Power storage system

Abstract

To provide a power storage system, a control system of a secondary battery, a measurement circuit of the secondary battery, and the like, which consume less power, and further provide a power storage system, a control system of the secondary battery and a measurement circuit of the secondary battery which are highly integrated.SOLUTION: The power storage system comprises a secondary battery and a measurement circuit. The measurement circuit comprises a resistive element, a capacitive element and an inductor. One terminal of the resistive element is electrically connected to one electrode of the capacitive element. The other terminal of the resistive element is electrically connected to one terminal of the inductor. One terminal of the inductor is electrically connected to a positive electrode of the secondary battery. The measurement circuit has a function of measuring impedance of the secondary battery by measuring current of the resistive element.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] One embodiment of the present invention relates to a measurement circuit, a control system, and a power storage system. Another embodiment of the present invention relates to a battery control circuit, a battery protection circuit, a power storage device, and an electric device. Another embodiment of the present invention relates to a secondary battery. Another embodiment of the present invention relates to a semiconductor device and an operation method of the semiconductor device.

[0002] Note that one embodiment of the present invention is not limited to the above-mentioned technical field. The technical field of the invention disclosed in this specification relates to an object or a 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 memory device, a driving method thereof, or a manufacturing method thereof. [Background technology]

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

[0004] Energy storage devices are equipped with circuits to detect abnormalities during charging and discharging, such as over-discharge, over-charge, over-current, or short circuits. In this way, the circuits that protect and control the battery acquire data such as voltage and current to detect abnormalities during charging and discharging. Furthermore, these circuits use the observed data to stop charging and discharging, perform cell balancing, and other controls.

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

[0006] Furthermore, Patent Document 2 discloses a battery state detection device that detects minute short circuits in a secondary battery, and a battery pack incorporating the same.

[0007] Patent Document 3 discloses a protective semiconductor device that protects a battery pack in which secondary battery cells are connected in series. Patent Document 4 discloses a device that detects the internal resistance value of a secondary battery.

[0008] Furthermore, Patent Document 5 describes a power MOSFET used in a semiconductor device that controls a battery. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] U.S. Patent Application Publication No. 2011-267726 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-66161 [Patent Document 3] Japanese Patent Application Laid-Open No. 2010-220389 [Patent Document 4] Japanese Patent Application Laid-Open No. 2008-175556 [Patent Document 5] International Publication No. 2017 / 094185 Summary of the Invention [Problem to be solved by the invention]

[0010] An object of one embodiment of the present invention is to provide a novel power storage system, a control system for a secondary battery, a measurement circuit for a secondary battery, or the like.Another object of one embodiment of the present invention is to provide a power storage system, a control system for a secondary battery, a measurement circuit for a secondary battery, or the like with low power consumption.Another object of one embodiment of the present invention is to provide a power storage system, a control system for a secondary battery, a measurement circuit for a secondary battery, or the like with high integration.

[0011] Another object of one embodiment of the present invention is to provide a novel system, a measurement circuit, a battery control circuit, a battery protection circuit, a power storage device, a semiconductor device, a vehicle, an electronic device, or the like.

[0012] 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 problems. One embodiment of the present invention solves at least one of the problems listed above and other problems. [Means for solving the problem]

[0013] One embodiment of the present invention is a power storage system that includes a secondary battery and a measurement circuit, the measurement circuit including a resistor, a capacitor, and an inductor, one terminal of the resistor electrically connected to one electrode of the capacitor, the other terminal of the resistor electrically connected to one terminal of the inductor, and one terminal of the inductor electrically connected to one of the positive and negative electrodes of the secondary battery, and the measurement circuit has the function of measuring the impedance of the secondary battery by measuring the current of the resistor.

[0014] Alternatively, one embodiment of the present invention is a power storage system that includes a secondary battery and a measurement circuit, the measurement circuit including a resistor, a capacitor, and an inductor, one terminal of the resistor being electrically connected to one electrode of the capacitor, the other terminal of the resistor being electrically connected to one terminal of the inductor, and the one terminal of the inductor being electrically connected to a positive electrode of the secondary battery, and the measurement circuit having a function of measuring the impedance of the secondary battery by measuring the current of the resistor.

[0015] Alternatively, one embodiment of the present invention is a power storage system that includes a secondary battery and a measurement circuit, the measurement circuit including a resistor, a capacitor, and an inductor, one terminal of the resistor being electrically connected to one electrode of the capacitor, the other electrode of the capacitor being electrically connected to one terminal of the inductor, and the one terminal of the inductor being electrically connected to one of the positive and negative electrodes of the secondary battery, and the measurement circuit having a function of measuring the impedance of the secondary battery by measuring the current of the resistor.

[0016] Alternatively, one embodiment of the present invention is a power storage system that includes a secondary battery and a measurement circuit, the measurement circuit including a resistor, a capacitor, and an inductor, one terminal of the resistor being electrically connected to one electrode of the capacitor, the other electrode of the capacitor being electrically connected to one terminal of the inductor, and the one terminal of the inductor being electrically connected to a positive electrode of the secondary battery, and the measurement circuit having a function of measuring the impedance of the secondary battery by measuring the current of the resistor.

[0017] In the above configuration, it is preferable that the impedance be measured while a charging current or a discharging current is being supplied to the secondary battery.

[0018] In the above configuration, it is preferable that the other terminal of the inductor is electrically connected to a first circuit, and that the first circuit has a function of controlling charging of the secondary battery.

[0019] In the above configuration, it is preferable that the charging current for the secondary battery is supplied to the secondary battery from the first circuit via an inductor.

[0020] Furthermore, in the above configuration, it is preferable that the measurement circuit has a function of applying a voltage having an AC component to the secondary battery, and that the measurement circuit has a function of sweeping the frequency of the AC component and a function of estimating the state of the secondary battery based on the correlation between the frequency and the current value of the resistance element.

[0021] In the above configuration, it is preferable to have a function of determining the charging conditions for the secondary battery based on the estimated state.

[0022] Alternatively, one embodiment of the present invention is a power storage system including a secondary battery and a measurement circuit, wherein the measurement circuit includes a resistor, a capacitor, an inductor, and an AC signal source, one terminal of the resistor is electrically connected to one electrode of the capacitor, the other terminal of the resistor is electrically connected to one terminal of the inductor, the one terminal of the inductor is electrically connected to one of the positive and negative electrodes of the secondary battery, and the AC signal source is electrically connected to the other electrode of the capacitor and the other of the positive and negative electrodes of the secondary battery.

[0023] Alternatively, one embodiment of the present invention is a power storage system including a secondary battery and a measurement circuit, the measurement circuit including a resistor, a capacitor, an inductor, and an AC signal source, one terminal of the resistor being electrically connected to one electrode of the capacitor, the other terminal of the resistor being electrically connected to one terminal of the inductor, the one terminal of the inductor being electrically connected to a positive electrode of the secondary battery, and the AC signal source being electrically connected to the other electrode of the capacitor and a negative electrode of the secondary battery.

[0024] Alternatively, one embodiment of the present invention is a power storage system including a secondary battery and a measurement circuit, wherein the measurement circuit includes a resistor, a capacitor, an inductor, and an AC signal source, one terminal of the resistor is electrically connected to one electrode of the capacitor, the other electrode of the capacitor is electrically connected to one terminal of the inductor, the one terminal of the inductor is electrically connected to one of the positive and negative electrodes of the secondary battery, and the AC signal source is electrically connected to the other terminal of the resistor and the other of the positive and negative electrodes of the secondary battery.

[0025] Alternatively, one embodiment of the present invention is a power storage system including a secondary battery and a measurement circuit, the measurement circuit including a resistor, a capacitor, an inductor, and an AC signal source, one terminal of the resistor being electrically connected to one electrode of the capacitor, the other electrode of the capacitor being electrically connected to one terminal of the inductor, the one terminal of the inductor being electrically connected to a positive electrode of the secondary battery, and the AC signal source being electrically connected to the other terminal of the resistor and a negative electrode of the secondary battery.

[0026] In the above configuration, it is preferable that the frequency of the signal output from the AC signal source be swept and a correlation between the current value of the resistance element and the frequency be obtained.

[0027] In addition, in the above configuration, it is preferable that the device has a function of estimating the state of the secondary battery based on the correlation between the current value of the resistance element and the frequency, and a function of determining the charging conditions of the secondary battery based on the estimated state.

[0028] In the above configuration, the current value of the resistance element is preferably measured while a charging current or a discharging current is being supplied to the secondary battery.

[0029] The power storage system of one embodiment of the present invention preferably includes a temperature sensor.

[0030] Another embodiment of the present invention is a vehicle including any one of the above power storage systems.

[0031] Another embodiment of the present invention is an electronic device including any one of the above power storage systems. [Effects of the Invention]

[0032] According to one embodiment of the present invention, a novel power storage system, a control system for a secondary battery, a measurement circuit for a secondary battery, or the like can be provided. Alternatively, according to one embodiment of the present invention, a power storage system, a control system for a secondary battery, a measurement circuit for a secondary battery, or the like with low power consumption can be provided. Alternatively, according to one embodiment of the present invention, a power storage system, a control system for a secondary battery, a measurement circuit for a secondary battery, or the like with high integration can be provided.

[0033] According to one embodiment of the present invention, a novel system, a measurement circuit, a battery control circuit, a battery protection circuit, a power storage device, a semiconductor device, a vehicle, an electronic device, or the like can be provided.

[0034] 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. 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 extracted as appropriate from these descriptions. One embodiment of the present invention has at least one of the effects listed above and other effects. Therefore, one embodiment of the present invention may not have the effects listed above in some cases. [Brief explanation of the drawings]

[0035] [Figure 1] 1A to 1D are circuit diagrams illustrating a power storage system according to one embodiment of the present invention, and FIG. 1E is a circuit diagram illustrating an example of a secondary battery. [Figure 2] 2A and 2B are circuit diagrams illustrating a power storage system of one embodiment of the present invention. [Figure 3] 3A to 3C are circuit diagrams illustrating a power storage system of one embodiment of the present invention. [Figure 4]4A and 4B are circuit diagrams illustrating a power storage system of one embodiment of the present invention. [Figure 5] 5A and 5B are diagrams showing examples of the configuration of a neural network, Fig. 5C is a diagram showing an example of the configuration of a control system having a switch unit, and Fig. 5D is a diagram showing an example of the configuration of the switch unit. [Figure 6] FIG. 6 is a diagram illustrating the crystal structure of the positive electrode active material. [Figure 7] FIG. 7 is a diagram illustrating the crystal structure of the positive electrode active material. [Figure 8] 8A and 8B are examples of cross-sectional views of a secondary battery. [Figure 9] 9A and 9B are diagrams showing an example of the external appearance of a secondary battery. [Figure 10] 10A and 10B are diagrams illustrating a method for manufacturing a secondary battery. [Figure 11] 11A and 11B are diagrams illustrating a method for producing a secondary battery. [Figure 12] 12A and 12B are diagrams illustrating an example of a secondary battery, and FIGS. 12C and 12D are diagrams illustrating an example of a power storage system. [Figure 13] 13A to 13C are diagrams showing an example of a battery pack. [Figure 14] FIG. 14 is a cross-sectional view showing an example of a secondary battery. [Figure 15] Fig. 15A is a diagram showing an example of a secondary battery, and Fig. 15B and Fig. 15C are diagrams showing an example of a method for producing a laminate. [Figure 16] 16A to 16C are diagrams showing an example of a method for manufacturing a secondary battery. [Figure 17] 17A and 17B are cross-sectional views showing an example of a laminate, and Fig. 17C is a cross-sectional view showing an example of a secondary battery. [Figure 18] 18A and 18B are diagrams showing an example of a secondary battery, and Fig. 18C is a diagram showing an example of a wound body. [Figure 19]Fig. 19A is a diagram showing an example of a wound body of a secondary battery, Fig. 19B is a diagram showing an example of the configuration of a secondary battery, and Fig. 19C is a diagram showing an example of a secondary battery. [Figure 20] Fig. 20A is a perspective view showing an example of a battery pack, Fig. 20B is a block diagram showing an example of a battery pack, and Fig. 20C is a block diagram showing an example of a vehicle having a motor. [Figure 21] 21A to 21E are diagrams showing an example of a transportation vehicle. [Figure 22] FIG. 22A is a diagram showing an electric bicycle, FIG. 22B is a diagram showing a secondary battery of the electric bicycle, and FIG. 22C is a diagram explaining an electric motorcycle. [Figure 23] 23A and 23B are diagrams illustrating an example of a power storage device. [Figure 24] 24A to 24E are diagrams showing an example of an electronic device. [Figure 25] 25A to 25H are diagrams illustrating an example of an electronic device. [Figure 26] 26A to 26C are diagrams illustrating an example of an electronic device. [Figure 27] FIG. 27 is a diagram illustrating an example of an electronic device. [Figure 28] 28A to 28C are diagrams illustrating an example of an electronic device. [Figure 29] 29A to 29C are diagrams showing an example of an electronic device. DETAILED DESCRIPTION OF THE INVENTION

[0036] Hereinafter, embodiments will be described with reference to the drawings. However, it will be readily understood by those skilled in the art that the embodiments can be implemented in many different ways and that various changes in form and details can be made without departing from the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the following description of the embodiments.

[0037] In this specification, the ordinal numbers "first," "second," and "third" are used to avoid confusion between 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.

[0038] 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 explanations thereof may be omitted.

[0039] Furthermore, 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.

[0040] In addition, in top views (also called "plan views") and perspective views, some components may be omitted to make the drawings easier to understand.

[0041] Furthermore, the terms "electrode" and "wiring" used in this specification and elsewhere do not limit the functionality of these components. For example, they may be used as part of an "electrode" and a "wiring," and vice versa. Furthermore, the terms "electrode" and "wiring" also include cases where multiple "electrodes" and multiple "wirings" are integrally formed.

[0042] Furthermore, in this specification and the like, a "terminal" may refer to, for example, a wiring or an electrode connected to a wiring. Furthermore, in this specification and the like, a part of a "wiring" may be called a "terminal."

[0043] In this specification, the terms "above" and "below" do not limit the positional relationship between components to directly above or below and in direct contact with each other. 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.

[0044] In addition, the functions of the source and drain are interchangeable depending on operating conditions, such as when transistors of different polarities are used or when the direction of current flow changes during circuit operation, making it difficult to define which is the source and which is the drain. For this reason, the terms source and drain can be used interchangeably in this specification.

[0045] Furthermore, in this specification, "electrically connected" includes both direct connection and connection via "something that has some kind of electrical effect." Here, "something that has some kind of electrical effect" is not particularly limited as long as it allows electrical signals to be transmitted and received between the connected objects. Therefore, even when the expression "electrically connected" is used, in an actual circuit, there may be no physical connection and only wiring may be extended.

[0046] Furthermore, in this specification and elsewhere, "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 cases in which the angle is -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 cases in which the angle is 85° or more and 95° or less.

[0047] In this specification and elsewhere, when referring to counting values ​​and measurement values, terms such as "same," "equal," or "uniform" are used, they are considered to include an error of plus or minus 20%, unless otherwise specified.

[0048] In addition, in this specification, when etching is performed after forming a resist mask, the resist mask is removed after the etching is completed, unless otherwise specified.

[0049] 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 can often be used interchangeably.

[0050] It should be noted that even when written as "semiconductor," if the conductivity is sufficiently low, it will have the properties of an "insulator." Therefore, it is also possible to use "semiconductor" instead of "insulator." In this case, the boundary between "semiconductor" and "insulator" is vague, and it is difficult to strictly distinguish between the two. Therefore, "semiconductor" and "insulator" described in this specification may be read interchangeably.

[0051] Furthermore, even when written as "semiconductor," if the conductivity is sufficiently high, it will have the properties of a "conductor." Therefore, it is also possible to use "semiconductor" instead of "conductor." In this case, the boundary between "semiconductor" and "conductor" is vague, and it is difficult to strictly distinguish between the two. Therefore, "semiconductor" and "conductor" described in this specification may be read interchangeably.

[0052] In this specification and the like, the "on state" of a transistor refers to a state in which the source and drain of the transistor are considered to be 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 are considered to be electrically disconnected (also referred to as a "non-conductive state").

[0053] In this specification, the term "on-state current" may refer to a current that flows between the source and drain of a transistor when the transistor is on, and the term "off-state current" may refer to a current that flows between the source and drain of a transistor when the transistor is off.

[0054] In this specification, the 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. The 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. The ground potential can also 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.

[0055] In this specification and the like, a gate refers to a gate electrode and a part or all of a gate wiring, and a gate wiring refers to a wiring for electrically connecting the gate electrode of at least one transistor to another electrode or another wiring.

[0056] In this specification, the term "source" refers to a source region, a source electrode, and part or all of a source wiring. The term "source region" refers to a region of a semiconductor layer whose resistivity is equal to or less than a certain value. The term "source electrode" refers to a conductive layer connected to the source region. The term "source wiring" refers to wiring that electrically connects the source electrode of at least one transistor to another electrode or wiring.

[0057] In this specification, the term "drain" refers to a part or all of the drain region, drain electrode, and drain wiring. The term "drain region" refers to a region of the semiconductor layer whose resistivity is equal to or less than a certain value. The term "drain electrode" refers to a conductive layer connected to the drain region. The term "drain wiring" refers to wiring that electrically connects the drain electrode of at least one transistor to another electrode or another wiring.

[0058] (Embodiment 1) In this embodiment, a measurement circuit, a control system, and a power storage system according to one embodiment of the present invention will be described.

[0059] FIG. 1A illustrates an example of a power storage system using a measurement circuit of one embodiment of the present invention.

[0060] 1A includes a measurement circuit 750 and a secondary battery 120 electrically connected to the measurement circuit 750. Also in FIG. 1A, the measurement circuit 750 is electrically connected to a terminal 771 and a terminal 772. Also in FIG. 1A, the secondary battery 120 is electrically connected to a voltmeter 782. The voltmeter 782 is connected in parallel to the secondary battery 120 and has a function of measuring the voltage of the secondary battery 120.

[0061] Various power storage devices can be used as the secondary battery 120. For example, a lithium ion secondary battery can be used as the secondary battery 120.

[0062] 1E, a battery pack in which a plurality of battery cells 121 are connected in series can be used as the secondary battery 120. A plurality of battery cells connected in series can be used as a single battery pack, and a measurement circuit 750 can be connected to both ends of the battery pack and measured by the measurement circuit 750. Note that measurement may also be performed by connecting the measurement circuit 750 to both ends of each of a plurality of battery cells 121 connected in series. Various power storage devices can be used as the battery cells 121. For example, a lithium ion secondary battery can be used as the battery cells 121.

[0063] The measurement circuit 750 can measure parameters for estimating the state of the secondary battery 120. For example, the measurement circuit 750 can acquire the frequency characteristics of the secondary battery 120. Furthermore, for example, the measurement circuit 750 can measure the impedance of the secondary battery 120.

[0064] The measurement circuit 750 preferably applies an AC signal to the secondary battery 120 and obtains the relationship between the frequency of the AC signal and the current flowing through the secondary battery 120. In addition, the measurement circuit 750 preferably extracts and obtains components in a specific frequency range from the current flowing through the secondary battery 120.

[0065] The measurement circuit 750 includes an AC signal source, a capacitance element (capacitor), a resistance element, etc. The measurement circuit 750 shown in FIG. 1A includes an AC signal source 751, a capacitance element 752, a resistance element 753, an inductor 754, and a voltmeter 781. In FIG. 1A, the negative electrode of the secondary battery 120 is electrically connected to a terminal 772 and one terminal of the AC signal source 751. The other terminal of the AC signal source 751 is electrically connected to one terminal of the capacitance element 752. The other terminal of the capacitance element 752 is electrically connected to one terminal of the resistance element 753. The other terminal of the resistance element 753 is electrically connected to the positive electrode of the secondary battery 120 and one terminal of the inductor 754. The other terminal of the inductor 754 is electrically connected to the terminal 771.

[0066] Measurement circuit 750 has a function of changing the frequency of the AC signal output from AC signal source 751 and analyzing the frequency dependency of the current flowing through resistive element 753. The current flowing through resistive element 753 can be obtained, for example, from the voltage of voltmeter 781 connected in parallel to resistive element 753.

[0067] The measurement circuit 750 has a function of providing a signal having an AC component to the secondary battery 120. For example, the measurement circuit 750 has a function of superimposing a small-amplitude AC voltage signal on the voltage of the secondary battery. The measurement circuit 750 can output a first AC voltage signal from an AC signal source 751. The measurement circuit 750 can superimpose a second AC voltage signal, which is a small-amplitude AC voltage signal with a variable frequency, on the voltage of the secondary battery by changing the frequency of the first AC voltage signal. The frequency of the second AC voltage signal corresponds to the frequency of the first AC voltage signal, for example. The second AC signal superimposed on the secondary battery preferably has a frequency of 0.01 Hz to 1 MHz. For example, two or more frequencies may be selected from the range of 0.01 Hz to 1 MHz, and the current of the resistor element 753 may be calculated when AC signals having each selected frequency are superimposed on the voltage of the secondary battery. Furthermore, it is preferable that at least one of the frequencies of the superimposed AC signals be selected from the range of 0.01 Hz to 0.5 Hz.

[0068] The current flowing through the resistance element 753 changes depending on the internal impedance of the secondary battery 120. The measurement circuit 750 has a function of evaluating the internal impedance of the secondary battery 120 by measuring the current flowing through the resistance element 753.

[0069] The amplitude of the minute AC voltage signal that measurement circuit 750 superimposes on the voltage of the secondary battery is preferably, for example, 0.00025 to 0.0125 times the voltage across secondary battery 120. Furthermore, if secondary battery 120 is a single lithium-ion secondary battery, the amplitude of the AC signal is preferably, for example, 1 mV to 50 mV. While this depends on the type and structure of the battery, inputting a 10 mV AC voltage signal, for example, will result in an AC current of approximately 10 μA. This current value is preferable because it is measurable.

[0070] The terminal 771 is electrically connected to the positive electrode of the secondary battery 120 via the inductor 754. When the secondary battery 120 is composed of n battery cells 121, which are connected in series in order starting from the first battery cell 121, and the negative electrode of the first battery cell 121 is connected to the positive electrode of the second battery cell 121, the terminal 771 is electrically connected to the positive electrode of the first battery cell 121 via the inductor 754. An inductor may also be called a coil, a reactor, or the like.

[0071] Terminal 771 is electrically connected to a circuit, electronic device, mobile object, etc. to which the output from the secondary battery is applied. The discharge current of secondary battery 120 is output from terminal 771 via inductor 754. It is preferable to provide at least one of discharge protection circuit 703, selection circuit 704, output control circuit 705, and output protection circuit 706 (described later) between the object to which the output of the secondary battery is applied and terminal 771.

[0072] Furthermore, the charging current for the secondary battery is supplied to the secondary battery from the terminal 771 via the inductor 754 .

[0073] The terminal 772 is electrically connected to the negative electrode of the secondary battery. When the secondary battery 120 is composed of n battery cells 121, which are connected in series starting from the first battery cell 121, and the negative electrode of the first battery cell 121 is connected to the positive electrode of the second battery cell 121, the terminal 772 is electrically connected to the negative electrode of the n-th battery cell 121.

[0074] 1A, one electrode of inductor 754 is electrically connected to terminal 771, and the other electrode is electrically connected to the positive electrode of secondary battery 120. Terminal 772 is electrically connected to the negative electrode of secondary battery 120. The other electrode of inductor 754 and terminal 772 may each be connected to a potential obtained by resistively dividing the potential between the positive electrode and negative electrode of the secondary battery.

[0075] The capacitor 752 has a function of blocking a direct current supplied from the secondary battery 120 to the terminal 771 and a direct current supplied from the terminal 771 to the secondary battery so as not to flow to the resistor 753. The capacitor 752 also has a function of passing an alternating current.

[0076] In the measurement circuit 750, the inductor 754 can function as a low-pass filter that blocks high-frequency signals and passes low-frequency signals. By including the inductor 754 in the measurement circuit 750, for example, it is possible to prevent the AC signal output from the AC signal source 751 from being output from the terminal 771.

[0077] The measurement circuit of one embodiment of the present invention can acquire parameters for estimating the state of the secondary battery 120 without interfering with the discharge current supplied from the secondary battery 120 to the terminal 771 or with only a small effect on the discharge current. By using the measurement circuit of one embodiment of the present invention, parameters for estimating the state of the secondary battery 120 can be acquired while a discharge current is being supplied from the secondary battery 120 to the terminal 771. Furthermore, the measurement circuit of one embodiment of the present invention can acquire parameters for estimating the state of the secondary battery 120 while a charge current is being supplied from the terminal 771 to the secondary battery 120.

[0078] Parameters for estimating the state of the secondary battery 120 include temperature, battery voltage or state of charge (SOC), charging current, discharging current, etc. It is preferable to acquire these parameters in association with time. By acquiring these parameters in association with time, it is possible to compare them with values ​​from a certain time ago and estimate the state of the secondary battery 120. As a calculation method for the estimation, various machine learning techniques can be used, for example. For machine learning, a neural network can be used, for example.

[0079] In particular, the measurement circuit according to one embodiment of the present invention can obtain a value corresponding to the internal impedance of the secondary battery by acquiring current characteristics relative to an AC signal.

[0080] The voltmeter 781 is electrically connected to both ends of the resistive element 753, and has a function of measuring the voltage of the resistive element 753. By measuring the voltage of the resistive element 753, the current flowing through the resistive element 753 can be detected.

[0081] A voltage determined by the AC signal output from AC signal source 751, a voltage corresponding to the potential difference across capacitance element 752, and a voltage corresponding to the potential difference across resistance element 753 is applied across secondary battery 120. The amount of current flowing through secondary battery 120 corresponds to the amount of current flowing through resistance element 753 and the amount of current flowing through inductor 754.

[0082] The inductor 754 can limit an AC component of a signal. For example, the inductor 754 can limit an AC signal output from the AC signal source 751. Therefore, by providing the inductor 754, it is possible to prevent an AC signal or an AC component of the signal from flowing to a circuit connected to the terminal 771. Examples of the circuit connected to the terminal 771 include a charging circuit and a load. Here, examples of the load include an electronic device or a mobile object driven by power from the power storage system of one embodiment of the present invention. Therefore, the measuring instrument of one embodiment of the present invention can diagnose the secondary battery while being driven by power from the power storage system and charging the power storage system.

[0083] By connecting the capacitor 752 to the resistor 753 in series, the DC component of the current flowing through the resistor 753 can be limited. Therefore, by providing the capacitor 752, the measuring instrument of one embodiment of the present invention can reduce the influence of the DC current output from the secondary battery 120 and the DC current input from the charging circuit. Therefore, the measuring instrument of one embodiment of the present invention can diagnose the secondary battery while being driven by power from the power storage system and charging the power storage system.

[0084] In other words, it can be expressed that the measuring instrument of one embodiment of the present invention can perform measurement in real time while the power storage system is operating.

[0085] 1B includes two secondary batteries 120 (hereinafter referred to as secondary batteries 120(1) and 120(2)), two measurement circuits 750, and two voltmeters 782. The measurement circuit 750 provided between the secondary batteries 120(1) and 120(2) is referred to as measurement circuit 750(1), and the other is referred to as measurement circuit 750(2).

[0086] One terminal of the inductor 754 included in the measurement circuit 750(1) is electrically connected to the positive electrode of the secondary battery 120(1), and the other terminal is electrically connected to the positive electrode of the secondary battery 120(2). The inductor 754 included in the measurement circuit 750(1) can prevent the AC signal output from the AC signal source 751 included in the measurement circuit 750(1) from flowing to the secondary battery 120(2). Therefore, the measurement circuit 750(1) can diagnose the secondary battery 120(1) while reducing the influence from the secondary battery 120(2). Furthermore, the measurement circuit 750(2) can diagnose the secondary battery 120(2) while reducing the influence from the secondary battery 120(1).

[0087] In the power storage system 100 shown in FIG. 1B, the measurement circuit 750 can be used to diagnose each of the two secondary batteries 120 connected in parallel via the inductor of the measurement circuit 750.

[0088] The number of secondary batteries 120 connected in parallel is not limited to two, and as shown in FIG. 1C, n secondary batteries 120 may be connected in parallel via a measurement circuit 750, and each may be diagnosed.

[0089] Also, as shown in FIG. 1D, the number of voltmeters 782 having the function of measuring the voltage of the secondary battery 120 may be one, and the number of voltmeters 782 may not be the same as the number of secondary batteries 120 .

[0090] 2A, in the measurement circuit 750, the voltage of the secondary battery 120 measured by the voltmeter 782 may be measured via a capacitance element 786. In the configuration shown in Fig. 2A, the capacitance element 786 and the voltmeter 782 are connected in series between the positive electrode and the negative electrode of the secondary battery 120. One terminal of the capacitance element 786 is electrically connected to the positive electrode of the secondary battery 120, and the other terminal is electrically connected to the voltmeter 782.

[0091] As shown in FIG. 2B, a resistive element 753 may be provided between an AC signal source 751 and a capacitive element 752 to detect a current between the AC signal source and the capacitive element.

[0092] 2A shows an example in which the resistive element 753 is provided between the positive electrode of the secondary battery 120 and the capacitive element 752, but as shown in FIG. 3A, one terminal of the resistive element 753 may be electrically connected to the positive electrode of the secondary battery 120, and the other terminal may be electrically connected to one terminal of the inductor 754. With such a configuration, the resistive element 753 can also be used to measure the charging current and discharging current of the secondary battery 120. Meanwhile, the configurations shown in FIGS. 1A, 2A, and 2B each provide improved accuracy in diagnosing the state of the secondary battery compared to the configuration shown in FIG. 3A.

[0093] As shown in Fig. 3B, a configuration may be adopted in which a switch 755 is provided instead of inductor 754. Fig. 3B shows an example in which a transistor is provided as an example of the switch. In measurement circuit 750 shown in Fig. 3B, a portion configured by AC signal source 751, capacitance element 752, resistance element 753, and voltmeter 781 is referred to as circuit 750a. Measurement circuit 750 shown in Fig. 3B includes circuit 750a and switch 755.

[0094] The power storage system 100 shown in FIG. 3C has n measurement circuits 750 shown in FIG. 3B, each connected to n secondary batteries 120. If the switches 755 of all the measurement circuits 750 are simultaneously turned off, the supply of power from the power storage system 100 will be stopped. Therefore, it is preferable to turn on the switch 755 of at least one measurement circuit 750. Furthermore, as shown in FIG. 3C, by providing bypass wiring, power is supplied not from the secondary battery 120 connected to the measurement circuit 750 whose switch 755 is turned off, but from a secondary battery 120 connected to another measurement circuit 750 via the bypass, thereby preventing the current path between the terminal 771 and the positive electrode of the secondary battery 120 from being interrupted.

[0095] The power storage system 100 may be configured without the AC signal source 751. In such a configuration without the AC signal source 751, a switch or a circuit including a switch may be used instead of the AC signal source. A step function such as a square wave may be generated by turning the switch on and off, and the time change in current may be acquired to evaluate the step response characteristics. When a switch or a circuit including a switch is used instead of the AC signal source, a voltage drop due to the internal resistance of the secondary battery occurs when the switch is turned off during charging of the secondary battery. This voltage drop can be used as a step function signal for analysis. Alternatively, a step function signal may be generated using a signal source. A triangular wave, a sawtooth wave, or the like may be used as the step function. A transfer function can be calculated using the input voltage waveform and the output current waveform. The transfer function is calculated as a function of the complex number s. By substituting jω for the complex number s, the AC frequency characteristics can be obtained.

[0096] The signal used to charge the secondary battery may be an intermittent signal rather than a continuous signal. For example, a pulse signal may be used for charging. Alternatively, the pulse signal may be combined with a continuous constant current. When a pulse signal is used for charging, the inductor 754 may be omitted.

[0097] During charging, the internal impedance of the secondary battery can be measured by using a pulse signal and analyzing the current flowing through the secondary battery.

[0098] FIG. 4A illustrates a power storage system of one embodiment of the present invention.

[0099] The power storage system 100 shown in Fig. 4A includes a control system 700 and a secondary battery 120. The control system 700 includes a measurement circuit 750. The control system 700 is electrically connected to the secondary battery 120. The control system 700 may include a plurality of measurement circuits 750. Each of the plurality of measurement circuits 750 included in the control system 700 has a function of estimating the state of each of the plurality of secondary batteries 120, for example. Fig. 4B shows an example in which each of the plurality of measurement circuits 750 in the power storage system 100 is electrically connected to each of the plurality of secondary batteries 120.

[0100] The control system 700 includes an input terminal 731, an output terminal 732, an input protection circuit 701, a charge protection circuit 702, a discharge protection circuit 703, a selection circuit 704, an output control circuit 705, an output protection circuit 706, a potential adjustment circuit 711, a power generation circuit 712, and a control circuit 713. The control system 700 also preferably includes a charge control circuit 721.

[0101] In addition, the power storage system 100 preferably includes a temperature sensor.

[0102] 4A, a terminal 771 of the measurement circuit 750 is connected to the charge protection circuit 702, the discharge protection circuit 703, and the power generation circuit 712. In addition, in FIG. 4B, the terminal 771 of each of the plurality of measurement circuits 750 is connected to the charge protection circuit 702, the discharge protection circuit 703, and the power generation circuit 712.

[0103] An input signal is applied to the input terminal 731. The control system 700 may have multiple input terminals.

[0104] For example, a DC signal and an AC signal are applied to the input terminal 731. When an AC signal is applied to the input terminal 731, it is preferable that the control system 700 be provided with a circuit having a function of converting the applied AC signal into a DC signal.

[0105] The input protection circuit 701 has a function of preventing the internal circuitry of the control system 700 from being destroyed when static electricity, an overvoltage, an overcurrent, or the like is applied to the input terminal 731 .

[0106] The output protection circuit 706 has a function of preventing an overvoltage, an overcurrent, or the like from being output from the output terminal 732 to a circuit or device external to the control system 700 .

[0107] The input protection circuit 701 and the output protection circuit 706 are preferably configured using non-linear elements.

[0108] The charging protection circuit 702 has a function of detecting overcharging of the secondary battery 120. The charging protection circuit 702 also has a function of detecting overcurrent in charging the secondary battery 120.

[0109] The discharge protection circuit 703 has a function of detecting over-discharge of the secondary battery 120. The discharge protection circuit 703 also has a function of detecting discharge over-current of the secondary battery 120.

[0110] The detection of overcharge, overdischarge, charging overcurrent, and discharging overcurrent can be performed using a comparator. A hysteresis comparator may also be used as the comparator. The comparison result of the comparator is provided to, for example, a control circuit 713. For example, based on the comparison result of the comparator, the control circuit 713 generates a signal for cutting off the charging current to the secondary battery 120, cutting off the discharging current from the secondary battery 120, or changing the charging conditions of the secondary battery 120. For example, based on the comparison result of the comparator, the control circuit 713 can provide a signal for changing the charging conditions to the charge control circuit 721.

[0111] The charge control circuit 721 has a function of changing the charging conditions based on a value measured by the measurement circuit of one embodiment of the present invention. The charge control circuit 721 may also have a function of stopping charging.

[0112] The charge control circuit 721 has a function of changing the charge end voltage in accordance with the internal resistance of the secondary battery 120 diagnosed by the measurement circuit 750, for example.

[0113] If the diagnosis using the internal impedance determines that the deterioration of the secondary battery 120 is small, for example, the charge control circuit 721 increases the charge end voltage. By increasing the charge end voltage, it is possible to increase the power supplied by the power storage system 100. As the charge end voltage is increased, the overcharge detection voltage is changed as necessary.

[0114] Furthermore, depending on the result of the diagnosis using the internal impedance, for example, the discharge cut-off voltage can be lowered. As the discharge cut-off voltage is lowered, the over-discharge detection voltage is changed as necessary.

[0115] Furthermore, if the diagnosis using the internal resistance indicates that the internal resistance is high and suggests degradation of the secondary battery 120, for example, the charge control circuit 721 lowers the charge end voltage. Lowering the charge end voltage can extend the life of the power storage system 100 or improve safety. It is preferable to lower the overcharge detection voltage in conjunction with lowering the charge end voltage.

[0116] The measurement circuit of one embodiment of the present invention can be realized with a simple circuit configuration, and therefore, the state of a secondary battery can be easily acquired. Furthermore, the measurement circuit of one embodiment of the present invention can acquire the state of a secondary battery while using the secondary battery, for example, while charging or discharging the secondary battery. By using the measurement circuit of one embodiment of the present invention, the secondary battery can be used while being monitored, and therefore, signs of deterioration or abnormality of the secondary battery can be quickly detected. When signs of deterioration or abnormality of the secondary battery are detected, the power storage system of one embodiment of the present invention can suppress deterioration of the secondary battery and improve the safety of the secondary battery by changing the charging or discharging conditions of the secondary battery.

[0117] The control system 700 preferably has a current interruption element. A transistor can be used as the current interruption element, and a power MOSFET is particularly suitable. The control system 700 preferably uses the current interruption element to interrupt the charging current to the secondary battery 120 and the discharging current from the secondary battery 120.

[0118] FIG. 5C shows an example of a configuration in which the control system 700 has a switch unit 714. A current blocking element can be used as the switch unit 714. The switch unit 714 can also be configured by combining multiple current blocking elements. A transistor can be used as the current blocking element. An n-channel transistor and a p-channel transistor can both be used as the transistor. The switch unit 714 may also be configured by combining multiple transistors, for example. For example, the switch unit 714 can be configured by combining multiple n-channel transistors. The switch unit 714 can also be configured by combining multiple p-channel transistors. The switch unit 714 can also be configured by combining an n-channel transistor and a p-channel transistor.

[0119] The current interrupting element can be a Si transistor using single crystal silicon, or a power transistor containing Ge (germanium), SiGe (silicon germanium), GaAs (gallium arsenide), GaAlAs (gallium aluminum arsenide), InP (indium phosphide), SiC (silicon carbide), ZnSe (zinc selenide), GaN (gallium nitride), or GaOx (gallium oxide; x is a real number greater than 0).

[0120] An example configuration of the switch unit 714 is shown in FIG. 5D. The switch unit 714 shown in FIG. 5D has a transistor 140 and a transistor 150. The transistors 140 and 150 are connected in series. Power transistors can be used as the transistors 140 and 150. The transistors 140 and 150 each have a parasitic diode. A signal from the control circuit 713 is applied to the gate of the transistor 140 and the gate of the transistor 150, respectively. The orientations of the parasitic diodes in the transistors 140 and 150 are different from each other.

[0121] The potential adjustment circuit 711 has a function of converting the voltage, amplification, frequency, etc. of a signal. For example, it can step down or step up the power supply potential applied from the input terminal 731. For example, a signal is applied to the potential adjustment circuit 711 from the input terminal 731 via the input protection circuit 701.

[0122] For example, when power is supplied from outside the power storage system 100 to the input terminal 731, the potential adjustment circuit 711 adjusts the voltage of the supplied power supply so that it is higher than the voltage supplied from the discharge protection circuit 703 to the selection circuit 704. The selection circuit 704 selects and outputs the signal having the higher voltage from the signal from the potential adjustment circuit 711 or the signal from the discharge protection circuit 703.

[0123] When no power is supplied to the input terminal 731 , the signal output from the potential adjustment circuit 711 is adjusted to be lower than the signal from the discharge protection circuit 703 .

[0124] The selection circuit 704 has a function of selecting either a signal from the input terminal 731 via the potential adjustment circuit 711 or a signal from the secondary battery 120 via the discharge protection circuit 703 .

[0125] The output control circuit 705 can monitor the signal provided to it from the selection circuit 704 and cut off the output from the control system 700. For example, upper and lower limit voltages, upper and lower currents, etc. of the signal can be set and the signal can be monitored. The output control circuit 705 may also have a function of converting, for example, the voltage, amplification, frequency, etc. of the signal.

[0126] Power is supplied from the output terminal 732 to external circuits and external electronic devices outside the power storage system 100. The power storage system 100 may have a plurality of output terminals.

[0127] The control circuit 713 has a function of providing a signal to each circuit included in the power storage system 100. The control circuit 713 also preferably has a function of receiving measurement data from the measurement circuit 750, a function of analyzing the received data, and a function of providing a signal to each circuit included in the power storage system 100 based on the received data.

[0128] It is also preferable that the control circuit 713 has the functions of receiving measurement data such as the voltage and current of the battery cells of the secondary battery 120, analyzing the received data, and providing signals to each circuit of the energy storage system 100 based on the received data.

[0129] The control circuit 713 preferably includes a CPU (Central Processing Unit), an MPU (Micro-processing Unit), etc. The control circuit 713 may also include a PLD (Programmable Logic Device) such as an FPGA (Field Programmable Gate Array).

[0130] The power supply generating circuit 712 has a function of generating a high potential signal, a constant potential signal, a ground signal, etc. to be provided to the control circuit 713. The power supply generating circuit 712 also has a function of generating a clock signal. The power supply generating circuit 712 also has a function of generating an AC signal.

[0131] The power supply generating circuit 712 has a function of supplying the generated AC signal to the measuring circuit 750 .

[0132] Alternatively, the AC signal to be applied to the measurement circuit 750 may be applied to the measurement circuit 750 from a circuit external to the control system 700 via the input terminal 731 .

[0133] The control system 700 also preferably includes a storage unit. The storage unit may include a volatile memory, a non-volatile memory, etc. The storage unit preferably includes a non-volatile memory.

[0134] The storage unit of the control system 700 may include a memory circuit including a transistor using an oxide semiconductor (OS transistor).

[0135] It is preferable to use a metal oxide that functions as an oxide semiconductor. For example, a metal oxide such as In-M-Zn oxide (wherein 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, etc.) can be used. In particular, the In-M-Zn oxide that can be used as the metal oxide is preferably a C-Axis Aligned Crystal Oxide Semiconductor (CAAC-OS) or a Cloud-Aligned Composite Oxide Semiconductor (CAC-OS). Alternatively, an In-Ga oxide or an In-Zn oxide may be used. A CAAC-OS is an oxide semiconductor having multiple crystalline regions, each of which has a c-axis aligned in a specific direction. The specific direction is the thickness direction of the CAAC-OS film, the normal direction to the surface on which the CAAC-OS film is formed, or the normal direction to the surface of the CAAC-OS film. The crystalline region is a region in which the atomic arrangement is periodic. If the atomic arrangement is considered as a lattice arrangement, the crystalline region is also a region in which the lattice arrangement is regular.

[0136] In addition, "CAC-OS" has a mosaic structure in which the material is separated into a first region and a second region, and the first region is distributed throughout the film (hereinafter also referred to as a cloud structure). In other words, CAC-OS is a composite metal oxide having a structure in which the first region and the second region are mixed. However, it may be difficult to observe a clear boundary between the first region and the second region.

[0137] For example, in the case of CAC-OS in In-Ga-Zn oxide, EDX mapping obtained using EDX (Energy Dispersive X-ray spectroscopy) confirms that the CAC-OS has a structure in which a region mainly composed of In (first region) and a region mainly composed of Ga (second region) are unevenly distributed and mixed.

[0138] When CAC-OS is used in a transistor, the conductivity due to the first region and the insulating property due to the second region act in a complementary manner, thereby providing the CAC-OS with a switching function (the ability to turn on and off). In other words, CAC-OS has a conductive function in part of the material and an insulating function in part of the material, and the material as a whole functions as a semiconductor. By separating the conductive function from the insulating function, both functions can be maximized. Therefore, by using CAC-OS in a transistor, a high on-current (I on ), high field-effect mobility (μ), and good switching behavior can be achieved.

[0139] Oxide semiconductors have a variety of structures, each with different characteristics. The oxide semiconductor of one embodiment of the present invention may include two or more of an amorphous oxide semiconductor, a polycrystalline oxide semiconductor, an a-like OS, a CAC-OS, an nc-OS, and a CAAC-OS.

[0140] Furthermore, the control system 700 preferably uses transistors using oxide semiconductors because they can be used in high-temperature environments. To simplify the process, the control system 700 may be formed using unipolar transistors. Transistors using oxide semiconductors in the semiconductor layer have a wider operating ambient temperature range than single-crystal silicon, from −40°C to 150°C, and their characteristics change less when the secondary battery is heated than single-crystal silicon. The off-current of a transistor using an oxide semiconductor is below the lower limit of measurement regardless of temperature, even at 150°C, whereas the off-current characteristics of single-crystal silicon transistors are highly temperature-dependent. For example, at 150°C, the off-current of a single-crystal silicon transistor increases, and the current on / off ratio does not become sufficiently large. The control system 700 can improve safety.

[0141] Furthermore, since memory elements using OS transistors can be freely arranged by stacking them on circuits using Si transistors, integration can be easily achieved. Furthermore, OS transistors can be manufactured using the same manufacturing equipment as Si transistors, and therefore can be manufactured at low cost. That is, in the control system 700, for example, if the control circuit 713 or the like has a circuit using Si transistors, a memory unit using OS transistors can be stacked on the circuit. Furthermore, a memory unit using OS transistors can be stacked on the switch unit 714 and integrated into a single chip. The volume occupied by the control system 700 can be reduced, enabling miniaturization.

[0142] The storage unit has a function of storing parameters for estimating the state of the secondary battery. The power storage system 100 has a function of estimating the state of the secondary battery 120 using the parameters stored in the storage unit.

[0143] The power storage system 100 has a function of comparing the parameters stored in the storage unit with the data measured by the measurement circuit 750, and determining the charging or discharging conditions for the secondary battery.

[0144] The parameters stored in the storage unit include the ambient temperature of the secondary battery, the charging voltage of the secondary battery, the discharging voltage of the secondary battery, and the frequency dependency of the current of the secondary battery.

[0145] The control system 700 may also include a neural network. The neural network can estimate the state of the secondary battery using parameters stored in the storage unit. Weighting coefficients of the neural network may also be stored in the storage unit.

[0146] FIG. 5A shows an example of a neural network according to one embodiment of the present invention. The neural network NN shown in FIG. 5A has an input layer IL, an output layer OL, and a hidden layer (intermediate layer) HL. The neural network NN can be configured as a neural network having multiple hidden layers HL, i.e., a deep neural network. Learning in a deep neural network is sometimes called deep learning. The output layer OL, input layer IL, and hidden layer HL each have multiple neuron circuits, and the neuron circuits provided in different layers are connected via synapse circuits.

[0147] The neural network NN is equipped with the ability to analyze the operation of the storage battery through learning. When the measured parameters of the storage battery are input into the neural network NN, calculations are performed in each layer. The calculations in each layer are performed by multiplying and accumulating the outputs of the neuron circuits in the previous layer and the weighting coefficients.

[0148] The connections between layers may be full connections, in which all neuron circuits are connected, or partial connections, in which only some neuron circuits are connected. For example, a convolutional neural network (CNN) may be used, in which only specific units are connected between adjacent layers and which has a convolutional layer and a pooling layer. CNNs are used, for example, for image processing. In the convolutional layer, for example, a product-sum operation is performed between image data and a filter. It is preferable to place the pooling layer immediately after the convolutional layer.

[0149] Figure 5B shows an example of a neuron's operation. It shows neuron N and two neurons in the previous layer that output signals to neuron N. Neuron N receives the output x1 of a neuron in the previous layer and the output x2 of a neuron in the previous layer. Neuron N then calculates the sum x1w1+x2w2 of the multiplication result (x1w1) of output x1 and weight w1 and the multiplication result (x2w2) of output x2 and weight w2, and then adds a bias b as needed to obtain the value a = x1w1+x2w2+b. The value a is then transformed by the activation function h, and neuron N outputs the output signal y = h(a).

[0150] As described above, the computation performed by a neuron includes the sum of the product of the output of a neuron in the previous layer and the weight, i.e., the sum-of-products computation (x1w1+x2w2 as described above). This sum-of-products computation may be performed in software using a program, or may be performed by hardware. When performing the sum-of-products computation by hardware, a sum-of-products computation circuit can be used. This sum-of-products computation circuit may be a digital circuit or an analog circuit. When an analog circuit is used for the sum-of-products computation circuit, it is possible to reduce the circuit size of the sum-of-products computation circuit or the number of memory accesses, thereby improving processing speed and reducing power consumption.

[0151] The product-sum operation circuit may be configured using transistors containing silicon (such as single crystal silicon) in their channel formation regions (hereinafter also referred to as Si transistors) or transistors containing an oxide semiconductor in their channel formation regions (hereinafter also referred to as OS transistors). OS transistors, in particular, have extremely low off-state current and are therefore suitable as transistors constituting the memory of the product-sum operation circuit. The product-sum operation circuit may be configured using both Si transistors and OS transistors.

[0152] For example, the current value of the resistor element 753 measured by the measurement circuit 750 and the voltage of the secondary battery are provided to the input layer of the neural network. The input layer may also be provided with a temperature acquired by a temperature sensor. For example, the frequency of the AC signal source is input to the input layer.

[0153] The input layer of the neural network may be provided with the state of charge (SOC), charging current, discharging current, etc. Alternatively, the neural network may estimate the state of charge (SOC) using the data provided to the input layer and output data corresponding to the SOC from the output layer.

[0154] The neural network, for example, learns data related to the deterioration of the secondary battery in advance. The neural network estimates the secondary battery and outputs, for example, information related to the deterioration of the secondary battery from an output layer. For example, the output layer of the neural network may output the SOH (State Of Health) of the secondary battery.

[0155] A parameter relating to the secondary battery obtained by the power storage system of one embodiment of the present invention from a certain time ago and a current parameter may be input to an input layer of the neural network.

[0156] The neural network may have previously learned the parameters of the secondary battery over time. By learning such parameters, it may be possible to predict the changes in the parameters of the secondary battery over time at future times by simply providing the neural network with data for a certain time, or data for a certain time and its neighboring edges, without inputting complex data over time.

[0157] Alternatively, a neural network may be used to determine the charging or discharging conditions of the secondary battery. For example, by providing parameters related to the secondary battery acquired by the power storage system of one embodiment of the present invention, such as the resistance value of the resistor 753 and the temperature of the temperature sensor, to an input layer of the neural network, the neural network can output suitable charging or discharging conditions that increase the energy density of the secondary battery and ensure the safety of the secondary battery, based on the state and environment of the secondary battery.

[0158] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0159] (Embodiment 2) 8A , a lithium-ion secondary battery will be described as an example of a structure applicable to the secondary battery of one embodiment of the present invention. The secondary battery includes an outer casing (not shown), a positive electrode 503, a negative electrode 506, a separator 507, and an electrolyte 508 in which a lithium salt or the like is dissolved. The separator 507 is provided between the positive electrode 503 and the negative electrode 506.

[0160] The positive electrode 503 includes a positive electrode active material and a positive electrode active material layer 502 provided on the positive electrode current collector 501. The positive electrode active material layer 502 includes, for example, a positive electrode active material, a conductive agent, and a binder.

[0161] The negative electrode 506 includes a negative electrode active material and a negative electrode active material layer 505 provided on a negative electrode current collector 504. The negative electrode active material layer 505 includes, for example, a negative electrode active material, a conductive agent, and a binder.

[0162] The positive electrode current collector 501 or the negative electrode current collector 504 can be made of a highly conductive material that does not alloy with carrier ions such as lithium, such as metals such as stainless steel, gold, platinum, zinc, iron, copper, aluminum, and titanium, or alloys thereof. Aluminum alloys containing elements that improve heat resistance, such as silicon, titanium, neodymium, scandium, and molybdenum, can also be used. They may also be made of a metal element that reacts with silicon to form a silicide. Examples of metal elements that react with silicon to form a silicide include zirconium, titanium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, cobalt, and nickel. The positive electrode current collector 501 or the negative electrode current collector 504 can be in a sheet, mesh, punched metal, expanded metal, or other suitable shape. The positive electrode current collector 501 or the negative electrode current collector 504 preferably has a thickness of 10 μm to 30 μm.

[0163] It is preferable that the negative electrode current collector 504 is made of a material that does not alloy with carrier ions such as lithium.

[0164] As the conductive agent, carbon-based materials such as graphene, carbon black, graphite, carbon fiber, and fullerene can be used. As the carbon black, for example, acetylene black (AB) can be used. As the graphite, for example, natural graphite, artificial graphite such as mesocarbon microbeads, etc. can be used. These carbon-based materials have high conductivity and can function as a conductive agent in the active material layer. Note that these carbon-based materials may also function as an active material.

[0165] In this specification and the like, graphene may include, for example, graphene, multilayer graphene, multi-graphene, graphene oxide, multilayer graphene oxide, multi-graphene oxide, reduced graphene oxide, reduced multilayer graphene oxide, reduced multi-graphene oxide, graphene quantum dots, etc. Graphene refers to a substance that contains carbon, has a shape such as a plate or sheet, and has a two-dimensional structure formed by six-membered carbon rings. The two-dimensional structure formed by six-membered carbon rings may also be called a carbon sheet. Graphene may have a functional group. Graphene preferably has a curved shape. Graphene may also be rolled up to resemble a carbon nanofiber.

[0166] Examples of carbon fibers that can be used include mesophase pitch-based carbon fibers and isotropic pitch-based carbon fibers. Carbon nanofibers and carbon nanotubes can also be used as carbon fibers. Carbon nanotubes can be produced by vapor phase growth, for example.

[0167] The active material layer may also contain, as a conductive agent, one or more selected from metal powders such as copper, nickel, aluminum, silver, and gold, metal fibers, and conductive ceramic materials.

[0168] As the binder, it is preferable to use materials such as polystyrene, polymethyl acrylate, polymethyl methacrylate (polymethyl methacrylate, PMMA), sodium polyacrylate, polyvinyl alcohol (PVA), polyethylene oxide (PEO), polypropylene oxide, polyimide, polyvinyl chloride, polytetrafluoroethylene, polyethylene, polypropylene, polyisobutylene, polyethylene terephthalate, nylon, polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), ethylene propylene diene polymer, polyvinyl acetate, and nitrocellulose.

[0169] Polyimide has excellent thermal, mechanical, and chemical stability. Furthermore, when polyimide is used as a binder, a dehydration reaction and a cyclization (imidization) reaction occur. These reactions can be performed, for example, by heat treatment. In an electrode of one embodiment of the present invention, when graphene having a functional group containing oxygen is used as the graphene and polyimide is used as the binder, the heat treatment can also reduce the graphene, thereby simplifying the process. Furthermore, because polyimide has excellent heat resistance, the heat treatment can be performed at a heating temperature of, for example, 200° C. or higher. By performing heat treatment at a heating temperature of 200° C. or higher, the reduction reaction of graphene can be sufficiently performed, and the conductivity of the electrode can be further increased.

[0170] Fluorine-containing polymer materials, specifically polyvinylidene fluoride (PVDF), can be used. PVDF is a resin with a melting point between 134°C and 169°C, and is a material with excellent thermal stability.

[0171] As the binder, it is preferable to use a rubber material such as styrene-butadiene rubber (SBR), styrene-isoprene-styrene rubber, acrylonitrile-butadiene rubber, butadiene rubber, ethylene-propylene-diene copolymer, etc. As the binder, fluororubber can also be used.

[0172] Furthermore, it is preferable to use, for example, a water-soluble polymer as the binder. Examples of the water-soluble polymer that can be used include polysaccharides. Examples of the polysaccharide that can be used include one or more selected from cellulose derivatives such as carboxymethyl cellulose (CMC), methyl cellulose, ethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, and regenerated cellulose, as well as starch. It is even more preferable to use these water-soluble polymers in combination with the aforementioned rubber material.

[0173] The binder may be used in combination with two or more of the above.

[0174] <Negative electrode active material> As the negative electrode active material, it is preferable to use a material capable of reacting with carrier ions of the secondary battery, a material capable of inserting and desorbing carrier ions, a material capable of alloying with a metal that becomes a carrier ion, a material capable of dissolving and precipitating a metal that becomes a carrier ion, or the like.

[0175] Silicon can be used as the negative electrode active material.

[0176] The negative electrode active material may be a metal or compound containing one or more elements selected from tin, gallium, aluminum, germanium, lead, antimony, bismuth, silver, zinc, cadmium, and indium. Examples of alloy compounds using such elements include Mg2Si, Mg2Ge, Mg2Sn, SnS2, V2Sn3, FeSn2, CoSn2, Ni3Sn2, Cu6Sn5, Ag3Sn, Ag3Sb, Ni2MnSb, CeSb3, LaSn3, La3Co2Sn7, CoSb3, InSb, and SbSn.

[0177] Alternatively, a material with low resistance may be used by adding impurity elements such as phosphorus, arsenic, boron, aluminum, or gallium to silicon. A silicon material pre-doped with lithium may also be used. Pre-doping methods include mixing silicon with lithium fluoride, lithium carbonate, or the like and annealing the mixture, or mechanically alloying lithium metal with silicon. After forming the electrode, the material may be combined with an electrode such as lithium metal to dope lithium through a charge-discharge reaction. The doped electrode may then be combined with a counter electrode (e.g., a positive electrode for a pre-doped negative electrode) to produce a secondary battery.

[0178] For example, silicon nanoparticles can be used as the negative electrode active material. The average diameter of the silicon nanoparticles is preferably 5 nm or more and less than 1 μm, more preferably 10 nm or more and 300 nm or less, and even more preferably 10 nm or more and 100 nm or less.

[0179] The silicon nanoparticles may be crystalline, or may have a crystalline region and an amorphous region.

[0180] Examples of silicon-containing materials include SiO x (x is preferably smaller than 2, more preferably 0.5 or more and 1.6 or less) can be used.

[0181] The silicon-containing material may have, for example, a plurality of crystal grains within a single particle. For example, a single particle may have one or more silicon crystal grains within it. The single particle may have silicon oxide around the silicon crystal grain. The silicon oxide may be amorphous. The material may also be a particle in which graphene is attached to a secondary silicon particle.

[0182] Furthermore, examples of compounds that can be used include Li2SiO3 and Li4SiO4. Li2SiO3 and Li4SiO4 may each be crystalline or amorphous.

[0183] The silicon-containing compound can be analyzed using NMR, XRD, Raman spectroscopy, SEM, TEM, EDX, or the like.

[0184] As the negative electrode active material, for example, carbon-based materials such as graphite, graphitizable carbon, non-graphitizable carbon, carbon nanotubes, carbon black, and graphene can be used.

[0185] Furthermore, as the negative electrode active material, for example, an oxide containing one or more elements selected from titanium, niobium, tungsten, and molybdenum can be used.

[0186] As the negative electrode active material, a combination of the above-mentioned metals, materials, compounds, etc. can be used.

[0187] Examples of negative electrode active materials include SnO, SnO2, titanium dioxide (TiO2), and lithium titanium oxide (Li4Ti5O 12 ), lithium-graphite intercalation compound (Li x C6), niobium pentoxide (Nb2O5), tungsten oxide (WO2), molybdenum oxide (MoO2), and other oxides can be used.

[0188] In addition, the negative electrode active material is a composite nitride of lithium and transition metals, Li3N-type 3-x M x N (M=Co, Ni, Cu) can be used. For example, Li 2.6 Co 0.4 N3 is preferable because it exhibits a large charge / discharge capacity (900 mAh / g).

[0189] The use of a lithium-transition metal complex nitride as the negative electrode material is preferable because it can be combined with a lithium-ion-free positive electrode material such as V2O5 or Cr3O8. Even when a material containing lithium ions is used as the positive electrode material, the lithium-transition metal complex nitride can be used as the negative electrode material by first removing the lithium ions contained in the positive electrode material.

[0190] In addition, materials that undergo a conversion reaction can also be used as the negative electrode active material. For example, transition metal oxides that do not undergo an alloying reaction with lithium, such as cobalt oxide (CoO), nickel oxide (NiO), and iron oxide (FeO), can be used as the negative electrode active material. Materials that undergo a conversion reaction include oxides such as Fe2O3, CuO, Cu2O, RuO2, and Cr2O3, and CoS 0.89 This phenomenon also occurs with sulfides such as NiS and CuS, nitrides such as Zn3N2, Cu3N and Ge3N4, phosphides such as NiP2, FeP2 and CoP3, and fluorides such as FeF3 and BiF3. Note that the above fluorides have high potentials and may therefore be used as positive electrode materials.

[0191] In addition, although the volume of the active material particles may change during charge and discharge, by disposing an electrolyte containing fluorine between a plurality of active material particles in the electrode, even if a volume change occurs during charge and discharge, it is easy to slide and suppress cracks, so that the cycle characteristics are dramatically improved. It is important that an organic compound containing fluorine exists between the plurality of active materials constituting the electrode.

[0192] <Positive electrode active material> Examples of the positive electrode active material include composite oxides having an olivine-type crystal structure, a layered rock salt-type crystal structure, or a spinel-type crystal structure. For example, compounds such as LiFePO4, LiFeO2, LiNiO2, LiMn2O4, V2O5, Cr2O5, and MnO2 can be mentioned.

[0193] In addition, a lithium-containing material having a spinel-type crystal structure containing manganese such as LiMn2O4 as the positive electrode active material is preferably mixed with lithium nickelate (LiNiO2 or LiNi 1-x M x O2 (0 <x <1) (M = Co, Al, etc.)). By adopting this configuration, the characteristics of the secondary battery can be improved.

[0194] In addition, as the positive electrode active material, the composition formula Li a Mn b M c O dA lithium-manganese composite oxide that can be expressed by the formula (1) can be used. Here, element M is preferably a metal element selected from among lithium and manganese, or silicon or phosphorus, and more preferably nickel. When measuring the entire <a / (b+c)<2、かつc>lithium-manganese composite oxide particle, it is preferable that the composition be 0 0 during discharge and satisfy 0.26≦(b+c) / d<0.5. The composition of metals, silicon, phosphorus, etc. in the entire lithium-manganese composite oxide particle can be measured using, for example, an inductively coupled plasma mass spectrometer (ICP-MS). The oxygen composition in the entire lithium-manganese composite oxide particle can be measured using, for example, energy dispersive X-ray spectroscopy (EDX). In addition, the composition can be determined by valence evaluation using fusion gas analysis and XAFS (X-ray absorption fine structure) analysis in combination with ICPMS analysis. The lithium manganese composite oxide refers to an oxide containing at least lithium and manganese, and may contain at least one element selected from the group consisting of chromium, cobalt, aluminum, nickel, iron, magnesium, molybdenum, zinc, indium, gallium, copper, titanium, niobium, silicon, phosphorus, and the like.

[0195] ​Alternatively, particles containing multiple positive electrode active materials listed above may be used as the positive electrode active material. For example, one of the positive electrode active materials listed above may be used as the first material, and another of the positive electrode active materials listed above may be used as the second material, with the first material being at least partially covered with the second material. Such particles, in which the first material is at least partially covered with the second material, may be referred to as a positive electrode active material composite. Examples of the composite process include one or more of the following: composite processes using mechanical energy, such as mechanochemical methods, mechanofusion methods, and ball milling; composite processes using liquid-phase reactions, such as coprecipitation methods, hydrothermal methods, and sol-gel methods; and composite processes using gas-phase reactions, such as barrel sputtering methods, atomic layer deposition (ALD), vapor deposition methods, and chemical vapor deposition (CVD). Furthermore, it is preferable to perform a heat treatment after the composite process. The composite treatment may also be called a surface coating treatment or a coating treatment.

[0196] <Structure of positive electrode active material> Materials with a layered rock-salt crystal structure, such as lithium cobalt oxide (LiCoO2), are known to have high discharge capacity and are excellent as positive electrode active materials for secondary batteries. An example of a material with a layered rock-salt crystal structure is a composite oxide represented by LiMO2. Metal M includes metal Me1. Metal Me1 is one or more metals including cobalt. Metal M can also include metal X in addition to metal Me1. Metal X is one or more metals selected from magnesium, calcium, zirconium, lanthanum, barium, copper, potassium, sodium, and zinc.

[0197] It is known that the strength of the Jahn-Teller effect in transition metal compounds varies depending on the number of electrons in the d orbital of the transition metal.

[0198] In compounds containing nickel, distortion may occur due to the Jahn-Teller effect. Therefore, when LiNiO2 is charged and discharged at high voltages, there is a concern that the crystal structure may collapse due to distortion. In LiCoO2, the influence of the Jahn-Teller effect is suggested to be small, and LiCoO2 may have better durability against charge and discharge at high voltages, which is preferable.

[0199] Here, the composition of the lithium composite oxide represented by LiMO2 is not limited to Li:M:O=1:1:2. Examples of the lithium composite oxide represented by LiMO2 include lithium cobalt oxide, lithium nickel-cobalt-manganese oxide, lithium nickel-cobalt-aluminate, and lithium nickel-cobalt-manganese-aluminate.

[0200] When cobalt is used as the element M in an amount of 75 atomic % or more, preferably 90 atomic % or more, and more preferably 95 atomic % or more, it has many advantages such as being relatively easy to synthesize and handle, and having excellent cycle characteristics.

[0201] On the other hand, when nickel is used as the element M in an amount of 33 atomic % or more, preferably 60 atomic % or more, and more preferably 80 atomic % or more, the raw material may be cheaper than when a large amount of cobalt is used, and the charge / discharge capacity per weight may increase, which is preferable.

[0202] Furthermore, the particle size may become small if nickel is used in an amount of 33 atomic % or more, preferably 60 atomic % or more, and more preferably 80 atomic % or more as the element M. Therefore, for example, the third particles described above preferably contain nickel as the element M in an amount of 33 atomic % or more, preferably 60 atomic % or more, and more preferably 80 atomic % or more.

[0203] Furthermore, the inclusion of nickel as element M along with cobalt can suppress the shift in the layered structure of cobalt and oxygen octahedra. This is preferable because it can make the crystal structure more stable, especially in the charged state at high temperatures. This is because nickel easily diffuses deep into the lithium cobalt oxide, and while it is present on the cobalt site during discharge, it is thought to be located on the lithium site through cation mixing during charge. The nickel present on the lithium site during charge is thought to function as a pillar supporting the layered structure of cobalt and oxygen octahedra, contributing to the stabilization of the crystal structure.

[0204] The element M does not necessarily have to contain manganese, nickel, or cobalt.

[0205] During charging, lithium is released from the surface of the particles, so the lithium concentration in the surface layer of the particles tends to be lower than in the interior, and the crystalline structure tends to collapse.

[0206] A particle according to one embodiment of the present invention contains lithium, an element M, and oxygen. The particle according to one embodiment of the present invention contains a lithium composite oxide represented by LiMO2 (where M is one or more metals including cobalt). The particle according to one embodiment of the present invention also contains one or more elements selected from magnesium, fluorine, aluminum, and nickel in the surface layer. By containing one or more of these elements in the surface layer, the particle according to one embodiment of the present invention can reduce structural changes in the surface layer of the particle associated with charge and discharge, thereby suppressing crack formation. Irreversible structural changes in the surface layer of the particle can be suppressed, thereby suppressing capacity loss associated with repeated charge and discharge. The concentrations of these elements in the surface layer are preferably higher than the concentrations of these elements in the entire particle. The particle according to one embodiment of the present invention may have a structure in the surface layer in which, for example, some atoms in the lithium composite oxide are substituted with one or more elements selected from magnesium, fluorine, aluminum, and nickel.

[0207] The positive electrode active material will be described with reference to FIGS.

[0208] The positive electrode active material shown in FIG. 6 can reduce the displacement of the CoO2 layer during repeated high-voltage charge and discharge. Furthermore, it can reduce the change in volume. Therefore, the positive electrode active material shown in FIG. 6 can achieve excellent cycle characteristics. In addition, it can adopt a stable crystal structure in a high-voltage charged state. Therefore, when a high-voltage charged state is maintained, short circuits may be less likely to occur. In such cases, safety is further improved, which is preferable.

[0209] In the positive electrode active material shown in FIG. 6, the change in crystal structure and the difference in volume per the same number of transition metal atoms are small when compared between a fully discharged state and a high-voltage charged state.

[0210] The positive electrode active material shown in FIG. 6 can be represented by a layered rock-salt structure. FIG. 6 shows an example of the crystal structure of one embodiment of the positive electrode active material before and after charge and discharge. In one embodiment of the positive electrode active material, the surface layer may have, in addition to or instead of the region represented by the layered rock-salt structure described below in FIG. 6 and the like, a crystal having titanium, magnesium, and oxygen and represented by a structure different from the layered rock-salt structure. For example, the surface layer may have a crystal having titanium, magnesium, and oxygen and represented by a spinel structure.

[0211] The crystal structure at a charge depth of 0 (discharged state) in Figure 6 is the same as that in Figure 7, R-3m(O3). On the other hand, the positive electrode active material shown in Figure 6 has a crystal structure different from the H1-3 type crystal structure when fully charged. This structure belongs to the space group R-3m and has the same symmetry of the CoO2 layers as the O3 type. Therefore, this structure is referred to as the O3' type crystal structure in this specification. While the O3' type crystal structure shown in Figure 6 indicates that lithium can be present at any lithium site with a probability of approximately 20%, this is not limited to this. It may be present only at a specific portion of the lithium sites. In both the O3 type and O3' type crystal structures, magnesium is preferably present in a dilute form between the CoO2 layers, i.e., at the lithium sites. Furthermore, halogens such as fluorine may be present randomly and dilutely at the oxygen sites.

[0212] In the O3'-type crystal structure, ions such as cobalt and magnesium ions occupy six coordination positions. Light elements such as lithium may occupy four coordination positions for oxygen.

[0213] The O3'-type crystal structure can also be said to be a crystal structure similar to the CdCl2-type crystal structure, although it has random Li between the layers. This CdCl2-type-like crystal structure was observed when lithium nickel oxide was charged to a charge depth of 0.94 (Li 0.06 It is known that the crystal structure of CdCl2 is similar to that of CdCl2 (NiO2), but pure lithium cobaltate or layered rock salt type positive electrode active materials containing a large amount of cobalt do not usually adopt the CdCl2 type crystal structure.

[0214] The anions in layered rock salt crystals and rock salt crystals have a cubic close-packed structure (face-centered cubic lattice structure). It is estimated that the anions in O3'-type crystals also have a cubic close-packed structure. When they come into contact, there is a crystal plane where the cubic close-packed structure formed by the anions is oriented in the same direction. However, since the space group of layered rock salt crystals and O3'-type crystals is R-3m, which is different from the space group of rock salt crystals, Fm-3m (the space group of general rock salt crystals), the Miller indices of the crystal planes that satisfy the above conditions are different between layered rock salt crystals and O3'-type crystals and rock salt crystals. In this specification, when the cubic close-packed structure formed by the anions is oriented in the same direction in layered rock salt crystals, O3'-type crystals, and rock salt crystals, it may be said that the crystal orientations are approximately the same.

[0215] In the positive electrode active material shown in Figure 6, the change in crystal structure between R-3m(O3) in the discharged state and the O3'-type crystal structure is more suppressed than in the positive electrode active material shown in Figure 7. For example, as shown by the dotted line in Figure 6, there is almost no deviation of the CoO2 layer between R-3m(O3) in the discharged state and the O3'-type crystal structure.

[0216] More specifically, the cathode active material shown in FIG. 6 exhibits high structural stability even at high charging voltages. For example, the cathode active material shown in FIG. 7 maintains the R-3m(O3) crystal structure even at charging voltages at which the H1-3 crystal structure is formed, such as approximately 4.6 V relative to the potential of lithium metal. Even at higher charging voltages, such as approximately 4.65 V to 4.7 V relative to the potential of lithium metal, there is a region in which the O3' crystal structure can be formed. Furthermore, the H1-3 crystal may only be observed when the charging voltage is increased above 4.7 V. Furthermore, even at lower charging voltages (e.g., charging voltages between 4.5 V and 4.6 V relative to the potential of lithium metal), the cathode active material shown in FIG. 6 may be able to form the O3' crystal structure. When graphite is used as the anode active material in a secondary battery, the voltage of the secondary battery decreases by the amount of the graphite potential. The potential of graphite is approximately 0.05 V to 0.2 V relative to the potential of lithium metal. Therefore, for example, even when the voltage of a secondary battery using graphite as a negative electrode active material is 4.3 V or higher and 4.5 V or lower, the positive electrode active material shown in Figure 6 can maintain the R-3m(O3) crystal structure. Furthermore, even when the charge voltage is higher, for example, when the voltage of the secondary battery is higher than 4.5 V and lower than 4.6 V, there is a region in which the O3'-type crystal structure can be formed. Furthermore, even when the charge voltage is lower, for example, when the voltage of the secondary battery is 4.2 V or higher and lower than 4.3 V, the positive electrode active material of one embodiment of the present invention may be able to form the O3'-type crystal structure.

[0217] Therefore, in the positive electrode active material shown in FIG. 6, the crystal structure is not easily broken even when the material is repeatedly charged and discharged at a high voltage.

[0218] In addition, in the positive electrode active material shown in Figure 6, the difference in volume per the same number of cobalt atoms between R-3m(O3) in the discharged state and the O3'-type crystal structure is 2.5% or less, more specifically 2.2% or less, and typically 1.8%.

[0219] In the O3'-type crystal structure, the coordinates of cobalt and oxygen in the unit cell can be expressed in the range of Co(0,0,0.5), O(0,0,x), 0.20≦x≦0.25. Regarding the lattice constant of the unit cell, the a-axis is preferably 0.2797≦a≦0.2837 (nm), more preferably 0.2807≦a≦0.2827 (nm), typically a=0.2817 (nm). The c-axis is preferably 1.3681≦c≦1.3881 (nm), more preferably 1.3751≦c≦1.3811 (nm), typically c=1.3781 (nm).

[0220] Magnesium, which exists randomly and dilutely between the CoO2 layers, i.e., at the lithium sites, has the effect of suppressing the displacement of the CoO2 layers when charged at high voltage. Therefore, when magnesium exists between the CoO2 layers, the O3'-type crystal structure is easily formed.

[0221] However, if the heat treatment temperature is too high, cation mixing occurs, increasing the possibility that magnesium will enter the cobalt site. x When x in CoO2 is small, the effect of maintaining the R-3m structure may be small. Furthermore, if the heat treatment temperature is too high, there are concerns about adverse effects such as cobalt being reduced to divalent and lithium evaporating.

[0222] Therefore, it is preferable to add a halogen compound such as a fluorine compound to the lithium cobalt oxide before the heat treatment to distribute magnesium throughout the particles. Adding the halogen compound lowers the melting point of the lithium cobalt oxide. Lowering the melting point makes it easier to distribute magnesium throughout the particles at a temperature where cation mixing is unlikely to occur. Furthermore, the presence of a fluorine compound is expected to improve corrosion resistance to hydrofluoric acid produced by decomposition of the electrolyte.

[0223] Note that increasing the magnesium concentration above a desired value may reduce the effect on stabilizing the crystal structure. This is thought to be because magnesium occupies not only the lithium site but also the cobalt site. The number of magnesium atoms in the positive electrode active material prepared according to one embodiment of the present invention is preferably 0.001 to 0.1 times the number of cobalt atoms, more preferably greater than 0.01 and less than 0.04, and even more preferably approximately 0.02. The magnesium concentration shown here may be, for example, a value obtained by performing elemental analysis of the entire particles of the positive electrode active material using ICP-MS or the like, or may be based on the value of the raw material composition during the preparation of the positive electrode active material.

[0224] The number of nickel atoms in the positive electrode active material is preferably 7.5% or less of the number of cobalt atoms, preferably 0.05% to 4%, and more preferably 0.1% to 2%. The nickel concentration shown here may be a value obtained by performing elemental analysis of the entire particles of the positive electrode active material using, for example, ICP-MS, or may be based on the value of the composition of raw materials in the process of producing the positive electrode active material.

[0225] The positive electrode active material shown in FIG. 6 can suppress the collapse of the crystal structure even at an extremely high charge voltage, and thus can be repeatedly charged at an extremely high end-of-charge voltage. Increasing the end-of-charge voltage can increase the energy density of the secondary battery, allowing the secondary battery's energy to be effectively utilized. Even when a secondary battery is used at such a high end-of-charge voltage, the power storage system of one embodiment of the present invention can easily estimate the state of the secondary battery and control the secondary battery according to the estimated state, thereby enabling the power storage system to operate safely. By incorporating the positive electrode active material of one embodiment of the present invention into the power storage system of one embodiment of the present invention, the secondary battery can be stably operated over a wide range of charge and discharge voltages.

[0226] <Particle size> If the particle size of the positive electrode active material is too large, problems such as difficulty in diffusing lithium and excessive roughness of the surface of the active material layer when applied to a current collector arise. On the other hand, if the particle size is too small, problems such as difficulty in supporting the active material layer when applied to a current collector and excessive reaction with the electrolyte occur. Therefore, the average particle size (D50: also referred to as median diameter) is preferably 1 μm or more and 100 μm or less, more preferably 2 μm or more and 40 μm or less, and even more preferably 5 μm or more and 30 μm or less.

[0227] <Analysis method> Whether a certain positive electrode active material exhibits the O3'-type crystal structure when charged at a high voltage can be determined by analyzing the positive electrode charged at a high voltage using XRD, electron diffraction, neutron diffraction, electron spin resonance (ESR), nuclear magnetic resonance (NMR), etc. XRD is particularly preferred because it can analyze the symmetry of transition metals such as cobalt contained in the positive electrode active material with high resolution, it can compare the level of crystallinity and the orientation of the crystals, it can analyze the periodic distortion of the lattice and the crystallite size, and it can obtain sufficient accuracy even when measuring the positive electrode obtained by disassembling the secondary battery.

[0228] As mentioned above, positive electrode active materials are characterized by minimal change in their crystal structure between the high-voltage charged and discharged states. Materials with a crystal structure that exhibits significant changes between the high-voltage charged and discharged states (50 wt% or more) are undesirable because they cannot withstand high-voltage charging and discharging. It is important to note that simply adding impurity elements may not result in the desired crystal structure. For example, even if lithium cobalt oxide containing magnesium and fluorine has the same characteristics, when charged at high voltage, the O3'-type crystal structure may be 60 wt% or more, or the H1-3-type crystal structure may be 50 wt% or more. Furthermore, at a certain voltage, the O3'-type crystal structure may be nearly 100 wt%, and further increasing the voltage may result in the H1-3-type crystal structure. Therefore, it is preferable to analyze the crystal structure of positive electrode active materials using techniques such as XRD. By combining these techniques with XRD, even more detailed analysis can be performed.

[0229] However, when positive electrode active materials are charged or discharged at high voltage, their crystal structure may change when exposed to air. For example, they may change from an O3'-type crystal structure to an H1-3-type crystal structure. Therefore, it is recommended that all samples be handled in an inert atmosphere, such as an argon-containing atmosphere.

[0230] The positive electrode active material shown in Figure 7 is lithium cobalt oxide (LiCoO2) to which no metal X is added. The crystal structure of the lithium cobalt oxide shown in Figure 7 changes depending on the depth of charge.

[0231] As shown in Figure 7, lithium cobalt oxide at a depth of charge of 0 (discharged state) has a region with a crystal structure of space group R-3m, with three CoO2 layers in the unit cell. For this reason, this crystal structure is sometimes called an O3-type crystal structure. Note that a CoO2 layer is an octahedral structure in which cobalt is six-coordinated with oxygen, and the layers are connected in a plane with edge sharing.

[0232] At a charge depth of 1, the crystal structure is of the space group P-3m1, with one CoO2 layer in the unit cell. Therefore, this crystal structure is sometimes called an O1-type crystal structure.

[0233] Furthermore, lithium cobalt oxide at a charge depth of approximately 0.8 has a crystal structure of the space group R-3m. This structure can be described as a structure in which a CoO2 structure such as P-3m1(O1) and a LiCoO2 structure such as R-3m(O3) are alternately stacked. Therefore, this crystal structure is sometimes referred to as an H1-3 crystal structure. In reality, the H1-3 crystal structure has twice the number of cobalt atoms per unit cell as other structures. However, in Figure 7 and other parts of this specification, for ease of comparison with other structures, the c-axis of the H1-3 crystal structure is shown as half the unit cell.

[0234] As an example, the coordinates of cobalt and oxygen in the unit cell of the H1-3 crystal structure can be expressed as Co(0,0,0.42150±0.00016), O1(0,0,0.27671±0.00045), and O2(0,0,0.11535±0.00045). O1 and O2 are each an oxygen atom. Thus, the H1-3 crystal structure is expressed by a unit cell using one cobalt and two oxygen atoms. On the other hand, the O3' crystal structure of one embodiment of the present invention is preferably expressed by a unit cell using one cobalt and one oxygen atom. This indicates that the symmetry between cobalt and oxygen differs between the O3' crystal structure and the H1-3 structure, and that the O3' crystal structure exhibits smaller changes from the O3 structure than the H1-3 structure. The unit cell that is more preferably used to represent the crystal structure of the positive electrode active material may be selected, for example, so that the GOF (good of fitness) value is smaller in Rietveld analysis of XRD.

[0235] When lithium cobalt oxide is repeatedly charged and discharged at a high voltage of 4.6 V or higher, based on the redox potential of lithium metal, or at a deep charge depth of 0.8 or higher, the crystal structure of the lithium cobalt oxide changes repeatedly (i.e., a non-equilibrium phase change) between the H1-3 crystal structure and the R-3m(O3) structure in the discharged state.

[0236] However, these two crystal structures have a large deviation in the CoO2 layers. As shown by the dotted lines and arrows in Figure 7, in the H1-3 type crystal structure, the CoO2 layers are significantly deviated from the R-3m(O3) structure. Such dynamic structural changes can adversely affect the stability of the crystal structure.

[0237] Furthermore, the difference in volume is large: when compared per the same number of cobalt atoms, the difference in volume between the H1-3 crystal structure and the O3 crystal structure in the discharged state is more than 3.0%.

[0238] In addition, the H1-3 type crystal structure, which has continuous CoO2 layers such as P-3m1(O1), is likely to be unstable.

[0239] Therefore, repeated high-voltage charging and discharging causes the crystalline structure of lithium cobalt oxide to collapse, which leads to a deterioration in cycle characteristics. This is thought to be because the collapse of the crystalline structure reduces the number of sites where lithium can exist stably and makes it difficult for lithium to be inserted and extracted.

[0240] <Electrolytes> The electrolyte preferably contains a solvent and a metal salt that serves as a carrier ion. The solvent for the electrolyte is preferably an aprotic organic solvent, such as ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate, chloroethylene carbonate, vinylene carbonate, γ-butyrolactone, γ-valerolactone, dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), methyl formate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, 1,3-dioxane, 1,4-dioxane, dimethoxyethane (DME), dimethyl sulfoxide, diethyl ether, methyl diglyme, acetonitrile, benzonitrile, tetrahydrofuran, sulfolane, or sultone, or any combination and ratio of two or more of these.

[0241] Furthermore, by using one or more flame-retardant and non-volatile ionic liquids (room-temperature molten salts) as the electrolyte solvent, it is possible to prevent the secondary battery from exploding or catching fire even if the internal temperature rises due to an internal short circuit or overcharging of the secondary battery. Ionic liquids are composed of cations and anions, including organic cations and anions. Examples of organic cations used in the electrolyte include aliphatic onium cations such as quaternary ammonium cations, tertiary sulfonium cations, and quaternary phosphonium cations, imidazolium cations, and aromatic cations such as pyridinium cations. Examples of anions used in the electrolyte include monovalent amide anions, monovalent methide anions, fluorosulfonate anions, perfluoroalkylsulfonate anions, tetrafluoroborate anions, perfluoroalkylborate anions, hexafluorophosphate anions, and perfluoroalkylphosphate anions.

[0242] Examples of salts that can be dissolved in the solvent include LiPF6, LiClO4, LiAsF6, LiBF4, LiAlCl4, LiSCN, LiBr, LiI, Li2SO4, and Li2B 10 Cl 10 , Li2B 12 Cl 12 Lithium salts such as LiCF3SO3, LiC4F9SO3, LiC(CF3SO2)3, LiC(C2F5SO2)3, LiN(CF3SO2)2, LiN(C4F9SO2)(CF3SO2), LiN(C2F5SO2)2 can be used alone or in any combination and ratio of two or more of these.

[0243] The electrolyte used in the secondary battery is preferably a highly purified electrolytic solution with a low content of granular dust or elements other than the constituent elements of the electrolyte (hereinafter simply referred to as "impurities"). Specifically, the weight ratio of impurities to the electrolyte is preferably 1% or less, preferably 0.1% or less, and more preferably 0.01% or less.

[0244] In addition, additives such as vinylene carbonate, propane sultone (PS), tert-butylbenzene (TBB), fluoroethylene carbonate (FEC), lithium bis(oxalato)borate (LiBOB), or dinitrile compounds such as succinonitrile and adiponitrile may be added to the electrolyte. The concentration of the added material may be, for example, 0.1 wt% to 5 wt% of the total solvent. VC or LiBOB are particularly preferred because they easily form a good coating.

[0245] A solution containing a solvent and a salt that serves as carrier ions may be called an electrolyte.

[0246] A polymer gel electrolyte in which a polymer is swollen with an electrolytic solution may also be used.

[0247] The use of a polymer gel electrolyte improves safety against leakage, etc. It also enables the secondary battery to be made thinner and lighter.

[0248] Examples of polymers that can be gelled include silicone gel, acrylic gel, acrylonitrile gel, polyethylene oxide gel, polypropylene oxide gel, and fluorine-based polymer gel.

[0249] Examples of polymers that can be used include polymers having a polyalkylene oxide structure such as polyethylene oxide (PEO), PVDF, and polyacrylonitrile, as well as copolymers containing these. For example, PVDF-HFP, a copolymer of PVDF and hexafluoropropylene (HFP), can be used. The polymer formed may also have a porous shape.

[0250] In addition, solid electrolytes containing inorganic materials such as sulfides or oxides, as well as solid electrolytes containing polymeric materials such as polyethylene oxide (PEO), can be used. When using a solid electrolyte, the installation of at least one of a separator and a spacer is unnecessary. Furthermore, since the entire battery can be solidified, the risk of leakage is eliminated, dramatically improving safety.

[0251] <Separator> Separator 507 can be made of, for example, paper, nonwoven fabric, glass fiber, ceramics, etc. Alternatively, it can be made of nylon (polyamide), vinylon (polyvinyl alcohol fiber), polyester, acrylic, polyolefin, polyurethane, polypropylene, polyethylene, etc. The separator is preferably processed into an envelope shape and disposed so as to encase either the positive electrode or the negative electrode.

[0252] Furthermore, a polymer film containing, for example, polypropylene, polyethylene, polyimide, etc. can be used for separator 507. Polyimide has good wettability with ionic liquids, and may be a more preferable material for separator 507 in some cases.

[0253] Polymer films containing polypropylene, polyethylene, etc. can be produced by either the dry method or the wet method. The dry method involves heating and stretching a polymer film containing polypropylene, polyethylene, polyimide, etc., to create gaps between the crystals and create fine holes. The wet method involves mixing a solvent into the resin beforehand, forming it into a film, and then extracting the solvent to create holes.

[0254] The left diagram in FIG. 8B shows an enlarged view of region 507a as an example of separator 507 (when produced by a wet method). In this example, a structure in which multiple holes 582 are formed in polymer film 581 is shown. The right diagram in FIG. 8B shows an enlarged view of region 507b as another example of separator 507 (when produced by a dry method). In this example, a structure in which multiple holes 585 are formed in polymer film 584 is shown.

[0255] The pore diameter of the separator may differ between the surface layer portion of the surface facing the positive electrode and the surface layer portion of the surface facing the negative electrode after charge and discharge. In this specification, the surface layer portion of the separator is preferably, for example, a region within 5 μm, more preferably within 3 μm, from the surface.

[0256] The separator may have a multi-layer structure, for example, a structure in which two types of polymer materials are laminated.

[0257] Alternatively, a structure can be used in which a ceramic material, a fluorine material, a polyamide material, or a mixture thereof is coated on a polymer film having, for example, polypropylene, polyethylene, polyimide, etc. Alternatively, a structure can be used in which a ceramic material, a fluorine material, a polyamide material, or a mixture thereof is coated on a nonwoven fabric, for example. Polyimide has good wettability with ionic liquids and may be more preferable as a coating material.

[0258] As the fluorine-based material, for example, PVdF, polytetrafluoroethylene, etc. can be used.

[0259] Examples of polyamide-based materials that can be used include nylon and aramid (meta-aramid, para-aramid).

[0260] <Exterior body> The exterior body of the secondary battery can be made of one or more materials selected from a metal material such as aluminum and a resin material. Alternatively, a film-like exterior body can be used. Examples of the film include a three-layer structure in which a thin, flexible metal film such as aluminum, stainless steel, copper, or nickel is provided on a film made of a material such as polyethylene, polypropylene, polycarbonate, ionomer, or polyamide, and an insulating synthetic resin film such as a polyamide resin or polyester resin is further provided on the thin metal film as the outer surface of the exterior body.

[0261] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0262] (Embodiment 3) In this embodiment mode, a method for manufacturing a secondary battery will be described.

[0263] <Method 1 for producing laminated secondary batteries> Here, an example of a method for producing a laminated secondary battery whose external views are shown in Figures 9A, 9B, and 9C will be described with reference to Figures 10A and 10B and Figures 11A and 11B. A secondary battery 500 shown in Figures 9A and 9B has a positive electrode 503, a negative electrode 506, a separator 507, an outer casing 509, a positive electrode lead electrode 510, and a negative electrode lead electrode 511. Note that, as a cross-sectional view of the laminated secondary battery shown in Figure 9A etc., for example, a structure in which a positive electrode, a separator, and a negative electrode are stacked and surrounded by an outer casing can be used, as shown in Figure 19 described later.

[0264] First, a positive electrode 503, a negative electrode 506, and a separator 507 are prepared. FIG. 10A shows an example of the positive electrode 503 and the negative electrode 506. The positive electrode 503 has a positive electrode active material layer 502 on a positive electrode current collector 501. The positive electrode 503 preferably has a tab region where the positive electrode current collector 501 is exposed. The negative electrode 506 has a negative electrode active material layer 505 on a negative electrode current collector 504. The negative electrode 506 preferably has a tab region where the negative electrode current collector 504 is exposed.

[0265] Next, negative electrodes 506, separators 507, and positive electrodes 503 are stacked. Figure 10B shows the stacked negative electrodes 506, separators 507, and positive electrodes 503. Here, an example is shown in which five pairs of negative electrodes and four pairs of positive electrodes are used. This can also be called a laminate consisting of negative electrodes, separators, and positive electrodes.

[0266] Next, the tab regions of the positive electrode 503 are joined together, and the positive electrode lead electrode 510 is joined to the tab region of the outermost positive electrode. For joining, ultrasonic welding, for example, may be used. Similarly, the tab regions of the negative electrode 506 are joined together, and the negative electrode lead electrode 511 is joined to the tab region of the outermost negative electrode.

[0267] Next, the negative electrode 506 , the separator 507 and the positive electrode 503 are placed on the exterior body 509 .

[0268] Next, as shown in Fig. 11A, the exterior body 509 is bent at the portion indicated by the dashed line. Thereafter, the outer periphery of the exterior body 509 is joined. For example, thermocompression bonding or the like may be used for joining. At this time, an area (hereinafter referred to as an inlet 516) that is not joined is provided in a part (or one side) of the exterior body 509 so that the electrolyte 508 can be introduced later.

[0269] 11B, electrolyte 508 is introduced into exterior body 509 through inlet 516 provided in exterior body 509. Electrolyte 508 is preferably introduced under a reduced pressure atmosphere or an inert atmosphere. Finally, inlet 516 is joined. In this manner, laminated secondary battery 500 can be fabricated.

[0270] In the above, the positive electrode lead electrode 510 and the negative electrode lead electrode 511 are led out of the exterior of the outer casing from the same side to produce the secondary battery 500 shown in Fig. 9A. The positive electrode lead electrode 510 and the negative electrode lead electrode 511 can also be led out of the exterior of the outer casing from opposite sides to produce the secondary battery 500 shown in Fig. 9B.

[0271] <Cylindrical secondary battery> An example of a cylindrical secondary battery will be described with reference to Fig. 12A. As shown in Fig. 12A, a cylindrical secondary battery 400 has a positive electrode cap (battery lid) 401 on the top surface, and a battery can (external can) 402 on the side and bottom surfaces. The positive electrode cap 401 and the battery can (external can) 402 are insulated by a gasket (insulating packing) 410.

[0272] Fig. 12B is a diagram showing a cross section of a cylindrical secondary battery. The cylindrical secondary battery shown in Fig. 12B has a positive electrode cap (battery lid) 601 on the top surface and a battery can (external can) 602 on the side and bottom surfaces. The positive electrode cap and battery can (external can) 602 are insulated by a gasket (insulating packing) 610.

[0273] A battery element is provided inside a hollow cylindrical battery can 602, in which a strip-shaped positive electrode 604 and a negative electrode 606 are wound with a separator 605 sandwiched between them. Although not shown, the battery element is wound around a center pin. One end of the battery can 602 is closed and the other end is open. The battery can 602 can be made of a metal such as nickel, aluminum, or titanium, or an alloy of these metals or an alloy of these metals with other metals (e.g., stainless steel), which are corrosion-resistant to the electrolyte. To prevent corrosion by the electrolyte, the battery can 602 is preferably coated with nickel, aluminum, or the like. Inside the battery can 602, the wound battery element, in which the positive electrode, negative electrode, and separator are wound, is sandwiched between a pair of opposing insulating plates 608 and 609. A nonaqueous electrolyte (not shown) is poured into the battery can 602, in which the battery element is provided. The nonaqueous electrolyte may be the same as that used in coin-type secondary batteries.

[0274] Because the positive and negative electrodes used in cylindrical storage batteries are wound, it is preferable to form active materials on both sides of the current collector. A positive electrode terminal (positive electrode current collector lead) 603 is connected to the positive electrode 604, and a negative electrode terminal (negative electrode current collector lead) 607 is connected to the negative electrode 606. Both the positive electrode terminal 603 and the negative electrode terminal 607 can be made of a metal material such as aluminum. The positive electrode terminal 603 is resistance-welded to a safety valve mechanism 613, and the negative electrode terminal 607 is resistance-welded to the bottom of the battery can 602. The safety valve mechanism 613 is electrically connected to the positive electrode cap 601 via a PTC (Positive Temperature Coefficient) element 611. The safety valve mechanism 613 cuts off the electrical connection between the positive electrode cap 601 and the positive electrode 604 when the internal pressure of the battery exceeds a predetermined threshold. The PTC element 611 is a thermosensitive resistor whose resistance increases as the temperature rises, and the increased resistance limits the amount of current to prevent abnormal heat generation. Barium titanate (BaTiO3) based semiconductor ceramics or the like can be used for the PTC element.

[0275] FIG. 12C illustrates an example of a power storage system 415. The power storage system 415 includes a plurality of secondary batteries 400. A positive electrode of each secondary battery is electrically connected to a conductor 424 separated by an insulator 425. The conductor 424 is electrically connected to a control system 420 through a wiring 423. A negative electrode of each secondary battery is electrically connected to the control system 420 through a wiring 426. The control system described in the above embodiment can be used as the control system 420. The control system 420 includes the measurement circuit described in the above embodiment. In the power storage system 415, the state of the secondary battery 400 can be estimated using the measurement circuit of one embodiment of the present invention. The power storage system 415 has a function of determining a charging condition or a discharging condition of the secondary battery 400 based on the state estimated by the measurement circuit of one embodiment of the present invention.

[0276] 12D , some components of a control system 420 included in the power storage system 415 may be provided as a circuit 420a on a chip for each secondary battery 400, and the remaining components may be provided as a circuit 420b on a single chip. For example, in the control system 420, a measurement circuit of one embodiment of the present invention may be provided in the circuit 420a.

[0277] A temperature control device may be provided between the multiple secondary batteries 400. When the secondary batteries 400 are overheated, they can be cooled by the temperature control device, and when the secondary batteries 400 are too cold, they can be heated by the temperature control device. This makes it difficult for the performance of the power storage system 415 to be affected by the outside air temperature.

[0278] Note that, although Figure 12A etc. shows an example in which a wound body made up of a positive electrode, a negative electrode, and a separator is wound to fit the shape of a cylindrical can, it is also possible to make a rectangular secondary battery by fitting the wound body to the shape of a rectangular can, for example.

[0279] <Secondary battery pack> Next, an example of a power storage system of one embodiment of the present invention will be described with reference to FIGS. 13A to 13C.

[0280] Fig. 13A is a diagram showing the appearance of a secondary battery pack 531. Fig. 13B is a diagram illustrating the configuration of the secondary battery pack 531. The secondary battery pack 531 has a circuit board 521 and a secondary battery 513. The secondary battery 513 has one of a positive electrode lead and a negative electrode lead 551 and the other of the positive electrode lead and negative electrode lead 552, and is covered with a label 514. The circuit board 521 is fixed with a sticker 515. The secondary battery pack 531 also has an antenna 517.

[0281] The circuit board 521 includes a control system 590. The control system included in the power storage system described in the above embodiment can be used as the control system 590, and the control system 590 includes the measurement circuit described in the above embodiment. In the secondary battery pack 531, the state of the secondary battery 513 can be estimated using the measurement circuit of one embodiment of the present invention. The secondary battery pack 531 has a function of determining a charge condition or a discharge condition of the secondary battery 513 based on the state estimated by the measurement circuit of one embodiment of the present invention. For example, as shown in FIG. 13B , the control system 590 is provided on the circuit board 521. The circuit board 521 is electrically connected to a terminal 522. The circuit board 521 is electrically connected to the antenna 517, one 551 of the positive electrode lead and the negative electrode lead of the secondary battery 513, and the other 552 of the positive electrode lead and the negative electrode lead.

[0282] 13C , the circuit system 590a may be provided on a circuit board 521, and the circuit system 590b may be electrically connected to the circuit board 521 via a terminal 522. For example, a portion of a control system according to an embodiment of the present invention is provided in the circuit system 590a, and another portion is provided in the circuit system 590b. For example, the circuit system 590a preferably includes the measurement circuit according to an embodiment of the present invention.

[0283] The antenna 517 is not limited to a coil shape, and may be, for example, a wire or plate shape. Also, antennas such as a planar antenna, an aperture antenna, a traveling wave antenna, an EH antenna, a magnetic field antenna, and a dielectric antenna may be used. Alternatively, the antenna 517 may be a flat conductor. This flat conductor can function as one of the conductors for electric field coupling. In other words, the antenna 517 may function as one of the two conductors of a capacitor. This allows power to be exchanged not only by electromagnetic fields and magnetic fields, but also by electric fields.

[0284] The secondary battery pack 531 has a layer 519 between the antenna 517 and the secondary battery 513. The layer 519 has a function of, for example, shielding an electromagnetic field caused by the secondary battery 513. The layer 519 can be made of, for example, a magnetic material.

[0285] The secondary battery 513 is formed by stacking a negative electrode and a positive electrode with a separator sandwiched between them, and then winding the laminate sheet.

[0286] Examples of various types of secondary batteries are shown below.

[0287] <Other secondary batteries and their manufacturing methods 1> An example of a cross-sectional view of a stack of one embodiment of the present invention is shown in Figure 14. A stack 550 shown in Figure 14 is produced by placing one separator between a positive electrode and a negative electrode while folding it.

[0288] In the laminate 550, one separator 507 is folded multiple times so as to be sandwiched between the positive electrode active material layers 502 and the negative electrode active material layers 505. In FIG. 14, six layers of positive electrodes 503 and six layers of negative electrodes 506 are stacked, and therefore the separator 507 is folded at least five times. The separator 507 may not only be provided so as to be sandwiched between the positive electrode active material layers 502 and the negative electrode active material layers 505, but also have its extending portion further folded so that the plurality of positive electrodes 503 and negative electrodes 506 are bound together with tape or the like.

[0289] In the method for manufacturing a secondary battery of one embodiment of the present invention, after the positive electrode 503 is disposed, an electrolyte can be dropped onto the positive electrode 503. Similarly, after the negative electrode 506 is disposed, an electrolyte can be dropped onto the negative electrode 506. Furthermore, in the method for manufacturing a secondary battery of one embodiment of the present invention, an electrolyte can be dropped onto the separator 507 before folding the separator or after folding the separator 507 and overlapping it with the negative electrode 506 or the positive electrode 503. By dropping the electrolyte onto at least one of the negative electrode 506, the separator 507, and the positive electrode 503, the negative electrode 506, the separator 507, or the positive electrode 503 can be impregnated with the electrolyte.

[0290] 15A has a laminate 972 inside a housing 971. A terminal 973b and a terminal 974b are electrically connected to the laminate 972. At least a portion of the terminal 973b and at least a portion of the terminal 974b are exposed to the outside of the housing 971.

[0291] A structure in which a positive electrode, a negative electrode, and a separator are stacked can be used as the stack body 972. Alternatively, a structure in which a positive electrode, a negative electrode, and a separator are wound can be used as the stack body 972.

[0292] For example, the laminate 972 may be a laminate having a structure in which the separator is folded back as shown in FIG.

[0293] An example of a method for manufacturing the stacked body 972 will be described with reference to FIGS. 15B and 15C.

[0294] First, as shown in FIG. 15B, a strip-shaped separator 976 is placed on top of a positive electrode 975a, and then a negative electrode 977a is placed on top of the positive electrode 975a with the separator 976 sandwiched between them. Thereafter, the separator 976 is folded back and placed on top of the negative electrode 977a. Next, as shown in FIG. 15C, a positive electrode 975b is placed on top of the negative electrode 977a with the separator 976 sandwiched between them. In this way, by folding back the separator and arranging the positive electrode and negative electrode in order, a stack 972 can be produced. A structure including a stack produced in this way is sometimes called a "zigzag structure."

[0295] Next, an example of a method for manufacturing the secondary battery 970 will be described with reference to FIGS. 16A to 16C.

[0296] 16A, a positive electrode lead electrode 973a is electrically connected to the positive electrode of the laminate 972. Specifically, for example, a tab region may be provided on each positive electrode of the laminate 972, and each tab region may be electrically connected to the positive electrode lead electrode 973a by welding or the like. In addition, a negative electrode lead electrode 974a is electrically connected to the negative electrode of the laminate 972.

[0297] One stack 972 or a plurality of stacks 972 may be arranged inside housing 971. Fig. 16B shows an example in which two sets of stacks 972 are prepared.

[0298] Next, as shown in FIG. 16C , the prepared laminate 972 is housed in a housing 971, terminals 973b and 974b are attached, and the housing 971 is sealed. It is preferable that a conductor 973c is electrically connected to each positive electrode lead electrode 973a of the plurality of laminates 972. It is also preferable that a conductor 974c is electrically connected to each negative electrode lead electrode 974a of the plurality of laminates 972. The terminal 973b is electrically connected to the conductor 973c, and the terminal 974b is electrically connected to the conductor 974c. The conductor 973c may have a conductive region and an insulating region. The conductor 974c may have a conductive region and an insulating region.

[0299] A metal material (such as aluminum) can be used for the housing 971. When a metal material is used for the housing 971, the surface is preferably covered with resin or the like. Alternatively, a resin material can be used for the housing 971.

[0300] It is preferable to provide a safety valve, an overcurrent protection element, or the like in the housing 971. The safety valve is a valve that releases gas when the pressure inside the housing 971 reaches a predetermined level in order to prevent the battery from exploding.

[0301] <Other secondary batteries and their manufacturing methods 2> 17C shows an example of a cross-sectional view of a secondary battery of another embodiment of the present invention. A secondary battery 560 shown in Fig. 17C is fabricated using the stack 130 shown in Fig. 17A and the stack 131 shown in Fig. 17B. Note that for clarity, Fig. 17C only shows the stack 130, the stack 131, and the separator 507.

[0302] As shown in FIG. 17A, the laminate 130 includes a positive electrode 503 having a positive electrode active material layer on both sides of a positive electrode current collector, a separator 507, a negative electrode 506 having a negative electrode active material layer on both sides of a negative electrode current collector, the separator 507, and a positive electrode 503 having a positive electrode active material layer on both sides of a positive electrode current collector, stacked in this order.

[0303] As shown in FIG. 17B , the laminate 131 includes a negative electrode 506 having a negative electrode active material layer on both sides of a negative electrode current collector, a separator 507, a positive electrode 503 having a positive electrode active material layer on both sides of a positive electrode current collector, the separator 507, and a negative electrode 506 having a negative electrode active material layer on both sides of a negative electrode current collector laminated in this order.

[0304] The method for manufacturing a secondary battery according to one embodiment of the present invention can be applied to manufacturing a stack. Specifically, when stacking the negative electrode 506, the separator 507, and the positive electrode 503 to manufacture a stack, an electrolyte is dropped onto at least one of the negative electrode 506, the separator 507, and the positive electrode 503. By dropping multiple drops of the electrolyte, the negative electrode 506, the separator 507, or the positive electrode 503 can be impregnated with the electrolyte.

[0305] As shown in FIG. 17C, the plurality of stacks 130 and the plurality of stacks 131 are covered with a wound separator 507.

[0306] In addition, in the method for manufacturing a secondary battery of one embodiment of the present invention, after the stack 130 is arranged, an electrolyte can be dropped onto the stack 130. Similarly, after the stack 131 is arranged, an electrolyte can be dropped onto the stack 131. Furthermore, before the separator 507 is folded, or after the separator 507 is folded and overlapped with the stack, an electrolyte can be dropped onto the separator 507. By dropping multiple drops of the electrolyte, the stack 130, the stack 131, or the separator 507 can be impregnated with the electrolyte.

[0307] <Other secondary batteries and their manufacturing methods 3> 18A to 19C, a secondary battery according to another embodiment of the present invention will be described. The secondary battery described here can be called a wound secondary battery, for example.

[0308] A secondary battery 913 shown in FIG. 18A has a wound body 950 provided with terminals 951 and 952 inside a housing 930. The wound body 950 is immersed in an electrolyte inside the housing 930. The terminal 952 contacts the housing 930, and the terminal 951 is not in contact with the housing 930 by using an insulating material or the like. Note that in FIG. 18A, for convenience, the housing 930 is shown separated, but in reality, the wound body 950 is covered by the housing 930, and the terminals 951 and 952 extend outside the housing 930. The housing 930 can be made of a metal material (such as aluminum) or a resin material.

[0309] 18B, the housing 930 shown in Fig. 18A may be formed from a plurality of materials. For example, the secondary battery 913 shown in Fig. 18B has housings 930a and 930b bonded together, and a wound body 950 is provided in the area surrounded by the housings 930a and 930b.

[0310] The housing 930a can be made of an insulating material such as organic resin. In particular, by using a material such as organic resin on the surface on which the antenna is formed, it is possible to prevent the secondary battery 913 from blocking the electric field. Note that if the electric field blocking effect of the housing 930a is small, the antenna may be provided inside the housing 930a. The housing 930b can be made of, for example, a metal material.

[0311] 18C shows the structure of wound body 950. Winding body 950 has a negative electrode 931, a positive electrode 932, and a separator 933. Winding body 950 is a wound body in which negative electrode 931 and positive electrode 932 are stacked on top of each other with separator 933 sandwiched therebetween, and the laminated sheet is wound. Note that multiple stacks of negative electrode 931, positive electrode 932, and separator 933 may be stacked.

[0312] In a method for manufacturing a secondary battery according to one embodiment of the present invention, when the negative electrode 931, the separator 933, and the positive electrode 932 are stacked, an electrolyte is dropped onto at least one of the negative electrode 931, the separator 933, and the positive electrode 932. That is, the electrolyte is preferably dropped onto at least one of the negative electrode 931, the separator 933, and the positive electrode 932 before the laminate sheet is wound. By dropping multiple drops of the electrolyte, the negative electrode 931, the separator 933, or the positive electrode 932 can be impregnated with the electrolyte.

[0313] Alternatively, a secondary battery 913 may be provided having a wound body 950a as shown in Fig. 19. The wound body 950a shown in Fig. 19A has a negative electrode 931, a positive electrode 932, and a separator 933. The negative electrode 931 has a negative electrode active material layer 931a. The positive electrode 932 has a positive electrode active material layer 932a.

[0314] The separator 933 has a width wider than the negative electrode active material layer 931a and the positive electrode active material layer 932a, and is wound so as to overlap the negative electrode active material layer 931a and the positive electrode active material layer 932a. From the standpoint of safety, it is preferable that the negative electrode active material layer 931a be wider than the positive electrode active material layer 932a. A wound body 950a having such a shape is preferable in terms of safety and productivity.

[0315] 19B, the negative electrode 931 is electrically connected to a terminal 951. The terminal 951 is electrically connected to a terminal 911a. The positive electrode 932 is electrically connected to a terminal 952. The terminal 952 is electrically connected to a terminal 911b.

[0316] 19C, wound body 950a and the electrolyte are covered with casing 930 to form secondary battery 913. It is preferable to provide casing 930 with a safety valve, an overcurrent protection element, etc. The safety valve opens temporarily only when the internal pressure of casing 930 exceeds a predetermined value, in order to prevent the battery from exploding.

[0317] 19B, the secondary battery 913 may have a plurality of wound bodies 950a. By using a plurality of wound bodies 950a, the secondary battery 913 can have a larger charge / discharge capacity.

[0318] This embodiment mode can be combined with other embodiment modes as appropriate.

[0319] (Fourth embodiment) In this embodiment, a structural example to which the power storage system of one embodiment of the present invention can be applied will be described with reference to FIGS. 20A to 29C.

[0320] <Vehicle> First, an example in which the power storage system of one embodiment of the present invention is applied to an electric vehicle (EV) will be described.

[0321] 20C shows a block diagram of a vehicle having a motor. The electric vehicle is equipped with first battery 1301a and first battery 1301b as main driving secondary batteries, and second battery 1311 that supplies power to inverter 1312 that starts motor 1304. Second battery 1311 is also called a cranking battery or starter battery. Second battery 1311 only needs to have high output, and does not need to have a large capacity, and the capacity of second battery 1311 is smaller than that of first battery 1301a and first battery 1301b.

[0322] For example, the secondary battery of one embodiment of the present invention can be used for one or both of the first battery 1301a and the first battery 1301b.

[0323] In this embodiment, an example is shown in which two first batteries 1301a and 1301b are connected in parallel, but three or more batteries may be connected in parallel. Also, if the first battery 1301a can store sufficient power, the first battery 1301b may not be necessary. By configuring a battery pack having multiple secondary batteries, it is possible to extract large amounts of power. The multiple secondary batteries may be connected in parallel, in series, or in series after being connected in parallel. A plurality of secondary batteries is also called a battery pack.

[0324] In addition, in a secondary battery for vehicle use, a service plug or circuit breaker that can cut off high voltage without using tools is provided in first battery 1301a in order to cut off power from multiple secondary batteries.

[0325] The power of the first battery 1301a and the first battery 1301b is mainly used to rotate the motor 1304, but also supplies power to 42V (high voltage) in-vehicle components (such as an electric power steering 1307, a heater 1308, and a defogger 1309) via a DC-DC circuit 1306. When a rear motor 1317 is provided on the rear wheels, the first battery 1301a is also used to rotate the rear motor 1317.

[0326] The second battery 1311 also supplies power via the DC-DC circuit 1310 to 14V (low voltage) in-vehicle components (audio 1313, power windows 1314, lamps 1315, etc.).

[0327] The first battery 1301a will be described with reference to FIG. 20A.

[0328] 20A shows an example of a large battery pack 1415. One electrode of the battery pack 1415 is electrically connected to the control system 1320 by a wiring 1421. The other electrode is electrically connected to the control system 1320 by a wiring 1422. The battery pack may be configured by connecting a plurality of secondary batteries in series.

[0329] The control system 1320 can be the control system described in the above embodiment. The control system 1320 includes the measurement circuit described in the above embodiment. In the battery pack 1415 illustrated in FIG. 20A , the state of the first battery 1301a can be estimated using the measurement circuit of one embodiment of the present invention. The battery pack 1415 has a function of determining a charge condition or a discharge condition of the first battery 1301a based on the state estimated by the measurement circuit of one embodiment of the present invention. Similarly, the second battery 1311 can be controlled based on the state estimated by the measurement circuit of one embodiment of the present invention.

[0330] The first batteries 1301a and 1301b primarily supply power to 42V (high-voltage) in-vehicle devices, while the second battery 1311 supplies power to 14V (low-voltage) in-vehicle devices. Lead-acid batteries are often used for the second battery 1311 due to their cost advantages. Lead-acid batteries have the disadvantage of being more self-discharged than lithium-ion batteries and being prone to degradation due to a phenomenon called sulfation. Using a lithium-ion battery as the second battery 1311 offers the advantage of being maintenance-free, but after prolonged use (e.g., three years or more), there is a risk of abnormalities that are difficult to identify during manufacturing. In particular, if the second battery 1311, which starts the inverter, becomes inoperable, even if the first batteries 1301a and 1301b still have remaining capacity, the motor cannot be started. To prevent this, if the second battery 1311 is a lead-acid battery, power is supplied from the first battery to the second battery, and the second battery is constantly charged to maintain a fully charged state.

[0331] In this embodiment, an example is shown in which lithium ion batteries are used for both the first battery 1301a and the second battery 1311. A lead-acid battery, an all-solid-state battery, or an electric double layer capacitor may be used for the second battery 1311. Using an all-solid-state battery for the second battery 1311 allows for high capacity, miniaturization, and weight reduction.

[0332] Furthermore, regenerated energy generated by the rotation of the tire 1316 is sent to the motor 1304 via the gear 1305, and is then charged into the second battery 1311 via the motor controller 1303 or the battery controller 1302 via the control circuit unit 1321. Alternatively, the first battery 1301a is charged from the battery controller 1302 via the control system 1320. Alternatively, the first battery 1301b is charged from the battery controller 1302 via the control system 1320. In order to efficiently charge the regenerated energy, it is desirable that the first batteries 1301a and 1301b be capable of being quickly charged.

[0333] The battery controller 1302 can set the charging voltage and charging current of the first batteries 1301a and 1301b. The battery controller 1302 can set charging conditions according to the charging characteristics of the secondary battery used, and can perform rapid charging.

[0334] Although not shown, when an external charger is connected, the charger's outlet or the charger's connection cable is electrically connected to the battery controller 1302. The power supplied from the external charger is charged to the first batteries 1301a, 1301b via the battery controller 1302. Some chargers are provided with a control circuit, and although the function of the battery controller 1302 may not be used, it is preferable to charge the first batteries 1301a, 1301b via the control system 1320 to prevent overcharging. In some cases, the connection cable or the charger's connection cable is provided with a control circuit. The control system 1320 is also called an ECU (Electronic Control Unit). The ECU is connected to a CAN (Controller Area Network) provided in the electric vehicle. CAN is one of the serial communication standards used as an in-vehicle LAN. The ECU includes a microcomputer. The ECU uses a CPU or a GPU.

[0335] External chargers installed at charging stations and the like are available in 100V-200V outlets, or three-phase 200V and 50kW. Charging is also possible by receiving power from external charging equipment using a wireless power supply system, etc.

[0336] FIG. 20B shows an example of a control system 1320. The control system 1320 shown in FIG. 20B includes a switch unit 1324 including at least a switch for preventing overcharging and a switch for preventing overdischarging, a control circuit 1322 for controlling the switch unit 1324, and a voltage measurement unit for the first battery 1301a. The control system 1320 sets upper and lower voltage limits for the secondary battery to be used and limits the upper limit of the current from the outside or the upper limit of the output current to the outside. The range between the lower limit voltage and the upper limit voltage of the secondary battery is within the recommended voltage range. If the voltage falls outside this range, the switch unit 1324 activates and functions as a protection circuit. The control system 1320 can also be called a protection circuit because it controls the switch unit 1324 to prevent overcharging and / or overdischarging. For example, if the control circuit 1322 detects a voltage that could cause overcharging, it turns off the switch unit 1324 to shut off the current. Furthermore, a PTC element may be provided in the charge / discharge path to provide a function of cutting off current in response to a rise in temperature. Control system 1320 also has external terminal 1325 (+IN) and external terminal 1326 (-IN).

[0337] Next, an example in which the secondary battery of one embodiment of the present invention is mounted on a vehicle, typically a transportation vehicle, will be described.

[0338] When a secondary battery according to one embodiment of the present invention is installed in a vehicle, next-generation clean energy vehicles such as hybrid vehicles (HVs), electric vehicles (EVs), and plug-in hybrid vehicles (PHVs) can be realized. Furthermore, the secondary battery can also be installed in agricultural machinery such as electric tractors, mopeds including electrically assisted bicycles, motorcycles, electric wheelchairs, electric carts, small or large ships, submarines, aircraft such as fixed-wing aircraft and rotary-wing aircraft, rockets, artificial satellites, space probes or planetary probes, and spacecraft. The use of a secondary battery according to one embodiment of the present invention enables a large secondary battery. Therefore, the secondary battery according to one embodiment of the present invention can be suitably used in transportation vehicles.

[0339] 21A to 21E illustrate a transportation vehicle using a secondary battery of one embodiment of the present invention. The automobile 2001 illustrated in FIG. 21A is an electric automobile using an electric motor as a power source for traveling. Alternatively, it is a hybrid automobile that can appropriately select and use an electric motor or an engine as a power source for traveling. When a secondary battery is installed in a vehicle, the secondary battery is installed in one or more locations. The automobile 2001 illustrated in FIG. 21A includes the battery pack 1415 illustrated in FIG. 20A. The battery pack 1415 includes a secondary battery module. The battery pack 1415 further includes a control system electrically connected to the secondary battery module. The control system including the measurement circuit described in the above embodiment can be used as the control system. The secondary battery module includes one or more secondary batteries.

[0340] Furthermore, automobile 2001 can charge its secondary battery by receiving power supply from an external charging facility using a plug-in system, a contactless power supply system, or the like. Charging can be performed using a predetermined charging method or connector standard, such as CHAdeMO (registered trademark) or Combo, as appropriate. The charging device may be a charging station installed in a commercial facility or a household power source. For example, plug-in technology can be used to charge the secondary battery installed in automobile 2001 using external power supply. Charging can be performed by converting AC power to DC power via a conversion device such as an AC-DC converter.

[0341] Although not shown, a power receiving device can be mounted on a vehicle and power can be supplied contactlessly from a ground-based power transmitting device for charging. In the case of this contactless power supply method, by incorporating a power transmitting device into the road or an exterior wall, charging can be performed not only while the vehicle is stopped but also while the vehicle is moving. This contactless power supply method can also be used to transmit and receive power between two vehicles. Furthermore, a solar cell can be installed on the exterior of the vehicle, and the secondary battery can be charged while the vehicle is stopped or moving. For such contactless power supply, an electromagnetic induction method or a magnetic field resonance method can be used.

[0342] 21B shows a large transport vehicle 2002 having an electrically controlled motor as an example of a transport vehicle. The secondary battery module of the transport vehicle 2002 is, for example, a four-cell unit of secondary batteries of 3.5V to 4.7V, with 48 cells connected in series for a maximum voltage of 170V. Apart from the number of secondary batteries constituting the secondary battery module of the battery pack 2201, the transport vehicle 2002 has the same functions as those shown in FIG. 21A, and therefore a description thereof will be omitted.

[0343] FIG. 21C shows, as an example, a large transport vehicle 2003 having an electrically controlled motor. The secondary battery module of the transport vehicle 2003 has, for example, a maximum voltage of 600 V, which is obtained by connecting in series one hundred or more secondary batteries with a voltage of 3.5 V to 4.7 V. Therefore, a secondary battery with little variation in characteristics is required. By using the method for manufacturing a secondary battery according to one embodiment of the present invention, secondary batteries with stable battery characteristics can be manufactured, and mass production at low cost is possible from the viewpoint of yield. Furthermore, except for the number of secondary batteries constituting the secondary battery module of the battery pack 2202, the same functions as those shown in FIG. 21A are provided, and therefore description thereof will be omitted.

[0344] Fig. 21D shows, as an example, an aircraft 2004 having an engine that burns fuel. Since the aircraft 2004 shown in Fig. 21D has wheels for takeoff and landing, it can also be said to be part of a transportation vehicle, and has a battery pack 2203 that includes a secondary battery module formed by connecting multiple secondary batteries and includes the secondary battery module and a charge control device.

[0345] The secondary battery module of the aircraft 2004 has, for example, eight 4V secondary batteries connected in series to produce a maximum voltage of 32V. Other than the number of secondary batteries constituting the secondary battery module of the battery pack 2203, it has the same functions as those in Fig. 21A, and therefore a description thereof will be omitted.

[0346] FIG. 21E shows an example of a transport vehicle 2005 for transporting cargo. The transport vehicle 2005 has an electrically controlled motor and performs various tasks by receiving power from a secondary battery constituting a secondary battery module of a battery pack 2204. Furthermore, the transport vehicle 2005 does not necessarily have to be driven by a human driver and can be unmanned using CAN communication or the like. While FIG. 21E illustrates a forklift, this is not a limitation, and a battery pack having a secondary battery according to one embodiment of the present invention can be mounted on industrial machinery that can be operated using CAN communication or the like, such as an automated transporter, a work robot, or a small construction machine.

[0347] 22A shows an example of an electric bicycle using the secondary battery of one embodiment of the present invention. The secondary battery of one embodiment of the present invention can be applied to the electric bicycle 2100 shown in FIG. 22A. The power storage device 2102 shown in FIG. 22B includes, for example, a plurality of secondary batteries and a control system. The control system of one embodiment of the present invention can be used for the control system.

[0348] The electric bicycle 2100 includes a power storage device 2102. The power storage device 2102 can supply electricity to a motor that assists a rider. The power storage device 2102 is portable and is shown in a state detached from the bicycle in FIG. 22B . The power storage device 2102 includes a plurality of secondary batteries 2101 of one embodiment of the present invention, and a display unit 2103 can display the remaining battery charge and other information. The power storage device 2102 also includes a control system 2104 that can estimate and control the state of the secondary battery, which is an example of one embodiment of the present invention. The control system 2104 preferably includes the measurement circuit described in the above embodiment. The control system 2104 is electrically connected to the positive and negative electrodes of the secondary battery 2101. The control system 2104 may also include a small solid-state secondary battery. By including a small solid-state secondary battery in the control system 2104, power can be supplied to retain data in a memory circuit of the control system 2104 for a long period of time. Furthermore, a synergistic effect in terms of safety can be obtained by combining the positive electrode active material according to one embodiment of the present invention with a secondary battery using the positive electrode active material according to one embodiment of the present invention. The secondary battery using the positive electrode active material according to one embodiment of the present invention and the control system 2104 can significantly contribute to the elimination of accidents such as fires caused by secondary batteries.

[0349] 22C illustrates an example of a two-wheeled vehicle using the secondary battery of one embodiment of the present invention. A scooter 2300 illustrated in FIG. 22C includes a power storage device 2302, a side mirror 2301, and a turn signal light 2303. The power storage device 2302 can supply electricity to the turn signal light 2303. The power storage device 2302, which includes a plurality of secondary batteries each using the positive electrode active material of one embodiment of the present invention for its positive electrode, can have a high capacity and contribute to miniaturization. To improve safety, a control system of one embodiment of the present invention is preferably electrically connected to the secondary battery.

[0350] 22C, the power storage device 2302 can be stored in the under-seat storage compartment 2304. The power storage device 2302 can be stored in the under-seat storage compartment 2304 even if the under-seat storage compartment 2304 is small.

[0351] <Buildings> Next, an example in which the secondary battery of one embodiment of the present invention is mounted in a building will be described with reference to FIG.

[0352] The house shown in FIG. 23A has a power storage device 2612 having a secondary battery, and a solar panel 2610. The power storage device 2612 is electrically connected to the solar panel 2610 via wiring 2611 or the like. The power storage device 2612 may also be electrically connected to a ground-mounted charging device 2604. The power obtained by the solar panel 2610 can be charged to the power storage device 2612. The power stored in the power storage device 2612 can also be charged to a secondary battery of the vehicle 2603 via the charging device 2604. The power storage device 2612 is preferably installed in an underfloor space. By installing it in the underfloor space, the space above the floor can be used effectively. Alternatively, the power storage device 2612 may be installed on the floor.

[0353] The power stored in the power storage device 2612 can be supplied to other electronic devices in the house. Therefore, even when power cannot be supplied from a commercial power source due to a power outage or the like, the power storage device 2612 can be used as an uninterruptible power supply, allowing the use of electronic devices.

[0354] 23B illustrates an example of a power storage device 1700 according to one embodiment of the present invention. As illustrated in FIG. 23B, a large-scale storage battery 1791 using a secondary battery according to one embodiment of the present invention is installed in an underfloor space 1796 of a building 1799. The measurement circuit described in the above embodiment is preferably electrically connected to the storage battery 1791. The power storage device 1700 has a function of determining a charging condition or a discharging condition of the storage battery 1791 based on a state of the storage battery 1791 estimated by the measurement circuit according to one embodiment of the present invention.

[0355] A control device 1790 is installed in the storage battery 1791, and the control device 1790 is electrically connected to a distribution board 1703, a storage controller 1705 (also called a control device), a display 1706, and a router 1709 by wiring.

[0356] Electric power is sent from commercial power source 1701 to distribution board 1703 via service line attachment section 1710. Electric power is also sent to distribution board 1703 from storage battery 1791 and commercial power source 1701, and distribution board 1703 supplies the sent electric power to general load 1707 and storage load 1708 via an outlet (not shown).

[0357] The general load 1707 is, for example, an electrical appliance such as a television or a personal computer, and the power storage load 1708 is, for example, an electrical appliance such as a microwave oven, a refrigerator, or an air conditioner.

[0358] The power storage controller 1705 includes a measurement unit 1711, a prediction unit 1712, and a planner 1713. The measurement unit 1711 has a function of measuring the amount of power consumed by the general load 1707 and the power storage load 1708 during one day (for example, from midnight to midnight). The measurement unit 1711 may also have a function of measuring the amount of power of the storage battery 1791 and the amount of power supplied from the commercial power source 1701. The prediction unit 1712 has a function of predicting the amount of power demand to be consumed by the general load 1707 and the power storage load 1708 during the next day, based on the amount of power consumed by the general load 1707 and the power storage load 1708 during the previous day. The planner 1713 has a function of creating a plan for charging and discharging the storage battery 1791, based on the amount of power demand predicted by the prediction unit 1712.

[0359] The amount of power consumed by the general load 1707 and the power storage load 1708 measured by the measurement unit 1711 can be confirmed on the display 1706. It can also be confirmed on an electrical device such as a television or a personal computer via the router 1709. It can also be confirmed on a mobile electronic device such as a smartphone or a tablet via the router 1709. The amount of power demand for each time period (or each hour) predicted by the prediction unit 1712 can also be confirmed on the display 1706, the electrical device, or the mobile electronic device.

[0360] <Electronic equipment> The secondary battery of one embodiment of the present invention can be used in, for example, one or both of an electronic device and a lighting device, such as a mobile phone, a smartphone, a portable information terminal such as a laptop computer, a portable game console, a portable music player, a digital camera, or a digital video camera.

[0361] A personal computer 2800 illustrated in FIG. 24A includes a housing 2801, a housing 2802, a display portion 2803, a keyboard 2804, a pointing device 2805, and the like. A secondary battery 2807 is provided inside the housing 2801, and a secondary battery 2806 is provided inside the housing 2802. To enhance safety, it is preferable to electrically connect a control system according to one embodiment of the present invention to the secondary battery 2807. Furthermore, by using the control system according to one embodiment of the present invention, the energy density that can be used in the secondary battery 2807 can be increased. Furthermore, by using the control system according to one embodiment of the present invention, the life of the secondary battery can be extended. The control system includes the measurement circuit described in the above embodiment. A touch panel is applied to the display portion 2803. As illustrated in FIG. 24B, the housings 2801 and 2802 can be removed from the personal computer 2800, and the personal computer 2800 can be used as a tablet terminal using only the housing 2802.

[0362] A large secondary battery to which the secondary battery according to one embodiment of the present invention can be applied can be used as one or both of the secondary battery 2806 and the secondary battery 2807. The shape of the secondary battery according to one embodiment of the present invention can be freely changed by changing the shape of the exterior body. For example, by making the secondary battery 2806 and the secondary battery 2807 shaped to match the shapes of the housings 2801 and 2802, the capacity of the secondary battery can be increased, and the usage time of the personal computer 2800 can be extended. Furthermore, the weight of the personal computer 2800 can be reduced.

[0363] A flexible display is applied to the display portion 2803 of the housing 2802. A large-sized secondary battery to which the secondary battery according to one embodiment of the present invention can be applied is used as the secondary battery 2806. A large-sized secondary battery to which the secondary battery according to one embodiment of the present invention can be applied can be made bendable by using a flexible film for the exterior body of the large-sized secondary battery to which the secondary battery according to one embodiment of the present invention can be applied. As a result, the housing 2802 can be folded for use as shown in FIG. 24C. In this case, part of the display portion 2803 can also be used as a keyboard as shown in FIG. 24C.

[0364] Furthermore, the housing 2802 can be folded so that the display portion 2803 faces inward as shown in FIG. 24D, or so that the display portion 2803 faces outward as shown in FIG. 24E.

[0365] The secondary battery of one embodiment of the present invention can be applied to a bendable secondary battery and can be mounted in electronic devices. It can also be incorporated along the curved surfaces of the interior or exterior walls of houses or buildings, or the interior or exterior of automobiles.

[0366] FIG. 25A illustrates an example of a mobile phone. The mobile phone 7400 includes a display portion 7402 built into a housing 7401, operation buttons 7403, an external connection port 7404, a speaker 7405, a microphone 7406, and the like. Note that the mobile phone 7400 includes a secondary battery 7407. By using the secondary battery of one embodiment of the present invention as the secondary battery 7407, a lightweight mobile phone with a long lifetime can be provided. To improve safety, it is preferable to electrically connect a control system of one embodiment of the present invention to the secondary battery 7407. Furthermore, by using the control system of one embodiment of the present invention, the energy density that can be used in the secondary battery 7407 can be increased. Furthermore, by using the control system of one embodiment of the present invention, the lifetime of the secondary battery can be extended. The control system includes the measurement circuit described in the above embodiment.

[0367] FIG. 25B shows the mobile phone 7400 in a bent state. When the mobile phone 7400 is deformed by an external force and bent as a whole, the secondary battery 7407 installed inside is also bent. FIG. 25C shows the state of the bent secondary battery 7407 at that time. The secondary battery 7407 is a thin storage battery. The secondary battery 7407 is fixed in a bent state. The secondary battery 7407 has a lead electrode electrically connected to the current collector. For example, the current collector is copper foil, and a portion of the current collector is alloyed with gallium to improve adhesion with the active material layer in contact with the current collector, resulting in a configuration with high reliability when the secondary battery 7407 is bent.

[0368] FIG. 25D illustrates an example of a bangle-type display device. The portable display device 7100 includes a housing 7101, a display unit 7102, operation buttons 7103, and a secondary battery 7104. To improve safety, a control system according to one embodiment of the present invention is preferably electrically connected to the secondary battery 7407. FIG. 25E illustrates a bent secondary battery 7104. When the secondary battery 7104 is bent and worn on a user's wrist, the housing deforms, causing a change in the curvature of part or the entire secondary battery 7104. Note that the degree of curvature at any point on the curve, expressed as the radius of the corresponding circle, is referred to as the radius of curvature, and the reciprocal of the radius of curvature is referred to as the curvature. Specifically, part or the entire main surface of the housing or the secondary battery 7104 changes when the radius of curvature is in the range of 40 mm to 150 mm. High reliability can be maintained when the radius of curvature of the main surface of the secondary battery 7104 is in the range of 40 mm to 150 mm. By using the secondary battery of one embodiment of the present invention as the secondary battery 7104, a lightweight and long-life portable display device can be provided.

[0369] 25F shows an example of a wristwatch-type portable information terminal 7200. The portable information terminal 7200 includes a housing 7201, a display portion 7202, a band 7203, a buckle 7204, operation buttons 7205, an input / output terminal 7206, and the like.

[0370] The portable information terminal 7200 can execute various applications such as mobile phone calls, e-mail, document browsing and creation, music playback, internet communication, and computer games.

[0371] The display surface of the display portion 7202 is curved, and a display can be performed along the curved display surface. The display portion 7202 is also provided with a touch sensor, and can be operated by touching the screen with a finger or a stylus. For example, an application can be started by touching an icon 7207 displayed on the display portion 7202.

[0372] The operation button 7205 can be provided with various functions, such as time setting, power on / off operation, wireless communication on / off operation, silent mode activation / deactivation, power saving mode activation / deactivation, etc. For example, the functions of the operation button 7205 can be freely set by an operating system incorporated in the mobile information terminal 7200.

[0373] The mobile information terminal 7200 is also capable of performing standardized short-range wireless communication. For example, hands-free conversation is also possible by communicating with a wirelessly enabled headset.

[0374] The portable information terminal 7200 also includes an input / output terminal 7206, and can directly exchange data with another information terminal via a connector. Charging can also be performed via the input / output terminal 7206. Note that charging may be performed by wireless power supply without using the input / output terminal 7206.

[0375] The display portion 7202 of the mobile information terminal 7200 includes the secondary battery of one embodiment of the present invention. By using the secondary battery of one embodiment of the present invention, a lightweight mobile information terminal with a long life can be provided. To improve safety, a protection circuit that prevents overcharging and / or overdischarging of the secondary battery may be electrically connected to the secondary battery. For example, the secondary battery 7104 shown in FIG. 25E can be installed in a curved state inside the housing 7201 or in a bendable state inside the band 7203.

[0376] The portable information terminal 7200 preferably has a sensor, such as a fingerprint sensor, a pulse sensor, a body temperature sensor, a touch sensor, a pressure sensor, or an acceleration sensor.

[0377] 25G illustrates an example of a wristband-type display device. The display device 7300 includes a display portion 7304 and the secondary battery of one embodiment of the present invention. The control system of one embodiment of the present invention is preferably electrically connected to the secondary battery. The display device 7300 may also include a touch sensor in the display portion 7304 and function as a portable information terminal.

[0378] The display surface of the display portion 7304 is curved, and display can be performed along the curved display surface. The display state of the display device 7300 can be changed by short-range wireless communication according to a communication standard.

[0379] The display device 7300 also includes an input / output terminal, allowing direct data exchange with other information terminals via a connector. Charging can also be performed via the input / output terminal. Note that charging may also be performed by wireless power supply without using the input / output terminal.

[0380] By using the secondary battery of one embodiment of the present invention as the secondary battery included in the display device 7300, a lightweight display device with a long lifetime can be provided.

[0381] Furthermore, examples in which a secondary battery with good cycle characteristics according to one embodiment of the present invention is mounted in an electronic device will be described with reference to FIGS. 25H, 26, and 27. FIG.

[0382] By using the secondary battery of one embodiment of the present invention as a secondary battery in an electronic device, a lightweight product with a long life can be provided. For example, examples of daily electronic devices include electric toothbrushes, electric shavers, and electric beauty devices. For the secondary battery of these products, a small, lightweight, and large-capacity stick-shaped secondary battery is desired for ease of holding by users.

[0383] FIG. 25H is a perspective view of a device also known as a tobacco-containing smoking device (electronic cigarette). In FIG. 25H, electronic cigarette 7500 includes atomizer 7501 including a heating element, secondary battery 7504 that supplies power to the atomizer, and cartridge 7502 including a liquid supply bottle or a sensor. To enhance safety, a protection circuit that prevents overcharging and / or over-discharging of secondary battery 7504 may be electrically connected to secondary battery 7504. Secondary battery 7504 shown in FIG. 25H has external terminals that allow connection to a charging device. Because secondary battery 7504 is the tip of the device when held, it is desirable that its total length be short and its weight be light. The secondary battery of one embodiment of the present invention has high capacity and good cycle characteristics, making it possible to provide a compact and lightweight electronic cigarette 7500 that can be used for a long period of time. It is preferable that a control system of one embodiment of the present invention is electrically connected to the secondary battery.

[0384] Next, an example of a foldable tablet terminal is shown in Figures 26A and 26B. Tablet terminal 7600 shown in Figures 26A and 26B includes a housing 7630a, a housing 7630b, a movable portion 7640 connecting housings 7630a and 7630b, a display portion 7631 having display portions 7631a and 7631b, switches 7625 to 7627, a fastener 7629, and an operation switch 7628. Using a flexible panel for display portion 7631 allows for a tablet terminal with a larger display area. Figure 26A shows tablet terminal 7600 in an open state, and Figure 26B shows tablet terminal 7600 in a closed state.

[0385] The tablet terminal 7600 also includes a power storage unit 7635 inside the housing 7630a and the housing 7630b. The power storage unit 7635 passes through the movable portion 7640 and is provided across the housings 7630a and 7630b.

[0386] All or part of the display portion 7631 can be a touch panel area, and data can be input by touching images including icons, characters, input forms, etc. displayed in the area. For example, keyboard buttons may be displayed on the entire surface of the display portion 7631a on the housing 7630a side, and information such as characters and images may be displayed on the display portion 7631b on the housing 7630b side.

[0387] A keyboard may be displayed on the display portion 7631b of the housing 7630b, and information such as text and images may be displayed on the display portion 7631a of the housing 7630a. A keyboard display switch button of a touch panel may be displayed on the display portion 7631, and the keyboard may be displayed on the display portion 7631 by touching the button with a finger or a stylus.

[0388] In addition, touch input can be simultaneously performed on the touch panel area of ​​the display portion 7631a on the housing 7630a side and the touch panel area of ​​the display portion 7631b on the housing 7630b side.

[0389] The switches 7625 to 7627 may be interfaces capable of switching various functions in addition to interfaces for operating the tablet terminal 7600. For example, at least one of the switches 7625 to 7627 may function as a switch for turning on and off the power of the tablet terminal 7600. For example, at least one of the switches 7625 to 7627 may have a function for switching the display orientation, such as portrait or landscape, or a function for switching between black and white and color display. For example, at least one of the switches 7625 to 7627 may have a function for adjusting the brightness of the display unit 7631. The brightness of the display unit 7631 can be optimized depending on the amount of external light detected by an optical sensor built into the tablet terminal 7600 during use. Note that the tablet terminal may have built-in not only an optical sensor but also other detection devices, such as a gyroscope, an acceleration sensor, or other sensors for detecting tilt.

[0390] 26A shows an example in which the display areas of the display portion 7631a on the housing 7630a and the display portion 7631b on the housing 7630b are substantially the same, the display areas of the display portion 7631a and the display portion 7631b are not particularly limited, and the sizes of one and the other may be different, and the display qualities may also be different. For example, one display panel may be capable of displaying at a higher resolution than the other.

[0391] 26B shows a tablet terminal 7600 folded in half, and the tablet terminal 7600 includes a housing 7630, a solar cell 7633, and a charge / discharge control circuit 7634 including a DC-DC converter 7636. The power storage unit 7635 is a secondary battery according to one embodiment of the present invention.

[0392] As described above, the tablet terminal 7600 can be folded in half, and thus can be folded so that the housing 7630a and the housing 7630b overlap each other when not in use. By folding, the display portion 7631 can be protected, thereby improving the durability of the tablet terminal 7600. Furthermore, the power storage unit 7635 using the secondary battery of one embodiment of the present invention has a high capacity and favorable cycle characteristics, and therefore, the tablet terminal 7600 can be used for a long period of time. To improve safety, it is preferable to electrically connect the control system of one embodiment of the present invention to the secondary battery included in the power storage unit 7635. The control system may also include a charge / discharge control circuit 7634. ​​The use of the control system of one embodiment of the present invention can increase the energy density that can be used in the secondary battery. Furthermore, the use of the control system of one embodiment of the present invention can extend the life of the secondary battery. The control system includes the measurement circuit described in the above embodiment.

[0393] In addition, the tablet terminal 7600 shown in Figures 26A and 26B can have functions such as displaying various information (still images, videos, text images, etc.), displaying a calendar, date and time, etc. on the display unit, a touch input function for touch input operations or editing information displayed on the display unit, and controlling processing using various software (programs).

[0394] A solar cell 7633 attached to the surface of the tablet terminal 7600 can supply power to a touch panel, a display unit, a video signal processor, or the like. The solar cell 7633 can be provided on one or both surfaces of the housing 7630, and can be configured to efficiently charge the power storage unit 7635. Note that using a lithium-ion battery as the power storage unit 7635 has advantages such as miniaturization.

[0395] 26C shows a block diagram of a configuration and an example of operation of the charge / discharge control circuit 7634 shown in Fig. 26B. Fig. 26C shows a solar cell 7633, a power storage unit 7635, a DC-DC converter 7636, a converter 7637, switches SW1 to SW3, and a display unit 7631. The power storage unit 7635, the DC-DC converter 7636, the converter 7637, and switches SW1 to SW3 correspond to the charge / discharge control circuit 7634 shown in Fig. 26B.

[0396] First, an example of operation when power is generated by the solar cell 7633 using external light will be described. The power generated by the solar cell is stepped up or down by a DC-DC converter 7636 to a voltage for charging a power storage unit 7635. When power from the solar cell 7633 is used to operate the display unit 7631, a switch SW1 is turned on, and the converter 7637 steps up or steps down the voltage to a voltage required for the display unit 7631. When no display is to be performed on the display unit 7631, the switch SW1 may be turned off and the switch SW2 may be turned on to charge the power storage unit 7635.

[0397] Note that the solar cell 7633 is shown as an example of a power generating means, but is not particularly limited thereto, and the power storage unit 7635 may be charged by other power generating means such as a piezoelectric element (piezo element) or a thermoelectric conversion element (Peltier element). For example, a contactless power transmission module that transmits and receives power wirelessly (contactlessly) for charging, or a combination of other charging means may be used.

[0398] FIG. 27 illustrates an example of another electronic device. A control circuit according to one embodiment of the present invention is preferably electrically connected to a secondary battery included in the electronic device illustrated in FIG. 27 . In FIG. 27 , a display device 8000 is an example of an electronic device using a secondary battery 8004 according to one embodiment of the present invention. Specifically, the display device 8000 corresponds to a display device for receiving TV broadcasts and includes a housing 8001, a display portion 8002, a speaker portion 8003, a secondary battery 8004, and the like. To enhance safety, a protection circuit for preventing overcharging and / or overdischarging of the secondary battery 8004 may be electrically connected to the secondary battery 8004. The secondary battery 8004 according to one embodiment of the present invention is provided inside the housing 8001. The display device 8000 can receive power from a commercial power source or can use power stored in the secondary battery 8004. Therefore, even when power cannot be supplied from the commercial power source due to a power outage or the like, the display device 8000 can be used by using the secondary battery 8004 according to one embodiment of the present invention as an uninterruptible power source.

[0399] The display unit 8002 can be a liquid crystal display device, a light-emitting device having a light-emitting element such as an organic EL element in each pixel, an electrophoretic display device, a semiconductor display device such as a DMD (Digital Micromirror Device), a PDP (Plasma Display Panel), or an FED (Field Emission Display).

[0400] The display device includes all display devices for displaying information, such as those for receiving TV broadcasts, those for personal computers, and those for displaying advertisements.

[0401] 27 , a stationary lighting device 8100 is an example of an electronic device using a secondary battery 8103 according to one embodiment of the present invention. Specifically, the lighting device 8100 includes a housing 8101, a light source 8102, a secondary battery 8103, and the like. To improve safety, a protection circuit that prevents overcharging and / or overdischarging of the secondary battery 8103 may be electrically connected to the secondary battery 8103. Although FIG. 27 illustrates the case where the secondary battery 8103 is provided inside a ceiling 8104 on which the housing 8101 and the light source 8102 are installed, the secondary battery 8103 may also be provided inside the housing 8101. The lighting device 8100 can receive power from a commercial power source or can use power stored in the secondary battery 8103. Therefore, even when power cannot be supplied from the commercial power source due to a power outage or the like, the lighting device 8100 can be used by using the secondary battery 8103 according to one embodiment of the present invention as an uninterruptible power supply.

[0402] Note that although Figure 27 illustrates an example of a stationary lighting device 8100 provided on the ceiling 8104, the secondary battery of one embodiment of the present invention can also be used in a stationary lighting device provided in places other than the ceiling 8104, such as a side wall 8105, a floor 8106, or a window 8107, or can also be used in a tabletop lighting device.

[0403] Furthermore, an artificial light source that artificially obtains light using electric power can be used as the light source 8102. Specifically, examples of the artificial light source include a discharge lamp such as an incandescent lamp or a fluorescent lamp, an LED, and / or an organic EL element.

[0404] In FIG. 27 , an air conditioner including an indoor unit 8200 and an outdoor unit 8204 is an example of an electronic device using a secondary battery 8203 according to one embodiment of the present invention. Specifically, the indoor unit 8200 includes a housing 8201, an air outlet 8202, a secondary battery 8203, and the like. To improve safety, a protection circuit that prevents overcharging and / or overdischarging of the secondary battery 8203 may be electrically connected to the secondary battery 8203. Although FIG. 27 illustrates the case where the secondary battery 8203 is provided in the indoor unit 8200, the secondary battery 8203 may also be provided in the outdoor unit 8204. Alternatively, the secondary battery 8203 may be provided in both the indoor unit 8200 and the outdoor unit 8204. The air conditioner can receive power from a commercial power source or can use power stored in the secondary battery 8203. In particular, when the secondary battery 8203 is provided in both the indoor unit 8200 and the outdoor unit 8204, the air conditioner can be used by using the secondary battery 8203 of one embodiment of the present invention as an uninterruptible power supply even when power cannot be supplied from a commercial power source due to a power outage or the like.

[0405] Note that although FIG. 27 illustrates an example of a separate-type air conditioner including an indoor unit and an outdoor unit, a secondary battery according to one embodiment of the present invention can also be used in an integrated-type air conditioner that has the functions of both the indoor unit and the outdoor unit in a single housing.

[0406] 27 , an electric refrigerator-freezer 8300 is an example of an electronic device using a secondary battery 8304 according to one embodiment of the present invention. Specifically, the electric refrigerator-freezer 8300 includes a housing 8301, a refrigerator door 8302, a freezer door 8303, a secondary battery 8304, and the like. To improve safety, a protection circuit that prevents overcharging and / or overdischarging of the secondary battery 8304 may be electrically connected to the secondary battery 8304. In FIG. 27 , the secondary battery 8304 is provided inside the housing 8301. The electric refrigerator-freezer 8300 can receive power from a commercial power source or can use power stored in the secondary battery 8304. Therefore, even when power cannot be supplied from the commercial power source due to a power outage or the like, the electric refrigerator-freezer 8300 can be used by using the secondary battery 8304 according to one embodiment of the present invention as an uninterruptible power source.

[0407] Among the electronic devices described above, electronic devices such as microwave ovens and other high-frequency heating devices and electric rice cookers require a large amount of power for a short period of time. Therefore, by using a secondary battery according to one embodiment of the present invention as an auxiliary power source for supplementing the power that cannot be supplied by the commercial power source, it is possible to prevent the breaker of the commercial power source from tripping when the electronic device is in use.

[0408] Furthermore, by storing power in the secondary battery during time periods when electronic devices are not in use, particularly during time periods when the ratio of the amount of power actually used to the total amount of power that can be supplied by the commercial power supplier (referred to as the power usage rate) is low, it is possible to prevent the power usage rate from increasing outside of these time periods. For example, in the case of electric refrigerator-freezer 8300, power is stored in secondary battery 8304 during the night when the temperature is low and refrigerator door 8302 and freezer door 8303 are not opened or closed. Then, during the daytime when the temperature rises and refrigerator door 8302 and freezer door 8303 are opened and closed, secondary battery 8304 is used as an auxiliary power source, thereby making it possible to keep the daytime power usage rate low.

[0409] According to one embodiment of the present invention, the cycle characteristics of the secondary battery can be improved, and the reliability can be improved. Furthermore, according to one embodiment of the present invention, a high-capacity secondary battery can be obtained, and therefore the characteristics of the secondary battery can be improved, and therefore the secondary battery itself can be made smaller and lighter. Therefore, by incorporating the secondary battery according to one embodiment of the present invention in the electronic device described in this embodiment, the electronic device can have a longer life and be lighter.

[0410] Figure 28A shows an example of a wearable device. The wearable device uses a secondary battery as a power source. Furthermore, in order to improve splash-proof, water-resistant, or dust-proof performance when used at home or outdoors, there is a demand for a wearable device that can be charged wirelessly as well as via a wired connection with an exposed connector.

[0411] For example, a secondary battery according to one embodiment of the present invention can be mounted on an eyeglasses-type device 9000 as shown in FIG. 28A . The eyeglasses-type device 9000 includes a frame 9000a and a display portion 9000b. Mounting a secondary battery on temple portions of the curved frame 9000a makes it possible to provide an eyeglasses-type device 9000 that is lightweight, has a good weight balance, and can be used for a long time. The control circuit according to one embodiment of the present invention is preferably electrically connected to the secondary battery. By including a secondary battery according to one embodiment of the present invention, a space-saving configuration can be realized that accompanies a miniaturized housing.

[0412] Furthermore, the secondary battery according to one embodiment of the present invention can be mounted on a headset-type device 9001. The headset-type device 9001 includes at least a microphone unit 9001a, a flexible pipe 9001b, and an earphone unit 9001c. The secondary battery can be provided in the flexible pipe 9001b or the earphone unit 9001c. To enhance safety, a protection circuit that prevents overcharging and / or overdischarging of the secondary battery may be electrically connected to the secondary battery. By including the secondary battery according to one embodiment of the present invention, a configuration that can accommodate space savings due to a smaller housing can be realized.

[0413] Furthermore, a secondary battery according to one embodiment of the present invention can be mounted on a device 9002 that can be directly attached to the body. A secondary battery 9002b can be provided in a thin housing 9002a of the device 9002. To improve safety, a protection circuit that prevents overcharging and / or overdischarging of the secondary battery 9002b may be electrically connected to the secondary battery 9002b. By including a secondary battery according to one embodiment of the present invention, a configuration that can accommodate space savings due to a smaller housing can be realized.

[0414] Furthermore, a secondary battery according to one embodiment of the present invention can be mounted on a device 9003 that can be attached to clothing. A secondary battery 9003b can be provided in a thin housing 9003a of the device 9003. To improve safety, a protection circuit that prevents overcharging and / or overdischarging of the secondary battery 9003b may be electrically connected to the secondary battery 9003b. By including the secondary battery according to one embodiment of the present invention, a configuration that can accommodate space savings due to a smaller housing can be realized.

[0415] Furthermore, the secondary battery according to one embodiment of the present invention can be mounted on a belt-type device 9006. The belt-type device 9006 has a belt portion 9006a and a wireless power receiving portion 9006b, and the secondary battery can be mounted inside the belt portion 9006a. To improve safety, a protection circuit that prevents overcharging and / or overdischarging of the secondary battery may be electrically connected to the secondary battery. By including the secondary battery according to one embodiment of the present invention, a configuration that can accommodate space savings due to a smaller housing can be realized.

[0416] Furthermore, the secondary battery of one embodiment of the present invention can be mounted on a wristwatch device 9005. The wristwatch device 9005 has a display portion 9005a and a belt portion 9005b, and the secondary battery can be provided on the display portion 9005a or the belt portion 9005b. To improve safety, a protection circuit that prevents overcharging and / or overdischarging of the secondary battery may be electrically connected to the secondary battery. By providing the secondary battery of one embodiment of the present invention, a space-saving configuration can be realized that accompanies a miniaturized housing.

[0417] The display unit 9005a can display not only the time but also various other information such as incoming emails and / or phone calls.

[0418] Furthermore, since the wristwatch type device 9005 is a wearable device that is worn directly on the wrist, it may be equipped with sensors that measure the user's pulse, blood pressure, etc. Data on the user's exercise amount and health can be accumulated to manage the user's health.

[0419] FIG. 28B shows a perspective view of the wristwatch type device 9005 removed from the wrist.

[0420] 28C shows a side view of the wristwatch-type device 9005. FIG. 28C shows a state in which a secondary battery 913 according to one embodiment of the present invention is built inside the wristwatch-type device. The secondary battery 913 is provided so as to overlap with the display portion 9005a, and is small and lightweight. The control circuit according to one embodiment of the present invention is preferably electrically connected to the secondary battery.

[0421] 29A illustrates an example of a cleaning robot. The cleaning robot 9300 includes a display portion 9302 arranged on the top surface of a housing 9301, a plurality of cameras 9303 arranged on the side surface, a brush 9304, an operation button 9305, a secondary battery 9306, various sensors, and the like. The control circuit of one embodiment of the present invention is preferably electrically connected to the secondary battery 9306. Although not shown, the cleaning robot 9300 also includes tires, a suction port, and the like. The cleaning robot 9300 can move by itself, detect dust 9310, and suck the dust through a suction port provided on the bottom surface.

[0422] For example, the cleaning robot 9300 can analyze an image captured by the camera 9303 to determine whether or not there is an obstacle such as a wall, furniture, or a step. Furthermore, if an object that may become entangled in the brush 9304, such as a wire, is detected through image analysis, the cleaning robot 9300 can stop the rotation of the brush 9304. The cleaning robot 9300 includes a secondary battery 9306 according to one embodiment of the present invention and a semiconductor device or an electronic component. By using the secondary battery 9306 according to one embodiment of the present invention in the cleaning robot 9300, the cleaning robot 9300 can be a highly reliable electronic device with a long operating time.

[0423] 29B shows an example of a robot. The robot 9400 shown in FIG. 29B includes a secondary battery 9409, an illuminance sensor 9401, a microphone 9402, an upper camera 9403, a speaker 9404, a display unit 9405, a lower camera 9406, an obstacle sensor 9407, a moving mechanism 9408, a computing device, and the like. The secondary battery 9409 is preferably electrically connected to a control circuit of one embodiment of the present invention.

[0424] The microphone 9402 has a function of detecting the user's voice, environmental sounds, etc. The speaker 9404 has a function of emitting sound. The robot 9400 can communicate with the user using the microphone 9402 and the speaker 9404.

[0425] The display unit 9405 has a function of displaying various types of information. The robot 9400 can display information desired by the user on the display unit 9405. The display unit 9405 may be equipped with a touch panel. The display unit 9405 may also be a detachable information terminal, which can be installed in a fixed position on the robot 9400 to enable charging and data transfer.

[0426] The upper camera 9403 and the lower camera 9406 have the function of capturing images of the surroundings of the robot 9400. In addition, the obstacle sensor 9407 can detect the presence or absence of obstacles in the direction of travel when the robot 9400 moves forward using the movement mechanism 9408. The robot 9400 can recognize the surrounding environment and move safely using the upper camera 9403, the lower camera 9406, and the obstacle sensor 9407.

[0427] The robot 9400 includes a secondary battery 9409 according to one embodiment of the present invention and a semiconductor device or an electronic component inside the robot 9400. By using the secondary battery according to one embodiment of the present invention in the robot 9400, the robot 9400 can be a highly reliable electronic device with a long operating time.

[0428] 29C illustrates an example of an aircraft. The aircraft 9500 illustrated in FIG. 29C includes a propeller 9501, a camera 9502, a secondary battery 9503, and the like, and has a function of flying autonomously. The secondary battery 9503 is preferably electrically connected to a control circuit of one embodiment of the present invention.

[0429] For example, image data captured by a camera 9502 is stored in an electronic component 9504. The electronic component 9504 can analyze the image data and detect the presence or absence of an obstacle when moving. The electronic component 9504 can also estimate the remaining battery charge from a change in the storage capacity of the secondary battery 9503. The flying object 9500 includes therein a secondary battery 9503 according to one embodiment of the present invention. By using the secondary battery according to one embodiment of the present invention in the flying object 9500, the flying object 9500 can be an electronic device with a long operating time and high reliability.

[0430] This embodiment mode can be implemented in appropriate combination with other embodiment modes. [Explanation of symbols]

[0431] 100: power storage system, 120: secondary battery, 121: battery cell, 130: laminate, 131: laminate, 400: secondary battery, 401: positive electrode cap, 415: power storage system, 420: control system, 420a: circuit, 420b: circuit, 423: wiring, 424: conductor, 425: insulator, 426: wiring, 500: secondary battery, 501: positive electrode current collector, 502: positive electrode active material layer, 503: positive electrode, 504: negative electrode current collector, 505: negative electrode active material layer, 506: negative electrode, 507: separator, 507a: region, 507b: region, 508: electrolyte, 509: exterior body, 510: positive electrode lead lead electrode, 511: negative lead electrode, 513: secondary battery, 515: seal, 516: inlet, 517: antenna, 519: layer, 521: circuit board, 522: terminal, 531: secondary battery pack, 550: laminate, 551: one side, 552: other side, 560: secondary battery, 581: polymer film, 582: hole, 584: polymer film, 585: hole, 590: control system, 590a: circuit system, 590b: circuit system, 601: positive electrode cap, 602: battery can, 603: positive electrode terminal, 604: positive electrode, 605: separator, 606: negative electrode, 607: negative electrode terminal, 608: insulation plate, 609: insulating plate, 611: PTC element, 613: safety valve mechanism, 700: control system, 701: input protection circuit, 702: charging protection circuit, 703: discharging protection circuit, 704: selection circuit, 705: output control circuit, 706: output protection circuit, 711: potential adjustment circuit, 712: power generation circuit, 713: control circuit, 714: switch section, 721: charging control circuit, 731: input terminal, 732: output terminal, 750: measurement circuit, 750a: circuit, 751: AC signal source, 752: capacitance element, 753: resistance element, 754: inductor, 755: switch, 771: terminal, 77 2: terminal, 781: voltmeter, 782: voltmeter, 786: capacitance element, 911a: terminal, 911b: terminal, 913: secondary battery, 930: housing, 930a: housing, 930b: housing, 931: negative electrode, 931a: negative electrode active material layer, 932: positive electrode, 932a: positive electrode active material layer, 933: separator, 950: wound body, 950a: wound body, 951: terminal, 952: terminal, 970: secondary battery, 971: housing, 972: laminate, 973a: positive electrode lead electrode, 973b: terminal, 973c: conductor, 974a: negative electrode lead electrode, 974b: terminal, 974c: conductor, 975a: positive electrode,975b: positive electrode, 976: separator, 977a: negative electrode, 1301a: first battery, 1301b: first battery, 1302: battery controller, 1303: motor controller, 1304: motor, 1305: gear, 1306: DCDC circuit, 1307: electric power steering, 1308: heater, 1309: defogger, 1310: DCDC circuit, 1311: second battery, 1312: inverter, 1313: audio, 1314: power window, 1315: lamps, 1316: tires, 1317: rear motor, 1320: control system system, 1415: battery pack, 1421: wiring, 1422: wiring, 1700: power storage device, 1701: commercial power supply, 1703: distribution board, 1705: power storage controller, 1706: display, 1707: general load, 1708: power storage load, 1709: router, 1710: lead-in line attachment section, 1711: measurement section, 1712: prediction section, 1713: planning section, 1790: control device, 1791: storage battery, 1796: underfloor space section, 1799: building, 2001: automobile, 2002: transport vehicle, 2003: transport vehicle, 2004: aircraft, 2005: transport vehicle, 2100: electric bicycle, 2 101: Secondary battery, 2102: Power storage device, 2103: Display unit, 2104: Control system, 2201: Battery pack, 2202: Battery pack, 2203: Battery pack, 2204: Battery pack, 2300: Scooter, 2301: Side mirror, 2302: Power storage device, 2303: Turn signal light, 2304: Under-seat storage, 2603: Vehicle, 2604: Charging device, 2610: Solar panel, 2611: Wiring, 2612: Power storage device, 2800: Personal computer, 2801: Housing, 2802: Housing, 2803: Display unit, 2804: Keyboard, 2805: Pointer device, 2806: secondary battery, 2807: secondary battery, 7100: portable display device, 7101: housing, 7102: display unit, 7103: operation button, 7104: secondary battery, 7200: portable information terminal, 7201: housing, 7202: display unit, 7203: band, 7204: buckle, 7205: operation button, 7206: input / output terminal, 7207: icon, 7300: display device, 7304: display unit, 7400: mobile phone, 7401: housing, 7402: display unit, 7403: operation button, 7404: external connection port, 7405: speaker, 7406: microphone,7407: Secondary battery, 7500: Electronic cigarette, 7501: Atomizer, 7502: Cartridge, 7504: Secondary battery, 7600: Tablet terminal, 7625: Switch, 7627: Switch, 7628: Operation switch, 7629: Fastener, 7630: Housing, 7630a: Housing, 7630b: Housing, 7631: Display unit, 7631a: Display unit, 7631b: Display unit, 7633: Solar cell, 7634: Charge / discharge control circuit, 7635: Storage battery, 7636: DCDC converter, 7637: Converter, 764 0: Movable part, 8000: Display device, 8001: Housing, 8002: Display unit, 8003: Speaker unit, 8004: Secondary battery, 8100: Lighting device, 8101: Housing, 8102: Light source, 8103: Secondary battery, 8104: Ceiling, 8105: Side wall, 8106: Floor, 8107: Window, 8200: Indoor unit, 8201: Housing, 8202: Air outlet, 8203: Secondary battery, 8204: Outdoor unit, 8300: Electric refrigerator-freezer, 8301: Housing, 8302: Refrigerator door, 8303: Freezer door, 8304: Secondary battery, 9000: Glasses type Device, 9000a: frame, 9000b: display unit, 9001: headset type device, 9001a: microphone unit, 9001b: flexible pipe, 9001c: earphone unit, 9002: device, 9002a: housing, 9002b: secondary battery, 9003: device, 9003a: housing, 9003b: secondary battery, 9005: watch type device, 9005a: display unit, 9005b: belt unit, 9006: belt type device, 9006a: belt unit, 9006b: wireless power receiving unit, 9300: Cleaning robot, 9301: housing, 9302: display unit, 9303: camera, 9304: brush, 9305: operation button, 9306: secondary battery, 9310: dust, 9400: robot, 9401: illuminance sensor, 9402: microphone, 9403: upper camera, 9404: speaker, 9405: display unit, 9406: lower camera, 9407: obstacle sensor, 9408: movement mechanism, 9409: secondary battery, 9500: flying object, 9501: propeller, 9502: camera, 9503: secondary battery, 9504: electronic component,

Claims

[Claim 1] A secondary battery and a measurement circuit are included, the measurement circuit includes a resistive element, a capacitive element, and an inductor; one terminal of the resistor element is electrically connected to one electrode of the capacitor element; the other terminal of the resistor element is electrically connected to one terminal of the inductor; one terminal of the inductor is electrically connected to the positive electrode of the secondary battery; The measurement circuit has a function of measuring the impedance of the secondary battery by measuring the current of the resistance element.

Images