JP2007258160A - Lithium ion secondary battery and battery pack using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means capable of improving heat resistance of a separator without degrading volume energy density of a battery, in a lithium ion secondary battery. <P>SOLUTION: This battery has at least one electric cell layer composed by stacking a positive electrode composed by forming a positive electrode active material layer containing a positive electrode active material on a surface of a collector, an electrolyte layer containing an electrolyte, and a negative electrode composed by forming a negative electrode active material layer containing a negative electrode active material on a surface of a collector in that order. In the battery, the separator formed out of insulating particles each having a particle diameter of 10-30 μm is further included in the electrolyte layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a lithium ion secondary battery. In particular, the present invention relates to an improvement for improving the durability of a lithium ion secondary battery.

  In recent years, in order to cope with air pollution and global warming, reduction of the amount of carbon dioxide has been strongly desired. In the automobile industry, there is a great expectation for reducing carbon dioxide emissions by introducing electric vehicles (EV) and hybrid electric vehicles (HEV), and the development of secondary batteries for motor drive that holds the key to commercialization of these is thriving. Has been done.

  As a secondary battery for driving a motor, a lithium ion secondary battery having the highest theoretical energy among all the batteries is attracting attention, and is currently being developed rapidly. Generally, a lithium ion secondary battery includes a positive electrode in which a positive electrode active material or the like is applied to both surfaces of a positive electrode current collector using a binder, and a negative electrode in which a negative electrode active material or the like is applied to both surfaces of a negative electrode current collector using a binder. Have battery elements (so-called “single cells”) connected via an electrolyte layer. In addition, for the purpose of extracting electric power to the outside, electrode terminals (a positive terminal and a negative terminal) are electrically connected to the battery element, and the battery element is further provided with resin sheets on both sides of a foil made of a light metal such as aluminum. In general, the electrode terminals are accommodated in a laminated metal-resin laminate sheet so as to lead out (see, for example, Patent Document 1).

  Here, the electrolyte layer of the lithium ion secondary battery generally has a configuration in which an electrolyte (liquid electrolyte or gel electrolyte) is held in a separator. At this time, the separator used for forming the electrolyte layer is required to have various characteristics. For example, a lithium ion secondary battery has a high energy density, and the battery temperature rise accompanying charging / discharging is relatively large. Therefore, when the heat resistance of the separator is low, the separator melts as the temperature of the battery rises, and there is a possibility that the positive and negative electrodes of the unit cell are short-circuited. Thus, one of the characteristics required for the separator is excellent heat resistance.

For the purpose of obtaining a separator having excellent heat resistance, a technique for including a heat-resistant nitrogen-containing aromatic polymer and ceramic powder in the separator has been proposed (see, for example, Patent Document 2). Specifically, in this document, a layer made of a resin such as an aromatic polyaramid or an aromatic polyimide containing ceramic powder such as alumina is formed on both surfaces of a base material made of polyolefin or polyester, and a non-aqueous electrolyte is formed. A technique for manufacturing a battery separator is disclosed.
JP 2001-52748 A Japanese Patent Laid-Open No. 2000-30686, Claim 2, Example

  If the separator described in Patent Document 2 is employed in a lithium ion secondary battery, the heat resistance of the separator can be improved. However, since the ceramic-containing resin layer is further formed on both surfaces of the base material, the thickness of the separator increases, and as a result, there is a problem that the volume energy density of the lithium ion secondary battery decreases.

  Therefore, an object of the present invention is to provide means capable of improving the heat resistance of a separator in a lithium ion secondary battery without causing a decrease in the volume energy density of the battery.

  The present inventors have intensively studied to solve the above problems. As a result, it was found that the separator of the lithium ion secondary battery can be made of insulating particles having a relatively small particle diameter, thereby improving the heat resistance of the separator while ensuring a sufficient volume energy density. The present invention has been completed.

  That is, the present invention provides a positive electrode in which a positive electrode active material layer containing a positive electrode active material is formed on the surface of a current collector, an electrolyte layer containing an electrolyte, and a negative electrode active material layer containing a negative electrode active material. A battery having at least one single cell layer formed by laminating a negative electrode formed on the surface in this order, wherein the electrolyte layer further includes a separator made of insulating particles having a particle diameter of 10 nm to 30 μm. It is a lithium ion secondary battery characterized by including.

  The present invention also includes a step of producing a positive electrode in which a positive electrode active material layer is formed on the surface of a current collector by applying a positive electrode active material slurry containing a positive electrode active material to the surface of the current collector and drying the slurry. A step of producing a negative electrode in which a negative electrode active material layer is formed on the surface of a current collector by applying and drying a negative electrode active material slurry containing a negative electrode active material on the surface of the current collector; and the positive electrode active material layer Alternatively, a step of forming a coating film by applying an insulating particle slurry containing insulating particles to at least one surface of the negative electrode active material layer, and the positive electrode active material layer and the negative electrode active material layer face each other. And a step of laminating the positive electrode and the negative electrode.

  According to the present invention, in a lithium ion secondary battery, the heat resistance of the separator can be improved without causing a decrease in the volume energy density of the battery.

  Embodiments of the present invention will be described below.

(First embodiment)
In the present embodiment, the positive electrode active material layer including the positive electrode active material is formed on the surface of the current collector, the electrolyte layer including the electrolyte, and the negative electrode active material layer including the negative electrode active material is the surface of the current collector. And a negative electrode formed on the battery and having at least one single battery layer laminated in this order, wherein the electrolyte layer further includes a separator made of insulating particles having a particle diameter of 10 nm to 30 μm. The present invention relates to a lithium ion secondary battery.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the technical scope of the present invention should be determined based on the description of the scope of claims, and 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.

  FIG. 1 is a cross-sectional view showing an outline of the lithium ion secondary battery of the first embodiment. The technical scope of the present invention is not limited to the illustrated embodiment.

  The lithium ion secondary battery 10 of this embodiment shown in FIG. 1 has a structure in which a substantially rectangular battery element 21 in which a charge / discharge reaction actually proceeds is sealed inside a laminate sheet 29 that is an exterior.

  As shown in FIG. 1, the battery element 21 of the lithium ion secondary battery 10 of the present embodiment includes a plurality of single battery layers 19. The unit cell layer 19 includes an electrolyte layer 17, a positive electrode active material layer 13 formed on one surface of the electrolyte layer 17, and a negative electrode active material layer 15 formed on the other surface of the electrolyte layer 17. The A positive electrode current collector 33 is disposed between the positive electrode active material layers 13 (including the outside of the outermost positive electrode current collector), and a negative electrode current collector 35 is disposed between the negative electrode active material layers 15. The That is, the battery element 21 includes a plurality of single battery layers 19 and a plurality of current collectors (a positive electrode current collector 33 and a negative electrode current collector 35).

  Further, the positive electrode current collector 33 and the negative electrode current collector 35 are electrically connected to the positive electrode tab 25 and the negative electrode tab 27, respectively. The battery element 21 is sealed with a laminate sheet 29 as an exterior so that the positive electrode tab 25 and the negative electrode tab 27 are led out to the outside.

  In the lithium ion secondary battery 10 shown in FIG. 1, the negative electrode active material layer 15 is slightly smaller than the positive electrode active material layer 13, but is not limited to such a form. A negative electrode active material layer 15 that is the same as or slightly larger than the positive electrode active material layer 13 may also be used.

  Hereinafter, although the member which comprises the lithium ion secondary battery 10 of this embodiment is demonstrated easily, it is not restrict | limited only to the following form, A conventionally well-known form can be employ | adopted similarly.

[Current collector]
The current collectors (33, 35) are made of a conductive material such as an aluminum foil, a copper foil, or a stainless steel (SUS) foil. The general thickness of the current collector is 1 to 30 μm. However, a current collector having a thickness outside this range may be used.

  The size of the current collector is determined according to the intended use of the lithium ion secondary battery 10. If a large electrode used for a large battery is manufactured, a current collector having a large area is used. If a small electrode is produced, a current collector with a small area is used.

[Active material layer]
The active material layer contains an active material, and further contains other additives as necessary.

The positive electrode active material layer 13 includes a positive electrode active material. Examples of the positive electrode active material include lithium-transition metal oxides such as LiMn ₂ O ₄ and LiNiO ₂ , lithium-transition metal phosphate compounds, and lithium-transition metal sulfate compounds. In some cases, two or more positive electrode active materials may be used in combination. Of course, positive electrode active materials other than those described above may be used.

  The negative electrode active material layer 15 includes a negative electrode active material. Examples of the negative electrode active material include carbon materials such as graphite, soft carbon, and hard carbon, lithium-transition metal compounds, metal materials, and lithium-metal alloy materials as described above. In some cases, two or more negative electrode active materials may be used in combination. Of course, negative electrode active materials other than those described above may be used.

  Although the average particle diameter of each active material contained in each active material layer (13, 15) is not particularly limited, it is preferably 0.01 to 100 μm, more preferably 1 to 50 μm. However, it goes without saying that a form outside this range may be adopted. In the present specification, “particle diameter” means the maximum distance L among the distances between any two points on the outline of the particle 1 as shown in FIG. The value of “particle diameter” is calculated as an average value of particle diameters of particles observed in several to several tens of fields using an observation means such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM). Shall be adopted.

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

  Examples of the binder include polyvinylidene fluoride (PVdF) and a synthetic rubber binder.

  The conductive assistant refers to an additive that is blended in order to improve the conductivity of the positive electrode active material layer 13 or the negative electrode active material layer 15. 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 (13, 15) contains a conductive additive, an electronic network inside the active material layer is effectively formed, which can contribute to the 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 the} like.

  Examples of the ion conductive polymer include polyethylene oxide (PEO) -based and polypropylene oxide (PPO) -based polymers. Here, the ion conductive polymer may be the same as or different from the ion conductive polymer used as the electrolyte in the electrolyte layer 17 of the lithium ion secondary battery 10, but is preferably the same. .

  The compounding ratio of the components contained in the positive electrode active material layer 13 and the negative electrode active material layer 15 is not particularly limited. The blending ratio can be adjusted by appropriately referring to known knowledge about the nonaqueous electrolyte secondary battery.

  The thickness of each active material layer (13, 15) is not particularly limited, and conventionally known knowledge about lithium ion secondary batteries can be appropriately referred to. As an example, the thickness of each active material layer (13, 15) is about 2 to 100 μm.

[Electrolyte layer]
The electrolyte layer 17 is a layer containing an electrolyte. The electrolyte (specifically, lithium salt) contained in the electrolyte layer 17 has a function as a carrier of lithium ions that moves between the positive and negative electrodes during charge and discharge.

  The lithium ion secondary battery of this embodiment is characterized in that the electrolyte layer 17 includes a separator made of insulating particles having a predetermined particle diameter. According to such a form, it is not necessary to use a substrate having a certain thickness as in the conventional electrolyte layer for the separator, and the electrode structure can be further thinned. As a result, the volume energy density of the lithium ion secondary battery can be improved. Moreover, heat resistance can also be improved by employ | adopting insulating particles as a separator compared with the case where the conventional separator is used.

  Hereinafter, the separator which is a characteristic configuration of the present embodiment will be described in more detail.

  The separator of this embodiment contains insulating particles. “Insulating particle” means a particle exhibiting electrical insulation. The material constituting the insulating particles is not particularly limited as long as the material exhibits electrical insulation, and conventionally known materials can be appropriately used. Specifically, a ceramic material or an organic polymer material is preferably used as a material constituting the insulating particles. By constituting the insulating particles using these materials, the function of preventing the short circuit between the positive and negative electrodes required for the separator can be sufficiently exhibited. Examples of the ceramic material include oxides such as silica, alumina, zirconia, magnesia, titania, silica alumina, chromium oxide, and ruthenium oxide, and nitrides such as aluminum nitride and silicon nitride. On the other hand, organic polymer materials include acrylic materials such as (meth) acrylates such as polymethyl acrylate and polymethyl methacrylate, polyimide materials such as fluorinated imides, polystyrene, polypropylene, polysulfone, and phenolic resins. And unsaturated polyester resins. Only 1 type of these materials may be used independently, and 2 or more types may be used together. All of the materials specifically listed above have a relatively high melting point, and by using these materials to form a separator, the heat resistance of the separator can be improved and the reliability of the battery can be improved. . Needless to say, materials other than those described above may be used to form the insulating particles contained in the separator.

  The insulating particles constituting the separator may be particles made of ceramic materials (ceramic particles), or particles made of organic polymer materials (organic polymer particles). Or a mixture of particles. When the form of the mixture is adopted, the mixing ratio of the ceramic particles and the organic polymer particles is not particularly limited, but is preferably a ratio of ceramic particles: organic polymer particles (volume ratio), preferably 10-20: 1-10. More preferably, it is 10-15: 3-10. However, it is needless to say that a form outside these ranges may be adopted.

  The insulating particles are preferably composed of two or more materials having different heat resistance. Here, “differing in heat resistance” of the materials constituting the insulating particles means that the melting points or softening points of the materials are different. Taking the above-described material as an example of the constituent material of the insulating particles, the ceramic material generally has higher heat resistance than the organic polymer material. In this application, “high heat resistance” and “low heat resistance” are merely relative concepts, and are limited by specific values of the melting point and softening point of the material constituting the insulating particles. There is no. However, as an example, a material having high heat resistance generally has a melting point or softening point of about 500 ° C. or higher, and a material having low heat resistance generally has a melting point or softening point of about 100 to 200 ° C.

  Specific examples of the case where the insulating particles are composed of two or more materials having different heat resistance include, for example, two types of the insulating particles composed of materials having different heat resistance, as described above. The form which is a mixture of the above particle | grains is mentioned.

  As another form, as shown in FIG. 3, the insulating particles include a core portion 110 made of a material having relatively high heat resistance (for example, ceramic particles) and a material having relatively low heat resistance ( For example, the form which has the core-shell structure which consists of the shell part 120 comprised from an organic polymer material) is mentioned. According to such a form, the heat resistance of the insulating particles is ensured by the material having a relatively high heat resistance, and as a result, the heat resistance of the entire battery can be improved. On the other hand, a material having a relatively low heat resistance generally has a smaller density (specific gravity) than a material having a relatively high heat resistance, and thus the weight of insulating particles can be reduced. As a result, it is possible to effectively suppress a decrease in the weight energy density of the battery while ensuring the heat resistance of the battery.

  In the form shown in FIG. 3, the sizes of the core part 110 and the shell part 120 are not particularly limited. However, as an example, the volume ratio (core part / shell part) between the core part 110 and the shell part 120 is 1/1 to 1. It is about 1/200000, preferably 1/2 to 1/100. Moreover, the diameter (maximum diameter) of the core part 110 is about 0.1-20 micrometers, Preferably it is 1-10 micrometers. Furthermore, the thickness of the shell part 120 is about 0.1-20 micrometers, Preferably it is 0.5-10 micrometers.

  When the insulating particles have the core-shell structure described above, the shell portion 120 has a layer structure of two or more layers composed of different materials (the inner shell portion 120a and the outer layer shown in FIG. 4), as shown in FIG. It may have a shell part 120b). At this time, the material constituting the outermost layer of the shell portion 120 (the outer shell portion 120b shown in FIG. 4) is more than the material constituting the other layers of the shell portion 120 (for example, the inner shell portion 120a shown in FIG. 4). It is preferable that heat resistance is low. According to such a form, the effect of improving the heat resistance by the insulating particles is maintained for a long period of time, and can effectively contribute to the durability of the battery.

  Even in such a form, the size of the core part 110 and each shell part (120a, 120b) is not particularly limited as described above. However, in the form in which the shell part 120 is composed of two layers as shown in FIG. The thickness of the shell part 120a is about 0.1 to 20 μm, preferably 0.2 to 10 μm. The thickness of the outer shell portion 120b is about 0.1 to 20 μm, preferably 0.2 to 10 μm.

  As yet another form, as shown in FIG. 5, in the insulating particles, fine particles 140 made of a material having a relatively high heat resistance are dispersed in a matrix 130 made of a material having a relatively low heat resistance. It may have a structure.

  In the form shown in FIG. 5, the ratio of the content of the matrix 130 and the fine particles 140 is not particularly limited. For example, the mass ratio of the matrix 130 and the fine particles 140 (matrix / fine particles) is 1/1 to 1 / It is about 100, preferably 1/1 to 1/10. In addition, although there is no restriction | limiting in particular also about the average particle diameter of the microparticles | fine-particles 140, Usually, it is about 0.1-20 micrometers, Preferably it is 0.5-10 micrometers.

  In the first embodiment of the present invention, it is essential that the average particle diameter of the insulating particles is 10 nm to 30 μm, preferably 50 nm to 25 μm, more preferably 100 nm to 20 μm, and still more preferably 1000 nm. 10 μm. The reason why the lower limit of the average particle diameter is 10 nm is that the lower limit of the particle diameter of the primary particles of the material that can be used as insulating particles is about 10 nm. On the other hand, the upper limit of the average particle diameter is set to 30 μm because when the average particle diameter of the insulating particles exceeds 30 μm, the thickness of the electrolyte layer including the separator made of insulating particles naturally exceeds 30 μm. This is because there is a possibility that the volume energy density of the material may decrease. In addition, even if the insulating particles constituting the separator fall off due to vibration during use of the battery, a short circuit between the positive and negative electrodes is generated by using such relatively small size insulating particles. Can be sufficiently suppressed.

  In the present embodiment, the thickness of the entire electrolyte layer is not particularly limited, but is preferably about 100 nm to 30 μm. When the thickness of the entire electrolyte layer is within such a range, it is possible to sufficiently suppress the occurrence of a short circuit between the positive and negative electrodes without causing a decrease in the volume energy density of the battery.

  In this embodiment, the electrolyte layer preferably further includes a binder in addition to the separator made of insulating particles. According to such a form, the insulating particles constituting the separator are bound to each other, and the adhesion between the separator of the electrolyte layer and the adjacent active material layer can also be improved. As a result, reliability such as vibration resistance of the lithium ion secondary battery can be improved. In addition, the specific form of the binder contained in the electrolyte layer is not particularly limited, but polyvinylidene fluoride (PVdF), polyvinyl acetate, polyimide, acrylic resin, polyethylene, polystyrene, polypropylene, polysulfone, polycarbonate, polytetrafluoro Thermoplastic resins such as ethylene; urea resins, epoxy resins, polyurethane resins, silicon resins, phenol resins, unsaturated polyester resins, and other thermosetting resins; butyl rubber, styrene rubber, polyisoprene rubber, olefin rubber, urethane rubber Further, rubber-based materials such as polyamide-based rubber, acrylic rubber, and fluorine rubber can be preferably used. Of course, other materials may be used as the binder. Moreover, only 1 type of these materials may be used independently, and 2 or more types may be used together.

  When the electrolyte layer 17 includes a binder in addition to the separator made of insulating particles, the binder content in the electrolyte layer is not particularly limited, but preferably 1 to 80 when the total amount of insulating particles is 100 parts by mass. It is a mass part, More preferably, it is 3-50 mass parts. When the added amount of the binder is in such a range, a battery having an excellent balance of binding property, adhesion, and volume energy density can be provided.

  In the present embodiment, the porosity of the electrolyte layer is also preferably a value within a predetermined range. Specifically, the porosity of the electrolyte layer is preferably 20 to 90%, more preferably 30 to 80%, and further preferably 40 to 60%. When the porosity of the electrolyte layer is in such a range, there is an advantage that lithium ions easily move in the electrolyte during charging and discharging, and lithium ions are quickly supplied to the electrodes. The “porosity of the electrolyte layer” means the volume of the insulating layer as the separator, and, if a binder is included, the remaining volume obtained by subtracting the volume of the binder from the total volume of the electrolyte layer. It means a value expressed as a percentage of the total volume of. Therefore, in the lithium ion secondary battery of this embodiment, for example, when an intrinsic polymer electrolyte is used as the electrolyte, the volume occupied by the intrinsic polymer electrolyte corresponds to a void.

  In general, the electrolyte constituting the electrolyte layer 17 includes a liquid electrolyte or a polymer electrolyte. In the present invention, a polymer electrolyte is preferably used. By using the polymer electrolyte, leakage of the electrolyte and the like can be prevented, and the safety of the lithium ion secondary battery 10 can be improved.

  The polymer electrolyte is composed of an ion conductive polymer, and the material is not limited as long as it exhibits ion conductivity. In view of the fact that excellent mechanical strength can be expressed, a polymerized ion conductive polymer that is crosslinked by thermal polymerization, ultraviolet polymerization, radiation polymerization, electron beam polymerization, or the like is preferably used. By using such a crosslinked polymer, the reliability of the battery is improved, and the lithium ion secondary battery 10 having a simple configuration and excellent output characteristics is manufactured.

  Examples of the polymer electrolyte include an intrinsic polymer electrolyte and a gel polymer electrolyte.

  The intrinsic polymer electrolyte is not particularly limited, and examples thereof 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. In addition, these polymers can exhibit excellent mechanical strength by forming a crosslinked structure.

The gel polymer electrolyte generally refers to an electrolyte solution held in an all-solid polymer electrolyte having ion conductivity. In the present application, a gel polymer electrolyte also includes a polymer skeleton having no lithium ion conductivity and a similar electrolyte solution held therein. The kind of electrolyte solution (electrolyte salt and plasticizer) used is not particularly limited. Examples of the electrolyte salt include lithium salts such as LiBETI, LiBF ₄ , LiPF ₆ , LiN (SO ₂ CF ₃ ) ₂ , and LiN (SO ₂ C ₂ F ₅ ) ₂ . Examples of the plasticizer include carbonates such as propylene carbonate and ethylene carbonate.

  In this embodiment, when the electrolyte contained in the electrolyte layer is an intrinsic polymer electrolyte or a gel polymer electrolyte, it is preferable that the electrolyte further includes insulating particles. This is due to the following reason. That is, when an intrinsic polymer electrolyte or a gel polymer electrolyte is used as the electrolyte, a short circuit between the positive and negative electrodes is relatively likely to occur due to gel flow and polymer melting at the time of battery temperature rise. When the electrolyte further includes insulating particles, even if gel flow or polymer melting occurs, occurrence of a short circuit between the positive and negative electrodes can be suppressed by the presence of the insulating particles. As a result, the reliability of the battery can be further improved.

[tab]
In the lithium ion secondary battery 10, a laminate sheet 29 in which the tabs (the positive electrode tab 25 and the negative electrode tab 27) electrically connected to the current collectors (33, 35) are the exterior for the purpose of taking out current outside the battery. It is taken out outside. Specifically, the positive electrode tab 25 electrically connected to the positive electrode current collector 33 and the negative electrode tab 27 electrically connected to the negative electrode current collector 35 are taken out of the exterior.

  The material constituting the tabs (the positive electrode tab 25 and the negative electrode tab 27) is not particularly limited, and a known material conventionally used as a tab for a lithium ion secondary battery can be used. Examples of the constituent material of the tab include aluminum, copper, titanium, nickel, stainless steel (SUS), and alloys thereof. Note that the same material may be used for the positive electrode tab 25 and the negative electrode tab 27, or different materials may be used. Further, as in the present embodiment, separately prepared tabs (25, 27) may be connected to the current collectors (33, 35), or the current collectors may be extended to form tabs.

[Exterior]
In the lithium ion secondary battery 10, the battery element 21 is preferably housed in an exterior such as a laminate sheet 29 in order to prevent external impact and environmental degradation during use. The exterior is not particularly limited, and a conventionally known exterior can be used. A polymer-metal composite laminate sheet or the like excellent in thermal conductivity can be preferably used in that heat can be efficiently transferred from a heat source of an automobile and the inside of the battery can be rapidly heated to the battery operating temperature.

(Production method)
There is no restriction | limiting in particular about the manufacturing method of the lithium ion secondary battery 10 of this embodiment, It can manufacture with reference to conventionally well-known knowledge in the manufacturing field of a battery. Hereinafter, the manufacturing method of the lithium ion secondary battery 10 of this embodiment is demonstrated easily.

  In producing a battery element, first, an active material layer (a positive electrode active material layer or a negative electrode active material layer) is formed on both surfaces of one current collector to produce an electrode. Then, a slurry containing insulating particles (insulating particle slurry) is separately prepared, and the insulating particle slurry is applied to the surface (preferably both surfaces) of at least one of the active material layers, dried, and finally A battery element is preferably formed by forming a coating film to be a separator on the substrate and then laminating adjacent electrodes so that the positive electrode active material layer and the negative electrode active material layer face each other. And application | coating of an insulating particle slurry and lamination | stacking of an electrode are repeated until the number of a single cell becomes a desired number. According to such a manufacturing method, it is possible to form a separator by a simpler method and to produce a battery element having high adhesion between the separator and the active material layer.

  The insulating particle slurry can be prepared by dispersing the insulating particles and, if necessary, the binder in a suitable solvent. Here, since the specific form of the insulating particles and the binder that can be included in the insulating particle slurry is as described above, detailed description thereof is omitted here.

  Regarding the insulating particles, commercially available products may be purchased and used, or those prepared by themselves may be used. Here, for example, insulating particles having a core-shell structure in the form shown in FIG. 3 (see Examples 2-4 to 2-6) and in the form shown in FIG. 4 (see Example 2-7) are prepared. For example, there is a technique in which a material constituting the core part and a material constituting the shell part are mixed by a mechanical milling method. You may heat as needed in the case of mixing. Moreover, in order to prepare the insulating particles in the form shown in FIG. 5 (see Examples 2-1 to 2-3), for example, a material having a relatively high melting point is dispersed in a material having a relatively low melting point (for example, In other words, a method of dispersing alumina fine particles in dissolved polypropylene) can be used.

  The solvent used in preparing the insulating particle slurry is not particularly limited as long as it does not react with the insulating particles (or a binder when a binder is included) and can achieve a desired viscosity. Specific examples include polar solvents such as N-methyl-2-pyrrolidone (NMP), dimethylformamide, dimethylacetamide, and methylformamide.

  The concentration of the insulating particles and binder in the insulating particle slurry and the viscosity of the slurry are not particularly limited, and may be appropriately determined in consideration of the application method to the active material layer. Specifically, the viscosity of the insulating particle slurry is preferably 500 to 8000 cPs, more preferably 1000 to 4000 cPs.

  The application means for applying the insulating particle slurry to the surface of the active material layer is not particularly limited, and a conventionally known technique can be appropriately employed in the battery manufacturing field. For example, methods such as a doctor blade method, an ink jet method, a screen printing method, and a die coater method are exemplified. However, it goes without saying that other methods may be used.

  Further, the drying means for drying the insulating particle slurry applied to the surface of the active material layer is not particularly limited, and a conventionally known method can be appropriately employed. As an example, natural drying, air drying, hot air drying, reduced pressure drying and the like can be mentioned. However, it goes without saying that other methods may be used.

  Subsequently, a tab to which a lead is connected is joined to the outermost layer of the battery element obtained by the above-described method, and the battery element is placed in a laminate sheet so that the lead is exposed to the outside, and sealed in a vacuum. To do. In addition, what is necessary is just to inject | pour electrolyte solution before sealing of a laminate sheet, when an electrolyte layer contains electrolyte solution, ie, when an electrolyte layer contains a liquid electrolyte or a gel electrolyte.

  Through the above steps, the lithium ion secondary battery 10 of the present embodiment having a plurality of unit cell layers is completed.

(Second Embodiment)
In the second embodiment, an assembled battery is configured by connecting a plurality of the lithium ion secondary batteries of the first embodiment in parallel and / or in series.

  FIG. 6 is a perspective view showing the assembled battery of the present embodiment.

  As illustrated in FIG. 6, the assembled battery 40 is configured by connecting a plurality of lithium ion secondary batteries described in the first embodiment. Each lithium ion secondary battery 10 is connected by connecting the positive electrode tab 25 and the negative electrode tab 27 of each lithium ion secondary battery 10 using a bus bar. On one side surface of the assembled battery 40, electrode terminals (42, 43) are provided as electrodes of the entire assembled battery 40.

  The connection method in particular when connecting the some lithium ion secondary battery 10 which comprises the assembled battery 40 is not restrict | limited, A conventionally well-known method can be employ | adopted suitably. For example, a technique using welding such as ultrasonic welding or spot welding, or a technique of fixing using rivets, caulking, or the like can be employed. According to such a connection method, the long-term reliability of the assembled battery 40 can be improved.

  According to the assembled battery 40 of the present embodiment, by using the lithium ion secondary battery 10 of the first embodiment as described above, the assembled battery 40 is sufficiently assembled even under high output conditions while sufficiently securing capacity characteristics. An assembled battery capable of exhibiting a high output can be provided.

  In addition, connection of the lithium ion secondary battery 10 which comprises the assembled battery 40 may be connected all in parallel, all may be connected in series, and also in series connection and parallel connection, May be combined.

(Third embodiment)
In the third embodiment, the lithium ion secondary battery 10 of the first embodiment and / or the assembled battery 40 of the second embodiment is mounted as a motor driving power source to constitute a vehicle. As a vehicle using the lithium ion secondary battery 10 or the assembled battery 40 as a motor power source, for example, a complete electric vehicle not using gasoline, a hybrid vehicle such as a series hybrid vehicle or a parallel hybrid vehicle, and a wheel such as a fuel cell vehicle The motor vehicle which drives with a motor is mentioned.

  For reference, FIG. 7 shows a schematic diagram of an automobile 50 on which the assembled battery 40 is mounted. The assembled battery 40 mounted on the automobile 50 has the characteristics as described above. For this reason, by mounting the assembled battery 40 on the automobile 50, the output characteristics and capacity characteristics of the automobile 50 are improved, and further, the automobile 50 can be further reduced in weight and size.

  As described above, some preferred embodiments of the present invention have been described. However, the present invention is not limited to the above embodiments, and various modifications, omissions, and additions can be made by those skilled in the art. . For example, in the above description, a lithium ion secondary battery that is not a bipolar type has been described as an example. However, the technical scope of the battery of the present invention is not limited to such a form. A lithium ion secondary battery (bipolar battery) may be used. For reference, FIG. 8 is a cross-sectional view showing an outline of a bipolar battery, and the outline of the bipolar battery and its components will be briefly described.

  The bipolar battery 60 shown in FIG. 8 has a structure in which a substantially rectangular battery element 21 in which a charge / discharge reaction actually proceeds is sealed inside a laminate sheet 29 that is an exterior.

  As shown in FIG. 8, the battery element 21 of the bipolar battery 60 of the present embodiment has the positive electrode active material layer 13 formed on one surface of the current collector 11 and the negative electrode active material layer 15 formed on the other surface. It has a plurality of bipolar electrodes. Each bipolar electrode is stacked via an electrolyte layer 17 to form a battery element 21. At this time, each bipolar electrode and electrolyte layer are arranged such that the positive electrode active material layer 13 of one bipolar electrode and the negative electrode active material layer 15 of another bipolar electrode adjacent to the one bipolar electrode face each other through the electrolyte layer 17. 17 are stacked.

  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 60 has a configuration in which the unit cell layers 19 are electrically connected in series via the surface. The current collector (outermost layer current collector) (11a, 11b) located in the outermost layer of the battery element 21 has a positive electrode active material layer 13 (positive electrode side outermost layer current collector 11a) or a negative electrode only on one side. One of the active material layers 15 (negative electrode side outermost layer current collector 11b) is formed.

  Further, in the bipolar battery 60 shown in FIG. 8, the positive electrode outermost layer current collector 11 a is extended to form a positive electrode tab 25, which is led out from a laminate sheet 29 that is an exterior. On the other hand, the negative electrode side outermost layer current collector 11 b is extended to form a negative electrode tab 27, which is similarly derived from the laminate sheet 29.

[Insulation layer]
In the bipolar battery 60, the insulating layer 31 is usually provided around each single battery layer 19. The insulating layer 31 prevents the adjacent current collectors 11 in the battery from coming into contact with each other or a short circuit caused by a slight irregularity at the end of the unit cell layer 19 in the battery element 21. Is provided. By providing such an insulating layer 31, long-term reliability and safety can be ensured, and a high-quality bipolar battery 60 can be provided.

  The insulating layer 31 may be made of a material having insulating properties, sealing properties against falling off of the solid electrolyte, sealing properties against moisture permeation from the outside (sealing properties), heat resistance at the battery operating temperature, and the like. For example, urethane resin, epoxy resin, polyethylene resin, polypropylene resin, polyimide resin, rubber or the like can be used. Among these, polyethylene resin and polypropylene resin are preferably used as the constituent material of the insulating layer 31 from the viewpoints of corrosion resistance, chemical resistance, ease of production (film forming property), economy, and the like.

  The effects of the present invention will be described using the following examples and comparative examples. However, the technical scope of the present invention is not limited only to the following examples.

<Example 1-1>
<Preparation of positive electrode>
Spinel-type lithium manganate (LiMn ₂ O ₄ ) (average particle size: 20 μm) (80% by mass) as a positive electrode active material, acetylene black (10% by mass) as a conductive additive, and polyvinylidene fluoride as a binder ( PVdF) (10% by mass) was mixed, and then an appropriate amount of N-methyl-2-pyrrolidone (NMP) as a slurry viscosity adjusting solvent was added to prepare a positive electrode active material slurry having a viscosity of 4000 cPs.

  On the other hand, an aluminum foil (thickness: 15 μm) was prepared as a positive electrode current collector. The positive electrode active material slurry prepared above was applied to both sides of the aluminum foil by a doctor blade method, and after drying, a press treatment was performed to form a positive electrode active material layer (thickness: 110 μm) having a size of 146 mm × 96 mm, A positive electrode was produced.

<Production of negative electrode>
Hard carbon (average particle size: 20 μm) (90% by mass) as a negative electrode active material and polyvinylidene fluoride (PVdF) (10% by mass) as a binder are mixed, and then N-methyl-as a slurry viscosity adjusting solvent. An appropriate amount of 2-pyrrolidone (NMP) was added to prepare a negative electrode active material slurry having a viscosity of 4000 cPs.

  On the other hand, a copper foil (thickness: 10 μm) was prepared as a negative electrode current collector. The negative electrode active material slurry prepared above was applied to both surfaces of the copper foil by a doctor blade method, dried and subjected to a press treatment to form a negative electrode active material layer (thickness: 75 μm) having a size of 150 mm × 100 mm, A negative electrode was produced.

<Production of battery element>
Alumina particles (average particle size: 3 μm) (70% by mass) as ceramic particles, polymethyl acrylate particles (average particle size: 5 μm) (20% by mass) as organic polymer particles, and polyvinylidene fluoride as a binder (PVdF) (10 mass%) was mixed, and then an appropriate amount of N-methyl-2-pyrrolidone (NMP), which is a slurry viscosity adjusting solvent, was added to prepare an insulating particle slurry having a viscosity of 3000 cPs.

  The insulating particle slurry prepared above is applied to the surface of the positive electrode active material layer of the positive electrode prepared above by a doctor blade method and dried to form a separator layer (thickness: 5 μm) on the surface of the positive electrode active material layer. Formed.

  Subsequently, the negative electrode produced above and the positive electrode similarly formed with the separator layer were laminated so that the negative electrode active material layer and the separator layer faced to complete a battery element.

<Encapsulation in laminate sheet>
As an electrolytic solution, LiPF ₆ as an electrolyte salt (lithium salt) is dissolved at a concentration of 1M in a mixed solution (EC: PC = 1: 1 (volume ratio)) of ethylene carbonate (EC) and propylene carbonate (PC). I prepared a dish.

  The battery element produced above was sandwiched between two aluminum laminate sheets, and the periphery of the sheet was sealed by thermal fusion, leaving the electrolyte inlet. Thereafter, the electrolytic solution prepared above is injected from the injection port, the injection port is sealed by thermal fusion under vacuum conditions, the battery element is enclosed in a laminate sheet, and the lithium ion secondary battery is sealed. Completed. In addition, the positive electrode tab made from aluminum was connected to the positive electrode collector, the negative electrode tab made from nickel was connected to the negative electrode collector, and each was derived | led-out from the opposing edge | side of a battery element.

<Example 1-2>
A lithium ion secondary battery was produced in the same manner as in Example 1-1 except that the thickness of the separator layer was controlled to 10 μm by adjusting the coating amount of the insulating particle slurry.

<Example 1-3>
A lithium ion secondary battery was fabricated in the same manner as in Example 1-1, except that the thickness of the separator layer was controlled to 20 μm by adjusting the coating amount of the insulating particle slurry.

<Example 1-4>
A lithium ion secondary battery was produced in the same manner as in Example 1-1, except that the thickness of the separator layer was controlled to 25 μm by adjusting the coating amount of the insulating particle slurry.

<Example 1-5>
A lithium ion secondary battery was produced in the same manner as in Example 1-4, except that alumina particles having an average particle diameter of 5 μm were used as ceramic particles.

<Example 1-6>
A lithium ion secondary battery was fabricated in the same manner as in Example 1-4, except that alumina particles having an average particle diameter of 10 μm were used as the ceramic particles.

<Example 1-7>
A lithium ion secondary battery was produced in the same manner as in Example 1-4, except that alumina particles having an average particle diameter of 15 μm were used as ceramic particles.

<Comparative example>
Instead of forming the separator layer by applying the insulating particle slurry, Example 1-1 above except that a separator (thickness: 30 μm) was inserted between the positive electrode active material layer and the negative electrode active material layer. A lithium ion secondary battery was produced in the same manner. In addition, what was produced with the following methods was used as a separator.

First, alumina particles (average particle size: 5 μm) (90% by mass) as ceramic particles and polyvinylidene fluoride (PVdF) (10% by mass) as a binder are mixed, and then N-methyl which is a slurry viscosity adjusting solvent. An appropriate amount of 2-pyrrolidone (NMP) was added to prepare an insulating particle slurry. Next, the insulating particle slurry prepared above was applied to both sides of a polyethylene terephthalate (PET) nonwoven fabric (thickness: 20 μm) by a doctor blade method and dried to prepare a separator. In addition, the basis weight of the alumina particles on one side of the obtained separator was 4.5 mg / cm ² .

<Evaluation Example 1>
The lithium ion secondary batteries produced in Examples 1-1 to 1-7 and the comparative examples described above were subjected to an initial charge process (CCCV) at 0.2C and an initial discharge process at 0.5C. The discharge capacity in the initial discharge process is referred to as “initial discharge capacity”.

  Each battery was then subjected to 10 cycles of charge / discharge treatment at a constant current of 1C. Thereafter, the rate characteristics (discharge capacity and volume energy density) at 5 C in the fully charged state (4.2 V) of each battery were evaluated. The discharge capacity at this time is referred to as “discharge capacity after cycle charge / discharge”. And according to following Numerical formula 1, the discharge efficiency from the full charge state after cycle charge / discharge was computed. The evaluation results of the rate characteristics at 5C for each battery are shown in Table 1 below. In Table 1, “5C relative discharge efficiency” indicates a relative value when the discharge efficiency of the battery of the comparative example is 1, and “relative energy density” indicates the volume energy density of the battery of the comparative example is 1. The relative value is shown.

  From the comparison between each example shown in Table 1 and the comparative example, in the lithium ion secondary battery, when the separator is composed mainly of insulating particles, the volume energy density is higher than that of the conventional separator using the base material. It shows that the discharge efficiency (capacity maintenance ratio after cycle charge / discharge) can be maintained at a high value without decreasing.

  Moreover, the comparison between Examples 1-1 to 1-4 and the comparative example shows that the volume energy density can be effectively improved as the thickness of the separator layer is thinner.

  Furthermore, the comparison of Examples 1-4 to 1-7 shows that the discharge efficiency can be improved more effectively as the particle diameter of the insulating particles contained in the separator layer is smaller.

<Example 2-1>
<Preparation of positive electrode>
Ten positive electrodes were produced by the following method.

Specifically, first, spinel type lithium manganate (LiMn ₂ O ₄ ) (average particle size: 20 μm) (85 mass%) as a positive electrode active material, acetylene black (5 mass%) as a conductive auxiliary agent, and A polyvinylidene fluoride (PVdF) (10 mass%) as a binder is mixed, and then an appropriate amount of N-methyl-2-pyrrolidone (NMP) as a slurry viscosity adjusting solvent is added to obtain a positive electrode active material slurry having a viscosity of 5000 cPs. Prepared.

  On the other hand, an aluminum foil (thickness: 15 μm) was prepared as a positive electrode current collector. The positive electrode active material slurry prepared above was applied to both surfaces of the aluminum foil by a doctor blade method, and after drying, a press treatment was performed to form a positive electrode active material layer (thickness: 110 μm) having a size of 145 mm × 95 mm, A positive electrode was produced.

<Production of negative electrode>
Eleven negative electrodes were produced by the following method.

  Specifically, first, hard carbon (average particle size: 20 μm) (90% by mass) as a negative electrode active material and polyvinylidene fluoride (PVdF) (10% by mass) as a binder are mixed, and then the viscosity of the slurry is adjusted. An appropriate amount of N-methyl-2-pyrrolidone (NMP) as a solvent was added to prepare a negative electrode active material slurry having a viscosity of 5000 cPs.

  On the other hand, a copper foil (thickness: 10 μm) was prepared as a negative electrode current collector. The negative electrode active material slurry prepared above was applied to both surfaces of the copper foil by a doctor blade method, dried and subjected to a press treatment to form a negative electrode active material layer (thickness: 75 μm) having a size of 150 mm × 100 mm, A negative electrode was produced.

<Production of battery element>
Alumina fine particles (average particle size: 1 μm) (85% by mass), which are fine particles composed of a ceramic material, are dispersed in a matrix composed of polypropylene (15% by mass), an organic polymer material (thermoplastic resin). Insulating particles (average particle size: 5 μm) having the above structure (see FIG. 5) and polyvinylidene fluoride (PVdF) as a binder (10% by mass with respect to the total mass of the insulating fine particles) are mixed, Next, an appropriate amount of N-methyl-2-pyrrolidone (NMP), which is a slurry viscosity adjusting solvent, was added to prepare an insulating particle slurry having a viscosity of 10,000 cPs.

  The insulating particle slurry prepared above is applied to the surfaces of the negative electrode active material layers on both sides of the negative electrode prepared above by a doctor blade method, dried, and a separator layer (thickness: 10 μm on the surface of the negative electrode active material layer). ) Was formed.

  Next, 11 negative electrodes each having the separator layer formed thereon and 10 positive electrodes prepared in the same manner were alternately stacked to complete a battery element. In addition, lamination | stacking of the negative electrode active material layer and the separator layer was omitted in the outer surface of the negative electrode located in the both ends of a battery element.

<Encapsulation in laminate sheet>
As an electrolytic solution, LiPF ₆ as an electrolyte salt (lithium salt) is dissolved at a concentration of 1M in a mixed solution (EC: PC = 1: 1 (volume ratio)) of ethylene carbonate (EC) and propylene carbonate (PC). I prepared a dish.

  The battery element produced above was sandwiched between two aluminum laminate sheets, and the periphery of the sheet was sealed by thermal fusion, leaving the electrolyte inlet. Thereafter, the electrolytic solution prepared above is injected from the injection port, the injection port is sealed by thermal fusion under vacuum conditions, the battery element is enclosed in a laminate sheet, and the lithium ion secondary battery is sealed. Completed. In addition, the positive electrode tab made from aluminum was connected to the positive electrode collector, the negative electrode tab made from nickel was connected to the negative electrode collector, and each was derived | led-out from the opposing edge | side of a battery element.

<Example 2-2>
A lithium ion secondary battery was produced in the same manner as in Example 2-1 except that the thickness of the separator layer was 25 μm.

<Example 2-3>
Insulating particles having alumina particles with an average particle size of 3 μm are used, and the contents of insulating particles (alumina particles) and matrix (polypropylene) are 85% by mass and 15% by mass, respectively. A lithium ion secondary battery was produced in the same manner as in Example 2-2 except that the average particle size of was 10 μm.

<Example 2-4>
As insulating particles, a core portion made of alumina particles (average particle diameter: 3 μm) made of a ceramic material, and a shell portion (thickness: about 1 μm) made of polypropylene which is an organic polymer material (thermoplastic resin), Lithium ion secondary by the same method as in Example 2-1 except that insulating particles (average particle diameter: 5 μm) (see FIG. 3) having a core-shell structure composed of A battery was produced.

<Example 2-5>
A lithium ion secondary battery was produced in the same manner as in Example 2-4 except that the thickness of the separator layer was 25 μm.

<Example 2-6>
In the insulating particles, lithium ions were obtained in the same manner as in Example 2-5 except that the average particle diameter of the alumina particles constituting the core portion was 8 μm and the average particle diameter of the insulating particles was 12 μm. A secondary battery was produced.

<Example 2-7>
As insulating particles, a core portion made of alumina particles (average particle diameter: 4 μm) made of a ceramic material, and an inner shell portion (thickness: about 2 μm) made of polypropylene which is an organic polymer material (thermoplastic resin) And insulating particles (average particle diameter: 12 μm) having a core-shell structure composed of an outer shell portion (thickness: about 2 μm) made of polyethylene, which is also an organic polymer material (thermoplastic resin) ( A lithium ion secondary battery was fabricated in the same manner as in Example 2-5 except that the method shown in FIG. 4 was used.

<Evaluation Example 2>
About the lithium ion secondary battery produced by said Example 2-1 to 2-7 and the comparative example mentioned above, 5C discharge efficiency and relative energy density were measured by the method similar to said evaluation example 1. FIG. The evaluation results of rate characteristics at 5C for each battery are shown in Table 2 below. In Table 2, “relative energy density” indicates a relative value when the volume energy density of the battery of the comparative example is 1.

  From the comparison between each example shown in Table 2 and the comparative example, in the lithium ion secondary battery, insulating particles having a core-shell structure and insulating particles in which ceramic fine particles are dispersed in a resin matrix are the main components. When the separator is configured as described above, it is possible to maintain the discharge efficiency (capacity maintenance ratio after cycle charge / discharge) at a high value without lowering the volumetric energy density as compared with the conventional separator using a base material. It is shown.

It is sectional drawing which shows the outline | summary of the lithium ion secondary battery of 1st Embodiment. It is explanatory drawing for demonstrating the absolute maximum length used when measuring the particle diameter of an active material. It is a schematic cross section which shows one form of the insulating particle | grains in 1st Embodiment. It is a schematic cross section which shows the other form of the insulating particle | grains in 1st Embodiment. It is a schematic cross section which shows the further another form of the insulating particle | grains in 1st Embodiment. It is a perspective view which shows the assembled battery of 2nd Embodiment. It is the schematic of the motor vehicle of 3rd Embodiment carrying the assembled battery of 2nd Embodiment. It is sectional drawing which shows the outline | summary of a bipolar battery.

Explanation of symbols

1 particle,
10 Lithium ion secondary battery,
11 Current collector,
11a, 11b outermost layer current collector,
13 positive electrode active material layer,
15 negative electrode active material layer,
17 electrolyte layer,
19 cell layer,
21 battery elements,
25 positive electrode tab,
27 negative electrode tab,
29 Laminate sheet,
31 insulating layer,
33 positive electrode current collector,
35 negative electrode current collector,
40 battery packs,
42, 43 electrode terminals,
50 cars,
60 bipolar battery,
110 core part,
120 shell part,
120a inner shell part,
120b outer shell part,
130 matrix,
140 fine particles,
L Maximum distance.

Claims (25)

A positive electrode formed by forming a positive electrode active material layer containing a positive electrode active material on the surface of the current collector, an electrolyte layer containing an electrolyte, and a negative electrode active material layer containing a negative electrode active material formed on the surface of the current collector A battery having at least one unit cell layer in which a negative electrode is laminated in this order,
The lithium ion secondary battery, wherein the electrolyte layer further includes a separator made of insulating particles having a particle diameter of 10 nm to 30 μm.   The lithium ion secondary battery according to claim 1, wherein the material constituting the insulating particles is a ceramic material or an organic polymer material.   The lithium ion secondary battery according to claim 1 or 2, wherein the insulating particles are composed of two or more kinds of materials having different heat resistance.   The lithium ion secondary battery according to claim 3, wherein the insulating particles are a mixture of two or more kinds of particles each made of a material having different heat resistance.   The said insulating particle has a core-shell structure which consists of a core part comprised from a material with comparatively high heat resistance, and a shell part comprised from a material with comparatively low heat resistance. Lithium ion secondary battery.   The lithium ion secondary battery according to claim 5, wherein the shell portion has a layer structure of two or more layers made of different materials.   The lithium ion secondary battery according to claim 6, wherein a material constituting the outermost layer of the shell portion has lower heat resistance than a material constituting the other layers of the shell portion.   The lithium ion secondary according to claim 3, wherein the insulating particles have a structure in which fine particles made of a material having a relatively high heat resistance are dispersed in a matrix made of a material having a relatively low heat resistance. battery.   The lithium ion secondary battery according to any one of claims 3 to 8, wherein the material having the highest heat resistance is a ceramic material.   The lithium ion secondary battery according to any one of claims 3 to 9, wherein the material having the lowest heat resistance is an organic polymer material.   The lithium ion secondary battery according to claim 1, wherein the electrolyte layer further includes a binder.   The lithium ion secondary battery according to claim 11, wherein the binder is a thermoplastic resin, a thermosetting resin, or a rubber-based material.   The lithium ion secondary battery of any one of Claims 1-12 whose thickness of the said electrolyte layer is 100 nm-30 micrometers.   The lithium ion secondary battery according to any one of claims 1 to 13, wherein a porosity of the electrolyte layer is 20 to 90%.   The lithium ion secondary battery according to any one of claims 1 to 14, wherein the electrolyte is a liquid electrolyte, an intrinsic polymer electrolyte, or a gel polymer electrolyte.   The lithium ion secondary battery according to claim 15, wherein when the electrolyte is an intrinsic polymer electrolyte or a gel polymer electrolyte, the electrolyte further includes insulating particles.   The lithium ion secondary battery according to any one of claims 1 to 16, wherein the positive electrode active material is a lithium-transition metal oxide, a lithium-transition metal phosphate compound, or a lithium-transition metal sulfate compound.   The lithium ion secondary battery according to claim 1, wherein the negative electrode active material is a carbon material, a lithium-transition metal compound, a metal material, or a lithium-metal alloy material.   The lithium ion secondary battery according to any one of claims 1 to 18, wherein at least one of the positive electrode active material layer or the negative electrode active material layer further includes a conductive additive made of a carbon material.   The lithium ion secondary battery according to any one of claims 1 to 19, which is a bipolar type.   A battery pack in which a plurality of lithium ion secondary batteries according to any one of claims 1 to 20 are electrically connected in series, parallel, or series-parallel.   A vehicle equipped with the lithium ion secondary battery according to any one of claims 1 to 20 or the assembled battery according to claim 21 as a motor driving power source. A step of producing a positive electrode in which a positive electrode active material layer is formed on the surface of the current collector by applying and drying a positive electrode active material slurry containing the positive electrode active material on the surface of the current collector; and
A step of producing a negative electrode in which a negative electrode active material layer is formed on the surface of the current collector by applying and drying a negative electrode active material slurry containing the negative electrode active material on the surface of the current collector;
Applying an insulating particle slurry containing insulating particles to at least one surface of the positive electrode active material layer or the negative electrode active material layer, and forming a coating film by drying; and
Laminating the positive electrode and the negative electrode so that the positive electrode active material layer and the negative electrode active material layer face each other;
A method for producing a lithium ion secondary battery.   The manufacturing method according to claim 23, further comprising a step of sintering the coating film by heating.   The manufacturing method according to claim 23 or 24, wherein the insulating particle slurry further contains a binder.

Images