Secondary battery

Abstract

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

Description

Technical Field

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

[0002] Note that in this specification, the electronic device refers to all devices having a power storage device, and all electro-optical devices having a power storage device, information terminal devices having a power storage device, etc. are electronic devices.

Background Art

[0003] In recent years, the development of various power storage devices such as lithium-ion secondary batteries, lithium-ion capacitors, air batteries, and all-solid-state batteries has been actively carried out. In particular, the lithium-ion secondary battery, which has high output and high capacity, has rapidly expanded its demand along with the development of the semiconductor industry and has become indispensable in modern information society as a source of rechargeable energy.

[0004] Along with the expansion of demand, a lithium-ion secondary battery with higher performance has been required. Therefore, the improvement of the positive electrode active material aiming at increasing the capacity and improving the cycle characteristics of the lithium-ion secondary battery has been progressing (for example, Patent Document 1).

[0005] In addition, the development of a safer all-solid-state battery among lithium-ion secondary batteries has been promoted. A thin-film secondary battery in which the positive electrode, electrolyte, and negative electrode are formed by PVD (physical vapor deposition), CVD (chemical vapor deposition), etc. is also a kind of all-solid-state battery (for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Non-Patent Literature

[0007]

Non-Patent Literature 1

Summary of the Invention

Problems 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, or cost. For example, regarding the cycle characteristics, as charge-discharge is repeated, the crystal structure of the positive electrode active material may collapse, which may lead to a decrease in the charge-discharge capacity. In addition, side reactions may occur at the interface between the positive electrode active material and the electrolyte, the interface between the positive electrode active material and the positive electrode current collector, etc., which may also lead to a decrease in the charge-discharge capacity.

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

[0010] Alternatively, one aspect of the present invention aims to provide a novel substance, an active material particle, a power storage device, or a method for producing them.

[0011] Note that the description of these problems does not preclude the existence of other problems. One aspect of the present invention does not necessarily have to solve all of these problems. It is possible to extract other problems from the descriptions in the specification, drawings, and claims.

Means for Solving the Problems

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

[0013] One aspect of the present invention is a positive electrode for a secondary battery, which has a base film, a positive electrode active material layer, and a cap layer, at least one of the base film and the cap layer has titanium oxynitride, the positive electrode active material layer has lithium cobaltate, and the cap layer has a titanium compound containing oxygen.

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

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

[0016] One aspect of the present invention is a secondary battery having the above positive electrode for a secondary battery, a solid electrolyte, and a negative electrode.

[0017] One aspect of the present invention is an electronic device having the above secondary battery.

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

Advantages of the Invention

[0019] According to one aspect of the present invention, it is possible to provide a positive electrode for a secondary battery in which side reactions hardly occur at the interface between the positive electrode active material and the electrolyte, the interface between the positive electrode active material and the positive electrode current collector, etc., even when charge and discharge are repeated. It is possible to provide a positive electrode for a secondary battery in which the crystal structure is hardly broken even when charge and discharge are repeated. In addition, it is possible to provide a positive electrode for a secondary battery having excellent charge and discharge cycle characteristics. In addition, it is possible to provide a positive electrode for a secondary battery having a large charge and discharge capacity. In addition, it is possible to provide a positive electrode for a secondary battery in which a decrease in capacity during charge and discharge cycles is suppressed. In addition, it is possible to provide a secondary battery having excellent charge and discharge cycle characteristics. In addition, it is possible to provide a secondary battery having a large charge and discharge capacity. In addition, it is possible to provide a secondary battery with high safety or reliability.

[0020] According to one aspect of the present invention, it is possible to provide a novel substance, active material particles, a power storage device, or a method for producing them.

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

Brief Description of the Drawings

[0022]

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MODE FOR CARRYING OUT THE INVENTION

[0023] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it is easily understood by those skilled in the art that its form and details can be variously changed. Further, the present invention is not construed as being limited to the description content of the embodiments shown below.

[0024] In addition, in this specification and the like, Miller indices are used for the notation of crystal planes and directions. Individual planes indicating crystal planes are represented by ( ). Directions are represented by [ ]. The same indices are used for reciprocal lattice points, but parentheses are not attached. In crystallography, the notation of crystal planes, directions, and space groups is represented by a bar above the number, but in this specification and the like, due to the constraints of the application notation, instead of attaching a bar above the number, a - (minus sign) may be attached before the number for expression.

[0025] In this specification and the like, the layered rock salt-type crystal structure of the 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, enabling two-dimensional diffusion of lithium. Note that there may be defects such as deficiencies of cations or anions. Also, strictly speaking, the layered rock salt-type crystal structure may be a structure in which the lattice of the rock salt-type crystal is distorted.

[0026] Also, in this specification and the like, the rock salt-type crystal structure refers to a structure in which cations and anions are alternately arranged. Note that there may be deficiencies of cations or anions.

[0027] The anions of the layered rock salt-type crystal and the rock salt-type crystal adopt a cubic close-packed structure (face-centered cubic lattice structure). When these are in contact, there is a crystal plane where the cubic close-packed structures composed of anions match. However, since the space group of the layered rock salt-type crystal is R-3m, which is different from the space group Fm-3m of the rock salt-type crystal, the Miller indices of the crystal planes satisfying the above conditions are different for the layered rock salt-type crystal and the rock salt-type crystal. In this specification, in the case of the layered rock salt-type crystal and the rock salt-type crystal, when the cubic close-packed structures composed of anions match, it may be said that the crystal orientations are approximately the same.

[0028] The approximate coincidence of the crystal orientations of two regions can be determined from TEM (transmission electron microscope) images, STEM (scanning transmission electron microscope) images, HAADF-STEM (high-angle annular dark-field scanning transmission electron microscope) images, ABF-STEM (annular bright-field scanning transmission electron microscope) images, etc. X-ray diffraction (XRD), electron diffraction, neutron diffraction, etc. can also be used as materials for determination. When the crystal orientations are approximately the same, in TEM images etc., it can be observed that the difference in the direction of the rows in which cations and anions are alternately arranged linearly is 5 degrees or less, or 2.5 degrees or less. Note that in TEM images etc., light elements such as oxygen and fluorine may not be clearly observable, but in that case, the coincidence of the orientation can be determined from the arrangement of metal elements.

[0029] In this specification and the like, the theoretical capacity of the positive electrode active material refers to the amount of electricity when all the insertable and removable lithium in the positive electrode active material has been removed. For example, the theoretical capacity of LiCoO 2 is 274 mAh / g, and the theoretical capacity of LiNiO 2 is 274 mAh / g. The theoretical capacity of LiMn 2 O 4 is 148 mAh / g.

[0030] In this specification and the like, the state where all the insertable and removable lithium is inserted is defined as a charge depth of 0, and the state where all the insertable and removable lithium in the positive electrode active material has been removed is defined as a charge depth of 1.

[0031] In this specification and the like, when two surfaces are parallel, it means not only when they are mathematically strictly parallel, but also when the angle formed by the two surfaces is 5° or less, or 2.5° or less.

[0032] (Embodiment 1) Using FIG. 1, the 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 the 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 underlying film 104, it is preferable to use a material having conductivity. It is also preferable to use a material that is easily resistant to oxidation. 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), 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 the side reaction between the positive electrode active material layer 101 and the electrolyte. Or it has a function of stabilizing the crystal structure of the positive electrode active material layer 101.

[0037] As the cap layer 102, it is preferable to use a titanium compound. 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 preferably used. 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 may be used as the transition metal included in the positive electrode active material layer 101, only nickel may be used, two types of cobalt and manganese, or two types of cobalt and nickel may be used, or three types of cobalt, manganese, and nickel may be used. That is, the positive electrode active material layer 101 can have a composite oxide containing lithium and the transition metal M, such as lithium cobaltate, lithium nickelate, lithium cobaltate in which a part of cobalt is substituted with manganese, lithium cobaltate in which a part of cobalt is substituted with nickel, and lithium nickel-manganese-cobaltate.

[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 stabilize the crystal structure of the positive electrode active material layer 101. That is, the positive electrode active material layer 101 can have lithium cobaltate added with magnesium and fluorine, lithium nickel-cobaltate added with magnesium and fluorine, lithium cobalt-aluminate added with magnesium and fluorine, lithium nickel-cobalt-aluminate, lithium nickel-cobalt-aluminate added with magnesium and fluorine, and the like.

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

[0043] By having nickel, aluminum, and magnesium at the above concentrations, a stable crystal structure can be maintained even when charging and discharging are repeated at high voltages. Therefore, a positive electrode active material layer 101 with high capacity and excellent charge-discharge cycle characteristics can be obtained.

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

[0045] <First-principles calculation> Here, the results of calculating the crystal structure at the interface between the positive electrode active material layer 101 and the base film 104 when lithium cobaltate is used for the positive electrode active material layer 101 will be described with reference to FIG. 2.

[0046] Figure 2A is a diagram when titanium nitride is applied as the underlayer film 104. It is calculated that titanium nitride has a rock-salt type crystal structure belonging to the space group Fm-3m, and lithium cobaltate has a layered rock-salt type crystal structure belonging to the space group R-3m. The (111) plane of titanium nitride and the (001) plane of lithium cobaltate are laminated so as to be parallel.

[0047] Figure 2B is a diagram when titanium oxide is applied as the underlayer film 104. It is calculated that titanium oxide has a rutile type crystal structure belonging to the space group P42 / mnm, and lithium cobaltate has a layered rock-salt type crystal structure belonging to the space group R-3m. The (100) plane of titanium oxide and the (001) plane of lithium cobaltate are laminated so as to be parallel.

[0048] All figures show an excerpt of the interface between the positive electrode active material layer 101 and the underlayer film 104. Other calculation conditions are shown in Table 1.

[0049]

Table 1

[0050] In the case of Figure 2A where titanium nitride is applied as the underlayer film 104, the Ti-O distance is 2.03 Å, the Ti-N distance is 1.93 Å, the Co-O distance is 2.25 Å, and the Co-N distance is 2.21 Å. Note that 1 Å = 10 -10 m.

[0051] In the rock-salt type crystal structure belonging to the space group Fm-3m, the plane where only anions are arranged exists in a plane parallel to the (111) plane. In titanium nitride, only nitrogen atoms are arranged in a plane parallel to the (111) plane. In the layered rock-salt type crystal structure belonging to the space group R-3m, the plane where only anions are arranged exists in a plane parallel to the (001) plane. In lithium cobaltate, only oxygen atoms are arranged in a plane parallel to the (001) plane.

[0052] When the (111) plane of titanium nitride is parallel to the (001) plane of lithium cobalt oxide, the planes where only anions are arranged in both become parallel, and the crystal structure tends to be stable.

[0053] Also, 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 can be said to be crystal structures in which cations and anions are alternately arranged. 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 orientations of the base film 104 and the positive electrode active material layer 101 tend to be substantially the same.

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

[0055] Thus, when lithium cobalt oxide having a layered rock-salt type crystal structure is used for the positive electrode active material layer 101, titanium nitride is particularly suitable as the base film 104.

[0056] FIG. 1B is a perspective view of another example of the positive electrode 100 according to one aspect of the present invention. The positive electrode 100 shown in FIG. 1B has a positive electrode current collector 103, a positive electrode active material layer 101, and a cap layer 102. Thus, the positive electrode 100 does not necessarily have to have the base film 104. Even without the base film 104, a secondary battery with sufficiently improved cycle characteristics can be obtained by having the cap layer 102 in some cases.

[0057] In FIGS. 1A and 1B, the positive electrode current collector 103 that also functions as a current collector and a substrate has been described, but one aspect of the present invention is not limited to this. FIG. 1C is a perspective view of another example of the positive electrode 100 according to one aspect of the present invention. As shown in FIG. 1C, the positive electrode 100 may be fabricated by forming a positive electrode current collector 103, a base film 104, a positive electrode active material layer 101, and a cap layer 102 on a substrate 110.

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

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

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

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

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

[0063] As the underlayer film 214, it is preferable to use a material having conductivity. Also, it is preferable to use a material that can suppress excessive expansion of the negative electrode active material layer. Also, it is preferable to use a material that is likely to suppress side reactions. For example, titanium compounds such as titanium oxide, titanium nitride, titanium oxide partially substituted with nitrogen, titanium nitride partially substituted with oxygen, or titanium oxynitride (TiO x N y , 0 < x < 2, 0 < y < 1) is 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 , where 0 < x < 2 and 0 < y < 1). Titanium is a material that can be contained in the solid electrolyte. Therefore, titanium and titanium compounds are particularly suitable as the cap layer 209.

[0066] As the negative electrode active material layer 204, silicon, carbon, titanium oxide, vanadium oxide, indium oxide, zinc oxide, tin oxide, nickel oxide, etc. can be used. Also, materials that alloy with lithium such as tin, gallium, aluminum, etc. can be used. Also, these alloyed metal oxides can be used. Also, lithium titanate (Li 4 Ti 5 O 12 , LiTi 2 O 4 , etc.) can be used, but among them, materials containing silicon and oxygen (also referred to as SiO x film) are preferable. Also, lithium metal can be used as the negative electrode active material layer 204. Also, mixtures of these materials can be used. For example, a mixture of silicon particles and carbon is suitable because of its good reliability and relatively high energy density per volume.

[0067] The solid electrolyte layer 203 is provided between the positive electrode 100 and the negative electrode 212. As the material of the solid electrolyte layer 203, Li 0.35 La 0.55 TiO 3 , La (2 / 3-A) Li 3A TiO 3、 Li 3 PO 4、 LixPO (4-B) NB , LiNb (1-A) Ta (A) WO 6 , Li 7 La 3 Zr 2 O 12 , Li (1+A) Al (A) Ti (2-A) (PO 4 ) 3 , Li (1+A) Al (A) Ge (2-A) (PO 4 ) 3 , LiNbO 2 etc. can be mentioned. Note that A > 0 and B > 0. As the film formation method, sputtering method, evaporation method, etc. can be used.

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

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

[0070] Also, the solid electrolyte layer 203 may have a laminated structure. When laminating, lithium phosphate (Li3 PO 4 ) with nitrogen added material (Li 3 PO (4-Z) N Z : also called LiPON) may be laminated. Note that Z > 0.

[0071] Also, as shown in FIG. 3B, a secondary battery 200 having a negative electrode 212 in which a plurality of negative electrode active material layers 204 and cap layers 209 are laminated may be used. By laminating a plurality of negative electrode active material layers 204 and cap layers 209, it is possible to improve the capacity while suppressing excessive expansion of the negative electrode 212. At this time, 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 having a positive electrode 100 in which a plurality of positive electrode active material layers 101 and cap layers 102 are laminated may be used. 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. At this time, 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] FIGS. 4A and 4B show a more specific example of the secondary battery 200 according to one aspect of the present invention. Here, the secondary battery 200 formed on the 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. As shown in FIG. 4B, the positive electrode 100 described in the previous embodiment is formed on the substrate 110, the solid electrolyte layer 203 is formed on the positive electrode 100, and the negative electrode 210 is formed on the solid electrolyte layer 203. The negative electrode 210 includes a negative electrode current collector 205, an underlayer film 214, a negative electrode active material layer 204, and a cap layer 209.

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

[0076] The films forming these layers can be formed using a metal mask, respectively. The positive electrode current collector 103, the underlayer 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 underlayer film 214, and the negative electrode current collector 205 can be selectively formed using a sputtering method. Also, the solid electrolyte layer 203 may be selectively formed by using a co-evaporation method and a metal mask.

[0077] As shown in FIG. 4A, a part of the negative electrode current collector 205 and the positive electrode current collector 103 is exposed to form a negative electrode terminal portion and a positive electrode terminal portion. The regions other than the negative electrode terminal portion and the positive electrode terminal portion are covered with the protective layer 206.

[0078] In FIGS. 4A and 4B, the configuration in which the solid electrolyte layer 203, the negative electrode active material layer 204, and the negative electrode current collector 205 are sequentially stacked on the positive electrode 100 having the positive electrode current collector 103, the underlayer film 104, the positive electrode active material layer 101, and the cap layer 102 has been described. However, one aspect of the present invention is not limited to this.

[0079] As shown in FIG. 4C, the secondary battery 200 may have a positive electrode 100 without the underlayer film 104 between the positive electrode current collector 103 and the positive electrode active material layer 101. Also, the negative electrode 210 may have no underlayer film 214 and cap layer 209.

[0080] Moreover, both the positive electrode and the negative electrode of the secondary battery according to one aspect of the present invention may have a laminated structure of an active material layer and a cap layer. For example, as shown in FIG. 4D, the secondary battery 200 may have a negative electrode 210 in which a plurality of negative electrode active material layers 204 and cap layers 209 are laminated. Further, it may have a positive electrode 100 in which a plurality of positive electrode active material layers 101 and cap layers 102 are laminated.

[0081] Also, as shown in FIGS. 5A and 5B, the secondary battery according to one aspect of the present invention may be a secondary battery 201 having a negative electrode 211 that also serves 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 also serves as a negative electrode current collector layer and a negative electrode active material layer, the process can be simplified and a highly productive secondary battery can be obtained. Also, a secondary battery with a high energy density can be obtained.

[0082] Also, as shown in FIGS. 5C and 5D, the secondary battery according to one aspect 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 C-C' in FIG. 5C.

[0083] Also, in FIGS. 4 and 5, a secondary battery in which not only the positive electrode but also the solid electrolyte layer and the negative electrode are formed of thin films has been described, but one aspect of the present invention is not limited to this. One aspect of the present invention may be a secondary battery having an electrolytic solution. Also, it may be a secondary battery having an electrolytic solution and a negative electrode that also serves as a negative electrode current collector layer and a negative electrode active material layer. Also, it may be a secondary battery having a negative electrode produced by coating a powder negative electrode active material on a negative electrode current collector.

[0084] A secondary battery 230 having an electrolytic solution is shown in FIGS. 6A and 6B. FIG. 6A is a top view, and FIG. 6B is a cross-sectional view taken along line D-D' in FIG. 6A.

[0085] As shown in FIG. 6B, the secondary battery 230 includes a positive electrode 100 on a substrate 110, a negative electrode 212 on a substrate 111, a separator 220, an electrolytic solution 221, and an exterior body 222. The negative electrode current collector 205, the negative electrode active material layer 204, and the cap layer 209 included in the negative electrode 212 are formed of thin films.

[0086] Also, as shown in FIG. 6A, the secondary battery 230 includes a lead electrode 223a and a lead electrode 223b. The lead electrode 223a is electrically connected to the positive electrode current collector 103. The lead electrode 223b is electrically connected to the negative electrode current collector 205. A part of the lead electrode 223a and the lead electrode 223b is drawn out of the exterior body 222.

[0087] FIGS. 7A and 7B show a secondary battery 231 having an electrolytic solution and a negative electrode 211 that also serves 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 a positive electrode 100, a negative electrode 211 that also serves as a negative electrode current collector layer and a negative electrode active material layer, a separator 220, an electrolytic solution 221, and an exterior body 222. By using the negative electrode 211 that also serves as a negative electrode current collector layer and a negative electrode active material layer, the process can be simplified to obtain a highly productive secondary battery. Also, a secondary battery with a high energy density can be obtained.

[0089] [Manufacturing Method] Next, an example of the manufacturing process flow of the secondary battery 200 shown in FIGS. 4A and 4B will be described with reference to FIG. 8.

[0090] First, a positive electrode current collector 103 is formed on a substrate 110 (S1). As a film formation method, a sputtering method, an evaporation method, or the like can be used. Also, a conductive substrate may be used as the current collector. As the positive electrode current collector 103, metals such as gold, platinum, aluminum, titanium, copper, magnesium, iron, cobalt, nickel, zinc, germanium, indium, silver, palladium, and alloys thereof, materials with high conductivity can be used. Further, aluminum added with elements such as silicon, titanium, neodymium, scandium, molybdenum to improve heat resistance can be used. Also, it may be formed of a metal element that reacts with silicon to form a silicide. Examples of the metal element that reacts with silicon to form a silicide include zirconium, titanium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, cobalt, nickel, etc.

[0091] Also, as the substrate 110, a ceramic substrate, a glass substrate, a resin substrate, a silicon substrate, a metal substrate, etc. can be used. 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 serve as both the substrate and the positive electrode current collector by using a material with high conductivity. In this case, for example, it is preferable to use a metal substrate such as titanium or copper. Also, when providing an underlayer film 104, the underlayer film 104 prevents the positive electrode current collector 103 from being oxidized by oxygen contained in the positive electrode active material layer 101 or the like, or suppresses the diffusion of metal atoms. Therefore, even a material that is easily oxidized or contains metal atoms that easily diffuse can be applied to the positive electrode current collector 103.

[0093] Next, an underlayer film 104 is formed (S2). As a film formation method for the underlayer film 104, a sputtering method, an evaporation method, or the like can be used. For example, when titanium nitride is used as the underlayer film 104, titanium nitride can be formed by a reactive sputtering method 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, for example, by sputtering 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 (LiCoO 2 2 2 2 4 or the like), a sputtering target mainly composed of lithium manganese oxide (LiMnO 2 2 2 2 4 or the like), or a sputtering target mainly composed of lithium nickel oxide (LiNiO 2 2 2 2 4 or the like) can be used. Alternatively, it may be formed by vacuum evaporation.

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

[0096] In addition, in order to form the positive electrode active material layer 101 containing magnesium, fluorine, aluminum, etc., in addition to lithium and one or more of manganese, cobalt, and nickel, a sputtering target containing magnesium, fluorine, aluminum, etc. may be used for film formation. Alternatively, after forming a film 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 evaporation and annealed.

[0097] Next, a cap layer 102 is formed on the positive electrode active material layer 101 (S4). As a method for forming the cap layer 102, a sputtering method, an evaporation method, or the like can be used. For example, when titanium oxide is used as the cap layer 102, titanium oxide can be formed by a reactive sputtering method using a titanium target and oxygen gas. Also, it is possible to form a film by sputtering a titanium oxide target.

[0098] It is preferable to form the positive electrode active material layer 101 and the cap layer 102 at a high temperature (500 °C or higher). A positive electrode 100 with better crystallinity can be produced.

[0099] Next, a 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, if a material containing titanium is also used for the solid electrolyte layer 203, a secondary battery can be easily manufactured. As a film formation method, a sputtering method, an evaporation method, or the like can be used.

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

[0102] Next, a negative electrode current collector 205 is formed on the negative electrode active material layer 204 (S7). As the material of the negative electrode current collector 205, one or more conductive materials selected from aluminum, titanium, copper, gold, chromium, tungsten, molybdenum, nickel, silver, etc. are used. As a film formation method, a sputtering method, an evaporation method, or the like can be used. Also, in the sputtering method, selective film formation can be achieved by using a metal mask. Further, the conductive film may be patterned by selectively removing it 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 sputtering, at least one of the positive electrode active material layer 101 and the negative electrode active material layer 204 is preferably formed by sputtering. The sputtering apparatus can also perform continuous film formation using the same chamber or a plurality of chambers, and can be a multi-chamber type manufacturing apparatus or an in-line type manufacturing apparatus. The sputtering method is a manufacturing method suitable for mass production using a chamber and a sputtering target. In addition, the sputtering method can form a thin film 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 two or more selected from hafnium, aluminum, gallium, yttrium, zirconium, tungsten, titanium, tantalum, nickel, germanium, neodymium, lanthanum, magnesium, etc. can be used. In addition, silicon oxynitride or silicon nitride can also be used. The protective layer 206 can be formed by using the sputtering method.

[0105] In addition, each layer described in this embodiment is not particularly limited to the sputtering method, and a vapor phase method (physical vapor deposition method, thermal spraying method, pulsed laser deposition method (PLD method), ion plating method, cold spray method, aerosol deposition method) can also be used. Note that the aerosol deposition (AD) method is a method of forming a film without heating the substrate. An aerosol refers to fine particles dispersed in a gas. In addition, a CVD method or an ALD (Atomic Layer Deposition) method may be used.

[0106] In the above process, the secondary battery 200, which is one aspect of the present invention, can be manufactured.

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

[0108] (Embodiment 3) In order to increase the output voltage of the thin-film secondary battery, the secondary batteries can be connected in series. In Embodiment 2, an example of a secondary battery with one cell was shown, but in this embodiment, an example of manufacturing a thin-film secondary battery in which a plurality of cells are connected in series is shown.

[0109] FIG. 9A shows a top view immediately after forming the first secondary battery, and FIG. 9B shows a top view in which two secondary batteries are connected in series. In FIGS. 9A and 9B, the same reference numerals are used for the same parts as those shown in FIG. 5A of Embodiment 2.

[0110] FIG. 9A shows a state immediately after forming the negative electrode current collector 205. The upper surface shape of the negative electrode current collector 205 is different from that in FIG. 5A. The negative electrode current collector 205 shown in FIG. 9A is in partial contact with 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 secondary batteries are arranged side by side on a plane and connected in series.

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

[0114] (Embodiment 4) In order to increase the output voltage of the thin-film secondary battery or to increase the discharge capacity, a multilayer secondary battery in which a plurality of positive electrodes and negative electrodes are respectively stacked and laminated can be used. In Embodiment 2, an example of a secondary battery with a single-layer cell was shown, but in this embodiment, an example of a thin-film battery with a multilayer cell is shown.

[0115] Figure 10 shows an example of the cross-section of a thin-film battery with a three-layer cell. By forming a positive electrode current collector 103 on a substrate 110, and then successively forming an underlayer 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 on the positive electrode current collector 103, the first cell is constructed.

[0116] Furthermore, by successively forming a second negative electrode active material layer 204, a solid electrolyte layer, a cap layer, a positive electrode active material layer, an underlayer film, and a positive electrode current collector layer on the negative electrode current collector 205, the second cell is constructed.

[0117] Furthermore, by successively forming a third underlayer 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 positive electrode current collector, the third cell is constructed.

[0118] In Figure 10, a protective layer 206 is finally formed. The three-layer stack shown in Figure 10 is configured to be connected in series to increase the capacitance, but it can also be connected in parallel by external wiring. Additionally, it is possible to select series, parallel, or series-parallel connections through external wiring.

[0119] Note that it is preferable to use the same material for the solid electrolyte layers 203, the second solid electrolyte layer, and the third solid electrolyte layer because it can reduce the manufacturing cost.

[0120] Also, an example of the manufacturing flow for obtaining the structure shown in Figure 10 is shown in Figure 11.

[0121] In Figure 11, in order to reduce the 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 the titanium film as a common electrode, a three-layer stacked cell can be realized with a simple configuration.

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

[0123] (Embodiment 5) In this embodiment, examples of a multi-chamber manufacturing apparatus capable of fully automating the production from the positive electrode current collector layer to the negative electrode current collector layer of a secondary battery are shown in FIGS. 12 and 13. This manufacturing apparatus can be suitably used for manufacturing a thin-film secondary battery according to one aspect of the present invention.

[0124] FIG. 12 shows an example of a multi-chamber manufacturing apparatus including 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, a plurality of film deposition chambers (a first film deposition chamber 892, a second film deposition 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 has at least a stage 851 and a substrate transfer 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 deposition chamber 892, the second film deposition 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 exhaust device may be appropriately selected according to the use purpose of each chamber. For example, an exhaust mechanism equipped with a pump having an adsorption means such as a cryopump, a sputter ion pump, a titanium sublimation pump, etc., or an exhaust mechanism equipped with a cold trap for a turbo molecular pump may be mentioned.

[0128] As a procedure for film formation on a substrate, the substrate 850 or the substrate cassette is placed in the load lock chamber 870 and transported to the mask alignment chamber 891 by the substrate transfer mechanism 852. In the mask alignment chamber 891, the mask to be used is picked up from among a plurality of pre-set masks, and alignment is performed with the substrate on the stage 851. After the alignment is completed, the gate 880 is opened, and the mask and the substrate 850 are transported to the first transfer chamber 871 by the substrate transfer mechanism 852. After transporting the mask and the substrate 850 to the first transfer chamber 871, the gate 881 is opened and they are transported to the second transfer chamber 872 by the substrate transfer mechanism 853.

[0129] The first film formation chamber 892 provided in the second transfer chamber 872 via the gate 882 is a sputtering film formation chamber. The sputtering film formation chamber has an RF power source and a mechanism capable of switching a pulse DC power source to apply a voltage to the sputtering target. Also, two or three types of sputtering targets can be set. In the present embodiment, a single crystal silicon target, a sputtering target mainly composed of lithium cobalt oxide (LiCoO 2 ), 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 perform film formation while heating to a heater temperature of 700°C.

[0130] In the sputtering method using a single crystal silicon target, the negative electrode active material layer can be formed. Also, a film formed as SiO 2 by a reactive sputtering method using Ar gas and O X gas may be used as the negative electrode active material layer. It is also possible to use a silicon nitride film as a sealing film by a reactive sputtering method using Ar gas and N 2 gas. Also, in the sputtering method using a sputtering target mainly composed of lithium cobalt oxide (LiCoO 2 ), the positive electrode active material layer can be formed. In the sputtering method using a titanium target, a conductive film serving as a current collector can be formed. A titanium nitride film can be formed by a reactive sputtering method using Ar gas and N 2 gas, and it is also possible to form a cap layer or an underlayer.

[0131] When forming the positive electrode active material layer, the substrate is transported from the second transfer chamber 872 to the first film deposition chamber 892 by the substrate transfer mechanism 853 with the mask and the substrate overlapped, the gate 882 is closed, and film deposition is performed by a sputtering method. After the film deposition is completed, the gates 882 and 883 are opened, and the substrate is transported to the heating chamber 893. After the gate 883 is closed, heating can be performed. For the heat treatment in the heating chamber 893, an RTA (Rapid Thermal Anneal) apparatus, a resistance heating furnace, or a microwave heating apparatus can be used. For the RTA apparatus, a GRTA (Gas Rapid Thermal Anneal) apparatus or an LRTA (Lamp Rapid Thermal Anneal) apparatus can be used. The heat treatment in the heating chamber 893 can be performed in an atmosphere of nitrogen, oxygen, noble gas, or dry air. Also, the heating time is set to be 1 minute or more and 24 hours or less.

[0132] After the film deposition or the heat treatment is completed, the substrate and the mask are returned to the mask alignment chamber 891, and a new mask is aligned. The substrate and the mask after the alignment are transported to the first transfer chamber 871 by the substrate transfer mechanism 852. The substrate is carried by the lifting mechanism of the first transfer chamber 871, 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 deposition chamber 874 connected to the third transfer chamber 873 via the gate 885 performs film deposition by evaporation.

[0134] An example of the cross-sectional structure of the configuration of the second film formation chamber 874 is shown in FIG. 13. FIG. 13 is a schematic cross-sectional view taken along the dotted line in FIG. 12. The second film formation chamber 874 is connected to the exhaust mechanism 849, and the first material supply chamber 895 is connected to the exhaust mechanism 848. The second material supply chamber 894 is connected to the exhaust mechanism 847. The second film formation chamber 874 shown in FIG. 13 is a vapor deposition chamber that performs vapor deposition using the vapor deposition source 856 moved from the first material supply chamber 895. The vapor deposition sources are moved from a plurality of material supply chambers respectively, and a plurality of substances can be vaporized and deposited simultaneously, that is, co-deposited. In FIG. 13, a vapor deposition source having a vapor deposition boat 858 moved from the second material supply chamber 894 is also shown.

[0135] Also, the second film formation chamber 874 is connected to the second material supply chamber 894 via the gate 886. Also, the second film formation chamber 874 is connected to the first material supply chamber 895 via the gate 888. Also, the second film formation chamber 874 is connected to the third material supply chamber 896 via the gate 887. Therefore, ternary co-deposition is possible in the second film formation chamber 874.

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

[0137] Thereafter, the shutter 868 and the evaporation source shutter 869 are opened to perform co-evaporation. During evaporation, the rotation mechanism 865 is rotated to enhance the film thickness uniformity. The substrate after evaporation follows the same path and is transported to the mask alignment chamber 891. When removing the substrate from the manufacturing apparatus, it will be transported from the mask alignment chamber 891 to the load lock chamber 870 and then removed.

[0138] Also, in FIG. 13, an example is shown when the substrate 850 and the mask are held by the substrate holding portion 845. By rotating the substrate 850 (and the mask) by the substrate rotation mechanism, the film formation uniformity can be enhanced. The substrate rotation mechanism may also serve as the substrate transfer mechanism.

[0139] Moreover, the second film formation chamber 874 may be provided with imaging means 863 such as a CCD camera. By providing the imaging means 863, it becomes possible to confirm the position of the substrate 850.

[0140] Also, in the second film formation chamber 874, the film thickness formed on the substrate surface can be predicted based on the measurement result of the film thickness measurement mechanism 867. As the film thickness measurement mechanism 867, for example, it may be provided with a crystal oscillator or the like.

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

[0142] In the evaporation source 856, an example of a resistance heating method is shown, but an EB (Electron Beam) evaporation method may also be used. Further, an example of a crucible is shown as the container of the evaporation source 856, but an evaporation boat may also be used. An organic material is placed as the first evaporation material 855 in the crucible heated by the heater 857. Further, when pellets or particulate SiO or the like is used as the evaporation material, the evaporation boat 858 is used. The evaporation boat 858 is composed of three parts, a member having a concave surface, an inner lid with two holes, and an upper lid with one hole, which are stacked. Note that the inner lid may be removed for evaporation. The evaporation boat 858 functions as a resistor when energized, and has a mechanism in which the evaporation boat itself is heated.

[0143] In addition, in this embodiment, an example of a multi-chamber method is shown, but it is not particularly limited, and an inline type manufacturing apparatus may also be used.

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

[0145] (Embodiment 6) In this embodiment, an example of a thin film secondary battery having a battery control circuit or the like will be described.

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

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

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

[0149] The layer 916 has a function of being able to shield, for example, an electromagnetic field by the secondary battery 913. As the layer 916, for example, a magnetic material can be used.

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

[0151] It is preferable to use a flexible substrate as the substrate 900.

[0152] By using a flexible substrate as the substrate 900, a thin battery control circuit can be realized. Also, as shown in FIG. 15D described later, the battery control circuit can be wound around the secondary battery.

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

[0154] As shown in FIG. 15C, by bending the substrate 900 according to the shape of the secondary battery 913 and arranging the battery control circuit around the secondary battery, as shown in FIG. 15D, the battery control circuit can be wound around the secondary battery. By using a secondary battery having such a configuration, a smaller secondary battery can be obtained.

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

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

[0157] FIG. 16A is an external perspective view of a thin-film secondary battery 3001 according to the present invention. It is sealed with a laminate film or an insulating material so that 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 protrude.

[0158] FIG. 16B is an IC card which is an example of an application device using the thin-film secondary battery according to the present invention. The thin-film secondary battery 3001 can be charged with the electric power obtained by power feeding from the radio wave 3005. Inside the IC card 3000, an antenna, an IC 3004, and the thin-film secondary battery 3001 are arranged. On the IC card 3000, the ID 3002 of the worker wearing the management badge and the photo 3003 are displayed. Signals such as authentication signals can also be transmitted from the antenna using the electric power charged in the thin-film secondary battery 3001.

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

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

[0161] Alternatively, a solar cell may be provided instead of the photo 3003. The solar cell can absorb light by irradiation with external light, generate electric power, and charge the thin-film secondary battery 3001 with the electric power.

[0162] In addition, the thin-film secondary battery is not limited to an IC card and can be used for powering wireless sensors for in-vehicle use, secondary batteries 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. Also, when the user uses it in daily life or outdoors, in order to enhance the anti-foaming performance, water resistance performance, or dust-proof performance, a wearable device that can perform not only wired charging with an exposed connector part but also wireless charging is desired.

[0164] For example, a secondary battery according to one aspect 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 the secondary battery on the temple part of the frame 400a having a curvature, a lightweight glasses-type device 400 with good weight balance and a long continuous use time can be obtained. By providing a secondary battery according to one aspect of the present invention, a configuration that can cope with space saving due to downsizing of the housing can be realized.

[0165] In addition, a secondary battery according to one aspect of the present invention can be mounted on a headset-type device 401. The headset-type device 401 has at least a microphone part 401a, a flexible pipe 401b, and an earphone part 401c. A secondary battery can be provided inside the flexible pipe 401b or inside the earphone part 401c. By providing a secondary battery according to one aspect of the present invention, a configuration that can cope with space saving due to downsizing of the housing can be realized.

[0166] In addition, a secondary battery according to one aspect 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 inside the thin housing 402a of the device 402. By providing a secondary battery according to one aspect of the present invention, a configuration that can cope with space saving due to downsizing of the housing can be realized.

[0167] Further, a secondary battery, which is one aspect of the present invention, can be mounted on a device 403 attachable to clothing. A secondary battery 403b can be provided inside a thin housing 403a of the device 403. By providing a secondary battery, which is one aspect of the present invention, a configuration can be realized that can cope with space saving accompanying the miniaturization of the housing.

[0168] Also, a secondary battery, which is one aspect of the present invention, can be mounted on a belt-type device 406. The belt-type device 406 has a belt portion 406a and a wireless power feeding / receiving portion 406b, and a secondary battery can be mounted inside the belt portion 406a. By providing a secondary battery, which is one aspect of the present invention, a configuration can be realized that can cope with space saving accompanying the miniaturization of the housing.

[0169] Also, a secondary battery, which is one aspect of the present invention, can be mounted on a wristwatch-type device 405. The wristwatch-type device 405 has a display portion 405a and a belt portion 405b, and a secondary battery can be provided in the display portion 405a or the belt portion 405b. By providing a secondary battery, which is one aspect of the present invention, a configuration can be realized that can cope with space saving accompanying the miniaturization of the housing.

[0170] The display portion 405a can display not only time but also various information such as incoming mails and calls.

[0171] Also, since the wristwatch-type device 405 is a wearable device of a type that is directly wound around the wrist, a sensor for measuring a user's pulse, blood pressure, etc. may be mounted. Data regarding the user's exercise amount and health can be accumulated to manage the health.

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

[0173] Further, a side view of the wristwatch-type device 405 is shown in FIG. 17C. FIG. 17C shows a state in which the secondary battery 913 is built inside. The secondary battery 913 is the secondary battery shown in Embodiment 5. The secondary battery 913 is provided at a position overlapping the display unit 405a, and is small and lightweight.

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

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

[0176] FIG. 18A shows a perspective view of a wristwatch-type portable information terminal (also called a smartwatch) 700. The portable information terminal 700 includes a housing 701, a display panel 702, a clasp 703, bands 705A and 705B, and operation buttons 711 and 712.

[0177] The display panel 702 mounted on the housing 701 that also serves as a bezel portion has a rectangular display area. Further, the display area forms a curved surface. The display panel 702 preferably has flexibility. Note that the display area may be non-rectangular.

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

[0179] FIG. 18B and FIG. 18C respectively show perspective views of the band 705A and the secondary battery 750. The band 705A has the secondary battery 750. As 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 part 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. Also, the surface of the secondary battery 750 is covered with an exterior body 753 (see FIG. 18C). Note that the above 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. By doing so, the configuration at the connection part of the band 705A and the housing 701 can be simplified.

[0180] The secondary battery 750 has flexibility. Therefore, the band 705A can be manufactured by integrally forming it with the secondary battery 750. For example, the secondary battery 750 is set in a mold corresponding to the outer shape of the band 705A, the material of the band 705A is poured into the mold, and the material is cured to manufacture the band 705A shown in FIG. 18B.

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

[0182] Examples of the material used for the band 705A include fluororubber, silicone rubber, fluorosilicone rubber, and urethane rubber, in addition to these.

[0183] Note that the mobile information terminal 700 shown in FIG. 18A can have various functions. For example, functions such as displaying various information (still images, moving images, text images, etc.) in the display area, touch panel function, displaying a calendar, date, or time, etc., controlling processing by various software (programs), wireless communication function, connecting to various computer networks using the wireless communication function, transmitting or receiving various data using the wireless communication function, reading out programs or data recorded on a recording medium and displaying them in the display area, etc. can be had.

[0184] Also, inside the housing 701, there can be a speaker, a sensor (including those having the function of measuring force, displacement, position, speed, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substances, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared rays), a microphone, etc. Note that the mobile information terminal 700 can be manufactured by using a light-emitting element for its display panel 702.

[0185] Note that in FIG. 18A, an example where the secondary battery 750 is included in the band 705A is shown, but the secondary battery 750 may be included in the band 705B. As the band 705B, the same material as the band 705A can be used.

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

[0187] For example, the cleaning robot 6300 can analyze the images captured by the camera 6303 and determine the presence or absence of obstacles such as walls, furniture, or steps. Also, when an object that is likely to get caught in the brush 6304 such as wiring 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 aspect of the present invention and a semiconductor device or electronic components inside thereof. By using the secondary battery according to one aspect of the present invention in the cleaning robot 6300, the cleaning robot 6300 can be made into an electronic device with a 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, an arithmetic unit, etc.

[0189] The microphone 6402 has a function of detecting the user's voice, environmental sounds, etc. Also, the speaker 6404 has a function of emitting sound. The robot 6400 can communicate with the user by 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 the information desired by the user on the display unit 6405. The display unit 6405 may be equipped with a touch panel. Also, the display unit 6405 may be a removable information terminal, and by installing it at a fixed position of the robot 6400, charging and data transfer are made possible.

[0191] The upper camera 6403 and the lower camera 6406 have the function of imaging the surroundings of the robot 6400. Also, the obstacle sensor 6407 can detect the presence or absence of obstacles in the traveling 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 aspect of the present invention and semiconductor devices or electronic components inside thereof. By using the secondary battery according to one aspect of the present invention in the robot 6400, the robot 6400 can be made into an electronic device with a long operating time and high reliability.

[0193] FIG. 19C shows an example of an aircraft. The aircraft 6500 shown in FIG. 19C has a propeller 6501, a camera 6502, a secondary battery 6503, etc., and has the function of autonomous flight.

[0194] For example, the 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 obstacles when moving. Also, the remaining battery level can be estimated from the change in the storage capacity of the secondary battery 6503 by the electronic component 6504. The aircraft 6500 includes a secondary battery 6503 according to one aspect of the present invention inside thereof. By using the secondary battery according to one aspect of the present invention in the aircraft 6500, the aircraft 6500 can be made into an electronic device with a long operating time and high reliability.

[0195] FIG. 19D shows an example of an automobile. The automobile 7160 has a secondary battery 7161, an engine, tires, brakes, a steering device, a camera, etc. It is preferable to have a system 1000 described later. The automobile 7160 includes a secondary battery 7161 according to one aspect of the present invention inside thereof. By using the secondary battery according to one aspect of the present invention in the automobile 7160, the automobile 7160 can be made into an automobile with a long cruising range, high safety, and high reliability.

[0196] Also, one aspect of the present invention may be an electronic device or system having the thin-film battery described in the previous embodiment and another secondary battery. The other secondary battery is not particularly limited, and for example, 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 can be used. In this specification and the like, the system refers to a system in which individual elements are combined. It has a secondary battery as one of the elements.

[0197] FIG. 20A shows a system 1000 having 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. By using such an electronic device or system, it is possible to take advantage of both a secondary battery having a larger discharge capacity and the thin-film battery described in the previous embodiment that can be easily made thin and light. The system 1000 preferably has a wireless power supply device. If it has a wireless power supply device, power can be easily supplied from the lithium-ion secondary battery 1002 to the thin-film battery 1001.

[0198] FIG. 20B shows the interior of an automobile 7160 when it has the system 1000. The automobile 7160 has a secondary battery for driving, a wireless power supply device 7162, and a key 7163. By arranging the key 7163 on the wireless power supply device 7162, power can be supplied from the secondary battery 7161 for driving to the key 7163. Although FIG. 20B shows an example where the wireless power supply device 7162 is installed on the dashboard, it is not limited to this. A storage place for the key 7163 may be provided at other locations around the driver's seat, and the wireless power supply device 7162 may be provided at the storage place.

[0199] At this time, if the key 7163 has the thin-film battery described in the previous embodiment, it is preferable because the key can be made thinner and lighter. Also, for the secondary battery for driving of 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 can be implemented in appropriate combination with other embodiments.

[0201] (Embodiment 9) The device described in this embodiment has at least a biosensor and a solid secondary battery that supplies power to the biosensor, and can acquire various biological information using infrared light and visible light and store it in a memory. Such biological information can be used for both user personal authentication applications and healthcare applications. The secondary battery of one aspect of the present invention has a high discharge capacity and cycle characteristics, and further has high safety. Therefore, the device has high safety and can be used for a long time.

[0202] A biosensor is a sensor that acquires biological information and acquires biological information that can be used for healthcare applications. Examples of biological information include pulse wave, blood glucose level, oxygen saturation, neutral fat concentration, etc. The data is stored in a memory.

[0203] Furthermore, it is preferable to provide the device described in this embodiment with means for acquiring other biological information. For example, in addition to biological information inside the body such as electrocardiogram, blood pressure, and body temperature, there is also surface biological information such as facial expression, complexion, and pupil. Also, information such as the number of steps, exercise intensity, height difference of movement, and diet (intake calories, nutrients, etc.) is also important information for healthcare. By using a plurality of biological information, etc., comprehensive physical condition management becomes possible, leading 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 time difference between two pulsations of a pulse wave (the length of the pulse wave propagation time). When the blood pressure is high, the pulse wave propagation time is short, and conversely, when the blood pressure is low, the pulse wave propagation time is long. Also, based on the relationship between the heart rate and blood pressure calculated from the electrocardiogram and the pulse wave, the physical condition of the user can be estimated. 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. Also, if the state of low blood pressure and high heart rate continues, there may be a possibility of heart disease or the like.

[0205] Since the user can check at any time the biological information measured by the electronic device and their own physical condition estimated based on that information, their health awareness is improved. As a result, it can also be a trigger for reviewing daily habits such as avoiding overeating and drinking, paying attention to appropriate exercise, or managing one's physical condition, or receiving a medical examination by a medical institution as needed.

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

[0207] In the case of the embedded type device shown in FIG. 21A, it is premised that it is small, has almost no heat generation, and does not cause an allergic reaction even when in contact with the skin. The secondary battery used in the device of one aspect of the present invention is small, has almost no heat generation, and does not cause an allergic reaction or the like, so it is suitable. Also, it is preferable for the embedded type device to incorporate an antenna in order to enable wireless charging.

[0208] The device of the type to be implanted in the 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 the acquired data in a temporary memory built into the device. Alternatively, each data acquired by the biosensor may be wirelessly or wiredly sent to the portable data terminal 85 in Fig. 21B, and the portable data terminal 85 may have a function of detecting a waveform. The portable data terminal 85 is a smartphone or the like, and it can detect whether there are problems such as arrhythmia from the data acquired by each biosensor. When sending the data acquired by a plurality of biosensors to the portable data terminal 85 by wire, it is preferable to transfer the data acquired until the wired connection is made all at once. Note that each detected data is automatically dated and stored in the memory of the portable data terminal 85 and may be managed personally. Alternatively, as shown in Fig. 21B, it may be transmitted to a medical institution 87 such as a hospital via a network (including the Internet). The data is managed by the hospital's data server and can be used as inspection data during treatment. Since medical data may be enormous, a network including Bluetooth (registered trademark) or a frequency band from 2.4 GHz to 2.4835 GHz may be used from the biosensor 80b to the portable data terminal 85, and high-speed communication may be performed using the fifth-generation wireless system from the portable data terminal 85 to the portable data terminal 85. The fifth-generation wireless system uses frequencies in the 3.7 GHz band, 4.5 GHz band, and 28 GHz band. By using the fifth-generation wireless system, it is possible to acquire data and transmit data to the medical institution 87 not only at home but also when going out, accurately acquire data when the user's physical condition is abnormal, and utilize it for subsequent processing or treatment. Note that as the portable data terminal 85, the configuration shown in Fig. 21C can be utilized.

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

[0211] The pair of electrodes 83 is provided on a part of the housing 82 with the display unit 81a interposed therebetween. The display unit 81b is a region having a curved surface. The electrode 83 functions as an electrode for acquiring biological information.

[0212] As shown in FIG. 21C, by arranging the pair of electrodes 83 in the longitudinal direction of the housing 82, when using the portable data terminal 89 with a horizontally long screen, it is possible to acquire biological information without the user being aware of it.

[0213] An example of the usage state of the portable data terminal 89 is shown. On the display unit 81a, information 88a of an electrocardiogram acquired by the pair of electrodes 83, information 88b of a heart rate, etc. can be displayed.

[0214] When the biosensor 80a is implanted in the user's body as shown in FIG. 21A, this function can be said to be unnecessary. However, when it is not implanted, the user can acquire an electrocardiogram by gripping the pair of electrodes 83 with both hands. Even when the biosensor 80a is implanted in the user's body, the portable data terminal 89 shown in FIG. 21C can be used to confirm whether the biosensor 80a is functioning properly. Also, when comparing electrocardiogram data among multiple users, the portable data terminal 89 shown in FIG. 21C can be used.

[0215] The camera 84 can image the user's face and the like. Biological information such as expression, pupil, and complexion can be acquired from the image of the user's face.

[0216] The microphone 86 can acquire the user's voice. From the acquired voice information, voiceprint information that can be used for voiceprint authentication can be obtained. Also, by periodically acquiring voice information and monitoring changes in its voice quality, it can be used for health management as well. Of course, it is also possible to make a videophone call with a doctor at the medical institution 87 using the microphone 86, the camera 84, and the speaker.

[0217] By using the device shown in FIG. 21A and the portable data terminal 89 shown in FIG. 21C, it is also possible to realize a remote medical support system such as sending information from a remote location to a doctor at a hospital and receiving medical treatment from the doctor.

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

Example

[0219] In this example, a secondary battery having a base film and a cap layer, which is one aspect of the present invention, and a secondary battery having no base film or cap layer as a comparative example were fabricated, and their charge-discharge characteristics and cycle characteristics were evaluated.

[0220] <Fabrication of Secondary Battery> Sample 1, which is one aspect of the present invention, was fabricated as follows. First, a titanium sheet was used as a material that also serves as a substrate and a positive current collector layer. The titanium sheet was a rolled foil with a thickness of 0.1 mm, a purity of 99.5%, subjected to etching, and non-mirror surface, and was processed into a 12 mmφ size for use.

[0221] On the titanium sheet, titanium nitride (TiN) was formed as a base film by sputtering at 20 nm. The sputtering conditions were as follows. Target: Titanium target, diameter 100 mm Sputtering power supply, output: DC power supply, 500 W Atmosphere: Argon flow rate 12.0 sccm, nitrogen flow rate 28 sccm, pressure 0.4 Pa Film formation time: 8 minutes Film formation temperature: Set to 600 °C Film formation rate: 2.5 nm / min

[0222] Next, lithium cobalt oxide (LiCoO 2 ) was deposited as the positive electrode active material layer by sputtering to a thickness of 1000 nm. The sputtering conditions were as follows. Target: Lithium cobalt oxide target, 100 mm in diameter Sputtering power supply, output: RF power supply, 500 W Atmosphere: Argon flow rate 40 sccm, oxygen flow rate 10 sccm, pressure 0.4 Pa Film deposition time: 461 minutes Film deposition temperature: Set to 600 °C Film deposition rate: 2.2 nm / min

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

[0224] Also, sample 2 without an underlayer film and sample 3 with titanium oxide (TiO x ) deposited as the underlayer film were fabricated. These were fabricated in the same manner as sample 1 except for the underlayer film.

[0225] Furthermore, as comparative examples, samples 4 to 6 without a cap layer were fabricated. These were fabricated in the same manner as samples 1 to 3 except that the cap layer was not deposited.

[0226] The fabrication conditions of each sample are shown in Table 2.

[0227]

Table 2

[0228] <Fabrication of Battery Cells> Next, using each sample as the positive electrode, coin-type battery cells of the CR2032 type (diameter 20 mm, height 3.2 mm) were fabricated.

[0229] Lithium metal was used as the counter electrode.

[0230] For the electrolyte in the electrolytic solution, 1 mol / L lithium hexafluorophosphate (LiPF 6 ) was used. For the electrolytic solution, a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) with EC:DEC = 3:7 (volume ratio) was used. For the secondary batteries for which charge-discharge efficiency was evaluated, 2 wt% vinylene carbonate (VC) was added to the electrolytic solution.

[0231] Polypropylene with a thickness of 25 μm was used as the separator.

[0232] Stainless steel (SUS)-formed positive and negative cans were used.

[0233] <Measurement of Charge-Discharge Efficiency> For the measurement of initial characteristics, charging was performed in CCCV at 0.2C, 4.2V, with a cut-off current of 0.1C. Discharging was performed in CC at 0.2C, with a cut-off voltage of 2.5V. Here, 1C was defined as 137 mA / g, which is the current value per unit weight of the positive electrode active material. The measurement temperature was 25°C. The results of measuring the initial characteristics are shown in Table 3, Figure 22A, and Figure 22B. Figure 22A is a graph of Samples 1 to 3, and Figure 22B is a graph of Samples 4 to 6.

[0234]

Table 3

[0235] From Table 3, Figure 22A, and Figure 22B, it was found that all samples exhibited good charge-discharge characteristics.

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

[0237] From FIGS. 23A and 23B, Samples 1 to 3 having a cap layer showed significantly better cycle characteristics than Samples 4 to 6 having no cap layer. Sample 1 having titanium nitride as the base film showed 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 the base film showed characteristics next 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 base film had a discharge capacity of 111 mAh / g and a discharge capacity retention rate of 92% after 25 cycles.

[0238] Therefore, it became clear that a secondary battery with good charge-discharge cycle characteristics can be produced by providing a cap layer. Also, it became clear that the charge-discharge cycle characteristics are better when there is a base film than when there is no base film, and titanium nitride is particularly preferable.

Example

[0239] In this example, a secondary battery having a cap layer, which is one aspect of the present invention, and a secondary battery having no cap layer as a comparative example were produced, and the characteristics were analyzed by TEM, electron energy loss spectroscopy (EELS), microelectron diffraction, impedance measurement, etc., and the cycle characteristics were evaluated.

[0240] <Fabrication of secondary battery> Sample 11, which is one aspect of the present invention, was fabricated as follows. First, a 100-μm titanium sheet was used as a substrate and a positive current collector layer.

[0241] A titanium nitride (TiN) film with a thickness of 20 nm was deposited as an underlayer film on a titanium sheet by sputtering. The sputtering conditions were as follows. Target: Titanium target, 2 inches in diameter Sputtering power supply, output: RF power supply, 100 W Atmosphere: Argon flow rate 3.0 sccm, nitrogen flow rate 7 sccm, pressure 0.5 Pa Film deposition time: 15 minutes Film deposition temperature: Set at 600 °C Target - substrate distance: 75 mm

[0242] Next, lithium cobalt oxide (LiCoO 2 ) was deposited by sputtering to form a 900 - nm - thick positive electrode active material layer. The sputtering conditions were as follows. Target: Lithium cobalt oxide target, 2 inches in diameter Sputtering power supply, output: RF power supply, 200 W Atmosphere: Argon flow rate 10 sccm, pressure 0.5 Pa Film deposition time: 109 minutes Film deposition temperature: Set at 600 °C Target - substrate distance: 75 mm Film deposition rate: 9.2 nm / min

[0243] Next, titanium oxide (TiO 2 ) was deposited by sputtering to form a 20 - nm - thick cap layer. The sputtering conditions were as follows. Target: Titanium target, 100 mm in diameter Sputtering power supply, output: DC power supply, 500 W Atmosphere: Argon flow rate 24 sccm, oxygen flow rate 16 sccm, pressure 0.4 Pa Film deposition time: 27.7 minutes Film deposition temperature: Set at 600 °C (the actual substrate temperature was about 400 °C) Film deposition rate: 0.72 nm / min

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

[0245] The production conditions of each sample are shown in Table 4.

[0246]

Table 4

[0247] <tem> The imaging conditions for the TEM images were as follows. Sample pretreatment: Thinning by the FIB method (μ-sampling method) Transmission electron microscope: JEM-ARM200F manufactured by JEOL Observation conditions Acceleration voltage: 200 kV Magnification accuracy: ±3%

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

[0249] <eels> Next, for the sample after charge and discharge, the electronic state of cobalt was analyzed using EELS, and the valence was calculated from the L 3 / L 2 ratio with reference to Non-Patent Document 1. The measurement conditions for EELS were as follows. Elemental analysis (point analysis) Scanning transmission electron microscope: JEM-ARM200F manufactured by JEOL Acceleration voltage: 200 kV Beam diameter: approximately 0.1 nm φ Elemental analyzer: Quantum ER manufactured by Gatan Electron spectrometer: MOS detector array Integration time: 30 seconds

[0250] The EELS analysis locations of Sample 11 after charge and discharge are indicated by *1 and *2 in Fig. 28A, and *3, *4, and *5 in Fig. 28B. *1 and *2 are at a depth of about 100 nm from the outermost surface of the lithium cobalt oxide layer toward the substrate. *3 to *5 are also at a depth of about 30 nm. All analysis locations are at grain boundaries and in their vicinity, but *2, *4, and *5 are inside the crystal grains, rather than *1 and *3. Note that Fig. 28B is an enlarged image of the photo.3-14 portion surrounded by a white line in Fig. 27.

[0251] The EELS spectra of the locations indicated by *1 to *5 of Sample 11 are shown in Fig. 29. The EEL spectrum (Background subtracted EEL spectrum) obtained by subtracting the background calculated from the lower binding energy side than the Co-L 3 edge, and the spectrum of the Co-L 3 edge and Co-L 2 edge, further subtracting the background calculated from the energy band between the edges, and the spectrum of the Co-L 3 level and the L 2 level continuum (Co-L 2 , 3 (continuum subtracted spectrum) is shown in the figure. The Background subtracted EEL spectrum was obtained by fitting the original data with a power law model and subtracting the background. Also, Co-L 2 , 3 The continuum subtracted spectrum was further obtained by subtracting the model of the scattering cross section of cobalt (Hartree-slater cross section model) as the background function from the data with the background removed by the above power law fitting. Also, L 3 / L 2 The area intensity ratio of and the calculated valence of cobalt are shown in Table 5.

[0252]

Table 5

[0253] Figures 31A and 31B are cross-sectional TEM images of Sample 12 after charge and discharge. The EELS analysis locations are indicated by *1 and *2 in Figure 31A, and *3, *4, and *5 in Figure 18B. All analysis locations are at or near grain boundaries, but *2, *4, and *5 are inside the grains compared to *1 and *3. Note that Figure 31B is an enlarged image of the photo.2-16 part surrounded by a white line in Figure 30.

[0254] The EELS spectra of locations *1 to *5 of Sample 12 after charge and discharge are similarly shown in Figure 32. L 3 / L 2 The area intensity ratio of and the calculated valence of cobalt are shown in Table 6.

[0255]

Table 6

[0256] From Tables 5 and 6, it was revealed that in Sample 11 with a cap layer, the reduction of cobalt inside the crystal grains tended to be suppressed. Therefore, it was suggested that the deterioration of the layered rock salt-type crystal structure could be suppressed by providing a cap layer.

[0257] <Ultra-micro electron beam diffraction> Next, the grain boundaries of lithium cobaltate and the crystal structure in the vicinity thereof were analyzed using ultra-micro electron beam diffraction.

[0258] Figure 25A is a cross-sectional TEM image of Sample 11 before charge and discharge. The analysis locations for ultra-micro 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 photo.1-7 portion surrounded by a black line in Figure 24.

[0259] Figure 25B shows the ultra-micro electron beam diffraction image of the *point1-1 portion. The transmitted light is denoted as O, and some of the diffraction spots are denoted as 1, 2, and 3 and shown in the figure. When analyzing the *point1-1 portion, the interplanar spacings were calculated as 0.137 nm for 1, 0.143 nm for 2, and 0.464 nm for 3. Also, the plane angles were ∠1O2 = 17°, ∠1O3 = 107°, and ∠2O3 = 90°. At this time, the electron beam incident direction was

[0120] . From the interplanar spacings and plane angles, it was considered that 1 was -213 of the layered rock salt-type crystal, 2 was similarly -210, and 3 was similarly 00-3, and it had a layered rock salt-type crystal structure. Calculating the lattice constants of the *point1-1 portion from these d values, a = 2.86 (Å) and c = 13.9 (Å).

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

[0120] . From the interplanar spacing and plane angles, 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. Calculating the lattice constants of the *point1-2 part from these d values, a = 2.86 (Å) and c = 13.9 (Å).

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

[0120] . From the interplanar spacing and plane angles, 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. Calculating the lattice constants of the *point1-3 part from these d values, a = 2.92 (Å) and c = 13.9 (Å).

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

[0263] Figure 33B shows the nanoelectron diffraction image of the *point3-1* part. The transmitted light is denoted as O, and some of the diffraction spots are denoted as 1, 2, and 3, which are shown in the figure. When analyzing the *point3-1* part, the interplanar spacing of 1 was calculated to be 0.227 nm, that of 2 was 0.183 nm, and that of 3 was 0.475 nm. Also, the plane angles were ∠1O2 = 21°, ∠1O3 = 71°, and ∠2O3 = 50°. At this time, the electron beam incident direction was [0 - 10]. From the interplanar spacing and plane angles, 1 was 10 - 2 of the layered rock salt type crystal, 2 was similarly 10 - 5, and 3 was similarly 00 - 3. It was considered to have a layered rock salt type crystal structure. Calculating the lattice constants of the *point3-1* part from these d values, a = 2.76 (Å) and c = 14.2 (Å).

[0264] Figure 34A shows the nanoelectron diffraction image of the *point3-2* part. The transmitted light is denoted as O, and some of the diffraction spots are denoted as 1, 2, and 3, which are shown in the figure. When analyzing the *point3-2* part, the interplanar spacing of 1 was calculated to be 0.226 nm, that of 2 was 0.181 nm, and that of 3 was 0.468 nm. Also, the plane angles were ∠1O2 = 22°, ∠1O3 = 71°, and ∠2O3 = 49°. At this time, the electron beam incident direction was [0 - 10]. 1 was - 102 of the layered rock salt type crystal, 2 was similarly - 105, and 3 was similarly 003. It was considered to have a layered rock salt type crystal structure. Calculating the lattice constants of the *point3-2* part from these d values, a = 2.74 (Å) and c = 14.1 (Å).

[0265] Figure 34B shows the nanoelectron diffraction image of the *point3-3* part. The transmitted light is denoted as O, and some of the diffraction spots are denoted as 1, which is shown in the figure. When analyzing the *point3-3* part, the interplanar spacing of 1 was calculated to be 0.470 nm. At this time, the electron beam incident direction was

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

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

[0267] Figure 35B shows the nanoelectron diffraction image of the *point2-1 portion. The transmitted light is denoted as O, and some of the diffraction spots are denoted as 1, 2, and 3, as shown in the figure. When analyzing the *point2-1 portion, the interplanar spacing of 1 was calculated to be 0.125 nm, that of 2 was 0.115 nm, and that of 3 was 0.234 nm. Also, the plane angles were ∠1O2 = 29°, ∠1O3 = 96°, and ∠2O3 = 66°. At this time, the electron beam incident direction was

[0010] , 1 was 20-1 of the layered rock salt-type crystal, 2 was similarly 205, and 3 was similarly 006, and it was considered to have a layered rock salt-type crystal structure. From these d values, when calculating the lattice constants of the *point2-1 portion, a = 2.91 (Å) and c = 14.1 (Å).

[0268] Figure 36A shows the nanoelectron diffraction image of the *point2-2 portion. The transmitted light is denoted as O, and some of the diffraction spots are denoted as 1, 2, and 3, as shown in the figure. When analyzing the *point2-2 portion, the interplanar spacing of 1 was calculated to be 0.126 nm, that of 2 was 0.115 nm, and that of 3 was 0.234 nm. Also, the plane angles were ∠1O2 = 29°, ∠1O3 = 95°, and ∠2O3 = 66°. At this time, the electron beam incident direction was

[0010] , 1 was 20-1 of the layered rock salt-type crystal, 2 was similarly 205, and 3 was similarly 006, and it was considered to have a layered rock salt-type crystal structure. From these d values, when calculating the lattice constants of the *point2-2 portion, a = 2.91 (Å) and c = 14.1 (Å).

[0269] Fig. 36B shows the ultrafine electron diffraction image of the *point2-3 portion. The transmitted light is marked as O, and a part of the diffraction spot is marked as 1, as shown in the figure. When analyzing the *point2-3 portion, the interplanar spacing of 1 was calculated to be 0.474 nm. At this time, the electron beam incident direction was

[0003] , and 1 was 003 of the layered rock salt type crystal, so it was considered to have a layered rock salt type crystal structure. From this d value, when calculating the lattice constant of the *point2-3 portion, c = 14.21 (Å). The a axis was not calculated because there was no corresponding d value.

[0270] As described above, the lattice constant of Sample 11 without a cap layer after charge and discharge tended to be larger than that of lithium cobaltate before charge and discharge. This is presumably because the reduction of cobalt occurred.

[0271] On the other hand, in Sample 12 with a cap layer, the a axis tended to be small on average even after charge and discharge. This indicates that the valence of cobalt is large and the reduction of cobalt is suppressed.

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

[0273] Coin-type battery cells of the CR2032 type (diameter 20 mm, height 3.2 mm) were fabricated with Sample 11 and Sample 12 as the positive electrodes and lithium metal as the counter electrode.

[0274] For the electrolyte in the electrolyte solution, 1 mol / L lithium hexafluorophosphate (LiPF 6 ) was used. For the electrolyte solution, a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) with a volume ratio of EC:DEC = 3:7 was used, and vinylene carbonate (VC) was added as an additive at 2 wt%.

[0275] A 25-μm-thick polypropylene was used for the separator.

[0276] For the positive electrode can and the negative electrode can, those made of stainless steel (SUS) were used.

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

[0278] Fig. 37 shows the results of the charge-discharge cycle test. Compared with Sample 12 without a cap layer, the positive electrode of Sample 11 with a cap layer showed extremely good charge-discharge cycle characteristics.

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

[0280] In this example, the electrochemical phenomenon occurring in the secondary battery of one aspect of the present invention is analyzed by replacing it with an equivalent circuit as shown in Fig. 38A.

[0281] Here, Rs is the electrical resistance of the electrode and the resistance of the electrolyte. Here, the electrical resistance of the electrode is assumed to include all the simple electrical resistances contained in the coin cell. Also, the resistance of the electrolyte refers to the ion diffusion resistance in the solution.

[0282] R1 may be denoted as Rf or Rsurface and is the high-frequency component of the impedance of the secondary battery. R1 includes the resistance of lithium ion diffusion at the positive electrode and electrolyte interface.

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

[0284] R2 may be denoted as Rct and is the low-frequency component. R2 includes the resistance of Li ions in the positive electrode active material layer (LiCoO in this example) 2 ) includes the resistance in the process of insertion / extraction (charge transfer).

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

[0286] The impedance typically results in a graph as shown in Fig. 38B. In the figure, the ranges affected by each component are indicated.

[0287] The impedance of Sample 11 is shown in Fig. 39, and the impedance of Sample 12 is shown in Fig. 40. Graphs of the second cycle and the 50th cycle are shown respectively. The measurement device used is the CELLTEST multi-channel electrochemical measurement system manufactured by Solartron. An AC voltage of 10 mV was swept from 0.001 Hz to 1 MHz. The measurement temperature was 25°C. Before impedance measurement, charging was performed to 4.2 V at 0.2C and left for 2 hours. The OCV at this time was 4.1308 V after the second cycle and 4.0607 V after 50 cycles for Sample 11. It was 4.1162 V after the second cycle and 4.0005 V after 50 cycles for Sample 12.

[0288] As shown in Fig. 40, when comparing the impedance of the second cycle and the 50th cycle in Sample 12, R1 (high-frequency component) has increased particularly significantly. Therefore, it is speculated that deterioration has occurred at the diffusion path of lithium, such as the interface between the positive electrode active material layer and the electrolyte, and some grain boundaries, etc., which is the cause of the deterioration of the charge-discharge cycle characteristics as shown in Fig. 37.

[0289] On the other hand, as shown in Fig. 39, when comparing the impedance of the second cycle and the 50th cycle in Sample 11, the increase in R1 is relatively small. Therefore, it is speculated that the formation of the film can be suppressed by the effect of the cap layer. Also, R2 (low-frequency component) has increased significantly. Therefore, it is speculated that deterioration has occurred in the crystal structure of LiCoO 2 .

Explanation of symbols

[0290] 100: Positive electrode, 101: Positive electrode active material layer, 102: Cap layer, 103: Positive electrode current collector, 104: Base 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: Base film, 215: Positive electrode current collector, 220: Separator, 221: Electrolyte solution, 222: Outer package, 223a: Lead electrode, 223b: Lead electrode, 230: Secondary battery, 231: Secondary battery< / eels> < / tem>

Claims

[Claim 1] A secondary battery having a positive electrode, a solid electrolyte, and a negative electrode, The positive electrode is 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 active material layer contains lithium cobalt oxide, The solid electrolyte comprises titanium.

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