JP2014203572A - Electrode for nonaqueous battery and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode for a nonaqueous battery, suppressing crystal growth of a binder and excellent in shock resistance performance, and a method for manufacturing the electrode for a nonaqueous battery.SOLUTION: A method for manufacturing an electrode for a nonaqueous battery comprises the steps of: mixing a slurry raw material containing an electrode active material, a semi crystalline polymer, and a solvent to prepare a slurry solution; and subjecting a current collector on which the slurry solution has been coated to heat treatment at a temperature of a crystallization temperature or more and less than a melting point of the semi crystalline polymer, thereby forming an electrode active material layer on a surface of the current collector.

Description

  The present invention relates to a nonaqueous battery electrode.

  In relation to solving the problems of energy and environmental conservation in modern society, expectations are gathered for the reduction of carbon dioxide emissions for the entire industry, and batteries are attracting attention as one of the solutions to these problems. It is. Among them, secondary batteries that can be used repeatedly are overwhelming with other batteries in terms of charge / discharge rate, self-discharge rate, load factor discharge characteristics, energy density, etc. Competing for battery research and development. In particular, non-aqueous electrolyte secondary batteries such as lithium ion secondary batteries are used not only for portable devices, but also for power supply devices for electric vehicles such as hybrid vehicles (HEV), electric vehicles (EV), and fuel cell vehicles. Are also being used. A nonaqueous electrolyte secondary battery generally includes a positive electrode obtained by applying a positive electrode active material or the like to a current collector, and a negative electrode obtained by applying a negative electrode active material or the like to a current collector. It has the structure connected through the electrolyte layer holding electrolyte gel. Then, for example, ions such as lithium ions are occluded / released in the electrode active material, whereby a charge / discharge reaction of the battery occurs.

  The electrode of such a non-aqueous electrolyte secondary battery usually uses a powdered metal, a carbon material, and a metal oxide as an electrode active material. Therefore, in order to produce the electrode, a polymer material that is a binder (or a binder or a binder) is required, and in general, an electrode slurry containing the raw material and the binder is prepared. The slurry is vacuum-dried to produce an electrode. However, when the amount of the binder in the electrode is small, the electrode active material component is easily peeled off, and when the amount of the binder is large, there is a problem of affecting the efficiency discharge characteristics.

  Therefore, Patent Document 1 is cited as a technique focusing on such a binder. Patent Document 1 discloses an electrode containing a predetermined amount of a γ phase of polyvinylidene fluoride as a binder. Thereby, it is said that the battery electrode with improved charge / discharge characteristics and life characteristics can be manufactured.

Japanese Patent Laid-Open No. 2005-72009

  The invention of Patent Document 1 is disclosed that when a compound having a high melting point is used as a binder, high charge / discharge characteristics are disclosed. However, the relationship between the binder composition in the electrode and the charge / discharge characteristics has not been clarified. This is in view of technology (paragraphs “0008” to “0012”). That is, it is known that polyvinylidene fluoride as a binder exists as three crystal phases of α, β, and γ, as described in paragraphs “0024” to “0025” of Patent Document 1. Yes. More specifically, when cooled and crystallized from a molten state, an α-type having no spontaneous polarization is formed, which is considered to be the most stable (SL Hsu, FJ Lu, DA Waldman). , And M. Muthukumar, Macromolecules 18, 2583 (1985)). In addition, it is known that it transitions to γ-type at 170 ° C. or higher and to β-type by high-pressure heat treatment (M. Kobayashi, K. Tashiro, and H. Tadokoro, Macromolecules 8, 158 (1978)). . Therefore, the fact that the infrared absorption peak fraction of the γ phase of polyvinylidene fluoride in the battery electrode described in Patent Document 1 is 0.35 to 1 means that the binder has been heat-treated at 170 ° C. or higher. Is grasped. Further, since the melting point of polyvinylidene fluoride is about 130 to 170 ° C., the heat treatment of the binder of Patent Document 1 is performed at a temperature higher than the melting point, or is vacuumed at 170 ° C. or higher after drying at 80 to 120 ° C. It is considered that the heat treatment is performed under the conditions (see Examples 1 to 7 in Patent Document 1). However, since the binder heat-treated at a temperature higher than the melting point is crystallized, there is a problem that the impact resistance performance of the electrode including the binder is lowered and the safety is impaired.

  Therefore, in order to solve such a problem, the present invention provides a nonaqueous battery electrode and a method for manufacturing the same, which reduces the crystal growth of the binder and has excellent impact resistance.

  The present inventors have found that the above-mentioned problems can be solved by heat treatment under predetermined conditions without heat treatment under vacuum conditions.

  Since the electrode manufacturing method according to the present invention does not require heat treatment in a vacuum environment, the production efficiency is improved and the cost is reduced.

  The electrode according to the present invention reduces the crystal growth of the binder and is excellent in impact resistance.

1 is a schematic cross-sectional view showing a basic configuration of a nonaqueous electrolyte secondary battery that is not a flat type (stacked type) bipolar type. 1 is a schematic cross-sectional view showing a basic configuration of a bipolar nonaqueous electrolyte secondary battery. It is the cross-sectional schematic which expanded and represented the electrode of preferable embodiment of this invention. It is a perspective view showing the appearance of a flat nonaqueous electrolyte secondary battery which is a preferred embodiment of the present invention. It is an image which shows the crystalline state of the semi-crystalline polymer of the electrode cross section by microscopic laser Raman spectroscopy in a present Example. It is a figure which shows the experimental result of a cycle test in a present Example. It is a figure which shows the experimental result of direct current | flow resistance (DCR) in a present Example. It is a figure which shows the experimental result of an impedance analysis in a present Example.

  In the first aspect of the present invention, a slurry raw material containing an electrode active material, a semi-crystalline polymer, and a solvent is mixed to prepare a slurry solution, and the current collector coated with the slurry solution is mixed with the semi-crystalline high And a step of forming an electrode active material layer on the surface of the current collector by heat treatment at a temperature higher than the crystallization temperature of the molecule and lower than the melting point.

  In general, as shown in Patent Document 1, an electrode of a non-aqueous electrolyte battery is manufactured by a so-called patch-type process in which heat treatment is performed in a vacuum environment (100 ppm or less) in order to avoid electrolysis of water. When an electrode is manufactured under such dry conditions of 100 ppm or less, the amount of moisture in the electrode can be suppressed, but on the other hand, the amorphous part in the binder crystal increases and as a result, the cycle life is shortened. There's a problem. However, the manufacturing method of the present invention can solve such problems and can provide a manufacturing method excellent in improving production efficiency and reducing costs because it is not necessary to perform heat treatment in a vacuum environment.

  The second aspect of the present invention includes a current collector, and an electrode active material layer formed on a surface of the current collector and including an electrode active material and a semicrystalline polymer. A low crystalline region of the semicrystalline polymer and a high crystalline region of the semicrystalline polymer are formed in the material layer, and an area ratio of the high crystalline region to the low crystalline region is 1 to 5. This is an electrode for a non-aqueous battery. Thereby, since the inside of the electrode maintains an appropriate crystal state, it can be expected to have an effect on the recycling life. Moreover, the electrode excellent in impact resistance can be provided.

  Hereinafter, for convenience, the electrode according to the present invention will be described, and then the electrode manufacturing method according to the present invention will be described in detail. As a preferred embodiment of the present invention, a non-aqueous electrolyte secondary battery will first be described as an example of a non-aqueous battery, but is not limited to the following embodiments. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. In addition, the dimensional ratios in the drawings are exaggerated for convenience of explanation, and may be different from the actual ratios.

  There is no particular limitation when distinguished by the form of the electrolyte of a non-aqueous electrolyte secondary battery (for example, a lithium ion secondary battery). For example, the present invention can be applied to any of a liquid electrolyte type battery in which a separator is impregnated with a nonaqueous electrolytic solution, a polymer gel electrolyte type battery also called a polymer battery, and a solid polymer electrolyte (all solid electrolyte) type battery. With respect to the polymer gel electrolyte and the solid polymer electrolyte, these can be used alone, or the polymer gel electrolyte or the solid polymer electrolyte can be used by impregnating the separator.

  FIG. 1 is a schematic cross-sectional view schematically showing a basic configuration of a non-aqueous electrolyte secondary battery (hereinafter also simply referred to as “stacked battery”) that is not a flat type (stacked type) bipolar type. As shown in FIG. 1, the stacked battery 10 a of this embodiment has a structure in which a substantially rectangular power generation element 21 in which a charge / discharge reaction actually proceeds is sealed inside a battery exterior material 29 that is an exterior body. Have. Here, the power generation element 21 has a configuration in which a positive electrode, an electrolyte layer 17, and a negative electrode are stacked. The positive electrode has a structure in which the positive electrode active material layer 13 is disposed on both surfaces of the positive electrode current collector 11. The negative electrode has a structure in which the negative electrode active material layers 15 are disposed on both surfaces of the negative electrode current collector 12. Specifically, the negative electrode, the electrolyte layer, and the positive electrode are laminated in this order so that one positive electrode active material layer 13 and the negative electrode active material layer 15 adjacent thereto face each other with the electrolyte layer 17 therebetween. . Thereby, the adjacent positive electrode, electrolyte layer, and negative electrode constitute one unit cell layer 19. Therefore, it can be said that the stacked battery 10a shown in FIG. 1 has a configuration in which a plurality of single battery layers 19 are stacked and electrically connected in parallel.

  In addition, although the positive electrode active material layer 13 is arrange | positioned only at one side in the outermost layer positive electrode collector 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. In addition, the arrangement of the positive electrode and the negative electrode is reversed from that in FIG. 1, so that the outermost layer negative electrode current collector is positioned on both outermost layers of the power generation element 21, and the outermost layer negative electrode current collector is disposed on one or both surfaces. A negative electrode active material layer may be disposed.

  The positive electrode current collector 11 and the negative electrode current collector 12 are respectively attached with a positive electrode current collector plate 25 and a negative electrode current collector plate 27 that are electrically connected to the respective electrodes (positive electrode and negative electrode), and are sandwiched between end portions of the battery exterior material 29. Thus, it has a structure led out of the battery exterior material 29. The positive electrode current collector plate 25 and the negative electrode current collector plate 27 are ultrasonically welded to the positive electrode current collector 11 and the negative electrode current collector 12 of each electrode, respectively, via a positive electrode lead and a negative electrode lead (not shown) as necessary. Or resistance welding or the like.

  FIG. 2 is a schematic cross-sectional view schematically showing a basic configuration of a bipolar nonaqueous electrolyte secondary battery (hereinafter also simply referred to as “bipolar battery”) 10b. The bipolar battery 10b shown in FIG. 2 has a structure in which a substantially rectangular power generation element 21 in which a charge / discharge reaction actually proceeds is sealed inside a laminate film 29 that is a battery exterior material.

  As shown in FIG. 2, the power generation element 21 of the bipolar battery 10 b has a positive electrode active material layer 13 that is electrically coupled to one surface of the current collector 11, and is formed on the opposite surface of the current collector 11. It has a plurality of bipolar electrodes 23 in which a negative electrode active material layer 15 that is electrically coupled is formed. Each bipolar electrode 23 is laminated via the electrolyte layer 17 to form the power generation element 21. The electrolyte layer 17 has a configuration in which an electrolyte is held at the center in the surface direction of a separator as a base material. At this time, the positive electrode active material layer 13 of one bipolar electrode 23 and the negative electrode active material layer 15 of another bipolar electrode 23 adjacent to the one bipolar electrode 23 face each other through the electrolyte layer 17. The bipolar electrodes 23 and the electrolyte layers 17 are alternately stacked. That is, the electrolyte layer 17 is interposed between the positive electrode active material layer 13 of one bipolar electrode 23 and the negative electrode active material layer 15 of another bipolar electrode 23 adjacent to the one bipolar electrode 23. ing.

  The adjacent positive electrode active material layer 13, electrolyte layer 17, and negative electrode active material layer 15 constitute one unit cell layer 19. Therefore, it can be said that the bipolar battery 10b has a configuration in which the single battery layers 19 are stacked. Further, for the purpose of preventing liquid junction due to leakage of the electrolytic solution from the electrolyte layer 17, a seal portion (insulating layer) 31 is disposed on the outer peripheral portion of the unit cell layer 19. A positive electrode active material layer 13 is formed only on one side of the positive electrode outermost layer current collector 11 a located in the outermost layer of the power generation element 21. The negative electrode active material layer 15 is formed only on one surface of the outermost current collector 11b on the negative electrode side located in the outermost layer of the power generation element 21. However, the positive electrode active material layer 13 may be formed on both surfaces of the outermost layer current collector 11a on the positive electrode side. Similarly, the negative electrode active material layer 15 may be formed on both surfaces of the outermost layer current collector 11b on the negative electrode side.

  Furthermore, in the bipolar battery 10b shown in FIG. 2, the positive electrode current collector plate 25 is disposed so as to be adjacent to the outermost layer current collector 11a on the positive electrode side, and this is extended and led out from the laminate film 29 which is a battery exterior material. ing. On the other hand, a negative electrode current collector plate 27 is disposed so as to be adjacent to the outermost layer current collector 11b on the negative electrode side.

  In the bipolar battery 10 b shown in FIG. 2, a seal portion 31 is usually provided around each single cell layer 19. The purpose of the seal portion 31 is to prevent the adjacent current collectors 11 in the battery from coming into contact with each other and a short circuit caused by a slight irregularity at the end of the unit cell layer 19 in the power generation element 21. Provided. By installing such a seal portion 31, long-term reliability and safety can be ensured, and a high-quality bipolar battery 10b can be provided.

  Note that the number of stacks of the unit cell layers 19 is adjusted according to a desired voltage. Further, in the bipolar battery 10b, the number of stacks of the single battery layers 19 may be reduced if a sufficient output can be ensured even if the battery is made as thin as possible. Even in the bipolar battery 10b, it is necessary to prevent external impact and environmental degradation during use. Therefore, the power generation element 21 is preferably sealed in a laminate film 29 that is a battery exterior material, and the positive electrode current collector plate 25 and the negative electrode current collector plate 27 are taken out of the laminate film 29.

  FIG. 3 is an enlarged schematic cross-sectional view showing a preferred embodiment of the electrode 65 used in the nonaqueous electrolyte secondary batteries 10 a and 10 b shown in FIGS. 1 and 2.

  The electrode 65 of this embodiment has an electrode active material layer 63 (positive electrode active material layer, negative electrode active material layer) formed on the current collector 62. Moreover, although the non-aqueous secondary battery was illustrated as an electrical device, it is not necessarily restricted to this, It can apply also to another type secondary battery (lithium ion secondary battery), and also a primary battery. Moreover, it can be applied not only to batteries but also to capacitors. In addition, in this specification, when describing as “current collector”, it may indicate all of the positive electrode current collector, the negative electrode current collector, and the bipolar battery current collector, or may refer to only one. is there. Similarly, in the case of describing as “electrode active material layer”, both the positive electrode active material layer and the negative electrode active material layer may be indicated, or only one of them may be indicated. Similarly, when describing as "electrode active material", both a positive electrode active material and a negative electrode active material may be pointed out, and only one side may be pointed out.

  Hereinafter, the electrode of this embodiment will be described in more detail.

[Current collector]
There is no particular limitation on the material constituting the current collector, but a metal is preferably used. Specifically, examples of the metal include aluminum, nickel, iron, stainless steel, titanium, copper, and other alloys. 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.

  The size of the current collector is determined according to the intended use of the battery. For example, if it is used for a large battery that requires a high energy density, a current collector having a large area is used. There is no particular limitation on the thickness of the current collector. The thickness of the current collector is usually about 1 to 100 μm.

[Electrode active material layer (positive electrode active material layer, negative electrode active material layer)]
The positive electrode active material layer or the negative electrode active material layer of the present embodiment includes an electrode active material and a semicrystalline polymer, and if necessary, a binder other than the semicrystalline polymer, a surfactant, a conductive additive, It further includes other additives such as an electrolyte (polymer matrix, ion conductive polymer, electrolyte solution, etc.) and a lithium salt for enhancing ion conductivity.

  Further, the semicrystalline polymer in the electrode active material layer according to the present invention forms a low crystalline region and a high crystalline region, and an area ratio of the high crystalline region to the low crystalline region is 1 to 1. 5. Furthermore, the area ratio of the high crystalline region to the low crystalline region is preferably 2 to 5, and more preferably 2.5 to 3. It is known that the low crystalline region (so-called amorphous portion) of the semicrystalline polymer in the electrode active material layer swells while having the effect of retaining the electrolytic solution, thereby reducing the cycle life of the battery. However, since the semi-crystalline polymer in the electrode according to the present invention is present in an appropriate ratio of the low crystalline region and the high crystalline region (area ratio is 1 to 5), the reduction in cycle life is suppressed / prevented. be able to.

  Further, in the electrode according to the present invention, the amount of the semi-crystalline polymer present on the current collector side on which the electrode active material layer is deposited is a half present on the counter electrode side (side in contact with the electrolyte layer) of the current collector. Preferably less than the amount of crystalline polymer. More preferably, the semicrystalline polymer is present only on the counter electrode side (the side in contact with the electrolyte layer) of the current collector. Particularly preferably, the semicrystalline polymer is present only on the counter electrode side (the side in contact with the electrolyte layer) of the current collector and in the vicinity of the surface portion of the electrode active material layer.

  The “low crystalline region” in the present specification has a half width w ° of the X-ray diffraction peak of w / h = 3 or more with respect to the peak intensity h, and is determined by XRD (Cu Kα) measurement. Further, the “high crystalline region” in the present specification means that the half width w ° of the X open diffraction peak is w / h = 0.5 or less with respect to the peak intensity h, and is determined by XRD (Cu Kα) measurement. doing.

The area ratio of the high crystalline region to the low crystalline region can be calculated by a known measurement method such as an electron backscattering pattern (EBSP) or analysis by a microscopic laser Raman spectrometer. In this specification, after cutting the electrode for a secondary battery in the thickness direction, a low crystalline region peak and a high crystalline region of a semi-crystalline polymer are obtained from a binder area per 1 μm ² of a cross section of the electrode using a microscopic laser Raman spectrometer. The occupation ratio of the crystalline region peak was calculated. In the examples, the state of the area of the low crystalline region and the high crystalline region of the semicrystalline polymer in the electrode is shown by image analysis.

  The content of the semi-crystalline polymer contained in the electrode active material layer according to the present invention is not particularly limited as long as the electrode active material is an amount that does not suppress the original activity of the active material. It is 1-10 mass% with respect to a substance layer, More preferably, it is 3-8 mass%.

  In addition, the composition of the electrode active material layer according to the present invention (active material, semi-crystalline polymer (role as a binder), and other binders, conductive assistants, etc., if necessary) is the electrode active material layer. When the material layer is 100 parts by mass, it is as follows. The amount of the semicrystalline polymer is preferably 1 to 10 parts by mass, more preferably 2 to 8 parts by mass. The amount of the electrode active material is preferably 70 to 99 parts by mass, and more preferably 75 to 85 parts by mass. The amount of the other binder (when a binder other than the semicrystalline polymer which is a binder is also mixed) is preferably 1 to 10 parts by mass, and more preferably 2 to 8 parts by mass. The amount of the conductive assistant is preferably 0 to 10 parts by mass, and more preferably 3 to 7 parts by mass.

  When the component in the electrode active material layer is in such a range, an electrode having appropriate crystallinity is obtained, and the effect can be expressed.

  For the thickness of the electrode active material layer according to the present invention, conventionally known knowledge about the battery can be referred to as appropriate. For example, the thickness is preferably 100 to 200 μm, more preferably 100 to 180 μm.

(Electrode active material)
The positive electrode active material layer preferably contains a positive electrode active material that can occlude ions during discharge and release ions during charge. Preferred examples of the positive electrode active material include composite oxides of lithium and transition metals, transition metal oxides, transition metal sulfides, PbO ₂ , AgO, or NiOOH. These may be used alone or in combination of two or more. Even it can be used.

Examples of the composite oxide of lithium and transition metal include Li-Mn composite oxides such as LiMnO ₂ and LiMn ₂ O ₄ , Li—Co composite oxides such as LiCoO ₂ , LiNiO ₂ , Li (Ni -Co-Mn) O ₂ and other Li-Ni complex oxides, LiFeO ₂ and other Li-Fe complex oxides, LiFePO4 and other complex phosphate compounds of lithium and transition metals, or lithium and transition metals Preferred examples include complex sulfuric acid compounds. Preferred examples of the transition metal oxide include V ₂ O ₅ , MnO ₂ , V ₂ MoO ₈ , and MoO ₃ . Preferred examples of the transition metal sulfide include TiS _{2 and} MoS ₂ . These positive electrode active materials can be used alone or in admixture of two or more. Preferably, from the viewpoint of capacity and output characteristics, a composite oxide of lithium and a transition metal is used as the positive electrode active material. Of course, positive electrode active materials other than those described above may be used. In addition, the positive electrode active material layer can contain the above-described optional components (conducting aid, binder, electrolyte, or the like depending on the purpose.

The negative electrode active material layer includes a negative electrode active material. In addition, the negative electrode active material layer preferably includes a negative electrode active material that releases ions during discharging and can store ions during charging. Examples of the negative electrode active material include metal oxides such as TiO, Ti ₂ O ₃ , TiO ₂ , or SnO ₂ , carbon materials such as graphite (graphite), soft carbon, and hard carbon, and lithium-transition metal composite oxides. (For example, Li ₄ Ti ₅ O ₁₂ ), metal materials, 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 or a lithium-transition metal composite oxide is used as the negative electrode active material. Further, the positive electrode active material layer can contain the above-mentioned optional components (conducting aid, binder, electrolyte, etc. depending on the purpose. Of course, other negative electrode active materials may be used. is there.

  Although the average particle diameter of each active material contained in each active material layer is not particularly limited, it is preferably 1 to 100 μm, more preferably 1 to 20 μm from the viewpoint of high output. Moreover, the said average particle diameter means the average particle diameter of a primary particle.

  The average particle diameter can be measured, for example, by SEM observation or TEM observation. The average particle diameter mentioned above is expressed by the absolute maximum length because the shape of the particles may not be uniform. Here, the absolute maximum length is an average of the maximum length L among the distances between any two points on the outline of the single bond. The value is an average value obtained from 10 single bonds.

(Semicrystalline polymer)
The positive electrode active material layer and / or the negative electrode active material layer includes a semicrystalline polymer. The semi-crystalline polymer according to the present invention is not particularly limited as long as it is a polymer that exhibits multiple melting behavior in thermal analysis measurement and plays a role as a binder. Moreover, the semi-crystalline polymer having the role of the binder is sufficient if it satisfies the following three points. (1) Keep the coating liquid in a stable slurry (having a dispersing action and a thickening action). (2) Particles such as active material powder and conductive filler powder are fixed to each other to maintain mechanical strength as an electrode, and to keep electrical contact between the particles. (3) Maintaining adhesive strength with respect to the current collector.

  Therefore, as the semicrystalline polymer, for example, at least one selected from the group consisting of polybutylene terephthalate, polyethylene terephthalate, polyvinylidene fluoride, polyethylene, polypropylene, polymethylpentene, and polybutene, or hydrogen of polyvinylidene fluoride It is also preferable to include compounds in which atoms are substituted with other halogen elements.

  The weight average molecular weight (Mw) of the semicrystalline polymer according to the present invention is preferably 5000 to 10000, and more preferably 7000 to 8000.

  In addition, the molecular weight based on this invention can be measured by well-known methods, such as MS spectrum method, a light-scattering method, a liquid chromatography, a gas chromatography. In this specification, it is the molecular weight measured by liquid chromatography, and various polymers used below are also measured by the same method.

  The crystallization temperature of the semicrystalline polymer according to the present invention is determined according to the semicrystalline polymer, but from the viewpoint of water removal, the crystallization temperature has a crystallization temperature in the range of 100 to 150 ° C. It is preferable to use a crystalline polymer.

  The glass transition temperature of the semicrystalline polymer according to the present invention is determined according to the semicrystalline polymer, and has a glass transition temperature in the range of −50 to 50 ° C. from the viewpoint of production environment. It is preferable to use a semicrystalline polymer.

  The “crystallization temperature” in the present specification is an endothermic peak showing multiple melting by DSC measurement and a peak on the high temperature side, and the “glass transition temperature” in this specification is multiple by DSC measurement. It is the low temperature side of the endothermic peak indicating melting.

  The crystallinity of the semicrystalline polymer according to the present invention is preferably 10% or more and 60% or less, and more preferably 40% or more and 60% or less.

  The crystallinity referred to here is weight crystallinity, and is measured using differential scanning calorimetry (DSC) under the condition of 1 atm and 25 ° C.

(Other binders)
The positive electrode active material layer and the negative electrode active material layer may contain other binders in addition to the semicrystalline polymer. The binder of the optional component used for the electrode active material layer is not particularly limited as long as it is hydrophobic, and examples thereof include the following materials.

  Polyether nitrile, polytetrafluoroethylene, polyacrylonitrile, polyimide, polyamide, ethylene-vinyl acetate copolymer, polyvinyl chloride, styrene / butadiene rubber (SBR), ethylene / propylene / diene copolymer, styrene / butadiene / styrene Block copolymers and their hydrogenated products, thermoplastic polymers such as styrene / isoprene / styrene block copolymers and their hydrogenated products, tetrafluoroethylene / hexafluoropropylene copolymer (FEP), tetrafluoroethylene Fluoroalkyl vinyl ether copolymer (PFA), ethylene-tetrafluoroethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), ethylene-chlorotrifluoroethylene copolymer (E Fluorine resins such as TFE) and polyvinyl fluoride (PVF), vinylidene fluoride-hexafluoropropylene-based fluoro rubber (VDF-HFP-based fluoro rubber), vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene-based fluoro rubber (VDF-) HFP-TFE fluorine rubber), vinylidene fluoride-pentafluoropropylene fluorine rubber (VDF-PFP fluorine rubber), vinylidene fluoride-pentafluoropropylene-tetrafluoroethylene fluorine rubber (VDF-PFP-TFE fluorine rubber) ), Vinylidene fluoride-perfluoromethyl vinyl ether-tetrafluoroethylene fluororubber (VDF-PFMVE-TFE fluororubber), vinylidene fluoride-chlorotrifluoroe Vinylidene fluoride-based fluorine rubbers such as Ren fluororubber (VDF-CTFE-based fluorine rubber), epoxy resins and the like. Among these, 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 independently and may use 2 or more types together.

  Examples of other additives that can be included in the electrode active material layer according to the present invention include surfactants, conductive assistants, electrolytes, and ion conductive polymers.

  As the surfactant, known cationic surfactants, anionic surfactants, and amphoteric surfactants can be used.

  The said conductive support agent means the additive mix | blended in order to improve the electroconductivity of a positive electrode active material layer or a negative electrode active material layer. Examples of the conductive auxiliary agent include carbon materials such as carbon black such as acetylene black, graphite, and carbon fiber. When the electrode active material layer contains a conductive additive, an electronic network inside the electrode active material layer is effectively formed, which can contribute to the improvement of the output characteristics of the battery.

The electrolyte is preferably an electrolyte salt (lithium salt), specifically, Li (C ₂ F ₅ SO ₂ ) ₂ N, LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiCF ₃ SO _{3 and the} like. It is done.

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

  Further, in the present invention, conductive assistants, electrolytes (polymer matrix, ion conductive polymer, electrolytic solution, etc.), lithium salts for improving ion conductivity, etc. that can be contained in the positive electrode active material layer and the negative electrode active material layer, etc. The mixing ratio of the other additives is not particularly limited. Those blending ratios can be adjusted by appropriately referring to known knowledge about the non-aqueous solvent secondary battery.

[Electrode manufacturing method]
The second of the present invention is a step of preparing a slurry solution by mixing a slurry raw material containing an electrode active material, a semicrystalline polymer, and a solvent (hereinafter also referred to as step 1), and applying the slurry solution. And a step of heat-treating the current collector at a temperature equal to or higher than the crystallization temperature of the semicrystalline polymer and less than the melting point to form an electrode active material layer on the surface of the current collector (hereinafter also referred to as step 2). It is a manufacturing method of an electrode.

  Crystallization of the semicrystalline polymer proceeds in the nonaqueous battery electrode by applying heat to the coating film formed on the surface of the current collector at a temperature higher than the crystallization temperature of the semicrystalline polymer and lower than the melting point. To do. However, the semi-crystalline polymer crystal growth can be suppressed due to the temperature that does not lead to melting. Thereby, the electrode whose area ratio of the said high crystalline area | region with respect to the low crystalline area | region of a semicrystalline polymer is 1-5 can be manufactured.

  In addition, since the manufacturing method of the present invention does not require heat treatment in a vacuum environment, it is possible to provide an electrode manufacturing method with improved production efficiency and cost reduction. That is, in the conventional method for producing an electrode for a non-aqueous battery, after preparing a slurry solution, the electrode is produced in the order of coating, drying, pressing, slitting, vacuum heat treatment, and electrolyte injection. However, in the present invention, by providing heat treatment at a constant temperature for controlling the crystal state of the electrode active material layer, heat treatment in a vacuum environment is not required, and the process from preparation of slurry solution to injection is consistently performed. It can be carried out.

  Hereinafter, each step will be described in detail.

(Process 1)
In step 1 according to the present invention, a slurry raw material containing an electrode active material, a semicrystalline polymer, and a solvent is mixed to prepare a slurry solution. Moreover, you may mix suitably arbitrary components, such as surfactant, a conductive support agent, electrolyte, or an ion conductive polymer, with a slurry raw material as needed. That is, the slurry raw material or slurry solution according to the present invention comprises the above-mentioned optional components such as an electrode active material, a solvent, a semi-crystalline polymer (role as a binder), and other binders and conductive assistants as necessary. Including.

  Generally, when producing a positive electrode active material layer and a negative electrode active material layer, a so-called slurry (coating liquid) obtained by adding and mixing layer constituents to a solvent is used. When the solvent is aqueous, the dispersibility of the layer constituents can be easily ensured. However, after the electrode active material layer is formed, water tends to remain in the layer, and there is a concern that the positive electrode active material or the electrolyte solution may be adversely affected by moisture. Therefore, there is an advantage in vacuum heat treatment using a non-aqueous solvent as much as possible as the solvent of the slurry. However, when a non-aqueous solvent is used as a solvent for the slurry, there is a difficulty that binders, active materials, and the like are difficult to dissolve and disperse in the solvent. One of the features of the present invention is that the binder is made into a specific non-crystalline polymer and the degree of crystal of the polymer is controlled at the stage of solidifying the non-crystalline polymer from the solution. This compensates for the problem of non-uniformity due to solubility and dispersibility.

  The method for preparing the slurry solution according to the present invention, that is, the method for mixing the electrode active material, the semicrystalline polymer, the solvent, and the optional components and the order of addition are not particularly limited. As the mixing method, each of them is pre-dispersed / dissolved in a solvent, other components are pre-dispersed / dissolved before the semi-crystalline polymer is dissolved, and pre-mixed with an electrode active material and / or a conductive aid. And a method such as adding in the middle of slurry production.

  The solvent according to the present invention is preferably an organic solvent, and is not particularly limited as long as it can disperse at least an electrode active material and a semicrystalline polymer. Specifically, N-methyl-2-pyrrolidone (NMP), dimethylformamide, dimethylacetamide, methylformamide, cyclohexane, hexane and the like can be used.

  The composition of the slurry solution according to the present invention is as follows when the solvent is 100 parts by mass. The amount of the semicrystalline polymer in the slurry solution is preferably 1 to 10 parts by mass, more preferably 1 to 7 parts by mass, and still more preferably 1 to 5 parts by mass. The amount of the electrode active material in the slurry solution is preferably 80 to 99 parts by mass, more preferably 85 to 99 parts by mass, and still more preferably 85 to 90 parts by mass. The amount of the other binder in the slurry solution (when the binder other than the semi-crystalline polymer as the binder is also mixed) is preferably 0.1 to 3 parts by mass, more preferably 0.1 to 2 parts by mass. Part. The amount of the conductive assistant in the slurry solution is preferably 1 to 5 parts by mass, more preferably 3 to 5 parts by mass, and still more preferably 4 to 5 parts by mass. If the slurry solution has such a composition, the target electrode can be produced.

  In other words, the slurry solution according to the present invention preferably contains 0.5 to 10% by mass of a semicrystalline polymer.

  Furthermore, the viscosity of the slurry solution is preferably 4000 to 10000 mPa · sec, more preferably 6000 to 8000 mPa · sec at 25 ° C. The viscosity of the slurry solution is preferably in the above range from the viewpoint of stabilizing the coating amount.

(Process 2)
Step 2 according to the present invention is a step of forming an electrode active material layer on the surface of the current collector by heat-treating the current collector coated with the slurry solution at a temperature equal to or higher than the crystallization temperature of the semicrystalline polymer and lower than the melting point.

  In the above step 2, the method of applying the slurry solution to the current collector is not particularly limited, and screen printing method, electrostatic spray coating method, ink jet method, doctor blade method, spray coating, flow coating method, etc. It can apply | coat on a collector with the well-known method of these. In addition, the concentration of the slurry solution, the number of coatings, the coating speed, and the like may be appropriately adjusted so that the obtained electrode active material layer has a desired thickness.

  In the step 2, it is preferable to perform a drying step separately from the heat treatment before the heat treatment at a temperature higher than the crystallization temperature of the semicrystalline polymer and lower than the melting point with respect to the coating film coated with the slurry solution.

  The drying step is preferably performed in a continuous hot air drying furnace. When the current collector coated with the slurry solution is dried in a continuous hot air drying oven, the temperature of the coating film can be increased in a short time as described later. It can be carried out. Specifically, it is preferable to heat and dry the coating film in an atmosphere maintained at a constant atmospheric temperature within a range of 80 to 150 ° C. by heating with hot air. Moreover, you may perform the below-mentioned heat processing simultaneously with heating and drying this coating film in the atmosphere hold | maintained to the constant atmospheric temperature within the range of 80-150 degreeC by the heating with a hot air.

  The electrode according to the present invention is formed by applying and drying the slurry solution as described above. The heat applied to the coating film in the drying process is also considered important in terms of pre-annealing in the next heat treatment. For example, in the case of a coating film containing PVdF, which is an example of a semicrystalline polymer, it has been reported that the crystal transition temperature changes when pre-annealed. Therefore, in the production method of the present invention, when a drying process is performed on the coating film coated with the slurry solution before the heat treatment at a temperature higher than the crystallization temperature of the semicrystalline polymer and lower than the melting point, the semicrystalline high in the electrode active material layer is obtained. It becomes easy to control the ratio between the high crystalline region and the low crystalline region of the molecule.

More preferably, for example, the drying step is preferably performed in a continuous hot air drying furnace using N ₂ gas or inert gas. Since the coating film of the slurry solution formed on the surface of the current collector is a porous body, it can efficiently transfer heat, has higher fluidity than air, and has excellent adsorptivity, such as N ₂ gas. It can be expected that the heat transfer effect will be improved by heating with the use of. In addition, a well-known thing can be used for the continuous hot air drying furnace which concerns on this invention, For example, hot-air drying furnaces, such as Unexamined-Japanese-Patent No. 10-160345, etc. are mentioned.

  Furthermore, it is more preferable to perform the drying step using infrared drying in combination with hot air drying. Compared with continuous hot air drying, infrared radiation heat transfer effect makes it easier to control the ratio of the high and low crystalline regions of the semi-crystalline polymer in the electrode active material layer. Can be lowered.

  Moreover, 0.0005 second-5 minutes are preferable, as for the time of the said drying process, 0.001 second-5 minutes are more preferable, It is more preferable that it is 0.005 second-1 minute, 0.01 second-30 minutes Even more preferably, it is seconds.

  In the heat treatment according to the present invention, it is preferable to apply heat to the electrode active material coating film that has undergone the drying step and press it in the film pressure direction. Thereby, the battery electrode according to the present invention is completed. At this time, the ratio of the high crystalline region and the low crystalline region of the semicrystalline polymer in the electrode active material layer can be controlled by adjusting the heat treatment conditions. In addition, when the heat treatment according to the present invention is performed at a temperature equal to or higher than the melting point of the semicrystalline polymer, the semicrystalline polymer in the electrode active material layer is crystallized and the impact resistance is lowered. On the other hand, when the temperature is lower than the crystallization temperature of the semicrystalline polymer, not only does the amorphous portion of the semicrystalline polymer in the electrode active material layer increase, but the electrode active material layer cannot be produced.

  Specific means and pressing conditions for the heat treatment are not particularly limited as long as the heat treatment is performed at a temperature not lower than the crystallization temperature of the semicrystalline polymer and lower than the melting point of the semicrystalline polymer. In addition, the ratio of the high crystalline region and the low crystalline region of the semicrystalline polymer of the electrode active material layer after the heat treatment can be appropriately adjusted so as to have a desired value. Specific examples of the pressing conditions include a hot press method, a roll method, a calendar roll press method, and the like. Therefore, the heat treatment according to the present invention is preferably pressed while applying heat.

  Therefore, in the pressing step, it is preferable to apply heat to the coating film at a temperature that is equal to or higher than the crystallization temperature of the semicrystalline polymer and less than the melting point (Tm) of the semicrystalline polymer. More specifically, in the case of pressing by a roll method or a hot press method, the temperature of the press surface (or roll surface) in direct contact with the electrode is equal to or higher than the crystallization temperature of the semicrystalline polymer, It is preferably less than the melting point (Tm) of the molecule.

  As a result, crystallization proceeds in the electrode (inside the coating film), but because the temperature does not reach the melting of the semicrystalline polymer, the crystal growth of the semicrystalline polymer is suppressed, and the high crystalline region And the ratio of the low crystalline region can be adjusted within a predetermined range.

  In general, in semicrystalline polymers and crystalline polymers, the melting of the polymer causes the crystalline portion to break and become fluid by heating or heating, and this temperature is the melting point of the semicrystalline polymer ( Tm). Moreover, since the polymer has a characteristic property indicating a variety of melting points (Tm), it is difficult to specify a specific value of each semicrystalline polymer. For example, the melting point (Tm) of polyvinylidene fluoride (PVdF), which is an example of a semicrystalline polymer that can be used in the present invention, has a melting point band of about 160 ° C. to 180 ° C. Similarly, polybutylene terephthalate (Tm 228 ° C), polyethylene terephthalate (Tm 260 ° C), polyvinylidene fluoride (Tm 134 ° C to 170 ° C), polyethylene (Tm 95 to 140 ° C), polypropylene (Tm 165 ° C), polymethyl Pentene (Tm 230-240 ° C) and polybutene (Tm 160-170 ° C). From the above, the melting point (Tm) of the semicrystalline polymer of the present invention is preferably 95 to 240 ° C, more preferably 130 to 240 ° C, and further preferably 160 to 180 ° C.

  On the other hand, as described above, the crystallization temperature of the semicrystalline polymer according to the present invention is an endothermic peak that exhibits multiple melting by DSC measurement and is the temperature of the highest temperature peak, and is a temperature range of 100 to 150 ° C. Is preferred.

  In addition, you may press, after apply | coating a slurry solution and laminating | stacking the electrode formed through drying after a drying process through a resin layer. The material used for the resin layer is not particularly limited as long as it is an insulating material that can achieve the above-described purpose and does not cause a side reaction (oxidation-reduction reaction) at the time of charge and discharge. Is mentioned. Olefin resins such as polyethylene (PE) and polypropylene (PP), polyethylene terephthalate (PET), polyether nitrile, polyacrylonitrile, polyimide, polyamide, cellulose, carboxymethyl cellulose (CMC), ethylene-vinyl acetate copolymer, polychlorinated Vinyl, styrene / butadiene rubber (SBR), isoprene rubber, butadiene rubber, ethylene / propylene rubber, ethylene / propylene / diene copolymer, styrene / butadiene / styrene block copolymer and hydrogenated products thereof, styrene / isoprene / styrene Thermoplastic polymers such as block copolymers and hydrogenated products thereof, polyvinylidene fluoride (PVdF), polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP), Lafluoroethylene (PTFE), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), ethylene / tetrafluoroethylene copolymer (ETFE), polychloro Fluoropolymers such as trifluoroethylene (PCTFE), ethylene / chlorotrifluoroethylene copolymer (ECTFE), polyvinyl fluoride (PVF), vinylidene fluoride-hexafluoropropylene-based fluororubber (VDF-HFP-based fluororubber), Vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene fluorine rubber (VDF-HFP-TFE fluorine rubber), vinylidene fluoride-pentafluoropropylene fluorine rubber (VDF) PFP-based fluororubber), vinylidene fluoride-pentafluoropropylene-tetrafluoroethylene-based fluororubber (VDF-PFP-TFE-based fluororubber), vinylidene fluoride-perfluoromethylvinylether-tetrafluoroethylene-based fluororubber (VDF-PFMVE) -TFE fluorine rubber), vinylidene fluoride-chlorotrifluoroethylene fluorine rubber (VDF-CTFE fluorine rubber) and other vinylidene fluoride fluorine rubber, epoxy resin, (meth) acrylic resin, aramid, etc. . Among these, polyvinylidene fluoride, polyimide, styrene / butadiene rubber, carboxymethyl cellulose, polypropylene, polytetrafluoroethylene, polyacrylonitrile, and polyamide are more preferable. The materials used for these suitable resin layers 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 resin layer. The material used for these resin layers may be used independently and may use 2 or more types together. However, it goes without saying that the material used for the resin layer is not limited thereto. Among these, for example, polyvinylidene fluoride (PVdF), methacrylic resin, olefinic resin, and the like can be applied to any of them because they are strong against both the positive electrode side and the negative electrode side. SBR or the like is preferably used on the negative electrode side because it is strong against the negative electrode potential. Furthermore, PTFE is preferably used on the positive electrode side because it is resistant to the positive electrode potential.

  By pressing with such a resin layer interposed, the semi-crystalline polymer contained in the electrode active material layer is thermally welded to obtain an adhesive effect with the separator. As a result, the stack can be prevented from shifting in the stacking process, and the productivity is improved.

  The time of the pressing step according to the present invention is preferably 0.0005 seconds to 5 minutes, more preferably 0.001 seconds to 5 minutes, further preferably 0.005 seconds to 1 minute, 0.01 seconds to More preferably, it is 30 seconds.

  Therefore, in the production method according to the present invention, the total of the drying process time and the heat treatment time is preferably 0.001 seconds to 10 minutes, more preferably 0.001 seconds to 5 minutes, and 0.01 seconds to 1 More preferably, it is minutes.

  After performing the heat treatment according to the present invention, it is preferable to further perform a cooling treatment. The cooling treatment is performed by cooling the surface temperature of the electrode to 25 ° C. in 0.1 to 2 minutes using an air-cooled blower device, and It is preferable to maintain the electrode at room temperature, 25 ° C.

  From the above, a preferred embodiment of the step 2 according to the present invention is to apply a slurry solution to at least one surface of the current collector surface to form a coating film, and then perform a drying step at 80 to 150 ° C., This is a step of forming an electrode active material layer by heat treatment at a temperature equal to or higher than the crystallization temperature of the semicrystalline polymer and lower than the melting point. In addition, when the drying process is performed using a continuous hot air drying furnace in which gas is blown while moving the object to be dried on the conveyor as described above, the crystallization temperature and melting point of the semicrystalline polymer contained in the coating film are also affected. Although it depends, the drying process and the heat treatment can be performed simultaneously while keeping the temperature constant. That is, when the drying process is performed by blowing the gas while moving the current collector on which the coating film, which is the object to be dried, is moved on the conveyor, the temperature of the drying process and the heat treatment temperature are kept constant in the continuous hot air drying furnace at the same time or immediately after. The pressing process can be performed while keeping

  Thereby, since the heat treatment in a vacuum environment is not required and the process from preparation of the slurry solution to liquid injection can be performed consistently, the production efficiency is greatly improved as compared with the conventional method.

  The lithium ion secondary battery described above is characterized by an electrode. Hereinafter, other main components will be described.

[Electrolyte layer]
The electrolyte constituting the electrolyte layer has, for example, a function as a lithium ion carrier. The electrolyte is not particularly limited as long as it can exhibit such a function, but a liquid electrolyte or a polymer electrolyte is used.

The liquid electrolyte preferably 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 used include carbonates such as ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), and diethyl carbonate (DEC). As the lithium _{salt, Li (CF 3 SO 2)} 2 N, Li (C 2 F 5 SO 2) 2 N, LiPF 6, LiBF 4, LiClO 4, LiAsF 6, LiTaF such 6, LiCF ₃ SO ₃ A compound that can be added to the active material layer of the electrode can be similarly employed.

  On the other hand, the polymer electrolyte is classified into a gel polymer electrolyte containing an electrolytic solution (gel electrolyte) and an intrinsic polymer electrolyte containing no electrolytic solution.

  The gel polymer electrolyte has a configuration in which the liquid electrolyte is injected into a matrix polymer (host polymer) made of an ion conductive polymer. The use of a gel polymer electrolyte as the electrolyte is superior in that the fluidity of the electrolyte is lost and the ion conductivity between the layers is easily cut off. Examples of the ion conductive polymer used as the matrix polymer (host polymer) include polyethylene oxide (PEO), polypropylene oxide (PPO), and copolymers thereof. In such polyalkylene oxide polymers, electrolyte salts such as lithium salts can be well dissolved.

  The intrinsic polymer electrolyte has a structure in which a lithium salt is dissolved in the above matrix polymer and does not contain an organic solvent. Therefore, by using an intrinsic polymer electrolyte as the electrolyte, there is no fear of liquid leakage from the battery, and the battery reliability can be improved.

  The matrix polymer of the gel electrolyte or the intrinsic polymer electrolyte can exhibit excellent mechanical strength by forming a crosslinked structure. In order to form a crosslinked structure, thermal polymerization, ultraviolet polymerization, radiation polymerization, electron beam polymerization, etc. are performed on a polymerizable polymer (for example, PEO or PPO) for forming a polymer electrolyte using an appropriate polymerization initiator. A polymerization treatment may be performed. These electrolytes may be used alone or in combination of two or more.

  In addition, when an electrolyte layer is comprised from a liquid electrolyte or a gel electrolyte, you may use a separator for an electrolyte layer. Specific examples of the separator include a microporous film made of a polyolefin such as polyethylene or polypropylene, a hydrocarbon such as polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP), glass fiber, or the like.

[Seal part]
The seal part 31 is a member peculiar to the bipolar battery 10 b shown in FIG. 2, and is disposed on the outer peripheral part of the single battery layer 19 for the purpose of preventing leakage of the electrolyte layer 17. In addition to this, it is possible to prevent current collectors adjacent in the battery from coming into contact with each other and a short circuit due to a slight unevenness at the end of the laminated electrode. In the form shown in FIG. 2, the seal portion 31 is sandwiched between the respective current collectors 11 constituting the two adjacent single battery layers 19 so as to penetrate the outer peripheral edge portion of the separator that is the base material of the electrolyte layer 17. Further, it is arranged on the outer peripheral portion of the unit cell layer 19. Examples of the constituent material of the seal portion 31 include polyolefin resins such as polyethylene and polypropylene, epoxy resins, rubber, and polyimide. Of these, polyolefin resins are preferred from the viewpoints of corrosion resistance, chemical resistance, film-forming properties, economy, and the like.

[Positive electrode current collector and negative electrode current collector]
The material which comprises a current collector plate (25, 27) is not restrict | limited in particular, The well-known highly conductive material conventionally used as a current collector plate for non-aqueous batteries or a current collector plate for lithium ion secondary batteries Can be used. As a constituent material of the current collector plate, for example, metal materials such as aluminum, copper, titanium, nickel, stainless steel (SUS), and alloys thereof are preferable. From the viewpoint of light weight, corrosion resistance, and high conductivity, aluminum and copper are more preferable, and aluminum is particularly preferable. Note that the positive electrode current collector plate 25 and the negative electrode current collector plate 27 may be made of the same material or different materials. Further, as shown in FIG. 2, the outermost layer current collector (11a, 11b) may be extended to form a current collector plate, or a separately prepared tab may be connected to the outermost layer current collector.

[Positive lead and negative lead]
Moreover, although illustration is abbreviate | omitted, you may electrically connect between the collector 11 and the current collector plates (25, 27) via a positive electrode lead or a negative electrode lead. As a constituent material of the positive electrode and the negative electrode lead, materials used in known nonaqueous batteries and secondary batteries can be similarly employed. In addition, heat-shrinkable heat-shrinkable parts are removed from the exterior so that they do not affect products (for example, automobile parts, especially electronic devices) by touching peripheral devices or wiring and causing leakage. It is preferable to coat with a tube or the like.

[Battery exterior materials]
As the battery exterior material 29, a 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. In addition, said nonaqueous battery and a lithium ion secondary battery can be manufactured with a conventionally well-known manufacturing method.

[External configuration of non-aqueous battery]
FIG. 4 is a perspective view showing the appearance of a flat lithium ion secondary battery which is a typical embodiment of a nonaqueous battery.

  As shown in FIG. 4, the flat lithium ion secondary battery 50 has a rectangular flat shape, and a positive electrode tab 58 and a negative electrode tab 59 for taking out electric power are drawn out from both sides thereof. Yes. The power generation element 57 is encased by the battery outer packaging material 52 of the lithium ion secondary battery 50, and the periphery thereof is heat-sealed. The power generation element 57 is sealed with the positive electrode tab 58 and the negative electrode tab 59 pulled out to the outside. Has been. Here, the power generation element 57 corresponds to the power generation element 21 of the lithium ion secondary battery 10 shown in FIGS. 1 and 2 described above. The power generation element 57 is formed by laminating a plurality of single battery layers (single cells) 19 including a positive electrode (positive electrode active material layer) 13, an electrolyte layer 17, and a negative electrode (negative electrode active material layer) 15.

  The lithium ion secondary battery is not limited to a stacked flat shape. The wound lithium ion secondary battery may have a cylindrical shape, or may have a shape that is a flattened rectangular shape by deforming such a cylindrical shape. There is no particular limitation. In the said cylindrical shape thing, a laminate film may be used for the exterior material, and the conventional cylindrical can (metal can) may be used, for example, It does not restrict | limit. Preferably, the power generation element is covered with an aluminum laminate film. By the said form, weight reduction can be achieved.

  Also, the removal of the tabs 58 and 59 shown in FIG. 4 is not particularly limited. The positive electrode tab 58 and the negative electrode tab 59 may be pulled out from the same side, or the positive electrode tab 58 and the negative electrode tab 59 may be divided into a plurality of parts and taken out from each side, as shown in FIG. It is not limited to. Further, in a wound type lithium ion battery, instead of a tab, for example, a terminal may be formed using a cylindrical can (metal can).

  The lithium ion secondary battery is used as a power source for driving a vehicle or an auxiliary power source that requires a high volume energy density and a high volume output density as a large capacity power source for an electric vehicle, a hybrid electric vehicle, a fuel cell vehicle, and a hybrid fuel cell vehicle. It can be suitably used.

  Moreover, although the said embodiment illustrated the lithium ion battery as a non-aqueous battery which concerns on this invention, it is not necessarily restricted to this, It can apply also to another type secondary battery, Furthermore, a primary battery. Needless to say.

  The electrode according to the present invention described above will be described in more detail using the following examples and comparative examples, but is not limited to the following examples.

(Example 1)
"Production of electrodes"
(Preparation of positive electrode)
Lithium manganate (LiMn ₂ O ₄ ), lithium nickelate (LiNiO ₂ ), and acetylene black each in predetermined amounts (80% by mass, 10% by mass with respect to the total amount of positive electrode slurry solids (positive electrode active material layer)) 5% by mass). These were thoroughly stirred with a planetary mixer to obtain a mixed powder. After that, a mixed powder obtained by dissolving a predetermined amount (5% by mass with respect to the total amount of positive electrode slurry solids) of PVdF in NMP (N-methyl-2-pyrrolidone) as a binder (semicrystalline polymer) In addition to the body, it was kneaded and thickened with NMP. The viscous solution (slurry for positive electrode) of this sample is uniformly applied on an aluminum foil (thickness 20 μm) by a slit die coater, and the temperature is set to 110 ° C. to 130 ° C. in order to evaporate NMP contained in the electrode. Drying was performed for 1 minute and 30 seconds in the set continuous hot air drying furnace.

Thereafter, a stereotaxic press is performed at a speed of 5 m / min using a Φ150 × 400 L oil-catalyzed hot press with a roll surface temperature of 150 ° C. so that the electrode density is 2.5 g / cm ^3. Was made.

(Preparation of negative electrode)
Carbon black, graphite, and PVdF as a semi-crystalline polymer are respectively weighed in predetermined amounts (90% by mass, 5% by mass, and 5% by mass in order of the total amount of negative electrode slurry solids (negative electrode active material layer)). I took it. These were added to NMP as a solvent and mixed with a desktop planetary mixer for a total of 5 hours to prepare a slurry for a negative electrode. Next, the negative electrode slurry was coated on a copper foil (thickness 10 μm) with a desktop coater, and a continuous hot air drying furnace set at a temperature of 110 ° C. to 130 ° C. to evaporate NMP contained in the electrode. Drying was performed for 1 minute 30 seconds.

After that, using a Φ150 × 400 L oil-catalyzed hot press with a roll surface temperature of 150 ° C. so that the electrode density is 1.5 g / cm ^3, a stereotaxic press is performed at a speed of 5 m / min. Was made.

(Production of battery)
The positive electrode active material layer portion was cut to 68 mm × 68 mm, and the negative electrode active material layer portion was cut to 70 mm × 70 mm, and the current extraction metal tab was ultrasonically welded. Thereafter, a polypropylene microporous membrane separator having a thickness of 25 μm was sandwiched between the positive electrode and the negative electrode so that the positive electrode and negative electrode active material layers were opposed to each other, and inserted into a bag made of an aluminum-resin laminate sheet. Lithium hexafluorophosphate (LiPF ₆ ) was dissolved in a solvent in which ethylene carbonate and diethylene carbonate were mixed at a volume ratio of 1: 2 so that the concentration was 1.0 mol / liter. And the prepared electrolyte solution was poured, and it sealed by heat sealing after that, and was set as the battery (sample 1).

(Comparative Example 1)
A predetermined amount of each of lithium manganate, lithium nickelate, and acetylene black was weighed out in the same amount as in Example 1 and stirred well with a planetary mixer to obtain a mixed powder. Thereafter, the same amount of PVdF as in Example 1 dissolved in NMP as a binder (semicrystalline polymer) was added to the mixed powder and kneaded to make it viscous with NMP. The viscous solution of this sample (slurry for positive electrode) was uniformly applied on an aluminum foil (thickness 20 μm) with a slit die coater to evaporate NMP. Then, the positive electrode was manufactured by pressing at room temperature (27 ° C.) so that the electrode density was 2.5 g / cm ³ .

Carbon black, graphite, and PVdF as a binder were weighed out in the same amount as in Example 1, added to NMP as a solvent, and stirred and mixed for a total of 5 hours with a desktop planetary mixer to prepare a negative electrode slurry. . Next, the slurry for negative electrode was coated on a copper foil (thickness 10 μm) with a desktop coater to evaporate NMP contained in the electrode. Thereafter, a negative electrode was produced by pressing at room temperature (27 ° C.) so that the electrode density was 1.5 g / cm ³ . Thereafter, a battery was produced in the same manner as in Example 1.

(Comparative Example 2)
Weigh out a predetermined amount of each of lithium manganate, lithium nickelate, and acetylene black in the same amount as in Example 1, thoroughly agitate with a planetary mixer, and then use the same amount as in Example 1 as a binder (semicrystalline polymer). A solution obtained by dissolving PVdF in NMP (N-methyl-2-pyrrolidone) was added to the mixed powder and kneaded to make it viscous with NMP. The viscous solution of this sample was uniformly applied on an aluminum foil (thickness 20 μm) with a slit die coater to evaporate NMP. Then, it pressed at normal temperature (27 degreeC) so that an electrode density might become a density of 2.5 g / cm < ³ >, and the positive electrode was dried with the 90 degreeC vacuum dryer for one day, and the positive electrode was manufactured.

Carbon black, graphite, and PVdF as a binder were weighed out in the same amount as in Example 1, added to NMP as a solvent, and stirred and mixed for a total of 5 hours with a desktop planetary mixer to prepare a negative electrode slurry. . Next, the slurry for negative electrode was coated on a copper foil (thickness 10 μm) with a desktop coater to evaporate NMP contained in the electrode. Then, it pressed at normal temperature (27 degreeC) so that an electrode density might become a density of 1.5 g / cm < ³ >, and it dried for one day with a 90 degreeC vacuum dryer, and manufactured the negative electrode. Thereafter, a battery was produced in the same manner as in Example 1.

"Evaluation of electrodes for nonaqueous batteries"
(Crystallinity evaluation)
The cross section of the electrode obtained above was measured using a microscopic laser Raman spectrometer, and the occupation ratio of the high crystal component peak and the low crystal component peak was calculated from the binder area per 1 μm ^{2 of} the electrode cross section. The result is shown in FIG. FIG. 5A shows a comparison of the crystal states of the binders in the cross sections of the electrodes of Example 1 and Comparative Example 1 (a semi-crystalline polymer in Example 1 and a binder in the Comparative Example). Further, FIG. 5B shows an image of the binder in the cross section of the electrode of Example 1 (the image on the left side of FIG. 5A) from the current collector side with respect to the film thickness direction. It is a figure which shows having divided into three of a part, a center part, and a surface part. In FIG. 5B, the area ratio of the high crystal region to the low crystal region in each section was calculated. The results are shown in the following table.

  The area ratio of the high crystal region to the low crystal region of the semicrystalline polymer contained in the entire electrode active material layer of the electrode of Example 1 was 2.

(Cycle test)
The charge / discharge test of the battery prepared above was performed using a charge / discharge device manufactured by Nippon Steel ELEX, and the charge was performed at a constant temperature until the measurement temperature reached 55 ° C. and reached 4.15 V at a current value of 1 C, and then the charge current. The battery was charged at a constant voltage of 4.15 V until the current reached 0.5 mA. The discharge was repeated by repeating the operation of discharging to 2.5 V at a current value of 1C. The result is shown in FIG.

(Evaluation of direct current resistance (DCR))
The battery prepared above was fully charged (4.15 V), and then a constant current discharge was performed at 25 ° C. and a current rate of 3 C for 30 seconds. The resistance value was obtained by dividing by the value of current flowed from the voltage drop value. The result is shown in FIG.

(Impedance analysis)
The impedance measurement in the charge state of the battery obtained above was performed, and the measurement was performed at a measurement frequency unit of 0.1 to 10000 Hz. The result is shown in FIG.

(Example 2)
"Production of electrodes"
(Preparation of positive electrode)
Lithium manganate (LiMn ₂ O ₄ ), lithium nickelate (LiNiO ₂ ), and acetylene black each in predetermined amounts (80% by mass, 10% by mass with respect to the total amount of positive electrode slurry solids (positive electrode active material layer)) 5% by mass). These were thoroughly stirred with a planetary mixer to obtain a mixed powder. After that, a mixed powder obtained by dissolving a predetermined amount (5% by mass with respect to the total amount of positive electrode slurry solids) of PVdF in NMP (N-methyl-2-pyrrolidone) as a binder (semicrystalline polymer) In addition to the body, it was kneaded and thickened with NMP. The viscous solution (slurry for positive electrode) of this sample is uniformly applied on an aluminum foil (thickness 20 μm) by a slit die coater, and the temperature is set to 110 ° C. to 130 ° C. in order to evaporate NMP contained in the electrode. Drying was performed for 1 minute and 30 seconds while using an infrared heater in a set hot air drying oven.

Thereafter, a stereotaxic press is performed at a speed of 5 m / min using a Φ150 × 400 L oil-catalyzed hot press with a roll surface temperature of 110 ° C. so that the electrode density is 2.5 g / cm ^3. Was made.

(Preparation of negative electrode)
Carbon black, graphite, and PVdF as a semi-crystalline polymer are respectively weighed in predetermined amounts (90% by mass, 5% by mass, and 5% by mass in order of the total amount of negative electrode slurry solids (negative electrode active material layer)). I took it. These were added to NMP as a solvent and mixed with a desktop planetary mixer for a total of 5 hours to prepare a slurry for a negative electrode. Next, the slurry for the negative electrode was coated on a copper foil (thickness 10 μm) with a desktop coater, and in a hot air drying furnace set at a temperature of 110 ° C. to 130 ° C. in order to evaporate NMP contained in the electrode. Drying was performed for 1 minute and 30 seconds while using an infrared heater.

Thereafter, a stereotaxic press is performed at a speed of 5 m / min using a Φ150 × 400 L oil-catalyzed hot press with a roll surface temperature of 110 ° C. so that the electrode density is 1.5 g / cm ^3. Was made. Thereafter, a battery was produced in the same manner as in Example 1.

(Cycle test)
The charge / discharge test of the battery produced above was performed using a charge / discharge device manufactured by Nippon Steel Elex, and was charged at a constant current until the measurement temperature reached 25 ° C. and reached 4.15 V at a current value of 1 C, and then the charge current. The battery was charged at a constant voltage of 4.15 V until the current reached 0.5 mA. For discharging, an operation of discharging to 2.5 V at a current value of 1 C (this is defined as one cycle) was repeated for 100 cycles or more. The results are shown in Table 2. As a result, the same capacity retention rate could be obtained even when the press temperature was lowered to 110 ° C. In addition, the capacity maintenance rate in 100 cycles was calculated | required by the following formula (Note that the initial discharge capacity is the discharge capacity in the first cycle).

10a, 10b, 50 non-aqueous battery,
11 positive electrode current collector,
12 negative electrode current collector,
13 positive electrode active material layer,
15 negative electrode active material layer,
17 electrolyte layer,
19 cell layer,
21, 57 power generation element,
25 positive current collector,
27 negative current collector,
29, 52 Battery exterior material,
31 seal part,
58 positive electrode tab,
59 Negative electrode tab,
62 current collector,
63 active material layer,
65 electrodes.

Claims (5)

Mixing a slurry raw material containing an electrode active material, a semi-crystalline polymer, and a solvent to prepare a slurry solution;
And a step of heat-treating the current collector coated with the slurry solution at a temperature equal to or higher than the crystallization temperature of the semicrystalline polymer and lower than the melting point to form an electrode active material layer on the surface of the current collector. A method for producing a water battery electrode.   The method for producing an electrode for a non-aqueous battery according to claim 1, wherein the slurry solution contains 0.5 to 10% by mass of a semicrystalline polymer.   The semicrystalline polymer includes polybutylene terephthalate, polyethylene terephthalate, polyvinylidene fluoride, a compound in which a hydrogen atom of polyvinylidene fluoride is substituted with another halogen element, polyethylene, polypropylene, polymethylpentene, and polybutene The method for producing an electrode for a non-aqueous battery according to claim 1 or 2, wherein at least one selected from the group consisting of:   An electrode active material layer formed on a surface of the current collector and including an electrode active material and a semi-crystalline polymer, and the semi-crystalline high in the electrode active material layer Non-water characterized in that a low crystalline region of a molecule and a high crystalline region of the semicrystalline polymer are formed, and an area ratio of the high crystalline region to the low crystalline region is 1 to 5. Battery electrode. The step of forming the electrode active material layer includes a drying step,
The method for producing an electrode for a nonaqueous battery according to any one of claims 1 to 3, wherein the drying step uses both infrared drying and hot air drying.