JP2012022969A - Method for regenerating electrode of lithium ion battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for regenerating an electrode of a lithium ion battery capable of obtaining a reproduction battery by regenerating and recycling the electrode kept in a state of the coated electrode (an electrode active material layer coated on a collector) with respect to a used lithium ion battery.SOLUTION: The present invention can be attained by a method for regenerating an electrode of a lithium ion battery with respect to a used lithium ion battery. The method includes processes for the used lithium ion battery to process at least either a positive electrode or a negative electrode of the battery with polar solvent, to dry the electrode processed with the solvent, and to reinject an electrolyte into the battery including a dried electrode.

Description

  The present invention relates to a method for regenerating an electrode of a lithium ion battery (hereinafter also simply referred to as LIB).

  Conventional LIB recycling technology is limited to a technology that completely destroys a battery, peels off an electrode active material layer from a current collector using a strong acid or the like, and collects a rare metal element or the like as a mineral.

  This method requires a large amount of man-hours, chemical costs, and dedicated processing tanks. Therefore, the cost of recovered valuables does not drop as expected because these costs are included. In this case, it is only about half to 1/3 of the case of newly refining from ore. Therefore, the cost merit is limited to Co, Cu, Li and the like.

  In addition, since the binder is deteriorated by acid or heat treatment, the molecular weight is reduced, and the binder can no longer be reused.

  When the current collector also uses a strong acid, the current collector is dissolved by an acid or at least remarkably deteriorates, so that electronic conduction cannot be expected and refining is required.

  In Patent Document 1, the electrode (positive electrode) is washed with water or alcohol without completely destroying the battery, and then the positive electrode current collector and the active material are separated by immersion and stirring in an aqueous sulfuric acid solution having a pH of 0 to 3. A collection method has been proposed.

JP 2007-122885 A

  However, even in the method described in Patent Document 1, after the positive electrode active material layer is broken into pieces, a rare metal element or the like used in the positive electrode active material is reused as a mineral. That is, in the prior art including Patent Document 1, since it cannot be reused as a coated electrode (electrode active material layer coated / formed on a current collector), from the viewpoint of recycling, cost and environmental impact There was a problem that it was not advantageous.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an LIB electrode regeneration method in which a regenerated battery can be obtained by regenerating and reusing a used LIB while maintaining the form of a coated electrode. And

  The purpose of the above is to wash the used LIB electrode with a polar solvent, wash away the deteriorated material containing Li adhering to the surface of the active material particles, which is the main component of capacity deterioration of the electrode, and dry it sufficiently to evaporate the washing solvent. This is achieved by the LIB electrode regeneration method of re-injecting a battery having a dry electrode.

  According to the present invention, the electrode can be regenerated as it is by treating (washing) the deposit represented by SEI (solid electrolyte interface) present on the surface of the electrode (especially active material particles) with a polar solvent. . For this reason, the electrode is not destroyed, and no strong acid or strong alkali is used. Therefore, no solid waste is generated, and the environmental load is low and an inexpensive rechargeable battery can be supplied.

It is a schematic sectional drawing which shows the basic composition of the laminated | stacked flat lithium ion battery which can be recycled as used LIB applicable to any embodiment. It is the perspective view which represented typically the external appearance of the laminated | stacked flat lithium ion battery which can be recycled as used LIB applicable to any embodiment. In the electrode regeneration method for a lithium ion battery according to the first embodiment, a used electrode is treated with a polar solvent, dried and re-injected into a reusable / reusable electrode (battery). FIG. It is drawing which represented the outline | summary of each process of the said embodiment in the electrode regeneration method of the lithium ion battery of 2nd Embodiment. It is drawing which showed the outline | summary of each process which applied the said embodiment to reproduction | regeneration of a positive electrode in the electrode reproduction | regeneration method of the lithium ion battery of 3rd Embodiment. In the electrode regeneration method of the lithium ion battery of 4th Embodiment, it is drawing which represented the outline of the battery in the said embodiment. It is a schematic sectional drawing which shows the internal structure of the laminate-type lithium ion secondary battery produced by the Example and the comparative example. It is drawing which represented the outline | summary of each process of 3rd Embodiment which reproduces | regenerates the negative electrode applied in Example 3. FIG. It is a graph which shows the discharge capacity per unit area of (1) theoretical value of the battery produced in Example 4, (2) after deterioration, and (3) after washing.

  Hereinafter, typical embodiments of a method for regenerating an electrode of a lithium ion battery of the present invention will be described in detail with reference to the drawings.

[I] Overall Structure and Appearance of Lithium Ion Batteries Common to All Embodiments As a used LIB that can be applied to any of the embodiments described below, the entire typical LIB that can be recycled and reused The structure and appearance will be briefly described with reference to the drawings.

(1) Overall structure of battery The LIB that can be regenerated and reused is not particularly limited. For example, when the LIB is distinguished by its form / structure, it can be applied to any conventionally known form / structure, such as a wound (cylindrical) battery or a stacked (flat) battery.

  In the following description using the drawings, a description will be given by taking a laminated flat lithium ion battery as a typical LIB as an example. However, the technical scope of the present embodiment is not limited to the following forms.

  FIG. 1 is a schematic diagram showing a basic configuration of a stacked flat lithium ion battery (also simply referred to as a stacked battery) that can be recycled as a used LIB that can be applied to any of the following embodiments. It is. As shown in FIG. 1, in the rechargeable / reusable stacked battery 10, a substantially rectangular power generation element 21 in which a charge / discharge reaction actually proceeds is sealed inside a laminate sheet 29 that is an exterior body. It has a structure. Here, in the power generation element 21, the negative electrode in which the negative electrode active material layer 13 is disposed on both surfaces of the negative electrode current collector 11, the electrolyte layer 17, and the positive electrode active material layer 15 are disposed on both surfaces of the positive electrode current collector 12. It has a configuration in which a positive electrode is laminated. Specifically, the negative electrode, the electrolyte layer, and the positive electrode are stacked in this order so that one negative electrode active material layer 13 and the positive electrode active material layer 15 adjacent thereto face each other with the electrolyte layer 17 therebetween. .

  Thereby, the adjacent negative electrode, electrolyte layer, and positive electrode constitute one unit cell layer 19. Therefore, it can be said that the stacked battery 10 has a configuration in which a plurality of single battery layers 19 are stacked and electrically connected in parallel. In addition, although the negative electrode active material layer 13 is arrange | positioned only in the single side | surface at all the outermost layer negative electrode collectors located in both outermost layers of the electric power generation element 21, an active material layer may be provided in both surfaces. That is, instead of using a current collector dedicated to the outermost layer provided with an active material layer only on one side, a current collector having an active material layer on both sides may be used as it is as an outermost current collector. Further, the arrangement of the positive electrode and the negative electrode is reversed from that in FIG. 1 so that the outermost positive electrode current collector is positioned on both outermost layers of the power generation element 21, and the outermost positive electrode current collector is disposed on one or both surfaces of the outermost layer positive electrode current collector. A positive electrode active material layer may be disposed.

  The negative electrode current collector 11 and the positive electrode current collector 12 are each provided with a negative electrode tab 25 and a positive electrode tab 27 that are electrically connected to the respective electrodes (negative electrode and positive electrode), and are sandwiched between end portions of the laminate sheet 29. 29 has a structure derived to the outside. The negative electrode tab 25 and the positive electrode tab 27 are ultrasonic welded or resistance welded to the negative electrode current collector 11 and the positive electrode current collector 12 of each electrode, respectively, via a negative electrode lead and a positive electrode lead (not shown) as necessary. May be attached.

  Further, from the viewpoint of recycling and reuse, the stacked (flat) battery 10 is not a disassembled but is a disassembled or semi-disassembled electrode (current collector + electrode) rather than a wound (cylindrical) battery. This is advantageous in that the active material layer) can be handled relatively easily.

  The members constituting the LIB that can be reproduced and reused are not particularly limited, and conventionally known members can be used. Hereinafter, each member will be described.

(A) Current collector The positive and negative electrode current collectors 12 and 11 are made of a conductive material. The sizes of the positive and negative electrode current collectors 12 and 11 are determined according to the intended use of the LIB. For example, if it is used for a large LIB that requires a high energy density, a current collector having a large area is used. The thickness of the positive and negative electrode current collectors 12 and 11 is not particularly limited. The thickness of the positive and negative electrode current collectors 12 and 11 is usually about 1 to 100 μm.

  There is no restriction | limiting in particular in the material which comprises the positive / negative electrode collectors 12 and 11. FIG. For example, a metal or a resin in which a conductive filler is added to a conductive polymer material or a non-conductive polymer material can be employed. Specifically, examples of the metal include aluminum, nickel, iron, stainless steel, titanium, and copper. In addition to these, a clad material of nickel and aluminum, a clad material of copper and aluminum, or a plating material of a combination of these metals can be preferably used. Moreover, the foil by which aluminum is coat | covered on the metal surface may be sufficient. Of these, aluminum, stainless steel, and copper are preferable from the viewpoints of electronic conductivity and battery operating potential.

  Examples of the conductive polymer material include polyaniline, polypyrrole, polythiophene, polyacetylene, polyparaphenylene, polyphenylene vinylene, polyacrylonitrile, and polyoxadiazole. Since such a conductive polymer material has sufficient conductivity without adding a conductive filler, it is advantageous in terms of facilitating the manufacturing process or reducing the weight of the current collector.

  Non-conductive polymer materials include, for example, polyethylene, polypropylene, polyethylene terephthalate, polyether nitrile, polyimide, polyamideimide, polyamide, polytetrafluoroethylene, styrene-butadiene rubber, polyacrylonitrile, polymethyl acrylate, polymethyl methacrylate, Examples thereof include polyvinyl chloride, polyvinylidene fluoride, and polystyrene. Such a non-conductive polymer material may have excellent potential resistance or solvent resistance.

  A conductive filler may be added to the conductive polymer material or the non-conductive polymer material as necessary. In particular, when the resin used as the base material of the current collector is made of only a non-conductive polymer, a conductive filler is inevitably necessary to impart conductivity to the resin. The conductive filler can be used without particular limitation as long as it is a substance having conductivity. For example, metals, conductive carbon, etc. are mentioned as a material excellent in electroconductivity, electric potential resistance, or lithium ion barrier | blocking property. The metal is not particularly limited, but at least one metal selected from the group consisting of Ni, Ti, Al, Cu, Pt, Fe, Cr, Sn, Zn, In, Sb, and K, or these metals It is preferable to contain an alloy or metal oxide containing. The conductive carbon is not particularly limited, and examples thereof include acetylene black, vulcan, black pearl, carbon nanofiber, ketjen black, carbon nanotube, carbon nanohorn, carbon nanoballoon, and fullerene. The amount of the conductive filler added is not particularly limited as long as it can provide sufficient conductivity to the positive and negative electrode current collectors 12 and 11, and is generally about 5 to 35% by mass.

  Moreover, as a material of the outermost layer current collector, for example, a metal or a conductive polymer can be adopted. From the viewpoint of ease of taking out electricity, a metal material is preferably used. Specifically, metal materials, such as aluminum, nickel, iron, stainless steel, titanium, copper, are mentioned, for example. In addition to these, a clad material of nickel and aluminum, a clad material of copper and aluminum, or a plating material of a combination of these metals can be preferably used. Moreover, the foil by which aluminum is coat | covered on the metal surface may be sufficient. Of these, aluminum and copper are preferable from the viewpoints of electron conductivity and battery operating potential.

(B) Active material layer The positive and negative electrode active material layers 15 and 13 contain an active material, and further contain other additives as required.

The positive electrode active material layer 15 includes a positive electrode active material. Examples of the positive electrode active material include LiMn ₂ O ₄ , LiCoO ₂ , LiNiO ₂ , Li (Ni—Co—Mn) O ₂ , LiFePO _4, and a part of these transition metals substituted with other elements. Lithium-transition metal composite oxides, lithium-transition metal phosphate compounds, lithium-transition metal sulfate compounds, and the like. In some cases, two or more positive electrode active materials may be used in combination. Preferably, a lithium-transition metal composite oxide is used as the positive electrode active material from the viewpoint of capacity and output characteristics. Of course, positive electrode active materials other than those described above may be used.

The negative electrode active material layer 13 includes a negative electrode active material. Examples of the negative electrode active material include natural graphite, MCMB (mesophase carbon microbead) type graphite, carbon materials such as graphite, soft carbon, and hard carbon, and lithium-transition metal composite oxide (for example, Li ₄ Ti ₅ O ₁₂ ). , Si, Ge, Sn, Pb, Al, In, Zn, and the like materials that form an alloy with lithium, lithium alloy negative electrode materials, and the like. In some cases, two or more negative electrode active materials may be used in combination. Preferably, from the viewpoint of capacity and output characteristics, a carbon material, a lithium-transition metal composite oxide, or a material alloyed with lithium is used as the negative electrode active material. Of course, negative electrode active materials other than those described above may be used.

  The average particle diameter of each of the active materials contained in the positive and negative electrode active material layers 15 and 13 is not particularly limited and may be about 0.1 to 100 μm, but preferably 1 to 20 μm from the viewpoint of high output. is there.

  The positive electrode active material layer 15 and the negative electrode active material layer 13 include a binder.

  Although it does not specifically limit as a binder used for the positive / negative electrode active material layers 15 and 13, For example, the following materials are mentioned. Polyethylene, polypropylene, polyethylene terephthalate, polyether nitrile, polyacrylonitrile, polyimide, polyamide, cellulose, carboxymethyl cellulose, ethylene-vinyl acetate copolymer, polyvinyl chloride, styrene / butadiene rubber, isoprene rubber, butadiene rubber, ethylene / propylene rubber , Thermoplastic polymers such as ethylene / propylene / diene copolymers, styrene / butadiene / styrene block copolymers and their hydrogenated products, styrene / isoprene / styrene block copolymers and their hydrogenated products, polyvinylidene fluoride ( PVdF), polytetrafluoroethylene, tetrafluoroethylene / hexafluoropropylene copolymer, tetrafluoroethylene / perfluoroalkyl vinyl ether Copolymers, ethylene / tetrafluoroethylene copolymers, polychlorotrifluoroethylene, ethylene / chlorotrifluoroethylene copolymers, fluororesins such as polyvinyl fluoride, vinylidene fluoride-hexafluoropropylene fluororubber, vinylidene fluoride Ride-hexafluoropropylene-tetrafluoroethylene-based fluororubber, vinylidene fluoride-based fluororubber, epoxy resin and the like. Among these, polyvinylidene fluoride, polyimide, styrene / butadiene rubber, carboxymethyl cellulose, polypropylene, polytetrafluoroethylene, polyacrylonitrile, and polyamide are more preferable. These suitable binders are excellent in heat resistance, have a very wide potential window, are stable at both the positive electrode potential and the negative electrode potential, and can be used for the active material layer. These binders may be used alone or in combination of two.

  The amount of the binder contained in the positive and negative electrode active material layers 15 and 13 is not particularly limited as long as it is an amount capable of binding the active material, but preferably 0.5% with respect to the active material layer. It is -15 mass%, More preferably, it is 1-10 mass%.

  Examples of other additives that can be included in the positive and negative electrode active material layers 15 and 13 include a conductive additive, an electrolyte salt (lithium salt), and an ion conductive polymer.

  The conductive assistant refers to an additive that is blended in order to improve the conductivity of the positive electrode active material layer 15 and the negative electrode active material layer 13. Examples of the conductive assistant include carbon materials such as carbon black such as acetylene black, graphite, and vapor grown carbon fiber. When the active material layer contains a conductive additive, an electronic network inside the active material layer is effectively formed, which can contribute to improvement of the output characteristics of the battery.

Examples of the electrolyte salt (lithium salt) include Li (C ₂ F ₅ SO ₂ ) ₂ N, LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , and LiBETI.

  Examples of the ion conductive polymer include polyethylene oxide (PEO) -based and polypropylene oxide (PPO) -based polymers.

  The compounding ratio of the components contained in the positive electrode active material layer and the negative electrode active material layer is not particularly limited. The blending ratio can be adjusted by appropriately referring to known knowledge about lithium ion batteries. The thickness of each active material layer is not particularly limited, and conventionally known knowledge about the battery can be appropriately referred to. For example, the thickness of each active material layer is about 2 to 100 μm.

(C) Electrolyte layer (electrolyte impregnated separator)
As the electrolyte constituting the electrolyte layer 17, an electrolytic solution (liquid electrolyte) can be used.

  The liquid electrolyte has a form in which a lithium salt as a supporting salt is dissolved in an organic solvent as a plasticizer. Examples of the organic solvent that can be used as the plasticizer include carbonates such as ethylene carbonate (EC), propylene carbonate, and diethyl carbonate (DEC). Further, as the supporting salt (lithium salt), a compound that can be added to the active material layer of the electrode, such as LiBETI, can be similarly employed.

  In addition, as a specific form of the separator 16 which comprises the electrolyte layer 17, the microporous film which consists of polyolefin, such as polyethylene and a polypropylene, is mentioned, for example. Moreover, a nonwoven fabric separator etc. can also be used. Furthermore, a separator provided with a heat-resistant layer made of an organic resin or inorganic particles on the surface can also be used.

(D) Electrode tabs and leads Electrode tabs 27 and 25 may be used for the purpose of taking out current outside the battery. The electrode tab is electrically connected to a current collector or a current collector plate, and is taken out of the laminate sheet which is a battery exterior material.

  The material which comprises an electrode tab is not restrict | limited in particular, The well-known highly electroconductive material conventionally used as an electrode tab for LIB may be used. As a constituent material of the electrode tab, for example, metal materials such as aluminum, copper, titanium, nickel, stainless steel, and alloys thereof are preferable, and aluminum, copper, and the like are more preferable from the viewpoint of light weight, corrosion resistance, and high conductivity. . Note that the same material may be used for the positive electrode tab 27 and the negative electrode tab 25, or different materials may be used.

  A positive terminal lead and a negative terminal lead (both not shown) are also used as necessary. As the material of the positive terminal lead and the negative terminal lead, a terminal lead used in a known LIB can be used. It should be noted that the part taken out from the battery outer packaging material 29 has a heat insulating property so as not to affect the product (for example, automobile parts, particularly electronic devices) by contacting with peripheral devices or wiring and causing leakage. It is preferable to coat with a heat shrinkable tube or the like.

(E) Battery exterior material As the battery exterior material 29, a well-known metal can case can be used, and a bag-like case using a laminate film containing aluminum that can cover the power generation element can be used. For example, a laminate film having a three-layer structure in which PP, aluminum, and nylon are laminated in this order can be used as the laminate film, but the laminate film is not limited thereto. A laminate film is desirable from the viewpoint that it is excellent in high output and cooling performance, and can be suitably used for a battery for large equipment for EV and HEV.

(2) Appearance of Battery FIG. 2 schematically shows the appearance of a laminated flat lithium ion battery that can be recycled as a used LIB that can be applied to any of the following embodiments. It is a perspective view. As shown in FIG. 2, the regenerative and reusable stacked battery 10 has a rectangular flat shape, and a negative electrode tab 25 and a positive electrode tab 27 for taking out electric power from both sides thereof. Has been pulled out. The power generation element 21 is wrapped by an outer package 29 of the battery 10 and the periphery thereof is heat-sealed. The power generation element 21 is sealed with the negative electrode tab 25 and the positive electrode tab 27 pulled out. Here, the power generation element 21 corresponds to the power generation element 21 of the stacked battery 10 shown in FIG. 1, and a plurality of unit cell layers 19 including the negative electrode active material layer 13, the electrolyte layer 17, and the positive electrode active material layer 15 are stacked. It has been done.

  The recyclable / reusable LIB is not limited to a flat shape (stacked type) as shown in FIGS. For example, the wound type LIB may have a cylindrical shape, or may be a flattened rectangular shape by deforming such a cylindrical shape. In the cylindrical shape, a laminate sheet or a conventional cylindrical can (metal can) may be used as the exterior material, and there is no particular limitation. Preferably, the power generation element (battery element) is covered with an aluminum laminate film. With this configuration, weight reduction and the application of the electrode regeneration method of the present embodiment are easy.

  Further, the extraction of the electrode tabs 25 and 27 shown in FIG. 2 is not particularly limited, and the negative electrode tab 25 and the positive electrode tab 27 may be pulled out from the same side, or a plurality of the negative electrode tab 25 and the positive electrode tab 27 may be provided. You may make it take out from each edge. Further, in a wound LIB, instead of the electrode tab, for example, a terminal may be formed using a cylindrical can (metal can).

  The recyclable / reusable LIB can be a used battery suitably used for a power source for driving a vehicle and an auxiliary power source of an electric vehicle, a hybrid electric vehicle, a fuel cell vehicle, and a hybrid fuel cell vehicle.

(3) Assembled battery An assembled battery is configured by connecting a plurality of the lithium ion secondary batteries. Specifically, at least two or more are used, and are configured by serialization, parallelization, or both. Capacitance and voltage can be freely adjusted by paralleling in series.

  The assembled battery forms a small assembled battery in which a plurality of lithium ion secondary batteries are connected in series or in parallel to be detachable. By connecting a plurality of these detachable battery packs in series or in parallel, a large capacity and high output suitable for vehicle drive power supplies and auxiliary power supplies that require high volume energy density and high volume output density. An assembled battery can also be formed. The small assembled batteries that can be attached and detached are connected to each other using an electrical connection means such as a bus bar, and the assembled batteries are stacked in a plurality of stages using a connection jig. How many lithium-ion batteries are connected to make an assembled battery and how many stages of assembled batteries are stacked to make an assembled battery depends on the battery capacity and output of the vehicle (electric vehicle) installed. You can decide accordingly.

(4) Vehicle A vehicle is equipped with the lithium ion battery or an assembled battery formed by combining a plurality of these. Since a long-life battery excellent in long-term reliability and output characteristics can be configured, it is possible to configure a plug-in hybrid electric vehicle having a long EV mileage and an electric vehicle having a long charge mileage when such a battery is mounted. In other words, a lithium ion battery or an assembled battery obtained by combining a plurality of these batteries can be used as a power source for driving a vehicle. Lithium-ion batteries or battery packs that combine them include, for example, hybrid vehicles, fuel cell vehicles, electric vehicles (all four-wheeled vehicles (passenger cars, trucks, buses and other commercial vehicles, light vehicles, etc.), two-wheeled vehicles ( (Including motorcycles) and tricycles). This is because the vehicle has a long life and high reliability. However, the application is not limited to automobiles. For example, it can be applied to various power sources for moving vehicles such as other vehicles, for example, trains, and power sources for mounting such as uninterruptible power supplies. It is also possible to use as.

  In order to mount the assembled battery on a vehicle such as an electric vehicle, it is mounted under the seat at the center of the body of the electric vehicle. This is because if it is installed under the seat, the interior space and the trunk room can be widened. The place where the assembled battery is mounted is not limited to the position under the seat, but may be a lower part of the rear trunk room or an area called an engine room in front of the vehicle. An electric vehicle using the assembled battery as described above has high durability and can provide a sufficient output even when used for a long time. Furthermore, it is possible to provide electric vehicles and hybrid vehicles that are excellent in fuel efficiency and running performance.

  Hereinafter, typical embodiments will be described in detail with reference to the drawings.

[II] First embodiment (overall embodiment)
In the first embodiment, for a used LIB, (1) a step of treating at least one of the positive and negative electrodes of the battery with a polar solvent, (2) a step of drying the solvent-treated electrode, (3) the step An LIB electrode regeneration method including a step of re-injecting a battery having a dry electrode.

  FIG. 3 shows a state in which used electrodes are treated with a polar solvent, dried and re-injected into a recyclable / reusable electrode (battery) for the LIB electrode regeneration method of the present embodiment. It is drawing which represented (image thru | or concept) typically.

  In the electrode regeneration method of the present embodiment, first, when a usable remaining capacity remains with respect to a used LIB whose resistance has been increased, it is desirable that the remaining capacity be sufficiently discharged and rendered harmless. This is because when there is a remaining capacity remaining in the used LIB, there is a risk of self-discharge during the regeneration, and therefore, the electrode tabs 25 and 27 are used until there is no remaining capacity remaining. It is necessary to fully discharge through (see FIGS. 1 and 2). Specifically, it is desirable that the discharged LIB is sufficiently discharged by 1C discharge until the discharge voltage of the used LIB becomes 2.5 V (or less). In other words, detoxification as used herein refers to reduction to 2.5 V (or less) per unit cell by 1 C discharge. However, when there is no remaining usable capacity for the used LIB with increased resistance, the steps (1) to (described later) are performed without performing the above-described discharge treatment (detoxification treatment). 3) may be performed. By this electrode regeneration method, deposits (SEI) can be removed almost completely, and the battery capacity can be restored to 60% or more, preferably 70% or more, more preferably about 70 to 95%. (See Examples 1-14).

  In addition, LIB has a characteristic that the usable discharge capacity gradually decreases as charging and discharging are repeated (the use period becomes longer). For this reason, it is difficult to uniquely define whether or not the LIB is a used LIB with increased resistance because it varies depending on the intended use and the user. In the present embodiment, it is assumed that the discharge capacity that can be used after charging (full charge) to at least the specified voltage is less than half of the new initial discharge capacity, but the user also feels inconvenience. Thus, all LIBs determined to be used (discarded) can be targeted. By the way, as a guideline of used on the supplier side, as can be seen from Examples 1 to 14, those that are 50% or less of the initial discharge capacity (44% in the example) can be the target (user side) It can also be an indication of when to replace the battery).

Step (1) After the used LIB is fully discharged and rendered harmless as necessary, as the step (1), at least one of the positive and negative electrodes of the used battery (simply referred to as a used electrode) is used. The process of processing with a polar solvent is performed.

  Specifically, as shown in FIG. 3, each used electrode 1 a is composed of a current collector 2 and an electrode active material layer 3 formed on the current collector 2. The electrode active material layer 3 is formed of a plurality of active material particles 4 whose surface is covered with a deposit (SEI) 5, and further, a binder and a conductive aid (both not shown).

  In this step, the used electrode 1a is treated with a polar solvent to form a solvent-treated electrode 1b. Specifically, the used electrode 1a is dissolved in the electrolyte 5 and the deposit 5 adhering to the surface of the active material particles of the electrode using a polar solvent (not shown), and then rinsed again with a fresh polar solvent ( Wash). By treating with the polar solvent in this manner, the deposit 5 is peeled off from the surface of each active material particle 4 in the used electrode 1a which is first immersed in the polar solvent for a predetermined time (for example, 30 to 60 minutes). The electrolytic solution and the deposit 5 are dissolved. The polar solvent in which the electrolytic solution and the deposit 5 are dissolved may be removed from the system, but it is desirable to recover and recycle / reuse them. Thereafter, the electrode 1a is rinsed again with a fresh polar solvent, so that the electrolyte solution and the deposit 5 slightly remaining together with the polar solvent are almost completely washed away (washed off), and are removed from the electrode 1a and removed. It can be set as the process electrode 1b.

  Here, deposits adhering to the surface of the active material particles of the electrode, specifically, deteriorated substances including Li, such as deposited Li organic salts, which are the main components of capacity deterioration, are simply named as SEI (Solid Electrolyte Interface). Also called. This SEI is said to be made by: That is, during repeated use of LIB charge / discharge, Li ions are repeatedly inserted and desorbed (or alloyed / dealloyed) between the electrode (positive electrode / negative electrode) active material and the electrolytic solution. At that time, the electrolytic solution (organic solvent + lithium salt) is partially reduced and decomposed. The organic compound derived from the solvent such as the decomposition product of the reduced organic solvent and the composite such as Li and positive electrode ions form a film that allows Li ions to pass but not electrons to pass through the surface of the active material particles of the electrode. Is. In this embodiment, the SEI is found to be specifically dissolved in a polar solvent having a dielectric constant of 5.0 or more, and the used electrode is pulverized by utilizing the excellent cleaning effect of the polar solvent. Without knowing, a reproducible method was obtained. Compare Examples 1-14 with Comparative Examples 1-4. In addition to so-called SEI, there is a possibility that deposits of salts such as LiF may be generated depending on the cell constituent components. However, since these salts are also washed with a polar solvent, the effect is the same. Hereinafter, in the present embodiment, the deposit is described as being representative of SEI.

  In this step (1), it is desirable to perform ultrasonic treatment when treating with a polar solvent. This is because when the used electrode is soaked in a polar solvent and treated, the inside of the electrode active material layer can be well washed by ultrasonic treatment by performing ultrasonic treatment. That is, the cleaning solvent (polar solvent) can permeate the electrode active material layer evenly and can be cleaned. For this reason, even the electrolyte solution inside the electrode active material layer and the SEI on the surface of the electrode (active material particles) can be uniformly dissolved in a polar solvent and removed. Cleaning by ultrasonic treatment is desirably 10 minutes or more and 60 minutes or less. If the cleaning time by ultrasonic treatment is 10 minutes or more, it is excellent in that it can be permeated evenly and the inside of the electrode active material layer can be washed well (electrolytic solution and deposits are removed). On the other hand, if the cleaning time by the ultrasonic treatment is within 60 minutes, the heat is not increased by the ultrasonic wave and the electrode active material layer is not damaged, and the active material layer is not peeled off by vibration, which is effective. This is excellent in that the inside of the electrode active material layer can be well washed (electrolytic solution and deposits are removed). The ultrasonic wave (frequency) may be appropriately adjusted depending on the degree of electrode contamination (particularly the degree of SEI adhesion on the surface of the electrode (active material particles)). Usually, it is sufficient to use a frequency around 40 KHz (applied in Example 12), but for stubborn dirt, it is effective to lower the frequency and remove it with the force of cavitation, and use a frequency around 28 kHz. Is good. Further, it is effective to remove the delicate dirt by increasing the frequency and reducing the cleaning unevenness, and it is preferable to use a frequency of 100 kHz or more. It is desirable to appropriately determine the optimum ultrasonic wave (frequency), for example, by conducting a preliminary experiment in advance.

  Here, the used electrode refers to at least one of positive and negative electrodes of a used stacked battery (see FIGS. 1 and 2).

  Further, the “polar solvent” in the present embodiment refers to a solvent having a dielectric constant of 5.0 or more.

  Although it does not restrict | limit especially as said polar solvent, For example, water, methanol, ethanol, n-propanol, isopropanol, 1-butanol, 2-butanol, formic acid, acetic acid, propionic acid, ethylene glycol, propylene glycol, etc. Protic polar solvents; aprotic polar solvents such as diethyl ether, ethyl acetate, tetrahydrofuran, pyridine, dimethyl sulfoxide, acetonitrile, cyclohexanone, acetone, methyl ethyl ketone, 1,4-dioxane, 1,3-dioxolane, ethylene glycol dimethyl ether A polar solvent or the like can be used. However, it is not limited to these polar solvents. Moreover, the polar solvent illustrated above may be used individually by 1 type, and may use 2 or more types together. When the positive and negative electrodes are treated (washed) simultaneously, it is desirable to use a polar solvent other than water. In addition, when the positive electrode is treated (washed), it is desirable to use an aprotic polar solvent. On the other hand, when the negative electrode is treated (washed), it is desirable to use a protic polar solvent.

Step (2) Next, as step (2), a step of drying the solvent-treated electrode is performed.

  The drying may be performed under the same conditions as drying the current collector coated with the electrode slurry in the process of manufacturing the electrode when manufacturing the battery, but the method is not limited thereto. For example, as shown in FIG. 3, the solvent-treated electrode 1b can be dried under appropriate drying conditions to form a dry electrode (not shown). As drying conditions for the above (a), drying may be performed at 60 to 150 ° C. for 5 to 24 hours at 0.1 atm or less in a vacuum dryer. However, it is not limited to the drying condition (a) above, and even if it is outside the range of the drying condition, there is no limitation as long as it does not impair the effects of the present embodiment. . When returning the pressure reduction, it is desirable to use dry air or argon gas in a dry box. Alternatively, (b) the solvent-treated electrode 1b can be dried in a dry box using dry air (dry air) or Ar gas under suitable drying conditions to obtain a dry electrode. The drying condition (b) may be drying at 60 to 150 ° C. for 3 to 24 hours under atmospheric pressure. However, it is not limited to the drying condition (b) above, and even if it is outside the range of the drying condition, there is no limitation as long as it does not impair the effects of the present embodiment. . If the pressure in the vacuum dryer at the time of drying (a) is 0.1 atm or less, the pressure can be sufficiently reduced (vacuum), so that the vaporized solvent can be removed under reduced pressure without liquefaction again. It is excellent in that it can be sufficiently dried in a short time. Even when dry air or Ar gas is used in the dry box at the time of drying (b) above, the evaporated solvent can be removed outside the dry box without being liquefied again, and the inside of the electrode can be sufficiently dried in a short time. Excellent in that it can be done. When the drying temperature of the above (a) and (b) is 60 ° C. or higher, the organic solvent can be quickly evaporated, and the inside of the electrode can be sufficiently dried in a short time. A drying temperature of 150 ° C. or lower is excellent in that the drying rate can be increased without causing deterioration of the electrode active material or the like. Moreover, if the drying time of said (a) (b) is 3 hours or more, it can fully dry to the inside of an electrode, without leaving an organic solvent. If the drying time is 24 hours or less, it is excellent in that the inside of the electrode can be sufficiently dried and the drying cost can be suppressed. However, in the present embodiment, the drying method is not limited at all. Drying by vacuum heating using the above-described vacuum dryer does not leave a polar solvent inside the solvent-treated electrode 1b, and can be uniformly heated to the inside of the electrode active material layer, and more uniformly. It is excellent in that it can be dried.

Step (3) Subsequently, as step (3), a step of re-injecting the liquid having the dry electrode is performed.

  Specifically, in this step, the electrolyte solution is re-injected into the reassembled battery using the dry electrode and further using the required battery components as in the case of a new battery. Thus, a battery having a recyclable / reusable electrode 1c is obtained. As a result, a battery having an electrode 1c that can be recycled and reused without reducing the deteriorated electrode 1a to the raw material can be obtained.

  The effects of the first embodiment are as follows.

  According to the first embodiment, a deposit (SEI) that is a main component of capacity deterioration attached to the surface of at least one of the positive and negative electrodes (active material particles) of the used LIB is treated with a polar solvent (cleaning, The electrode can be regenerated as it is.

  Therefore, the electrode (particularly the active material layer) is not destroyed, and no strong acid or strong alkali is used. Therefore, solid waste is not generated or can be greatly reduced. Can do.

  In addition, since the electrode can be regenerated as it is, the electrode can be regenerated to a LIB having the same shape and the same purpose, which is excellent in that it has a simple recyclability.

  Furthermore, if the electrode is washed as it is (treatment with a polar solvent), dried, and re-injected, it is also excellent in that the capacity and output can be restored to the same level as the initial stage of a new battery.

[III] Second Embodiment In the second embodiment, (1) a step of treating positive and negative electrodes taken out from a used LIB with a polar solvent, (2) a step of drying the solvent-treated electrode, (3) A method of regenerating an LIB electrode, comprising re-injecting a battery that is reassembled using the dry electrode.

  FIG. 4 is a diagram showing an outline of each process of the second embodiment.

  Also in the electrode regeneration method of the present embodiment, first, when a usable remaining capacity remains with respect to a used LIB whose resistance has been increased, the remaining capacity is sufficiently discharged through the electrode tabs 25 and 27 to be harmless. It is desirable to This is the same as described in the first embodiment. Therefore, the description here is omitted.

  The determination as to whether the LIB 10 has been used is also the same as described in the first embodiment. Therefore, the description here is omitted.

Step (1) Next, the used LIB is fully discharged and rendered harmless as necessary, and then, as the step (1), the positive and negative electrodes taken out from the used LIB are treated with a polar solvent. I do.

  Specifically, the outer periphery of the exterior material such as a laminate type is cut from the used LIB so as not to damage the electrode (electrode active material layer + current collector; hereinafter also including the electrode tab) in the glove box. Alternatively, it is peeled off by heat melting, semi-disassembled and divided into positive and negative electrodes. Specifically, as shown in FIG. 4, the used LIB is peeled off by cutting or heat-melting the outer periphery of a laminate type or the like so as not to damage the electrodes in the glove box, 6a was taken out. The extracted power generation element 6a has a configuration in which a plurality of positive electrodes, electrolyte layers (electrolyte impregnated separators), and negative electrodes are stacked. Therefore, the positive electrode, the electrolyte layer (electrolyte-impregnated separator), and the negative electrode are peeled off one by one from the power generation element 6a, and separated into the positive electrode 7a and the negative electrode 8a, respectively. The electrolyte layer (electrolyte impregnated separator) is preferably used for recycling and reuse, but may be disposed of in consideration of the recycling cost.

  Each electrode separately divided into the used positive electrode 7a and the negative electrode 8a is processed with a polar solvent to obtain a solvent-treated electrode. Specifically, after each of the electrodes separately divided into the used positive electrode 7a and negative electrode 8a is dissolved in an electrolyte and a deposit (SEI) using a polar solvent (not shown), again with a fresh polar solvent. Rinse (wash). By treating with the polar solvent in this way, the deposit (SEI) is peeled off from the surfaces of the active material particles in the used electrodes 7a and 8a which are first immersed in the polar solvent for a predetermined time (for example, 30 to 60 minutes). The electrolyte and deposit (SEI) are dissolved in the solvent. The polar solvent in which the electrolytic solution and the deposit (SEI) are dissolved may be removed from the system, but it is desirable that these are also recovered, recycled and reused. Thereafter, the electrodes 7a and 8a are again rinsed with a fresh polar solvent, so that the electrolyte solution and the deposit (SEI) slightly remaining together with the polar solvent are almost completely washed away (washed off). It can remove from 8a and can be set as the solvent processing electrodes 7b and 8b.

  Even in the step (1) of the present embodiment, it is desirable to perform ultrasonic treatment (frequency 15 to 400 kHz) when treating with a polar solvent. This is because when the used electrode is immersed in a polar solvent for treatment, the inside of the electrode active material layer can be well washed by ultrasonic treatment by performing ultrasonic treatment. That is, the cleaning solvent (polar solvent) can permeate the electrode active material layer evenly and can be cleaned. For this reason, even the electrolyte solution inside the electrode active material layer and the SEI on the surface of the electrode (active material particles) can be uniformly dissolved in a polar solvent and removed. Cleaning by ultrasonic treatment is desirably 10 minutes or more and 60 minutes or less. If the cleaning time by ultrasonic treatment is 10 minutes or more, it is excellent in that it can be permeated evenly and the inside of the electrode active material layer can be washed well (electrolytic solution and deposits are removed). On the other hand, if the cleaning time by the ultrasonic treatment is within 60 minutes, the heat is not increased by the ultrasonic wave and the electrode active material layer is not damaged, and the active material layer is not peeled off by vibration, which is effective. This is excellent in that the inside of the electrode active material layer can be well washed (electrolytic solution and deposits are removed). The ultrasonic wave (frequency) may be appropriately adjusted depending on the degree of electrode contamination (particularly the degree of SEI adhesion on the surface of the electrode (active material particles)). Usually, it is sufficient to use a frequency around 40 KHz (applied in Example 12), but for stubborn dirt, it is effective to lower the frequency and remove it with the force of cavitation, and use a frequency around 28 kHz. Is good. Further, it is effective to remove the delicate dirt by increasing the frequency and reducing the cleaning unevenness, and it is preferable to use a frequency of 100 kHz or more. It is desirable to appropriately determine the optimum ultrasonic wave (frequency), for example, by conducting a preliminary experiment in advance.

  Here, the used electrode means that the power generation element is taken out from the outer packaging material of the used stacked battery (see FIGS. 1 and 2) and peeled off in this order: positive electrode, electrolyte layer (electrolyte impregnated separator), negative electrode,. It refers to both the positive electrode and the negative electrode other than the recovered electrolyte layer (electrolyte impregnated separator).

  Further, the “polar solvent” in the present embodiment refers to a solvent having a dielectric constant of 5.0 or more.

Preferably, the polarity of the polar solvent used for electrode treatment (washing) is expressed by the following inequality:
(Polarity of polar solvent used for treatment of positive electrode) ≦ (Polarity of polar solvent used for treatment of negative electrode)
The one represented by is desirable.

In other words,
(Dielectric constant of polar solvent used for treatment of positive electrode) ≦ (dielectric constant of polar solvent used for treatment of negative electrode)
It is represented by

  This is because, for the treatment (cleaning) of the positive electrode, water having a relatively high solvent polarity is not desirable depending on the type of active material, and therefore ether or acetone having a relatively low solvent polarity is desirable. In other words, the positive electrode can be sufficiently washed with an ether or acetone having a relatively low polarity of the solvent for the deterioration (deposit) containing Li adhering to the positive electrode active material layer. On the other hand, for the negative electrode, water having a relatively high solvent polarity is most effective, but alcohol may be used. In other words, since the negative electrode has a lot of deposits, it is easy to wash it with water having a relatively high polarity of the solvent. The comparison of the polarity of the solvent is judged by the level (value) of the dielectric constant of the solvent.

  The polar solvent is not particularly limited. For example, protic polar solvents such as water, methanol, ethanol, n-propanol, isopropanol, 1-butanol, 2-butanol, formic acid, acetic acid, propionic acid, ethylene glycol, propylene glycol; diethyl ether, ethyl acetate, tetrahydrofuran, Aprotic polar solvents such as pyridine, dimethyl sulfoxide, acetonitrile, cyclohexanone, acetone, methyl ethyl ketone, 1,4-dioxane, 1,3-dioxolane, and ethylene glycol dimethyl ether can be used. However, it is not limited to these polar solvents. Moreover, the polar solvent illustrated above may be used individually by 1 type, and may use 2 or more types together.

The solvent used for the treatment (cleaning) of the positive electrode is preferably an aprotic polar solvent. This is because some positive electrodes (for example, Ni-rich positive electrodes) release Li ⁺ from the surface by H ⁺ , and thus aprotic polar solvents such as ether and acetone are preferable. This is because the surface of the positive electrode (positive electrode active material layer) can be washed without hurting with H ⁺ by using ether or acetone which is an aprotic polar solvent for the treatment (washing) of the positive electrode. Examples of such aprotic polar solvents include, for example, diethyl ether, ethyl acetate, tetrahydrofuran, pyridine, dimethyl sulfoxide, acetonitrile, cyclohexanone, acetone, methyl ethyl ketone, 1,4-dioxane, 1,3-dioxolane. And ethylene glycol dimethyl ether. The aprotic polar solvents described above may be used alone or in combination of two or more. However, the present embodiment is not limited to these.

  On the other hand, the solvent used for the treatment (cleaning) of the negative electrode is preferably a protic polar solvent. This is because the deposit on the negative electrode surface is mainly composed of an organic lithium salt, and the one with higher polarity dissolves more quickly. That is, the solvent used for the treatment (cleaning) of the negative electrode is not adversely affected even if it is an aprotic polar solvent as in the case of the positive electrode, but the protic polar solvent is superior in that the treatment process becomes faster. . Examples of such protic polar solvents include water, methanol, ethanol, n-propanol, isopropanol, 1-butanol, 2-butanol, formic acid, acetic acid, propionic acid, ethylene glycol, and propylene glycol. The above protic polar solvents may be used alone or in combination of two or more. Among the above-mentioned protic polar solvents, particularly when treated (washed) with water, deposits can be dissolved quickly, and water is suitable because it is inexpensive and has a low environmental impact. However, the present embodiment is not limited to these.

Step (2) Next, as step (2), a step of drying the solvent-treated electrode is performed.

  The drying may be performed under the same conditions as drying the current collector coated with the electrode slurry in the process of manufacturing the electrode when manufacturing the battery, but the method is not limited thereto. For example, as shown in FIG. 4, (a) the solvent-treated positive electrode 7b and the solvent-treated negative electrode 8b, which are solvent-treated electrodes, are dried under appropriate drying conditions to form dry electrodes (dry positive electrode 7c and dry negative electrode 8c). it can. As the drying conditions for the above (a), drying may be performed at 110 to 150 ° C. for 3 to 24 hours at 0.1 atm or less in a vacuum dryer. However, it is not limited to the drying condition (a) above, and even if it is outside the range of the drying condition, there is no limitation as long as it does not impair the effects of the present embodiment. . When returning to a reduced pressure, it is desirable to use dry air or Ar gas in a dry box. Alternatively, (b) the solvent-treated electrode 7b and the solvent-treated anode 8b, which are solvent-treated electrodes, can be dried under suitable drying conditions and dried to dry electrodes (dry cathode 7c and dried anode 8c). As the drying condition of (b) above, dry air (dry air) or Ar gas may be used in a dry box at 110 to 150 ° C. for 3 to 24 hours under atmospheric pressure. However, it is not limited to the drying condition (b) above, and even if it is outside the range of the drying condition, there is no limitation as long as it does not impair the effects of the present embodiment. . If the pressure in the vacuum dryer at the time of drying (a) is 0.1 atm or less, the pressure can be sufficiently reduced (vacuum), so that the vaporized solvent can be removed under reduced pressure without liquefaction again. It is excellent in that it can be sufficiently dried in a short time. Even when dry air or Ar gas is used in the dry box at the time of drying (b) above, the evaporated solvent can be removed outside the dry box without being liquefied again, and the inside of the electrode can be sufficiently dried in a short time. Excellent in that it can be done. When the drying temperature of the above (a) and (b) is 110 ° C. or higher, the organic solvent can be quickly evaporated, and the inside of the electrode can be sufficiently dried in a short time. A drying temperature of 150 ° C. or lower is excellent in that the drying rate can be increased without causing deterioration of the electrode active material or the like. Moreover, if the drying time of said (a) (b) is 3 hours or more, it can fully dry to the inside of an electrode, without leaving an organic solvent. If the drying time is 24 hours or less, it is excellent in that the inside of the electrode can be sufficiently dried and the drying cost can be suppressed. However, in the present embodiment, the drying method is not limited at all. Drying by vacuum heating using the above-described vacuum dryer allows the vacuum treatment state to be uniformly applied to the inside of the electrode active material layer without leaving a polar solvent inside the solvent-treated electrodes 7b and 8b. It is excellent in that it can be dried uniformly.

Step (3) Subsequently, as step (3), a step of re-injecting a battery that is reassembled using the dry electrode is performed.

  In this step (3), using the dry positive electrode 7c and the dry negative electrode 8c, which are the dry electrodes, and reassembling the battery using other battery components as necessary, the electrolyte solution is re-similar to a new battery. By injecting the liquid, a recyclable / reusable battery can be obtained. Specifically, the power generation element 6b is regenerated by reassembling the dry positive electrode 7c and the dry negative electrode 8c and using a plurality of unused separators. A battery that can be recycled and reused can be obtained by storing the power generation element 6b in an unused exterior member and re-injecting the electrolyte in the same manner as a new battery. Here, by re-injecting the liquid, the separator is impregnated with the electrolytic solution to form an electrolyte layer (it can be said that the power generation element 6c is completed at this point). As a result, a battery having recyclable / reusable electrodes 7c, 8c can be obtained without reducing the deteriorated electrodes 7a, 8a to the raw materials.

  In FIG. 4, a power generation element of a laminated battery, that is, a power generation element formed by laminating a plurality of rectangular positive electrodes, electrolyte layers (electrolyte impregnated separators), and negative electrodes is used as an exterior material. This is an example using a laminate type exterior material. However, the present embodiment is not limited to this. That is, even in a wound battery, a power generation element in which a positive electrode, an electrolyte layer (electrolyte impregnated separator), and a negative electrode are wound in a spiral shape (winding shape) may be used, and a cylindrical can may be used as an exterior material. Even in this case, the power generation element wound in a spiral shape (winding shape) is rolled up and divided into a positive electrode, an electrolyte layer (electrolyte impregnated separator), and a negative electrode. After that, as in FIG. 4, the electrode divided into the positive and negative electrodes is treated with a polar solvent, dried, reassembled with an unused separator (rewinded), stored in a cylindrical can, and re-injected by re-injection. A reusable battery can be obtained. As for the exterior material, a new product or a reused product may be used, or a laminate-type exterior material may be used instead of the cylindrical can.

  The operational effects of the second embodiment are as follows.

  The second embodiment is characterized in that the power generation element is taken out from the LIB, and the electrodes are peeled off once to be semi-disassembled.

  After that, the semi-disassembled positive electrode and negative electrode are washed with a polar solvent, and the deposit (SEI) which is the main component of capacity deterioration is washed away, sufficiently dried to evaporate the washing solvent, reassembled and re-injected. By doing so, it can be reused again as a battery (recycled battery).

  That is, the degradation product containing Li adhering to the semi-disassembled positive and negative electrode active material layers (particularly the active material particle surface as shown in FIG. 3) dissolves well in a polar solvent such as water. Can be washed out more easily.

  If the electrolyte solution is newly replenished after drying, it can operate sufficiently as a LIB (recycle battery) again.

  The conventional technical problem is solved by the operation (processing) as described above.

  According to the second embodiment, an inexpensive rechargeable battery with a low environmental load can be provided.

  In the second embodiment, the battery is semi-disassembled, the electrode (particularly, the electrode active material layer) is treated (cleaned), and reused as it is, so that recycling near the reuse type is possible.

  Further, since no strong acid or strong alkali is used and no solid waste is generated, the environmental load can be very low.

  Furthermore, it is possible to hold a capacity (initial discharge capacity in a regenerative battery) of 60% or more, preferably 70% or more, more preferably about 70 to 95% of the initial discharge capacity of a new battery (Example 1, 4-10).

[IV] Third Embodiment The third embodiment is (1) a step of treating one of the positive and negative electrodes taken out from the used LIB with a polar solvent, (2) a step of drying the solvent-treated electrode, (3 ) A method for regenerating an electrode of LIB including a step of re-injecting the dry electrode into a reassembled battery together with an unused counter electrode.

  FIG. 5 is a diagram showing an outline of each process of the third embodiment.

  Also in the electrode regeneration method of the present embodiment, first, when a usable remaining capacity remains with respect to a used LIB having an increased resistance, the electrode current collector plates 25 and 27 (see FIGS. 2 and 4) are used. It is desirable that the remaining capacity be sufficiently discharged and rendered harmless. This is the same as described in the first embodiment. Therefore, the description here is omitted.

  The determination as to whether the LIB 10 has been used is also the same as described in the first embodiment. Therefore, the description here is omitted.

Step (1) Next, the used LIB is fully discharged and rendered harmless as necessary, and then, as the step (1), one of the positive and negative electrodes taken out from the used LIB is used as a polar solvent. The process of processing is performed.

  Specifically, the outer periphery of the outer packaging material such as a laminate type is cut or used so that the used LIB does not damage the electrode (active material layer + current collector, hereinafter including the electrode tab) in the glove box. Heat melt and peel, half disassemble and separate into positive and negative electrodes. Specifically, as shown in FIG. 5, the used LIB is used by removing the outer periphery of a laminate type or other exterior material by cutting or heat-melting it so as not to damage the electrode in the glove box. The power generation element 6a was taken out. The extracted power generation element 6a has a configuration in which a plurality of positive electrodes, electrolyte layers (electrolyte impregnated separators), and negative electrodes are stacked. Therefore, the positive electrode, the electrolyte layer (electrolyte-impregnated separator), and the negative electrode are peeled off one by one from the power generation element 6a, and separated into the positive electrode 7a and the negative electrode 8a, respectively. The electrolyte layer (electrolyte impregnated separator) is preferably used for recycling and reuse, but may be disposed of in consideration of the recycling cost.

  Either one of the electrodes separately divided into the used positive electrode 7a and negative electrode 8a is treated with a polar solvent to form a solvent-treated electrode. Specifically, one of the electrodes separately divided into the positive electrode 7a and the negative electrode 8a (the example of the positive electrode 7a is shown in FIG. 5 but may be the negative electrode 8a) using a polar solvent (not shown) After the sediment (SEI) is dissolved, it is again rinsed (washed) with fresh polar solvent. By treating with the polar solvent in this way, the deposit (SEI) is peeled off from the surface of each active material particle in the used electrode 7a which is first immersed in the polar solvent for a predetermined time (for example, 30 to 60 minutes), and in the polar solvent. The electrolyte and deposit (SEI) are dissolved in The polar solvent in which the electrolytic solution and the deposit (SEI) are dissolved may be removed from the system, but it is desirable that these are also recovered, recycled and reused. Thereafter, the electrode 7a is rinsed again with a fresh polar solvent, so that the electrolyte solution and the deposit (SEI) slightly remaining together with the polar solvent are almost completely washed away (washed off) and removed from the electrode 7a. Thus, the solvent-treated electrode 7b can be obtained. One used negative electrode 8a may be treated as a solid waste together with the electrolyte layer (electrolyte impregnated separator). Preferably, the used negative electrode 8a is pulverized into a mineral such as an active material. It is desirable to recycle and reuse. The electrolyte layer (electrolyte impregnated separator) is also preferably pulverized and purified, and recycled and reused as a recycled separator or other recycled paper.

  Also in the step (1) of this embodiment, it is desirable to perform ultrasonic treatment when treating with a polar solvent. This is because when one of the used electrodes is immersed in a polar solvent for treatment, the inside of the electrode active material layer can be well washed by ultrasonic waves by performing ultrasonic treatment. That is, the cleaning solvent (polar solvent) can permeate the electrode active material layer evenly and can be cleaned. For this reason, even the electrolyte solution inside the electrode active material layer and the SEI on the surface of the electrode (active material particles) can be uniformly dissolved in a polar solvent and removed. Cleaning by ultrasonic treatment is desirably 10 minutes or more and 60 minutes or less. If the cleaning time by ultrasonic treatment is 10 minutes or more, it is excellent in that it can be permeated evenly and the inside of the electrode active material layer can be washed well (electrolytic solution and deposits are removed). On the other hand, if the cleaning time by the ultrasonic treatment is within 60 minutes, the heat is not increased by the ultrasonic wave and the electrode active material layer is not damaged, and the active material layer is not peeled off by vibration, which is effective. This is excellent in that the inside of the electrode active material layer can be well washed (electrolytic solution and deposits are removed). The ultrasonic wave (frequency) may be appropriately adjusted depending on the degree of electrode contamination (particularly the degree of SEI adhesion on the surface of the electrode (active material particles)). Usually, it is sufficient to use a frequency around 40 KHz (applied in Example 12), but for stubborn dirt, it is effective to lower the frequency and remove it with the force of cavitation, and use a frequency around 28 kHz. Is good. Further, it is effective to remove the delicate dirt by increasing the frequency and reducing the cleaning unevenness, and it is preferable to use a frequency of 100 kHz or more. It is desirable to appropriately determine the optimum ultrasonic wave (frequency), for example, by conducting a preliminary experiment in advance.

  Either one of the used electrodes refers to the electrolyte layer collected by removing the power generation element from the package material of the used stacked battery and peeling it off in the order of positive electrode, electrolyte layer (electrolyte impregnated separator), negative electrode,. It means any one of positive and negative electrodes other than (electrolyte impregnated separator).

  Further, the “polar solvent” in the present embodiment refers to a solvent having a dielectric constant of 5.0 or more.

Preferably, the polarity of the polar solvent used for electrode treatment (washing) is expressed by the following inequality:
(Polarity of polar solvent used for treatment of positive electrode) ≦ (Polarity of polar solvent used for treatment of negative electrode)
The one represented by is desirable.

In other words,
(Dielectric constant of polar solvent used for treatment of positive electrode) ≦ (dielectric constant of polar solvent used for treatment of negative electrode)
It is represented by

  This is because, for the treatment (cleaning) of the positive electrode, water having a relatively high solvent polarity is not desirable depending on the type of active material, and therefore ether or acetone having a relatively low solvent polarity is desirable. In other words, the positive electrode can be sufficiently washed with an ether or acetone having a relatively low polarity of the solvent for the deterioration (deposit) containing Li adhering to the positive electrode active material layer. On the other hand, for the negative electrode, water having a relatively high solvent polarity is most effective, but alcohol may be used. In other words, since the negative electrode has a lot of deposits, it is easy to wash it with water having a relatively high polarity of the solvent. The comparison of the polarity of the solvent is judged by the level (value) of the dielectric constant of the solvent.

  The polar solvent is not particularly limited. For example, protic polar solvents such as water, methanol, ethanol, n-propanol, isopropanol, 1-butanol, 2-butanol, formic acid, acetic acid, propionic acid, ethylene glycol, propylene glycol; diethyl ether, ethyl acetate, tetrahydrofuran, Aprotic polar solvents such as pyridine, dimethyl sulfoxide, acetonitrile, cyclohexanone, acetone, methyl ethyl ketone, 1,4-dioxane, 1,3-dioxolane, and ethylene glycol dimethyl ether can be used. However, it is not limited to these polar solvents. Moreover, the polar solvent illustrated above may be used individually by 1 type, and may use 2 or more types together.

The solvent used for treating (washing) the positive electrode is preferably an aprotic polar solvent. This is because some positive electrodes (for example, Ni-rich positive electrodes) release Li ⁺ from the surface by H ⁺ , and thus aprotic polar solvents such as ether and acetone are preferable. This is because the surface of the positive electrode (positive electrode active material layer) can be washed without hurting with H ⁺ by using ether or acetone which is an aprotic polar solvent for the treatment (washing) of the positive electrode. Examples of such aprotic polar solvents include, for example, diethyl ether, ethyl acetate, tetrahydrofuran, pyridine, dimethyl sulfoxide, acetonitrile, cyclohexanone, acetone, methyl ethyl ketone, 1,4-dioxane, 1,3-dioxolane. And ethylene glycol dimethyl ether. However, the present embodiment is not limited to these. The said aprotic polar solvent may be used individually by 1 type, and may use 2 or more types together.

  On the other hand, it is desirable that the solvent used when treating (washing) the negative electrode is a protic polar solvent. This is because the deposit on the negative electrode surface is mainly composed of an organic lithium salt, and the one with higher polarity dissolves more quickly. That is, the solvent used for the treatment (cleaning) of the negative electrode is not adversely affected even if it is an aprotic polar solvent as in the case of the positive electrode, but the protic polar solvent is superior in that the treatment process becomes faster. . Examples of such protic polar solvents include water, methanol, ethanol, n-propanol, isopropanol, 1-butanol, 2-butanol, formic acid, acetic acid, propionic acid, ethylene glycol, propylene glycol, and the like. . The said protic polar solvent may be used individually by 1 type, and may use 2 or more types together. Among the above-mentioned protic polar solvents, treatment (washing) with water is particularly preferable because the deposit can be dissolved quickly, and water is inexpensive and has a low environmental burden. However, the present embodiment is not limited to these.

Step (2) Next, as step (2), a step of drying the solvent-treated electrode is performed.

  The drying may be performed under the same conditions as drying the current collector coated with the electrode slurry in the process of manufacturing the electrode when manufacturing the battery, but the method is not limited thereto. For example, as shown in FIG. 5, (a) a solvent-treated positive electrode 7b that is a solvent-treated electrode, and an unused negative electrode 8d that is used for battery regeneration are dried under appropriate drying conditions to obtain a dry electrode (the dried positive electrode 7c and the dried electrode). The negative electrode 8e) can be obtained. As the drying conditions for the above (a), drying may be performed at 110 to 150 ° C. for 3 to 24 hours at 0.1 atm or less in a vacuum dryer. However, it is not limited to the drying condition (a) above, and even if it is outside the range of the drying condition, there is no limitation as long as it does not impair the effects of the present embodiment. . When returning to a reduced pressure, it is desirable to use dry air or Ar gas in a dry box. Alternatively, (b) the solvent-treated positive electrode 7b, which is a solvent-treated electrode, and the unused negative electrode 8d, which is an unused counter electrode, are dried in a dry box using dry air or Ar gas under appropriate drying conditions, and dried electrode (dried positive electrode) 7c and dry negative electrode 8e). The drying condition (b) may be drying at 110 to 150 ° C. for 3 to 24 hours under atmospheric pressure. However, it is not limited to the drying condition (b) above, and even if it is outside the range of the drying condition, there is no limitation as long as it does not impair the effects of the present embodiment. . If the pressure in the vacuum dryer at the time of drying (a) is 0.1 atm or less, the pressure can be sufficiently reduced (vacuum), so that the vaporized solvent can be removed under reduced pressure without liquefaction again. It is excellent in that it can be sufficiently dried in a short time. Even when dry air or Ar gas is used in the dry box at the time of drying (b) above, the evaporated solvent can be removed outside the dry box without being liquefied again, and the inside of the electrode is sufficiently dried in a short time. Excellent in that it can. When the drying temperature of the above (a) and (b) is 110 ° C. or higher, the organic solvent can be quickly evaporated, and the inside of the electrode can be sufficiently dried in a short time. A drying temperature of 150 ° C. or lower is excellent in that the drying rate can be increased without causing deterioration of the electrode active material or the like. Moreover, if the drying time of said (a) (b) is 3 hours or more, it can fully dry to the inside of an electrode, without leaving an organic solvent. If the drying time is 24 hours or less, it is excellent in that the inside of the electrode can be sufficiently dried and the drying cost can be suppressed. However, in the present embodiment, the drying method is not limited at all. Drying by vacuum heating using the above-described vacuum dryer does not leave the polar solvent inside the solvent-treated electrode 7b, and does not leave the solvent used during production inside the unused negative electrode 8d. The inside of the electrode active material layer can be uniformly heated in a vacuum. As a result, it is excellent in that it can be dried more uniformly.

Step (3) Subsequently, as the step (3), a step of re-injecting the dry electrode into a battery reassembled with an unused counter electrode is performed.

  In this step, as shown in FIG. 5, the electrolyte is re-injected into a battery reassembled with the dry positive electrode 7c, which is the dry electrode, and the dry electrode 8e, which is the unused negative electrode, in the same manner as a new battery. By refining, a recyclable / reusable battery can be obtained. Specifically, the power generation element 6c is regenerated by reusing the dry positive electrode 7c, a dry electrode 8e of an unused negative electrode, and a plurality of unused separators. A battery that can be recycled and reused can be obtained by storing the power generation element 6c in an unused exterior material and re-injecting the electrolyte in the same manner as a new battery. Here, by re-injecting the liquid, the separator is impregnated with the electrolytic solution to form an electrolyte layer (it can be said that the power generation element 6c is completed at this point). As a result, a battery having a recyclable / reusable electrode 7c without reducing the deteriorated electrode 7a to the raw material can be obtained. Note that the unused negative electrode 8d may be a battery reassembled with the dry positive electrode 7c without performing the above-described drying treatment. Preferably, as described above, the unused negative electrode 8d is dried to form the dry electrode 8e, and the dry electrode 8e is reassembled with the dry positive electrode 7c. This is because when the viscosity adjusting solvent at the time of manufacture remains or water vapor (moisture) in the air adheres to the unused negative electrode 8d, water vapor (moisture) in the ambient atmosphere gas adheres even during storage. May have. Therefore, by performing the drying treatment, it is possible to reliably remove the solvent and moisture that may affect the battery performance.

  The theoretical capacity of the unused counter electrode may be the same as the theoretical capacity of the counter electrode of a new battery. However, it may be adjusted in consideration of the initial discharge capacity of the regenerated electrode by conducting a preliminary experiment or the like in advance. As shown in Examples 2 and 3 of Table 1, the initial discharge capacity of the regenerated battery that depends on the capacity of the regenerated electrode is about 90 to 95% of the initial discharge capacity of the battery when it is new. it can. For this reason, the capacity of the unused counter electrode is also adjusted (reduced) according to the capacity of the regenerated electrode (= the initial discharge capacity of the regenerated battery), thereby optimizing the active material amount of the unused counter electrode and reducing the cost. It is excellent in that

  In FIG. 5, the power generation element of the stacked battery is used in accordance with the shape of the power generation element and the electrode, that is, the power generation element formed by laminating a plurality of rectangular positive electrodes, electrolyte layers (electrolyte impregnated separators), and negative electrodes. This is an example in which a laminate type exterior material is used as the material. However, this embodiment is not limited to this. That is, even in a wound battery, a power generation element in which a positive electrode, an electrolyte layer (electrolyte impregnated separator), and a negative electrode are wound in a spiral shape (winding shape) may be used, and a cylindrical can may be used as an exterior material. Even in this case, the power generation element wound in a spiral shape (winding shape) is rolled up and divided into a positive electrode, an electrolyte layer (electrolyte impregnated separator), and a negative electrode. After that, as in FIG. 5, one electrode is treated with a polar solvent, dried, reassembled (rewinded) with an unused counter electrode and an electrolyte layer (electrolyte impregnated separator), stored in a cylindrical can, and then reused. By injecting the solution, a recyclable battery can be obtained. As for the exterior material, a new product or a reused product may be used, or a laminate-type exterior material may be used instead of the cylindrical can.

  The operational effects of the third embodiment are as follows.

  In the third embodiment, the power generation element is taken out from the LIB, and the electrodes are peeled off once to be semi-disassembled. Further, one of the positive and negative electrodes is washed with a polar solvent, and the deposit which is the main component of capacity deterioration is washed away sufficiently. It is characterized in that it is dried to volatilize the washing solvent to obtain a regenerative electrode.

  Further, the regenerated electrode can be reused as a battery (regenerated battery) again by reassembling the regenerated electrode together with the unused counter electrode and reinjecting the liquid. The conventional technical problem is solved by such operation (processing).

  According to the third embodiment, an inexpensive rechargeable battery with a low environmental load can be provided.

  In the third embodiment, the battery is semi-disassembled, and the active material layer on one side of the positive and negative electrodes is treated (cleaned) and reused as it is, so that one of the positive and negative electrodes is combined with a regenerative electrode and a new counter electrode. This makes it possible to recycle near reuse.

  That is, in the third embodiment, it is not essential to regenerate and use both poles. If either the positive or negative electrode can be manufactured at a relatively low cost, it is possible to secure a capacity closer to that of a new product by using a new product.

  As a result, an inexpensive regenerative battery can be supplied.

  Further, one of the positive and negative electrodes can be treated as solid waste, but the environmental load can be reduced because no strong acid or strong alkali is used.

  Further, the initial discharge capacity of a new battery is 60% or more, preferably 70% or more, more preferably 80% or more, still more preferably 90% or more, and particularly preferably about 90 to 95%. (Discharge capacity) can also be maintained (see Examples 2 and 3).

[V] Fourth Embodiment This embodiment includes a lithium-ion battery including the following steps for a used lithium-ion battery having two or more openable / closable cock parts provided on an exterior material. This is an electrode regeneration method. That is, (1a) a step of opening the cock, (1) a step of injecting and processing a polar solvent into the battery, (2a) a step of discharging the polar solvent treatment liquid from the cock, and (2) the inside of the solvent treatment battery (3) A step of re-injecting the solution into the dry battery and sealing it.

  FIG. 6 is a diagram showing an outline of the fourth embodiment.

  Also in the electrode regeneration method of the present embodiment, first, when a usable remaining capacity remains for the used LIB 10 having an increased resistance, the remaining capacity is passed through the negative current collector 25 and the positive current collector 27. It is desirable to fully discharge and detoxify. This is the same as described in the first embodiment. Therefore, the description here is omitted.

  The determination as to whether the LIB 10 has been used is also the same as described in the first embodiment. Therefore, the description here is omitted.

  Further, in the electrode regeneration method of the present embodiment, as the used LIB, as shown in FIG. 6, two or more (two examples are shown in FIG. 6) openable / closable cock portions 26 and 28 are used as exterior materials. The LIB 10 provided so as to penetrate 29 is used. With this configuration, the inside of the LIB 10 is cleaned using the cock portions 26 and 28, sufficiently dried, and then re-injected to recover the capacity without disassembling the LIB 10 at all. It is. The installation location of the cock portions 26 and 27 is not particularly limited. Preferably, when the electrode current collector plates 25 and 27 of the LIB 10 are taken out from two opposite sides of the rectangular shape so that they do not get in the way during normal charge and discharge use, the positive and negative current collector plates are It is desirable to provide on two opposite sides different from the taken-out sides. In particular, it can be said that it is more desirable to provide it at a diagonal position as shown in FIG. However, the number of cocks installed is not limited to two as shown in FIG. 6 but is arranged (installed) so as to improve injection and drainage efficiency by providing three or more. May be.

  The cock portion may be installed in a new LIB in advance or may be installed later in a used LIB. Thereby, it is excellent at the point which can provide the reproduction | regenerating method of this embodiment with respect to all the batteries. When installing in a new LIB in advance, after the power generation element 21 is stored, the cock portions 26 and 28 are placed (inserted) at predetermined locations on the exterior material 29 before sealing, and the periphery of the exterior material 29 is heat-melted. What is necessary is just to seal by sealing. Thereafter, an electrolytic solution is injected from the cock part 26 attached to the lower part of the LIB 10, and then the cock parts 26, 28 are closed (sealed) so that the cock parts 26, 28 are installed in the new LIB 10 in advance. Can do. On the other hand, when installing to used LIB retrofitting, after fully discharging as above-mentioned, the attachment planned location of the cock part of an exterior material is opened. When opening, heat may be applied as necessary to reduce the adhesive strength of the seal portion. If necessary, after extracting (a part of) the electrolyte from the opening, insert the cock part into the opening and seal (seal) the outer packaging around the cock again by heat sealing. Good. However, the installation method of the cock portion of the present embodiment is not limited to the above-described method.

Step (1a) Next, after the used LIB is sufficiently discharged and rendered harmless as necessary, a step of opening the cock is performed as step (1a).

  Specifically, openable / closable cocks (not shown) of the cock parts 26 and 28 shown in FIG. 6 are opened. Thereby, a part of the electrolytic solution in the LIB 10 is drained from the cock portion 26 provided in the lower part of the LIB 10 (it is desirable to collect and reuse the electrolytic solution). Further, the gas generated in the LIB 10 is exhausted from the cock portion 28 provided on the upper part of the LIB 10. However, before opening the cocks of the cock parts 26, 28, a pipe (hose) for injection from a polar solvent storage tank is connected to the cock part 26 in advance, and a pipe (hose) for draining from the cock part 28 is connected. You may connect to the collection | recovery tank of the polar solvent in which electrolyte solution and SEI dissolved. In this case, it is not necessary to drain the electrolytic solution and exhaust the generated gas in the LIB. Thus, in this step, it is only necessary to perform an operation for opening the cock, and the operation is not limited to the above-described operation.

Step (1) Subsequently, as the step (1), a process of injecting a polar solvent into the battery is performed.

  Specifically, as shown in FIG. 6, a solvent processing battery is obtained by injecting a polar solvent into the LIB 10 (see FIG. 1 for the basic configuration of the LIB 10). The contents to be processed by injecting the polar solvent are the same as those in the first embodiment described in FIG. That is, in the step of opening the cock of (1a), after draining the electrolyte solution that can be easily extracted from the cock part 26 at the bottom of the LIB 10, a polar solvent is injected into the LIB 10 from the cock part 26 at the bottom of the LIB 10. Fill with polar solvent (fill with polar solvent). By filling the inside of the LIB 10 with the polar solvent for a predetermined time (for example, about 30 to 60 minutes), the used electrode in the LIB 10 can be immersed in the polar solvent as in the first embodiment. As a result, the electrolyte remaining in the LIB 10 and the deposit (SEI) on the surface of the used electrode (active material particles) can be dissolved in the polar solvent. Thereafter, the polar solvent in which the remaining electrolyte and the deposit (SEI) on the surface of the used electrode (active material particles) are dissolved opens the cocks 26 and 28 and is discharged from the lower cock part 26. After discharging the polar solvent, while re-injecting fresh polar solvent from the cock part 26 at the lower part of the LIB 10, while extracting the polar solvent in which the electrolyte and deposits are dissolved from the cock part 28 at the upper part of the LIB 10, Rinse with fresh polar solvent. By injecting the polar solvent in this way, the deposit (SEI) is peeled off from the used LIB 10 immersed in the polar solvent first, particularly from the surface of each active material particle in the electrode. Deposit (SEI) is dissolved. The polar solvent in which the electrolytic solution and the deposit (SEI) are dissolved may be extracted out of the system from the cock portion 28 at the top of the LIB 10, but it is desirable to recover and reuse them. Thereafter, fresh polar solvent is injected again from the cock part 26, and the polar solvent in which the electrolyte and deposits are dissolved is extracted from the cock part 28, and the inside of the LIB 10, particularly the electrode, is rinsed. By performing such a rinsing treatment, it is excellent in that it is possible to completely wash away (wash off) the electrolyte solution and deposits that remain slightly together with the polar solvent. In the above description, the mode in which the polar solvent is injected into the LIB 10 from the cock portion 26 at the bottom of the LIB 10 has been described. However, when the cock is once closed and cleaning is performed for a predetermined time, the injection direction is not limited. That is, the polar solvent may be injected into the LIB 10 from the cock part 26 at the lower part of the LIB 10, or the polar solvent may be injected into the LIB 10 from the cock part 28 at the upper part of the LIB 10. On the other hand, in the embodiment in which the polar solvent is continuously injected into the LIB 10 from the cock portion of the LIB 10, as described above, the polar solvent is injected into the LIB 10 from the cock portion 26 below the LIB 10, and from the cock portion 28 above the LIB 10. It is preferable to discharge. This is because, compared with the case of injecting from the upper part, the generation of bubbles and uninjected portions can be suppressed, the inside of the LIB 10 can be easily filled with the polar solvent, and the cleaning efficiency of the entire battery can be increased.

  In this step (1), it is desirable to perform ultrasonic treatment (frequency 15 to 400 kHz) when treating with a polar solvent. This is because the inside of the electrode active material layer can be well washed with ultrasonic waves by performing ultrasonic treatment when injecting a polar solvent into the LIB 10 for processing. That is, the cleaning solvent (polar solvent) can permeate the electrode active material layer evenly and can be cleaned. For this reason, even the electrolyte solution inside the electrode active material layer and the SEI on the surface of the electrode (active material particles) can be uniformly dissolved in a polar solvent and removed. Cleaning by ultrasonic treatment is desirably 10 minutes or more and 60 minutes or less. If the cleaning time by ultrasonic treatment is 10 minutes or more, it is excellent in that it can be permeated evenly and the inside of the electrode active material layer can be washed well (electrolytic solution and deposits are removed). On the other hand, if the cleaning time by ultrasonic treatment is within 60 minutes, the heat is not increased excessively by the ultrasonic waves and the battery contents are not damaged, and the active material layer is not peeled off by vibration, and the electrode is effectively removed. It is excellent in that the inside of the active material layer can be washed well (electrolytic solution and deposits are removed). The ultrasonic wave (frequency) may be appropriately adjusted depending on the degree of electrode contamination (particularly the degree of SEI adhesion on the surface of the electrode (active material particles)). Usually, it is sufficient to use a frequency around 40 KHz (applied in Example 12), but for stubborn dirt, it is effective to lower the frequency and remove it with the force of cavitation, and use a frequency around 28 kHz. Is good. Further, it is effective to remove the delicate dirt by increasing the frequency and reducing the cleaning unevenness, and it is preferable to use a frequency of 100 kHz or more. It is desirable to appropriately determine the optimum ultrasonic wave (frequency), for example, by conducting a preliminary experiment in advance.

  Moreover, a used electrode means the used positive / negative electrode inside a used laminated battery (refer FIG. 1).

  Further, the “polar solvent” injected from the cock section refers to an organic solvent having a dielectric constant of 5.0 or more.

The polar solvent injected from the cock portion in this step (1) is not particularly limited as long as it is a polar solvent other than water, but is preferably an aprotic polar solvent. This is because some positive electrodes constituting the power generation element in the LIB, such as Ni-rich positive electrodes, release Li ⁺ from the surface by H ⁺ , so that aprotic polar solvents such as ether and acetone are not used. This is because the degree of deterioration is acceptable if it is not water. In this step (1), since the positive and negative electrodes constituting the power generation element inside the LIB are simultaneously cleaned without dismantling the LIB, the polar solvent as the cleaning solvent is preferably other than water, more preferably ether or acetone. Aprotic polar solvent. By injecting from the aprotic polar solvent cock such as ether or acetone, it is excellent in that the positive and negative electrodes constituting the power generation element 21 inside the LIB 10 can be washed without damaging the positive electrode. ing.

  Examples of the polar solvent injected from the cock part include protic polar solvents such as methanol, ethanol, n-propanol, isopropanol, 1-butanol, 2-butanol, formic acid, acetic acid, propionic acid, ethylene glycol, and propylene glycol. Aprotic polar solvents such as diethyl ether, ethyl acetate, tetrahydrofuran, pyridine, dimethyl sulfoxide, acetonitrile, cyclohexanone, acetone, methyl ethyl ketone, 1,4-dioxane, 1,3-dioxolane, and ethylene glycol dimethyl ether are used. be able to. However, it is not limited to these polar solvents. Moreover, the polar solvent illustrated above may be used individually by 1 type, and may use 2 or more types together.

  Examples of the aprotic polar solvent suitable as the polar solvent to be injected from the cock portion include, for example, diethyl ether, ethyl acetate, tetrahydrofuran, pyridine, dimethyl sulfoxide, acetonitrile, cyclohexanone, acetone, methyl ethyl ketone, 1, 4 -Dioxane, 1,3-dioxolane, ethylene glycol dimethyl ether, etc. are mentioned. However, there is no limitation to these aprotic polar solvents. Moreover, the aprotic polar solvent illustrated above may be used individually by 1 type, and may use 2 or more types together.

(2a) Step Next, as the step (2a), a step of discharging the polar solvent treatment liquid from the cock is performed.

  Specifically, in the step (1), fresh polar solvent is injected again from the cock part 26, and the polar solvent in which the electrolyte and deposits are dissolved is extracted from the cock part 28, and the inside of the LIB 10, particularly the electrodes, is rinsed. Thereafter, the injection of the polar solvent from the cock portion 26 is stopped. After the stop, the cock of the cock part 26 is temporarily closed, and the injection path connected to the cock part 26 is switched to the discharge path. Thereafter, the cock of the cock part 26 is opened, and the polar solvent treatment liquid inside the LIB 10 is discharged from the cock part 26. The discharged polar solvent treatment liquid may be recovered, purified and reused. By discharging the polar solvent treatment liquid inside the LIB 10 from the cock portion 26, it is possible to obtain a solvent treatment battery in which the electrolyte and deposits are removed from the inside of the LIB 10, particularly from the electrodes.

Step (2) Next, as step (2), a step of drying the inside of the solvent-treated battery is performed.

  For example, (a) a solvent-treated battery can be dried under appropriate drying conditions to obtain a dry battery. As the drying condition of (a) above, it is placed in a vacuum dryer with the cocks 26 and 28 of the solvent processing battery opened, and is dried at 60 to 80 ° C. for 8 to 24 hours at 0.1 atm or less. Just do it. However, it is not limited to the drying condition (a) above, and even if it is outside the range of the drying condition, there is no limitation as long as it does not impair the effects of the present embodiment. . When returning to a reduced pressure, it is desirable to use dry air or argon gas in a dry box. Or (b) The inside of the solvent-treated battery is dried and dried by ventilating dry air or Ar gas inside the solvent-treated battery with appropriate ventilation conditions using the cocks 26 and 28 of the solvent-treated battery as vents and exhaust ports. It can be a battery. The drying condition (b) may be performed for 8 to 24 hours by passing dry air or Ar gas heated to 60 to 80 ° C. through the solvent-treated battery. However, it is not limited to the drying condition (b) above, and even if it is outside the range of the drying condition, there is no limitation as long as it does not impair the effects of the present embodiment. . If the pressure in the vacuum dryer at the time of drying (a) is 0.1 atm or less, the pressure can be sufficiently reduced (vacuum), so that the vaporized solvent can be removed under reduced pressure without liquefaction again. It is excellent in that it can be sufficiently dried in a short time. Even when dry air (dry air) or Ar gas is used in the dry box at the time of drying (b) above, the vaporized solvent can be removed outside the dry box without being liquefied again, and the inside of the electrode can be quickly removed. Is excellent in that it can be sufficiently dried. Moreover, if the drying temperature of said (a) (b) is 60 degreeC or more, an organic solvent can be evaporated quickly and it can fully dry to the inside of an electrode for a short time. A drying temperature of 80 ° C. or lower is excellent in that the drying rate can be increased without causing deterioration of the electrode active material or the like. Moreover, if the drying time of said (a) (b) is 8 hours or more, it can fully dry to the inside of an electrode, without leaving an organic solvent. If the drying time is 24 hours or less, it is excellent in that the inside of the electrode can be sufficiently dried and the drying cost can be suppressed. However, in the present embodiment, the drying method is not limited at all. Preferably, the drying by vacuum heating using the vacuum dryer described above is performed so that the polar solvent does not remain in the dry solvent-treated battery, and the vacuum active state can be uniformly applied to the inside of the electrode active material layer. It is excellent in that it can be dried more uniformly.

Step (3) Next, as step (3), a step of re-injecting the liquid into the dry battery and sealing it is performed.

  Specifically, a rechargeable / reusable battery is obtained by re-injecting an electrolyte (new) into a dry battery in the same manner as a new battery. In the step (3) of the present embodiment, the dry battery is placed in a vacuum / depressurized state in the step (2) (that is, the cocks of the cock portions 26 and 28 are closed under vacuum depressurization after vacuum drying). . Thereafter, the cock of the cock part 26 at the lower part of the vacuum / depressurized dry battery is opened, and vacuum injection is performed from the cock part. After re-injecting the same amount of electrolyte as the new battery with the vacuum injection, the cock of the cock part is closed and sealed, so that a reusable / reusable battery (regenerated battery) can be obtained. . After the cocks of the cock parts 26 and 28 are closed, the cock of the regenerative battery is not accidentally operated by bolting, crimping, fusing or bonding, etc. It is desirable to fasten or seal so that it does not open. Here, by re-injecting the liquid, the separator in the dry LIB 10 is re-impregnated with the electrolytic solution, and the electrolyte layer is revived (it can be said that the power generation element is also regenerated (completed) at this point). By this step (3), a battery having a reusable / reusable electrode can be obtained without reducing the deteriorated electrode to the raw material.

  The operational effects of the fourth embodiment are as follows.

  According to the fourth embodiment, the battery is provided with two or more openings, the inside of the LIB is washed without disassembling the LIB, and the deposit which is the main component of capacity deterioration is washed away and sufficiently dried. By re-injecting liquid, the conventional technical problem is solved.

  In the fourth embodiment, if the LIB is previously provided with an inlet / outlet for the polar solvent for washing, and the polar solvent is injected and washed from there, the capacity can be recovered without disassembly at all.

  In addition, since there are a plurality of cocks, the polar solvent for cleaning is easily volatilized without clogging during drying under reduced pressure.

  Further, since the capacity can be recovered without disassembling the battery, it can be provided at low cost when the used LIB for an electric vehicle (EV) is reused as a stationary LIB.

  Moreover, without disassembling the LIB, further up to 60% or more of the initial discharge capacity of a new battery, preferably 70% or more, more preferably about 70 to 85% (initial discharge capacity in a regenerative battery). Can be recovered (see Examples 11-14).

  Further, it is not necessary to peel off the electrodes one by one, and it is excellent in that a laminate type or other exterior material can be recycled by treatment (washing) with a polar solvent, drying, and re-injection.

  The effects of the embodiment will be described using the following examples. However, the technical scope of the embodiment is not limited to the following examples. FIG. 7 is a schematic cross-sectional view of a laminate type lithium ion secondary battery manufactured in Examples and Comparative Examples.

[Example 1]
The positive electrode current collector 12 of FIG. 7 is an aluminum foil, the positive electrode active material is lithium cobalt nickel manganate (LiNi _0.33 Co _0.33 Mn _0.33 O ₂ ), the negative electrode current collector 11 is a copper foil, and the negative electrode active material A laminated lithium ion secondary battery 10 using artificial graphite was prepared. Specifically, a laminate type lithium ion secondary battery 10 was produced as follows.

<Preparation of positive electrode>
The positive electrode current collector 12 is an aluminum foil (Al foil) having a size (area) of 32 mm × 42 mm and a thickness of 20 μm. The positive electrode active material is lithium cobalt nickel manganate (LiNi 0.1 .mu.m) having an average particle diameter of 5 μm _{. 33} Co _0.33 Mn _0.33 O ₂ ). PVdF was used for the binder, and acetylene black was used as a conductive auxiliary.

The positive electrode 18 was prepared by changing the electrode composition ratio (mass ratio) to an active material (LiNi _0.33 Co _0.33 Mn _0.33 O ₂ ): conductive aid: binder = 91: 4: 5 (mass ratio). It was made to become. First, an active material, a conductive additive, and a binder were weighed, an appropriate amount of NMP (N-methyl-2-pyrrolidone) was added to the mixture, and the mixture was placed in a homogenizer container and thoroughly stirred and mixed to prepare a slurry. Thereafter, a certain amount of this slurry was applied to one side of a positive electrode current collector (Al foil) 12 using a die coater so that the positive electrode active material layer 15 portion was 30 mm × 40 mm in size and dried. On the other side of the positive electrode current collector (Al foil) 12, a certain amount was applied so that the positive electrode active material layer 15 portion was 30 mm × 40 mm, dried, and pressed with a roll press. . It dried for one day with a 90 degreeC vacuum dryer. The thickness (single side) of the positive electrode active material layer 15 of the positive electrode 18 produced in this way was 80 μm at the time of completion. As shown in FIG. 7, an aluminum tab is joined by ultrasonic welding as a positive electrode tab (current collector plate) 27 to one end of the positive electrode current collector 12 where the positive electrode active material layer 15 is not formed (electrical). Connected).

<Production of negative electrode>
The negative electrode current collector 11 was a copper foil having a size (area) of 34 mm × 47 mm and a thickness of 15 μm, and artificial graphite having an average particle diameter of 10 μm was used as the negative electrode active material. PVdF was used for the binder, and acetylene black was used as a conductive auxiliary.

  The negative electrode 14 was prepared such that the electrode composition ratio (mass ratio) was active material (artificial graphite): conductive aid: binder F = 96: 1: 5 (mass ratio). First, an active material, a conductive additive and a binder were weighed, an appropriate amount of NMP was added thereto, and the mixture was placed in a homogenizer container, and thoroughly stirred and mixed to prepare a slurry. Thereafter, this slurry was applied to only one surface of the negative electrode current collector (copper foil) 11 using a die coater so that the negative electrode active material layer 13 portion had a size of 32 mm × 45 mm, dried, and then rolled. It was over. It dried for one day with a 90 degreeC vacuum dryer. The thickness (single side) of the negative electrode active material layer 13 of the negative electrode 14 thus produced was 60 μm at the time of completion. As shown in FIG. 7, a nickel tab as a negative electrode tab (current collector plate) 25 is joined by ultrasonic welding to one end of the negative electrode current collector 11 where the negative electrode active material layer 13 is not formed (electrical). Connected).

<Production of battery>
As shown in FIG. 7, one positive electrode 18 and two negative electrodes 14 are alternately stacked between the positive electrode 18 and the negative electrode 14 manufactured as described above, with the separator 16 serving as the outermost electrode. Thus, a power generation element (laminated body) 21 was obtained. The positive electrode tab 27 and the negative electrode tab 25 attached to the current collectors 11 and 12 of the power generation element 21 were inserted into an Al laminate film back as an exterior material 29 so as to have a structure for taking out to the outside. Thereafter, an electrolytic solution is injected into the back 29 through an opening of the film back 29, and the opening is sealed (sealed) by heat-sealing under reduced pressure. A laminate type lithium ion secondary battery 10 composed of a single cell 19 was produced. The separator 16 was a polypropylene microporous film having a size (area) of 36 mm × 50 mm and a thickness of 25 μm. As the electrolytic solution, 1M LiPF ₆ EC: DEC (3: 7 (volume ratio)) was used. Here, EC is ethylene carbonate, and DEC is diethyl carbonate. By injecting the electrolytic solution, the separator 16 was impregnated with the electrolytic solution to form the electrolyte layer 17.

The laminate type lithium ion secondary battery 10 produced above had an initial discharge capacity of 5.0 mAh / cm ² (battery capacity; 120 mAh). When the battery 10 was deteriorated by charging and discharging 400 times at 45 ° C., the discharge capacity was deteriorated to 2.2 mAh / cm ² (44%). Of the 400 charge / discharge conditions including the initial charge / discharge, the charge condition is 45 ° C. and constant current / constant voltage method (CCCV, current: 1 C, cell voltage: 4.2 V) for a total of 2.5 hours. The charging process was performed. The discharge conditions were 45 ° C. and a constant current method (CC, current: 1 C).

  The battery (deteriorated battery) 10 deteriorated by charging and discharging 400 times as described above was discharged and rendered harmless. Here, the discharge for detoxification performed the process which reduces a cell voltage to 2.5V (below) by normal temperature (25 degreeC) and 1C discharge. Thereafter, the outer periphery of the laminate outer packaging material 29 was cut so as not to damage the positive and negative electrodes 18 and 14 and the positive and negative electrode tabs 27 and 25 in the glove box, so to speak, it was semi-disassembled. From here, it demonstrates using FIG. Each electrode of the used positive electrode 7a and the negative electrode 8a with a tab was taken out from the obtained battery content (used electric power generation element 6a), and was divided separately.

  The used positive electrode (positive electrode active material layer + positive electrode current collector + positive electrode tab) 7a is immersed in a beaker filled with acetone (dielectric constant 20.7) as a polar solvent for cleaning the positive electrode for 30 minutes, and deposited with an electrolytic solution. After the product was dissolved, it was rinsed again with fresh acetone for about 1 minute. Two used negative electrodes (negative electrode active material layer + negative electrode current collector + negative electrode tab) 8a were also immersed in a beaker filled with acetone (dielectric constant 20.7) as a polar solvent for cleaning the negative electrode for 30 minutes, and electrolysis was performed. After dissolving the liquid and sediment, it was rinsed again with fresh acetone for about 1 minute.

The solvent-treated positive and negative electrodes 7b and 8b after the washing treatment with the polar solvent were dried at 130 ° C. for 5 hours in a vacuum dryer. The dried positive and negative electrodes (regenerated positive and negative electrodes) 7c and 8c thus dried were assembled again as a regenerated power generation element 6b together with a separator (reference numeral 16 in FIG. 7; hereinafter the same). The regenerated power generation element 6b is inserted into a laminate-type exterior material (reference numeral 29 in FIG. 7; the same applies hereinafter), an electrolyte is injected, and the laminate is sealed, and a laminated lithium ion secondary battery (reference numeral 10 in FIG. 7; the same applies hereinafter). ). The electrolytic solution is impregnated with the electrolytic solution to form an electrolyte layer (reference numeral 17 in FIG. 7; the same applies hereinafter) (this is also true in the following examples and comparative examples). ). The regenerated battery had an initial discharge capacity of 4.1 mAh / cm ² and had recovered to 82% capacity when it was new. Table 1 shows the obtained results (capacity after deterioration after deterioration test, capacity recovery rate of regenerated battery). Here, the initial discharge conditions of the regenerated battery were the same as the 400 charge / discharge conditions for a new battery (the same applies to the following examples and comparative examples).

[Example 2]
In the same manner as that used in Example 1, the deteriorated battery 10 was discharged and rendered harmless, and the outer periphery of the laminate outer packaging material 29 was cut, so to speak, semi-disassembled. From here, it demonstrates using FIG. Further, in the same manner as in Example 1, the used positive electrode 7a and negative electrode 8a with tabs were taken out from the obtained battery contents (used power generation element 6a), and the following treatments were performed on the separated electrodes. Went.

The used positive electrode (positive electrode active material layer + positive electrode current collector; hereinafter also including the positive electrode tab) 7a in FIG. 5 is placed in a beaker filled with acetone (dielectric constant 20.7) as a polar solvent for cleaning the positive electrode. After soaking for a minute, the electrolyte and deposits were dissolved, and then rinsed again with fresh acetone for about 1 minute. Two pieces of used negative electrode (negative electrode active material layer + negative electrode current collector; hereinafter also including negative electrode tab) 8a was discarded without regenerating the electrode (actually crushed and reused in the same manner as in Patent Document 1). Was used). Instead, a negative electrode (negative electrode active material layer + negative electrode current collector + negative electrode tab; reference numeral 14 in FIG. 7) obtained in the same manner as in Example 1 was prepared as a new electrode (unused negative electrode) 8d. The solvent-treated positive electrode 7b after washing with the polar solvent and a new unused negative electrode 8d were dried at 130 ° C. for 5 hours in a vacuum dryer. The dried positive and negative electrodes 7c and 8e thus dried were assembled together with the separator as a regenerated power generation element 6c. The regenerated power generation element 6c was inserted into a laminate-type exterior material, an electrolyte solution (new) was injected, and sealed to regenerate the laminate-type lithium ion secondary battery. The regenerated battery had an initial discharge capacity of 4.75 mAh / cm ² and had recovered to 95% of the capacity when new. The obtained results are shown in Table 1.

[Example 3]
In the same manner as that used in Example 1, the deteriorated battery 10 was discharged and rendered harmless, and the outer periphery of the laminate outer packaging material 29 was cut, so to speak, semi-disassembled. From here, it demonstrates using FIG. 8 (here, FIG. 8 is a figure showing the outline | summary of each process of 3rd Embodiment which reproduces | regenerates a negative electrode applied in Example 3). Further, in the same manner as in Example 1, the used positive electrode 7a and negative electrode 8a with tabs were taken out from the obtained battery contents (used power generation element 6a), and the following treatments were performed on the separated electrodes. Went.

The used positive electrode (positive electrode active material layer + positive electrode current collector; hereinafter also including the positive electrode tab) 7a in FIG. 8 was discarded without regenerating the electrode (actually crushed and reused in the same manner as in Patent Document 1). Provided). Instead, a positive electrode (positive electrode active material layer + positive electrode current collector + positive electrode tab; symbol 18 in FIG. 7) obtained in the same manner as in Example 1 was used as a new electrode (cobalt nickel lithium manganate as the positive electrode active material). Unused positive electrode) 7d was prepared. The used negative electrode (negative electrode active material layer + negative electrode current collector, including negative electrode tab) 8a is immersed in a beaker filled with distilled water (dielectric constant 80.2) as a polar solvent for cleaning the negative electrode for 30 minutes. After dissolving the electrolytic solution and the deposit, it was rinsed again with fresh distilled water for about 1 minute. The solvent-treated negative electrode 8b washed with the polar solvent and the new unused positive electrode 7d were dried at 130 ° C. for 5 hours in a vacuum dryer. The dried positive and negative electrodes 7e and 8c thus dried were assembled together with the separator as a regenerated power generation element 6d. The regenerated power generation element 6d was inserted into a laminate type exterior material, an electrolyte solution (new) was injected, and sealed to regenerate a laminate type lithium ion secondary battery. The regenerated battery had an initial discharge capacity of 4.65 mAh / cm ² and had recovered to a capacity of 93% of the new battery. The obtained results are shown in Table 1.

[Example 4]
In the same manner as that used in Example 1, the deteriorated battery 10 was discharged and rendered harmless, and the outer periphery of the laminate outer packaging material 29 was cut, so to speak, semi-disassembled. From here, it demonstrates using FIG. Further, in the same manner as in Example 1, the used positive electrode 7a and negative electrode 8a with tabs were taken out from the obtained battery contents (used power generation element 6a), and the following treatments were performed on the separated electrodes. Went.

The used positive electrode (positive electrode active material layer + positive electrode current collector + positive electrode tab) 7a in FIG. 5 is immersed in a beaker filled with acetone (dielectric constant 20.7) as a polar solvent for positive electrode cleaning for 30 minutes, and electrolysis is performed. After dissolving the liquid and sediment, it was rinsed again with fresh acetone for about 1 minute. The used negative electrode (negative electrode active material layer + negative electrode current collector + negative electrode tab) 8a was immersed in a beaker filled with distilled water (dielectric constant 80.2) as a polar solvent for cleaning the negative electrode for 30 minutes, After dissolving the sediment, it was rinsed again with fresh distilled water for about 1 minute. The solvent-treated positive and negative electrodes 7b and 8b after the washing treatment with the polar solvent were dried at 130 ° C. for 5 hours in a vacuum dryer. The dried positive and negative electrodes (regenerated positive and negative electrodes) 7c and 8c were assembled together with the separator as a regenerated power generation element 6b. The regenerated power generation element 6b was inserted into a laminate-type exterior material, an electrolyte (new) was injected, and sealed to regenerate a laminate-type lithium ion secondary battery. The regenerated battery had an initial discharge capacity of 4.55 mAh / cm ² and had recovered to a capacity of 91% when new. The obtained results are shown in Table 1.

[Example 5]
Laminated lithium using an aluminum foil as the positive electrode current collector 12 in FIG. 7, a spinel structure lithium manganate (LiMn ₂ O ₄ ) as the positive electrode active material, a copper foil as the negative electrode current collector 11, and MCMB-type graphite as the negative electrode active material. An ion secondary battery 10 was produced. Specifically, a laminate type lithium ion secondary battery 10 was produced as follows.

<Preparation of positive electrode>
The positive electrode current collector 12 is an aluminum foil (Al foil) having a size (area) of 32 mm × 42 mm and a thickness of 20 μm, and the positive electrode active material is a spinel structure lithium manganate (LiMn ₂ O) having an average particle diameter of 5 μm. ₄ ) was used. PVdF was used for the binder, and acetylene black was used as a conductive auxiliary.

The positive electrode 18 was produced such that the electrode composition ratio (mass ratio) was positive electrode active material (LiMn ₂ O ₄ ): conductive auxiliary agent: binder = 91: 4: 5 (mass ratio). First, a positive electrode active material, a conductive additive, and a binder were weighed, an appropriate amount of NMP was added thereto, and the mixture was placed in a homogenizer container, and well stirred and mixed to prepare a slurry. Thereafter, a certain amount of this slurry was applied to one side of the positive electrode current collector 12 using a die coater so that the positive electrode active material layer 15 portion was 30 mm × 40 mm in size and dried. On the other side of the positive electrode current collector 12, a certain amount was applied and dried so that the positive electrode active material layer 15 portion was 30 mm × 40 mm in size, and pressed with a roll press. It dried for one day with a 90 degreeC vacuum dryer. The thickness (single side) of the positive electrode active material layer 15 of the positive electrode 18 produced in this way was 80 μm at the time of completion. An aluminum tab as a positive electrode tab (current collector plate) 27 was joined (electrically connected) to one end of the positive electrode current collector 12 where the positive electrode active material layer 15 of FIG. 7 was not formed by ultrasonic welding.

<Production of negative electrode>
The negative electrode current collector 11 was a copper foil having a size (area) of 34 mm × 47 mm and a thickness of 15 μm, and the negative electrode active material was MCMB type graphite having an average particle diameter of 10 μm. PVdF was used for the binder, and acetylene black was used as a conductive auxiliary.

  The negative electrode 14 was prepared such that the electrode composition ratio (mass ratio) was negative electrode active material (MCMB type graphite): conductive aid: binder F = 96: 1: 5 (mass ratio). First, a negative electrode active material, a conductive additive, and a binder were weighed, and an appropriate amount of NMP was added thereto and placed in a homogenizer container, and thoroughly stirred and mixed to prepare a slurry. Thereafter, this slurry was applied to only one surface of the negative electrode current collector (copper foil) 11 using a die coater so that the negative electrode active material layer 13 portion had a size of 32 mm × 45 mm, dried, and then rolled. It was over. It dried for one day with a 90 degreeC vacuum dryer. The thickness (single side) of the negative electrode active material layer 13 of the negative electrode 14 thus produced was 60 μm at the time of completion. A nickel tab as a negative electrode tab (current collector plate) 25 was joined (electrically connected) to one end of the negative electrode current collector 11 where the negative electrode active material layer 13 of FIG. 7 was not formed by ultrasonic welding.

<Production of battery>
As shown in FIG. 7, one positive electrode 18 and two negative electrodes 14 are alternately stacked between the positive electrode 18 and the negative electrode 14 manufactured as described above, with the separator 16 serving as the outermost electrode. Thus, a power generation element (laminated body) 21 was obtained. The positive electrode tab 27 and the negative electrode tab 25 attached to the current collectors 11 and 12 of the power generation element 21 were inserted into an Al laminate film back as an exterior material 29 so as to have a structure for taking out to the outside. Thereafter, an electrolytic solution is injected into the back 29 through an opening of the film back 29, and the opening is sealed (sealed) by heat-sealing under reduced pressure. A laminate-type lithium ion secondary battery 10 composed of The separator 16 was a polypropylene microporous film having a size (area) of 36 mm × 50 mm and a thickness of 25 μm. As the electrolytic solution, 1M LiPF ₆ EC: DEC (3: 7 (volume ratio)) was used. By injecting the electrolytic solution, the separator 16 was impregnated with the electrolytic solution to form the electrolyte layer 17.

The laminate type lithium ion secondary battery 10 produced above had an initial discharge capacity of 5.0 mAh / cm ² (battery capacity; 120 mAh). When the battery 10 was deteriorated by charging and discharging 400 times at 45 ° C., the discharge capacity was deteriorated to 1.8 mAh / cm ² (36%). Of the 400 charge / discharge conditions including the initial charge / discharge, the charge condition is 45 ° C. and constant current / constant voltage method (CCCV, current: 1 C, cell voltage: 4.2 V) for a total of 2.5 hours. The charging process was performed. The discharge conditions were 45 ° C. and a constant current method (CC, current: 1 C).

  The battery (deteriorated battery) 10 deteriorated by charging and discharging 400 times as described above was discharged and rendered harmless. Here, the discharge for detoxification performed the process which reduces a cell voltage to 2.5V (below) by normal temperature (25 degreeC) and 1C discharge. Thereafter, the outer periphery of the laminate outer packaging material 29 was cut so as not to damage the positive and negative electrodes 18 and 14 and the positive and negative electrode tabs 27 and 25 in the glove box, so to speak, it was semi-disassembled. From here, it demonstrates using FIG. Each electrode of the used positive electrode 7a and the negative electrode 8a with a tab was taken out from the obtained battery content (used electric power generation element 6a), and was divided separately.

  The used positive electrode (positive electrode active material layer + positive electrode current collector + positive electrode tab) 7a is immersed in a beaker filled with tetrahydrofuran (THF; dielectric constant 7.6) as a polar solvent for cleaning the positive electrode for 30 minutes, and an electrolytic solution After the deposit was dissolved, it was rinsed again with fresh THF for about 1 minute. Two used negative electrodes (negative electrode active material layer + negative electrode current collector + negative electrode tab) 8a were also immersed in a beaker filled with methanol (dielectric constant 32.7) as a polar solvent for cleaning the negative electrode for 30 minutes, and subjected to electrolysis. After dissolving the liquid and sediment, it was rinsed again with fresh methanol for about 1 minute.

The solvent-treated positive and negative electrodes 7b and 8b after the washing treatment with the polar solvent were dried at 130 ° C. for 5 hours in a vacuum dryer. The dried positive and negative electrodes (regenerated positive and negative electrodes) 7c and 8c were assembled together with the separator as a regenerated power generation element 6b. The regenerated power generation element 6b was inserted into a laminate-type exterior material, an electrolyte was injected, and sealed to regenerate the laminate-type lithium ion secondary battery. The regenerated battery had an initial discharge capacity of 4.3 mAh / cm ² and had recovered to a capacity of 86% when new. The obtained results are shown in Table 1.

[Example 6]
As the positive electrode active material, lithium nickelate (LiNiO ₂ ) was used instead of spinel structure lithium manganate (LiMn ₂ O ₄ ), and as the polar solvent for positive electrode cleaning, THF (dielectric constant 7.6) was changed to methyl ethyl ketone (MEK). A dielectric constant of 18.5) was used. As the negative electrode active material, natural graphite was used instead of MCMB type graphite, and ethanol (dielectric constant 24.6) was used instead of methanol (dielectric constant 32.7) as a polar solvent for cleaning the negative electrode. Except for these, a laminated lithium ion secondary battery was produced, deteriorated, and regenerated in the same manner as in Example 5. The obtained results are shown in Table 1.

[Example 7]
As a positive electrode active material, lithium cobaltate (LiCoO ₂ ) was used instead of spinel structure lithium manganate (LiMn ₂ O ₄ ), and ethyl acetate (dielectric constant 7.6) was used as a polar solvent for positive electrode cleaning. Dielectric constant 6) was used. As the negative electrode active material, natural graphite was used instead of MCMB type graphite, and 1-butanol (dielectric constant 12.5) was used as the polar solvent for cleaning the negative electrode instead of methanol (dielectric constant 32.7). Except for these, a laminated lithium ion secondary battery was produced, deteriorated, and regenerated in the same manner as in Example 5. The obtained results are shown in Table 1.

[Example 8]
As the positive electrode active material, lithium olivine (LiFePO ₄ ) was used instead of spinel structure lithium manganate (LiMn ₂ O ₄ ), and acetonitrile (dielectric constant) was changed to THF (dielectric constant 7.6) as a polar solvent for positive electrode cleaning. A rate of 37.5) was used. As the negative electrode active material, hard carbon was used instead of MCMB type graphite, and isopropanol (dielectric constant 19.9) was used as the polar solvent for cleaning the negative electrode instead of methanol (dielectric constant 32.7). Except for these, a laminated lithium ion secondary battery was produced, deteriorated, and regenerated in the same manner as in Example 5. The obtained results are shown in Table 1.

[Example 9]
As the positive electrode active material, lithium nickelate (LiNiO ₂ ) was used instead of spinel structure lithium manganate (LiMn ₂ O ₄ ), and distilled water (dielectric constant 7.6) was used as the polar solvent for positive electrode cleaning. Dielectric constant 80.2) was used. As the negative electrode active material, natural graphite was used instead of MCMB type graphite, and ethanol (dielectric constant 24.6) was used instead of methanol (dielectric constant 32.7) as a polar solvent for cleaning the negative electrode. Except for these, a laminated lithium ion secondary battery was produced, deteriorated, and regenerated in the same manner as in Example 5. The obtained results are shown in Table 1.

[Example 10]
As the positive electrode active material, lithium cobalt manganate (LiNi _0.33 Co _0.33 Mn _0.33 O ₂ ) was used instead of spinel structure lithium manganate (LiMn ₂ O ₄ ). Further, acetone (dielectric constant 20.7) was used instead of THF (dielectric constant 7.6) as a polar solvent for cleaning the positive electrode. As the negative electrode active material, silicon powder was used instead of MCMB type graphite, and distilled water (dielectric constant 80.2) was used as the polar solvent for cleaning the negative electrode instead of methanol (dielectric constant 32.7). Except for these, a laminated lithium ion secondary battery was produced, deteriorated, and regenerated in the same manner as in Example 5. The obtained results are shown in Table 1.

[Example 11]
7 except that the power generation element 21 described in Example 1 in FIG. 7 was enclosed in an exterior material 29 of an Al laminate film back provided with two openable / closable plastic screw cocks 26 and 28 in FIG. In the same manner as in Example 1, a laminated lithium ion secondary battery 10 was produced.

The lithium ion secondary battery 10 produced above had an initial discharge capacity of 5.0 mAh / cm ² (battery capacity; 120 mAh). When the battery 10 was deteriorated by charging and discharging 400 times at 45 ° C., the discharge capacity was deteriorated to 2.2 mAh / cm ² (44%). Here, the charge / discharge conditions of 400 times including the first charge / discharge were the same as in Example 1.

  Open the plastic screw cock 28 inside the glove box and inject acetone (dielectric constant 20.7) as a polar solvent for electrode cleaning inside the battery (deteriorated battery) after being deteriorated by charging and discharging 400 times as described above. The cock 28 was closed and held for 30 minutes. After 30 minutes, the cock 26 was opened to squeeze out the treatment solution (polar solvent in which the electrolyte and deposits were dissolved), the cock 28 was opened, acetone was again injected from the cock 28, and rinsed for about 1 minute while being discharged from the cock 26.

Then, it dried for 8 hours at 75 degreeC in the vacuum dryer in the state which opened the cocks 26 and 28. FIG. The cock 26 of the dried LIB 10 was closed and the electrolyte solution (new article) was re-injected from the cock 28, and then the cock 28 was also closed to regenerate the laminated lithium ion secondary battery 10. The regenerated battery had an initial discharge capacity of 3.95 mAh / cm ² and had recovered to 79% of the capacity when it was new. The results are shown in Table 1.

[Example 12]
In the operation described in Example 11, laminated lithium ion was obtained by the operation described in Example 11, except that acetone was injected as the polar solvent for electrode cleaning, and the cock 28 was closed and sonication was performed in an ultrasonic cleaner for 15 minutes. The secondary battery 10 was regenerated. The regenerated battery had an initial discharge capacity of 4.1 mAh / cm ² and had recovered to 82% capacity when it was new. The results are shown in Table 1.

[Example 13]
In the operation described in Example 11, the laminate type lithium ion secondary battery 10 was regenerated by the operation described in Example 11 except that treatment was performed with methanol instead of acetone as the polar solvent for electrode cleaning. The regenerated battery had an initial discharge capacity of 3.7 mAh / cm ² and had recovered to a capacity of 74% of the new battery. The results are shown in Table 1.

[Example 14]
In the operation described in Example 11, the laminate type lithium ion secondary battery 10 was regenerated by the operation described in Example 11 except that the polar solvent for electrode cleaning was treated with distilled water instead of acetone. The regenerated battery had an initial discharge capacity of 3.6 mAh / cm ² and was restored to 72% capacity when it was new. The results are shown in Table 1.

[Comparative Example 1]
In the same manner as that used in Example 1, the deteriorated battery 10 was discharged and rendered harmless, and the outer periphery of the laminate outer packaging material 29 was cut, so to speak, semi-disassembled. From here, it demonstrates using FIG. Further, in the same manner as in Example 1, the used positive electrode 7a and negative electrode 8a with tabs were taken out from the obtained battery contents (used power generation element 6a), and the following treatments were performed on the separated electrodes. Went.

The used positive and negative electrodes (active material layer + current collector + electrode tab) 7a, 8a in FIG. 5 are placed in a beaker filled with toluene (dielectric constant 2.4 = nonpolar solvent) as a solvent for cleaning the positive and negative electrodes. After soaking for a minute, the electrolyte and deposits were dissolved, and then rinsed again with fresh toluene for about 1 minute. The solvent-treated positive and negative electrodes 7b and 8b after the washing treatment with the solvent were dried at 130 ° C. for 5 hours in a vacuum dryer. The dried positive and negative electrodes (regenerated positive and negative electrodes) 7c and 8c were assembled together with the separator as a regenerated power generation element 6b. The regenerated power generation element 6b was inserted into a laminate-type exterior material, an electrolyte (new) was injected, and sealed to regenerate a laminate-type lithium ion secondary battery. The regenerated battery had an initial discharge capacity of 2.55 mAh / cm ² and had recovered only to a capacity of 51% when new, and no reuse value was observed. The results are shown in Table 1.

[Comparative Example 2]
In the same manner as that used in Example 1, the deteriorated battery 10 was discharged and rendered harmless, and the outer periphery of the laminate outer packaging material 29 was cut, so to speak, semi-disassembled. From here, it demonstrates using FIG. Further, in the same manner as in Example 1, the used positive electrode 7a and negative electrode 8a with tabs were taken out from the obtained battery contents (used power generation element 6a), and the following treatments were performed on the separated electrodes. Went.

The used positive and negative electrodes (active material layer + current collector + electrode tab) 7a, 8a in FIG. 5 are placed in a beaker filled with chloroform (dielectric constant 4.8 = nonpolar solvent) as a solvent for cleaning the positive and negative electrodes. After soaking for a minute, the electrolyte and deposits were dissolved, and then rinsed again with fresh chloroform for about 1 minute. The solvent-treated positive and negative electrodes 7b and 8b after the washing treatment with the solvent were dried at 130 ° C. for 5 hours in a vacuum dryer. The dried positive and negative electrodes (regenerated positive and negative electrodes) 7c and 8c were assembled again as a regenerated power generation element 6b together with the separator (FIG. 7; reference numeral 16). The regenerated power generation element 6b was inserted into a laminate-type exterior material, an electrolyte (new) was injected, and sealed to regenerate a laminate-type lithium ion secondary battery. The regenerated battery had an initial discharge capacity of 2.8 mAh / cm ² and had recovered only to a capacity of 56% of the new battery, and no reuse value was observed. The results are shown in Table 1.

[Comparative Example 3]
In the same manner as that used in Example 5, the deteriorated battery 10 was discharged and rendered harmless, and the outer periphery of the laminate outer packaging material 29 was cut, that is, semi-disassembled. From here, it demonstrates using FIG. Further, in the same manner as in Example 5, the used positive electrode 7a and negative electrode 8a with tabs are taken out from the obtained battery contents (used power generation element 6a), and the following treatments are performed for those separately separated. Went.

The used positive and negative electrodes (active material layer + current collector + electrode tab) 7a and 8a in FIG. 5 are immersed in a beaker filled with cyclohexane (dielectric constant 2 = nonpolar solvent) as a solvent for cleaning the positive and negative electrodes for 30 minutes. After dissolving the electrolytic solution and the deposit, it was rinsed again with fresh cyclohexane for about 1 minute. The solvent-treated positive and negative electrodes 7b and 8b after the washing treatment with the solvent were dried at 130 ° C. for 5 hours in a vacuum dryer. The dried positive and negative electrodes (regenerated positive and negative electrodes) 7c and 8c were assembled together with the separator as a regenerated power generation element 6b. The regenerated power generation element 6b was inserted into a laminate-type exterior material, an electrolyte (new) was injected, and sealed to regenerate a laminate-type lithium ion secondary battery. The regenerated battery had an initial discharge capacity of 2.35 mAh / cm ² and had recovered only to 47% of the capacity when new, and no reuse value was observed. The results are shown in Table 1.

[Comparative Example 4]
A laminated lithium ion secondary battery was regenerated by the same operation as described in Example 11 except that only one plastic screw cock was installed. In the regenerated battery 10, the corner portion far from the cock could not be sufficiently cleaned. Moreover, the blockage of the laminate was observed near the cock during vacuum drying. The regenerated battery 10 had an initial discharge capacity of 2.9 mAh / cm ² , and recovered only to a capacity of 58% at the time of a new product, and the reuse value was not recognized. The results are shown in Table 1.

  “Acetone ultrasonic wave” in the column of the positive electrode cleaning solvent and the negative electrode cleaning solvent in Example 12 in the table represents that acetone was used as a polar solvent at the time of cleaning, and ultrasonic treatment was also used at the time of cleaning. .

  In the table, “(new)” in the column of the negative electrode active material of Example 2 indicates that the negative electrode was not regenerated and a new negative electrode was used. “(New)” in the column of the positive electrode active material of Example 3 indicates that the positive electrode was not regenerated and a new positive electrode was used.

(Experimental fact: Negative electrode cleaning effect)
FIG. 9 is a graph showing (1) theoretical values, (2) after discharge, and (3) discharge capacity per unit area after cleaning for the battery fabricated in Example 4.

  Here, (1) The theoretical discharge capacity means the theoretical discharge capacity of the battery produced in Example 4 when it is new. (2) The discharge capacity after deterioration refers to the discharge capacity of the battery at the 400th cycle of the deterioration test. (3) The discharge capacity after cleaning is that after the deterioration test, the battery is discharged and rendered harmless, then the semi-disassembled positive electrode is washed with acetone and the negative electrode is washed with water (both treated with a polar solvent), dried, reassembled, and re-assembled. It shall be the discharge capacity of the injected and regenerated battery.

From the results of FIG. 9, the discharge capacity after degradation was 2.25 mAh / cm ² , which was 44% of the theoretical value, with respect to the theoretical value of 5.0 mAh / cm ^{2 of} the battery manufactured in Example 4. Discharge capacity after washing is made harmless by discharging after the deterioration test, and the semi-decomposed positive and negative electrodes are washed with acetone and water to dissolve deposits on the surface of the active material layer (active material particles) in acetone and water and wash away. It was found that the recovery was about 4.5 mAh / cm ² to 91% of the theoretical value. Here, the deposit on the surface of the active material layer (active material particles) includes, for example, a composite such as Li salt, Li carboxylate, Li carbonate, Li, positive electrode and negative electrode-derived ions, solvent-derived organic matter, and the like. These are well soluble in acetone and water, which are polar solvents. Therefore, it can be said that the positive and negative electrode cleaning effect by washing with acetone, which is the polar solvent, and water, can be exhibited, and as a result, the high capacity recovery as described above can be achieved. From this result of Examples 2 and 3, it was confirmed that the same positive and negative electrode cleaning effect was obtained. Furthermore, from the results of other Examples 1 and 5 to 14, it was confirmed that the same positive and negative electrode cleaning effect was obtained.

  From the above, the positive and negative electrodes after the deterioration test shown in FIG. 9 appear to be considerably deteriorated. However, from the positive and negative electrode cleaning effect shown in FIG. 9, the positive and negative electrodes taken out by disassembling the exterior material are washed with acetone and water to dissolve the deposits on the surface of the active material layer in acetone and water, and the capacity is reduced to 91%. I found that I could recover. That is, after the used battery is discharged and rendered harmless, the positive and negative electrodes taken out by disassembling the exterior material are washed with acetone and washed with water, dried, reassembled, re-injected and regenerated, It was confirmed that it can be easily recycled and reused.

1a Used electrode,
1b Solvent-treated electrode,
1c Recyclable and reusable electrodes,
2 current collector,
3 electrode active material layer,
4 active material particles,
5 SEI (sediment)
6a Used power generation elements,
6b, 6c, 6d Regenerated power generation elements,
7a Used positive electrode,
7b Solvent-treated positive electrode,
7c, 7e dry cathode,
7d unused positive electrode,
8a Used negative electrode,
8b Solvent-treated negative electrode,
8c, 8e Dry negative electrode,
8d unused negative electrode,
10 Laminated battery (LIB, laminated lithium ion secondary battery),
11 negative electrode current collector,
12 positive electrode current collector,
13 negative electrode active material layer,
14 negative electrode (negative electrode current collector + negative electrode active material layer (+ negative electrode tab)),
15 positive electrode active material layer,
16 separator,
17 electrolyte layer (separator + electrolyte),
18 Positive electrode (positive electrode current collector + positive electrode active material layer (+ positive electrode tab))
19 cell layer,
21 power generation elements,
25 negative electrode tab (current collector plate),
27 Positive electrode tab (current collector plate),
26, 28 Cook (cock part),
29 Exterior body (laminate sheet).

Claims (9)

For used lithium-ion batteries,
(1) a step of treating at least one of positive and negative electrodes of the battery with a polar solvent;
(2) a step of drying the solvent-treated electrode,
(3) a step of re-injecting the battery having the dry electrode;
A method for regenerating an electrode of a lithium ion battery. At least one of the positive and negative electrodes in the step (1) is a positive and negative electrode taken out from a used lithium ion battery,
The method for regenerating a lithium ion battery according to claim 1, wherein the battery having the dry electrode in the step (3) is a battery that is reassembled using the dry electrode. The polarity of the polar solvent used for the electrode treatment in the step (1) is the following inequality;
(Polarity of polar solvent used for treatment of positive electrode) ≦ (Polarity of polar solvent used for treatment of negative electrode)
The electrode regeneration method of a lithium ion battery according to claim 1 or 2, wherein   The lithium ion battery according to any one of claims 1 to 3, wherein a solvent used for the positive electrode treatment among the solvents used for the electrode treatment in the step (1) is an aprotic polar solvent. Electrode regeneration method.   5. The lithium ion battery according to claim 1, wherein a solvent used for the negative electrode treatment among the solvents used for the electrode treatment in the step (1) is a protic polar solvent. Electrode regeneration method. For the used lithium ion battery provided with two or more cocks that can be opened and closed in the exterior material,
Before the step (1), (1a) having a step of opening the cock,
The step (1) is a step of injecting a polar solvent into the battery for processing,
Before the step (2), (2a) a step of discharging the polar solvent treatment liquid from the cock,
The step (2) is a step of drying the inside of the solvent treatment battery,
2. The method for regenerating an electrode of a lithium ion battery according to claim 1, wherein the step (3) is a step of re-injecting the liquid into the dry battery and sealing it.   The method for regenerating an electrode of a lithium ion battery according to claim 1, wherein ultrasonic treatment is performed when treating with the polar solvent.   The electrode regenerating method for a lithium ion battery according to claim 6 or 7, wherein the polar solvent is a polar solvent other than water.   The method for regenerating an electrode of a lithium ion battery according to any one of claims 6 to 8, wherein the polar solvent is an aprotic polar solvent.

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