Secondary battery

Abstract

To provide a secondary battery in which a side reaction hardly occurs at an interface between a positive electrode active material and a solid electrolyte, the interface between the positive electrode active material and a positive electrode current collector even if charging and discharging are repeated.SOLUTION: A buffer layer or a protective layer is provided on a surface of a current collector or between a current collector layer and an active material layer in order to prevent deterioration such as oxidation of the current collector. For the buffer layer or the protection layer, a titanium compound such as titanium oxide, the titanium oxide in which part of oxygen is substituted with nitrogen, titanium nitride, titanium nitride in which part of nitrogen is substituted with oxygen, or titanium oxynitride (TiOxNy, 0<x<2, 0<y<1) can be applied. Among them, the titanium nitride is particularly preferable because of high conductivity and a high function of suppressing oxidation.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] One aspect of the present invention relates to an article, a method, or a manufacturing method. Alternatively, the present invention relates to a process, a machine, a manufacture, or a composition of matter. One aspect of the present invention relates to a semiconductor device, a display device, a light-emitting device, a power storage device, a lighting device, or an electronic device, or a manufacturing method thereof. In particular, the present invention relates to a positive electrode active material that can be used for a secondary battery, a secondary battery, and an electronic device having the secondary battery.

[0002] In the present specification, the power storage device refers to an element and a device having a power storage function in general. For example, it includes a storage battery (also referred to as a secondary battery) such as a lithium ion secondary battery, a lithium ion capacitor, and an electric double layer capacitor.

[0003] In the present specification, the electronic device refers to a device having a power storage device in general, and an electro-optical device having a power storage device, an information terminal device having a power storage device, etc. are all electronic devices.

Background Art

[0004] In recent years, various power storage devices such as lithium ion secondary batteries, lithium ion capacitors, air batteries, and all-solid-state batteries have been actively developed. In particular, lithium ion secondary batteries with high output and high capacity have rapidly expanded their demand along with the development of the semiconductor industry, and have become indispensable in modern information societies as a source of rechargeable energy.

[0005] In addition, the development of all-solid-state batteries with higher safety among lithium ion secondary batteries has been promoted.

[0006] Patent Document 1 discloses a secondary battery using an oxide-based all-solid-state battery.

Prior Art Documents

Patent Documents

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2019-102261 [Summary of the Invention] [Problems to be Solved by the Invention]

[0008] There is room for improvement in various aspects of secondary batteries, such as charge-discharge characteristics, cycle characteristics, reliability, safety, or cost. For example, regarding the cycle characteristics, as charge and discharge are repeated, the crystal structure of the positive electrode active material may collapse, which may lead to a decrease in the charge-discharge capacity. In addition, side reactions may occur at the interface between the positive electrode active material and the solid electrolyte, the interface between the positive electrode active material and the positive electrode current collector, etc., which may also lead to a decrease in the charge-discharge capacity.

[0009] Therefore, one aspect of the present invention is to provide a secondary battery in which side reactions are less likely to occur at the interface between the positive electrode active material and the solid electrolyte, the interface between the positive electrode active material and the positive electrode current collector, etc., even when charge and discharge are repeated. Or, one aspect of the present invention is to provide a secondary battery having excellent charge-discharge cycle characteristics. Or, one aspect of the present invention is to provide a secondary battery having a large charge-discharge capacity. Or, one aspect of the present invention is to provide a secondary battery in which a decrease in capacity during charge-discharge cycles is suppressed. Or, one aspect of the present invention is to provide a secondary battery having high safety or reliability.

[0010] Or, one aspect of the present invention is to provide a novel substance, active material particles, power storage device, or a method for producing them.

[0011] Note that the description of these problems does not prevent the existence of other problems. Note that one aspect of the present invention does not need to solve all of these problems. Note that it is possible to extract other problems from the description of the specification, drawings, and claims. [Means for Solving the Problems]

[0012] In one aspect of the present invention, a buffer layer or a protective layer is provided on the surface of the current collector or between the current collector layer and the active material layer in order to prevent deterioration such as oxidation of the current collector.

[0013] As the buffer layer or the protective layer, it is preferable to use a conductive material. Also, it is preferable to use a material that is easy to suppress oxidation. For example, titanium oxide which is a titanium compound, titanium oxide in which part of oxygen is substituted by nitrogen, titanium nitride, titanium nitride in which part of nitrogen is substituted by oxygen, or titanium oxynitride (TiO x N y , 0 < x < 2, 0 < y < 1) etc. can be applied. Among them, titanium nitride is particularly preferable because it has high conductivity and a high function of suppressing oxidation.

[0014] One aspect of the present invention has a laminate in which a positive electrode current collector layer which is a collection of first metal particles, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector layer which is a collection of second metal particles are laminated in this order, and has a first buffer layer between the first metal particles and the positive electrode active material layer, or a second buffer layer between the negative electrode active material layer and the second metal particles. It is a secondary battery.

[0015] In the above configuration, the first buffer layer contains titanium nitride particles. Also, in the above configuration, the second buffer layer contains titanium nitride particles.

[0016] Also, in the above configuration, the first metal particles may further be metal particles having a titanium nitride film formed on the surface.

[0017] Also, in the above configuration, the second metal particles may further be metal particles having a titanium nitride film formed on the surface.

[0018] Also, a secondary battery using metal particles having a titanium nitride film formed on the surface for the positive electrode current collector layer is also one of the present inventions, and the configuration of the invention is a positive electrode current collector layer which is a collection of first metal particles, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, It is a secondary battery having a laminate in which a negative electrode current collector layer which is a collection of second metal particles is laminated in this order, and the first metal particles are metal particles having a titanium nitride film formed on the surface.

[0019] In addition, a secondary battery using metal particles with a titanium nitride film formed on the surface as a negative electrode current collector layer is also one of the present inventions. The configuration of the invention has a laminate laminated in the order of a positive electrode current collector layer which is a collection of first metal particles, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector layer which is a collection of second metal particles. The second metal particles are metal particles with a titanium nitride film formed on the surface, and it is a secondary battery.

[0020] In this specification and the like, the electrolyte shall include not only solid electrolytes but also electrolytic solutions in which a lithium salt is dissolved in a liquid solvent and electrolytic solutions in which a lithium salt is dissolved in a gel-like compound.

Advantages of the Invention

[0021] According to one aspect of the present invention, it is possible to provide a secondary battery in which side reactions hardly occur at the interface between the positive electrode active material and the electrolyte, the interface between the positive electrode active material and the positive electrode current collector, etc., even when charge and discharge are repeated. It is possible to provide a secondary battery in which the crystal structure is hardly broken even when charge and discharge are repeated. In addition, it is possible to provide a secondary battery having excellent charge and discharge cycle characteristics. In addition, it is possible to provide a secondary battery having a large charge and discharge capacity. In addition, it is possible to provide a secondary battery in which a decrease in capacity during charge and discharge cycles is suppressed. In addition, it is possible to provide a secondary battery with high safety or reliability.

[0022] In addition, according to one aspect of the present invention, it is possible to provide a novel substance, active material particles, power storage device, or a method for producing them.

[0023] Note that the description of these effects does not prevent the existence of other effects. Note that one aspect of the present invention does not necessarily have to have all of these effects. Note that other effects will naturally become clear from the descriptions in the specification, drawings, claims, etc., and it is possible to extract these other effects from the descriptions in the specification, drawings, claims, etc.

Brief Description of the Drawings

[0024]

Figure 1

Figure 2

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Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Embodiments for Carrying Out the Invention

[0025] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and those skilled in the art can easily understand that its form and details can be variously changed. Further, the present invention is not construed as being limited to the description of the embodiments shown below.

[0026] (Embodiment 1) Fig. 1A shows a perspective view of an all-solid-state secondary battery having external electrodes 71 and 72 and sealed with a package member.

[0027] Further, an example of a cross-section cut along the dotted line in Fig. 1A is shown in Fig. 1B. The laminate is enclosed and sealed by a package member 70a provided with a positive electrode current collector layer 73a containing metal particles, a frame-shaped package member 70b, and a package member 70c provided with a negative electrode current collector layer 73b containing metal particles. As the package members 70a, 70b, and 70c, an insulating material, for example, a resin material or a ceramic can be used.

[0028] The external electrode 72 is electrically connected to the positive electrode active material layer 50a through a positive electrode current collector layer 73a having a buffer layer 74 on both sides or one side, and functions as a positive electrode. The external electrode 71 is electrically connected to the negative electrode active material layer 50c through a negative electrode current collector layer 73b having a buffer layer 74 on both sides, and functions as a negative electrode.

[0029] Aluminum particles or copper particles are used for the positive electrode current collector layer 73a.

[0030] As the buffer layer 74, titanium nitride which is a titanium compound, titanium nitride partially substituted with oxygen, or titanium oxynitride (TiO x N y , 0 < x < 2, 0 < y < 1) etc. can be applied. Among them, titanium nitride is particularly preferable because it has high conductivity and a high function of suppressing oxidation. In the present embodiment, titanium nitride powder (particle size 0.7 μm or more and 2.5 μm) is used.

[0031] The positive electrode active material layer 50a has lithium, transition metal M, and oxygen. It can also be said that the positive electrode active material layer 50a has a composite oxide containing lithium and transition metal M.

[0032] As the transition metal M included in the positive electrode active material layer 50a, it is preferable to use a metal that can form a layered rock salt type composite oxide belonging to the space group R-3m together with lithium. As the transition metal M, for example, one or more of manganese, cobalt, and nickel can be used. That is, only cobalt may be used as the transition metal included in the positive electrode active material layer 50a, only nickel may be used, two types of cobalt and manganese, or two types of cobalt and nickel may be used, or three types of cobalt, manganese, and nickel may be used. That is, the positive electrode active material layer 50a can have a composite oxide containing lithium and the transition metal M, such as lithium cobaltate, lithium nickelate, lithium cobaltate in which a part of cobalt is substituted with manganese, lithium cobaltate in which a part of cobalt is substituted with nickel, and lithium nickel-manganese-cobaltate.

[0033] In addition to the transition metal M described above, the positive electrode active material layer 50a may contain elements other than the transition metal M such as magnesium, fluorine, and aluminum. These elements may stabilize the crystal structure of the positive electrode active material layer 50a. That is, the positive electrode active material layer 50a can have lithium cobaltate added with magnesium and fluorine, lithium nickel-cobaltate added with magnesium and fluorine, lithium cobalt-aluminate added with magnesium and fluorine, lithium nickel-cobalt-aluminate, and lithium nickel-cobalt-aluminate added with magnesium and fluorine.

[0034] When the positive electrode active material layer 50a contains lithium, cobalt, nickel, aluminum, magnesium, oxygen, and fluorine, when the atomic ratio of cobalt in the positive electrode active material layer 50a is 100, the atomic ratio of nickel is preferably, for example, 0.05 or more and 2 or less, more preferably 0.1 or more and 1.5 or less, and still more preferably 0.1 or more and 0.9 or less. When the atomic ratio of cobalt in the positive electrode active material layer 101 is 100, the atomic ratio of aluminum is preferably, for example, 0.05 or more and 2 or less, more preferably 0.1 or more and 1.5 or less, and still more preferably 0.1 or more and 0.9 or less. When the atomic ratio of cobalt in the positive electrode active material layer 50a is 100, the atomic ratio of magnesium is preferably, for example, 0.1 or more and 6 or less, more preferably 0.3 or more and 3 or less. Further, when the atomic ratio of magnesium in the positive electrode active material layer 50a is 1, the atomic ratio of fluorine is preferably, for example, 2 or more and 3.9 or less.

[0035] By having nickel, aluminum, and magnesium at the above concentrations, a stable crystal structure can be maintained even when repeatedly charging and discharging at a high voltage with a small particle size. Therefore, a positive electrode active material layer 50a with high capacity and excellent charge and discharge cycle characteristics can be obtained.

[0036] As the solid electrolyte layer 50b, for example, a sulfide-based solid electrolyte, an oxide-based solid electrolyte, a halide-based solid electrolyte, etc. can be used.

[0037] Among the sulfide-based solid electrolytes, there are thiolsilicon-based (Li 10 GeP 2 S 12 、Li 3.25 Ge 0.25 P 0.75 S 4 etc.), sulfide glasses (70Li 2 S·30P 2 S 5 、30Li 2 S·26B 2 S 3 ·44LiI、63Li 2 S·38SiS 2 ·1Li 3 PO 4 、57Li2 S·38SiS 2 ·5Li 4 SiO 4 、50Li 2 S·50GeS 2 etc.), sulfide crystallized glass (Li 7 P 3 S 11 、Li 3.25 P 0.95 S 4 etc.) are included. Sulfide-based solid electrolytes have advantages such as containing materials with high conductivity, being synthesizable at low temperatures, and being relatively soft so that the conductive path is easily maintained even after charge and discharge.

[0038] Oxide-based solid electrolytes include materials having a perovskite-type crystal structure (La 2 / 3-x Li 3x TiO 3 etc.), materials having a NASICON-type crystal structure (Li 1-X Al X Ti 2-X (PO 4 ) 3 etc.), materials having a garnet-type crystal structure (Li 7 La 3 Zr 2 O 12 etc.), materials having a LISICON-type crystal structure (Li 14 ZnGe 4 O 16 etc.), oxide glass (Li 3 PO 4 -Li 4 SiO 4 、50Li 4 SiO 4 ·50Li 3 BO 3 etc.), oxide crystallized glass (Li 1.07 Al 0.69 Ti 1.46 (PO 4 ) 3 、Li 1.5 Al 0.5 Ge 1.5 (PO 4 ) 3 etc.) are included. Oxide-based solid electrolytes have the advantage of being stable in the atmosphere.

[0039] Halide-based solid electrolytes include LiAlCl 4 , Li 3 InBr 6 , LiF, LiCl, LiBr, LiI, etc. In addition, composite materials in which these halide-based solid electrolytes are filled in the pores of porous alumina or porous silica can also be used as solid electrolytes.

[0040] Also, different solid electrolytes may be mixed and used.

[0041] Among them, Li 1+x Al x Ti 2-x (PO 4 ) 3 (0 < x < 1) (hereinafter referred to as LATP), and the positive electrode active material of one embodiment of the present invention contains a common element of aluminum, so a synergistic effect can be expected for improving cycle characteristics, which is preferable. In addition, an improvement in productivity due to reduction of processes can also be expected. In this specification, etc., the NASICON-type crystal structure means a compound represented by M 2 (XO 4 ) 3 (M: transition metal, X: S, P, As, Mo, W, etc.), and refers to a compound having a structure in which MO 6 octahedrons and XO 4 tetrahedrons share vertices and are three-dimensionally arranged.

[0042] As the negative electrode active material layer 50c, silicon, carbon, titanium oxide, vanadium oxide, indium oxide, zinc oxide, tin oxide, nickel oxide, etc. can be used. In addition, materials that alloy with Li such as tin, gallium, and aluminum can be used. Further, metal oxides that alloy with these Li may be used. Further, lithium titanate (Li 4 Ti 5 O 12 , LiTi 2 O 4 , etc.) may be used, but among them, a material containing silicon and oxygen (also referred to as a SiOx film) is preferable. Further, Li metal may be used as the negative electrode active material layer 50c.

[0043] As the negative electrode current collector layer 73b, copper particles may be used.

[0044] In FIG. 1B, an example is shown in which three laminations are made with a lamination of a positive electrode current collector layer 73a, a buffer layer 74, a positive electrode active material layer 50a, a solid electrolyte layer 50b, a negative electrode active material layer 50c, a buffer layer 74, and a negative electrode current collector layer 73b as one set, but a plurality of them may be further laminated.

[0045] In addition, in FIG. 1B, each layer is shown as a schematic diagram, but each layer is composed of particles and is also called a bulk-type all-solid-state battery. A schematic diagram obtained by enlarging the dotted line portion of FIG. 1B is shown in FIG. 2. In FIG. 2, the shapes of the respective particles are shown as spherical, but this is only a schematic illustration and is not particularly limited to the shapes and sizes in FIG. 2.

[0046] As shown in FIG. 2, a secondary battery 400 according to one aspect of the present invention includes a positive electrode 430, a solid electrolyte layer 50b, and a negative electrode 410.

[0047] In FIG. 2, the positive electrode 430 includes a positive electrode current collector layer 73a, a buffer layer 74, and a positive electrode active material layer 50a. The positive electrode current collector layer 73a may contain a solid electrolyte 421, a conductive material (also called a conductive auxiliary agent), and a binder in addition to the positive electrode active material 431.

[0048] Further, the negative electrode 410 includes a negative electrode current collector layer 73b, a buffer layer 74, and a negative electrode active material layer 50c. The negative electrode current collector layer 73b may contain a solid electrolyte 421, a conductive material (also called a conductive auxiliary agent), and a binder in addition to the negative electrode active material 411.

[0049] The solid electrolyte layer 50b has a solid electrolyte 421. The solid electrolyte layer 420 is located between the positive electrode 430 and the negative electrode 410 and is a region that has neither the positive electrode active material 431 nor the negative electrode active material 411.

[0050] When manufacturing a secondary battery, the positive electrode 430, the solid electrolyte layer 50b, and the negative electrode 410 are each formed into a paste layer by preparing and applying their respective pastes. As the coating method for forming the paste layer, a die coating method, a spray coating method, a dip method, a spin coating method, a relief printing method, an offset printing method, a gravure printing method, a screen printing method, or the like can be used. Further, the positive electrode current collector layer, the negative electrode current collector layer, and the buffer layer are also formed into a paste layer by preparing a paste and applying it onto a support substrate. In order to peel it off later, it is preferable to previously form a material imparting peelability on the support substrate. For example, it is preferable to form a resin film containing a binder or the like as a pretreatment by film formation.

[0051] Each is formed on a support substrate, and the paste layer for the positive electrode current collector layer, the paste layer for the negative electrode current collector layer, the paste layer for the buffer layer, the paste layer for the positive electrode, the paste layer for the solid electrolyte layer, and the paste layer for the negative electrode are peeled off from the support substrate and laminated together.

[0052] The laminate thus laminated is crimped or fired.

[0053] Further, after cutting the laminate into a desired shape, it is surrounded by a package member. Alternatively, the laminate may be configured to be surrounded by a package member after being pressed into a frame so as not to spread.

[0054] Finally, the end faces of the laminate surrounded by the package member are dipped in a conductive paste. Thereafter, by firing, external electrodes 71 and 72 are formed, and a all-solid-state secondary battery sealed with a package member as shown in FIG. 1A can be manufactured.

[0055] The dimensions of the all-solid-state secondary battery shown in FIG. 1A can be manufactured, for example, in a rectangular parallelepiped shape such that the first side × the second side × the height is 3.5 mm × 2.5 mm × 2 mm, 4.5 mm × 3 mm × 1 mm, 10 mm × 10 mm × 6 mm.

[0056] This embodiment can be used in combination with other embodiments.

[0057] (Embodiment 2) In this embodiment, an example that is partially different from Embodiment 1 is shown.

[0058] In Embodiment 1, an example in which the buffer layer is a collection of particles was shown, but in this embodiment, an example in which a buffer layer is formed on the surface of the current collector particles is shown.

[0059] FIG. 3A shows a schematic cross-sectional view of the secondary battery 500. Note that the same reference numerals are used for the parts common to FIG. 1B for explanation. The difference in FIG. 3A is that the buffer layer 74 in FIG. 1B is not shown.

[0060] Further, FIG. 3B is an example of an enlarged view of the dotted line portion in FIG. 3A, and the same reference numerals are used for the parts common to FIG. 2 for explanation. The difference between FIG. 3B and FIG. 2 is that the buffer layer 74 is formed on the surface of the current collector particles.

[0061] The current collector particles coated with the buffer layer 74 can be produced by forming a film on the surface of the current collector particles using a barrel sputtering method or the like.

[0062] In FIG. 3B, an example in which the buffer layer 74 is formed on the surface of the positive electrode current collector particles and the buffer layer 74 is formed on the surface of the negative electrode current collector particles is shown, but it is not particularly limited, and the buffer layer may be formed on only one of them.

[0063] Further, this embodiment can be freely combined with Embodiment 1.

[0064] (Embodiment 3) As the positive electrode active material 431 shown in Embodiment 1 or Embodiment 2, a positive electrode active material containing lithium, cobalt, magnesium, aluminum, nickel, oxygen, and fluorine may be used.

[0065] Regarding the production of the positive electrode active material, it is shown below using the production flow shown in FIG. 4.

[0066] <Step S21> First, prepare a halogen source such as a fluorine source or a chlorine source, a magnesium source, a nickel source, and an aluminum source as materials for the mixture 901. It is also preferable to prepare a lithium source.

[0067] As the fluorine source, for example, lithium fluoride, magnesium fluoride, etc. can be used. Among them, lithium fluoride has a relatively low melting point of 848 °C and is preferable because it is easily melted in the annealing process described later. As the chlorine source, for example, lithium chloride, magnesium chloride, etc. can be used. As the magnesium source, for example, magnesium fluoride, magnesium oxide, magnesium hydroxide, magnesium carbonate, etc. can be used. As the lithium source, for example, lithium fluoride, lithium carbonate can be used. That is, lithium fluoride can be used as both a lithium source and a fluorine source. Also, magnesium fluoride can be used as both a fluorine source and a magnesium source.

[0068] In this embodiment, lithium fluoride LiF is prepared as the fluorine source and the lithium source, and magnesium fluoride MgF 2 is prepared (step S21 in FIG. 4).

[0069] Lithium fluoride LiF and magnesium fluoride MgF 2 have the highest effect of lowering the melting point when mixed at about LiF:MgF 2 = 65:35 (molar ratio). On the other hand, if the amount of lithium fluoride increases, there is a concern that lithium will be excessive and the cycle characteristics will deteriorate. Therefore, the molar ratio of lithium fluoride LiF and magnesium fluoride MgF 2 is preferably LiF:MgF 2 = x:1 (0 ≤ x ≤ 1.9), more preferably LiF:MgF 2 = x:1 (0.1 ≤ x ≤ 0.5), and even more preferably LiF:MgF 2 = x:1 (x is around 0.33).

[0070] As the nickel source, for example, nickel hydroxide (Ni(OH)2 ) can be used. At this time, the nickel source is preferably micronized. For example, by using a ball mill, a bead mill, etc., and mixing and pulverizing nickel hydroxide with acetone as a solvent, micronized nickel hydroxide can be obtained.

[0071] As the aluminum source, for example, aluminum hydroxide (Al(OH) 3 ) can be used. The aluminum source is preferably micronized. For example, by using a ball mill, a bead mill, etc., and mixing and pulverizing aluminum hydroxide with acetone as a solvent, micronized aluminum hydroxide can be obtained.

[0072] Also, when performing the following mixing and pulverizing steps wet, a solvent is prepared. As the solvent, ketones such as acetone, alcohols such as ethanol and isopropanol, ether, dioxane, acetonitrile, N-methyl-2-pyrrolidone (NMP), etc. can be used. It is more preferable to use an aprotic solvent that hardly reacts with lithium. In this embodiment, acetone is used (see step S21 in FIG. 4).

[0073] <Step S22> Next, the materials of the above mixture 901 are mixed and pulverized (step S22 in FIG. 4). The mixing can be performed dry or wet, but wet is preferable because it can pulverize more finely. For mixing, for example, a ball mill, a bead mill, etc. can be used. When using a ball mill, it is preferable to use zirconia balls as the media, for example. It is preferable to perform this mixing and pulverizing step sufficiently to micronize the mixture 901.

[0074] The mixing means is preferably mixing by a blender, a mixer, or a ball mill.

[0075] <Step S23, Step S24> Collect the material mixed and pulverized above (step S23 in FIG. 4) to obtain a mixture 901 (step S24 in FIG. 4).

[0076] The mixture 902 preferably has a D50 of 600 nm or more and 20 μm or less, more preferably 1 μm or more and 10 μm or less. With the mixture 902 micronized in this way, when it is mixed with a composite oxide having lithium, a transition metal, and oxygen in a later step, it is easy to uniformly adhere the mixture 902 to the surface of the composite oxide particles. When the mixture 902 is uniformly adhered to the surface of the composite oxide particles, it is preferable because it is easy to distribute halogen and magnesium in the surface layer portion of the composite oxide particles after heating. If there is a region in the surface layer portion that does not contain halogen and magnesium, there is a possibility that it is difficult to form the O3'-type crystal structure described later in the charged state.

[0077] <Step S25> Use a composite oxide having lithium, a transition metal, and oxygen that has been synthesized in advance as step S25 in FIG. 4.

[0078] When using a composite oxide having lithium, a transition metal, and oxygen that has been synthesized in advance, it is preferable to use one with less impurities. In this specification and the like, for the composite oxide having lithium, a transition metal, and oxygen, and the positive electrode active material, the main components are lithium, cobalt, nickel, manganese, aluminum, and oxygen, and elements other than the above main components are regarded as impurities. For example, when analyzed by glow discharge mass spectrometry, the total impurity concentration is preferably 10,000 ppm wt or less, more preferably 5000 ppm wt or less. In particular, the total impurity concentration of transition metals such as titanium and arsenic is preferably 3000 ppm wt or less, more preferably 1500 ppm wt or less.

[0079] For example, as the pre-synthesized lithium cobaltate, lithium cobaltate particles (trade name: Celseed C-10N) manufactured by Nippon Chemical Industry Co., Ltd. can be used. This has a median diameter (D50) of about 12 μm, and in impurity analysis by glow discharge mass spectrometry (GD-MS), the magnesium concentration and fluorine concentration are 50 ppm wt or less, the calcium concentration, aluminum concentration and silicon concentration are 100 ppm wt or less, the nickel concentration is 150 ppm wt or less, the sulfur concentration is 500 ppm wt or less, the arsenic concentration is 1100 ppm wt or less, and the concentration of elements other than lithium, cobalt and oxygen is 150 ppm wt or less. It is lithium cobaltate.

[0080] The composite oxide containing lithium, transition metal and oxygen in step S25 preferably has a layered rock salt-type crystal structure with few defects and strains. Therefore, it is preferably a composite oxide with few impurities. If the composite oxide containing lithium, transition metal and oxygen contains a large amount of impurities, it is highly likely to have a crystal structure with many defects or strains.

[0081] <Step S31> Next, the mixture 901 is mixed with a composite oxide containing lithium, transition metal and oxygen (step S31 in FIG. 4). The ratio of the number of atoms TM of the transition metal in the composite oxide containing lithium, transition metal and oxygen to the number of atoms MgMix1 of magnesium in the mixture 902 is preferably TM:MgMix1 = 1:y (0.005 ≦ y ≦ 0.05), more preferably TM:MgMix1 = 1:y (0.007 ≦ y ≦ 0.04), and even more preferably about TM:MgMix1 = 1:0.02.

[0082] The mixing in step S31 is preferably carried out under milder conditions than the mixing in step S22 so as not to break the particles of the composite oxide. For example, it is preferable to set conditions with a lower rotation speed or a shorter time than the mixing in step S22. Also, it can be said that the dry condition is milder than the wet condition. For mixing, for example, a ball mill, a bead mill, etc. can be used. When using a ball mill, it is preferable to use zirconia balls as media, for example.

[0083] The above - mixed material is recovered (step S32 in FIG. 4), and a mixture 903 is obtained (step S33 in FIG. 4).

[0084] Next, the mixture 903 is heated (step S34 in FIG. 4). This step may be referred to as annealing or firing.

[0085] Annealing is preferably carried out at an appropriate temperature and time. The appropriate temperature and time vary depending on conditions such as the particle size and composition of the composite oxide having lithium, transition metal, and oxygen in step S25. When the particles are small, a lower temperature or a shorter time may be more preferable than when they are large.

[0086] For example, when the median diameter (D50) of the particles in step S25 is about 12 μm, the annealing temperature is preferably 700 °C or higher and 950 °C or lower, for example. The annealing time is preferably 3 hours or more, more preferably 10 hours or more, and even more preferably 60 hours or more.

[0087] The temperature - lowering time after annealing is preferably 10 hours or more and 50 hours or less, for example.

[0088] When the mixture 903 is annealed, first, the material with a lower melting point in the mixture 903 (for example, lithium fluoride, melting point 848 °C) melts and is considered to be distributed on the surface layer of the composite oxide particles. Next, due to the presence of this melted material, the melting point of other materials drops, and it is speculated that other materials melt. For example, magnesium fluoride (melting point 1263 °C) melts and is considered to be distributed on the surface layer of the composite oxide particles.

[0089] The diffusion of the elements in this mixture 903 is faster in the surface layer and near the grain boundaries than in the interior of the composite oxide particles. Therefore, magnesium and halogen become higher in concentration in the surface layer and near the grain boundaries than in the interior. As will be described later, when the magnesium concentration in the surface layer and near the grain boundaries is high, the change in the crystal structure can be more effectively suppressed.

[0090] The annealed material is recovered (step S35 in FIG. 4). Further, it is preferable to sieve the particles. In the above process, the positive electrode active material 200A of one aspect of the present invention can be produced (step S36 in FIG. 4).

[0091] The positive electrode active material 200A will be described with reference to FIGS. 6 to 9.

[0092] <Conventional positive electrode active material> The positive electrode active material shown in FIG. 8 is lithium cobaltate (LiCoO 2 ) to which halogen and magnesium are not added by the production method described later. The lithium cobaltate shown in FIG. 8 changes its crystal structure depending on the depth of charge.

[0093] As shown in FIG. 8, lithium cobaltate at a charge depth of 0 (discharged state) has a region with a crystal structure of space group R-3m, lithium occupies the octahedral site, and there are 3 layers of CoO 2 layers in the unit cell. Therefore, this crystal structure is sometimes called an O3-type crystal structure. Note that the CoO 2 layer refers to a structure in which an octahedral structure with oxygen coordinated to cobalt in a 6-fold coordination is continuous in a plane in a state of sharing edges.

[0094] Also, when the depth of charge is 1, it has a crystal structure of space group P-3m1, and there is one layer of CoO in the unit cell. Therefore, this crystal structure may be referred to as the O1-type crystal structure. 2 There is one layer of CoO in the unit cell. Therefore, this crystal structure may be referred to as the O1-type crystal structure.

[0095] Also, lithium cobaltate when the depth of charge is about 0.8 has a crystal structure of space group R-3m. This structure can also be said to be a structure in which the structure of CoO such as P-3m1 (O1) and the structure of LiCoO such as R-3m (O3) are alternately stacked. Therefore, this crystal structure may be referred to as the H1-3 type crystal structure. In actuality, in the H1-3 type crystal structure, the number of cobalt atoms per unit cell is twice that of other structures. However, in this specification including FIG. 8, for ease of comparison with other structures, the c-axis of the H1-3 type crystal structure will be shown in a figure with it being 1 / 2 of the unit cell. 2 the structure of CoO such as P-3m1 (O1) and 2 the structure of LiCoO such as R-3m (O3) are alternately stacked. Therefore, this crystal structure may be referred to as the H1-3 type crystal structure. In actuality, in the H1-3 type crystal structure, the number of cobalt atoms per unit cell is twice that of other structures. However, in this specification including FIG. 8, for ease of comparison with other structures, the c-axis of the H1-3 type crystal structure will be shown in a figure with it being 1 / 2 of the unit cell.

[0096] As an example, the H1-3 type crystal structure, as described in Non-Patent Document 3, the coordinates of cobalt and oxygen in the unit cell can be expressed as Co(0, 0, 0.42150 ± 0.00016), O 1 (0, 0, 0.27671 ± 0.00045), O 2 (0, 0, 0.11535 ± 0.00045). O 1 and O 2 are oxygen atoms respectively. Thus, the H1-3 type crystal structure is represented by a unit cell using one cobalt and two oxygens. On the other hand, as will be described later, the O3'-type crystal structure of one aspect of the present invention is preferably represented by a unit cell using one cobalt and one oxygen. This indicates that in the case of the O3'-type crystal structure and the H1-3 type structure, the symmetry between cobalt and oxygen is different, and the change from the O3 structure in the O3'-type crystal structure is smaller than that in the H1-3 type structure. For the selection of which unit cell is more preferable for representing the crystal structure of the positive electrode active material, for example, in the Rietveld analysis of XRD, it may be selected so that the value of GOF (good of fitness) becomes smaller.

[0097] When high-voltage charging is performed such that the charging voltage is 4.6 V or more based on the redox potential of lithium metal, or deep charging is performed such that the depth of charge is 0.8 or more, and charging and discharging are repeated, lithium cobaltate repeats a change in crystal structure (i.e., a non-equilibrium phase change) between the H1-3 type crystal structure and the R-3m (O3) structure in the discharged state.

[0098] However, the shift in the CoO 2 layers is large between these two crystal structures. As shown by the dotted lines and arrows in Fig. 8, in the H1-3 type crystal structure, the CoO 2 layers are significantly shifted from R-3m (O3). Such dynamic structural changes can have an adverse effect on the stability of the crystal structure.

[0099] Furthermore, the volume difference is also large. When compared per the same number of cobalt atoms, the volume difference between the H1-3 type crystal structure and the O3 type crystal structure in the discharged state is 3.0% or more.

[0100] In addition, the structure in which CoO 2 layers such as P-3m1 (O1) in the H1-3 type crystal structure are continuous is likely to be unstable.

[0101] Therefore, when high-voltage charge and discharge are repeated, the crystal structure of lithium cobaltate collapses. The collapse of the crystal structure causes deterioration of the cycle characteristics. This is presumably because when the crystal structure collapses, the sites where lithium can stably exist decrease, and it becomes difficult for lithium to be inserted and removed.

[0102] <Positive electrode active material 200A according to one aspect of the present invention> ≪Inside≫ The positive electrode active material 200A according to one aspect of the present invention, in repeated high-voltage charge and discharge, CoO 2The layer displacement can be reduced. Furthermore, the volume change can be reduced. Therefore, the cathode active material according to one aspect of the present invention can achieve excellent cycle characteristics. In addition, the cathode active material according to one aspect of the present invention can have a stable crystal structure in a charged state at a high voltage. Therefore, when the cathode active material according to one aspect of the present invention holds a charged state at a high voltage, a short circuit may be less likely to occur. In such a case, the safety is further improved, which is preferable.

[0103] In the cathode active material according to one aspect of the present invention, the change in crystal structure and the volume difference per the same number of transition metal atoms in a fully discharged state and a state charged at a high voltage are small.

[0104] The crystal structure of the cathode active material 200A before and after charge and discharge is shown in FIG. 6. The cathode active material 200A is a composite oxide having lithium, cobalt as a transition metal, and oxygen. In addition to the above, it preferably has magnesium as an additive. It also preferably has a halogen such as fluorine or chlorine as an additive.

[0105] The crystal structure at a charge depth of 0 (discharged state) in FIG. 6 is the same R-3m (O3) as in FIG. 8. On the other hand, the cathode active material 200A has crystals having a structure different from the H1-3 type crystal structure when fully charged. This structure is the space group R-3m and is not a spinel type crystal structure, but ions such as cobalt and magnesium occupy the oxygen 6-coordination positions, and the arrangement of the cations has symmetry similar to that of the spinel type. Also, the CoO of this structure 2 The layer symmetry is the same as that of the O3 type. Therefore, in this specification, etc., this structure is referred to as an O3' type crystal structure or a pseudo-spinel type crystal structure. Therefore, the O3' type crystal structure may be rephrased as a pseudo-spinel type crystal structure. In the diagram of the O3' type crystal structure shown in FIG. 6, the display of lithium is omitted in order to explain the symmetry of cobalt atoms and oxygen atoms, but actually CoO 2 There is, for example, 20 atomic% or less of lithium relative to cobalt between the layers. Also, in both the case of the O3 type crystal structure and the O3' type crystal structure, CoO2 It is preferable that magnesium is thinly present between the layers, that is, at the lithium sites. Further, it is preferable that a halogen such as fluorine is randomly and thinly present at the oxygen sites.

[0106] In addition, in the O3’-type crystal structure, light elements such as lithium may occupy the oxygen four-coordination positions. In this case as well, the ion arrangement has symmetry similar to that of the spinel type.

[0107] Also, the O3’-type crystal structure can be said to be a crystal structure similar to that of the CdCl 2 type. This crystal structure similar to the CdCl 2 type is close to the crystal structure when lithium nickelate is charged to a charge depth of 0.94 (Li 0.06 NiO 2 ). However, it is known that pure lithium cobaltate or a layered rock salt-type positive electrode active material containing a large amount of cobalt usually does not take this crystal structure.

[0108] In the positive electrode active material 200A according to one aspect of the present invention, the change in the crystal structure when charged at a high voltage and a large amount of lithium is removed is suppressed more than that of the conventional positive electrode active material. For example, as shown by the dotted line in FIG. 6, in these crystal structures, there is almost no shift in the CoO 2 layers.

[0109] More specifically, the positive electrode active material 200A according to one aspect of the present invention has high structural stability even when the charging voltage is high. For example, in a conventional positive electrode active material, there is a region of charging voltage where the crystal structure of R-3m (O3) can be maintained even at a charging voltage that results in an H1-3 type crystal structure, for example, a voltage of about 4.6V based on the potential of lithium metal. Further, there is a region where an O3' type crystal structure can be adopted even in a region where the charging voltage is increased, for example, at a voltage of about 4.65V to 4.7V based on the potential of lithium metal. Only when the charging voltage is further increased, an H1-3 type crystal may be observed. In addition, when graphite is used as the negative electrode active material in a secondary battery, for example, there is a region of charging voltage where the crystal structure of R-3m (O3) can be maintained even when the voltage of the secondary battery is 4.3V or more and 4.5V or less. Further, there is a region where an O3' type crystal structure can be adopted even in a region where the charging voltage is increased, for example, at a voltage of 4.35V or more and 4.55V or less based on the potential of lithium metal.

[0110] Therefore, in the positive electrode active material 200A according to one aspect of the present invention, the crystal structure is not easily broken even when charging and discharging are repeated at a high voltage.

[0111] In addition, in the positive electrode active material 200A, the difference in volume per unit cell between the O3 type crystal structure at a charging depth of 0 and the O3' type crystal structure at a charging depth of 0.8 is 2.5% or less, more specifically 2.2% or less.

[0112] The O3' type crystal structure can be represented by the coordinates of cobalt and oxygen in the unit cell within the range of Co(0,0,0.5), O(0,0,x), and 0.20 ≤ x ≤ 0.25.

[0113] CoO 2 Additives, such as magnesium, which are randomly and thinly present in the interlayer, that is, the lithium site, have the effect of suppressing the layer shift. Therefore, CoO 2 has the effect of suppressing the layer shift. Therefore, CoO 2When magnesium is present between layers, it is likely to form an O3'-type crystal structure. Therefore, it is preferable that magnesium is distributed throughout the particles of the positive electrode active material 200A according to one aspect of the present invention. Further, in order to distribute magnesium throughout the particles, it is preferable to perform a heat treatment in the process of producing the positive electrode active material 200A according to one aspect of the present invention.

[0114] However, if the temperature of the heat treatment is too high, cation mixing occurs and there is an increased possibility that an additive, for example magnesium, enters the cobalt site. Magnesium present in the cobalt site has no effect of maintaining the R-3m structure during high-voltage charging. Further, if the temperature of the heat treatment is too high, there are also concerns about adverse effects such as cobalt being reduced to divalent and lithium evaporating.

[0115] Therefore, it is preferable to add a halogen compound such as a fluorine compound to lithium cobaltate before the heat treatment for distributing magnesium throughout the particles. Adding the halogen compound causes a melting point drop of lithium cobaltate. By lowering the melting point, it becomes easy to distribute magnesium throughout the particles at a temperature at which cation mixing is less likely to occur. Further, if a fluorine compound is present, it can be expected that the corrosion resistance against hydrofluoric acid generated by the decomposition of the electrolytic solution is improved.

[0116] In addition, if the magnesium concentration is increased to a value equal to or higher than a desired value, the effect on the stabilization of the crystal structure may be reduced. This is presumably because magnesium enters not only the lithium site but also the cobalt site. The number of magnesium atoms in the positive electrode active material according to one aspect of the present invention is preferably 0.001 times or more and 0.1 times or less, more preferably more than 0.01 and less than 0.04, and even more preferably about 0.02, based on the number of transition metal atoms. The magnesium concentration shown here may be, for example, a value obtained by performing elemental analysis of the entire particles of the positive electrode active material using ICP-MS or the like, or may be based on the value of the raw material formulation in the process of producing the positive electrode active material.

[0117] One or more metals selected from, for example, nickel, aluminum, manganese, titanium, vanadium, and chromium may be added to lithium cobaltate as a metal other than cobalt (hereinafter referred to as metal Z), and it is particularly preferable to add one or more of nickel and aluminum. Manganese, titanium, vanadium, and chromium may tend to stably take a tetravalent state and may contribute highly to structural stability. By adding metal Z, in the positive electrode active material of one aspect of the present invention, for example, the crystal structure may become more stable in a charged state at a high voltage. Here, in the positive electrode active material of one aspect of the present invention, metal Z is preferably added at a concentration that does not significantly change the crystallinity of lithium cobaltate. For example, it is preferably an amount that does not exhibit the aforementioned Jahn-Teller effect or the like.

[0118] As shown in the legend in FIG. 6, transition metals such as nickel and manganese and aluminum preferably exist at the cobalt site, but a part of them may exist at the lithium site. Magnesium preferably exists at the lithium site. Oxygen may be partially substituted with fluorine.

[0119] As the magnesium concentration of the positive electrode active material of one aspect of the present invention increases, the capacity of the positive electrode active material may decrease. As a factor, for example, it is conceivable that the amount of lithium contributing to charge and discharge may decrease when magnesium enters the lithium site. In addition, excessive magnesium may generate a magnesium compound that does not contribute to charge and discharge. By having nickel as metal Z in addition to magnesium in the positive electrode active material of one aspect of the present invention, the capacity per unit weight and per unit volume may be increased in some cases. Also, by having aluminum as metal Z in addition to magnesium in the positive electrode active material of one aspect of the present invention, the capacity per unit weight and per unit volume may be increased in some cases. Further, by having nickel and aluminum in addition to magnesium in the positive electrode active material of one aspect of the present invention, the capacity per unit weight and per unit volume may be increased in some cases.

[0120] The concentrations of elements such as magnesium and metal Z in the positive electrode active material of one embodiment of the present invention are represented by the number of atoms.

[0121] The number of atoms of nickel in the positive electrode active material of one embodiment of the present invention is preferably 10% or less, more preferably 7.5% or less, still more preferably 0.05% or more and 4% or less, and particularly preferably 0.1% or more and 2% or less of the number of atoms of cobalt. The nickel concentration shown here may be, for example, a value obtained by performing elemental analysis of the entire particles of the positive electrode active material using ICP-MS or the like, or may be based on the value of the raw material formulation in the process of producing the positive electrode active material.

[0122] When the state of being charged at a high voltage is maintained for a long time, there is a risk that transition metals elute from the positive electrode active material into the electrolytic solution and the crystal structure collapses. However, by having nickel in the above ratio, elution of transition metals from the positive electrode active material 200A may be suppressed.

[0123] The number of atoms of aluminum in the positive electrode active material of one embodiment of the present invention is preferably 0.05% or more and 4% or less, more preferably 0.1% or more and 2% or less of the number of atoms of cobalt. The aluminum concentration shown here may be, for example, a value obtained by performing elemental analysis of the entire particles of the positive electrode active material using ICP-MS or the like, or may be based on the value of the raw material formulation in the process of producing the positive electrode active material.

[0124] The positive electrode active material of one embodiment of the present invention preferably has element X, and preferably uses phosphorus as element X. Further, the positive electrode active material of one embodiment of the present invention more preferably has a compound containing phosphorus and oxygen.

[0125] When the positive electrode active material of one embodiment of the present invention has a compound containing element X, short circuits may be less likely to occur when the charged state at a high voltage is maintained.

[0126] When the positive electrode active material of one embodiment of the present invention has phosphorus as element X, hydrogen fluoride generated by the decomposition of the electrolytic solution may react with phosphorus, and the hydrogen fluoride concentration in the electrolytic solution may decrease.

[0127] When the electrolyte contains LiPF 6 Hydrogen fluoride may be generated by hydrolysis. In addition, hydrogen fluoride may also be generated by the reaction between PVDF used as a component of the positive electrode and an alkali. By reducing the hydrogen fluoride concentration in the electrolyte, corrosion of the current collector and / or peeling of the film may be suppressed in some cases. In addition, a decrease in adhesiveness due to gelation and / or insolubilization of PVDF may be suppressed in some cases.

[0128] When the positive electrode active material of one aspect of the present invention contains magnesium in addition to element X, the stability in a high-voltage charged state is extremely high. When element X is phosphorus, the number of phosphorus atoms is preferably 1% or more and 20% or less, more preferably 2% or more and 10% or less, still more preferably 3% or more and 8% or less of the number of cobalt atoms. In addition, the number of magnesium atoms is preferably 0.1% or more and 10% or less, more preferably 0.5% or more and 5% or less, still more preferably 0.7% or more and 4% or less of the number of cobalt atoms. The concentrations of phosphorus and magnesium shown here may be values obtained by performing elemental analysis of the entire particles of the positive electrode active material using, for example, ICP-MS or the like, or may be based on the values of the raw material formulation in the process of producing the positive electrode active material.

[0129] When the positive electrode active material has cracks, the progress of the cracks may be suppressed by the presence of phosphorus, more specifically, a compound containing, for example, phosphorus and oxygen, inside the cracks.

[0130] As is clear from the oxygen atoms indicated by the arrows in FIG. 6, the symmetry of the oxygen atoms is slightly different between the O3-type crystal structure and the O3'-type crystal structure. Specifically, in the O3-type crystal structure, the oxygen atoms are aligned along the dotted line, whereas the oxygen atoms in the O3'-type crystal structure are not strictly aligned. This is because in the O3'-type crystal structure, as lithium decreases, tetravalent cobalt increases, the Jahn-Teller distortion increases, and the octahedral structure of CoO 6 is distorted. In addition, as lithium decreases, the repulsion between oxygen atoms in the CoO 2 layer also becomes stronger, which also has an effect.

[0131] ≪Surface portion≫ Magnesium is preferably distributed throughout the particles of the positive electrode active material 200A according to one embodiment of the present invention. In addition to this, it is preferable that the magnesium concentration in the surface portion is higher than the average of the whole particles. For example, it is preferable that the magnesium concentration in the surface portion measured by XPS or the like is higher than the average magnesium concentration of the whole particles measured by ICP-MS or the like.

[0132] Further, when the positive electrode active material 200A according to one embodiment of the present invention has one or more metals selected from elements other than cobalt, such as nickel, aluminum, manganese, iron, and chromium, it is preferable that the concentration of the metal in the vicinity of the particle surface is higher than the average of the whole particles. For example, it is preferable that the concentration of the element other than cobalt in the surface portion measured by XPS or the like is higher than the concentration of the element in the average of the whole particles measured by ICP-MS or the like.

[0133] The particle surface can be said to be all crystal defects, and during charging, lithium is removed from the surface, so it is a portion where the lithium concentration is likely to be lower than that inside. Therefore, it is a portion that is likely to become unstable and whose crystal structure is likely to collapse. If the magnesium concentration in the surface portion is high, the change in the crystal structure can be suppressed more effectively. Also, when the magnesium concentration in the surface portion is high, it can be expected that the corrosion resistance against hydrofluoric acid generated by the decomposition of the electrolytic solution is improved.

[0134] Also, for halogens such as fluorine, it is preferable that the concentration in the surface portion of the positive electrode active material 200A according to one embodiment of the present invention is higher than the average of the whole particles. The presence of halogen in the surface portion, which is the region in contact with the electrolytic solution, can effectively improve the corrosion resistance against hydrofluoric acid.

[0135] Thus, it is preferable that the surface layer portion of the positive electrode active material 200A according to one embodiment of the present invention has a composition different from that of the interior, with a higher concentration of additives, such as magnesium and fluorine, than the interior. Further, it is preferable that the composition has a crystal structure that is stable at room temperature. Therefore, the surface layer portion may have a crystal structure different from that of the interior. For example, at least a part of the surface layer portion of the positive electrode active material 200A according to one embodiment of the present invention may have a rock salt-type crystal structure. Further, when the surface layer portion and the interior have different crystal structures, it is preferable that the crystal orientations of the surface layer portion and the interior are substantially the same.

[0136] The anions of the layered rock salt-type crystal and the rock salt-type crystal adopt a cubic close-packed structure (face-centered cubic lattice structure). It is also estimated that the anions of the O3'-type crystal adopt a cubic close-packed structure. When these are in contact, there is a crystal plane where the orientations of the cubic close-packed structures composed of anions are aligned. However, since the space groups of the layered rock salt-type crystal and the O3'-type crystal are R-3m, which are different from the space groups of the rock salt-type crystal, Fm-3m (the space group of a general rock salt-type crystal) and Fd-3m (the space group of the rock salt-type crystal having the simplest symmetry), the Miller indices of the crystal planes satisfying the above conditions are different between the layered rock salt-type crystal and the O3'-type crystal and the rock salt-type crystal. In this specification, in the case of a layered rock salt-type crystal, an O3'-type crystal, and a rock salt-type crystal, when the orientations of the cubic close-packed structures composed of anions are aligned, it may be said that the crystal orientations are substantially the same.

[0137] The fact that the crystal orientations of the two regions are substantially the same can be determined from TEM (transmission electron microscope) images, STEM (scanning transmission electron microscope) images, HAADF-STEM (high-angle annular dark-field scanning transmission electron microscope) images, ABF-STEM (annular bright-field scanning transmission electron microscope) images, etc. X-ray diffraction (XRD), electron beam diffraction, neutron beam diffraction, etc. can also be used as materials for determination. When the crystal orientations are substantially the same, it can be observed in a TEM image or the like that the difference in the direction of the rows in which cations and anions are alternately arranged linearly is 5 degrees or less, more preferably 2.5 degrees or less. In addition, in a TEM image or the like, light elements such as oxygen and fluorine may not be clearly observable. In that case, the coincidence of the orientation can be determined by the arrangement of metal elements.

[0138] However, if the surface layer is only composed of MgO or has only a structure in which MgO and CoO(II) are solid-soluted, the insertion and desorption of lithium become difficult. Therefore, the surface layer should have at least cobalt and also lithium in the discharged state, and it is necessary to have a path for the insertion and desorption of lithium. Also, it is preferable that the concentration of cobalt is higher than that of magnesium.

[0139] Also, the element X is preferably located in the surface layer of the particles of the positive electrode active material 200A according to one aspect of the present invention. For example, the positive electrode active material 200A according to one aspect of the present invention may be covered with a film having the element X.

[0140] <Analysis method> Whether a certain positive electrode active material is the positive electrode active material 200A according to one aspect of the present invention that exhibits an O3'-type crystal structure when charged at a high voltage can be determined by analyzing the positively charged electrode using XRD, electron beam diffraction, neutron beam diffraction, electron spin resonance (ESR), nuclear magnetic resonance (NMR), etc. In particular, XRD is preferable in that it can analyze the symmetry of transition metals such as cobalt possessed by the positive electrode active material with high resolution, can compare the crystallinity and crystal orientation, can analyze the lattice periodic strain and crystallite size, and sufficient accuracy can be obtained even by measuring the positive electrode obtained by disassembling the secondary battery as it is.

[0141] The positive electrode active material 200A according to one aspect of the present invention is characterized in that there is little change in the crystal structure between the charged state at a high voltage and the discharged state as described above. A material in which a crystal structure with a large change from the discharged state occupies 50 wt% or more in the charged state at a high voltage is not preferable because it cannot withstand charge and discharge at a high voltage. It should be noted that the desired crystal structure may not be obtained only by adding an additive element. For example, even though they are common in that they are lithium cobaltate having magnesium and fluorine, there are cases where the O3' type crystal structure becomes 60 wt% or more and the H1-3 type crystal structure occupies 50 wt% or more in the charged state at a high voltage. Also, at a predetermined voltage, the O3' type crystal structure may become almost 100 wt%, and when the predetermined voltage is further increased, the H1-3 type crystal structure may occur. Therefore, in order to determine whether it is the positive electrode active material 200A according to one aspect of the present invention, analysis of the crystal structure including XRD is necessary.

[0142] However, the positive electrode active material in the charged state or the discharged state at a high voltage may cause a change in the crystal structure when it comes into contact with the atmosphere. For example, it may change from the O3' type crystal structure to the H1-3 type crystal structure. Therefore, it is preferable to handle all samples in an inert atmosphere such as an argon atmosphere.

[0143] ≪XRD≫ The ideal powder XRD patterns by CuKα1 line calculated from the models of the O3' type crystal structure and the H1-3 type crystal structure are shown in FIGS. 7 and 9. Also, for comparison, LiCoO with a charge depth of 0 2 (O3) and the ideal XRD pattern calculated from the crystal structure of CoO with a charge depth of 1 2 (O1) are also shown. Incidentally, LiCoO 2 (O3) and CoO 2The pattern of (O1) was created using Reflex Powder Diffraction, which is one of the modules of Materials Studio (BIOVIA), from the crystal structure information obtained from the ICSD (Inorganic Crystal Structure Database) (see Non-Patent Document 5). The range of 2θ was set from 15° to 75°, Step size = 0.01, wavelength λ1 = 1.540562×10 -10 m, λ2 was not set, and the Monochromator was set to single. The pattern of the H1-3 type crystal structure was similarly created from the crystal structure information described in Non-Patent Document 3. The pattern of the crystal structure of the O3’ type crystal structure was estimated from the XRD pattern of the positive electrode active material of one aspect of the present invention, and was fitted using TOPAS ver.3 (crystal structure analysis software manufactured by Bruker), and the XRD pattern was created in the same manner as the others.

[0144] As shown in Fig. 7, in the O3’ type crystal structure, diffraction peaks appear at 2θ (degree) = 19.30 ± 0.20° (19.10° or more and 19.50° or less), and 2θ = 45.55 ± 0.10° (45.45° or more and 45.65° or less). More specifically, sharp diffraction peaks appear at 2θ = 19.30 ± 0.10° (19.20° or more and 19.40° or less), and 2θ = 45.55 ± 0.05° (45.50° or more and 45.60° or less). However, as shown in Fig. 9, in the H1-3 type crystal structure and CoO 2 (P-3m1, O1), no peaks appear at these positions. Therefore, it can be said that the appearance of peaks at 2θ (degree) = 19.30 ± 0.20°, and 2θ = 45.55 ± 0.10° in the state of being charged at a high voltage is a characteristic of the positive electrode active material 200A of one aspect of the present invention.

[0145] This can also mean that in the crystal structure at a charge depth of 0 and the crystal structure when charged at a high voltage, the positions where the XRD diffraction peaks appear are close. More specifically, it can be said that the difference in the positions where peaks appear is 2θ = 0.7 or less, more preferably 2θ = 0.5 or less, in two or more, more preferably three or more of the main diffraction peaks of both.

[0146] Note that the positive electrode active material 200A according to one embodiment of the present invention has an O3'-type crystal structure when charged at a high voltage, but not all of the particles need to have the O3'-type crystal structure. It may contain other crystal structures or a part thereof may be amorphous. However, when Rietveld analysis is performed on the XRD pattern, the O3'-type crystal structure is preferably 50 wt% or more, more preferably 60 wt% or more, and even more preferably 66 wt% or more. If the O3'-type crystal structure is 50 wt% or more, more preferably 60 wt% or more, and even more preferably 66 wt% or more, a positive electrode active material with excellent cycle characteristics can be obtained.

[0147] Also, even after 100 or more charge-discharge cycles from the start of measurement, when Rietveld analysis is performed, the O3'-type crystal structure is preferably 35 wt% or more, more preferably 40 wt% or more, and even more preferably 43 wt% or more.

[0148] Also, the crystallite size of the O3'-type crystal structure of the particles of the positive electrode active material only decreases to about 1 / 10 of that of LiCoO 2 (O3) in the discharged state. Therefore, even under the same XRD measurement conditions as the positive electrode before charge-discharge, a clear peak of the O3'-type crystal structure can be confirmed after high-voltage charging. On the other hand, in simple LiCoO 2 , even if a part has a structure similar to the O3'-type crystal structure, the crystallite size becomes small and the peak becomes broad and small. The crystallite size can be obtained from the half-value width of the XRD peak.

[0149] In the positive electrode active material according to one embodiment of the present invention, it is preferable that the influence of the Jahn-Teller effect is small. The positive electrode active material according to one embodiment of the present invention preferably has a layered rock salt-type crystal structure and mainly contains cobalt as a transition metal. Further, in the positive electrode active material according to one embodiment of the present invention, within a range where the influence of the Jahn-Teller effect is small, in addition to cobalt, it may have the metal Z described above.

[0150] In the positive electrode active material, the range of lattice constants where the influence of the Jahn-Teller effect is presumed to be small will be considered using XRD analysis.

[0151] Alternatively, in the layered rock salt-type crystal structure of the particles of the positive electrode active material in a state where charge and discharge are not performed or in a discharged state, when XRD analysis is performed, a first peak may be observed at 2θ of 18.50° or more and 19.30° or less, and a second peak may be observed at 2θ of 38.00° or more and 38.80° or less.

[0152] Note that the peaks appearing in the powder XRD pattern reflect the crystal structure inside the positive electrode active material 200A, which occupies most of the volume of the positive electrode active material 200A. The crystal structure of the surface layer portion and the like can be analyzed by electron beam diffraction or the like of the cross section of the positive electrode active material 200A.

[0153] In addition, the positive electrode active material is not limited to the above configuration, and even a positive electrode active material that does not use nickel and aluminum can obtain a remarkable effect by combining this positive electrode active material, an electrolytic solution, and an additive.

[0154] Regarding another example of the production of the positive electrode active material, it is shown below using the production flow shown in FIG. 5.

[0155] As shown in step S11 of FIG. 5, first, as materials for the mixture 902, lithium fluoride, which is a fluorine source, and magnesium fluoride, which is a magnesium source, are prepared. Lithium fluoride has a relatively low melting point of 848 °C and is preferable because it is easily melted in the annealing process described later. Lithium fluoride can be used as both a lithium source and a fluorine source. Magnesium fluoride can also be used as both a fluorine source and a magnesium source.

[0156] In FIG. 5, lithium fluoride LiF is prepared as a fluorine source and a lithium source, and magnesium fluoride MgF 2 is prepared (step S11 in FIG. 5). Lithium fluoride LiF and magnesium fluoride MgF 2The molar ratio of LiF:MgF 2 is preferably x:1 (0 ≦ x ≦ 1.9), more preferably LiF:MgF 2 = x:1 (0.1 ≦ x ≦ 0.5), and even more preferably LiF:MgF 2 = x:1 (x is around 0.33).

[0157] Also, when the following mixing and pulverizing steps are performed wet, a solvent is prepared. As the solvent, ketones such as acetone, alcohols such as ethanol and isopropanol, ether, dioxane, acetonitrile, N-methyl-2-pyrrolidone (NMP), etc. can be used. It is more preferable to use an aprotic solvent that hardly reacts with lithium. In this embodiment, acetone is used (see step S11 in FIG. 5).

[0158] Next, the materials of the above mixture 902 are mixed and pulverized (step S12 in FIG. 5). The mixing can be performed dry or wet, but wet is preferable because it can pulverize into smaller particles. For mixing, for example, a ball mill, a bead mill, etc. can be used. When using a ball mill, it is preferable to use zirconia balls as the media, for example. It is preferable to perform this mixing and pulverizing step sufficiently to pulverize the mixture 902 into fine powder.

[0159] The materials mixed and pulverized above are recovered (step S13 in FIG. 5) to obtain the mixture 902 (step S14 in FIG. 5).

[0160] Mixture 902 preferably has a D50 of 600 nm or more and 20 μm or less, more preferably 1 μm or more and 10 μm or less. When the thus micronized mixture 902 is mixed with a composite oxide containing lithium, a transition metal, and oxygen in a subsequent step, it is easy to uniformly adhere the mixture 902 to the surface of the composite oxide particles. When the mixture 902 is uniformly adhered to the surface of the composite oxide particles, it is preferable because it is easy to uniformly distribute halogen and magnesium in the surface layer portion of the composite oxide particles after heating. If there is a region in the surface layer portion that does not contain halogen and magnesium, there is a possibility that it is difficult to form the aforementioned O3'-type crystal structure in the charged state.

[0161] Next, as shown in step S25 of FIG. 5, a lithium source is prepared. As step S25, a composite oxide containing lithium, a transition metal, and oxygen, which has been synthesized in advance, is used.

[0162] For example, as the lithium cobaltate synthesized in advance, lithium cobaltate particles (trade name: Celsid C-10N) manufactured by Nippon Chemical Industry Co., Ltd. can be used. This has an average particle diameter (D50) of about 12 μm, and in impurity analysis by glow discharge mass spectrometry (GD-MS), the magnesium concentration and fluorine concentration are 50 ppm wt or less, the calcium concentration, aluminum concentration, and silicon concentration are 100 ppm wt or less, the nickel concentration is 150 ppm wt or less, the sulfur concentration is 500 ppm wt or less, the arsenic concentration is 1100 ppm wt or less, and the concentration of elements other than lithium, cobalt, and oxygen is 150 ppm wt or less. It is lithium cobaltate.

[0163] The composite oxide containing lithium, a transition metal, and oxygen in step S25 preferably has a layered rock salt-type crystal structure with few defects and strains. Therefore, it is preferably a composite oxide with few impurities. If the composite oxide containing lithium, a transition metal, and oxygen contains a large amount of impurities, there is a high possibility that it will have a crystal structure with many defects or strains.

[0164] Next, the mixture 902 is mixed with a composite oxide containing lithium, a transition metal, and oxygen (step S31 in FIG. 5). The ratio of the number of atoms TM of the transition metal in the composite oxide containing lithium, a transition metal, and oxygen to the number of atoms MgMix1 of magnesium in the mixture 902 is preferably TM:MgMix1 = 1:y (0.005 ≦ y ≦ 0.05), more preferably TM:MgMix1 = 1:y (0.007 ≦ y ≦ 0.04), and even more preferably about TM:MgMix1 = 1:0.02.

[0165] The mixing in step S31 is preferably carried out under milder conditions than the mixing in step S12 so as not to break the particles of the composite oxide. For example, it is preferable to use conditions with a lower rotation speed or a shorter time than the mixing in step S12. Also, it can be said that the dry condition is milder than the wet condition. For mixing, for example, a ball mill, a bead mill, etc. can be used. When using a ball mill, it is preferable to use zirconia balls as the media, for example.

[0166] The material mixed above is recovered (step S32 in FIG. 5) to obtain a mixture B (step S33 in FIG. 5).

[0167] Next, the mixture B is heated (step S34 in FIG. 5).

[0168] Annealing is preferably carried out at an appropriate temperature and time. The appropriate temperature and time vary depending on conditions such as the particle size and composition of the composite oxide containing lithium, a transition metal, and oxygen in step S25. When the particles are small, a lower temperature or a shorter time may be more preferable than when they are large.

[0169] For example, when the average particle diameter (D50) of the particles in step S25 is about 12 μm, the annealing temperature is preferably 600°C or higher and 950°C or lower, for example. The annealing time is preferably 3 hours or longer, more preferably 10 hours or longer, and even more preferably 60 hours or longer.

[0170] On the other hand, when the average particle diameter (D50) of the particles in step S25 is about 5 μm, the annealing temperature is preferably, for example, 600°C or higher and 950°C or lower. The annealing time is preferably, for example, 1 hour or longer and 10 hours or shorter, and more preferably about 2 hours.

[0171] The temperature drop time after annealing is preferably, for example, 10 hours or longer and 50 hours or shorter.

[0172] When the mixture B is annealed, first, the material with a low melting point in the mixture B (for example, lithium fluoride, melting point 848°C) is considered to melt and be distributed in the surface layer part of the composite oxide particles. Next, due to the presence of this melted material, the melting point of other materials drops, and it is presumed that other materials melt. For example, magnesium fluoride (melting point 1263°C) is considered to melt and be distributed in the surface layer part of the composite oxide particles.

[0173] The diffusion of the elements contained in this mixture B is faster in the surface layer part and near the grain boundaries than in the interior of the composite oxide particles. Therefore, magnesium and halogen become higher in concentration in the surface layer part and near the grain boundaries than in the interior. As will be described later, when the magnesium concentration in the surface layer part and near the grain boundaries is high, the change in the crystal structure can be more effectively suppressed.

[0174] The annealed material is recovered (step S35 in FIG. 5), and the positive electrode active material 200B is obtained (step S36 in FIG. 5).

[0175] The secondary battery using the thus obtained positive electrode active material 200B has excellent cycle characteristics.

[0176] This embodiment can be freely combined with Embodiment 1 or Embodiment 2.

[0177] (Embodiment 4) In this embodiment, examples that are partially different from Embodiment 1 or Embodiment 2 are shown.

[0178] In Embodiment 1, an example where the buffer layer is a collection of particles was shown, and in Embodiment 2, an example where the buffer layer is formed on the surface of the current collector particles was shown. In this embodiment, an example where the buffer layer is formed on the current collector particles is shown.

[0179] FIG. 10 shows a part of the structure of the secondary battery 600 of this embodiment.

[0180] The difference between FIG. 10 and FIG. 2 is that the buffer layer 74 is formed on the positive electrode current collector layer 73a. Also, the buffer layer 74 is formed on the negative electrode current collector layer 73b. By forming the buffer layer 74 in a film shape, the surface area can be enlarged, and since the contact area increases, it has the effect of contributing to reducing the internal resistance of the secondary battery.

[0181] As a method for forming the buffer layer 74, for example, a sputtering method, a chemical vapor deposition (CVD) method, a molecular beam epitaxy (MBE) method, a pulsed laser deposition (PLD) method, an atomic layer deposition (ALD) method, etc. can be used.

[0182] In FIG. 10, the configuration where the buffer layer 74 is formed so as to cover the positive electrode current collector layer 73a and the negative electrode current collector layer 73b is illustrated, but it is not limited thereto. For example, the buffer layer 74 may be formed so as to cover a part of the positive electrode current collector layer 73a or at least a part of the negative electrode current collector layer 73b.

[0183] Since the cross-sectional schematic diagram of the secondary battery 600 is the same as that of FIG. 1B, the description is omitted here. Note that the same reference numerals are used for the parts common to FIG. 1B for explanation. An enlarged view of the dotted line portion of FIG. 1B corresponds to FIG. 10.

[0184] Also, this embodiment can be freely combined with Embodiment 1.

[0185] (Embodiment 5) In this embodiment, an application example of a secondary battery according to one aspect of the present invention will be described.

[0186] The secondary battery according to one aspect of the present invention can be applied, for example, as a power source or an auxiliary power source for various electronic devices (e.g., information terminals, computers, smartphones, e-book terminals, digital still cameras, video cameras, recording and playback devices, navigation systems, game machines, etc.). It can also be used for image sensors, IoT (Internet of Things) terminal devices, healthcare, etc. Here, the computer includes not only tablet-type computers, notebook-type computers, and desktop-type computers, but also large-scale computers such as server systems.

[0187] An example of an electronic device having a secondary battery according to one aspect of the present invention will be described. FIGS. 12A to 12I illustrate a state in which an electronic component 4700 for mounting the secondary battery is included in each electronic device. The secondary battery according to one aspect of the present invention has a high discharge capacity, high cycle characteristics, and high safety. Therefore, it can be suitably used for the following electronic devices. In particular, it can be suitably used for electronic devices that require durability.

[0188] [Mobile phone] The information terminal 5500 shown in FIG. 12A is a mobile phone (smartphone), which is a type of portable information terminal. The information terminal 5500 has a housing 5510 and a display unit 5511. As an input interface, a touch panel is provided on the display unit 5511, and buttons are provided on the housing 5510.

[0189] [Wearable terminal] Further, FIG. 12B shows an information terminal 5900, which is an example of a wearable terminal. The information terminal 5900 has a housing 5901, a display unit 5902, operation switches 5903, 5904, a band 5905, etc.

[0190] [Information terminal] In addition, FIG. 12C shows a desktop information terminal 5300. The desktop information terminal 5300 includes a main body 5301 of the information terminal, a display unit 5302, and a keyboard 5303.

[0191] In the above description, smartphones, wearable terminals, and desktop information terminals are illustrated in FIGS. 12A to 12C as examples of electronic devices, but information terminals other than smartphones, wearable terminals, and desktop information terminals can also be applied. Examples of information terminals other than smartphones, wearable terminals, and desktop information terminals include, for example, PDAs (Personal Digital Assistants), notebook information terminals, workstations, and the like.

[0192] [Household Appliance] In addition, FIG. 12D shows an electric refrigerator-freezer 5800 as an example of a household appliance. The electric refrigerator-freezer 5800 includes a housing 5801, a refrigerator door 5802, a freezer door 5803, and the like. For example, the electric refrigerator-freezer 5800 is an electric refrigerator-freezer compatible with IoT (Internet of Things).

[0193] A secondary battery according to one aspect of the present invention can be applied to the auxiliary power supply of the electric refrigerator-freezer 5800. The electric refrigerator-freezer 5800 can transmit and receive information such as the food stored in the electric refrigerator-freezer 5800 and the expiration date of the food to and from an information terminal through the Internet or the like. By applying a secondary battery according to one aspect of the present invention to the auxiliary power supply, the internal temperature and the like can be maintained during a power outage or the like.

[0194] In the present embodiment, an electric refrigerator-freezer is described as a household appliance. Other household appliances include, for example, vacuum cleaners, microwave ovens, electric ovens, rice cookers, water heaters, IH cookers, water servers, air conditioners and other heating and cooling appliances, washing machines, dryers, audio-visual equipment, and the like.

[0195] [Game Machine] In addition, FIG. 12E shows a portable game machine 5200, which is an example of a game machine. The portable game machine 5200 includes a housing 5201, a display unit 5202, buttons 5203, and the like.

[0196] Furthermore, FIG. 12F shows a stationary game machine 7500, which is an example of a game machine. The stationary game machine 7500 includes a main body 7520 and a controller 7522. Note that the controller 7522 can be connected to the main body 7520 wirelessly or by wire. Although not shown in FIG. 12F, the controller 7522 can include a display unit for displaying game images, a touch panel, a stick, a rotary knob, a slide knob, and the like, which serve as input interfaces other than buttons. In addition, the controller 7522 is not limited to the shape shown in FIG. 12F, and the shape of the controller 7522 can be variously changed according to the genre of the game. For example, in a shooting game such as FPS (First Person Shooter), a controller in the shape of a gun with a trigger as a button can be used. Also, for example, in a music game or the like, a controller in the shape of a musical instrument or a music device can be used. Furthermore, the stationary game machine may be configured to be operated by the gestures and / or voice of the game player, instead of using a controller, and may be equipped with a camera, a depth sensor, a microphone, and the like.

[0197] In addition, the video of the game machine described above can be output by a display device such as a television set, a personal computer display, a game display, or a head-mounted display.

[0198] FIG. 12E shows a portable game machine as an example of a game machine. FIG. 12F shows a home stationary game machine. Note that the electronic device according to one aspect of the present invention is not limited thereto. Examples of the electronic device according to one aspect of the present invention include an arcade game machine installed in an entertainment facility (such as a game center or an amusement park), a pitching machine for batting practice installed in a sports facility, and the like.

[0199] [Moving body] The secondary battery described in the above embodiment can be applied to an automobile which is a moving body and the periphery of the driver's seat of the automobile.

[0200] An automobile 5700 which is an example of a moving body is illustrated in FIG. 12G.

[0201] Around the driver's seat of the automobile 5700, an instrument panel is provided which provides various information by displaying a speedometer, a tachometer, a travel distance, a fuel gauge, a gear state, an air conditioner setting, etc. Also, a display device for indicating those information may be provided around the driver's seat. By using a part of the secondary battery according to one aspect of the present invention for the automobile 5700, the automobile 5700 can be made into a highly reliable automobile.

[0202] In particular, the display device can supplement a field of view blocked by a pillar or a blind spot of the driver's seat by projecting an image from an imaging device (not shown) provided in the automobile 5700, and can enhance safety. That is, by displaying an image from an imaging device provided outside the automobile 5700, a blind spot can be supplemented and safety can be enhanced.

[0203] In the above description, an automobile is described as an example of a moving body, but the moving body is not limited to vehicles such as automobiles. For example, examples of the moving body include trains, monorails, ships, flying bodies (helicopters, unmanned aerial vehicles (drones), airplanes, rockets), etc.

[0204] [Camera] The secondary battery described in the above embodiment can be applied to a camera.

[0205] FIG. 12H shows a digital camera 6240 which is an example of an imaging device. The digital camera 6240 includes a housing 6241, a display unit 6242, an operation switch 6243, a shutter button 6244, etc., and a detachable lens 6246 is attached to the digital camera 6240. Here, the digital camera 6240 is configured such that the lens 6246 can be removed from the housing 6241 and replaced, but the lens 6246 and the housing 6241 may be integrated. Also, the digital camera 6240 may be configured such that a strobe device, a viewfinder, etc. can be separately attached.

[0206] [Video camera] The secondary battery described in the above embodiment can be applied to a video camera.

[0207] FIG. 12I shows a video camera 6300 which is an example of an imaging device. The video camera 6300 includes a first housing 6301, a second housing 6302, a display unit 6303, an operation switch 6304, a lens 6305, a connection part 6306, etc. The operation switch 6304 and the lens 6305 are provided on the first housing 6301, and the display unit 6303 is provided on the second housing 6302. The first housing 6301 and the second housing 6302 are connected by the connection part 6306, and the angle between the first housing 6301 and the second housing 6302 can be changed by the connection part 6306. The video on the display unit 6303 may be switched according to the angle between the first housing 6301 and the second housing 6302 at the connection part 6306.

[0208] [ICD] The secondary battery described in the above embodiment can be applied to an implantable cardioverter defibrillator (ICD).

[0209] FIG. 12J is a schematic cross-sectional view showing an example of an ICD. The ICD main body 5400 includes at least a secondary battery 5401, a regulator, a control circuit, an antenna 5404, a wire 5402 to the right atrium, and a wire 5403 to the right ventricle.

[0210] The ICD body 5400 is implanted into the body through surgery, and the two wires are passed through the subclavian vein 5405 and the superior vena cava 5406 of the human body so that one wire tip is placed in the right ventricle and the other wire tip is placed in the right atrium.

[0211] The ICD body 5400 has the function of a pacemaker and paces the heart when the heart rate is outside the specified range. Also, when the heart rate is not improved by pacing (such as rapid ventricular tachycardia or ventricular fibrillation), treatment by electric shock is performed.

[0212] The ICD body 5400 needs to constantly monitor the heart rate in order to perform pacing and electric shock appropriately. Therefore, the ICD body 5400 has a sensor for detecting the heart rate. Also, the ICD body 5400 can store data on the heart rate obtained by the sensor and the like, the number of times and the time of treatment by pacing, etc. in the electronic component 4700.

[0213] Also, power can be received by the antenna 5404, and the power is charged to the secondary battery 5401. Also, since the ICD body 5400 has a plurality of secondary batteries, the safety can be improved. Specifically, even if some of the secondary batteries of the ICD body 5400 become unusable, the remaining secondary batteries can function, so it also functions as an auxiliary power source.

[0214] Also, separately from the antenna 5404 that can receive power, it may have an antenna that can transmit physiological signals. For example, a system for monitoring heart activities such that physiological signals such as pulse, respiratory rate, heart rate, body temperature, etc. can be confirmed by an external monitoring device may be configured.

[0215] The signal processing board 6621 shown in FIG. 11 is an example of a board corresponding to the electronic component 4700 shown in FIGS. 12A to 12I. The board substrate 6620 can also be said to be a wiring board or a circuit board including a ceramic material called a green sheet.

[0216] The signal processing board 6621 has a connection terminal 6623, a connection terminal 6624, a connection terminal 6625, a semiconductor device 6626, a secondary battery 6627, a semiconductor device 6628, and a connection terminal 6622.

[0217] The semiconductor device 6626 has terminals (not shown) for inputting and outputting signals and is electrically connected to the secondary battery 6627. The semiconductor device 6626 also functions as a charge / discharge control circuit for the secondary battery 6627, a protection circuit for the secondary battery 6627, and a power supply circuit for supplying power and signals from the secondary battery 6627 to other elements. In FIG. 11, two secondary batteries 6627 are shown, but one or three or more may be used, and there is no particular limitation.

[0218] The connection terminal 6622 has a shape into which the connector of the FPC 6629 can be inserted and functions as an interface for connecting to another board or a display module.

[0219] The connection terminals 6623, 6624, and 6625 can be used as interfaces for, for example, supplying power to and inputting signals to the signal processing board 6621. Also, for example, they can be used as interfaces for outputting signals calculated by the signal processing board 6621. Examples of the specifications of each of the connection terminals 6623, 6624, and 6625 include USB (Universal Serial Bus), SATA (Serial ATA), and SCSI (Small Computer System Interface). Also, when outputting video signals from the connection terminals 6623, 6624, and 6625, examples of the specifications include HDMI (registered trademark).

[0220] The semiconductor device 6628 has a plurality of terminals, and the wiring provided on the board substrate 6620 for the terminals can be electrically connected to the wiring of the board substrate 6620 by, for example, performing reflow soldering. Examples of the semiconductor device 6628 include an FPGA (Field Programmable Gate Array), a GPU, a CPU, and the like.

[0221] By mounting the secondary battery according to one aspect of the present invention on a board substrate of each of the above various electronic devices, it is possible to reduce the size, increase the speed, or reduce the power consumption of the electronic device. In addition, since the secondary battery according to one aspect of the present invention has little deterioration, an electronic device with stable operation can be realized. Therefore, the reliability of the electronic device can be improved.

[0222] This embodiment can be freely combined with other embodiments.

Description of Reference Numerals

[0223] 50a: Positive electrode active material layer, 50b: Solid electrolyte layer, 50c: Negative electrode active material layer, 70a: Package member, 70b: Package member, 70c: Package member, 71: External electrode, 72: External electrode, 73a: Positive electrode current collector layer, 73b: Negative electrode current collector layer, 74: Buffer layer, 101: Positive electrode active material layer, 200A: Positive electrode active material, 200B: Positive electrode active material, 400: Secondary battery, 410: Negative electrode, 411: Negative electrode active material, 420: Solid electrolyte layer, 421: Solid electrolyte, 430: Positive electrode, 431: Positive electrode active material, 500: Secondary battery, 600: Secondary battery, 901: Mixture, 902: Mixture, 903: Mixture, 4700: Electronic component, 5200: Portable game machine, 5201: Housing, 5202: Display unit, 5203: Button, 5300: Desktop information terminal, 5301: Main body, 5302: Display unit, 5303: Keyboard, 5400: ICD main body, 5401: Secondary battery, 5402: Wire, 5403: Wire, 5404: Antenna, 5405: Subclavian vein, 5406: Superior vena cava, 5500: Information terminal, 5510: Housing, 5511: Display unit, 5700: Automobile, 5800: Electric refrigerator-freezer, 5801: Housing, 5802: Refrigerator door, 5803: Freezer door, 5900: Information terminal, 5901: Housing, 5902: Display unit, 5903: Operation switch, 5904: Operation switch, 5905: Band, 6240: Digital camera, 6241: Housing, 6242: Display unit, 6243: Operation switch, 6244: Shutter button, 6246: Lens, 6300: Video camera, 6301: Housing, 6302: Housing, 6303: Display unit, 6304: Operation switch, 6305: Lens, 6306: Connection part, 6620: Board substrate, 6621: Signal processing board, 6622: Connection terminal, 6623: Connection terminal, 6624: Connection terminal, 6625: Connection terminal, 6626: Semiconductor device, 6627: Secondary battery, 6628: Semiconductor device, 6629: FPC, 7500: Console game machine, 7520: Main body, 7522: Controller

Claims

1. a laminate including a positive electrode current collector layer, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector layer, the positive electrode current collector layer comprises aluminum, the negative electrode current collector layer comprises copper, a buffer layer is provided between the positive electrode current collector layer and the positive electrode active material layer, and between the positive electrode current collector layer and the positive electrode active material layer, The buffer layer is made of titanium oxynitride (TiO ｘ N ｙ , O<x<2, O<y<l).

2. a laminate including a positive electrode current collector layer, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector layer, the positive electrode current collector layer comprises aluminum, the negative electrode current collector layer comprises copper, a buffer layer is provided between the positive electrode current collector layer and the positive electrode active material layer, and between the positive electrode current collector layer and the positive electrode active material layer, The buffer layer comprises titanium nitride.

3. a laminate including a positive electrode current collector layer which is an aggregate of first metal particles, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector layer which is an aggregate of second metal particles; the first metal particles are aluminum particles; the second metal particles are copper particles; The surfaces of the first metal particles and the surfaces of the second metal particles are made of titanium oxynitride (TiO ｘ N ｙ , O<x<2, O<y<l) is formed.

4. a laminate including a positive electrode current collector layer which is an aggregate of first metal particles, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector layer which is an aggregate of second metal particles; the first metal particles are aluminum particles; the second metal particles are copper particles; A secondary battery, wherein titanium nitride is formed on the surfaces of the first metal particles and the surfaces of the second metal particles.

5. In any one of claims 1 to 4, The positive electrode active material layer comprises lithium cobalt oxide, magnesium, fluorine, and aluminum.

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