WO2025100403A1 - Method for producing recycled active material and method for producing nonaqueous electrolyte power storage element - Google Patents

Abstract

A method for producing a recycled active material according to one aspect of the present invention includes: extracting an active material that contains secondary particles from an electrode which has the active material or from a nonaqueous electrolyte power storage element which is provided with the electrode; and pulverizing the extracted active material. A recycled active material is obtained by means of the pulverization.

Description

Manufacturing method for regenerative material and manufacturing method for non-aqueous electrolyte storage element

The present invention relates to a method for producing a regenerative substance and a method for producing a non-aqueous electrolyte storage element.

Non-aqueous electrolyte secondary batteries, such as lithium-ion secondary batteries, are widely used in electronic devices such as personal computers and communication terminals, as well as automobiles, due to their high energy density. Non-aqueous electrolyte secondary batteries generally have a pair of electrodes electrically isolated by a separator and a non-aqueous electrolyte interposed between the electrodes, and are configured to charge and discharge by transferring charge-transporting ions between the two electrodes. In addition to non-aqueous electrolyte secondary batteries, capacitors such as lithium-ion capacitors and electric double-layer capacitors are also widely used as non-aqueous electrolyte storage elements.

As the market for non-aqueous electrolyte storage elements expands, efforts are underway to develop methods for recycling used non-aqueous electrolyte storage elements. One method under consideration for recycling non-aqueous electrolyte storage elements is a method known as direct recycling, in which active material is extracted from the electrodes of the non-aqueous electrolyte storage element and reused as active material without dissolving the extracted active material or decomposing it into raw material compounds containing the constituent elements (see Patent Document 1).

Japanese Patent Application Publication No. 2014-207192

Direct recycling of active materials is considered to be a more efficient method of recycling at lower cost than the method of synthesizing new active materials using active materials extracted from electrodes as raw materials. However, in the case of nonaqueous electrolyte storage elements having electrodes in which active materials that are secondary particles are used, cracks tend to progress due to repeated expansion and contraction of the active materials as they are used, such as during charging and discharging. The degree of cracking of each secondary particle varies greatly depending on the state of use of the nonaqueous electrolyte storage element and its position in the electrode. For this reason, the degree of cracking of active materials extracted from electrodes, etc. in nonaqueous electrolyte storage elements after use varies greatly. Since the degree of cracking affects the performance of the active material, active materials with a large degree of cracking variation will have a large variation in quality, which may lead to variation in the quality of the electrodes and nonaqueous electrolyte storage elements manufactured using them.

The object of the present invention is to provide a method for producing a recycled material that can obtain recycled materials with little variation in quality by reusing electrodes or nonaqueous electrolyte storage elements that use active materials containing secondary particles, and a method for producing nonaqueous electrolyte storage elements that can obtain nonaqueous electrolyte storage elements with little variation in quality.

A method for producing a regenerative material according to one aspect of the present invention comprises extracting the active material from an electrode having an active material containing secondary particles or from a nonaqueous electrolyte storage element including the electrode, and pulverizing the extracted active material, and obtaining the regenerative material by the pulverization.

　A method for manufacturing a nonaqueous electrolyte storage element according to another aspect of the present invention includes producing an electrode having a regenerative material obtained by the method for manufacturing a regenerative material according to one aspect of the present invention.

According to one aspect of the present invention, it is possible to provide a method for producing a recycled material that can obtain recycled materials with little variation in quality by reusing electrodes or nonaqueous electrolyte storage elements that use active materials containing secondary particles, and a method for producing nonaqueous electrolyte storage elements that can obtain nonaqueous electrolyte storage elements with little variation in quality.

FIG. 1 is a flow diagram showing one embodiment of a method for producing a regenerative material. FIG. 2 is a perspective view showing one embodiment of a nonaqueous electrolyte electricity storage element. FIG. 3 is a schematic diagram showing one embodiment of an electricity storage device formed by assembling a plurality of nonaqueous electrolyte electricity storage elements.

First, we will provide an overview of the method for producing a regenerative substance and the method for producing a nonaqueous electrolyte storage element disclosed in this specification.

(1) A method for producing a regenerative material according to one aspect of the present invention comprises extracting the active material from an electrode having an active material containing secondary particles or from a nonaqueous electrolyte storage element including the electrode, and pulverizing the extracted active material, thereby obtaining a regenerative material by the pulverization.

According to the method for producing a regenerative material described in (1) above, it is possible to obtain a regenerative material with little variation in quality (i.e., non-uniformity) by reusing an electrode or non-aqueous electrolyte storage element in which an active material containing secondary particles is used. The reason for this is unclear, but the following reason is presumed. As described above, the presence of active materials with different degrees of cracking is one of the causes of the variation in quality. Therefore, by removing the active material from the electrode or non-aqueous electrolyte storage element and crushing the removed active material, the secondary particles with few cracks are preferentially crushed, and all the active material is cracked to the same degree. Thus, according to the method for producing a regenerative material described in (1) above, by crushing the removed active material, the variation in the degree of cracking of the active material is reduced, and a regenerative material with little variation in quality can be obtained.

"Secondary particles" refer to particles formed by agglomeration of multiple primary particles. "Primary particles" refer to particles that do not show visible grain boundaries when observed with a scanning electron microscope (SEM).

(2) In the method for producing a regenerative substance described in (1) above, the grinding may include breaking the secondary particles into single particles.

The method for producing a regenerative material described in (2) above converts the active material present as secondary particles into single particles, making it possible to obtain a regenerative material with less variation in quality.

"Single particle" refers to the reduction in the number of primary particles that make up one secondary particle. In other words, "single particle" refers to the separation of one secondary particle composed of multiple primary particles into two or more particles (secondary particles or single particles) and the ratio of the average particle size of each of the two or more separated particles to the average primary particle size becomes smaller than the ratio of the average particle size of one secondary particle before separation to the average primary particle size. "Single particle" refers to a particle consisting of only one primary particle. In other words, single particle does not only refer to becoming a single particle. In addition, in the crushing process, in addition to the secondary particles being crushed into single particles, primary particles may be crushed into finer primary particles, etc.

(3) In the method for producing a regenerative material described in (1) or (2) above, the active material may contain a lithium transition metal composite oxide.

Lithium transition metal complex oxides are generally used as active materials in the form of secondary particles, and are prone to cracking during charging and discharging. For this reason, lithium transition metal complex oxides in the form of secondary particles extracted from electrodes or nonaqueous electrolyte storage elements have particularly large variations in cracking. Therefore, the method for producing a regenerative material described above in (3), which reuses electrodes or nonaqueous electrolyte storage elements in which such lithium transition metal complex oxides are used as active materials, has a particularly significant advantage of the present invention, that is, it is possible to obtain regenerative materials with little variation in quality.

(4) In the method for producing a regenerative substance described in any one of (1) to (3) above, the regenerative substance may be composed of secondary particles having a ratio of the average particle size to the average primary particle size of 3 or less, or primary particles that are substantially not aggregated.

The method for producing the regenerated material described in (4) above allows the obtained regenerated material to be broken with a particularly high degree of uniformity, making it possible to obtain a regenerated material with less variation in quality.

The "average primary particle diameter" of the active material and the regenerative material is the average value of the primary particle diameters of any 50 primary particles constituting the active material or the regenerative material observed under SEM. The primary particle diameter of the primary particles is determined as follows. The shortest diameter passing through the center of the smallest circumscribing circle of the primary particle is defined as the short diameter, and the diameter passing through the center and perpendicular to the short diameter is defined as the long diameter. The average value of the long diameter and the short diameter is defined as the particle diameter. When there are two or more shortest diameters, the longest perpendicular diameter is defined as the short diameter.
The "average particle size" of the active material and the regenerative material is a value (D50: median diameter) at which the volume-based cumulative distribution calculated in accordance with JIS-Z-8819-2 (2001) is 50% based on the particle size distribution measured by a laser diffraction/scattering method for a dilution solution obtained by diluting the active material or the regenerative material with a solvent in accordance with JIS-Z-8815 (2013). It has been confirmed that the average particle size based on the above measurement is almost identical to the average particle size, which is the average value of the particle size (secondary particle size) of each secondary particle measured by extracting 50 particles from the SEM image of the particles while avoiding extremely large particles and extremely small particles. The particle size of each secondary particle based on the measurement from this SEM image is obtained as follows. Based on the SEM image, the shortest diameter passing through the center of the minimum circumscribing circle of each secondary particle is the short diameter, and the diameter passing through the center and perpendicular to the short diameter is the long diameter. The average value of the long diameter and the short diameter is the particle size of each secondary particle. When there are two or more shortest diameters, the longest diameter that intersects at right angles is taken as the shortest diameter.
The term "primary particles that are not substantially aggregated" refers to primary particles in which a plurality of primary particles are present independently without being aggregated when observed with a SEM, or primary particles in which the primary particles are not generally directly bonded to other primary particles.
When the regenerative substance is incorporated into the electrodes of the nonaqueous electrolyte storage element, the average primary particle size and the average particle size of the regenerative substance are values obtained when the nonaqueous electrolyte storage element is charged at a constant current of 0.05 C until the charge end voltage during normal use is reached, and then discharged at a constant current of 0.05 C until the discharge end voltage during normal use is reached after a 30-minute pause. "During normal use" refers to a case where the nonaqueous electrolyte storage element is used under charge and discharge conditions recommended or specified for the nonaqueous electrolyte storage element. For example, when equipment for using the nonaqueous electrolyte storage element is available, the nonaqueous electrolyte storage element may be used by applying the equipment.

(5) In the method for producing a regenerative substance described in any one of (1) to (4) above, the electrode or the nonaqueous electrolyte storage element may be a recycled product.

Generally, when electrodes or nonaqueous electrolyte storage elements are used products that have been repeatedly charged and discharged many times, there tends to be a large variation in the degree of cracking of the active material contained therein, and a large variation in quality resulting from this variation. Therefore, the method for producing a recyclable material described in (5) above, which reuses electrodes or nonaqueous electrolyte storage elements that have been collected as used products, particularly significantly achieves the advantage of the present invention, that a recyclable material with little variation in quality can be obtained.

(6) A method for producing a nonaqueous electrolyte storage element according to another aspect of the present invention includes producing an electrode having a regenerative substance obtained by the method for producing a regenerative substance described in any one of (1) to (5) above.

The manufacturing method for a nonaqueous electrolyte storage element described in (6) above makes it possible to reuse electrodes or nonaqueous electrolyte storage elements that use active materials containing secondary particles, thereby obtaining nonaqueous electrolyte storage elements with little variation in quality.

(7) In the method for producing a nonaqueous electrolyte storage element described in (6) above, preparing the electrode may include mixing the regenerative material with another active material including secondary particles.

The manufacturing method for a nonaqueous electrolyte storage element described in (7) above makes it possible to obtain a nonaqueous electrolyte storage element that can exhibit good performance according to the required performance, etc.

(8) In the method for producing a nonaqueous electrolyte storage element described in (6) above, preparing the electrode may include mixing the regenerative material with another active material having a larger average particle size than the regenerative material.

The manufacturing method for a nonaqueous electrolyte storage element described in (8) above makes it possible to obtain, for example, a nonaqueous electrolyte storage element equipped with high-density electrodes with few voids.

A method for producing a regenerative substance according to one embodiment of the present invention, a method for producing a nonaqueous electrolyte storage element, and other embodiments are described in detail below. Note that the names of the components (elementary components) used in each embodiment may differ from the names of the components (elementary components) used in the background art.

<Method of manufacturing regenerative substances>
The method for producing a re-living material according to one embodiment of the present invention comprises extracting the active material from an electrode having an active material containing secondary particles or a non-aqueous electrolyte storage element including the electrode (hereinafter also referred to as "removal of active material S1"); and pulverizing the extracted active material (hereinafter also referred to as "pulverization of active material S2"). The pulverization produces a re-living material (see FIG. 1). The method for producing a re-living material does not synthesize a new active material using the active material extracted from the electrode or non-aqueous electrolyte storage element as a raw material. That is, the method for producing a re-living material is to reuse the active material extracted from the electrode or non-aqueous electrolyte storage element while maintaining the main crystal structure (for example, without changing the crystal structure significantly or passing through a different compound or element such as a metal), and is to directly recycle the active material. Each step will be described below. The specific form of the non-aqueous electrolyte storage element and electrodes (positive and negative electrodes) to be reused in the method for producing a re-living material will be described in detail later.

(Removal of active material S1)
In this step, an active material containing secondary particles is extracted from the electrode or nonaqueous electrolyte storage element. The electrodes or nonaqueous electrolyte storage elements to be subjected to this step, i.e., to be reused, include those collected as used products, those collected as unused products after shipment, and those collected as defective products during production. In addition, for electrodes such as electrodes collected as defective products during production, those not incorporated in a nonaqueous electrolyte storage element can also be used. Since the advantage of being able to obtain a recyclable material with little variation in quality is particularly noticeable, it is preferable that the electrodes or nonaqueous electrolyte storage elements are collected as used products.

When the nonaqueous electrolyte storage element is to be reused, first, the nonaqueous electrolyte storage element is disassembled by a known method, and the electrodes are taken out. The electrodes taken out may or may not be subjected to treatments such as washing and drying. The electrodes to be reused may be either positive or negative electrodes, so long as they have an active material containing secondary particles. Both the positive and negative electrodes of the nonaqueous electrolyte storage element may be reused. The electrode has, for example, an electrode substrate and an active material layer disposed on the electrode substrate directly or via an intermediate layer. The active material layer usually contains an active material together with optional components such as a binder and a conductive agent. When the electrode is a positive electrode, the electrode substrate is also called a positive electrode substrate, and the active material layer is also called a positive electrode active material layer. When the electrode is a negative electrode, the electrode substrate is also called a negative electrode substrate, and the active material layer is also called a negative electrode active material layer.

In one embodiment of the present invention, the electrode to be reused may be a positive electrode. From the viewpoint of cost-effectiveness of reuse, etc., it is preferable that the active material of the positive electrode to be reused contains a compound containing a rare metal element such as lithium element, nickel element, cobalt element, manganese element, etc. The active material of the positive electrode to be reused is preferably, for example, a lithium transition metal composite oxide, and more preferably a lithium transition metal composite oxide containing nickel element and cobalt element. More specific forms of the active material, etc. will be described in detail later.

The method for extracting the active material from the electrode is not particularly limited, and any known method can be used. For example, the active material layer can be separated from the electrode and the active material can be extracted by contacting the electrode with a liquid such as an organic solvent, an alkaline solution, an acidic solution, or water, by baking the electrode, or by other physical means. Depending on the type of active material to be extracted, a method that is unlikely to have an undesirable effect on the active material is appropriately selected. A combination of multiple methods may also be used. The electrode may be cut to an appropriate size before the active material extraction S1.

Examples of contacting the electrodes with liquid include immersing the electrodes in the liquid and applying the liquid to the electrodes. The electrodes immersed in the liquid may be subjected to further physical treatment such as stirring and sliding. The temperature of the liquid used may be about room temperature (e.g., 10°C or higher but lower than 40°C), or may be heated to, for example, 40°C or higher and 120°C or lower. As the liquid, in addition to a liquid capable of dissolving the binder in the active material layer, a liquid capable of dissolving the electrode other than the active material may be used. A specific example of contacting the electrodes with liquid includes contacting the electrodes with N-methyl-2-pyrrolidone (NMP) as the liquid, and the electrodes may be immersed in NMP. When immersing the electrodes in NMP, the electrodes may be heated, for example, within the above temperature range.

In addition to firing the electrode, the active material layer may be peeled off from the electrode substrate in the electrode by a different means, and only the active material layer may be fired. The electrode or active material layer may be fired in an inert gas atmosphere or an active gas atmosphere. The electrode or active material layer may be fired, for example, under conditions that decompose the binder. For example, when the binder is polyvinylidene fluoride (PVDF), firing may be performed in the range of 350°C to 700°C.

When the active material is extracted from the electrode, the active material may be extracted alone, or may be extracted together with other components (e.g., binder, conductive agent, etc.). For example, the binder may be dissolved by contacting the electrode with a liquid, or the binder may remain. Similarly, the binder may be eliminated by firing the electrode, or the binder may remain. The active material layer containing the active material peeled off from the electrode may be directly subjected to the active material pulverization S2, or the active material layer from which some or all of the components other than the active material have been removed may be subjected to the active material pulverization S2. From the viewpoint of enabling efficient pulverization, it is preferable to remove some of the binder by dissolving, firing, etc. when extracting the active material.

(Pulverization of active material S2)
In this step, the removed active material is pulverized. The removed active material contains secondary particles. The secondary particles contained in the removed active material may be secondary particles having a ratio of the average particle size to the average primary particle size of more than 3 and not more than 100, or may be secondary particles having a ratio of the average particle size to the average primary particle size of more than 5 and not more than 50. The removed active material may contain single particles. The removed active material is pulverized to obtain a regenerative material.

The grinding may be wet grinding, dry grinding, or both. For example, when the active material is extracted by contacting a liquid with an electrode in the active material extraction step S1, a slurry containing the active material may be obtained. Grinding (wet grinding) may be performed on the slurry containing the active material without removing the liquid from the slurry. Alternatively, the liquid may be removed from the slurry, and grinding (dry grinding) may be performed on the solid containing the active material.

Grinding can be carried out by known methods. Examples of grinding methods include methods using a mortar, ball mill, sand mill, vibrating ball mill, planetary ball mill, jet mill, counter jet mill, swirling airflow type jet mill, etc.

By grinding, the secondary particles contained in the active material may be made into single particles. The regenerated material obtained through the grinding S2 of the active material may be, for example, secondary particles having a ratio of the average particle diameter to the average primary particle diameter of 5 or less, or primary particles that are not substantially aggregated. However, it is preferable that the regenerated material obtained is made into a single particle by secondary particles having a ratio of the average particle diameter to the average primary particle diameter of 3 or less, or primary particles that are not substantially aggregated. In this way, the obtained regenerated material is sufficiently made into a single particle, so that the variation in quality is smaller. The ratio of the average particle diameter to the average primary particle diameter of the regenerated material is more preferably 2.5 or less. The ratio of the average particle diameter to the average primary particle diameter of the regenerated material is preferably 1 or more. Note that, due to differences in the measurement methods of the average primary particle diameter and the average particle diameter, the ratio of the average particle diameter to the average primary particle diameter may be less than 1.

(Other processes)
The method for producing a regenerative material according to one embodiment of the present invention may further include a step other than removing the active material S1 and grinding the active material S2.

For example, if the mixture of the extracted active material and other components is pulverized, the recycled material obtained through pulverization may be separated from the other components. Also, if a slurry containing an active material is pulverized, the slurry may be dried after pulverization to obtain a powdered recycled material. On the other hand, the obtained slurry containing the recycled material may be used for the manufacture of electrodes without being dried.

Furthermore, the active material that has been pulverized may be separated into re-living materials based on the degree of pulverization. For example, the degree of pulverization may be determined based on particle size. That is, the active material that has been pulverized may be classified, for example. The active material with a small particle size separated by classification may be taken out as the re-living material, and the active material with a large particle size may be further pulverized. Also, active material that has been broken into too small particles may be removed from the re-living material.

The active material to be reused may be subjected to an adjustment process for the content of charge transport ions such as lithium ions. When the active material is a positive electrode active material, the adjustment process may typically be a process for filling the positive electrode active material with charge transport ions. When the active material is a negative electrode active material, the adjustment process may typically be a process for releasing charge transport ions from the negative electrode active material. Such a process may be performed, for example, by discharging the nonaqueous electrolyte storage element to be reused.

According to a method for producing a re-living material according to one embodiment of the present invention, electrodes or non-aqueous electrolyte storage elements using active materials containing secondary particles can be reused to obtain re-living materials with little variation in quality. This method for producing a re-living material involves direct recycling of active materials, and therefore has the advantage of being relatively low-cost and efficient. The obtained re-living material can be suitably used as an active material for non-aqueous electrolyte storage elements, particularly as an active material for non-aqueous electrolyte secondary batteries.

<Method of Manufacturing Nonaqueous Electrolyte Storage Element>
A method for manufacturing a nonaqueous electrolyte storage element according to one embodiment of the present invention includes preparing an electrode having a re-living material obtained by a method for manufacturing a re-living material according to one embodiment of the present invention. The method for manufacturing the nonaqueous electrolyte storage element may include preparing at least one of a positive electrode and a negative electrode having a re-living material obtained by a method for manufacturing a re-living material according to one embodiment of the present invention. The method for manufacturing the nonaqueous electrolyte storage element may employ a conventional method for manufacturing a nonaqueous electrolyte storage element, except that the re-living material is used as at least a part of the active material.

Specific electrodes can be prepared, for example, by applying an electrode mixture paste directly to an electrode substrate or via an intermediate layer, and then drying. The electrode mixture paste contains each component that constitutes the active material layer, such as a regenerative substance and other binders. The electrode mixture paste usually also contains a dispersion medium. The dispersion medium used to prepare the electrode mixture paste may be an organic solvent such as N-methylpyrrolidone or toluene, or may be water. By applying the electrode mixture paste, drying it, and pressing, etc. as necessary, an electrode active material layer is formed on the electrode substrate, and an electrode is obtained.

In preparing an electrode, the re-living material obtained by the method for producing a re-living material according to one embodiment of the present invention may be mixed with other active materials. In other words, the active material may be a combination of the re-living material obtained by the method for producing a re-living material according to one embodiment of the present invention and other active materials, and the electrode mixture paste may contain the re-living material obtained by the method for producing a re-living material according to one embodiment of the present invention and other active materials.

The other active material preferably contains secondary particles. For example, by using a single-particle recycled material in combination with another active material containing secondary particles, an electrode can be obtained that has both the advantages of a single-particle active material and an active material that is a secondary particle. For example, a single-particle active material has the advantages of being less susceptible to cracking and having excellent life performance. An active material that is a secondary particle has the advantages of having a large specific surface area and excellent charge/discharge reaction performance.

It is also preferable that the other active material has a larger average particle size than the recycled material. By using a recycled material that has been pulverized into small particles in combination with another active material that has a relatively large particle size, it is possible to obtain a high-density electrode with few voids. For example, the average particle size of the other active material may be more than 1 time and not more than 20 times the average particle size of the recycled material, or may be 2 times or more and not more than 10 times.

When active materials are mixed and used, each active material, i.e., the re-living material obtained by the method for producing a re-living material according to one embodiment of the present invention and the other active material, may be an active material having the same elemental composition, or may be an active material having a different elemental composition. Furthermore, the other active material may be a re-living material obtained by a method other than the method for producing a re-living material according to one embodiment of the present invention.

The method for manufacturing a nonaqueous electrolyte storage element according to one embodiment of the present invention may further include preparing a positive electrode and a negative electrode, forming an electrode body by stacking or rolling the positive electrode and the negative electrode via a separator, preparing a nonaqueous electrolyte, and housing the electrode body and the nonaqueous electrolyte in a container. In preparing the positive electrode and the negative electrode, at least one of the positive electrode and the negative electrode is made using a re-living material obtained by the method for manufacturing a re-living material according to one embodiment of the present invention.

According to a method for producing a nonaqueous electrolyte storage element according to one embodiment of the present invention, a nonaqueous electrolyte storage element with little variation in quality can be obtained by reusing an electrode or a nonaqueous electrolyte storage element in which an active material containing secondary particles is used. The structure, etc. of the nonaqueous electrolyte storage element obtained by this production method is not particularly limited. Below, a specific form of a nonaqueous electrolyte storage element to be reused (including positive and negative electrodes, which are electrodes to be reused) and a specific form of a nonaqueous electrolyte storage element obtained using a re-living material (including positive and negative electrodes, which are electrodes obtained using a re-living material) are collectively described. However, the electrode or nonaqueous electrolyte storage element to be reused and the electrode or nonaqueous electrolyte storage element obtained using a re-living material may be different or the same in structure, shape, size, performance, use, etc.

(Non-aqueous electrolyte storage element for reuse or obtained using recycled materials)
A non-aqueous electrolyte storage element (hereinafter simply referred to as "non-aqueous electrolyte storage element") that is to be reused or obtained using a recyclable material includes an electrode assembly having a positive electrode, a negative electrode, and a separator, a non-aqueous electrolyte, and a container that contains the electrode assembly and the non-aqueous electrolyte. The electrode assembly is usually a stacked type in which a plurality of positive electrodes and a plurality of negative electrodes are stacked with a separator interposed therebetween, or a wound type in which a positive electrode and a negative electrode are stacked with a separator interposed therebetween and wound. The non-aqueous electrolyte exists in a state in which it is permeated into the positive electrode, the negative electrode, and the separator. As an example of a non-aqueous electrolyte storage element, a non-aqueous electrolyte secondary battery will be described.

(positive electrode)
The positive electrode has a positive electrode substrate and a positive electrode active material layer disposed on the positive electrode substrate directly or via an intermediate layer.

The positive electrode substrate has electrical conductivity. Whether or not the substrate has "electrical conductivity" is determined by using a volume resistivity of 10 ^-2 Ω·cm measured in accordance with JIS-H-0505 (1975) as a threshold value. As the material of the positive electrode substrate, metals such as aluminum, titanium, tantalum, stainless steel, and alloys thereof are used. Among these, aluminum or aluminum alloys are preferred from the viewpoints of potential resistance, high electrical conductivity, and cost. As the positive electrode substrate, foil, vapor deposition film, mesh, porous material, etc. are mentioned, and foil is preferred from the viewpoint of cost. Therefore, aluminum foil or aluminum alloy foil is preferred as the positive electrode substrate. As the aluminum or aluminum alloy, A1085, A3003, A1N30, etc., as specified in JIS-H-4000 (2014) or JIS-H-4160 (2006) can be exemplified.

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, even 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 volume of the nonaqueous electrolyte storage element.

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 agent such as carbon particles to reduce the contact resistance between the positive electrode substrate and the positive electrode active material layer. The composition of the intermediate layer is not particularly limited, and may contain, for example, a binder and a conductive agent.

The positive electrode active material layer contains a positive electrode active material. The positive electrode active material layer contains optional components such as a conductive agent, a binder, a thickener, and a filler, as necessary.

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 capable of absorbing and releasing lithium ions is usually used. As the positive electrode active material, for example, a transition metal composite oxide having an α-NaFeO ₂ type crystal structure, a transition metal composite oxide having a spinel type crystal structure, a polyanion compound, a chalcogen compound, sulfur, etc. can be mentioned. As the transition metal composite oxide having an α-NaFeO ₂ type crystal structure, a lithium transition metal composite oxide having an α-NaFeO ₂ type crystal structure can be mentioned, and as the transition metal composite oxide having a spinel type crystal structure, a lithium transition metal composite oxide having a spinel type crystal structure can be mentioned. Examples of lithium transition metal composite oxides having α-NaFeO type ₂ crystal structure include Li[Li _x Ni _(1-x) ]O ₂ (0≦x<0.5), Li[Li _x Ni _γ Co _(1-x-γ) ]O ₂ (0≦x<0.5, 0<γ<1, 0<1-x-γ), Li[Li _x Co _(1-x) ]O ₂ (0≦x<0.5), Li[Li _x Ni _γ Mn _(1-x-γ) ]O ₂ (0≦x<0.5, 0<γ<1, 0<1-x-γ), Li[Li _x Ni _γ Mn _β Co _(1-x-γ-β) ]O ₂ (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) ]O ₂ (0≦x<0.5, 0<γ, 0<β, 0.5<γ+β<1, 0<1-x-γ-β), etc. Examples of lithium transition metal composite oxides having a spinel type crystal structure include Li _x Mn ₂ O ₄ and Li _x Ni _γ Mn _(2-γ) O ₄ . Examples of polyanion compounds include _LiFePO4 , _LiMnPO4 , _LiNiPO4 , _LiCoPO4 , _Li3V2 ( _PO4 ) _{3 , Li2MnSiO4} , and _Li2CoPO4F . Examples of chalcogen compounds include titanium disulfide, molybdenum _disulfide , and molybdenum _dioxide . Atoms or polyanions in these materials may be partially substituted with atoms or anion species of other elements. Surfaces of these materials may be coated with other materials. One of these materials may be used alone, or two or more may be mixed and used.

The positive electrode active material preferably contains lithium element, and more preferably is a lithium transition metal composite oxide. The lithium transition metal composite oxide preferably has an α-NaFeO ₂ type crystal structure. The positive electrode active material preferably contains at least one of nickel element, cobalt element, and manganese element. The lithium transition metal composite oxide preferably contains nickel element and cobalt element, and in this case, more preferably further contains manganese element or aluminum element. The lithium transition metal composite oxide is more preferably lithium nickel cobalt manganese composite oxide or lithium nickel cobalt aluminum composite oxide. One or more positive electrode active materials can be used.

Examples of lithium transition metal composite oxides include LiNi1 _/3Co1 / _3Mn1 / _3O2 , LiNi3/ _5Co1 / _{5Mn1 / 5O2} , LiNi1/2Co1/ _{5Mn3 / 10O2} , LiNi1 _{/ 2Co3} / _{10Mn1 /5O2 ,} LiNi8 _{/ 10Co1 / 10Mn1 / 10O2} , _{and LiNi0.8Co0.15Al0.05O2 .}

The positive electrode active material preferably contains lithium transition metal complex oxide in a proportion of 50% by mass or more (preferably 70% by mass to 100% by mass, more preferably 80% by mass to 100% by mass) of the total positive electrode active material in the positive electrode active material layer, and it is more preferable to use a positive electrode active material consisting essentially of lithium transition metal complex oxide.

The positive electrode active material is usually a particle (powder). In one embodiment of the present invention, the positive electrode active material of the positive electrode to be reused contains secondary particles. In one embodiment of the present invention, the positive electrode active material of the nonaqueous electrolyte storage element obtained using the recycled material may contain the recycled material. The average particle diameter of the positive electrode active material is preferably, for example, 0.1 μm to 20 μm. By setting the average particle diameter of the positive electrode active material to be equal to or greater than the above lower limit, the production or handling of the positive electrode active material becomes easier. By setting the average particle diameter of the positive electrode active material to be equal to or less than the above upper limit, the electronic conductivity of the positive electrode active material layer is improved. Note that when a composite of the positive electrode active material and another material is used, the average particle diameter of the composite is taken as the average particle diameter of the positive electrode active material.

In order to obtain powder with a specified particle size, a grinder or a classifier is used. Grinding methods include, for example, methods using a mortar, ball mill, sand mill, vibrating ball mill, planetary ball mill, jet mill, counter jet mill, swirling airflow type jet mill, or a sieve. Wet grinding in the presence of water or an organic solvent such as hexane can also be used during grinding. As classification methods, a sieve or an air classifier can be used as necessary for both dry and wet methods.

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, it is possible to achieve both high energy density and manufacturability of the positive electrode active material layer.

The conductive agent is not particularly limited as long as it is a material having electrical conductivity. Examples of such conductive agents 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 nanotubes (CNT), fullerene, etc. Examples of the conductive agent include powder and fiber. As the conductive agent, one of these materials may be used alone, or two or more types may be mixed and used. These materials may also be used in combination. For example, a material in which carbon black and CNT are combined may be used. Among these, carbon black is preferred from the viewpoints of electronic conductivity and coatability, and acetylene black is preferred among these.

The content of the conductive agent 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 agent within the above range, the energy density of the nonaqueous electrolyte storage element can be increased.

Examples of binders 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; polysaccharide polymers, etc.

The binder content 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 keeping the binder content within the above range, the positive electrode active material can be stably maintained.

Examples of thickeners include polysaccharide polymers such as carboxymethylcellulose (CMC) and methylcellulose. 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 a thickener is used, 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.

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 aluminosilicates, hydroxides such as magnesium hydroxide, calcium hydroxide, and aluminum hydroxide, carbonates such as calcium carbonate, poorly soluble ion crystals such as calcium fluoride, barium fluoride, and barium sulfate, nitrides such as aluminum nitride and silicon nitride, mineral resource-derived substances such as talc, montmorillonite, boehmite, zeolite, apatite, kaolin, mullite, spinel, olivine, sericite, bentonite, and mica, and artificial products thereof. When a filler is used, the content of the filler 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 filler.

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

(Negative electrode)
The negative electrode has a negative electrode substrate and a negative electrode active material layer disposed on the negative electrode substrate directly or via an intermediate layer. The configuration of the intermediate layer is not particularly limited and can be selected from the configurations exemplified for the positive electrode.

The negative electrode substrate is conductive. Metals such as copper, nickel, stainless steel, nickel-plated steel, and aluminum, or alloys of these, carbonaceous materials, etc. are used as the material for the negative electrode substrate. Among these, copper or copper alloys are preferred. Examples of the negative electrode substrate include foil, vapor deposition film, mesh, and porous materials, with foil being preferred from the viewpoint of cost. Therefore, copper foil or copper alloy foil is preferred as the negative electrode substrate. Examples of copper foil include rolled copper foil and electrolytic copper foil.

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, even 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 nonaqueous electrolyte storage element.

The negative electrode active material layer contains a negative electrode active material. The negative electrode active material layer contains optional components such as a conductive agent, a binder, a thickener, and a filler as necessary. The optional components such as a conductive agent, a binder, a thickener, and a filler can be selected from the materials exemplified for the positive electrode above.

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

The negative electrode active material can be appropriately selected from known negative electrode active materials. As the negative electrode active material for lithium ion secondary batteries, a material capable of absorbing and releasing lithium ions is usually used. Examples of the negative electrode active material include metal Li; metals or semimetals such as Si and Sn; metal oxides or semimetal oxides such as Si oxide, Ti oxide, and Sn oxide; titanium-containing oxides such as Li ₄ Ti ₅ O ₁₂ , LiTiO _{2, and} TiNb ₂ O ₇ ; polyphosphate compounds; silicon carbide; carbon materials such as graphite and non-graphitic carbon (easily graphitized carbon or non-graphitizable carbon). 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 may be mixed and used.

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

"Non-graphitic carbon" refers to a carbon material having an average lattice spacing ( _d002 ) of 0.34 nm or more and 0.42 nm or less of (002) plane determined by X-ray diffraction before charging and discharging or in a discharged state. Examples of non-graphitic carbon include carbon that is difficult to graphitize and carbon that is easy to graphitize. Examples of non-graphitic carbon include resin-derived materials, petroleum pitch or petroleum pitch-derived materials, petroleum coke or petroleum coke-derived materials, plant-derived materials, and alcohol-derived materials.

Here, "discharged state" refers to a state in which the negative electrode active material, the carbon material, is discharged so that lithium ions that can be absorbed and released during charging and discharging are sufficiently released. For example, in a half cell using a negative electrode containing a carbon material as the negative electrode active material as the working electrode and metallic Li as the counter electrode, this is a state in which the open circuit voltage is 0.7 V or higher.

The term "non-graphitizable carbon" refers to a carbon material having the above _d002 of 0.36 nm or more and 0.42 nm or less.

The term "graphitizable carbon" refers to a carbon material having the above _d002 of 0.34 nm or more and less than 0.36 nm.

The negative electrode active material is usually a particle (powder). In one embodiment of the present invention, the negative electrode active material of the negative electrode to be reused contains secondary particles. In one embodiment of the present invention, the negative electrode active material may contain a recycled material in the nonaqueous electrolyte storage element obtained using the recycled material. The average particle diameter of the negative electrode active material may 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 polyphosphate compound, the average particle diameter may be 1 μm or more and 100 μm or less. When the negative electrode active material is Si, Sn, Si oxide, Sn oxide, or the like, the 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 more than the above lower limit, the negative electrode active material can be easily manufactured or handled. By setting the average particle diameter of the negative electrode active material to be equal to or less than the above upper limit, the electronic conductivity of the negative electrode active material layer is improved. In order to obtain powder with a predetermined particle diameter, a grinder, a classifier, or the like is used. The pulverization method and classification method can be selected from, for example, the methods exemplified for the positive electrode above. When the negative electrode active material is a metal such as metallic Li, the negative electrode active material layer may be in the form of a foil.

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, it is possible to achieve both high energy density and manufacturability of the negative electrode active material layer.

(Separator)
The separator can be appropriately selected from known separators. For example, a separator consisting of only a substrate 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 substrate layer, etc. can be used as the separator. Examples of the shape of the substrate layer of the separator include woven fabric, nonwoven fabric, and porous resin film. Among these shapes, a porous resin film is preferred from the viewpoint of strength, and a nonwoven fabric is preferred from the viewpoint of non-aqueous electrolyte retention. As the material of the substrate layer of the separator, polyolefins such as polyethylene and polypropylene are preferred from the viewpoint of shutdown function, and polyimide and aramid are preferred from the viewpoint of oxidation decomposition resistance. A material obtained by combining these resins may be used as the substrate layer of the separator.

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 under an air atmosphere at 1 atmosphere, and more preferably have a mass loss of 5% or less when heated from room temperature to 800°C. Examples of materials with a mass loss of a predetermined amount 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; mineral resource-derived substances such as talc, montmorillonite, boehmite, zeolite, apatite, kaolin, mullite, spinel, olivine, sericite, bentonite, and mica, or man-made products thereof. As the inorganic compound, these substances may be used alone or in the form of a complex, or two or more of them may be mixed and used. Among these inorganic compounds, silicon oxide, aluminum oxide, or aluminosilicates are preferred from the viewpoint of the safety of the nonaqueous electrolyte storage element.

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

As the separator, a polymer gel composed of a polymer and a non-aqueous electrolyte may be used. Examples of polymers include polyacrylonitrile, polyethylene oxide, polypropylene oxide, polymethyl methacrylate, polyvinyl acetate, polyvinylpyrrolidone, and polyvinylidene fluoride. The use of a polymer gel has the effect of suppressing leakage. As the separator, a polymer gel may be used in combination with the porous resin film or nonwoven fabric described above.

(Non-aqueous electrolyte)
The nonaqueous electrolyte may be appropriately selected from known nonaqueous electrolytes. The nonaqueous electrolyte may be a nonaqueous electrolyte solution. The nonaqueous electrolyte solution includes a nonaqueous solvent and an electrolyte salt dissolved in the nonaqueous solvent.

The non-aqueous solvent can be appropriately selected from known non-aqueous solvents. Examples of non-aqueous solvents include cyclic carbonates, chain carbonates, carboxylate esters, phosphate esters, sulfonate esters, ethers, amides, and nitriles. Non-aqueous solvents in which some of the hydrogen atoms contained in these compounds are replaced with halogens may also be used.

Cyclic carbonates include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinylene carbonate (VC), vinylethylene carbonate (VEC), chloroethylene carbonate, fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), styrene carbonate, 1-phenylvinylene carbonate, 1,2-diphenylvinylene carbonate, etc. Of these, EC is preferred.

Examples of chain carbonates 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.

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 combination of a cyclic carbonate and a chain carbonate. By using a cyclic carbonate, it is possible to promote dissociation of the electrolyte salt and improve the ionic conductivity of the non-aqueous electrolyte. By using a chain carbonate, it is possible to keep the viscosity of the non-aqueous electrolyte low. When using a combination of a cyclic carbonate and a chain carbonate, it is preferable that the volume ratio of the cyclic carbonate to the chain carbonate (cyclic carbonate:chain carbonate) is, for example, in the range of 5:95 to 50:50.

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, etc. Among these, lithium salts are preferred.

Examples of the lithium salt include inorganic lithium _salts such as _LiPF6 , _LiPO2F2 , _LiBF4 , _LiClO4 , and LiN( _SO2F ) ₂ ; lithium oxalate salts such as lithium bis(oxalate)borate (LiBOB), lithium difluorooxalateborate (LiFOB), and 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} , and LiC(SO2C2F5) _{3 .} Among these, inorganic lithium salts are preferred, and _LiPF6 is more preferred.

The content of the electrolyte salt in the nonaqueous electrolyte solution is preferably 0.1 mol/dm ³ or more and 2.5 mol/dm ³ or less, more preferably 0.3 mol/dm ³ or more and 2.0 mol/dm ³ or less, even more preferably 0.5 mol/dm ³ or more and 1.7 mol/dm ³ or less, and particularly preferably 0.7 mol/dm ³ or more and 1.5 mol/dm ³ or less, at 20° C. and 1 atmospheric pressure. By setting the content of the electrolyte salt in the above range, the ionic conductivity of the nonaqueous electrolyte solution can be increased.

The non-aqueous electrolyte may contain additives in addition to the non-aqueous solvent and electrolyte salt. Examples of additives include aromatic compounds such as biphenyl, alkylbiphenyl, terphenyl, partially hydrogenated terphenyl, cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenyl ether, and dibenzofuran; partial halides 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, methylvinylene carbonate, ethylvinylene carbonate, succinic anhydride, glutaric anhydride, maleic anhydride, citraconic anhydride, glutaconic anhydride, itaconic anhydride, and cyclohexanedicarboxylic anhydride; ethylene sulfite, propylene sulfite, and sulfurous acid. Examples of the additives include dimethyl sulfide, 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-propene sultone, 1,3-propane sultone, 1,4-butane sultone, 1,4-butene sultone, perfluorooctane, tristrimethylsilyl borate, tristrimethylsilyl phosphate, tetrakistrimethylsilyl titanate, lithium monofluorophosphate, and lithium difluorophosphate. These additives may be used alone or in combination of two or more.

The content of the additives contained in the non-aqueous electrolyte is preferably 0.01% by mass to 10% by mass, more preferably 0.1% by mass to 7% by mass, even more preferably 0.2% by mass to 5% by mass, and particularly preferably 0.3% by mass to 3% by mass. By setting the content of the additives within the above range, it is possible to improve the capacity retention performance or cycle performance after high-temperature storage, and to further improve safety.

A solid electrolyte may be used as the non-aqueous electrolyte, or a non-aqueous electrolyte solution and a solid electrolyte may be used in combination.

The solid electrolyte can be selected from any material that has ionic conductivity such as lithium, sodium, calcium, etc., and is solid at room temperature (e.g., 15°C to 25°C). Examples of solid electrolytes include sulfide solid electrolytes, oxide solid electrolytes, nitride solid electrolytes, and polymer solid electrolytes.

In the case of a lithium ion secondary battery, examples of the sulfide solid electrolyte include Li ₂ S—P ₂ S ₅ , LiI—Li ₂ S—P ₂ S ₅ , and Li ₁₀ Ge—P ₂ S ₁₂ .

The shape of the non-aqueous electrolyte storage element is not particularly limited, and examples include cylindrical batteries, square batteries, flat batteries, coin batteries, button batteries, etc.

Figure 2 shows a nonaqueous electrolyte storage element 1 as an example of a square battery. Note that this figure is a see-through view of the inside of the container. An electrode body 2 having a positive electrode and a negative electrode wound with a separator sandwiched between them is stored in a square 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.

(Electricity storage device)
The nonaqueous electrolyte storage element can be mounted as an electricity storage unit (battery module) comprising a plurality of nonaqueous electrolyte storage elements in, for example, an automobile power source for an electric vehicle (EV), a hybrid electric vehicle (HEV), or a plug-in hybrid electric vehicle (PHEV), a power source for electronic devices such as a personal computer or a communication terminal, or a power source for power storage.

FIG. 3 shows an example of an energy storage device 30 which further comprises an energy storage unit 20, which is an assembly of two or more electrically connected nonaqueous electrolyte energy storage elements 1. The energy storage device 30 may include a bus bar (not shown) which electrically connects two or more nonaqueous electrolyte energy storage elements 1, a bus bar (not shown) which electrically connects two or more energy storage units 20, etc. The energy storage unit 20 or the energy storage device 30 may include a status monitoring device (not shown) which monitors the status of one or more nonaqueous electrolyte energy storage elements.

<Other embodiments>
The method for producing a regenerative substance and the method for producing a nonaqueous electrolyte storage element of the present invention are not limited to the above-mentioned embodiments, and various modifications may be made within the scope of the present invention. For example, the configuration of one embodiment may be added to the configuration of another embodiment, and part of the configuration of one embodiment may be replaced with the configuration of another embodiment or a well-known technique. Furthermore, part of the configuration of one embodiment may be deleted. Also, a well-known technique may be added to the configuration of one embodiment.

In the above embodiment, the nonaqueous electrolyte storage element is used as a chargeable and dischargeable nonaqueous electrolyte secondary battery (e.g., a lithium ion secondary battery), but the type, shape, size, capacity, etc. of the nonaqueous electrolyte storage element are arbitrary. The present invention can also be applied to various secondary batteries, electric double layer capacitors, lithium ion capacitors, and other capacitors.

In the above embodiment, an electrode body in which a positive electrode and a negative electrode are stacked with a separator interposed therebetween has been described, but the electrode body does not need to include a separator. For example, the positive electrode and the negative electrode may be in direct contact with each other in a state in which a non-conductive layer is formed on the active material layer of the positive electrode or the negative electrode.

The present invention is useful as a technology for recycling non-aqueous electrolyte storage elements, etc.

Reference Signs List 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 Storage unit 30 Storage device

Claims (8)

A method for producing a recycled material, comprising: removing the active material from an electrode having an active material containing secondary particles or a nonaqueous electrolyte storage element including the electrode; and pulverizing the removed active material, wherein the pulverization produces a recycled material. The method for producing a regenerative material according to claim 1, wherein the grinding step includes breaking the secondary particles into single particles. The method for producing a regenerative material according to claim 1 or 2, wherein the active material includes a lithium transition metal composite oxide. The method for producing a regenerative material according to claim 1 or 2, wherein the regenerative material is composed of secondary particles having a ratio of the average particle size to the average primary particle size of 3 or less, or primary particles that are substantially not aggregated. The method for producing a regenerative material according to claim 1 or 2, wherein the electrode or the nonaqueous electrolyte storage element is a recycled product. A method for producing a non-aqueous electrolyte storage element, comprising: preparing an electrode having a regenerative substance obtained by the method for producing a regenerative substance according to claim 1 or 2. The method for producing a nonaqueous electrolyte storage element according to claim 6, wherein preparing the electrode comprises mixing the regenerative material with another active material including secondary particles. The method for producing a nonaqueous electrolyte storage element according to claim 6, wherein preparing the electrode comprises mixing the regenerative material with another active material having a larger average particle size than the regenerative material.