Positive electrode for secondary battery, secondary battery and electronic device

Abstract

Provided is a secondary battery positive electrode which is less likely to experience a change in crystal structure due to charging and discharging, and thus has excellent cycle characteristics. This secondary battery positive electrode comprises n positive electrode active material layers (n is an integer of at least two), n-1 separation layers, and a positive electrode current collector layer, wherein the positive electrode active material layers and the separation layers are alternately laminated, the positive electrode active material layer has lithium, cobalt, and oxygen, and the separation layer has a titanium compound. As the titanium compound, titanium oxide and titanium nitride are preferable, and, the titanium oxide is particularly preferable.

Description

[Technical Field]

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

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

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

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

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

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2018-206747 [Patent Document 2] US Patent Application Publication No. 2010 / 0190051 Summary of the Invention [Problem to be solved by the invention]

[0007] Thin-film secondary batteries have room for improvement in various aspects, such as charge / discharge characteristics, cycle characteristics, reliability, safety, cost, etc. For example, one method for increasing the discharge capacity of secondary batteries is to deepen the depth of charge.

[0008] However, when the battery is charged to a deep depth of charge, for example, 0.75 or more (lithium filling rate of 25% or less), the crystalline structure of the positive electrode active material layer is easily destroyed, and the charge / discharge capacity is likely to decrease as charge / discharge is repeated.

[0009] In view of the above, an object of one embodiment of the present invention is to provide a positive electrode for a secondary battery whose crystal structure is not easily destroyed even after repeated charge and discharge. Another object is to provide a positive electrode for a secondary battery with excellent charge and discharge cycle characteristics. Another object is to provide a positive electrode for a secondary battery with large charge and discharge capacity. Another object is to provide a positive electrode for a secondary battery in which a decrease in capacity during charge and discharge cycles is suppressed. Another object is to provide a secondary battery with excellent charge and discharge cycle characteristics. Another object is to provide a secondary battery with large charge and discharge capacity. Another object is to provide a secondary battery with high safety or reliability.

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

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

[0012] One aspect of the present invention is a positive electrode for a secondary battery, the positive electrode for the secondary battery having n layers (n is an integer of 2 or more) of positive electrode active material layers, n-1 layers of separation layers, and a positive electrode current collector layer, the positive electrode active material layers and the separation layers being alternately stacked, the positive electrode active material layers containing lithium, cobalt, and oxygen, and the separation layers containing a titanium compound.

[0013] In the above, it is preferable that the positive electrode active material layer contains lithium cobalt oxide, the separation layer contains titanium oxide, and the (001) plane of the crystal structure belonging to the space group R-3m of the positive electrode active material layer is parallel to the (100) plane of the crystal structure belonging to the space group P42 / mnm of the separation layer.

[0014] In the above, it is preferable that the positive electrode active material layer contains lithium cobalt oxide, the separation layer contains titanium nitride, and the (001) plane of the crystal structure belonging to the space group R-3m of the positive electrode active material layer is parallel to the (100) plane of the crystal structure belonging to the space group Fm-3m of the separation layer.

[0015] In the above, the positive electrode active material layer preferably contains one or more of nickel, aluminum, magnesium, and fluorine. In the above, the positive electrode active material layer preferably contains nickel, aluminum, magnesium, and fluorine, and when the number of cobalt atoms in the positive electrode active material layer is taken as 100, the number of nickel atoms is preferably 0.05 to 2, the number of aluminum atoms is preferably 0.05 to 2, and the number of magnesium atoms is preferably 0.1 to 6.

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

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

[0018] According to one embodiment of the present invention, a positive electrode for a secondary battery whose crystalline structure is not easily destroyed even after repeated charge and discharge can be provided. Furthermore, a positive electrode for a secondary battery having excellent charge and discharge cycle characteristics can be provided. Furthermore, a positive electrode for a secondary battery having a large charge and discharge capacity can be provided. Furthermore, a positive electrode for a secondary battery in which a decrease in capacity during charge and discharge cycles is suppressed can be provided. Furthermore, a secondary battery having excellent charge and discharge cycle characteristics can be provided. Furthermore, a secondary battery having a large charge and discharge capacity can be provided. Furthermore, a secondary battery with high safety or reliability can be provided.

[0019] According to one embodiment of the present invention, a novel substance, active material particles, a power storage device, or a manufacturing method thereof can be provided.

[0020] Note that the description of these effects does not preclude the existence of other effects. Note that one embodiment of the present invention does not necessarily have all of these effects. Note that effects other than these will become apparent from the description in the specification, drawings, claims, etc., and it is possible to extract other effects from the description in the specification, drawings, claims, etc. [Brief explanation of the drawings]

[0021] 1A and 1B are perspective views of a positive electrode according to one embodiment of the present invention and a diagram illustrating a stacked structure of the positive electrode according to one embodiment of the present invention. FIG. 2 illustrates a stacked structure of a positive electrode according to one embodiment of the present invention. 3A and 3B illustrate a crystal structure of a positive electrode of one embodiment of the present invention. 4A to 4E illustrate a crystal structure of a positive electrode of one embodiment of the present invention. 5A to 5E illustrate a crystal structure of a positive electrode of one embodiment of the present invention. 6A and 6B illustrate a crystal structure of a positive electrode of one embodiment of the present invention. 7A to 7E illustrate a crystal structure of a positive electrode of one embodiment of the present invention. 8A to 8E illustrate a crystal structure of a positive electrode of one embodiment of the present invention. FIG. 9 illustrates a crystal structure of a positive electrode of one embodiment of the present invention. 10A to 10F illustrate a crystal structure of a positive electrode of one embodiment of the present invention. 11A to 11E are diagrams illustrating the crystal structure of the positive electrode of the comparative example. 12A and 12B are graphs showing the volume change rate and the c-axis change amount of the crystal structure of the positive electrodes of one embodiment of the present invention and a comparative example, respectively. FIG. 13A is a top view illustrating one embodiment of the present invention, and FIGS. 13B to 13D are cross-sectional views illustrating one embodiment of the present invention. 14A and 14C are top views showing one embodiment of the present invention, and FIGS. 14B and 14D are cross-sectional views showing one embodiment of the present invention. FIG. 15A is a top view illustrating one embodiment of the present invention, and FIG. 15B is a cross-sectional view illustrating one embodiment of the present invention. FIG. 16A is a top view illustrating one embodiment of the present invention, and FIG. 16B is a cross-sectional view illustrating one embodiment of the present invention. FIG. 17 illustrates a manufacturing flow of a secondary battery of one embodiment of the present invention. 18A and 18B are top views illustrating one embodiment of the present invention. FIG. 19 is a cross-sectional view showing one embodiment of the present invention. FIG. 20 illustrates a manufacturing flow of a secondary battery of one embodiment of the present invention. FIG. 21 is a schematic top view of a secondary battery manufacturing apparatus. FIG. 22 is a cross-sectional view of a part of a secondary battery manufacturing apparatus. Fig. 23A is a perspective view showing an example of a battery cell, Fig. 23B is a perspective view of a circuit, and Fig. 23C is a perspective view of the battery cell and the circuit stacked together. Fig. 24A is a perspective view showing an example of a battery cell, Fig. 24B is a perspective view of a circuit, and Figs. 24C and 24D are perspective views of a battery cell and a circuit superimposed on each other. Fig. 25A is a perspective view of a battery cell, and Fig. 25B is a diagram showing an example of an electronic device. 26A to 26C are diagrams showing examples of electronic devices. 27A to 27C are diagrams showing examples of electronic devices. Fig. 28A is a schematic diagram of an electronic device according to one embodiment of the present invention, Fig. 28B is a diagram showing a part of the system, and Fig. 28C is an example of a perspective view of a portable data terminal used in the system. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it will be readily understood by those skilled in the art that various modifications can be made to the embodiments and details. Furthermore, the present invention should not be interpreted as being limited to the description of the embodiments shown below.

[0023] Furthermore, in this specification and the like, Miller indices are used to represent crystal planes and directions. Individual planes indicating crystal planes are represented in parentheses. In crystallography, crystal planes, directions, and space groups are represented by placing a superscript bar above the numbers, but in this specification and the like, due to restrictions on notation in applications, numbers may be represented by placing a - (minus sign) before them instead of placing a bar above them.

[0024] In this specification, the layered rock-salt type crystal structure of a composite oxide containing lithium and a transition metal refers to a crystal structure having a rock-salt type ion arrangement in which cations and anions are alternately arranged, and in which the transition metal and lithium are regularly arranged to form a two-dimensional plane, allowing two-dimensional diffusion of lithium. Defects such as cation or anion deficiencies may also be present. Furthermore, strictly speaking, the layered rock-salt type crystal structure may have a distorted rock-salt type crystal lattice structure.

[0025] In this specification and the like, the rock salt type crystal structure refers to a structure in which cations and anions are arranged alternately, and it is also possible for there to be a deficiency of cations or anions.

[0026] In this specification, the theoretical capacity of a positive electrode active material refers to the amount of electricity when all of the intercalable lithium contained in the positive electrode active material is deintercalated. For example, the theoretical capacity of LiCoO2 is 274 mAh / g, the theoretical capacity of LiNiO2 is 274 mAh / g, and the theoretical capacity of LiMn2O4 is 148 mAh / g.

[0027] In this specification and the like, the depth of charge when all intercalable and deintercalable lithium has been intercalated is defined as 0, and the depth of charge when all intercalable and deintercalable lithium contained in the positive electrode active material has been deintercalated is defined as 1. It may also be said that the lithium filling rate when all intercalable and deintercalable lithium has been intercalated is 100%, and the lithium filling rate when all intercalable and deintercalable lithium contained in the positive electrode active material has been deintercalated is defined as 0%.

[0028] In this specification, the term "surfaces are parallel" does not only mean that they are mathematically strictly parallel, but also means that the difference in angle between the surfaces is 5° or less, more preferably 2.5° or less.

[0029] (Embodiment 1) A positive electrode for a secondary battery according to one embodiment of the present invention and a crystal structure of the positive electrode for the secondary battery will be described with reference to FIGS.

[0030] FIG. 1A is a perspective view of a positive electrode 100 according to one embodiment of the present invention. The positive electrode 100 includes n positive electrode active material layers 101, n-1 separation layers 102, and a positive electrode current collector layer 103. n is an integer of 2 or greater. FIG. 1A illustrates the case where n=4. The positive electrode active material layers 101 and separation layers 102 are alternately stacked. The positive electrode 100 is formed on a substrate 110.

[0031] The separation layer 102 is provided between the positive electrode active material layers 101 and has the function of stabilizing the crystal structure of the positive electrode active material layers 101 .

[0032] Fig. 1B is a diagram illustrating region 100a shown in Fig. 1A. Region 100a is a region having one positive electrode active material layer 101 and two separation layers 102 sandwiching it.

[0033] The separation layer 102 has a titanium compound TiX. X is an anion including oxygen, nitrogen, etc. That is, the separation layer 102 has, for example, titanium oxide, titanium nitride, titanium oxide partially substituted with nitrogen, titanium nitride partially substituted with oxygen, or titanium oxynitride (TiOxNy, 0 < x < 2, 0 < y < 1). Titanium and oxygen are materials that can be contained in the solid electrolyte. Therefore, titanium oxide is particularly suitable as the separation layer 102.

[0034] The positive electrode active material layer 101 has lithium, a transition metal M, and oxygen. It can be said that the positive electrode active material layer 101 has a composite oxide containing lithium and the transition metal M.

[0035] As the transition metal M included in the positive electrode active material layer 101, a metal that can form a layered rock salt type composite oxide belonging to the space group R-3m together with lithium is used. As the transition metal M, for example, one or more of manganese, cobalt, and nickel can be used. That is, only cobalt can be used as the transition metal included in the positive electrode active material layer 101, only nickel can be used, two kinds of cobalt and manganese, or two kinds of cobalt and nickel can be used, or three kinds of cobalt, manganese, and nickel can be used. That is, the positive electrode active material layer 101 can have a composite oxide containing lithium and the transition metal M, such as lithium cobaltate, lithium nickelate, lithium cobaltate in which part of cobalt is substituted with manganese, lithium cobaltate in which part of cobalt is substituted with nickel, lithium nickel-manganese-cobaltate, etc.

[0036] Furthermore, the positive electrode active material layer 101 may contain elements other than the transition metal M, such as magnesium, fluorine, and aluminum, in addition to the above. These elements may further stabilize the crystal structure of the positive electrode active material layer 101. That is, the positive electrode active material layer 101 may contain lithium cobalt oxide to which magnesium and fluorine have been added, lithium nickel-cobalt oxide to which magnesium and fluorine have been added, lithium cobalt-aluminate to which magnesium and fluorine have been added, nickel-cobalt-lithium aluminum oxide, nickel-cobalt-lithium aluminum oxide, or nickel-cobalt-lithium aluminum oxide to which magnesium and fluorine have been added.

[0037] When the positive electrode active material layer 101 contains lithium, cobalt, nickel, aluminum, magnesium, oxygen, and fluorine, the number of nickel atoms is preferably, for example, 0.05 to 2, more preferably 0.1 to 1.5, and even more preferably 0.1 to 0.9, relative to the number of cobalt atoms contained in the positive electrode active material layer 101 taken as 100. The number of aluminum atoms is preferably, for example, 0.05 to 2, more preferably 0.1 to 1.5, and even more preferably 0.1 to 0.9, relative to the number of cobalt atoms contained in the positive electrode active material layer 101 taken as 100. The number of magnesium atoms is preferably, for example, 0.1 to 6, more preferably 0.3 to 3, relative to the number of cobalt atoms contained in the positive electrode active material layer 101 taken as 1. Furthermore, the number of fluorine atoms is preferably, for example, 2 to 3.9, relative to the number of magnesium atoms contained in the positive electrode active material layer 101 taken as 1.

[0038] As the positive electrode current collector layer 103, materials with high conductivity such as metals like gold, platinum, aluminum, titanium, copper, magnesium, iron, cobalt, nickel, zinc, germanium, indium, silver, palladium, and alloys thereof can be used. Further, nitrides, oxides, etc. of these metals may also be used. For example, titanium nitride has sufficient conductivity and has a rock-salt type crystal structure. Therefore, for the same reason as the content described later using FIGS. 9 and 10, titanium nitride is particularly preferable as the positive electrode current collector layer 103 when a material having a layered rock-salt type crystal structure is used for the positive electrode active material layer 101. Also, as the positive electrode current collector layer 103, aluminum added with elements such as silicon, titanium, neodymium, scandium, molybdenum, etc. to improve heat resistance can be used. Further, 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.

[0039] Also, the positive electrode 100 of one aspect of the present invention may have a cap layer 105 as shown in FIG. 2. The cap layer 105 is provided on the positive electrode active material layer 101_n and has a function of stabilizing the crystal structure of the positive electrode active material layer 101. The cap layer 105 has a titanium compound TiX. X is an anion including oxygen, nitrogen, etc. That is, the cap layer 105 has, for example, titanium oxide, titanium nitride, titanium oxide partially substituted with nitrogen, titanium nitride partially substituted with oxygen, or titanium oxynitride (TiOxNy, 0 < x < 1, 0 < y < 1). The cap layer 105 preferably has titanium oxide in particular.

[0040] [Crystal Structure of One Aspect of the Present Invention] FIGS. 3A and 3B are diagrams for explaining an example of the crystal structure of the positive electrode of one aspect of the present invention. Hereinafter, for clarity of explanation, a region 100a which is a part of the positive electrode 100 as shown in FIG. 1B will be described. Also, it will be described assuming that the transition metal M is cobalt.

[0041] 3A shows a case where the positive electrode active material layer 101 contains lithium cobalt oxide and has a layered rock-salt crystal structure belonging to the space group R-3m, and the separation layer 102 contains titanium oxide and has a rutile crystal structure belonging to the space group P42 / mnm. In this case, as shown in FIG. 3A, the positive electrode 100 is preferably stacked such that the (001) plane of the layered rock-salt crystal structure belonging to the space group R-3m of the positive electrode active material layer 101 is parallel to the (100) plane of the rutile crystal structure belonging to the space group P42 / mnm of the separation layer 102. Stacking with such a plane orientation effectively stabilizes the crystal structure of the separation layer 102, and the crystal structure of the positive electrode 100 is less likely to collapse even when repeatedly charged and discharged to a depth of charge of 0.75 or more.

[0042] 3B, the positive electrode active material layer 101 may have a crystal structure belonging to the space group P-3m1. In this case as well, the positive electrode 100 is preferably stacked such that the (001) plane of the crystal structure belonging to the space group P-3m1 of the positive electrode active material layer 101 and the (100) plane of the rutile-type crystal structure belonging to the space group P42 / mnm of the separation layer 102 are parallel to each other.

[0043] We will explain the results of calculating the optimized crystal structure at various depths of charge (Li filling rate) for the stacked structure described above. There are five depths of charge: depth of charge 0 (Li filling rate 100%), depth of charge 0.75 (Li filling rate 25%), depth of charge 0.875 (Li filling rate 12.5%), depth of charge 0.9375 (Li filling rate 6.25%), and depth of charge 1 (Li filling rate 0). Other calculation conditions are shown in Table 1.

[0044] [Table 1]

[0045] 4A to 4E show calculation results for the case where the positive electrode active material layer 101 has a layered rock-salt crystal structure belonging to the space group R-3m as shown in Fig. 3A. The regions, elements, crystal structures, and the like in Fig. 4A to 4E can be seen in Fig. 3A.

[0046] Figure 4A shows the calculation results for a charge depth of 0 (Li filling rate 100%), Figure 4B for a charge depth of 0.75 (Li filling rate 25%), Figure 4C for a charge depth of 0.875 (Li filling rate 12.5%), Figure 4D for a charge depth of 0.9375 (Li filling rate 6.25%), and Figure 4E for a charge depth of 1 (Li filling rate 0%).

[0047] 5A to 5E show calculation results for the case where the positive electrode active material layer 101 has a crystal structure belonging to the space group P-3m1 as shown in Fig. 3B. The regions, elements, crystal structures, and the like in Fig. 5A to 5E can be understood by referring to the description in Fig. 3B.

[0048] Figure 5A shows the calculation results for a charge depth of 0 (Li filling rate 100%), Figure 5B for a charge depth of 0.75 (Li filling rate 25%), Figure 5C for a charge depth of 0.875 (Li filling rate 12.5%), Figure 5D for a charge depth of 0.9375 (Li filling rate 6.25%), and Figure 5E for a charge depth of 1 (Li filling rate 0).

[0049] As shown in FIGS. 4A to 4E and 5A to 5E, the layers of CoO2 octahedra remain stable at any charging depth.

[0050] 3A and 3B, the crystal structure of the positive electrode active material layer 101 is stable even at a deep charge depth. As a result, the charge / discharge capacity is less likely to decrease even when charge / discharge is repeated at a deep charge depth, and the positive electrode exhibits excellent cycle characteristics.

[0051] Another example of the crystal structure of the positive electrode of one embodiment of the present invention will be described with reference to FIGS. 6A and 6B.

[0052] 6A shows a case where the positive electrode active material layer 101 contains lithium cobalt oxide and has a layered rock-salt crystal structure belonging to the space group R-3m, and the separation layer 102 contains titanium oxide and has a rutile crystal structure belonging to the space group P42 / mnm. In this case, as shown in FIG. 3A, the positive electrode 100 is preferably stacked so that the (104) plane of the layered rock-salt crystal structure belonging to the space group R-3m of the positive electrode active material layer 101 and the (100) plane of the rutile crystal structure belonging to the space group P42 / mnm of the separation layer 102 are parallel to each other.

[0053] 6B, the positive electrode active material layer 101 may have a crystal structure belonging to the space group P-3m1. In this case as well, the positive electrode 100 is preferably stacked such that the (104) plane of the crystal structure belonging to the space group P-3m1 of the positive electrode active material layer 101 and the (100) plane of the rutile-type crystal structure belonging to the space group P42 / mnm of the separation layer 102 are parallel to each other.

[0054] In the case where the layers are stacked as described above, the results of calculating the optimized crystal structure will be described in the same manner as in FIGS. 4A to 5E.

[0055] 7A to 7E show calculation results for the case where the positive electrode active material layer 101 has a layered rock-salt crystal structure belonging to the space group R-3m as shown in Fig. 6A. The regions, elements, crystal structures, etc. in Fig. 7A to 7E can be seen in Fig. 6A.

[0056] Figure 7A shows the calculation results for a charge depth of 0 (Li filling rate 100%), Figure 7B for a charge depth of 0.75 (Li filling rate 25%), Figure 7C for a charge depth of 0.875 (Li filling rate 12.5%), Figure 7D for a charge depth of 0.9375 (Li filling rate 6.25%), and Figure 7E for a charge depth of 1 (Li filling rate 0).

[0057] 8A to 8E show calculation results for the case where the positive electrode active material layer 101 has a crystal structure belonging to the space group P-3m1 as shown in Fig. 6B. The regions, elements, crystal structures, and the like in Fig. 8A to 8E can be understood by referring to the description in Fig. 6B.

[0058] Figure 8A shows the calculation results for a charge depth of 0 (Li filling rate 100%), Figure 8B for a charge depth of 0.75 (Li filling rate 25%), Figure 8C for a charge depth of 0.875 (Li filling rate 12.5%), Figure 8D for a charge depth of 0.9375 (Li filling rate 6.25%), and Figure 8E for a charge depth of 1 (Li filling rate 0).

[0059] As shown in FIGS. 7A to 7E and 8A to 8E, the layers of CoO2 octahedra remain stable at any charging depth.

[0060] 6A and 6B, the crystal structure of the positive electrode active material layer 101 is stable even at a deep charge depth. As a result, the charge / discharge capacity is less likely to decrease even when charge / discharge is repeated at a deep charge depth, and the positive electrode exhibits excellent cycle characteristics.

[0061] Another example of the crystal structure of the positive electrode of one embodiment of the present invention will be described with reference to FIG.

[0062] 9 shows a case where positive electrode active material layer 101 contains lithium cobalt oxide and has a layered rock-salt crystal structure belonging to space group R-3m, and separation layer 102 contains titanium nitride and has a rock-salt crystal structure belonging to space group Fm-3m. In this case, as shown in FIG. 9, positive electrode 100 is preferably stacked such that the (104) plane of the layered rock-salt crystal structure belonging to space group R-3m of positive electrode active material layer 101 and the (100) plane of the rock-salt crystal structure belonging to space group Fm-3m of separation layer 102 are parallel to each other.

[0063] For the above-described stacked structures, the results of calculations of optimized crystal structures similar to those of FIGS. 4 and 5 are shown in FIGS. 10A to 10F. The calculation conditions are shown in Table 2. The regions, elements, crystal structures, etc. of FIGS. 10A to 10F can be referenced from the description of FIG. 9.

[0064] [Table 2]

[0065] Figure 10A shows the calculation results for a charge depth of 0 (Li filling rate 100%), Figure 10B shows the calculation results for a charge depth of 0.5 (Li filling rate 50%), Figure 10C shows the calculation results for a charge depth of 0.75 (Li filling rate 25%), Figure 10D shows the calculation results for a charge depth of 0.875 (Li filling rate 12.5%), Figure 10E shows the calculation results for a charge depth of 0.9375 (Li filling rate 6.25%), and Figure 10F shows the calculation results for a charge depth of 1 (Li filling rate 0).

[0066] As shown in the areas surrounded by dotted lines in Figures 10D and 10E, at a charge depth of 0.875 or higher, cobalt migrates to the lithium sites in some areas, causing the layers made up of CoO2 octahedra to collapse, but the layers made up of CoO2 octahedra are maintained in most other areas.

[0067] 9, the crystal structure of the positive electrode active material layer 101 is stable even at a deep charge depth. As a result, the charge / discharge capacity is less likely to decrease even when the positive electrode 100 is repeatedly charged and discharged at a deep charge depth, and the positive electrode exhibits excellent cycle characteristics.

[0068] [Crystal structure of comparative example] Next, as a comparative example, a positive electrode in which the positive electrode active material layer 101 and the separation layer 102 are stacked in a combination other than the above will be described with reference to FIGS. 11A to 11E.

[0069] 11A to 11E show a case where the positive electrode active material layer 101 contains lithium cobalt oxide and has a layered rock-salt crystal structure belonging to the space group R-3m, and the separation layer 102 contains titanium nitride and has a rock-salt crystal structure belonging to the space group Fm-3m. The positive electrode active material layer 101 is laminated so that the (001) plane of the layered rock-salt crystal structure belonging to the space group R-3m is parallel to the (111) plane of the sodium chloride crystal structure belonging to the space group Fm-3m of the separation layer 102. Five optimized crystal structures were calculated: a charge depth of 0 (Li filling rate 100%), a charge depth of 0.75 (Li filling rate 25%), a charge depth of 0.875 (Li filling rate 12.5%), a charge depth of 0.9375 (Li filling rate 6.25%), and a charge depth of 1 (Li filling rate 0).

[0070] Figure 11A shows the calculation results for a charge depth of 0 (Li filling rate 100%), Figure 11B for a charge depth of 0.75 (Li filling rate 25%), Figure 11C for a charge depth of 0.875 (Li filling rate 12.5%), Figure 11D for a charge depth of 0.9375 (Li filling rate 6.25%), and Figure 11E for a charge depth of 1 (Li filling rate 0).

[0071] As shown in the dotted-line areas in Figures 11B to 11E, at a charge depth of 0.75 or greater, cobalt migrates to the lithium sites, causing the CoO2 octahedron layer to collapse. Compared to Figure 10, the crystal structure begins to collapse at a shallower charge depth, and over a wider area. Furthermore, the crystal structure tends to collapse more easily when the CoO2 octahedron layer contacts titanium nitride than when the lithium layer contacts titanium nitride.

[0072] Therefore, it is considered that a positive electrode formed by stacking the crystal structures shown in FIG. 11 is less stable and has poorer cycle characteristics than a positive electrode according to one embodiment of the present invention.

[0073] [Volume change rate] Next, we will explain the results of calculating the volume change at various depths of charge (Li filling rates) for the following four patterns of positive electrodes.

[0074] (1) A positive electrode according to one embodiment of the present invention, as shown in Figure 3A, is constructed by stacking lithium cobalt oxide (LiCoO) with a layered rock-salt crystal structure belonging to the space group R-3m and titanium dioxide (TiO) with a rutile crystal structure belonging to the space group P42 / mnm so that their (001) planes are parallel to each other (hereinafter referred to as LCO(R-3m)\TiO).

[0075] (2) A positive electrode according to one embodiment of the present invention, as shown in Figure 9. The (104) plane of lithium cobalt oxide, which has a layered rock-salt crystal structure belonging to the space group R-3m, and the (100) plane of titanium nitride, which has a rock-salt crystal structure belonging to the space group Fm-3m, are stacked parallel to each other (hereinafter referred to as LCO\TiN).

[0076] (3) A comparative example is a positive electrode using titanium metal for the separation layer 102. The (104) plane of lithium cobalt oxide, which has a layered rock-salt crystal structure belonging to the space group R-3m, and the (001) plane of titanium, which has a hexagonal close-packed structure belonging to the space group P63 / mmc, are stacked parallel to each other (hereinafter referred to as LCO\Ti).

[0077] (4) A comparative example of a positive electrode without a separation layer. This electrode is made of only lithium cobalt oxide (hereinafter referred to as LCO) with a layered rock-salt crystal structure belonging to the space group R-3m.

[0078] Figure 12A shows the volume change rate relative to the volume at a charge depth of 0 (100% Li charge). Regardless of whether or not the separation layer 102 is present, all positive electrodes tend to rapidly decrease in volume when the charge depth reaches 0.8 or higher (20% or lower Li charge). However, at a charge depth of 0.875 (12.5% ​​Li charge), the volumes of LCO(R-3m)\TiO2 and LCO(R-3m)\TiN, which are embodiments of the present invention, are between -2% and 1% of the reference volume. In particular, the volume change rate of LCO(R-3m)\TiO2, which is an embodiment of the present invention, is very small at charge depths of 0 or higher but less than 0.8 (20% to 100% Li charge). Therefore, the use of the LCO(R-3m)\TiO2 structure is more suitable as an embodiment of the present invention. On the other hand, the volume change rates of the comparative examples, LCO(R-3m)\Ti and LCO, are less than -3% of the reference volume, which is larger than the volume change rate of the embodiment of the present invention.

[0079] [C-axis change] Next, the results of calculating the c-axis change for the same four patterns of positive electrodes as in the calculation of the volume change rate are shown in Figure 12B. Regardless of whether or not the separation layer 102 is present, all positive electrodes tend to have a shorter c-axis when the charge depth reaches 0.8 or higher. This is consistent with the trend in the volume change rate, and it is clear that the length in the c-axis direction contributes significantly to the volume change. Again, at a charge depth of 0.875 (Li filling rate of 12.5%), the c-axis change for LCO(R-3m)\TiO2 and LCO\TiN, which are embodiments of the present invention, remains between the reference value of -1 Å and 0 Å. On the other hand, the c-axis change for the comparative example, LCO\Ti, is significantly larger at about -3 Å. Note that 1 Å = 10 -10 m.

[0080] Thus, the positive electrode according to one embodiment of the present invention is a stable positive electrode that undergoes little volume change even when charged to a deep depth.

[0081] Although the positive electrode 100 of one embodiment of the present invention has the above-described crystal structure, the entire positive electrode 100 does not necessarily have to have the above-described crystal structure. The positive electrode 100 may include other crystal structures, or may be partially amorphous. The crystal structure of the positive electrode 100 described in this embodiment can be estimated using XRD. However, the crystal structure may not be exactly as described above and may be distorted. The crystal planes referred to in this embodiment only indicate the plane orientation and do not precisely limit the interplanar spacing.

[0082] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0083] (Embodiment 2) In this embodiment mode, a secondary battery having the positive electrode for the secondary battery described in Embodiment 1 and a manufacturing method thereof will be described.

[0084] [Secondary battery configuration] 13A and 13B show a secondary battery 200, which is an example of the secondary battery of one embodiment of the present invention, in which Fig. 13A is a top view and Fig. 13B is a cross-sectional view taken along line AA' in Fig. 13A.

[0085] The secondary battery 200 is a thin-film battery, and as shown in FIG. 13B, the positive electrode 100 described in the previous embodiment is formed on a substrate 110, a solid electrolyte layer 203 is formed on the positive electrode 100, and a negative electrode 210 is formed on the solid electrolyte layer 203. FIG. 13B shows a case where the positive electrode 100 has two positive electrode active material layers 101 on a positive electrode current collector layer 103 and one separation layer 102 sandwiched between them (i.e., a case where n = 2). The negative electrode 210 has a negative electrode active material layer 204 and a negative electrode current collector layer 205. Furthermore, it is preferable that the secondary battery 200 has a protective layer 206 formed on the positive electrode 100, the solid electrolyte layer 203, and the negative electrode 210.

[0086] The films forming these layers can be formed using a metal mask. The positive electrode current collector layer 103, the positive electrode active material layer 101, the separation layer 102, the solid electrolyte layer 203, the negative electrode active material layer 204, the negative electrode current collector layer 205, and the protective layer 206 can be selectively formed by sputtering. Alternatively, the solid electrolyte layer 203 may be selectively formed by co-evaporation using a metal mask.

[0087] 13A, a negative electrode terminal can be formed by exposing a portion of the negative electrode current collector layer 205. Also, a positive electrode terminal can be formed by exposing a portion of the positive electrode current collector layer 103. The area other than the negative electrode terminal and the positive electrode terminal is preferably covered with a protective layer 206.

[0088] 13A and 13B illustrate a configuration in which the solid electrolyte layer 203, the negative electrode active material layer 204, and the negative electrode current collector layer 205 are stacked in this order on the positive electrode 100 including the positive electrode current collector layer 103, the positive electrode active material layer 101, and the separation layer 102; however, one embodiment of the present invention is not limited thereto.

[0089] 13C , a secondary battery 200 may have a positive electrode 100 having an underlayer 104 between a positive electrode current collector layer 103 and a positive electrode active material layer 101. The underlayer 104 preferably has high crystallinity and has the function of controlling the orientation of the positive electrode active material layer 101. The material of the underlayer 104 may be the same as that of the separation layer 102.

[0090] Similarly to the positive electrode, the negative electrode of the secondary battery of one embodiment of the present invention may also have a stacked structure of active material layers and separation layers. For example, as shown in FIG. 13D , a secondary battery 200 may have a negative electrode 210 including m negative electrode active material layers 204 and (m+1) separation layers 209. m is an integer of 2 or greater. FIG. 13D illustrates the case where m=2. As shown in FIG. 13D , the negative electrode 210 preferably includes separation layers 209 between the negative electrode active material layers 204 and the negative electrode current collector layer 205 and between the negative electrode active material layers 204 and the solid electrolyte layer 203.

[0091] The material and manufacturing method of separation layer 209 can be referred to the description of separation layer 102. Negative electrode 210 having separation layer 209 is a negative electrode that exhibits excellent cycle characteristics, with little change in volume even when absorbing lithium ions, and is resistant to cracking or crumbling.

[0092] 14A and 14B, a secondary battery of one embodiment of the present invention may be a secondary battery 201 including a negative electrode 211 that serves both as a negative electrode current collector layer and a negative electrode active material layer. FIG. 14A is a top view of the secondary battery 201, and FIG. 14B is a cross-sectional view taken along line B-B' in FIG. 14A. By using the negative electrode 211 that serves both as a negative electrode current collector layer and a negative electrode active material layer, a secondary battery can be manufactured with simplified manufacturing processes and high productivity. Furthermore, a secondary battery with high energy density can be manufactured.

[0093] Although the secondary battery in which the positive electrode 100, the solid electrolyte layer 203, and the negative electrode 210 are provided in this order on the substrate has been described above, one embodiment of the present invention is not limited to this. As shown in FIGS. 14C and 14D , a secondary battery of one embodiment of the present invention may be a secondary battery 202 in which the solid electrolyte layer 203 and the positive electrode 100 are stacked on the negative electrode 210. In this case, the positive electrode 100 preferably has a cap layer 105. FIG. 14C is a top view of the secondary battery 202, and FIG. 14D is a cross-sectional view taken along line C-C' in FIG. 14C .

[0094] Although the above description has been given of a secondary battery in which not only the positive electrode but also the solid electrolyte layer and the negative electrode are formed as thin films, one embodiment of the present invention is not limited thereto. Another embodiment of the present invention may be a secondary battery having an electrolytic solution. Another embodiment of the present invention may be a secondary battery having an electrolytic solution and a negative electrode that also serves as a negative electrode current collector layer and a negative electrode active material layer. Another embodiment of the present invention may be a secondary battery having a negative electrode prepared by coating a powdered negative electrode active material on a negative electrode current collector.

[0095] A secondary battery 230 having an electrolyte solution is shown in Figures 15A and 15B, where Figure 15A is a top view and Figure 15B is a cross-sectional view taken along line DD' in Figure 15A.

[0096] 15B, secondary battery 230 has positive electrode 100 on substrate 110, negative electrode 212 on substrate 111, separator 220, electrolyte 221, and exterior body 222. Negative electrode current collector layer 205, negative electrode active material layer 204, and separation layer 209 of negative electrode 212 are formed as thin films.

[0097] 15A , the secondary battery 230 has lead electrodes 223a and 223b. The lead electrode 223a is electrically connected to the positive electrode current collector layer 103. The lead electrode 223b is electrically connected to the negative electrode current collector layer 205. Portions of the lead electrodes 223a and 223b are drawn out of the exterior body 222.

[0098] 16A and 16B show a secondary battery 231 having an electrolyte solution and a negative electrode 211 that serves both as a negative electrode current collector layer and a negative electrode active material layer. Fig. 16A is a top view, and Fig. 16B is a cross-sectional view taken along line E-E' in Fig. 16A.

[0099] 16B, a secondary battery 231 includes a positive electrode 100 on a substrate 110, a negative electrode 211 serving both as a negative electrode current collector layer and a negative electrode active material layer, a separator 220, an electrolyte 221, and an exterior body 222. By using the negative electrode 211 serving both as a negative electrode current collector layer and a negative electrode active material layer, the manufacturing process can be simplified, resulting in a secondary battery with high productivity. In addition, a secondary battery with high energy density can be obtained.

[0100] [Production method] Next, an example of the flow of a method for manufacturing the secondary battery 200 shown in FIGS. 13A and 13B will be described with reference to FIG.

[0101] First, the positive electrode current collector layer 103 is formed on the substrate 110 (S1). The film formation method can be sputtering, vapor deposition, etc. Alternatively, a conductive substrate may be used as the current collector.

[0102] Furthermore, a ceramic substrate, a glass substrate, a resin substrate, a silicon substrate, a metal substrate, or the like can be used as the substrate 110. If a flexible material is used as the substrate 110, a flexible thin-film secondary battery can be manufactured.

[0103] Next, the positive electrode active material layer 101 is formed (S2). The positive electrode active material layer 101 can be formed by sputtering using a sputtering target whose main component is an oxide containing lithium and one or more of manganese, cobalt, and nickel. For example, a sputtering target whose main component is lithium cobalt oxide (LiCoO2, LiCo2O4, etc.), a sputtering target whose main component is lithium manganese oxide (LiMnO2, LiMn2O4, etc.), or a sputtering target whose main component is lithium nickel oxide (LiNiO2, LiNi2O4, etc.) can be used. Alternatively, the positive electrode active material layer 101 may be formed by vacuum deposition.

[0104] In addition, in the sputtering method, selective film formation is possible by using a metal mask. Alternatively, the positive electrode active material layer 101 may be patterned by selectively removing the resist mask or the like by dry etching or wet etching.

[0105] At this time, it is preferable to form the film so that the (104) plane of the layered rock-salt crystal structure belonging to the space group R-3m of the positive electrode active material layer 101 is parallel to the substrate 110. To achieve this, it is preferable to adjust the crystal orientation of the substrate 110, the film formation conditions (output, atmosphere including oxygen partial pressure, temperature, etc.), the magnetic field, etc.

[0106] Furthermore, in order to form the positive electrode active material layer 101 containing magnesium, fluorine, aluminum, etc., a sputtering target containing magnesium, fluorine, aluminum, etc. in addition to lithium and one or more of manganese, cobalt, and nickel may be used for film formation. Alternatively, after forming a film using a sputtering target containing as its main component an oxide containing lithium and one or more of manganese, cobalt, and nickel, magnesium, fluorine, aluminum, etc. may be deposited by vacuum evaporation and annealed.

[0107] Next, the separation layer 102 is formed on the positive electrode active material layer 101 (S3). The separation layer 102 can be formed by sputtering, vapor deposition, or the like.

[0108] For example, when titanium nitride is used as the separation layer 102, the titanium nitride can be deposited by reactive sputtering using a titanium target and nitrogen gas. When the separation layer 102 has a crystal structure belonging to the space group Fm-3m, like titanium nitride, it is preferable to deposit the layer so that its (100) plane is parallel to the (104) plane of the layered rock-salt crystal structure belonging to the space group R-3m of the positive electrode active material layer 101. To achieve this, it is preferable to adjust the deposition conditions (output, atmosphere including oxygen partial pressure, temperature, etc.), magnetic field, etc.

[0109] Furthermore, when titanium oxide is used as the separation layer 102, a titanium nitride film can be formed by reactive sputtering using a titanium target and oxygen gas. When the separation layer 102 has a crystal structure belonging to the space group P42 / mnm, such as titanium oxide, it is preferable to form the film so that its (100) plane is parallel to the (104) plane of the layered rock-salt crystal structure belonging to the space group R-3m of the positive electrode active material layer 101. To achieve this, it is preferable to adjust the film formation conditions (output, atmosphere including oxygen partial pressure, temperature, etc.), magnetic field, etc.

[0110] Next, the positive electrode active material layer 101 is formed again on the separation layer 102 (S4).

[0111] S3 and S4 are performed n-1 times (n is an integer of 2 or more). In this way, a positive electrode having n (n is an integer of 2 or more) positive electrode active material layers and n-1 separation layers can be produced.

[0112] The positive electrode active material layer 101 and the separation layer 102 are preferably formed at a high temperature (500°C or higher, more preferably 600°C or higher). Alternatively, the positive electrode active material layer 101 and the separation layer 102 are preferably annealed (500°C or higher, more preferably 600°C or higher) after being formed. By using such a manufacturing method, a positive electrode 100 with better crystallinity can be manufactured.

[0113] Next, the solid electrolyte layer 203 is formed on the positive electrode active material layer 101 (S5). The material of the solid electrolyte layer is Li3PO 4、 Li A PO (4-B) Ny, Li 0.35 La 0.55 TiO3, La (2 / 3-x) Li 3A TiO 3、 LiNb (1-A) Ta (A) WO6, Li7La3Zr2O 12 ,Li (1+A) Al (A) Ti (2-A) (PO4)3, Li (1+A) Al (A) Ge(2-A) (PO4)3, LiNbO2, etc. can be mentioned. Note that A > 0 and B > 0. As the film formation method, sputtering method, evaporation method, etc. can be used. Also, SiO C (0 < C ≤ 2) can also be used as the solid electrolyte layer 203. SiO C (0 < C ≤ 2) is used as the solid electrolyte layer 203, and further, SiO C (0 < C ≤ 2) may be used as the negative electrode active material layer 204. 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. By adopting such a configuration, conductive ions (especially lithium ions) easily diffuse in the solid electrolyte layer 203, and conductive ions (especially lithium ions) easily 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, the secondary battery can be easily manufactured.

[0114] Also, the solid electrolyte layer 203 may have a laminated structure. When laminating, a material obtained by adding nitrogen to lithium phosphate (Li3PO4) (also called Li3PO (4-Z) N Z :LiPON) may be laminated. Note that Z > 0.

[0115] Also, it is preferable to use a compound containing titanium for the solid electrolyte layer 203. Since the separation layer 102 of the positive electrode 100 has titanium, if a material having titanium is also used for the solid electrolyte layer 203, the secondary battery can be easily manufactured.

[0116] Next, the negative electrode active material layer 204 is formed on the solid electrolyte layer 203 (S6). The negative electrode active material layer 204 can be formed by sputtering or the like, and can be a film mainly composed of silicon, a film mainly composed of carbon, a titanium oxide film, a vanadium oxide film, an indium oxide film, a zinc oxide film, a tin oxide film, a nickel oxide film, or the like. Films that can be alloyed with Li, such as tin, gallium, or aluminum, can also be used. Metal oxide films that can be alloyed with these can also be used. Lithium titanium oxide (Li4Ti5O 12 , LiTi2O4, etc.) may be used, among which a film containing silicon and oxygen is preferable. A Li metal film may also be used as the negative electrode active material layer 204. The Li metal film can also be used as a negative electrode that serves as both a negative electrode current collector layer and a negative electrode active material layer.

[0117] Next, the negative electrode current collector layer 205 is formed on the negative electrode active material layer 204 (S7). The material of the negative electrode current collector layer 205 is one or more conductive materials selected from Al, Ti, Cu, Au, Cr, W, Mo, Ni, Ag, etc. Sputtering, vapor deposition, etc. can be used as the film formation method. In the sputtering method, a metal mask can be used to selectively form the film. Alternatively, the conductive film may be patterned by selectively removing the resist mask or the like by dry etching or wet etching.

[0118] When the positive electrode current collector layer 103 or the negative electrode current collector layer 205 is formed by sputtering, it is preferable to form at least one of the positive electrode active material layer 101 and the negative electrode active material layer 204 by sputtering. The sputtering device can perform continuous film formation in the same chamber or using multiple chambers, and can also be a multi-chamber manufacturing device or an in-line manufacturing device. The sputtering method is a manufacturing method suitable for mass production using a chamber and a sputtering target. Furthermore, the sputtering method allows for thin film formation and has excellent film formation characteristics.

[0119] Next, it is preferable to form a protective layer 206 on the positive electrode 100, the solid electrolyte layer 203, and the negative electrode 210 (S8). The protective layer 206 can be made of a metal oxide containing one or more elements selected from hafnium, aluminum, gallium, yttrium, zirconium, tungsten, titanium, tantalum, nickel, germanium, neodymium, lanthanum, magnesium, etc. Silicon nitride oxide or silicon nitride can also be used. The protective layer 206 can be formed by sputtering.

[0120] Furthermore, the layers described in this embodiment are not limited to being formed by sputtering, and gas phase methods (vacuum evaporation, thermal spraying, pulsed laser deposition (PLD), ion plating, cold spray, and aerosol deposition) can also be used. The aerosol deposition (AD) method is a method of forming a film without heating the substrate. Aerosol refers to fine particles dispersed in a gas. Alternatively, CVD or ALD (Atomic Layer Deposition) can also be used.

[0121] Through the above steps, the secondary battery 200 of one embodiment of the present invention can be manufactured.

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

[0123] (Embodiment 3) In order to increase the output voltage of a thin-film secondary battery, the secondary batteries can be connected in series. While the example of a secondary battery having one cell was shown in the second embodiment, this embodiment shows an example of fabricating a thin-film secondary battery in which multiple cells are connected in series.

[0124] Fig. 18A shows a top view of the first secondary battery immediately after its formation, and Fig. 18B shows a top view of two secondary batteries connected in series. Note that in Fig. 18A and Fig. 18B, the same reference numerals are used for the same parts as in Fig. 13A shown in Embodiment 2.

[0125] Fig. 18A shows the state immediately after the deposition of the negative electrode current collector layer 205. The shape of the top surface of the negative electrode current collector layer 205 differs from that of Fig. 13A. The negative electrode current collector layer 205 shown in Fig. 18A is in contact with a part of the side surface of the solid electrolyte layer and also with the insulating surface of the substrate.

[0126] 18B, a second negative electrode active material layer is formed on a region of the negative electrode current collector layer 205 that does not overlap with the first negative electrode active material layer. Then, a second solid electrolyte layer 213 is formed, and a second positive electrode active material layer and a second positive electrode current collector layer 215 are formed thereon. Finally, a protective layer 206 is formed.

[0127] FIG. 18B shows a configuration in which two solid-state secondary batteries are arranged on a plane and connected in series.

[0128] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0129] (Fourth embodiment) In order to increase the output voltage or discharge capacity of the thin-film secondary battery, a multi-layer secondary battery can be formed in which multiple positive electrodes and multiple negative electrodes are stacked one on top of the other. While the second embodiment shows an example of a secondary battery that is a single-layer cell, the present embodiment shows an example of a thin-film battery that is a multi-layer cell.

[0130] 19 shows an example of a cross section of a three-layer thin-film battery. A positive electrode current collector layer 103 is formed on a substrate 110, and a positive electrode active material layer 101, a separation layer 102, a positive electrode active material layer 101, a solid electrolyte layer 203, a negative electrode active material layer 204, and a negative electrode current collector layer 205 are sequentially formed on the positive electrode current collector layer 103 to form the first cell.

[0131] Furthermore, a second negative electrode active material layer 204, a solid electrolyte layer, a positive electrode active material layer, a separation layer, a positive electrode active material layer, and a positive electrode current collector layer are sequentially formed on the negative electrode current collector layer 205 to form a second cell.

[0132] Furthermore, the third cell is constructed by sequentially forming a third layer of positive electrode active material layer, a separation layer, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector layer on the second layer of positive electrode current collector layer.

[0133] In Fig. 19, a protective layer 206 is formed last. The three-layer stack shown in Fig. 19 is configured to be connected in series to increase capacity, but it can also be connected in parallel via external wiring. Also, series and parallel or series-parallel can be selected via external wiring.

[0134] It is preferable to use the same material for the solid electrolyte layer 203, the second solid electrolyte layer, and the third solid electrolyte layer, as this reduces manufacturing costs.

[0135] FIG. 20 shows an example of a manufacturing flow for obtaining the structure shown in FIG.

[0136] In Fig. 20, in order to reduce the number of manufacturing steps, it is preferable to use a lithium cobalt oxide film as the positive electrode active material layer and a titanium film as the positive electrode current collector layer and the negative electrode current collector layer (conductive layer). By using a titanium film as the common electrode, a three-layer stacked cell can be realized with a reduced configuration.

[0137] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0138] (Embodiment 5) In this embodiment, an example of a multi-chamber manufacturing apparatus that can fully automate the manufacturing of the positive electrode current collector layer to the negative electrode current collector layer of a secondary battery is shown in FIGS. 21 and 22. The manufacturing apparatus can be suitably used for manufacturing the thin-film secondary battery of one embodiment of the present invention.

[0139] Figure 21 shows an example of a multi-chamber manufacturing apparatus equipped with gates 880, 881, 882, 883, 884, 885, 886, 887, 888, a load lock chamber 870, a mask alignment chamber 891, a first transfer chamber 871, a second transfer chamber 872, a third transfer chamber 873, multiple film formation chambers (first film formation chamber 892, second film formation chamber 874), a heating chamber 893, a second material supply chamber 894, a first material supply chamber 895, and a third material supply chamber 896.

[0140] The mask alignment chamber 891 includes at least a stage 851 and a substrate transport mechanism 852 .

[0141] 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 has a substrate transfer mechanism 854.

[0142] The first film formation chamber 892, the second film formation chamber 874, the second material supply chamber 894, the first material supply chamber 895, the third material supply chamber 896, the mask alignment chamber 891, the first transfer chamber 871, the second transfer chamber 872, and the third transfer chamber 873 are each connected to an exhaust mechanism. As the exhaust mechanism, an appropriate exhaust device may be selected depending on the intended use of each chamber, and examples include an exhaust mechanism equipped with a pump having an adsorption means such as a cryopump, a sputter ion pump, or a titanium sublimation pump, and an exhaust mechanism equipped with a turbomolecular pump and a cold trap.

[0143] The procedure for forming a film on a substrate is as follows: a substrate 850 or a substrate cassette is placed in a load lock chamber 870, and then transported to a mask alignment chamber 891 by a substrate transport mechanism 852. In the mask alignment chamber 891, a mask to be used is picked up from a plurality of masks that have been set in advance, and the mask is aligned with the substrate on a stage 851. After alignment is complete, a gate 880 is opened, and the substrate is transported to a first transport chamber 871 by the substrate transport mechanism 852. The substrate is transported to the first transport chamber 871, and the gate 881 is opened, and the substrate is transported to a second transport chamber 872 by a substrate transport mechanism 853.

[0144] The first film formation chamber 892, which is connected to the second transfer chamber 872 via a gate 882, is a sputtering film formation chamber. The sputtering film formation chamber has a mechanism that can switch between an RF power supply and a pulsed DC power supply to apply voltage to the sputtering target. Two or three types of sputtering targets can be set. In this embodiment, a single crystal silicon target, a sputtering target mainly composed of lithium cobalt oxide (LiCoO2), and a titanium target are installed. A substrate heating mechanism is installed in the first film formation chamber 892, and it is also possible to perform film formation while the heater temperature is raised to 700°C.

[0145] The negative electrode active material layer can be formed by sputtering using a single crystal silicon target. Also, SiO2 can be formed as a negative electrode by reactive sputtering using Ar gas and O2 gas. X A film made of titanium can be used as the negative electrode active material layer. A silicon nitride film can also be used as a sealing film by reactive sputtering using Ar gas and N2 gas. In addition, a positive electrode active material layer can be formed by sputtering using a sputtering target whose main component is lithium cobalt oxide (LiCoO2). A conductive film that serves as a current collector can be formed by sputtering using a titanium target. A titanium nitride film can also be formed by reactive sputtering using Ar gas and N2 gas, and used as a separation layer or base film.

[0146] When forming a positive electrode active material layer, the substrate is transported from the second transport chamber 872 to the first film formation chamber 892 with the mask and the substrate stacked thereon by the substrate transport mechanism 853, and then the gate 882 is closed and film formation is performed by sputtering. After film formation is completed, the gates 882 and 883 are opened, the substrate is transported to the heating chamber 893, and the gate 883 is closed, after which heating can be performed. For the heating treatment in the heating chamber 893, an RTA (Rapid Thermal Anneal) device, a resistance heating furnace, or a microwave heating device can be used. For the RTA device, a GRTA (Gas Rapid Thermal Anneal) device or an LRTA (Lamp Rapid Thermal Anneal) device can be used. The heating treatment in the heating chamber 893 can be performed in an atmosphere of nitrogen, oxygen, a rare gas, or dry air. The heating time is from 1 minute to 24 hours.

[0147] After the film formation or heat treatment is completed, the substrate and mask are returned to the mask alignment chamber 891, and a new mask is aligned. After alignment, the substrate and mask are transferred to the first transfer chamber 871 by the substrate transfer mechanism 852. The substrate is transferred by the lifting mechanism of the first transfer chamber 871, and after the gate 884 is opened, the substrate is transferred to the third transfer chamber 873 by the substrate transfer mechanism 854.

[0148] The second film formation chamber 874, which is connected to the third transfer chamber 873 via a gate 885, performs film formation by evaporation.

[0149] An example of the cross-sectional structure of the second film formation chamber 874 is shown in FIG. 22. FIG. 22 is a schematic cross-sectional view taken along the dotted line in FIG. 21. The second film formation chamber 874 is connected to an exhaust mechanism 849, and the first material supply chamber 895 is connected to an exhaust mechanism 848. The second material supply chamber 894 is connected to an exhaust mechanism 847. The second film formation chamber 874 shown in FIG. 22 is an evaporation chamber that performs evaporation using an evaporation source 856 moved from the first material supply chamber 895. Evaporation sources can be moved from multiple material supply chambers, and multiple substances can be simultaneously vaporized and evaporated for evaporation, i.e., co-evaporation can be performed. FIG. 22 shows an evaporation source having an evaporation boat 858 that is also moved from the second material supply chamber 894.

[0150] The second film formation chamber 874 is connected to a second material supply chamber 894 via a gate 886. The second film formation chamber 874 is connected to a first material supply chamber 895 via a gate 888. The second film formation chamber 874 is connected to a third material supply chamber 896 via a gate 887. Therefore, the second film formation chamber 874 is capable of three-source co-evaporation.

[0151] In the vapor deposition procedure, first, a substrate is placed on a substrate holder 845. The substrate holder 845 is connected to a rotation mechanism 865. Then, a first vapor deposition material 855 is heated to a certain extent in a first material supply chamber 895, and when the vapor deposition rate becomes stable, a gate 888 is opened, an arm 862 is extended, and a vapor deposition source 856 is moved and stopped at a position below the substrate. The vapor deposition source 856 is composed of the first vapor deposition material 855, a heater 857, and a container for storing the first vapor deposition material 855. Similarly, a second vapor deposition material is heated to a certain extent in a second material supply chamber 894, and when the vapor deposition rate becomes stable, a gate 886 is opened, and an arm 861 is extended, and the vapor deposition source is moved and stopped at a position below the substrate.

[0152] Thereafter, the shutter 868 and the deposition source shutter 869 are opened to perform co-evaporation. During the evaporation, the rotation mechanism 865 is rotated to improve the uniformity of the film thickness. After the evaporation, the substrate is transported to the mask alignment chamber 891 along the same route. When the substrate is to be removed from the manufacturing equipment, it is transported from the mask alignment chamber 891 to the load lock chamber 870 and then removed.

[0153] 22 shows an example in which a substrate 850 and a mask are held by a substrate holder 845. By rotating the substrate 850 (and the mask) using a substrate rotation mechanism, the uniformity of film formation can be improved. The substrate rotation mechanism may also serve as a substrate transport mechanism.

[0154] Furthermore, the second film formation chamber 874 may be provided with an imaging means 863 such as a CCD camera. By providing the imaging means 863, the position of the substrate 850 can be confirmed.

[0155] In the second film formation chamber 874, the thickness of the film formed on the surface of the substrate can be predicted based on the measurement results of the film thickness measurement mechanism 867. The film thickness measurement mechanism 867 may include, for example, a quartz oscillator.

[0156] In order to control the deposition of the vaporized deposition material, a shutter 868 that overlaps with the substrate until the evaporation rate of the deposition material stabilizes, and a deposition source shutter 869 that overlaps with the deposition source 856 and the deposition boat 858 are provided.

[0157] Although an example of a resistance heating type of evaporation source 856 is shown, an EB (Electron Beam) evaporation type may also be used. Furthermore, although a crucible is shown as an example of a container for evaporation source 856, an evaporation boat may also be used. An organic material is placed as first evaporation material 855 in the crucible heated by heater 857. Furthermore, when pellets or particulate SiO or the like are used as the evaporation material, an evaporation boat 858 is used. The evaporation boat 858 consists of three parts: a member with a concave surface, an inner lid with two holes, and an upper lid with one hole, which are stacked one on top of the other. Note that the inner lid may be removed during evaporation. The evaporation boat 858 acts as a resistor when electricity is applied, and the evaporation boat itself heats up.

[0158] Furthermore, although the present embodiment has been described as an example of a multi-chamber system, the present invention is not particularly limited thereto, and an in-line type manufacturing apparatus may also be used.

[0159] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0160] (Embodiment 6) In this embodiment, an example of a thin-film secondary battery having a battery control circuit and the like will be described.

[0161] 23A is an external view of a thin-film secondary battery. The secondary battery 913 includes a terminal 951 and a terminal 952. The terminal 951 is electrically connected to a positive electrode, and the terminal 952 is electrically connected to a negative electrode. The secondary battery of one embodiment of the present invention has excellent cycle characteristics. Furthermore, since it can be an all-solid-state secondary battery, it also has excellent safety. Therefore, the secondary battery of one embodiment of the present invention can be suitably used as the secondary battery 913.

[0162] 23B is an external view of the battery control circuit. The battery control circuit shown in FIG. 23B includes a substrate 900 and a layer 916. A circuit 912 and an antenna 914 are provided over the substrate 900. The antenna 914 is electrically connected to the circuit 912. Terminals 971 and 972 are electrically connected to the circuit 912. The circuit 912 is electrically connected to terminal 911.

[0163] The terminal 911 is connected to, for example, a device to which power is supplied from the thin-film solid secondary battery, such as a display device, a sensor, or the like.

[0164] The layer 916 has a function of shielding, for example, an electromagnetic field generated by the secondary battery 913. The layer 916 can be made of, for example, a magnetic material.

[0165] 23C shows an example in which the battery control circuit shown in FIG. 23B is disposed on a secondary battery 913. Terminal 971 is electrically connected to terminal 951, and terminal 972 is electrically connected to terminal 952. Layer 916 is disposed between substrate 900 and secondary battery 913.

[0166] The substrate 900 is preferably a flexible substrate.

[0167] A thin battery control circuit can be realized by using a flexible substrate as the substrate 900. Furthermore, the battery control circuit can be wrapped around the secondary battery as shown in Fig. 24D, which will be described later.

[0168] Another example of a thin-film secondary battery having a battery control circuit etc. will be described with reference to Figures 24A to 24D. Figure 24A is an external view of a thin-film solid-state secondary battery. The battery control circuit shown in Figure 24B has a substrate 900 and a layer 916.

[0169] As shown in Fig. 24C, by bending substrate 900 to fit the shape of secondary battery 913 and arranging the battery control circuit around the secondary battery, the battery control circuit can be wrapped around the secondary battery as shown in Fig. 24D. A secondary battery with such a configuration can be made smaller.

[0170] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0171] (Embodiment 7) In this embodiment, examples of electronic devices using a thin-film secondary battery will be described with reference to FIGS. 25A, 25B, and 26A to 26C. The secondary battery of one embodiment of the present invention has high discharge capacity, high cycle characteristics, and high safety. Therefore, the electronic devices are highly safe and can be used for a long time.

[0172] 25A is a perspective view of the appearance of a thin-film secondary battery 3001. The battery is sealed with a laminate film or an insulating film 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 thereof protrude.

[0173] 25B shows an IC card, which is an example of an application device using the thin-film secondary battery according to the present invention. Power obtained by power supply from radio waves 3005 can be charged into thin-film secondary battery 3001. An antenna, IC 3004, and thin-film secondary battery 3001 are arranged inside IC card 3000. ID 3002 and photo 3003 of the worker wearing IC card 3000 are displayed on IC card 3000. The power charged in thin-film secondary battery 3001 can also be used to transmit signals such as authentication signals from the antenna.

[0174] An active matrix display device may be provided to display the ID 3002 and the photo 3003. Examples of active matrix display devices include reflective liquid crystal displays, organic EL displays, and electronic paper. The active matrix display device can also display images (moving or still images) and time. Power for the active matrix display device can be supplied from a thin-film secondary battery 3001.

[0175] Since a plastic substrate is used in an IC card, an organic EL display device using a flexible substrate is preferred.

[0176] A solar cell may be provided in place of the photo 3003. When irradiated with external light, the solar cell absorbs the light, generates electricity, and the electricity can be used to charge the thin-film secondary battery 3001.

[0177] Furthermore, the thin-film secondary battery is not limited to use in IC cards, but can also be used as a power source for wireless sensors used in vehicles, a secondary battery for MEMS devices, and the like.

[0178] Figure 26A shows an example of a wearable device. The wearable device uses a secondary battery as a power source. Furthermore, in order to improve splash-proof, water-resistant, or dust-proof performance when used at home or outdoors, there is a demand for a wearable device that can be charged wirelessly as well as via a wired connection with an exposed connector.

[0179] For example, a secondary battery according to one embodiment of the present invention can be mounted on an eyeglasses-type device 400 as shown in FIG. 26A. The eyeglasses-type device 400 includes a frame 400a and a display unit 400b. Mounting a secondary battery on the temples of the curved frame 400a makes it possible to provide an eyeglasses-type device 400 that is lightweight, has a good weight balance, and can be used for a long time. The inclusion of a secondary battery according to one embodiment of the present invention makes it possible to realize a configuration that can accommodate space saving associated with a smaller housing.

[0180] Furthermore, a secondary battery according to one embodiment of the present invention can be mounted on a headset-type device 401. The headset-type device 401 includes at least a microphone unit 401a, a flexible pipe 401b, and an earphone unit 401c. A secondary battery can be provided in the flexible pipe 401b or the earphone unit 401c. By including a secondary battery according to one embodiment of the present invention, a configuration that can accommodate space savings due to a smaller housing can be realized.

[0181] Furthermore, the secondary battery according to one embodiment of the present invention can be mounted on a device 402 that can be directly attached to the body. A secondary battery 402b can be provided in a thin housing 402a of the device 402. By providing the secondary battery according to one embodiment of the present invention, a space-saving configuration can be realized that accompanies a miniaturized housing.

[0182] Furthermore, the secondary battery according to one embodiment of the present invention can be mounted on a device 403 that can be attached to clothing. A secondary battery 403b can be provided in a thin housing 403a of the device 403. By providing the secondary battery according to one embodiment of the present invention, a space-saving configuration can be realized that accompanies a miniaturized housing.

[0183] Furthermore, the secondary battery of one embodiment of the present invention can be mounted on the belt-type device 406. The belt-type device 406 has a belt portion 406a and a wireless power receiving portion 406b, and the secondary battery can be mounted inside the belt portion 406a. By including the secondary battery of one embodiment of the present invention, a configuration that can accommodate space saving due to miniaturization of the housing can be realized.

[0184] Furthermore, the secondary battery of one embodiment of the present invention can be mounted on the wristwatch device 405. The wristwatch device 405 has a display portion 405a and a belt portion 405b, and the secondary battery can be provided on the display portion 405a or the belt portion 405b. By providing the secondary battery of one embodiment of the present invention, a space-saving configuration can be realized that accompanies a miniaturized housing.

[0185] The display unit 405a can display not only the time but also various other information such as incoming emails and phone calls.

[0186] Furthermore, since the wristwatch device 405 is a wearable device that is worn directly on the wrist, it may be equipped with sensors that measure the user's pulse, blood pressure, etc. Data on the user's exercise volume and health can be accumulated to manage the user's health.

[0187] FIG. 26B shows a perspective view of the wristwatch type device 405 removed from the wrist.

[0188] 26C shows a side view of the display portion 405a. FIG. 26C shows that a secondary battery 913 is built in the display portion 405a. The secondary battery 913 is the secondary battery described in Embodiment 5. The secondary battery 913 is provided at a position overlapping with the display portion 405a, and is small and lightweight.

[0189] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0190] (Embodiment 8) In this embodiment, electronic devices using a secondary battery including a positive electrode of one embodiment of the present invention will be described with reference to FIGS. 27A to 27C. A secondary battery including a positive electrode of one embodiment of the present invention has high discharge capacity, high cycle characteristics, and high safety. Therefore, it can be suitably used in the following electronic devices. In particular, it can be suitably used in electronic devices that require durability.

[0191] 27A shows a perspective view of a wristwatch-type mobile information terminal (also called a smart watch) 700. Mobile information terminal 700 has a housing 701, a display panel 702, a clasp 703, bands 705A and 705B, and operation buttons 711 and 712.

[0192] A display panel 702 mounted on a housing 701 that also serves as a bezel has a rectangular display area. The display area has a curved surface. The display panel 702 is preferably flexible. The display area may also be non-rectangular.

[0193] Band 705A and band 705B are connected to housing 701. Clasp 703 is connected to band 705A. Band 705A and housing 701 are connected via a pin, for example, so that the connection can rotate. The same applies to the connections between band 705B and housing 701, and between band 705A and clasp 703.

[0194] 27B and 27C are perspective views of the band 705A and the secondary battery 750, respectively. The band 705A includes the secondary battery 750. The secondary battery 750 may be, for example, one of the secondary batteries described in the previous embodiment. The secondary battery 750 is embedded inside the band 705A, and a portion of each of the positive electrode lead 751 and the negative electrode lead 752 protrudes from the band 705A (see FIG. 27B). The positive electrode lead 751 and the negative electrode lead 752 are electrically connected to the display panel 702. The surface of the secondary battery 750 is covered with an exterior body 753 (see FIG. 27C). The pins may also function as electrodes. Specifically, the positive electrode lead 751 and the display panel 702, and the negative electrode lead 752 and the display panel 702 may be electrically connected via pins connecting the band 705A to the housing 701, respectively. This simplifies the configuration at the connection between the band 705A and the housing 701.

[0195] Secondary battery 750 is flexible. Therefore, band 705A can be manufactured by integrally forming it with secondary battery 750. For example, secondary battery 750 is placed in a mold that corresponds to the outer shape of band 705A, and the material for band 705A is poured into the mold and cured, thereby manufacturing band 705A shown in FIG. 27B.

[0196] When a rubber material is used as the material for the band 705A, the rubber is hardened by heat treatment. For example, when fluororubber is used as the rubber material, it is hardened by heat treatment at 170°C for 10 minutes. When silicone rubber is used as the rubber material, it is hardened by heat treatment at 150°C for 10 minutes.

[0197] Materials used for the band 705A include fluororubber, silicone rubber, fluorosilicone rubber, and urethane rubber.

[0198] 27A can have various functions. For example, it can have a function of displaying various information (still images, videos, text images, etc.) in a display area, a touch panel function, a function of displaying a calendar, date or time, etc., a function of controlling processing by various software (programs), a wireless communication function, a function of connecting to various computer networks using the wireless communication function, a function of transmitting or receiving various data using the wireless communication function, a function of reading out programs or data recorded on a recording medium and displaying them in a display area, etc.

[0199] The housing 701 may also include a speaker, a sensor (including a function of measuring force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared ray), a microphone, etc. The portable information terminal 700 can be manufactured by using a light-emitting element for the display panel 702.

[0200] 27A shows an example in which secondary battery 750 is included in band 705A, but secondary battery 750 may be included in band 705B. Band 705B can be made of the same material as band 705A.

[0201] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0202] (Embodiment 9) The device described in this embodiment includes at least a biosensor and a solid-state secondary battery that supplies power to the biosensor. It can acquire various types of biometric information using infrared light and visible light and store the information in a memory. Such biometric information can be used for both personal authentication of users and healthcare applications. The secondary battery of one embodiment of the present invention has high discharge capacity, high cycle characteristics, and high safety. Therefore, the device is highly safe and can be used for a long period of time.

[0203] A biosensor is a sensor that acquires biological information that can be used for healthcare purposes. Such biological information includes pulse wave, blood glucose level, oxygen saturation, and triglyceride concentration. The data is stored in memory.

[0204] Furthermore, it is preferable to provide the device described in this embodiment with means for acquiring other biological information. For example, in addition to internal biological information such as electrocardiogram, blood pressure, and body temperature, there is also external biological information such as facial expression, complexion, and pupils. Information on the number of steps taken, exercise intensity, elevation change, and diet (calorie intake, nutrients, etc.) is also important information for health care. Using multiple pieces of biological information enables comprehensive health management, which not only contributes to daily health management but also to early detection of injuries and illnesses.

[0205] For example, blood pressure can be calculated from an electrocardiogram and the difference in timing between two beats of a pulse wave (length of pulse wave propagation time). High blood pressure results in a short pulse wave propagation time, and conversely, low blood pressure results in a long pulse wave propagation time. The user's physical condition can also be estimated from the relationship between heart rate and blood pressure calculated from an electrocardiogram and pulse wave. For example, if both the heart rate and blood pressure are high, it can be estimated that the user is in a state of tension or excitement, and conversely, if both the heart rate and blood pressure are low, it can be estimated that the user is in a relaxed state. Furthermore, if the user has low blood pressure and a high heart rate that continues to be present, it could be a sign of heart disease or the like.

[0206] Users can check their own health status at any time, as well as their biological information measured by electronic devices, which can improve their health awareness. This can lead to them reviewing their daily habits, such as avoiding overeating, getting moderate exercise, and managing their health, and may even encourage them to seek medical advice if necessary.

[0207] Each data may be shared among multiple biosensors. Fig. 28A shows an example in which a biosensor 80a is implanted in a user's body and an example in which a biosensor 80b is worn on the user's wrist. Fig. 28A shows a device having a biosensor 80a capable of measuring, for example, an electrocardiogram, and a device having a biosensor 80b capable of measuring heart rate by optically monitoring the pulse of the user's arm. Note that the watch or wristband-type wearable device shown in Fig. 28A is not limited to heart rate measurement, and various biosensors can be used.

[0208] 28A is based on the premise that it is small, generates almost no heat, and does not cause allergic reactions or the like even when it comes into contact with the skin. The secondary battery used in the device of one embodiment of the present invention is suitable because it is small, generates almost no heat, and does not cause allergic reactions or the like. In addition, it is preferable that the implantable device has a built-in antenna so that it can be wirelessly charged.

[0209] The device of the type implanted in a living body shown in FIG. 28A is not limited to a biosensor capable of measuring an electrocardiogram, and a biosensor capable of acquiring other biological data can be used.

[0210] The biosensor 80b built into the device may be temporarily stored in the device's built-in memory. Alternatively, data acquired by each biosensor may be sent wirelessly or via a wired connection to a portable data terminal 85 shown in FIG. 28B, where the waveform may be detected. The portable data terminal 85 may be a smartphone or the like, and may detect problems such as arrhythmia from the data acquired from each biosensor. When data acquired by multiple biosensors is sent to the portable data terminal 85 via a wired connection, it is preferable to transfer the acquired data collectively before establishing a wired connection. Each detected data may be automatically dated and saved in the memory of the portable data terminal 85 for personal management. Alternatively, the data may be sent to a medical institution 87, such as a hospital, via a network (including the Internet), as shown in FIG. 28B. The data may be managed by the hospital's data server and used as test data during treatment. Because the amount of medical data can be enormous, a network including Bluetooth (registered trademark) or a frequency band from 2.4 GHz to 2.4835 GHz may be used between biosensor 80b and portable data terminal 85, and a fifth-generation (5G) wireless system may be used between portable data terminals 85 for high-speed communication. The fifth-generation (5G) wireless system uses frequencies in the 3.7 GHz, 4.5 GHz, and 28 GHz bands. Using the fifth-generation (5G) wireless system enables data acquisition and transmission to medical institutions 87 not only at home but also when the user is out and about. This allows accurate acquisition of data when the user's physical condition becomes abnormal and can be used for subsequent processing or treatment. The configuration shown in FIG. 28C can be used for portable data terminal 85.

[0211] 28C shows another example of a portable data terminal 89. In addition to a secondary battery, the portable data terminal 89 has a speaker, a pair of electrodes 83, a camera 84, and a microphone 86.

[0212] A pair of electrodes 83 is provided on a part of the housing 82, sandwiching a display unit 81a therebetween. The display unit 81b is a region having a curved surface. The electrodes 83 function as electrodes for acquiring biological information.

[0213] As shown in FIG. 28C, by arranging a pair of electrodes 83 in the longitudinal direction of the housing 82, when using the portable data terminal 89 with a landscape screen, biometric information can be acquired without the user being aware of it.

[0214] 1 shows an example of the usage state of a portable data terminal 89. The display unit 81a can display electrocardiogram information 88a acquired by a pair of electrodes 83, heart rate information 88b, and the like.

[0215] This function is unnecessary when biosensor 80a is implanted in the user's body as shown in Figure 27A, but when it is not implanted, the user can obtain an electrocardiogram by holding a pair of electrodes 83 with both hands. Even when biosensor 80a is implanted in the user's body, portable data terminal 89 shown in Figure 28C can be used to compare electrocardiogram data with that of other users to check whether biosensor 80a is functioning normally.

[0216] The camera 84 can capture an image of the user's face, etc. From the image of the user's face, biological information such as facial expression, pupils, and complexion can be obtained.

[0217] The microphone 86 can capture the user's voice. Voiceprint information that can be used for voiceprint authentication can be obtained from the captured voice information. Furthermore, voice information can be captured periodically and changes in voice quality can be monitored, which can be used for health management. Of course, the microphone 86, camera 84, and speaker can also be used to make video calls with a doctor at a medical institution 87.

[0218] By using the device shown in FIG. 28A and the portable data terminal 89 shown in FIG. 28C, it is possible to realize a remote medical support system in which information is sent from a remote location to a doctor in a hospital and the patient is examined by the doctor.

[0219] This embodiment mode can be implemented in appropriate combination with other embodiment modes. [Explanation of symbols]

[0220] 100: positive electrode, 100a: region, 101: positive electrode active material layer, 102: separation layer, 103: positive electrode current collector layer, 104: base film, 105: cap layer, 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 layer, 206: protective layer, 209: separation layer, 210: negative electrode, 211: negative electrode, 212: negative electrode, 213: solid electrolyte layer, 215: positive electrode current collector layer, 220: separator, 221: electrolyte, 222: exterior body, 223a: lead electrode, 223b: lead electrode, 230: secondary battery, 231: secondary battery

Claims

1. A positive electrode for a secondary battery, The positive electrode for a secondary battery has n layers (n is an integer of 2 or more) of positive electrode active material layers, n-1 layers of separation layers, and a positive electrode current collector layer, The positive electrode active material layers and the separation layers are laminated alternately, the positive electrode active material layer contains lithium, cobalt, oxygen, nickel, aluminum, magnesium, and fluorine; the separation layer comprises a titanium compound; When the number of cobalt atoms in the positive electrode active material layer is 100, The number of nickel atoms is 0.05 or more and 2 or less, The number of aluminum atoms is 0.05 or more and 2 or less, A positive electrode for a secondary battery, comprising: a magnesium atom number of 0.1 or more and 6 or less.

2. A positive electrode for a secondary battery, The positive electrode for a secondary battery has n layers (n is an integer of 2 or more) of positive electrode active material layers, n-1 layers of separation layers, and a positive electrode current collector layer, The positive electrode active material layers and the separation layers are laminated alternately, the positive electrode active material layer contains lithium cobalt oxide, The separation layer comprises titanium oxide, The positive electrode active material layer has a (001) plane of a crystal structure belonging to space group R-3m; The separation layer has a crystal structure belonging to the space group P42 / mnm, and the (100) plane of the crystal structure is parallel to the surface of the separation layer.

3. A positive electrode for a secondary battery, The positive electrode for a secondary battery has n layers (n is an integer of 2 or more) of positive electrode active material layers, n-1 layers of separation layers, and a positive electrode current collector layer, The positive electrode active material layers and the separation layers are laminated alternately, the positive electrode active material layer contains lithium cobalt oxide, the separation layer comprises titanium nitride; The positive electrode active material layer has a (104) plane of a crystal structure belonging to space group R-3m; The separation layer has a crystal structure belonging to the space group Fm-3m, and the (100) plane of the crystal structure is parallel to the surface of the separation layer.

4. In claim 2 or 3, the positive electrode active material layer contains nickel, aluminum, magnesium and fluorine, When the number of cobalt atoms in the positive electrode active material layer is 100, The number of nickel atoms is 0.05 or more and 2 or less, The number of aluminum atoms is 0.05 or more and 2 or less, A positive electrode for a secondary battery, in which the number of magnesium atoms is 0.1 or more and 6 or less.

5. The positive electrode for a secondary battery according to any one of claims 1 to 4, A secondary battery having a solid electrolyte and a negative electrode.

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

Images