Method for manufacturing nonaqueous electrolyte storage element and method for reusing active material and conductive aid

Abstract

To provide a method for manufacturing a nonaqueous electrolyte storage element and a method for reusing active materials and conductive aid.SOLUTION: A method for manufacturing a nonaqueous electrolyte storage element in accordance with an aspect of the present invention includes: preparing a recovery electrode for the nonaqueous electrolyte storage element having a base material and an active material layer laminated to the base material and containing an active material, a conductive aid, and a binder; heating the recovery electrode at a temperature lower than the pyrolysis temperature of the conductive aid; separating the base material from the active material layer and recovering the active material and conductive aid contained in the active material layer; and making a new electrode using the recovered active material and conductive aid.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a non-aqueous electrolyte storage element and a method for recycling an active material and a conductive assistant.

Background Art

[0002] Non-aqueous electrolyte secondary batteries typified by lithium-ion secondary batteries are widely used in electronic devices such as personal computers and communication terminals, and automobiles, etc. due to their high energy density. A non-aqueous electrolyte secondary battery generally has a pair of electrodes electrically isolated by a separator and a non-aqueous electrolyte interposed between the electrodes, and is configured to charge and discharge by transferring charge-transporting ions between both electrodes. As non-aqueous electrolyte storage elements other than non-aqueous electrolyte secondary batteries, capacitors such as lithium-ion capacitors and electric double layer capacitors are also widely popular.

[0003] With the increasing demand for non-aqueous electrolyte storage elements, the waste derived from used non-aqueous electrolyte storage elements may increase. Also, it may become difficult to secure the raw materials of non-aqueous electrolyte storage elements. For this reason, a technology capable of efficiently recycling the raw materials of non-aqueous electrolyte storage elements is desired. As such a technology, a method (direct recycling) of taking out an active material from the electrodes of a used non-aqueous electrolyte storage element and recycling the material constituting the active material without decomposing it into a raw material compound containing constituent elements can be mentioned. Patent Document 1 describes a method for recovering a positive electrode material from a secondary battery waste material in which a metal compound is recovered by thermally decomposing a secondary battery waste material in which an electrode material is coated on a metal foil.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the positive electrode material recovery method described in Patent Document 1, after incinerating the electrode material peeled from the secondary battery waste material at a temperature of 500°C or higher, a metal compound useful as a positive electrode material (active material) is recovered, and materials other than the active material constituting the electrode material (active material layer) are not recovered. Therefore, there is room for improvement from the viewpoints of environmental load and the recycling rate of the materials constituting the active material layer.

[0006] The present invention has been made based on the above circumstances, and an object thereof is to provide a method for manufacturing a non-aqueous electrolyte storage element and a method for recycling an active material and a conductive assistant that can increase the recycling rate of the materials constituting the active material layer while reducing the environmental load.

Means for Solving the Problems

[0007] The method for manufacturing a non-aqueous electrolyte storage element according to one aspect of the present invention includes preparing a recovered electrode for a non-aqueous electrolyte storage element having a base material and an active material layer laminated on the base material and containing an active material, a conductive assistant, and a binder, heating the recovered electrode at a temperature lower than the thermal decomposition temperature of the conductive assistant, separating the base material and the active material layer to recover the active material and the conductive assistant contained in the active material layer, and manufacturing a new electrode using the recovered active material and the conductive assistant.

[0008] The method for recycling an active material and a conductive assistant according to another aspect of the present invention includes preparing a recovered electrode for a non-aqueous electrolyte storage element having a base material and an active material layer laminated on the base material and containing an active material, a conductive assistant, and a binder, heating the recovered electrode at a temperature lower than the thermal decomposition temperature of the conductive assistant, and separating the base material and the active material layer to recover the active material and the conductive assistant contained in the active material layer.

Effects of the Invention

[0009] According to any one aspect of the present invention, it is possible to provide a method for manufacturing a non-aqueous electrolyte storage element that can increase the recycling rate of materials constituting the active material layer while reducing the environmental load, and a method for recycling the active material and the conductive assistant.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0011] First, an overview of the method for manufacturing a non-aqueous electrolyte storage element and the method for recycling the active material and the conductive assistant disclosed in this specification will be described.

[0012] (1) The method for manufacturing a non-aqueous electrolyte storage element according to one aspect of the present invention includes preparing a recovered electrode for a non-aqueous electrolyte storage element having a base material and an active material layer laminated on the base material and containing an active material, a conductive assistant, and a binder, heating the recovered electrode at a temperature lower than the thermal decomposition temperature of the conductive assistant, separating the base material and the active material layer to recover the active material and the conductive assistant contained in the active material layer, and manufacturing a new electrode using the recovered active material and conductive assistant.

[0013] The method for manufacturing a non-aqueous electrolyte storage element according to (1) above includes heating the recovered electrode at a temperature lower than the thermal decomposition temperature of the conductive assistant. Therefore, the base material and the active material layer can be separated while the conductive assistant remains sufficiently in the active material layer. The active material and the conductive assistant recovered from the separated active material layer are used to produce a new electrode. That is, compared with the case of recovering only the active material from the active material layer, the environmental load is low and the recycling rate of the materials constituting the active material layer is high. In addition, since the heating temperature is lower than the thermal decomposition temperature of the conductive assistant, the energy consumption is relatively small. Therefore, the method for manufacturing a non-aqueous electrolyte storage element according to (1) above can increase the recycling rate of the materials constituting the active material layer while reducing the environmental load.

[0014] In the present invention, the "recovered electrode for a non-aqueous electrolyte storage element" means an electrode for a non-aqueous electrolyte storage element that has been recovered and is to be reused. In addition to the electrodes taken out from the non-aqueous electrolyte storage element recovered after use, it also includes electrodes taken out from the non-aqueous electrolyte storage element recovered due to initial defects even before use, electrodes taken out from the non-aqueous electrolyte storage element recovered as unused products after shipment, electrodes recovered as defective products during manufacturing, etc.

[0015] The "thermal decomposition temperature of the conductive assistant" means the temperature obtained by the following procedure. First, a measurement sample of the conductive assistant is subjected to thermogravimetric measurement (TG) in the same atmosphere as the atmosphere in the above heating. In the thermogravimetric measurement (TG), the mass of the measurement sample is 30 mg and the heating rate is 10 °C / min. Then, in the thermogravimetric curve obtained by the thermogravimetric measurement, the temperature at which the time derivative of the mass reduction amount of the measurement sample is maximum is defined as the thermal decomposition temperature of the conductive assistant.

[0016] (2) In the method for manufacturing a non-aqueous electrolyte storage element according to (1) above, the conductive assistant is a carbonaceous material, and in the above heating, the heating temperature of the recovered electrode may be 300 °C or higher and 550 °C or lower.

[0017] According to the method for manufacturing a non-aqueous electrolyte storage element described in (2) above, since the conductive assistant is a carbonaceous material and the heating temperature of the recovered electrode is 300°C or higher and 550°C or lower, it becomes easy to separate the base material and the active material layer. Further, thermal decomposition of the conductive assistant, which is a carbonaceous material, can be suppressed, and the reuse rate of the material constituting the active material layer can be easily increased.

[0018] The "heating temperature" means the maximum temperature reached on the surface of the recovered electrode, and the temperature within a range where the temperature difference from this maximum temperature reached is within 10°C. This temperature difference is preferably 5°C and more preferably 1°C.

[0019] (3) In the method for manufacturing a non-aqueous electrolyte storage element described in (2) above, the heating temperature may be higher than the thermal decomposition temperature of the binder.

[0020] According to the method for manufacturing a non-aqueous electrolyte storage element described in (3) above, since the heating temperature is higher than the thermal decomposition temperature of the binder, the base material and the active material layer can be separated in a state where the content of the binder in the active material layer is reduced. Therefore, there are few impurities contained in the recovered active material and conductive assistant, and the handleability when producing a new electrode is improved.

[0021] (4) In the method for manufacturing a non-aqueous electrolyte storage element described in (2) above, the heating temperature may be equal to or lower than the thermal decomposition temperature of the binder.

[0022] According to the method for manufacturing a non-aqueous electrolyte storage element described in the above (4), since the heating temperature is equal to or lower than the thermal decomposition temperature of the binder, the base material and the active material layer can be separated with the binder remaining in the active material layer. Therefore, in addition to the active material and the conductive assistant, the binder can also be reused. The "thermal decomposition temperature of the binder" shall be determined in the same procedure as the "thermal decomposition temperature of the conductive assistant" described above. However, when determining the thermal decomposition temperature of the binder, the solid content of the binder shall be used as the measurement sample in the above procedure, and the temperature at which the time derivative of the mass reduction of the measurement sample is maximized shall be defined as the thermal decomposition temperature of the binder.

[0023] (5) A method for reusing an active material and a conductive assistant according to another aspect of the present invention includes preparing a recovered electrode for a non-aqueous electrolyte storage element having a base material and an active material layer laminated on the base material and containing an active material, a conductive assistant, and a binder, heating the recovered electrode at a temperature lower than the thermal decomposition temperature of the conductive assistant, and separating the base material and the active material layer to recover the active material and the conductive assistant contained in the active material layer.

[0024] Since the method for reusing an active material and a conductive assistant described in the above (5) includes heating the recovered electrode at a temperature lower than the thermal decomposition temperature of the conductive assistant, the base material and the active material layer can be separated with the conductive assistant sufficiently remaining in the active material layer. The active material and the conductive assistant recovered from the separated active material layer are used to fabricate a new electrode. That is, since the conductive assistant can be sufficiently reused in addition to the active material, the environmental load is low and the recycling rate of the materials constituting the active material layer is high. Further, since the heating temperature is lower than the thermal decomposition temperature of the conductive assistant, the energy consumption is relatively small. Therefore, the method for reusing an active material and a conductive assistant described in the above (5) can increase the recycling rate of the materials constituting the active material layer while reducing the environmental load.

[0025] Hereinafter, a method for manufacturing a non-aqueous electrolyte storage element according to an embodiment of the present invention, a method for recycling an active material and a conductive assistant, and other embodiments will be described in detail. Note that the names of the constituent members (each component) used in each embodiment may be different from the names of the constituent members (each component) used in the background art.

[0026] <Method for manufacturing a non-aqueous electrolyte storage element> The method for manufacturing a non-aqueous electrolyte storage element according to an embodiment of the present invention includes preparing a recovered electrode for a non-aqueous electrolyte storage element having a base material and an active material layer laminated on the base material and containing an active material, a conductive assistant, and a binder (hereinafter, also referred to as "preparation of electrode S1"), heating the recovered electrode at a temperature lower than the thermal decomposition temperature of the conductive assistant (hereinafter, also referred to as "heating of electrode S2"), separating the base material and the active material layer to recover the active material and the conductive assistant contained in the active material layer (hereinafter, also referred to as "recovery of active material and conductive assistant S3"), and manufacturing a new electrode using the recovered active material and conductive assistant (hereinafter, also referred to as "manufacture of electrode S4").

[0027] As an optional step, the manufacturing method may include assembling a new non-aqueous electrolyte storage element including the manufactured electrode (hereinafter, also referred to as "assembly S5").

[0028] The manufacturing method does not newly synthesize an active material using the active material contained in the recovered electrode as a raw material. That is, the manufacturing method directly recycles the active material.

[0029] In the method for manufacturing a non-aqueous electrolyte storage element according to an embodiment of the present invention, as the recovered electrode to be reused, those taken out from a non-aqueous electrolyte storage element recovered after use, those taken out from a non-aqueous electrolyte storage element recovered due to initial defects or the like even before use, those taken out from a non-aqueous electrolyte storage element recovered as unused products after shipment, those recovered as defective products during manufacturing, and the like can be mentioned. Further, the recovered electrode to be reused may be either a positive electrode or a negative electrode. Both the positive electrode and the negative electrode may be reused as the recovered electrode. The active material layer of the recovered electrode may be disposed directly on the base material or may be disposed via an intermediate layer. The active material layer may contain optional components such as fillers and thickeners in addition to the active material, conductive assistant, and binder. Incidentally, when the recovered electrode is a positive electrode, the base material is also referred to as a positive electrode base material, and the active material layer is also referred to as a positive electrode active material layer. When the recovered electrode is a negative electrode, the base material is also referred to as a negative electrode base material, and the active material layer is also referred to as a negative electrode active material layer.

[0030] In one embodiment of the present invention, the recovered electrode may be a positive electrode. From the viewpoint of cost-effectiveness of reuse and the like, the active material contained in this positive electrode preferably contains a compound containing a rare metal element such as a lithium element, a nickel element, a cobalt element, or a manganese element. The active material contained in the positive electrode to be reused as the recovered electrode is preferably, for example, a lithium transition metal composite oxide, and more preferably a lithium nickel cobalt manganese composite oxide. In one embodiment of the present invention, the recovered electrode may be a negative electrode. From the viewpoint of cost-effectiveness of reuse and the like, the active material contained in this negative electrode is preferably a carbon material, and more preferably graphite and non-graphitic carbon. The conductive assistant in the recovered electrode is preferably a carbonaceous material, more preferably carbon black, and even more preferably acetylene black, from the viewpoint of achieving both stability against heating and conductivity. The binder in the recovered electrode is preferably a fluororesin, and more preferably polyvinylidene fluoride (PVDF), from the viewpoints of facilitating decomposition by heating, adhesive strength, electrochemical stability, and the like. The specific forms of the recovered electrode, active material, conductive assistant, binder, etc. to be reused in the manufacturing method will be described in detail later.

[0031] Hereinafter, each step of the method for manufacturing a non-aqueous electrolyte storage element according to an embodiment of the present invention will be described with reference to FIG. 1. Note that FIG. 1 shows the process sequence as an example in the manufacturing method as a flow chart. The manufacturing method is not limited to the process sequence of FIG. 1. Also, as described above, steps other than the preparation S1 of the electrode, the heating S2 of the electrode, the recovery S3 of the active material and the conductive assistant, and the production S4 of the electrode are optional steps.

[0032] (Preparation S1 of the electrode) In this step, a recovered electrode for a non-aqueous electrolyte storage element is prepared. The recovered electrode has a base material and an active material layer laminated on the base material and containing an active material, a conductive assistant, and a binder. The recovered electrode may be prepared by taking it out from a non-aqueous electrolyte storage element (hereinafter, also referred to as "recovered non-aqueous electrolyte storage element") recovered as a used product, recovered as an unused product after shipment, or recovered as a defective product during manufacturing. The removal of the recovered electrode from the recovered non-aqueous electrolyte storage element can be performed by disassembling the recovered non-aqueous electrolyte storage element by a known method or the like. The taken-out recovered electrode may or may not be subjected to treatments such as washing and drying. When only one of the positive and negative electrodes is used as the recovered electrode in the manufacturing method of the non-aqueous electrolyte storage element of this embodiment, the other electrode may be reused by another method different from the manufacturing method of the non-aqueous electrolyte storage element of this embodiment, or other treatments other than reuse may be performed.

[0033] In this step, the recovered electrode may be prepared by recovering the electrode before being incorporated into the non-aqueous electrolyte storage element, that is, the electrode recovered as a defective product during manufacturing. In this case, the recovered electrode is prepared without going through the process of taking out the electrode from the recovered non-aqueous electrolyte storage element.

[0034] (Heating S2 of the electrode) In this process, a recovered electrode having an active material layer containing an active material, a conductive aid, and a binder is heated at a temperature lower than the thermal decomposition temperature of the conductive aid. By heating the recovered electrode, the binder contained in the active material layer is thermally decomposed, so that in "Recovery S3 of the active material and the conductive aid" described later, the substrate and the active material layer can be easily separated. Further, since heating is performed at a temperature lower than the thermal decomposition temperature of the conductive aid, the conductive aid can be left in the active material layer. Heating of the recovered electrode can be performed using a conventionally known heat treatment apparatus or the like. When starting heating of the recovered electrode, the active material layer may be laminated on the substrate, or the active material layer may be separated from the substrate. Further, as a result of heating the recovered electrode, the active material layer may be at least partially separated from the substrate, or the active material layer may remain laminated on the substrate.

[0035] When two or more kinds of conductive aids are contained in the active material layer, it is preferable to heat at a temperature lower than the thermal decomposition temperature of the conductive aid having the lowest thermal decomposition temperature from the viewpoint of leaving a large amount of the conductive aid in the active material layer.

[0036] The recovered electrode is preferably heated in an atmosphere in which oxygen is present. By heating the recovered electrode in such an atmosphere in which oxygen is present, the binder contained in the active material layer can be easily thermally decomposed. As the atmosphere in which oxygen is present, an air atmosphere is preferable, and an oxygen atmosphere is more preferable.

[0037] The heating temperature of the recovery electrode is preferably in a temperature range that is about 50°C to 300°C, more preferably about 100°C to 280°C, still more preferably about 120°C to 260°C lower than the thermal decomposition temperature of the conductive aid. In some embodiments, the heating temperature of the recovery electrode may be in a temperature range that is about 140°C to 240°C lower than the thermal decomposition temperature of the conductive aid, or may be in a temperature range that is about 160°C to 220°C lower. The heating temperature of the recovery electrode may be in a temperature range higher than the thermal decomposition temperature of the binder. The heating temperature of the recovery electrode may be in a temperature range below the thermal decomposition temperature of the binder (for example, a temperature range that is about 0°C to 100°C, typically about 5°C to 50°C lower than the thermal decomposition temperature of the binder). By having the heating temperature of the recovery electrode in the above temperature range, thermal decomposition of the conductive aid can be suppressed, and the recycling rate of the material constituting the active material layer can be easily increased. Also, the substrate and the active material layer can be easily separated.

[0038] For example, when the conductive aid is a carbonaceous material, the lower limit of the heating temperature of the recovery electrode is preferably 300°C, more preferably 320°C, still more preferably 340°C, even more preferably 360°C, and particularly preferably 380°C. By having the heating temperature of the recovery electrode above the above lower limit, the binder contained in the active material layer can be easily thermally decomposed. Also, in one embodiment of the present invention, the heating temperature of the recovery electrode may be a temperature higher than the thermal decomposition temperature of the binder. For example, when the binder contained in the active material layer is PVDF, from the viewpoint of sufficiently reducing the content of the binder in the active material layer, the heating temperature of the recovery electrode may exceed 400°C. In this case, since the thermal decomposition temperature of PVDF is about 400°C, when the heating temperature of the recovery electrode exceeds 400°C, the impurities contained in the active material and the conductive aid recovered in "Recovery S3 of the active material and the conductive aid" described later are few, and the handleability when producing a new electrode is improved.

[0039] The upper limit of the heating temperature (maximum temperature reached) of the recovered electrode is preferably 550°C, more preferably 500°C, still more preferably 480°C, even more preferably 460°C, and particularly preferably 440°C. By keeping the heating temperature of the recovered electrode below the above upper limit, thermal decomposition of the conductive assistant can be suppressed, and the recycling rate of the materials constituting the active material layer can be easily increased. Further, in one embodiment of the present invention, the heating temperature of the recovered electrode may be equal to or lower than the thermal decomposition temperature of the binder. For example, when the binder contained in the active material layer is PVDF, from the viewpoint of separating the substrate and the active material layer with the binder remaining in the active material layer in "Recovery S3 of the active material and the conductive assistant" described later, the heating temperature of the recovered electrode may be 400°C or lower. In this case, since the thermal decomposition temperature of PVDF is about 400°C, if the heating temperature of the recovered electrode is 400°C or lower, the binder is likely to remain in the active material layer. Even when the binder remains in the active material layer, the substrate and the active material layer can be separated by locally thermally decomposing a part of the binder in the active material layer (for example, the binder in contact with the substrate) by heating. Therefore, in addition to the active material and the conductive assistant, the binder can also be reused as a material for a new electrode.

[0040] The temperature rising time when heating the recovered electrode is not particularly limited, but it may be 5 minutes or more and 150 minutes or less, may be 10 minutes or more and 120 minutes or less, or may be 15 minutes or more and 100 minutes or less. Further, the heat retention time when heating the recovered electrode is not particularly limited, but it may be 20 minutes or more and 500 minutes or less, may be 30 minutes or more and 400 minutes or less, or may be 40 minutes or more and 300 minutes or less. By keeping the temperature rising time and the heat retention time of the recovered electrode within the above ranges, the recovered electrode can be sufficiently heated while suppressing energy consumption due to heating. Here, the "temperature rising time" means the time from the start of heating until the heating temperature is reached. The "heat retention time" means the time for maintaining the heating temperature. The heat retention time may be a continuous heat retention time or the total time when heating intermittently.

[0041] (Recovery S3 of the active material and the conductive assistant) In this process, the active material and the conductive assistant contained in the active material layer are recovered. Also, when the active material layer is at least partially laminated on the substrate, the substrate and the active material layer are separated in addition to recovering the active material and the conductive assistant. For example, the active material and the conductive assistant contained in the active material layer may be recovered after separating the substrate and the active material layer, or the active material and the conductive assistant contained in the active material layer may be recovered simultaneously with separating the substrate and the active material layer. Further, when both the positive electrode and the negative electrode provided in the recovered non-aqueous electrolyte storage element are reused, the positive electrode active material and the conductive assistant contained in the positive electrode active material layer and the negative electrode active material and the conductive assistant contained in the negative electrode active material layer are recovered separately.

[0042] As a method for recovering the active material and the conductive assistant in this process, for example, the active material layer may be directly scraped off from the substrate and recovered. In this case, the recovered active material layer (active material and conductive assistant) may be pulverized by being fed to a pulverizer such as a ball mill from the viewpoint of handleability in subsequent processes. Also, the active material layer may be separated from the substrate by pulverizing the recovered electrode by feeding it to a pulverizer. In this case, the pulverized material of the active material layer containing the active material and the conductive assistant may be recovered using various sieves such as a vibrating sieve.

[0043] In this process, only the active material and the conductive assistant contained in the active material layer may be recovered, but it is preferable to recover the active material and the conductive assistant in a state where the active material and the conductive assistant contained in the active material layer are mixed with other components. For example, the pulverized material of the active material layer described above may be recovered in a state where the active material and the conductive assistant are mixed with other components. By thus collectively recovering the active material, the conductive assistant, and other components from the active material layer, it is not necessary to separate only the active material and the conductive assistant, and the efficiency of recovering the active material and the conductive assistant can be increased.

[0044] (Fabrication of Electrode S4) In this process, a new electrode is fabricated using the recovered active material and conductive additive. The new electrode can be fabricated by known methods such as mixing the recovered active material and conductive additive as optional components, preparing a compound paste using a dispersion medium, coating and drying the compound paste on a substrate. Also, a new electrode may be fabricated by adding a new active material and conductive additive to the recovered active material and conductive additive.

[0045] (Assembly S5) In this process, a new non-aqueous electrolyte storage element having a new electrode fabricated in electrode fabrication S4 using the recovered active material and conductive additive is assembled. This process can be carried out in the same manner as a conventional known non-aqueous electrolyte storage element, except that at least one of the positive and negative electrodes uses the electrode fabricated in electrode fabrication S4 using the recovered active material and conductive additive. For example, in assembly S5, an electrode body is fabricated using the new electrode fabricated in electrode fabrication S4, and the electrode body and non-aqueous electrolyte are housed in a container. When a non-aqueous electrolyte solution is used as the non-aqueous electrolyte, after injecting the non-aqueous electrolyte solution through an injection port formed in the container, the injection port is sealed to obtain a new non-aqueous electrolyte storage element.

[0046] In this process, for example, when using the positive electrode as the recovered electrode, a positive electrode produced as a new electrode using the recovered positive electrode active material and conductive assistant can be combined with a separately prepared negative electrode to produce an electrode body. Also, when using the negative electrode as the recovered electrode, a negative electrode produced as a new electrode using the recovered negative electrode active material and conductive assistant can be combined with a separately prepared positive electrode to produce an electrode body. When using both the positive electrode and the negative electrode as the recovered electrodes, a positive electrode produced as a new electrode using the recovered positive electrode active material and conductive assistant and a negative electrode produced as a new electrode using the recovered negative electrode active material and conductive assistant can be combined to produce an electrode body. Alternatively, new electrodes can be produced respectively using both the positive electrode and the negative electrode as the recovered electrodes, and each can be combined with a separately prepared electrode to produce an electrode body. The separately prepared electrode may be an electrode recycled by another method different from the method for manufacturing a non-aqueous electrolyte storage element according to an embodiment of the present invention.

[0047] The electrode body produced in this process may be a wound-type electrode body, a laminated-type electrode body, or an electrode body of other shapes. The production of the electrode body can be carried out by a conventionally known method, except that an electrode taken out from a recovered non-aqueous electrolyte storage element is used for at least one of the positive electrode and the negative electrode. For example, an electrode body can be produced by laminating or winding the positive electrode and the negative electrode with a separator in between.

[0048] (Other processes, etc.) The method for manufacturing a non-aqueous electrolyte storage element according to an embodiment of the present invention may further include other processes other than the above-described respective processes. For example, in the manufacturing method, washing, drying, etc. of the recovered electrode may be performed. Washing, drying, etc. may be performed multiple times at appropriate timings. Also, the recovered electrode may be cut, etc. before the recovery S3 of the active material and the conductive assistant.

[0049] According to the method for manufacturing a non-aqueous electrolyte storage element according to an embodiment of the present invention, it is possible to increase the recycling rate of the materials constituting the active material layer while reducing the environmental load. The structure and the like of the new non-aqueous electrolyte storage element obtained by the manufacturing method are not particularly limited. Hereinafter, the specific form of the recovered electrode to be recycled, the specific form of the recovered non-aqueous electrolyte storage element, and the specific form of the obtained new non-aqueous electrolyte storage element will be collectively described. However, the recovered electrode and the electrode included in the new non-aqueous electrolyte storage element may have different structures, shapes, sizes, performances, uses, etc., or may be the same. Further, when the recovered electrode is taken out from the recovered non-aqueous electrolyte storage element, the recovered non-aqueous electrolyte storage element and the new non-aqueous electrolyte storage element may have different structures, shapes, sizes, performances, uses, etc., or may be the same.

[0050] (Recovered non-aqueous electrolyte storage element and new non-aqueous electrolyte storage element) The recovered non-aqueous electrolyte storage element and the new non-aqueous electrolyte storage element (hereinafter, simply referred to as "non-aqueous electrolyte storage element") include an electrode body having a positive electrode, a negative electrode, and a separator, a non-aqueous electrolyte, and a container for housing the electrode body and the non-aqueous electrolyte. The electrode body is usually a laminated type in which a plurality of positive electrodes and a plurality of negative electrodes are laminated via a separator, or a wound type in which a positive electrode and a negative electrode are wound in a state of being laminated via a separator. The non-aqueous electrolyte exists in a state of being impregnated into the positive electrode, the negative electrode, and the separator. As an example of the non-aqueous electrolyte storage element, a non-aqueous electrolyte secondary battery (hereinafter, also simply referred to as "secondary battery") will be described.

[0051] (Positive electrode) The positive electrode as the recovered electrode and the positive electrode included in the new non-aqueous electrolyte storage element (hereinafter, simply referred to as "positive electrode") have a positive electrode substrate and a positive electrode active material layer disposed directly or via an intermediate layer on the positive electrode substrate.

[0052] The positive electrode substrate has conductivity. Whether it has "conductivity" is determined by the volume resistivity measured in accordance with JIS-H-0505 (1975) being 10 -2It is determined using Ω·cm as the threshold value. As the material of the positive electrode substrate, metals such as aluminum, titanium, tantalum, stainless steel, or alloys thereof are used. Among these, aluminum or an aluminum alloy is preferable from the viewpoints of corrosion resistance, high conductivity, and cost. Examples of the positive electrode substrate include foil, vapor deposition film, mesh, porous material, etc., and foil is preferable from the viewpoint of cost. Therefore, as the positive electrode substrate, aluminum foil or aluminum alloy foil is preferable. Examples of aluminum or an aluminum alloy include A1085, A3003, A1N30, etc. defined in JIS-H-4000 (2014) or JIS-H-4160 (2006).

[0053] The average thickness of the positive electrode substrate is preferably 3 μm or more and 50 μm or less, more preferably 5 μm or more and 40 μm or less, still more preferably 8 μm or more and 30 μm or less, and particularly preferably 10 μm or more and 25 μm or less. By setting the average thickness of the positive electrode substrate within the above range, it is possible to increase the strength of the positive electrode substrate while increasing the energy density per unit volume of the non-aqueous electrolyte storage element.

[0054] The intermediate layer is a layer disposed between the positive electrode substrate and the positive electrode active material layer. The intermediate layer contains a conductive auxiliary agent such as carbon particles to reduce the contact resistance between the positive electrode substrate and the positive electrode active material layer. The configuration of the intermediate layer is not particularly limited, and for example, it contains a binder and a conductive auxiliary agent.

[0055] The positive electrode active material layer contains a positive electrode active material. In one embodiment of the present invention, when the recovered electrode is a positive electrode, the positive electrode active material layer of the positive electrode further contains a conductive auxiliary agent and a binder, and the positive electrode active material layer of the positive electrode provided in the new non-aqueous electrolyte storage element contains a conductive auxiliary agent and a binder as required. The positive electrode active material layer may further contain optional components such as a thickener and a filler as required.

[0056] The positive electrode active material can be appropriately selected from known positive electrode active materials. As the positive electrode active material for a lithium-ion secondary battery, a material that can occlude and release lithium ions is usually used. Examples of the positive electrode active material include lithium transition metal composite oxides having an α-NaFeO2-type crystal structure, lithium transition metal composite oxides having a spinel-type crystal structure, polyanion compounds, chalcogen compounds, sulfur, and the like. Examples of the lithium transition metal composite oxide having an α-NaFeO2-type crystal structure include Li[Li x Ni (1-x) O2 (0 ≦ x < 0.5), Li[Li x Ni γ Co (1-x-γ) O2 (0 ≦ x < 0.5, 0 < γ < 1, 0 < 1 - x - γ), Li[Li x Co (1-x) O2 (0 ≦ x < 0.5), Li[Li x Ni γ Mn (1-x-γ) O2 (0 ≦ x < 0.5, 0 < γ < 1, 0 < 1 - x - γ), Li[Li x Ni γ Mn β Co (1-x-γ-β) O2 (0 ≦ x < 0.5, 0 < γ, 0 < β, 0.5 < γ + β < 1, 0 < 1 - x - γ - β), Li[Li x Ni γ Co β Al (1-x-γ-β) O2 (0 ≦ x < 0.5, 0 < γ, 0 < β, 0.5 < γ + β < 1, 0 < 1 - x - γ - β), etc. Examples of the lithium transition metal composite oxide having a spinel-type crystal structure include Li x Mn2O4, Li x Ni γ Mn (2-γ)Examples include O4. Examples of the polyanion compound include LiFePO4, LiMnPO4, LiNiPO4, LiCoPO4, Li3V2(PO4)3, Li2MnSiO4, Li2CoPO4F, etc. Examples of the chalcogen compound include titanium disulfide, molybdenum disulfide, molybdenum dioxide, etc. Atoms or polyanions in these materials may be partially substituted with atoms or anion species composed of other elements. These materials may have their surfaces coated with other materials. In the positive electrode active material layer, one of these materials may be used alone, or two or more of them may be mixed and used.

[0057] As the positive electrode active material, it is preferably a lithium-transition metal composite oxide containing a lithium element, and more preferably a lithium-transition metal composite oxide having an α-NaFeO2 type crystal structure. Further, as the positive electrode active material, it preferably contains at least one of nickel element, cobalt element and manganese element, more preferably contains nickel element, cobalt element and manganese element, and even more preferably is a lithium nickel cobalt manganese composite oxide. One kind or two or more kinds of positive electrode active materials can be used.

[0058] Examples of the lithium-transition metal composite oxide include, for example, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiNi 3 / 5 Co 1 / 5 Mn 1 / 5 O2, LiNi 1 / 2 Co 1 / 5 Mn 3 / 10 O2, LiNi 1 / 2 Co 3 / 10 Mn 1 / 5 O2, LiNi 8 / 10 Co 1 / 10 Mn 1 / 10 O2, LiNi 0.8 Co 0.15 Al 0.05 O2, etc.

[0059] Of all the positive electrode active materials in the positive electrode active material layer, the content of the lithium transition metal composite oxide is preferably 50% by mass or more (preferably 70 to 100% by mass, more preferably 80 to 100% by mass). Further, it is more preferable that the positive electrode active material layer substantially has only the lithium transition metal composite oxide as the positive electrode active material.

[0060] The positive electrode active material is usually particles (powder). The average particle size of the positive electrode active material is preferably, for example, 0.1 μm or more and 20 μm or less. By setting the average particle size of the positive electrode active material to be not less than the above lower limit, the production or handling of the positive electrode active material becomes easy. By setting the average particle size of the positive electrode active material to be not more than the above upper limit, the electron conductivity of the positive electrode active material layer is improved. When using a composite of the positive electrode active material and other materials, the average particle size of the composite is taken as the average particle size of the positive electrode active material. The "average particle size" means a value at which the volume-based cumulative distribution calculated in accordance with JIS-Z-8819-2 (2001) based on the particle size distribution measured by the laser diffraction / scattering method for a dilution obtained by diluting the particles with a solvent conforms to JIS-Z-8825 (2013).

[0061] To obtain powder with a predetermined particle size, a pulverizer, a classifier, etc. are used. Examples of the pulverization method include methods using a mortar, a ball mill, a sand mill, a vibration ball mill, a planetary ball mill, a jet mill, a counter jet mill, a swirling air flow type jet mill, or a sieve. During pulverization, wet pulverization in which water or an organic solvent such as hexane coexists can also be used. As the classification method, a sieve, an air classifier, etc. are used as needed for both dry and wet processes.

[0062] The content of the positive electrode active material in the positive electrode active material layer is preferably 50% by mass or more and 99% by mass or less, more preferably 70% by mass or more and 98% by mass or less, and even more preferably 80% by mass or more and 95% by mass or less. By setting the content of the positive electrode active material within the above range, both high energy density and manufacturability of the positive electrode active material layer can be achieved.

[0063] The conductive aid is not particularly limited as long as it is a material having conductivity. Examples of such conductive aids include carbonaceous materials, metals, conductive ceramics, etc. Examples of carbonaceous materials include graphite, non-graphitic carbon, graphene-based carbon, etc. Examples of non-graphitic carbon include carbon nanofibers, pitch-based carbon fibers, carbon black, etc. Examples of carbon black include furnace black, acetylene black, ketjen black, etc. Examples of graphene-based carbon include graphene, carbon nanotube (CNT), fullerene, etc. From the viewpoint of achieving both stability against heating and conductivity, carbonaceous materials are preferable as the conductive aid, carbon black is more preferable, and acetylene black is even more preferable. Examples of the shape of the conductive aid include powder form, fibrous form, etc. As the conductive aid, one of these materials may be used alone, or two or more of them may be mixed and used. Also, these materials may be used in a composite form. For example, a material in which carbon black and CNT are composite may be used.

[0064] The content of the conductive aid in the positive electrode active material layer is preferably 1% by mass or more and 10% by mass or less, and more preferably 3% by mass or more and 9% by mass or less. By setting the content of the conductive aid within the above range, the energy density of the non-aqueous electrolyte storage element can be increased.

[0065] Examples of the binder include thermoplastic resins such as fluororesins (polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), etc.), polyethylene, polypropylene, polyacrylic, polyimide, etc.; elastomers such as ethylene-propylene-diene rubber (EPDM), sulfonated EPDM, styrene-butadiene rubber (SBR), fluororubber, etc.; polysaccharide polymers, etc. From the viewpoints of facilitating decomposition by heating, adhesive force, electrochemical stability, etc., fluororesins are preferable as the binder, and polyvinylidene fluoride (PVDF) is more preferable.

[0066] The content of the binder in the positive electrode active material layer is preferably 1% by mass or more and 10% by mass or less, more preferably 3% by mass or more and 9% by mass or less. By setting the content of the binder within the above range, the positive electrode active material can be stably held.

[0067] Examples of the thickener include polysaccharide polymers such as carboxymethyl cellulose (CMC) and methyl cellulose. When the thickener has a functional group that reacts with lithium or the like, this functional group may be deactivated in advance by methylation or the like. When using a thickener, the content of the thickener in the positive electrode active material layer is preferably 5% by mass or less, more preferably 1% by mass or less. The positive electrode active material layer may not contain a thickener.

[0068] The filler is not particularly limited. Examples of the filler include polyolefins such as polypropylene and polyethylene, inorganic oxides such as silicon dioxide, alumina, titanium dioxide, calcium oxide, strontium oxide, barium oxide, magnesium oxide, and aluminosilicate, hydroxides such as magnesium hydroxide, calcium hydroxide, and aluminum hydroxide, carbonates such as calcium carbonate, sparingly soluble ionic crystals such as calcium fluoride, barium fluoride, and barium sulfate, nitrides such as aluminum nitride and silicon nitride, and mineral resource-derived substances such as talc, montmorillonite, boehmite, zeolite, apatite, kaolin, mullite, spinel, olivine, sericite, bentonite, and mica, or artificial products thereof. When using a filler, the content of the filler in the positive electrode active material layer is preferably 5% by mass or less, more preferably 1% by mass or less. The positive electrode active material layer may not contain a filler.

[0069] The positive electrode active material layer may contain typical non-metal elements such as B, N, P, F, Cl, Br, and I, typical metal elements such as Li, Na, Mg, Al, K, Ca, Zn, Ga, Ge, Sn, Sr, and Ba, and transition metal elements such as Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Mo, Zr, and Nb as components other than the positive electrode active material, conductive assistant, binder, thickener, and filler.

[0070] Negative electrode The negative electrode as a recovered electrode and the negative electrode included in a new non-aqueous electrolyte storage element (hereinafter simply referred to as "negative electrode") have a negative electrode substrate and a negative electrode active material layer disposed directly or via an intermediate layer on the negative electrode substrate. The configuration of the intermediate layer is not particularly limited, and for example, it can be selected from the configurations exemplified for the positive electrode above.

[0071] The negative electrode substrate has conductivity. As the material of the negative electrode substrate, metals such as copper, nickel, stainless steel, nickel-plated steel, or alloys thereof, carbon materials, etc. are used. Among these, copper or a copper alloy is preferable. Examples of the negative electrode substrate include foil, vapor deposition film, mesh, porous material, etc., and foil is preferable from the viewpoint of cost. Therefore, a copper foil or a copper alloy foil is preferable as the negative electrode substrate. Examples of the copper foil include rolled copper foil, electrolytic copper foil, etc.

[0072] The average thickness of the negative electrode substrate is preferably 2 μm or more and 35 μm or less, more preferably 3 μm or more and 30 μm or less, still more preferably 4 μm or more and 25 μm or less, and particularly preferably 5 μm or more and 20 μm or less. By setting the average thickness of the negative electrode substrate within the above range, it is possible to increase the strength of the negative electrode substrate while increasing the energy density per volume of the non-aqueous electrolyte storage element.

[0073] The negative electrode active material layer contains a negative electrode active material. In one embodiment of the present invention, when the recovered electrode is a negative electrode, the negative electrode active material layer of the negative electrode further contains a conductive assistant and a binder, and the negative electrode active material layer of the negative electrode included in the new non-aqueous electrolyte storage element contains a conductive assistant and a binder as required. The negative electrode active material layer may further contain optional components such as a thickener, a filler, etc. as required. The conductive assistant, binder, thickener, filler, etc. can be selected from the materials exemplified for the positive electrode above.

[0074] The negative electrode active material layer may contain, as components other than the negative electrode active material, conductive assistant, binder, thickener, and filler, typical non-metal elements such as B, N, P, F, Cl, Br, I, etc., typical metal elements such as Li, Na, Mg, Al, K, Ca, Zn, Ga, Ge, Sn, Sr, Ba, etc., and transition metal elements such as Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Mo, Zr, Ta, Hf, Nb, W, etc.

[0075] As the negative electrode active material, it can be appropriately selected from known negative electrode active materials. As the negative electrode active material for a lithium-ion secondary battery, a material that can occlude and release lithium ions is usually used. Examples of the negative electrode active material include metallic lithium; metals or semi-metals such as Si and Sn; metal oxides or semi-metal oxides such as Si oxide, Ti oxide, and Sn oxide; Li4Ti5O 12 、LiTiO 2、 titanium-containing oxides such as TiNb2O7; polyphosphoric acid compounds; silicon carbide; carbon materials such as graphite (graphite), non-graphitic carbon (easily graphitizable carbon or hardly graphitizable carbon), etc. Among these materials, graphite and non-graphitic carbon are preferred. In the negative electrode active material layer, one of these materials may be used alone, or two or more of them may be mixed and used.

[0076] "Graphite" refers to a carbon material with an average lattice plane spacing (d 002 ) of the (002) plane determined by X-ray diffraction method of 0.33 nm or more and less than 0.34 nm before charge and discharge or in the discharged state. Examples of graphite include natural graphite and artificial graphite. From the perspective of obtaining materials with stable physical properties, artificial graphite is preferred.

[0077] "Non-graphitic carbon" refers to a carbon material with an average lattice plane spacing (d 002 ) of the (002) plane determined by X-ray diffraction method of 0.34 nm or more and 0.42 nm or less before charge and discharge or in the discharged state. Examples of non-graphitic carbon include hardly graphitizable carbon and easily graphitizable carbon. Examples of non-graphitic carbon include materials derived from resins, petroleum pitch or materials derived from petroleum pitch, petroleum coke or materials derived from petroleum coke, plant-derived materials, alcohol-derived materials, etc.

[0078] Here, the "discharged state" of the carbon material means a state in which lithium ions that can be occluded and released with charge and discharge are sufficiently released from the carbon material serving as the negative electrode active material. For example, in a half-cell using a negative electrode containing a carbon material as the working electrode and metallic lithium as the counter electrode, it is a state where the open circuit voltage is 0.7 V or more.

[0079] "Graphitization-resistant carbon" refers to a carbon material where the above d 002 is 0.36 nm or more and 0.42 nm or less.

[0080] "Graphitization-easy carbon" refers to a carbon material where the above d 002 is 0.34 nm or more and less than 0.36 nm.

[0081] The negative electrode active material is usually particles (powder). The average particle diameter of the negative electrode active material can be, for example, 1 nm or more and 100 μm or less. When the negative electrode active material is a carbon material, a titanium-containing oxide, or a polyphosphoric acid compound, its average particle diameter may be 1 μm or more and 100 μm or less. When the negative electrode active material is Si, Sn, a Si oxide, or a Sn oxide, etc., its average particle diameter may be 1 nm or more and 1 μm or less. By setting the average particle diameter of the negative electrode active material to be equal to or greater than the above lower limit, the production or handling of the negative electrode active material becomes easy. By setting the average particle diameter of the negative electrode active material to be equal to or less than the above upper limit, the electron conductivity of the negative electrode active material layer is improved. A crusher, a classifier, etc. are used to obtain powder with a predetermined particle diameter. When the negative electrode active material is a metal such as metallic lithium, the negative electrode active material layer may be in the form of a foil.

[0082] The content of the negative electrode active material in the negative electrode active material layer is preferably 60% by mass or more and 99% by mass or less, and more preferably 90% by mass or more and 98% by mass or less. By setting the content of the negative electrode active material within the above range, both high energy density and manufacturability of the negative electrode active material layer can be achieved.

[0083] (Separator) The separator can be appropriately selected from known separators. As the separator, for example, a separator composed only of a base material layer, a separator having a heat-resistant layer containing heat-resistant particles and a binder formed on one or both surfaces of the base material layer, etc. can be used. Examples of the shape of the base material layer of the separator include woven fabric, non-woven fabric, porous resin film, etc. Among these shapes, a porous resin film is preferable from the viewpoint of strength, and a non-woven fabric is preferable from the viewpoint of the liquid retention property of the non-aqueous electrolyte. As the material of the base material layer of the separator, polyolefins such as polyethylene and polypropylene are preferable from the viewpoint of the shut-down function, and polyimides, aramids, etc. are preferable from the viewpoint of oxidation decomposition resistance. As the base material layer of the separator, a material obtained by compounding these resins may be used.

[0084] The heat-resistant particles contained in the heat-resistant layer preferably have a mass loss of 5% or less when heated from room temperature to 500 °C in an air atmosphere at 1 atm, and more preferably have a mass loss of 5% or less when heated from room temperature to 800 °C. Inorganic compounds are cited as materials having a mass loss of a predetermined value or less. Examples of inorganic compounds include oxides such as iron oxide, silicon oxide, aluminum oxide, titanium oxide, zirconium oxide, calcium oxide, strontium oxide, barium oxide, magnesium oxide, and aluminosilicate; nitrides such as aluminum nitride and silicon nitride; carbonates such as calcium carbonate; sulfates such as barium sulfate; sparingly soluble ionic crystals such as calcium fluoride, barium fluoride, and barium titanate; covalent crystals such as silicon and diamond; mineral resource-derived substances such as talc, montmorillonite, boehmite, zeolite, apatite, kaolin, mullite, spinel, olivine, sericite, bentonite, mica, or artificial products thereof, etc. As the inorganic compound, these substances may be used alone as a simple substance or a composite, or two or more kinds may be mixed and used. Among these inorganic compounds, silicon oxide, aluminum oxide, or aluminosilicate is preferable from the viewpoint of the safety of the non-aqueous electrolyte storage element.

[0085] The porosity of the separator is preferably 80% by volume or less from the viewpoint of strength, and preferably 20% by volume or more from the viewpoint of discharge performance. Here, the "porosity" is a volume-based value and means the measured value by a mercury porosimeter.

[0086] As the separator, a polymer gel composed of a polymer and a non-aqueous electrolyte may be used. Examples of the polymer include polyacrylonitrile, polyethylene oxide, polypropylene oxide, polymethyl methacrylate, polyvinyl acetate, polyvinyl pyrrolidone, polyvinylidene fluoride, and the like. Using a polymer gel has the effect of suppressing liquid leakage. As the separator, a porous resin film or non-woven fabric as described above and a polymer gel may be used in combination.

[0087] (Non-aqueous electrolyte) The non-aqueous electrolyte can be appropriately selected from known non-aqueous electrolytes. A non-aqueous electrolyte solution may be used as the non-aqueous electrolyte. The non-aqueous electrolyte solution contains a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent.

[0088] The non-aqueous solvent can be appropriately selected from known non-aqueous solvents. Examples of the non-aqueous solvent include cyclic carbonates, chain carbonates, carboxylic acid esters, phosphate esters, sulfonic acid esters, ethers, amides, nitriles, and the like. As the non-aqueous solvent, those in which some of the hydrogen atoms contained in these compounds are substituted with halogens may be used.

[0089] Examples of the cyclic carbonate include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinylene carbonate (VC), vinyl ethylene carbonate (VEC), chloroethylene carbonate, fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), styrene carbonate, 1-phenylvinylene carbonate, 1,2-diphenylvinylene carbonate, and the like. Among these, EC is preferred.

[0090] Examples of the chain carbonates include diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diphenyl carbonate, trifluoroethyl methyl carbonate, bis(trifluoroethyl) carbonate, and the like. Among these, EMC is preferred.

[0091] As the non-aqueous solvent, it is preferable to use a cyclic carbonate or a chain carbonate, and it is more preferable to use a cyclic carbonate and a chain carbonate in combination. By using a cyclic carbonate, the dissociation of the electrolyte salt can be promoted and the ionic conductivity of the non-aqueous electrolyte can be improved. By using a chain carbonate, the viscosity of the non-aqueous electrolyte can be kept low. When a cyclic carbonate and a chain carbonate are used in combination, the volume ratio of the cyclic carbonate to the chain carbonate (cyclic carbonate:chain carbonate) is preferably in the range of, for example, 5:95 to 50:50.

[0092] The electrolyte salt can be appropriately selected from known electrolyte salts. Examples of the electrolyte salt include lithium salts, sodium salts, potassium salts, magnesium salts, onium salts, and the like. Among these, lithium salts are preferred.

[0093] Examples of the lithium salts include inorganic lithium salts such as LiPF6, LiPO2F2, LiBF4, LiClO4, LiN(SO2F)2; lithium oxalate salts such as lithium bis(oxalate) borate (LiBOB), lithium difluorooxalate borate (LiFOB), lithium bis(oxalate) difluorophosphate (LiFOP); and lithium salts having a halogenated hydrocarbon group such as LiSO3CF3, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiN(SO2CF3)(SO2C4F9), LiC(SO2CF3)3, LiC(SO2C2F5)3. Among these, inorganic lithium salts are preferred, and LiPF6 is more preferred.

[0094] The content of the electrolyte salt in the non-aqueous electrolyte is 0.1 mol / dm at 20 °C and 1 atm. 32.5 mol / dm or less is preferred, 0.3 mol / dm 3 or more is more preferred, 0.5 mol / dm 3 2.0 mol / dm or less is even more preferred, 0.7 mol / dm 3 or more is particularly preferred, 1.5 mol / dm 3 or less. By setting the content of the electrolyte salt within the above range, the ionic conductivity of the non-aqueous electrolyte can be increased. 3 3 3

[0095] ​​​In addition to the non-aqueous solvent and the electrolyte salt, the non-aqueous electrolyte may contain an additive. Examples of the additive include halogenated carbonates such as fluoroethylene carbonate (FEC) and difluoroethylene carbonate (DFEC); oxalates such as lithium bis(oxalato)borate (LiBOB), lithium difluorooxalate borate (LiFOB), and lithium bis(oxalato)difluorophosphate (LiFOP); imide salts such as lithium bis(fluorosulfonyl)imide (LiFSI); aromatic compounds such as biphenyl, alkyl biphenyl, terphenyl, partially hydrogenated terphenyl, cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenyl ether, and dibenzofuran; partially halogenated compounds of the above aromatic compounds such as 2-fluorobiphenyl, o-cyclohexylfluorobenzene, and p-cyclohexylfluorobenzene; halogenated anisole compounds such as 2,4-difluoroanisole, 2,5-difluoroanisole, 2,6-difluoroanisole, and 3,5-difluoroanisole; vinylene carbonate, methyl vinylene carbonate, ethyl vinylene carbonate, succinic anhydride, glutaric anhydride, maleic anhydride, citraconic anhydride, glutaconic anhydride, itaconic anhydride, cyclohexanedicarboxylic anhydride; ethylene sulfite, propylene sulfite, dimethyl sulfite, methyl methanesulfonate, busulfan, methyl toluenesulfonate, dimethyl sulfate, ethylene sulfate, sulfolane, dimethyl sulfone, diethyl sulfone, dimethyl sulfoxide, diethyl sulfoxide, tetramethylene sulfoxide, diphenyl sulfide, 4,4'-bis(2,2-dioxo-1,3,2-dioxathiolane), 4-methylsulfonyloxymethyl-2,2-dioxo-1,3,2-dioxathiolane, thioanisole, diphenyl disulfide, dipyridinium disulfide, 1,3-propenesultone, 1,3-propanesultone, 1,4-butanesultone, 1,4-butenesultone, perfluorooctane, tris(trimethylsilyl) borate, tris(trimethylsilyl) phosphate, tetrakis(trimethylsilyl) titanate, lithium monofluorophosphate, and lithium difluorophosphate. These additives may be used alone or in combination of two or more.

[0096] The content of the additive contained in the non-aqueous electrolyte is preferably 0.01% by mass or more and 10% by mass or less, more preferably 0.1% by mass or more and 7% by mass or less, still more preferably 0.2% by mass or more and 5% by mass or less, and particularly preferably 0.3% by mass or more and 3% by mass or less, based on the mass of the entire non-aqueous electrolyte. By setting the content of the additive within the above range, the capacity retention performance or cycle performance after high-temperature storage can be improved, or the safety can be further improved.

[0097] The shape of the non-aqueous electrolyte storage element is not particularly limited, and examples include cylindrical batteries, rectangular batteries, flat batteries, coin-type batteries, button-type batteries, and the like.

[0098] FIG. 2 shows a non-aqueous electrolyte storage element 1 as an example of a rectangular battery. Note that the figure is a perspective view of the inside of the container. An electrode body 2 having a positive electrode and a negative electrode wound with a separator interposed therebetween is housed in a rectangular container 3. The positive electrode is electrically connected to the positive electrode terminal 4 via the positive electrode lead 41. The negative electrode is electrically connected to the negative electrode terminal 5 via the negative electrode lead 51.

[0099] (Power storage device) The non-aqueous electrolyte storage element can be mounted as a power storage unit (battery module) configured by aggregating a plurality of non-aqueous electrolyte storage elements in a power source for automobiles such as electric vehicles (EVs), hybrid vehicles (HEVs), plug-in hybrid vehicles (PHEVs), a power source for electronic devices such as personal computers and communication terminals, or a power source for power storage.

[0100] Fig. 3 shows an example of a power storage device 30 formed by further aggregating power storage units 20 each formed by aggregating two or more non-aqueous electrolyte power storage elements 1 electrically connected to each other. The power storage device 30 may include a bus bar (not shown) for electrically connecting two or more non-aqueous electrolyte power storage elements 1, a bus bar (not shown) for electrically connecting two or more power storage units 20, and the like. The power storage unit 20 or the power storage device 30 may include a state monitoring device (not shown) for monitoring the state of one or more non-aqueous electrolyte power storage elements.

[0101] <Method for Recycling Active Material and Conductive Aid> A method for recycling an active material and a conductive aid according to an embodiment of the present invention includes preparing a recovered electrode for a non-aqueous electrolyte power storage element having a base material and an active material layer laminated on the base material and containing an active material, a conductive aid, and a binder (hereinafter also referred to as "electrode preparation S1"), heating the recovered electrode at a temperature lower than the thermal decomposition temperature of the conductive aid (hereinafter also referred to as "electrode heating S2"), and separating the base material and the active material layer to recover the active material and the conductive aid contained in the active material layer (hereinafter also referred to as "recovery of active material and conductive aid S3").

[0102] As an optional step, the recycling method may include producing a new electrode using the recovered active material and conductive aid (hereinafter also referred to as "electrode production S4") and assembling a new non-aqueous electrolyte power storage element including the produced electrode (hereinafter also referred to as "assembly S5").

[0103] In the recycling method, electrode preparation S1, electrode heating S2, recovery of active material and conductive aid S3, electrode production S4, and assembly S5 can be the same as the respective steps described in the manufacturing method of the non-aqueous electrolyte power storage element described above.

[0104] According to the recycling method, it is possible to increase the recycling rate of the materials constituting the active material layer while reducing the environmental load. In the recycling method, the specific form of the recovered electrode to be recycled, the specific form of the recovered non-aqueous electrolyte storage element, and the specific form of the obtained new non-aqueous electrolyte storage element can be the same as those described in the manufacturing method of the non-aqueous electrolyte storage element described above.

[0105] <Other Embodiments> Note that the manufacturing method of the non-aqueous electrolyte storage element and the recycling method of the active material and the conductive assistant of the present invention are not limited to the above embodiments, and various modifications may be made without departing from the gist of the present invention. For example, the configuration of another embodiment can be added to the configuration of a certain embodiment, and a part of the configuration of a certain embodiment can be replaced with the configuration of another embodiment or well-known technology. Furthermore, a part of the configuration of a certain embodiment can be deleted. In addition, well-known technology can be added to the configuration of a certain embodiment.

[0106] In the above embodiment, the case where the non-aqueous electrolyte storage element is used as a rechargeable non-aqueous electrolyte secondary battery (for example, a lithium-ion secondary battery) has been described. However, the type, shape, dimensions, capacity, etc. of the non-aqueous electrolyte storage element are arbitrary. The present invention can also be applied to various secondary batteries, electric double layer capacitors, or capacitors such as lithium-ion capacitors.

[0107] In the above embodiment, the electrode body in which the positive electrode and the negative electrode are laminated via a separator has been described. However, the electrode body may not include a separator. For example, the positive electrode and the negative electrode may be in direct contact with each other in a state where a non-conductive layer is formed on the active material layer of the positive electrode or the negative electrode.

Industrial Applicability

[0108] The present invention is useful as a technology for recycling electrodes for non-aqueous electrolyte storage elements.

Explanation of Reference Numerals

[0109] 1 Non-aqueous electrolyte storage element 2 Electrode body 3 Container 4 Positive electrode terminal 41 Positive electrode lead 5 Negative electrode terminal 51 Negative electrode lead 20 Power storage unit 30 Power storage device

Claims

1. Preparing a recovered electrode for a non-aqueous electrolyte storage element having a base material and an active material layer laminated on the base material and containing an active material, a conductive assistant, and a binder; Heating the recovered electrode at a temperature lower than the thermal decomposition temperature of the conductive assistant; Separating the base material and the active material layer to recover the active material and the conductive assistant contained in the active material layer; and Manufacturing a new electrode using the recovered active material and conductive assistant A method for manufacturing a non-aqueous electrolyte storage element comprising the above steps.

2. The conductive assistant is a carbonaceous material, In the above heating, the heating temperature of the recovered electrode is 300°C or higher and 550°C or lower. The method for manufacturing a non-aqueous electrolyte storage element according to Claim 1.

3. The method for manufacturing a non-aqueous electrolyte storage element according to Claim 2, wherein the heating temperature is higher than the thermal decomposition temperature of the binder.

4. The method for manufacturing a non-aqueous electrolyte storage element according to Claim 2, wherein the heating temperature is equal to or lower than the thermal decomposition temperature of the binder.

5. Preparing a recovered electrode for a non-aqueous electrolyte storage element having a base material and an active material layer laminated on the base material and containing an active material, a conductive assistant, and a binder; Heating the recovered electrode at a temperature lower than the thermal decomposition temperature of the conductive assistant; and Separating the base material and the active material layer to recover the active material and the conductive assistant contained in the active material layer A method for recycling an active material and a conductive assistant comprising the above steps.

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