Control circuit

Abstract

To provide a protection circuit, a control circuit and the like of a secondary battery. To provide a circuit with low power consumption. To provide a highly integrated circuit.SOLUTION: A control circuit includes a first resistance circuit, a second resistance circuit, a comparator, and a storage circuit. One terminal of the first resistance circuit is electrically connected to a positive electrode of the secondary battery, the other terminal of the first resistance circuit is electrically connected to a first input terminal of the comparator and one terminal of the second resistance circuit, and the memory circuit is configured to retain first data. The control circuit has a function of generating a first signal and a second signal by using the first data, a function of adjusting resistance of the first resistance circuit by supplying the first signal to the first resistance circuit, a function of adjusting resistance of the second resistance circuit by supplying the second signal to the second resistance circuit, and a function of stopping one of charging and discharging of the secondary battery in accordance with an output of the comparator.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] TECHNICAL FIELD One embodiment of the present invention relates to a control circuit and the like. In particular, one embodiment of the present invention relates to a control circuit and the like for a secondary battery. Another embodiment of the present invention relates to a protection circuit for a secondary battery.

[0002] Note that one embodiment of the present invention is not limited to the above technical field. Examples of the technical field of one embodiment of the present invention disclosed in this specification and the like include semiconductor devices, imaging devices, display devices, light-emitting devices, power storage devices, memory devices, display systems, electronic devices, lighting devices, input devices, input / output devices, and driving methods thereof or manufacturing methods thereof. Note that a semiconductor device generally refers to a device that utilizes semiconductor characteristics, and a control circuit for a secondary battery is a semiconductor device. [Background technology]

[0003] Secondary batteries (also called batteries or power storage devices) are now used in a wide range of fields, from small electronic devices to automobiles.

[0004] A secondary battery is equipped with a control circuit for managing charging and discharging to prevent abnormalities during charging and discharging, such as over-discharging, over-charging, overcurrent, or short circuit. The control circuit acquires data such as voltage and current to manage the charging and discharging of the secondary battery. The control circuit controls charging and discharging based on the observed data.

[0005] Patent Document 1 discloses a protection monitoring circuit that functions as a control circuit for a secondary battery. The protection monitoring circuit described in Patent Document 1 discloses a configuration in which multiple comparators are provided internally and a reference voltage is compared with the voltage at the terminal to which the secondary battery is connected to detect abnormalities during charging and discharging.

[0006] Furthermore, Patent Document 2 discloses a control device that performs trickle charging to compensate for the decrease in capacity due to natural discharge of a secondary battery. The control device in Patent Document 2 discloses a configuration in which an upper limit voltage and a lower limit voltage are set and control is performed to repeatedly switch between a charging state and a cut-off state within the set voltage range.

[0007] Furthermore, Patent Document 3 discloses a configuration in which a reference voltage is adjusted by adjusting a resistance value in a battery charging circuit in order to accurately control the battery charging current.

[0008] One known method for adjusting resistance is fuse trimming. Patent Document 4 discloses a semiconductor integrated circuit equipped with a fuse element that can be adjusted by laser trimming. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] US Patent Application Publication No. 2011 / 267726 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-175688 [Patent Document 3] Japanese Patent Application Laid-Open No. 2009-55652 [Patent Document 4] Japanese Patent Application Laid-Open No. 2008-198775 Summary of the Invention [Problem to be solved by the invention]

[0010] When fuse trimming is used to adjust the resistance, the circuit area may increase due to the placement of fuse elements for adjustment by laser trimming. Also, if a large current flows through the fuse elements, the power consumption of the circuit may increase.

[0011] An object of one embodiment of the present invention is to provide a novel protection circuit or the like for a secondary battery.An object of one embodiment of the present invention is to provide a novel control circuit or the like for a secondary battery.An object of one embodiment of the present invention is to provide a control circuit or protection circuit or the like for a secondary battery with a novel structure that can reduce power consumption.An object of one embodiment of the present invention is to provide a control circuit or protection circuit or the like for a secondary battery with a novel structure that can be integrated.

[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 extracted as appropriate from these descriptions. One embodiment of the present invention solves at least one of the problems listed above and / or other problems. [Means for solving the problem]

[0013] One embodiment of the present invention is a control circuit having a first resistor circuit, a second resistor circuit, a comparator, and a memory circuit. The comparator has a first input terminal, a second input terminal, and a first output terminal that outputs a comparison result between the first input terminal and the second input terminal. One terminal of the first resistor circuit is electrically connected to a positive electrode of a secondary battery, and the other terminal of the first resistor circuit is electrically connected to the first input terminal and one terminal of the second resistor circuit. The memory circuit has a function of retaining first data. The control circuit has a function of generating a first signal and a second signal using the first data, a function of adjusting the resistance of the first resistor circuit by providing the first signal to the first resistor circuit, a function of adjusting the resistance of the second resistor circuit by providing the second signal to the second resistor circuit, and a function of stopping one of charging and discharging of the secondary battery depending on the output from the first output terminal. The memory circuit is a control circuit having a capacitance element using a ferroelectric layer.

[0014] Furthermore, in the above configuration, it is preferable that the first resistance circuit has a plurality of pairs of one resistance element and one switch, and in each pair of one resistance element and one switch, one switch has a function of varying the current flowing through the resistance element, and the control circuit has a function of controlling the operation of each switch in the plurality of pairs using the first signal.

[0015] In the above configuration, it is preferable that a signal corresponding to an upper limit of the charging voltage or a signal corresponding to a lower limit of the discharging voltage is applied to the second input terminal.

[0016] Furthermore, in the above configuration, it is preferable that the power supply has a third resistor circuit and a second comparator, the second comparator has a third input terminal, a fourth input terminal, and a second output terminal that outputs a comparison result between the third input terminal and the fourth input terminal, the other terminal of the second resistor circuit is electrically connected to the third input terminal and one terminal of the third resistor circuit, and the other terminal of the third resistor circuit is electrically connected to the negative electrode of the secondary battery, and the control circuit has a function of generating a third signal using the first data, a function of adjusting the resistance of the third resistor circuit by providing the third signal to the third resistor circuit, and a function of stopping the other of charging and discharging of the secondary battery depending on the output of the second output terminal.

[0017] In the above configuration, it is preferable that one of the signal corresponding to the upper limit of the charging voltage and the signal corresponding to the lower limit of the discharging voltage is supplied to the second input terminal and the other is supplied to the fourth input terminal.

[0018] Alternatively, one embodiment of the present invention is a control circuit having a first terminal electrically connected to a positive electrode of a secondary battery, a second terminal electrically connected to a negative electrode of the secondary battery, a third terminal electrically connected to a gate of a power transistor that controls an electrical connection between the secondary battery and a charger or a load, a detection unit electrically connected to the first terminal and the second terminal, a control unit electrically connected to the detection unit, and a memory circuit electrically connected to the control unit, wherein the memory circuit has a memory cell having a ferroelectric layer between a pair of electrodes, a transistor electrically connected to the memory cell, and a decoder to which a signal from the memory cell is output, the detection unit has a resistance circuit whose resistance is adjusted based on data stored in the memory circuit, and the control unit has a function of determining that the secondary battery is over-discharged based on a comparison result between a reference potential input from the detection unit and the potential of the first terminal or the potential of the second terminal, and a function of outputting a signal to the third terminal to turn off the power transistor when over-discharge is determined.

[0019] One aspect of the present invention is a control circuit having a first terminal electrically connected to a positive electrode of a secondary battery, a second terminal electrically connected to a negative electrode of the secondary battery, a third terminal electrically connected to a gate of a power transistor that controls the electrical connection between the secondary battery and a charger or a load, a detection unit electrically connected to the first terminal and the second terminal, a control unit electrically connected to the detection unit, and a memory circuit electrically connected to the control unit, wherein the memory circuit has a memory cell having a ferroelectric layer between a pair of electrodes, a transistor electrically connected to the memory cell, and a decoder to which a signal from the memory cell is output, the detection unit has a resistance circuit whose resistance is adjusted based on data stored in the memory circuit, and the control unit has a function of determining that the secondary battery is overcharged based on a comparison result between a reference potential input from the detection unit and the potential of the first terminal or the potential of the second terminal, and a function of outputting a signal to the third terminal to turn off the power transistor when overcharge is determined.

[0020] In one embodiment of the present invention, data is written to the memory circuit in response to a signal supplied from outside the control circuit, and the control circuit has a fourth terminal to which the signal is input from the outside.

[0021] In one embodiment of the present invention, the ferroelectric material of the ferroelectric layer of the memory circuit includes an oxide containing hafnium and zirconium.

[0022] In one embodiment of the present invention, the crystal structure of the ferroelectric material of the ferroelectric layer is orthorhombic.

[0023] In one embodiment of the present invention, a pair of electrodes included in the memory circuit includes titanium nitride.

[0024] In one embodiment of the present invention, the transistor is a Si transistor.

[0025] Another embodiment of the present invention is an electronic device including any one of the above control circuits and a secondary battery. [Effects of the Invention]

[0026] According to one embodiment of the present invention, a novel protection circuit for a secondary battery can be provided. According to another embodiment of the present invention, a novel control circuit for a secondary battery can be provided. According to another embodiment of the present invention, a novel control circuit for a secondary battery, a novel protection circuit for a secondary battery, and the like, which can reduce power consumption, can be provided. According to another embodiment of the present invention, a novel control circuit for a secondary battery, a novel protection circuit for a secondary battery, and the like, which can be integrated, can be provided.

[0027] 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 / or other effects. Therefore, one embodiment of the present invention may not have the effects listed above in some cases. [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a control circuit. [Figure 2] Fig. 2A is a diagram showing a configuration example of a voltage generating unit, Fig. 2B is a diagram showing a configuration example of a bandgap reference circuit, Fig. 2C and Fig. 2D are diagrams showing configuration examples of a resistor circuit. [Figure 3] 3A to 3F are diagrams illustrating an example of the operation of the control circuit. [Figure 4] 4A and 4B are diagrams illustrating configuration examples of a storage circuit. [Figure 5] FIG. 5 is a diagram illustrating an example of the configuration of a power storage system. [Figure 6] Fig. 6A is a diagram illustrating a configuration example of a power storage system, and Fig. 6B is a diagram illustrating a configuration example of a part of the power storage system. [Figure 7] FIG. 7 is a diagram illustrating an example of the operation of the control circuit. [Figure 8] Fig. 8A is a circuit diagram of a memory cell MC, and Fig. 8B is a cross-sectional view of a capacitive element of the memory cell MC. [Figure 9] FIG. 9 is a model diagram illustrating the crystal structure of hafnium oxide. [Figure 10] Fig. 10A is a graph showing the hysteresis characteristics of the ferroelectric layer of the memory cell MC, and Fig. 10B is a diagram showing a method for driving the memory cell MC. [Figure 11]11A and 11B are cross-sectional views of a memory cell MC. [Figure 12] FIG. 12 is a cross-sectional view of a memory cell MC. [Figure 13] FIG. 13 is a diagram illustrating the crystal structure of the positive electrode active material. [Figure 14] FIG. 14 is a diagram illustrating the crystal structure of the positive electrode active material. [Figure 15] FIG. 15 is a diagram illustrating an example of an electronic component. [Figure 16] 16A, 16B, 16C, and 16D are diagrams illustrating an electric device of one embodiment of the present invention. [Figure 17] 17A, 17B, and 17C are diagrams illustrating an electric device of one embodiment of the present invention. [Figure 18] 18A, 18B, and 18C are diagrams illustrating an electric device of one embodiment of the present invention. [Figure 19] 19A and 19B illustrate an electric device according to one embodiment of the present invention. [Figure 20] 20A, 20B, and 20C are diagrams illustrating an electric device of one embodiment of the present invention. [Figure 21] FIG. 21 illustrates an electrical device according to one embodiment of the present invention. [Figure 22] 22A is a diagram illustrating an electric device of one embodiment of the present invention. FIG. 22B is a diagram illustrating an electric device of one embodiment of the present invention. FIG. 22C is a diagram illustrating an electric device of one embodiment of the present invention. FIG. 22D is a diagram illustrating an electric device of one embodiment of the present invention. FIG. 22E is a diagram illustrating an electric device of one embodiment of the present invention. [Figure 23]FIG. 23 shows an example of a system according to an embodiment of the present invention. [Figure 24] 24A to 24C are diagrams illustrating an example of a secondary battery. [Figure 25] 25A to 25E are perspective views showing electronic devices. [Figure 26] 26A and 26B illustrate a power storage system according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0029] 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.

[0030] 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.

[0031] 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.

[0032] In this specification and the like, the term "metal oxide" refers to an oxide of a metal in a broad sense. Metal oxides are classified into oxide insulators, oxide conductors (including transparent oxide conductors), oxide semiconductors (also referred to as "oxide semiconductors" or simply as "OSs"). For example, when a metal oxide is used in an active layer of a transistor, the metal oxide may be referred to as an oxide semiconductor. That is, when a metal oxide can form a channel formation region of a transistor having at least one of an amplifying function, a rectifying function, and a switching function, the metal oxide can be referred to as a metal oxide semiconductor. Furthermore, when the term "OS FET" or "OS transistor" is used, it can be rephrased as a transistor having a metal oxide or an oxide semiconductor.

[0033] (Embodiment 1) In this embodiment, a control circuit of one embodiment of the present invention and a power storage system using the control circuit of one embodiment of the present invention will be described.

[0034] 1 shows a control circuit 191 according to one embodiment of the present invention. The control circuit 191 includes a control unit 121, a voltage generation unit 122, a detection unit 127, a detection unit 128, a memory circuit FE1, a level shifter LS1, and a level shifter LS2.

[0035] The control circuit 191 also has terminals VDDD, VSSS, CO, DO, VM, and TES. By connecting the terminal VDDD to the positive electrode of the secondary battery and the terminal VSSS to the negative electrode of the secondary battery, the control circuit 191 can function as a protection circuit for the secondary battery, and signals corresponding to the state of the secondary battery are output from the terminals CO and DO. The terminal TES can be used as a terminal for inputting a signal to the control unit 121 from outside the control circuit 191.

[0036] The detection unit 127 has a function of detecting overcharging and overdischarging of the secondary battery. The detection unit 127 has a comparator 113_1, a comparator 113_2, a resistance circuit Rs1, a resistance circuit Rs2, a resistance circuit Rs3, and a logic circuit LC1. The resistance circuits Rs1, Rs2, and Rs3 are electrically connected in series and connected in this order between the terminal VDDD and the terminal VSSS.

[0037] A potential obtained by resistively dividing the potential between the terminal VDDD and the terminal VSSS is input to one of the input terminals of the comparator 113_1, and a reference potential Rf_v(1) is input to the other input terminal. In the example shown in Fig. 1, the reference potential Rf_v(1) is input to the non-inverting input terminal of the comparator 113_1, and a potential Vb1, which is the potential between the resistor circuit Rs1 and the resistor circuit Rs2, is input to the inverting input terminal.

[0038] A comparator according to one embodiment of the present invention has a function of comparing a reference potential applied to one of its input terminals with a potential applied to the other of its input terminals and outputting the comparison result to a control unit.

[0039] When the control circuit 191 is made to function as a protection circuit for the secondary battery, if the potential Vb1 exceeds the reference potential Rf_v(1), it is determined that the secondary battery is in an overcharged state, and a signal for cutting off charging is output from the terminal CO via the control unit 121. Alternatively, a signal for changing the charging conditions may be output.

[0040] A potential obtained by resistively dividing the potential between the terminal VDDD and the terminal VSSS is input to one of the input terminals of the comparator 113_2, and a reference potential Rf_v(2) is input to the other input terminal. In the example shown in Fig. 1, a potential Vb2, which is the potential between the resistor circuit Rs2 and the resistor circuit Rs3, is input to the non-inverting input terminal of the comparator 113_2, and the reference potential Rf_v(2) is input to the inverting input terminal.

[0041] When the control circuit 191 is made to function as a protection circuit for the secondary battery, if the potential Vb2 becomes less than the reference potential Rf_v(2), it is determined that the secondary battery is in an over-discharge state, and a signal for cutting off discharge is output from the terminal DO via the control unit 121. Alternatively, a signal for changing the discharge conditions may be output.

[0042] Here, variations in resistance values ​​may occur among the multiple resistor circuits used for resistive division. For example, if the resistor circuit has a thin-film resistor element, variations in film thickness, film quality, etc. may cause variations in resistance values. The variations in the resistance values ​​of the resistor elements cause variations in potentials Vb1 and Vb2.

[0043] Furthermore, the characteristics of the comparator may fluctuate due to fluctuations in the characteristics of the semiconductor elements contained in the comparator. For example, the comparator may use semiconductor elements such as transistors and capacitors. The fluctuations in the characteristics of the comparator may cause a discrepancy between the relationship between the potentials applied to the two input terminals of the comparator and the signal output from the comparator.

[0044] A control circuit according to one embodiment of the present invention can improve the accuracy of the control circuit by adjusting the resistance value of the resistor circuit used for resistive division after undergoing a process for manufacturing the control circuit so as to offset the effects of fluctuations in the resistance value of the resistor circuit and fluctuations in the characteristics of the comparator.

[0045] The control circuit of one embodiment of the present invention can improve the accuracy of voltage detection by the detection unit 127 or the like by adjusting the resistance value of the resistor circuit. The resistance value can be adjusted by supplying an electrical signal to the detection unit. Furthermore, the control circuit of one embodiment of the present invention can store the resistance value adjusted in the detection unit even when power supply to the control circuit is stopped.

[0046] The adjustment of the resistance value of the resistor circuit will be described later.

[0047] The detection unit 128 has comparators 113_3, 113_4, and 113_5. In the configuration example shown in FIG. 1, the detection unit 128 is electrically connected to the terminal VM. By inputting a potential corresponding to the current of the secondary battery to one input terminal of each comparator and inputting a reference potential to the other input terminal, the detection unit 128 can detect a charging overcurrent, a discharging overcurrent, and a short-circuit current of the secondary battery. For example, a reference potential Rf_v(3) corresponding to a charging overcurrent may be input to the comparator 113_3, a reference potential Rf_v(4) corresponding to a discharging overcurrent may be input to the comparator 113_4, and a reference potential Rf_v(5) corresponding to a short-circuit current may be input to the comparator 113_5.

[0048] The voltage generating unit 122 has a function of generating a reference potential Rf_v(x) (x=1, 2, 3, 4, 5), a potential VD1, a potential VD2, a current Ir1, a clock signal CLK, a reset signal RESET, etc. The potentials, currents, and signals generated in the voltage generating unit 122 are provided to circuits and elements included in the control circuit 191. The voltage generating unit 122 will be described in detail with reference to FIG. 2A.

[0049] The control unit 121 has a function of providing signals to the level shifters LS1 and LS2 using signals provided from the detection units 127 and 128. The level shifter LS1 has a function of converting the signal provided from the control unit 121 and providing it to the terminal CO. The level shifter LS2 has a function of converting the signal provided from the control unit 121 and providing it to the terminal DO. The switch SW1 has a function of controlling the electrical connection between the control unit 121 and the terminal DO.

[0050] As will be described later with reference to Fig. 5, it is preferable that the terminals CO and DO are each electrically connected to the gates of the power transistors. It is preferable that the level shifters LS1 and LS2 convert the signals from the control unit 121 to potentials appropriate as gate voltages for driving the power transistors. Here, conversion of a signal refers to, for example, increasing or decreasing the potential of a signal, increasing the amplitude of a signal, etc.

[0051] The control unit 121 also has the function of providing a signal Sn1 to the detection unit 127 to adjust the resistance value of the resistance circuit included in the detection unit 127. Here, "adjustment" refers to, for example, changing the resistance value to a desired value. In the detection unit 127, the signal Sn1 is provided to a logic circuit LC1. The logic circuit LC1 uses the provided signal Sn1 to change the resistance values ​​of the resistance circuits Rs1, Rs2, and Rs3. Note that if changing the resistance values ​​is not necessary, the resistance values ​​do not need to be changed.

[0052] The memory circuit FE1 preferably stores data for generating the signal Sn1. The memory circuit FE1 is preferably nonvolatile. The memory circuit FE1 is also preferably rewritable at a low voltage, for example, 4V or less. Details of the memory circuit FE1 will be described later with reference to FIG. 2B.

[0053] By providing a signal EN to the level shifter LS2, the output from the level shifter LS2 is cut off, the switch SW1 is brought into a conductive state, and a signal from the control unit 121 can be output to the terminal DO. For example, data stored in the memory circuit FE1 can be output from the terminal DO via the control unit 121.

[0054] <Resistance circuit> The resistance circuits Rs1, Rs2, and Rs3 have a configuration in which the resistance value can be adjusted, more specifically, for example, the resistance value can be reduced, by switching the switches between the on state and the off state.

[0055] A resistor circuit according to one embodiment of the present invention includes, for example, a plurality of pairs of one resistor element and one switch. In each pair of one resistor element and one switch, one switch has a function of varying a current flowing through the resistor element. By supplying a signal to each switch and controlling its operation, the resistance of the resistor circuit can be adjusted.

[0056] FIG. 2C shows an example of a configuration that can be used for the resistor circuits Rs1, Rs2, and Rs3. In FIG. 2C, multiple resistor elements (represented as resistor elements R in the figure) are electrically connected in series, and a switch is electrically connected in parallel to each resistor element. The resistor elements represented as resistor elements R in the figure may have the same resistance value or different resistance values. The switch can be opened and closed by an electrical signal. The resistance value of the switch in the off state is significantly lower than the resistance values ​​of the resistor elements electrically connected in parallel. FIG. 2C shows an example in which four or more resistor elements are electrically connected in series, and a switch 99 (switches 99_1, 99_2, 99_3, and 99_4 in FIG. 2C) is electrically connected in parallel to each resistor element R. However, the number of resistor elements electrically connected in series may be less than four or may be five or more.

[0057] When one or more switches 99 are turned on, the resistance value of the resistor circuit decreases compared to when all four switches 99 are turned off.

[0058] The resistor circuit shown in FIG. 2C may be called a resistor ladder circuit or a ladder resistor circuit.

[0059] A transistor, for example, can be used as the switch 99. Figure 2D shows a configuration in which a transistor is used as a specific example of the switch in Figure 2C. By applying a signal to the gate of the transistor, it is possible to control the switching between the on and off states of the switch.

[0060] As described in FIGS. 2C and 2D, the resistance values ​​of the resistor circuits Rs1, Rs2, and Rs3 can be adjusted by applying a signal to the switch of each resistor circuit.

[0061] The logic circuit LC1 has a function of applying a signal to the switch of each resistor circuit based on the signal Sn1.

[0062] As described above, the control circuit according to an embodiment of the present invention can improve the accuracy of voltage detection by adjusting the resistance value of the resistor circuit. Furthermore, since the memory circuit FE1 can store data related to the signal to be applied to the switch of the resistor circuit, the control circuit according to an embodiment of the present invention can store the signal for controlling the resistance value of the resistor circuit even when the power supply to the control circuit is stopped.

[0063] Furthermore, the control circuit of one embodiment of the present invention can change the resistance value to a desired value using an electrical signal. Furthermore, the control circuit of one embodiment of the present invention can increase the accuracy of a potential generated by resistive division. Furthermore, the control circuit of one embodiment of the present invention can set the potential generated by resistive division to a desired value.

[0064] Furthermore, the voltage of a battery that is determined to be in an overcharged state may be changed in accordance with the SOH (State Of Health) of the secondary battery. The SOH is expressed as 100 when the secondary battery is new, and as the secondary battery deteriorates, the SOH is expressed as a value smaller than 100. As the SOH decreases, the voltage of a battery that is determined to be in an overcharged state may be lowered, for example.

[0065] The control circuit of one embodiment of the present invention can change the resistance value using an electrical signal, and therefore can change the determination criteria of the detection units 127 and 128 according to the state of the battery. More specifically, the control circuit can change the threshold values ​​for determining an overcharge voltage, an overdischarge voltage, a charging overcurrent, a discharging overcurrent, and a short-circuit current.

[0066] <Voltage generation section> FIG. 2A shows an example of the configuration of the voltage generating unit 122.

[0067] The voltage generating unit 122 includes a bandgap reference circuit BGR, an oscillator Osc, a power-on reset circuit POR, and a regulator circuit Reg.

[0068] The bandgap reference circuit BGR has a function of generating a potential VD1 and a current Ir1. The potential VD1 is, for example, a constant potential. The current Ir1 is, for example, a constant current.

[0069] The regulator circuit Reg has a function of boosting the potential VD1 to generate the potential VD2.

[0070] The oscillator Osc has a function of generating a clock signal CLK.

[0071] The power-on reset circuit POR has a function of resetting the circuits of the voltage generating unit 122 when power supply to the voltage generating unit 122 starts. In addition, the data stored in the memory circuit FE1 is read, for example, immediately after the reset by the power-on reset circuit POR.

[0072] The voltage generating unit 122 has a function of generating a reference potential Rf_v(x) using the potential VD2. For example, as shown in FIG. 2A, each reference potential can be generated by resistively dividing the potential VD2 using a resistance circuit Rs4(x) and a resistance circuit Rs5(x).

[0073] The resistor circuits Rs4(x) and Rs5(x) may have the resistor circuit configurations shown in Figures 2C and 2D. In that case, the resistance values ​​may be adjusted by sending signals from control unit 121 to the switches of resistor circuits Rs4(x) and Rs5(x).

[0074] 2B shows an example of the configuration of the bandgap reference circuit BGR. The bandgap reference circuit BGR has two resistor elements Ra (Ra1, Ra2), a resistor element Rr, a diode element Di1, a diode element Di2, and an amplifier AMP. The amplifier AMP receives as input a potential Va between the resistor element Ra1 and the diode element Di1, and a potential Vb between the resistor element Ra2 and the resistor element Rr.

[0075] <Memory circuit> 4A and 4B show an example of the configuration of the memory circuit FE1. The memory circuit FE1 stores data for generating signals that control the resistance values ​​of the resistor circuits in the control circuit 191.

[0076] The memory circuit FE1 is preferably a nonvolatile memory. Memories such as FeRAM (Ferroelectric Random Access Memory), NAND flash memory, NOR flash memory, MRAM (Magnetoresistive RAM), PRAM (Phase change RAM), and ReRAM (Resistive RAM) can be used as the memory circuit FE1. FeRAM is sometimes called a ferroelectric memory.

[0077] The power consumption of the memory circuit FE1 can be reduced by lowering the operating voltage of the memory circuit FE1, more specifically, the voltage used for a rewrite operation, for example. When the control circuit of one embodiment of the present invention is used as a protection circuit for a secondary battery, the memory circuit FE1 preferably operates at a voltage equal to or lower than the voltage of the secondary battery. When the memory circuit FE1 operates at a voltage equal to or lower than the voltage of the secondary battery, there is no need to boost the voltage of the secondary battery, and therefore the power consumption required for boosting the voltage in the boost circuit can be reduced. Alternatively, even when the voltage of the secondary battery is boosted, it is preferable to operate at a lower voltage in order to reduce power consumption.

[0078] An FeRAM can be operated at an extremely low voltage, for example, lower than the voltage of a lithium-ion battery. Therefore, it is particularly preferable to use an FeRAM as a memory circuit in one embodiment of the present invention.

[0079] Data can be written to the memory circuit FE1 by applying a signal from the outside using a terminal.

[0080] Here, writing to the storage circuit FE1 can be performed using two signals, the data signal (Din) and the clock signal (CLK), at separate terminals, that is, two terminals.

[0081] Alternatively, writing to the memory circuit FE1 can be performed using only one terminal. Having a large number of terminals in the control circuit 191 not only increases the circuit area but also increases the volume occupied by wiring connected to the terminals, thereby increasing the area and volume occupied by the control circuit 191. Having a large number of terminals may limit the degree of freedom in arranging the control circuit 191 and other circuits. Having a large number of terminals may also limit the degree of freedom in designing the control circuit 191. Therefore, in the control circuit 191 of one embodiment of the present invention, writing to the memory circuit FE1 is preferably performed using only one terminal, in this case, the terminal TES.

[0082] A case will be described in which a data signal (hereinafter referred to as data signal Smem) is applied to terminal TES in control circuit 191 to write data to memory circuit FE1. Data signal Smem is an asynchronous signal that is not synchronized with the signals generated inside control circuit 191. Therefore, for example, a signal that changes at a slower cycle than the cycle of clock signal CLK generated in voltage generating unit 122 is used as data signal Smem. Furthermore, control circuit 191 may have a circuit that synchronizes the data signal applied from terminal TES.

[0083] 3A to 3C show examples of signals input to the terminal TES. In addition to the data signal Smem, the terminal TES is supplied with a data signal for determining whether the mode is test mode or normal mode (hereinafter, signal Smd) and a data signal for determining whether the mode is read mode or write mode (hereinafter, signal Srw).

[0084] The signal Smd will be described with reference to Figures 3A and 3B. Figure 3A shows the signal Smd when the test mode is determined, and Figure 3B shows the signal Smd when the normal mode is determined. As shown in Figure 3B, if the signal remains at L (low potential signal), the normal mode is determined. As shown in Figure 3A, if there is a period when the signal is at H (high potential signal), the test mode is determined.

[0085] In the test mode, adjustments of the resistance circuit and the like are performed.

[0086] In the normal mode, the data stored in the memory circuit FE1 is read out by the control unit 121 and provided to the resistance circuit via the logic circuit LC1. In the normal mode, for example, the secondary battery is electrically connected to the control circuit to monitor and protect the secondary battery.

[0087] In the test mode, the period W1 during which the signal is H and the period W2 during which the signal is L are preferably 16 times or more the period of the clock signal generated by the voltage generating section 122.

[0088] The signal Srw will be described using Figures 3C and 3D. Figure 3C shows the signal Srw when the write mode is determined, and Figure 3D shows the signal Srw when the read mode is determined. The write mode and read mode differ in the length of the period during which the signal is low. For the signal indicating the write mode, the period W3 during which the signal is high is preferably four or more times the cycle of the clock signal, and the period W4 during which the signal is low is preferably four to sixteen times the cycle of the clock signal. For the signal indicating the read mode, the period W5 during which the signal is high is preferably four or more times the cycle of the clock signal, and the period W6 during which the signal is low is preferably 20 to 32 times the cycle of the clock signal.

[0089] The data signal Smem will be explained using Figures 3E and 3F. The data signal Smem is composed of a binary signal. Figure 3E shows the signal indicating a signal "1", and Figure 3F shows the signal indicating a signal "0". The signal indicating a signal "1" and the signal indicating a signal "0" have different lengths of time during which the signal is low. For the signal indicating a signal "1", the period W3 during which the signal is high is preferably four or more times the cycle of the clock signal, and the period W4 during which the signal is low is preferably four to 16 times the cycle of the clock signal. For the signal indicating a signal "0", the period W5 during which the signal is high is preferably four or more times the cycle of the clock signal, and the period W6 during which the signal is low is preferably 20 to 32 times the cycle of the clock signal.

[0090] The data signal Smem is converted in the control unit 121 into a format to be applied to the memory circuit FE1, and then applied to the memory circuit FE1.

[0091] The data stored in the storage circuit FE1 can be read out from the terminal DO.

[0092] By applying a signal EN to the level shifter LS2, stopping the output of the level shifter LS2, and turning on the switch SW1, the data stored in the memory circuit FE1 can be output to the terminal DO. If data is not written correctly to the memory circuit FE1, processing can be performed such as changing the write conditions or replacing the bits in the memory circuit FE1 that are not written correctly with redundant bits. A write-prohibited bit can also be set. By performing such processing or setting, the yield of the memory circuit FE1 can be improved. Furthermore, the reliability of the memory circuit FE1 can be increased.

[0093] <Example of memory circuit configuration> FIG. 4A illustrates a configuration example of a memory circuit of one embodiment of the present invention.

[0094] The memory circuit FE1 shown in FIG. 4A includes a memory cell array MEM_AR and a sense amplifier SA.

[0095] Data (Din) is provided to the memory circuit FE1 from the control unit 121. The provided data is stored in the memory cell array MEM_AR.

[0096] The reading of data stored in the memory cell array MEM_AR will be described below. The stored data is amplified by the sense amplifier SA and output to the control unit 121 (Dout).

[0097] Each memory cell in the memory cell array MEM_AR can be, for example, a memory cell consisting of one transistor and one capacitive element (1T1C type memory cell), and by using a ferroelectric layer as the dielectric layer of the capacitive element, the memory circuit FE1 can function as an FeRAM.

[0098] <Energy storage system> FIG. 5 shows an example of a power storage system 190 using the above-described control circuit 191.

[0099] The power storage system 190 has a secondary battery 192, a control circuit 191, a load 193, a charger 140, and power transistors 150A and 150B. Fig. 5 also shows a switch 131 for passing current to the load 193 when the secondary battery 192 is discharged, and a switch 141 for passing current from the charger 140 to charge the secondary battery 192. Fig. 5 also shows terminals on the positive side of the load 193 and the charger 140 as VDDD and terminals on the negative side as VSSS. The control circuit 191 can function as a protection circuit for the secondary battery.

[0100] A terminal CO of the control circuit 191 is electrically connected to the gate of the power transistor 150A, and a terminal DO is electrically connected to the gate of the power transistor 150B.

[0101] The power transistor 150A and the power transistor 150B are electrically connected in series. The power transistor 150A and the power transistor 150B have parasitic diodes.

[0102] The power transistor 150A and the power transistor 150B have the function of cutting off the current between the terminal VSSS and the charger 140, and between the terminal VSSS and the load 193. The control circuit 191 has the function of monitoring the secondary battery 192, and controlling the on or off state of the gates of the power transistor 150A and the power transistor 150B according to the state of the secondary battery 192, thereby protecting the secondary battery 192.

[0103] A resistor Rs is provided between the terminal VM and the terminal VSSS. The current distributed by the resistor Rs is supplied to the terminal VM of the control circuit 191.

[0104] FIG. 6A shows an example of a power storage system 190 including a battery pack 111 using multiple secondary batteries 192. FIG. 6B shows an example of a detection unit 127 that can be used in the configuration of FIG. 6A and a secondary battery 192 electrically connected to the detection unit 127. In FIG. 6B, resistor circuits Rs1 to Rs3 may be used to shut off charging or discharging of the secondary battery 192. For example, the multiple secondary batteries 192 may take different amounts of time to fully charge. For example, among multiple secondary batteries 192, charging of a second secondary battery may be completed even when charging of a first secondary battery is not yet completed. In such a case, the resistance of a resistor circuit electrically connected in parallel to the second secondary battery may be adjusted to limit the charging current flowing to the second secondary battery. This allows the charging and discharging of each secondary battery to be individually controlled, suppressing deterioration of each secondary battery and extending its lifespan.

[0105] <Adjusting the resistance value of the resistor circuit> An example of a method for adjusting the resistance value of a resistor circuit in a control circuit of one embodiment of the present invention is described with reference to a flow chart in FIG.

[0106] First, in step S000, the process starts.

[0107] Next, in step S001, a potential is applied to each of the terminals VDDD and VSSS. It is preferable that a variable potential is applied to the terminal VDDD. A variable potential or a constant potential may be applied to the terminal VSSS. For example, a voltage source capable of sweeping (scanning) voltage is electrically connected to the terminal VDDD, and a ground potential is applied to the terminal VSSS. Here, the voltage applied to the terminal VDDD is set to voltage Vswp, and the voltage applied to the terminal VSSS is set to voltage V0. Here, when verifying the operation of the comparator 113_1, for example, the potential difference between voltage Vswp and voltage V0 in step S001 is set to a value lower than the upper limit voltage of the secondary battery, and when verifying the operation of the comparator 113_2, for example, the potential difference between voltage Vswp and voltage V0 in step S001 is set to a value higher than the lower limit voltage of the secondary battery.

[0108] Next, in step S002, the value of the voltage Vswp is swept. For example, when verifying the operation of the comparator 113_1, the value of the voltage Vswp is swept upward, and when verifying the operation of the comparator 113_2, the value of the voltage Vswp is swept downward.

[0109] Next, in step S003, the comparator that performs the verification (comparator 113_1 or comparator 113_2) performs detection. When the comparator performs detection, it outputs a detection signal to the control unit 121. In the case of the comparator 113_1, when the voltage Vb1 exceeds the reference potential Rf_v(1), the signal that is output to the control unit 121 switches from one of the high potential signal H and the low potential signal L to the other. In the case of the comparator 113_2, when the voltage Vb2 becomes less than the reference potential Rf_v(2), the signal that is output to the control unit 121 switches from one of the high potential signal H and the low potential signal L to the other.

[0110] When the signal output from the verification comparator to the control unit 121 is switched, the control unit 121 determines that an abnormal event has occurred. Specifically, when the output from the comparator 113_1 is switched, it is determined that overcharging has occurred, and when the output from the comparator 113_2 is switched, it is determined that overdischarge has occurred. When the control unit 121 determines that overcharging has occurred, it applies a signal to the terminal CO via the level shifter LS1 to turn off the power transistor 150A. When it determines that overdischarge has occurred, it applies a signal to the terminal DO via the level shifter LS2 to turn off the power transistor 150B.

[0111] However, in an actual control circuit, due to variations in the resistance values ​​of the resistor elements used in the resistor circuit and variations in the semiconductor elements used in the comparator, the output signal of the comparator used for verification may switch at a voltage that deviates from the voltage assumed in the design.

[0112] In step S004, the voltage deviation is verified.

[0113] In step S005, if the result of the verification in step S004 shows that the voltage when the comparator performed the detection operation in step S003 exceeds the voltage range assumed in the design, the process proceeds to step S006, and if no deviation is found, the process proceeds to step S999, where the process ends.

[0114] In step S006, the adjustment amounts of the resistance values ​​of the resistor circuits are calculated. Specifically, the adjustment amounts of the resistance values ​​of the resistor circuits Rs1 to Rs3 to eliminate the voltage deviation are calculated based on the voltage deviation. Based on the calculated adjustment amounts, the signals (data signals Smem) to be provided to the switches of the resistor circuits Rs1 to Rs3 are determined.

[0115] Next, in step S007, writing to the memory circuit FE1 is performed. Writing to the memory circuit FE1 can be performed by providing a data signal Smem from the terminal TES to the control unit 121, and providing a signal based on the data signal Smem from the control unit 121 to the memory circuit FE1 (Din). The data signal Smem relates to a signal provided to each switch of the resistance circuits Rs1 to Rs3.

[0116] Here, the data in the memory circuit FE1 may be read. The data in the memory circuit FE1 can be read using the terminal DO. By reading the data in this manner, it can be confirmed whether the data was correctly written to the memory circuit FE1 in step S007.

[0117] Next, in step S008, the resistance values ​​of the resistor circuits are adjusted. The resistance value is adjusted by sending a signal based on the data signal Smem from the memory circuit FE1 to the control unit 121 (Dout), sending a signal Sn1 from the control unit 121 to the logic circuit LC1, and sending signals from the logic circuit LC1 to the switches of the resistor circuits Rs1 to Rs3 based on the signal Sn1. The control unit 121 receives the signal based on the data signal Smem from the memory circuit FE1 and generates the signal Sn1 using the signal.

[0118] Next, the process returns to step S001.

[0119] Through the above steps, the resistance value of the resistor circuit can be adjusted in the control circuit of one embodiment of the present invention.

[0120] The structure described in this embodiment mode can be combined as appropriate with structures described in other embodiments.

[0121] (Embodiment 2) In this embodiment, a memory circuit of one embodiment of the present invention will be described.

[0122] FIG. 4B shows details of FIG. 4A described in the first embodiment.

[0123] As shown in FIG. 4B, the memory circuit FE1 includes memory cells MC. A plurality of memory cells MC are arranged in an array to form a memory element region MEM_AR. The memory circuit FE1 also includes a driver circuit around the memory element region MEM_AR. The driver circuit, also called a peripheral circuit, can include, for example, row and column circuits. The driver circuit shown in FIG. 4B includes row and column circuits. The row circuit controls the input side of the memory element region MEM_AR, while the column circuit controls the output side of the memory element region MEM_AR. The row circuit includes a level shifter LS3 and a shift register SR. The level shifter LS3 changes the potential level of the signal input to the memory element region MEM_AR. The shift register SR includes multiple flip-flops and other components and shifts the input signal sequentially in synchronization with a clock signal (CLK). If necessary, the internal circuit is initialized by a reset signal RESET. The signal (Din) output from the control circuit 191 is shifted sequentially through the shift register SR, and the signal, whose potential level is changed by the level shifter LS3, is input to the memory element region MEM_AR. Such a row circuit allows signals to be written sequentially to the memory cells MC of the memory element region MEM_AR. Therefore, address signals and the like do not need to be input. If there is no address signal input, the row circuit does not become complicated, which is preferable. If you want to input a signal to any memory cell MC of the memory element region MEM_AR, an address signal is required.

[0124] As shown in FIG. 4B, the column circuit includes a sense amplifier circuit SA, a decoder SR-MUX, etc. The sense amplifier SA has the function of amplifying the voltage of the output signal from the memory element region MEM_AR. The output signal can be amplified to a voltage suitable for the circuit to which the output signal from the memory element region MEM_AR is applied. A differential sense amplifier or a latch-type sense amplifier can be applied to the sense amplifier SA. The decoder SR-MUX has the function of outputting each memory data amplified by the sense amplifier SA to a control circuit 191 in sequence. A signal (Dout) from the decoder SR-MUX is input to the control circuit 191.

[0125] Next, the memory cell MC of the memory circuit FE1 will be described. FIG. 8A shows a circuit diagram of the memory cell MC. The memory cell MC is a 1T1C type memory cell, and has a transistor 11 that functions as a switching element and a capacitance element 10. Since the 1T1C type memory cell has a small number of elements, the memory cells MC can be arranged at a high density, and the storage capacity can be increased. Of course, the memory cell MC may have other elements.

[0126] The gate of the transistor 11 is electrically connected to the wiring WL. The wiring WL functions as a word line, and the transistor 11 can be turned on and off by controlling the potential of the wiring WL. For example, the transistor 11 can be turned on by setting the potential of the wiring WL to a high potential (H), and the transistor 11 can be turned off by setting the potential of the wiring WL to a low potential (L). The wiring WL is electrically connected to a drive circuit. Specifically, for example, the wiring WL is electrically connected to the level shifter LS3 shown in FIG. 4B. The wirings WL are sequentially selected by the function of the level shifter LS3, and the transistor 11 is controlled to be turned on and off.

[0127] One of the source and drain of the transistor 11 is electrically connected to a wiring BL. The wiring BL functions as a bit line, and when the transistor 11 is on, a potential corresponding to the potential of the wiring BL is supplied to one electrode of the capacitor 10. The wiring BL is electrically connected to a sense amplifier SA shown in FIG. 4B, and data output from the memory cell MC can be read via the sense amplifier SA.

[0128] The other electrode of the capacitor 10 is electrically connected to a wiring PL. The wiring PL functions as a plate line, and the potential of the wiring PL can be set to the potential of the other electrode of the capacitor 10. When the potential of the wiring BL becomes a constant value, a voltage can be applied to the wiring PL, and data can be read out.

[0129] It is preferable to use a Si transistor as the transistor 11. Cross-sectional views of a memory cell using a Si transistor will be described later with reference to FIGS.

[0130] An OS transistor may be used as the transistor 11. An OS transistor is a transistor that uses a metal oxide in a semiconductor layer, and the metal oxide may be called an oxide semiconductor (also referred to simply as an OS).

[0131] An OS transistor has a characteristic of being highly voltage-resistant. Therefore, by using an OS transistor as the transistor 11, a high voltage can be applied to the transistor 11 even when the transistor 11 is miniaturized. Miniaturizing the transistor 11 is preferable because it can reduce the area occupied by the memory cells MC. For example, the area occupied by each memory cell MC can be reduced to 1 / 3 to 1 / 6 of the area occupied by each SRAM cell. Therefore, the memory cells MC can be arranged at a high density, thereby increasing the storage capacity.

[0132] 8B shows a cross-sectional view of the capacitor 10. The capacitor 10 has an insulator 130 between the lower electrode 120a and the upper electrode 120b. The insulator 130 has a ferroelectric material as a dielectric layer. A dielectric layer having a ferroelectric material is sometimes called a ferroelectric layer.

[0133] Ferroelectric materials include hafnium oxide, zirconium oxide, and HfZrO X(X is a real number greater than 0), a material in which an element J1 (element J1 is zirconium (Zr), silicon (Si), aluminum (Al), gadolinium (Gd), yttrium (Y), lanthanum (La), strontium (Sr), or the like) is added to hafnium oxide, and a material in which an element J2 (element J2 is hafnium (Hf), silicon (Si), aluminum (Al), gadolinium (Gd), yttrium (Y), lanthanum (La), strontium (Sr), or the like) is added to zirconium oxide. In other words, the ferroelectric material preferably has an oxide containing hafnium and zirconium.

[0134] Another ferroelectric material is PbTiO X There are piezoelectric ceramics with perovskite structure such as barium strontium titanate (BST), strontium titanate, lead zirconate titanate (PZT), strontium bismuth tantalate (SBT), bismuth ferrite (BFO), and barium titanate.

[0135] Other ferroelectric materials include mixtures or compounds having more than one material selected from the materials listed above.

[0136] The materials listed above may exhibit ferroelectricity or other properties depending on the crystal structure or additives, but are included in the ferroelectric material in this specification etc. In other words, the ferroelectric material includes materials that have ferroelectricity and materials that can have ferroelectricity.

[0137] The insulator 130 may have a single layer structure or a multilayer structure. The insulator 130 having a multilayer structure may have a structure in which materials selected from the materials listed above are stacked in order.

[0138] Next, we will use hafnium oxide as an example to explain its crystal structure and physical properties such as ferroelectricity. Figure 9 is a model diagram illustrating the crystal structure of hafnium oxide (HfO2). Hafnium oxide is known to have a variety of crystal structures, such as cubic (cubic system, space group: Fm-3m), tetragonal (tetragonal system, space group: P42 / nmc), orthorhombic (orthorhombic system, space group: Pbc22), and monoclinic (monoclinic system, space group: P21 / c) crystal structures shown in Figure 9. Hafnium oxide has a high dielectric constant when it is monoclinic, a ferroelectric when it is orthorhombic, and an antiferroelectric when it is tetragonal. Therefore, when used in a ferroelectric layer, it is preferable for hafnium oxide to be orthorhombic.

[0139] Furthermore, the crystal structure of hafnium oxide can undergo phase changes between the crystal structures indicated by the arrows, as shown in Figure 9. Phase changes can occur due to heat treatment, etc.

[0140] Ferroelectricity can also be imparted to hafnium oxide by doping it with additives such as zirconium (Zr), silicon (Si), aluminum (Al), gadolinium (Gd), yttrium (Y), lanthanum (La), or strontium (Sr).

[0141] The control of the crystal structure and the doping with the additives can be used independently or in combination.

[0142] For example, by doping hafnium oxide with zirconium, the monoclinic crystal structure can be changed to an orthorhombic crystal structure. As mentioned above, orthorhombic hafnium oxide exhibits ferroelectric properties and is therefore preferred as a ferroelectric layer. When hafnium oxide is doped with zirconium, it may be composited, and may be called a composite material or mixed crystal of hafnium oxide and zirconium oxide.

[0143] Although this is an example different from the composite material described above, a laminated structure in which hafnium oxide and zirconium oxide are alternately deposited in a 1:1 ratio may be used as a ferroelectric layer. By using the ALD method, the hafnium oxide and zirconium oxide can each be thinned to a thickness of 5 nm to 25 nm, which is preferable because the laminated structure can be 50 nm to 100 nm. If the laminated structure contains at least hafnium oxide with an orthorhombic crystal structure, it can exhibit ferroelectricity and is suitable as a ferroelectric layer.

[0144] Furthermore, the crystalline state of the above-mentioned laminated structure may be amorphous immediately after film formation. Heating can be used to change the amorphous structure to an orthorhombic crystalline structure. Depending on the heating temperature, the orthorhombic crystalline structure may change to a monoclinic crystalline structure. To exhibit ferroelectricity, it is preferable for hafnium oxide to have an orthorhombic crystalline structure rather than a monoclinic crystalline structure, so the heating temperature should be set to 300°C or higher and 500°C or lower.

[0145] The crystal structure of the insulator 130 is not particularly limited as long as it exhibits ferroelectricity. For example, the insulator 130 may have an amorphous structure or may be single crystal. Furthermore, the insulator 130 may have a structure (composite structure) that has both an amorphous structure and the above-mentioned crystalline structure in a single material layer.

[0146] The insulator 130 is a composite material having hafnium oxide and zirconium oxide (HfZrO x When using a composite material containing hafnium oxide and zirconium oxide (HfZrO), it is preferable to form the film using the thermal ALD method. The ALD method is also called atomic layer deposition, and allows control at the atomic level, making it possible to form thin films of 5 nm to 25 nm. The ALD method is also preferable because of its fast film formation speed. x ) has a composition such as Hf:Zr:O=0.5:0.5:2 or Hf:Zr:O=0.25:0.75:2.

[0147] When forming the insulator 130 using the thermal ALD method, it is preferable to use a material that does not contain hydrocarbons (also referred to as Hydro Carbon, HC) as a precursor. If either or both of hydrogen and carbon are contained in the insulator 130, crystallization of the insulator 130 may be inhibited, so a material that does not contain hydrocarbons is preferable. As described above, by using a precursor that does not contain hydrocarbons, the concentration of either or both of hydrogen and carbon in the insulator 130 is reduced, resulting in a highly pure and genuine insulator. For example, a chlorine-based material can be used as a precursor that does not contain hydrocarbons. Note that a material containing hafnium oxide and zirconium oxide (HfZrO x When using HfCl4, one or more selected from HfCl4 and ZrCl4 may be used as the chlorine-based precursor.

[0148] Furthermore, when a large amount of hydrogen and carbon is contained in the insulator 130, a step of removing the hydrogen and carbon may be performed. The step of removing the hydrogen and carbon may be performed by forming a capture layer for the hydrogen and carbon and then heating the layer. This removal step may be called gettering.

[0149] Furthermore, when forming the insulator 130 using a thermal ALD method, HO or O can be used as the oxidizing agent. Note that using O is more preferable than using HO as the oxidizing agent for the thermal ALD method because it can reduce the hydrogen concentration in the film. However, the oxidizing agent for the thermal ALD method is not limited to these. For example, the oxidizing agent for the thermal ALD method may include one or more selected from O, O, NO, NO, HO, and HO.

[0150] As shown in FIG. 8B, the capacitor 10 includes a lower electrode 120a and an upper electrode 120b in addition to the insulator 130. The upper electrode 120b and the lower electrode 120a can be fabricated using the same material and process. The upper electrode 120b and the lower electrode 120a each independently or identically include a metal nitride such as titanium nitride or tantalum nitride. The upper electrode 120b and the lower electrode 120a each independently or identically include a conductive material such as platinum, aluminum, or copper. The upper electrode 120b and the lower electrode 120a each independently or identically include indium oxide, gallium oxide, zinc oxide, tin oxide, indium tin oxide (ITO), or indium zinc oxide (IZO). The upper electrode 120b and the lower electrode 120a each independently or identically include a solid solution containing two or more of the above materials. A stable voltage can be applied to the ferroelectric layer.

[0151] The upper electrode 120b is preferably formed using an ALD method or a CVD method, since it is formed after the insulator 130. For example, the upper electrode 120b may be formed as a titanium nitride film using a thermal ALD method. Here, the upper electrode 120b is preferably formed by a method in which the substrate is heated, as in the thermal ALD method. The lower limit of the substrate temperature may be set to, for example, room temperature or higher, preferably 300°C or higher, more preferably 325°C or higher, and even more preferably 350°C or higher. The upper limit of the substrate temperature may be set to, for example, 500°C or lower, preferably 450°C or lower.

[0152] By forming the upper electrode 120b within the above temperature range, it is possible to impart ferroelectricity to the insulator 130 without performing high-temperature heat treatment (for example, heat treatment at a temperature of 400°C or higher or 500°C or higher) after forming the upper electrode 120b. Furthermore, by forming the upper electrode 120b using the ALD method, which causes relatively little damage to the base, as described above, it is possible to prevent the crystal structure of the insulator 130 from being excessively destroyed, thereby increasing the ferroelectricity of the insulator 130 or maintaining a high level of ferroelectricity.

[0153] When the upper electrode 120b is formed by a sputtering method or the like, there is a possibility that damage may occur in the insulator 130. For example, when the insulator 130 is made of a composite material containing hafnium oxide and zirconium oxide (HfZrO x ) and the upper electrode 120b is formed by sputtering. x Damage occurs to HfZrO x The crystal structure (typically a cubic crystal structure) of HfZrO may be destroyed by heat treatment. x There are also methods to repair the damage to the crystal structure of HfZrO formed by sputtering. x Damage in, e.g., HfZrO x Dangling bonds in (e.g., O * ) and HfZrO x The hydrogen contained in the x In some cases, damage in the crystal structure of the material cannot be repaired.

[0154] Therefore, the insulator 130, here HfZrO x For example, the concentration of hydrogen contained in the insulator 130 is preferably 5×10 20 atoms / cm 3 Less than 1×10 is preferred 20 atoms / cm 3 The following is more preferable: The hydrogen concentration can be measured by secondary ion mass spectrometry (SIMS). The lower limit of the above concentration is the lower detection limit of SIMS.

[0155] As described above, in order to reduce the hydrogen concentration in the insulator 130, it is preferable to use a material that does not contain hydrocarbons as a precursor. This may result in the insulator 130 being a film that does not contain hydrocarbons as a main component or that contains an extremely small amount of hydrocarbons. For example, the concentration of carbon that constitutes the hydrocarbons contained in the insulator 130 is preferably 5×10 20 atoms / cm3 Less than or equal to 1×10 20 atoms / cm 3 The hydrocarbon concentration can be measured by SIMS. The lower limit of the above concentration is the lower detection limit of SIMS.

[0156] Furthermore, when a material that does not contain hydrocarbons is used as a precursor to form the insulator 130, the insulator 130 may be a film that does not contain carbon as a main component or has an extremely low carbon content. For example, the carbon concentration in the insulator 130 is preferably 5×10 20 atoms / cm 3 Less than or equal to 1×10 20 atoms / cm 3 The carbon concentration can be measured by SIMS. The lower limit of the above concentration is the lower limit of detection for SIMS.

[0157] It is preferable to use a material containing extremely low amounts of at least one of hydrogen, hydrocarbon, and carbon for the insulator 130. It is particularly important to minimize the amounts of hydrocarbon and carbon. Hydrocarbons and carbon are heavier molecules or atoms than hydrogen, making them difficult to remove in subsequent processes. Therefore, it is preferable to thoroughly eliminate hydrocarbons and carbon during the deposition of the insulator 130.

[0158] As described above, by using a material for the insulator 130 that does not contain at least hydrogen, hydrocarbons, and carbon, or that has an extremely low content of at least one of hydrogen, hydrocarbons, and carbon, it is possible to improve the crystallinity of the insulator 130 and to provide it with high ferroelectricity.

[0159] By thoroughly eliminating impurities, in this case at least one of hydrogen, hydrocarbon, and carbon, from the film of the insulator 130, a film having high purity and intrinsic ferroelectricity can be formed, and a capacitor element having a film having high purity and intrinsic ferroelectricity can be formed.

[0160] As described above, a ferroelectric layer is formed as the insulator 130 using a thermal ALD method with a hydrocarbon-free precursor (typically a chlorine-based precursor) and an oxidizing agent (typically O3). Then, the upper electrode 120b is formed by deposition, typically at a substrate temperature of 400°C or higher. By setting the substrate temperature at 400°C or higher, heating for crystallizing the insulator 130 after deposition of the upper electrode 120b is not necessary. In other words, the crystallinity or ferroelectricity of the insulator 130 can be improved by utilizing the temperature during deposition of the upper electrode 120b. Note that improving the crystallinity or ferroelectricity of the insulator 130 by utilizing the temperature during deposition of the upper electrode 120b without performing heating after deposition of the upper electrode 120b is sometimes referred to as self-annealing.

[0161] The insulator 130 is preferably formed as a thin film by the above method. The thickness of the insulator 130 is 100 nm or less, preferably 50 nm or less, more preferably 20 nm or less, and even more preferably 10 nm or less. Combining a thinned insulator 130 with a miniaturized transistor 11 improves the integration density of the memory device. Hafnium oxide or a composite material of hafnium oxide and zirconium oxide is preferable because it can retain ferroelectricity even when thinned to a thickness of several nm.

[0162] The ferroelectric material of the insulator 130 has the property that polarization occurs internally when an electric field is applied, and that polarization remains even when the electric field is removed to zero. Therefore, a capacitance element using this material as a dielectric can function as a nonvolatile memory element. A capacitance element using a ferroelectric material is sometimes called a ferroelectric capacitor, and a nonvolatile memory element using a ferroelectric capacitor is sometimes called a Ferroelectric Random Access Memory (FeRAM) or a ferroelectric memory. In other words, the memory cell MC can function as a ferroelectric memory.

[0163] The insulator 130 may have a laminated structure of a ferroelectric layer having a ferroelectric material and a layer of a material with high dielectric strength. Examples of materials with high dielectric strength include silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, silicon oxide doped with fluorine, silicon oxide doped with carbon, silicon oxide doped with carbon and nitrogen, and silicon oxide or resin with vacancies. By laminating such a layer of an insulator with high dielectric strength with the ferroelectric layer, the dielectric strength is improved and the leakage current of the capacitor 10 can be suppressed.

[0164] Next, the lower electrode 120a shown in FIG. 8B will be described. The lower electrode 120a can be formed using the same process and materials as the upper electrode 120b. That is, the lower electrode 120a can be formed by the ALD method. Unlike the upper electrode 120b, the lower electrode 120a is formed before the insulator 130 is formed, so it can also be formed using a sputtering method, a CVD method, or the like in addition to the ALD method. Furthermore, the lower electrode 120a preferably contains titanium nitride.

[0165] The upper electrode 120b may have a single-layer structure or a multi-layer structure of a conductive film. The lower electrode 120a may have a single-layer structure or a multi-layer structure of a conductive film. The upper electrode 120b may have a multi-layer structure of titanium nitride, aluminum, and copper. The lower electrode 120a may have a multi-layer structure of titanium nitride, aluminum, and copper. If the upper electrode 120b or the lower electrode 120a has a multi-layer structure, leakage can be suppressed.

[0166] Next, the hysteresis characteristics of the ferroelectric layer are illustrated in Fig. 10A, where the horizontal axis represents the voltage applied to the ferroelectric layer.

[0167] 10A, the vertical axis indicates the polarization amount of the ferroelectric layer, and a positive value indicates that positive charges are biased toward one electrode side of the capacitance element 10, and negative charges are biased toward the other electrode side of the capacitance element 10. On the other hand, a negative value indicates that positive charges are biased toward the other electrode side of the capacitance element 10, and negative charges are biased toward one electrode side of the capacitance element 10.

[0168] 10A may be the difference between the potential of the other electrode of the capacitor 10 and the potential of one electrode of the capacitor 10. Also, the amount of polarization shown on the vertical axis of the graph in Fig. 10A may be a positive value when positive charges are biased toward the other electrode of the capacitor 10 and negative charges are biased toward one electrode of the capacitor 10, and may be a negative value when positive charges are biased toward one electrode of the capacitor 10 and negative charges are biased toward the other electrode of the capacitor 10.

[0169] 10A, the hysteresis characteristic of the ferroelectric layer can be represented by a curve 51 and a curve 52. The voltages at the intersections of the curves 51 and 52 are defined as VSP and −VSP. It can be said that VSP and −VSP have opposite polarities.

[0170] When a voltage equal to or less than -VSP is applied to the ferroelectric layer and then the voltage applied to the ferroelectric layer is increased, the polarization amount of the ferroelectric layer increases according to curve 51. On the other hand, when a voltage equal to or greater than VSP is applied to the ferroelectric layer and then the voltage applied to the ferroelectric layer is decreased, the polarization amount of the ferroelectric layer decreases according to curve 52. Therefore, VSP and -VSP can be referred to as saturation polarization voltages. Note that, for example, VSP may be referred to as the first saturation polarization voltage, and -VSP may be referred to as the second saturation polarization voltage. Also, although FIG. 10A shows that the absolute values ​​of the first and second saturation polarization voltages are equal, they may be different.

[0171] Here, Vc denotes the voltage applied to the ferroelectric layer when the polarization amount of the ferroelectric layer changes according to curve 51 and is zero. Furthermore, −Vc denotes the voltage applied to the ferroelectric layer when the polarization amount of the ferroelectric layer changes according to curve 52 and is zero. Vc and −Vc can be referred to as coercive voltages. The values ​​of Vc and −Vc can be referred to as values ​​between −VSP and VSP. For example, Vc may be referred to as the first coercive voltage, and −Vc may be referred to as the second coercive voltage. Although FIG. 10A illustrates the absolute values ​​of the first coercive voltage and the second coercive voltage as being equal, they may be different. By reducing the coercive voltage, the memory cell MC can be operated at a low voltage.

[0172] As described above, the voltage applied to the ferroelectric layer of the capacitor 10 can be expressed as the difference between the potential of one electrode of the capacitor 10 and the potential of the other electrode of the capacitor 10. Also, as described above, the other electrode of the capacitor 10 is electrically connected to the wiring PL. Therefore, by controlling the potential of the wiring PL, the voltage applied to the ferroelectric layer can be controlled.

[0173] 10B illustrates an example of a method for driving the memory cell MC whose circuit configuration is shown in FIG. 8A. In the following description, the voltage applied to the ferroelectric layer of the capacitive element 10 refers to the difference between the potential of one electrode of the capacitive element 10 and the potential of the other electrode (wiring PL). The polarity of the transistor 11 is assumed to be n-channel.

[0174] 10B is a timing chart showing an example of a method for driving the memory cell MC shown in FIG. 8A. FIG. 10B shows an example of writing and reading binary digital data to the memory cell MC. Specifically, FIG. 10B shows an example in which data "1" is written to the memory cell MC from time T01 to time T02, read and rewrite are performed from time T03 to time T05, read and write data "0" to the memory cell MC from time T11 to time T13, read and rewrite are performed from time T14 to time T16, and read and write data "1" to the memory cell MC from time T17 to time T19.

[0175] A reference potential Vref is supplied to the sense amplifier SA electrically connected to the line BL. In the read operation shown in FIG. 10B, when the potential of the line BL is higher than Vref, data "1" is read by the column circuit. On the other hand, when the potential of the line BL is lower than Vref, data "0" is read by the column circuit.

[0176] Between time T01 and time T02, the potential of the wiring WL is set to a high potential. This turns on the transistor 11. The potential of the wiring BL is set to Vw. Since the transistor 11 is on, the potential of one electrode of the capacitor 10 becomes Vw. Furthermore, the potential of the wiring PL is set to GND. As a result, the voltage applied to the ferroelectric layer of the capacitor 10 becomes "Vw-GND." This allows data "1" to be written to the memory cell MC. Therefore, the period from time T01 to time T02 can be said to be a period during which a write operation is performed.

[0177] Here, Vw is preferably equal to or greater than VSP, for example. GND can be, for example, a ground potential, but does not necessarily have to be a ground potential as long as the memory cell MC can be driven to satisfy the spirit of one aspect of the present invention. For example, if the absolute values ​​of the first saturation polarization voltage and the second saturation polarization voltage are different, and the absolute values ​​of the first coercive voltage and the second coercive voltage are different, GND can be a potential other than ground.

[0178] Between time T02 and time T03, the potential of the wiring BL and the potential of the wiring PL are set to GND. As a result, the voltage applied to the ferroelectric layer of the capacitor 10 becomes 0 V. Since the voltage "Vw-GND" applied to the ferroelectric layer of the capacitor 10 between time T01 and time T02 can be set to VSP or higher, the polarization amount of the ferroelectric layer of the capacitor 10 changes according to curve 52 shown in FIG. 10A between time T02 and time T03. As a result, no polarization reversal occurs in the ferroelectric layer of the capacitor 10 between time T02 and time T03.

[0179] After the potentials of the wiring BL and the wiring PL are set to GND, the potential of the wiring WL is set to a low potential. This turns off the transistor 11. This completes the write operation, and data "1" is stored in the memory cell MC. The potentials of the wiring BL and the wiring PL can be set to any potential as long as no polarization reversal occurs in the ferroelectric layer of the capacitor 10, i.e., the voltage applied to the ferroelectric layer of the capacitor 10 is equal to or greater than the second coercive voltage, −Vc.

[0180] Between time T03 and time T04, the potential of the wiring WL is set to a high potential. This turns on the transistor 11. The potential of the wiring PL is set to Vw. By setting the potential of the wiring PL to Vw, the voltage applied to the ferroelectric layer of the capacitor 10 becomes "GND-Vw." As described above, the voltage applied to the ferroelectric layer of the capacitor 10 between time T01 and time T02 is "Vw-GND." Therefore, polarization reversal occurs in the ferroelectric layer of the capacitor 10. During polarization reversal, current flows through the wiring BL, and the potential of the wiring BL becomes higher than Vref. This allows the column circuit to read the data "1" stored in the memory cell MC. Therefore, the period from time T03 to time T04 can be considered a period during which a read operation is performed. Note that although Vref is higher than GND and lower than Vw, it may be higher than Vw, for example.

[0181] Since the above read is a destructive read, the data "1" held in the memory cell MC is lost. Therefore, from time T04 to time T05, the potential of the wiring BL is set to Vw, and the potential of the wiring PL is set to GND. This rewrites the data "1" to the memory cell MC. Therefore, the period from time T04 to time T05 can be said to be a period in which a rewrite operation is performed.

[0182] From time T05 to time T11, the potentials of the wiring BL and the wiring PL are set to GND. Then, the potential of the wiring WL is set to low. This completes the rewrite operation, and data "1" is held in the memory cell MC.

[0183] Between time T11 and time T12, the potential of the wiring WL is set to a high potential, and the potential of the wiring PL is set to Vw. Since the memory cell MC holds data "1," the potential of the wiring BL becomes higher than Vref, and the data "1" held in the memory cell MC is read. Therefore, the period from time T11 to time T12 can be considered a period in which a read operation is performed.

[0184] From time T12 to time T13, the potential of the wiring BL is set to GND. Because the transistor 11 is on, the potential of one electrode of the capacitor 10 is set to GND. Also, the potential of the wiring PL is set to Vw. As a result, the voltage applied to the ferroelectric layer of the capacitor 10 is "GND-Vw." This allows data "0" to be written to the memory cell MC. Therefore, the period from time T12 to time T13 can be said to be a period during which a write operation is performed.

[0185] Between time T13 and time T14, the potential of the wiring BL and the potential of the wiring PL are set to GND. As a result, the voltage applied to the ferroelectric layer of the capacitor 10 becomes 0V. Since the voltage "GND-Vw" applied to the ferroelectric layer of the capacitor 10 between time T12 and time T13 can be set to -VSP or less, the polarization amount of the ferroelectric layer of the capacitor 10 between time T13 and time T14 changes according to the curve 51 shown in FIG. 10A. As a result, no polarization reversal occurs in the ferroelectric layer of the capacitor 10 between time T13 and time T14.

[0186] After the potentials of the wiring BL and the wiring PL are set to GND, the potential of the wiring WL is set to a low potential. This turns off the transistor 11. This completes the write operation, and data "0" is stored in the memory cell MC. The potentials of the wiring BL and the wiring PL can be set to any potential as long as no polarization reversal occurs in the ferroelectric layer of the capacitor 10, i.e., the voltage applied to the ferroelectric layer of the capacitor 10 is equal to or lower than the first coercive voltage Vc.

[0187] From time T14 to time T15, the potential of the line WL is set to a high potential. This turns on the transistor 11. The potential of the line PL is set to Vw. By setting the potential of the line PL to Vw, the voltage applied to the ferroelectric layer of the capacitor 10 becomes “GND-Vw.” As described above, the voltage applied to the ferroelectric layer of the capacitor 10 is “GND-Vw” from time T12 to time T13. Therefore, no polarization reversal occurs in the ferroelectric layer of the capacitor 10. Therefore, the amount of current flowing through the line BL is smaller than when polarization reversal occurs in the ferroelectric layer of the capacitor 10. As a result, the increase in the potential of the line BL is smaller than when polarization reversal occurs in the ferroelectric layer of the capacitor 10; specifically, the potential of the line BL is below Vref. This allows the column circuit to read the data “0” stored in the memory cell MC. Therefore, the period from time T14 to time T15 can be considered a period during which a read operation is performed.

[0188] From time T15 to time T16, the potential of the wiring BL is set to GND. The potential of the wiring PL is set to Vw. This causes data "0" to be rewritten to the memory cell MC. Therefore, the period from time T15 to time T16 can be considered a period in which a rewrite operation is performed.

[0189] Between time T16 and time T17, the potentials of the wirings BL and PL are set to GND. Then, the potential of the wiring WL is set to low. This completes the rewrite operation, and data "0" is held in the memory cell MC.

[0190] Between times T17 and T18, the potential of the wiring WL is set to a high potential, and the potential of the wiring PL is set to Vw. Because data "0" is stored in the memory cell MC, the potential of the wiring BL becomes lower than Vref, and the data "0" stored in the memory cell MC is read. Therefore, the period from time T17 to time T18 can be considered a period in which a read operation is performed.

[0191] From time T18 to time T19, the potential of the wiring BL is set to Vw. Because the transistor 11 is on, the potential of one electrode of the capacitor 10 is Vw. The potential of the wiring PL is set to GND. As a result, the voltage applied to the ferroelectric layer of the capacitor 10 is "Vw-GND." This allows data "1" to be written to the memory cell MC. Therefore, the period from time T18 to time T19 can be said to be a period during which a write operation is performed.

[0192] After time T19, the potential of the wiring BL and the potential of the wiring PL are set to GND. After that, the potential of the wiring WL is set to a low potential. With the above, the write operation is completed and data "1" is held in the memory cell MC. The memory cell MC having a ferroelectric layer can hold data using two voltage values, VSP and -VSP. The memory cell MC is capable of high-speed rewriting and can be rewritten 10 times. 10 more than 10 times 12 The memory cells MC can function as nonvolatile memory for less than 1000 times. Also, the memory cells MC can operate at low voltage.

[0193] 11 shows a cross-sectional structure of a memory cell MC, in which a capacitor 10 is disposed above a transistor 11.

[0194] 11A is provided on a substrate 311 and includes a conductor 316 functioning as a gate, an insulator 315 functioning as a gate insulator, a semiconductor region 313 formed of part of the substrate 311, and low-resistance regions 314a and 314b functioning as source and drain regions. The transistor 11 may be either a p-channel type or an n-channel type.

[0195] In the transistor 11, the semiconductor region 313 (part of the substrate 311) where the channel is formed has a convex shape. Therefore, in the channel width direction, etc., the conductor 316 can be provided so as to cover the side and top surfaces of the semiconductor region 313 via the insulator 315. Such a transistor 11 is also called a FIN type transistor because it utilizes the convex portion of the semiconductor substrate. Note that an insulator may be provided in contact with the top of the convex portion and function as a mask for forming the convex portion. Furthermore, although the case where the convex portion is formed by processing a part of the semiconductor substrate has been shown here, a semiconductor film having a convex shape may also be formed by processing an SOI substrate.

[0196] The transistor 11 is merely an example, and the structure is not limited to this, and an appropriate transistor may be used depending on the circuit configuration or driving method.

[0197] A wiring layer including an interlayer film, a wiring, a plug, and the like may be provided between the transistor 11 and the capacitor 10. A plurality of wiring layers may be provided depending on the design. Here, a conductor functioning as a plug or a wiring may be collectively denoted by the same reference numeral. In this specification and the like, a wiring and a plug electrically connected to the wiring may be continuously manufactured without being manufactured in separate steps. That is, a part of the conductor may function as a wiring, and a part of the conductor may function as a plug.

[0198] For example, an insulator 320 and an insulator 322 are stacked in this order as an interlayer film over the transistor 11. An insulator 287 that functions as a barrier insulating film against hydrogen is preferably provided. The insulator 287 preferably contains silicon nitride or aluminum oxide because silicon nitride or aluminum oxide has high blocking properties against hydrogen.

[0199] A conductor 357 or the like that electrically connects the capacitor 10 and the transistor 11 is embedded in the insulator 320, the insulator 322, and the insulator 287. Note that the conductor 357 has a plug function or a wiring function, or both a plug function and a wiring function.

[0200] The insulator functioning as an interlayer film may also function as a planarizing film that covers the underlying unevenness. For example, the top surface of the insulator 322 may be planarized by a planarization process using a chemical mechanical polishing (CMP) method or the like to enhance flatness.

[0201] The wiring layer may be provided over the capacitor 10. FIG. 11B shows a wiring layer including a conductor 330, a conductor 356, and a conductor 357 over the capacitor 10. An insulator 352 is provided to cover the conductor 330. An insulator 354 is provided to cover the conductor 356. An insulator 210 is provided to cover the conductor 357. The wiring layer has a multilayer structure including two or more conductors.

[0202] The wiring layer may be provided between the transistor 11 and the capacitor 10. For example, in FIG. 12 , the insulators 320 and 322 are formed, the conductor 328 is buried to form part of the wiring layer, the insulators 324 and 326 are formed, the conductor 330 is buried to form another part of the wiring layer, the insulators 350, 352, and 354 are formed, the conductor 356 is buried to form yet another part of the wiring layer, the insulator 210 and 287 are formed, and the conductor 357 is buried to form yet another part of the wiring layer. The insulator 287 functions as a barrier insulating film against hydrogen. A wiring layer is formed by stacking four conductors. Note that the conductors 328, 330, 356, and 357 each have the function of a plug or a wiring, or the function of a plug and a wiring, respectively.

[0203] The insulators mentioned above include oxides, nitrides, oxynitrides, nitride oxides, metal oxides, metal oxynitrides, and metal nitride oxides, which have insulating properties.

[0204] The insulator may be made of a material with a low dielectric constant, which can reduce the parasitic capacitance between the wirings. Therefore, it is advisable to select the material depending on the function of the insulator.

[0205] The insulator preferably has a low dielectric constant. For example, the insulator preferably includes fluorine-doped silicon oxide, carbon-doped silicon oxide, carbon- and nitrogen-doped silicon oxide, pore-containing silicon oxide, or resin. Alternatively, the insulator preferably has a laminate structure of silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, fluorine-doped silicon oxide, carbon-doped silicon oxide, carbon- and nitrogen-doped silicon oxide, or pore-containing silicon oxide, and resin. Silicon oxide and silicon oxynitride are thermally stable, and therefore, by combining them with resin, a thermally stable laminate structure with a low dielectric constant can be obtained. Examples of resins include polyester, polyolefin, polyamide (e.g., nylon, aramid), polyimide, polycarbonate, and acrylic.

[0206] Conductors can be used for wiring and plugs. Materials containing one or more metal elements selected from aluminum, chromium, copper, silver, gold, platinum, tantalum, nickel, titanium, molybdenum, tungsten, hafnium, vanadium, niobium, manganese, magnesium, zirconium, beryllium, indium, and ruthenium can be used as the conductor. Semiconductors with high electrical conductivity, such as polycrystalline silicon containing impurity elements such as phosphorus, and silicides such as nickel silicide can also be used.

[0207] For example, the conductor may be a single layer or a laminate of conductive materials such as metals, alloys, metal nitrides, or metal oxides formed from the above materials. High-melting-point materials such as tungsten and molybdenum, which have both heat resistance and conductivity, are preferably used, and tungsten is preferred. Alternatively, the conductor may be formed from a low-resistance conductive material such as aluminum or copper. The use of a low-resistance conductive material can reduce wiring resistance.

[0208] 11A, 11B, and 12, the upper electrode 120b is formed by a method involving substrate heating, such as thermal ALD, thereby enhancing the ferroelectricity of the insulator 130 without performing high-temperature baking after formation. Therefore, since a semiconductor device can be fabricated without performing high-temperature baking, a low-resistance conductive material with a low melting point, such as copper, can be used.

[0209] The upper surface of the conductor 357 is in contact with the lower surface of the conductor 110. The upper surface of the conductor 110 is in contact with at least the lower surface of the lower electrode 120a of the capacitor 10. In this way, the lower electrode 120a functioning as the lower electrode of the capacitor 10 and the low-resistance region 314a functioning as one of the source and drain of the transistor 11 are electrically connected via at least the conductor 357.

[0210] 11A, 11B, and 12, the capacitor 10 is sealed with an insulator 287 disposed below the capacitor 10 and insulators 152a and 152b disposed above the capacitor 10. The insulators 287 and 152b can prevent hydrogen from diffusing from the outside to the capacitor 10, thereby reducing or maintaining a reduced hydrogen concentration in the insulator 130 of the capacitor 10. This can improve the ferroelectricity of the insulator 130. The insulators 152a and 152b each preferably contain silicon nitride or aluminum oxide.

[0211] It is also preferable that an insulator 155 is provided below the insulator 152a. The insulator 155 is preferably an insulator that has the function of capturing and fixing hydrogen. For example, it is preferable to use aluminum oxide or the like. By providing such an insulator 155 so as to cover the capacitor 10, it is possible to capture and fix hydrogen contained in the insulator 130 of the capacitor 10, thereby reducing the hydrogen concentration in the insulator 130. This can improve the ferroelectricity of the insulator 130. It is also possible to reduce leakage current between the conductor 110 and the conductor 120. However, this is not limited to this, and a configuration without providing the insulator 155 is also possible.

[0212] 11A, 11B, and 12, an insulator 286 is further provided over the insulator 152b. The insulator 286 may have the same material as the insulators 320 and 322.

[0213] The memory cell MC having the cross-sectional structure shown in FIGS. 11A, 11B, and 12 can realize high integration, high-speed driving, high durability, or low power consumption of the memory circuit.

[0214] At least part of the structures, methods, and the like described in this embodiment mode can be implemented in appropriate combination with other embodiment modes and examples described in this specification.

[0215] (Embodiment 3) In this embodiment, an example of a secondary battery protected by a control circuit of one embodiment of the present invention will be described.

[0216] <Configuration example 1 of secondary battery> A secondary battery in which a positive electrode, a negative electrode, and an electrolyte are enclosed in an exterior body will be exemplified below.

[0217] [Positive electrode] The positive electrode includes a positive electrode active material layer and a positive electrode current collector. The positive electrode active material layer includes a positive electrode active material, and may include a conductive material and a binder.

[0218] 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.

[0219] Materials having a layered rock salt-type crystal structure such as lithium cobalt oxide (LiCoO2) are known to have a high discharge capacity and be excellent as the positive electrode active material of a secondary battery. Examples of the material having a layered rock salt-type crystal structure include composite oxides represented by LiMO2. Examples of the element M include one or more selected from Co, Ni, and Mn. Further, examples of the element M include one or more selected from Al and Mg in addition to one or more selected from Co, Ni, and Mn.

[0220] In addition, it is preferable to mix lithium nickelate (LiNiO2 or LiNi 1-x M x O2 (0 < x < 1) (M = Co, Al, etc.)) with a lithium-containing material having a spinel-type crystal structure containing manganese such as LiMn2O4 as the positive electrode active material. By adopting such a configuration, the characteristics of the secondary battery can be improved.

[0221] In addition, as the positive electrode active material, a 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 lithium-manganese composite oxide particle, <a / (b+c)<2、かつc>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.

[0222] [Negative electrode] The negative electrode includes a negative electrode active material layer and a negative electrode current collector. The negative electrode active material layer may also include a conductive material and a binder.

[0223] As the negative electrode active material, for example, at least one of an alloy-based material and a carbon-based material can be used.

[0224] ​The negative electrode active material can be an element capable of undergoing charge-discharge reactions through alloying and dealloying reactions with lithium. For example, materials containing at least one of silicon, tin, gallium, aluminum, germanium, lead, antimony, bismuth, silver, zinc, cadmium, and indium can be used. These elements have a larger capacity than carbon, and silicon, in particular, has a high theoretical capacity of 4200 mAh / g. For this reason, silicon is preferred as the negative electrode active material. Compounds containing these elements can also be used. Examples include SiO, Mg2Si, Mg2Ge, SnO, SnO2, Mg2Sn, SnS2, V2Sn3, FeSn2, CoSn2, Ni3Sn2, Cu6Sn5, Ag3Sn, Ag3Sb, Ni2MnSb, CeSb3, LaSn3, La3Co2Sn7, CoSb3, InSb, and SbSn. Here, elements that can undergo charge-discharge reactions by alloying / dealloying reactions with lithium, and compounds containing such elements, are sometimes called alloy-based materials.

[0225] In this specification and the like, SiO refers to, for example, silicon monoxide. Alternatively, SiO refers to SiO x Here, x preferably has a value close to 1. For example, x is preferably 0.2 or more and 1.5 or less, and more preferably 0.3 or more and 1.2 or less.

[0226] Examples of carbonaceous materials that can be used include graphite, easily graphitizable carbon (soft carbon), non-graphitizable carbon (hard carbon), carbon nanotubes, graphene, and carbon black.

[0227] Examples of graphite include artificial graphite and natural graphite. Examples of artificial graphite include mesocarbon microbeads (MCMB), coke-based artificial graphite, and pitch-based artificial graphite. Here, spherical graphite having a spherical shape can be used as the artificial graphite. For example, MCMB may have a spherical shape and is preferred. Furthermore, it is relatively easy to reduce the surface area of ​​MCMB, and this may be preferred. Examples of natural graphite include flake graphite and spherical natural graphite.

[0228] When lithium ions are inserted into graphite (when lithium-graphite intercalation compounds are formed), graphite exhibits a low potential similar to that of metallic lithium (0.05 V to 0.3 V vs. Li / Li + ) This allows lithium-ion secondary batteries to exhibit high operating voltages. Furthermore, graphite is preferred because it has advantages such as a relatively high capacity per unit volume, a relatively small volume expansion, low cost, and a higher level of safety compared to lithium metal.

[0229] In addition, titanium dioxide (TiO2), 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.

[0230] 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 has a large charge / discharge capacity (900mAh / g, 1890mAh / cm 3 ) and is preferred.

[0231] When a composite nitride of lithium and a transition metal is used, lithium ions are contained in the negative electrode active material, and therefore it can be preferably combined with a material that does not contain lithium ions, such as V2O5 or Cr3O8, as the positive electrode active material. Even when a material containing lithium ions is used as the positive electrode active material, the composite nitride of lithium and a transition metal can be used as the negative electrode active material by first desorbing the lithium ions contained in the positive electrode active material.

[0232] 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 form alloys 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 It 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.

[0233] The conductive material and binder that can be contained in the negative electrode active material layer can be the same as the conductive material and binder that can be contained in the positive electrode active material layer.

[0234] [Current collector] The positive electrode current collector and the negative electrode current collector are preferably made of a material that does not alloy with carrier ions such as lithium, etc. The current collectors can be made of aluminum, copper, titanium, or the like.

[0235] [Electrolyte] The electrolyte can be a solution containing a solvent and a salt. The solvent 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.

[0236] Furthermore, by using one or more flame-retardant and non-volatile ionic liquids (room-temperature molten salts) as the solvent, it is possible to prevent the secondary battery from exploding or catching fire even when 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, as well as aromatic cations such as imidazolium cations and 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.

[0237] 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.

[0238] The solution used as the electrolyte in the secondary battery is preferably a highly purified solution with low content of granular dust and elements other than the constituent elements of the electrolyte (hereinafter simply referred to as "impurities"). Specifically, the weight ratio of impurities to the solution is preferably 1% or less, preferably 0.1% or less, and more preferably 0.01% or less.

[0239] 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 also be added to the solution. The concentration of the added material may be, for example, 0.1 wt % to 5 wt % of the total solvent.

[0240] Alternatively, a polymer gel electrolyte obtained by swelling a polymer with a solution may be used.

[0241] The use of a polymer gel electrolyte improves safety against leakage, etc. It also enables the secondary battery to be made thinner and lighter.

[0242] 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.

[0243] Examples of polymers that can be used include polymers having a polyalkylene oxide structure such as polyethylene oxide (PEO), PVDF, polyacrylonitrile, and 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.

[0244] In addition, instead of an electrolyte solution, a solid electrolyte containing an inorganic material such as a sulfide or oxide, or a polymer material such as a PEO (polyethylene oxide) can be used. When a solid electrolyte is used, 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.

[0245] Furthermore, a solid electrolyte can be used as the electrolyte, such as a sulfide-based solid electrolyte, an oxide-based solid electrolyte, or a halide-based solid electrolyte.

[0246] Sulfide-based solid electrolytes include thiolithium-based (Li 10 GeP2S 12 , Li 3.25 Ge 0.25 P 0.75 S4, etc.), sulfide glasses (70Li2S·30P2S5, 30Li2S·26B2S3·44LiI, 63Li2S·36SiS2·1Li3PO4, 57Li2S·38SiS2·5Li4SiO4, 50Li2S·50GeS2, etc.), sulfide crystallized glasses (Li7P3S 11 , Li 3.25 P 0.95 Sulfide-based solid electrolytes have the advantages of being highly conductive, being able to be synthesized at low temperatures, and being relatively soft, which makes it easy to maintain conductive paths even after charging and discharging.

[0247] Oxide-based solid electrolytes include materials with a perovskite crystal structure (La 2 / 3-x Li 3x TiO3, etc.), materials with NASICON-type crystal structure (Li 1-X Al X Ti 2-X (PO4)3, etc.), materials with garnet-type crystal structure (Li7La3Zr2O 12 etc.), materials with LISICON-type crystal structure (Li 14 ZnGeO 16 etc.), LLZO(Li7La3Zr2O 12 ), oxide glass (Li3PO4-Li4SiO4, 50Li4SiO4·50Li3BO3, etc.), oxide glass-ceramics (Li 1.07 Al 0.69 Ti 1.46 (PO4)3, Li 1.5 Al 0.5 Ge 1.5 Oxide-based solid electrolytes have the advantage of being stable in the atmosphere.

[0248] Halide-based solid electrolytes include LiAlCl4, Li3InBr6, LiF, LiCl, LiBr, LiI, etc. Further, composite materials in which these halide-based solid electrolytes are filled in the pores of porous aluminum oxide or porous silica can also be used as solid electrolytes.

[0249] Also, different solid electrolytes may be mixed and used.

[0250] Among them, Li 1+x Al x Ti 2-x (PO4)3(0 < x < 1) (hereinafter referred to as LATP) contains aluminum and titanium, which are elements that the positive electrode active material used in the secondary battery of one aspect of the present invention may have. Therefore, a synergistic effect can be expected for improving the cycle characteristics, which is preferable. Also, an improvement in productivity due to reduction of processes can be expected. In this specification, etc., the NASICON-type crystal structure refers to a compound represented by M2(XO4)3 (M: transition metal, X: S, P, As, Mo, W, etc.), which has a structure in which MO6 octahedrons and XO4 tetrahedrons share vertices and are three-dimensionally arranged.

[0251] 〔Separator〕 The secondary battery preferably has a separator. As the separator, for example, those formed of paper, non-woven fabric, glass fiber, ceramics, or synthetic fibers using nylon (polyamide), vinylon (polyvinyl alcohol-based fiber), polyimide, polyester, acrylic, polyolefin, polyurethane, etc. can be used. The separator is preferably processed into an envelope shape and arranged so as to wrap either the positive electrode or the negative electrode.

[0252] The separator may have a multilayer structure. For example, an organic material film such as polypropylene or polyethylene can be coated with a ceramic material, a fluorine-based material, a polyamide material, or a mixture of these. Examples of ceramic materials that can be used include aluminum oxide particles and silicon oxide particles. Examples of fluorine-based materials that can be used include PVDF and polytetrafluoroethylene. Examples of polyamide materials that can be used include nylon and aramid (meta-aramid, para-aramid).

[0253] Coating with ceramic materials improves oxidation resistance, suppressing separator degradation during high-voltage charging and discharging and improving the reliability of secondary batteries. Coating with fluorine-based materials also improves adhesion between the separator and electrodes, improving output characteristics. Coating with polyamide materials, especially aramid, improves heat resistance, improving the safety of secondary batteries.

[0254] For example, both sides of a polypropylene film may be coated with a mixed material of aluminum oxide and aramid, or the surface of the polypropylene film that contacts the positive electrode may be coated with a mixed material of aluminum oxide and aramid, and the surface that contacts the negative electrode may be coated with a fluorine-based material.

[0255] When a separator with a multilayer structure is used, the safety of the secondary battery can be maintained even if the overall thickness of the separator is thin, and therefore the capacity per volume of the secondary battery can be increased.

[0256] [Exterior body] The exterior body of the secondary battery can be made of a metal material such as aluminum or 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.

[0257] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0258] (Fourth embodiment) In this embodiment, a positive electrode active material of a secondary battery protected by a control circuit according to one embodiment of the present invention will be described in detail.

[0259] It is preferable that the positive electrode active material of a secondary battery be capable of being charged even at a high charging voltage. By increasing the charging voltage, the energy density of the secondary battery can be increased. Therefore, the duration of the secondary battery can be extended. Furthermore, since a high energy density can be achieved even in a small volume, it becomes possible to reduce the size and weight of electronic devices.

[0260] By using a control circuit of one embodiment of the present invention, it is possible to detect, control, or suppress overcharge, overdischarge, charging overcurrent, discharging overcurrent, short-circuit current, cell balancing, and the like. The control circuit of one embodiment of the present invention has high accuracy in detecting abnormalities. For example, in a detection operation during overcharge or overdischarge, it is possible to significantly reduce the difference between the actual voltage of a secondary battery and the voltage set in the design. Similarly, it is possible to significantly reduce the difference between the actual current of a secondary battery and the current set in the design.

[0261] Therefore, even when a positive electrode active material with a high charging voltage and excellent characteristics is used, safety can be maintained by the control circuit of one embodiment of the present invention, and the excellent characteristics of the positive electrode active material can be fully exhibited.

[0262] The positive electrode active material will be described below.

[0263] [Positive electrode active material structure] As described in the previous embodiment, materials having 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 having a layered rock-salt crystal structure is a composite oxide represented by LiMO2. Examples of the element M include one or more selected from Co, Ni, and Mn. Examples of the element M include one or more selected from Co, Ni, and Mn, as well as one or more selected from Al and Mg.

[0264] 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.

[0265] 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.

[0266] The structure of the positive electrode active material will be described with reference to Figures 13 and 14. Figures 13 and 14 describe the case where cobalt is used as the transition metal contained in the positive electrode active material.

[0267] The positive electrode active material shown in Figure 14 is lithium cobalt oxide (LiCoO2) to which no halogen or magnesium is added, and its crystal structure changes depending on the depth of charge. The manner in which the crystal structure changes will be explained using Figure 14.

[0268] As shown in Figure 14, 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.

[0269] 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.

[0270] Furthermore, lithium cobalt oxide at a charge depth of approximately 0.88 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. For this reason, 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 14 and other parts of this specification, the c-axis of the H1-3 crystal structure is shown as half the unit cell to facilitate comparison with other structures.

[0271] 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, as described below, the O3' crystal structure 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.

[0272] 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.

[0273] However, these two crystal structures have a large deviation in the CoO2 layers. As shown by the dotted lines and arrows in Figure 14, 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.

[0274] 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%.

[0275] In addition, the H1-3 type crystal structure, which has continuous CoO2 layers such as P-3m1(O1), is likely to be unstable.

[0276] 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.

[0277] Next, the positive electrode active material shown in FIG. 13 can reduce the displacement of the CoO2 layer during repeated high-voltage charge and discharge. Furthermore, it can reduce the change in volume. Therefore, this compound can achieve excellent cycle characteristics. Furthermore, this compound can have a stable crystal structure in a high-voltage charged state. Therefore, this compound is preferable because it is less likely to cause a short circuit when maintained in a high-voltage charged state, further improving safety.

[0278] In the above-described positive electrode active material, the change in crystal structure and the difference in volume per the same number of transition metal atoms between a fully discharged state and a high-voltage charged state are small.

[0279] Figure 13 shows the crystal structure before and after charge and discharge. The positive electrode active material is a composite oxide containing lithium, cobalt as a transition metal, and oxygen. In addition to the above, it is preferable to contain magnesium as an additive element. It is also preferable to contain a halogen such as fluorine or chlorine as an additive element.

[0280] The crystal structure at a charge depth of 0 (discharged state) in Figure 13 is R-3m(O3). This is the same crystal structure as Figure 14. On the other hand, when the charge depth is fully charged in Figure 13, the crystal has a structure different from the H1-3 crystal structure shown in Figure 14. The crystal structure shown in Figure 13 belongs to the space group R-3m. Although it is not a spinel crystal structure, ions such as cobalt and magnesium occupy six oxygen coordination positions, and the arrangement of cations has a symmetry similar to that of a spinel structure. In the crystal structure shown in Figure 13, the symmetry of the CoO2 layer is the same as that of an O3 type. Therefore, in this specification, the crystal structure shown in Figure 13 is referred to as an O3' type crystal structure or a pseudospinel type crystal structure. Note that in the diagram of the O3' type crystal structure shown in Figure 13, lithium is omitted to explain the symmetry of the cobalt atoms and the oxygen atoms. However, in reality, lithium, for example, 20 atomic % or less relative to cobalt, is present between the CoO2 layers. 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, and halogens such as fluorine are preferably present randomly and dilutely at the oxygen sites.

[0281] In the O3'-type crystal structure, light elements such as lithium may occupy the oxygen tetracoordination site, and in this case too, the ion arrangement has a symmetry similar to that of the spinel type.

[0282] It can also be said that the O3' type crystal structure is 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 The crystal structure is similar to that of lithium cobaltate (NiO2), but it is known that pure lithium cobaltate or layered rock salt-type positive electrode active materials containing a large amount of cobalt do not usually adopt this crystal structure.

[0283] In the above-mentioned positive electrode active materials, the change in the crystal structure when a large amount of lithium is released during high-voltage charging is further suppressed compared to positive electrode active materials that do not contain magnesium, etc. For example, as shown by the dotted line in Figure 13, there is almost no displacement of the CoO2 layers in these crystal structures.

[0284] More specifically, the cathode active material shown in FIG. 13 exhibits high structural stability even at high charging voltages. For example, the cathode active material shown in FIG. 14, which does not contain magnesium, assumes an H1-3 crystal structure at a charging voltage of approximately 4.6 V relative to the lithium metal potential. However, the cathode active material shown in FIG. 13 can maintain the R-3m(O3) crystal structure even at charging voltages of approximately 4.6 V. Even at higher charging voltages, such as 4.65 V to 4.7 V relative to the lithium metal potential, the cathode active material shown in FIG. 13 can adopt an O3' crystal structure. Furthermore, when the charging voltage is increased above 4.7 V, the H1-3 crystal structure may finally be observed in the cathode active material shown in FIG. 13. Furthermore, at lower charging voltages, such as at a charging voltage of 4.5 V or more but less than 4.6 V relative to the lithium metal potential, the cathode active material shown in FIG. 13 may adopt an O3' crystal structure.

[0285] In addition, when graphite is used as the negative electrode active material in a secondary battery, the voltage of the secondary battery decreases by the difference between the potential of graphite and that of lithium metal. The potential of graphite is approximately 0.05 V to 0.2 V relative to the potential of lithium metal. Therefore, even when the voltage of a secondary battery using graphite as the negative electrode active material is 4.3 V or higher and 4.5 V or lower, the positive electrode active material shown in Figure 13 can maintain the R-3m(O3) crystal structure. Furthermore, even when the charge voltage is higher, for example, when the secondary battery voltage is higher than 4.5 V and lower than 4.6 V, the positive electrode active material shown in Figure 13 can also adopt the O3'-type crystal structure. Furthermore, even when the charge voltage is lower, for example, when the secondary battery voltage is 4.2 V or higher but lower than 4.3 V, the positive electrode active material shown in Figure 13 can adopt the O3'-type crystal structure.

[0286] Therefore, in the positive electrode active material shown in FIG. 13, the crystal structure is not easily broken even when charging and discharging are repeated at a high voltage.

[0287] In addition, in the positive electrode active material, the difference in volume per unit cell between the O3 type crystal structure at a charge depth of 0 and the O3' type crystal structure at a charge depth of about 0.8 is 2.5% or less, more specifically 2.2% or less.

[0288] In addition, the O3' type crystal structure can be expressed by the coordinates of cobalt and oxygen in the unit cell being Co(0,0,0.5), O(0,0,x), 0.20≦x≦0.25.

[0289] Additive elements, such as magnesium, present randomly and dilutely between the CoO2 layers, i.e., at the lithium sites, have the effect of suppressing the displacement of the CoO2 layers. Therefore, the presence of magnesium between the CoO2 layers tends to result in an O3'-type crystal structure. Therefore, it is preferable for magnesium to be distributed throughout the particles of the positive electrode active material. In addition, to distribute magnesium throughout the particles, it is preferable to perform a heat treatment during the manufacturing process of the positive electrode active material.

[0290] However, if the heat treatment temperature is too high, cation mixing occurs, increasing the possibility that added elements, such as magnesium, will enter the cobalt site. Magnesium present in the cobalt site is ineffective in maintaining the R-3m structure during high-voltage charging. Furthermore, if the heat treatment temperature is too high, there are concerns that adverse effects such as cobalt being reduced to a divalent state and lithium evaporating may occur.

[0291] 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. The addition of 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.

[0292] However, if the magnesium concentration is increased beyond a desired value, the effect on stabilizing the crystal structure may be reduced. 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 is preferably 0.001 to 0.1 times the number of transition metal atoms, more preferably more than 0.01 to less than 0.04 times, and even more preferably about 0.02 times. The magnesium 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 raw material composition during the production process of the positive electrode active material.

[0293] Lithium cobalt oxide may contain, as an additive element, one or more metals other than cobalt, selected from nickel, aluminum, manganese, titanium, vanadium, and chromium, with the addition of at least one of nickel and aluminum being particularly preferred. Manganese, titanium, vanadium, and chromium may be stable and easily tetravalent, which may contribute significantly to structural stability. Addition of an additive element may result in a more stable crystalline structure in the positive electrode active material, for example, in a charged state at a high voltage. The additive element is preferably added to the positive electrode active material at a concentration that does not significantly alter the crystallinity of the lithium cobalt oxide. For example, the amount is preferably such that the aforementioned Jahn-Teller effect or the like is not exhibited.

[0294] As shown in the legend in Figure 13, transition metals such as nickel and manganese and aluminum are preferably present at the cobalt site, but some may be present at the lithium site. Magnesium is also preferably present at the lithium site. Oxygen may be partially substituted with fluorine.

[0295] The capacity of a positive electrode active material may decrease as the magnesium concentration of the positive electrode active material increases. For example, magnesium may enter lithium sites, reducing the amount of lithium contributing to charge and discharge. Excess magnesium may also produce magnesium compounds that do not contribute to charge and discharge. By including nickel as an additive element in addition to magnesium in a positive electrode active material, the capacity per weight and per volume may be increased. By including aluminum as an additive element in addition to magnesium in a positive electrode active material, the capacity per weight and per volume may be increased. By including nickel and aluminum in addition to magnesium in a positive electrode active material, the capacity per weight and per volume may be increased.

[0296] Hereinafter, the concentration of elements such as magnesium contained in the positive electrode active material will be expressed using the number of atoms.

[0297] The number of nickel atoms in the positive electrode active material is preferably 10% or less of the number of cobalt atoms, more preferably 7.5% or less, even more preferably 0.05% to 4% and particularly 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 the like, or may be based on the value of the composition of raw materials in the process of producing the positive electrode active material.

[0298] If the positive electrode active material is charged at a high voltage for a long period of time, transition metals may leach out of the positive electrode active material into the electrolyte, causing the crystal structure to collapse. However, by including nickel in the above proportions, it may be possible to suppress the leaching of transition metals from the positive electrode active material. The number of aluminum atoms in the positive electrode active material is preferably 0.05% to 4% of the number of cobalt atoms, and more preferably 0.1% to 2%. The aluminum 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 raw material composition during the production process of the positive electrode active material.

[0299] The positive electrode active material preferably contains an additional element X, and phosphorus is preferably used as the additional element X. Furthermore, the positive electrode active material of one embodiment of the present invention more preferably contains a compound containing phosphorus and oxygen.

[0300] When the positive electrode active material contains a compound containing the additive element X, short circuits may be less likely to occur when a high-voltage charged state is maintained.

[0301] When the positive electrode active material contains phosphorus as the additional element X, hydrogen fluoride generated by decomposition of the electrolyte solution may react with the phosphorus, resulting in a decrease in the concentration of hydrogen fluoride in the electrolyte solution.

[0302] When the electrolyte contains LiPF6, hydrogen fluoride may be generated by hydrolysis. Hydrogen fluoride may also be generated by the reaction of PVDF, which is used as a component of the positive electrode, with alkali. By reducing the hydrogen fluoride concentration in the electrolyte, corrosion of the current collector and / or peeling of the coating may be suppressed. Furthermore, gelation and / or insolubilization of PVDF may be suppressed, which may reduce adhesion.

[0303] When the positive electrode active material contains magnesium in addition to the additive element X, the stability in a high-voltage charged state is extremely high. When the additive element X is phosphorus, the number of phosphorus atoms is preferably 1% to 20% of the number of cobalt atoms, more preferably 2% to 10%, and even more preferably 3% to 8%. In addition, the number of magnesium atoms is preferably 0.1% to 10% of the number of cobalt atoms, more preferably 0.5% to 5%, and even more preferably 0.7% to 4%. The concentrations of phosphorus and magnesium shown here may be values ​​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 values ​​of the composition of raw materials in the process of producing the positive electrode active material.

[0304] When the positive electrode active material has cracks, the presence of phosphorus, more specifically, a compound containing phosphorus and oxygen, inside the cracks may inhibit the progression of the cracks.

[0305] As is clear from the oxygen atoms indicated by the arrows in Figure 13, the symmetry of the oxygen atoms is slightly different between the O3 and O3' crystal structures. Specifically, in the O3 crystal structure, the oxygen atoms are aligned along the (-1 0 2) plane indicated by the dotted line, whereas in the O3' crystal structure, the oxygen atoms are not strictly aligned along the (-1 0 2) plane. This is because, in the O3' crystal structure, as lithium decreases, tetravalent cobalt increases, increasing Jahn-Teller distortion and distorting the octahedral structure of CoO6. Another factor is that as lithium decreases, the repulsion between oxygen atoms in the CoO2 layer becomes stronger.

[0306] Magnesium is preferably distributed throughout the particles of the positive electrode active material, and in addition, the magnesium concentration in the surface layer is preferably higher than the average magnesium concentration in the entire particle. For example, the magnesium concentration in the surface layer measured by XPS or the like is preferably higher than the average magnesium concentration in the entire particle measured by ICP-MS or the like.

[0307] Furthermore, when the positive electrode active material contains elements other than cobalt, such as one or more metals selected from nickel, aluminum, manganese, iron, and chromium, the concentration of the metal near the particle surface is preferably higher than the average concentration of the entire particle. For example, the concentration of elements other than cobalt in the surface layer measured by XPS or the like is preferably higher than the average concentration of the element in the entire particle measured by ICP-MS or the like.

[0308] The particle surface is essentially a crystal defect, and because lithium is released from the surface during charging, the lithium concentration is likely to be lower than in the interior. This makes the surface more unstable and prone to the collapse of the crystal structure. If the magnesium concentration in the surface layer is high, changes in the crystal structure can be more effectively suppressed. Furthermore, a high magnesium concentration in the surface layer is expected to improve corrosion resistance to hydrofluoric acid produced by the decomposition of the electrolyte.

[0309] It is also preferable that the concentration of halogens such as fluorine in the surface layer of the positive electrode active material is higher than the average concentration of the entire particle. The presence of halogen in the surface layer, which is the region in contact with the electrolyte, can effectively improve corrosion resistance to hydrofluoric acid.

[0310] Thus, the surface layer of the positive electrode active material preferably has a different composition from the interior, with a higher concentration of additive elements, such as magnesium and fluorine, than the interior. Furthermore, it is preferable that the composition has a stable crystal structure at room temperature. Therefore, the surface layer may have a different crystal structure from the interior. For example, at least a portion of the surface layer of the positive electrode active material may have a rock salt crystal structure. Furthermore, when the surface layer and the interior have different crystal structures, it is preferable that the crystal orientations of the surface layer and the interior are roughly the same.

[0311] 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 contact, there is a crystal plane where the cubic close-packed structure formed by the anions is oriented in the same direction. However, the space group of layered rock salt crystals and O3'-type crystals is R-3m, which is different from the space groups Fm-3m (the space group of general rock salt crystals) and Fd-3m (the space group of rock salt crystals with the simplest symmetry) of rock salt crystals. Therefore, 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.

[0312] The general alignment of the crystal orientations of the two regions can be determined from TEM (transmission electron microscope) images, STEM (scanning transmission electron microscope) images, HAADF-STEM (high-angle annular dark-field scanning transmission electron microscope) images, and ABF-STEM (annular bright-field scanning transmission electron microscope) images. X-ray diffraction (XRD), electron diffraction, and neutron diffraction can also be used for this determination. If the crystal orientations are generally aligned, the difference in the orientation of the alternating linear array of cations and anions can be observed in TEM images, etc., to be 5 degrees or less, more preferably 2.5 degrees or less. Light elements such as oxygen and fluorine may not be clearly visible in TEM images, but in such cases, the alignment of the orientations can be determined from the arrangement of metal elements.

[0313] However, if the surface layer is only MgO or only a solid solution of MgO and CoO(II), it becomes difficult to insert and extract lithium. Therefore, the surface layer must contain at least cobalt, and in the discharged state, it must also contain lithium, providing a path for lithium insertion and extraction. It is also preferable that the concentration of cobalt is higher than that of magnesium.

[0314] The additional element X is preferably located in the surface layer of the particles of the positive electrode active material. For example, the positive electrode active material may be covered with a coating containing the additional element X.

[0315] <Grain boundary> The additive element X contained in the positive electrode active material may be present randomly and dilutely inside, but it is more preferable that a portion of it is segregated at the grain boundaries.

[0316] In other words, it is preferable that the concentration of the additional element X at and near the grain boundaries of the positive electrode active material is higher than that in other regions inside.

[0317] Like particle surfaces, grain boundaries are also planar defects. This makes them prone to instability and facilitates changes in the crystal structure. Therefore, if the concentration of the added element X at and near the grain boundaries is high, changes in the crystal structure can be more effectively suppressed.

[0318] Furthermore, when the concentration of the additive element X at and near the grain boundary is high, even if cracks occur along the grain boundary of the particles of the positive electrode active material, the concentration of the additive element X becomes high near the surface formed by the cracks. Therefore, even after the cracks occur, the corrosion resistance to hydrofluoric acid of the positive electrode active material can be improved.

[0319] In this specification and the like, the vicinity of the grain boundary refers to the region up to about 10 nm from the grain boundary.

[0320] <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.

[0321] <Analysis method> Whether a certain positive electrode active material exhibits an 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 a positive electrode obtained by disassembling a secondary battery.

[0322] As mentioned above, positive electrode active materials are characterized by minimal change in 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 the desired crystal structure may not be achieved simply by adding additional elements. 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, crystal structure analysis, including XRD, is required to determine whether a material is a positive electrode active material.

[0323] 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 atmosphere.

[0324] (Embodiment 5) In this embodiment mode, an example in which the control circuit for a secondary battery described in the above embodiment mode is used as an electronic component will be described with reference to FIG.

[0325] 15 shows an example in which multiple chips are provided on a printed circuit board (PCB) 1203. In FIG. 15, a chip 1201 is provided on the printed circuit board 1203. A control circuit of one embodiment of the present invention is provided on the chip 1201. A plurality of bumps 1202 are provided on the back surface of the chip 1201 and are electrically connected to the printed circuit board 1203.

[0326] By providing a control circuit according to one embodiment of the present invention, the volume of an electronic component can be reduced, and power consumption of the electronic component can be reduced.

[0327] Furthermore, since the control circuit of one embodiment of the present invention can be integrated on a chip, the volume occupied by the control circuit can be reduced in mobile terminals and various other electronic devices, which enables the miniaturization of the electronic devices.

[0328] Furthermore, since the control circuit of one embodiment of the present invention consumes low power, the duration of the secondary battery can be extended. Furthermore, by miniaturizing the control circuit, the volume occupied by the battery can be increased. As a result, the duration of the secondary battery can be extended.

[0329] An integrated circuit 1223 is preferably provided as a second chip on the printed circuit board 1203. The integrated circuit 1223 has a function of providing a control signal, a power supply, or the like to the chip 1201.

[0330] The various chips provided on the printed circuit board 1203 may include storage devices such as a DRAM 1221 and an FeRAM 1222. The printed circuit board 1203 may also be provided with a chip 1225 that has a function of performing wireless communication.

[0331] The integrated circuit 1223 may also have at least one of a function for performing image processing and a function for performing product-sum operations.

[0332] The integrated circuit 1223 may also include one or both of an A / D (analog / digital) conversion circuit and a D / A (digital / analog) conversion circuit.

[0333] This embodiment mode can be combined with the descriptions of other embodiment modes as appropriate.

[0334] (Sixth embodiment) In this embodiment mode, a configuration of a power storage system to which an electronic component including the control circuit described in the above embodiment mode can be applied will be described.

[0335] [Cylindrical secondary battery] An example of a cylindrical secondary battery will be described with reference to Fig. 16A. As shown in Fig. 16A, 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.

[0336] Fig. 16B is a diagram showing a cross section of a cylindrical secondary battery. The cylindrical secondary battery shown in Fig. 16B 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.

[0337] 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 alloys 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.

[0338] 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 electrically connected to the positive electrode 604, and a negative electrode terminal (negative electrode current collector lead) 607 is electrically 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.

[0339] 16C 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 400 is in contact with and electrically connected to a conductor 424 separated by an insulator 425. The conductor 424 is electrically connected to a control circuit 420 through a wiring 423. A negative electrode of each secondary battery 400 is electrically connected to the control circuit 420 through a wiring 426. The control circuit described in the above embodiment can be used as the control circuit 420.

[0340] 16D shows an example of a power storage system 415. The power storage system 415 has a plurality of secondary batteries 400, which are sandwiched between a conductive plate 413 and a conductive plate 414. The plurality of secondary batteries 400 are electrically connected to the conductive plate 413 and the conductive plate 414 by wiring 416. The plurality of secondary batteries 400 may be connected in parallel, in series, or may be connected in parallel and then further connected in series. By configuring the power storage system 415 to have a plurality of secondary batteries 400, a large amount of power can be extracted.

[0341] Consider a case where multiple secondary batteries 400 are electrically connected in parallel and then electrically connected in series, in which one control circuit is electrically connected to the multiple secondary batteries electrically connected in parallel.

[0342] 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.

[0343] 16D, the power storage system 415 is electrically connected to a control circuit 420 through wiring 421 and wiring 422. The control circuit described in the above embodiment can be used as the control circuit 420. The wiring 421 is electrically connected to positive electrodes of the plurality of secondary batteries 400 through a conductive plate 413, and the wiring 422 is electrically connected to negative electrodes of the plurality of secondary batteries 400 through a conductive plate 414.

[0344] Alternatively, a secondary battery 913 may be provided having a wound body 950a as shown in FIGS. 24A to 24C. The wound body 950a shown in FIG. 24A 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. The separator 933 has a width greater than that of the negative electrode active material layer 931a and the positive electrode active material layer 932a, and is wound so as to overlap with 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 width of the negative electrode active material layer 931a is greater than that of the positive electrode active material layer 932a. A wound body 950a having such a shape is preferable because of its high safety and productivity.

[0345] 24B, negative electrode 931 is electrically connected to terminal 951. Terminal 951 is electrically connected to terminal 911a. Positive electrode 932 is electrically connected to terminal 952. Terminal 952 is electrically connected to terminal 911b.

[0346] 24C, wound body 950a and the electrolyte are covered with casing 930 to form secondary battery 913. It is preferable that casing 930 be provided with a safety valve, an overcurrent protection element, and the like.

[0347] 24B, 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.

[0348] By using the positive electrode active material described in the above embodiment for the positive electrode 932, the secondary battery 913 can have high charge / discharge capacity and excellent cycle characteristics.

[0349] [Secondary battery pack] Next, an example of a power storage system of one embodiment of the present invention will be described with reference to FIG.

[0350] 17A is a diagram showing the appearance of secondary battery pack 531. FIG. 17B is a diagram illustrating the configuration of secondary battery pack 531. Secondary battery pack 531 has circuit board 501 and secondary battery 513. Label 509 is attached to secondary battery 513. Circuit board 501 is fixed with sticker 515. Secondary battery pack 531 also has antenna 517.

[0351] The circuit board 501 has a control circuit 590. The control circuit described in the previous embodiment can be used as the control circuit 590. For example, as shown in FIG. 17B , the control circuit 590 is provided on the circuit board 501. The circuit board 501 is electrically connected to a terminal 511. The circuit board 501 is also electrically connected to an antenna 517, one 551 of a positive electrode lead and a negative electrode lead of a secondary battery 513, and the other 552 of the positive electrode lead and the negative electrode lead.

[0352] 17C , the semiconductor device may have a circuit system 590a provided on a circuit board 501 and a circuit system 590b electrically connected to the circuit board 501 via a terminal 511. For example, a part of a control circuit according to one embodiment of the present invention is provided in the circuit system 590a, and another part is provided in the circuit system 590b.

[0353] 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.

[0354] 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.

[0355] 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.

[0356] This embodiment mode can be combined with the descriptions of other embodiment modes as appropriate.

[0357] (Embodiment 7) In this embodiment, an example in which a power storage system according to one embodiment of the present invention is mounted on a vehicle is described. Examples of vehicles include automobiles, motorcycles, and bicycles.

[0358] By installing a power storage system 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.

[0359] FIG. 18 illustrates an example of a vehicle using a power storage system according to one embodiment of the present invention. An automobile 8400 illustrated in FIG. 18A 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. By using one embodiment of the present invention, a vehicle with a long cruising distance can be realized. The automobile 8400 includes a power storage system. The power storage system not only drives the electric motor 8406 but also supplies power to light-emitting devices such as a headlight 8401 and an interior light (not shown).

[0360] The power storage system can also supply power to display devices such as a speedometer and a tachometer included in the automobile 8400. The power storage system can also supply power to a navigation system included in the automobile 8400.

[0361] The automobile 8500 shown in FIG. 18B can be charged by receiving power from an external charging facility via a plug-in system, a wireless power supply system, or the like, to the power storage system 8024 of the automobile 8500. FIG. 18B shows a state in which charging is being performed from a ground-mounted charging device 8021 to the power storage system 8024 mounted on the automobile 8500 via a cable 8022. The charging method and connector specifications may be determined appropriately using a predetermined method such as CHAdeMO (registered trademark) or Combo. The charging device 8021 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 power storage system 8024 mounted on the automobile 8500 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.

[0362] Although not shown, a power receiving device can be mounted on a vehicle and can be charged by receiving power contactlessly from a ground-based power transmitting device. In the case of this contactless power supply method, by incorporating a power transmitting device into a 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 vehicles. Furthermore, a solar cell can be installed on the exterior of the vehicle, and the power storage system can be charged while the vehicle is stopped or moving. Electromagnetic induction and magnetic resonance methods can be used for such contactless power supply.

[0363] 18C shows an example of a two-wheeled vehicle using the power storage system of one embodiment of the present invention. A scooter 8600 shown in FIG. 18C includes a power storage system 8602, a side mirror 8601, and a turn signal light 8603. The power storage system 8602 can supply electricity to the turn signal light 8603.

[0364] 18C, the power storage system 8602 can be stored in the under-seat storage 8604. The power storage system 8602 can be stored in the under-seat storage 8604 even if the under-seat storage 8604 is small.

[0365] 19A illustrates an example of an electric bicycle using the power storage system of one embodiment of the present invention. The power storage system of one embodiment of the present invention can be applied to an electric bicycle 8700 illustrated in FIG. 19A. The power storage system of one embodiment of the present invention includes, for example, a plurality of storage batteries, a protection circuit, and a neural network.

[0366] The electric bicycle 8700 includes a power storage system 8702. The power storage system 8702 can supply electricity to a motor that assists a rider. The power storage system 8702 is portable and is shown in a state detached from the bicycle in FIG. 19B . The power storage system 8702 includes a plurality of built-in storage batteries 8701, which are included in the power storage system of one embodiment of the present invention, and the remaining battery charge and the like can be displayed on a display unit 8703. The power storage system 8702 also includes a control circuit 8704 of one embodiment of the present invention. The control circuit 8704 is electrically connected to the positive and negative electrodes of the storage batteries 8701. The control circuit described in the above embodiment can be used as the control circuit 8704.

[0367] This embodiment mode can be combined with the descriptions of other embodiment modes as appropriate.

[0368] (Embodiment 8) In this embodiment, an example in which the power storage system described in the above embodiment is mounted on an electronic device will be described.

[0369] Next, FIGS. 20A and 20B show an example of a foldable tablet terminal (including a clamshell terminal). The tablet terminal 9600 shown in FIGS. 20A and 20B includes a housing 9630a, a housing 9630b, a movable portion 9640 connecting the housings 9630a and 9630b, a display unit 9631, a display mode selector switch 9626, a power switch 9627, a power saving mode selector switch 9625, a fastener 9629, and an operation switch 9628. Using a flexible panel for the display unit 9631 allows the tablet terminal to have a larger display area. FIG. 20A shows the tablet terminal 9600 in an open state, and FIG. 20B shows the tablet terminal 9600 in a closed state.

[0370] The tablet terminal 9600 also includes a power storage unit 9635 inside the housing 9630a and the housing 9630b. The power storage unit 9635 passes through the movable portion 9640 and is provided across the housing 9630a and the housing 9630b.

[0371] A part of the display portion 9631 can be a touch panel area, and data can be input by touching displayed operation keys. Furthermore, keyboard buttons can be displayed on the display portion 9631 by touching a position on the touch panel where a keyboard display switch button is displayed with a finger or a stylus.

[0372] Furthermore, a display mode switch 9626 can select between portrait and landscape display orientation, black and white display and color display, etc. A power saving mode switch 9625 can optimize the display brightness according to the amount of external light during use detected by an optical sensor built into the tablet terminal 9600. The tablet terminal may be equipped with not only an optical sensor but also other detection devices such as a gyroscope, an acceleration sensor, or other sensors for detecting tilt.

[0373] 20B illustrates a tablet terminal 9600 in a closed state, which includes a housing 9630, a solar cell 9633, and the power storage system of one embodiment of the present invention. The power storage system includes a control circuit 9634 and a power storage unit 9635. The control circuit described in the above embodiment can be used for the control circuit 9634.

[0374] The tablet terminal 9600 can be folded in half, so that the housing 9630a and the housing 9630b overlap each other when not in use. By folding, the display portion 9631 can be protected, thereby improving durability of the tablet terminal 9600.

[0375] In addition, the tablet terminals shown in Figures 20A and 20B can have functions such as displaying various information (still images, videos, text images, etc.), displaying a calendar, date or time 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).

[0376] A solar cell 9633 attached to the surface of the tablet terminal can supply power to a touch panel, a display unit, a video signal processor, etc. The solar cell 9633 can be provided on one or both surfaces of the housing 9630, and can be configured to efficiently charge the power storage unit 9635.

[0377] 20A and 20B illustrate a configuration in which a control circuit using the battery control circuit described in the above embodiment is applied to a foldable tablet terminal. However, other configurations may be used. For example, as illustrated in FIG. 20C, the present invention may be applied to a notebook personal computer, which is a clamshell terminal. FIG. 20C illustrates a notebook personal computer 9601 including a display portion 9631 in a housing 9630a and a keyboard portion 9650 in a housing 9630b. The notebook personal computer 9601 includes the control circuit 9634 and a power storage unit 9635 described in FIGS. 20A and 20B. The control circuit described in the above embodiment can be used for the control circuit 9634.

[0378] FIG. 21 illustrates an example of another electronic device. In FIG. 21, a display device 8000 is an example of an electronic device incorporating the power storage system of 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. The power storage system of 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.

[0379] 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).

[0380] The voice input device 8005 also uses a secondary battery. The voice input device 8005 has the power storage system described in the above embodiment. The voice input device 8005 has a plurality of sensors (optical sensors, temperature sensors, humidity sensors, air pressure sensors, illuminance sensors, motion sensors, and the like) including a microphone in addition to wireless communication elements, and can operate other devices by verbal commands from the user, for example, by controlling the power of the display device 8000 or adjusting the light intensity of the lighting device 8100. The voice input device 8005 can operate peripheral devices by voice and can replace a manual remote control.

[0381] In addition, the voice input device 8005 has at least one of wheels and mechanical movement means, and moves in the direction in which the user's voice can be heard, accurately picks up commands using a built-in microphone, and displays the contents on the display unit 8008, or allows touch input operations on the display unit 8008.

[0382] The voice input device 8005 can also function as a charging dock for a mobile information terminal 8009 such as a smartphone. The mobile information terminal 8009 and the voice input device 8005 can exchange power via wired or wireless connection. The mobile information terminal 8009 does not need to be carried around indoors, and it is desirable to ensure the necessary capacity while avoiding deterioration due to load on the secondary battery. Therefore, it is desirable to use the voice input device 8005 to manage and maintain the secondary battery. Furthermore, the voice input device 8005 has a speaker 8007 and a microphone, so that hands-free conversation is possible even while the mobile information terminal 8009 is charging. Furthermore, when the capacity of the secondary battery of the voice input device 8005 decreases, it can be moved in the direction of the arrow and wirelessly charged from a charging module 8010 connected to an external power source.

[0383] The voice input device 8005 may be placed on a stand. The voice input device 8005 may be provided with at least one of wheels and mechanical moving means so that it can be moved to a desired position, or the voice input device 8005 may be fixed to a desired position, for example, on the floor, without being provided with a stand or wheels.

[0384] 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.

[0385] 21, a stationary lighting device 8100 is an example of an electronic device that uses a secondary battery 8103 controlled by a microprocessor (including an APS) that controls charging. Specifically, the lighting device 8100 has a housing 8101, a light source 8102, a secondary battery 8103, and the like. FIG. 21 illustrates an example in which the secondary battery 8103 is provided inside a ceiling 8104 on which the housing 8101 and the light source 8102 are installed, but the secondary battery 8103 may 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.

[0386] Although Figure 21 shows an example of a stationary lighting device 8100 installed on a ceiling 8104, the secondary battery 8103 can also be used in a stationary lighting device installed on a surface 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, etc.

[0387] 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 discharge lamps such as incandescent lamps and fluorescent lamps, and light-emitting elements such as LEDs and organic EL elements.

[0388] 21, an air conditioner having an indoor unit 8200 and an outdoor unit 8204 is an example of an electronic device using a secondary battery 8203. Specifically, the indoor unit 8200 includes a housing 8201, an air outlet 8202, a secondary battery 8203, and the like. Although FIG. 21 illustrates an example in which the secondary battery 8203 is provided in the indoor unit 8200, the secondary battery 8203 may 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.

[0389] 21, an electric refrigerator-freezer 8300 is an example of an electronic device using a secondary battery 8304. 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. In FIG. 21, 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.

[0390] 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.

[0391] In addition to the electronic devices described above, the secondary battery can be mounted in various electronic devices. According to one embodiment of the present invention, the cycle characteristics of the secondary battery are improved. Therefore, by mounting a microprocessor (including an APS) that controls charging, which is one embodiment of the present invention, in the electronic device described in this embodiment, the electronic device can have a longer life. This embodiment can be implemented in appropriate combination with other embodiments.

[0392] 22A to 22E show examples of electronic devices to which the power storage system of one embodiment of the present invention is applied. Examples of electronic devices to which the power storage system of one embodiment of the present invention is applied include television devices (also referred to as televisions or television receivers), computer monitors, digital cameras, digital video cameras, digital photo frames, mobile phones (also referred to as mobile phones or mobile phone devices), portable game consoles, personal digital assistants, sound players, and large game consoles such as pachinko machines.

[0393] 22A 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 the power storage system of one embodiment of the present invention. The power storage system of one embodiment of the present invention includes, for example, a storage battery 7407 and the control circuit described in the above embodiment.

[0394] FIG. 22B illustrates a state in which the mobile phone 7400 is bent. When the mobile phone 7400 is deformed by an external force and bent as a whole, the storage battery 7407 provided therein may also be bent. In such a case, it is preferable to use a flexible storage battery as the storage battery 7407. FIG. 22C illustrates the bent state of the flexible storage battery. A control circuit 7408 is electrically connected to the storage battery. The control circuit described in the above embodiment can be used as the control circuit 7408.

[0395] Furthermore, a storage battery having a flexible shape can be incorporated along the curved surfaces of the interior or exterior walls of a house or building, or the interior or exterior of an automobile.

[0396] 22D illustrates an example of a bangle-type display device. A portable display device 7100 includes a housing 7101, a display portion 7102, operation buttons 7103, and the power storage system of one embodiment of the present invention. The power storage system of one embodiment of the present invention includes, for example, a storage battery 7104 and the control circuit described in the above embodiment.

[0397] 22E 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.

[0398] 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.

[0399] 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.

[0400] 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.

[0401] 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.

[0402] The portable information terminal 7200 also includes an input / output terminal 7206, and can directly exchange data with other information terminals 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.

[0403] The portable information terminal 7200 includes the power storage system of one embodiment of the present invention. The power storage system includes a storage battery and the control circuit described in the above embodiment.

[0404] The mobile information terminal 7200 preferably has a sensor, such as a fingerprint sensor, a pulse sensor, a body temperature sensor, or other human body sensor, a touch sensor, a pressure sensor, an acceleration sensor, or the like.

[0405] This embodiment mode can be combined with the descriptions of other embodiment modes as appropriate.

[0406] An example of an electronic device including a control circuit of one embodiment of the present invention will be described with reference to FIGS.

[0407] The cleaning robot 7140 includes a secondary battery, a display disposed on its top surface, multiple cameras disposed on its side, a brush, operation buttons, various sensors, and the like. Although not shown, the cleaning robot 7140 also includes tires, a suction port, and the like. The cleaning robot 7140 can move by itself, detect dust, and suck the dust through a suction port disposed on its bottom surface. By using a semiconductor device including a control circuit according to one embodiment of the present invention that is electrically connected to the secondary battery of the cleaning robot 7140, the number of components used can be reduced and abnormalities such as a micro-short circuit in the secondary battery can be detected.

[0408] The cleaning robot 7140 includes a secondary battery, an illuminance sensor, a microphone, a camera, a speaker, a display, various sensors (infrared sensors, ultrasonic sensors, acceleration sensors, piezoelectric sensors, optical sensors, gyro sensors, and the like), a moving mechanism, etc. A semiconductor device including a control circuit of one embodiment of the present invention is applied to the secondary battery of the cleaning robot 7140, so that the secondary battery can be controlled, protected, and the like.

[0409] The microphone has a function of detecting acoustic signals such as the user's voice and environmental sounds. The speaker has a function of emitting audio signals such as voice and warning sounds. The cleaning robot 7140 can analyze audio signals input via the microphone and emit necessary audio signals from the speaker. The cleaning robot 7140 can communicate with the user using the microphone and speaker.

[0410] The camera has a function of capturing images of the surroundings of the cleaning robot 7140. The cleaning robot 7140 also has a function of moving using a movement mechanism. The cleaning robot 7140 can capture images of the surroundings using the camera and analyze the images to detect the presence or absence of obstacles when moving.

[0411] The robot 7000 is equipped with a secondary battery, an illuminance sensor, a microphone, a camera, a speaker, a display unit, an obstacle sensor, a movement mechanism, a computing device, and the like.

[0412] The microphone has a function of detecting the user's voice and environmental sounds, etc. The speaker has a function of emitting sound. The robot 7000 can communicate with the user using the microphone and speaker.

[0413] The display unit has a function of displaying various information. The robot 7000 can display information desired by the user on the display unit. The display unit may be equipped with a touch panel. The display unit may also be a detachable information terminal, which can be installed in a fixed position on the robot 7000 to enable charging and data transfer.

[0414] The camera has a function of capturing images of the surroundings of the robot 7000. In addition, the obstacle sensor can detect the presence or absence of obstacles in the direction of travel when the robot 7000 moves forward using the movement mechanism. The robot 7000 can recognize the surrounding environment and move safely using the camera and obstacle sensor.

[0415] The robot 7000 includes a secondary battery according to one embodiment of the present invention and a semiconductor device or electronic component in its internal region. The semiconductor device including the control circuit according to one embodiment of the present invention can be applied to the secondary battery included in the robot 7000 to control, protect, and the like the secondary battery.

[0416] The flying object 7120 has a propeller, a camera, a secondary battery, etc., and has the ability to fly autonomously.

[0417] Furthermore, by applying a semiconductor device including a control circuit of one embodiment of the present invention to the secondary battery of the flying object 7120, the secondary battery can be controlled and protected in addition to being lighter in weight.

[0418] An electric vehicle 7160 is shown as an example of a moving object. The electric vehicle 7160 includes a secondary battery, tires, brakes, a steering device, a camera, and the like. By using a semiconductor device including a control circuit according to one embodiment of the present invention that is electrically connected to a secondary battery of the electric vehicle 7160, the number of components used can be reduced and abnormalities such as a micro-short circuit in the secondary battery can be detected.

[0419] Although an electric vehicle is described above as an example of a mobile object, the mobile object is not limited to an electric vehicle. For example, examples of the mobile object include a train, a monorail, a ship, and an aircraft (a helicopter, an unmanned aerial vehicle (drone), an airplane, and a rocket). By applying a semiconductor device including a control circuit according to one embodiment of the present invention that is electrically connected to a secondary battery of these mobile objects, the number of components used can be reduced and abnormalities such as a micro-short circuit in the secondary battery can be detected.

[0420] A battery pack including a control circuit of the present invention can be incorporated into a smartphone 7210, a PC (personal computer) 7220, a game console 7240, or the like. Note that the control circuit of one embodiment of the present invention may be attached to a battery pack.

[0421] The smartphone 7210 is an example of a portable information terminal. The smartphone 7210 includes a microphone, a camera, a speaker, various sensors, and a display unit. These peripheral devices are controlled by a semiconductor device including a control circuit. By using a semiconductor device including a control circuit of one embodiment of the present invention that is electrically connected to a secondary battery of the smartphone 7210, the number of components used can be reduced, and the secondary battery can be controlled and protected, thereby improving safety.

[0422] PC7220 is an example of a notebook PC. By applying a semiconductor device including a control circuit according to one embodiment of the present invention that is electrically connected to a secondary battery of a notebook PC, the number of components used can be reduced, and the secondary battery can be controlled and protected, thereby improving safety.

[0423] The game console 7240 is an example of a portable game console. The game console 7260 is an example of a home-use stationary game console. A controller 7262 is connected to the game console 7260 wirelessly or via a wire. By applying a semiconductor device including a control circuit of one embodiment of the present invention to the controller 7262, the number of components used can be reduced and a secondary battery can be controlled and protected, thereby improving safety.

[0424] This embodiment mode can be implemented in appropriate combination with any of the structures described in other embodiment modes.

[0425] (Embodiment 9) In this embodiment, an example in which a power storage system including a control circuit of one embodiment of the present invention and a secondary battery is mounted in an electronic device or a mobile object will be described.

[0426] 25A to 25D show examples of electronic devices incorporating a power storage system having the control circuit and a secondary battery described in the previous embodiment. Examples of electronic devices to which the power storage system is applied include television devices (also called televisions or television receivers), computer monitors, digital cameras, digital video cameras, digital photo frames, mobile phones (also called mobile phones or mobile phone devices), portable game machines, personal digital assistants, audio playback devices, and large game machines such as pachinko machines.

[0427] Furthermore, the secondary battery can be applied to a mobile object, typically an automobile. Examples of the automobile include next-generation clean energy automobiles such as hybrid vehicles (HVs), electric vehicles (EVs), and plug-in hybrid vehicles (PHVs). The secondary battery can be used as one of the power sources mounted in the automobile. The mobile object is not limited to an automobile. Examples of the mobile object include trains, monorails, ships, aircraft (helicopters, unmanned aerial vehicles (drones), airplanes, and rockets), electric bicycles, and electric motorcycles. A power storage system including a control circuit of one embodiment of the present invention and a secondary battery can be applied to these mobile objects.

[0428] Furthermore, the power storage system including the control circuit of this embodiment and a secondary battery may be applied to a ground-mounted charging device installed in a house or a charging station installed in a commercial facility.

[0429] 25A shows an example of a mobile phone. The mobile phone 2100 includes a display unit 2102 built into a housing 2101, as well as operation buttons 2103, an external connection port 2104, a speaker 2105, a microphone 2106, and the like. The mobile phone 2100 also includes a power storage system 2107.

[0430] The mobile phone 2100 can execute various applications such as mobile phone calls, e-mail, document browsing and creation, music playback, internet communication, and computer games.

[0431] The operation button 2103 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 2103 can be freely set by an operating system built into the mobile phone 2100.

[0432] The mobile phone 2100 is also capable of performing standardized short-range wireless communication, and can also make hands-free calls by communicating with a wirelessly enabled headset, for example.

[0433] The mobile phone 2100 also has an external connection port 2104, which allows direct data exchange with other information terminals via a connector. Charging can also be performed via the external connection port 2104. Charging may also be performed by wireless power supply without using the external connection port 2104.

[0434] The mobile phone 2100 preferably has a sensor, such as a fingerprint sensor, a pulse sensor, a body temperature sensor, or other human body sensor, a touch sensor, a pressure sensor, an acceleration sensor, or the like.

[0435] FIG. 25B illustrates an unmanned aerial vehicle 2300 having multiple rotors 2302. The unmanned aerial vehicle 2300 is sometimes called a drone. The unmanned aerial vehicle 2300 includes a power storage system 2301 of one embodiment of the present invention, a camera 2303, and an antenna (not shown). The unmanned aerial vehicle 2300 can be remotely controlled via the antenna. The power storage system of one embodiment of the present invention is highly safe and can be used safely for a long period of time, making it suitable as a secondary battery to be mounted on the unmanned aerial vehicle 2300.

[0436] 25C , a power storage system 2602 of one embodiment of the present invention may be mounted on a hybrid vehicle (HV), an electric vehicle (EV), a plug-in hybrid vehicle (PHV), or other electronic devices. The power storage system 2602 includes a plurality of secondary batteries 2601.

[0437] FIG. 25D illustrates an example of a vehicle equipped with a power storage system 2602. The vehicle 2603 is an electric vehicle using an electric motor as a power source for running. Alternatively, the vehicle 2603 is a hybrid vehicle that can appropriately select and use an electric motor or an engine as a power source for running. The vehicle 2603 using an electric motor includes multiple ECUs (Electronic Control Units), and the ECUs perform engine control and the like. The ECUs include a microcomputer. The ECUs are connected to a Controller Area Network (CAN) provided in the electric vehicle. CAN is one of the serial communication standards used for an in-vehicle LAN. By using the power storage system of one embodiment of the present invention as a power source for the ECU, a highly safe vehicle with a long cruising range can be realized.

[0438] The power storage system can not only drive an electric motor (not shown) but also supply power to one or more light-emitting devices such as headlights and room lights, etc. The power storage system can also supply power to display devices and semiconductor devices such as a speedometer, a tachometer, and a navigation system included in the vehicle 2603.

[0439] The vehicle 2603 can charge the secondary battery 2601 of the power storage system 2602 by receiving power supply from an external charging facility by a plug-in method, a contactless power supply method, or the like.

[0440] FIG. 25E shows a state in which a vehicle 2603 is being charged via a cable from a ground-mounted charging device 2604. Charging may be performed using a predetermined charging method and connector specifications, such as CHAdeMO (registered trademark) or Combo, as appropriate. For example, plug-in technology can be used to charge the power storage system 2602 mounted on the vehicle 2603 using external power supply. Charging can be performed by converting AC power to DC power via a converter such as an AC-DC converter. The charging device 2604 may be installed in a home as shown in FIG. 25E, or may be a charging station installed in a commercial facility.

[0441] Although not shown, a power receiving device can be mounted on a vehicle and power can be supplied contactlessly from a ground power transmitting device to charge the vehicle. In the case of this contactless power supply method, by incorporating a power transmitting device into a 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 vehicles. Furthermore, a solar cell can be installed on the exterior of the vehicle to charge the secondary battery while the vehicle is stopped or moving. Electromagnetic induction and magnetic resonance methods can be used for such contactless power supply.

[0442] Next, an example of a power storage system of one embodiment of the present invention will be described with reference to FIGS. 26A and 26B.

[0443] 26A includes a power storage system 2612 including a control circuit of one embodiment of the present invention and a secondary battery, and a solar panel 2610. The power storage system 2612 is electrically connected to the solar panel 2610 via wiring 2611 or the like. The power storage system 2612 may 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 system 2612. The power stored in the power storage system 2612 can be charged to the power storage system 2602 of the vehicle 2603 via the charging device 2604. The power storage system 2612 is preferably installed in an underfloor space. By installing the power storage system 2612 in the underfloor space, the space above the floor can be effectively utilized. Alternatively, the power storage system 2612 may be installed on the floor.

[0444] The power stored in the power storage system 2612 can also 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 system 2612 of one embodiment of the present invention can be used as an uninterruptible power supply, enabling the use of electronic devices.

[0445] 26B illustrates an example of a power storage system according to one embodiment of the present invention. As illustrated in FIG. 26B, a power storage system 791 according to one embodiment of the present invention is installed in an underfloor space 796 of a building 799.

[0446] The power storage system 791 is equipped with a control device 790, which is electrically connected to a distribution board 703, a power storage controller 705 (also referred to as a control device), a display 706, and a router 709 by wiring.

[0447] Electric power is sent from commercial power source 701 to distribution board 703 via service line attachment portion 710. Electric power is also sent to distribution board 703 from power storage system 791 and commercial power source 701, and distribution board 703 supplies the sent electric power to general load 707 and power storage load 708 via outlets (not shown).

[0448] The general load 707 is, for example, an electrical appliance such as a television or a personal computer, and the power storage load 708 is, for example, an electrical appliance such as a microwave oven, a refrigerator, or an air conditioner.

[0449] The power storage controller 705 has a measurement unit 711, a prediction unit 712, and a planning unit 713. The measurement unit 711 has a function of measuring the amount of power consumed by the general load 707 and the power storage load 708 during one day (for example, from midnight to midnight). The measurement unit 711 may also have a function of measuring the amount of power of the power storage system 791 and the amount of power supplied from the commercial power source 701. The prediction unit 712 has a function of predicting the amount of power demand to be consumed by the general load 707 and the power storage load 708 during the next day, based on the amount of power consumed by the general load 707 and the power storage load 708 during the previous day. The planning unit 713 has a function of making a plan for charging and discharging the power storage system 791, based on the amount of power demand predicted by the prediction unit 712.

[0450] The amount of power consumed by the general load 707 and the power storage load 708 measured by the measurement unit 711 can be confirmed on the display 706. It can also be confirmed on electrical appliances such as televisions and personal computers via the router 709. It can also be confirmed on portable electronic devices such as smartphones and tablets via the router 709. The amount of power demand for each time period (or each hour) predicted by the prediction unit 712 can also be confirmed on the display 706, the electrical appliances, and the portable electronic devices.

[0451] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0452] (Notes regarding the present specification) The above-described embodiments and the respective components in the embodiments will be described below with additional notes.

[0453] The configurations shown in each embodiment can be combined with the configurations shown in other embodiments as appropriate to form one aspect of the present invention. Furthermore, when multiple configuration examples are shown in one embodiment, the configuration examples can be combined as appropriate.

[0454] In addition, the content (or even a part of the content) described in one embodiment can be applied to, combined with, or replaced with another content (or even a part of the content) described in that embodiment, and / or with the content (or even a part of the content) described in one or more other embodiments.

[0455] The contents described in the embodiments refer to the contents described in each embodiment using various figures or the contents described using text in the specification.

[0456] Furthermore, a figure (or even a part thereof) described in one embodiment can be combined with another part of that figure, another figure (or even a part thereof) described in that embodiment, and / or a figure (or even a part thereof) described in one or more other embodiments to form even more figures.

[0457] In addition, in the present specification and the like, in the block diagrams, components are classified by function and shown as independent blocks. However, in actual circuits, etc., it is difficult to separate components by function, and there may be cases where one circuit is involved in multiple functions, or where one function is involved across multiple circuits. Therefore, the blocks in the block diagrams are not limited to the components described in the specification, but may be rephrased appropriately depending on the situation.

[0458] In addition, in the drawings, the size, layer thickness, or region is shown at an arbitrary size for convenience of explanation. Therefore, it is not necessarily limited to the scale. Note that the drawings are shown schematically for clarity, and are not limited to the shapes or values ​​shown in the drawings. For example, it is possible to include variations in signal, voltage, or current due to noise, or variations in signal, voltage, or current due to timing deviations.

[0459] In this specification and the like, when describing the connection relationship of a transistor, the term "one of the source or drain" (or first electrode or first terminal) is used, and the other of the source and drain is referred to as "the other of the source or drain" (or second electrode or second terminal). This is because the source and drain of a transistor vary depending on the structure or operating conditions of the transistor. Note that the names of the source and drain of a transistor can be appropriately changed to source (drain) terminal, source (drain) electrode, etc. depending on the situation.

[0460] Furthermore, the terms "electrode" and "wiring" used in this specification and elsewhere do not limit the functionality of these components. For example, an "electrode" may be used as part of a "wiring," and vice versa. Furthermore, the terms "electrode" and "wiring" also include cases where multiple "electrodes" and "wirings" are integrally formed.

[0461] Furthermore, in this specification and the like, the terms voltage and potential can be interchanged as appropriate. Voltage refers to the potential difference from a reference potential. For example, if the reference potential is the ground voltage, voltage can be interchanged with potential. Ground potential does not necessarily mean 0 V. Note that potential is relative, and the potential applied to wiring, etc. may change depending on the reference potential.

[0462] In this specification and the like, terms such as "film" and "layer" can be interchangeable depending on the circumstances. For example, the term "conductive layer" can be changed to the term "conductive film." Or, for example, the term "insulating film" can be changed to the term "insulating layer."

[0463] In this specification, a switch refers to a device that has a function of being in a conductive state (on state) or a non-conductive state (off state) and controlling whether or not a current flows. Alternatively, a switch refers to a device that has a function of switching a path through which a current flows.

[0464] In this specification, the channel length refers to, for example, a region where a semiconductor (or a portion in the semiconductor through which current flows when the transistor is on) and a gate overlap in a top view of a transistor, or a distance between a source and a drain in a region where a channel is formed.

[0465] In this specification and the like, the channel width refers to, for example, the length of the region where the semiconductor (or the portion in the semiconductor through which current flows when the transistor is on) and the gate electrode overlap, or the length of the portion where the source and drain face each other in the region where the channel is formed.

[0466] In this specification, "A and B are connected" includes not only a direct connection between A and B, but also an electrical connection between A and B. Here, "A and B are electrically connected" means that when an object having some kind of electrical effect exists between A and B, it enables the exchange of electrical signals between A and B. [Explanation of symbols]

[0467] 10: Capacitor, 11: Transistor, 51: Curve, 52: Curve, 99: Switch, 99_1: Switch, 99_2: Switch, 99_3: Switch, 110: Conductor, 111: Battery pack, 113_1: Comparator, 113_2: Comparator, 113_3: Comparator, 113_4: Comparator, 113_5: Comparator, 120a: Lower electrode, 120b: Upper electrode, 121: Control unit, 122: Voltage generation unit, 127: Detection unit, 128: Detection unit, 130: Insulator, 131: Switch, 140: Charger, 141: Switch, 150A: Power transistor transistor, 150B: power transistor, 152a: insulator, 152b: insulator, 155: insulator, 190: power storage system, 191: control circuit, 192: secondary battery, 193: load, 210: insulator, 286: insulator, 287: insulator, 311: substrate, 313: semiconductor region, 314a: low resistance region, 314b: low resistance region, 315: insulator, 316: conductor, 320: insulator, 322: insulator, 324: insulator, 326: insulator, 328: conductor, 330: conductor, 350: insulator, 352: insulator, 354: insulator, 356: conductor, 357: conductor, 4 00: secondary battery, 401: positive electrode cap, 413: conductive plate, 414: conductive plate, 415: power storage system, 416: wiring, 420: control circuit, 421: wiring, 422: wiring, 423: wiring, 424: conductor, 425: insulator, 426: wiring, 501: circuit board, 509: label, 511: terminal, 513: secondary battery, 515: seal, 517: antenna, 519: layer, 531: secondary battery pack, 551: one of positive electrode lead and negative electrode lead, 552: the other of positive electrode lead and negative electrode lead, 590: control circuit, 590a: circuit system, 590b: circuit system, 60 1: positive electrode cap, 602: battery can, 603: positive electrode terminal, 604: positive electrode, 605: separator, 606: negative electrode, 607: negative electrode terminal, 608: insulating plate, 609: insulating plate, 611: PTC element, 613: safety valve mechanism, 701: commercial power supply, 703: distribution board, 705: energy storage controller, 706: display, 707: general load, 708: energy storage system load, 709: router, 710: service line attachment part, 711: measurement part, 712: prediction part, 713: planning part, 790: control device, 791: energy storage system, 796: underfloor space part, 799: building, 911a: terminal, 911b: terminal,913: secondary battery, 930: housing, 931: negative electrode, 931a: negative electrode active material layer, 932: positive electrode, 932a: positive electrode active material layer, 933: separator, 950a: wound body, 951: terminal, 952: terminal, 1201: chip, 1202: bump, 1203: printed circuit board, 1213: analog calculation unit, 1221: DRAM, 1222: FeRAM, 1223: integrated circuit, 1225: chip, 2100: mobile phone, 2101: housing, 2102: display unit, 2103: operation button, 2104: external connection port, 2105: speaker, 2106: microphone, 2107: power storage System, 2300: unmanned aerial vehicle, 2301: power storage system, 2302: rotor, 2303: camera, 2601: secondary battery, 2602: power storage system, 2603: vehicle, 2604: charging device, 2610: solar panel, 2611: wiring, 2612: power storage system, 7000: robot, 7100: portable display device, 7101: housing, 7102: display unit, 7103: operation button, 7104: storage battery, 7120: flying object, 7140: cleaning robot, 7160: electric vehicle, 7200: portable information terminal, 7201: housing, 7202: display unit, 7203: band , 7204: Buckle, 7205: Operation button, 7206: Input / output terminal, 7207: Icon, 7210: Smartphone, 7220: PC, 7240: Game console, 7260: Game console, 7262: Controller, 7400: Mobile phone, 7401: Housing, 7402: Display unit, 7403: Operation button, 7404: External connection port, 7405: Speaker, 7406: Microphone, 7407: Storage battery, 7408: Control circuit, 8000: Display device, 8001: Housing, 8002: Display unit, 8003: Speaker unit, 8004: Secondary battery, 8005: Voice input device, 8007: speaker, 8008: display unit, 8009: mobile information terminal, 8010: charging module, 8021: charging device, 8022: cable, 8024: power storage system, 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, 8400: automobile,8401: headlight, 8406: electric motor, 8500: automobile, 8600: scooter, 8601: side mirror, 8602: power storage system, 8603: turn signal light, 8604: under-seat storage, 8700: electric bicycle, 8701: storage battery, 8702: power storage system, 8703: display unit, 8704: control circuit, 9600: tablet terminal, 9601: notebook personal computer, 9625: switch, 9626: switch, 9627: power switch, 9628: operation switch, 9629: fastener, 9630: housing, 9630a: housing, 9630b: housing, 9631: display unit, 9633: solar cell, 9634: control circuit, 9635: power storage unit, 9640: moving part, 9650: keyboard unit,

Claims

[Claim 1] a first terminal electrically connected to the positive electrode of the secondary battery; a second terminal electrically connected to the negative electrode of the secondary battery; a third terminal electrically connected to a gate of a power transistor that controls an electrical connection between the secondary battery and a charger or a load; a detection unit electrically connected to the first terminal and the second terminal; a control unit electrically connected to the detection unit; a control circuit having a memory circuit electrically connected to the control unit, The memory circuit includes a memory cell having a ferroelectric layer between a pair of electrodes, a transistor electrically connected to the memory cell, and a decoder to which a signal from the memory cell is output. the detection unit has a resistance circuit whose resistance is adjusted based on the data stored in the memory circuit, The control unit has a function of determining that the secondary battery is overcharged based on a comparison result between a reference potential input from the detection unit and the potential of the first terminal or the potential of the second terminal, and a function of outputting a signal to the third terminal to turn off the power transistor when it is determined that the secondary battery is overcharged.

Images