Secondary batteries

Abstract

To provide a positive electrode of a secondary battery, excellent in cycle characteristic.SOLUTION: A positive electrode for a secondary battery, includes: a positive electrode collector layer; an underground film; a positive electrode active material layer; and a cap layer. The underground film includes a titanium nitride, the positive electrode collector layer includes a lithium cobaltate, and the cap layer includes a titanium oxide. By adopting the titanium nitride to the underground film, a sufficient conductivity is secured, and an oxide of the positive electrode collector layer and a diffusion of a metal atom can be suppressed. Also, by adapting titanium oxide to the cap layer, a side reaction of the positive electrode collector layer with an electrolyte and breaking of a crystal structure of a positive electrode material are suppressed, and thus, a cycle characteristic can be improved.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] One embodiment of the present invention relates to an object, a method, or a manufacturing method. Alternatively, the present invention relates to a process, a machine, a manufacture, or a composition of matter. One embodiment of the present invention relates to a semiconductor device, a display device, a light-emitting device, a power storage device, a lighting device, an electronic device, or a manufacturing method thereof.

[0002] In this specification, the term "electronic device" refers to any device having a power storage device, and includes electro-optical devices having a power storage device, information terminal devices having a power storage device, and the like. [Background technology]

[0003] In recent years, there has been active development of various types of energy storage devices, such as lithium-ion secondary batteries, lithium-ion capacitors, air batteries, and all-solid-state batteries. Demand for high-power, high-capacity lithium-ion secondary batteries has expanded rapidly in line with the development of the semiconductor industry, and they have become indispensable in today's information society as a rechargeable energy source.

[0004] In addition, as demand expands, there is a demand for higher performance lithium-ion secondary batteries, and therefore, progress has been made in improving the positive electrode active materials of lithium-ion secondary batteries in order to increase their capacity and improve their cycle characteristics (for example, Patent Document 1).

[0005] Furthermore, among lithium-ion secondary batteries, development of all-solid-state batteries, which are safer, is underway. Thin-film secondary batteries, in which the positive electrode, electrolyte, and negative electrode are formed by PVD (physical vapor deposition), CVD (chemical vapor deposition), or the like, are also a type of all-solid-state battery (for example, Patent Document 2). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2018-206747 [Patent Document 2] US Patent Application Publication No. 2010 / 0190051 [Non-patent literature]

[0007] [Non-Patent Document 1] EELS analysis of cation valence states and oxygen vacancies in magnetic oxides, ZLWang, JSYin, YDJiang, Micron 31(2000)571-580 Summary of the Invention [Problem to be solved by the invention]

[0008] Thin-film secondary batteries have room for improvement in various aspects, such as charge / discharge characteristics, cycle characteristics, reliability, safety, and cost. For example, with regard to cycle characteristics, repeated charge / discharge cycles can cause the crystal structure of the positive electrode active material to collapse, potentially leading to a decrease in charge / discharge capacity. Furthermore, side reactions can occur at the interface between the positive electrode active material and the electrolyte, or the interface between the positive electrode active material and the positive electrode current collector, potentially leading to a decrease in charge / discharge capacity.

[0009] In view of the above, an object of one embodiment of the present invention is to provide a positive electrode for a secondary battery in which side reactions are unlikely to occur at an interface between a positive electrode active material and an electrolyte, an interface between a positive electrode active material and a positive electrode current collector, or the like, even after repeated charge and discharge. Another object is to provide a positive electrode for a secondary battery in which a crystal structure is unlikely to be destroyed even after repeated charge and discharge. Another object is to provide a positive electrode for a secondary battery with excellent charge and discharge cycle characteristics. Another object is to provide a positive electrode for a secondary battery with a large charge and discharge capacity. Another object is to provide a positive electrode for a secondary battery in which a decrease in capacity during charge and discharge cycles is suppressed. Another object is to provide a secondary battery with excellent charge and discharge cycle characteristics. Another object is to provide a secondary battery with a large charge and discharge capacity. Another object is to provide a secondary battery with high safety or reliability.

[0010] Another object of one embodiment of the present invention is to provide a novel substance, active material particles, a power storage device, or a manufacturing method thereof.

[0011] Note that the description of these problems does not preclude the existence of other problems. Note that one embodiment of the present invention does not necessarily solve all of these problems. Note that problems other than these can be extracted from the description in the specification, drawings, and claims. [Means for solving the problem]

[0012] In one embodiment of the present invention, a cap layer is provided on the positive electrode active material layer in order to make the crystal structure less likely to collapse or to suppress side reactions and improve cycle characteristics.

[0013] One aspect of the present invention is a positive electrode for a secondary battery, the positive electrode having an underlayer, a positive electrode active material layer, and a cap layer, wherein at least one of the underlayer and the cap layer contains titanium oxynitride, the positive electrode active material layer contains lithium cobalt oxide, and the cap layer contains a titanium compound containing oxygen.

[0014] Alternatively, in the above, it is preferable that the crystal structure of the undercoat film and the crystal structure of the positive electrode active material layer each have a plane in which only anions are arranged.

[0015] In the above, it is preferable that both the undercoat film and the positive electrode active material layer have a crystal structure in which cations and anions are arranged alternately.

[0016] Another embodiment of the present invention is a secondary battery including the above-described positive electrode for secondary batteries, a solid electrolyte, and a negative electrode.

[0017] Another embodiment of the present invention is an electronic device including the above secondary battery.

[0018] Another embodiment of the present invention is an electronic device including the above secondary battery and a lithium ion secondary battery including a positive electrode, a negative electrode, an electrolyte, and a separator. [Effects of the Invention]

[0019] According to one embodiment of the present invention, a positive electrode for a secondary battery can be provided that is less likely to cause side reactions 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, and the like, even after repeated charge and discharge. A positive electrode for a secondary battery that is less likely to lose its crystal structure even after repeated charge and discharge can be provided. A positive electrode for a secondary battery with excellent charge and discharge cycle characteristics can be provided. A positive electrode for a secondary battery with a large charge and discharge capacity can be provided. A positive electrode for a secondary battery in which a decrease in capacity during charge and discharge cycles is suppressed can be provided. A secondary battery with excellent charge and discharge cycle characteristics can be provided. A secondary battery with a large charge and discharge capacity can be provided. A secondary battery with high safety or reliability can be provided.

[0020] According to one embodiment of the present invention, a novel substance, active material particles, a power storage device, or a manufacturing method thereof can be provided.

[0021] Note that the description of these effects does not preclude the existence of other effects. Note that one embodiment of the present invention does not necessarily have all of these effects. Note that effects other than these will become apparent from the description in the specification, drawings, claims, etc., and it is possible to extract other effects from the description in the specification, drawings, claims, etc. [Brief explanation of the drawings]

[0022] [Figure 1] 1A to 1C are perspective views of a positive electrode according to one embodiment of the present invention. [Figure 2] 2A and 2B illustrate a crystal structure of a positive electrode of one embodiment of the present invention. [Figure 3] 3A to 3C illustrate a stacked structure of a secondary battery of one embodiment of the present invention. [Figure 4] FIG. 4A is a top view illustrating one embodiment of the present invention, and FIGS. 4B to 4D are cross-sectional views illustrating one embodiment of the present invention. [Figure 5] 5A and 5C are top views showing one embodiment of the present invention, and FIGS. 5B and 5D are cross-sectional views showing one embodiment of the present invention. [Figure 6] FIG. 6A is a top view illustrating one embodiment of the present invention, and FIG. 6B is a cross-sectional view illustrating one embodiment of the present invention. [Figure 7] FIG. 7A is a top view illustrating one embodiment of the present invention, and FIG. 7B is a cross-sectional view illustrating one embodiment of the present invention. [Figure 8] FIG. 8 illustrates a manufacturing flow of a secondary battery according to one embodiment of the present invention. [Figure 9] 9A and 9B are top views illustrating one embodiment of the present invention. [Figure 10] FIG. 10 is a cross-sectional view showing one embodiment of the present invention. [Figure 11] FIG. 11 illustrates a manufacturing flow of a secondary battery of one embodiment of the present invention. [Figure 12] FIG. 12 is a schematic top view of a secondary battery manufacturing apparatus. [Figure 13] FIG. 13 is a cross-sectional view of a part of a secondary battery manufacturing apparatus. [Figure 14] Fig. 14A is a perspective view showing an example of a battery cell, Fig. 14B is a perspective view of a circuit, and Fig. 14C is a perspective view of the battery cell and the circuit stacked on top of each other. [Figure 15] Fig. 15A is a perspective view showing an example of a battery cell, Fig. 15B is a perspective view of a circuit, and Figs. 15C and 15D are perspective views of the battery cell and the circuit superimposed on each other. [Figure 16] Fig. 16A is a perspective view of a battery cell, and Fig. 16B is a diagram showing an example of an electronic device. [Figure 17] 17A to 17C are diagrams showing examples of electronic devices. [Figure 18] 18A to 18C are diagrams showing examples of electronic devices. [Figure 19]19A to 19D are diagrams showing examples of electronic devices. [Figure 20] Fig. 20A is a diagram showing a part of a system according to an embodiment of the present invention, and Fig. 20B is a diagram showing an example of an electronic device according to an embodiment of the present invention. [Figure 21] Fig. 21A is a schematic diagram of an electronic device according to one embodiment of the present invention, Fig. 21B is a diagram showing a part of the system, and Fig. 21C is an example of a perspective view of a portable data terminal used in the system. [Figure 22] 22A and 22B are graphs showing the charge and discharge characteristics of the secondary battery according to Example 1. FIG. [Figure 23] 23A and 23B are graphs showing the cycle characteristics of the secondary battery according to Example 1. FIG. [Figure 24] FIG. 24 is a cross-sectional TEM image of the positive electrode according to Example 2. [Figure 25] 25A is a cross-sectional TEM image of the positive electrode active material layer according to Example 2. FIG. 25B is a micro-electron diffraction image of the positive electrode active material layer according to Example 2. [Figure 26] 26A and 26B are micro-electron beam diffraction images of the positive electrode active material layer according to Example 2. FIG. [Figure 27] FIG. 27 is a cross-sectional TEM image of the positive electrode according to Example 2. [Figure 28] 28A and 28B are cross-sectional TEM images of the positive electrode according to Example 2. FIG. [Figure 29] FIG. 29 shows the EELS spectrum of the positive electrode active material layer according to Example 2. [Figure 30] FIG. 30 is a cross-sectional TEM image of the positive electrode according to Example 2. [Figure 31] 31A and 31B are cross-sectional TEM images of the positive electrode according to Example 2. FIG. [Figure 32] FIG. 32 shows the EELS spectrum of the positive electrode active material layer according to Example 2. [Figure 33] 33A is a cross-sectional TEM image of the positive electrode active material layer according to Example 2. FIG. 33B is a micro-electron diffraction image of the positive electrode active material layer according to Example 2. [Figure 34]34A and 34B are micro-electron beam diffraction images of the positive electrode active material layer according to Example 2. FIG. [Figure 35] 35A is a cross-sectional TEM image of the positive electrode active material layer according to Example 2. FIG. 35B is a micro-electron diffraction image of the positive electrode active material layer according to Example 2. [Figure 36] 36A and 36B are micro-electron beam diffraction images of the positive electrode active material layer according to Example 2. FIG. [Figure 37] FIG. 37 is a graph showing the charge-discharge cycle characteristics of the secondary battery according to Example 2. [Figure 38] 38A and 38B are diagrams illustrating the impedance measurement of the secondary battery according to Example 2. In FIG. [Figure 39] FIG. 39 shows the impedance measurement results of the secondary battery according to Example 2. [Figure 40] FIG. 40 shows the impedance measurement results of the secondary battery according to Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0023] 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 it will be readily understood by those skilled in the art that various modifications can be made to the embodiments and details. Furthermore, the present invention should not be interpreted as being limited to the description of the embodiments shown below.

[0024] Furthermore, in this specification and elsewhere, Miller indices are used to denote crystal planes and directions. Individual planes indicating crystal planes are represented in ( ). Orientations are represented in [ ]. Similar indices are used for reciprocal lattice points, but no parentheses are used. In crystallography, crystal planes, directions, and space groups are represented by placing a superscript bar above the numbers, but in this specification and elsewhere, due to limitations on application notation, numbers may be represented by placing a - (minus sign) before them instead of placing a bar above them.

[0025] In this specification, the layered rock-salt type crystal structure of a composite oxide containing lithium and a transition metal refers to a crystal structure having a rock-salt type ion arrangement in which cations and anions are alternately arranged, and in which the transition metal and lithium are regularly arranged to form a two-dimensional plane, allowing two-dimensional diffusion of lithium. Defects such as cation or anion deficiencies may also be present. Furthermore, strictly speaking, the layered rock-salt type crystal structure may have a distorted rock-salt type crystal lattice structure.

[0026] In this specification and the like, the rock salt type crystal structure refers to a structure in which cations and anions are arranged alternately, and it is also possible for there to be a deficiency of cations or anions.

[0027] Layered rock salt-type crystals and the anions of rock salt-type crystals have a cubic close-packed structure (face-centered cubic lattice structure). When they contact, there is a crystal plane where the cubic close-packed structures formed by the anions coincide. However, since the space group of layered rock salt-type crystals is R-3m, which is different from the rock salt-type space group Fm-3m, the Miller indices of the crystal planes that satisfy the above conditions are different between layered rock salt-type crystals and rock salt-type crystals. In this specification, when the cubic close-packed structures formed by the anions coincide in layered rock salt-type crystals and rock salt-type crystals, it may be said that the crystal orientations are approximately the same.

[0028] The general alignment of the crystal orientations of the two regions can be determined from TEM (transmission electron microscope), STEM (scanning transmission electron microscope), HAADF-STEM (high-angle annular dark-field scanning transmission electron microscope), and ABF-STEM (annular bright-field scanning transmission electron microscope) images. X-ray diffraction (XRD), electron diffraction, and neutron diffraction can also be used for this determination. If the crystal orientations are generally aligned, the difference in the orientation of the alternating linear array of cations and anions can be observed in TEM images, etc., to be less than 5 degrees or less than 2.5 degrees. Light elements such as oxygen and fluorine may not be clearly visible in TEM images, but in such cases, the alignment of the orientations can be determined from the arrangement of metal elements.

[0029] In this specification, the theoretical capacity of a positive electrode active material refers to the amount of electricity when all of the intercalable lithium contained in the positive electrode active material is deintercalated. For example, the theoretical capacity of LiCoO2 is 274 mAh / g, the theoretical capacity of LiNiO2 is 274 mAh / g, and the theoretical capacity of LiMn2O4 is 148 mAh / g.

[0030] In this specification and the like, the depth of charge when all intercalable and deintercalable lithium is intercalated is defined as 0, and the depth of charge when all intercalable and deintercalable lithium contained in the positive electrode active material is deintercalated is defined as 1.

[0031] In this specification, the term "surfaces are parallel" does not only mean that they are mathematically strictly parallel, but also means that the angle between the surfaces is 5° or less, or 2.5° or less.

[0032] (Embodiment 1) A positive electrode for a secondary battery according to one embodiment of the present invention will be described with reference to FIG.

[0033] 1A is a perspective view of an example of a positive electrode 100 according to one embodiment of the present invention. The positive electrode 100 includes a positive electrode current collector 103, a base film 104, a positive electrode active material layer 101, and a cap layer .

[0034] The base film 104 is provided between the positive electrode current collector 103 and the positive electrode active material layer 101. The base film 104 has a function of increasing the conductivity between the positive electrode current collector 103 and the positive electrode active material layer 101. Alternatively, the base film 104 has a function of suppressing side reactions such as oxidation of the positive electrode current collector 103 by oxygen contained in the positive electrode active material layer 101 or the like, or diffusion of metal atoms contained in the positive electrode current collector 103 into the positive electrode active material layer 101. Alternatively, the base film 104 has a function of stabilizing the crystal structure of the positive electrode active material layer 101.

[0035] It is preferable to use a material having electrical conductivity for the underlayer 104. It is also preferable to use a material that is easily inhibited from oxidation. For example, titanium compounds such as titanium oxide, titanium nitride, titanium oxide partially substituted with nitrogen, titanium nitride partially substituted with oxygen, or titanium oxynitride (TiO x Ny For example, conditions such as 0 < x < 2 and 0 < y < 1 can be applied. Among them, titanium nitride is particularly preferred because it has high conductivity and a high function of suppressing oxidation.

[0036] The cap layer 102 is provided on the positive electrode active material layer 101. The cap layer 102 has a function of suppressing the side reaction between the positive electrode active material layer 101 and the electrolyte. Or it has a function of stabilizing the crystal structure of the positive electrode active material layer 101.

[0037] It is preferable to use a titanium compound as the cap layer 102. For example, titanium oxide, titanium nitride, titanium oxide partially substituted with nitrogen, titanium nitride partially substituted with oxygen, or titanium oxynitride (TiO x N y It is preferable to have, where 0 < x < 2 and 0 < y < 1). Titanium and oxygen are materials that can be contained in the solid electrolyte. Therefore, titanium oxide is particularly suitable as the cap layer 102.

[0038] In this specification and the like, the electrolyte shall include not only the solid electrolyte, but also an electrolytic solution in which a lithium salt is dissolved in a liquid solvent and an electrolytic solution in which a lithium salt is dissolved in a gel-like compound.

[0039] The positive electrode active material layer 101 has lithium, transition metal M, and oxygen. It can also be said that the positive electrode active material layer 101 has a composite oxide containing lithium and transition metal M.

[0040] The transition metal M contained in the positive electrode active material layer 101 is preferably a metal capable of forming a layered rock-salt composite oxide belonging to the space group R-3m with lithium. For example, one or more of manganese, cobalt, and nickel can be used as the transition metal M. That is, the positive electrode active material layer 101 may contain only cobalt, only nickel, a combination of cobalt and manganese, or a combination of cobalt and nickel, or three of cobalt, manganese, and nickel. That is, the positive electrode active material layer 101 may contain a composite oxide containing lithium and the transition metal M, such as lithium cobalt oxide, lithium nickel oxide, lithium cobalt oxide in which some of the cobalt is substituted with manganese, lithium cobalt oxide in which some of the cobalt is substituted with nickel, or nickel-manganese-lithium cobalt oxide.

[0041] Furthermore, the positive electrode active material layer 101 may contain elements other than the transition metal M, such as magnesium, fluorine, and aluminum, in addition to the above. These elements may further stabilize the crystal structure of the positive electrode active material layer 101. That is, the positive electrode active material layer 101 may contain lithium cobalt oxide to which magnesium and fluorine have been added, lithium nickel-cobalt oxide to which magnesium and fluorine have been added, lithium cobalt-aluminate to which magnesium and fluorine have been added, nickel-cobalt-lithium aluminum oxide, nickel-cobalt-lithium aluminum oxide, or nickel-cobalt-lithium aluminum oxide to which magnesium and fluorine have been added.

[0042] When the positive electrode active material layer 101 contains lithium, cobalt, nickel, aluminum, magnesium, oxygen, and fluorine, the atomic ratio of nickel is preferably, for example, 0.05 to 2, more preferably 0.1 to 1.5, and even more preferably 0.1 to 0.9, relative to the atomic ratio of cobalt contained in the positive electrode active material layer 101 taken as 100. The atomic ratio of aluminum is preferably, for example, 0.05 to 2, more preferably 0.1 to 1.5, and even more preferably 0.1 to 0.9, relative to the atomic ratio of cobalt contained in the positive electrode active material layer 101 taken as 100. The atomic ratio of magnesium is preferably, for example, 0.1 to 6, more preferably 0.3 to 3. Furthermore, when the atomic ratio of magnesium contained in the positive electrode active material layer 101 is taken as 1, the atomic ratio of fluorine is preferably, for example, 2 to 3.9.

[0043] By containing nickel, aluminum, and magnesium at the above concentrations, a stable crystal structure can be maintained even after repeated charge and discharge at high voltages, resulting in a positive electrode active material layer 101 with high capacity and excellent charge and discharge cycle characteristics.

[0044] The molar concentrations of cobalt, nickel, aluminum, and magnesium can be determined, for example, by inductively coupled plasma mass spectrometry (ICP-MS). The molar concentration of fluorine can be determined, for example, by glow discharge mass spectrometry (GD-MS).

[0045] <First principles calculation> Here, the results of calculations of the crystal structure at the interface between the positive electrode active material layer 101 and the base film 104 when lithium cobalt oxide is used for the positive electrode active material layer 101 will be described with reference to FIG.

[0046] 2A shows the case where titanium nitride is used as the underlayer 104. Calculations were made assuming that the titanium nitride has a rock-salt crystal structure belonging to the space group Fm-3m, and the lithium cobalt oxide has a layered rock-salt crystal structure belonging to the space group R-3m. The (111) plane of the titanium nitride and the (001) plane of the lithium cobalt oxide are stacked parallel to each other.

[0047] 2B shows the case where titanium oxide is used as the underlayer 104. Calculations were made assuming that the titanium oxide has a rutile-type crystal structure belonging to the space group P42 / mnm, and the lithium cobalt oxide has a layered rock-salt-type crystal structure belonging to the space group R-3m. The (100) plane of the titanium oxide and the (001) plane of the lithium cobalt oxide are stacked parallel to each other.

[0048] Each figure shows an excerpt of the interface between the positive electrode active material layer 101 and the undercoat film 104. Other calculation conditions are shown in Table 1.

[0049] [Table 1]

[0050] In the case of FIG. 2A where titanium nitride was used as the underlayer 104, the Ti-O distance was 2.03 Å, the Ti-N distance was 1.93 Å, the Co-O distance was 2.25 Å, and the Co-N distance was 2.21 Å. -10 m.

[0051] In rock-salt crystal structures belonging to the space group Fm-3m, the planes where only anions are arranged are parallel to the (111) plane. In titanium nitride, only nitrogen atoms are arranged parallel to the (111) plane. In layered rock-salt crystal structures belonging to the space group R-3m, the planes where only anions are arranged are parallel to the (001) plane. In lithium cobalt oxide, only oxygen atoms are arranged parallel to the (001) plane.

[0052] When the (111) plane of titanium nitride and the (001) plane of lithium cobalt oxide are parallel, the planes on which only anions are arranged are parallel, making the crystal structure more stable.

[0053] Furthermore, both the rock-salt crystal structure belonging to the space group Fm-3m and the layered rock-salt crystal structure belonging to the space group R-3m are crystal structures in which cations and anions are arranged alternately. Therefore, when lithium cobalt oxide having a layered rock-salt crystal structure is laminated on titanium nitride having a rock-salt crystal structure, the crystal orientations of underlayer 104 and positive-electrode active material layer 101 tend to roughly match.

[0054] On the other hand, in the case of titanium oxide (Figure 2B) used as the underlayer 104, the Ti-O distance was 2.15 Å and the Co-O distance was 1.91 Å. In titanium oxide with a rutile crystal structure, oxygen atoms are not arranged on a plane parallel to the (100) plane. Therefore, compared to titanium nitride, it may have a lower ability to stabilize the layered rock-salt crystal structure.

[0055] When lithium cobalt oxide having a layered rock salt type crystal structure is used for the positive electrode active material layer 101 in this way, titanium nitride is particularly suitable for the underlayer 104 .

[0056] FIG. 1B is a perspective view of another example of a positive electrode 100 according to one embodiment of the present invention. The positive electrode 100 shown in FIG. 1B includes a positive electrode current collector 103, a positive electrode active material layer 101, and a cap layer 102. As described above, the positive electrode 100 does not necessarily include the base film 104. Even if the base film 104 is not included, the presence of the cap layer 102 may result in a secondary battery with sufficiently improved cycle characteristics.

[0057] 1A and 1B illustrate a positive electrode in which the positive electrode current collector 103 functions both as a current collector and a substrate, but this is not a limitation of one embodiment of the present invention. Fig. 1C is a perspective view of another example of a positive electrode 100 according to one embodiment of the present invention. As shown in Fig. 1C, the positive electrode 100 may be fabricated by forming the positive electrode current collector 103, an undercoat film 104, a positive electrode active material layer 101, and a cap layer 102 on a substrate 110.

[0058] This embodiment can be implemented in appropriate combination with other embodiments.

[0059] (Embodiment 2) In this embodiment, with reference to FIGS. 3 to 8, a secondary battery having the positive electrode for a secondary battery described in Embodiment 1 and a method for manufacturing the same will be described.

[0060] [Configuration of Secondary Battery] FIG. 3A is a diagram for explaining an example of a stacked structure of a secondary battery 200 having a positive electrode 100 for a secondary battery according to an aspect of the present invention.

[0061] The secondary battery 200 is a thin-film battery, has the positive electrode 100 described in the previous embodiment, and a solid electrolyte layer 203 is formed on the positive electrode 100, and a negative electrode 212 is formed on the solid electrolyte layer 203. The negative electrode 212 has a negative electrode current collector 205 and a negative electrode active material layer 204. Further, as shown in FIG. 3A, it is preferable that the negative electrode 212 has an underlayer film 214 and a cap layer 209.

[0062] The underlayer film 214 is provided between the negative electrode current collector 205 and the negative electrode active material layer 204. The underlayer film 214 has a function of enhancing the conductivity between the negative electrode current collector 205 and the negative electrode active material layer 204. Or it has a function of suppressing excessive expansion of the negative electrode active material layer. Or it has a function of suppressing side reactions between the negative electrode current collector 205 and the negative electrode active material layer 204.

[0063] As the underlayer film 214, it is preferable to use a material having conductivity. Also, it is preferable to use a material that can suppress excessive expansion of the negative electrode active material layer. Also, it is preferable to use a material that is likely to suppress side reactions. For example, titanium compounds such as titanium oxide, titanium nitride, titanium oxide partially substituted with nitrogen, titanium nitride partially substituted with oxygen, or titanium oxynitride (TiO x N y , 0 < x < 2, 0 < y < 1) is preferable. In particular, titanium nitride is highly preferable because it has high conductivity and a high function of suppressing side reactions.

[0064] The cap layer 209 is provided between the negative electrode active material layer 204 and the solid electrolyte layer 203. The cap layer 209 has a function of suppressing side reactions between the negative electrode active material layer 204 and the solid electrolyte layer 203.

[0065] Preferably, titanium or a titanium compound is used as the cap layer 209. Examples of the titanium compound include titanium oxide, titanium nitride, titanium oxide partially substituted with nitrogen, titanium nitride partially substituted with oxygen, or titanium oxynitride (TiO x N y , where 0 < x < 2 and 0 < y < 1). Titanium is a material that can be contained in the solid electrolyte. Therefore, titanium and titanium compounds are particularly suitable as the cap layer 209.

[0066] As the negative electrode active material layer 204, silicon, carbon, titanium oxide, vanadium oxide, indium oxide, zinc oxide, tin oxide, nickel oxide, etc. can be used. Also, materials that alloy with lithium such as tin, gallium, aluminum, etc. can be used. Also, these alloying metal oxides can be used. Also, lithium titanate oxides (Li4Ti5O 12 , LiTi2O4, etc.) can be used, but among them, a material containing silicon and oxygen (also referred to as a SiO x film) is preferred. Also, lithium metal can be used as the negative electrode active material layer 204. Also, mixtures of these materials can be used. For example, a mixture of silicon particles and carbon is suitable because of its good reliability and relatively high energy density per volume.

[0067] The solid electrolyte layer 203 is provided between the positive electrode 100 and the negative electrode 212. As the material of the solid electrolyte layer 203, Li 0.35 La 0.55 TiO3, La (2 / 3-A) Li 3A TiO 3、 Li3PO 4、 LixPO (4-B) N B 、LiNb (1-A) Ta (A) WO6、Li7La3Zr2O 12 ,Li(1+A) Al (A) Ti (2-A) (PO4)3, Li (1+A) Al (A) Ge (2-A) (PO4)3, LiNbO2, etc. can be mentioned. Note that A > 0 and B > 0. As the film formation method, sputtering method, evaporation method, etc. can be used.

[0068] It is preferable to use a compound containing titanium for the solid electrolyte layer 203. Since the cap layer 102 of the positive electrode 100 and the cap layer 209 of the negative electrode 212 contain titanium, if a material containing titanium is also used for the solid electrolyte layer 203, a secondary battery can be easily manufactured.

[0069] Also, SiO C (0 < C ≤ 2) can also be used as the solid electrolyte layer 203. Using SiO C (0 < C ≤ 2) as the solid electrolyte layer 203 and further using SiO C (0 < C ≤ 2) for the negative electrode active material layer 204 may be acceptable. In this case, it is preferable that the ratio of silicon to oxygen (O / Si) of SiO C is higher in the solid electrolyte layer 203. With this configuration, conductive ions (especially lithium ions) are likely to diffuse in the solid electrolyte layer 203, and conductive ions (especially lithium ions) are likely to desorb or accumulate in the negative electrode active material layer 204, so a solid secondary battery with good characteristics can be obtained. By using materials composed of the same components for the solid electrolyte layer 203 and the negative electrode active material layer 204 as described above, a secondary battery can be easily manufactured.

[0070] Also, the solid electrolyte layer 203 may have a laminated structure. When laminating, a material obtained by adding nitrogen to lithium phosphate (Li3PO4) (also called Li3PO (4-Z) N Z :LiPON) may be laminated. Note that Z > 0.

[0071] 3B , a secondary battery 200 may be provided having an anode 212 in which a plurality of anode active material layers 204 and cap layers 209 are stacked. Stacking a plurality of anode active material layers 204 and cap layers 209 can improve capacity while suppressing excessive expansion of the anode 212. In this case, the cap layer 209 in contact with the solid electrolyte layer 203 and the cap layer 209 sandwiched between the anode active material layers 204 may be made of the same material or different materials. For example, titanium oxide may be used for the cap layer 209 in contact with the solid electrolyte layer 203, and titanium nitride may be used for the cap layer 209 sandwiched between the anode active material layers 204.

[0072] Furthermore, as shown in FIG. 3C , a secondary battery 200 may be provided having a cathode 100 in which a plurality of cathode active material layers 101 and cap layers 102 are stacked. By stacking a plurality of cathode active material layers 101 and cap layers 102, it is possible to improve the capacity while suppressing the collapse of the crystalline structure of the cathode active material layers 101. In this case, the cap layer 102 in contact with the solid electrolyte layer 203 and the cap layer 102 sandwiched between the cathode active material layers 101 may be made of the same material or different materials. For example, titanium oxide may be used for the cap layer 102 in contact with the solid electrolyte layer 203, and titanium nitride may be used for the cap layer 102 sandwiched between the cathode active material layers 101.

[0073] 4A and 4B show a more specific example of a secondary battery 200 according to one embodiment of the present invention. Here, the secondary battery 200 formed over a substrate 110 will be described.

[0074] Fig. 4A is a top view, and Fig. 4B is a cross-sectional view taken along line A-A' in Fig. 4A. Secondary battery 200 is a thin-film battery, and as shown in Fig. 4B, positive electrode 100 described in the previous embodiment is formed on substrate 110, solid electrolyte layer 203 is formed on positive electrode 100, and negative electrode 210 is formed on solid electrolyte layer 203. Negative electrode 210 has negative electrode current collector 205, base film 214, negative electrode active material layer 204, and cap layer 209.

[0075] In addition, it is preferable that the secondary battery 200 has a protective layer 206 formed on the positive electrode 100 , the solid electrolyte layer 203 , and the negative electrode 210 .

[0076] The films forming these layers can be formed using metal masks. The positive electrode current collector 103, the base film 104, the positive electrode active material layer 101, the cap layer 102, the solid electrolyte layer 203, the cap layer 209, the negative electrode active material layer 204, the base film 214, and the negative electrode current collector 205 can be selectively formed using a sputtering method. Alternatively, the solid electrolyte layer 203 may be selectively formed using a co-evaporation method using a metal mask.

[0077] 4A, a negative electrode terminal and a positive electrode terminal are formed by exposing a portion of the negative electrode current collector 205 and a portion of the positive electrode current collector 103. The areas other than the negative electrode terminal and the positive electrode terminal are covered with a protective layer 206.

[0078] Note that although the configuration in which the solid electrolyte layer 203, the negative electrode active material layer 204, and the negative electrode current collector 205 are stacked in this order on the positive electrode 100 including the positive electrode current collector 103, the base film 104, the positive electrode active material layer 101, and the cap layer 102 has been described in FIGS. 4A and 4B, one embodiment of the present invention is not limited thereto.

[0079] 4C , the secondary battery 200 may have a positive electrode 100 without an underlayer 104 between the positive electrode current collector 103 and the positive electrode active material layer 101. Alternatively, the secondary battery 200 may have a negative electrode 210 without an underlayer 214 and a cap layer 209.

[0080] In addition, both the positive electrode and the negative electrode of the secondary battery of one embodiment of the present invention may have a stacked structure of an active material layer and a cap layer. For example, as shown in FIG. 4D , a secondary battery 200 may have a negative electrode 210 in which a plurality of negative electrode active material layers 204 and a plurality of cap layers 209 are stacked. Alternatively, the secondary battery 200 may have a positive electrode 100 in which a plurality of positive electrode active material layers 101 and a plurality of cap layers 102 are stacked.

[0081] 5A and 5B, a secondary battery of one embodiment of the present invention may be a secondary battery 201 including a negative electrode 211 that serves both as a negative electrode current collector layer and a negative electrode active material layer. FIG. 5A is a top view of the secondary battery 201, and FIG. 5B is a cross-sectional view taken along line B-B' in FIG. 5A. By using the negative electrode 211 that serves both as a negative electrode current collector layer and a negative electrode active material layer, a secondary battery can be manufactured with simplified manufacturing processes and high productivity. Furthermore, a secondary battery with high energy density can be manufactured.

[0082] 5C and 5D, the secondary battery of one embodiment of the present invention may be a secondary battery 202 in which a solid electrolyte layer 203 and a positive electrode 100 are stacked on a negative electrode 210. FIG. 5C is a top view of the secondary battery 202, and FIG. 5D is a cross-sectional view taken along line CC' in FIG. 5C.

[0083] 4 and 5 illustrate a secondary battery in which not only the positive electrode but also the solid electrolyte layer and the negative electrode are formed as thin films, but one embodiment of the present invention is not limited to this. Another embodiment of the present invention may be a secondary battery having an electrolytic solution. Another embodiment may be a secondary battery having an electrolytic solution and a negative electrode that also serves as a negative electrode current collector layer and a negative electrode active material layer. Another embodiment may be a secondary battery having a negative electrode prepared by coating a negative electrode current collector with a powdered negative electrode active material.

[0084] A secondary battery 230 having an electrolyte solution is shown in Figures 6A and 6B, where Figure 6A is a top view and Figure 6B is a cross-sectional view taken along line DD' in Figure 6A.

[0085] 6B, secondary battery 230 has positive electrode 100 on substrate 110, negative electrode 212 on substrate 111, separator 220, electrolyte 221, and exterior body 222. Negative electrode current collector 205, negative electrode active material layer 204, and cap layer 209 of negative electrode 212 are formed as thin films.

[0086] 6A , secondary battery 230 has lead electrodes 223a and 223b. Lead electrode 223a is electrically connected to positive electrode current collector 103. Lead electrode 223b is electrically connected to negative electrode current collector 205. Portions of lead electrodes 223a and 223b are drawn out of exterior body 222.

[0087] 7A and 7B show a secondary battery 231 having an electrolyte solution and a negative electrode 211 that serves both as a negative electrode current collector layer and a negative electrode active material layer. Fig. 7A is a top view, and Fig. 7B is a cross-sectional view taken along line E-E' in Fig. 7A.

[0088] 7B, a secondary battery 231 includes a positive electrode 100, a negative electrode 211 that also serves as a negative electrode current collector layer and a negative electrode active material layer, a separator 220, an electrolyte 221, and an exterior body 222. By using the negative electrode 211 that also serves as a negative electrode current collector layer and a negative electrode active material layer, the manufacturing process can be simplified, resulting in a secondary battery with high productivity. In addition, a secondary battery with high energy density can be obtained.

[0089] [Production method] Next, an example of the flow of a method for manufacturing the secondary battery 200 shown in FIGS. 4A and 4B will be described with reference to FIG.

[0090] First, a positive electrode current collector 103 is formed on a substrate 110 (S1). Examples of film formation methods include sputtering and vapor deposition. A conductive substrate may also be used as the current collector. The positive electrode current collector 103 may be made of a highly conductive material, such as gold, platinum, aluminum, titanium, copper, magnesium, iron, cobalt, nickel, zinc, germanium, indium, silver, or palladium, or an alloy thereof. Alternatively, aluminum doped with an element that improves heat resistance, such as silicon, titanium, neodymium, scandium, or molybdenum, may also be used. Alternatively, the positive electrode current collector 103 may be made of a metal element that reacts with silicon to form a silicide. Examples of metal elements that react with silicon to form a silicide include zirconium, titanium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, cobalt, and nickel.

[0091] Furthermore, a ceramic substrate, a glass substrate, a resin substrate, a silicon substrate, a metal substrate, or the like can be used as the substrate 110. If a flexible material is used as the substrate 110, a flexible thin-film secondary battery can be manufactured.

[0092] The positive electrode current collector 103 can function both as a substrate and a positive electrode current collector by using a highly conductive material. In this case, it is preferable to use a metal substrate such as titanium or copper. When the base film 104 is provided, the base film 104 prevents the positive electrode current collector 103 from being oxidized by oxygen contained in the positive electrode active material layer 101 or the like, or prevents the diffusion of metal atoms. Therefore, even a material that is easily oxidized or a material that contains easily diffusible metal atoms can be used for the positive electrode current collector 103.

[0093] Next, the base film 104 is formed (S2). The base film 104 can be formed by sputtering, vapor deposition, or the like. For example, when titanium nitride is used as the base film 104, the titanium nitride can be formed by reactive sputtering using a titanium target and nitrogen gas.

[0094] Next, the positive electrode active material layer 101 is formed (S3). The positive electrode active material layer 101 can be formed by sputtering using a sputtering target whose main component is an oxide containing lithium and one or more of manganese, cobalt, and nickel. For example, a sputtering target whose main component is lithium cobalt oxide (LiCoO2, LiCo2O4, etc.), a sputtering target whose main component is lithium manganese oxide (LiMnO2, LiMn2O4, etc.), or a sputtering target whose main component is lithium nickel oxide (LiNiO2, LiNi2O4, etc.) can be used. Alternatively, the positive electrode active material layer 101 may be formed by vacuum deposition.

[0095] In addition, in the sputtering method, selective film formation is possible by using a metal mask. Alternatively, the positive electrode active material layer 101 may be patterned by selectively removing the resist mask or the like by dry etching or wet etching.

[0096] Furthermore, in order to form the positive electrode active material layer 101 containing magnesium, fluorine, aluminum, etc., a sputtering target containing magnesium, fluorine, aluminum, etc. in addition to lithium and one or more of manganese, cobalt, and nickel may be used for film formation. Alternatively, after forming a film using a sputtering target containing as its main component an oxide containing lithium and one or more of manganese, cobalt, and nickel, magnesium, fluorine, aluminum, etc. may be deposited by vacuum evaporation and annealed.

[0097] Next, the cap layer 102 is formed on the positive electrode active material layer 101 (S4). The cap layer 102 can be formed by sputtering, vapor deposition, or the like. For example, when titanium oxide is used as the cap layer 102, the titanium oxide can be formed by reactive sputtering using a titanium target and oxygen gas. Alternatively, the titanium oxide can be formed by sputtering a titanium oxide target.

[0098] The positive electrode active material layer 101 and the cap layer 102 are preferably formed at high temperatures (500° C. or higher), which allows the formation of a positive electrode 100 with better crystallinity.

[0099] Next, the solid electrolyte layer 203 is formed on the positive electrode active material layer 101 (S5).

[0100] It is preferable to use a compound containing titanium for the solid electrolyte layer 203. Since the cap layer 102 of the positive electrode 100 contains titanium, a secondary battery can be easily fabricated by using a material containing titanium for the solid electrolyte layer 203. The film formation method can be a sputtering method, a vapor deposition method, or the like.

[0101] Next, the negative electrode active material layer 204 is formed on the solid electrolyte layer 203 (S6). As the film forming method, a sputtering method, a vapor deposition method, or the like can be used.

[0102] Next, the negative electrode current collector 205 is formed on the negative electrode active material layer 204 (S7). The material of the negative electrode current collector 205 is one or more conductive materials selected from aluminum, titanium, copper, gold, chromium, tungsten, molybdenum, nickel, silver, and the like. Film formation methods include sputtering and vapor deposition. In sputtering, a metal mask can be used to selectively form a film. Alternatively, the conductive film may be patterned by selectively removing the film by dry etching or wet etching using a resist mask or the like.

[0103] When the positive electrode current collector 103 or the negative electrode current collector 205 is formed by sputtering, it is preferable to form at least one of the positive electrode active material layer 101 and the negative electrode active material layer 204 by sputtering. The sputtering device can perform continuous film formation in the same chamber or using multiple chambers, and can also be a multi-chamber manufacturing device or an in-line manufacturing device. The sputtering method is a manufacturing method suitable for mass production using a chamber and a sputtering target. Furthermore, the sputtering method allows for thin film formation and has excellent film formation characteristics.

[0104] Next, it is preferable to form a protective layer 206 on the positive electrode 100, the solid electrolyte layer 203, and the negative electrode 210 (S8). The protective layer 206 can be made of a metal oxide containing one or more elements selected from hafnium, aluminum, gallium, yttrium, zirconium, tungsten, titanium, tantalum, nickel, germanium, neodymium, lanthanum, magnesium, etc. Silicon nitride oxide or silicon nitride can also be used. The protective layer 206 can be formed by sputtering.

[0105] Furthermore, the layers described in this embodiment are not limited to being formed by sputtering, and gas phase methods (vacuum evaporation, thermal spraying, pulsed laser deposition (PLD), ion plating, cold spray, and aerosol deposition) can also be used. The aerosol deposition (AD) method is a method of forming a film without heating the substrate. Aerosol refers to fine particles dispersed in a gas. Alternatively, CVD or ALD (Atomic Layer Deposition) can be used.

[0106] Through the above steps, the secondary battery 200 of one embodiment of the present invention can be manufactured.

[0107] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0108] (Embodiment 3) In order to increase the output voltage of a thin-film secondary battery, the secondary batteries can be connected in series. While the example of a secondary battery having one cell was shown in the second embodiment, this embodiment shows an example of fabricating a thin-film secondary battery in which a plurality of cells are connected in series.

[0109] Fig. 9A shows a top view of the first secondary battery immediately after its formation, and Fig. 9B shows a top view of two secondary batteries connected in series. Note that in Fig. 9A and Fig. 9B, the same reference numerals are used for the same parts as in Fig. 5A shown in Embodiment 2.

[0110] 9A shows the state immediately after the deposition of negative electrode current collector 205. The shape of the top surface of negative electrode current collector 205 differs from that of FIG. 5A. Negative electrode current collector 205 shown in FIG. 9A is in contact with a part of the side surface of the solid electrolyte layer and also with the insulating surface of the substrate.

[0111] Then, a second negative electrode active material layer, a second solid electrolyte layer 213, a second positive electrode active material layer, and a second positive electrode current collector 215 are formed in this order on a region of the negative electrode current collector 205 that does not overlap with the first negative electrode active material layer. Finally, a protective layer 206 is formed (FIG. 9B).

[0112] FIG. 9B shows a configuration in which two solid-state secondary batteries are arranged on a plane and connected in series.

[0113] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0114] (Fourth embodiment) In order to increase the output voltage or discharge capacity of the thin-film secondary battery, a multi-layer secondary battery can be formed in which multiple positive electrodes and multiple negative electrodes are stacked one on top of the other. While the second embodiment shows an example of a secondary battery that is a single-layer cell, the present embodiment shows an example of a thin-film battery that is a multi-layer cell.

[0115] 10 shows an example of a cross section of a three-layer thin-film battery. A positive electrode current collector 103 is formed on a substrate 110, and a base film 104, a positive electrode active material layer 101, a cap layer 102, a solid electrolyte layer 203, a negative electrode active material layer 204, and a negative electrode current collector 205 are sequentially formed on the positive electrode current collector 103 to form the first cell.

[0116] Furthermore, a second negative electrode active material layer 204, a solid electrolyte layer, a cap layer, a positive electrode active material layer, a base film, and a positive electrode current collector layer are sequentially formed on the negative electrode current collector 205 to form a second cell.

[0117] Furthermore, the third cell is constructed by sequentially forming a third layer of base film, a positive electrode active material layer, a cap layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector layer on the second layer of positive electrode current collector.

[0118] In Fig. 10, a protective layer 206 is formed last. The three-layer stack shown in Fig. 10 is configured to be connected in series to increase capacity, but it can also be connected in parallel via external wiring. Also, series and parallel or series-parallel can be selected via external wiring.

[0119] It is preferable to use the same material for the solid electrolyte layer 203, the second solid electrolyte layer, and the third solid electrolyte layer, as this reduces manufacturing costs.

[0120] FIG. 11 shows an example of a manufacturing flow for obtaining the structure shown in FIG.

[0121] In Fig. 11, in order to reduce the number of manufacturing steps, it is preferable to use a lithium cobalt oxide film as the positive electrode active material layer and a titanium film as the positive electrode current collector and the negative electrode current collector (conductive layer). By using a titanium film as a common electrode, a three-layer stacked cell can be realized with a small configuration.

[0122] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0123] (Embodiment 5) In this embodiment, an example of a multi-chamber manufacturing apparatus that can fully automate the manufacturing of the positive electrode current collector layer to the negative electrode current collector layer of a secondary battery is shown in FIGS. 12 and 13. The manufacturing apparatus can be suitably used for manufacturing the thin-film secondary battery of one embodiment of the present invention.

[0124] Figure 12 shows an example of a multi-chamber manufacturing apparatus equipped with gates 880, 881, 882, 883, 884, 885, 886, 887, 888, a load lock chamber 870, a mask alignment chamber 891, a first transfer chamber 871, a second transfer chamber 872, a third transfer chamber 873, multiple film formation chambers (first film formation chamber 892, second film formation chamber 874), a heating chamber 893, a second material supply chamber 894, a first material supply chamber 895, and a third material supply chamber 896.

[0125] The mask alignment chamber 891 includes at least a stage 851 and a substrate transport mechanism 852 .

[0126] The first transfer chamber 871 has a substrate cassette lifting mechanism, the second transfer chamber 872 has a substrate transfer mechanism 853, and the third transfer chamber 873 has a substrate transfer mechanism 854.

[0127] The first film formation chamber 892, the second film formation chamber 874, the second material supply chamber 894, the first material supply chamber 895, the third material supply chamber 896, the mask alignment chamber 891, the first transfer chamber 871, the second transfer chamber 872, and the third transfer chamber 873 are each connected to an exhaust mechanism. As the exhaust mechanism, an appropriate exhaust device may be selected depending on the intended use of each chamber, and examples include an exhaust mechanism equipped with a pump having an adsorption means such as a cryopump, a sputter ion pump, or a titanium sublimation pump, and an exhaust mechanism equipped with a turbomolecular pump and a cold trap.

[0128] The procedure for forming a film on a substrate is as follows: a substrate 850 or a substrate cassette is placed in a load lock chamber 870, and then transported to a mask alignment chamber 891 by a substrate transport mechanism 852. In the mask alignment chamber 891, a mask to be used is picked up from a plurality of masks that have been set in advance, and the mask is aligned with the substrate on a stage 851. After alignment is complete, a gate 880 is opened, and the mask and substrate 850 are transported to a first transport chamber 871 by the substrate transport mechanism 852. After the mask and substrate 850 have been transported to the first transport chamber 871, a gate 881 is opened, and the mask and substrate 850 are transported to a second transport chamber 872 by a substrate transport mechanism 853.

[0129] The first film formation chamber 892, which is connected to the second transfer chamber 872 via a gate 882, is a sputtering film formation chamber. The sputtering film formation chamber has a mechanism that can switch between an RF power supply and a pulsed DC power supply to apply voltage to the sputtering target. Two or three types of sputtering targets can be set. In this embodiment, a single crystal silicon target, a sputtering target mainly composed of lithium cobalt oxide (LiCoO2), and a titanium target are installed. A substrate heating mechanism is installed in the first film formation chamber 892, and it is also possible to perform film formation while the heater temperature is raised to 700°C.

[0130] The negative electrode active material layer can be formed by sputtering using a single crystal silicon target. Also, SiO X A film made of titanium can be used as the negative electrode active material layer. A silicon nitride film can also be used as a sealing film by reactive sputtering using Ar gas and N2 gas. A positive electrode active material layer can also be formed by sputtering using a sputtering target whose main component is lithium cobalt oxide (LiCoO2). A conductive film that serves as a current collector can be formed by sputtering using a titanium target. A titanium nitride film can also be formed by reactive sputtering using Ar gas and N2 gas, and used to form a cap layer or base film.

[0131] When forming a positive electrode active material layer, the substrate is transported from the second transport chamber 872 to the first film formation chamber 892 with the mask and the substrate stacked thereon by the substrate transport mechanism 853, and then the gate 882 is closed and film formation is performed by sputtering. After film formation is completed, the gates 882 and 883 are opened, the substrate is transported to the heating chamber 893, and the gate 883 is closed, after which heating can be performed. For the heating treatment in the heating chamber 893, an RTA (Rapid Thermal Anneal) device, a resistance heating furnace, or a microwave heating device can be used. For the RTA device, a GRTA (Gas Rapid Thermal Anneal) device or an LRTA (Lamp Rapid Thermal Anneal) device can be used. The heating treatment in the heating chamber 893 can be performed in an atmosphere of nitrogen, oxygen, a rare gas, or dry air. The heating time is from 1 minute to 24 hours.

[0132] After the film formation or heat treatment is completed, the substrate and mask are returned to the mask alignment chamber 891, and a new mask is aligned. After alignment, the substrate and mask are transferred to the first transfer chamber 871 by the substrate transfer mechanism 852. The substrate is transferred by the lifting mechanism of the first transfer chamber 871, and after the gate 884 is opened, the substrate is transferred to the third transfer chamber 873 by the substrate transfer mechanism 854.

[0133] The second film formation chamber 874, which is connected to the third transfer chamber 873 via a gate 885, performs film formation by evaporation.

[0134] An example of the cross-sectional structure of the second film formation chamber 874 is shown in FIG. 13. FIG. 13 is a schematic cross-sectional view taken along the dotted line in FIG. 12. The second film formation chamber 874 is connected to an exhaust mechanism 849, and the first material supply chamber 895 is connected to an exhaust mechanism 848. The second material supply chamber 894 is connected to an exhaust mechanism 847. The second film formation chamber 874 shown in FIG. 13 is an evaporation chamber that performs evaporation using an evaporation source 856 moved from the first material supply chamber 895. Evaporation sources can be moved from multiple material supply chambers, and multiple substances can be simultaneously vaporized and evaporated for evaporation, i.e., co-evaporation can be performed. FIG. 13 also shows an evaporation source having an evaporation boat 858 moved from the second material supply chamber 894.

[0135] The second film formation chamber 874 is connected to a second material supply chamber 894 via a gate 886. The second film formation chamber 874 is connected to a first material supply chamber 895 via a gate 888. The second film formation chamber 874 is connected to a third material supply chamber 896 via a gate 887. Therefore, the second film formation chamber 874 is capable of three-source co-evaporation.

[0136] In the vapor deposition procedure, first, a substrate is placed on a substrate holder 845. The substrate holder 845 is connected to a rotation mechanism 865. Then, a first vapor deposition material 855 is heated to a certain extent in a first material supply chamber 895, and when the vapor deposition rate becomes stable, a gate 888 is opened, an arm 862 is extended, and a vapor deposition source 856 is moved and stopped at a position below the substrate. The vapor deposition source 856 is composed of the first vapor deposition material 855, a heater 857, and a container for storing the first vapor deposition material 855. Similarly, a second vapor deposition material is heated to a certain extent in a second material supply chamber 894, and when the vapor deposition rate becomes stable, a gate 886 is opened, and an arm 861 is extended, and the vapor deposition source is moved and stopped at a position below the substrate.

[0137] Thereafter, the shutter 868 and the deposition source shutter 869 are opened to perform co-evaporation. During the evaporation, the rotation mechanism 865 is rotated to improve the uniformity of the film thickness. After the evaporation, the substrate is transported to the mask alignment chamber 891 along the same route. When the substrate is to be removed from the manufacturing equipment, it is transported from the mask alignment chamber 891 to the load lock chamber 870 and then removed.

[0138] 13 shows an example in which a substrate 850 and a mask are held by a substrate holder 845. By rotating the substrate 850 (and the mask) using a substrate rotation mechanism, the uniformity of film formation can be improved. The substrate rotation mechanism may also serve as a substrate transport mechanism.

[0139] Furthermore, the second film formation chamber 874 may be provided with an imaging means 863 such as a CCD camera. By providing the imaging means 863, the position of the substrate 850 can be confirmed.

[0140] In the second film formation chamber 874, the thickness of the film formed on the surface of the substrate can be predicted based on the measurement results of the film thickness measurement mechanism 867. The film thickness measurement mechanism 867 may include, for example, a quartz oscillator.

[0141] In order to control the deposition of the vaporized deposition material, a shutter 868 that overlaps with the substrate until the evaporation rate of the deposition material stabilizes, and a deposition source shutter 869 that overlaps with the deposition source 856 and the deposition boat 858 are provided.

[0142] Although an example of a resistance heating type of evaporation source 856 is shown, an EB (Electron Beam) evaporation type may also be used. Furthermore, although a crucible is shown as an example of a container for evaporation source 856, an evaporation boat may also be used. An organic material is placed as first evaporation material 855 in the crucible heated by heater 857. Furthermore, when pellets or particulate SiO or the like are used as the evaporation material, an evaporation boat 858 is used. The evaporation boat 858 consists of three parts, which are stacked on top of each other: a member with a concave surface, an inner lid with two holes, and an upper lid with one hole. Note that the inner lid may be removed during evaporation. The evaporation boat 858 acts as a resistor when electricity is applied, and the evaporation boat itself heats up.

[0143] Furthermore, although the present embodiment has been described as an example of a multi-chamber system, the present invention is not particularly limited thereto, and an in-line type manufacturing apparatus may also be used.

[0144] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0145] (Sixth embodiment) In this embodiment, an example of a thin-film secondary battery having a battery control circuit and the like will be described.

[0146] 14A is an external view of a thin-film secondary battery. The secondary battery 913 includes a terminal 951 and a terminal 952. The terminal 951 is electrically connected to a positive electrode, and the terminal 952 is electrically connected to a negative electrode. The secondary battery of one embodiment of the present invention has excellent cycle characteristics. Furthermore, since it can be an all-solid-state secondary battery, it also has excellent safety. Therefore, the secondary battery of one embodiment of the present invention can be suitably used as the secondary battery 913.

[0147] 14B is an external view of the battery control circuit. The battery control circuit shown in FIG. 14B includes a substrate 900 and a layer 916. A circuit 912 and an antenna 914 are provided over the substrate 900. The antenna 914 is electrically connected to the circuit 912. Terminals 971 and 972 are electrically connected to the circuit 912. The circuit 912 is electrically connected to terminal 911.

[0148] The terminal 911 is connected to, for example, a device to which power is supplied from the thin-film solid secondary battery, such as a display device, a sensor, or the like.

[0149] The layer 916 has a function of shielding, for example, an electromagnetic field generated by the secondary battery 913. The layer 916 can be made of, for example, a magnetic material.

[0150] 14C shows an example in which the battery control circuit shown in FIG. 14B is disposed on a secondary battery 913. Terminal 971 is electrically connected to terminal 951, and terminal 972 is electrically connected to terminal 952. Layer 916 is disposed between substrate 900 and secondary battery 913.

[0151] The substrate 900 is preferably a flexible substrate.

[0152] A thin battery control circuit can be realized by using a flexible substrate as the substrate 900. Furthermore, the battery control circuit can be wrapped around the secondary battery as shown in Fig. 15D, which will be described later.

[0153] Another example of a thin-film secondary battery having a battery control circuit etc. will be described with reference to Figures 15A to 15D. Figure 15A is an external view of a thin-film solid-state secondary battery. The battery control circuit shown in Figure 15B has a substrate 900 and a layer 916.

[0154] As shown in Fig. 15C, by bending substrate 900 to fit the shape of secondary battery 913 and arranging the battery control circuit around the secondary battery, the battery control circuit can be wrapped around the secondary battery as shown in Fig. 15D. A secondary battery with such a configuration can be made smaller.

[0155] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0156] (Embodiment 7) In this embodiment, examples of electronic devices using a thin-film secondary battery will be described with reference to FIGS. 16A, 16B, and 17A to 17C. The secondary battery of one embodiment of the present invention has high discharge capacity, high cycle characteristics, and high safety. Therefore, the electronic devices are highly safe and can be used for a long time.

[0157] 16A is a perspective view of the appearance of a thin-film secondary battery 3001 according to the present invention. A positive electrode lead electrode 513 electrically connected to the positive electrode of the solid secondary battery and a negative electrode lead electrode 511 electrically connected to the negative electrode are sealed with a laminate film or an insulating material so as to protrude.

[0158] 16B shows an IC card, which is an example of an application device using the thin-film secondary battery according to the present invention. Power obtained by power supply from radio waves 3005 can be charged into thin-film secondary battery 3001. An antenna, IC 3004, and thin-film secondary battery 3001 are arranged inside IC card 3000. ID 3002 and photo 3003 of the worker wearing the management badge are displayed on IC card 3000. The power charged in thin-film secondary battery 3001 can also be used to transmit signals such as authentication signals from the antenna.

[0159] An active matrix display device may be provided to display the ID 3002 and the photo 3003. Examples of active matrix display devices include reflective liquid crystal displays, organic EL displays, and electronic paper. The active matrix display device can also display images (moving or still images) and time. Power for the active matrix display device can be supplied from a thin-film secondary battery 3001.

[0160] Since a plastic substrate is used in an IC card, an organic EL display device using a flexible substrate is preferred.

[0161] A solar cell may be provided in place of the photo 3003. When irradiated with external light, the solar cell absorbs the light, generates electricity, and the electricity can be used to charge the thin-film secondary battery 3001.

[0162] Furthermore, the thin-film secondary battery is not limited to use in IC cards, but can also be used as a power source for wireless sensors used in vehicles, a secondary battery for MEMS devices, and the like.

[0163] Figure 17A shows an example of a wearable device. A wearable device may use a secondary battery as a power source. Furthermore, when used at home or outdoors, a wearable device that can be charged wirelessly, as well as via a wired connection with an exposed connector, is desired in order to improve splash resistance, water resistance, or dust resistance.

[0164] For example, a secondary battery according to one embodiment of the present invention can be mounted on an eyeglasses-type device 400 as shown in FIG. 17A. The eyeglasses-type device 400 includes a frame 400a and a display unit 400b. Mounting a secondary battery on the temples of the curved frame 400a makes it possible to provide an eyeglasses-type device 400 that is lightweight, has a good weight balance, and can be used for a long time. The inclusion of a secondary battery according to one embodiment of the present invention makes it possible to realize a configuration that can accommodate space saving associated with a smaller housing.

[0165] Furthermore, a secondary battery according to one embodiment of the present invention can be mounted on a headset-type device 401. The headset-type device 401 includes at least a microphone unit 401a, a flexible pipe 401b, and an earphone unit 401c. A secondary battery can be provided in the flexible pipe 401b or the earphone unit 401c. By including a secondary battery according to one embodiment of the present invention, a configuration that can accommodate space savings due to a smaller housing can be realized.

[0166] Furthermore, the secondary battery according to one embodiment of the present invention can be mounted on a device 402 that can be directly attached to the body. A secondary battery 402b can be provided in a thin housing 402a of the device 402. By providing the secondary battery according to one embodiment of the present invention, a space-saving configuration can be realized that accompanies a miniaturized housing.

[0167] Furthermore, the secondary battery according to one embodiment of the present invention can be mounted on a device 403 that can be attached to clothing. A secondary battery 403b can be provided in a thin housing 403a of the device 403. By providing the secondary battery according to one embodiment of the present invention, a space-saving configuration can be realized that accompanies a miniaturized housing.

[0168] Furthermore, the secondary battery of one embodiment of the present invention can be mounted on the belt-type device 406. The belt-type device 406 has a belt portion 406a and a wireless power receiving portion 406b, and the secondary battery can be mounted inside the belt portion 406a. By including the secondary battery of one embodiment of the present invention, a configuration that can accommodate space saving due to miniaturization of the housing can be realized.

[0169] Furthermore, the secondary battery of one embodiment of the present invention can be mounted on the wristwatch device 405. The wristwatch device 405 has a display portion 405a and a belt portion 405b, and the secondary battery can be provided on the display portion 405a or the belt portion 405b. By providing the secondary battery of one embodiment of the present invention, a space-saving configuration can be realized that accompanies a miniaturized housing.

[0170] The display unit 405a can display not only the time but also various other information such as incoming emails and phone calls.

[0171] Furthermore, since the wristwatch device 405 is a wearable device that is worn directly on the wrist, it may be equipped with sensors that measure the user's pulse, blood pressure, etc. Data on the user's exercise volume and health can be accumulated to manage the user's health.

[0172] FIG. 17B shows a perspective view of the wristwatch type device 405 removed from the wrist.

[0173] 17C shows a side view of wristwatch type device 405. FIG. 17C shows that secondary battery 913 is built inside. Secondary battery 913 is the secondary battery described in Embodiment 5. Secondary battery 913 is provided at a position overlapping with display portion 405a, and is small and lightweight.

[0174] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0175] (Embodiment 8) In this embodiment, electronic devices using a secondary battery including a positive electrode of one embodiment of the present invention will be described with reference to FIGS. 18A to 18C, 19A to 19D, and 20A and 20B. A secondary battery including a positive electrode of one embodiment of the present invention has high discharge capacity, high cycle characteristics, and high safety. Therefore, it can be suitably used in the following electronic devices. It can be suitably used in electronic devices that require durability in particular.

[0176] 18A shows a perspective view of a wristwatch-type mobile information terminal (also called a smart watch) 700. Mobile information terminal 700 has a housing 701, a display panel 702, a clasp 703, bands 705A and 705B, and operation buttons 711 and 712.

[0177] A display panel 702 mounted on a housing 701 that also serves as a bezel has a rectangular display area. The display area has a curved surface. The display panel 702 is preferably flexible. The display area may also be non-rectangular.

[0178] Band 705A and band 705B are connected to housing 701. Clasp 703 is connected to band 705A. Band 705A and housing 701 are connected via a pin, for example, so that the connection can rotate. The same applies to the connections between band 705B and housing 701, and between band 705A and clasp 703.

[0179] 18B and 18C are perspective views of the band 705A and the secondary battery 750, respectively. The band 705A includes the secondary battery 750. The secondary battery 750 may be, for example, one of the secondary batteries described in the previous embodiment. The secondary battery 750 is embedded inside the band 705A, and a portion of each of the positive electrode lead 751 and the negative electrode lead 752 protrudes from the band 705A (see FIG. 18B). The positive electrode lead 751 and the negative electrode lead 752 are electrically connected to the display panel 702. The surface of the secondary battery 750 is covered with an exterior body 753 (see FIG. 18C). The pins may also function as electrodes. Specifically, the positive electrode lead 751 and the display panel 702, and the negative electrode lead 752 and the display panel 702 may be electrically connected via pins connecting the band 705A to the housing 701, respectively. This simplifies the configuration at the connection between the band 705A and the housing 701.

[0180] Secondary battery 750 is flexible. Therefore, band 705A can be manufactured by integrally forming it with secondary battery 750. For example, secondary battery 750 is placed in a mold that corresponds to the outer shape of band 705A, and the material of band 705A is poured into the mold and cured, thereby manufacturing band 705A shown in FIG. 18B.

[0181] When a rubber material is used as the material for the band 705A, the rubber is hardened by heat treatment. For example, when fluororubber is used as the rubber material, it is hardened by heat treatment at 170°C for 10 minutes. When silicone rubber is used as the rubber material, it is hardened by heat treatment at 150°C for 10 minutes.

[0182] Materials used for the band 705A include fluororubber, silicone rubber, fluorosilicone rubber, and urethane rubber.

[0183] 18A can have various functions. For example, it can have a function of displaying various information (still images, videos, text images, etc.) in a display area, a touch panel function, a function of displaying a calendar, date or time, etc., a function of controlling processing by various software (programs), a wireless communication function, a function of connecting to various computer networks using the wireless communication function, a function of transmitting or receiving various data using the wireless communication function, a function of reading out programs or data recorded on a recording medium and displaying them in a display area, etc.

[0184] The housing 701 may also include a speaker, a sensor (including a function of measuring force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared ray), a microphone, etc. The portable information terminal 700 can be manufactured by using a light-emitting element for the display panel 702.

[0185] 18A shows an example in which secondary battery 750 is included in band 705A, secondary battery 750 may be included in band 705B. Band 705B can be made of the same material as band 705A.

[0186] 19A shows an example of a cleaning robot. The cleaning robot 6300 has a display unit 6302 arranged on the top surface of a housing 6301, a plurality of cameras 6303 arranged on the side surface, a brush 6304, an operation button 6305, various sensors, and the like. Although not shown, the cleaning robot 6300 is provided with tires, a suction port, and the like. The cleaning robot 6300 can move by itself, detect dust 6310, and suck up the dust from a suction port arranged on the bottom surface.

[0187] For example, the cleaning robot 6300 can analyze an image captured by the camera 6303 to determine whether or not there is an obstacle such as a wall, furniture, or a step. Furthermore, when an object that may become entangled in the brush 6304, such as a wire, is detected through image analysis, the cleaning robot 6300 can stop rotation of the brush 6304. The cleaning robot 6300 includes a secondary battery according to one embodiment of the present invention and a semiconductor device or an electronic component. By using the secondary battery according to one embodiment of the present invention in the cleaning robot 6300, the cleaning robot 6300 can be a highly reliable electronic device with a long operating time.

[0188] Fig. 19B shows an example of a robot. The robot 6400 shown in Fig. 19B includes a secondary battery 6409, an illuminance sensor 6401, a microphone 6402, an upper camera 6403, a speaker 6404, a display unit 6405, a lower camera 6406, an obstacle sensor 6407, a movement mechanism 6408, a computing device, etc.

[0189] The microphone 6402 has a function of detecting the user's voice, environmental sounds, etc. The speaker 6404 has a function of emitting sound. The robot 6400 can communicate with the user using the microphone 6402 and the speaker 6404.

[0190] The display unit 6405 has a function of displaying various information. The robot 6400 can display information desired by the user on the display unit 6405. The display unit 6405 may be equipped with a touch panel. The display unit 6405 may also be a detachable information terminal, which can be installed in a fixed position on the robot 6400 to enable charging and data transfer.

[0191] The upper camera 6403 and the lower camera 6406 have the function of capturing images of the surroundings of the robot 6400. In addition, the obstacle sensor 6407 can detect the presence or absence of obstacles in the direction of travel when the robot 6400 moves forward using the movement mechanism 6408. The robot 6400 can recognize the surrounding environment and move safely using the upper camera 6403, the lower camera 6406, and the obstacle sensor 6407.

[0192] The robot 6400 includes a secondary battery 6409 according to one embodiment of the present invention and a semiconductor device or an electronic component inside the robot 6400. By using the secondary battery according to one embodiment of the present invention in the robot 6400, the robot 6400 can be a highly reliable electronic device with a long operating time.

[0193] Fig. 19C shows an example of an aircraft. Aircraft 6500 shown in Fig. 19C has propeller 6501, camera 6502, secondary battery 6503, etc., and has the function of flying autonomously.

[0194] For example, image data captured by the camera 6502 is stored in the electronic component 6504. The electronic component 6504 can analyze the image data and detect the presence or absence of an obstacle when moving. Furthermore, the electronic component 6504 can estimate the remaining battery charge from a change in the storage capacity of the secondary battery 6503. The flying object 6500 includes the secondary battery 6503 according to one embodiment of the present invention therein. By using the secondary battery according to one embodiment of the present invention in the flying object 6500, the flying object 6500 can be an electronic device with a long operating time and high reliability.

[0195] 19D shows an example of an automobile. The automobile 7160 includes a secondary battery 7161, an engine, tires, brakes, a steering device, a camera, and the like. The automobile 7160 also preferably includes a system 1000, which will be described later. The automobile 7160 includes a secondary battery 7161 according to one embodiment of the present invention inside. By using a secondary battery according to one embodiment of the present invention in the automobile 7160, the automobile 7160 can have a long cruising distance, high safety, and high reliability.

[0196] Another embodiment of the present invention may be an electronic device or a system including the thin-film battery described in the above embodiment and another secondary battery. The other secondary battery is not particularly limited, and may be, for example, a lithium-ion secondary battery including a positive electrode, a negative electrode, an electrolyte, and a separator, or a bulk all-solid-state secondary battery. Note that in this specification and the like, a system refers to a system in which individual elements are combined. The system includes a secondary battery as one of the elements.

[0197] FIG. 20A shows a system 1000 including a thin-film battery 1001 described in the previous embodiment and a lithium-ion secondary battery 1002 having a positive electrode, a negative electrode, an electrolyte, and a separator. Such an electronic device or system can take advantage of the advantages of both a secondary battery with a larger discharge capacity and the thin-film battery described in the previous embodiment, which is easily made thin and lightweight. The system 1000 preferably includes a wireless power feeder. The wireless power feeder allows for easy power feeding from the lithium-ion secondary battery 1002 to the thin-film battery 1001.

[0198] Fig. 20B shows the interior of an automobile 7160 equipped with the system 1000. The automobile 7160 has a driving secondary battery, a wireless power feeder 7162, and a key 7163. By placing the key 7163 on the wireless power feeder 7162, it is possible to feed power from the driving secondary battery 7161 to the key 7163. Note that Fig. 20B shows an example in which the wireless power feeder 7162 is installed on the dashboard, but this is not limiting. A storage space for the key 7163 may be provided in another location around the driver's seat, and the wireless power feeder 7162 may be installed in this storage space.

[0199] In this case, if the key 7163 has the thin-film battery described in the previous embodiment, the key can be made thinner and lighter, which is preferable. Furthermore, it is preferable to use, as the secondary battery for driving the automobile 7160, a secondary battery that can easily obtain a larger discharge capacity, such as a lithium-ion secondary battery having a positive electrode, a negative electrode, an electrolyte, and a separator, or a bulk all-solid-state secondary battery.

[0200] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0201] (Embodiment 9) The device described in this embodiment includes at least a biosensor and a solid-state secondary battery that supplies power to the biosensor. It can acquire various types of biometric information using infrared light and visible light and store the information in a memory. Such biometric information can be used for both personal authentication of users and healthcare applications. The secondary battery of one embodiment of the present invention has high discharge capacity, high cycle characteristics, and high safety. Therefore, the device is highly safe and can be used for a long period of time.

[0202] A biosensor is a sensor that acquires biological information that can be used for healthcare purposes. Such biological information includes pulse wave, blood glucose level, oxygen saturation, and triglyceride concentration. The data is stored in memory.

[0203] Furthermore, it is preferable to provide the device described in this embodiment with means for acquiring other biological information. For example, in addition to internal biological information such as electrocardiogram, blood pressure, and body temperature, there is also external biological information such as facial expression, complexion, and pupils. Information on the number of steps taken, exercise intensity, elevation change, and diet (calorie intake, nutrients, etc.) is also important information for health care. Using multiple pieces of biological information enables comprehensive health management, which not only contributes to daily health management but also to early detection of injuries and illnesses.

[0204] For example, blood pressure can be calculated from an electrocardiogram and the difference in timing between two beats of a pulse wave (length of pulse wave propagation time). High blood pressure results in a short pulse wave propagation time, and conversely, low blood pressure results in a long pulse wave propagation time. The user's physical condition can also be estimated from the relationship between heart rate and blood pressure calculated from an electrocardiogram and pulse wave. For example, if both the heart rate and blood pressure are high, it can be estimated that the user is in a state of tension or excitement, and conversely, if both the heart rate and blood pressure are low, it can be estimated that the user is in a relaxed state. Furthermore, if the user has low blood pressure and a high heart rate that continues to be present, it could be a sign of heart disease or the like.

[0205] Users can check their own health status at any time, as well as their biological information measured by electronic devices, which can improve their health awareness. This can lead to them reviewing their daily habits, such as avoiding overeating, getting moderate exercise, and managing their health, and may even encourage them to seek medical advice if necessary.

[0206] Each data may be shared among multiple biosensors. Fig. 21A shows an example in which a biosensor 80a is implanted in a user's body and an example in which a biosensor 80b is worn on the user's wrist. Fig. 21A shows a device having a biosensor 80a capable of measuring, for example, an electrocardiogram, and a device having a biosensor 80b capable of measuring heart rate by optically monitoring the pulse of the user's arm. Note that the watch or wristband-type wearable device shown in Fig. 21A is not limited to heart rate measurement, and various biosensors can be used.

[0207] 21A is based on the premise that the device is small, generates almost no heat, and does not cause allergic reactions or the like when it comes into contact with the skin. The secondary battery used in the device of one embodiment of the present invention is suitable because it is small, generates almost no heat, and does not cause allergic reactions or the like. In addition, the implantable device preferably has a built-in antenna so that it can be wirelessly charged.

[0208] The device of the type implanted in a living body shown in FIG. 21A is not limited to a biosensor capable of measuring an electrocardiogram, but may be a biosensor capable of acquiring other biological data.

[0209] The biosensor 80b built into the device may have a function to store acquired data in a temporary memory built into the device. Alternatively, the data acquired by each biosensor may be transmitted wirelessly or via a wired connection to a portable data terminal 85 shown in FIG. 21B, which may then detect waveforms. The portable data terminal 85 may be a smartphone or the like, and may detect problems such as arrhythmia from the data acquired by each biosensor. When transmitting data acquired by multiple biosensors to the portable data terminal 85 via a wired connection, it is preferable to transfer the data acquired by the multiple biosensors together before establishing a wired connection. Each detected data item may be automatically dated and stored in the memory of the portable data terminal 85 for personal management. Alternatively, the data may be transmitted to a medical institution 87, such as a hospital, via a network (including the Internet) as shown in FIG. 21B. The data may be managed by a hospital data server and used as test data during treatment. Because the amount of medical data can be enormous, a network including Bluetooth (registered trademark) or a frequency band from 2.4 GHz to 2.4835 GHz may be used from biosensor 80b to portable data terminal 85, and a fifth-generation wireless system may be used for high-speed communication between portable data terminals 85. The fifth-generation wireless system uses frequencies in the 3.7 GHz, 4.5 GHz, and 28 GHz bands. Using the fifth-generation wireless system makes it possible to acquire and transmit data to medical institutions 87 not only at home but also when the user is out and about. This allows accurate acquisition of data when the user's physical condition becomes abnormal and can be used for subsequent processing or treatment. The configuration shown in FIG. 21C can be used as portable data terminal 85.

[0210] 21C shows another example of a portable data terminal 89. In addition to a secondary battery, the portable data terminal 89 has a speaker, a pair of electrodes 83, a camera 84, and a microphone 86.

[0211] A pair of electrodes 83 is provided on a part of the housing 82, sandwiching a display unit 81a therebetween. The display unit 81b is a region having a curved surface. The electrodes 83 function as electrodes for acquiring biological information.

[0212] As shown in FIG. 21C, by arranging a pair of electrodes 83 in the longitudinal direction of the housing 82, when using the portable data terminal 89 with a landscape screen, biometric information can be acquired without the user being aware of it.

[0213] 1 shows an example of the usage state of a portable data terminal 89. The display unit 81a can display electrocardiogram information 88a acquired by a pair of electrodes 83, heart rate information 88b, and the like.

[0214] This function is unnecessary when biosensor 80a is implanted in the user's body as shown in Figure 21A, but when biosensor 80a is not implanted, the user can obtain an electrocardiogram by holding a pair of electrodes 83 with both hands. Even when biosensor 80a is implanted in the user's body, portable data terminal 89 shown in Figure 21C can be used to check whether biosensor 80a is functioning normally. Portable data terminal 89 shown in Figure 21C can also be used when comparing electrocardiogram data between multiple users.

[0215] The camera 84 can capture an image of the user's face, etc. From the image of the user's face, biological information such as facial expression, pupils, and complexion can be obtained.

[0216] The microphone 86 can capture the user's voice. Voiceprint information that can be used for voiceprint authentication can be obtained from the captured voice information. Furthermore, voice information can be captured periodically and changes in voice quality can be monitored, which can be used for health management. Of course, the microphone 86, camera 84, and speaker can also be used to make video calls with a doctor at a medical institution 87.

[0217] By using the device shown in FIG. 21A and the portable data terminal 89 shown in FIG. 21C, it is possible to realize a remote medical support system in which information is sent from a remote location to a doctor in a hospital and the patient receives medical treatment from the doctor.

[0218] This embodiment mode can be implemented in appropriate combination with other embodiment modes. [Example]

[0219] In this example, a secondary battery having an underlayer and a cap layer according to one embodiment of the present invention and a secondary battery having no underlayer or cap layer as a comparative example were fabricated, and the charge / discharge characteristics and cycle characteristics were evaluated.

[0220] <Preparation of secondary battery> Sample 1, an embodiment of the present invention, was prepared as follows. First, a titanium sheet was used to serve as both the substrate and the positive electrode current collector layer. The titanium sheet was a rolled foil with a thickness of 0.1 mm, purity of 99.5%, etched, and non-mirror finish, cut to 12 mm diameter.

[0221] A titanium nitride (TiN) film was formed as an undercoat film on the titanium sheet by sputtering under the following conditions: Target: Titanium target, diameter 100mm Sputtering power supply, output: DC power supply, 500W Atmosphere: Argon flow rate 12.0 sccm, nitrogen flow rate 28 sccm, pressure 0.4 Pa Film formation time: 8 minutes Film formation temperature: set to 600°C Film formation rate: 2.5 nm / min

[0222] Next, a 1000 nm thick film of lithium cobalt oxide (LiCoO2) was formed as a positive electrode active material layer by sputtering under the following sputtering conditions. Target: Lithium cobalt oxide target, diameter 100 mm Sputtering power supply, output: RF power supply, 500W Atmosphere: Argon flow rate 40sccm, oxygen flow rate 10sccm, pressure 0.4Pa Film formation time: 461 minutes Film formation temperature: set to 600°C Film formation rate: 2.2 nm / min

[0223] Next, titanium oxide (TiO) was deposited as a cap layer. x ) was deposited to a thickness of approximately 20 nm by sputtering under the following sputtering conditions. Target: Titanium target, diameter 100mm Sputtering power supply, output: DC power supply, 500W Atmosphere: Argon flow rate 24sccm, oxygen flow rate 16sccm, pressure 0.4Pa Film formation time: 27.7 minutes Film formation temperature: Set to 600°C (actual substrate temperature is about 400°C) Film formation rate: 0.72 nm / min

[0224] Sample 2 has no undercoat film, and sample 3 has titanium oxide (TiO x ) was formed on the substrate, and Sample 3 was fabricated. These were fabricated in the same manner as Sample 1 except for the undercoat film.

[0225] Furthermore, as comparative examples, Samples 4 to 6, which do not have a cap layer, were fabricated in the same manner as Samples 1 to 3, except that no cap layer was formed.

[0226] Table 2 shows the preparation conditions for each sample.

[0227] [Table 2]

[0228] <Battery cell production> Next, each sample was used as a positive electrode to fabricate a CR2032 type coin-type battery cell (diameter 20 mm, height 3.2 mm).

[0229] The counter electrode was made of lithium metal.

[0230] The electrolyte used in the electrolytic solution was 1 mol / L lithium hexafluorophosphate (LiPF6), and the electrolytic solution was a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) at a volume ratio of EC:DEC = 3:7. For the secondary batteries used to evaluate the charge / discharge efficiency, 2 wt% vinylene carbonate (VC) was added to the electrolytic solution.

[0231] The separator was made of polypropylene with a thickness of 25 μm.

[0232] The positive electrode can and the negative electrode can were made of stainless steel (SUS).

[0233] <Charge / discharge efficiency measurement> The initial characteristics were measured by charging at CCCV, 0.2 C, 4.2 V, and a cutoff current of 0.1 C. The discharge was performed at CC, 0.2 C, and a cutoff voltage of 2.5 V. Here, 1 C represents a current value per weight of positive electrode active material of 137 mA / g. The measurement temperature was 25°C. The results of measuring the initial characteristics are shown in Table 3 and Figures 22A and 22B. Figure 22A is a graph of Samples 1 to 3, and Figure 22B is a graph of Samples 4 to 6.

[0234] [Table 3]

[0235] It is clear from Table 3 and FIGS. 22A and 22B that all the samples exhibited good charge-discharge characteristics.

[0236] <Charge / discharge cycle characteristics> Next, the charge / discharge cycle characteristics of these battery cells were evaluated. Charge / discharge cycle characteristics were measured in the same manner as in the measurement of initial characteristics. The results of the cycle characteristics are shown in Figures 23A and 23B. Figure 23A is a graph of Samples 1 to 3, and Figure 23B is a graph of Samples 4 to 6.

[0237] 23A and 23B, Samples 1 to 3, which had a cap layer, exhibited significantly better cycle characteristics than Samples 4 to 6, which did not have a cap layer. Sample 1, which had titanium nitride as an underlayer, exhibited the best characteristics, with a discharge capacity of 115 mAh / g and a discharge capacity retention rate of 93% after 25 cycles. Sample 3, which had titanium oxide as an underlayer, exhibited characteristics second only to Sample 1, with a discharge capacity of 113 mAh / g and a discharge capacity retention rate of 93% after 25 cycles. Sample 2, which did not have an underlayer, exhibited a discharge capacity of 111 mAh / g and a discharge capacity retention rate of 92% after 25 cycles.

[0238] Therefore, it was revealed that the provision of a capping layer can produce a secondary battery with good charge-discharge cycle characteristics. It was also revealed that the charge-discharge cycle characteristics are better with an underlayer than without an underlayer, and that titanium nitride is particularly preferable. [Example]

[0239] In this example, a secondary battery having a cap layer according to one embodiment of the present invention and a secondary battery having no cap layer as a comparative example were fabricated, and their characteristics were analyzed by TEM, electron energy loss spectroscopy (EELS), electron microbeam diffraction, impedance measurement, and the like, and their cycle characteristics were evaluated.

[0240] <Preparation of secondary battery> Sample 11, which is one embodiment of the present invention, was prepared as follows: First, a 100 μm titanium sheet was used as both the substrate and the positive electrode current collector layer.

[0241] A titanium nitride (TiN) film was formed as an undercoat film on the titanium sheet by sputtering under the following conditions: Target: Titanium target, 2 inch diameter Sputtering power supply, output: RF power supply, 100W Atmosphere: Argon flow rate 3.0 sccm, nitrogen flow rate 7 sccm, pressure 0.5 Pa Film formation time: 15 minutes Film formation temperature: set to 600°C Target-substrate distance: 75mm

[0242] Next, a 900 nm thick film of lithium cobalt oxide (LiCoO2) was formed as a positive electrode active material layer by sputtering under the following sputtering conditions. Target: Lithium cobalt oxide target, 2 inches diameter Sputtering power supply, output: RF power supply, 200W Atmosphere: Argon flow rate 10sccm, pressure 0.5Pa Film formation time: 109 minutes Film formation temperature: set to 600°C Target-substrate distance: 75mm Film formation rate: 9.2 nm / min

[0243] Next, a 20 nm film of titanium oxide (TiO2) was formed as a cap layer by sputtering under the following sputtering conditions. Target: Titanium target, diameter 100mm Sputtering power supply, output: DC power supply, 500W Atmosphere: Argon flow rate 24sccm, oxygen flow rate 16sccm, pressure 0.4Pa Film formation time: 27.7 minutes Film formation temperature: Set to 600°C (actual substrate temperature is about 400°C) Film formation rate: 0.72 nm / min

[0244] As a comparative example, Sample 12 was prepared without a cap layer. Sample 12 was prepared in the same manner as Sample 11 except for the cap layer.

[0245] The preparation conditions for each sample are shown in Table 4.

[0246] [Table 4]

[0247] <tem> The TEM imaging conditions were as follows: Sample pretreatment: Thin sectioning using FIB (μ-sampling) Transmission electron microscope: JEOL JEM-ARM200F Observation conditions: Accelerating voltage: 200 kV Magnification accuracy: ±3%

[0248] Figure 24 shows a cross-sectional TEM image of Sample 11 before charge and discharge. A titanium oxide cap layer 1102 was observed in the surface layer. Figure 27 shows a cross-sectional TEM image of Sample 11 after charge and discharge. A titanium oxide cap layer 1102 was observed in the surface layer. Figure 30 shows a cross-sectional TEM image of Sample 12 after charge and discharge. In both samples, the positive electrode active material layer 1101 of lithium cobalt oxide was polycrystalline, and it was observed that the crystallites were in the shape of long columns.

[0249] <eels> Next, the electronic state of cobalt was analyzed using EELS for the sample after charging and discharging, and the valence was calculated from the L3 / L2 ratio with reference to Non-Patent Document 1. The EELS measurement conditions were as follows. Elemental analysis (point analysis) Scanning transmission electron microscope: JEOL JEM-ARM200F Accelerating voltage: 200 kV Beam diameter: approx. 0.1 nmφ Elemental analyzer: Gatan Quantum ER Electron spectrometer: MOS detector array Capture time: 30 seconds

[0250] The EELS analysis points for Sample 11 after charge and discharge are indicated by *1 and *2 in Figure 28A, and *3, *4, and *5 in Figure 28B. *1 and *2 are approximately 100 nm deep from the outermost surface of the lithium cobalt oxide layer toward the substrate. *3 to *5 are also approximately 30 nm deep. All of the analysis points are at or near grain boundaries, but *2, *4, and *5 are deeper inside the crystal grains than *1 and *3. Figure 28B is an enlarged image of the portion of photo.3-14 circled in white in Figure 27.

[0251] Figure 29 shows the EELS spectra of sample 11 at the locations indicated by *1 to *5. The figure also shows the EEL spectrum, where the background calculated from the lower binding energy side than the Co-L3edge is subtracted (Background subtracted EEL spectrum), and the spectrum of the cobalt L3 and L2 levels continuum (Co-L2,3 continuum subtracted spectrum), where the background calculated from the energy band between the Co-L3edge and Co-L2edge is further subtracted. The background subtracted EEL spectrum was obtained by subtracting the background from the original data using a power law model. The Co-L2,3 continuum subtracted spectrum was also obtained by further subtracting the cobalt scattering cross section model (Hartree-Slater cross section model) from the data after background subtraction using the power law fitting. The L3 / L2 area intensity ratio and the calculated cobalt valence are shown in Table 5.

[0252] [Table 5]

[0253] Figures 31A and 31B are cross-sectional TEM images of Sample 12 after charge and discharge. The EELS analysis locations are indicated by *1 and *2 in Figure 31A and *3, *4, and *5 in Figure 18B. All analysis locations are grain boundaries or their vicinity, but *2, *4, and *5 are located further inside the crystal grains than *1 and *3. Figure 31B is an enlarged image of the portion of photo.2-16 circled in white in Figure 30.

[0254] EELS spectra of Sample 12 at points *1 to *5 after charge and discharge are similarly shown in Figure 32. Table 6 shows the L3 / L2 area intensity ratio and the calculated cobalt valence.

[0255] [Table 6]

[0256] Tables 5 and 6 show that the reduction of cobalt inside the crystal grains tends to be more suppressed in Sample 11 with the cap layer, suggesting that the provision of a cap layer can suppress the deterioration of the layered rock-salt crystal structure.

[0257] <Microelectron diffraction> Next, the crystal structure of the lithium cobalt oxide at and near the grain boundaries was analyzed using ultrafine electron diffraction.

[0258] Figure 25A is a cross-sectional TEM image of Sample 11 before charge and discharge. The analysis points of the electron microbeam diffraction are indicated by *point1-1, *point1-2, and *point1-3 in Figure 25A. Note that Figure 25A is an enlarged image of the portion of photo.1-7 surrounded by a black line in Figure 24.

[0259] Figure 25B shows the microelectron diffraction image of *point1-1. The transmitted light is designated O, and some of the diffraction spots are designated 1, 2, and 3. Analysis of *point1-1 revealed that the interplanar spacing of 1 was 0.137 nm, that of 2 was 0.143 nm, and that of 3 was 0.464 nm. The plane angles were ∠1O2 = 17°, ∠1O3 = 107°, and ∠2O3 = 90°. The electron beam incident direction was

[0120] . Based on the interplanar spacing and plane angles, 1 was determined to be -213, 2 was similarly -210, and 3 was similarly 00-3, indicating a layered rock-salt crystal structure. The lattice constants of *point1-1 were calculated from these d values ​​to be a = 2.86 (Å) and c = 13.9 (Å).

[0260] Figure 26A shows the microelectron diffraction image of *point 1-2. The transmitted light is designated O, and some of the diffraction spots are designated 1, 2, and 3. Analysis of *point 1-2 revealed that the interplanar spacing of 1 was 0.137 nm, that of 2 was 0.143 nm, and that of 3 was 0.464 nm. The plane angles were ∠1O2 = 17°, ∠1O3 = 107°, and ∠2O3 = 90°. The electron beam incident direction was

[0120] . Based on the interplanar spacing and plane angles, 1 was determined to be -213, 2 was similarly -210, and 3 was similarly 00-3, indicating a layered rock-salt crystal structure. The lattice constants of *point 1-2 were calculated from these d values ​​to be a = 2.86 (Å) and c = 13.9 (Å).

[0261] Figure 26B shows the microelectron diffraction image of *points 1-3. The transmitted light is designated O, and some of the diffraction spots are designated 1, 2, and 3. Analysis of *points 1-3 revealed that the interplanar spacing of 1 was 0.146 nm, that of 2 was 0.139 nm, and that of 3 was 0.463 nm. The plane angles were ∠1O2 = 17°, ∠1O3 = 90°, and ∠2O3 = 72°. The electron beam incident direction was

[0120] . Based on the interplanar spacing and plane angles, 1 was determined to be -210, 2 was similarly -21-3, and 3 was similarly 00-3, suggesting a layered rock-salt crystal structure. The lattice constants of *points 1-3 were calculated from these d values ​​to be a = 2.92 (Å) and c = 13.9 (Å).

[0262] Fig. 33A is a cross-sectional TEM image of Sample 11 after charge and discharge. The analysis points of the electron microbeam diffraction are indicated by *point3-1, *point3-2, and *point3-3 in Fig. 33A.

[0263] Figure 33B shows the microelectron diffraction image of *point3-1. The transmitted light is designated O, and some of the diffraction spots are designated 1, 2, and 3. Analysis of *point3-1 revealed that the interplanar spacings of 1, 2, and 3 were 0.227 nm, 0.183 nm, and 0.475 nm, respectively. The plane angles were ∠1O2 = 21°, ∠1O3 = 71°, and ∠2O3 = 50°. The incident direction of the electron beam was [0-10]. Based on the interplanar spacings and plane angles, 1 was determined to be 10-2, 2 was determined to be 10-5, and 3 was determined to be 00-3, indicating a layered rock-salt crystal structure. The lattice constants of *point3-1 were calculated from these d values ​​to be a = 2.76 (Å) and c = 14.2 (Å).

[0264] Figure 34A shows the microelectron diffraction image of *point3-2. The transmitted light is designated O, and some of the diffraction spots are designated 1, 2, and 3. Analysis of *point3-2 revealed that the interplanar spacings of 1, 2, and 3 were 0.226 nm, 0.181 nm, and 0.468 nm, respectively. The plane angles were ∠1O2 = 22°, ∠1O3 = 71°, and ∠2O3 = 49°. The incident direction of the electron beam was [0-10]. 1 was at -102, 2 was at -105, and 3 was at 003, indicating a layered rock-salt crystal structure. The lattice constants of *point3-2 were calculated from these d values ​​to be a = 2.74 (Å) and c = 14.1 (Å).

[0265] Figure 34B shows an ultrafine electron diffraction image of *point3-3. The transmitted light is designated as O, and a portion of the diffraction spot is designated as 1, which is shown in the figure. When *point3-3 was analyzed, the interplanar spacing of 1 was calculated to be 0.470 nm. The incident direction of the electron beam was

[0003] , and 1 is the 003 of a layered rock salt crystal, suggesting a layered rock salt crystal structure. The lattice constant of *point3-3 was calculated from this d value to be c = 14.0 (Å). The a-axis was not calculated because there was no corresponding d value.

[0266] Figure 35A is a cross-sectional TEM image of Sample 12 after charge and discharge. The analysis points of the electron microbeam diffraction are indicated by *point2-1, *point2-2, and *point2-3 in Figure 35A.

[0267] Figure 35B shows the electron microbeam diffraction image of *point2-1. The transmitted light is designated O, and some of the diffraction spots are designated 1, 2, and 3. Analysis of *point2-1 revealed that the interplanar spacings of 1, 2, and 3 were 0.125 nm, 0.115 nm, and 0.234 nm, respectively. The plane angles were ∠1O2 = 29°, ∠1O3 = 96°, and ∠2O3 = 66°. The incident direction of the electron beam was

[0010] . 1 was 20-1, a layered rock-salt crystal, while 2 was 205 and 3 was 006. This suggests a layered rock-salt crystal structure. From these d values, the lattice constants of *point2-1 were calculated to be a = 2.91 (Å) and c = 14.1 (Å).

[0268] Figure 36A shows the electron microbeam diffraction image of *point2-2. The transmitted light is designated O, and some of the diffraction spots are designated 1, 2, and 3. Analysis of *point2-2 revealed that the interplanar spacings of 1, 2, and 3 were 0.126 nm, 0.115 nm, and 0.234 nm, respectively. The plane angles were ∠1O2 = 29°, ∠1O3 = 95°, and ∠2O3 = 66°. The incident direction of the electron beam was

[0010] . 1 was 20-1, 2 was 205, and 3 was 006, suggesting a layered rock-salt crystal structure. From these d values, the lattice constants of *point2-2 were calculated to be a = 2.91 (Å) and c = 14.1 (Å).

[0269] Figure 36B shows an ultrafine electron diffraction image of *point 2-3. The transmitted light is designated as O, and a portion of the diffraction spot is designated as 1, which is shown in the figure. Analysis of *point 2-3 revealed that the interplanar spacing of 1 was calculated to be 0.474 nm. The incident direction of the electron beam was

[0003] , and 1 is the 003 of a layered rock salt crystal, suggesting a layered rock salt crystal structure. Calculating the lattice constant of *point 2-3 from this d value gave c = 14.21 (Å). The a-axis was not calculated because there was no corresponding d value.

[0270] As described above, the lattice constant of Sample 11 without a cap layer after charging and discharging tended to be larger than the lattice constant of lithium cobalt oxide before charging and discharging. This is presumably due to the reduction of cobalt.

[0271] On the other hand, Sample 12, which has a cap layer, tends to have a small a-axis on average even after charge and discharge, which indicates that the valence of cobalt is large and the reduction of cobalt is suppressed.

[0272] <Charge / discharge cycle> Next, secondary batteries were fabricated using Samples 11 and 12, and the charge-discharge cycle characteristics were evaluated.

[0273] Using Sample 11 and Sample 12 as the positive electrode and lithium metal as the counter electrode, a CR2032 type coin-type battery cell (diameter 20 mm, height 3.2 mm) was fabricated.

[0274] The electrolyte used in the electrolytic solution was 1 mol / L lithium hexafluorophosphate (LiPF6), and the electrolytic solution was a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) in a volume ratio of EC:DEC = 3:7, to which 2 wt% vinylene carbonate (VC) was added as an additive.

[0275] The separator was made of polypropylene with a thickness of 25 μm.

[0276] The positive electrode can and the negative electrode can were made of stainless steel (SUS).

[0277] The cycle test was carried out under the following conditions: the charging voltage was 4.2 V; the measurement temperature was 25°C; charging was CC / CV (0.2 C, 0.1 C cut), discharging was CC (0.1 C, 2.5 V cut), and a 10-minute rest period was provided before the next charge. In this example, 1 C was 137 mA / g.

[0278] The results of the charge-discharge cycle test are shown in Figure 37. Compared with Sample 12 without a cap layer, the positive electrode of Sample 11 with a cap layer exhibited extremely good charge-discharge cycle characteristics.

[0279] <Impedance> During the charge-discharge cycle test, the impedance of the secondary battery was measured.

[0280] In this example, electrochemical phenomena occurring in a secondary battery of one embodiment of the present invention are analyzed by replacing the phenomenon with an equivalent circuit as shown in FIG. 38A.

[0281] Here, Rs is the electrical resistance of the electrode and the resistance of the electrolyte. The electrical resistance of the electrode includes all the simple electrical resistances contained in the coin cell. The resistance of the electrolyte is the resistance of ion diffusion in the solution.

[0282] R1, sometimes referred to as Rf or Rsurface, is the high-frequency component of the impedance of a secondary battery. R1 includes the resistance of lithium ion diffusion at the interface between the positive electrode and the electrolyte.

[0283] CPE1 (constant phase element, electric double layer capacitance) is a capacitance that reproduces the behavior of porous electrodes.

[0284] R2, sometimes referred to as Rct, is a low-frequency component. R2 includes the resistance of the charge transfer process in which Li ions are inserted into and removed from the positive electrode active material layer (LiCoO2 in this example).

[0285] Ws1 is the resistance associated with lithium diffusion in the solid.

[0286] The impedance is typically plotted as shown in Figure 38B, which shows the range of influence of each component.

[0287] The impedance of Sample 11 is shown in Figure 39, and the impedance of Sample 12 is shown in Figure 40. These graphs show the results after the second and 50th cycles, respectively. The measurement was performed using a Solartron CELLTEST multi-channel electrochemical measurement system, sweeping an AC voltage of 10 mV from 0.001 Hz to 1 MHz. The measurement temperature was 25°C. Prior to impedance measurement, the batteries were charged to 4.2 V at 0.2 C and left for two hours. The OCVs of Sample 11 after two cycles and Sample 12 after 50 cycles were 4.1308 V and 4.0607 V, respectively. Sample 12 after two cycles and Sample 12 after 50 cycles were 4.1162 V and 4.0005 V, respectively.

[0288] As shown in Figure 40, when comparing the impedance between the 2nd and 50th cycles in Sample 12, R1 (high-frequency component) is particularly increased. This suggests that degradation has occurred in the lithium diffusion pathways, for example, at the interface between the positive electrode active material layer and the electrolyte solution, and at some grain boundaries, and that this is the cause of the deterioration in charge-discharge cycle characteristics shown in Figure 37.

[0289] On the other hand, as shown in Figure 39, when comparing the impedance of Sample 11 between the 2nd and 50th cycles, the increase in R1 is relatively small. This suggests that the cap layer is effective in suppressing the formation of a coating. Furthermore, R2 (low-frequency components) increases significantly. This suggests that the crystal structure of LiCoO2 is deteriorating. [Explanation of symbols]

[0290] 100: positive electrode, 101: positive electrode active material layer, 102: cap layer, 103: positive electrode current collector, 104: underlayer, 110: substrate, 111: substrate, 200: secondary battery, 201: secondary battery, 202: secondary battery, 203: solid electrolyte layer, 204: negative electrode active material layer, 205: negative electrode current collector, 206: protective layer, 209: cap layer, 210: negative electrode, 211: negative electrode, 212: negative electrode, 213: solid electrolyte layer, 214: underlayer, 215: positive electrode current collector, 220: separator, 221: electrolyte, 222: exterior body, 223a: lead electrode, 223b: lead electrode, 230: secondary battery, 231: secondary battery< / eels> < / tem>

Claims

[Claim 1] A secondary battery having a positive electrode, a solid electrolyte, and a negative electrode, The positive electrode is a base film, a positive electrode active material layer, and a cap layer; at least one of the underlayer and the cap layer is a titanium compound; the titanium compound is titanium oxide partially substituted with nitrogen, titanium nitride partially substituted with oxygen, or titanium oxynitride; the positive electrode active material layer contains lithium cobalt oxide, The secondary battery, wherein the solid electrolyte contains titanium.

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