Positive electrode for secondary battery, secondary battery, electronic device and system

Abstract

Provided is a positive electrode that is for secondary batteries and that has excellent cycle characteristics. This positive electrode for secondary batteries has a positive electrode collector layer, an underlying film, a positive electrode active material layer, and a cap layer, wherein the underlying film includes titanium nitride, the positive electrode active material layer includes lithium cobalt oxide, and the cap layer includes titanium oxide. The application of titanium nitride to the underlying film ensures sufficient conductivity, and inhibits oxidation of the positive electrode collector layer and diffusion of metal atoms. In addition, by applying titanium oxide to the cap layer, it is possible to improve cycle characteristics through inhibition of collapse of the crystal structure of the electrode active material and side reactions between the positive electrode active material layer and electrolytes.

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 an electro-optical device having a power storage device, an information terminal device having a power storage device, and the like are all classified as electronic devices. [Background technology]

[0003] In recent years, various types of power storage devices have been actively developed, such as lithium-ion secondary batteries, lithium-ion capacitors, air batteries, all-solid-state batteries, etc. In particular, the demand for high-output, high-capacity lithium-ion secondary batteries has rapidly expanded in line with the development of the semiconductor industry, and they have become indispensable in the modern information society as a rechargeable energy source.

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

[0005] In addition, the development of all-solid-state batteries, which are safer than lithium-ion secondary batteries, 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] JP 2018-206747 A [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] There is still room for improvement in various aspects of thin-film secondary batteries, such as charge / discharge characteristics, cycle characteristics, reliability, safety, and cost. For example, with regard to cycle characteristics, the crystal structure of the positive electrode active material may be destroyed as charging and discharging are repeated, which may lead to a decrease in charge / discharge capacity. In addition, side reactions may 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, which may also lead 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 a side reaction is 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 when charging and discharging are repeated. Another object is to provide a positive electrode for a secondary battery in which a crystal structure is unlikely to be destroyed even when charging and discharging are repeated. Another object is to provide a positive electrode for a secondary battery having excellent charge and discharge cycle characteristics. Another object is to provide a positive electrode for a secondary battery having 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 a charge and discharge cycle is suppressed. Another object is to provide a secondary battery having excellent charge and discharge cycle characteristics. Another object is to provide a secondary battery having 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 it is possible to extract problems other than these from the description of the specification, drawings, and claims. [Means for solving the problem]

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

[0013] One embodiment of the present invention is a positive electrode for a secondary battery, the positive electrode having an undercoat film, a positive electrode active material layer, and a cap layer, in which at least one of the undercoat film 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, both the undercoat film and the positive electrode active material layer preferably 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. Effect of the Invention

[0019] According to one embodiment of the present invention, a secondary battery positive electrode 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, etc., even after repeated charging and discharging can be provided. A secondary battery positive electrode that is less likely to lose its crystal structure even after repeated charging and discharging can be provided. A secondary battery positive electrode with excellent charge and discharge cycle characteristics can be provided. A secondary battery positive electrode with large charge and discharge capacity can be provided. A secondary battery positive electrode in which the 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 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 effects other than these from the description in the specification, drawings, claims, etc. [Brief description of the drawings]

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

[0023] Hereinafter, the 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 easily understood by those skilled in the art that the form and details of the present invention can be modified in various ways. Furthermore, the present invention is not to be interpreted as being limited to the description of the embodiments shown below.

[0024] Additionally, 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 parentheses are not used. In crystallography, crystal planes, directions, and space groups are represented by adding a superscript bar to the numbers, but in this specification and elsewhere, due to restrictions on notation in applications, the numbers may be represented by adding a - (minus sign) before them instead of adding 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 deficiencies of cations or anions may be present. Strictly speaking, the layered rock-salt type crystal structure may have a structure in which the lattice of the rock-salt type crystal is distorted.

[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 acceptable for there to be a deficiency of cations or anions.

[0027] Layered rock salt type crystals and anions in 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 match. However, since the space group of layered rock salt type crystals is R-3m, which is different from the space group of rock salt type 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 match 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 crystal orientation of the two regions can roughly match up from TEM (transmission electron microscope), STEM (scanning transmission electron microscope), HAADF-STEM (high-angle annular dark-field scanning transmission electron microscope), ABF-STEM (annular bright-field scanning transmission electron microscope) images, etc. X-ray diffraction (XRD), electron diffraction, neutron diffraction, etc. can also be used to make the determination. When the crystal orientation roughly matches up, it can be observed in a TEM image, etc. that the difference in the direction of the linear rows of alternating cations and anions is 5 degrees or less, or 2.5 degrees or less. Note that light elements such as oxygen and fluorine may not be clearly observed in a TEM image, etc., in which case the match in the orientation 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 lithium that can be inserted and removed from the positive electrode active material is removed. 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 and the like, the term "parallel to each other" means not only when the planes are mathematically strictly parallel, but also when the angle formed by the planes is 5° or less, or 2.5° or less.

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

[0033] FIG. 1A is a perspective view of an example of a positive electrode 100 according to one aspect of the present invention. The positive electrode 100 includes a positive electrode current collector 103, an underlayer film 104, a positive electrode active material layer 101, and a cap layer 102.

[0034] The underlayer film 104 is provided between the positive electrode current collector 103 and the positive electrode active material layer 101. The underlayer film 104 has a function of enhancing the conductivity between the positive electrode current collector 103 and the positive electrode active material layer 101. Alternatively, it 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, it has a function of stabilizing the crystal structure of the positive electrode active material layer 101.

[0035] As the underlayer film 104, it is preferable to use a material having conductivity. Also, it is preferable to use a material that is easily resistant to 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 N y , 0 < x < 2, 0 < y < 1) etc. can be applied. Among them, titanium nitride is particularly preferable because it has high conductivity and a high function of suppressing oxidation.

[0036] The cap layer 102 is provided on the positive electrode active material layer 101. The cap layer 102 has a function of suppressing side reactions between the positive electrode active material layer 101 and the electrolyte. Alternatively, 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 , 0 < x < 2, 0 < y < 1) is preferred. 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 solid electrolytes, but also electrolytic solutions in which a lithium salt is dissolved in a liquid solvent and electrolytic solutions in which a lithium salt is dissolved in a gel-like compound.

[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] As the transition metal M included in the positive electrode active material layer 101, it is preferable to use a metal that can form a layered rock salt-type composite oxide belonging to the space group R-3m together with lithium. As the transition metal M, for example, one or more of manganese, cobalt, and nickel can be used. That is, only cobalt can be used as the transition metal included in the positive electrode active material layer 101, only nickel can be used, two types of cobalt and manganese, or two types of cobalt and nickel can be used, or three types of cobalt, manganese, and nickel can be used. That is, the positive electrode active material layer 101 can have a composite oxide containing lithium and transition metal M, such as lithium cobaltate, lithium nickelate, lithium cobaltate in which part of cobalt is substituted with manganese, lithium cobaltate in which part of cobalt is substituted with nickel, lithium nickel-manganese-cobaltate, etc.

[0041] In addition to the above, the positive electrode active material layer 101 may contain elements other than the transition metal M, such as magnesium, fluorine, and aluminum. 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, lithium nickel-cobalt-aluminate, lithium nickel-cobalt-aluminate, lithium nickel-cobalt-aluminate to which magnesium and fluorine have been added, or the like.

[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, when the atomic ratio of cobalt contained in the positive electrode active material layer 101 is 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, when the atomic ratio of cobalt contained in the positive electrode active material layer 101 is taken as 100. The atomic ratio of magnesium is preferably, for example, 0.1 to 6, and more preferably 0.3 to 3. 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 in the above-mentioned concentrations, a stable crystal structure can be maintained even when charging and discharging are repeated at a high voltage, and thus the positive electrode active material layer 101 can be provided with a high capacity and excellent charge-discharge cycle characteristics.

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

[0045] <First principles calculation> Here, the results of calculations of the crystal structure of the interface between the positive electrode active material layer 101 and the undercoat 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 is a diagram showing the case where titanium nitride is used as the undercoat film 104. Calculations were performed assuming that titanium nitride has a rock-salt crystal structure belonging to the space group Fm-3m, and lithium cobalt oxide has a layered rock-salt crystal structure belonging to the space group R-3m. The titanium nitride and lithium cobalt oxide are laminated so that their (111) planes are parallel to each other.

[0047] 2B is a diagram showing the case where titanium oxide is used as the undercoat film 104. Calculations were performed assuming that titanium oxide has a rutile crystal structure belonging to the space group P42 / mnm, and lithium cobalt oxide has a layered rock-salt crystal structure belonging to the space group R-3m. The (100) plane of titanium oxide and the (001) plane of lithium cobalt oxide are laminated in parallel.

[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 in which titanium nitride was used as the undercoat film 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 on which only anions are arranged are parallel to the (111) plane. In titanium nitride, only nitrogen atoms are arranged on the planes parallel to the (111) plane. In layered rock-salt crystal structures belonging to the space group R-3m, the planes on which only anions are arranged are parallel to the (001) plane. In lithium cobalt oxide, only oxygen atoms are arranged on the planes 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 in which only anions are arranged are parallel to each other, which tends to stabilize the crystal structure.

[0053] In addition, both the rock-salt type crystal structure belonging to the space group Fm-3m and the layered rock-salt type 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 type crystal structure is laminated on titanium nitride having a rock-salt type crystal structure, the crystal orientation of the undercoat film 104 and the positive electrode active material layer 101 tends to roughly match.

[0054] On the other hand, in the case of FIG. 2B where titanium oxide was used as the undercoat film 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 function of stabilizing 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 manner, titanium nitride is particularly suitable for the undercoat film 104 .

[0056] 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 positive electrode 100 does not include the base film 104, the positive electrode 100 may have a secondary battery with sufficiently improved cycle characteristics by including the cap layer 102.

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

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

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

[0060] [Secondary battery configuration] FIG. 3A is a diagram illustrating an example of a stacked structure of a secondary battery 200 including a positive electrode for a secondary battery 100 according to one embodiment of the present invention.

[0061] The secondary battery 200 is a thin-film battery, and has the positive electrode 100 described in the previous embodiment, a solid electrolyte layer 203 formed on the positive electrode 100, and a negative electrode 212 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. In addition, as shown in FIG. 3A, the negative electrode 212 preferably has a base film 214 and a cap layer 209.

[0062] The base film 214 is provided between the negative electrode current collector 205 and the negative electrode active material layer 204. The base film 214 has a function of increasing electrical conductivity between the negative electrode current collector 205 and the negative electrode active material layer 204, a function of suppressing excessive expansion of the negative electrode active material layer, or a function of suppressing a side reaction between the negative electrode current collector 205 and the negative electrode active material layer 204.

[0063] As the underlying film 214, it is preferable to use a material having conductivity. It is also preferable to use a material that can suppress excessive expansion of the negative electrode active material layer. It is also preferable to use a material that can easily 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) are preferably used. 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] As the cap layer 209, it is preferable to use titanium or a titanium compound. 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 , 0 < x < 2, 0 < y < 1) are preferably used. 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. Materials that alloy with lithium such as tin, gallium, and aluminum can also be used. Metal oxides obtained by alloying these can also be used. Lithium titanate (Li4Ti5O 12 , LiTi2O4, etc.) can also be used, but among them, materials containing silicon and oxygen (SiO xIt is preferable to use (also referred to as a film). Further, lithium metal may be used as the negative electrode active material layer 204. A mixture of these materials may also be used. For example, a mixture of silicon particles and carbon is suitable because it has good reliability and a 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, a sputtering method, an evaporation method, etc. can be used.

[0068] It is preferable to use a titanium-containing compound 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, the 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) as the negative electrode active material layer 204 may be acceptable. In this case, SiO CIt is preferable that the ratio of silicon to oxygen (O / Si) is higher in the solid electrolyte layer 203. With this configuration, conductive ions (particularly lithium ions) are easily diffused in the solid electrolyte layer 203, and conductive ions (particularly lithium ions) are easily desorbed or accumulated in the negative electrode active material layer 204, so that a solid secondary battery with good characteristics can be obtained. As described above, by using materials consisting of the same components for the solid electrolyte layer 203 and the negative electrode active material layer 204, a secondary battery can be easily manufactured.

[0070] The solid electrolyte layer 203 may have a laminated structure. In the case of the laminated structure, one layer is made of a material in which nitrogen is added to lithium phosphate (Li3PO4) (Li3PO (4-Z) N Z : Also called LiPON) may be laminated. Note that Z>0.

[0071] As shown in FIG. 3B, the secondary battery 200 may have a negative electrode 212 in which a plurality of negative electrode active material layers 204 and cap layers 209 are laminated. By laminating a plurality of negative electrode active material layers 204 and cap layers 209, it is possible to improve the capacity and suppress excessive expansion of the negative electrode 212. In this case, the cap layer 209 in contact with the solid electrolyte layer 203 and the cap layer 209 sandwiched between the negative electrode 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 negative electrode active material layers 204.

[0072] Furthermore, as shown in FIG. 3C, a secondary battery 200 may be provided having a positive electrode 100 in which a plurality of positive electrode active material layers 101 and cap layers 102 are laminated. By laminating a plurality of positive electrode active material layers 101 and cap layers 102, it is possible to improve the capacity while suppressing the collapse of the crystal structure of the positive electrode active material layer 101. In this case, the cap layer 102 in contact with the solid electrolyte layer 203 and the cap layer 102 sandwiched between the positive electrode 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 positive electrode 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, a 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. The secondary battery 200 is a thin-film battery, and as shown in Fig. 4B, the positive electrode 100 described in the previous embodiment is formed on the substrate 110, a solid electrolyte layer 203 is formed on the positive electrode 100, and a negative electrode 210 is formed on the solid electrolyte layer 203. The negative electrode 210 has a negative electrode current collector 205, a base film 214, a negative electrode active material layer 204, and a cap layer 209.

[0075] In addition, in the secondary battery 200 , a protective layer 206 is preferably 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 a metal mask. The positive electrode 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 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 and a metal mask.

[0077] 4A, a negative electrode terminal portion and a positive electrode terminal portion are formed by exposing a part of the negative electrode current collector 205 and a part of the positive electrode current collector 103. The area other than the negative electrode terminal portion and the positive electrode terminal portion is 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 FIG. 4A and FIG. 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 undercoat film 104 between the positive electrode current collector 103 and the positive electrode active material layer 101. Also, the secondary battery 200 may have a negative electrode 210 without an undercoat film 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, the 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 obtained with simplified manufacturing process and high productivity. In addition, a secondary battery with high energy density can be obtained.

[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 laminated 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, the secondary battery in which not only the positive electrode but also the solid electrolyte layer and the negative electrode are formed as thin films has been described, but an embodiment of the present invention is not limited thereto. An embodiment of the present invention may be a secondary battery having an electrolytic solution. Alternatively, the secondary battery may be a secondary battery having an electrolytic solution and a negative electrode that serves both as a negative electrode current collector layer and a negative electrode active material layer. Alternatively, the secondary battery may be a secondary battery having a negative electrode prepared by coating a powdered negative electrode active material on a negative electrode current collector.

[0084] A secondary battery 230 having an electrolyte 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. Parts of lead electrodes 223a and 223b are drawn out to the outside 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] As shown in Fig. 7B, the secondary battery 231 includes the positive electrode 100, the negative electrode 211 serving both as the negative electrode current collector layer and the negative electrode active material layer, a separator 220, an electrolyte 221, and an exterior body 222. By using the negative electrode 211 serving both as the negative electrode current collector layer and the negative electrode active material layer, the process can be simplified and a secondary battery with high productivity can be obtained. 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 producing the secondary battery 200 shown in FIGS. 4A and 4B will be described with reference to FIG.

[0090] First, the positive electrode current collector 103 is formed on the substrate 110 (S1). As a film formation method, a sputtering method, a vapor deposition method, or the like can be used. A conductive substrate may be used as the current collector. As the positive electrode current collector 103, a material having high conductivity, such as a metal such as gold, platinum, aluminum, titanium, copper, magnesium, iron, cobalt, nickel, zinc, germanium, indium, silver, or palladium, or an alloy thereof, can be used. Also, aluminum to which an element that improves heat resistance, such as silicon, titanium, neodymium, scandium, or molybdenum, is added, can be used. Also, the positive electrode current collector 103 may be formed 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 suppresses the oxidation of the positive electrode current collector 103 by oxygen contained in the positive electrode active material layer 101 or the like, or the diffusion of metal atoms. Therefore, even a material that is easily oxidized or a material that contains easily diffused metal atoms can be used for the positive electrode current collector 103.

[0093] Next, the undercoat film 104 is formed (S2). The undercoat film 104 can be formed by sputtering, vapor deposition, or the like. For example, when titanium nitride is used as the undercoat 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 a sputtering method using a sputtering target mainly composed of an oxide containing lithium and one or more of manganese, cobalt, and nickel. For example, a sputtering target mainly composed of lithium cobalt oxide (LiCoO2, LiCo2O4, etc.), a sputtering target mainly composed of lithium manganese oxide (LiMnO2, LiMn2O4, etc.), or a sputtering target mainly composed of lithium nickel oxide (LiNiO2, LiNi2O4, etc.) can be used. Alternatively, the layer may be formed by a vacuum deposition method.

[0095] In addition, in the sputtering method, the positive electrode active material layer 101 can be selectively formed 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 a film is formed using a sputtering target mainly composed of an oxide containing lithium and one or more of manganese, cobalt, and nickel, magnesium, fluorine, aluminum, etc. may be formed by vacuum deposition 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 production 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 manufactured by using a material containing titanium for the solid electrolyte layer 203. As a film formation method, a sputtering method, a vapor deposition method, or the like can be used.

[0101] Next, the negative electrode active material layer 204 is formed (S6) on the solid electrolyte layer 203. 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. The film formation method may be a sputtering method, a vapor deposition method, or the like. In the sputtering method, a film can be selectively formed by using a metal mask. The conductive film may be patterned by selectively removing the conductive film by dry etching or wet etching using a resist mask or the like.

[0103] In addition, when the positive electrode current collector 103 or the negative electrode current collector 205 is formed by a sputtering method, 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 a sputtering method. The sputtering device can perform continuous film formation in the same chamber or using multiple chambers, and can also be a multi-chamber type manufacturing device or an in-line type manufacturing device. The sputtering method is a manufacturing method suitable for mass production using a chamber and a sputtering target. In addition, the sputtering method can be formed thinly 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). As the protective layer 206, a metal oxide containing one or more elements selected from hafnium, aluminum, gallium, yttrium, zirconium, tungsten, titanium, tantalum, nickel, germanium, neodymium, lanthanum, magnesium, etc. can be used. Silicon oxynitride or silicon nitride can also be used. The protective layer 206 can be formed by using a sputtering method.

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

[0106] Through the above process, the secondary battery 200 which is 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. In the second embodiment, an example of a secondary battery having one cell is shown, but in the present embodiment, an example of a thin-film secondary battery having a plurality of cells connected in series is shown.

[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. In Fig. 9A and Fig. 9B, the same reference numerals are used for the same parts as Fig. 5A shown in the second embodiment.

[0110] Fig. 9A shows the state immediately after the deposition of the negative electrode current collector 205. The shape of the top surface of the negative electrode current collector 205 is different from that of Fig. 5A. The 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 in contact 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] (Embodiment 4) 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. In the second embodiment, an example of a secondary battery that is a single-layer cell is shown, but in the present embodiment, an example of a thin-film battery that is a multi-layer cell is shown.

[0115] Fig. 10 shows an example of a cross section of a thin-film battery with a three-layer cell. 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 constitute 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 undercoat 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 laminate shown in Fig. 10 is configured to be connected in series to increase capacity, but it can also be connected in parallel with external wiring. Also, series and parallel or series-parallel can be selected with external wiring.

[0119] It is preferable to use the same material for solid electrolyte layer 203, the second solid electrolyte layer, and the third solid electrolyte layer, since 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 process from the positive electrode current collector layer to the negative electrode current collector layer of a secondary battery is shown in Fig. 12 and Fig. 13. The manufacturing apparatus can be suitably used for manufacturing a 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 use of each chamber, and examples of the exhaust mechanism 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 turbo molecular pump and a cold trap.

[0128] The procedure for forming a film on a substrate involves placing a substrate 850 or a substrate cassette in a load lock chamber 870 and transporting the substrate 850 or a substrate cassette 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 set in advance and 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 provided in 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 apply a voltage to the sputtering target by switching between an RF power supply and a pulse DC power supply. 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 provided in the first film formation chamber 892, and it is also possible to form a film while heating the substrate to a heater temperature of 700°C.

[0130] A negative electrode active material layer can be formed by sputtering using a single crystal silicon target. Also, a reactive sputtering method using Ar gas and O2 gas can be used to form a SiO XThe film formed by sputtering may be used as the negative electrode active material layer. A silicon nitride film formed by reactive sputtering using Ar gas and N2 gas can also be used as a sealing film. A positive electrode active material layer can be formed by sputtering using a sputtering target mainly composed of 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 formed by reactive sputtering using Ar gas and N2 gas can also be used to form a cap layer or undercoat film.

[0131] When forming a positive electrode active material layer, the mask and the substrate are stacked and transported from the second transport chamber 872 to the first film formation chamber 892 by the substrate transport mechanism 853, 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 a LRTA (Lamp Rapid Thermal Anneal) device can be used. The heating treatment in the heating chamber 893 can be performed under an atmosphere of nitrogen, oxygen, 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 the alignment is completed, the substrate and mask are transferred to the first transfer chamber 871 by the substrate transfer mechanism 852. The substrate is transported by the lift mechanism of the first transfer chamber 871, and the gate 884 is opened, and the substrate is transported to the third transfer chamber 873 by the substrate transfer mechanism 854.

[0133] The second film formation chamber 874 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 cut 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, and can simultaneously vaporize and deposit a plurality of substances by moving the evaporation sources from a plurality of material supply chambers, that is, co-evaporation. FIG. 13 shows an evaporation source having an evaporation boat 858 also 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 procedure for performing deposition, first, the substrate is placed on the substrate holder 845. The substrate holder 845 is connected to a rotation mechanism 865. Then, the first deposition material 855 is heated to a certain degree in the first material supply chamber 895, and when the deposition rate becomes stable, the gate 888 is opened, and the arm 862 is extended to move the deposition source 856 and stop it at a position below the substrate. The deposition source 856 is composed of the first deposition material 855, a heater 857, and a container for storing the first deposition material 855. Also, the second deposition material is heated to a certain degree in the second material supply chamber 894, and when the deposition rate becomes stable, the gate 886 is opened, and the arm 861 is extended to move the deposition source and stop it at a position below the substrate.

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

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

[0139] Moreover, 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 substrate surface 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 becomes stable, 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 is shown for the deposition source 856, an EB (Electron Beam) deposition type may be used. Although an example of a crucible is shown as a container for the deposition source 856, an deposition boat may be used. An organic material is placed as a first deposition material 855 in the crucible heated by a heater 857. When pellets or particulate SiO are used as the deposition material, a deposition boat 858 is used. The deposition boat 858 is made up of three parts, a member having a concave surface, an inner lid with two holes, and an upper lid with one hole are stacked on top of each other. The inner lid may be removed for deposition. The deposition boat 858 acts as a resistor when electricity is applied, and the deposition boat itself is heated.

[0143] Further, although the present embodiment shows an example of a multi-chamber system, the present invention is not particularly limited, 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] (Embodiment 6) 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. A secondary battery 913 has 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. In addition, since the secondary battery can be an all-solid-state secondary battery, it is also excellent in safety. Thus, the secondary battery of one embodiment of the present invention can be suitably used as the secondary battery 913.

[0147] Fig. 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. A terminal 971 and a terminal 972 are electrically connected to the circuit 912. The circuit 912 is electrically connected to a terminal 911.

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

[0149] The layer 916 has a function of shielding, for example, an electromagnetic field caused 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. In addition, the battery control circuit can be wound around the secondary battery as shown in Fig. 15D 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 the substrate 900 to fit the shape of the secondary battery 913 and arranging the battery control circuit around the secondary battery, the battery control circuit can be wound around the secondary battery as shown in Fig. 15D. By using a secondary battery with such a configuration, a smaller secondary battery can be obtained.

[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 Fig. 16A, Fig. 16B, and Fig. 17A to Fig. 17C. The secondary battery of one embodiment of the present invention has high discharge capacity, high cycle characteristics, and high safety. Therefore, the electronic device is 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 as an example of an application device using the thin-film secondary battery according to the present invention. Electric power obtained by power supply from radio waves 3005 can be charged into thin-film secondary battery 3001. An antenna and IC 3004, and thin-film secondary battery 3001 are arranged inside IC card 3000. An ID 3002 and a photo 3003 of a worker who wears the management badge are displayed on IC card 3000. A signal such as an authentication signal can also be transmitted from the antenna using the power charged in thin-film secondary battery 3001.

[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 preferable.

[0161] A solar cell may be provided in place of the photograph 3003. When exposed to external light, the light is absorbed, electricity is generated, and the thin-film secondary battery 3001 can be charged with the electricity.

[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 mounted on vehicles, as a secondary battery for MEMS devices, and the like.

[0163] FIG. 17A shows an example of a wearable device. A wearable device may use a secondary battery as a power source. In addition, when a user uses the device in daily life or outdoors, in order to improve splash-proof performance, water resistance, or dust-proof performance, a wearable device that can be charged wirelessly as well as charged by a wire with an exposed connector is desired.

[0164] For example, the secondary battery according to one embodiment of the present invention can be mounted on a glasses-type device 400 as shown in FIG. 17A. The glasses-type device 400 has a frame 400a and a display unit 400b. By mounting a secondary battery on the temples of the curved frame 400a, the glasses-type device 400 can be made lightweight, well-balanced in weight, and capable of long continuous use. By providing the secondary battery according to one embodiment of the present invention, a configuration that can accommodate space saving associated with a smaller housing can be realized.

[0165] Furthermore, the secondary battery according to one embodiment of the present invention can be mounted on the headset type device 401. The headset type device 401 has at least a microphone unit 401a, a flexible pipe 401b, and an earphone unit 401c. The secondary battery can be provided in the flexible pipe 401b or the earphone unit 401c. By providing the secondary battery according to one embodiment of the present invention, a configuration that can accommodate space saving associated with a miniaturized 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 configuration that can accommodate space saving due to miniaturization of the housing can be realized.

[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 configuration that can accommodate space saving due to miniaturization of the housing can be realized.

[0168] Furthermore, the secondary battery according to 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 a secondary battery can be mounted inside the belt portion 406a. By providing the secondary battery according to one embodiment of the present invention, a configuration that can accommodate space saving associated with a miniaturized housing can be realized.

[0169] Furthermore, the secondary battery according to 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 according to one embodiment of the present invention, a configuration that can accommodate space saving due to miniaturization of the housing can be realized.

[0170] Display unit 405a can display not only the time, but also various other information such as incoming e-mails and phone calls.

[0171] In addition, since the wristwatch type device 405 is a wearable device that is directly wrapped around the arm, it may be equipped with sensors that measure the user's pulse, blood pressure, etc. Data on the user's amount of exercise 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 in. 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 having 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 having a positive electrode of one embodiment of the present invention has high discharge capacity and cycle characteristics and is highly safe. Therefore, the secondary battery can be suitably used in the following electronic devices. In particular, the secondary battery can be suitably used in electronic devices that require durability.

[0176] 18A shows a perspective view of a wristwatch-type mobile information terminal (also called a smart watch) 700. The 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 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, for example, via a pin 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 has the secondary battery 750. For the secondary battery 750, for example, the secondary battery described in the previous embodiment can be used. 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 have the function of 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 that connect the band 705A and the housing 701, respectively. In this way, the configuration at the connection portion between the band 705A and the housing 701 can be simplified.

[0180] The secondary battery 750 is flexible. Therefore, the band 705A can be produced by integrally forming it with the secondary battery 750. For example, the band 705A shown in FIG. 18B can be produced by setting the secondary battery 750 in a mold that corresponds to the outer shape of the band 705A, pouring the material of the band 705A into the mold, and hardening the material.

[0181] When a rubber material is used as the material of 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 a program or data recorded in a recording medium and displaying it in a display area, etc.

[0184] The housing 701 may also have a speaker, a sensor (including a function of measuring force, displacement, position, speed, 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, or the like inside the housing 701. 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 provided on the bottom surface.

[0187] For example, the cleaning robot 6300 can analyze an image captured by the camera 6303 and determine the presence or absence of an obstacle such as a wall, furniture, or a step. When an object that may become entangled in the brush 6304, such as a wire, is detected by image analysis, the rotation of the brush 6304 can be stopped. The cleaning robot 6300 includes a secondary battery according to one embodiment of the present invention and a semiconductor device or electronic component therein. By using the secondary battery according to one embodiment of the present invention in the cleaning robot 6300, the cleaning robot 6300 can be an electronic device with long operating time and high reliability.

[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 moving mechanism 6408, a computing device, and the like.

[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 removable information terminal, and by installing it in a fixed position on the robot 6400, charging and data transfer are possible.

[0191] The upper camera 6403 and the lower camera 6406 have a function of capturing images of the surroundings of the robot 6400. In addition, the obstacle sensor 6407 can detect the presence or absence of an obstacle in the moving direction when the robot 6400 moves forward using the moving 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. An aircraft 6500 shown in Fig. 19C has a propeller 6501, a camera 6502, a secondary battery 6503, and the like, and has a 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. The electronic component 6504 can estimate the remaining battery charge from a change in the power storage capacity of the secondary battery 6503. The flying object 6500 includes therein the secondary battery 6503 according to one embodiment of the present invention. 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 has a secondary battery 7161, an engine, tires, brakes, a steering device, a camera, and the like. It is preferable that the automobile 7160 also has a system 1000 described below. The automobile 7160 has a secondary battery 7161 according to one embodiment of the present invention therein. By using a secondary battery according to one embodiment of the present invention in the automobile 7160, the automobile 7160 can have a long driving range, 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. One of the elements is a secondary battery.

[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 utilize the advantages of both a secondary battery having a larger discharge capacity and the thin-film battery described in the previous embodiment, which is easy to make thin and light. The system 1000 preferably includes a wireless power feeder. The wireless power feeder allows easy power feeding from the lithium-ion secondary battery 1002 to the thin-film battery 1001.

[0198] Fig. 20B shows the inside of an automobile 7160 having the system 1000. The automobile 7160 has a secondary battery for driving, 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 secondary battery for driving 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 provided in the 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. In addition, as the secondary battery for driving the automobile 7160, it is preferable to use 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 has at least a biosensor and a solid-state secondary battery that supplies power to the biosensor, and can obtain various types of bioinformation using infrared light and visible light and store the information in a memory. Such bioinformation can be used for both personal authentication of users and health care. The secondary battery of one embodiment of the present invention has high discharge capacity and cycle characteristics, and is also highly safe. 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, and acquires biological information that can be used for healthcare purposes. The biological information includes pulse wave, blood glucose level, oxygen saturation, triglyceride concentration, etc. The data is stored in a memory.

[0203] Furthermore, it is preferable to provide a means for acquiring other biological information in the device described in this embodiment. For example, in addition to internal biological information such as electrocardiogram, blood pressure, and body temperature, there is superficial biological information such as facial expression, complexion, and pupils. Information on the number of steps, exercise intensity, elevation change, and diet (calories ingested, nutrients, etc.) are also important information for health care. Using multiple biological information enables comprehensive health management, which leads not only 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 the 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 relationship between heart rate and blood pressure calculated from an electrocardiogram and pulse wave can also be used to estimate the user's physical condition. 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 continues to have low blood pressure and a high heart rate, this may be a sign of heart disease.

[0205] Users can check their own physical condition estimated based on the biometric information measured by electronic devices at any time, which will improve their health awareness. As a result, they may be prompted to review their daily habits, such as avoiding overeating and drinking, taking appropriate exercise, and managing their physical condition, and may even be prompted to receive a medical examination if necessary.

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

[0207] 21A is premised on being small, generating almost no heat, and causing no allergic reactions even 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 causes no allergic reactions. In addition, it is preferable that the embedded device 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, and a biosensor capable of acquiring other biological data can be used.

[0209] The biosensor 80b built into the device may have a function of storing acquired data in a temporary memory built into the device. Alternatively, each piece of data acquired by the biosensor may be sent wirelessly or wired to a portable data terminal 85 in FIG. 21B, and the portable data terminal 85 may have a function of detecting the waveform. The portable data terminal 85 is a smartphone or the like, and can detect whether a problem such as arrhythmia has occurred from the data acquired by each biosensor. When sending data acquired by a plurality of biosensors to the portable data terminal 85 by wire, it is preferable to transfer the data acquired by the portable data terminal 85 together before connecting by wire. Each piece of detected data may be automatically given a date and stored in the memory of the portable data terminal 85, and managed by an individual. Alternatively, the data may be sent to a medical institution 87 such as a hospital via a network (including the Internet) as shown in FIG. 21B. The data is managed by a data server of the hospital, and can be used as test data during treatment. Since the amount of medical data may be huge, a network including Bluetooth (registered trademark) or a frequency band of 2.4 GHz to 2.4835 GHz may be used from the biosensor 80b to the portable data terminal 85, and a fifth-generation wireless system may be used from the portable data terminal 85 to the portable data terminal 85 for high-speed communication. The fifth-generation wireless system uses frequencies of 3.7 GHz, 4.5 GHz, and 28 GHz. By using the fifth-generation wireless system, data can be acquired and transmitted to a medical institution 87 not only at home but also when going out, and data can be accurately acquired when the user's physical condition is abnormal and can be used for subsequent processing or treatment. The configuration shown in FIG. 21C can be used as the 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 are 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 housing 82, when using 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 a 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] When biosensor 80a is embedded in the user's body as shown in Fig. 21A, this function is unnecessary, but when biosensor 80a is not embedded, the user can obtain an electrocardiogram by holding a pair of electrodes 83 with both hands. Even when biosensor 80a is embedded in the user's body, portable data terminal 89 shown in Fig. 21C can be used to check whether biosensor 80a is functioning normally. Portable data terminal 89 shown in Fig. 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 acquire the user's voice. Voiceprint information that can be used for voiceprint authentication can be acquired from the acquired voice information. In addition, voice information can be acquired periodically and changes in voice quality can be monitored for use in health management. Of course, the microphone 86, camera 84, and speaker can also be used to make a videophone call 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, a remote medical support system can be realized in which information can be sent from a remote location to a doctor in a hospital and the patient can receive medical treatment from the doctor.

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

[0219] EXAMPLES In this example, a secondary battery having an undercoat film and a cap layer according to one embodiment of the present invention and a secondary battery having no undercoat film 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, which is one 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, which was processed to 12 mmφ.

[0221] A titanium nitride (TiN) film was formed as a base film on the titanium sheet by sputtering to a thickness of 20 nm under the following sputtering conditions: Target: Titanium target, diameter 100mm Sputtering power supply, output: DC power supply, 500W Atmosphere: Argon flow rate 12.0sccm, nitrogen flow rate 28sccm, pressure 0.4Pa Film formation time: 8 minutes Film formation temperature: set to 600℃ Deposition rate: 2.5 nm / min

[0222] Next, lithium cobalt oxide (LiCoO2) was sputtered to form a 1000 nm film as a positive electrode active material layer 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℃ Film formation rate: 2.2 nm / min

[0223] Next, titanium dioxide (TiO x The sputtering conditions were as follows: 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) Deposition rate: 0.72 nm / min

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

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

[0226] The preparation conditions for each sample are shown in Table 2.

[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] Lithium metal was used as the counter electrode.

[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 having 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, 0.2C, 4.2V, and a cutoff current of 0.1C. The discharge was performed at CC, 0.2C, and a cutoff voltage of 2.5V. Here, 1C is a current value per weight of the positive electrode active material of 137mA / g. The measurement temperature was 25°C. The results of measuring the initial characteristics are shown in Table 3 and Figs. 22A and 22B. Fig. 22A is a graph of Samples 1 to 3, and Fig. 22B is a graph of Samples 4 to 6.

[0234] [Table 3]

[0235] It is apparent from Table 3 and FIGS. 22A and 22B that all of 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 in measuring the cycle characteristics was performed in the same manner as in measuring the 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 having a cap layer exhibited cycle characteristics significantly better than Samples 4 to 6 having no cap layer. Sample 1 having titanium nitride as an undercoat film 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 having titanium oxide as an undercoat film 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 having no undercoat film exhibited a discharge capacity of 111 mAh / g and a discharge capacity retention rate of 92% after 25 cycles.

[0238] Therefore, it was found that the provision of a capping layer enables the fabrication of a secondary battery with good charge-discharge cycle characteristics. It was also found that the charge-discharge cycle characteristics are better in the case of having an underlayer than in the case of not having an underlayer, and that titanium nitride is particularly preferable. EXAMPLES

[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), ultrafine electron beam 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 a base film on the titanium sheet by sputtering to a thickness of 20 nm under the following sputtering conditions: Target: Titanium target, 2 inch diameter Sputtering power supply, output: RF power supply, 100W Atmosphere: Argon flow rate 3.0sccm, nitrogen flow rate 7sccm, pressure 0.5Pa Film formation time: 15 minutes Film formation temperature: set to 600℃ Target-substrate distance: 75mm

[0242] Next, lithium cobalt oxide (LiCoO2) was sputtered to form a 900 nm film as a positive electrode active material layer under the following sputtering conditions. Target: Lithium cobalt oxide target, 2 inch 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℃ Target-substrate distance: 75mm Deposition rate: 9.2 nm / min

[0243] Next, a titanium oxide (TiO2) film was formed as a cap layer to a thickness of 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) Deposition rate: 0.72 nm / min

[0244] Sample 12 was prepared as a comparative example without a cap layer, and 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 method (μ-sampling method) Transmission electron microscope: JEOL JEM-ARM200F Observation conditions Acceleration voltage: 200 kV Magnification accuracy: ±3%

[0248] Fig. 24 shows a cross-sectional TEM image of Sample 11 before charging and discharging. A titanium oxide cap layer 1102 was observed on the surface layer. Fig. 27 shows a cross-sectional TEM image of Sample 11 after charging and discharging. A titanium oxide cap layer 1102 was observed on the surface layer. Fig. 30 shows a cross-sectional TEM image of Sample 12 after charging and discharging. In both samples, it was observed that the positive electrode active material layer 1101 of lithium cobalt oxide was polycrystalline, with the crystallites being vertically 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 Acceleration 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 of sample 11 after charging and discharging are shown as *1 and *2 in Figure 28A, and *3, *4, and *5 in Figure 28B. *1 and *2 are about 100 nm deep from the outermost surface of the lithium cobalt oxide layer toward the substrate. *3 to *5 are also about 30 nm deep. All of the analysis points are grain boundaries or their vicinity, but *2, *4, and *5 are further inside the crystal grains than *1 and *3. Figure 28B is an enlarged image of the part of photo.3-14 surrounded by a white line in Figure 27.

[0251] Figure 29 shows the EELS spectrum of sample 11 at the points indicated by *1 to *5. The figure shows the EEL spectrum from which the background calculated from the lower binding energy side than Co-L3edge is subtracted (Background subtracted EEL spectrum), and the spectrum of the L3 and L2 levels of cobalt from which the background calculated from the energy band between Co-L3edge and Co-L2edge is further subtracted (Co-L2,3 continuum subtracted spectrum). The background subtracted EEL spectrum was obtained by fitting the original data with a power law model to subtract the background. The Co-L2,3 continuum subtracted spectrum was obtained by further subtracting the cobalt scattering cross section model (Hartree-Slater cross section model) from the data from which the background was removed by 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 charging and discharging. The EELS analysis points are indicated by *1 and *2 in Figure 31A, and *3, *4, and *5 in Figure 18B. All analysis points 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 part of photo.2-16 surrounded by a white line in Figure 30.

[0254] EELS spectra of the sample 12 at points *1 to *5 after charging and discharging are similarly shown in Fig. 32. The L3 / L2 area intensity ratio and the calculated cobalt valence are shown in Table 6.

[0255] [Table 6]

[0256] Tables 5 and 6 show that the reduction of cobalt inside the crystal grains tends to be suppressed in Sample 11 with the cap layer. This suggests 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 grain boundaries and their vicinity in the lithium cobalt oxide was analyzed using ultra-microelectron diffraction.

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

[0259] Figure 25B shows the ultrafine electron beam diffraction image of the *point1-1 part. The transmitted light is O, and some of the diffraction spots are indicated as 1, 2, and 3 in the figure. Analysis of the *point1-1 part showed 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°. At this time, the electron beam incidence direction was

[0120] , and from the interplanar spacing and plane angle, 1 was -213 of the layered rock salt type crystal, 2 was -210, and 3 was 00-3, which was considered to have a layered rock salt type crystal structure. The lattice constants of the *point1-1 part were calculated from these d values ​​to be a=2.86(Å) and c=13.9(Å).

[0260] Figure 26A shows the ultrafine electron beam diffraction image of the *point1-2 part. The transmitted light is O, and some of the diffraction spots are indicated as 1, 2, and 3 in the figure. When the *point1-2 part was analyzed, the interplanar spacing of 1 was calculated to be 0.137 nm, the interplanar spacing of 2 was 0.143 nm, and the interplanar spacing of 3 was 0.464 nm. The plane angles were ∠1O2=17°, ∠1O3=107°, and ∠2O3=90°. At this time, the electron beam incidence direction was

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

[0261] Figure 26B shows the ultrafine electron beam diffraction image of the *point1-3 part. The transmitted light is O, and some of the diffraction spots are indicated as 1, 2, and 3 in the figure. When the *point1-3 part was analyzed, the interplanar spacing of 1 was calculated to be 0.146 nm, the interplanar spacing of 2 was 0.139 nm, and the interplanar spacing of 3 was 0.463 nm. The plane angles were ∠1O2=17°, ∠1O3=90°, and ∠2O3=72°. At this time, the electron beam incidence direction was

[0120] , and from the interplanar spacing and plane angle, 1 was -210 of the layered rock salt type crystal, 2 was similarly -21-3, and 3 was similarly 00-3, and it was considered to have a layered rock salt type crystal structure. The lattice constants of the *point1-3 part 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 charging and discharging. 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 ultrafine electron diffraction image of *point3-1. The transmitted light is O, and some of the diffraction spots are indicated as 1, 2, and 3 in the figure. Analysis of *point3-1 revealed that the interplanar spacing of 1 was 0.227 nm, that of 2 was 0.183 nm, and that of 3 was 0.475 nm. The plane angles were ∠1O2=21°, ∠1O3=71°, and ∠2O3=50°. The electron beam incident direction was [0-10], and from the interplanar spacing and plane angle, 1 was 10-2 of a layered rock salt crystal, 2 was 10-5, and 3 was 00-3, which was considered to have 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 ultrafine electron diffraction image of *point3-2. The transmitted light is O, and some of the diffraction spots are indicated as 1, 2, and 3 in the figure. Analysis of *point3-2 showed that the interplanar spacing of 1 was 0.226 nm, that of 2 was 0.181 nm, and that of 3 was 0.468 nm. The plane angles were ∠1O2=22°, ∠1O3=71°, and ∠2O3=49°. The electron beam incident direction was [0-10], and 1 was -102 of the layered rock salt crystal, 2 was -105, and 3 was 003, which suggested that the crystal structure had a layered rock salt 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 a microelectron beam 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. At this time, the direction of incidence of the electron beam was

[0003] , and 1 was 003 of the layered rock salt crystal, and it was thought to have 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] Fig. 35A is a cross-sectional TEM image of Sample 12 after charging and discharging. The analysis points of the electron microbeam diffraction are indicated by *point2-1, *point2-2, and *point2-3 in Fig. 35A.

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

[0010] , and 1 was 20-1 of a layered rock salt crystal, 2 was 205, and 3 was 006, so it was considered to have 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 ultrafine electron beam diffraction image of *point2-2. The transmitted light is O, and some of the diffraction spots are indicated as 1, 2, and 3 in the figure. Analysis of *point2-2 showed that the interplanar spacing of 1 was 0.126 nm, that of 2 was 0.115 nm, and that of 3 was 0.234 nm. The plane angles were ∠1O2=29°, ∠1O3=95°, and ∠2O3=66°. The electron beam incident direction was

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

[0269] Figure 36B shows a micro-diffraction image of *point2-3. 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 *point2-3 was analyzed, the interplanar spacing of 1 was calculated to be 0.474 nm. At this time, the direction of incidence of the electron beam was

[0003] , and 1 was 003 of the layered rock salt crystal, and it was thought to have a layered rock salt crystal structure. The lattice constant of *point2-3 was calculated from this d value to be 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 the cap layer after charging and discharging tended to be larger than the lattice constant of lithium cobalt oxide before charging and discharging, which is presumably due to the reduction of cobalt.

[0271] On the other hand, in Sample 12 having a cap layer, the a-axis tended to be small on average even after charging and discharging, indicating that the valence of cobalt was large and the reduction of cobalt was suppressed.

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

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

[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 having 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. The charging was CC / CV (0.2 C, 0.1 C cut), and the discharging was CC (0.1 C, 2.5 V cut), with a 10-minute rest period before the next charging. In this embodiment, 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 having 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, an electrochemical phenomenon occurring in a secondary battery of one embodiment of the present invention is analyzed by replacing the phenomenon with an equivalent circuit as shown in FIG. 38A.

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

[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 embodiment).

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

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

[0287] The impedance of Sample 11 is shown in FIG. 39, and the impedance of Sample 12 is shown in FIG. 40. The graphs are for the 2nd and 50th cycles, respectively. The measurement device used was a Solartron CELLTEST multi-channel electrochemical measurement system, and an AC voltage of 10 mV was swept from 0.001 Hz to 1 MHz. The measurement temperature was 25°C. Before impedance measurement, the battery was charged to 4.2 V at 0.2 C and left for 2 hours. The OCVs of Sample 11 after 2 cycles and Sample 12 after 50 cycles were 4.1308 V and 4.0607 V, respectively. The OCVs of Sample 12 after 2 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 at the 2nd cycle and the 50th cycle in Sample 12, R1 (high frequency component) is particularly increased. Therefore, it is presumed that degradation occurs in the lithium diffusion path, for example, at the interface between the positive electrode active material layer and the electrolyte solution, and at some crystal grain boundaries, etc., which is the cause of the deterioration of the charge-discharge cycle characteristics as shown in Figure 37.

[0289] On the other hand, as shown in Figure 39, in sample 11, the increase in R1 is relatively small when comparing the impedance at the 2nd and 50th cycles. Therefore, it is inferred that the formation of the coating is suppressed by the effect of the cap layer. In addition, R2 (low frequency component) increases significantly. Therefore, it is inferred that the crystal structure of LiCoO2 is degraded. [Explanation of symbols]

[0290] 100: positive electrode, 101: positive electrode active material layer, 102: cap layer, 103: positive electrode current collector, 104: undercoat film, 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: undercoat film, 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

1. A positive electrode for a secondary battery, The cathode has an undercoat film, a positive electrode active material layer, and a cap layer, At least one of the undercoat film 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 for a secondary battery, wherein the positive electrode active material layer contains lithium cobalt oxide.

2. In claim 1, a crystal structure of the undercoat film and a crystal structure of the positive electrode active material layer each having a surface on which only anions are arranged;

3. In claim 1 or 2, The positive electrode for a secondary battery, wherein both the undercoat film and the positive electrode active material layer have a crystal structure in which cations and anions are arranged alternately.

4. A secondary battery comprising the positive electrode for secondary batteries according to any one of claims 1 to 3, a solid electrolyte, and a negative electrode.

5. An electronic device comprising the secondary battery according to claim 4.

6. The secondary battery according to claim 4 ; a lithium ion secondary battery having a positive electrode, a negative electrode, an electrolyte, and a separator; A system having