regenerated electrodes have excellent electronic conductivity and can suppress the deterioration of the active material, so that a battery with excellent durability can be realized.

[0070] A specific example of the electrode recycling method of the embodiment will be described below. First, the target electrode is removed from the non-injected waste battery. When the exterior member of the non-injected waste battery is a metal can, the target electrode is removed by the method described below. The non-injected waste battery is set in an exterior separation device installed in a chamber set to a nitrogen atmosphere, and the exterior member (can) is cut to remove the electrode group. Furthermore, this electrode group is placed in a positive / negative electrode separation device installed in the chamber, and separated into a positive electrode, a separator, and a negative electrode. For example, a negative electrode is used as the target electrode. A positive electrode can also be used instead of the negative electrode.

[0071] This negative electrode includes a layer containing 80% by mass of niobium titanium oxide particles represented by Nb2TiO7 as a negative electrode active material, 5% by mass of acetylene black as a conductor, 5% by mass of carbon nanotubes, and 10% by mass of CMC as a binder, and a first current collector made of aluminum foil. The binder is decomposed by baking the negative electrode at 450°C for about 30 minutes in air to obtain a baked product. The decomposition temperature of CMC as a binder is about 350°C. The baking temperature of 450°C is 210°C lower than the melting point (about 660°C) of the first current collector. The organic components can be reduced by baking by a weight equivalent to about 10% of the weight of the organic components contained in the negative electrode. The organic components here are a conductor and a binder.

[0072] The fired product of the first current collector is separated from the fired product by sieving. This results in a mixture containing a negative electrode active material and a conductor. The content of the conductor in the mixture may vary depending on the effects of temperature unevenness during firing, the arrangement of the negative electrode in the firing furnace, and the like. The content of the conductor in the mixture is up to 10% by mass. CMC and water are added to the mixture so that the composition of the negative electrode active material-containing layer becomes the target composition, and these are crushed to a predetermined particle size, and then SBR is added to these and stirred to prepare a slurry. SBR can increase the binding property of the active material-containing layer. The obtained slurry is applied to a second current collector made of aluminum foil, and then dried and pressed to prepare an electrode. In the obtained electrode, carbon nanotubes are present so as to be entangled on the surface of the niobium titanium oxide particles. In addition, acetylene black is also present on the surface of the niobium titanium oxide particles. Therefore, a good conductive path is formed between the niobium titanium oxide particles, and an electrode with excellent electronic conductivity is provided. In addition, since niobium titanium oxide is not easily deteriorated by moisture, sintering in air hardly deteriorates the niobium titanium oxide. Therefore, an electrode with a long life can be obtained. Furthermore, since the electrode can be regenerated from waste materials generated in the manufacturing process, the amount of waste materials to be disposed of can be reduced. This can increase the recycling rate of the electrode. In addition, the manufacturing cost can be reduced. An example of a method for recycling a negative electrode according to the above embodiment will be described below. Example 1 The negative electrode to be recycled was taken out from the non-injected waste battery. Since the exterior member of the non-injected waste battery was a metal can, the target negative electrode was taken out by the method described in the above specific example. The target negative electrode contained a negative electrode active material-containing layer containing 80 mass% niobium titanium oxide particles represented by Nb2TiO7 as a negative electrode active material, 5 mass% acetylene black as a conductor, 5 mass% carbon nanotubes, 6 mass% CMC and 4 mass% SBR as binders, and a first current collector made of aluminum foil. The negative electrode was baked in air at 450°C for about 30 minutes to decompose the binder and obtain a baked product. The decomposition temperature of CMC, which is a binder, was about 350°C. The decomposition temperature of SBR was 400°C. Therefore, the baking temperature of 450°C was higher than the decomposition temperature of the binder. In addition, the baking temperature of 450°C was 210°C lower than the melting point (about 660°C) of the first current collector. The organic components equivalent to about 10% of the weight of the organic components contained in the negative electrode were reduced by baking. The organic components here were the conductor and the binder. The fired product of the first current collector was separated from the fired product by sieving. This resulted in a mixture containing a negative electrode active material and a conductor. The content of the conductor in the mixture was measured and compared with the initial value (10% by mass in this case), which was 1% by mass less than the initial value. To the mixture obtained, 6 mass% CMC and 4 mass% SBR as binders and water as a solvent were added and stirred to prepare a slurry. The obtained slurry was applied onto an aluminum foil second current collector, and then dried and pressed to prepare the negative electrode of Example 1. As a result of evaluating the charge-discharge characteristics of the negative electrode of Example 1, a discharge capacity of 99% was obtained compared to a new negative electrode. The new negative electrode was produced without using materials extracted by recycling. Specifically, the new negative electrode was produced by mixing a negative electrode active material, a conductor, a binder, and water to prepare a slurry having the same composition as the negative electrode to be recycled, applying the obtained slurry onto an aluminum foil current collector, and then drying and pressing the slurry. Example 2 In the same manner as in Example 1, a mixture containing a negative electrode active material and a conductor was obtained. To the mixture obtained, 1% by mass of carbon nanotubes, 6% by mass of CMC and 4% by mass of SBR as binders, and water as a solvent were added and stirred to prepare a slurry. The obtained slurry was applied onto an aluminum foil second current collector, and then dried and pressed to prepare a negative electrode of Example 2. The charge / discharge characteristics of the negative electrode of Example 2 were evaluated, and as a result, a discharge capacity of 100% was obtained in comparison with a new negative electrode. Example 3 In the same manner as in Example 1, a mixture containing a negative electrode active material and a conductor was obtained. To the mixture obtained, 2% by mass of carbon nanotubes, 6% by mass of CMC and 4% by mass of SBR as binders, and water as a solvent were added and stirred to prepare a slurry. The obtained slurry was applied onto an aluminum foil second current collector, and then dried and pressed to prepare a negative electrode of Example 3. The charge / discharge characteristics of the negative electrode of Example 3 were evaluated, and as a result, a discharge capacity of 98% was obtained in comparison with a new negative electrode.

[0073] According to at least one of the above-described embodiments or examples of the electrode recycling method, the method includes heat-treating the target electrode at a temperature lower than the melting point of the first current collector to decompose the binder, separating the first current collector from the obtained heat-treated product, and preparing an electrode using the obtained mixture. According to this method, the binder of the target electrode can be reduced by decomposition, so that the first current collector can be easily separated from the heat-treated product without crushing the obtained heat-treated product. In addition, since the mixture obtained by separation contains a conductor, it is easy to form a conductive path between active materials, and deterioration of the active materials can be suppressed, and the performance of the regenerated electrode can be improved. Furthermore, since the electrode can be regenerated from waste materials that may be generated in the manufacturing process, the amount of waste materials to be disposed of can be reduced. This can increase the recycling rate of the electrode. In addition, the manufacturing cost can be reduced.

[0074] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims.

[0075] The invention according to the embodiment will be described below. <1> a step of heat-treating a target electrode including a first current collector and an active material-containing layer supported on the first current collector and including an active material, a binder, and a conductor, at a temperature lower than the melting point of the first current collector to decompose the binder, thereby obtaining a heat-treated product; obtaining a mixture containing the active material and the conductor by separating the first current collector from the heat-treated product; manufacturing an electrode using the mixture; A method for recycling electrodes comprising the steps of: <2> The conductor comprises a carbon material. <1> A method for recycling the electrode according to claim 1. <3> The carbon material includes carbon nanotubes. <2> A method for recycling the electrode according to claim 1. <4> The content of the carbon material in the mixture is 0.1% by mass or more and 10% by mass or less. <2> or <3> A method for recycling the electrode according to claim 1. <5> the heat treatment temperature is 20° C. or more lower than the melting point of the first current collector; <1> ~ <4> 2. The method for recycling an electrode according to claim 1 . <6> The heat treatment temperature is equal to or higher than the decomposition temperature of the binder. <1> ~ <5> 2. The method for recycling an electrode according to claim 1 . <7> The active material is substantially free of Li. <1> ~ <6> 2. The method for recycling an electrode according to claim 1 . <8> The active material is an oxide. <1> ~ <7> 2. The method for recycling an electrode according to claim 1 . <9> The oxide includes at least one of a niobium-containing oxide or a niobium titanium-containing oxide; <1> ~ <8> 2. The method for recycling an electrode according to claim 1 . <10> The heat treatment is carried out in air. <1> ~ <9> 2. The method for recycling an electrode according to claim 1 . <11> The heat treatment is performed so that the weight of the organic component contained in the target electrode is reduced by 10% to 90% of the weight of the organic component. <1> ~ <10> 2. The method for recycling an electrode according to claim 1 . <12> The manufacturing of the electrode includes a step of preparing a slurry using the mixture, and a step of applying the slurry to a second current collector. <1> ~ <11> 2. The method for recycling an electrode according to claim 1 . <13> <1> ~ <12> A battery manufacturing method comprising the steps of: manufacturing a battery by using an electrode recycled by any one of the methods described above. [Explanation of symbols]

[0076] 1...target electrode, 2...first current collector, 3...active material-containing layer, 11...waste electrode, 12...waste battery without liquid injection, 20...nonaqueous electrolyte battery, 21...metal container, 22...electrode group, 23...metal sealing plate, 24...negative electrode terminal, 25...positive electrode terminal, 26...negative electrode, 26a...negative electrode current collector, 26b...negative electrode active material-containing layer, 27...positive electrode, 27a...positive electrode current collector, 27b...positive electrode active material-containing layer, 28...separator, 29...negative electrode current collector tab, 30...insulating member, 31...positive electrode current collector tab, S1...heat treatment of target electrode, S2...separation of first current collector, S3...manufacture of electrode, S11...preparation of slurry (dispersion), S12...coating, S13...drying, S14...pressing, S15...cutting, S21...assembly, S22...pouring liquid, S23...product. < / gc>

Claims

1. a step of heat-treating a target electrode including a first current collector and an active material-containing layer supported on the first current collector and including an active material, a binder, and a conductor, at a temperature lower than the melting point of the first current collector to decompose the binder, thereby obtaining a heat-treated product; obtaining a mixture containing the active material and the conductor by separating the first current collector from the heat-treated product; manufacturing an electrode using the mixture; A method for recycling electrodes comprising the steps of:

2. The method for recycling electrodes according to claim 1 , wherein the conductor comprises a carbon material.

3. The method for recycling electrodes according to claim 2 , wherein the carbon material comprises carbon nanotubes.

4. The method for recycling electrodes according to claim 2 , wherein the content of the carbon material in the mixture is from 0.1% by mass to 10% by mass.

5. The method for recycling electrodes according to claim 1 , wherein the heat treatment temperature is lower by 20° C. or more than the melting point of the first current collector.

6. The method for recycling electrodes according to claim 1 , wherein the heat treatment temperature is equal to or higher than a decomposition temperature of the binder.

7. The method for recycling an electrode according to claim 1 , wherein the active material is substantially free of Li.

8. The method for recycling an electrode according to claim 1 , wherein the active material is an oxide.

9. 9. The method for recycling electrodes according to claim 8, wherein the oxide comprises at least one of a niobium-containing oxide or a niobium titanium-containing oxide.

10. The method for recycling electrodes according to claim 1 , wherein the heat treatment is carried out in air.

11. 2. The method for recycling electrodes according to claim 1, wherein the heat treatment is carried out so as to reduce an amount of the organic components contained in the target electrode by a weight equivalent to 10% to 90% of the weight of the organic components.

12. The method for recycling an electrode according to claim 1 , wherein the manufacturing of the electrode includes the steps of preparing a slurry using the mixture and applying the slurry to a second current collector.

13. measuring the content of the conductor in the mixture obtained; determining a composition of the electrode to be produced based on the content of the conductor; The method for recycling electrodes according to claim 1 , wherein the manufacturing of the electrode using the mixture is performed by manufacturing an electrode having a determined composition using the mixture.

14. A method for producing a battery, comprising producing a battery using an electrode recycled by the method according to any one of claims 1 to 13.

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