Method for manufacturing nonaqueous electrolyte storage element

Abstract

To provide a method for manufacturing a nonaqueous electrolyte storage element that can easily reuse active materials that are altered by oxidation contained in recovered electrodes, and that can suppress the degradation of the performance of the active materials.SOLUTION: A method for manufacturing a nonaqueous electrolyte storage element in accordance with an aspect of the present invention comprises: 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 and a binder; heating the recovery electrode at a temperature of 400°C or higher in an atmosphere of inert or reducing gas; and separating the base material from the active material layer and recovering the active material contained in the active material layer. The active material is a single substance or a compound in which a metallic element is not directly bonded to an oxygen element.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a non-aqueous electrolyte storage element.

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. because of their high energy density. A non-aqueous electrolyte secondary battery generally has a pair of electrodes electrically separated 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 that can efficiently reuse the raw materials of non-aqueous electrolyte storage elements is desired. As such a technology, there is a method (direct recycling) of taking out an active material from the electrodes of a used non-aqueous electrolyte storage element and reusing it without decomposing the material constituting the active material into a raw material compound containing constituent elements. 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 heating waste secondary battery materials in an oxygen-containing gas stream, a metal compound useful as a positive electrode material (active material) in the electrode material is recovered. However, when the active material contained in the electrode material is a compound or the like that can be altered by oxidation, heating in an atmosphere containing oxygen gas may cause a decrease in the performance of the active material.

[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 that can easily reuse an active material that can be altered by oxidation contained in a recovered electrode and can suppress a decrease in the performance of the active material.

Means for Solving the Problems

[0007] A 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 and a binder, heating the recovered electrode at a temperature of 400°C or higher in an atmosphere of an inert gas or a reducing gas, and separating the active material layer from the base material to recover the active material contained in the active material layer, wherein the active material is a simple substance or a compound in which a metal element and an oxygen element are not directly bonded.

Effects of the Invention

[0008] 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 easily reuse an active material that can be altered by oxidation contained in a recovered electrode and can suppress a decrease in the performance of the active material.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0010] First, an outline of the method for manufacturing a non-aqueous electrolyte power storage element disclosed in this specification will be described.

[0011] (1) The method for manufacturing a non-aqueous electrolyte power storage element according to one aspect 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 and a binder, heating the recovered electrode at a temperature of 400° C. or higher in an atmosphere of an inert gas or a reducing gas, and separating the active material layer from the base material to recover the active material contained in the active material layer. The active material is a single substance or a compound in which a metal element and an oxygen element are not directly bonded.

[0012] The method for manufacturing a non-aqueous electrolyte power storage element described in the above (1) can easily reuse the active material that can be altered by oxidation contained in the recovered electrode and can suppress a decrease in the performance of the active material. The reasons therefor will be described below. In a conventional direct recycling process, in order to separate the active material layer from the recovered electrode, the recovered electrode may be heated in an atmosphere containing oxygen gas. When the active material layer containing an active material that can be altered by oxidation is heated under the same conditions, the performance of the active material tends to deteriorate. Further, as a method for recycling the recovered electrode other than direct recycling, there is a method of recovering a raw material compound containing a metal element in the active material from the recovered electrode by extraction with a solution or the like. However, since the recovered active material is decomposed into a raw material compound containing constituent elements, further steps are required for reuse as an active material. On the other hand, the method for manufacturing a non-aqueous electrolyte storage element described in the above (1) includes heating the recovered electrode at 400°C or higher in an atmosphere of an inert gas or a reducing gas. Thereby, since the binder contained in the active material layer in the recovered electrode can be sufficiently thermally decomposed, the base material and the active material layer can be easily separated. The active material in the separated active material layer can be reused as it is. Further, since the recovered electrode is heated in an atmosphere of an inert gas or a reducing gas, oxidation of the active material, which is a simple substance in the active material layer or a compound in which a metal element and an oxygen element are not directly bonded, can be suppressed. That is, the method for manufacturing a non-aqueous electrolyte storage element described in the above (1) can easily reuse the active material contained in the recovered electrode while suppressing a decrease in performance.

[0013] 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, and in addition to the electrode taken out from the non-aqueous electrolyte storage element recovered after use, even before use, an electrode taken out from the non-aqueous electrolyte storage element recovered due to initial defects or the like, an electrode taken out from the non-aqueous electrolyte storage element recovered as an unused product after shipment, an electrode recovered as a defective product during manufacturing, etc. are also included. The "inert gas" means a gas that does not substantially react with the active material. The "reducing gas" means a gas that can cause a reduction reaction in the active material. "Heating at 400°C or higher" means that the heating temperature is 400°C or higher. The "heating temperature" is defined as the maximum temperature reached on the surface of the recovery 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.

[0014] (2) In the method for manufacturing a non-aqueous electrolyte storage element described in (1) above, the active material may be a lithium transition metal compound having a polyanion structure. By having the active material be a lithium transition metal compound having a polyanion structure in this way, the effect of suppressing a decrease in the performance of the active material can be fully enjoyed.

[0015] (3) In the method for manufacturing a non-aqueous electrolyte storage element described in (1) or (2) above, the active material layer may further contain a conductive assistant, and may include recovering the conductive assistant together with the active material.

[0016] According to the method for manufacturing a non-aqueous electrolyte storage element described in (3) above, in an atmosphere of an inert gas or a reducing gas, the decomposition of the conductive assistant due to oxidation or combustion is suppressed, so that it can be easily recovered together with the active material. Further, by including recovering the conductive assistant together with the active material, the recycling rate of the materials constituting the active material layer of the electrode can be increased.

[0017] Hereinafter, the method for manufacturing a non-aqueous electrolyte storage element according to an embodiment of the present invention and other embodiments will be described in detail. Note that the names of the respective constituent members (each constituent element) used in each embodiment may be different from the names of the respective constituent members (each constituent element) used in the background art.

[0018] <Method for Manufacturing a Non-Aqueous Electrolyte Storage Element> A method for manufacturing a non-aqueous electrolyte storage element according to an aspect of the present invention includes preparing a recovery electrode for a non-aqueous electrolyte having a base material and an active material layer laminated on the base material and containing an active material and a binder (hereinafter, also referred to as "preparation of electrode S1"), heating the recovery electrode at a temperature of 400°C or higher in an atmosphere of an inert gas or a reducing gas (hereinafter, also referred to as "heating of electrode S2"), and separating the active material layer from the base material to recover the active material contained in the active material layer (hereinafter, also referred to as "recovery of active material S3"). The active material is a single substance or a compound in which a metal element and an oxygen element are not directly bonded. Further, the active material layer of the recovery electrode may further have a conductive assistant. When the active material layer of the recovery electrode further has a conductive assistant, in addition to the active material, the conductive assistant may be recovered in the recovery of active material S3, and both the recovered active material and the conductive assistant may be reused for manufacturing a new non-aqueous electrolyte storage element.

[0019] As an optional step, the manufacturing method may include manufacturing a new electrode using the recovered active material (hereinafter, also referred to as "manufacturing of electrode S4") and assembling a new non-aqueous electrolyte storage element including the manufactured electrode (hereinafter, also referred to as "assembly S5").

[0020] The manufacturing method does not newly synthesize an active material using the active material contained in the recovery electrode as a raw material. That is, the manufacturing method directly recycles the active material.

[0021] 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, there are those taken out from a non-aqueous electrolyte storage element recovered after use, those recovered due to initial defects 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. 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 preferably contains a conductive auxiliary agent in addition to the active material and the binder, and may further contain optional components such as a filler and a thickener. 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.

[0022] In one embodiment of the present invention, the recovered electrode to be reused may be a positive electrode. From the viewpoint of sufficiently enjoying the effect of suppressing the deterioration of the performance of the active material, the active material of the positive electrode to be reused is preferably a lithium transition metal compound having a polyanion structure. Also, from the same viewpoint, the active material of the positive electrode to be reused is preferably an organic sulfur compound and elemental sulfur. The binder in the positive electrode to be reused is preferably a fluororesin from the viewpoints of facilitating decomposition by heating, adhesive strength, electrochemical stability, etc., and polyvinylidene fluoride (PVDF) is more preferable. When the positive electrode contains a conductive auxiliary agent, the conductive auxiliary agent in the positive electrode to be reused is preferably a carbonaceous material from the viewpoints of achieving both stability against heating and conductivity, and carbon black is more preferable, and acetylene black is even more preferable. The specific form of the positive electrode to be reused in the manufacturing method will be described in detail later.

[0023] In one embodiment of the present invention, the recovered electrode to be reused may be a negative electrode. From the viewpoint of sufficiently enjoying the effect of suppressing the deterioration of the performance of the active material, the active material of the negative electrode to be reused is preferably a carbon material, more preferably graphite and non-graphite carbon. The binder and the conductive assistant in the negative electrode to be reused can be the same as the binder and the conductive assistant in the positive electrode described above. The specific form of the negative electrode to be reused in the manufacturing method will be described in detail later.

[0024] Hereinafter, each step of the method for manufacturing a non-aqueous electrolyte storage element according to one embodiment of the present invention will be described with reference to FIG. 1. Note that FIG. 1 shows the process order as an example in the manufacturing method as a flow chart. The manufacturing method is not limited to the process order of FIG. 1. Also, as described above, the steps other than the electrode preparation S1, the electrode heating S2, and the active material recovery S3 are optional steps.

[0025] (Electrode preparation S1) 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 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 recovered electrode can be taken out from the recovered non-aqueous electrolyte storage element 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 electrode and the negative electrode is used as the recovered electrode in the manufacturing method of the non-aqueous electrolyte storage element of the present embodiment, the other electrode may be reused by another method different from the manufacturing method of the non-aqueous electrolyte storage element of the present embodiment, or other treatments other than reuse may be performed.

[0026] In this process, the recovered electrode may be prepared by recovering the electrode before it is incorporated into the non-aqueous electrolyte storage element, that is, the electrode recovered as a defective product during manufacturing or the like. In this case, the recovered electrode is prepared without taking out the electrode from the recovered non-aqueous electrolyte storage element.

[0027] (Electrode heating S2) In this process, the recovered electrode is heated at a temperature of 400°C or higher in an atmosphere of an inert gas or a reducing gas. By heating the recovered electrode in this way, the binder contained in the active material layer is thermally decomposed, so that in the "recovery of active material S3" described later, the base material and the active material layer can be easily separated. The heating of the recovered electrode can be performed with a conventionally known heat treatment apparatus or the like. When starting the heating of the recovered electrode, the active material layer may be laminated on the base material, or the active material layer may be separated from the base material. Further, as a result of heating the recovered electrode, the active material layer may be at least partially separated from the base material, or the active material layer may remain laminated on the base material.

[0028] As described above, the recovered electrode is heated in an atmosphere of an inert gas or a reducing gas. By heating the recovered electrode in an atmosphere of an inert gas or a reducing gas in this way, the oxidation of the active material, which is a simple substance in the active material layer or a compound in which a metal element and an oxygen element are not directly bonded, can be suppressed. Further, in an atmosphere of an inert gas or a reducing gas, when the active material layer contains a conductive assistant, the decomposition of the conductive assistant due to oxidation or combustion can also be suppressed. Examples of the inert gas include gases of noble gas elements such as helium gas, neon gas, and argon gas, nitrogen gas, carbon dioxide gas, etc. Among them, nitrogen gas, which is inexpensive and has high safety, is preferable. Examples of the reducing gas include hydrogen gas, carbon monoxide gas, hydrocarbon gas, ammonia gas, etc. In this process, the inert gas and the reducing gas may be used alone or in combination of two or more.

[0029] The lower limit of the heating temperature of the recovery electrode is 400°C, preferably 420°C, more preferably 440°C, still more preferably 460°C, and even more preferably 480°C in some cases. When the heating temperature of the recovery electrode is equal to or higher than the above lower limit, the binder contained in the active material layer can be easily thermally decomposed in an atmosphere of an inert gas or a reducing gas. As a result, in "recovery S3 of the active material" described later, the substrate and the active material layer can be easily separated. On the other hand, as the upper limit of the heating temperature of the recovery electrode, 800°C is preferable, 760°C is more preferable, 720°C is still more preferable, 680°C is even more preferable, and 640°C is particularly preferable. When the heating temperature of the recovery electrode is equal to or lower than the above upper limit, the energy consumption associated with heating can be suppressed. Further, when a conductive assistant is contained in the active material layer, decomposition of the conductive assistant due to heating can be suppressed. As a result, the conductive assistant can be recovered together with the active material in subsequent steps.

[0030] The heating temperature of the recovery electrode can be appropriately adjusted based on the thermal decomposition temperature of the binder in a temperature range of 400°C or higher. In one embodiment of the present invention, the heating temperature of the recovery electrode may be higher than the thermal decomposition temperature of the binder. For example, since the thermal decomposition temperature of PVDF is about 400°C in an air atmosphere, when the binder contained in the active material layer is PVDF, the heating temperature of the recovery electrode in an atmosphere of an inert gas or a reducing gas may be higher than 400°C. Note that since 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 at 400°C or higher, the heating temperature of the recovery electrode does not necessarily have to be higher than the thermal decomposition temperature of the binder in an atmosphere of an inert gas or a reducing gas. The "thermal decomposition temperature of the binder" means the temperature obtained by the following procedure. First, the solid content of the binder is used as a measurement sample and subjected to thermogravimetric measurement (TG) in a predetermined atmosphere. 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 binder.

[0031] The heat preservation time of the recovery electrode is not particularly limited, but is preferably 5 minutes or more and 100 minutes or less, more preferably 10 minutes or more and 80 minutes or less, still more preferably 15 minutes or more and 60 minutes or less, and even more preferably 20 minutes or more and 40 minutes or less. By having the heat preservation time of the recovery electrode within the above range, the recovery electrode can be sufficiently heated while suppressing the energy consumption due to heating. Here, the "heat preservation time" means the time for maintaining the above-described heating temperature. The heat preservation time may be a continuous heat preservation time or the total time when heating intermittently.

[0032] (Recovery S3 of the active material) In this step, the active material contained in the active material layer is recovered. Further, 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. For example, the active material contained in the active material layer may be recovered after separating the substrate and the active material layer, or the active material 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 contained in the positive electrode active material layer and the negative electrode active material contained in the negative electrode active material layer are recovered separately.

[0033] Examples of the method for recovering the active material in this step include directly scraping off the active material layer from the substrate for recovery. In this case, the recovered active material layer (active material) may be pulverized by being subjected to a pulverizer such as a ball mill from the viewpoint of handleability in subsequent steps. Further, the active material layer may be separated from the substrate by pulverizing the recovery electrode by using a pulverizer to pulverize the active material layer. In this case, the powder material of the active material layer containing the active material may be recovered by using various sieves such as a vibrating sieve.

[0034] In this process, it is possible to recover only the active material contained in the active material layer. However, when the conductive aid is included in the active material layer, it is preferable to recover the conductive aid together. It is also preferable to recover any other optional components other than the conductive aid. For example, the powder material of the active material layer described above may be recovered in a state where optional components other than the active material are also mixed. By recovering the active material and the optional components together in this way, it is not necessary to separate only the active material, and the efficiency of recovering the active material can be increased.

[0035] (Fabrication of Electrode S4) In this process, a new electrode is fabricated using the recovered active material. The new electrode can be fabricated by known methods such as mixing the recovered active material with 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 to the recovered active material.

[0036] (Assembly S5) In this process, a new non-aqueous electrolyte storage element equipped with the new electrode fabricated in the electrode fabrication S4 using the recovered active material is assembled. This process can be carried out in the same manner as a conventional known non-aqueous electrolyte storage element, except that an electrode fabricated in the electrode fabrication S4 using the recovered active material is used as at least one of the positive electrode and the negative electrode. For example, in the assembly S5, an electrode body is fabricated using the new electrode fabricated in the electrode fabrication S4, and the electrode body and the non-aqueous electrolyte are housed in a container. When a non-aqueous electrolyte solution is used as the non-aqueous electrolyte, a new non-aqueous electrolyte storage element can be obtained by injecting the non-aqueous electrolyte solution through an injection port formed in the container and then sealing the injection port.

[0037] In this process, for example, when a positive electrode is used as the recovered electrode, a positive electrode fabricated as a new electrode using the recovered positive electrode active material can be combined with a separately prepared negative electrode to fabricate an electrode body. Also, when a negative electrode is used as the recovered electrode, a negative electrode fabricated as a new electrode using the recovered negative electrode active material and a conductive assistant can be combined with a separately prepared positive electrode to fabricate an electrode body. When both a positive electrode and a negative electrode are used as the recovered electrodes, an electrode body may be fabricated by combining a positive electrode fabricated as a new electrode using the recovered positive electrode active material and a negative electrode fabricated as a new electrode using the recovered negative electrode active material. An electrode body may also be fabricated by separately fabricating new electrodes using both a positive electrode and a negative electrode as the recovered electrodes and combining each with a separately prepared electrode. The separately prepared electrode may be an electrode recycled by a method different from the method for manufacturing a non-aqueous electrolyte storage element according to an embodiment of the present invention.

[0038] The electrode body fabricated in this process may be a wound-type electrode body, a laminated-type electrode body, or an electrode body of other shapes. The fabrication of the electrode body can be performed by a conventionally known method except for using a recovered electrode for at least one of the positive electrode and the negative electrode. For example, an electrode body can be fabricated by laminating or winding a positive electrode and a negative electrode with a separator therebetween.

[0039] (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 processes. For example, in the manufacturing method, cleaning, drying, etc. of the recovered electrode may be performed. Cleaning, 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.

[0040] According to the method for manufacturing a non-aqueous electrolyte storage element according to an embodiment of the present invention, an active material that can be deteriorated by oxidation contained in the recovered electrode can be easily reused, and a decrease in the performance of the active material can be suppressed. 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 reused, 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.

[0041] (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 that houses 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.

[0042] (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.

[0043] 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 with Ω·cm as the threshold value. As the material of the positive electrode substrate, metals such as aluminum, titanium, tantalum, and 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, an aluminum foil or an 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).

[0044] 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.

[0045] 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. For example, it contains a binder and a conductive auxiliary agent.

[0046] The positive electrode active material layer contains a positive electrode active material. In one embodiment of the present invention, when the recovered electrode to be reused is a positive electrode, the positive electrode active material layer further contains a binder, and the positive electrode active material layer of the positive electrode included in the new non-aqueous electrolyte storage element contains a binder as required. The positive electrode active material layer may further contain optional components such as a conductive auxiliary agent, a thickener, and a filler as required. The positive electrode active material layer may have one or more positive electrode active materials.

[0047] In one embodiment of the present invention, when the recovery electrode is a positive electrode, the positive electrode active material layer of the positive electrode has a single substance or a positive electrode active material that is a compound in which a metal element and an oxygen element are not directly bonded. Examples of the above compound include a compound containing a metal element and an oxygen element and in which the metal element and the oxygen element are not directly bonded (hereinafter also referred to as "first compound"), a compound containing a metal element and not containing an oxygen element (hereinafter also referred to as "second compound"), and a compound not containing both a metal element and an oxygen element (hereinafter also referred to as "third compound").

[0048] Typical examples of the first compound used as the positive electrode active material include lithium transition metal compounds having a polyanion structure.

[0049] Lithium transition metal compounds having a polyanion structure are usually used in the form of granular materials coated with a carbon material from the viewpoint of electron conductivity and the like. That is, in one embodiment of the present invention, the positive electrode active material may be a granular material in which particles containing a lithium transition metal compound having a polyanion structure are coated with a carbon material.

[0050] Examples of the lithium transition metal compound having a polyanion structure include compounds containing an oxoacid anion (PO4 3- 、SO4 2- 、SiO4 4- 、BO3 3- 、VO4 3- etc.) and lithium ions and transition metal ions. The oxoacid anion is a condensed anion (P2O7 4- 、P3O 10 5-It may also be (etc.). The lithium transition metal compound having a polyanion structure may have an olivine-type crystal structure. The lithium transition metal compound having a polyanion structure is typically a polyanion compound containing a lithium element and a transition metal element, and may further contain other elements (such as halogen elements, etc.). As the transition metal element contained in the lithium transition metal compound having a polyanion structure, an iron element, a manganese element, a nickel element, and a cobalt element are preferable, and an iron element is more preferable. As the oxoacid anion contained in the lithium transition metal compound having a polyanion structure, a phosphate anion (PO4 3- ) is preferable.

[0051] The lithium transition metal compound having a polyanion structure is preferably a compound represented by the following formula (1). Li a M b (AO c ) d X e ···(1) In formula (1), M is at least one kind of transition metal element. A is at least one kind selected from B, Al, Si, P, S, Cl, Ti, V, Cr, Mo, and W. X is at least one kind of halogen element. a, b, c, d, and e are numbers satisfying 0 < a ≤ 3, 0 < b ≤ 2, 2 ≤ c ≤ 4, 1 ≤ d ≤ 3, and 0 ≤ e ≤ 1. a, b, c, d, and e may all be integers or may be decimals.

[0052] As M in formula (1), any one of Fe, Mn, Ni, and Co, or a combination of any two of these is preferable. As M, Fe, Mn, or a combination of these is more preferable, and Fe is even more preferable. Also, the content of Fe in M is preferably 50 mol% or more, more preferably 70 mol% or more, 90 mol% or more, or 99 mol% or more. As A, P is preferable. As X, F is preferable. In one embodiment, a = 1, b = 1, c = 4, d = 1, and e = 0 may be preferable in some cases.

[0053] Specific examples of the lithium transition metal compound having a polyanion structure include, for example, LiFePO4, LiCoPO4, LiFe 0.5 Co 0.5 PO4, LiMnPO4, LiNiPO4, LiMn 0.5 Fe 0.5 PO4, LiCrPO4, LiFeVO4, Li2FeSiO4, Li2Fe2(SO4)3, LiFeBO3, LiFePO 3.9 F 0.2 , Li3V2(PO4)3, Li2MnSiO4, Li2CoPO4F, and the like. Atoms or polyanions in these lithium transition metal compounds having a polyanion structure may be partially substituted with other atoms or anion species. The lithium transition metal compound having a polyanion structure may be used alone or in combination of two or more.

[0054] Examples of the second compound used as the positive electrode active material include chalcogen compounds such as titanium disulfide, molybdenum disulfide, and molybdenum dioxide. These compounds may be used alone or in combination of two or more.

[0055] Examples of the third compound used as the positive electrode active material include organic sulfur compounds such as organic disulfide compounds and carbon sulfide compounds. These compounds may be used alone or in combination of two or more.

[0056] Typical examples of the simple substance used as the positive electrode active material include sulfur simple substance.

[0057] The sulfur simple substance may be contained in a composite of porous carbon and sulfur. Examples of the composite of porous carbon and sulfur include a form in which porous carbon and sulfur simple substance are contained in one particle. The composite may be in a form in which at least a part of the sulfur simple substance is disposed in the pores of the porous carbon. In other words, it may be in a form in which at least a part of the sulfur simple substance is impregnated in the porous carbon.

[0058] Porous carbon is a porous material mainly composed of carbon elements. The main constituent element refers to the element with the highest content based on mass. The content of carbon elements in porous carbon is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. Porous carbon may consist essentially of only carbon elements. Porous carbon may further contain other elements such as oxygen elements in addition to carbon elements.

[0059] The content of porous carbon in the composite (mass ratio of porous carbon to the total mass of the composite) is preferably 10% by mass or more and 50% by mass or less, more preferably 20% by mass or more and 45% by mass or less, and even more preferably 30% by mass or more and 40% by mass or less. By setting the content of porous carbon in the composite within the above range, the discharge capacity of the non-aqueous electrolyte energy storage device can be increased, etc.

[0060] The content of elemental sulfur in the composite (mass ratio of elemental sulfur to the total mass of the composite) is preferably 50% by mass or more and 90% by mass or less, more preferably 55% by mass or more and 80% by mass or less, and even more preferably 60% by mass or more and 70% by mass or less. By setting the content of elemental sulfur in the composite within the above range, the discharge capacity of the non-aqueous electrolyte energy storage device can be increased, etc.

[0061] The content of the composite in the positive electrode active material layer is preferably 60% by mass or more and 95% by mass or less, more preferably 70% by mass or more and 90% by mass or less. By setting the content of the composite within the above range, the discharge capacity of the non-aqueous electrolyte energy storage device can be increased, and the energy density can be enhanced, etc.

[0062] The positive electrode active material layer may contain other positive electrode active materials other than the above-described simple substance, first compound, second compound, and third compound. Examples of other positive electrode active materials include lithium transition metal composite oxides having an α-NaFeO2-type crystal structure and lithium transition metal composite oxides having a spinel-type crystal structure. However, when the recovered electrode to be reused is a positive electrode, from the viewpoint of sufficiently enjoying the effect of suppressing the deterioration of the performance of the active material, the content of the above other positive electrode active material in all the positive electrode active materials in the positive electrode active material layer is preferably 20% by mass or less, more preferably 10% by mass or less, still more preferably 5% by mass or less, and even more preferably 1% by mass or less.

[0063] 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 a composite of the positive electrode active material and other materials is used, the average particle size of the composite is defined as the average particle size of the positive electrode active material. The "average particle size" conforms to JIS-Z-8825 (2013), and is 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 diluted solution in which particles are diluted with a solvent is 50%.

[0064] To obtain powder with a predetermined particle size, a pulverizer, a classifier, or the like is 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, or the like is used as needed for both dry and wet processes.

[0065] The content of the total 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 still more preferably 80% by mass or more and 95% by mass or less. By setting the content of the total positive electrode active material within the above range, it is possible to achieve both high energy density and manufacturability of the positive electrode active material layer.

[0066] The conductive assistant is not particularly limited as long as it is a material having conductivity. Examples of such conductive assistants 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 preferred as the conductive assistant, carbon black is more preferred, and acetylene black is still more preferred. Examples of the shape of the conductive assistant include powder form, fibrous form, etc. As the conductive assistant, 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 obtained by compositeizing carbon black and CNT may be used.

[0067] The content of the conductive assistant 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 assistant within the above range, the energy density of the non-aqueous electrolyte storage element can be increased.

[0068] Examples of the binder include thermoplastic resins such as fluororesins (polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), etc.), polyethylene, polypropylene, polyacrylic, and polyimide; elastomers such as ethylene-propylene-diene rubber (EPDM), sulfonated EPDM, styrene-butadiene rubber (SBR), and fluororubber; and polysaccharide polymers. From the viewpoints of facilitating decomposition by heating, adhesive strength, electrochemical stability, etc., fluororesins are preferred as the binder, and polyvinylidene fluoride (PVDF) is more preferred.

[0069] 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, and 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.

[0070] 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, and more preferably 1% by mass or less. The positive electrode active material layer may not contain a thickener.

[0071] 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 substances derived from mineral resources 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.

[0072] 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.

[0073] (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 can be selected, for example, from the configurations exemplified for the positive electrode above.

[0074] 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 preferred. Examples of the negative electrode substrate include foil, vapor deposition film, mesh, porous material, etc., and foil is preferred from the viewpoint of cost. Therefore, as the negative electrode substrate, copper foil or copper alloy foil is preferred. Examples of copper foil include rolled copper foil, electrolytic copper foil, etc.

[0075] 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 unit volume of the non-aqueous electrolyte storage element.

[0076] 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 binder, and the negative electrode active material layer of the negative electrode included in the new non-aqueous electrolyte storage element contains a binder as required. The negative electrode active material layer may further contain optional components such as a conductive assistant, a thickener, a filler, etc. as required. The conductive assistant, binder, thickener, filler, etc. can be selected from the materials exemplified for the above positive electrode. The negative electrode active material layer may have one or more negative electrode active materials.

[0077] The negative electrode active material layer may contain 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. as components other than the negative electrode active material, conductive assistant, binder, thickener, filler.

[0078] In one embodiment of the present invention, when the recovered electrode to be reused is a negative electrode, the negative electrode active material layer of the negative electrode has a negative electrode active material that is a single substance or a compound (first compound, second compound, or third compound) in which a metal element and an oxygen element are not directly bonded. Examples of such negative electrode active materials include metals or semi-metals such as Si and Sn; and single substances such as carbon materials like graphite (graphite), non-graphitic carbon (easily graphitizable carbon or hardly graphitizable carbon). Among these, from the perspective of sufficiently enjoying the effect of suppressing the degradation of the performance of the active material, carbon materials are preferred, and graphite and non-graphitic carbon are more preferred.

[0079] "Graphite" refers to a carbon material having an average lattice plane spacing (d 002 ) of 0.33 nm or more and less than 0.34 nm as determined by X-ray diffraction before charge-discharge or in a discharged state. Examples of graphite include natural graphite and artificial graphite. Artificial graphite is preferred from the perspective of obtaining a material with stable physical properties.

[0080] "Non-graphitic carbon" refers to a carbon material having an average lattice plane spacing (d 002 ) of 0.34 nm or more and 0.42 nm or less as determined by X-ray diffraction before charge-discharge or in a discharged state. Examples of non-graphitic carbon include hardly graphitizable carbon and easily graphitizable carbon. Examples of non-graphitic carbon include, for example, resin-derived materials, petroleum pitch or petroleum pitch-derived materials, petroleum coke or petroleum coke-derived materials, plant-derived materials, alcohol-derived materials, and the like.

[0081] Here, the "discharged state" of the carbon material means a state in which lithium ions that can be occluded and released during charge-discharge are sufficiently released from the carbon material that is 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.

[0082] "Hardly graphitizable carbon" refers to a carbon material having the above d 002 of 0.36 nm or more and 0.42 nm or less.

[0083] "Easily graphitizable carbon" refers to a carbon material where d 002 is from 0.34 nm or more to less than 0.36 nm.

[0084] The negative electrode active material is usually in the form of particles (powder). The average particle size 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 size may be 1 μm or more and 100 μm or less. When the negative electrode active material is Si, Sn, an Si oxide, an Sn oxide, etc., its average particle size may be 1 nm or more and 1 μm or less. By setting the average particle size 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 easier. By setting the average particle size 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. To obtain a powder with a predetermined particle size, a pulverizer, a classifier, etc. are used.

[0085] Among all the negative electrode active materials in the negative electrode active material layer, the content of the carbon material 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 negative electrode active material layer substantially has only a carbon material as the negative electrode active material.

[0086] The negative electrode active material layer may contain other negative electrode active materials other than simple substances and compounds in which a metal element and an oxygen element are not directly bonded. Examples of other negative electrode active materials include metal oxides or semi-metal oxides such as Si oxides, Ti oxides, and Sn oxides; Li4Ti5O 12 , LiTiO 2、 , titanium-containing oxides such as TiNb2O7, etc. However, when the recovered electrode to be reused is a negative electrode, from the viewpoint of sufficiently enjoying the effect of suppressing the deterioration of the performance of the active material, among all the negative electrode active materials in the negative electrode active material layer, the content of the above other negative electrode active materials is preferably 20% by mass or less, more preferably 10% by mass or less, still more preferably 5% by mass or less, and even more preferably 1% by mass or less.

[0087] The content of the total 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 total negative electrode active material within the above range, it is possible to achieve both high energy density and manufacturability of the negative electrode active material layer.

[0088] (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 in which a heat-resistant layer containing heat-resistant particles and a binder is 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 and aramids 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.

[0089] The heat-resistant particles contained in the heat-resistant layer preferably have a mass reduction 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 reduction of 5% or less when heated from room temperature to 800 °C. Examples of materials with a mass reduction of 5% or less include inorganic compounds. 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; and substances derived from mineral resources such as talc, montmorillonite, boehmite, zeolite, apatite, kaolin, mullite, spinel, olivine, sericite, bentonite, and mica, or artificial products thereof. As the inorganic compound, these substances may be used alone or in combination, or two or more of them may be mixed and used. Among these inorganic compounds, from the viewpoint of the safety of non-aqueous electrolyte energy storage elements, silicon oxide, aluminum oxide, or aluminosilicate is preferred.

[0090] From the viewpoint of strength, the porosity of the separator is preferably 80% by volume or less, and from the viewpoint of discharge performance, it is preferably 20% by volume or more. Here, the "porosity" is a value based on volume and means the measured value by a mercury porosimeter.

[0091] 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, and polyvinylidene fluoride. Using a polymer gel has the effect of suppressing leakage of the liquid. As the separator, the above-mentioned porous resin film or non-woven fabric, etc. may be used in combination with a polymer gel.

[0092] (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 this non-aqueous solvent.

[0093] 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, etc. As the non-aqueous solvent, those in which some of the hydrogen atoms contained in these compounds are substituted with halogens may be used.

[0094] 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, etc. Among these, EC is preferred.

[0095] Examples of the chain carbonate include diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diphenyl carbonate, trifluoroethyl methyl carbonate, bis(trifluoroethyl) carbonate, etc. Among these, EMC is preferred.

[0096] 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.

[0097] As the electrolyte salt, it can be appropriately selected from known electrolyte salts. Examples of the electrolyte salt include lithium salts, sodium salts, potassium salts, magnesium salts, onium salts, etc. Among these, lithium salts are preferable.

[0098] Examples of the lithium salt include inorganic lithium salts such as LiPF6, LiPO2F2, LiBF4, LiClO4, LiN(SO2F)2, lithium oxalate salts such as lithium bis(oxalato)borate (LiBOB), lithium difluorooxalate borate (LiFOB), lithium bis(oxalato)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, etc. Among these, inorganic lithium salts are preferable, and LiPF6 is more preferable.

[0099] The content of the electrolyte salt in the non-aqueous electrolyte is preferably 0.1 mol / dm 3 or more and 2.5 mol / dm 3 or less at 20°C and 1 atm, more preferably 0.3 mol / dm 3 or more and 2.0 mol / dm 3 or less, still more preferably 0.5 mol / dm 3 or more and 1.7 mol / dm 3 or less, and most preferably 0.7 mol / dm 31.5 mol / dm or less is particularly preferred. By setting the content of the electrolyte salt within the above range, the ionic conductivity of the non-aqueous electrolyte can be increased. 3 It is particularly preferable that it is as follows. By setting the content of the electrolyte salt within the above range, the ionic conductivity of the non-aqueous electrolyte can be increased.

[0100] In addition to the non-aqueous solvent and the electrolyte salt, the non-aqueous electrolyte may contain additives. Examples of the additives 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 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 kinds.

[0101] 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 with respect to 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.

[0102] A solid electrolyte may be used for the non-aqueous electrolyte, or a non-aqueous electrolyte and a solid electrolyte may be used in combination.

[0103] The shape of the non-aqueous electrolyte storage element is not particularly limited, and examples thereof include a cylindrical battery, a prismatic battery, a flat battery, a coin-type battery, and a button-type battery.

[0104] FIG. 2 shows a non-aqueous electrolyte storage element 1 as an example of a prismatic 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 prismatic container 3. The positive electrode is electrically connected to a positive electrode terminal 4 via a positive electrode lead 41. The negative electrode is electrically connected to a negative electrode terminal 5 via a negative electrode lead 51.

[0105] (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.

[0106] 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.

[0107] <Other Embodiments> Note that the method for manufacturing the non-aqueous electrolyte power storage element of the present invention is not limited to the above-described embodiments, and various modifications may be made without departing from the gist of the present invention. For example, the configuration of another embodiment may be added to the configuration of a certain embodiment, and a part of the configuration of a certain embodiment may be replaced with the configuration of another embodiment or a well-known technique. Further, a part of the configuration of a certain embodiment may be deleted. In addition, a well-known technique may be added to the configuration of a certain embodiment.

[0108] In the above-described embodiments, the case where the non-aqueous electrolyte power storage element is used as a non-aqueous electrolyte secondary battery (for example, a lithium ion secondary battery) capable of charge and discharge has been described. However, the type, shape, dimensions, capacity, etc. of the non-aqueous electrolyte power 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.

[0109] In the above-described embodiments, 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 layer having no conductivity is formed on the active material layer of the positive electrode or the negative electrode.

Industrial Applicability

[0110] The present invention is useful as a technique for recycling electrodes for non-aqueous electrolyte power storage elements.

Explanation of Reference Numerals

[0111] 1 Non-aqueous electrolyte energy storage element 2 Electrode body 3 Container 4 Positive electrode terminal 41 Positive electrode lead 5 Negative electrode terminal 51 Negative electrode lead 20 Energy storage unit 30 Energy 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 and a binder; Heating the recovered electrode at a temperature of 400°C or higher in an atmosphere of an inert gas or a reducing gas; and Separating the active material layer from the base material and recovering the active material contained in the active material layer comprising: A method for manufacturing a non-aqueous electrolyte storage element, wherein the active material is a single substance or a compound in which a metal element and an oxygen element are not directly bonded.

2. The method for manufacturing a non-aqueous electrolyte storage element according to Claim 1, wherein the active material is a lithium transition metal compound having a polyanion structure.

3. The active material layer further contains a conductive assistant, The method for manufacturing a non-aqueous electrolyte storage element according to Claim 1 or Claim 2, comprising recovering the conductive assistant together with the active material.

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