Method for producing recycled active material and method for producing nonaqueous electrolyte power storage element

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 regenerating material and manufacturing method for non-aqueous electrolyte storage element

[0001] The present invention relates to a method for producing a regenerative substance and a method for producing a non-aqueous electrolyte electricity storage element.

[0002] Due to their high energy density, non-aqueous electrolyte secondary batteries, such as lithium ion secondary batteries, are widely used in electronic devices such as personal computers and communication terminals, automobiles, etc. 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 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 energy storage elements.

[0003] As the market for nonaqueous electrolyte storage elements expands, efforts are being made to develop methods for recycling used nonaqueous electrolyte storage elements, etc. One method under consideration for recycling nonaqueous electrolyte storage elements is a method known as direct recycling, in which active materials are extracted from electrodes of the nonaqueous electrolyte storage elements and reused as active materials without dissolving the extracted active materials or decomposing them into raw material compounds containing the constituent elements (see Patent Document 1).

[0004] Japanese Patent Application Publication No. 2014-207192

[0005] Direct recycling of active materials is considered to be a more cost-effective and efficient method of recycling active materials than synthesizing new active materials using active materials extracted from electrodes as raw materials. However, in the case of nonaqueous electrolyte storage elements equipped with electrodes containing secondary particle active materials, cracking is likely to progress due to repeated expansion and contraction of the active material during use, such as charging and discharging. The degree of cracking of each secondary particle varies significantly depending on the usage conditions of the nonaqueous electrolyte storage element, its position in the electrode, and other factors. Therefore, the degree of cracking in active materials extracted from electrodes and other components of used nonaqueous electrolyte storage elements varies greatly. Because 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 variations in the quality of electrodes and nonaqueous electrolyte storage elements manufactured using such materials.

[0006] An object of the present invention is to provide a method for producing a recycled material that can obtain recycled material 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 a nonaqueous electrolyte storage element that can obtain nonaqueous electrolyte storage elements with little variation in quality.

[0007] A method for producing a regenerative substance according to one aspect 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, and pulverizing the extracted active material, thereby obtaining a regenerative substance by the pulverization.

[0008] A method for manufacturing a nonaqueous electrolyte storage element according to another aspect of the present invention includes fabricating an electrode having a recycled material obtained by the method for manufacturing a recycled material according to one aspect of the present invention.

[0009] According to one aspect of the present invention, there can be provided a method for producing a recycled material that can obtain recycled material with little variation in quality by reusing an electrode or nonaqueous electrolyte storage element that uses an active material containing secondary particles, and a method for producing a nonaqueous electrolyte storage element that can obtain nonaqueous electrolyte storage elements with little variation in quality.

[0010] Fig. 1 is a flow chart showing one embodiment of a method for producing a regenerative substance. 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.

[0011] First, an outline of the method for producing a regenerative substance and the method for producing a nonaqueous electrolyte electricity storage element disclosed in this specification will be described.

[0012] (1) A method for producing a regenerative substance according to one aspect 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, and pulverizing the extracted active material, thereby obtaining a regenerative substance by the pulverization.

[0013] According to the method for producing a recycled material described in (1) above, electrodes or non-aqueous electrolyte storage elements using active materials containing secondary particles can be reused to obtain recycled materials with little variation in quality (i.e., non-uniformity). 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 cause of quality variation. Therefore, by removing the active material from the electrode or non-aqueous electrolyte storage element and pulverizing the removed active material, secondary particles with less cracking are preferentially pulverized, and all active materials are cracked to the same degree. Thus, according to the method for producing a recycled material described in (1) above, pulverizing the removed active material reduces variation in the degree of cracking of the active material, thereby obtaining recycled materials with little variation in quality.

[0014] The term "secondary particles" refers to particles formed by agglomeration of multiple primary particles. The term "primary particles" refers to particles in which no grain boundaries are observed on the surface when observed with a scanning electron microscope (SEM).

[0015] (2) In the method for producing a regenerating material described in (1) above, the pulverization may include breaking the secondary particles into single particles.

[0016] According to the method for producing a recycled material described above in (2), the active material existing as secondary particles is converted into single particles, so that a recycled material with less variation in quality can be obtained.

[0017] "Single particle" refers to the reduction in the number of primary particles constituting 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 to the average primary particle size before separation. "Single particle" refers to a particle consisting of only one primary particle. In other words, single particle does not only refer to the reduction to a single particle. Note that in pulverization, in addition to the reduction of secondary particles to single particles, primary particles may also be pulverized into finer primary particles.

[0018] (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.

[0019] Lithium transition metal composite oxides are generally used as active materials in the form of secondary particles, and are prone to cracking during charge and discharge. Therefore, lithium transition metal composite oxides in the form of secondary particles extracted from electrodes or nonaqueous electrolyte storage elements have particularly large cracking variations. Therefore, the method for producing a recycled material described in (3) above, which reuses electrodes or nonaqueous electrolyte storage elements that use such lithium transition metal composite oxides as active materials, particularly significantly achieves the advantage of the present invention, which is that recycled materials with little quality variation can be obtained.

[0020] (4) In the method for producing a regenerative substance described in any one of (1) to (3) above, the regenerative substance may consist of secondary particles having a ratio of average particle diameter to average primary particle diameter of 3 or less, or primary particles that are substantially unagglomerated.

[0021] According to the method for producing the recyclable material described in (4) above, the obtained recyclable material is broken into pieces with particularly high uniformity, so that a recyclable material with less variation in quality can be obtained.

[0022] The "average primary particle diameter" of the active material and the regenerating material is the average value of the primary particle diameters of any 50 primary particles constituting the active material or the regenerating 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 the short diameter, and the diameter passing through the center and perpendicular to the short diameter is the longest diameter. The average value of the longest diameter and the shortest diameter is the particle diameter. If there are two or more shortest diameters, the longest diameter perpendicular to the short diameter is the shortest diameter. The "average particle diameter" of the active material and the regenerating material is the 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 laser diffraction / scattering method on a diluted solution obtained by diluting the active material or the regenerating material with a solvent in accordance with JIS-Z-8815 (2013). It has been confirmed that the average particle diameter based on the above measurement is substantially consistent with the average particle diameter (secondary particle diameter) of each secondary particle measured by extracting 50 particles from an SEM image of the particles, excluding extremely large and extremely small particles. The particle diameter of each secondary particle based on this measurement from the SEM image is determined as follows. Based on the SEM image, the shortest diameter passing through the center of the smallest circumscribing circle of each secondary particle is defined as the minor diameter, and the diameter passing through the center and perpendicular to the minor diameter is defined as the major diameter. The average of the major and minor diameters is defined as the particle diameter of each secondary particle. When there are two or more shortest diameters, the longest diameter perpendicular to the minor diameter is defined as the minor diameter. "Substantially non-aggregated primary particles" refers to primary particles in which, when observed with an SEM, multiple primary particles exist independently without agglomeration, or primary particles in which primary particles are generally not directly bonded to other primary particles. When a regenerative substance is incorporated into the electrodes of a non-aqueous electrolyte storage element, the average primary particle size and average particle size of the regenerative substance shall be the values ​​measured when the non-aqueous electrolyte storage element is charged at a constant current of 0.05 C until the charge end voltage for normal use is reached, and then, after a 30-minute rest, is discharged at a constant current of 0.05 C until the discharge end voltage for normal use is reached. "During normal use" refers to the case where the non-aqueous electrolyte storage element is used under the charge and discharge conditions recommended or specified for the non-aqueous electrolyte storage element.For example, if an apparatus for using the nonaqueous electrolyte electricity storage element is available, the nonaqueous electrolyte electricity storage element may be used in the apparatus.

[0023] (5) In the method for producing a regenerative substance according to any one of (1) to (4) above, the electrode or the nonaqueous electrolyte storage element may be a recycled product.

[0024] Generally, when an electrode or a nonaqueous electrolyte storage element is a used product that has 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 the quality variation resulting from this variation tends to be large. Therefore, the method for producing a recycled material described in (5) above, which reuses electrodes or nonaqueous electrolyte storage elements collected as used products, particularly significantly achieves the advantage of the present invention, that a recycled material with little variation in quality can be obtained.

[0025] (6) Another aspect of the present invention relates to a method for manufacturing a non-aqueous electrolyte storage element, which comprises producing an electrode having a regenerating material obtained by a method for manufacturing a regenerating material described in any one of (1) to (5) above.

[0026] According to the method for producing a nonaqueous electrolyte storage element described in (6) above, electrodes or nonaqueous electrolyte storage elements using an active material containing secondary particles can be reused to obtain nonaqueous electrolyte storage elements with little variation in quality.

[0027] (7) In the method for manufacturing a nonaqueous electrolyte storage element described in (6) above, preparing the electrode may include mixing the regenerating material with another active material containing secondary particles.

[0028] According to the method for producing a nonaqueous electrolyte storage element described in (7) above, it is possible to obtain a nonaqueous electrolyte storage element that can exhibit good performance according to the required performance, etc.

[0029] (8) In the manufacturing method of the nonaqueous electrolyte storage element described in (6) above, preparing the electrode may include mixing the recycled material with another active material having an average particle diameter larger than that of the recycled material.

[0030] According to the method for producing a nonaqueous electrolyte storage element described in (8) above, for example, it is possible to obtain a nonaqueous electrolyte storage element having high-density electrodes with few voids.

[0031] 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 will be described in detail. 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.

[0032] <Method for Producing Regenerated Material> A method for producing a regenerated 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 "removing the active material S1") and pulverizing the extracted active material (hereinafter also referred to as "pulverizing the active material S2"), thereby obtaining a regenerated material (see FIG. 1). This method for producing a regenerated 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. In other words, this method for producing a regenerated material reuses the active material extracted from the electrode or non-aqueous electrolyte storage element while maintaining its primary crystalline structure (e.g., without significantly changing the crystalline structure or passing through a different compound or element such as a metal), thereby directly recycling the active material. Each step is described below. The specific configurations of the non-aqueous electrolyte storage element and electrodes (positive and negative electrodes) to be reused in this method for producing a regenerated material will be described in detail later.

[0033] (Removal of Active Material S1) In this step, active material containing secondary particles is removed from an electrode or nonaqueous electrolyte storage element. Electrodes or nonaqueous electrolyte storage elements that are subjected to this step, i.e., subjected to reuse, include those collected as used products, those collected as unused products after shipment, and those collected as defective products during manufacturing. It is also possible to use electrodes that have not been incorporated into a nonaqueous electrolyte storage element, such as electrodes collected as defective products during manufacturing. Because the advantage of being able to obtain recycled materials with little variation in quality is particularly pronounced, it is preferable that the electrodes or nonaqueous electrolyte storage elements be collected as used products.

[0034] When a nonaqueous electrolyte storage element is reused, the element is first disassembled using a known method to remove the electrodes. The removed electrodes 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, as long as they contain an active material containing secondary particles. Both the positive and negative electrodes of a nonaqueous electrolyte storage element may be reused. The electrode may, for example, have an electrode substrate and an active material layer disposed on the electrode substrate directly or via an intermediate layer. The active material layer typically 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 referred to as a positive electrode substrate, and the active material layer is also referred to as a positive electrode active material layer. When the electrode is a negative electrode, the electrode substrate is also referred to as a negative electrode substrate, and the active material layer is also referred to as a negative electrode active material layer.

[0035] In one embodiment of the present invention, the electrode to be reused may be a positive electrode. From the viewpoint of cost-effectiveness of recycling, the active material of the positive electrode to be reused preferably includes a compound containing a rare metal element such as lithium, nickel, cobalt, or manganese. 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 and cobalt. More specific examples of the active material will be described in detail below.

[0036] The method for extracting the active material from the electrode is not particularly limited, and known methods can be used. For example, the active material layer can be separated from the electrode and extracted by contacting the electrode with a liquid such as an organic solvent, an alkaline solution, an acidic solution, or water, baking the electrode, or other physical means. Depending on the type of active material to be extracted, a method that is less likely to have an undesirable effect on the active material can be appropriately selected. Alternatively, a combination of multiple methods may be used. Before the active material extraction step S1, the electrode may be cut to an appropriate size.

[0037] Examples of contacting the electrode with a liquid include immersing the electrode in the liquid and applying the liquid to the electrode. The electrode immersed in the liquid may be further subjected to physical treatment such as stirring or 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, about 40°C or higher and 120°C or lower. As the liquid, a liquid capable of dissolving the binder in the active material layer, as well as a liquid capable of dissolving components of the electrode other than the active material, may be used. Specific examples of contacting the electrode with a liquid include contacting the electrode with N-methyl-2-pyrrolidone (NMP) as the liquid, and the electrode may be immersed in NMP. When immersing the electrode in NMP, the immersion may be performed while heating, for example, within the above-mentioned temperature range.

[0038] Alternatively, the active material layer may be peeled off from the electrode substrate by a separate method, 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 under conditions that decompose the binder. For example, when the binder is polyvinylidene fluoride (PVDF), firing may be performed at a temperature in the range of 350°C to 700°C.

[0039] When the active material is extracted from the electrode, only the active material may be extracted alone, or the active material may be extracted together with other components (e.g., a binder, a conductive agent, etc.). For example, the binder may be dissolved by contacting a liquid with the electrode, 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 from the electrode may be subjected to the active material pulverization S2 as is, 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 dissolution, firing, etc. when extracting the active material.

[0040] (Pulverization of active material S2) In this step, the extracted active material is pulverized. The extracted active material contains secondary particles. The secondary particles contained in the extracted active material may be secondary particles having a ratio of their average particle size to their average primary particle size of more than 3 and not more than 100, or may be secondary particles having a ratio of their average particle size to their average primary particle size of more than 5 and not more than 50. The extracted active material may contain single particles. By pulverizing the extracted active material, a recycled material is obtained.

[0041] The pulverization may be wet pulverization, dry pulverization, or both. For example, when the active material is extracted by bringing a liquid into contact with an electrode in the active material extraction step S1, a slurry containing the active material may be obtained. The slurry containing the active material may be pulverized (wet pulverization) without removing the liquid from the slurry. Alternatively, the liquid may be removed from the slurry, and the solid containing the active material may be pulverized (dry pulverization).

[0042] The pulverization can be carried out by a known method, for example, a method 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 airflow type jet mill, or the like.

[0043] The secondary particles contained in the active material may be monolithic through pulverization. The recycled material obtained through pulverization S2 of the active material may be, for example, secondary particles having a ratio of the average particle size to the average primary particle size of 5 or less, or substantially non-aggregated primary particles. However, it is preferable that the recycled material be secondary particles having a ratio of the average particle size to the average primary particle size of 3 or less, or substantially non-aggregated primary particles. By sufficiently monolithicizing the resulting recycled material, the variation in quality is reduced. The ratio of the average particle size to the average primary particle size of the recycled material is more preferably 2.5 or less. The ratio of the average particle size to the average primary particle size of the recycled material is preferably 1 or more. Note that, due to differences in the measurement methods for the average primary particle size and the average particle size, the ratio of the average particle size to the average primary particle size may be less than 1.

[0044] (Other Steps) The method for producing a recyclable material according to one embodiment of the present invention may further include steps other than the step S1 of removing the active material and the step S2 of pulverizing the active material.

[0045] For example, when a mixture of the extracted active material and other components is pulverized, the resulting recycled material may be separated from the other components. When a slurry containing the active material is pulverized, the slurry may be dried after pulverization to obtain a powdered recycled material. Alternatively, the resulting slurry containing the recycled material may be used for the production of an electrode without drying.

[0046] Furthermore, the active material that has undergone pulverization may be separated into recycled 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 undergone pulverization may be classified, for example. The active material with a small particle size separated by classification may be taken out as recycled materials, and the active material with a large particle size may be further pulverized. Furthermore, active material that has been reduced to too small particles may be removed from the recycled materials.

[0047] The active material to be reused may be subjected to a treatment for adjusting the content of charge transport ions such as lithium ions. When the active material is a positive electrode active material, the adjustment treatment may typically be a treatment for filling the positive electrode active material with charge transport ions. When the active material is a negative electrode active material, the adjustment treatment may typically be a treatment for releasing charge transport ions from the negative electrode active material. Such a treatment may be performed, for example, by discharging the nonaqueous electrolyte storage element to be reused.

[0048] According to a method for producing a recycled 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 recycled materials with little variation in quality. Because this method for producing recycled materials involves direct recycling of the active material, it also has the advantage of being relatively low-cost and efficient. The resulting recycled 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.

[0049] <Method for manufacturing a non-aqueous electrolyte storage element> A method for manufacturing a non-aqueous electrolyte storage element according to one embodiment of the present invention comprises fabricating an electrode having a recycled material obtained by a method for manufacturing a recycled material according to one embodiment of the present invention. The method for manufacturing a non-aqueous electrolyte storage element may comprise fabricating at least one of a positive electrode and a negative electrode having a recycled material obtained by a method for manufacturing a recycled material according to one embodiment of the present invention. The method for manufacturing a non-aqueous electrolyte storage element may employ a conventional method for manufacturing a non-aqueous electrolyte storage element, except that the recycled material is used as at least a part of the active material.

[0050] A specific electrode can be produced, for example, by applying an electrode mixture paste to an electrode substrate directly or via an intermediate layer, and then drying. The electrode mixture paste contains each component constituting the active material layer, such as a recycled material and other binders. The electrode mixture paste usually further 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 it as necessary, an electrode active material layer is formed on the electrode substrate, and an electrode is obtained.

[0051] In the preparation of an electrode, the regenerated material obtained by the method for producing a regenerated material according to one embodiment of the present invention may be mixed with other active materials. That is, the regenerated material obtained by the method for producing a regenerated material according to one embodiment of the present invention may be used in combination with other active materials as the active material, and the electrode mixture paste may contain the regenerated material obtained by the method for producing a regenerated material according to one embodiment of the present invention and other active materials.

[0052] 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 having both the advantages of a single-particle active material and an active material that is a secondary particle can be obtained. For example, a single-particle active material has advantages such as being less susceptible to cracking and having excellent life performance. An active material that is a secondary particle has advantages such as a large specific surface area and excellent charge / discharge reaction performance.

[0053] 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 with 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.

[0054] When active materials are mixed, each active material, i.e., the regenerated material obtained by the method for producing a regenerated 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 an active material having a different elemental composition. Furthermore, the other active material may be a regenerated material obtained by a method other than the method for producing a regenerated material according to one embodiment of the present invention.

[0055] A 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 winding the positive electrode and the negative electrode with a separator interposed therebetween, 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 recycled material obtained by a method for manufacturing a recycled material according to one embodiment of the present invention.

[0056] According to a method for manufacturing a nonaqueous electrolyte storage element according to one embodiment of the present invention, electrodes or nonaqueous electrolyte storage elements using an active material containing secondary particles can be reused to obtain nonaqueous electrolyte storage elements with little variation in quality. The structure, etc., of the nonaqueous electrolyte storage element obtained by this manufacturing method is not particularly limited. Below, specific forms of nonaqueous electrolyte storage elements to be reused (including positive and negative electrodes, which are electrodes to be reused) and specific forms of nonaqueous electrolyte storage elements obtained using a recycled material (including positive and negative electrodes, which are electrodes obtained using a recycled 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 recycled material may be the same or different in structure, shape, size, performance, use, etc.

[0057] (Non-aqueous electrolyte storage element to be recycled or obtained using a recycled material) A non-aqueous electrolyte storage element to be recycled or obtained using a recycled material (hereinafter simply referred to as a "nonaqueous electrolyte storage element") comprises an electrode assembly having a positive electrode, a negative electrode, and a separator, a non-aqueous electrolyte, and a container for accommodating the electrode assembly and the non-aqueous electrolyte. The electrode assembly is typically a stacked type in which multiple positive electrodes and multiple negative electrodes are stacked with separators interposed therebetween, or a wound type in which positive electrodes and negative electrodes are stacked with separators interposed therebetween and wound. The non-aqueous electrolyte exists in a state in which it is impregnated into the positive electrode, negative electrode, and separator. As an example of a non-aqueous electrolyte storage element, a non-aqueous electrolyte secondary battery will be described.

[0058] (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.

[0059] The positive electrode substrate has electrical conductivity. Whether or not it has electrical conductivity is determined by whether or not the volume resistivity measured in accordance with JIS-H-0505 (1975) is 10 －２ The resistance is determined using Ω cm as a threshold value. Metals such as aluminum, titanium, tantalum, and stainless steel, or alloys thereof, are used as the material for the positive electrode substrate. Among these, aluminum or aluminum alloys are preferred from the viewpoints of potential resistance, high conductivity, and cost. Examples of the positive electrode substrate include foil, vapor-deposited film, mesh, and porous material, with foil being preferred from the viewpoint of cost. Therefore, aluminum foil or aluminum alloy foil is preferred as the positive electrode substrate. Examples of aluminum or aluminum alloys include A1085, A3003, and A1N30, as specified in JIS-H-4000 (2014) or JIS-H-4160 (2006).

[0060] The average thickness of the positive electrode substrate is preferably 3 μm to 50 μm, more preferably 5 μm to 40 μm, even more preferably 8 μm to 30 μm, and particularly preferably 10 μm to 25 μm. By setting the average thickness of the positive electrode substrate within the above range, the strength of the positive electrode substrate can be increased while increasing the energy density per volume of the nonaqueous electrolyte storage element.

[0061] 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 configuration of the intermediate layer is not particularly limited, and may contain, for example, a binder and a conductive agent.

[0062] The positive electrode active material layer contains a positive electrode active material and, if necessary, optional components such as a conductive agent, a binder, a thickener, and a filler.

[0063] 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. Examples of the positive electrode active material include α-NaFeO ２ Examples of suitable transition metal composite oxides include those having a α-type crystal structure, those having a spinel-type crystal structure, polyanion compounds, chalcogen compounds, and sulfur. ２ Examples of transition metal composite oxides having a crystalline structure include α-NaFeO ２ Examples of the transition metal composite oxides having a spinel-type crystal structure include lithium transition metal composite oxides having a spinel-type crystal structure. ２ As the lithium transition metal composite oxide having a crystalline structure, for example, 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 crystal structure include Li ｘ Mn ２ O ４ , Li ｘ Ni γ Mn （２－γ） O ４ Examples of polyanion compounds include LiFePO ４ , LiMnPO ４ , LiNiPO ４ , LiCoPO ４ , Li ３ V ２ (P.O. ４ ) ３ , Li ２ MnSiO ４ , Li ２ CoPO ４ Examples of the chalcogen compound include titanium disulfide, molybdenum disulfide, and molybdenum dioxide. The atoms or polyanions in these materials may be partially substituted with atoms or anion species of other elements. The surfaces of these materials may be coated with other materials. One of these materials may be used alone, or two or more may be used in combination.

[0064] 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 is α-NaFeO ２It is preferable that the positive electrode active material has a crystalline structure. Furthermore, it is preferable that the positive electrode active material contains at least one of nickel, cobalt, and manganese. The lithium transition metal composite oxide preferably contains nickel and cobalt, and in this case, it is more preferable that it further contains manganese or aluminum. It is more preferable that the lithium transition metal composite oxide is lithium nickel cobalt manganese composite oxide or lithium nickel cobalt aluminum composite oxide. One or more positive electrode active materials can be used.

[0065] Examples of lithium transition metal composite oxides include LiNi １／３ Co １／３ Mn １／３ O ２ , LiNi ３／５ Co １／５ Mn １／５ O ２ , LiNi １／２ Co １／５ Mn ３／１０ O ２ , LiNi １／２ Co ３／１０ Mn １／５ O ２ , LiNi ８／１０ Co １／１０ Mn １／１０ O ２ , LiNi ０．８ Co ０．１５ Al ０．０５ O ２ etc.

[0066] The positive electrode active material preferably contains a lithium transition metal composite oxide in a proportion of 50 mass % or more (preferably 70 mass % to 100 mass %, more preferably 80 mass % to 100 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 a lithium transition metal composite oxide.

[0067] The positive electrode active material is usually in the form of particles (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, a nonaqueous electrolyte storage element obtained using a recycled material may contain a recycled material in the positive electrode active material. The average particle diameter 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 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.

[0068] To obtain powder with a predetermined particle size, a pulverizer, a classifier, or the like is used. Examples of pulverization methods 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 airflow jet mill, or a sieve. Wet pulverization in the presence of water or an organic solvent such as hexane can also be used. As a classification method, a sieve, an air classifier, or the like is used as needed for both dry and wet methods.

[0069] The content of the positive electrode active material in the positive electrode active material layer is preferably 50% by mass to 99% by mass, more preferably 70% by mass to 98% by mass, and even more preferably 80% by mass to 95% by mass. By setting the content of the positive electrode active material within the above range, both high energy density and manufacturability of the positive electrode active material layer can be achieved.

[0070] 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), fullerenes, etc. The conductive agent may be in the form of powder, fiber, etc. As the conductive agent, one of these materials may be used alone, or two or more may be mixed and used. These materials may also be used in combination. For example, a composite material of carbon black and CNT may be used. Among these, carbon black is preferred from the viewpoints of electronic conductivity and coatability, and acetylene black is particularly preferred.

[0071] 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 in this range, the energy density of the nonaqueous electrolyte storage element can be increased.

[0072] 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; and polysaccharide polymers.

[0073] The content of the binder in the positive electrode active material layer is preferably 1% by mass to 10% by mass, more preferably 3% by mass to 9% by mass, by which the positive electrode active material can be stably maintained.

[0074] Examples of thickeners 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, the 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.

[0075] 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, sparingly soluble ionic crystals such as calcium fluoride, barium fluoride, and barium sulfate, nitrides such as aluminum nitride and silicon nitride, mineral-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.

[0076] The positive electrode active material layer may contain typical non-metallic 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.

[0077] 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 above, for example.

[0078] The negative electrode substrate is conductive. Metals such as copper, nickel, stainless steel, nickel-plated steel, and aluminum, alloys thereof, and carbonaceous materials 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 foils, vapor-deposited films, meshes, and porous materials, with foils 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.

[0079] The average thickness of the negative electrode substrate is preferably 2 μm to 35 μm, more preferably 3 μm to 30 μm, even more preferably 4 μm to 25 μm, and particularly preferably 5 μm to 20 μm. By setting the average thickness of the negative electrode substrate within the above range, the strength of the negative electrode substrate can be increased while increasing the energy density per volume of the nonaqueous electrolyte storage element.

[0080] 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 needed. The optional components such as the conductive agent, the binder, the thickener, and the filler can be selected from the materials exemplified for the positive electrode above.

[0081] The negative electrode active material layer may contain typical non-metallic 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 metal 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.

[0082] The negative electrode active material can be appropriately selected from known negative electrode active materials. A material capable of absorbing and releasing lithium ions is usually used as the negative electrode active material for a lithium ion secondary battery. 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; Li ４ Ti ５ O １２ , LiTiO ２、 TiNb ２ O ７Examples of the material include titanium-containing oxides such as titanium dioxide, polyphosphate compounds, silicon carbide, and carbon materials such as graphite and non-graphitic carbon (easily graphitizable 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 used in combination.

[0083] "Graphite" refers to a graphite material that has an average lattice spacing (d ００２ ) is 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 availability of a material with stable physical properties.

[0084] "Non-graphitic carbon" refers to a carbon material that has an average lattice spacing (d ００２ ) is 0.34 nm or more and 0.42 nm or less. Examples of non-graphitizable carbon include non-graphitizable carbon and graphitizable carbon. Examples of non-graphitizable 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.

[0085] Here, the "discharged state" refers to a state in which the battery is discharged so that lithium ions capable of being absorbed and desorbed during charging and discharging are sufficiently released from the carbon material serving as the negative electrode active material. For example, this refers to a state in which the open circuit voltage of 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 is 0.7 V or higher.

[0086] "Non-graphitizable carbon" refers to the above-mentioned d ００２ The term "carbon material" refers to a carbon material having a particle size of 0.36 nm or more and 0.42 nm or less.

[0087] "Graphitizable carbon" refers to the above-mentioned d ００２ The term "carbon material" refers to a carbon material having a particle size of 0.34 nm or more and less than 0.36 nm.

[0088] The negative electrode active material is usually in the form of particles (powder). In one embodiment of the present invention, the negative electrode active material of the negative electrode to be recycled contains secondary particles. In one embodiment of the present invention, a nonaqueous electrolyte storage element obtained using a recycled material may contain a recycled material in the negative electrode active 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 greater than the above lower limit, the production or handling of the negative electrode active material becomes easier. 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. A pulverizer, a classifier, or the like is used to obtain powder with a predetermined particle diameter. The pulverization method and classification method can be selected from 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.

[0089] The content of the negative electrode active material in the negative electrode active material layer is preferably 60% by mass to 99% by mass, more preferably 90% by mass to 98% by mass. By setting the content of the negative electrode active material within this range, both high energy density and manufacturability of the negative electrode active material layer can be achieved.

[0090] (Separator) The separator can be appropriately selected from known separators. Examples of separators that can be used include separators consisting of only a substrate layer and separators in which a heat-resistant layer containing heat-resistant particles and a binder is formed on one or both surfaces of the substrate layer. Examples of the shape of the substrate layer of the separator include woven fabric, nonwoven fabric, and porous resin film. Among these shapes, porous resin films are preferred from the viewpoint of strength, and nonwoven fabrics are preferred from the viewpoint of non-aqueous electrolyte retention. Materials for the substrate layer of the separator are preferably polyolefins such as polyethylene and polypropylene from the viewpoint of shutdown function, and polyimide and aramid from the viewpoint of oxidative decomposition resistance. A composite material of these resins may also be used for the substrate layer of the separator.

[0091] The heat-resistant particles contained in the heat-resistant layer preferably exhibit 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 exhibit a mass loss of 5% or less when heated from room temperature to 800°C. Examples of materials exhibiting a mass loss of a predetermined value 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; covalently bonded crystals such as silicon and diamond; mineral-derived substances such as talc, montmorillonite, boehmite, zeolite, apatite, kaolin, mullite, spinel, olivine, sericite, bentonite, and mica, as well as artificial 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 used in combination. Among these inorganic compounds, silicon oxide, aluminum oxide, or aluminosilicate is preferred from the viewpoint of safety of the nonaqueous electrolyte storage element.

[0092] The porosity of the separator is preferably 80% by volume or less from the viewpoint of strength, and is preferably 20% by volume or more from the viewpoint of discharge performance. Here, "porosity" refers to a volume-based value measured with a mercury porosimeter.

[0093] The separator may be a polymer gel composed of a polymer and a non-aqueous electrolyte. 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. The separator may be a combination of the porous resin film or nonwoven fabric described above and a polymer gel.

[0094] (Non-aqueous electrolyte) The non-aqueous electrolyte can be appropriately selected from known non-aqueous electrolytes. The non-aqueous electrolyte may be a non-aqueous electrolyte solution. The non-aqueous electrolyte solution contains a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent.

[0095] The non-aqueous solvent can be appropriately selected from known non-aqueous solvents. Examples of non-aqueous solvents include cyclic carbonates, chain carbonates, carboxylic acid esters, phosphate esters, sulfonic acid esters, ethers, amides, and nitriles. Non-aqueous solvents in which some of the hydrogen atoms contained in these compounds have been substituted with halogens may also be used.

[0096] Examples of 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.

[0097] 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.

[0098] It is preferable to use a cyclic carbonate or a chain carbonate as the non-aqueous solvent, and it is more preferable to use a cyclic carbonate and a chain carbonate in combination. The use of a cyclic carbonate can promote dissociation of the electrolyte salt and improve the ionic conductivity of the non-aqueous electrolyte. The use of a chain carbonate can reduce the viscosity of the non-aqueous electrolyte. 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.

[0099] The electrolyte salt can be appropriately selected from known electrolyte salts, such as lithium salts, sodium salts, potassium salts, magnesium salts, and onium salts. Of these, lithium salts are preferred.

[0100] The lithium salt is LiPF ６ , LiPO ２ F ２ , LiBF ４ , LiClO ４ , LiN(SO ２ F) ２ inorganic lithium salts such as lithium oxalate salts, lithium bis(oxalate)borate (LiBOB), lithium difluorooxalateborate (LiFOB), and lithium bis(oxalate)difluorophosphate (LiFOP); ３ CF ３ , LiN(SO ２ CF ３ ) ２ , LiN(SO ２ C ２ F ５ ) ２ , LiN(SO ２ CF ３ ) (SO ２ C ４ F ９ ), LiC(SO ２ CF ３ ) ３ , LiC(SO ２ C ２ F ５ ) ３ Among these, inorganic lithium salts are preferred, and LiPF ６ is more preferred.

[0101] The content of the electrolyte salt in the non-aqueous electrolyte solution is 0.1 mol / dm at 20°C and 1 atmosphere. ３ 2.5mol / dm or more ３ It is preferably 0.3 mol / dm or less. ３ 2.0mol / dm or more ３ It is more preferable that it is 0.5 mol / dm or less. ３ More than 1.7mol / dm ３It is more preferable that it is 0.7 mol / dm or less. ３ More than 1.5mol / dm ３ By setting the content of the electrolyte salt within the above range, the ionic conductivity of the non-aqueous electrolyte can be increased.

[0102] The non-aqueous electrolyte may contain additives in addition to the non-aqueous solvent and the electrolyte salt. Examples of the 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 sulfur dioxide. Examples of the additive include dimethyl ether, 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.

[0103] The content of the additive 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, based on the total mass of the non-aqueous electrolyte. By setting the content of the additive within the above range, it is possible to improve the capacity retention performance or cycle performance after high-temperature storage, and further improve safety.

[0104] The non-aqueous electrolyte may be a solid electrolyte, or a non-aqueous electrolytic solution and a solid electrolyte may be used in combination.

[0105] The solid electrolyte can be selected from any material that has ionic conductivity of lithium, sodium, calcium, etc. and is solid at room temperature (e.g., 15° C. to 25° C.) Examples of the solid electrolyte include sulfide solid electrolytes, oxide solid electrolytes, nitride solid electrolytes, and polymer solid electrolytes.

[0106] As the sulfide solid electrolyte, in the case of a lithium ion secondary battery, for example, Li ２ S-P ２ S ５ , LiI-Li ２ S-P ２ S ５ , Li １０ Ge-P ２ S １２ etc.

[0107] The shape of the nonaqueous electrolyte storage element is not particularly limited, and examples thereof include cylindrical batteries, prismatic batteries, flat batteries, coin batteries, and button batteries.

[0108] Figure 2 shows a nonaqueous electrolyte storage element 1 as an example of a prismatic battery. This figure is a see-through view of the inside of the container. An electrode assembly 2 having a positive electrode and a negative electrode wound with a separator sandwiched between them 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.

[0109] (Electricity Storage Device) The nonaqueous electrolyte electricity storage element can be mounted as an electricity storage unit (battery module) comprising a plurality of nonaqueous electrolyte electricity storage elements in a power source for an automobile such as an electric vehicle (EV), a hybrid electric vehicle (HEV), or a plug-in hybrid electric vehicle (PHEV), a power source for an electronic device such as a personal computer or a communication terminal, or a power source for power storage.

[0110] 3 shows an example of an energy storage device 30 in which energy storage units 20, each of which is an assembly of two or more electrically connected nonaqueous electrolyte energy storage elements 1, are further assembled. The energy storage device 30 may include a bus bar (not shown) that electrically connects two or more nonaqueous electrolyte energy storage elements 1, a bus bar (not shown) that 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) that monitors the status of one or more nonaqueous electrolyte energy storage elements.

[0111] <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-described embodiments, and various modifications may be made without departing from the spirit of the present invention. For example, the configuration of one embodiment can be added to the configuration of another embodiment, and part of the configuration of one embodiment can be replaced with the configuration of another embodiment or well-known technology. Furthermore, part of the configuration of one embodiment can be deleted. Also, well-known technology can be added to the configuration of one embodiment.

[0112] 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 nonaqueous electrolyte storage element may be of any type, shape, size, capacity, etc. The present invention can also be applied to various secondary batteries, electric double layer capacitors, lithium ion capacitors, and other capacitors.

[0113] In the above embodiment, the electrode assembly in which the positive electrode and the negative electrode are stacked with a separator interposed therebetween has been described, but the electrode assembly 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 in which a non-conductive layer is formed on the active material layer of the positive electrode or the negative electrode.

[0114] The present invention is useful as a technology for recycling non-aqueous electrolyte electricity storage elements and the like.

[0115] REFERENCE SIGNS LIST 1 nonaqueous 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. A method for producing a recycled material, comprising: extracting 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 extracted active material, wherein the pulverization produces a recycled material.

2. The method for producing a regenerative material according to claim 1, wherein the grinding step includes breaking down the secondary particles into single particles.

3. The method for producing a regenerative material according to claim 1 or 2, wherein the active material comprises a lithium transition metal composite oxide.

4. A method for producing a regenerative material as described in claim 1 or claim 2, wherein the regenerative material consists of secondary particles having a ratio of average particle size to average primary particle size of 3 or less, or primary particles that are substantially not agglomerated.

5. The method for producing a regenerative material according to claim 1 or 2, wherein the electrode or the nonaqueous electrolyte storage element is a recovered used product.

6. A method for manufacturing a non-aqueous electrolyte storage element, comprising: preparing an electrode having a regenerative substance obtained by the method for manufacturing a regenerative substance according to claim 1 or 2.

7. The method for producing a nonaqueous electrolyte storage element according to claim 6, wherein preparing the electrode comprises mixing the recycled material with another active material including secondary particles.

8. The method for producing a nonaqueous electrolyte storage element as described in claim 6, wherein preparing the electrode comprises mixing the recycled material with another active material having an average particle size larger than that of the recycled material.