Power storage device

Abstract

To provide a power storage device and the like that consume less power, or a power storage device and the like having a high degree of integration.SOLUTION: There is provided a power storage device in which a first battery cell has a first electrode on a first substrate, a positive electrode active material layer on the first electrode, an electrolyte layer on the positive electrode active material layer, a negative electrode active material layer on the electrolyte layer, and a second electrode on the negative electrode active material layer, a comparator circuit has a first input terminal, a second input terminal, an output terminal, and a first transistor, the first transistor has an oxide semiconductor on the first substrate, a first insulator on the oxide semiconductor, and a gate electrode on the first insulator, the first electrode is electrically connected to a gate of the first transistor and the first input terminal, the comparator circuit has a function of outputting, from the output terminal to a control circuit, a first signal in response to a result of comparison between a potential of the first electrode and a desired reference potential, and the control circuit has a function of controlling charging of the first battery cell in response to the first signal.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] TECHNICAL FIELD One embodiment of the present invention relates to a semiconductor device and a method for operating the semiconductor device.

[0002] Note that one embodiment of the present invention is not limited to the above technical field. The technical field of the invention disclosed in this specification relates to an object, a method, or a manufacturing method. Alternatively, one embodiment of the present invention relates to a process, a machine, a manufacture, or a composition of matter. Therefore, more specifically, examples of the technical field of one embodiment of the present invention disclosed in this specification include a display device, a light-emitting device, a power storage device, an imaging device, a storage device, a driving method thereof, or a manufacturing method thereof. [Background technology]

[0003] Energy storage devices (also called batteries or secondary batteries) are being used in a wide range of fields, from small electronic devices to automobiles. As the range of applications for batteries expands, applications using multi-cell battery stacks in which multiple battery cells are connected in series are also increasing.

[0004] The energy storage device is equipped with a circuit for detecting abnormalities during charging and discharging, such as over-discharging, over-charging, over-current, or short circuit. In this way, in the circuit that protects and controls the battery, data such as voltage and current is acquired to detect abnormalities during charging and discharging. In addition, such a circuit performs control such as stopping charging and discharging and cell balancing based on the observed data.

[0005] Patent Document 1 discloses a protection IC that functions as a battery protection circuit. Patent Document 1 discloses a protection IC that has multiple comparators built in and compares a reference voltage with the voltage of the terminal to which the battery is connected to detect abnormalities during charging and discharging.

[0006] Moreover, Patent Document 2 discloses a battery state detection device for detecting a micro-short circuit in a secondary battery, and a battery pack incorporating the same.

[0007] Moreover, Patent Document 3 discloses a protective semiconductor device that protects a battery pack in which secondary battery cells are connected in series. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] US Patent Application Publication No. 2011-267726 [Patent Document 2] JP 2010-66161 A [Patent Document 3] JP 2010-220389 A Summary of the Invention [Problem to be solved by the invention]

[0009] An object of one embodiment of the present invention is to provide a novel battery control circuit, battery protection circuit, power storage device, semiconductor device, vehicle, electronic device, etc. Another object of one embodiment of the present invention is to provide a battery control circuit, battery protection circuit, power storage device, semiconductor device, vehicle, electronic device, etc. that consumes low power. Another object of one embodiment of the present invention is to provide a battery control circuit, battery protection circuit, power storage device, semiconductor device, vehicle, electronic device, etc. that are highly integrated.

[0010] The problems of one embodiment of the present invention are not limited to the problems listed above. The problems listed above do not preclude the existence of other problems. The other problems are problems not mentioned in this section, which will be described below. Problems not mentioned in this section can be derived by a person skilled in the art from the description in the specification or drawings, and can be appropriately extracted from these descriptions. One embodiment of the present invention solves at least one of the problems listed above and / or other problems. [Means for solving the problem]

[0011] One embodiment of the present invention is a power storage device including a first substrate, a first battery cell, a comparison circuit, and a control circuit. The first battery cell includes a first electrode on the first substrate, a positive electrode active material layer on the first electrode, an electrolyte layer on the positive electrode active material layer, a negative electrode active material layer on the electrolyte layer, and a second electrode on the negative electrode active material layer. The comparison circuit includes a first input terminal, a second input terminal, an output terminal, and a first transistor. The first transistor includes an oxide semiconductor on the first substrate, a first insulator on the oxide semiconductor, and a gate electrode on the first insulator. The first electrode is electrically connected to a gate of the first transistor and the first input terminal. The comparison circuit has a function of outputting a first signal according to a comparison result between a potential of the first electrode and a desired reference potential from the output terminal to the control circuit. The control circuit has a function of controlling charging of the first battery cell in response to the first signal.

[0012] In the above configuration, it is preferable that the semiconductor device further includes a second transistor and a capacitor, one of a source and a drain of the second transistor is electrically connected to a second input terminal, the other of the source and the drain of the second transistor is electrically connected to one electrode of the capacitor, and the second transistor includes an oxide semiconductor.

[0013] In the above structure, the output terminal is preferably electrically connected to the source or drain of the first transistor.

[0014] In the above configuration, it is preferable that the semiconductor device includes a second transistor having an oxide semiconductor, a third transistor having an oxide semiconductor, and a capacitor, one of a source and a drain of the second transistor is electrically connected to a second input terminal and a gate of the third transistor, the other of the source and drain of the second transistor is electrically connected to one electrode of the capacitor, and the output terminal is electrically connected to the source or drain of the third transistor.

[0015] In addition, in the above configuration, it is preferable that the first transistor has a second insulator on a gate electrode thereof and a third electrode on the second insulator, the first electrode being located on the second insulator, the first electrode and the third electrode each having a titanium compound, and the third electrode being electrically connected to the source or drain of the first transistor.

[0016] In the above structure, it is preferable that the first transistor has a source electrode and a drain electrode, and that the first electrode, the source electrode of the first transistor, and the drain electrode of the first transistor each contain a titanium compound.

[0017] In the above structure, the first electrode and the gate electrode of the first transistor each preferably contain a titanium compound.

[0018] In addition, in the above configuration, it is preferable that the device has a second battery cell, a conversion circuit, a clock generation circuit, a boost circuit, and a voltage holding circuit, the first transistor has a backgate, the conversion circuit has a function of converting the positive electrode potential of the second battery cell and providing it as a second signal to the clock generation circuit, the clock generation circuit has a function of generating a third signal that is a clock signal using the second signal, the boost circuit has a function of generating a first potential using the third signal, and the voltage holding circuit has a function of providing the first potential to the backgate and holding it.

[0019] In the above configuration, the first substrate is preferably any one of a glass substrate, a quartz substrate, a sapphire substrate, a ceramic substrate, a metal substrate, a semiconductor substrate, an SOI substrate, and a plastic substrate.

[0020] In the above structure, it is preferable that the first substrate is a semiconductor substrate, the first substrate includes silicon, and a transistor has a channel formation region provided in the first substrate.

[0021] Alternatively, one embodiment of the present invention is a power storage device including a first substrate, a first transistor having an oxide semiconductor on the first substrate, a first insulator on the oxide semiconductor, and a gate electrode on the first insulator, a second insulator on the oxide semiconductor, a first electrode on the second insulator, a positive electrode active material layer on the first electrode, an electrolyte layer on the positive electrode active material layer, a negative electrode active material layer on the electrolyte layer, and a second electrode on the negative electrode active material layer, and a third electrode on the second insulator, where the third electrode is electrically connected to a source or drain of the first transistor.

[0022] In the above configuration, the first electrode and the third electrode preferably contain a titanium compound.

[0023] In the above structure, the first transistor preferably includes an oxide semiconductor in a channel formation region.

[0024] In the above configuration, it is preferable that the device further comprises a fourth electrode on the third electrode and a third insulator sandwiched between the third electrode and the fourth electrode, and that the first electrode and the fourth electrode each contain a titanium compound.

[0025] In the above configuration, it is preferable that the piezoelectric element further comprises a fourth electrode on the third electrode, and a piezoelectric layer sandwiched between the third electrode and the fourth electrode, and that the first electrode and the fourth electrode each contain a titanium compound.

[0026] Alternatively, one embodiment of the present invention is a power storage device including a first substrate, a first transistor having a source electrode and a drain electrode over the first substrate, an oxide semiconductor over the source electrode and the drain electrode, a first insulator over the oxide semiconductor, and a gate electrode over the first insulator, and a first battery cell including a first electrode over the first substrate, a positive electrode active material layer over the first electrode, an electrolyte layer over the positive electrode active material layer, a negative electrode active material layer over the electrolyte layer, and a second electrode over the negative electrode active material layer, in which the source electrode, the drain electrode, and the first electrode each contain a titanium compound.

[0027] Alternatively, one embodiment of the present invention is an electronic device including a first substrate, a first battery cell, a comparison circuit, a control circuit, and a piezoelectric element. The first battery cell includes a first electrode on the first substrate, a positive electrode active material layer on the first electrode, an electrolyte layer on the positive electrode active material layer, a negative electrode active material layer on the electrolyte layer, and a second electrode on the negative electrode active material layer. The comparison circuit includes a first transistor. The first transistor includes an oxide semiconductor on the first substrate, a first insulator on the oxide semiconductor, and a gate electrode on the first insulator. The piezoelectric element includes a third electrode, a piezoelectric layer on the third electrode, and a fourth electrode on the piezoelectric layer. The first electrode is electrically connected to the gate electrode of the first transistor. The comparison circuit has a function of outputting a first signal according to a comparison result between a potential of the first electrode and a desired potential to the control circuit. The control circuit has a function of controlling charging of the first battery cell in response to the first signal.

[0028] In the above structure, it is preferable that the first electrode and the third electrode each contain a titanium compound.

[0029] Alternatively, one embodiment of the present invention is an electronic device including a first substrate, a first battery cell, a comparison circuit, a display unit, and a driver circuit. The first substrate is selected from a glass substrate, a quartz substrate, a sapphire substrate, a ceramic substrate, a metal substrate, a semiconductor substrate, an SOI substrate, and a plastic substrate. The first battery cell includes a first electrode over the first substrate, a positive electrode active material layer over the first electrode, an electrolyte layer over the positive electrode active material layer, a negative electrode active material layer over the electrolyte layer, and a second electrode over the negative electrode active material layer. The first electrode includes a titanium compound. The comparison circuit includes a first transistor. The first transistor includes an oxide semiconductor over the first substrate, a source electrode and a drain electrode over the oxide semiconductor, a first insulator over the oxide semiconductor, and a gate electrode over the first insulator. The first electrode is electrically connected to a gate of the first transistor. The driver circuit has a function of applying an image signal to the display unit. The driver circuit includes a plurality of transistors including an oxide semiconductor.

[0030] Alternatively, one embodiment of the present invention includes a first substrate, a first battery cell, a comparison circuit, and a control circuit. The first battery cell includes a first electrode over the first substrate, a positive electrode active material layer over the first electrode, an electrolyte layer over the positive electrode active material layer, a negative electrode active material layer over the electrolyte layer, and a second electrode over the negative electrode active material layer. The first electrode includes a titanium compound. The comparison circuit includes a first input terminal, a second input terminal, an output terminal, and a first transistor. The first transistor includes an oxide semiconductor over the first substrate and an oxide the first input terminal is electrically connected to the gate electrode, the first electrode is electrically connected to the first input terminal, the comparator circuit has a function of outputting a first signal according to a comparison result between the potential of the first electrode and a desired reference potential from the output terminal to a control circuit, and the control circuit has a function of controlling charging of a first battery cell according to the first signal. Effect of the Invention

[0031] One embodiment of the present invention can provide a novel battery control circuit, a novel battery protection circuit, a power storage device, a semiconductor device, a vehicle, an electronic device, etc. One embodiment of the present invention can provide a battery control circuit, a battery protection circuit, a power storage device, a semiconductor device, a vehicle, an electronic device, etc. that consumes low power. One embodiment of the present invention can provide a battery control circuit, a battery protection circuit, a power storage device, a semiconductor device, a vehicle, an electronic device, etc. that are highly integrated.

[0032] The effects of one embodiment of the present invention are not limited to the effects listed above. The effects listed above do not preclude the existence of other effects. The other effects are described below and are not mentioned in this section. The effects not mentioned in this section can be derived by a person skilled in the art from the description in the specification or drawings, and can be appropriately extracted from these descriptions. One embodiment of the present invention has at least one of the effects listed above and / or other effects. Therefore, one embodiment of the present invention may not have the effects listed above in some cases. [Brief description of the drawings]

[0033] [Figure 1] 1A and 1B are a top view and a cross-sectional view of a secondary battery according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view showing one embodiment of the present invention. [Diagram 3] FIG. 3 is a cross-sectional view showing one embodiment of the present invention. [Figure 4] FIG. 4 is a cross-sectional view showing one embodiment of the present invention. [Diagram 5] FIG. 5 is a cross-sectional view showing one embodiment of the present invention. [Figure 6] FIG. 6 is a cross-sectional view showing one embodiment of the present invention. [Figure 7] 7A and 7B are cross-sectional views illustrating a transistor according to one embodiment of the present invention. [Figure 8] 8A and 8B are top views of a secondary battery according to one embodiment of the present invention. [Figure 9] FIG. 9 is a block diagram illustrating one embodiment of the present invention. [Figure 10] 10A and 10B are circuit diagrams illustrating one embodiment of the present invention. [Figure 11] FIG. 11 is a block diagram illustrating one embodiment of the present invention. [Figure 12] 12A and 12B are a block diagram and a circuit diagram illustrating one embodiment of the present invention. [Figure 13] 13A and 13B are circuit diagrams illustrating one embodiment of the present invention. [Figure 14] 14A, 14B, and 14C are circuit diagrams illustrating one embodiment of the present invention. [Figure 15] 15A and 15B are circuit diagrams illustrating one embodiment of the present invention. [Figure 16] FIG. 16 is a diagram illustrating an example of an electronic device. [Figure 17] Fig. 17A is a diagram illustrating an example of an electronic device, Fig. 17B is a diagram illustrating an example of an electronic device, and Fig. 17C is a diagram illustrating an example of an electronic device. [Figure 18] Fig. 18A is a diagram illustrating an example of an electronic device, and Fig. 18B is a diagram illustrating an example of an electronic device. [Figure 19] Fig. 19A is a diagram for explaining an example of an electronic device. Fig. 19B is a diagram for explaining an example of an electronic device. Fig. 19C is a diagram for explaining an example of an aircraft. Fig. 19D is a diagram for explaining an example of a vehicle. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] Hereinafter, the embodiments will be described with reference to the drawings. However, it will be easily understood by those skilled in the art that the embodiments can be implemented in many different ways, and that the modes and details can be changed in various ways without departing from the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the description of the following embodiments.

[0035] In this specification, the ordinal numbers "first," "second," and "third" are used to avoid confusion of components. Therefore, they do not limit the number of components. Furthermore, they do not limit the order of the components. For example, a component referred to as "first" in one embodiment of this specification may be a component referred to as "second" in another embodiment or in the claims. For example, a component referred to as "first" in one embodiment of this specification may be omitted in another embodiment or in the claims.

[0036] In the drawings, the same elements or elements having similar functions, elements made of the same material, or elements formed at the same time may be given the same reference numerals, and repeated description thereof may be omitted.

[0037] In addition, the position, size, range, etc. of each component shown in the drawings, etc. may not represent the actual position, size, range, etc. in order to facilitate understanding of the invention. Therefore, the disclosed invention is not necessarily limited to the position, size, range, etc. disclosed in the drawings, etc. For example, in an actual manufacturing process, a resist mask, etc. may be unintentionally eroded by a process such as etching, but this may not be reflected in the drawings in order to facilitate understanding.

[0038] In addition, in top views (also called "plan views"), perspective views, and the like, illustration of some components may be omitted in order to make the drawings easier to understand.

[0039] In addition, the terms "electrode" and "wiring" used in this specification and the like do not limit the functionality of these components. For example, an "electrode" may be used as part of a "wiring", and vice versa. Furthermore, the terms "electrode" and "wiring" include cases where multiple "electrodes" or "wirings" are formed integrally.

[0040] In addition, in this specification, a "terminal" may refer to, for example, a wiring or an electrode connected to a wiring. In addition, in this specification, a part of a "wiring" may be called a "terminal".

[0041] In this specification, the terms "above" and "below" do not limit the positional relationship of components to being directly above or below and in direct contact. For example, the expression "electrode B on insulating layer A" does not require that electrode B be formed in direct contact with insulating layer A, and does not exclude the inclusion of other components between insulating layer A and electrode B.

[0042] In addition, the functions of the source and drain are interchangeable depending on the operating conditions, such as when transistors of different polarities are used or when the direction of current changes during circuit operation, so it is difficult to determine which is the source and which is the drain. For this reason, in this specification, the terms source and drain can be used interchangeably.

[0043] In addition, in this specification, "electrically connected" includes a direct connection and a connection via "something having some electrical action." Here, the "something having some electrical action" is not particularly limited as long as it allows the transmission and reception of electrical signals between the connected objects. Therefore, even when it is expressed as "electrically connected," in the actual circuit, there may be no physical connection and only wiring extending therethrough.

[0044] In addition, in this specification, "parallel" refers to, for example, a state in which two straight lines are arranged at an angle of -10° or more and 10° or less. Therefore, it also includes the case of -5° or more and 5° or less. Furthermore, "perpendicular" and "orthogonal" refer to, for example, a state in which two straight lines are arranged at an angle of 80° or more and 100° or less. Therefore, it also includes the case of 85° or more and 95° or less.

[0045] In this specification and elsewhere, when referring to counting values ​​and measurement values, terms such as "same," "equal," "uniform," etc. are used, they are intended to include an error of plus or minus 20% unless otherwise expressly stated.

[0046] In addition, in this specification, when an etching process is performed after forming a resist mask, the resist mask is removed after the etching process is completed, unless otherwise specified.

[0047] Furthermore, voltage often refers to the potential difference between a certain potential and a reference potential (for example, a ground potential or a source potential). Therefore, voltage and potential are often interchangeable.

[0048] Even when written as "semiconductor", for example, if the conductivity is sufficiently low, it has the characteristics of an "insulator". Therefore, it is also possible to use "semiconductor" instead of "insulator". In this case, the boundary between "semiconductor" and "insulator" is ambiguous, and it is difficult to strictly distinguish between the two. Therefore, "semiconductor" and "insulator" described in this specification may be read as interchangeable.

[0049] Furthermore, even when written as "semiconductor", if the conductivity is sufficiently high, it has the characteristics of a "conductor". Therefore, it is also possible to use "semiconductor" in place of "conductor". In this case, the boundary between "semiconductor" and "conductor" is ambiguous, and it is difficult to strictly distinguish between the two. Therefore, "semiconductor" and "conductor" described in this specification may be interchangeable.

[0050] In this specification, the "on state" of a transistor refers to a state in which the source and drain of the transistor can be regarded as being electrically short-circuited (also referred to as a "conductive state"). The "off state" of a transistor refers to a state in which the source and drain of the transistor can be regarded as being electrically disconnected (also referred to as a "non-conductive state").

[0051] In this specification, the term "on-state current" may refer to a current that flows between a source and a drain when a transistor is on, and the term "off-state current" may refer to a current that flows between a source and a drain when a transistor is off.

[0052] In this specification and the like, high power supply potential VDD (hereinafter simply referred to as "VDD" or "H potential") refers to a power supply potential that is higher than the low power supply potential VSS. Also, low power supply potential VSS (hereinafter simply referred to as "VSS" or "L potential") refers to a power supply potential that is lower than the high power supply potential VDD. Also, the ground potential can be used as VDD or VSS. For example, when VDD is the ground potential, VSS is a potential lower than the ground potential, and when VSS is the ground potential, VDD is a potential higher than the ground potential.

[0053] In this specification and the like, a gate refers to a gate electrode and a part or the whole of a gate wiring. A gate wiring refers to a wiring for electrically connecting a gate electrode of at least one transistor to another electrode or another wiring.

[0054] In this specification and the like, the source refers to a source region, a source electrode, and a part or all of a source wiring. The source region refers to a region of a semiconductor layer having a resistivity equal to or lower than a certain value. The source electrode refers to a conductive layer connected to the source region. The source wiring refers to a wiring for electrically connecting the source electrode of at least one transistor to another electrode or another wiring.

[0055] In this specification and the like, the drain refers to a part or all of the drain region, the drain electrode, and the drain wiring. The drain region refers to a region of the semiconductor layer whose resistivity is equal to or lower than a certain value. The drain electrode refers to a conductive layer that is connected to the drain region. The drain wiring refers to a wiring for electrically connecting the drain electrode of at least one transistor to another electrode or another wiring.

[0056] (Embodiment 1) A secondary battery of one embodiment of the present invention will be described with reference to FIG.

[0057] [Secondary battery configuration]

[0058] 1A and 1B show a specific example of a secondary battery 200 according to one embodiment of the present invention. Here, a secondary battery 200 formed over a substrate 110 will be described.

[0059] FIG. 1A is a top view, and FIG. 1B is a cross-sectional view taken along line A-A' in FIG. 1A. The secondary battery 200 is a thin-film battery. As shown in FIG. 1B, a stack of a positive electrode 100 and a solid electrolyte layer 203 is formed on a substrate 110, and a negative electrode 210 is formed on the solid electrolyte layer 203. The positive electrode 100 includes a positive electrode current collector 103 and a positive electrode active material layer 101 on the positive electrode current collector 103. The negative electrode 210 includes a negative electrode active material layer 204 and a negative electrode current collector 205 on the negative electrode active material layer 204. The solid electrolyte layer 203 is provided between the positive electrode active material layer 101 and the negative electrode active material layer 204.

[0060] Further, it is preferable that a protective layer 206 is formed on the positive electrode 100, the solid electrolyte layer 203, and the negative electrode 210 of the secondary battery 200.

[0061] The films forming these layers can be formed using a metal mask respectively. The positive electrode current collector 103, the positive electrode active material layer 101, the solid electrolyte layer 203, the negative electrode active material layer 204, and the negative electrode current collector 205 can be selectively formed using a sputtering method. Also, the solid electrolyte layer 203 may be selectively formed by using a co-evaporation method and a metal mask.

[0062] As shown in FIG. 1A, a part of the negative electrode current collector 205 is exposed to form a negative electrode terminal portion. Also, a part of the positive electrode current collector 103 is exposed to form a positive electrode terminal portion. Regions other than the negative electrode terminal portion and the positive electrode terminal portion are covered with the protective layer 206.

[0063] As the positive electrode current collector 103, it is preferable to use a material having conductivity. Also, it is preferable to use a material that is easily resistant to oxidation. For example, titanium compounds such as titanium oxide, titanium nitride, titanium oxide partially substituted with nitrogen, titanium nitride partially substituted with oxygen, or titanium oxynitride (TiO x N y , 0 < x < 2, 0 < y < 1) etc. can be applied. Among them, titanium nitride is particularly preferable because it has high conductivity and a high function of suppressing oxidation. By using titanium nitride, the crystal structure of the positive electrode active material layer 101 may be stabilized.

[0064] A laminated structure may also be used as the positive electrode current collector 103. For example, a first layer containing a material such as a metal, such as gold, platinum, aluminum, titanium, copper, magnesium, iron, cobalt, nickel, zinc, germanium, indium, silver, or palladium, or an alloy thereof, may be provided, and a second layer containing a titanium compound may be provided by laminating the first layer on the first layer.

[0065] The material of the solid electrolyte layer 203 is Li 0.35 La 0.55 TiO 3 , La (2 / 3-X) Li 3X TiO 3 , Li 3 PO 4 , Li X PO (4-Y) N Y , LiNb (1-X) Ta (X) WO 6 , Li 7 La 3 Zr 2 O 12 , Li (1+X) Al (X) Ti (2-X) (PO 4 ) 3 , Li (1+X) Al (X) Ge (2-X) (PO 4 ) 3 , LiNbO 2 In addition, X>0 and Y>0. As a film formation method, a sputtering method, a vapor deposition method, etc. can be used.

[0066] The solid electrolyte layer 203 may have a laminated structure. In the case of the laminated structure, lithium phosphate (Li 3 PO 4 ) with nitrogen added (Li 3 PO (4-Z) N Z : Also called LiPON) may be laminated. Note that Z>0.

[0067] Moreover, the solid electrolyte layer 203 can be formed by, for example, a sputtering method.

[0068] The positive electrode active material layer 101 contains lithium, a transition metal M, and oxygen. It may be said that the positive electrode active material layer 101 contains a composite oxide containing lithium and the transition metal M.

[0069] As the transition metal M contained in the positive electrode active material layer 101, it is preferable to use a metal that can form a layered rock salt type composite oxide belonging to the space group R-3m together with lithium. As the transition metal M, for example, one or more of manganese, cobalt, and nickel can be used. In other words, as the transition metal contained in the positive electrode active material layer 101, only cobalt may be used, only nickel may be used, two kinds of cobalt and manganese, two kinds of cobalt and nickel may be used, or three kinds of cobalt, manganese, and nickel may be used. In other words, the positive electrode active material layer 101 can have a composite oxide containing lithium and the transition metal M, such as lithium cobalt oxide, lithium nickel oxide, lithium cobalt oxide in which a part of cobalt is replaced with manganese, lithium cobalt oxide in which a part of cobalt is replaced with nickel, and nickel-manganese-lithium cobalt oxide.

[0070] In addition to the above, the positive electrode active material layer 101 may contain elements other than the transition metal M, such as magnesium, fluorine, and aluminum. These elements may further stabilize the crystal structure of the positive electrode active material layer 101. That is, the positive electrode active material layer 101 may contain lithium cobalt oxide to which magnesium and fluorine have been added, lithium nickel-cobalt oxide to which magnesium and fluorine have been added, lithium cobalt-aluminate to which magnesium and fluorine have been added, lithium nickel-cobalt-aluminate, lithium nickel-cobalt-aluminate, lithium nickel-cobalt-aluminate to which magnesium and fluorine have been added, or the like.

[0071] When the positive electrode active material layer 101 contains lithium, cobalt, nickel, aluminum, magnesium, oxygen, and fluorine, the atomic ratio of nickel is preferably, for example, 0.05 to 2, more preferably 0.1 to 1.5, and even more preferably 0.1 to 0.9, when the atomic ratio of cobalt contained in the positive electrode active material layer 101 is taken as 100, the atomic ratio of aluminum is preferably, for example, 0.05 to 2, more preferably 0.1 to 1.5, and even more preferably 0.1 to 0.9, when the atomic ratio of cobalt contained in the positive electrode active material layer 101 is taken as 100. The atomic ratio of magnesium is preferably, for example, 0.1 to 6, and more preferably 0.3 to 3. Furthermore, when the atomic ratio of magnesium contained in the positive electrode active material layer 101 is taken as 1, the atomic ratio of fluorine is preferably, for example, 2 to 3.9.

[0072] By containing nickel, aluminum, and magnesium in the above-mentioned concentrations, a stable crystal structure can be maintained even when charging and discharging are repeated at a high voltage, and thus the positive electrode active material layer 101 can be provided with a high capacity and excellent charge-discharge cycle characteristics.

[0073] The molar concentrations of cobalt, nickel, aluminum and magnesium can be assessed, for example, by inductively coupled plasma mass spectrometry (ICP-MS). The molar concentration of fluorine can be assessed, for example, by glow discharge mass spectrometry (GD-MS).

[0074] For example, a composite oxide having a spinel crystal structure can be used as the positive electrode active material. For example, a polyanion-based material can be used as the positive electrode active material. For example, a material having an olivine crystal structure, a Nasicon-based material, etc. can be used as the polyanion-based material. For example, a material having sulfur can be used as the positive electrode active material.

[0075] Examples of materials having a spinel-type crystal structure include those having the general formula LiM 2 O 4The composite oxide represented by the above general formula LiM 2 O 4 In the above, it is preferable to have Mn as the element M. For example, LiMn 2 O 4 The above general formula LiM 2 O 4 In the above, by including Ni as the element M in addition to Mn, the discharge voltage of the secondary battery may be improved and the energy density may be improved, which is preferable. 2 O 4 Lithium-containing materials with spinel-type crystal structure containing manganese such as 2 Or LiNi 1-x M x O 2 By mixing (M=Co, Al, etc.), the characteristics of the secondary battery can be improved, which is preferable.

[0076] As the polyanion-based material, for example, a composite oxide having oxygen, a metal A, a metal M, and an element Z can be used. The metal A in the polyanion-based material is one or more of Li, Na, and Mg, the metal M in the polyanion-based material is one or more of Fe, Mn, Co, Ni, Ti, V, and Nb, and the element Z is one or more of S, P, Mo, W, As, and Si.

[0077] Examples of materials having an olivine-type crystal structure include composite materials (general formula LiMPO 4 (M is one or more of Fe(II), Mn(II), Co(II), and Ni(II)) can be used. The general formula is LiMPO 4 A representative example is LiFePO 4 , LiNiPO 4 , LiCoPO 4 , LiMnPO 4 , Life a Ni b PO 4 , Life a Co b PO 4 , Life a Mn b PO4 , LiNi a Co b PO 4 , LiNi a Mn b PO 4 (a + b is less than or equal to 1, 0 < a < 1, 0 < b < 1), LiFe c Ni d Co e PO 4 , LiFe c Ni d Mn e PO 4 , LiNi c Co d Mn e PO 4 (c + d + e is less than or equal to 1, 0 < c < 1, 0 < d < 1, 0 < e < 1), LiFe f Ni g Co h Mn i PO 4 (f + g + h + i is less than or equal to 1, 0 < f < 1, 0 < g < 1, 0 < h < 1, 0 < i < 1), lithium compounds such as these can be used.

[0078] Also, composite materials such as the general formula Li (2-j) MSiO 4 (M is one or more of Fe(II), Mn(II), Co(II), Ni(II), 0 ≤ j ≤ 2) can be used. For the general formula Li (2-j) MSiO 4 , representative examples include Li (2-j) FeSiO 4 , Li (2-j) NiSiO 4 , Li (2-j) CoSiO 4 , Li (2-j) MnSiO 4 , Li (2-j) Fe k Ni l SiO 4 , Li (2-j) Fe k Co l SiO 4 , Li (2-j) Fe k Mn l SiO 4 , Li (2-j) Nik Co l SiO 4 、Li (2-j) Ni k Mn l SiO 4 (k + l is 1 or less, 0 < k < 1, 0 < l < 1), Li (2-j) Fe m Ni n Co q SiO 4 、Li (2-j) Fe m Ni n Mn q SiO 4 、Li (2-j) Ni m Co n Mn q SiO 4 (m + n + q is 1 or less, 0 < m < 1, 0 < n < 1, 0 < q < 1), Li (2-j) Fe r Ni s Co t Mn u SiO 4 (r + s + t + u is 1 or less, 0 < r < 1, 0 < s < 1, 0 < t < 1, 0 < u < 1), etc., lithium compounds can be used as materials.

[0079] Also, A x M 2 (XO 4 ) 3 (A = Li, Na, Mg, M = Fe, Mn, Ti, V, Nb, X = S, P, Mo, W, As, Si) represented by the general formula, a NASICON-type compound can be used. As NASICON-type compounds, there are Fe 2 (MnO 4 ) 3 、Fe 2 (SO 4 ) 3 、Li 3 Fe 2 (PO 4 ) 3 etc. Also, as the positive electrode active material, Li 2 MPO 4 F, Li 2 MP 2 O 7 、Li 5 MO 4Compounds represented by the general formula (M=Fe, Mn) can be used.

[0080] In addition, NaFeF 3 , FeF 3 Perovskite-type fluorides such as TiS 2 , MoS 2 Metal chalcogenides (sulfides, selenides, tellurides), LiMVO 4 oxides with inverse spinel crystal structure such as vanadium oxides (V 2 O 5 , V 6 O 13 , LiV 3 O 8 etc.), manganese oxides, organic sulfur compounds, and other materials may also be used.

[0081] In addition, the positive electrode active material is LiMBO 3 A borate-based material represented by (M is Fe(II), Mn(II), or Co(II)) may be used.

[0082] An example of a material containing sodium is NaFeO 2 Ya, Na 2 / 3 [Fe 1 / 2 Mn 1 / 2 ]O 2 , Na 2 / 3 [Ni 1 / 3 Mn 2 / 3 ]O 2 , Na 2 Fe 2 (SO 4 ) 3 , Na 3 V 2 (PO 4 ) 3 , Na 2 FePO 4 F, NaVPO 4 F, NaMPO 4 (M is Fe(II), Mn(II), Co(II), Ni(II)), Na 2 FePO 4 F, Na 4 Co 3 (PO 4 ) 2 P2 O 7 , etc. may be used as the positive electrode active material.

[0083] In addition, lithium-containing metal sulfides may be used as the positive electrode active material. 2 TiS 3 , Li 3 NbS 4 etc.

[0084] As the positive electrode active material of one embodiment of the present invention, two or more of the materials listed above may be mixed and used.

[0085] For the negative electrode active material layer 204, silicon, carbon, titanium oxide, vanadium oxide, indium oxide, zinc oxide, tin oxide, nickel oxide, etc. can be used. In addition, materials that can be alloyed with Li, such as tin, gallium, and aluminum, can be used. Metal oxides that can be alloyed with these can also be used. In addition, lithium titanium oxide (Li 4 Ti 5 O 12 , LiTi 2 O 4 Among them, the negative electrode active material layer 204 may be made of a material containing silicon and oxygen (SiO x It is preferable to use a lithium metal film (also referred to as a lithium film) as the negative electrode active material layer 204.

[0086] In the secondary battery 200, a positive electrode, a solid electrolyte layer, and a negative electrode may be combined into one set, and multiple sets may be stacked and connected in series to increase the voltage of the secondary battery.

[0087] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0088] (Embodiment 2) In this embodiment, a configuration example of a power storage device of one embodiment of the present invention will be described.

[0089] A power storage device of one embodiment of the present invention includes a secondary battery and a battery control circuit. The battery control circuit has, for example, a function of protecting the secondary battery. The battery control circuit has, for example, a function of controlling charging of the secondary battery. The battery control circuit has, for example, a function of monitoring the voltage of the secondary battery.

[0090] The battery control circuit of one embodiment of the present invention preferably includes a transistor having an oxide semiconductor in a channel formation region (hereinafter, referred to as an OS transistor). The battery control circuit including an OS transistor will be described in detail later. The battery control circuit of one embodiment of the present invention may include a transistor having silicon, germanium, silicon germanium, silicon carbide, or the like in a channel formation region, in addition to the OS transistor.

[0091] 2 illustrates a configuration example that can be applied to a power storage device of one embodiment of the present invention. In the configuration example illustrated in FIG. 2, a secondary battery 200 and a transistor 500 that is an OS transistor included in a battery control circuit are stacked over a substrate 599. Note that although FIG. 2 illustrates an example in which one secondary battery is provided over the substrate 599, two or more secondary batteries may be provided over the substrate 599. In such a case, for example, either the positive electrode or the negative electrode of the batteries may be shared. Furthermore, it is preferable to use the same material for the positive electrode, the negative electrode, the electrolyte, and the like.

[0092] As the substrate 599, a glass substrate, a quartz substrate, a sapphire substrate, a ceramic substrate, a metal substrate (for example, a stainless steel substrate, a substrate having stainless steel foil, a tungsten substrate, a substrate having tungsten foil, etc.), a semiconductor substrate (for example, a single crystal semiconductor substrate, a polycrystalline semiconductor substrate, or a compound semiconductor substrate, etc.), an SOI (SOI: Silicon on Insulator) substrate, a plastic substrate, etc. can be used. In addition, as the substrate, a flexible substrate, a laminated film, a paper containing a fibrous material, a base film, etc. can be used. Examples of the flexible substrate, the laminated film, the base film, etc. include the following. For example, there are plastics represented by polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), and polytetrafluoroethylene (PTFE). Alternatively, as an example, there is a synthetic resin such as acrylic. Alternatively, as an example, there are polypropylene, polyester, polyvinyl fluoride, polyvinyl chloride, etc. Alternatively, examples include polyamide, polyimide, aramid resin, epoxy resin, inorganic vapor deposition film, and paper.

[0093] 2, an insulator 514 is provided over a substrate 599. A film having a barrier property that prevents diffusion of hydrogen or impurities is preferably used as the insulator 514. For example, silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, aluminum oxide, aluminum oxynitride, aluminum nitride oxide, aluminum nitride, or the like can be used as the insulator 514.

[0094] In this specification, silicon oxynitride refers to a material having a higher oxygen content than nitrogen, silicon nitride oxide refers to a material having a higher nitrogen content than oxygen, aluminum oxynitride refers to a material having a higher oxygen content than nitrogen, and aluminum nitride oxide refers to a material having a higher nitrogen content than oxygen.

[0095] <Transistor 500> In the transistor 500, a metal oxide functioning as an oxide semiconductor is preferably used for the oxide 530 including the channel formation region. For example, a metal oxide such as In-M-Zn oxide (wherein the element M is one or more elements selected from aluminum, gallium, yttrium, copper, vanadium, beryllium, boron, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, magnesium, or the like) may be used for the oxide 530.

[0096] Specifically, the oxide 530a may be a metal oxide having an atomic ratio of In:Ga:Zn=1:3:4 or 1:1:0.5. The oxide 530b may be a metal oxide having an atomic ratio of In:Ga:Zn=4:2:3 or 1:1:1. The oxide 530c may be a metal oxide having an atomic ratio of In:Ga:Zn=1:3:4, Ga:Zn=2:1, or Ga:Zn=2:5. Specific examples of the oxide 530c having a layered structure include a layered structure of In:Ga:Zn=4:2:3 [atomic ratio] and In:Ga:Zn=1:3:4 [atomic ratio], a layered structure of Ga:Zn=2:1 [atomic ratio] and In:Ga:Zn=4:2:3 [atomic ratio], a layered structure of Ga:Zn=2:5 [atomic ratio] and In:Ga:Zn=4:2:3 [atomic ratio], and a layered structure of gallium oxide and In:Ga:Zn=4:2:3 [atomic ratio].

[0097] The oxide 530b may have crystallinity. For example, it is preferable to use a c-axis aligned crystalline oxide semiconductor (CAAC-OS) described later. Crystalline oxides such as CAAC-OS have few impurities and defects (such as oxygen vacancies) and have a dense structure with high crystallinity. This can suppress the source electrode or drain electrode from extracting oxygen from the oxide 530b. Even when a heat treatment is performed, the transistor 500 is stable against high temperatures (so-called thermal budget) in the manufacturing process because the extraction of oxygen from the oxide 530b can be suppressed.

[0098] The metal oxide that functions as a channel formation region in the oxide 530 preferably has a band gap of 2 eV or more, preferably 2.5 eV or more. In this manner, by using a metal oxide with a wide band gap, the off-state current of the transistor can be reduced.

[0099] The oxide 530 has the oxide 530a below the oxide 530b, so that the diffusion of impurities from structures formed below the oxide 530a to the oxide 530b can be suppressed. Also, the oxide 530 has the oxide 530c on the oxide 530b, so that the diffusion of impurities from structures formed above the oxide 530c to the oxide 530b can be suppressed.

[0100] The oxide 530 preferably has a laminated structure of a plurality of oxide layers with different atomic ratios of each metal atom. Specifically, in the metal oxide used for the oxide 530a, the atomic ratio of element M among the constituent elements is preferably larger than the atomic ratio of element M among the constituent elements in the metal oxide used for the oxide 530b. In addition, in the metal oxide used for the oxide 530a, the atomic ratio of element M to In is preferably larger than the atomic ratio of element M to In in the metal oxide used for the oxide 530b. In addition, in the metal oxide used for the oxide 530b, the atomic ratio of In to element M is preferably larger than the atomic ratio of In to element M in the metal oxide used for the oxide 530a. In addition, the oxide 530c can use a metal oxide that can be used for the oxide 530a or the oxide 530b.

[0101] In addition, the energy of the conduction band minimum of the oxide 530a and the oxide 530c is preferably higher than that of the oxide 530b. In other words, the electron affinity of the oxide 530a and the oxide 530c is preferably smaller than that of the oxide 530b.

[0102] Here, the energy level of the conduction band minimum changes gradually at the junction of the oxide 530a, the oxide 530b, and the oxide 530c. In other words, it can be said that the energy level of the conduction band minimum at the junction of the oxide 530a, the oxide 530b, and the oxide 530c changes continuously or is a continuous junction. To achieve this, it is preferable to reduce the defect level density of the mixed layer formed at the interface between the oxide 530a and the oxide 530b and the interface between the oxide 530b and the oxide 530c.

[0103] Specifically, the oxides 530a and 530b, and the oxides 530b and 530c have a common element other than oxygen (as a main component), so that a mixed layer with a low density of defect states can be formed. For example, when the oxide 530b is an In-Ga-Zn oxide, the oxides 530a and 530c may be made of an In-Ga-Zn oxide, a Ga-Zn oxide, or a gallium oxide.

[0104] At this time, the main carrier path is the oxide 530b. By configuring the oxide 530a and the oxide 530c as described above, the defect state density at the interface between the oxide 530a and the oxide 530b and at the interface between the oxide 530b and the oxide 530c can be reduced. Therefore, the effect of interface scattering on carrier conduction is reduced, and the transistor 500 can obtain a high on-state current.

[0105] Conductors 542a and 542b functioning as a source electrode and a drain electrode are provided on the oxide 530b. As the conductors 542a and 542b, it is preferable to use a metal element selected from aluminum, chromium, copper, silver, gold, platinum, tantalum, nickel, titanium, molybdenum, tungsten, hafnium, vanadium, niobium, manganese, magnesium, zirconium, beryllium, indium, ruthenium, iridium, strontium, and lanthanum, an alloy containing the above-mentioned metal element as a component, or an alloy combining the above-mentioned metal elements. For example, it is preferable to use tantalum nitride, titanium nitride, tungsten, a nitride containing titanium and aluminum, a nitride containing tantalum and aluminum, ruthenium oxide, ruthenium nitride, an oxide containing strontium and ruthenium, an oxide containing lanthanum and nickel, or the like. In addition, tantalum nitride, titanium nitride, nitrides containing titanium and aluminum, nitrides containing tantalum and aluminum, ruthenium oxide, ruthenium nitride, oxides containing strontium and ruthenium, and oxides containing lanthanum and nickel are conductive materials that are difficult to oxidize, or materials that maintain conductivity even when oxygen is absorbed, and are therefore preferable.Furthermore, metal nitride films such as tantalum nitride are preferable because they have barrier properties against hydrogen or oxygen.

[0106] 2, the conductor 542a and the conductor 542b are shown as a single-layer structure, but may be a stacked structure of two or more layers. For example, a tantalum nitride film and a tungsten film may be stacked. A titanium film and an aluminum film may be stacked. Alternatively, a two-layer structure in which an aluminum film is stacked on a tungsten film, a two-layer structure in which a copper film is stacked on a copper-magnesium-aluminum alloy film, a two-layer structure in which a copper film is stacked on a titanium film, or a two-layer structure in which a copper film is stacked on a tungsten film may be used.

[0107] In addition, there are three-layer structures in which a titanium film or titanium nitride film is laminated on the titanium film or titanium nitride film, an aluminum film or copper film is laminated on the titanium film or titanium nitride film, and a titanium film or titanium nitride film is further formed thereon, and a three-layer structure in which a molybdenum film or molybdenum nitride film is laminated on the molybdenum film or molybdenum nitride film, an aluminum film or copper film is laminated on the molybdenum film or molybdenum nitride film, and a molybdenum film or molybdenum nitride film is further formed thereon, etc. Note that a transparent conductive material containing indium oxide, tin oxide, or zinc oxide may be used.

[0108] 2, regions 543a and 543b may be formed as low-resistance regions at and near the interface of the oxide 530 with the conductor 542a (conductor 542b). In this case, the region 543a functions as one of the source region and the drain region, and the region 543b functions as the other of the source region and the drain region. A channel formation region is formed in a region sandwiched between the regions 543a and 543b.

[0109] By providing the conductor 542a (conductor 542b) so as to be in contact with the oxide 530, the oxygen concentration in the region 543a (region 543b) may be reduced. Also, a metal compound layer containing a metal contained in the conductor 542a (conductor 542b) and a component of the oxide 530 may be formed in the region 543a (region 543b). In such a case, the carrier density in the region 543a (region 543b) increases, and the region 543a (region 543b) becomes a low-resistance region.

[0110] The insulator 544 is provided to cover the conductor 542a and the conductor 542b and suppresses oxidation of the conductor 542a and the conductor 542b. In this case, the insulator 544 may be provided to cover the side surface of the oxide 530 and to be in contact with the insulator 524.

[0111] The insulator 544 can be a metal oxide containing one or more elements selected from hafnium, aluminum, gallium, yttrium, zirconium, tungsten, titanium, tantalum, nickel, germanium, neodymium, lanthanum, magnesium, etc. Alternatively, the insulator 544 can be silicon nitride oxide, silicon nitride, or the like.

[0112] In particular, it is preferable to use, as the insulator 544, an insulator containing an oxide of either or both of aluminum and hafnium, such as aluminum oxide, hafnium oxide, or an oxide containing aluminum and hafnium (hafnium aluminate). In particular, hafnium aluminate has higher heat resistance than a hafnium oxide film. Therefore, it is preferable because it is less likely to crystallize in a heat treatment in a later step. Note that the insulator 544 is not an essential component when the conductor 542a and the conductor 542b are made of a material having oxidation resistance or when the conductivity does not decrease significantly even when oxygen is absorbed. It may be designed appropriately depending on the desired transistor characteristics.

[0113] The insulator 544 can prevent impurities such as water and hydrogen contained in the insulator 580 from diffusing to the oxide 530b through the oxide 530c and the insulator 550. The insulator 580 can also prevent the conductor 560 from being oxidized by excess oxygen contained in the insulator 580.

[0114] The insulator 550 functions as a first gate insulating film. The insulator 550 is preferably disposed in contact with the inside (top and side surfaces) of the oxide 530c. The insulator 550 is preferably formed using an insulator that contains excess oxygen and releases oxygen by heating, similar to the insulator 524 described above.

[0115] Specifically, silicon oxide having excess oxygen, silicon oxynitride, silicon nitride oxide, silicon nitride, silicon oxide to which fluorine is added, silicon oxide to which carbon is added, silicon oxide to which carbon and nitrogen are added, and silicon oxide having vacancies can be used. In particular, silicon oxide and silicon oxynitride are preferable because they are stable against heat.

[0116] By providing an insulator that releases oxygen when heated as the insulator 550 in contact with the top surface of the oxide 530c, oxygen can be effectively supplied from the insulator 550 to the channel formation region of the oxide 530b through the oxide 530c. Similarly to the insulator 524, the concentration of impurities such as water or hydrogen in the insulator 550 is preferably reduced. The thickness of the insulator 550 is preferably 1 nm or more and 20 nm or less.

[0117] Furthermore, in order to efficiently supply excess oxygen contained in the insulator 550 to the oxide 530, a metal oxide may be provided between the insulator 550 and the conductor 560. The metal oxide preferably suppresses oxygen diffusion from the insulator 550 to the conductor 560. By providing a metal oxide that suppresses oxygen diffusion, the diffusion of excess oxygen from the insulator 550 to the conductor 560 is suppressed. That is, a decrease in the amount of excess oxygen supplied to the oxide 530 can be suppressed. Furthermore, oxidation of the conductor 560 due to the excess oxygen can be suppressed. As the metal oxide, a material that can be used for the insulator 544 may be used.

[0118] The insulator 550 may have a laminated structure, similar to the second gate insulating film. As transistors become smaller and more highly integrated, problems such as leakage current may occur due to the thinning of the gate insulating film. Therefore, by making the insulator that functions as the gate insulating film a laminated structure of a high-k material and a thermally stable material, it is possible to reduce the gate potential during transistor operation while maintaining the physical film thickness. In addition, a laminated structure that is thermally stable and has a high relative dielectric constant can be obtained.

[0119] The conductor 560 functioning as the first gate electrode is shown as having a two-layer structure in FIG. 2, but may have a single-layer structure or a laminated structure of three or more layers.

[0120] The conductor 560a is a hydrogen atom, a hydrogen molecule, a water molecule, a nitrogen atom, a nitrogen molecule, or a nitrogen oxide molecule (N 2 O, NO, NO 2 It is preferable to use a conductive material having a function of suppressing the diffusion of impurities such as copper atoms, etc., or the like. Alternatively, it is preferable to use a conductive material having a function of suppressing the diffusion of oxygen (for example, at least one of oxygen atoms, oxygen molecules, etc.). When the conductor 560a has a function of suppressing the diffusion of oxygen, it is possible to suppress the conductor 560b from being oxidized by the oxygen contained in the insulator 550 and the conductivity from decreasing. As a conductive material having a function of suppressing the diffusion of oxygen, for example, tantalum, tantalum nitride, ruthenium, ruthenium oxide, or the like is preferably used. In addition, an oxide semiconductor that can be applied to the oxide 530 can be used as the conductor 560a. In that case, the conductor 560b can be formed by a sputtering method to reduce the electrical resistance value of the conductor 560a and make it a conductor. This can be called an OC (Oxide Conductor) electrode.

[0121] The conductor 560b is preferably made of a conductive material containing tungsten, copper, or aluminum as a main component. Since the conductor 560b also functions as wiring, it is preferable to use a conductor having high conductivity. For example, a conductive material containing tungsten, copper, or aluminum as a main component can be used. The conductor 560b may have a layered structure, for example, a layered structure of titanium or titanium nitride and the above conductive material.

[0122] The insulator 580 is provided on the conductor 542a and the conductor 542b via the insulator 544. The insulator 580 preferably has an excess oxygen region. For example, the insulator 580 preferably has silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, silicon oxide to which fluorine has been added, silicon oxide to which carbon has been added, silicon oxide to which carbon and nitrogen have been added, silicon oxide having voids, or a resin. In particular, silicon oxide and silicon oxynitride are preferable because they are thermally stable. In particular, silicon oxide and silicon oxide having voids are preferable because they allow for easy formation of an excess oxygen region in a later step.

[0123] The insulator 580 preferably has an excess oxygen region. By providing the insulator 580, which releases oxygen when heated, in contact with the oxide 530c, oxygen in the insulator 580 can be efficiently supplied to the oxide 530 through the oxide 530c. Note that the concentration of impurities such as water or hydrogen in the insulator 580 is preferably reduced.

[0124] The opening of the insulator 580 is formed to overlap the region between the conductor 542a and the conductor 542b. As a result, the conductor 560 is formed so as to be embedded in the opening of the insulator 580 and the region sandwiched between the conductor 542a and the conductor 542b.

[0125] In miniaturizing a semiconductor device, it is necessary to shorten the gate length, but it is also necessary to prevent the conductivity of the conductor 560 from decreasing. If the film thickness of the conductor 560 is increased for that purpose, the conductor 560 may have a shape with a high aspect ratio. In this embodiment, the conductor 560 is provided so as to be embedded in the opening of the insulator 580, so that even if the conductor 560 has a shape with a high aspect ratio, the conductor 560 can be formed without collapsing during the process.

[0126] The insulator 574 is preferably provided in contact with a top surface of the insulator 580, a top surface of the conductor 560, and a top surface of the insulator 550. By forming the insulator 574 by a sputtering method, excess oxygen regions can be provided in the insulator 550 and the insulator 580. This allows oxygen to be supplied from the excess oxygen regions into the oxide 530.

[0127] For example, the insulator 574 can be a metal oxide containing one or more elements selected from hafnium, aluminum, gallium, yttrium, zirconium, tungsten, titanium, tantalum, nickel, germanium, magnesium, and the like.

[0128] In particular, aluminum oxide has high barrier properties and can suppress the diffusion of hydrogen and nitrogen even in a thin film of 0.5 nm to 3.0 nm. Therefore, aluminum oxide formed by sputtering can function as a barrier film against impurities such as hydrogen as well as an oxygen source.

[0129] An insulator 581 functioning as an interlayer film is preferably provided over the insulator 574. Like the insulator 524, the insulator 581 preferably has a reduced concentration of impurities such as water or hydrogen.

[0130] The conductor 540a and the conductor 540b are arranged in openings formed in the insulator 581, the insulator 574, the insulator 580, and the insulator 544. The conductor 540a and the conductor 540b are provided facing each other with the conductor 560 interposed therebetween.

[0131] The conductor 610 and the secondary battery 200 are provided on the insulator 581. The conductor 610 functions as a wiring that connects to the conductor 540a.

[0132] The conductor 610 is preferably made of the same material as the positive electrode current collector 103. By using the same material for the conductor 610 and the positive electrode current collector 103, they can be formed using the same process, which makes manufacturing easy.

[0133] FIG. 3 is different from FIG. 2 in that a capacitive element 600 and a sensor element 660 are provided on an insulator 581 .

[0134] The example configuration shown in FIG. 3 includes an insulator 514 on a substrate 599, a transistor 500 on the insulator 514, an insulator 574 and an insulator 581 on the transistor 500, and conductors 540a and 540b are formed so as to be embedded in insulator 580, insulator 574 and insulator 581, with conductor 540a functioning as a plug connecting to conductor 542a and conductor 540b functioning as a plug connecting to conductor 542b.

[0135] 3, the conductor 610b is provided over the insulator 581, the insulator 611 is provided over the conductor 610b and the insulator 581, and the conductor 610 is provided over the insulator 611 to overlap with the conductor 610b. The conductor 610 and the conductor 610b function as electrodes of the capacitor 600, and a region of the insulator 611 between the conductor 610 and the conductor 610b functions as a dielectric of the capacitor 600.

[0136] In addition, in FIG. 3, the secondary battery 200 and the sensor element 660 are provided on an insulator 611 .

[0137] The sensor element 660 has a conductor 660a on an insulator 611, a conductor 660c on the conductor 660a, and a layer 660b sandwiched between the conductor 660a and the conductor 660c.

[0138] It is preferable that the conductor 610 and the conductor 660a be made of the same material as the positive electrode current collector 103.

[0139] The sensor element 660 may be, for example, a pressure sensor, a piezoelectric sensor, an acceleration sensor, a gyro sensor, a magnetic sensor, an optical sensor, an infrared sensor, a distance sensor, a pulse sensor, an ultrasonic sensor, a touch sensor, a fingerprint sensor, or the like.

[0140] The following is an example in which a piezoelectric sensor is used as the sensor element 660. By using a piezoelectric sensor, pressure, displacement, and the like can be detected.

[0141] It is preferable to use a titanium compound as the conductor 660a. Specifically, for example, it is preferable to use titanium nitride. Alternatively, it is preferable to use titanium. By using titanium nitride, the crystallinity of the layer 660b may be increased. In addition, a second conductive layer may be further provided on the conductor 660a. For example, titanium and platinum on the titanium may be stacked. By using titanium and platinum on the titanium, the crystallinity of the layer 660b may be increased.

[0142] The layer 660b may be made of a piezoelectric ceramic such as lead zirconate titanate or barium titanate. x Ti 1-x )O 3 Barium titanate is sometimes expressed as BaTiO 3 It may be expressed as:

[0143] A compound having strontium (e.g., La 0.5 Sr 0.5 Chief of Staff 3 , SrTiO 3 , SrRuO 3 etc.), lanthanum-containing compounds (LaNiO 3 ), (Bi,La) 4 Ti 3 O 12 etc.), compounds containing yttrium (e.g. Y 1 Ba 2 Cu 3 O 7-x etc.), and the like may be laminated.

[0144] As in the example of the configuration shown in FIG. 4, a transistor 500 that is an OS transistor and the secondary battery 200 may be provided in a region between an insulator 514 and an insulator 574.

[0145] The transistor 500 shown in FIG. 4 has a bottom-contact structure. In FIG. 4, a conductor 542a and a conductor 542b are provided over an insulator 524. The transistor 500 shown in FIG. 4 also includes an oxide 530 over the insulator 524, the conductor 542a, and the conductor 542b, an insulator 550 on the oxide 530, and a conductor 560 on the insulator 550. In FIG. 4, the conductor 560 and the conductor 503 are provided to overlap with each other with the oxide 530 interposed therebetween. An insulator 520, an insulator 522, and an insulator 524 are provided between the conductor 503 and the oxide 530.

[0146] 4, the secondary battery 200 is provided on an insulator 524. An insulating layer 550 is provided on the protective layer 206 of the secondary battery 200, an insulator 580 is provided on the insulating layer 550, and an insulator 574 is provided on the insulator 580.

[0147] The conductor 542a and the conductor 542b function as a source electrode and a drain electrode of the transistor 500. The conductor 542a and the conductor 542b are preferably made of the same material as the positive electrode current collector 103.

[0148] 4 and FIG. 5 described later, the transistor 500 may have the structure of the transistor shown in FIG. 2 or the like.

[0149] 5, the secondary battery 200 may be provided over a substrate 599, an insulator 580b may be provided over the secondary battery 200, an insulator 514 may be provided over the insulator 580b, and the transistor 500 may be provided over the insulator 514. For materials that can be used for the insulator 580b, the insulator 580 can be referred to.

[0150] 6, silicon, silicon germanium, or silicon carbide may be used as a substrate 599, the transistor 300 may be provided over the substrate 599, and an insulator 514, the transistor 500, a capacitor 600, a sensor element 660, and the like may be provided over the transistor 300. Part of the transistors included in the battery control circuit of one embodiment of the present invention may be formed using the transistor 300, for example.

[0151] 6 is provided on a substrate 599, and includes a conductor 316, an insulator 315, a semiconductor region 313 made of a part of the substrate 599, a low-resistance region 314a, and a low-resistance region 314b. One of the low-resistance region 314a and the low-resistance region 314b functions as a source region, and the other functions as a drain region.

[0152] In the transistor 300, the top surface and the side surface in the channel width direction of the semiconductor region 313 are covered with a conductor 316 via an insulator 315. By forming the transistor 300 as a fin type in this manner, the effective channel width is increased, and the on-characteristics can be improved. In addition, the contribution of the electric field of the gate electrode can be increased, and therefore the off-characteristics of the transistor 300 can be improved.

[0153] Note that the transistor 300 may be either a p-channel transistor or an n-channel transistor.

[0154] Low resistance region 314a and low resistance region 314b contain, in addition to the semiconductor material applied to semiconductor region 313, an element that imparts n-type conductivity, such as arsenic or phosphorus, or an element that imparts p-type conductivity, such as boron.

[0155] The conductor 316 functioning as the gate electrode can be made of a conductive material such as a semiconductor material, such as silicon, containing an element that imparts n-type conductivity, such as arsenic or phosphorus, or an element that imparts p-type conductivity, such as boron, a metal material, an alloy material, or a metal oxide material.

[0156] Since the work function is determined by the material of the conductor, the threshold voltage of the transistor can be adjusted by selecting the material of the conductor. Specifically, it is preferable to use a material such as titanium nitride or tantalum nitride for the conductor. Furthermore, in order to achieve both electrical conductivity and embeddability, it is preferable to use a metal material such as tungsten or aluminum as the conductor in a laminated state, and in particular, it is preferable to use tungsten in terms of heat resistance.

[0157] The transistor 300 may be formed using a silicon on insulator (SOI) substrate or the like.

[0158] The SOI substrate may be a SIMOX (Separation by Implanted Oxygen) substrate formed by implanting oxygen ions into a mirror-polished wafer and then heating at high temperature to form an oxide layer at a certain depth from the surface and eliminate defects in the surface layer, or an SOI substrate formed using the Smart Cut method, which cleaves a semiconductor substrate by utilizing the growth of microvoids formed by hydrogen ion implantation through heat treatment, or the ELTRAN method (registered trademark: Epitaxial Layer Transfer). A transistor formed using a single crystal substrate has a single crystal semiconductor in the channel formation region.

[0159] An insulator 320, an insulator 322, an insulator 324, and an insulator 326 are stacked in this order over the transistor 300.

[0160] As the insulators 320, 322, 324, and 326, for example, silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, aluminum oxide, aluminum oxynitride, aluminum nitride oxide, aluminum nitride, or the like can be used.

[0161] In this specification, silicon oxynitride refers to a material having a higher oxygen content than nitrogen, silicon nitride oxide refers to a material having a higher nitrogen content than oxygen, aluminum oxynitride refers to a material having a higher oxygen content than nitrogen, and aluminum nitride oxide refers to a material having a higher nitrogen content than oxygen.

[0162] The insulator 322 may function as a planarizing film that planarizes steps caused by the transistor 300 provided thereunder. For example, the top surface of the insulator 322 may be planarized by a planarization process using a chemical mechanical polishing (CMP) method or the like to improve the planarity.

[0163] The insulator 324 is preferably a film having a barrier property that prevents diffusion of hydrogen or impurities from the substrate 599 or the transistor 300 to a region where the transistor 500 is provided.

[0164] As an example of a film having a barrier property against hydrogen, for example, silicon nitride formed by a CVD method can be used. Here, when hydrogen diffuses into a semiconductor element having an oxide semiconductor such as the transistor 500, the characteristics of the semiconductor element may deteriorate. Therefore, it is preferable to use a film that suppresses the diffusion of hydrogen between the transistor 500 and the transistor 300. Specifically, the film that suppresses the diffusion of hydrogen is a film that releases a small amount of hydrogen.

[0165] The amount of desorption of hydrogen can be analyzed, for example, by using thermal desorption spectrometry (TDS). For example, the amount of desorption of hydrogen from the insulator 324 is calculated as 10×10 per area of ​​the insulator 324 when the surface temperature of the film is in the range of 50° C. to 500° C. in the TDS analysis. 15 atoms / cm 2 Less than or equal to 5×10 15 atoms / cm 2 The following is acceptable.

[0166] The insulator 326 preferably has a lower dielectric constant than the insulator 324. For example, the relative dielectric constant of the insulator 326 is preferably less than 4, and more preferably less than 3. For example, the relative dielectric constant of the insulator 326 is preferably 0.7 times or less, and more preferably 0.6 times or less, the relative dielectric constant of the insulator 324. By using a material with a low dielectric constant as the interlayer film, the parasitic capacitance generated between wirings can be reduced.

[0167] Conductors 328, 330, and the like are embedded in the insulators 320, 322, 324, and 326. The conductors 328 and 330 function as plugs or wiring. A plurality of conductors having the function of plugs or wiring may be collectively given the same reference numeral. In this specification and the like, the wiring and the plug connected to the wiring may be integral. That is, a part of the conductor may function as the wiring, and a part of the conductor may function as the plug.

[0168] As the material for each plug and wiring (conductor 328, conductor 330, etc.), a conductive material such as a metal material, an alloy material, a metal nitride material, or a metal oxide material can be used in a single layer or a laminated layer. It is preferable to use a high melting point material such as tungsten or molybdenum that has both heat resistance and conductivity, and tungsten is preferably used. Alternatively, it is preferable to form the plug and wiring from a low resistance conductive material such as aluminum or copper. By using a low resistance conductive material, the wiring resistance can be reduced.

[0169] Note that, for example, the insulator 350 is preferably an insulator having a barrier property against hydrogen, similar to the insulator 324. The conductor 330 preferably includes a conductor having a barrier property against hydrogen. In particular, a conductor having a barrier property against hydrogen is preferably formed in an opening of an insulator having a barrier property against hydrogen. With this structure, the transistor 300 and the transistor 500 can be separated by a barrier layer, and diffusion of hydrogen from the transistor 300 to the transistor 500 can be suppressed.

[0170] Note that, for example, tantalum nitride or the like may be used as the conductor having a barrier property against hydrogen. By stacking tantalum nitride and tungsten having high conductivity, diffusion of hydrogen from the transistor 300 can be suppressed while maintaining the conductivity of the wiring. In this case, it is preferable that the tantalum nitride layer having a barrier property against hydrogen be in contact with the insulator 350 having a barrier property against hydrogen.

[0171] An insulator 512 is provided over the insulator 350, and an insulator 514 is provided over the insulator 512. For materials that can be used for the insulator 512, see, for example, the insulator 326.

[0172] The transistor 500 shown in FIG. 7A is a modified example of the transistor 500 shown in FIG. 2, where FIG. 7A is a cross-sectional view of the transistor 500 in the channel length direction, and FIG. 7B is a cross-sectional view of the transistor 500 in the channel width direction.

[0173] 7A differs from the transistor 500 shown in FIG. 2A in that it does not have an oxide 530c. An insulator 550 is disposed on the bottom and side surfaces of an opening formed between the conductor 542a and the conductor 542b of the insulator 580, and a conductor 560 is disposed on the surface on which the insulator 550 is formed. Since the transistor 500 shown in FIG. 7A does not have an oxide 530c, it is possible to eliminate parasitic capacitance between the oxide 530c and the conductor 560 via the insulator 550.

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

[0175] (Embodiment 3) In order to increase the output voltage of a thin-film secondary battery, the secondary batteries can be connected in series. In the second embodiment, an example of a secondary battery having one cell is shown, but in the present embodiment, an example of a thin-film secondary battery having a plurality of cells connected in series is shown.

[0176] Fig. 8A shows a top view of the first secondary battery immediately after its formation, and Fig. 8B shows a top view of two secondary batteries connected in series. Note that in Fig. 8A and Fig. 8B, the same reference numerals are used for the same parts as in Fig. 5A shown in the second embodiment.

[0177] Fig. 8A shows the state immediately after the deposition of the negative electrode current collector 205. The shape of the top surface of the negative electrode current collector 205 is different from that of Fig. 5A. The negative electrode current collector 205 shown in Fig. 8A is in contact with a part of the side surface of the solid electrolyte layer and also in contact with the insulating surface of the substrate.

[0178] 8B, a second negative electrode active material layer is formed on a region of the negative electrode current collector 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 215 are formed thereon. Finally, a protective layer 206 is formed.

[0179] FIG. 8B shows a configuration in which two solid-state secondary batteries are arranged on a plane and connected in series.

[0180] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0181] (Embodiment 4) In this embodiment, an example of a power storage device of one embodiment of the present invention will be described.

[0182] <Example of an electricity storage device 1> Fig. 9 illustrates an example of a power storage device 90. The power storage device 90 illustrated in Fig. 9 includes a battery control circuit 91 and a battery pack 120. The battery control circuit 91 preferably includes a circuit using the above-described OS transistor.

[0183] The battery control circuit 91 includes a circuit 91a and a circuit 91b.

[0184] The circuit 91 a includes a cell balancing circuit 130 , a detection circuit 185 , a detection circuit 186 , a detection circuit MSD, a detection circuit SD, a temperature sensor TS, and a logic circuit 182 .

[0185] The circuit 91b also includes a transistor 140 and a transistor 150. Various transistors can be used as the transistor 140 and the transistor 150. Note that, as shown in FIG. 9, each of the transistor 140 and the transistor 150 preferably includes a parasitic diode.

[0186] OS transistors can be used as transistors included in the cell balance circuit 130, the detection circuits 185, 186, the detection circuits MSD, the detection circuits SD, the temperature sensor TS, and the logic circuit 182 included in the circuit 91a.

[0187] As an example of the transistor 140 and the transistor 150 included in the circuit 91b, a transistor having single crystal silicon in a channel formation region is considered. In such a case, for example, the transistor 140 and the transistor 150 can be formed on a silicon substrate, and an OS transistor can be formed thereon by a film formation process, and the circuit 91a and the circuit 91b can be formed on the same substrate. This can reduce costs, for example. In addition, the circuit can be integrated, and the circuit area can be reduced. In addition, the circuit 91a and the circuit 91b are stacked on the same substrate, and the resistance of wiring can be reduced. A large current may flow through the transistor 140 and the transistor 150, and it is preferable to reduce the wiring resistance.

[0188] The battery pack 120 has a plurality of battery cells 121. FIG. 9 shows an example having n battery cells 121. The kth battery cell (k is an integer between 1 and n) may be referred to as battery cell 121(k). The battery pack 120 has a plurality of battery cells 121 electrically connected in series. FIG. 9 shows an example in which the battery pack 120 has a plurality of battery cells 121 connected in series, but the battery pack 120 may have only one battery. Alternatively, the battery pack 120 may have a plurality of batteries, which are connected in parallel.

[0189] Here, for example, a secondary battery described in the embodiment described later can be used as the battery cell. For example, a secondary battery having a wound battery element can be used. In addition, it is preferable that the battery cell has an exterior body. For example, a cylindrical exterior body, a rectangular exterior body, or the like can be used. As a material for the exterior body, a metal plate covered with an insulator, a metal film sandwiched between insulators, or the like can be used. For example, the battery cell has a pair of a positive electrode and a negative electrode. In addition, the battery cell may have a terminal electrically connected to the positive electrode and a terminal electrically connected to the negative electrode. In addition, the battery cell may have a part of the configuration of a battery control circuit of one embodiment of the present invention.

[0190] The cell balance circuit 130 has a function of controlling charging of each battery cell 121 in the assembled battery 120. The detection circuit 185 has a function of detecting overcharging and overdischarging of the assembled battery 120. The detection circuit 186 has a function of detecting discharging overcurrent and charging overcurrent of the assembled battery 120.

[0191] The detection circuit MSD has a function of detecting a micro-short circuit.

[0192] A micro-short circuit refers to a tiny short circuit inside a secondary battery, and is not so severe that the positive and negative electrodes of the secondary battery are short-circuited to the point that charging and discharging are impossible, but rather refers to a phenomenon in which a short-circuit current flows for a short period of time at a tiny short circuit. The cause of a micro-short circuit is believed to be that multiple charging and discharging cycles cause metal elements such as lithium and cobalt to precipitate inside the battery, and the precipitates grow, causing localized current concentration in parts of the positive electrode and negative electrode, resulting in parts of the separator not functioning, or the generation of by-products.

[0193] The detection circuit SD detects, for example, a short circuit in a circuit operated using the assembled battery 120. In addition, the detection circuit SD detects the charging current and discharging current of the assembled battery 120, for example.

[0194] The battery control circuit 91 has terminals VC1 to VCN electrically connected to the positive electrodes of the n battery cells 121 in the battery pack 120, and a terminal VSSS electrically connected to the negative electrode of the nth battery cell 121.

[0195] The logic circuit 182 has a function of controlling the transistors 140 and 150 in response to output signals from the detection circuit 185, the detection circuit 186, the detection circuit SD, the detection circuit MSD, and the temperature sensor TS. The logic circuit 182 may also provide a signal to a charging circuit provided outside or inside the battery control circuit 91. In this case, for example, charging of the secondary battery is controlled in response to a signal provided from the logic circuit 182 to the charging circuit. Here, the charging circuit has a function of controlling the conditions for charging the battery, for example. Alternatively, the charging circuit provides a signal for controlling the conditions for charging the battery to another circuit, for example, a cell balance circuit, an overcharge detection circuit, the transistor 140, the transistor 150, a circuit for controlling the transistors 140 and 150, or the like, which are included in one embodiment of the present invention.

[0196] The transistor 140 and the transistor 150 have a function of controlling charging or discharging to the assembled battery 120. As an example, the transistor 140 is controlled to be in a conductive state or a non-conductive state by a control signal T1 provided by the logic circuit 182, and thus it is controlled whether or not to charge the assembled battery 120. The transistor 150 is controlled to be in a conductive state or a non-conductive state by a control signal T2 provided by the logic circuit 182, and thus it is controlled whether or not to discharge the assembled battery 120. In the example shown in FIG. 9, one of the source and the drain of the transistor 140 is electrically connected to the terminal VSSS. The other of the source and the drain of the transistor 140 is electrically connected to one of the source and the drain of the transistor 150. The other of the source and the drain of the transistor 150 is electrically connected to the terminal VM. The terminal VM is electrically connected to, for example, the negative pole of a charger. The terminal VM is also electrically connected to, for example, a load during discharging.

[0197] The battery control circuit 91 may have a function of observing the voltage value (monitor voltage) of each terminal of the battery cells 121 of the assembled battery 120 and the current value (monitor current) flowing through the assembled battery. For example, the on-current of the transistor 140 or the transistor 150 may be observed as the monitor current. Alternatively, a resistive element may be provided in series with the transistor 140 or the like, and the current value of the resistive element may be observed.

[0198] The temperature sensor TS may have a function of measuring the temperature of the battery cell 121 and controlling charging and discharging of the battery cell based on the measured temperature. For example, at a low temperature, the resistance of the secondary battery may increase, so the charging current density and the discharging current density may be reduced. At a high temperature, the resistance of the secondary battery may decrease, so the discharging current density may be increased. When the charging current is increased at a high temperature and deterioration of the characteristics of the secondary battery is concerned, for example, the charging current may be controlled to a value that suppresses deterioration. Data such as the charging conditions and the discharging conditions is preferably stored in a memory circuit or the like included in the battery control circuit 91 of one embodiment of the present invention. In addition, the temperature of the battery control circuit 91 or the assembled battery 120 may increase due to charging. In such a case, it is preferable to control charging according to the measured temperature. For example, the charging current may be suppressed as the temperature increases.

[0199] The cell balance circuit 130, the detection circuit 185, the detection circuit 186, the detection circuit MSD, the detection circuit SD, and the temperature sensor TS preferably have a memory element. The memory element can store, for example, the upper limit voltage, the lower limit voltage, the voltage corresponding to an overcurrent, the voltage corresponding to a temperature, and the like of the battery.

[0200] 10A can be used as the memory element. The memory element 114 shown in FIG 10A includes a capacitor 161 and a transistor 162.

[0201] An OS transistor is preferably used as the transistor 162. In one embodiment of the present invention, by using the memory element 114 including an OS transistor, a desired voltage can be held in the memory element by utilizing the extremely low leakage current (hereinafter referred to as off-current) that flows between the source and drain in an off state.

[0202] 10B differs from FIG. 10A in that the transistor 162 included in the memory element 114 has a second gate. The second gate may be called a back gate or a bottom gate. The second gate of the OS transistor will be described in detail in a later embodiment.

[0203] Next, the components of the cell balancing circuit 130 and the detection circuit 185 will be described.

[0204] FIG. 11 shows a cell balancing circuit 130a and a detection circuit 185a corresponding to one battery cell 121.

[0205] 9 has multiple cell balancing circuits 130a, with one cell balancing circuit 130a connected to one battery cell. In a configuration in which multiple battery cells 121 are connected in series, a cell balancing circuit 130a and a transistor 132 are provided for each battery cell 121, and the transistors 132 are directly connected, thereby reducing variations in charging voltage between the battery cells 121 when charging the multiple battery cells 121 connected in series.

[0206] The detection circuit 185a shown in Fig. 11 includes a circuit 185c and a circuit 185d. The detection circuit 185c has a function of detecting overcharging, and the detection circuit 185d has a function of detecting overdischarging.

[0207] The detection circuit 185 shown in Fig. 9 has multiple detection circuits 185a, and one detection circuit 185a is connected to one battery cell. Alternatively, the detection circuit shown in Fig. 9 may be provided with one detection circuit 185a for a configuration in which multiple battery cells 121 are connected in series.

[0208] 11, a transistor 132 and a resistance element 131 are connected in series, one of the source and drain of the transistor 132 is electrically connected to the negative electrode of the battery cell 121, and the other is electrically connected to one electrode of the resistance element. The other electrode of the resistance element is electrically connected to the positive electrode of the secondary battery.

[0209] Here, one of the source and drain of the transistor 132 may be electrically connected to the positive electrode of the battery cell 121, the other to one electrode of the resistive element 131, and the other electrode of the resistive element 131 to the negative electrode of the battery cell 121.

[0210] 11, the cell balance circuit 130a, the circuit 185c, and the circuit 185d each include a comparator 113 and a storage element 114. The storage element 114 includes a capacitor 161 and a transistor 162. The storage element 114 is electrically connected to one of the non-inverting input terminal or the inverting input terminal of each of the comparators 113 included in the cell balance circuit 130a, the circuit 185c, and the circuit 185d. In the storage element 114, a common terminal, here a terminal VT, is electrically connected to one of the source and the drain of the transistor 162 included in each of the storage elements 114. In the storage element 114, a terminal (terminal SH6 in the cell balance circuit a130, terminal SH1 in the circuit 185c, and terminal SH2 in the circuit 185d) is electrically connected to the gate of the transistor 162 included in each of the storage elements 114.

[0211] In FIG. 11, the cell balance circuit 130a is electrically connected to the positive and negative electrodes of the battery cell 121. The positive electrode of the battery cell 121 is electrically connected to a terminal VC1, and the negative electrode is electrically connected to a terminal VC2. In the cell balance circuit 130a, the other of the source and drain of the transistor 162 included in the memory element 114 is electrically connected to an inverting input terminal of the comparator 113. In the cell balance circuit 130a, it is preferable that the non-inverting input terminal of the comparator 113 is electrically connected to the terminal VC1. Alternatively, as shown in FIG. 11, a voltage obtained by dividing the voltage between the terminals VC1 and VC2 by resistors may be applied to the non-inverting input terminal of the comparator 113. In the cell balance circuit 130a, a node connected to the other of the source and drain of the transistor 162 included in the memory element 114 is referred to as a node N6.

[0212] In Fig. 11, the detection circuit 185a is electrically connected to the positive and negative electrodes of the battery cell 121. In the circuit 185c, the other of the source and drain of the transistor 162 is electrically connected to an inverting input terminal of a comparator. In the circuit 185c, the non-inverting input terminal of the comparator 113 is preferably electrically connected to the terminal VC1. Alternatively, as shown in Fig. 11, a voltage obtained by resistor division between the terminals VC1 and VC2 may be applied to the non-inverting input terminal of the comparator 113. In the circuit 185c, a node connected to the other of the source and drain of the transistor 162 is referred to as a node N1.

[0213] In the circuit 185d, the non-inverting input terminal of the comparator is electrically connected to the other of the source and drain of the transistor 162. In the circuit 185d, the inverting input terminal of the comparator 113 is preferably electrically connected to the terminal VC1. Alternatively, as shown in FIG. 11, a voltage obtained by resistor-dividing between the terminals VC1 and VC2 may be applied to the inverting input terminal of the comparator 113. In the circuit 185d, a node connected to the other of the source and drain of the transistor 162 is referred to as a node N2.

[0214] In the cell balance circuit 130a and the detection circuit 185a, a node (here, node N6, node N1, and node N2) to which the other electrode of the capacitance element 161 of each circuit is connected is held by turning off the transistor 162.

[0215] The terminal VT sequentially supplies an analog signal to the cell balance circuit 130a, the circuit 185c, and the circuit 185d. The analog signal is sequentially supplied to the node N6, the node N1, and the node N2, and is held therein. After the analog signal is supplied to the first node among the nodes N6, N1, and N2, the transistor 162 connected to the node is turned off, thereby holding the potential of the first node. Thereafter, a potential is supplied to the second node and held therein, and then a potential is supplied to the third node and held therein. The on and off control of the transistor 162 is controlled by signals supplied to the terminals SH1, SH2, and SH6.

[0216] 11 is provided for each of the battery cells 121 in the battery pack 120, it is possible to individually control the voltage difference (the voltage difference between the positive electrode and the negative electrode) across each of the battery cells 121. The cell balancing circuit 130a can also store in the memory element 114 a value that is preferable as the first upper limit voltage of the positive electrode for each battery cell 121.

[0217] The cell balance circuit 130a controls whether to turn the transistor 132 on or off depending on the relationship between the voltage of the positive electrode of the battery cell 121 and the voltage of the non-inverting input terminal of the comparator 113. By controlling the transistor 132, it is possible to adjust the ratio between the amount of current flowing through the resistance element 131 and the amount of current flowing through the battery cell 121. For example, when charging of the battery cell 121 is stopped, a current is caused to flow through the resistance element 131, and the current flowing through the battery cell 121 is limited.

[0218] 9, a plurality of battery cells 121 are electrically connected in series between terminals VC1 and VSSS. The plurality of battery cells 121 are charged by causing a current to flow between terminals VC1 and VSSS.

[0219] Consider a case where the positive electrode of one of the multiple battery cells 121 reaches a predetermined voltage and the current is limited. In such a case, by passing a current through the transistor 132 and the resistance element 131 connected in parallel to the battery cell, the current path between the terminal VC1 and the terminal VSSS is not interrupted and the charging of the other battery cells 121 whose positive electrodes have not yet reached the predetermined voltage can be continued. That is, in the battery cell 121 in which charging has been completed, charging is stopped by turning on the transistor 132, and in the battery cell 121 in which charging has not been completed, charging is continued by turning off the transistor 132.

[0220] For example, if there is a variation in resistance among the battery cells 121, charging of a certain battery cell 121 with low resistance may be completed first, and charging of a battery cell 121 with a higher resistance compared to another battery cell 121 may be insufficient. Here, insufficient charging refers to, for example, the voltage difference between the positive electrode and the negative electrode being lower than the desired voltage. By using the cell balance circuit 130, the voltage of the positive electrode of the battery cell 121 during charging can be controlled based on the voltage of the negative electrode of each battery cell.

[0221] In the cell balance circuit of one embodiment of the present invention, the charging voltage, charging capacity, and the like of one battery cell or multiple battery cells can be controlled without using a circuit provided outside the battery control circuit 91, such as an arithmetic circuit such as an MPU or MCU.

[0222] That is, by using N cell balance circuits 130a, it is possible to reduce variation in the state after charging the multiple battery cells 121, for example, when fully charged. This may increase the capacity of the assembled battery 120 as a whole. In addition, by increasing the capacity, it may be possible to reduce the number of charge / discharge cycles of the battery cells 121, which may increase the durability of the assembled battery 120.

[0223] The circuit 185c can cause the memory element 114 to store a second upper limit voltage of the positive electrode in charging the battery cell 121 for each battery cell 121. The second upper limit voltage may be called an overcharge voltage. The circuit 185d can cause the memory element 114 to store a lower limit voltage of the positive electrode in discharging. The lower limit voltage may be called an overdischarge voltage.

[0224] The comparator constituting the detection circuit 185 may have different thresholds when the output changes from an L level to an H level and when the output changes from an H level to an L level, that is, may be a hysteresis comparator. It is preferable that the storage element connected to the input section of the reference potential of the hysteresis comparator has a function of holding two thresholds.

[0225] The detection circuit 185 can detect overcharging and overdischarging of one battery cell or multiple battery cells and protect the battery cells without using a circuit provided outside the battery control circuit 91, for example, an arithmetic circuit such as an MPU or MCU. When a voltage drop due to overdischarge is detected, the control circuit of one embodiment of the present invention cuts off the discharge current to prevent the voltage drop. If the discharge current is not sufficiently cut off, a leakage current may occur, causing a voltage drop. A circuit configuration using power gating may suppress the leakage current. Furthermore, a circuit configuration using OS transistors may suppress the leakage current.

[0226] The upper limit voltage of the battery cell is controlled by a cell balancing circuit connected to the battery cell and a circuit for detecting overcharging. The upper limit voltage detected by the cell balancing circuit is, for example, lower than the upper limit voltage detected by the circuit for detecting overcharging. Therefore, in the charging process, the cell balancing circuit detects the battery cell reaching the upper limit voltage in a first step and changes the charging conditions. Here, for example, the charging current density is lowered. Alternatively, discharging may be started. Thereafter, when the battery cell's charging voltage increases and it is detected that the upper limit voltage detected by the circuit for detecting overcharging is reached, the charging conditions of the battery cell are changed in a second step. Here, for example, charging is stopped and discharging is started.

[0227] <Further components of the power storage device> An example of further components included in the power storage device of one embodiment of the present invention will be described below.

[0228] The battery control circuit 91 also has a terminal group AH. The terminal group AH has one terminal or a plurality of terminals.

[0229] 12, the terminal group AH is connected to the logic circuit 182. The terminal group AH preferably has a function of providing a signal to the logic circuit 182 and a function of providing a signal from the logic circuit 182 to a circuit provided outside the battery control circuit 91.

[0230] FIG. 12A illustrates an example of a logic circuit 182. The logic circuit 182 illustrated in FIG. 12A includes an interface circuit IF, a counter circuit CND, a latch circuit LTC, and a transistor 172. An OS transistor is preferably used as the transistor 172. Note that the configuration illustrated in FIG. 12A may be formed only from OS transistors included in the battery control circuit of one embodiment of the present invention, or only a part of the configuration illustrated in FIG. 12A may be formed from OS transistors included in the battery control circuit of one embodiment of the present invention. When only a part of the configuration illustrated in FIG. 12A is formed from OS transistors included in the battery control circuit of one embodiment of the present invention, the other part is formed from, for example, transistors having single crystal silicon.

[0231] The interface circuit IF is supplied with signals from output terminals OUT11 and OUT12 of the detection circuit 185, signals from output terminals OUT31 and OUT32 of the detection circuit 186, and a signal from an output terminal OUT41 of the detection circuit SD. The output terminal OUT11 supplies, for example, a signal corresponding to overcharging. The output terminal OUT12 supplies, for example, a signal corresponding to overdischarging. The output terminal OUT31 supplies, for example, a signal corresponding to an overcurrent during charging. The output terminal OUT32 supplies, for example, a signal corresponding to an overcurrent during discharging.

[0232] The interface circuit IF provides a signal PG to the gate of the transistor 172 when detecting a signal that detects an abnormality, for example a signal that corresponds to at least one of overcharging, overdischarging, and overcurrent.

[0233] The transistor 172 is connected to the counter circuit CND.

[0234] The counter circuit CND operates the counter and the delay circuit when the signal PG outputs a signal that turns on the transistor 172, more specifically, a high potential signal, for example. On the other hand, when the signal PG outputs a signal that turns off the transistor 172, more specifically, a low potential signal, for example, the counter circuit CND can stop operating or put the counter circuit CND into a standby state. The interface circuit IF provides the counter circuit CND and the latch circuit LTC with a signal res. The signal res is a reset signal. The counter circuit CND is provided with the signal res and starts counting. The signal en is an enable signal. The counter circuit CND starts or stops operating according to the signal en.

[0235] When a signal detecting an abnormality is given to the interface circuit IF, the counter circuit CND counts for a certain period of time, and then a signal corresponding to the detected abnormality is given to the latch circuit LTC via the counter circuit CND.

[0236] The latch circuit LTC applies a signal to the gate of the transistor 140 or the transistor 150 in response to the detected abnormality, to turn the transistor off.

[0237] 13A shows an example of a circuit diagram of the detection circuit 186. The detection circuit 186 has two comparators 113.

[0238] A memory element 114 that holds a voltage corresponding to discharge overcurrent detection is electrically connected to the non-inverting input terminal of one comparator 113. A terminal SH3 is electrically connected to the gate of a transistor in the memory element 114. In addition, a terminal SENS is electrically connected to the inverting input terminal. When an overcurrent is detected by the voltage applied to the inverting input terminal, the output from the output terminal OUT32 is inverted.

[0239] The terminal SENS is electrically connected to the non-inverting input terminal of the other comparator 113. In addition, a memory element 114 that holds a voltage corresponding to charging overcurrent detection is electrically connected to the inverting input terminal. A terminal SH4 is electrically connected to the gate of a transistor in the memory element 114. When an overcurrent is detected by the voltage applied to the non-inverting input terminal, the output from the output terminal OUT31 is inverted.

[0240] The temperature sensor TS has a function of measuring the temperature of the battery pack 120 or the power storage device 90 including the battery pack 120. Fig. 13B is a circuit diagram showing an example of the temperature sensor TS. Note that the circuit diagram shown in Fig. 13B may show a part of the circuit of the temperature sensor TS.

[0241] 13B, the temperature sensor TS has three comparators 113, and voltages VT (VT=Tm1, Tm2, ​​Tm3) corresponding to different temperatures are respectively applied to the inverting input terminals of the comparators. Each applied voltage VT is held by a memory element 114 electrically connected to the inverting input terminal. The voltages Tm1, Tm2, ​​Tm3 may be applied from the battery control circuit 91, for example.

[0242] A voltage corresponding to the measured temperature is applied to the input terminal Vt. The input terminal Vt is applied to the non-inverting input terminals of three comparators 113.

[0243] Corresponding to the comparison result between the voltage applied to the input terminal Vt and the voltage at the inverting input terminal of each comparator 113, a signal is output from the output terminal of each comparator (output terminal OUT51, output terminal OUT52, output terminal OUT53), and the temperature can be determined.

[0244] OS transistors have the property that their resistance decreases as the temperature rises. Using this property, the ambient temperature can be converted into a voltage. This voltage can be applied to the input terminal Vt, for example.

[0245] The logic circuit 182 may be configured to detect the output of the temperature sensor TS, and when the temperature exceeds the operable temperature range of the battery pack 120, to make the transistor 140 and / or the transistor 150 non-conductive and stop charging and / or discharging.

[0246] <Battery cell> As the battery cell 121, the secondary battery 200 shown in the above embodiment can be used.

[0247] <Transistor> In one embodiment of the present invention, a memory element including an OS transistor is used, and a reference voltage can be held in the memory element by utilizing the extremely low leakage current (hereinafter, off-current) that flows between the source and drain in an off state. In this case, the power supply of the memory element can be turned off, so that the use of a memory element including an OS transistor allows the reference voltage to be held with extremely low power consumption.

[0248] In addition, a memory element having an OS transistor can hold an analog potential. For example, the voltage of a secondary battery can be held in the memory element without being converted into a digital value using an analog-to-digital conversion circuit. Since a conversion circuit is not required, the circuit area can be reduced.

[0249] In addition, in a memory element using an OS transistor, the reference voltage can be rewritten and read by charging or discharging an electric charge, so that the monitor voltage can be acquired and read substantially unlimited times. A memory element using an OS transistor has excellent rewrite endurance because it does not involve structural changes at the atomic level, as in a magnetic memory or a resistive memory. Furthermore, a memory element using an OS transistor does not exhibit instability due to an increase in electron trap centers even when repeatedly rewritten, as in a flash memory.

[0250] In addition, the OS transistor has characteristics such as an extremely low off-state current and good switching characteristics even in a high-temperature environment, so that the charging or discharging of the battery pack 120 can be controlled without malfunction even in a high-temperature environment.

[0251] In addition, memory elements using OS transistors can be freely arranged by stacking them on circuits using Si transistors, making integration easy. In addition, OS transistors can be manufactured using the same manufacturing equipment as Si transistors, so they can be manufactured at low cost.

[0252] Furthermore, if an OS transistor includes a back gate electrode in addition to a gate electrode, a source electrode, and a drain electrode, it can be a four-terminal semiconductor element. It can be configured as an electric circuit network that can independently control the input and output of signals flowing between the source and drain according to the voltage applied to the gate electrode or the back gate electrode. Therefore, the circuit can be designed with the same concept as that of an LSI. In addition, OS transistors have better electric characteristics than Si transistors in high-temperature environments. Specifically, the ratio of on-current to off-current is large even at high temperatures of 100°C to 200°C, preferably 125°C to 150°C, so that good switching operation can be performed.

[0253] An OS transistor is preferably used as the transistor 162. Alternatively, an OS transistor may be used as the transistor 132.

[0254] The comparator may also be formed using OS transistors.

[0255] This embodiment mode can be appropriately combined with the descriptions of other embodiment modes.

[0256] (Embodiment 5) In this embodiment, an example of a detection circuit included in a battery control circuit according to one embodiment of the present invention will be described. The semiconductor device according to one embodiment of the present invention has a function of detecting an instantaneous potential change (here, a drop in potential) due to a micro-short circuit by sampling (acquiring) a potential between a positive electrode and a negative electrode of a secondary battery at predetermined time intervals during charging and discharging, and comparing the sampled potential with the potential between the positive electrode and the negative electrode after sampling. By repeating sampling at predetermined time intervals, the semiconductor device can respond to the potential change of the secondary battery during charging and discharging, and can be operated using the potential between the positive electrode and the negative electrode of the secondary battery.

[0257] In this embodiment, the potential fluctuation of the secondary battery and the semiconductor device during charging will be described using a timing chart, etc. The potential fluctuation during discharging will be easily understood by those skilled in the art, so the description thereof will be omitted.

[0258] <An example of a detection circuit> 14A is a circuit diagram showing a configuration example of the detection circuit MSD. The detection circuit MSD has transistors 11 to 15, a capacitance element C11, and a comparator 50. In the drawings described in this specification, the flow of main signals is indicated by arrows or lines, and power lines and the like may be omitted. A hysteresis comparator may be used as the comparator 50 of the detection circuit MSD. The detection circuit MSD may perform detection on a plurality of battery cells connected in series, or may perform detection on each battery cell.

[0259] The detection circuit MSD illustrated in FIG. 14A also includes a terminal VC1, a wiring VB1_IN to which a predetermined potential VB1 is supplied, a wiring VB2_IN to which a predetermined potential VB2 is supplied, a wiring SH_IN to which a sampling signal is supplied, and an output terminal S_OUT.

[0260] Here, the predetermined potential VB1 is a potential higher than the predetermined potential VB2, and the predetermined potential VB2 is a potential higher than the potential of the terminal VSSS.

[0261] FIG. 14B differs from FIG. 14A in that the transistors 11 to 15 in the detection circuit MSD have second gates.

[0262] 14C differs from FIG. 14B in that it includes a terminal VSSS, a memory element 114 connected to a wiring VB1_IN, and a memory element 114 connected to a wiring VB2_IN. In FIG. 14C, one of the source and drain of the transistor 11, one of the source and drain of the transistor 13, and one electrode of the capacitor C11 are electrically connected to the terminal VSSS. Since the potentials VB1 and VB2 are applied to the wiring VB1_IN and the wiring VB2_IN through the memory element 114, respectively, the potentials applied by the memory element 114 can be held. Therefore, the power supply of the voltage generating circuit that supplies the potentials VB1 and VB2 can be turned off or put into a standby state.

[0263] The transistors 11 to 15 are n-channel transistors. In this specification and the like, an example in which the detection circuit MSD is configured using n-channel transistors is shown, but p-channel transistors may be used. Those skilled in the art can easily understand how to change a circuit diagram configured using n-channel transistors to a p-channel transistor, and therefore a description thereof will be omitted.

[0264] In the detection circuit MSD, one of the source and drain of transistor 11 is electrically connected to terminal VSSS, the other of the source and drain of transistor 11 is electrically connected to one of the source and drain of transistor 12 and one of the source and drain of transistor 15, the gate of transistor 11 is electrically connected to wiring VB1_IN, and the other of the source and drain of transistor 12 and the gate of transistor 12 are electrically connected to terminal VC1.

[0265] One of the source and drain of transistor 13 is electrically connected to terminal VSSS, the other of the source and drain of transistor 13 is electrically connected to one of the source and drain of transistor 14 and the inverting input terminal of comparator 50, the gate of transistor 13 is electrically connected to wiring VB2_IN, and the other of the source and drain of transistor 14 and the gate of transistor 14 are electrically connected to terminal VC1.

[0266] The other of the source and drain of the transistor 15 is electrically connected to the other terminal of the capacitance element C11 and the non-inverting input terminal of the comparator 50, the gate of the transistor 15 is electrically connected to the wiring SH_IN, one terminal of the capacitance element C11 is electrically connected to the terminal VSSS, and the output terminal of the comparator 50 is electrically connected to the output terminal S_OUT. Note that the one terminal of the capacitance element C11 may be electrically connected to a wiring other than the terminal VSSS as long as it is a wiring to which a predetermined potential is supplied.

[0267] Here, the connection part where the other of the source and drain of transistor 11, one of the source and drain of transistor 12, and one of the source and drain of transistor 15 are electrically connected is referred to as node N11, the connection part where the other of the source and drain of transistor 13, one of the source and drain of transistor 14, and the inverting input terminal of comparator 50 are electrically connected is referred to as node N12, and the connection part where the other of the source and drain of transistor 15, the other terminal of capacitive element C11, and the non-inverting input terminal of comparator 50 are electrically connected is referred to as node N13.

[0268] Moreover, transistors 11 and 12 constitute a first source follower, and transistors 13 and 14 constitute a second source follower. That is, the gate of transistor 11 corresponds to the input of the first source follower, which outputs to node N11. The gate of transistor 13 corresponds to the input of the second source follower, which outputs to node N12.

[0269] An example of the operation of the detection circuit MSD will be described with reference to the circuit shown in FIG. 14C.

[0270] When charging of the battery pack is started, the sampling signal provided to the line SH_IN goes high at predetermined time intervals. A potential higher than the potential VB2 is provided as the potential VB1. As the charging proceeds, the potentials of the nodes N11 and N12 rise.

[0271] When the positive electrode potential drops instantaneously due to the occurrence of a microshort circuit, the potentials of the nodes N11 and N12 drop instantaneously. On the other hand, when the sampling signal provided to the wiring SH_IN is at a low level, the potential of the node N13 is not affected by the potential of the node N11, and the potential of the node N12 becomes lower than the potential of the node N13. Then, the output of the comparator 50 is inverted, and a microshort circuit is detected.

[0272] Also, in order to improve the accuracy of detecting a micro-short circuit, the voltage of the secondary battery may be converted to digital data by an analog-digital conversion circuit, and a processor unit or the like may be used to perform calculations based on the digital data, analyze the charging waveform or discharging waveform, and detect or predict a micro-short circuit. For example, in the charging waveform or discharging waveform, the displacement of the voltage error at each time step is used to detect or predict a micro-short circuit. The displacement of the voltage error is found by calculating the voltage error and calculating the difference from the previous step.

[0273] To improve the accuracy of detecting micro-shorts, a neural network may be used.

[0274] A neural network is a method and neural network processing performed by a neural network section (including, for example, a CPU (Central Processor Unit), a GPU (Graphics Processing Unit), an APU (Accelerated Processing Unit), memory, etc.). Note that an APU refers to a chip that integrates a CPU and a GPU into one.

[0275] The discharge of secondary batteries installed in devices is random as it tends to depend on the usage method of the user, but the charging conditions are fixed for charging, so the charging curve is easier to predict than discharging. By using a certain number of charging curves as learning data, it is possible to predict accurate values ​​using a neural network. Once the charging curve is obtained, it is possible to obtain the SOC (State of charge) and other values ​​using the neural network. For example, a microprocessor can be used to calculate the neural network.

[0276] Specifically, the various data obtained is evaluated and learned using machine learning or artificial intelligence, the predicted degree of deterioration of the secondary battery is analyzed, and if an abnormality is detected, charging of the secondary battery is stopped or the current density of constant current charging is adjusted.

[0277] For example, in an electric vehicle, learning data can be acquired while the vehicle is running, and the deterioration state of the secondary battery can be grasped. A neural network is used to predict the deterioration state of the secondary battery. The neural network can be configured as a neural network having multiple hidden layers, that is, a deep neural network. Learning in a deep neural network is sometimes called deep learning.

[0278] In machine learning, first, feature values ​​are extracted from training data. Relative amounts of change that change over time are extracted as feature values, and a neural network is trained based on the extracted feature values. The training means can train the neural network based on different training patterns for each time interval. The connection weights applied to the neural network can be updated according to the training results based on the training data.

[0279] As a method for estimating the state of charge of a secondary battery using a neural network, the state of charge can also be obtained by performing calculation processing using a regression model, for example, a Kalman filter.

[0280] The Kalman filter is a type of infinite impulse response filter. Multiple regression analysis is a type of multivariate analysis in which multiple independent variables are used in regression analysis. Examples of multiple regression analysis include the least squares method. While regression analysis requires many time series of observed values, the Kalman filter has the advantage that it can sequentially obtain optimal correction coefficients as long as a certain amount of data is accumulated. The Kalman filter can also be applied to non-stationary time series.

[0281] A nonlinear Kalman filter (specifically, an unscented Kalman filter (also called UKF)) can be used to estimate the internal resistance and state of charge (SOC) of a secondary battery. An extended Kalman filter (also called EKF) can also be used. SOC indicates the state of charge (also called the charge rate), and is an index in which a fully charged state is 100% and a completely discharged state is 0%.

[0282] The initial parameters obtained by the optimization algorithm are collected every n cycles (n is an integer, for example, 50), and this data set is used as training data for neural network processing, enabling highly accurate estimation of the SOC.

[0283] The learning system includes a teacher data creation device and a learning device. The teacher data creation device creates teacher data used by the learning device when learning. The teacher data includes data that is the same as the data to be processed and the recognition target, and an evaluation of the label corresponding to the data. The teacher data creation device includes an input data acquisition unit, an evaluation acquisition unit, and a teacher data creation unit. The input data acquisition unit may acquire data from data stored in a storage device, or may acquire learning input data via the Internet. The input data is data used for learning, and includes a current value and a voltage value of a secondary battery. The teacher data does not have to be actual measurement data, and data close to the actual measurement may be created by setting conditions for initial parameters, and a predetermined characteristic database of the data may be used as the teacher data to perform neural network processing to estimate the state of charge (SOC). The SOC of the same type of battery can be efficiently estimated by creating data close to the actual measurement based on the charge and discharge characteristics of a certain battery, and performing neural network processing using the predetermined characteristic database of the data as the teacher data.

[0284] When the secondary battery is deteriorated, if the FCC of the initial parameter changes significantly, an error in the SOC may occur, so the initial parameter used in the calculation for estimating the SOC may be updated. The updated initial parameter is calculated by an optimization algorithm using data of charge / discharge characteristics actually measured in advance. By performing calculation processing using a regression model, such as a Kalman filter, using the updated initial parameter, it is possible to estimate the SOC with high accuracy even after deterioration. In this specification, calculation processing using a Kalman filter is also expressed as Kalman filter processing.

[0285] The timing for updating the initial parameters may be arbitrary, but in order to estimate the SOC with high accuracy, it is preferable to update the parameters frequently, and it is preferable to update the parameters periodically and continuously. In addition, when the temperature of the secondary battery is high, if the SOC is high, deterioration may progress easily. In such a case, it is preferable to suppress deterioration of the secondary battery by discharging the secondary battery and lowering the SOC.

[0286] This embodiment mode can be appropriately combined with the descriptions of other embodiment modes.

[0287] (Embodiment 6) This embodiment shows an example of the configuration of a comparator.

[0288] 15A shows an example of the configuration of the comparator 50 described in the previous embodiment. The comparator 50 has transistors 21 to 25. The comparator 50 also has a wiring VBM_IN to which a negative electrode potential of the secondary battery is supplied, a wiring VBP_IN to which a positive electrode potential VBP of the secondary battery is supplied, a wiring VB3_IN to which a predetermined potential VB3 is supplied, an input terminal CP1_IN, an input terminal CM1_IN, an output terminal CP1_OUT, and an output terminal CM1_OUT.

[0289] When the comparator 50 in FIG. 15A is applied to the cell balancing circuit 130 and the detection circuit 185, for example, a potential is connected from the terminal VC1 to the wiring VBP_IN, and a potential is connected from the terminal VC2 to the wiring VBM_IN.

[0290] Here, the predetermined potential VB3 is a potential higher than the negative electrode potential VBM, and in the comparator 50, the positive electrode potential VBP is a high power supply potential, and the negative electrode potential VBM is a low power supply potential.

[0291] In the comparator 50, one of the source and drain of the transistor 21 is electrically connected to the wiring VBM_IN, the other of the source and drain of the transistor 21 is electrically connected to one of the source and drain of the transistor 22 and one of the source and drain of the transistor 24, and the gate of the transistor 21 is electrically connected to the wiring VB3_IN.

[0292] The other of the source and drain of transistor 22 is electrically connected to one of the source and drain of transistor 23 and the output terminal CM1_OUT, the other of the source and drain of transistor 23 and the gate of transistor 23 are electrically connected to wiring VBP_IN, and the gate of transistor 22 is electrically connected to the input terminal CP1_IN.

[0293] The other of the source and drain of transistor 24 is electrically connected to one of the source and drain of transistor 25 and the output terminal CP1_OUT, the other of the source and drain of transistor 25 and the gate of transistor 25 are electrically connected to wiring VBP_IN, and the gate of transistor 24 is electrically connected to the input terminal CM1_IN.

[0294] 15A may be connected in parallel to be used as comparator 50. That is, the output of the comparator shown in Fig. 15A may be input to the next-stage comparator 50, and multiple comparators may be connected and used.

[0295] Note that the transistor included in the circuit shown in Fig. 15A may have a backgate as shown in Fig. 15B. A voltage can be applied to the backgate and held by a holding circuit 99. In the holding circuit 99, one of the source and drain of the transistor 99a is electrically connected to the terminal SH_99, and the other is electrically connected to the backgate of the transistor 22, the backgate of the transistor 24, and one electrode of the capacitor 99b.

[0296] In the holding circuit 99, a voltage to be applied to the backgate is applied to the terminal SH_99, the transistor 99a is turned on to apply the voltage to the backgates of the transistors 22 and 24, and then the transistor 99a is turned off, thereby holding the voltage of the backgates. By using an OS transistor as the transistor 99a, a leakage current (hereinafter, off-current) flowing between the source and drain when the transistor 99a is off is extremely low, so that a desired voltage can be held in the backgates of the transistors 22 and 24.

[0297] The voltage applied to the terminal SH_99 is, for example, applied from a secondary battery 99f to a conversion circuit 99e, passed through the conversion circuit 99e, and then applied to a boost circuit 99c, where it is boosted and then applied to the terminal SH_99. A signal is applied to the boost circuit 99c from a clock generation circuit 99d. The conversion circuit 99e, the boost circuit 99c, and the clock generation circuit 99d can be configured using OS transistors.

[0298] In the power storage device of one embodiment of the present invention, two or more secondary batteries may be provided over a substrate. For example, a secondary battery 99f may be provided in addition to a secondary battery (here referred to as a first secondary battery) for sharing power from the power storage device to an electronic device or the like described later. In such a case, the capacity of the secondary battery 99f may be smaller than that of the first secondary battery, for example, 0.1 times or less or 0.01 times or less.

[0299] FIG. 12B shows an example of the configuration of a clock buffer circuit 99g to which signals are applied from a booster circuit 99c and a clock generating circuit 99d.

[0300] (Clock buffer circuit) The clock buffer circuit 99g includes inverters 70 to 75 and terminals a1 to a3. The clock buffer circuit 99g has a function of generating signals CK1_cp and CKB1_cp from the signal CLK_cp. The terminal a1 is an input terminal for the signal CLK_cp, and the terminals a2 and a3 are output terminals for the signals CK1_cp and CKB1_cp. The signal CLK_cp is a clock signal. The power storage device of one embodiment of the present invention may have a function of dividing a reference clock signal to generate the signal CLK_cp. The signals CK1_cp and CKB1_cp are complementary clock signals.

[0301] (Boost circuit) The boost circuit 99c is a step-down charge pump and has a function of stepping down the potential GND to generate the potential Vcp1. Note that the input potential is not limited to the potential GND. The boost circuit 99c includes transistors MN61 to MN65 and capacitance elements C61 to C65. The number of stages in the boost circuit 99c is five, but the number of stages is not limited to this.

[0302] This embodiment mode can be appropriately combined with the descriptions of other embodiment modes.

[0303] (Embodiment 7) In this embodiment, examples of electronic devices using a power storage device of one embodiment of the present invention will be described with reference to Fig. 16 and Fig. 17A to Fig. 17C. In the power storage device of one embodiment of the present invention, a secondary battery and a battery control circuit can be provided over the same substrate, which enables the electronic device to be miniaturized and improves the safety of the secondary battery. In addition, the power storage device of one embodiment of the present invention has a characteristic of being thin because it can be provided over a substrate.

[0304] 16 illustrates an IC card as an example of an application device using a power storage device of one embodiment of the present invention. Power obtained by power supply from radio waves 3005 can be charged into a thin-film secondary battery 3001 included in the power storage device. An antenna and an IC 3004, and a thin-film secondary battery 3001 are arranged inside the IC card 3000. An ID 3002 and a photo 3003 of a worker who wears the management badge are displayed on the IC card 3000. A signal such as an authentication signal can also be transmitted from the antenna using the power charged in the thin-film secondary battery 3001.

[0305] The power storage device of one embodiment of the present invention may include a display device for displaying the ID 3002 and the photograph 3003. The display device includes, for example, a display unit and a driver circuit that applies an image signal to the display unit. The driver circuit can include, for example, a plurality of OS transistors described in the above embodiment. In the power storage device of one embodiment of the present invention, a secondary battery and an OS transistor can be provided over the same substrate. Thus, by providing the driver circuit using an OS transistor, the secondary battery and the driver circuit, or at least a part of the driver circuit, can be provided over the same substrate. Thus, it is possible to reduce the thickness, weight, and durability of an IC card.

[0306] As the display device, for example, an active matrix display device may be provided. Examples of active matrix display devices include reflective liquid crystal display devices, organic EL display devices, 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.

[0307] Since a plastic substrate is used in an IC card, an organic EL display device using a flexible substrate is preferable.

[0308] A solar cell may be provided in place of the photograph 3003. When exposed to external light, the light is absorbed, electricity is generated, and the thin-film secondary battery 3001 can be charged with the electricity.

[0309] Furthermore, the thin-film secondary battery is not limited to use in IC cards, but can also be used as a power source for wireless sensors mounted on vehicles, as a secondary battery for MEMS devices, and the like.

[0310] FIG. 17A shows an example of a wearable device. The wearable device uses a secondary battery as a power source. In addition, when a user uses the device in daily life or outdoors, in order to improve splash-proof performance, water resistance, or dust resistance, a wearable device that can be charged wirelessly as well as by wire with an exposed connector is desired.

[0311] For example, the power storage device of one embodiment of the present invention can be mounted on a glasses-type device 400 as shown in FIG. 17A. The glasses-type device 400 has a frame 400a and a display unit 400b. By mounting a power storage device having a secondary battery on temples of the curved frame 400a, the glasses-type device 400 can be lightweight, well-balanced in weight, and has a long continuous use time. By providing the secondary battery of one embodiment of the present invention, a configuration that can accommodate space saving associated with a smaller housing can be realized.

[0312] Furthermore, the secondary battery according to one embodiment of the present invention can be mounted on the headset type device 401. The headset type device 401 has at least a microphone unit 401a, a flexible pipe 401b, and an earphone unit 401c. The secondary battery can be provided in the flexible pipe 401b or the earphone unit 401c. By providing the secondary battery according to one embodiment of the present invention, a configuration that can accommodate space saving associated with a miniaturized housing can be realized.

[0313] 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 power storage device 402b including a secondary battery 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 structure that can accommodate space saving associated with a miniaturized housing can be realized.

[0314] Furthermore, the power storage device according to one embodiment of the present invention can be mounted on a device 403 that can be attached to clothing. A power storage device 403b including a secondary battery 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 structure that can save space due to the miniaturization of the housing can be realized.

[0315] Furthermore, the power storage device 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 a power storage device having a secondary battery can be mounted inside the belt portion 406a. By providing the power storage device of one embodiment of the present invention, a configuration that can accommodate space saving associated with miniaturization of the housing can be realized.

[0316] Furthermore, the power storage device 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 power storage device can be provided on the display portion 405a or the belt portion 405b. By providing the power storage device of one embodiment of the present invention, a configuration that can accommodate space saving due to miniaturization of the housing can be realized.

[0317] Display unit 405a can display not only the time, but also various other information such as incoming e-mails and phone calls.

[0318] In addition, since the wristwatch type device 405 is a wearable device that is directly wrapped around the arm, it may be equipped with sensors that measure the user's pulse, blood pressure, etc. Data on the user's amount of exercise and health can be accumulated to manage the user's health.

[0319] FIG. 17B shows a perspective view of the wristwatch type device 405 removed from the wrist.

[0320] A side view is shown in Fig. 17C. Fig. 17C shows a state in which a power storage device 913 having a secondary battery is built in. The power storage device 913 is provided at a position overlapping with the display portion 405a, and is small and lightweight.

[0321] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0322] (Embodiment 8) In this embodiment, electronic devices using a power storage device of one embodiment of the present invention will be described with reference to Fig. 18A, Fig. 18B, and Fig. 19A to Fig. 19D. In the power storage device of one embodiment of the present invention, a secondary battery and a battery control circuit can be provided over the same substrate, which makes it possible to miniaturize the electronic device and improve the safety of the secondary battery. In addition, the power storage device of one embodiment of the present invention has a characteristic of being thin because it can be provided over a substrate.

[0323] 18A shows a perspective view of a wristwatch-type mobile information terminal (also called a smart watch (registered trademark)) 700. The mobile information terminal 700 has a housing 701, a display panel 702, a clasp 703, bands 705A and 705B, and operation buttons 711 and 712.

[0324] For example, an active matrix display device may be provided as the display panel. Examples of active matrix display devices include reflective liquid crystal display devices, organic EL display devices, and electronic paper. Images (moving or still images) and time can also be displayed on the active matrix display device. Power for the active matrix display device can be supplied from a thin-film secondary battery. Also, an organic EL display device using a flexible substrate may be used.

[0325] The display device includes a display panel and a driver circuit that supplies an image signal to the display panel. The driver circuit can include, for example, a plurality of OS transistors as described in the above embodiment. In a power storage device according to one embodiment of the present invention, a secondary battery and an OS transistor can be provided over the same substrate. Thus, by providing the driver circuit using an OS transistor, the secondary battery and the driver circuit, or at least a part of the driver circuit, can be provided over the same substrate. Thus, the portable information terminal according to one embodiment of the present invention can be made smaller, lighter, and more durable.

[0326] A display panel 702 mounted on a housing 701 that also serves as a bezel has a rectangular display area. The display area has a curved surface. The display panel 702 is preferably flexible. The display area may be non-rectangular.

[0327] Band 705A and band 705B are connected to housing 701. Clasp 703 is connected to band 705A. Band 705A and housing 701 are connected, for example, via a pin so that the connection can rotate. The same applies to the connections between band 705B and housing 701, and between band 705A and clasp 703.

[0328] FIG. 18B shows a perspective view of the band 705A. The band 705A has a power storage device. For example, the power storage device described in the previous embodiment can be used for the power storage device. The power storage device is embedded inside the band 705A, and a positive electrode lead 751 and a negative electrode lead 752 of a secondary battery of the power storage device each partially protrude from the band 705A (see FIG. 18B). The positive electrode lead 751 and the negative electrode lead 752 are electrically connected to the display panel 702. Note that the above pins may have an electrode function. Specifically, the positive electrode lead 751 and the display panel 702, and the negative electrode lead 752 and the display panel 702 may each be electrically connected via a pin that connects the band 705A to the housing 701. In this way, the configuration at the connection portion between the band 705A and the housing 701 can be simplified.

[0329] The power storage device is flexible. Therefore, the band 705A can be manufactured by integrally forming it with the power storage device. For example, the power storage device is set in a mold that corresponds to the outer shape of the band 705A, and the material of the band 705A is poured into the mold and hardened, thereby manufacturing the band 705A shown in FIG. 18B.

[0330] When a rubber material is used as the material of the band 705A, the rubber is hardened by heat treatment. For example, when fluororubber is used as the rubber material, it is hardened by heat treatment at 170°C for 10 minutes. When silicone rubber is used as the rubber material, it is hardened by heat treatment at 150°C for 10 minutes.

[0331] Materials used for the band 705A include fluororubber, silicone rubber, fluorosilicone rubber, and urethane rubber.

[0332] 18A can have various functions. For example, it can have a function of displaying various information (still images, videos, text images, etc.) in a display area, a touch panel function, a function of displaying a calendar, date or time, etc., a function of controlling processing by various software (programs), a wireless communication function, a function of connecting to various computer networks using the wireless communication function, a function of transmitting or receiving various data using the wireless communication function, a function of reading out a program or data recorded in a recording medium and displaying it in a display area, etc.

[0333] The housing 701 may also have a speaker, a sensor (including a function of measuring force, displacement, position, speed, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared ray), a microphone, or the like inside the housing 701. The portable information terminal 700 can be manufactured by using a light-emitting element for the display panel 702.

[0334] 18A shows an example in which the power storage device is included in the band 705A, the power storage device may be included in the band 705B. The band 705B can be formed using the same material as the band 705A.

[0335] 19A shows an example of a cleaning robot. The cleaning robot 6300 has a display unit 6302 arranged on the top surface of a housing 6301, a plurality of cameras 6303 arranged on the side surface, a brush 6304, an operation button 6305, various sensors, and the like. Although not shown, the cleaning robot 6300 is provided with tires, a suction port, and the like. The cleaning robot 6300 can move by itself, detect dust 6310, and suck up the dust from a suction port provided on the bottom surface.

[0336] For example, the cleaning robot 6300 can analyze an image captured by the camera 6303 and determine the presence or absence of an obstacle such as a wall, furniture, or a step. When an object that may become entangled in the brush 6304, such as a wire, is detected by image analysis, the rotation of the brush 6304 can be stopped. The cleaning robot 6300 includes a power storage device according to one embodiment of the present invention and a semiconductor device or electronic component therein. By using the power storage device according to one embodiment of the present invention in the cleaning robot 6300, the cleaning robot 6300 can be an electronic device with long operating time and high reliability.

[0337] Fig. 19B shows an example of a robot. The robot 6400 shown in Fig. 19B includes a power storage device 6409, an illuminance sensor 6401, a microphone 6402, an upper camera 6403, a speaker 6404, a display unit 6405, a lower camera 6406, an obstacle sensor 6407, a moving mechanism 6408, a computing device, and the like.

[0338] The microphone 6402 has a function of detecting the user's voice, environmental sounds, etc. The speaker 6404 has a function of emitting sound. The robot 6400 can communicate with the user using the microphone 6402 and the speaker 6404.

[0339] The display unit 6405 has a function of displaying various information. The robot 6400 can display information desired by the user on the display unit 6405. The display unit 6405 may be equipped with a touch panel. The display unit 6405 may also be a removable information terminal, and by installing it in a fixed position on the robot 6400, charging and data transfer are possible.

[0340] The upper camera 6403 and the lower camera 6406 have a function of capturing images of the surroundings of the robot 6400. In addition, the obstacle sensor 6407 can detect the presence or absence of an obstacle in the moving direction when the robot 6400 moves forward using the moving mechanism 6408. The robot 6400 can recognize the surrounding environment and move safely using the upper camera 6403, the lower camera 6406, and the obstacle sensor 6407.

[0341] The robot 6400 includes a power storage device 6409 according to one embodiment of the present invention and electronic components inside the robot 6400. By using the power storage device according to one embodiment of the present invention in the robot 6400, the robot 6400 can be a highly reliable electronic device with a long operating time.

[0342] Fig. 19C shows an example of an aircraft. An aircraft 6500 shown in Fig. 19C has a propeller 6501, a camera 6502, a power storage device 6503, and the like, and has a function of flying autonomously.

[0343] For example, image data captured by the camera 6502 is stored in the electronic component 6504. The electronic component 6504 can analyze the image data and detect the presence or absence of an obstacle when moving. The power storage device 6503 can estimate the remaining amount from a change in the power storage capacity of the secondary battery. The flying object 6500 includes the power storage device 6503 according to one embodiment of the present invention therein. By using the power storage device according to one embodiment of the present invention for the flying object 6500, the flying object 6500 can be an electronic device with long operating time and high reliability.

[0344] 19D illustrates an example of an automobile. The automobile 7160 includes a power storage device 7161, an engine, tires, brakes, a steering device, a camera, and the like. The automobile 7160 includes a power storage device 7161 according to one embodiment of the present invention inside. By using a power storage device according to one embodiment of the present invention in the automobile 7160, the weight of the vehicle can be reduced. Furthermore, the volume of the secondary battery in the vehicle can be reduced. Furthermore, the automobile 7160 can be a vehicle with a long cruising distance, high safety, and high reliability.

[0345] This embodiment mode can be implemented in appropriate combination with other embodiment modes. [Explanation of symbols]

[0346] 11: transistor, 12: transistor, 13: transistor, 14: transistor, 15: transistor, 21: transistor, 22: transistor, 23: transistor, 24: transistor, 25: transistor, 50: comparator, 90: power storage device, 91: battery control circuit, 91a: circuit, 91b: circuit, 99: holding circuit, 99a: transistor, 99b: transistor, 100: positive electrode, 101: positive electrode active material layer, 103: positive electrode current collector, 110: substrate, 113: comparator, 114: memory element, 120: battery pack, 121: battery cell, 130: Cell balance circuit, 130a: cell balance circuit, 131: resistive element, 132: transistor, 140: transistor, 150: transistor, 161: capacitive element, 162: transistor, 172: transistor, 182: logic circuit, 185: detection circuit, 185a: detection circuit, 185c: circuit, 185d: circuit, 186: detection circuit, 200: secondary battery, 203: solid electrolyte layer, 204: negative electrode active material layer, 205: negative electrode current collector, 206: protective layer, 210: negative electrode, 213: solid electrolyte layer, 215: positive electrode current collector, 300: transistor, 313: semiconductor region, 31 4a: low resistance region, 314b: low resistance region, 315: insulator, 316: conductor, 320: insulator, 322: insulator, 324: insulator, 326: insulator, 328: conductor, 330: conductor, 350: insulator, 400: glasses-type device, 400a: frame, 400b: display unit, 401: headset-type device, 401a: microphone unit, 401b: flexible pipe, 401c: earphone unit, 402: device, 402a: housing, 402b: power storage device, 403: device, 403a: housing, 403b: power storage device, 405: wristwatch-type device, 405a: Display unit, 405b: belt unit, 406: belt type device, 406a: belt unit, 406b: wireless power receiving unit, 500: transistor, 503: conductor, 512: insulator, 514: insulator, 520: insulator, 522: insulator, 524: insulator, 530: oxide, 530a: oxide, 530b: oxide, 530c: oxide, 540a: conductor, 540b: conductor, 542a: conductor, 542b: conductor, 543a: region, 543b: region, 544: insulator, 550: insulator, 560: conductor, 560a: conductor, 560b: conductor, 574: insulator,580: insulator, 580b: insulator, 581: insulator, 599: substrate, 600: capacitance element, 610: conductor, 610b: conductor, 611: insulator, 660: sensor element, 660a: conductor, 660b: layer, 660c: conductor, 700: portable information terminal, 701: housing, 702: display panel, 703: clasp, 705A: band, 705B: band, 711: operation button, 712: operation button, 751: positive electrode lead, 752: negative electrode lead, 913: power storage device, 3000: IC card, 3001: thin-film secondary battery, 3002: ID, 3003: photo, 3004: I C, 3005: radio waves, 6300: cleaning robot, 6301: housing, 6302: display unit, 6303: camera, 6304: brush, 6305: operation button, 6310: dust, 6400: robot, 6401: illuminance sensor, 6402: microphone, 6403: upper camera, 6404: speaker, 6405: display unit, 6406: lower camera, 6407: obstacle sensor, 6408: moving mechanism, 6409: power storage device, 6500: flying object, 6501: propeller, 6502: camera, 6503: power storage device, 6504: electronic parts, 7160: automobile, 7161: power storage device,

Claims

1. a first battery cell, a comparison circuit, a control circuit, a first transistor, and a capacitance element; the comparison circuit has a first input terminal, a second input terminal, an output terminal, and a second transistor; one of a source and a drain of the first transistor is electrically connected to the second input terminal; the other of the source and the drain of the first transistor is electrically connected to one electrode of the capacitance element; the first transistor has an oxide semiconductor in a channel formation region; the second transistor has an oxide semiconductor in a channel formation region; a first electrode of the first battery cell electrically connected to a gate electrode of the second transistor and the first input terminal; the comparison circuit has a function of outputting a first signal corresponding to a comparison result between the potential of the first electrode and a desired reference potential from the output terminal to the control circuit; The control circuit is a power storage device having a function of controlling charging of the first battery cell in response to the first signal.

2. In claim 1, The output terminal of the power storage device is electrically connected to the source or drain of the second transistor.

3. In claim 1, a third transistor; the third transistor has an oxide semiconductor in a channel formation region; The output terminal of the power storage device is electrically connected to the source or drain of the third transistor.

Images